ENVIRONMENTAL ASSESSMENT
OF Public Disclosure Authorized MUNICIPALITIES OF SPLIT/SOLIN, KA§TELA/TROGIR WASTE WATER DISPOSAL INFRASTRUCTURE PROJECT
DRAFT £223 Public Disclosure Authorized
SOLIN Public Disclosure Authorized Public Disclosure Authorized
Split,October 199. y!ZRI THE%0w".'kWoNJNTY OF IA" j Ml ij .12 4 SPLITAND DALMATIA
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01 ENVIRONMENTAL ASSESSMENT
OF
MUNICIPALITIES OF SPLIT/SOLIN, KASTELAITROGIR WASTE WATER DISPOSAL INFRASTRUCTURE PROJECT
DRAFT
prepared by:
Jure Margeta, Ph.D.
Ante Baric, Ph.D. CONTENTS:
PREFACE ...... ;.iv IATRODUC7TTON ...... - :.v OBJECI7VES OF THE STUDY . . v 1. DESCRIPTION OF THE PROPOSED PROJECT .. 1.1. INTRODUC1ION .. 1.2. EXISTINGSTATE OF SEWERAGESYSTEM., ...... ,.,,...... 4 1.3. WASTEWATER...... , ,, ... 8 1.4. THE SEWERAGESYSTEM SOLUTION - CONCEPT . .17 1.4.1 -Methologyof solution selection ...... ,, ,...... 17 1.4.2. Sewerage system concept ...... 17 1.4.3. The Split - Solin sewerage system ...... 18 1.4,3.1. Treatment plant and submarine outfall ...... 18 1.4.3.2. Sewerage system of Split and Solin...... I ...... 26 1.4.3.3. Characteristics of the wastewater treatment plant site .. 29 1.4.4. The Kastela - Trogir sewerage system . .35 1.4.4.1. Treatment plant and submarine outfall ...... ,, 35 1.4.4.2. Sewerage system of Katela ...... , . 40 1,4.4.3. Sewerage system of Trogir ...... I... 42 1.4.4.4. Hydrotechnical tunnel !iovo . . 44 1.4.4.5. Characteristics of the wastewater treatment plant site .. 44 1 4.5. Phases in the construction of the sewveragesystems. . 48 1.5. I\TEGRATED ENVIRONMENTALPROJECT - KAX-TEIABAY.. 3 1.6. MANAGEMENTAND STAFFING . .58 2. DESCRIPTION OF THE ENVIRONMENT 59 2.1. PHYSICALENVIRONMENT ...... : 59 2.1.1. Geology. 9 2.1.2. Soils .. 62 2.1.3. Hydrology ...... , 64 2.1.4. Climate conditions .. 65 2.1.5. Oceanography .. 69 2.2. BIOLOGICALENVIRONMENT ...... ; 81 2.2.1. Terrestrial vegetation .. 81 2.2.2. Marine biology .. 83 2.2.3. Fisheries, places of special interest for spawing and nursery grounds of conmmercialimportant species 86 2.2.4. Rare or endangered species and sensitive habitats .86 2.2.5. Quality of receiving waters. 86 2.2.6. Sanitary quality of marine coastal waters and die-off rate of faecal bacteria94 2.3. ASSIMILATIVECAPACITY OF RECEIVINGWATERS .96 2.4. SOCIOCULTURALEN-VIRONMENT .99 2.4.1. Present and projected population .99 2.4.2. Present and planned land use .99 3. LEGISLATIVE AND REGULATORY CONSIDERATIONS ...... 101 3.1. NATIONALLEGISLAT E ...... 101 3.2. INTERNATIONALAGREEMENTS ...... 105 3.3. EU DIRECIVES...... 16 4. DETERMINATION OF THE POTENTIAL IMPACT OF THE PROPOSED PROJECT COMPONENTS ...... 108 4.1. IMPACTSDURING CONSTRUCTION ...... 112 4.1.1. Collectingsystem, treatment plants and turnels ...... 112 4.1.2 Submarineoutfalls ...... 113 4.2. IMPACTSDURING THE USE...... _ 115 4.2.1. Impactsof the sewerage system and the wastewater treatment plants... 115 4.2.2. Impactsof the submarine outfalls ...... 118 4.2.3. Overflows...... 121 4.2.4. Turnels ...... 122 5. ANALYSIS OF THE ALTERNATIVESOF THE P3ROPOSED PROJECT. 123 5.1. ANALYSESAND ALTERNTATIVSOLLMONTS OFTHE MAINCONCEPT ...... 123 5.2. ANALYSESAND A1TERNATIVESOLUTIONS FOR THE PLANTLOCATION ... 128 5.3. ANALYSESAN7D ALTERNAnVE SOLUTIONS FOR THE WASTE WATER DISPOSAL...... ; : 131 5.4. ALTERNATIVESOLLTIONS FOR THE TREATMENTPLANTS TECHNOLOGY 135 5.5. ANALYSESAND ALTERNATIVESOLUTIONS FOR SUBMARINE Ot-rFALLS. .136 6. PROPOSED MEASURES TO PREVENT, REDUCE OR MITIGATE THE ADVERSE EFFECTS OF THE PLANNED WASTEWATER DISCHARGE SYSTEM...... 139 6.1. STRATEGICPREREQUISI FORTHE PROTECION OF ATELA AIND TROGIR BAY AND BRA,-AND SPLITCHANNEL AGAINST POLLLMOIN FROM LA-NDBASED SOURCESAND ACTIITIES ...... 139 6.2. SPECIFICMEASURES PROPOSED TO PREVENT,REDUCED OR MITIGATEDTHE NEGATIVEEFFECTS OF THE PLANEDSEWERAGrE SYSTEM ...... 142 6.2.1. Legal and administrative measures during the construction ...... 142 6.2.2. The collecting system ...... 142 6.2.2.1. Measures during design and construction ...... :142...... 1 6.2.2.2. Measures during operation .144 6.2.3. Treatment plants ...... ; 144 6.2.4. The submarine outfalls ...... 146 6.2.4.1. General ...... 146 6.2.4.2. Measures that should be undertaken during the construction of submarine outfalls ...... 146 6.2.4.3. Measures that should be undertaken during the operation of submarine outfalls ...... 147 6.2.5. Tunnel ...... 147 6.2.6. Organization and management ...... 147 6.2.7. Other measures and studies ...... 148
ii 7. PROPOSED RESEARCH AND MONITORING PROGRAMME ...... 149 7.1. JUSTIFICATINFOR THE PROGRAMME...... 149 7.2. AIMSOF THE PROGRAMME...... 150 7.3. OUTLINEOF THE RESEARCHPROGRAMME ...... 151 7.4. OUTLINEOF THE MONITORINGPROGRAMME ...... 153 7.5. COMPUTER-BASEDDECISION SUPPORT SYSTEMFOR COASTALWATER RESOURCESMANAGEMENT ...... 158 8. ESTIMATION COST FOR CONSTRUCTION, RESERACH, MONITORING, TRAINING AND MAINTENANCE EQUIPMENT ...... 160
9. PUBLIC HEARING ...... 161
LITERATURE ...... 166
iii :
\ PREFACE
This documentwas prepared in the accordance with Contract made on the one hand, "Hrvatskevode" as the Client and, on the other hand the Consultants.Document have been prepared in accordance with terms of referenceprepared by World Bank. The Client, according to the provisions of Contract, provided all available documentationto the Consultant. The assessment of environmental impacts was made using the available data, an estimation based on the most likely conditions prevailing at the project area and based on similar predictions at other areas previously evaluated by the Consultants.
iv INTRODUCTION
At the request of the Croatian Government, the World Bank and the European Bank for Reconstruction and Development, in close cooperation with HBOR, are developing the project "Municipal Environmental InfrastructureInvestment Program". The nature and size of the investmentpart of the project, as well as its potential environmental impacts require, according to the Croatian environmental regulations and those of the participating banks, to carrying out of an environmentalassessment. The project has been ranked as category "A" for the purpose of the World Bank Operational Directive O.D. 4.01, which means that a full environmental assessment study is required before banks can approve the project for its financing. The study area for the assessment consists of the drainage area to be serviced by the wastewater collection system; the tracts of land on which effluent to be applied in reuse systems; marine and estuarine waters which could be influenced by effluent discharge; remote sites identified for disposal of solid waste generated in the treatment process, and watershedwhich might be affected.
OBJECTIVES OF THE STUDY
The environmentalassessment study is being developed to: (i) assess potential environmental consequences of the potential project alternatives; (ii) help guide the design of the proposed project's alternative to minimize any potential negative environmental impacts which might occur during construction and operation, and (iii) to formulate recommendations concerning measures that should be undertaken in order to maintain conditions for the protection of the marine enviromnent in the area. This study with its recommendationswill be the basis for applying for an environmentalpermit from the regionalauthorities.
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: v - 1. DESCRIPTION OF THE PROPOSED PROJECT
1.1. INTRODUCTION This study deals with the wider area of the Kastela Bay that covers the municipalities of Split, Solin, Kastela and Trogir. This region represents a unique economic and territorial complex whose segments are closely bound to each other and to the city of Split as a dominating center which is why it is referred to as the region of Split. This region is situated in the central part of the Croatian littoral and the entire region belongs to the County of Split and Dalmatia (Fig. 1.1.). The city of Split is the main center of the wider area of the Kastela Bay and also the capital of the mentioned County. Within the system of industrial centres within the Republic of Croatia Split is referred to as a category 2 centre while within the system of tourist activities it bears a category I title. In the year of 1981 the region of Split had a population of 466.567. The estimated population until 2015 is approx. 530.000. In 1991 Split, Solin, Kastela and Trogir had a population of 266.118, and the estimated population in 2015 is 355.000. This region covers an area of approx. 14.500 hectares. It has been known for a rather long time that the area of Kastela Bay has been one of the most polluted areas in the Adriatic. It has also been known that efforts have been made in trying to solve this problem. The problem, however occurred as a result of intensive construction and industrialization on a rather small area. Within all this, through a long period of time, the basic municipal infrastucture - sewerage system was omitted. Therefore, the solution to this problem cannot be expected so soon. This problem has become wider by scope, more complex in the technical way, and too heavy economically which are the reasons why it cannot be solved quickly and easily. The region of Split that covers towns such as Solin, Kastela and Trogir greatly developed and became urbanized in the post-war period. In the last forty years the population grew three times as much so that in 1953 it had about 109.000 inhabitants, presently about 300.000. Along with the increase of population, industry, traffic and trade developed as well. Split is the largest traffic, industrial, commercial and administrative centre of Dalmatia with a strong tendency of growing in the future. Unfortunately, town planning, construction and particularly industry was directed onto the area of Kastela Bay (Fig. 1 1.) so that this rather small surface with restricted capacities is already greatly devastated and polluted. Throughout this period, the intensive construction of residential and industrial buildings was not in relation to the construction of the sewerage infrastructure. As a result of this a greater part of this region does not have a unique and complete sewerage system. The area of Trogir, Kastela and Solin has no sewerage system so that the greatest part of wastewater is collected in septic tanks. The wastewater is either directly or indirectly without treatment drained into the coastal sea. Regarding the sewerage system the area of the city of Split enjoys a somewhat better situation, but even here all the wastewater is either directly or indirectly drained into the coastal sea. I .0 As
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1:5WOO( WWE W3W 24 20 30 t.. Wwa w4k .4110 m or. 6 Such level of urban construction, concentration of traffic and industry adds to the pollution of air, land and particularly the sea as a recipient of the entire pollution of the corresponding catchment area. The unexacting necessary infrastructure increases the dangerous environmental impact up to a level where the environment could affect future development or even cause regression.of the achieved level of development It can be said of the wider area of Split that is facing an ecological crisis, because it is experiencing all levels of development and crisis impact, from pollution over negative impact to destruction. Certain environmental elements can still bear this while others are affected to such an extent that their ability to cope is reduced. Unfortunately there are also environmental elements that are destroyed to such extent that they cannot be restored. Year after year, this situation causes an increasing quantity of destroyed natural environment, simultaneously reducing the unaffected elements. It is entirely up to the inhabitants of this area whether this trend will continue in the future, and it is up to them to stop this negative trend of environmental pollution. One of the main prerequisites for solving this problem is the construction of a sewerage system, a treatment plant and wastewater disposal plant The topic is very complex, and the ways of solving it are rather hard and confusing. The study brings a description of the solution to the problem, a long-term concept of the sewerage system of the wider area of the Kastela Bay, phases of its construction as well as part of the system whose construction will be financed by the World Bank and the European Bank for Reconstruction and Development.
3 12. EXISTING STATE OF SEWERAGE SYSTEM In the studied area, the greatest part of the sewerage system was built only in Split, and approx. 70% of the population is connected onto the sewerage. Speaking in tenns of surface, only 55% of the urban area of Split has its sewerage system. The total length of the sewerage system of Split is approx. 202 km. The sewerage system in Solin,, Kastela and Trogir was partly constructed, i.e. the part in the town nucleus. Approximately 25% of the population is connected onto the sewerage system. The total length of the Solin sewerage system is approx. 13 km, Kastela - 31 kn and Trogir - 16 km. Other buildings bave their septic tanks. Neither the entire -area nor these towns individually have a umique sewerage system. Not even Split. The existing sewerage system was built mostly in the city nucleus, and as the city grew larger the sewerage system grew accordingly. However, the system did not increase as a unique sewerage system. It may rather be considered as separate subsystems that accumulate wastewater on a smaller area i drain it where the wastewater is drained inltothe coastal sea. Because of this, the area has more than several hundred of separate outfalls into the sea (Fig. 1.2). This practically means that this area has no wastewater treatment, plants, neither partly mechanical ones. Of all the outfalls that were built in accordance with the professional standards, those that should be mentioned are: the Podstrana outfall, the Lav Hoitel outfall, the Split airport outfall and the Medena Hotel outfall. The largest outfall in Split is the one at Katalinid&brig which has not been in use in the past few years due to the malfunctioningyof the pump station. The southern part of Split, i.e. the wider area of Bacvice is connected onto this outfall. In accordance with the aforementioned it may be concluded that Split has an incomplete sewerage system while other towns practically have none at all The sewerage system of Split is mostly a combined-type system, while only the segment built in the past ten years was built as a separate one (Fig. 1.3.). The sewerage system of Split is as old as the city itself, i.e. built before 1700 years. In the Diocletian Palace there is a unique sewerage system that remained very well preserved until the present. Presently, works are carried out so that it will be able to function properly. The sewerage system was built as the city grew larger, so that the city nucleus bears remains of cross-sections of the sewerage system, although it was not until the period between the wars that greater sewers were built The city saw its most intense development in the post-war years so that it may be said that a more serious construction of the sewerage system did not begin until then. Unfortunately, due to short-term economic interests and an incorrect approach to the assessment of the capacity of the coastl sea, a combined-type sewerage system was foreseen. This was common practice in the Mediterranean that foresaw outfall of part of the wastewater into the sea by means of long submarine outfalls and only partial mechanical treatment. The result of such practice was a concentration of all wastewater and rainwater in the centre of the city, i.e. at Katalini6a brig, where the mechanical plant and outfall was foreseen and where the first phase of the outfall was built All overflow water was supposed to be drained into the coastal sea, the greater part of which (approx. 60%) into the Split port, which makes 80% of'the entire annual pollution.
4 KCASTELANSKIZALJEVDumva ~ W kAtTELA BAY
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Fig. 1.2. Submarine outfalls of the existing sewerage system ft__ KASTELA
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Fig. 1.3. Existing seweragesystem of SpiItISolin 6 In accordance with the aforementioned and also with the topographic characteristics of the region, presently all the wastewater of the southern part of Split and partly the northern part is concentrated in the city port where it is drained into the sea in the area of Vranjic. This has the greatest affect on regular mortality of fisb during the summer. As the planned sewerage system did not foresee any plants (except partly mechanical ones) the area near the outfalls became urbanized so that there are is no way of erecting any quality wastewater treatment plant in theses areas. Altogether this led to a very complicated situation regarding the sewerage system, treatment plant and submarine outfalls that should be solved on a long-term basis. The present situation could be solved in a much easier way in Solin, Kastela and Trogir because a separate system was partly built and because the sewerage system was not built yet. The newly constructed one would therefore be much easier to design and it would also be less restricted by the existing systern. Due to the situation that occurred in the past few years, sewerage systems were built very intensively. Presently under construction are: a) the one on the area of the city of Split; the main sewer in the city port, the corresponding treatment plant (mechanical) and pump station, and a connection onto the existing submarine outfall as well as the reconstruction of the existing sewerage system on that area. b) the one on the area of the town of Solin; the main pump station Solin with corresponding transmission mains bearing in mind that part of the main system has already been built. c) the one on the area of the town of Kastela; the sewerage system and pump station of the first phase of the sewerage system that covers K. Sucurac and K. Gomilica.
As result of such situation a big quantities of pollutant have been discharged in to Kastela bay directly from sewerage system or indirectly by hydrological cycle or local water resources. In accordance with result of the study /3/ total biological oxygen demand load and suspended solids load of the Kaktela bay was:
SOURCE (tlyear) BOD5 SOLIDSED
Domestic water 2226.0 2431.0 _ Industry 1562.0 954.0 Storm water 984.0 4920.0 Air deposit _ _ _ Underground water 206.6 88.6 Surface runoff 27.2 87.4 Rivers 387.9 1419.1 TOTAL 5394.0 9900.1
7 1.3. WASTEWATER According to the last census in 1991, the population was 266.118 while the long-term estimated population is 381.000. Table 1.1 brings the situation and plans according to specific cities. Table i.1. Population and tourists in SpUt,Solin, Kaitela and ITrogr
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~~~ C C CI N C I,.. ~ ~ ~ Figures for the year of 2000 and up are given on the basis of the trend from the past, while figures for the year of 2015 are taken from revised urban plans of certain towns. The total water consumption on this area is given in Table 1.2., while facts on certain industries and consumers are given in Tsble 1.3. Quantity of the wastewater is about 70-80 % of domestic water consumption. Quantity of industial wastewater vary depend on industry type. Estimation for 1995 on the bases of study /24/ and other data results in overall a flow of around 10600 m31day. Only part of this quantities will be collected by sewerage system, about 8500 m3/day, because part of it will be lost (shipyard, cement industry, construction industry, etc.). Table 1.2 Water consumption and forecast of water consumption (averageflow in max. day in Vs)
Net water Total Water Year Population Tourism Industry Agriculture Public fac. demands demands losses (Us) (Vs) (Us) (I/s) (OIs) (/s) (Us) (%) 1991 825 53 864 154 26 1923 2634 27 1995 808 61 833 146 37 1886- 2583 27 2000 926 88 467 157 39 1677 2266 26 2005 999 100 467 160 41 1768 2326 24 2010 1088 115 489 160 44 1896 2431 22 2015 1191 132 515 160 46 2044 2555 20 2020 1272 150 539 160 49 2170 2679 19 2025 1347 167 563 160 51 2289 2791 18
Total water demands - SPLIT, SOLIN, KASTELA, TROGIR maximum day (1ls)
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9 In the past few years, on the area of Split, the quality of wastewater has been measured and the results of last years results are given in Table l.4. Since this is,a combined-type sewerage system the intensity of wastewater varies greatly and is affected by rainwater and infiltration water in the system. Therefore, all level of pollution and the quantity of specific- materials that- are introduced into the environment are calculated on the basis of expected production of waste material and not on the basis of the concentration in wastewater.- Within the systen of industrial centres within the Republic of Croatia Split and his region is refefred to as a category 2 centre. Industry of the Split region is mostly located in the norther part of the community around north part of the Kastela bay (Vranjic basin). This region around nort port in Kastela bay is industrial zone -of the comunity Split, Solin and Kaitela. In this area we have general port, oil port, railway, Split shipyard, Vranjic shipworks, and most of industry. In the Trogir area the most significant industry is shipyard located in the Trogir bay. The region of the Kaitela bay -accommodates-a while -variety of industry. Some of them has strong organic wastewaters and high flow like several food and drink processing plants, including a large brewer, a winery, two soft drink plants, dairy and one big and several small slaughter house. This industry bighly contribute to potlution of the Kastela bay because all of this industry have been discharged wastewaters into easten part of the bay. Other industry are: metal finishing, metal construction, chemical processing, PVC factory, shipyard and shipworks, machinery production, building industry and other typical industry associated with urbanized area. Table 1.5. brings figures on quality of industrial wastewater in accodance with a survey of industrial discharges carried out during 1990 /24/. Some of industries had appropriate wastewater treatment plant. However, due to current industrial restuctriation processes. economical fluctuations, bankrupcy and liquidation of certain industries and the development of new ones, these figures are given rather as a reference and apply to industry that is foreseen to exist in the following period. Most of big industry not operate in fall capacity or not operate at all. In same time small industry have been establishing. Existing states of industrial wastewaters, treatment plants and other characteristics are not known and appropriate study have to be developed in the next stage of the project. Most of these industry from Split and Solin will significantly contribute both flow and strength organic waste water which will be biodegraded in the treatment plant, especially food and drinling processing plants. Organic load from such industry have been estimated about 89000 equivalent people. Discharges from other industry like chemical processing and metal finishing may contain materials dangerous for treatment processes or pass through treatment works and polluted the sea water at the outfall. As it is presented in table 1.3. industrial water consumption in community Split drop from 13.262.000 in 1987 to 10.707.000 in 1995. and will continue to decline as was projected to 5.874.000 in 2010 year. Major reason for this is better water economy with industrial works. Information about present condition is not available because changes are frequent and considerable. For example, the largest industrial plants of INk-Vinil and Adriachem in Kstel Sucurac with around 1500 employees haven't been operating for 4 months. Frequent and considerable changes can be expected during following few years. After that period stabilization and the end of restructuring of industry can be expected. Therefore it is necessary to prepare and
10 conduct the program to analyze industry, circumstances and needs in reference to protection of environment and wastewater treatment plant. Because of the circumstances it is not recommended to haste with planning of secondary treatment plant because input data is subjected to frequent changes. In order to protect the sewerage system and wastewater purification plant Directive /25/ (Chapter 2) on Trade Effluent Discharge Standards for sewerage system in communities Split, Solin and Kastela was issued. Today the majority of industrial wastewaters have been discharged into Kastela bay because of its position along the coastline. Planned sewerage system will deliver industrial wastewater to wastewater treatment plant and then discharge it into Brac Channel. During the initial phase of the treatment plant development removal of solids and suspended materials will be limited. Therefore the majority of wastewater will be discharged into sea water of Brac ChanneL In order to protect Brac Channell the Trade Effluent Discharge Standards should be strictly carried out and strict trade effluent monitoring controls instituted. It is also necessary to begin the process of greening of industry. Study carried out in 1990. /24/ involving industry that existed in that period established measures that industry had to take (treatment level) in accordance with the Trade Effluent Discharge Standards in order to be connected to the sewerage system of Split/Solin area. Same measures are still valid for industry that exists today and should be strictly carried out Similar study hasn't been carried out for Kakela and Trogir area. However industry is not well spread in this area or its influence on urban wastewater characteristics is insignificant (e.g. shipyard in Trogir, cement factory in Kastel Su6urac etc.). The only factories that, if working, will have significant influence on quality of urban wastewater of the Kaktela sewerage system are INA Vinil and Adriachem situated in Kastel Sucurac.
11 Table 1.3. Water consumption according to sectors and consumers (Ribarevie)
MIVI0A1I 3)01111( W16A0IA10.(01301411 I 1I AN(AX 11100 1130161MI1) (twits) I 100 MR/1 Mil0 I-in'? I-PHI 109 IMA) 1993 '99l I')l., PON. IAl .I'AOII 191P) '/0111 20o1 A00, AN01: AIDS. 20, 2061, 701)0 "W6 M1 2010 2.011 ...... P...... I..... ( ... I...... I.....I..... K...... t ...... i ...... it...... I o...... I.... M .... m.....AC.
I. 36811(330K.5 (Pt688.IC FAC11I.IIirS) OH063 630 462 622 MD0 621 *01 440 414 631 611. Me1 660 660 116 668 660 660 650 660 60 660 660 6611 660 660 660 7. I)3O.30('600ED0(00GR0.10J11I1) HO0K3 1.056 1.036 1. 44 1.220 091 919 1. 61 1.190 lORI) 9020 1.60)) 1.000 966 90H Wu) 90 HO0 OH0 900 960 900 900 9 OH0 gall HO 3. IN1)8I.1 61 6SF100061. MA 1.)fit) 6r.Mal'dflistl,, 6). ...o.I.l) 61063K 2.122 1.92') 1.19 02a)9 62629 820 629629 879 029 829m629r 829 8929 829 )rK (lb.4.ltel) 060813 724 MI0 606 620 620 62 620 620 620 620 $20 1.2 s20 620 620 62D 620 * loto. (PlastIc plat) 'QUO63 .210 730 106J 100 160 160 160 160 160 160 100 160 100e 160 IGD 100 I00 w)toI split 600U63 . 290 245 210 160 I6D ISO 1Ko Igo 100 100 ISO I00 too 1600 18 [00 160 *Lii 01ati.l 'OH 63 246 220 2030 180 1KD In ISO 190 Igo 160 ISO ISO 1Ko 10 180 I00 too WWlI,lHarjai, '000 613 1)16r 160 160 140 140 140 140 140 140 140 140 140 140 140 140 140 140 I)almacijavino19r101k botteCi),)) '000 MI 100 170 10 160 160 160 15 IS0 160 ISO ISO ISO lt 160ISO 160 160 SO 1 0S ra go0ip.9r tilloticip. of.) 0006M3 100 Ina .10 16 10 10 10 10 10 10 10 l0 10 10 l0 10 *l*v. laioIJ.ca (iallway) 0006M3 I60 130 110 9H H90 90 H 90 90 90H H H900 MlIel.ars (Diary plant) 080to 166( ISO 140 130 130 130 130 130 130 130 130 130 130 130 130 130 130 *1)1e6 I.v 'M0013 166 166 146 i36 135 136 136 135 135 136 136 136 135 .136 136 136 135
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6938, 9.DO 4. ((090L1.TO04,9 '00090 1.8116I '(04A 2-(.0 232 M-.9.. 3.9i2l 40, 1.061. 9Y01)'l 1.0$! 11!3. 'I I (.3'.. ' .1-!. IO/ . I2610 3.036l 1.19034 (672 4.312 4.477 4.63!. 4.749 4.964 16.16 Table 1.4.Characteristcs of the Split wastewater
-- . ~ ~ ~ ~ ______IXKCATI IN ______IBANOVIA DU)JE ZIINTA RSI'I'.NIK I lEL "LAV" COMPOSITION(1995.) XAVR XMIN XMAX XAVR XMIN XMAX XAVR XMMIN XMAX XAVRI XMIN XMAX XAVR XM XMAX Suspendedtotal mg/i 52.65 24.4 116 49.325 26.9 10 43.725 20.1 104 49.475 18.7 96 67.044 '18.7 104 COD mg/i 153.9 94.1 324 139 44.4 223 206.38 81.5 421 167.58 51.9 383 255.87 51.9 421 BOD-5 mg/i 117.95 49.8 271 83.3 37.1 167 148.63 37.1 289 93.6 34.4 224 160.25 34.4 289 Total -N mg/i 99.05S 22 174.12 24.595 14.88 35 37.405 24 54.92 22.025 15.6 31.8 31.086 15.6 54.92 l'otal 1P mg/l 7.62 2.8 12 2.785 2.3 4.04 4.235 3.5 5.5 5.99 2.2 13.76 6.8625 2.2 13.76 MPN JO coli/IOOmI 40123 43 160000 2357.6 0.2 9000 5753.8 3 23000 2304.3 2 9000 8576.6 2 23000 Mineral oils 1tg/l 369 0 570 950 0 2700 232.5 0 510 344.75 0 927 445.44 0 927 Anion detergents pg/l 1287.5 810 2170 1376 844 2750 1614.8 960 2750 1763.8 470 4100 2270.9 470 4100 Phenol jag/l 1.75 0 4 2.75 0 6 6.25 0 13 3.5 0 9 6.375 0 13 Total - Ilg jg_ 0.5Q J 0 1 0.3 0 0.075 0 0.3 0 0 0 0.075 0 0.3 0 Total - Cd jtg/l 5.8425 0.67 17 10.738 0.95 353 0.6775 0 2.1 2.925 0 8.6 3.4063 8.6 Zn g/I 58 32 99 76.025 45.1 116 78 35 117 76.25 65 100 89.563 65 117 15 (Cr -g/I 9.7775 7.2 15.31 30.25 8 52 6.325 4.9 7.8 8.07 5.1 15 8.9925 S.1 Pb 8/I 381I 26.5 60.8 29.4 9.7 61.3 18.925 6 36.1 13.675 8.1 21.4 19.819 8.1 36.1
14 KAgTELA
Fig. 1.4. Plan of measurement stations within the sewerage system.
1S Table 1.5. Industrlal wastewater
AVIiRA(GI'VAIAJi.S FOR 1989.
IND[JS'IKRY KBC(' Djokom I)Dalmacijavinollr. 71jc;nic Mljekura IX' 10. kolovo? Salonil Salonacop Pivovara COMP'OSI'I1ION (flospilal) (P'lasticp.(Irrkbiig)(awy)()ryp)(Cement Chaino (Comnclt-azbc-St.PI.)(lugtrhse(rwe) CI' 8.57 7.56 7.49 7.75 6.67 8.37 11.5 7.33 6.62 Suspendedtotal mg/I 73.2 11.9 40.19 447 279 01.775 52 323 238 COD mg/I 273 113 2430 -- 471 142.1 54.2 289 1985 BOD-5 mg/I 86.9 28.9 1045 20.5 118 2.45 2.34 141 441 Total- N tng/I 2.95 3.49 12.4 13.76 . 24.3 9.97 Organic -N mg/i 1.61 _ (.903 6.53 7.19 14.52 4.01 _ 18.17 3.48 NI 3-N mg/l 1.76 11.25 2.25 7.2 8.58 0.035 . NO-N mg/lI 0.03 0 0 0.038 0.()12 0.009 0.204 0.001 0.006 0.416 0.56 0.431 NO3-N mg/I 0.788 0.688 0.65 1.1 0.86 6.63 3.22 P04 -P mg/I 3.45 _ 0.396 1.66 8.03 (irease mg/l 4.39 0.088 0.444 27 0.523 0.911 4.013 0.975 Mineraloils mgll 1.38 0 0.164 0,696 0.344 0.294 2.01 0.241 I'henols mg/l 0.025s 0.002 0,014 0.001 0.013 I)etergents mg/l 8.3 0.107 0.188 0.1° 0.906 0.873 Ml'N l2fcoli/lOObnl 7.8 23 33 6.6 11.6 0.000022 6700 990
16 I 1.4. THE SEWERAGE SYSTEM SOLUTION - CONCEPT
1.4.1. Metbology of solution selection - If wishing to exploit the coastal sea, i.e. the coast as it is foreseen, wastewater should be accumulated at several locations, treated to a certain extent and disposed into the sea far enough so that it will not affect the quality of the coastal and also open sea. Solving wastewater disposal should meet required standards and also prevent undesired long-termneffects. The question is how to do it in the most useful way. The sewerage system is always designed in accordance with certain water and sanitary standards that set the legal framework for a certain solution. Departing from the existing situation, and also taking into consideration its usage, water and sanitary conditions require that all wastewater from the area of Split, Solin, Kastela and Trogirr be disposed into the Brac Channel and the Split Channel far enough along with previous corresponding treatment that will ensure a permanent protection. This means that the Kaltela and Trogir Bay cannot be permanent recipients of wastewater from towns that surround them /2/, /3/ and /8/. With such requirements with a determined recipient, the basic prerequisites for solving the problem of sewerage system in this area have been set. The engineers were to find the best technical solution that would meet the required sanitary and environmental standards. Choosing the location for the treatment plant was the next crucial step in solving this problem. It was desirable that the plant be close to the recipient and that the greatest part of wastewater reaches it by means of gravity. Bearing this in mind the entire area of the Brac and Split Channel would be appropriate locations for the plant. However, this coastal area is extremely valuable and is primarily intended for housing, tourism and recreation and as such is not suitable for a wastewater treatment plant. Apart from that, the greatest part of the coastal area is already populated. On the other hand the plant should be located in such a way that it takes ihe advantage of most of the existing sewerage system thus requiring as less reconstruction as possible. Unfortunately, as it is presently the case, all the wastewater is concentrated in the very centres of towns where there are no facilities for -building wastewater treatment plants. Such situation did not provide any simple solution. In order to reach the most suitable solution, a detailed analysis of potential locations for the treatment plant was worked out /I1. Considering the plant features (capacity, dimensions, environmental impact, necessary infrastructure etc.), the potential locations were determined. Each location was completed with corresponding technical sanitary, town planning and other requirements on the basis of which a conceptual design of the plant was worked out. The solutions were evaluated and ranked. A conceptual design for the three most favorable locations was worked out accordingly as to make the final decision and taking into consideration the recipient, plant and outfall features and the sewerage system in general. The solutions were studied in detail bearing in mind the stipulated criteria. /1/. The results obtained were presented to experts, town planners, representatives of all interested institutions, government representatives and others who were welcome to express their opinion and propose the most suitable solution. On the basis of the aforementioned the most suitable solution for the Split, Solin, Kastela and Trogir sewerage system was chosen. 1A.2. Sewerage system concept On the basis of detailed analysis it have been concluded that protection of the sea environment have to be implemented by: treatment of wastewater at the sewerage treatment work, disposal of
17 effluent by long submarine outfall, treatment of industrial wastewater at production site and greening industry. The long-term solution for the Split, Solin, Kastela and Trogir sewerage ystem foresees the construction of two separate sewerage systems, that of Split - Solin and the one of Kastela - Trogir. (Fig. 1.5). These systems are separate-type systems. Each one would have its central wastewater treatment plant and a corrsponding submarine outfall. All the wastewater from Split and Solin would be united at the central plant Stupe in Stobrec, to the north of the commercial and transport terminal (TTTS). Treated water would be drained into the sea of the Brac Channel in front of Stobrec. All the wastewater from Kastela and Trogir would be united at the central treatment plant on the Island of tiovo, to the south of the village of ±edno. Treated wastewater would be drained into the Split Channel in front of Mavascica. In order to unite all this wastewater into the tratment plants, appropriate sewerage collectors would need to be built, as well as a number of pump stations and facilities. In order to protect the sea and perfortnance of sewerage treatment works, treatment of industrial wastewater at the production site will be instituted. The trade effluent policy will be established and strict trade effluent monitoring controls instituted. 1.423.The Split - SoIin sewerage system 1.43.1. Treatment plant and submarine outfall Treatment plant The crucial element of this system is the wastewater treatment plant (15). Analyses have shown that on the area of the Split peninsula there is not a suitable!area where a plant of 8 hectares could be located. The Stupe site was chosen as the most favorable solution. This site is north of theT7M and south of the city landfill Karepovac. This area is not suitable for any other purposes and it is at the same time far enough from the city and is not in collision with the purpose of the nearby land. Hydraulic load of the plant: Qaver., day Qaver.,day- Qmax, hour Qrain summer _ 3 m /day 128736 161568 - I m3/hour 5364 7732 8352 15804 m3/s 1.49 1.87 2.32 4.39 The organic load of the plant is as follows: concentration average load summer load (mg/l) (kg/day) (kglday) BODS 235 30252 37970 COD 470 60504 75940 TS 280 36046 45240 T-N 40 5149 6465 T-P 10 1287 1615
. . Long term solution of sewerage systems Split-Solin and KRatela-Trogir
.* - TREATMENTPLANT .* - PUMP STATION - - SEWER - - - - RAISING MAIN .- -- SllBMARINEOtlTFALL - TUNNEL
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-',VAMICA 611vo
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Fig. 1.5. Concept of the Spit-Solin andKalteIa-Trogir sewerage system. 19 The size of the plant complies with Austrian and German standards and instructions A131 from ATV. It was anticipated that the works would serve a population equivalent of up to 632833, including tourists and industrial contributions. The plant was designed by the Austrian company Scieffe & Forsthuber Consulting from Salzburg in cooperation with the Faculty of Civil Engineering in Split. As the technological process, the two-stepped process with active sludge was chosen (AB process) although satisfying results may also be obtained with a single-stepped process. The process was chosen according to a complex analysis of these processes 112/. The main advantage of the two-stepped process lies in the fact that in accordance with the cbaracteristics of the recipients the water will for a long time only need partial treatment so that the level of treatment provided by phase A of the AB process is in this case completely satisfactory. The plant was planned in several parallel technological lines, and each line in several technological phases, i.e. treatment levels. The basic elements and construction phases of the plant are adapted to the long-term requirements of the system and are as follows:
I phase II phase m phase screens B process anaerobic tanks aerated gritigrease rem. settling tanks sludge digestion A process sludge treatment RAS process settling tanks _ P- settling sludge treatment flocculation and settling disinfection
Efficiency of the plant and characteristicsof the effluent obtained in certain phases is as follows:
I phase _ phase Emphase (mg/,) % (mg/l) % (mg/l) % BOD5 94 60 5 98 5 98 COD 258 45 47. 90 47 90 TS 56 80 14 95 14 95 TN 32 20 12 70 12 70 TP 5.5 45 4.5 55 1 90 MPN coli.b. 10X106 99 10x104 99.99 O 100 Apart from the mentioned phases, it was foreseen for the beginning of the system construction that the plant operates only with a mechanical level of treatment, i.e. only with the screens and aerated grit/grease removal chamber. With the construction of the plant divided into phases the level of treatment would be adapted to the real needs and there would be a possibility for the third level of treatment in the future should this be necessary.
20 WrILgM -- , ------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..... *.L.-..
Fig. 1.6,Scheme - ground-pln of the treatmentplant
21 As the level of treatment increases, the energy consumption increases accordingly, as well as the number of workers, chemicals consumption, required space and the quantity of waste that is separated in the plant, so that the phases are as follows: energy persons chemicals space sludge (kwhlep/year) _ (g/ep/year) (M2) -(OgDM/ep/year) I phase 5 16 70 28000 29 H phase 30 32 78 64000 32 mHpIhas 32 38 810 73000 31
Submarine outfall In order to satisfy the characteristics of the recipient, primarily regarding the bacteriological pollution, a corresponding submarine outfall was foreseen for each construction phase of the plant Together with the treatment plant it would operate as a unique system plant - outfall. With regard to this, there will be two submarine outfalls im the final phase of realizing the treatment plant One of them would be rather long as a result of a phase-by-phase construction and a shorter one depending on the final condition. At the beginning, the mechanical treatment would require a submarine outfall 3230 m long, with a 400 m long diffuser. Depth at the point of disposal is 42 m. The diameter of the outfall is 1400 m Initial dilution will be 250 and secondary 35. As for the complete biological treatment of wastewater, the shorter outfall can be 931 m long, with a 400 m long diffuser. Depth at the point of of disposal is 32 m. The outfall diameter should be 1340 mm. Initial dilution will be 175 and secondary 6. In the first time period when treatment work will work with ca 50M capacity shorter submarine outfall can be built In this case total length of outfall will be 2600 m with a 400 m long diffuser. The outfall diameter should be at shalow water in Stobrec bay (956 m) 1000 mm while out of by 700 mm. Depth at the point of disposal is 36.65 m. Initial dilution will be 350 and secondary 34. The land part begins at the outlet and inlet chamber next to the treatment plant (Fig.l17.). Accepted route of the land part follows the transport terminal plateau, the access road to the terminal, crossing the access road in the south after the railing of the terminal. The route follows the access road as far as to the Adriatic highway, goes along it and Zrnovnica river estuary, crosses the highway toward Stobrec camp. The submarine part begins at the Stobrec camp, crosses the Stobrec bay in the direction of Brac Island. - The outfall route has a slight fall from the waste water treatment plant to the beginning of the submarine part and even further. Even though this fall is not necessary since the outfall is operated under pressure, depth difference makes possible emptying of the pipeline at a single point as well as collecting of the water after rinsing. The atitude of the land part takes the advantage of natural characteristics of the area, for the most part it requires digging for protectiorn. The submarine part is raised at such an altitude to provide a fall towards the outlet end, Fig 1.8.
22 -~~~~_ i nta - -s
Int - _,,- - _ / TRANSPDJRT - I- J
4~~~~~
-,.-. \A-,_ Xp- '- Fg1.Idprothsbaieuf/
/<'''~~~ deomlion ~Ochomber
river
Stobre,- - . ~~~STO8REE boy~
200m-
Fig. 1.7.Land part of the submiariieoutfall The diffuser is located at the end of the submarinepart, whereasdeaereation manhole is at the end of the land part (or the begininngof the submarinepart). Locationof diffuserdepends on stage of realiztion of the system(quan"t of water and level of treatment,or rate at whichthe seweragesystem is realized) Locationsfor I phaseand final phaseis givenon Fig 1.9. Solid wastes from treatment iplant The solid wastesassociated with the operationof the treatmentplant will consisto£ screenings, grease, oil, grit, sand and biosolids sludge.Screenings will be wash, dewateredand compacted before transportto the a landfill site or incinerateon-site. Oil and greasewill be burn on small incineratorin first time period and later will be dispose itothe digester. Grit and sand after passing through fine screens will be suitable for disposal to landfill or can be used for landscaping purposes. Stabilized biosolids from the treatment plant will be stabilized by anaerobicdigestion and dewateed. Sludgewill have a long term stabilityand will be suitablefor agriculturalor horticulturalpurposes Tot quani of sludge which will be produced at the works depend of inflow quantities of waste water and treatment leveL In accordance with total caPacityofthe trement plant daily quantitiesofthe sludge productioncan be ca 55 tlday.
23 110.0
5.0
E -iS.0
,, | -1~~~~~~5.0o. 4040
'PIPE DIAMETER AZBEST CEMENT A 1000 mm HARD POLYETHYtENE * 770/700 mni PIPE INVERT LEVEL [m) .l EXi.STING GROUNDLEVEL(m) S^ CHAINAGE Im) 8-
Fig. I.8. Longitudinal section of the submarlne outfall "StobreV" - I phase
24 ZALOV~ ~ ~772
VO 48-?~~~~~~~~52 4
56 S5~~~~~~~~~~~~4 35 5 48
37~~~~~~15
25 In the first time period (15-20 years) treatent plant will work probably with 50 % capacity. Initial wastewater flows will be lower than 50%/oand will depend on development of sewerage system. Increase capacity of the wozks will be necessazy when wastewater from Kaalinic Brig (existing submarine outfall) will be transferred to the central treatment plant 1A.3±1 Sewerage system of Split and Solin In order to bring all the wastewater to the plant, large sewerage collectors and pump stations should be built As already said the existing Split sewerage system collects all the wastewater in the city port and the Sjeverna luka (commercial harbour), 4 km from the site of the future plant In order to connect the northern Split area (Dujmova3a) and the town of Solin onto the central plant, a hydrotechnical tunnel approx. 2.4 km long should be built beneath Karepavac which would transfer all the wastewater of the northern Split area and Solin onto the southern area of the Split peninsula. Fig. 1.5. Fig. 1.10. Such tunnel would be necessary for the improvement of Kastela Bay because of its environmental significance for the protection of the Bay. Approximately 80% of organic pollution that reaches Kaktela Bay comes from the northern Split area and the town of Solin so that if transferred into the Brac Channel, the pollution of Kaktela Bay would considerably be reduced. Several pump stations would be required for connecting the southern Split area onto the cental plant Fig. 1.10. The southern Split area does have a sewerage system by means of which the wastewater is concentrated in the Split port Two collectors - the one at Ba&ice and the other along the railroad onto which the collector in the Domownskog rata St. is connected, form a complex scheme of the Split sewerage system by which the wastewater is collected in the city port All other zones at higher elevations are connected onto the aforementioned collectors by gravitation, while the zones at lower elevations are pumped by means of a number of pump stations. However, the direction of all the wastewater should be changed into the opposite direction (southwards) and brought to the Stupe plant In order to rationalize the costs of repumping part of the system will be altered from a combined to a separate one, and the whole new system will be built as a separate systemnin which the transmission mains will be directed towards the wastewater treatment plant Improvement costs of the existing system and bringing all the wastewater onto the central plant will be very high, and the construction of the system would last rather long even in the event should the financial means be provided (over ten years). Operation costs would also be very high due to often repumping of wastewater. Basic concept of the proposed sewerage system design The sewerage system covers the Split/Solin area in accordance with the General urbanistic plan (GUP). Wastewaters of this area (industrial wastewater as well as domestic wastewater) are collected by a system of canals and pumping stations and delivered to the wastewater treatment plant situated in Stupe area. Purified water is then disposed into the Brac Channel though submarine outfall situated in Stobrec, Fig. 1.10.
26 KAtTELA *
. / ~~CATCHMENTSOLIN .
K A T E L A 0 A Y V@o@ovoS..:
5J1NIE 7 .'ENTRAL\ TREATMENT -* .,PLANT"STUPE
- SEWEfl SPLIT ~~~~~~~00,2 1., --RISiNG MAIN B RA C C HAN N EL , )-S- TUNNEL , ; . . o os , t ~~~~~i. A.,. SUBMARINEOUTFALL @ PUMPSTATION jSEWERAGE SYSTEM SPLIT- SOLIN . ZN TREATMENTPLANT -WASTE WATERl-! ****e **CATCHMENT BOUNDA RlY M N_J V .______CT
Fig. 1.10. Seweralgeuystem Split/Solin -
27 The sewerage system is partially combined but mostly separate sewerage system- A combined sewerage system covers the area of already existing combined sewerage system. It will be stiU in use but the tendency is to eliminate it in the future. Combined sewerage system covers the major area of already existing sewerage system of Split Peninsula. That is the sewerage system that tends toward city port with the trunk sewer alongside the railroad, tnmk sewer Setaliste Bacvice and a series of smaller trunk sewers situated in old part of the town as well as a part of already existng sewerage system that tends toward Vranjic basuLnHigher zones are covered with combined sewerage system while coastal areas will be covered with separate sewerage system no matter if it already exists or it is only proposed. The rest of the area will be covered with separate sewerage system. A storm water will be disposed into coastal sea area on certain locations, diredy or indirectly, by means of existing springs and torrents. In the combined sewerage system storm water will be disposed into the sea at initial ratio of sanitary sewer and storm water of 1:3. An outfall position (depth and distance from the shore) should satisfy the required sea standards at each outfall site. Considering the topography and urbanisation of the area as well as the location of the wastewater treatment plant, the entire sewerage system can be divided into few separate catchment areas, Fig. 1.10. They are: the South catchment area, the Dujmovaca catchment area, the Solin catcbment area and the Stobrec catchment area. A construction of series of smaller and bigger pumping stations, truk sewers and other structures is planned in order to conduct wastewater to a singular wastewater treatment plant The South catchment area covers the area of Split Peninsula from Znjan in the south then following the peninsula watershed to Domovinskog rata street in the north and a shipyard in the wesL Wastewaters of this area are delivered to the central pumping station of this catchment area 3 PS Katalini6a Brig. Its dry weather capacity is 2,097 m ts while its rain weather capacity is 9,24 m3ts. This pumping station is situated on the hill Katalinica Brig nearby existing submarine outfalL The purpose of this pumping station is to pump wastewater from the South catchment area to the central wastewater treatment plant Stupe. Three main trunk sewers of the South catchment area are connected to this pumping station. They are: the city poIt trunk sewer, trunk sewer alongside the railroad and trunk sewer from Setaliste Ba6vice street Second biggest pumping station is PS Znjan. Its capacity is 2,1 m3/s. It is a pumping station situated on rising main of the pumping station Katalinia Brig.- The Dujmovaca catchment area covers the area of Dujmova&a in the north following the line of Mravinaci potok to existing Jadranska cesta and than following river Jadro to the sea; in the south following the peninsula watshed to the Pujanke district; in the west Pujanke district and the area below Domovinskog rata street to the shipyard. Wastewaters of the area above existing Jadranska cesta are delivered by gravity to the collecting chamber of the tunnel from where wastewater drains by gravity to the wastewater treatment plant Stupe. Wastewaters of the area below existing Jadrauska cesta are delivered to the main pumping station Dujmovaca situated west from the crossroads Solinska cesta and Put mostina. This pumping station pumps wastewater to the collecting chamber of the tunnel from where wastewater drains by gravity to the wastewater treatment plant Stupe. Dry weather capacity of Dujmovaca pumping station is 3 3 0,630 mns wile its rain weather capacity is 0,963 m /s. - The Solin catchment area covers the area of town of Solin, in the south to Mravinac- potok and in the west to the boundary of Kastela county. Its north boudary is formed by suburban districts. It also includes wastewater coming from solinska zagora (area over the mountain). Wastewater
28 of this area is deliveredto the pumpingstation Solin. Wastewateris then pumpedto the 1mnk sewer saed aboveexisfing Jadanska-cesta and then to the collectingschmberof the tunnel. 3 Diy wather capaity of this pumpingstation is 0,650in s:. - Wasewater of Dujnoaa and Solin catcbmentarea is deliveredto the collectingchamber of Stupe nnel fromwhere it drains by gravityto the wastewatertreatment plant Stupe. The Stobre6catcibment area covers ihe rest, mainlysouth, area of city of Split Wastewaterof this area is partiallyby gravityand partiallyby meansof pumpingstations drained to the main wastewatertrainent plant Thebiggest pumping station of this areais the pumpingstation tine. Its dry weathercapacity is 0,188m 3ls while its rain weather capacityis 0,240m 3/s. It can be observedthat capital stuctures of the sewage system are: the wastewatertreatment plant Stupe and its submarineoutfal tumnelStupe, the wastewar teatment plant Katalinica brig and its outfal ma pumpingstations: Katalinica brig, Znjan,Solin-Japirko, DNmova6a, tine and main trnsk sewer of severalcatchinent areas hiterim solutionof the first phase of the seweragesystem constructionwill be the wastewater treatmentplant Katalinidabrig and its outlet Hydrotechnical tunnel "Stuae" In orderto connectwastewater of the town of Solinarea and wastwater of northernpart of Split (Dujmovava,Ravne Njive, Pujanke and other) with a commonwastewater treatment plant situatedin Stobrecarea, constructionof the hydrotechnicaltunel between Duje and Stobrec (TITS)isplanned,Fig. 1.10. andFig. l.11. Hydrotechnicaltunnel is chosen as the most acceptable technical and long term economic solution.A major part of watercatchment area of northern and southernpart of Split as wel as part of the town of Solin area can be deliveredby gravity to the wastewatertreatment plant Pumpingheight of lowerzones is considerablydecreased as well as the cost of works. Tunnelis 2436imlong. Its cross sectionis 15,39ni 2 . The elevationof tunnel entranceis 14.36m above sea levelwhile the elevationof tunnelexit is 11.93m abovesea leveLTwo sewer pipesof 1300 mm diameterare situatedin the tunneL.Tunnel is big enoughto lay other infasructu (electricity,telephone) out of which the most important is water supply systemthat connects northernpart of Split and Solin area with-plannedwater intake situatedat 2rnovnicawell. Total volume of excavatedmateial is 38500 m3 . 1.433. Characteristics of the wastewater treatment plant dte Microlocational characteristics of the wastewater treatment nilant site in reference to the entire area Considerng the city organisationand development,the most.appropriate wastewatertreatment plant location would be the north side of Split peninsula. It is the area intended for small businesses.It is obviousthat the basic ecologicalrequirements for every urban locationmust be fulfilled. Elevation (10-15 m above sea level) and partially built operationalarea are the limitations Thereforethe only suitablelocation will be the one situatednorth from the planned railroad junctionSolin-TTTS, Fi& 1.12. - -
29 z~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
m .n.m. o -b c-c 1001
70- -
20~~~~~~~~~~~~~~ 0 S -deoN,22 A A 4 - I 30- p R / tUHNN9 D .t . 'ore T 20R 00 NE i0::$-~~~~10X T-- C C-A
-30-~~ ~ ~ ~ ~ ~~~3 | IEVG L/DEPNT _5 9t r3cr c ._ -
Fig. 1.11.Longitudinal section of the tunnel-plant-outfall system; Split - Solin seweragesystem. 20. , 3 F;ig.1.12. Lmation of the treatment pliant"Stupe"
31 Location is situated in the far north of the Commercial-Transport Terminal area, in the foothill of Mosor, between proposed railroad junction Solin-TITS in the south and proposed highway Split-Zagreb in the north. The area is 8,4 hectares. Ground surface elevation is mainly 15,0 m above sea leveL According to the General urabanistic plan (GUP) one part of this area is planned to be used for tasportation activities. The other part of the area is situated in the comrdor of Split-Zagreb highway. A solid waste dump Karepovac is situated approx. 550 m to the west. The Split-Zagreb highway corridor is still not defined because its route is moved beyond Mosor (according to the Area plan of the Spli Municipality - adopted in 1982). A residential area of low density is planned north from the highway corridor. A small number of residential buildings is already constructed north-east from the wastewater treatment plant location. Significant forest zone is also situated in this area. A Commercial-Transport Terminal contents are situated south from the wastewater treatment plant location, Photograph 1. Considering the purpose of the area: large traffic areas, solid waste dump, forests (Mosor hillsides), the collision between proposed wastewater treatment plant location and proposed puurposeof the surrounding area is the smallest Site location in reference to the city infrastructure Traffic A track and a switching yard of TTTS-Solin railway junction are planned in the south of Stupe- TlTS site. A proposed highway corridor is situated north from the plant complex. Water supply system Water supply of Stupe-TITS area is planned from the water supply system of mrnovnicawell that delivers water of the entire area south of Koresnica by gravity. Electricity supply system According to the General Urabanistic Plan (GUP) TS 110/35 kV "Meterize", TS "Sucidar" and TS 110/35 kV "Centar" will be connected to the main city transformer station TS 220/100 kV "Vrboran". TS -Vrbobran" is connected to the main transformer station 380/22/110 kV situated in Konjsko. TS 110/10 "Split-3" was built to supply the middle part of Split peninsula. Transformer stations: 110/10 kV "Split-4" and 110/35 kV "Split-5 - Koresnica" will be built to supply the area of Stobrec. Stupe-TTTS site will be supplied with electrical energy from planned TS 110/35 kV Koresnica. Telecommunication system The main telephone exchange situated in Split covers the area of middle Dalmatian municipalities. According to GUP telephone network of the Split area contains: transit and main telephone exchange Split, centre ATC Kastela and seven district TS telephone exchanges situated in following city areas: Split Centre, Su6idar, Visoka, Sirobuja, Stobrec, Mravmci and Solin. Stupe-TTTS site will be connected to ATC Split (Sirobuja).
32
Proposed Site
~~~01"
Photograph 1. Location of the wastewater treatment plant "Stupe"
33 Microlocation characteristics of the site and usafe conditions Lavoutand available area - - Treatment plant site is situated in far north of the Stobrec field. Available area is 8,4 ha. Ground surface elevation is approx. 15,0 m above sea level in the east Ground level elevates toward west This site is relatively favourable in reference to the planned facilities of the surrounding area- The distance between wastewater treatment plant and TTS operational area is approx. 100 m. The distance between wastewater treatment plant and planned residential area of low density is approx. 120 m.. According to the conceptual design of TTTS (Civil Eng. Institute, Split) it is necessary to move the switching yard building south from railroad-junction. It is possible to place it as a part of central boiler goup building complex. Lithographic. engineering geological and hvdroyeolo ical characteristicsof the area Surface area is made of prolluvial sediments (youngest Quartemary sediments Qpr), composed of silty-clay material with some graveL Eocenic flisch (E2,3) mostly built of marls was deposited under proluvial sediments. Prolluvial sediments are poorly compacted and heterogeneous. Limestones are degredated but as the depth increases they have better physical and mechanical characteristics. Silty-clay material with some gravel has intergranular porosity, it is hydrogeological collector. These sediments are saturated. Water table was observed immediately under the ground surface. .Marls form impermeable base. Drainage must be well designed in order to secure functionality of the stucture. Foundations must be built on marl base. According to the Seismic map of Croatia, this area is situated in the zone where maximum earthquake intensity of 7°MCS for recurrent period of 200 years is expected. If shallow foundations are built on proluvial sediments higher level of seismic risk should be taken into account because of soil composition and high underground water leveL General hvdrological characteristics Civil Engineering Institute, Faculty of Civil Engineering, Split produced hydrogeological base plans and detailed design for regulation of one part of water courses Bekavac and Vrbovik (according to "General solution of drainage and stream regulation of ITIS area" and general design "Regulation of water courses Bekavac and Vrbovik" produced in 1981. and 1987). Regulation wasn't done till today. The same principle should be used for regulation of the upper part of stream Bekavac and one of its tributaries. It must be done because they either intercept or are situted near the wastewater treatment plant site. Microclimate characteristics General climate characteristics are given in the begging of the Study (General plan of Split,1978.). It will be possible to define microclimate characteristics of the area after one year measurements and monitoring. This must be done in the next design phase. Climate elements are very important factors in wastewater treatment plant design. Existing and planned infitructure Traffic Existing traffic infastructure consists of partially built TITS with traffic routs and junction road to Jadranska cesta (MC-2) at Stobrec area. Water purification plant complex can be connected
34 with urban iraportation network though previouslymentioned access road for ITIS and furiher witb separate accessroad that passesunder the plannedtack This road is 7,0 m wide. Parldnglot of224PlMcapacityis planmedin the east of the complex. Ia new urbanfrewway.is biult within the highwaycoridor (routeplaced behindKo2zak),'plant complexshould be accessedfom it. Water supply Existingpipe line of 500 mm diametercoming out of reservoirVisoka I is situatednorth from Jadranskacesta_ Another pipe line of 300mm diameteris buned in TTTS accessroad. Commercial-TransportTerminal Split (TTT) as well as the ewastewater treatmentplant site will be connectedto existingpipe line duringthe first phase. As the ultimatesolution they will be connectedto Zrnovnicawater supply system. Electricity - ; Electricty fahlities and instalations are not present in this area Therefore,according to the project,wastewater treatment plant willbe connectedto TS 1 10/10Koresnica. If wastewatertreatment plant is built before TS 110/10Koresnica it should be connectedto xisting TS 35/10 Miljevac with 10 kV cable extendingiiom TS 10/0,4 at the plant site, followingthe TITS road to TS Mljevac. Telecommunications Telecommunicationfacilities are not presentin this area Thereforeit is necessaryto lay 50-pair cablebetween wastewater treatment plant site and plannedAl'C Split4. 3patial dispositionofthe site and use of the area Taling into considerationthe site position in larger urban area as well as purpose of the surroundingarea (operationalarea, highwaycorridor that is stihlnot defined) limitationfactors of this site for wastewatertreatment plant construction are the leasL It is necessaryto cover preliminaryphysical treatment objects (racks and possibly sand traps, gease traps and primarysedimentation tanks). There are no specialrequirements conceming buildingoutines. Administation buildingshould be placed in the east facing existingresidential zone. Access road passes through the tunnel underplanned track- Surroundingarea shouldbe plantedout of securityand aestheticreasons. It is also possibleto build all necessaryinstallations. Railroadjunction can also be used. 1.4.4. The Kaftela - Trogir seweragesystem 1.4.4.1.Treatment plant and submarine outfall As alreadymentioned the central plantof this systemis locatedon the tiovo Island,at the site south of ±edno (Photograph2.) This site is visuallyremote from the coastalpart and is natually well protectedby a depressionso that its locationcannot affet the coastal sea. This site that is rather close to the sea of the Split Channel (400 m) is practically the only area of minor importancewhere the Ureatnentplant could be located accordingto the long-termneeds of Kakela and Trogin Collectingthe wasewater from Kastela and Trogir at this particularsite is the most suitble solutionin the enviomnental,economic and technicalpoint of view /147/ and /5/.
35 | ' ' , x,-~~~~~~~~~~~~~~~~~~~~~r , .a f
- , t-c.w' - - -- *- 4 *jS , n~ - -
1 Ph otograp- - of te 1 . ; .ovo
36,^_ CX _l 1; i ...... , , , - {E 4; < S ...... | .,.~~~~~~~~~~~~~>e t i ' i i f-- .7; b,-
!.i- -~ ~~e ' _-
Photograph 2. Locatfon of the wautewatertreatment plant "tiovo" 316 The greatest disadvantage of this location is the same as for Split - it is rather far from present locations for collecting the wastewater in Ka§tela and Trogir and the need for building a tunnel through the Ciovo Island because the wastewater needs to be transfen-edfrom Kastela and Trogir into the Split ChanneL The situaion here, is though somewhat more simple because there is not a significant sewerage system in this area so that the problem should be approaced from the very beginning. The wastewater treatment plant has the same characteristics as the one in Split, but its capacity is much smaller. It was anticipated that the works would serve a population equivalent of up to 150000, including tourists and industrial contributions. The hydraulic load of the plant is:
Qaver,day Qmax,hour m3tday 35888 1 m3thour 1494 2340 m3 /s 0.415 0.650
Mechanical wastewater treatment would require a 2400 m long submarine outfall, and a 400 m long diffusor. The outfall would be at a depth of 52 m and the outfall diameter 900 mm. Initial dilution will be 705. Biological wastewater treatment would require a 650 m long submarine outfall, and a 400 m long diffusor. In the first time period when treatment work will work with ca 50% capacity shorter and smaller submarne outfall can be built In this case total length of outfall will be 2050 m with a 400 m long diffuser. The outfall diameter should be 500 mm. Depth at the point of disposal is 52 in Initial dilution will be 394. The outfall route has a slight fall from the waste water treatment plant to the beginning of the submarine part and even further. Even though this fall is not necessary since the outfall is operated under pressure, depth difference makes possible emptying of the pipeline at a single point as well as collecting of the water after rinsing. The altitude of the land part takes the advantage of natural characteristics of the area, for the most part it requires digging for protection. The submarine part is raised at such an altitude to provide a fall towards the outlet end, Fig 1.13. The diffuser is located at the end of the submarine part, whereas deaereation manhole is at the end of the land part (or the beginning of the submarine part). Location of diffuser depends on stage of realization of the system (quantity of water and level of treatment, or rate at which the sewerage system is realized). Locations for I phase and final phase is given on Fig. 1.14.
37 20.0
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0.0
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E
-- 20.0
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.45.0
PIPE DIAMETER HARD POLYETHYLENE4SC mm
PIPE INVERT LEVELlm) _ . _ . ______. _ l
___ _: . _ _ _ .__ ___ EXISTINGGROUND LEVEL (m) __5___ 4 _ .7. CHAINAGE _m) A
Fig. 1.13. Longitudinalsection of the submarineoutfall "tiovo" - I phase
38 A ~ ~ ~ Jj /3 U'3..
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A*SU~~~~I V)I 36 53---
ss .,n5j; S St ~ nn ~ ~ 61: 57r36 M\ 334S
3 ' 59 _ 4a
1:100000 62 5 RAZMJER A 9 s K 6 6 A,oVSA.DU N r 7 59~~~~~~~~~~~~3 St Elcvldetatnclt ttlO metsr i ^ F F ~~~~~~~~~Godiooas, S' ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~VbIPPeI dubine a metrima.1ubfne oo odnose Po S S : I voda tIvib o,orsklh 5~~~~~~~~~9 srndnju rotinu nUtlh niskib - 45§ - , _ g Ut' ee J 'm oS,ta VISSA. na aredojo railo more,
4Figj 14 21. aootdfrvo3h The solid wastes associatedwith the operationof thetreatment plant will consistof screenings, grease, oil, gnt, sand and biosolids sludge.Screenings will be wash, dewateredand compacted before transportto the a landfill site or incinerateon-site. Oil and greasewill be bmnon small incineator in first time period and later will be dispose to the digester. Cit and sand af*er passing tbrough fine screens will be suitable for disposal to landfill or can be used forr landscaping purposes. Stabilized biosolids from the treatment plant will-be stabilized by anaerobicdigestion and dewatered. Sludge will havea long termstability and willbe suitablefor agniculturalor horticulturalpurposes. Total quantityof sludge which will be producedat the works dependof inflow quantitiesof wastewater and treatmentleveL In accordancewith total capacityof the treatnentplant dally quantitiesof the sludgeproduction can be ca 21 t/day. In the first time period (10-15 years) treatmentplant will workprobably with 50 % capacity. Initial wastewaterflows will be lowerthan 50%1*and will depend on developmentof sewerage system. 1A4.2 Seweragesystem of Kaltela The seweragesystem for Kasela would be rather easy to solve. The greatestpart of wastewater of this area (approx. 70%) is collectedby gravity by the main collectorwhich is locatedin the old Kastelaroad, i.e. the entire area abovethis collector.The wastewaterfrom the area between this collectorand the sea is transferredonto the main collectorby meansof a numberof pump stations.At the end of the main collectoris the main pump station that will transfer all the wastewaterfrom the Kastela area into the tunnel on the tiovo Island and throughthe tunnel bring it to the treatmentplant The wastewaterfrom the plant is by gravitydrained into the sea by meansof submarineoutfll The sewerage system covers the area of the town of Kastela in accordancewith the General wubanisticplan (GUP).It is the separatesewerage system. Wastewater is by meansof a special sewer networkdelivered to the wastewatertreatment plant A storm water will be disposedinto the coastal sea area on certain locationsdirectly or indirectlyby meansof existingsprings and torrents Consideringthe topographyand proposedurbanisation of the area as well as the locationof the wastewater treatment plant, the entire sewerage system can be divided into few separate catchmentareas, Fig. 1.15. They are: thearea aboveKa§telanska cesta that can be connectedby gravity with the wastewatertreatment plant and the area below Kahtelanskacesta that is by meansof severalpumping stations connected to the truniksewer situatedin Kaitelanskacesta. A wastewater is conducted through a main trunk sewer situated in Kastelanskacesta to the wastewatertreatment plant sitated on Ciovo Island. Every pumpingstation formsa separate smaller catchmentarea. Several pumpingstations connectedin series forma biggersewerage systemthat is connectedto a main tunk sewer situatedin Kaltelanskacesta. Larger pumping stationsare: P.S. Gomilica1 of 114,4Vs capacity,P.S. LukWicII of 48,8 Vs capacityand seveal others.
40 - c " .*t4 '- - -I~~~~~~~~~~~~~~~~Aobo-~
A '~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~k
00tto.,~ ~ 5 b,3
17~~~~~~~4
>=~( tUNNEt. SEWERAGE SY5TEM 4 "
55 ---. SUBMARINE OUTFALt OF KASTELA *,. * Ss;56:Rt 57SS * AcOO 7050 XGSom * PUMP STAIION o 10 o0 2a0 I REAIMENI PLANItt S7 00000 CACHNENY BOUNDARY u.-
FIg. 1.15. Sew,eralgeslystem of Kaltela -:
Is 4 The biggest pumpingstations of ultimatephase are: P.S. Jadro of 370 1ls capacity and P.S. Pantana-DivuljeofA21 Vlscapacity that partiallycollects astwaters of Trogir. The pressure pipeline of P.S. Pantana-Divuljeis 1600 m long. It connects wastewater of Ka§tea with wastewaterof Trogir at the entranceof the tiovo tunnel"Fig. 1.5. This pipeline is situated mostly under the water in Kakela Bay. In case of final phase constructionit is necessaryto constmcthydrotechnical tunael throughtiovo of 1900m lengthas well as one part of the tiovo Island seweragesystem It can be observedthat the capitalstructurs of the final so]tutionof the sewagesystem are: the wastewae treatment plant tiovo and its submaine outfalL tiovo tumnel main pumping stations: P.S. Jadro of 370 lls capacity and P.S. Pantana-Divu1jeof 421 I/s capacityand its submarinerismng main and the main trunk sewersituated in Kaltelanskacesta. 1.4.4.3. Seweragesystem of Trogir The conceptfor the Trogir seweragesystem is similar,except that there are three main sewerage systems:the land seweragesystem, the CiovoIsland seweragesystem and the seweragesystem of the old part of the town locatedon a small islandbetweeL the mainlandand the tiovo Island. The land seweragesystem of Trogiris mostly by gravityunited onto one pumpstation by means of which it is transferredto the tiovo tunnel.Zones at lowerelevations are repumpedinto main collectingsewers. The wastewaterfrom the northernarea of the Ciovo Island is by meansof a number of pump stations transferredinto the tiovo tunnel, while the wastewaterfrom the southern and western part of the island are united on the western part of the island at the wastewatertreatment plant Wastewaterfrom the old part of the town is connectedwith the land system.(Fig. 1.16.) Planned seweragesystem of Trogir is separatesewerage system Wastewateris deliveredto the wastwater treatmentplant situated on tiovo island tbrough single seweragesystem. A storm water is deliveredthrough separatestorm seweragenetwork to the sea. It is then disposedinto the sea in accordancewith the local requirements. The wastewater sewerage system network consists of three main catchment areas: the land catchmentarea and seweragesystem, the (iovo catchmentarea and seweragesystem, and old part of the town (small island) catchraentarea and seweragesystem. The sewerage system of each catchmentarea consistsof severalsmaller catchment areas. Each smallercatchment area is formed by a pumping station that delivers water to the central wastewatertreatment plant situatedon Ciovoisland, Fig 1.16. Totalnumber of requiredpumping stations is morethan 16. The coastal sewerage system consists of 7 pumping stations.The biggest ones are: Lokvice (Q=283 Vs, H=24m, P=lllkW) and Medena (Q=134 1/., H=24 m, P--53 kW). The main pumnpingstation of this part of a sewerage system is pumping station Lokvice that pumps wastewaterfrom the land overthe bay to the hydrotechnicalunel tiovo. Seweragesystem of the old part of the town consists of a single catchmentarea formed by pumpingstation "Stan grad" that pumpswastewater to the seweragesystem of the coastalarea
42 SEWER~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I RISINGMAIN~~ ~~~~~~~~~~RD IEVC PSMU
)-==< TUNNEL ee'c'P KYER SUBMARINEOUTFALL SEWER PUMIJA I~~~~~~~~(FULWAER e PUMPSTAtION - SMSEWERAGE SYSTEM i TREATMENTPLANT ,_ 2000O 2SOm OF TROGIR .CATCHMENTBOUNDARY
Plg. 1.16. Sewerage systemof Trogir
43 Sewae system of liovo island consistsof 9 pumping tations.The biggest ones are: Liovo (Q=25Vs, H=25m,P=15 kW), M$Draga (Q=43 /s, H=8 m, P=6 kW) and Okrug G (Q=144l/s-- H-30 m, P=71 kW). Pumping stations of northem part of the island tiovo, MiLevac and Arbanijapump wastewater to the north entranceof the tumneLPumping stions of the west side of the island.:MDraga, Okrug. G., OknigD. and OkrugD.-Recetinovac pump wastewater to the south side of the island into trunk sewer of the wastewatertreatment plant Pmnpingstations Fumnijaand Mavarfica are situatedin the south of the island. Sewerage system of Trogir is very complex and expensive as it can be observed from its description- Seweragesystem of Trogiris designedon a studyleveL Only central part of the town and part of the main trunk sewerof the land catchmentarea are designedon a higherleveL 1AAA.Hydrotechnical tunnel Ciovo In order to connect wastewaterof the Kagtelaarea and major part of Trogir (northempart of ,tiovo island and land part of the city of Trogir) with the commonwastewater treatment plant situatedin the southern part of Ciovo island, a constructionof hydrotechnicaltunnel through (-iovoisland is planned,Fig. 1.16. and Fig.-1.17. Hydrotechimcaltunnel was chosen as the most acceptabletechnical and long term economic solution. Constructionof this tunnel decreasesthe cost of pumping. Constructionof a very expensivetrunk sewer throughSaldun Bay is also avoided. Tunel is 1851m long. Its cross sectionis 10,52rm. The elevationof tunnel entance is 17,0m abovesea leveLThe tunnel exit is situatedin the south of Liovoisland, and its elevation is 15,0 m abovesea leveLOne sewerpipe of 1000mm diameteris situatedin the tunneL.The tunnel is big enoughto lay other infiastr e (electricity,water, telephone). Total volumeof excavated materialis 20500in 3. Materialis mostly limestone. 1.4A.5 Characteristics of the wastewater treatment plant site Conceptualdesign of the sewerage system of Kabtelaanticipated two constructionphases; the constuction of wastewater treatment plant near the airport as transition phase and the constuction of wastewater treatment phlnt on Ciovo island as the ultimate phase. The environmenalstudy will treat Ciovoplant becauseonly ultimateworks will be performed. Microlocationalcharacteristics of the site in reference to the entire area The wastewatertreatment plant tiovo is a commonplant for seweragesystems of Katela and Trogir. It is situated in the south of Ciovo island in the middle of the valley that extendsfrom village Zedno to MavarscicaBay, Fig. 1.18. This valley is not residentialarea or intendedfor any other activity. Thereforeas a less valuable area it was left to be the "green" area. Site situatedin the middle of the valley is far away from the coast (more than 800 m), inaccessible, closedand it can't be seen from surroundingurbanised area. The wastewatertreatment plant is situated far away from the town centre, residential areas of Trogir and main inffasrctu facilities and close by the holiday villge MavarAtica.Therefore it is the best site for the wastewatertreatment plant
44 mn MM /10VO ISLAND C C 100
U. u-II
30o, °, jlF TUNNEL l
-70 40 PH dOOm PD-Am . PD40m AVOmAC
| ^tAelONA 70 z Z z B . DIS1ANC~~~ ~ ~ 0 KOtErEsRENA~ Rc4n- to > >~~~~~~~~~~~~~~~~~~~~~~I~ 40 LEYGL/DEN0 TUNNEL
FI. onItdinisetin.1. f hetunnEL-patotalsse;K~eaTo eeaesse 20 cj~~~~~~~~~~~~4 fM - / Mi
Z'A ...
~~ ~ -0
-Fig. 1.18. Lo>cationof the treatent plant I|Ciovou
46 The sewerage system Kastela and Trogir study (Faculty of Civil Engineering, 1990) analysed several sites. Site situated in Kakela Bay and Trogir Bay as long term common solution wasn't accepted because it is vezy valuable and attractive area- Acoording to -water management authorities Split Channel that is situated accross from 6iovo island and is not a part of Kastela and Trogir Bay is water recipient The only logical solution was the treatment plant site situated on the south side of tiovo island. Out of aU available sites in that area, that is already considerably built and also intended for construction, site situated in the cove below village Zedno was considered to be the best. The wastewater treatment plant is situated 15 m above sea leveL It is a very rational solution considering that wastewaters of Kaktela and Trogir area (except for part of villages on Ciovo island) must be permanently multiple times repumped to the plant The wastewater treatment plant tiovo was worked out only on prefeasibility study level, hence detailed information about the treatment plant and its characteristics don't exist Therefore we can't give its precise position in reference to the urban infrastructure. Plant is situated far away from the town centre, residential areas of Trogir and main infiastructure,facilities. It is situated close by the holiday village Mavarstica. Plant can be accessed by road from the area of Mavarisica Bay. Infrshucture connection (water, electricity, phone) is also possible in Mavarscicavillage but only in the beginning while the plant is still not working with its full capacity. For the ultimate works suitable infrastructure must be built in order to meet the requirements of the plant with its capacity and characteristics. Litho2raphic. engineering geological and hvdrogeological characteristics of the area. The area is made of limestone beddings of Upper Cretaceous (Senonian) with infrequent dolomite lenses. This area is part of Primosten-Trogir-Split tectonic uimt Its north boundary is reverse fault Kozjak. The rock mass is well jointed because of inrtnse tectonic activity. Sandstone and limestone are brittle, jointed, very hard rocks of shell-like and irregular fracture. Joints are of "dmi" aperture, empty or infilled with degradation products such as terra rossa and silty clays. Hydrogeologicaly speaking these beddings have secondary jointed porosity that is more distinct in the surfice area. Precipitation water can be infiltrated relatively fast through the surface zone to the sea level. Duing rainy season a temporary surface runoff toward the valley can be expected. Therefore treatment plant site must be protected from it According to the Seismic map of this area, the wastewater treatment plant is situated in the zone where maximum earthquake intensity of 60MCS for recurrent period of 200 years and of 9°MCS for recurrent period of 500 years is expected. General hbrdrologicalcharacterisfics Hydrological layout of this area is very simple. Site must be protected from rainfall water only. Depending on the feasibility project of the plant it is possible that only one small stone canal that collects water coming from the boundaries will be. sufficient Surfaces of the plant should be mildly inclined toward the sea. Therefore the removal of ranoff can be done by gravity.
47 Existing and plannedinfrastructure
Traffic . - - Only the road that leads to M cimca village is built near planned treatmentplant complx. Treatmentplant site is connectedto the road of the holidayvillage Mavarsiica. Water supply Treatmentplant canbe connectedto the watersupply system of Mavarscicavillage. Sewerage Seweragesysten doesn't existin this area. Electricity, Telecommunications Detailedinformation about electricityand telecommunicatiorsystem is not available. Spatial _t2fion and use of the area As it was earliermentioned, the wastwater treatmentplant was designedon prefeasibilitystudy leveLTherefore detailed information about spatialdisposition and use of the treatmentplant area can not be given. As it is evident from the indented coast and town of Trogir, collectingwastewater is very complex and expensiveand requires a constructionof a larger number of pump stationsand several underwatercrossings and the constuction of two tunnels The Kadtelaarea requires similarfacilities, even thoughthe Kastela sewerageis somewhatmore simpleand cheap.Due to all the aforementioned,the constructionof the Kaktela-Trogirsewerage systm is a high-cost, complexand long-lastingsolution. 1A.5. Phases in the construction of the seweragesystems Such solutionfor the Split-Solinand Kaktela-Trogirsewerage systems is very expensiveboth regardingthe constructionas well as maintenance/operation.It is therefore foreseenthat it will not be realized in the near future. We must bear in mind that because of the standardof the populationin theseareas, the peoplewill not be able to financethe seweragesystem and to repay the loans in accordingto the foreseenfinal solutionthat provides a high standardprotection of the sea. This mostly applies to constuction, maintenance and operatin costs of the plant- Becauseof this we have foreseensohltions by phases by meansof which the long-termsolution would be completed.As to provide such type of constructionthe solutions by phases should meet the technicaland technologicalrequirements of the long-termsolution, but also improve the present environmentprotection, and functionas a unique technicaland technologicalwhole. Phasesin the constructionregarding the capacityof the plant and pumpstations are providedby buildingseveral separate operation lines: plant, outfall and other seweragefacilities. Depending on the level of treatment each operation line will be built at several treatment levels ie. technologicaltreatment processes.The followingis foreseen:complete mechanical wastewater tratment (screen, sediment chamber),partial biological tratment (A phase of AB biological treatmentand sludgeprocessing), complete biological treatment (B phaseof AB procedurewith appropiate sludge processing, de-nitrification, de-phosphatizationand disinfection. Each treatmentlevel would be accompaniedby a conrrspondingsubmarine outfall that togetherwith the plant forms a unique technical and technologicalwhole both in the sense of treatment and wastewaterdisposal into the sea.
48 Construction by phases would also be necessary because the largest part of this area has no sewerage system the construction of which would, apart from substantial fiancial means, require a long time. This practically means that a complete and unique sewerage system would require a very long time. As each constuction phase should improve the environmentprotection it was foreseen that a corresponding treatment plant and submanne outfall be built for each construction phase. This means that certam construction phases will be accompanied by building treatment plants and outfalls. However, as the long-term solution foresees a unique treatment plant these so-called "phase-plants are temporary because as the construction of the sewerage system advances towards a unique sewerage system and plant they lose their function. Therefore these phase-plants should be the least expensive as possible or to be used long enough as to depreciate the investnent Therefore only two levels of temporary plants have been foreseen: complete mechanical treatment and A phase of AB biological process. The sludge treatment plant was foreseen strictly at the site of the plant, i.e. it should be permanent Mechanical wastewater treatment would meet aesthetical standards of the sea and by long submanne outfalls they would meet the sanitary standard of the sea. The environmental protection of the sea would start with A phase of AB plant, and it would be more significant with the completion of B phase of AB plant De-nitrification and de-phosphatization and disnfection would provide high quality effluent and a long-term protection of the sea. Sites for the plant were chosen taking into consideration the fact that they be used as long as possible so that the investmnentsbe most depreciated. Bearing in mind the town-planning, and environmental features of this region as well as the existing state of construction of the sewerage system and outfall, we have come to three phases of the sewerage system (Fig. 1.19.). Within them there are several smaller systems and significant facilities. Technological phase A, final solution with two separate systems; technological phase B with four separate systems and an A-AB level of biological wastewater treatment at each of them; technological phase C with six temporary sewerage systems and corresponding mechanical treatment plants. It is evident that as the sewerage systems becomes more complete, the level of treatment increases because only in such a way is it possible to improve the environmental protection, i.e. reduce the pollution of the sea. The technological and economically acceptable transition from one phase of the system into the other is provided by temporary plants that would be built at the sites of the main regional pump stations that need to be built in accordance with the long-term concept of the sewerage system. Therefore, the temporary plants are conceived in such a way that they be used in the followmg phase for the final pump stations and functioning in incidental situations when the unique sewerage system breaks down. The transition from one sewerage system of construction phase into the other requires some major facilities that would enable smaller systems to be united into larger ones (C into B, B into A). In this case these are two hydrotechnical tunnels Stupe and Ciovo. In order to connect the Solin sewerage system to the one of Split it is necessary to built the Stupe tunnel, and in order to connect the Kagtela sewerage system and part of that of Trogir with the central plant of the Kastela-Trogir system, the Ciovo tunnel should be built Accordingly, the following elements-subprojects of the sewer system construction are possible: 1. Projects of A technological level: Al - Split-Solin sewer system with the centamlplant and full biological treatment and a central outfall A2 - Kastela-Trogir sewer system with a central treatment plant and full biological treatment and a cental outfall.
49 2. Subprojectsof B technologicallevel: BI - Stobrec sewr system with 'A-AB' phase of the AB treatmentlevel -and the respective outfall B2 - Sewerisystem of the Splt port with "A-AB, phase of the,AB uatent level and the respective outfiall . . x B3 - Kaltela sewer systemwith one tratment plant with "A-AB"level and the rspectiv outfll B4 - TIogir sewer system wii "A-AB" phase of the AD tratment level and the respective outfiall B5 - The Supe tunnel as the main swturefor connectig the Soliz and Split system B6 - the sewer system mcludingSoliM, Dujmovaca, Stobrec, with the plant "A-AB"phase of the AD treatmentlevel at the locationof the centralplant and respectivesubmarine oufall 3. Subprojectsof C technologicallevel: Cl - Stobrecsewer system, reatmentplant with fill mechanicaltretment of wastewater and a respectv outfill C2 - Stupe tnel, Solin , Dujmovac and Stobrec sewer systm, treatmentplant with full mechanicaltreatment of wastewat and a respectiveoutfall C3 - sewer systemof the City port catcbment,treatent plant vith fill mechanicaltratment of wastewater at Katalini6Bng and a respectiveoutfall C4 - Kastel Sucuracand Gomiica sewer system,treatment plant vwthful mechanicaltreatment of wastewater and a respectiveoutfall - C5 - sewer systemof westernpart of KaAtelamunicipali, treatmentplant with fiul mechanical treatmentof wastewater and a respectiveoutfall C6 - Trogir sewer systm, treatmentplant with fill mechanicaltreatment of waste waterand a respectiveoutfill 07 - 6iovo sewcr system,treatment plant with ful mechanicalntatment of waste water at the locationof the cental plant and a respectiveoutfall. Thus, fifteen alterative solutions of phase constuction were obtained in the wide area of Kaltela Bay, Figure 1.19. Each alteative is specific consideringthe cost of construction, operation and maintenance and also with regard to its envirnmental impacts, i.e. the impovemnentof environmentalprotection. This protectionis improvedwith the centralizationof the system and with higher treatment levels; howeer, this implies costs of constuction, operation and maintenanceof the systm The decision makers should solve the following dilemma.which structureshould be built with the availablefimds while simultaneouslyensuing better environmentalprotection. It is a complexand difficultproblem to reach correctdecisions since the selectionof eachphase of the systemconstuction does not includeonly the considerationof financialmeans (funds) but also the technologicalcharacteistics of the seweragesystem. The fundsnecessary for the system constructioncertainly representthe most importantfacto to be considered.Greater amount of fimdsimplies a higher level of purificationof the plant and bett collectionof the wastewater, which in turn makes the long-term implementationof the system more efficient and less expensive. If the funds are smaller the system should includelower levels of purificationand then it shouldbe decidedwhich is the best of the availablealternatives. The selectionshould not be based on some local interests since then the unique concept of the system should be threatened and hence its most efficient construction.Possible errors can provevery expensive and hazardousfor the successfulpotection of the sea in this area
so A T E L A
Figure 1.19. Sub-projects of the construction of the Split-Solin and KaBteIa-Trogir systems
51 Table 1.6. Cost of construction, operation and maintenance for each alternative of treatment work Total amount Unit Dally Sewerage Yearly Cost of the Altemaive of waste water operation operation system in use operation - system -______.______cost cost cost . . . (m3 /day) (US$/m3 ) (US$/day) (%) (US$/year) (US$) Al - 126 566.60 0.132 16 706.8 90 5488180.9 52 000 000 A2 30 868.20 0.132 4 074.6 90 1338498.2 40 000 000 BI 32 000.00 0.110 3 520.0 90 1156320.0 14 000 000 B2 36 000.00 0.110 3 960.0 95 1373130.0 16 000 000 B3 18 008.60 0.110 1 980.0 90 650740.8 10 000 000 B4 12 859.60 0.110 1 414.6 85 438865.9 13 000 000 B5 0 _ 6 000 000 B6 90 766.60 0.110 9 984.3 90 3279851.1 16 000 000 Cl 32 000.00 0.075 2 400.0 90 788400.0 5 000 000 C2 90 566.60 0.075 9 962.3 80 2908999.2 6 000 000 C3 36 000.00 0.075 3 960.0 95 1373130.0 8 000 000 C4 8 008.60 0.075 880.9 90 289390.8 3 000 000 Cs 10 000.00 0.075 750.0 90 246375.0 5 000 000 C6 9 800.00 0.075 1078.0 90 354123.0 4 000 000 C7 3 059.60 0.075 336.6 90 110558.6 6 000 000 Table 1.7. Organic load which will be removed in each alternative Equivalent Total quantity Efficiency of Total organic Alternative number of of sewage Pollution load teatment load removed population water plant (BOD5) (BODS) e_p.) (m3/day) (BODSkg/day) (%) (BODSkg/dayj Al 632 833 126566.60 37 969.98 90 34 172.98 A2 154 341 30 868.20 9 260.46 90 8 334.41 BI 160 000 32 000.00 9 600.00 50 4 800.00 B2 180 000 36 000.00 10 800.00 50 5 400.00 B3 90 043 18 008.60 - 5402.00 50 2 701.29 B4 64 298 12 859.60 3 857.88 50 1 928.94 B5 0 0 0 0 0 B6 453 833 90 766.60 27 229.98 50 13 614.99 Cl 160 000 32 000.00 9 600.00 25 2 400.00 C2 452 833 90 566.60 27 169.98 25 6 792.50 C3 180 000 36 000.00 10 800.00 25 1 620.00 C4 40 043 8 008.60 2 402.58 25 600.65 C5 50 000 10 000.00 3 000.00 25 750.00 C6 49 000 9 800.00 2 940.00 25 735.00 C7 15 298 3 059.60 917.88 25 229.47
52 1-L.NTEGRATED ENVIRONfMNTAL'PROJECT - KASTELA BAY The Project financed by the Bank includesthe main elementsof the sewrage systems Split- Solin and Kastela-Trogirwhich ensurea7long-term protection of the Kastela Bay, Figure 1.20. This Troject inakesit posnsblefor all the wastewater released into the Kastda Bay to be collected, purfied and released outside the Bay into the lfai-Split Channel.This Project SIso ensurs total and long-term protection of the Trogir Bay since all the waste water currently released into the bay will be collected,purified and released outside the Bay into the Split ChanneL.. The Projectincludes the followingelements of the sewersystems: a) Split-Solin seweragesystem . - -main sewer systemof Solin(total lengthof 3800m, 0 400-800mm), with the main pumping station "Japirko-Solin"(Q=0.650m 3/s, Hman=23m) and the belonging pressure pipeline -(lengthof 800 m,0500 mm), Theseselected strUCtUres represent the most importantparts of the Solin seweragesystem which ensure that system can function as a unique and completetechnological system which ensures environmentalprotection and high standardsfor the usersof these systems.All wastewater from these systemwill be transferby pump station'Japirko-Solin" to hydrotechnicaltunnel "Stupe".
- main sewer systemfor the DujmovaEaand Vranjic (totallength of 9400 m, 0 250-1200mm) with the accompanyingmain pumpingstations, -i.e. the pumpingstations of the Dujmova6a sub-catchment"Duje (Q-0.506 m31s,Hman 22m, belonging pressurepipelinelength of 260m, 0600 mm), and "Dujmovaa (Q - 0.963 m31s,Hman - 21 rm,belonging pressure pipelinelength of 831m, 0800 mm), and the punping stationsof the Vranjicsub-catchnent" "VranjicI" (Q = 0.020m3/s, Hmnan = 6 m, belongingpressure pipeline length of 360m, 0150 mm), "VranjicIIr (Q - 0.090 m31s,Hlman - 13 m, belonging pressire pipeline length of 5OOm,0300 mm) and "WVranjicHr (Q0= 0.180 m3/s, H[man- 12 in, belongingpressure pipelinelength of 400m, 0250 mm). These selectedsucures represent the most importantparts of the Split north catchmentarea seweragesystem which ensurethat systemcan functionas a uiique and completetechnological system which ensures enviromental protection and hilgh standards for the users of those systems.All waste water from these system will be trasfer by pump station "Dujmovada"to hydrotechnical tunnel "Stupe".
- main sewer system of the Strobre6(total length of 2300 m, 0 300-600mm) sub-catchment with the main pumpingstation "Sine" (Q - 0.240 m3/1s,lman - 18 m, belongingprssure pipeline length of 1440 m, 0500 mm). These selected structures representthe most importantpart of the Stobredseweage system which ensurethat systemcan functionas a uniqueand completetechnological system. All waste water from these system will be transfer by pump station"-ine" to wasewater treatmentplant "Stupe". ..
hydrotechnical tunnel "Stupe" (length 2436 m, crosi section A = 15.39 m2)
53 WORLD BANK AND EBRD PROJECT
._i - TREATMENTPLANT; MErCIIANICAL .* - PUMP STATION
- -SEWER - -- - RAISINGMAIN ..- -- SUBMARINEOLUITALL - TUNNIL
Seweragesystem T L L A Kastela-Trogir 0 ., Seweragesystem Split-Solin
TROGIR~ ~ ~ ~ ~ ~ ~ ~~ ~~~ *~~~SOLIN TROGIR ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~jadro
P.S5.Du mvI rament plant ~~PV ~~~~DUIMOAAstipe
~~~EDNO ~~~~~~~~~~~~~~~SPLITMARIAN FS sn Treatmentplant
Figure 1.20. Parts of the seweragesystems which will be flnsnced by the Banks which are Included in the Kastela Bay Project 54 The hart of wasewater collection system Split/Solin is hydrotecinical tunnel "Stupe- by which wastewater which belong to catchment area of Kaktelabay will be transfer out of bay to the Brac charmel.Transferring wastewater out of the Kastela bay enviromnental rehabilitation of the sea water of the bay will start
_ - Stape"treatment plant - Phase I (mechanical treatment)(Qmax = 0.880 m3/s), The goal of this treatment is to produce an effluent that may be discharged by outfall, producing "no visible slick" and protecting downstream processes. It can be achieved by- coarse and fine screening (holes less than 6 mm), grit removal, grease and oil removaL
- long submarine outfall in Stobrec - Phase I (length 2600 m, 01000 - 700 mm, difusor 400 m, depth 37 m) The outfall diameter should be at shallow water in Stobrec bay (956 m) 1000 mm while out of by 700 mm. Since the waste water sewerage system will be realized by stages, the outfall should meet legal criteria for coastal water quality (El class at point of discharge and II class at 300 m from coastline) at any stage of realization including and Phase I of Stupe wastewater treatment plant development b) Kastela-Trogir sewer system - main sewer system of Kastela (total length of 16800 m, 0250-1100 mm) with accompanying 13 pumping stations, These selected structures represent the most important parts of the Kagtela sewerage system which ensure that system can function as a unique and complete technological system which ensures environmental protection and high standards for the users of these systems. All waste water from these system will be transfer by pump station "Divulje-Pantana" to hydrotechnical tunnel "tiovo". main sewer system for Trogir (total length of 13900 p,3 2 50-7 0 0 mm) with accompanying 9 pumping stations, - These selected structares represent the most important parts of the Trogir sewerage system which ensure that system can function as a unique and complete technological system which ensures environmental protection and high standards for the users of these systems. All waste water from these system will be transfer by pump stations to wastewater treatment plant "liovo".
- hydrotechnical tunnel "tiovo" (length 1851 m, cross section A = 10.52 m2), The hart of wastewater collection system Kaitela/Trogir is hydrotechnical tunnel "tiovo" by which wastewater which belong to catchment area of Kastela bay and Trogir bay will be transfer out of bay to the Split channeL Transferring wastewater out of the bays environmental rehabilitation of the sea water of the bays will start 3 - "(iovo treatment plant - Phase I (mechanical treatnent) (Qrnax = 0.356 m /s), The goal of this treatment is to produce an effluent that may be discharged by outfalL producing "no visible slick" and protecting downstream processes. It can be achieved by: coarse and fine screening (holes less than 6 mm), grit removal grease and oil removal.
- long submarine outfall on tiovo I phase (length 2050 m, 0500 mm, difusor 400 m, depth 47m).
55 Sincethe waste water seweragesystem will be realizedby stages,the outfall shouldmeet legal criteia for coastal water quality (MI class-at point of dischargeand II class at 300 m flm coastline)at any stage of realizationincludig and Phase I of tiovo wastewatertreatment plant devicopment ^--: ~-- -- +v - ,; Theseselected structures ensure that each sewer systemcan functionas a unique and complete technologicalsystem which ensuresenviomental protectionand high standardsfor the users of these systems.This systemalso ensuresthe use of the coastalsea in accordancewith legislation, Figure 1.21. The treatmentplan includesthe plant for the materialfrom. the septic tanks which will makes possibleefficient disposal of the wastewater. The proposedconfiguration of the sewer systems and treahmentplanu ensures a gradual and efficientlong-term solution of the problemsrelated to the collection,treatment and disposalof wastewater in the area of KastelaBay and TrogirBay. The selectedtechnological level is in accordancewith the cmrentpractice and experienceof the communalorganization engaged in the maintenanceand managementof the seweragesystaem, so that all the problems can be efficientlysolved. Almost all the structureswhich will be built within the Project already exist withn the present sewerage systems.The constructionof the plannedstructures will result in the employmentof a great numberof new personneL Since these problemsrelated to the collection,treatment and disposalof the waste water have been dealt with for severalyears many administrativeand technicalactivities have alreadybeen carred out. Thus, urbanplans have been broughtinto accordance wifh the proposedsolutions of the sewer systems. Various pennmissionsfiom the water managementauthorities have been obtainedas well as consuuctionpemit for some structures.It shouldbe bomein mind that one part of the sewer systemshas alreadybeen constructedor is being constructedaccording to the selectedsolutions. The Projectdocumentation has been developedfor all systemsfor differentlevels, according to the interest of some cities and the priorities of their construction,starting from prelimiary design to the final designs.The Split-Solin,sewersystem has, thus, been developedat a higher level of the documentationand preliminaryactivities and will be realized before some other systems. The sewer system in the Kastela area has also been quite well developed,while the Trogirregion is the leastwell prepared,considering the documentationand construction. Environmentalimpact studies have been developedfor all sewer systems in accordancewith Croatian legislation.These studies representedessential conditions for obtainingthe respective permits and agreements. The plan for the constuction of structuresfor the sewer systemsprimarily includesthe proper disposal of the waste water, i.e. first the operationof the submarineoutfalls and plants, and subsequentlyall other structuresnecessary for collectingthe wastewater and deliveringit to the treatmentplants. The Project also includes,simultaneously with the constructionof the structures,the training of the personnelaccording to the selected equipmentand the purchaseof the equipmentfor the orgzations who will operatethese systemsaccording to the expectedtass in the maintenance of the sewer systems.
56 I COASTAL WATER CATEGORY: T1category _- IHIcategory a_ IV category OPEN SEA (ALL): III category
A T E L A
TROGIRjar
~~EDNO - -. ~~~~~~SPLIT
VAkICA '11ivo-
Flgure 1.21. Categorization of the coastal water In accordance with Croatian standards
57 1.6. MANAGEMENT AND STAFFING Vodovod i Kanalizacija is the operating company set up to manage the water and sewage infratucture on behalf of the Split, Solin, Kaitela and Trogir municipalities. Cuetly, approximately 35 staff are employed to operate the sewage system and pumping stations for the whole four municipalities. In addition, approximately 55 technical specialists are employed as mechanical and electrical fitter Planed development of sewerage systems Split-Solin and Kaltela-Trogir will require significant additional resources and additional 15-20 operatives will be required to maintain the new assets (sewers, pump stations, telemetric system, etc.). With two treatment plant the staffing level will increase over an extended penod of time. The treatent works operations team will be small in the beginning peiod (6 -10). A smaller team of chemists and laboratory staff (5-7) will be required for the initial phase. This period will require significant activity, establishing effluent and trade effluent monitoring. Planing development of the sewerage systems will require new management organization which will be able to operate and maintenance new collecting system asset, treatment plants and submarine outfills. Main component of that organization should be: - Administration and finance department, - Seweragedepattment, - Treatment works department, - Maintenancedepartment, - Scientific department Treatment works team and part of collecting system team should be recruited at the beginning period of systems construction in order to be familiarzed with the work and elements of the Systems. Planed full automatisation of systems and treatment works will require training for existing and new staff.
s8 2. DESCRIPTION OF THE ENVIRONMENT
2.1. PHYSICAL ENVIRONMENT - - The aea of concern is the wider area of KahtelaBay and neighboringmaritime areasincluding the Bras and Split channelsand the coastalstrip boundedby the slopesof the Koijak mountains to nrth, the city of Trogirin the west, and the river of ±rnvnica in the cast Thetopogaby of the area is shown on the Figure 21. The Figure shows the topographic diversity with mountainousland forms,gently inclinedfields typicalof coastalflatland and the teraced slopes of surroundinghills. 2.1.1. Geology This area is a part of a large C(taceDus-Tertiarysystem of outer Dinaric massiveand a typical Adriatic structu unit characteized by sediments of Jurassic, Cretaceous, Tertiary and Quatenary time (Figure2.2.). Jumssic thick-depositedEohtic and Lower Cretaceouslimestones occupy a very small area northeasternof the Jadro springtowards the MosorMountain . 7 Cretaceoustime is representedby the depositsof Upper Cretaceoustime: Turonianmainly well stafied limestones very little commingledwith dolomites and dolomitic limestones and Senonianmassive thick-deposited limestones and limestonedolomites exceptthe complexityof plate limestonesat the feet of the BiranjHill on the KozjakMounuin. Tertiary is representedby the depositsof eocenetime: classicaland carbonateEocene Flysch deposits, breccia, breccia conglomerates,with limestoneand marly depositsand fommmiifeal limestones. Flysch deposits of very heterogeneousstructure prevaiL Petrographicallythey are mainly sandstones commingled with marles, still limestone breccia, breccia conglomemtes,sandy calcarenitesand biocalcarenitesmay alsobe found. Such marked stratificationpoints to a rhythmicalsedimentation. Foraminiferallimestones occupy a small area at the marginsof Cretaceous-Tertiarysynclines. A largepart of Flysh sedimentsis coveredby Quatenary deposts of a very varying structure and thickness. During Quaternary,intensive erosion was a dominantprocess along with the transport and local settling of materia made up of fragmentsof limestone-dolomiticangular coarse skeleton and soil particles.The ratio of skeletonqutanty to soil particlesand depth of these depositsdetermine ecological-productive properties of this land. QuatermaryPleistocene breccia, counting fragments of Cretaceousand Paleogenecarbonate depositsof differentsize, extendsover a small areaon the westernside of Kastelafarmland. Alluvial deposits adjacent to the nvers of Jadro and Zrnovica are made up of sandy-gravely layers of Cretaceousand Tertiarysediments. The continental part slightly rises from the sea, gradually becoming rather inclined and tectonically folded slope, ending in a steep fissure - reverse fissure of Kozjak and Mosor mountains Pronounced deformities, appearing as folds sloping to the south, as well as transversallyand longitudnally split architectureare indicativeof high plasticityof Flysch deposits.
59 co ~~~~~~~~~~~~S.
C El,,
UpperCrelacews
KK2 Turonlanlmeslones wlh rarelayers dolemltas E3 Brecclasand breccla-congmerates withlbnes d limestones
E I Senonlanmassie Nmestones and dolordtes 0.1OLimeotnes brecclas Paiseogens Ouatemary
E12 ForaminelralUmestones d Wel-cementedbraccia
I] E2,3 Ilysch z a Alhukmn Fig. 2.2. Geologyof the area
61 Reverse fissures of Kozjak and Mosor steeply rise from recent Flysch deposits. Other parts of the cretaceous complex aLso make it a terrin of great energy with a number of karst geomorphologic phenomena. 2.1.2 Soils The soils in the area are very variable, resulting from the great vanation m different soil formatting factors over short distances (Figure 2.3.). Such factors include: the composition of the parent material; topography; and, human use and interference. The relative position and relationship between topography, geological structures and altitudmal distribution of soil types (soil mapping units) are illustrated in the schematic cross section A-A' (Figure 2.4.). There is close relationship between the spatial distnbution of the different soil types and the topography flatland and gently sloping relief are covered by arable, anthropogenic, terraced soils; abandoned terrace soils are found in areas of steeper slope; and, on the very steep slopes, natural, shallow and skeletal soil types are developed on the underlying limestones and dolomites. Natural soil types include Lithosols, Calco-melanosols, Cambic soils and Rendzinas. Lithosols lack well-developed genetic horizons, and are formed of skeletal limestones. Their appearance is unstratified due to the physical friable nature of the limestone, to the karstic hydrology and to intensive erosion of the smaller particles. On flat ground, these soils are very shallow (10-20 cm); on the steep slopes lithosols are found in combination with calco-melanosols and colluvial soils, which are much deeper but very skeletal. The properties of colluvial soils, which are much deeper but very skeletal. The properties of colluvial soils depend on the quality of the material that is transported, the distance of transport and the physical characteristics of the environment Calco-melanosols are shallow soils with well-developed organic horizons that lie above the limestones. chemically, these soils have a high humus content (mull-type), an excellent soil structure and the Calcium carbonate content is very low. Shallow depth and dryness resulting from low water retention capacity and underlying karst hydrology are the principal limiting factors to potential production of these soils. Calco-melansols are found in combination with Cambic soils. Rendzinas are humus-carbonate soils and represent a further stage in the development of the carbonate regisoils. These are mostly plateau type soils covered with forest vegetation. Their productivity dependents on the thickness of the humus horizon, depth of the profile and the properties of the parent material. Rendzinas formed on the marl regolites have a deep soil solum, in contrast to rendzinas on marl limestones or sandstones that are in direct contact with the parent rock. Soils developed on the impermeable Flysh marls, with a high content of silt and fine sand, are particularly prone to physical degradation such as crusting of the soil surface and erosion. The intensity and consequences of erosion processes differ, depending on the geology, topograpby, climate, soils, vegetation cover and human activities. The area surveyed is made up of two completely different geological substrta, which affect the hydrological characteristics of the soils. In the impermeable Flysh marls, with siltly and clayey soils, sparse vegetative cover and montane topography, erosion processes are most obvious.
62 ~~~~~~~Kailela bay 0
0 1 2 3 4 Skm
t. LUhdo andCalcokmelanosol corpiax 7. TarracedAbandoned soles on Flysch * 2.ltegosols 8.Terraced csrborrste sotis on Flyach 3. 2Rendzinas 9. Terracedvety skeletal soils on qualernary 4. Calco-melanosolsand Calco-combisl eomplex deposits S.Calco-carmbobs typical and colluvial 10.Anthropogenlc skeletal claylsh-oam S. TerraRossa soil; occslonalfy Cab.cembb9ol t togs on nuaemrarydeposits I:. Anthropogel sonson th alluvaldeposits (Fkrhi o)
Fig. 2.3. SoIl of the area
63 Sea "pe 10 Soi sye
/2K 500
O * 2 Ian
--- units -_t CEZ3
See
A------A
MFg.2.4. Schemadiccross-section along the section marked A-Al on Fig. 2.3. Cambic soils are formed on Cretaceous limestones and dolomites; and on Palaeogenic foraminiferal limestones, breccia and conglomerates. The ground where they are formed is characterized by a high density of stones and the well-developed karstic sub-soil morphology of the parent mateiaL As a consequence, wide variation in soil depth is a basic feature of these soils affecting their ecological value. In contrast to the erosion processes in the area of Flysh, the Cretaceous limestones have a high infilation capacity, which reduces or precludes the possibility of surface runoff and hence reduces surface erosion and mass movement As a result of the conditions affecting soil formation, in particular those relating to the parent rocks of the aea and the action of the climate on the limestones, Calco-Cambisols and Tera Rossa soils may also be formed. 2.13. Hydrology Hydrological, Cretaceous and Tertiary sediments are markedly contrasted. On the one hand, limestones and dolomites are very cracked and frequenty calcified, porous and therefore arid and without surface waterfilows. On the other hand, Paleogene Flysh complex is practically impermeable and liable to erosion and slide. Quaternary colluvial deposits drape Flysh deposits protecting them from erosion. Hydrological properties of Quatemary colluvium are determined by their texture and skeleton structure as well as by the thickens and properties of the environment and substrates through which they have been brought there. The geological properties of the coastline control ground and surface drainages creating different hydrological phenomena so that this area is comprised of rivers, smaller surface waterflows, ground water which diffusely and concentrated enters the sea at the sea level or below it (submarine springs). The catcbment area of the Bay watershed is twice that ofthe Bay itself (about 120 km2).
64 Intensiveurbanization caused this area to changepersistently the characteristicsof drained area. So, growing quantites of precipitatioiremain on the -smrce and are dischargedinto the Bay through a whole system of sma1 streams and chamels (precipitationsewerage). Since water quantitiesare limitedand relativelysmall, the water input is directlydependet on the intensity and duration of rainfill, varying a lot and being almost completely and during summer. Hydrologicalanalysis of the coastalwatrshed has never beenicompleted so that actualquantities have remainedunknown. However, the total quantityof suface and groundwaters that enterthe Bay everyyear havebeen estimatedat 100million cubic metres. The Jadro nver and the Pantana stream accountfor most of the freshwaterinput into Kaltela Bay. The area they drain doesnot belongto the surfacewatercourses of the coastalwatershed of the Bay. Flysch geological barrier extending along the coastline causes ground water accumulationsin the hinterlandwherefrom the Pantana and the Jadro waters sprout out to the ground. Thewateshed of these smallrivers covers an area exceeding260 km2. Annual averageflow rate of the Jadro River is 9.5 m3/s. Its minimum flow is 4.0 m3/s and maximumreaches as high value as 66.0 m3/s. The Jadro River annual run-of amountsto 300 million cubicmetres of freshwater. The Pantana flow rte has not been accrtely determined,since the spring is at the sea level where fresh and sea water mix The averagespring capacity has been estimatedat 6 m3/s, minimumbeing 0.5 m3/s and maximum20.0 m 3/s. The 2rnovica River,discharging into the Split Channel,is of considerablylower capacitythan the Jadro River. Winter averageflow rate has been estimatedat about S m3/s and the summer one to be very smalL An essential propertyof the riverineinput of fresh water is great variabilityaffected by the ainfilL About70% of annualfreshwater input is realizedduring winter. 2.1A. Climate conditions A long time meteorological-montorng shows that the study area is with relatively warm conditions,moderato precipitation, and markedlywmdy. Table 2.1 shows monthly frequency and averagewind speed(expressed in Beauforts)based on data obtainedover the 28-yearperiod from 1949-1976at the Split-Marjansaion, while Figure 2.5 shows monthly wind rose. The north-cast wind (CBuraWis most frequentand this blows 25% of the time with an averageforce of over 3 B in some autumnand wintr months Generallyspeaking, except in Mayand June,the frequencyof "bura wind never drops below20%. "tiroko" or the south-eastwind is frequentin February, Apnl and November,so that the local maximumfrequency coincides with the local minimumof "siroko"and vise versa. Theaverage force of the "siroko"exceeds that of the "bura" for much of the year. The "Maestral"is on-shoresuromer wind, which blows in the afternoonas the consequenceof much fasterwarming up of the land duringthe day as comparedwith the sea. Its directionvaries, depending on local conditions.In the study area, "maestral"is southwestern wind blowingtowards the coast at an angle of about 45°. The mean frequenciesof this wind in summertime (June, July, August)are 18.3, 17.3and 19.4 /%,respectively, while in the rest of the year it is negligible.Ifs force in smunmeris up to force 2-3Bf£
65 w w
January February
S w
March _ April
~~~~~~~~~~N
w wE
S -S
May June
Fig. 2.5. Monthly wind rose
66 8 July August
$ S
September - October
S S~~~~~~~~
November December
Fig. 2.S. Monthly wind rose (contd.)
67 In the summer period the frequency of the south-west wind is high. In contrast, the frequency of the south-east and north-east winds is at a minimum in the summer months, since the passage of low-pressure systems over this area is minimal during this period. During summer, the frequency of the nort-ieast wind is somewhat greater than that of the south-east wind, since it regularly occurs during the night time as part of the sea-breeze Circulation-During the summer period the wind is generally weaker and the greatest changes occur on a daily time scale These changes are the result of day-night circulation. The wind direction rotates over the 24 hour period in clockwise direction, so that at night a light north-easterly wind prevails, while during the aftenoon a south-westerly wind is predominant The afternoon or south-westerly wind may be stronger that the night wind because it represents the sum of thermally induced sea-to-shore winds. The so-called etesian wind, which form part of the general summer circulation of the eastern Mediterranean region, generally blow from the northwest, although locally their direction may correspond to the direction of on-shore winds connected with the day-night circulation. Table 2L1. Mean frequency (F) in parts per thousand and strength (J) of wind in Beaufortsover the period 1949-1976. N NE E SE S SW w NW Month F J F J F J F J F J F J F J F J Jan 178 3.1 276 2.7 213 3.6 140 4.1 68 2.1 36 1.6 26 1.8 41 1.8 Feb 196 3.7 299 3.5 160 3.9 198 3.3 64 2.7 31 2.3 26 1.7 19 2.2 Mar 167 3.2 219 3.2 158 3.8 176 4.2 88 2.2 79 1.9 28 1.4 64 2.1 Apr 129 3.3 216 3.2 149 4.2 197 4.2 82 3.1 129 2.2 29 2.7 53 2.1 May 136 2.7 140 2.4 136 3.3 120 3.7 122 2.2 168 2.3 47 2.1 77 1.8 June 97 2.8 169 2.6 130 3.0 156 3.3 127 2.0 187 2.2 35 1.9 57 1.9 July 151 3.1 235 2.9 102 2.4 84 2.5 92 2.1 173 2.4 64 2.0 54 1.8 Aug 149 2.6 229 2.3 88 1.9 68 2.6 118 2.2 194 2.3 45 1.9 62 1.8 Sept 193 3.4 285 2.8 101 2.5 84 3.5 120 2.2 133 1.9 22 1.1 38 2.0 Oct 195 3.5 305 3.2 101 3.3 99 3.3 120 2.3 80 1.9 33 1.8 39 1.6 Nov 160 2.8 252 2.9 178 3.8 185 4.0 86 2.6 37 1.6 33 2.0 54 1.4 Dec 177 3.3 316 3.2 127 3.4 111 3.2 96 1.8 58 1.5 36 1.8 52 1.6 A,mual 161 3.2 245 3.2 137 34 135 2.3 98 2.2 109 2.1 35 1.8 51 1. mean
With regard to outfalls design the most critical wind are the Southerly winds (SW, S and SE) as these will generate on-shore currents. The mean yearly frequencies of these winds is 34.2% and during the critical summer months (June, July and august) the frequency is 35.5 %. Surface air temperature is controlled by the wind and other weather processes and reflects the local balance of incoming and outgoing radiation, as well as heat storage in water bodies. Monthly mean air temperature over the annual cycles are presented in Table 2.2. Mean annual temperature is 16.0°C and the annual range (difference in mean temperature between the coldest and warmest months) is 17.90 C. January appears to be the coldest month with a mean temperature of 7.60 C and July the warmest month with a mean temperature of 25.50 C, which is in agreement with changes in global irradiance.
68 Tabk 2.2. Mean monthy tUmperatre (C,); number of hot, warmad cold days In exch month; mas (tl), min ( 2) and range of mean monthly temperature for the Split-Marjan -staonl 1949-1928 --. ;- - - Month Ian Feb Mar Apr May June July Aug Sept Oct Nov Dct MeanTemp 7.6 8.1.. 10.3 13.8 18.7 22.6 25.5 25.0. 21.5 16.9 12.3 9.2 Hot - -: - _ 0.2 4.9 15.7 14.3 2.1 Wa-m 0.2 7.6 21.4 29.4 28.4 16.4 13 - Cold 2.8 2.4 0.9 - - - - 0.1Q 0.1 tl (OC) 10.6 11.4 13.1 16.9 21.6 25.6 28.8 28.2 24.3 18.8 15.6 11.0 t2 (OC) 4.3 2.0 7.1 11.3 15.8 20.8 23.3 21.2 18.6 12.8 8.7 6.0 tI-t2 (OC) 6.3 9.4 6.0 5.6 5.8 4.8 5.5 7.0 5.7 6.0 6.9 5.0
The mean annual precipitation in this area is 820.6 mm with a minimum of 613.0 mm and a maxiunm of 1101.5mm. Precipitation is, on average, lowest in July and highest in November (Table 2.3.). The annual distribution of rainfall reflects both cyclonic activity and local topography. Since orographic rainfall is affected by the local topogWhy, a single rainfall recordmg station cannot be represenative of the spatial distnrbution of rainfall over the entire area Companson of the monthly ranfall figures suggests that the mean monthly total precipitationat the Katela Airport station is generally higher than that at the Split-Majan station.The KaktelaAirport station is situatedin the vicinityofthe highestmountain in the area, which is oriented in an ENE-WSW direction, practically perpendicular to the giroko". This is the wind that carries humidand relativelywarna air and thereforeusaully coincideswith rainy weather. Table 2.3. Monthly total precipitation (mm) for the Split-Mar; n station over the period from 1949 to 1988,and for the Kateda Airport station over the period from 1949 to 1970, and mean number of days with daily precipitation >0.1 mm (Nj), >1.0mm (N2) and >10mm (N3) for the Split-Marjan station Man& Ian Feb MMar Apr ay hkme J t Oct Nov Dec Agauaa SpEtM 9.7 70.2 69.1 60.5 562 511 304 443 60.1 74.S 113 SII820.6 Kakd&l.Aip. 102 S3 2 S2 5S 63 31 65 71 99 177 165 1068 NJ 12.5 11.1 10.7 10.1 10 u8 53 I 59 8.Ls3 10.7 12.9 N2 9.5 7.9 7.6 6.3 69 5.6 33 3J7 6 7.2 S3 103 N33b 2.9 21 1.7 2.1 -A 09 1.4 21 1.9 3.1 4.5
Mmimumvalues of relative humidity are recorded in the warmer part of the year, while the highesthumidity occus in the wintermonths (Table 2.4). Table 2.4. Annual and month, mean and minimum values of relative humidity (f) over the period from 1949-1928. month Jn Feb Mr Apr May Jime July AugI St Ot Nov D.I A..uaI MeM 1 61 0 60 59 r156 55015158162161 635 MaM 2 30 128 7 1 27 1 29 129 130 1281 AbsLMin. 12 110 115 1 6 1 21 'I 9 112 118 119 is X is IS 15
2.1.5. Oceanography The oceanographic chaacteistics of the marine environermntof the area, in terms of the cufemnts and distributionof temperatue, salinityand densitydepend upon the characteristicsof the wind field, the inflow of fieshwater,the insolaion and the influence of neighbouring sea. the effects of tidal oscillation are relatively weak and negligible due to the small amplitude of the oscillationsof the surfiaceresulting in relaively weak horinal currents.
69 Kakela Bay The Kastela Bay is a relatively deep basin witb an average depth of about 23 m (Figure 2.6.). It covers a total surface of about 60 km2 . It is deepest at the inlet (an-avrage inlet depth is about 40 m), so that the communication with the adjacent basin (the Split Channel) is good. Its flushing time and changes in the current field are greatly induced by local winds. The tides energy is considerable smaller. Since wind oscillates mostly on the time scale of synoptic disturbance, the curent field does the same with some delay. The estimated flushing time of the Bay is about one month. The eastern, relatively shallow part which represents one fourth of the total body of the Bay water, has the flushing time of 15 days. Some recent current measurements in the Bay inlet have shown that under strong winds the flushing time of the Bay may be considerably shorter, even less than five days. The same is presumably applicable to the eastern part of the Bay as well. This part of the Bay receives the bulk of waste waters entering the Bay. In the surface layer of the Kaitela Bay, a number of residual circulation types - both cyclonic, antcyclonic, and a combinationof the two can be seen at different times. The type of circulation is dependent on many factors, but primarily on the wind. The south-west wind generates incoming currents in the surface layer, while the north-east wind generates outgoing currents. At same time the surface circulation patterns in the Bay are anticyclonic and cyclonic with respect to the two winds. The temperature and the salinity of the sea water have been measured monthly since the late 1940s at a station located in the center of the Kastela Bay. In addition, sporadic measurements of these parameters are carried out in other parts of the bay. Table 2.5 shows the average monthly values of water temperture at the central station in the Bay over the period from 1952 to 1964. These data show a cooling of the sea surface during the period from November to February, when the surface temperature is lower than that of the deeper layers during this period. The surface temperature is at minimum in February and at maximum in August The water column is most homogenous in March, but in April the existence of a termocline can be detected in the upper layers. In October the thermocline almost disappears due to cooling of the sea surface and the vertical mixing generated by the wind. During the summer season the lowest salinity is found at the surface of the eastern section of the Bay, while in spring low salinity water is found in the west. This reflects the impact of freshwater inflow from the Jadro river and submarine sprngs. As a rule, the influence of the freshwater inflow is not apparent at depth below 10 m. The surface water of the central part of the Bay is under the direct influence of the Split channeL The eastern portion of the bay is separated from the rest by a quasi-stationary front in the field of mass. The less dense water, which is probably less saline as well, leaves the bay along the coast of the island of Ciovo. The temperature minimum of the deeper water layers in the central part of the bay during the summer has been excpalined in terms of upweling generated by the wind, suggesting that transport from the Split channel into the bay predominates in the bottom layer.
70 It~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.
Is, H';~~~~~~~~~~~~~~~~~~t * is ~~
Is~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1
94 6. I- Wall (j,'ill
4. ) I'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~'
) If~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~o II I, -~~~~~~P"4~1-Ai
t. 61~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.
of~~ ~ ~~ ~ ~ ~~~~~~~~~~~~~~~~~~- (Iq
Is~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~* ~*~. "-t
-.. Tt~~~~~~~~~~~~~~~I
So~~~~~~~~~~~~~~~~~~~~- C.0. g.~..,v6 .. t Table 2.5. Month averagewater temperature (DC)in KOtea bay Month Depth Depth Depth Depth Depth . Om lOm 20m 30m 35m Jan 10.8 12.04 13.77 13.50 13.70 Feb 10.76 11.22 11.43 11.82 12.00 Mar 11.49 11.49 11.44 - 11.77 -11.95 Apr 14.06 13.44 12.03 12.79 12.76 May 17.51 15.40 14.72 14.10 13.84 June 22.09 19.16 16.58 15.13 14.76 July 22.71 19.68 15.92- - 14.62:' 14.35 Aug 24.49 21.97 17.26 15.23 15.01 Sept 22.41 21.65 20.89 18.33 16.96 Oct 20.15 20.62 20.75 20,04 19.88 -Nov 17.29 17.76 18.37 18.52 18.55 Dec 13.19 13.75 14.85 15.20 15.37
Br=F and Split channel The Brac Channel spreads between the mainland and the Bran Island. It is bordered by the line between the small town Stobrec and Gomilica cape on the southwestem island coast, and by the line St Rok to Makarska in the southeast The channel is narrowest between Pucik6a (island Bra6) and the mainland (5 km) and widest in its southeastern part (13 kn). The greatest depth (78 m) is in the most south-eastern part of the ChanneL The Split Channel is a part of the sea between the islands tiovo, Solta and Brac. It is bordered by the southern Ciovo coast in the northwest, by a line that over the small islands Fumija, Kraljevac and Zaprinovac cliff stretches to the small islands Klude and Vei Drvenik A line nmning from Veli Drvenik across the cape Obinucki rt to golta, along the northem golta coast and through the Split Strait to the cape Zglav borders it in the southwest and south. Its eastern border is the line connectirlg the Gomilica cape on the Brac Island and Stobrec on the mainland. The greatest depths were recorded in front of the island Veli Drvenik in the western channel part (68 m); eastward the depths are smaller ( on the average 50 to 57 m). About 300 m long shoal Mlin stretches between the westem Solta part and tiovo (0-2 m the shallowest point). There is a large submarine erection between the Gomilica Cape and Stobre witb avage 15 to 20 m deep sea over it (9 m the shallowest point). Water mass circulation and vrevailin! currents Movement of water masses in the Split channel and Brac channel is mainly westward, and forms part of the general current pattern of the Adriatic. Surface currents are under wind influence, especialy during the summer season. Therefore, "maestral" the predominant summer wind generated eastward currents in a surface layer, while the "bora" (wind from the north) generates southward currents. Current field characteistics of the Bra6 and Split channels were described after analyzing all the available data on currents measured on several occasions since 1972. During the earlier period currents were measured from moored ships over 24 or maximum 48 h. The latest measurements were done in 1990 and 1991 by automatic moorings, so that these series are also longer and results more appropriate for observaions of wind effects. Measurements from a moored ship are performed under mainly calm conditions which is not the case with automatic
72 curTentinetes-Current measurementstations are so distributedto cover-a rather large part of both channels.In addition,we had availablea lot of the data from the close vicinityof the site of planned submarineoutfalL Ibis analysiswill give specialattention tothe rents in front of the Splittown port and in the area in fiont of Stobrecwhere sewageoutfall is plannedto be built 7 It might be expected that the occwrence of wedward and northward directons are very probable. These directions are in fact a part of the incoming current of general Adriatic circulationalong our coast Their fiequency is followedby the fiequencyof eastwardand southeastwarddirections which are very likelya compensatorycounter cmrent,prevailmg m the bottomlayer as distinctfrom the wetward directionswhich mainlyoccur m the surfacelayer. Westward directions are particularly frequent in winter,-whereas eastward and westward directionsprobabilty is very similarfor summer.It is importantthat the highest currentvalues are mainly relatedto westwarddirections coinciding in time with maximumfrequencies of these directions.So, for example,the greatest cumrentspeed of about 50 cm s-I was recordedat the station in ftont of the town port on 22 and 23 November 1972 when westwarddirecton frequencyamounted as high as to 49%/o.On the other hand the lowest observedmost probable current speed was recorded from the same station when the eastward direction is highly probable. It may be concluded that fiom the viewpoint of sea water tsanport and its charactrics, westwardflow, that is the currentto the western quadrantis most importint m the areas in fiont of Split harbor and Stobrze. The resultant currentsamount up to 50 cm se with the most frequentvalues between 10 and 20 cm7l. The highestvalue of mean daily resultantof all the data collectedby now was 47 cm s-l and was recorded in front of the Split town porLMean currentspeeds are bighest in the surface layer, rangingfiom 8 to 20 cm s7l. Currentspeed decreases with depth to be 6 to 11 cm s7l near the bottom. Of all the measmrementsever since 1972 resultant surfiacecmrent of eastward directionwas recordedon only one occasion;all other measurementsshowed suce currnts of westwarddirection suggesting extremely high probabilityof westwardflow. Frequently,surface currents have opposite directions of bottom currents which may be accounted for by compenstory mechanisms This situation occurs particularlyunder the conditionsof strong "jugo" wind forcing an onshore surface flow in the area of Split and Stobrec which is compensatedby an offshorecurrent towards the south in deeperlayes The highest speeds occur im autumn and winter months as a consequenceof strongerwind forcing.So, maximumrecorded speedsin the study areavary about 60 cm s-l occmringin the surfacelayer what points to the fact that they are due to wind forcing. Even though wmd speed is lowerin summerthan in winterwind forcing is more obvious.This is due to the fact that momentumof motion is transferredto a considerablyshallower sea water layer in summerthat is only to the layer downto the thermoclineowing to summerstratification. In summer, surface flow completelyfollows wind forcing as shown by the availabledata. To conclude,summer wind inducesthe flow whosedirection fuUy agrees with the wind direction. Under "bora" conditionsthe flow is of offshore directionand under "jugo" it is of westward directionwith an onshore component The most fiequentsummer wind (maestral),which locally blows from the southwest,forces surface flow along the northern coast of the Brac island of, generally,eastward direction. Under summer conditions with poor wind the flow is relatively poor, as well, in front of Stobrec;with a tendencyto be modifiedby bottomtopography. As it is wenlknown, a shoal in
73 this area has depth not exceeding 10 m in its central part It seems that the current field eddy occurs and that its position is determined by the position and magnitude of the shoaL On-shore winds generated surface currents are caused by 'maestral" wind and the south and south-eastern wind. While the frequencies of the "maestral in the summnerseason is high, the fiequencies of the south and south-easten winds are low. The sout-east wind, has a high fiequency in all seasons except the summer and is much stronger than the south or "maestmal" winds- Off-shore winds generated surface curTentsare induced by northern winds (N, NE, NW) and the -mean yearly frequency are 16.1 %, 24.5 %/o,and 5.1 % respectively. Long-shore currents, which can be regarded as favorable for the outfalls operation, are induced by easterly and westerly winds, and the mean yearly frequencies are 13.7 % and 3.5 % respectively. It can be concluded that on average more than 60 % of the total surface current frequencies are favorable (off-shore or parallel to the shore line) with respect to the outfall design. Temperature and salinity Temporal changes of sea water temperature in the Brac and Split Channels may be presented on the basis of data collected from two stations, Split and Stobrec (mouth of 2 rnovnica River) between July 1972 and August 1973, and 10 stations in September 1990 (Figure 2.7a) and 14 stations in April 1991 (Figure 2.7b). A temperature gradient was marked at both stations in July 1972, disappearing gradually in August, September and November due to vertical water mixing. The entire water column was isothermal at the station in front of Split during the late autumn and winter. Temperature inversion, with the surface colder than deeper layers, was recorded from the station in front of StobreL. Surface layers were again heated in March so that temperature gradient was pronounced in warmer months. There was a thermocline between 10 and 20 m in August 1973. The research carried out in September 1990 and April 1991 shonwedtemperature stratification with the thermocline between 10 and 20 m in the wider area of Brac and Split channels in September. In April the vertical isothermy was present almost throughout the study area No horizontal temperature gradient was recorded from the surface layer (0.5 m) of the Split and Brac channels. Salinity distribution at the surface of the Brac and Split channels shows that the Cetina fresh water effects are limited to the eastern part of the Brac Channel at the end of summer (September 1990) whereas only a narrow belt between Dugi Rat and Stobrec has lower salinity at the beginning of spring (April 1991 ._The shape of isolines suggests prevailing surface east- westward flow which was more pronounced in April 1991 than in September 1990. Higher or lower sea water density or at depends on temperature and salinity and is affected more by either former or latter parameter. Temporal variations of at at stations in front of the town Split and Stobrec in 1972/73 in dictated that the stratification is pronounced at both stations in summer whereas the water column is homogeneous in winter. In August 1972 the occurrence of "upwelling" or rise of bottom water due to the inflow of the open sea water in the bottom layer was pronounced at station in front of Stobrec. This phenomenon is indicated by the very well defined isotherms.
74 The at data colleed in September1990 fiom the coastalprofile of other stations point to the fect that bottom topogapby affects the sea water density isolines. This mens that the shoal betweenSplt and Stobredaffts he se of more densewatcloser to the.sface., 7 Ihe T-S diagrm, based on al the-available data from a wider area' of the Bra6 and Split channels,-sbows verfical sratification im this area to Ibe-due -to the vertical distnbution of salinity, which is particularly low at surface of the stations clOseto Stobre6 and Dugi Rat stongly affected by Cetina runoffs and to a lesser extent by those of the rnovnica River. However,this fresh wate is reaied in the nanow coastalbelt which becomesnarrower affected by the jugDwind. As shown by the data on currents,"jugo" induces an onshore flow component in the surface layer making the belt of fresh water along the coast still narrower.A comparson of T-S diagrm for April 1991 to that for September1990 shows-late spring fresh waterrunoffs to exceedthose in the late summerdue to graer precipitationquantities. Nutrients and oxvyen concentration Most of the data on nutrient concenttationsrefer to the sea water close to the coast (Split) directly.affectedby urban effluents.The data collectedin September1990 and April 1991refer to the thorough area of the Brac and Split channelsso they are better representativeof nutient loads in this area
10 km
tt ~~~SPtJTCHA*E B R A \. +
. _rv2i e C A __
FTig2.7a. Location of stations during September 1990 druie
75 @7 @2
tn~~~~~ .n2 *6 * 21 . *92
461'2~~~~
Fig.2.7b. Location of stations during April 1991 cruise
Table 2.6. Summarized concentrationsof ammonia (minmolNH3NIm 3 ) by levels in the Brac and Split channels Time Depth Geor. mean Stand. dev. max Mm
Sept 1990 0 0.44 1.23 5.15 0.06 April 1991 0 0.92 0.50 2.17 0.42 Sept 1990 20 0.24 0.89 0.56 0.03 April 1991 20 0.74 0.40 - 1.35 0.36 Sept 1990 botom 0.38 1.67 11.57 0.02 April 1991 bottom 0.76 0.42 1.48 0.
3 Table 2.7. Sumnmarized concentrations of nitrite (mmol N02-N/m ) by levels Time Depth Geom mean Stand.dcv. Max Min _ (m) (In) Sept 1990 0 0.09 0.34 0.127 0.047 April 1991 0 0.09 0.28 0.144 0.062 Scpt 1990 20 0.08 0.26 0.127 0.047 April 1991 20 0.09 0.47 1.206 0.041 Sept 1990 bottom 0.25 0.74 0.775 0.064 April 1991 bottom 0.28 0.84 1.188 0.090
76 Table 2.8 Summa_zed concentrtions of nitrate (mmol N034Wm3 ) by kvels -_- - Time Depth Geom- mean Stand. dev. Max Min - _{m)_ (in) _-_ _ SepL 1990 0 0.62 0.30 7.30 0.17 April 1991 0 0.52 0.44 1.11- 0.23
SepL1990 20 0.37 0.57 0.80 0.14 - April 1991 20 0.45 0.39 0.91 0.23 Sept 1990 bottom 0.52 1.15 5.00 0.22 April 1991 bottom 0.60 0.91 1.74 0.13
Tab. 2.9. Summarized concentrationsof phosphate (mmol 1P04-P/m3 ) by levelsof Bra and Split channels Time Depth Geoommean Stand.dev. Max Mm (m) (In) _ Sept 1990 0-- -0.067 - 0.467 0.121 0.022 April 1991 0 0.067 0.191 0.088 0.052 Sept 1990 20 0.033 0.881 0.105 0.006 April 1991 20 0.066 0.234 0.094 0.046 Sept 1990 bottom 0.058 1.480 0.193 0.000 April 1991 bottom 0.073 0.221 0.110 0.058
Ammonia concentrations were equal throughout the water column in April 1991 and significantlyexceeded those from September 1990 (Table 2.6). Nitites by different levels showedno differencesbetween different samplingintervals However,the nitrite quantitiesat the bottomof the Brac-SplitChannel were significantlydifferent from those in the upper sea water layr (Table 2.7). Differencesbetween mean nitrate concentrationswere not great with the exceptionof the bottom layer means for September1990. Mean phosphateconcentrations showedpractically no differenceseither as to the samplingintervals or to the layersof the Bra- Split ChanneL As shownby the collecteddata on ammoniaconcentratons at the coastal profileof stationsin September 1990 the station in the vicinity of Split appears to be the source of surfice layer ammonia.There are also some indicationsthat ammoniais releasedby remineralizationfrom the bottm As to the nitrates at the coastalprofile Qfstations in September1990 it is evidentthat they originatefrom the bottomwest of the staion in front of Spli Recordsof nutrientconcentrations characteize this channelarea as oigotrophic. Variationsin dissolvedoxygen concentrations,that is oxygen saturation,may be observedon data collectedfrom stationin fiont of Split in 1972/73. During summer (July, August, September)oxygen saation stratificationoccurred with the 100%isoline at 25 m depth.From September1972 a slight oxygendeficiency occurred at the surface,due to nutrient input by precipitationsfrom the land, as well as at the bottom. During winter, the entire water column was well aemraedand oxygen saturated owing to the good vertical water mixing and reaeration. With the coming of spring oxygen concentrationwas increaseddue to phytoplanktonactivity. Vertical structure of oxygen saturaion, measured during September 1990 cuise along the profileof coastal stations show that the oxygen saturation sructure differs firm that on the shoal
77 between Split and Stobrec. The sea water is oxygen saturated throughout the water column in the eastern part'(Stobre-&Dugi Rat), whereas bottom layers show deficiency and surface layer oxygen saturation in the western parts with respect to the station in front of Split Tbis is a consequence of vertical distribution of sea water density in September, which prents mixing of the surface and bottom layer water, as well as of biological activity of production in the surface layers and oxygen assimilation in the bottom layers. It is important that oxygen deficiency at the bottom coincides with the higher nitrate quantities. Under the conditions of sea water stratification honzontal distrbution of oxygen saturation shows oxygen deficiency in the bottom layer of the Split Channel due to organic matter input by cunrents and sedimentation from the area of Split. During winter months, when vertical sratification disappears the entire water column is well aerated affecting disappearance of oxygen deficiency. Therefore it may be stated that temporal and spatial oxygen distribution is prevalently affected by physical conditions in the Brac and Split channels whereas anthropogenic effects have not yet become obvious. Granulometrv of marine sedimentsr The September 1990 cruises for studies of geological properties of the sea bottom included the area of the Brac and Split channels from the line connecting Dugi Rat and Postira to the line connecting the islands solta and Drvenik and the mainland. In 1973 the profiles along the isobaths of 15, 20, 30 and 40 m along the southern coast of Split peninsula were studied in the area of Kasjuni, Sustjepan and Katalinika brig. Loam was recorded from the southern part of Split peninsula along three parallel profiles vertical to the coastline. This points to the fact that this fine sediment stretches parallel to the coastline and that there is a calm sedimentation area with no influences nor signs of bottom sea water movements adjacent to the southern coast of Split peninsula. Loamy facies with very small fine sand particles prevails in the northern part of the Brac Channel, whereas the IV fraction (particles size between 0.1 mm and 2.00 mm) with some ingredients of the I and II fraction (particles size < 0.01 mm, and between 0.01 and 0.05 mm respectively) particles is prevalent in the southern parL Therefore it may be stated that the loamy-clayey facies occurs in this area where, apart from terrigeneous component, due to the relative vicinity of the northern coast of Brac Iland, biogeneous component occurs, as well. The particles of the I and II fraction, with far lower presence of the IV fraction particles, were recorded from the area of the Split Channel on the southern coast of diovo Island forming the facies of clayey-sandy loam. The distribution of particles in the sedimerntof the Brac and Split channels gives respective sediment facies, which complies with the principle of basic and regular granulometric selection with respect to the distance from the coast and depth. This area is prevalently an area of undisturbed sedimentation with the dominance of the I and II fraction particles. The structure of size fractions of sediment particles reveals a lot about hydrodynamical properties of a particular area. Sediment is a deposit for a lot of substances of anthropogenetic origin. The main processes of remineralization of organic matter also take place there. The Table 2.12 gives the fractions by particle size in the Brac and Split channels However, to obtain mean particle diameter, as a common sediment measure which may be compared to some other properties, cumulative frequency of relative occurrence of individual particle sizes was related to
78 particie size classes on a probe paper. The size classes weretransformd, if necessary, to obtain linear relationshipof probability and particle sizes. Tabk 2.10. -Grmnulometricstructure on three profiles vertical to the coast of-the southern part of Split pedisula -, -, . Fraction7i( _ Depth I ml IV v (m) <0.01 0.01-0.05 0.05-0.1 0.1-2.0 >2.0mm Profile Katalini6aBrig .--15 - 17.86 32.59 26.52 2039 2.60 20 22.00 35.95 23.31 1i.09 0.65 30 31.03 36.90 14.87 22.20 40 - 40.92 33.22 14.61 9.32 1.03 Profile Sustjepan 15 13.13 26.04 21.01 35.23 4.59 20 18.35 33.65 21.I 17AI 9.18 30 32.55 34.05 16.70 13.99 -2.71 40 3802 29.93 12.60 18.60 0.82 ProfileKaunmi 15 9.05 16.56 24.72 45.85 3.82 20 32.61 31.96 15.43 18.29 1.71 30 22.13 29.10 27.46 21.31 - 40 32.98 32.55 13.19 20.80 0.48
Table 2.11. Mechanical (granulometric) sediment structure (frctions in %) In the Brac and Sp- chan at the stations Indicated on Figure 2.. station I I m .v v Teidunmark <0.01mm 0.01-0.05 0.05-0.1 0.1-2mm >2mm
1 30.43 29.57 18.71 20.97 0.32 Clayey-sandyloam 2 18.05 34.75 18.67 27.49 1.04 -Sandyloam 3 35.84 33.63 15.24 15.24 0.05 Loam 4 3.92 7.73 6.08 80.41 1.86 Loamy-clayeysand 5 . 18.47 32.11 18.68 28.96 1.78 Sandyloam 6 6.08 17.32 14.54 61.34 0.72 Loamy-clayeysand 7 38.38 27.90 16.14 17.53 0.05 Clacy-sandyloam 8 7.96 27.89 -126 41.32 1457 Loamy-clayeysand 9 28.87 27.18 19.85 23.89 0.21 Clayey-sandyloam 10 13.56 25.88 19.15 37.79 3.62 Loamy-clayeysand Table 2.12. Mean sedimentparticle diatnetr in the BraEand Split chanels at the stations indication on Fgre 2.8. ______Station Depth Meanparticle diameter -(m) (pm) 1 50 25 2 34 45 3 52 25 4 51- 400 5 '55 45 45- .256 53 45 8 60 135 9 65 40 10 28 o80
79 If particle size reflects the dynamics of water masses in a particular area (greater presence of smaller particles is suggestive of poorer bottom flow and uce versa, than it is obvious that the flow is stronger along the Brac Island coast and poorer along the northen coast of the channels. Isolines in the cental part ofthe Bra&Split Channelpoint to a possible cyclonic flow. Transparencv Transparency measured at station 1 (Figure 2.7) in front of Split between 1976 and 1990 ranged between 5 and 37 ri. Extremely high transparency was recorded only once whereas the lowest value of 5 m was recorded several times. Mean value of measured values was 12.23 m and standard deviation 5.74 m. Transparency shows here no definite trend.
so 2.2 BIOLOGICAL ENVIRONMET 221. Terrestrial vegetation ^ Present vegetation has almost completely been ihe result of the thousand years of human activitiesin this arLea-Coastalplain and slightlysteep slopes are mainly used for agriculture. However,agriculbtual land has been permanentlylost as a result of the recent developmentof tmws and residentialzones. Steeper slopes and mountainsides have preservedthe residuesof orginal vegetationcover, even though secondaryvegetation of coppicesand underwoodextends here and covers completelybare surfiaces.The coastalplain may have lost its originalvegetation alreadyin Neoliticwith first forestclearing, ploughing and finng Primary vegetation of this area belongs to two plant-geographicalzones: Mediterranean- evergreenone and sub-Mediteranean- deciduous(Figure 2.8). The Mediterranean- evergreenzone lies prevalentlyin the lower coastal part dominatedby Quercus ilex L. The sub-Mediterranean - deciduous vegetation with the species Carpinus onrentalis Mill, Quercus pubescens L. Traxinus ornus L and Ostya carpinifolia Scop., is dominant in higher parts belowmountain sheer rocks. However,long term frequentlycareless wood exploitationhas changed the structure of the Kaitela area vegetation.The primary evergreenvegetation has been stronglydegraded or it almostcompletely disappeared. Therefore different degradational stages of this vegetationcover the most part of this area Desertedterraces were planted by pine woods of Pinus halepensisM'IL, cypress (Cupressuw semprevirensMill) and arborvitae(YThja orientas). Of wild growingplants Pistacialentiscus, Pistacia terehinthus, Phillyrea media, Juwperus Oxycedrus and SparWum jwucem are encounteredhere. Pine woodsspread very quicklyinvading new areasof desertedantopogenic terraces. The largestpine trees was plantedon the Maijan Hill. Pine trees also dominateon the east of Solinbasin and toward2rnovnica. Very degradedsurfaces with shallowand skeletonsoil are overgrownby rockypastures and dry grasslandcharacterized by a large numberof species. Stronglydegraded surfaces of evergreenvegetative belt (on the west from Kastel Gomilicato Trogir),where trees and coppicevegetaton has almostcompletely disappeared, are of the form of spacious,deserted rocky land coveredof and rockygrassland and Adriaticcoastal rocky land (Brachypodfo - Chrysopogonetea). Low, alluvial plains along the nvers Jadro and 2rovnica and also Pantan spring were once coveredby wetlandvegetation of whichvery litle has remainedalong the Jadro River.Wetlands vegetationstill covers some parts of the right bank and estuary of the 2 rnovnicaRiver and the Pantan. Of wetland vegetation there may be found Sparagenwn eractum, Juncus mantimus, Chlorociperus longus and the reed species Phragmires Communis Trin.
81 I's Split
Clovo Ejjjgj3JPinus halepensis Maquls
Ouercuspubescens [Jji Scrub0
Carpinusorientalis eurned area
Fig. 2.8.Vegetation cover of the area
82 2.2.2 Marine biology Qualitative and quantitative(density) phytoplankton composition was observed at stations in front of Split and Stobrec in 1972 and 1973. Seasonalvariation amplitudes of phytoplankton were very smalLPhytoplankton quantity ranged between52000 and 96000cells/L Duringthe September1990 and April 1991 cruisesin the Bral and Split channelsphytoplankton chlorophyllbiomas (chlorophylla) was determinedapart from its qualitativestructure. Values of chlorophylla biomassranged from 0.09to 0.48mg chl a mn3. Highestchlorophyll a biomass was recordedfrom stations in vicinityof Trogirand Split The April cruisewas realizedduring regularspring phytoplankton bloom so that chlorophylla valuesvaried from 0.35to 1.47mg chl am -33 Verticaldistribution of chlorophylla on the profileof coastalstations shows high concentrations in the surfaeelayer of stations in front of Split and Stobrecand bottomlayer west of Split The area with high surface concentrationscorreponds to the area with higb ammonia (NH3-N) concentrationsand the area with high bottomconcentrations to that with high nitrate (NO3-N) concentrations. The same samplingswere carried out in the KaktelaBay and open Adriaticwaters (Stoncica) duringthe sametime interval.A comparisonof obtaineddata showedBrac and Split channelsto be more similarto Stoneicathan to the KaktelaBay. Chlorophylla quantitiesin the KaktelaBay were three to four times those recordedfrom most of the channelsstations. Vertical distnbudon wasuniform in Aprilpointing to intensivevertical sea watermixing. During April, productionin the area of the channelswas more similarto that in the KaftelaBay than to that in the opensea 'Stoncica). Qualitativephytoplankton structure shows great variety throughoutthe area, pointingto a rich but still "healthy"phytoplankton community. The area of the Brac and Split channelsis more stronglyaffected by precipitationwaters than by sewageeffluents of the town of Split. Seasonalvariations of zooplanktonbiomass in the coastalzone of the Brac Channelare shown by the data collectedduring 1972/73(Table 2.13). Table2.13. Seasonalvariations of zooplankton biomass (dry weightmg/haul) at stationsin front of Split and Stobret Station Time 10 11
September1972 89 67 November1972 47 1 April 1973 36 9 July 1973 57 42 August 1973 69 91 November 1973 - 105 10 January 1974 2 2 Geometricalmean 38 12
September1990 and April 1991 cruisesshowed that zooplanktonbiomass at stationsin front of Split and Stobrec was 107 and 70 mg/haulrespectively in Septemberand 61 and 49 mg/haul rpectively in ApriL Spatialdistribution of zooplanktonbiomasas in the Bradand Split channels
83 showed the greatest concentrations in the channels centre in September, and between Postira and Dugi Rat and in the Split Strait in April. This affects small pelagic fish behavior, that is their concentrations were also greatest at these sites which are also the sites oftheir spawning. Of plan1tonic fish stages sardine eggs and larve are dominant both by their numbers and percentages. The analysis of spatial distribution of the total numbers of fish eggs and larvae showed their greatest concentration in the area close to Stobrec in September 1990 and between Postira and Dugi Rat in April 1991. Greater quantity of eggs in the area of the Split Strait in April is indicative of the possible effect of incoming current from the open sea to this area. The analysis of benthic flora may be used as a good indicator of pollution state of a particular area. This particularly applies to three principal systematic algal groups: RHODOPHYTA (red algae), PHAEOPHYTA (brown algae) and CHLOROPHYTA (green algae). The group CHLOROPHYTA is most tolerant to pollution and eutrophication whereas PHAEOPHYTA are least tolerant The phytobeathos of the Split peninsula was studied in 1973/74. Two transects have been chosen, Zvoncac and Stobrec. During the 1977/78 research algae were determined from Zvoncac and Katalini6a brig transects (Table 2.14). Table 2.14. Numericaland percentage presence of benthic algae species on the localities: Zvoncac,Stobrec and Katalinica brig Zvoncac Stobrec Zvoncac Katalinika brig 1973/74 1973/74 1977/78 1977/78 Taxonomicgroups No % No % No % No % RHODOPHYTA -27 47.4 16 40.0 59 62.8 38- 53.5 PHAEOPHYTA 17 29.8 15 37.5 21 22.3 19 26.8 CHLOROPHYTA 13 22.8 9 22.5 14 14.9 14 19.7 TOTAL 57 40 94 71 R/P 1.6 1.1 2.8 2.0
Phytobenthic research was carried out in a wider area of Brac and Split channels in 1990 (Table 2.15). Table 2.15. Numerical and percentage presence of speciesof benthic algae and marine phanerogams on studied locaDtiesand throughout the study area (Split, StobreE, tiovo and Brac) .____.___ .___5g_ Split Stobrec Ciovo Bra6 Entire area Taxonomic groups No I% No % No % No % No % RHODOPHYTA 59 68.6 87 64.0 97 68.8 107 63.3 140 61.4 PHAEOPHYTA 10 . 11.6 27 19.9 26 18. 39 23.1 50 21.9 CHLOROPHYTA 17 19.8 22 16.2 18 12.8 23 13.6 38 16.7 Total 86 136 141 169 228 CYANOPHYTA 1 1 1 2 3 ANGIOSPERMAE 2 1 - 2 2 TOTAL 89 138 142 173 233 R/P 5.9 3.2 -] 3.73 2.7 2.8
84 Thegreatest changes in the stucttre of phytobenthicsettlements of the coastalchannel part were fomndat the Zvon6actnmsect (Split) where the numberof specieswas considerably er than on other fancts Recordedspecies mainly prefeiru iophiedwater most fiequenly polluted by ehemicals.The changesat Stobre6tnact were not of that intensity.A considerablygreater numberof specieswas recorded fiom the fansacts of the southerntiovo coastand westernBrac coast It is also importantthat no nyirophilousspecies were foundwhich is indicativeof the fact that the areaof Brae and t!iovo have not yet been underthe man-madeimpact Faunal materialwas also collectedduring the research oif the Braa and Split channels.It is qualitativelypresented by systematiccategories. Table 2.16. Numerical and percentage presence of macrozoobenthicspecies by systematic categories at the transactsZvon&c, K iniWa brig and Stobrec during earlier studies Zvoncac StobreI Zvonaac Katalinica brig 197314 1973174 1977178 1977/78 No % No % No % No %
PORIFERA 5 6.2 4 7.3 Is 7.6 7 7.5 CNMARIA 4 5.0 3 5.4 4 3.8 5 5.4 ANNELIDA 3 3.7 1 1.8 3 2.8 4 4.3 ARTHROPODA- 14 17.5 14 25.4 19 18.0 - 13- 14.0 MOLLUSCA 31 38.7 23 41.8 45 42.8 42 45.2 TENTACULATA 4 5.0 1 1.8 4 3.8 2 2.1 ECEINODERMATA 17 21.2 7 12.7 19 18.0 18 19.3 TUNICATA - - 2 2.5 2 3.6 --- 3 2.8 2 2.1 TOTAL_0 55 105 93
Studies of qualitaive stucture of zoological component of bionomic steps of supralittoral, mediloittoraland inhfalittoraldown to 30 m depth at the transacts Split (Zvoncac), Stobrec (southernside), tiovo (southernside) and Brac (northernside) were carried out as a part of the complexresearch in September1990. The transacton the southern side of Liovo is marked by the number and diversityof species preset there (112), followedby the tansact along the northern side of the Bra6 Island (96) whereasthe data for the transactsin Split (ZvondacX76)and Stobrea(75) were very similar and slightly poorer (Table 2.17). Table 2.17. Numbers and percentage presence of macrozoobenthic species by systematic categories at individual transacts studied in September 1999 - Split Stobrea ciovo Brac No % No % No % No % PORIFERA 8 10.5 7 9.3 22 19.6 No CNIDARIA 5 6.6 -3 4.0- 6- '5.3 ANNEL1DA 5 6.6 S --6.7 5 4 -45 ARTHROPODA 9 11.8 S 10.7 13 11.6 MOLLUSCA 37 48.7 44 58.7 49 43.7 - TENTACULATA I -1.3 1 1.3 -1 0.9 - - ECH1NODERMATA 7 9.2 -6 8.0- . - TUNICATA 4 5.3 1 1.3
85 The transact along the southern side of tiovo is far from any pollution source and is exposed to a permanent inflow of the sea water carried by current and to waves resulting in the richness and diversity of zoological element Similar applies to the transact near Brat. However, the areas of Split and Stobrec are affected by municipal effluents. The adverse effects are manifested as poor zoological element of medioli±toraland upper infmalittoralin the area of Split and Stobrec, where the changes in floral and faunal structure have already been recorded. 2.2.3. Fisheries, places of special interest for spawing and nursery grounds of commercial important species The most important commercial pelagic species in the area are sardina (Sarina pilckardus Walb), anchovy (Engraulis encrasicolus L.), while demersal species are silver hake (Merluccius merluccius), striped mullet (Mullusbarbatus), boops (Boops boops) and Maena smarts. The usual positions for traditional fishing under lamplight of sardinas and anchovies are shown on Figure 2.9. The average yearly yield of these species for the past period was estimated at 500 t for the Kastela Bay and at 2000 t for Brac-Split channels, while at present time was estimated at 50 and 1500 t respectively. The trawl fishing is forbidden over the entire area of Kastela Bay, while in Brad-Split channels is forbidden in the 1 Nm wide coastal strip and in the area between Stobrec and Supetar (Figure 2.10). According to the recently adopted regulation (NN 46/1996) trawling is allowed in the period from 1 October until 31 March from 5.00 am. to 10.00 p.m in Wednesday and Thursday only. There ara no informationon yearly yield. The Kastela Bay is the spawning area for sardina and anchovy, but not Brad and Split Recently was discovered that species Lithognathus mormyrus, L. was spawed during June and July at northeastem coast of Liovo island (Kraljevic et al., 1992). Estuaries of Jadro river and Pantana spring are the most important nursery grounds for sardines and anchovies, and very probably for other marine species. A similar situation should be at the estuary of rnovica river, but there are not adequate information. 2.2.4. Rare or endangered species and sensitive habitats So far, no rare or endangered species and sensitive habitats are identified in the area. 2.2.5. Quality of receiving waters Quality of receiving marine waters could be expressed in terms of the levels of pollutants concentrations in different components of marine ecosystems, as well as a health of the marine ecosystems. Both way, in describing the present and past trends in quality of marine waters, are used in this report. Kaftela Bay The Kastela Bay has been used as a recipient of the total amount of untreated urban waste waters of Trogir, Kastela, Solin, and about 40 % of the total amount of the town of Split, as well as total, partially treated, industrial waste waters of the whole industry in the region. This kdnd of pollution, together with airborne pollution and drainage from the urban and agricultural areas affect the marine ecosystems.
86 i I ;;.^ X rs *.~~~~~~~~~~~~~~~~~~~~~ttZW
se,_*~~~~~~~~~Fg .. sa stto for trdtoa fihn unde lapig '
nJIF $ ei~~~~~~~~~~~~~~9 I Legend
\ > \_ 1~~~~~~~~~~~~~~~~~~~~~~~~~IForbiddenTrrwilng Area|
1 > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Kameh KuOne
00
lFiv. 2.10. Zone for trawl fishing V
An eutrophication phenomenon in the Bay is very well developed. Results of the analyses of long-term data senes of dissolved oxygen, nutrients, transparency and phytoplankton have shown a cortinuos increase of the eutrophication in the Bay. While the concentration of oxygen in the euphotic layer increases due to a higher phytoplankton productivity, iD the bottom layer it decreases as a result of the activity of heterotrophic bacteria (Figure 2.11). The nitrogen/phosporus ratio in sea water has decreased, and today is much lower than in the open sea. From the Secchi-disc data it is clear that transparency has also decreased for the last three decade (Figure 2.12). Primary production as well phytoplankton biomass has also increased * (Figure 2.13). The stucture of phytoplankton community has been changed and dinofllagelate species have become dominant rather than diatoms. The direct consequence of the eutrophication is the occurrence of mass mortality of marine organisms which normally happened by the end of summer in the eastern, the most polluted, part of the Bay Microbial pollution of the Bay is very high. Dispersion of the pollution depends on winds conditions, but almost entire area ofthe Bay is not suitable for bathing Figure 2.13). Concerntration of mercury in the marine sediment is very high (1.95 -8.79 mg Hg/kg of dry sediment), due to more than 40 years of discharge of waste from a chlor-alkali plant which was operating in Kastel Sucurac. The Bay could be considered as sensitive area because it can be found highly eutrophicated area as a result of poor water exchange and a discharge of large quantities of urban waste water
- SURFACE BOTTOM
'S.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1960 1970 1980 1990
L S : Y E A RI,0'.,
Fig. 2.11.Average annual values of dissolved oxygen in the surface and bottom layer at the central sampling station in Kaitela Bay
89 20
to-
1960 1970 10 90 jSA
.~0 . .0O
-YEA R
Fg 2.12. Average annual valuesof transparency (Secchi disc) at the central sampling station in Katela Bay - Cm2 i * - primary production - n-uchlorophyll g biomass mgChia m 250 0
200 . 1.60
* ~~~~~~~~~~1.20
0.80
90 im 1970 ~~~1801990 FIg. 2.13. Increase of the primary production and chiorophili a in the Kaltela Bay
90 Trogir Bay Comparing to the KabtelaBay, the Trogir Bay is much less polluted. A study of sanitary quality of marine waters in the Bay, performed in the summer 1993, shows that the Bay is moderato polluted by urban waste waters, particularly in the eastern and north-easten part This part, obviously, is under the influence of urban waste waters of the town of Trogir and village of Seget The distribution of indicators of feacal pollution throughout the Bay depends on wind conditions. There are no other available information which could be used for the characterization of quality of marine waters in the Bay. BracFand Split channels The most northeastern part of the Split channel and the northwestern part of the Brac channel are under strong influence of high polluted city harbors (it receives a large amounts of untreated urban waste water). In this part of the channels the greatest changes in benthic communities have been recorded as a result of waste water pollution. A number of species was considerably smaller than on the westem part of Split channel and at the northwestern coast of Brac island. In this part (Zvoncac profile) the group of Phaeophyta (brown algea), the least tolerant to eutrophication, is represent by 11.6 %, while the group of Chlorophyta, the most tolerant to pollution and eutrophication, is represent by 19.8 %. In same time at the profile at tiovo island the percentage of Phaeophyta and Chlorophytaare 18.4 % and 12. % respectively. The changes at the Stobrec are less pronounced than at the Zvoncac profile (Figure 2.14). A similar changes were found in number of zoobenthic species (Figure 2.15) The concentrations of heavy metal (Cd, Pb, Cu, and Zn) in surface sediment sampled in 1990 are given in Table 2.18.
Table 2.18. Mean concentration of Cd, Pd, Cu, and Zn in surface sediment (mg/kg of dry sediment) Station Cd Pb Cu Zn I 0.796 38.48 26.45 167.47 2 0.831 28.71 20.01 115.57 3 1.006 37.99 24.93 149.75 4 0.674 1724 11.92 63.86 5 0.832 35.89 19.55 117.11 6 0.503 20.19 12.82 73.84 7 0.650 38.08 24.04 162.02 8 0.487 24.42 14.36 72.47 9 0.730 34.50 22.28 160.28 10 0.674 32.59 15.63 88.09
91 s W~~~~~~~~~~~~W
Fig214 oPesnc secesofbethc lgeon suidlcUfsi rcptcanl Legend ~~~~~~~~~~~4/ I Porifera
Fig. 2.15. Presence of macrozoobenthic species by systematic categories on studied locallties In the Brac-Sp3itchannels The reported values are within the range of natural concentation for manne sediments from the open Mediteranean sea, only zinc was present at a level which was twice of natural values. The increased zinc concentrtion was explained by the discharge of urban waste water into the channels. The Brac and Split channels, in general, could be considered as less sensitive area because of relatively good water exchange with open sea, they are not subject to eutrophication or oxygen depletion, and could be considered unlikely to become eutrophic or to develop oxygen depletion due to the discharge of urban waste water. 22.6. Sanitary quality of marine coastal waters and die-off rate of faecal bacteria Split town port and Vranjic basin are principal faecal pollution sources, besides a numerous outlets dispersed along the entire coastline of the studied area, since they receive untreated municipal sewage effluents. The speed and direction of waste water spreading in this area and its effects on the adjacent coastal sea is highly dependent on wind direction and speed. Split recreational zones only partly meet the requirements for their use (Figure 2.16). The poorest sea water quality was regularly recorded from Zvoncac and Bacvice, whicl may be attnbuted to town port impact. Stations Bene, Kasjuni, Hotel "Split" and Hotel "Lav" almost always met the requirements for their use. No essential oscillations in the number of faecal pollution indicators were recorded during the period of investigations with the exception of 1986 when these values were extremely high throughout the Split area. This was probably due to uncontrolled discharges of material from septic tanks into the collectors in the close vicinity to the sea, which overloaded the coastal area with faecal wastes. Die-off rate of faecal bacteria (Tgo) were measured at different depths at the station in front of Split in September 1990 and April 1991. The former measurement was carried out during poor insulation (veiy cloudy) and the latter during a sunny day. Both measurements showed that Tgo significantly increase with depth (Table 2.19). Table 2.19. Too values of faecal coliformsmeasured in September 1990 and AprUl199 Dph) T9o(hour) September 1990 April 1991 0 5.48 4.04 5 7.84 5.23 10 9.32 6.57 20 13.80 12.11 30 20.29 15.33 40 28.75 76.67 45 (bottom) 62.73 76.67
94
COASTALWATER CATEGORY: I category II category III category IV category
| 9 A §~~~ T E LA4
Fig. 2.16. Sanitaryqualty of the coastalwater In the area 95 2.3. ASSDMILATIVE CAPACITY OF RECEIVMIG WATERS The assimilative capacity of a body of water was defined by Goldberg (1979) as !amount of material that could be contained within a body of seawater without producing unacceptable. biological impact". The word assimilation is not quite proper, therefore GESAM (1986) replaced it by a word "enviromnental". The envirommentalcapacity is defined as a ability of the environment to accommodate a particular activity or rate of activity without unacceptable impact. The determination of environmental capacity of the study areas to acconmmodateurban waste waters requires rather more scientific information than is currently available. The capacity of Split-Brac channels to accommodate the waste waters was determined using a numerical model (see Appendix 2). The model was used to assess impacts of organic substances contained in the urban waste waters on the oxygen concentration. The model was made for the 'steady state" conditions, without the time component. It was tested using the existing data, which is not sufficient, specially because there are no data for the summer critical season. It is, also, very important to point out that the model doesn't deal with the changes in biological componentsof the marine ecosystems which would happened as consequences of the urban waste waters discharge. Results of the model indicated that this area has the ability to accumulate the planned quantities of the urban waste waters without unaccepted oxygen concentration decrease. Despite the mentioned disadvantages the results were used as good indications in the decision taking on the suitability of the Split-Brac channels to accommodate of the urban waste waters. In order to confirm the conclusion that the Split-Brac channels are the best solution for the accommodation of the urban waste waters, for the purpose of this reports the Ka-tela Bay, Split and Brac channels and Trogir Bay are discussed in terms of their volume, sea curent velocities and predominant directions and general physical characteristics. The Kastela Bay is a semienclosed oval shape bay. Its longest axis is 14.8 km long, while the shorter axis is 6.6 km long. The total volume of the Bay is 1.4 kn 3 , and average depth is about 23 m. The shallowest parts of the Bay are the eastern and western corners. The residual current field variations and the water exchange with the Split channel is mainly wind-driven. The average flushing time is about a month. The narrow coastal strip of the Bay is a highly developed area with various uses (housing, industry, harbor, tounsm, recreation, etc. The Trogir Bay, a semi-enclosed bay, as well, is much smaller than the Kastela Bay. It is 5 kn long, only, and 2.5 km wide. The depth at the planned location of the submarine outfall is 25 m, while the average depth is about, which gives the total volume of about 0.25 km3 . The residual currents (during the summer period in 1993) were very weak, particularly during a calm weather. The average cunTentspeed in the surface layer was 9 cm/s and at the bottom layer was 6 cm/s, while the predominant directions were N and ENE. The water exchange with the adjacent basin, would be, therefore, very weakL The coastal strip of the Bay is rather developed for tourism and recreation. Only, the north-eastern part is developed for housing (Trogir and Seget). The Split-Brac channels represent a much larger water body than the Kastela bay. The average depth of the Split channel is 60 m, its length is 20 km, and wide is about 10 km. The total volume of the channel is about 12 km3 . The average depth of the Brac channel is about 50 m and its volume is about 16 km3. The main directions of sea currents in the channels are westward and northward (measured in September 1990 and April 1991). These directions are in fact a part of the incoming current of general Adriatic circulation along the Croatian coast. The
96 highest speedsoccur in autumnand wintermonths as a consequenceof strongerwind forcing. The maximumrecorded speeds in the surfacelayer are up to 60 cm/s - In the summer,surface flow 'copletely followswinds directions.Under "Bua" conditions he flow is of offshore direction and under 1jugo" it is of westwarddirection with an onshore component The most frequent sumnmerwind "maestral". whicb locally blows from the southwest,forces surfice flow in easward direction.Mean speed in the bottom layer measured in September1990 in the Split channelat a station in the vicinity of the planned submarine outfall was 42 cm/s (minimun1.5 cm/s and maximum113 cm/s) The onshorecurTent direction (N) frequencyat the bottomlevel was zeo, whileat the surfacelevel was 32 %. The sea currents measurementsat the station located in vicinity of Stobre smibmarineoutfal showed the following:in September1990 the averagespeed in the upper layer was 4.8 cm/min(minimum 1.1 cmts, maximum 12.6 cm/s) and in the bottom layer was 6.2 cm/s (minimum 1.1 cm/s, maximum14.2 cmls; the onshorecurrent component (N) frequencyin the bottomlayer was 12% (average speed6.3 mts) and in the bottom layer was 20 % (averagespeed 8.1 sm/s); in April 1991 the averagespeed in the upperlayer was 16.5cm/s (miimum 1.5 cm/s, maximum45.6 cm/s);the onshorecurent direction(N) frequency100/e (average speed 13.9cm/s). The coastalstrip of the channe in its westernpart is mainlyundeveloped. The ratio of the volumesof the Split-Bradchannels, Kastela and Trogirbays is 112:5.6:1. This makesthe Split Channelthe mostsuitable to accommodateof wastewater, while the TrogirBay is the least suitable. Sea curents, directions and velocities also favor dischargeto the Split-Bracchannels. The predomnant directions are along the shores, which will result in the waste water not being tasported towards ihe shores but removedfrom the area of dischage to a widerarea The secondarydilution of the dischargedwaste will be much higher. In case of the Kastela and Trogirbays onshore directionof sea currentsare significant,which could bnng the wasteto the shore. Someamount of the wastecould be trappedin the bay. The accumulationof wastein the bays would impactthe marine ecosystem In the case of TrogirBay, due to its small dimension it is impossibleto discharge the waste waters far enough offshore, in order to preserve the coastalwater for bathingand recreation. The depth of the plannedsubmarine outfall plays the significantrole in the selectionof the most suitable location. In the Split-Brac channels,the depth of the outfall is 55 m and 32 m respectively,while in the Kasela Bay and in the TrogirBay are 30 and 25 m, respectively.In the of case the Split channelthe dischargeof wastewater would occur well enoughbelow the thermoclinedunng a summerseason. The probabilitythat the waste waterwould enrichthe sea surface is very low as the plume would be trapped below the thermocline and generally dispersedin the water column. A similarsituation will apply in the Brac channel and Kastela Bay. In Trogir Bay however it is more likely that the will plume reaches the surface and the wastewater tawsported towards the shoreby relativefast onshorewinter-induced currents. The present ecologicalconditions of the Split-Bracchannels also indicatethat this is the most suitableenvironment for the accommodationof urbanwaste waters. On the basis of -previouslysaid, it can be concludedthat the Split-Bracchannels represent ecologicallythe most acceptablesolution for the disposalof Split, Solin, Kastela and Trogir waste wates The advantages are:
97 - they have the largest volume; - they are the deepest, what is very convenient for thernocline and for primary dispersion, - they are not closed, so the outfalls could be as long as necessary, - - main cmrent is longitudinal, and so it will transort the waste waters of the channels into the open sea (waste water will not stay in the channels); - the influence of the urban areas of towns Omin, Split and Trogir is the least in-Split channel.
98 2.4. SOCIOCULTURALENVIRONMENT 2.4.1. Present and projected population The nummberof ihabitants in the Xaktea-Bayarea vaied in differentiniercensuns penods, but the populationgowth rate has alwaysbeen ratherhigb (Table 2.20). - Populationexpansion reached its highest point in the intercensusperiod of 1961-1971-1981. This significantrise in populationproves that the Katela Bay is an attractiveurbanized area with the city of Split i.e. its coastl agglomeration,having absorbed a large part of the migration. These processestook place in the period of intensive changes in the population economicstucture (declineof agrariancomplex and loss of rural population)and consequent changes in spatial distributionof the populationin widea gravitationalzone. In the decade between 1971 and 1981 the population growth continued, however at a lower rate. The populationgrowth rate decreasedfrom 2.3 per cent in the period between 1971and 1981to 1.2 per cent in the periodbetween 1981and 1991.This is very importantbecause such a trends leads towards a gradualrestraining of excessivegromwth which has alreadyresulted m overpopulation in the area Table2.20. Population according to censusesin the peidbetween 1857and 199. Year Kastela Solin Split Trogir KastelaBay_ % in Croatia 1857 9,540 13,407 14,545 8,682 46,174 2.12 1900 13,124 18,486 26,208 12,847 70,665 2.24 1948 15,806 24,318 57,022 17,511 114,657 3.03 1953 17,038 23,955 67,827 18,549 127,369 3.24 1961 20,125 25,445 87,303 19,111 151,984 3.65 1971 24,626 27,797 133,048 18,480 203,951 4.60 1981 28,550 27,105 180,571 19,856 256,082 5.56 1991 32,286 27,402 207,147 22,168 289,003 6.04
Some studies, done before aggressionin 1991 and significant socioeconomicchanges, are predicting a further increaseof populationin the area to reach 376,000 in the year 2011, and 415,000 in the year 2025. After the trntion changeshappened in the last five years it is very difficult to predictthe fiture developmen in the area. It would need sometime to settledown presentdifficulties in the economyand relatedconsequences in the society. 2.4.2. Present and planned land use Figure 2.17 showsthe plannedland use of the widerarea of the Kakela Bay. The largestpart of the coastalstrip is devotedfor the settlementsand recrion. Area for Touristicdevelopment is also very significant Comparingthe planned land use with present land use it comesout that tourismand recreationare receivingmuch more importancethan in the past New tourstic zones are planned in Kastela between K. Luldi6 and K. Kambelovac,on the southwesternpart of tCiovoisland and westwardof Stobre6. The planned submarineoutfall in Stobrecis locatedin betweenthe existingand plannedtoursitic zone, while the Mavariticaoutfall is locatedin the vicinity of the plannedtouristic zone on the westen part of Ciovo island. Both treatmentplants are located in the vicinity of existing or plannedsettlement area of low density. The plannedmain sewer collectorsin the Kaftela,Solin and Trogirwill be placedin a settlement area of low density,while in Split will be placedmosty in an industryand servicesarea.
99 RAZVOJA X~A 0 N C E P CIJ
GtLA _ __ F.R ______
A 0 0 I ri li4 pDKosmed IN
K
yamjena povr.ina
R A oB 2 Veli Kaknjrok oca PROMETNEPOVREINE~~~~~~~~~SLITSTR CENTRITURIZAM. .::.:~~~~~~~S:.: SPORT A I Z L VEDRIK 0.M. DRVENlh( R - CRI
g 2, 0 D ;>oMoeXenor0rud<1
D i e0SoOLtA C'->Siiprnsvo >'jj <
ESLATCJKPDUJ Ilililill SERVICEOE, |||||~*fl* INDUSTRtJA UZMORE < STANOVANJE // rzARE POLJOPRIVR1EDA RMTEPVSN I JAVNE PovRA INS INDUSTRIJA RE >z STANOVltNJE ZONE AGRICULTU ANDPUurLc USES 1111 INDUSTRIAL HOUSINO GRANICA GRADESK AGLO4ERACtJE RECREATIQIt TOURISMNlSPORTS_ CENTRE "' Fig. 2.17. Planned land otse in fl arean 3. LEGISLATIVE AND REGULATORY CONSIDERATIONS
3.1. NATIONALLEGISLATIVE - - An umbrellalaw in the field of environmentis "Lawon the Environment'which passedin the Parliament in 1995. Different sectonal laws deal with specific subjects relevant to the environment The Law on Waters,among other subjects,deals with pollutionprotection of the sea from land based sourcesof pollution.In accordancewith the law provisionsa criteriafor the classificationof coastal marine waters, as well as regulations on maximum permissible concentrationsof dangerousand other substancesin industrialand urban wastewatersbefore discharge into a natual recipient should be developed. Until the new regulationswill be adopted, old regulations are still in the force. According to the Regulations on Water Classification(NN 15, 1981) coastal marine water could be classifiedin four categories( I categoryfor shellfishculture, II categoryfor bathing,recreation and water sports,m category for fisheries,and IV categoryfor harbor). The classificationof coastal marinewater couldbe done in the compliancewith 11 parameters (Table 3.1). Table3.1. Parameters used in theclassification ofcoastal marine waters Parameter I It m category IV category category category Suspendedmatter (mg/i), 10 20 60 no more than NVB colifoims/l, 100 5,000 200,000 - no more than Dissolvedoxygen (% of sat) 70 60 40 20 pH 8.1±0.2 ±0.3 ±0.3 ±0.4 Degreeof biologicalproduct. oligotroph. oligotroph. oligotroph eutrophic Visiblewaste without without without without Temperatureincrease (eC) 0 2 3 12 Oil, crude oil, refined petroleum 0.05 1 10 100 products- ona surface(mg/I) Surfaceactive substance 0.05 1 10 100 (miliequivalentsT_X-1I0011) II Radioactivity(Bq/l) .1Total radionucides should not exceed the maximal
. allowed concentration of alpha-0.1, beta-l.00 Dangeroussubstances Shouldbe not present at concentrationhigher than prescribedfor each category
By the Regulationsof Maximum PermissibleConcentrations of Dangerous Substances in Freshwaterand CoastalMarine Waters(NN 2, 1984) the maximumpermissible concentrations (mg/dm3) of dangeroussubstances for eachof the water categoryare prescribed.According to the same Regulationsthe concentrationsof dangeroussubstances in waste waters at marine outletscould be 200 times greaterthan valuesprescribed for coastalmarine waters.
101 At the mgionallevels still is in forcethe Action Plan for WaterProtection from Pollutionof the Split Regionwhich prescibes the maximumpermissible concenaton of dangeous substances which may containwaste waters to be dischargedinto a public sewer system(Table 3.2). Waste waers enterig a public sewer ystem shouldnot contai: ilammableand explosivesubstances; noxious gases (H2S, S02); nitrogenoxides, HCN, chlorine, etc.; waste wates from hosptals, slaughterhouse,veterinary stations and similar which were not disinficted before discharge; solid and viscosesuch as: as*, sludge, metal scrap, plastics, wood, glass, feather,-hair, meet, chemicals, etc.; acid, alkaline and aggressive substances;other noxious substances. pH of industrialwaste water should be not less than 5.5 and more than 9.5. The dischargeof industrial wastewaters mtopublic sewersystem or coastalwaters is allowedonly after the pretreatnentin accordancewith an authorizationfor discharge. Table32. Maximumpermissible concentration of dangeroussubstances in wastewater to be dischargedin a publicsewer Supstance Concentrationmg/l settledmaterial 20 suspendedmatter 200 BODs 300 COD 500 total oils 40 mineraloils 20 phenols 0.5 Crtotal 2 Ca Zn 2 Ni 2 Fe 5- Pb - 0.5 Cd 0.5 cyanides 0.5 - - anionicdetergents 10 - _ nonionicdetergents 10
cationic detegents 5 - radioactivesubstances 4x10-12CiMl
The qualityrequirements for bathingis prescribedby the regulationson qualitystandards for sea waterat marinebeaches (NN 33/1996).The qualityrequirements are given in Table3.3.
102 Table3.3. Quality requirements for bathing water Parameters Limitedvalues - Methodof determination I.Colour - natural- ---- visual inspection 2. Transparency(m) mmimum2 (depending Secchi'sdisc .______on depth) 3. Visiblefloating materials without visual inspection 4. Visiblemineral oils no film visibleon the visual inspection surface 5. Suspendedmatter without visual inspection 6. Turbidity(degrees of the silicate 20 comparisonwith the standards, scale) and turbidimeters 7. pH') 8.1±0.3 pH meter, colorimeter 8. Dissolvedoxygen (% of saturation) 70-120 Winlders method,electrochemical method 9. Ammonia(mgll N) 0.1 phenolate method 10. Total coliforms/ 100ml 500 (80% of samples) a) NBB5)35-37 0C 1000(20 % of samples) b) MF4)-selectiveagar 35-37°C 11. Faecal caoliforns/ 100ml 100(80 % of samples) a) NBB'J 44.50C 200 (20 % of samples) b) MFs43elective agar 44.5°C 12.Faecal streptococci/ 100ml 100(80 % of samples) a) NBB-) 35-37°C 0 13. &_te ______. 200 (20% of samples) b) selective gar 35-37C 13. Enterovinjses') PFU5)10I- 14. Salmonedla) 0 concentrationby membrane isolated/lof water filtrationand inculationon selectivemedium 1) lowerpH values can be tolerated in case of lower sality due to freshwaterdischarge. 2) perfonned only in the case of existng pollution or epidemology on special request of responsible health authority. 3) NBB - most probablenumber 4) MF - membranefiltration 5) PFU - ineffectiveunit The sludge could be used in agriculture, but in accordance with the Regulations on the protection of agricultural land from pollution by noxious substances (NN 15/1992), but the sludge must be stabilized before the application, and the content of noxious substances should be below prescribed values (Table 3.4).
103 Table 3A. Maximum permissible concentrations of heavy metal and selected organic substnes in dudge (mgfkg dry weight)
Substance------Cocnon mglkg dry weight --
Cd > *-!:-''. ._
Hg -10- Pb _o _ _ S50 - _ Mo 20 As ------20 - Co --- - 100 Ni .- 100 Cu - 500- Cr - 500 - - Zn .. _ 2000 2,3,7,8 - TCDD - - - 0.002 3,4,3',4'- TCAB 0.01 PCB, PCP, HCH (total without lindane), . . triazin herbicide (total) HCB, heptachlor,
endrin, aldiin,and dieldrin -05 lindan 0.1 total isomers DDT+DDD+DDE 0.5
104 3.2. NTERNATIONAL AGREEMENTS Croatia had ratified the Barcelona Convention for the Protection of the MediterTaneaSea against Pollution and Protocol for the Protection of the Mediterranean Sea against Pollution from Land- Based Sources (LBS Protocol) ln the accordance with provisions of the Protocol Croatia is obliged to undertake measures to eliminate pollution of the sea from land-based sources by substances listed in annex I to the LBS Protocol (Appendix 3). Croatia is also strictly obliged to limit pollution from land-based sources into the marine environment by substances or sources listed in annex II to the LBS Protocol (Appendix 3). Discharges of the waste into the sea shall be strictly subject to the issue, by the competent national authorities, of an authorization taking due account of provisions of annex m to the LBS Protocol (Appendix 3).
105 3.3. EU DIRECTIVES Council Directive of 21 May 1991 (91/271/EEC)concens the collection,treatment and dischargeof urban wasw water and the treatmentand dischargeof waste water from certain industrial sectors According to the Directive all Member States shall ensure that all agglomerationswith a population equivalent (p.c.) of more than 15,000 are providedwith collectingsystems f6r ban waste water at the latest by 31 December2000. For urban waste water discharginginto receiving waters which are considered'sensitive areas"Member States shall ensure that collection systems are provided at the latest by 31 December 1998 for agglomerationof more than 10,000p.c. Urban waste water entering colecting system shall beforedischarge be subjectto secondary treatment or an equivalenttreatment at the latest by 31 December2000 for all dischargesfrom agglomerationof morethan 15,000p.c. Urbanwaste water discharginginto sensitiveareas shall be subjectof treatmentby 31 December1998 at latestfor al dischargesfrom agglomerationsof more than 10,000p.e. Urban waste water discharges from agglomerationsof between 10,000 and 150,000p.e. to coastalwaters, identifiedas less sensitiveareas, may be subjectto treatmentless than secondary level providing that such dischargesreceive at least primary treatment and comprehensive studies indicate that such dischargeswil not adverselyaffect the environment.In exceptional circumstances,when it can be demonstratedthat more advancedtreatment will not produceany environmentalbenefits, dischargesinto less sensitiveareas of waste from agglomerationsof more than 150,000p.c. may be subject(which need to be approvedby the Commission)of the same way of treatment. Only technical problems can be accepted for a longer period for complyingwith the abovementioned deadline, but the longerperiod may not extendbeyond 31 December2005. In accordancewith the Criteriafor identificationof sensitiveand less sensitiveareas, sensitive areas are, inter aha, coastalwaters which are foundto be eutrophicor which in the near future may become eutrophicif protectiveaction is not takn, and areas where farthertreatment than secondary is necessary to fulfill Council Directives-A marine water body or area can be identified as a less sensitivearea if the dischargeof waste water does not adverselyaffect the environmentas a result of morphology,hydrology or specifichydraulic conditions which exist in that area. the following elements shall be taken into considerationwhen- identifying less sensitiveareas: open bays, estuariesand other coastalwaters with a good waterexchange and not subject to eutrophicationor oxygen depletionor which are considered unlikelyto become eutrophicor to developoxygen depletion due to the dischargeof urbanwaste water. Urban waste water treatment plants should be designed, constructed and operated and maintained in order to comply with the requirementsof the directive and to ensuresufficient performance under all normal local climaticconditions. When designingthe plants,seasonal variationsof the load shall be taken into account The dischargeof industrialwaste water into collectingsystems and urbanwaste treatment plants should be subjectto prior regulationsand/or specific authorizations by the competentauthority or appropriate body. Industrial waste water entering collecting systems and urban waste treatmentplants shall be subjectto pre-treatmentin orderto: protect the healthof staff working in collectingsystems and treatmentplants; ensure that collectingsystems, waste water treatment plants and associatedequipment are not demaged;ensure that the operationof the wastewater treatment plant and the treatmentof sludge are not impeded;ensure that dischargesfrom the
106 treatment plants do not adversely affect the envirnment, or prevent receiving water from complying with other Community Directives; ensure that sludge can be disposed of safety in an environmentally acceptable manner. Sludge arising from waste water treatment shall be re-used whenever appropriate. Dlsposal routes shall minimize the adverse effects on the environment. Competent authorities or appropriate bodies shall ensure that before 31 December 1998 the disposal of sludge from urban waste water treatment plants is subject to general rules or registration or authorization. The disposal of sludge to surface waters by dumping fiom ships, by discharge from pipelines or by other means should be phased out before 31 December 1998. - Competent authorities or appropriate bodies shall monitor. discharges from urban waste water treatment to verify compliance with the requirements of the Directive accordance with the control procedures.
107 4. DETERMINATION OF THE POTENTAL IMPACT OF THE PROPOSED PROJECTCOMPONENTS -
The mamn positive impact of the planned -sewer system and submarine -outflswill be eliminationof pollutionby urbanwaste water from the Kastela Bay and TrogirBay. The Bays are semienclosedand in the accordancewith Criteia for identificationof sensitive and less sensitiveareas of the Council Directive(91/271/EEC) concerning urban wastewater treatment their could be consideras a sensitiveareas. Recoveryof the KaktelaBay will take sometime, which is impossibleto assess because of lack of dat. For sure, the Bay will become very inportant resourcefor furtherdevelopment, specially tourism. The eliminationof pollutionfrom the bayswill improvethe enviomental qualityin the whole area. The plannedsewer systemsin the firrstphase (pretreatment of the urban waste water only) will trnsfer into Brac and Split channelspractically all the wastedischarging at presentinto KIatela Bay (Figures4.1., 4.2 and Table4.1). The performed assessmentsand numerical model show that the two wastwater outflls will have no significantlynegative effects on the marine ecosystemsin Brac and Split channels,nor on the present and planned use of the coastl sea and land strip in the areas neighboringthe outfalls.Some local changes are expectedin the iumnediatevicinity of the outfalls. Since the wastewatertreatrnent plant is plannedto be built in several phases,it is necessaryto implementa comprehensivemonitoring program of effects on the marine ecosystemswith regard to the presentand planneduse of the coastalsea and land strip, in orderto enablea timely decisionon a higherdegree of treatment,as required. In order to make proper decisionsregarding necessary treament and improvementof collecting system ComputerizedDecision Support Systemsin CoastalWater ResourcesManagement have to be implemented.This systemwill aid decisionmakers in the process of transformingdata into necessaryinformation to solveunsetctred problemsof coastalwater qualitymanagement
108 Contributionsto the polutionof Kastcla13ay Contributionsto the polutionof Kaltcla Bay in 1995. in 2005.
4000000 4000000
35000Oo 3500000
3000000 Trro8tir 30t)0000 Kngtlel 1'wjtiW
3200000 K 25 300000026 2 S
2000000i ' SotItil 2000tt000 : Sil
1{500000 IISS73S 4 500000 9
1000000 7Iooooo
300000 300000- 243667
0 45385 _ 30348| | | 440421 6285 i Split Solin KiRlicin 'rmgir Spli Solinl , Knitlcn Th,nir
Figure 4.1. Present and planned domestic pollution load by BODS Into Kaltelabay
109 Contributions to the polution of l3ra&-SplitChannel Contributions to the polution of BraM.SplitChannel in 1995;. in 2005.
6000000 6000000
50000 0 5oOOD00 4693631 l'roeIs1%Kdelar
4000000 0% 4000000 , ^ 341t __ 11111 _ ) s _ .~~~~~~~~~~~~~~~~~~~~~~~~~Solln111 9% 3000000o l l 1 0 Spl I 300coDo 0 I 1E99% 700
20000D00 20000C0
1000000 1000000 576612 c91049
0 4S393 oj* s - 43s. a Spit Soli,l Knltola Troir Splil Sollo Kniela Trogir
Figure 4.2. Present and planned domestic pollution load by BODS Into Bral and Spilt channels
110 Table 4.1. Present and planned population and domesticwastewater pollution load by BODSfrom Split, Solin, Kaitela and Trogir Into Kaltela Bay, Troglr Bay, Bran and Split channels
Town Populaton Winter Suimmer Whiter Suimmer Yeat Winter Suimmer Year Witier Snicr Year tirsummier Year
Spolt torss 4000 151 600 30 4000 60 36.0 .'240.0 31620 90 - 32.4 210.0 3385 tO 3.6 24.0l 3762 0 0.0 0.00
SolIn torists tO 01 0 30 O 6 . 0,6 72 0 .0 0.0 01001 0.0 0.6 72 . 0.0 0.0 0l total . . 2000 . ~20010 198160 20. 188,6 4366320 00 0 .0 1200.0 1188.6 4366 2 0.0 0.0 _ _ 0 Inhbtnts 3140 100l 140 9 3 86 6 380 4 865.2 685 99 0 0.0 . lbOG 168. 1865.2 685399 0 0.0 .. 0 Kalites Io is 5000 10 50100 500 6 30.0 .300.0 43350 0 0. 0. 3001 30. 3000 43350 01 0.0 0.0 0 total6400 . 31900 6086 1914.0 .2365.2 28749.2 0.0 0.0 00 1914.0 2365.226.2 7287497879a 0.0 . 0.0. 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0 Iihhsbitsnts 310 19700 991 93953 60 3,.lj82A.01I70.2i 430012 01 I318.2 II. 4300 3 1Q8. 337.0 43001 80 . . 3. 344009 Trog3r tourists 5500 5 300M0l. 5500 60 1 ~33.0330.0 47685 5 37 5 3 F4 51 1.7 .65 2384 901 29,7 . 297.0 42917
Inaiatsfl3 : 820 22209 8 16. V69 2 6. . 893 636.7 =.0 231639<6 96 4 Total tourits 141 60 3509. 7, 28727 34.31 2 235 36242 353 43 49568 29.7I -297.0 429171
Trown Poulation Winter Sumimer Winter Summer Year Winier Summer Year Wtner Sumtmer Year Whinier Summer Year
SpHit tuit 6800 15 1020 10 680 60 61.2 4.0 63954 30 632 408.0 394 0 0.0 0.0 0 0 0.05 0.0
oln toutsl 2300038003000 026006.0 60.00867 95595182.7 5792.0 823 67032 065. .. 4346 0 0.0 0.0 0
ialehatoristts 87500 30.8275030 -9 295008 60 151.0 5307.0 739191 53484 5670010 51 2.6 25.5 36815 0 .0.0 0.0 0
Trogir tourists 850 30 85 300 8500 60 53.0 510.0 7395 95 485 78.5 70070 0.3 5.3. 7374 2.0 touital 248500 ITtl 28200 24800 356.2 6406220.04 36.8 149342561.02322 .4 33.6 48559 .. .0 20.4 . 94 itolaltts 376 )22.0 291.3 05714 38T1.7 27.4 76709 8. 97.3I 442 .0 .1 3
looRX)37166981 36358 40357~Il 4.1. IMPACTSDURING CONSTRUCTION 4.1.1. Collectingsystem, treatment plants and tunnels Colectine vstem The pipesof the sewer systemwill be mostly buriedand partly placed in ihetunnels (two main tunnels with total lengthof cca 3400 in) Duringthe trenchingto bury the pipes machineryand vehicleswill producesubstantial noise and dust,which will disturbneighboring population. The noise will be much more intensive on liovo island duteto rocky ground, and much more importantsince this area is very quietwith residentialor summerhouses, withoutany economic activity. The impactson local populationand tourists will be more significantduring summer season when numerous summer houses located in this part of the island are occupied by numeroustourists. Trenchalong roads will disturblocal traffic and in some caseswill block accessto somehouses. This type of impactwill be significantin the older parts of the towns (especiallyin Trogir old city and Kastela)where roads are traditionallyvery narrow. In this area constructionof the pipelines will be very complicatedbecause excavationcan endangerstability of houses.This will have influenceon the preparationof the work and increaseof cost of the work It will, also, at most places be required to replace existing undergroundinstallations (water pipelines, telephonewires, etc.). In this case a certainnumber of householdswill be tempormywithout servicesof runningwater, electricity or telephone. In same time the earth works will impact pubhicservices and local shops activitiesalong the place of work.This impactwill be commonwithout any specificcharacteristics. Connectionsof existingsewer pipes with the new constuctedmay lead to the leakageof urban wastewhich couldcreate health hazard for workersand localpopulation. Earth works will not significantlyaffect neither flora and fauna of the area becausesewer are located in the urbanizedareas. Constructionwill not impact the flow and characteristicsof groundwaters, but the flow of srface waters(draiage waters and sporadicwater flows)will be disturbedin the area of KaAtela. The constructionof transmissionmain will not endangerknown historicmonuments but in the area of Sohinit could happenedthat on the route of pipelinessome so far unknownarcheological monumentscould be found.In accordancewith transmission mains projects the pipes will be not laid down in the ecologicalsensitive areas. The rising mains of pump stations Divulje-Pantanaand Lokvice are designed to cross the Kaftela bay and will be buried and concreted.The trenchingthrough KaktelaBay will produce turbidity, caused by clay and sand particles.This, however,will not last a long time, no more than one week after accomplishmentof the work, and will cause no sigmificant changes in plant and animal communitiesof the Bay. The communitieson the place of the rising mains will be completelydestroyed, but in severalyear time they will be recoverd. The taenchingthrough the Bay wouldhave negativeinpact on juvnile orpisms of commercialimportant species, if any retain in this part of the bay. During the constructiontraffic in this part of the bay may be temporarydistubed. - hnpacts of the constructionof pump stationsand storm wateroverflows will be similar to-the impactsof tranmission mains.The locationsof pumpstations and overflowshave been chosen taking in consideraton local charcterstcs whicb could createdifficulties in the construction.
112 Treatment Dwants The construction of both treatment plants will create noise and dust by earthworks and intensified road transport Civil engineering works at the treatment plant will have impacts as any other typical construction,work. The most significal impact will have traffic to and out of const-uction site. The impact of intensified road transpozt will be much more important on tiovo island because this area is very quiet area without heavy trAffic and noise. A special problem will be Mavascica area. At the Stupe area there will not be significant impacts because in this are heavy traffic is common. At the Stupe location construction of the plant will require replacement of existing small creeks. In the rain period of construction it is very probable that rain nmoff over the construction site will wash out materials and caused increased turbidity of Stobrec bay and Mavak;ica bay. This impact can be temporary significant on aesthetic and ecological characteristics of the sea water in the bays. It will impact bottom communities. Surplus excavation mateials could be used for sanation of existing left quarnies in the area or for earth work in the area when appropriate. The quality of excavated materials can be of good quality for civil works and beneficial uses. At the location Stupe there are electric overhead lines which have to be relocated. On the site in the southern corner there are several houses which have been illegally constructed. These houses will not impact preliminary work but can impact extension of the treatment plant in the future. The location Ciovo do not have such problems because it is natural green area Tunnels The size of the tunnels (Stupe 2436 m, Ciovo 1851 m) and complexity of the work as well as possible impacts require the preparation of specific environmental impact assessment study. This study is prerequisite to obtaining a Location Permit in accordance with Croatian legislative. The construction of the tunnels will have a significant impacts on local and wider areas with respect to noise, dust, traffic, vibration, visual impact and disposal of excavation materials. The amount of excavated materials will be very significant (Stupe 38500, tiovo 20500 m3). This material can be used locally for fill platform at treatment plant site (tiovo), filling of quarries or for beneficial uses. Impacts of construction Ciovo tunne will be significant on both portals but much more important at south portal in Mavascica area especially regarding traffic inpact These impacts will be less significant at the Stupe tunnel. 4.1.2 Submarine outfalls The outfalls are not located in ecological sensitive areas or ground of endanger and protect species. Since the part of Stobrec submarine outfall is designed to be buried and concreted, trenching through Stobrec Bay will produce turbidity, caused by clay and sand particles. This, however, will not last a long time, no more than one week after accomplishment of the work, and will cause no significant changes in plant and animal communities of the entire Bay. The communities on the place of the submarine outfall will be completely destroyed, but in several year time they will be recovered. The trenching through the Bay would have negative impact on juvenile organisms of commercial important species, if any retain in this area.
113 Tbe consruction works at the inner Stobre6bay will be significant(big size of the pipe 1000 mm and big escavationwork) and will createtemporary local problems in use of the sea in this ama.Dragged material (ca 1500m3) bave to be disposedat the appropriatedisposal site. The constructionof the submarineoutfall at Ciovo island (0 500 mm in first phase) will not crate burbidyas the Stobre6outfall, but it will createmuch more noisebecause of rockyground. Tne lay down operation of the both outfills will affectthe navigationof pleasureboats in the area of activityin a short time period. The submarne outfall on tiovo island will hamper trawl fishing in the area of submarne outfall,while sardines and anchovies fishingwill be mot affected.Stobrec submarine outfall is alreadyin the trawl fishingforbidden zone. Assemblingof the pipe and preparation work for laydlown(pressure testing, attaching of concreteloads, etc.) will have localimpacts. It is not knowa wherethis workwill take place and there for it not possible to asses impacts.It seems that MavascicaBay becauseof the size and oast line configurationis not sutable for suchactivities, wvile Stobre6bay issuitable. -
114 4.2. EIPACTS DURING THE USE 4.2-1. Impacts of the sewerage system and the wastewater treatment plants The treatment plant tiovo have a size of 110 x 200m and its location is about 250 m fare from neighboring house, but if necessary it could be relocated to be more than 300m. Location is on the level of 15 to 20 m over sea leveL The treatent plant Stupe have a size of 190 x 380 m and it is located ca 100 m from the closes houses. At the southern corner of site location there are several illegally constructed house. Location is on the level of 13 to 10 m over sea leveL Imiacts on the air aualitv Easily volatile gases of very intensive smell occur in wastwaters. These odours occur particularly at anaerobic state of the effluent Do to emnissionof unpleasant scented substances at the waste discharge facilities, undesirable changes of air quality are possible:
- in the operating environment of the waste waters treatment plant in particular the preliminary works, where potentially septic waste water is first broth to the site. This include Reception Chamber, Inlet Channels, Screens, Aerated Grit/Grease Channels, Cess Tanker reception screenings
- in the facilities surrounding but much less. the distribution of unpleasant odours in the facilities surroundings is affected not only by the type and intensity of the scented substance but also by wind direction and intensity. At the entrance to treatment plants the unpleasant odours are possible due to the processes of anaerobic degradation in the sewerage system, that is under the conditions of oxygen depletion in the effluent In our cases this is possible owing to the increase of soil and shallow trenches temperature in summer. This means that the water temperature increase may accelerate the process of organic matter degradation and consequently the rate of oxygen depletion in the water. This problem is particularly pronounced in this case since the water is conveyed over a long distance. Odour is a highly individual perception and its measurements requires a panel of test persons an a rather laborious test procedure. Therefore, it is very difficult the assess odour impact from the waste water treatment plants on neighboring population. But, considering the locations of both treatment plants in relation with the neighboring population, it comes out that the locations are not suitable regarding the predominant nightly winds in ihe warm period of year. Unpleasant odour problems can be created at the pump stations and impacting neighboring population. Noise and Vibration There will be limited equipment at the treatment plants that will emit significant noise, like: aeration blowers and power generation plant using biogas. Vibration may occur in the rising mains and partly not in the teatment plants, such as the air blowers and power plant Vibrations in the outfalls are due to air penetration in the pipes during emptying and filling of the sewer. This is of particular importance for the safety of the
115 polyethylenepipes, since vibrationsmay causeconcrete blocks to unfastenand let the submarine part to lift up to the surface. Leakaee There are a possibilitiesof smaller breaks and leakage ofjoints elementsof the pipes and channelswhich would causethe polution to the ground. Such leakagewould produceharmful sanitaryand ecologicaleffects. The extent of these effectswould mainly depend on the quantityof leaked water. In the case of smaller quantities the effectswill be insignificant At this stage of the planningprocess it is impossibleto assesthe importanceof this impactbut it shouldbe avoided. This impact can be very important for Kaltela area because of usage of ground water for irigation. In coastalbelt the leakagewill pollute coastalmarine water and endangerusage of this water. leakage from the treatmentplant Stupe and incomingand outgoingpipes can significantly impact river 2rnovnicawhich is claified as I categoryof water quality. Impacts caused by insectsa Sewageeffluents and the wastesubstances they containare very suitablehabit for insects(flies, mosquitoes,etc.). Exposedsurfaces are particularlysuitable. Since sewage effluents contain also pathogenicmicroorganisms the insectsare particularlydangerous as disease camers. Becauseof the regularityin anti insectsactions this kIndof impactcould be consideredas negligible Imnacts due to the 2eneration of combustiblegases Gasesmay occur at any point in the systemunder anaerobicconditions which are feasiblein our case because of long trawsportof watewater.This particularlyapplies to the spaces closed to prevent unfavorableodours to disperse. If these spaces are not properly aerated they present potenbal hazard for explosion.This kind of impact could be avoided by appropriatedesign, constmctionand maintenanceof the sewersystem and treatmentplants Fire hazard on treatmentplants are only relevantto sludgedigestion process and relatedhandling and use of digestorgas. Traffic movementsat the treatment ulants There will be significantnumber vehicle movementsduriag the normalworking day. This will include cess tankers deliveringwaste to the site. This will be very significantduring the initial faces of the developmentof the sewer system, but in the latter developmentof the treatment plants there will be significantsludge tacks takingsludge eak of site. At the treatment plant Stupe the main access route to the plant will be via the proposed industrial/warehousingdevelopment area and traffic willn ot cause problems.At the treatment plant 6iovo the existing road to the locationcoming through Mavascicavillage which is not appropriatefor this type of tranwort,and anotheraccess road shouldbe found. Aesthetic impacts The significantaesthetic impacts will have Thetreatment plant will have the significantaesthetic impactswhile major pump stationswill have only minor impacts. Otherelements of the system won't have any impacL
116 The proposed plants stuctures consist manly of low buildings and tanks many of which will be located below gromundleveL The tollest structures will be vent stacks from odour control, biogas flaring and power generation exhaust chimmey. This stack: will be about 10 m above ground leveL Aa -the (tiovo reatment plant is located deep in valley it Will not be visible from the village Mavaikica or any local road. Treatment plant Stupe will be visible but as it is located in industrial/vwhorehousearea. There for this structures will not have any significant aesthetic impacts. Health hazard Health hazard to the local population from any of the component of the sewerage system (transmission mains, pump station, treatment plants) is negligible (distance from the houses more than 200 m). The only one how can be impacted are the workers especially at the treatment plants. Problem erase when workers are in contact with row wastewater. Another problems are entry to confined spaces in the system (transmission mains and pump stations) and at the treatment plant Solids disposal Solid waste associatedwith treatment works will consist of: screenings, grit and sand, grease and oil, and biosolid sludge cake. These solid waste will have impacts on environment depending on the way of treatment and disposal. For the first phase of treatment plant development it is proposed to instole a small incineration plant for the incineration both screeningsand grease and oil. If a modern incineration technology would be used then the exhouse gases will not represent an environmental nuisance. Other option is to damp waste of the first phase to the municipal landfill site. Grit and send after removal organic materials within them will not have any significant impact on environment and can be used for landscaping. In the second and further stages of treatment plants development a significant amount of sludge will be produced. The sludge will be digested at the treatment plants and will have long term stability. If the sludge has a good quality than will not have negative impact on environment and can be of beneficial usesin agricukure or silviculture. Such sludge can be also dumped on landfill site if necessary. Quality of the sludge is directly related to quality of the wastewater inflow to the treatment plant The problems are created mainly by industrial wastewater discharged into sewer system containing toxic and hazard substances. Any heavy metal present in wastewater will concentrate in the sludge produced on the works and jeopardize the beneficial use of the sludge. The use of polluted sludge in karstic area, as it is Kagtela Bay area, is very dangerous for the pollution of fresh and marine environment Because of restructuration of local industry it is in this time very difficult to predict impact of the industry on the sludge quality. Adequate agricultral areas in this region exist for beneficial uses of sludge. Since the local population and farmers are not familiarize with beneficial uses of the sludge at the beginning the will be resist to the sludge application.
117 Confirmation to existint and ,lanied land use Cbaacterstcs of location area of the treatmnt plants are described m Chapter I of this report As it was present the locationof .Stupetreatment plant is Alreadyplanned for the onsruction of the plant and because of that is not in contradictionwith land use plan (master plan) The treatment plant liovo is planned on natural greo area but it is not in conflict with other uses of land. This are (deep in valley) is not suitablefor any beneficialuse of land (nanow and step area). Some prblems might erase becmse of vicinity of neighboringMavaitica village. Distancefrom the first housesis 250 m. 4.2.2 Impacts of the submarine outfalls The main direct environmentalconsequence of a sewerageoutfill is the contamintion of the recipientwaters with raw faecalmaterial (in case of untrated or inadequatelytreated sewage), intestal microorganim (mcluding pathogens), nutrients and other oxygen cousuming substances.This consequencesof wastedisposal may be: - reducedquality of recreationalcoastal waten; - oxygen depletion and eutrophicationof recipient watas, including excessivealgal blooms and fish kills under extremeconditions; - alternationsof marineecosystems in the vicinityof disposalpoint; - spreadingof pathogens by wind. Phase I installation at the treatment plant anticipatedpreliminary treatment only. The key requirementfor this phaseis tbat there shouldbe ""no visible slick"on the sea surface.Phase I includesthe installationof a primy treatmentprocess. This will substantiallyreduce suspended solids together with associatedorganic mater. In Phase m the quantity the waste water treatment by the plant increasedand the quality of marine eviromnent could be decreased. Therefor,it may be becamedesirable to treat the wastewaterto an unprove standard.Tis may be catried out m severalappropriate steps: - ganic reduction, - desinfectionof effluent, - ammoniareduction, total nitrogenreduction and phosphorusreduction. The HARO-3three dimensionalstationary model developedby USA-EPAwas used to predict impact of the submaine outfills on the oxygen concentrationin the marine environment (Appendix2). Sea water temperature Sewage effluent disposal in ihe wider area of Brac and Split Channels will not cause any changesof the sea water temperature. Microbial pollution of coastal marine waters The distanceof the outfallsdisposal point from the coast vwerecalculated for the first phase of water treatment development (pretetment of urban waste water only), using some basic charactristics of the sea water, such as physicalproperties, prevailing curents and die-offrate of bacteria. On this basis it may be predicted with relative high probability that microbial pollutionwill not be increasedm the coastalstrip intended for recreationalpursuits (Appendix 1). If a secondary treatment including the UV desifection of the effluent is appliedthe probabilitylevel will be mucb higher.
118. The transfer of urban waste water from Kagtela Bay into Split-Brac channels and elimination of all existing small outlet and septic tnks (by development of sewerage system) will improve sanitary quality over the entire area. The expected sanitary quality of coastal waters in the area is shown on Figure 4.3. Oxvgen and nutrient concentrations The preatreatment of only the urban wastewaters is envisaged during the first stage of construction of waste water collection system. These waters which will be conveys through the outfall will contain large quantities of suspended matter (180 mgll), the degradation of which will require high oxygen amount (BOD5=180 mg/l): A considerable part of suspended matter will sedimnentin the vicinity of the disposal point, whereas the rest will be spreaded to a wider area by currents. In the first phase of treatment plant development significant oxygen depletion will occur on the bottom close to the disposal points especially in sunimer and early autmnn due to the organic degradation. However, anoxia is very unlikely to occur owing to relatively favorable currents in the bottom layer. Oxygen content reduction will not be significant in the wider area of the Brac and Split channels. In winter, oxygen concentration reduction will be very poor. During the third phase the organic matter will be removed fom effluent and oxygen depletion will be much lower. In the second and third phases of waste treatnent plants the organic effect of the waste water will be reduced and any solids deposition in the vicinity of the outfalls diffuser minimized. Long-term discharge of municipal effluents, regardless on treatment level, will very likely cause increase of nutrient concentations which will later affect moderate changes in phytoplankton and zooplankton populations and consequently the changes in primary production. The important of this impact impacts is impossible to predict there fore a comprehensive monitoring program was proposed. All above mentioned impacts of effluent discharges will be much more less intensive at the vicinity of tiovo outfal due to smaller amount of watewater discharged (equivalent population Kastela-Trogir system at final stage ca 150,000, while Stobrec ca 500,000), higher depth of discharged (tiovo outfall 52 m, Stobre6 outfall 36 m) and assimilative capacity of Split channel. Sea water color and turbiditv Waste waters will increase turbidity in the vicinity of the outflls discharge which will limit the light penetration. Whereas these changes will mainly occur in deeper layers in summer, they will occur through the water column in winter even though of far smaller extent Waste water discharge will also cause the sea water colour change to a green yellowish. However, this discolouration will not be visible in the surface layer in summer due to stratification. This impacts will much more pronounced during the first phase due to high suspended particles and associated organic matter content in the effluent, while during the third phase wil be practically eliminated. This impact will be of less intensive at Mavascica submarine outfalL A gradual transparency reduction and change of the sea water colour will presumably occur as a secondary effect of nutrient content and primry production increase in the wider area
119
F~~~~~~~~~~ l COASTALWATER CATEGORY: _ I category _ It category HI category w$0U IV category
0 . S. A §~ T E LA
.Figure 4.3. The expected sanitary quality of the coastal waters In the area
120 Flora and fauna Disposal of municipal waste waters will affect flora and fauna of the wider area of the outfall. In the first place, the number of plant species will be reduced and followed by the species diversity reduction with a considerable increase in the number of nitrophilus algal species. As to the fauna of the wider outfall area, the number of species will also be reduced with an increase in the number of specimens and biomass of individual species. Dramatic reduction of both the number of plant and animal species and their total biomass will occur in the close vicinity of the point of disposal due to the sedimentation of suspended particles from the effluent The construction of the submarine outfalls and elimination of waste water discharge by numerous outlets located will have positive impact on benthic communities along the coast in the area between Stobrec and Rt Maijan. The discharged waste will not reach the coast line and the communities will be recovered. The recovery time to the previous conditions will between 5 to 10 years. The commercial fish species will not be subject of significant impact of discharged waste water. IMpacts on other ipresent and lpotential uses of the coastal and marine environment Discharge of pretreated municipal waste waters will not impair the present quality of coastal sea water. So, its presents and planned uses for recreation and bathing will not be endangered. Construction of the sewerage system in the wider area of the present one, to which the waste vates now disposed uncontrolled into the sea, will be collected for treatment at central ueatment plant, will contribute to the improvement of the prerent state. The Mavascica outfall is located in the area of commercial fishing (trawling) so that the decision to ban this activity in these areas will produce some small impact on this activity. The Stobrec outfall is located in the area where trawl fishing is forbidden. No data are available on the infective diseases so that there is no basis for any estimate of the outfalls impact on their eventual reduction or extension. Since trenching to bury and concrete the submarine part of the Stobrec outfall is proposed at approximate length of 900 m, to the point at which the sea water depth reaches 12 m, recreational pursuits will not be limited in this area. Anchorage, fishing an any other activity that may damage the pipes will be limited but only at greater distances offshore. 4.2.3. Overflows Part of the existing sewerage system in Dujmovaca catchment area is of a combined type. It means that during the rainy period of the year storm water will be discharged by storm water overflows. Only three overflows have been planned. All of them will discharge water in the north port sea which is classified as IV category in accordance with the Croatian law. Discharged water will have impact on sea water quality in this area Study of the analyses of possible impact of overflow water was made as part of the project of sewerage system Split-Solin /I. Based on that study it was concluded that overflow waters can be discharged in the north port sea after the ratio of dilution of wastewaters with storm waters of 1:3 was accomplished. It was concluded that discharge of these waters won't have negative impact on the usage of sea water of the north port and therefore this solution is in accordance with the Croatian standards.
121 Ihis approachis not in accordancewith the EU standardstbat requirethe determinationof the outfall fiequencyand total volume of overflowwaters durng one year period. Thenfre it is necessaryto developsimulation model of the seweage systemwhich will be done in next phases ofthe design ofthe sewerage system. . . -- 4.24. Tunnels - The most importat impact of the tnel wil be on the health of workemsIt is possiblethat withinthe tunnel,that is a closedarea, gases that evaporatefinm sewers(methan) that are toxic and explosivecan be .accumlated.There is a danger for workerslives and dangerof destuction due to explosionunless respectivemeasures concerning the accumulationof gases within the tunnel and measures and proceduresthat should be done before entering the tunnel were undertaken. During the operational period tunnels won't have significant envirornmentalimpact The EnvironmentalImpact Assessment will be undertakenfor this object and therefbrethis problem won't be further discussed.
T-x.~~ ~ ~ -1 .
122 5. ANALYSIS OF THE ALTERNATIVES OF THE PROPOSED PROJECT
Before the selectionof the optimal alternativefor the sewer systemin the wider area of the Katela Bay, several alternativeswere analyzedconsidering the total conceptand the specific elements of the sewer system. Accordingly,extensive investigationsand studies of the characteristicsof the coastalsea and wastewater have been carried out as well as the urban- planning analyses, cLimathologicalcharacteristics, techno-economical analyses and environmentalimpact studies.This process of the selectionof the optimalalternative lasted more than four years.All these analysesstarted from the present state,local, national and international requirements,local characteristics,short-term and long-termneeds, requirementsand financial, technicaland technologicalpossibilities as well as the availablepersonneL The adoptedsolution, and its realizationin phasesis consideredto be optimalfor this regionand for the presentsituation.
5.1. ANALYSESAND ALTERNATIE SOLUIIONS OF THEMAIN CONCEPT Several alternativeswere analyzedat the level of a concept The first analysisreferred to the sewersystem, i.e. eithercombined or separate/I1. Consideringthe fact that the greatestpart of the existingsewer systemis of a combinedtype it was necessaryto decide whetherto keepthe samekind of systemor to build a separatesystem. Consequently,a separatesystem was selectedand the existingsystem will also be transformed into this new type. The separatesystem was selectedconsidering the ecologicalfactors (better control of the disposalof wastewater and reductionof the storm water overflow),economic reasons (decreasein the costs of pre-pumpingand treatment),maintenance and reclamationof the existing system (problemswith significantinfiltration, insufficient capacity of the present sewer system,etc.) In addition,there is no sewer system in a large area coveredby the cities (more than 60%/),so that the separatesystem is more efficientfor the constructionin phases, where the sewer system for fecal (domestic)water is built first and later the storm run-off system. As the result separatesystem was proposedfor seweragesystems of Split, Solin, Kaktelaand Trogir. The secondanalysis referred to the configurationof the sewersystem as a whole. Three basic possibilitieswere considered:(a) unique systemfor all cities Split, Solin, Kastela and one part of Trogir(one treatmentplans and one submarineoutfall), Figure 5.1.; (b) a great numberof small sewer systems(a treatmentplant and an outfall for each large catchmentarea, Figure 5.2.; (c) optimumnumber of sewer systems (most efficient collection,treatment and disposalsystems). Each of the alternativeswas analyzedconsidering several criteria, such as the most important ones: - envixonmentalimpacts, - technologicalefficiency of the system, - functionalefficiency of the system, - exploitationof the system - reliabilityof the systemand - economicalefficiency of the system.
123
@,§T E L A
Figure 5.1. Conceptof a unique sewer system- one treatmentplant
YL A T E L A
Figure 5.2. Conceptwith severalsmall sewer system- several treatmentplant
124 Appropriate study was produced /1/, /5/ and results of the study were discussed between groups of pets and interested institutions and organizations. The discussions were held according to the present state and past experience, obtained data, requirements in accordance with Croatian regulations, -and internfational requirements (Mediteranean protocols and declarations, EU directives). The following conclusions were reached Single treatment Plant Cental treatnent plant was planed at location of Split community because Split is the far the biggest community in the area and collecting waste water at one location in this area have been economically and technically the most acceptable solution. A unique system is the optimal solution regarding environmental impacts because all waste water will be controlled at one location, one treatment work and one submarine outfall. The treated waste water will be discharged in the Brae channel. There will not be discharges in Ka'tela bay from municipalities and industries and full protection of the Kaitela bay from point sources of pollution wiU be achieved. The treatment plant construction, operation and maintenance costs will be minimum (cost per m3 of treated waste water). This alternative taking in account whole sewerage system has been the most expensive one especially in the initial phase of the construction because it will require significant reconstruction of existing sewerage system, construction of numerous pump station and high operation costs of the sewerage system (waste water should be prepumped several times). There are a number of technical objections to the aernative of single treatment plant: The general fall in the Kastela and Trogir area is from east to west and significant pumping would be required (Fig. 1.15.), there is no simple and obvious route for main pipelines from east to west (from Trogir to Split), travel time of waste water will be too long which will result in septicity and odour problems (length of main pipeline more than 25 lon), connection of the settlements in Ciovo would be difficult to achieve ig. 1.16.). Regarding operation, sewerage system will be sensitive to the malfunctioning which could results in occasional pollution of the coastal waters. This alternative has been difficult for the phasing of the system development and construction because it requires, in the beginning period, significant construction, time of constuction and costs in order to start functioning. This is also the least favorable solution considering the existing state and the possibilities for bzinging into accordance the interest of the four cities. Several treatment plants For areas of Split and Solin, based on existing sewerage system and topography (the possibility of collection by gravity), the possible sewerage systems are /1l/: _ the sewerage system of the catchment areas of Dajmova6a and Solin with the waste water treatment plant situated in commercial port area and the belonging submanne outfall for discharge into the Kastela Bay,
- the sewerage system of the southern part of Split peninsula (old city center) with the waste water treatment plant on Katalini6 Bng and the belonging submarine outfal for discharge into the Brad Channel,
125 - the swerge systemof the catchmentarea of Stobre6with the waste water tratment plant situatedat Stupeand the belongingsubmaine outfall for dischargeinto the Brac Channel .and- - the seweragesystem of the area of Podstranawith.the wastewater trcatmentplant situated-n the center of that-area and the belongingsubmarine outfall for discharge into the .Bra ChaneL For the area of Kastela,as a realisticsolution, there has alwaysbeen assumedonly one sewerage system with the waste water treatmentplant situated in that area and a submarineoutfaU for dischargeinto the KastelaBay 15/. Also for the area of Trogir there has always been assmnedonly one unique seweragesystem with the treatmentplant situatedon tiovo Island and a submarineoutfall for dischargein the Split Channel/141. The solutionwhich includes severalsmall sewer systems is optimal consideringthe economic factors of transmissionmains construction(savings in size of pipelines,capacity of pumpstation nd pumpingcosts) and-the present state (no big changesin the existingsystem). It is the least acceptablesolution considering the environmentalimpacts (disposal in the bays). Discharge of effluent m the bays would require full tertiary V treatment to achieve the necessarywater quality in the closedbays. Kaela bay and Trogir bay have been dassifted as a sensiive sea water 13/. As it was presentedin Chapter 2 the easternpart of KaTtelabay was found to be eutrophic.Impacts of the treatmentplant on land environmenthas been significant and it waSdifficult to find so many appropriatelocations for treatmentplants. Construction,operation and maintenancecosts of the tetent work will be significantlyhigher because severaltreatment works would be built resultg in higherunit costs per m3 of waste water and highercosts becae trament levelif effluentis dischargedin the bays. This alternativehas been favorableregarding phasing of the seweragesystem constructionand developmentbecause systems can be developedseparately in shortertime periodwith immediate resultsand improvementsin coastalwater protection. Managementand operation of the system wiUlbe more expensive and less reliable (several operationunits-depots, more staff, lack of exprts and operationalexperience to operate such type of work at the requiredconsistent standards). Optimal solution Consequently, it was conclded to find an optimal solution regarding the economic, envinromenl and other cntenia, so that after an anawss the alternative for the construction of two sewer systems: Split-Solhn and Kaftela-Trogir was proposed and accepted (two plants and two oufalis). Regardingecological impacts, this solutionmakes it possibleto satisfy long-termenvironmental criteriaand the controlof the waste wasters and, hence, the long-termprotection of the Kastela and TrogirBays. With such solutionthere will no be municipalityand industy waste waters dischargesin to the bays (pointsources of pollution).The disposalof the wastewater outsidethe bays makesit possibleto use the assimilativecapacity of the sea in the bays for all diffuse and uncontrolled-pollutants in this area which are and will be significant /31 (storm mnofl agriculturaldrainage waters, fiesh waters fromrivers, air depositand others). This ensureslong- term protectionof the bays with relativelylow cost of the systemsand plantsoperaton.
126 Treatment and discharge of the effluent by long submarine ouffalls into the Brat and Split channels will not jeopardize water quality in the channels although waste water will be treated only mechanically /13/. Study and simulation of the long term effects of discharges of waste water into the channels show that there will no be reduction in oxygen concentration except smal reduction in the vacancy of the diffuser and all Croatian, international ind EU standards can be achieve. The channels have good water exchange and are not subjected to eutropkication and can be classifed as less sensitive areas. Results of simulation are given in the Appendix 2. In order to protect sea water and performance of treatment works treatment of industri waste waters at production site has to be instituted and trade effluent policy kas to be established exceptfor biologically degradable effluent& It is necessary to pay special attention to heavy metals and other toxic materials that can eventually be found in industrial waste water. Therefore it is necessary to analyze the necessary pretreatment of industrial wasewater and to strictly define the requirements for the connection to the sewerage system. These activities must be completed before the construction and commissioning of the sewerage system has finished. Solution with two treatment plants and two sewerage system was the most economical solution regarding construction, operation and maintenance costs of treatment plant and sewerage system (pipelines, pump stations, tunnels, and others) /10, 14/. Split as the far biggest city and producer of waste water was the logical priority in the problem solving process Based on previous studies and projects /1/ it was concluded that Split should have the unique sewerage system and the waste water treatment plant with the belonging submarine outfal for discharge into the Brac ChanneL It was logical that SoHn, as the settlement closest to Split, should be included in the solution for Split and therefore the unique Split-Solin sewerage system was formed. For all settlements in the Trogir area as well as parts of the town of Trogr situated on tiovo Island the most acceptable solution was the collecting of waste waters at the unique treatment plant situated on the southern side of the island with the belonging outfall for discharge into the Split Channel. Also logical and the most acceptable was to connect the rest of the town of Trogir situated on the land with that solution in the unique sewerage system. One more reason to do that are the small quantities of waste water. Since the town of Trogir together with adjacent settlements must have the treatment plant and the belonging outfall situated on the southern side of tiovo Island, there was a question of justification of construction of the separate teatment plant and outfall for discharge into the Kastela Bay for the area of Kaktela. Conducted analyses /14/ confirmed that the most acceptable solution was to connect the area of KYitela with Trogir in the unique KaMtela-Trogirsewerage systen with the unique waste water treatment plant and the outfall for discharge into the Split Channel This solution is economically, technically and environmentally the most acceptable with small impacts on land and sea environment, and also reliable and suitable under local conditions.
127 5.2. ANALYSESAND ALTERNATIVESOLUTIONS FOR THE PLANT LOCATION Smce the adoptedsolution includes two sewersystems, i.e Split-Solinand Kaltela-Trogirit was necessaryto select the locationfor the teatent plants. Snlit-SolincoIectine system In the Split-Solinsewer system all previoussolutions included a treament plant on the Katalinic Brig /18/. This traditionallocation was consideredwith seemralother locations.After an initial analysis11/ of the locationsand requirementsto be satisfied,four locationswere selectedas the best ones:Katalini6 Brig, Gizdauia, Stobrecquarry and Stupe,Figure 5.3. Each of the potential locations was analyzedat the level of conceptualdesign includingthe necessalyurban-planning solution. The analysisof eachof ihe potentialaltematives impacts and characteristicsincluded- - urban characteristicsof the locations (land use, conditionssatisfying the surroundingarea, cutumalmonuments, etc.), - enviromental charatristics (sanitary conditions, noiise,smell, flora and fauna, water resces, etc.) - position with regard to the urban and required infrastnure (electricity,water-supply, telephone,roads, etc.), - positionswith regardto the recipient(disposal/outfall), - positionwith -regard to the present and futuresewer systemas well as other microand macro locationcharacteristics of the area, - costs (land, constructioncost, operationcost), 7 flexibilityand reliability. The altemative locations were analyzed employing the multicriterionalanalysis and the Prometheemethod with 15 criteria. This analysis showed that the best alternativefor the treatment plant was the Stupe location,than Katalinicbrig, Gizdarua and Stobrecquarry IlI. Sensitiveanalyze of the multicriterialprocedure was perforned and in all combinationsthe best sohltionwas locationStupe. The biggest disadvantageof Katalini6 brig location is the shortage of availablearea for the higher level of treatnent and very high cost of the consbuctionin city center and the most attactive part of the city. This locationis favorablein reganrto dispositionand collectingof the waste water. Significantand expensivesteps shouldbe taken at this locationto reducenegative impactson the surroundingarea. Gizdarusalocation situated on the coast shouldbe completely constructedbelow ground level in order to reduce negativeimpacts on surroundingarea ant thereforeit is very expensiveone. Besides, an outfall at this locationwill be very unacceptable becauseof shallow sea and submarinereefs in front of the location..A treatmentplant situated on the coast would have negativeimpact on the developmentof the rest of the coastal strip.. Stobrec quarry location is situated in the center of intensiveurban development,and it is far away from the sea and the possible position for effluent discharge.. This location is very unfavorablein regard to existingsewerage system and their collectionin the treatmentplant as well as for local population. Therefore it is necessary to conduct complex and expensive measuresin order to reducenegative impact on the surroundingarea.. Results with regard to several groups of criteria were the following: The most mexpensive installation (constuction only) is for Stupelocation and then Gzdaruia Operationalcosts of the systemand treatmentplant are the most favorablefor Stupelocation and then Katalinicbrig;
128 In regard to necessary resources the most favorable is Stupe and then Stobrec quarry, In regard to flexibility and envirommentalimpact situation is the same; in regard to the disposition the best location is Katalini6 Brig and then Stupe. In accordance with the Study,/If the Stupe location has been chosen as the best This location has the smallest environmental impact on the area around the treatment plant and in regard to lend section of the submarine outfalL Besides, this location will fit into the present state of construction and planned development of the area. In all public presentations of the project, local population considered this location as the most favorable and the most acceptable. For this location sewerage system was designed on the level of preliminary design, including treatment plant and submarine outfiall.Solution of the sewerage system has been included in the land use plan and master plan of the city. Kaitela-Troeir coilectine system The sewer system Kastela-Trogir included the analysis of several locations for the treatment plants and two of these were selected as the best ones, i.e. the valley near Zedno and the Rastici area, Figure 5.4. Afier a detailed analysis the valley near Zedno was selected, i.e. near Mavascice /141. This location is on an abandoned tenrain. Unlike this place the Rasticnd location is well visible and situated near the area intended for tourism of high category, partly in this very location /19/. In addition the Mavas6ica location is more favorable considering the economic and ecological factors. In order to unite all waste waters at the Rastic location it would be necessary to prepump waste water several times to a height of 50 m (Figure 1.16). Therefore the operational costs are far bigger then the ones for Mavascica location. Besides, the constuction of trunk sewer through the Saldun bay, mostly under the sea, would be far more expensive then the construction of -tiovo" tunneL Therefore in regard to the construction of the sewerage network, Mavascica location is more favorable. This location is situated next to the existing housing and in the area of fiture development and therefore it is extremely unacceptable for the local population. In order to eliminate negative impacts on the surrounding area it would be necessary to place the biggest part of treatment plant installations inside stable object to make them invisible but it is a very expensive solution. Mavascica location is closed deep inside the bay (Photography 2), it is invisible and it won't have impact on the development of the surrounding area, that can not be said for Rasticand location. It won't be necessary to conduct any special measures in order to reduce negative impacts on the surrounding area. Mavascica location, even though far better located in regard to present and planned construction in this area, is not very well accepted from the local population that always has negative attitude in regard to the treatment plant Therefore the phased construction of the treatment plant and lots of effort will be necessary in order to explain to the local population the importance of the treatment plant for preservation of the environment and development of tourism.
129
KA.g.TELA
Figure 5.3.Analyzed locationsof the centralplant for the Split-Sohinsewer system
Figure 5.4.Analyzed locationsof the centralplant for the Kastela-Trogirsewer system
130 53. ANALYSES AND ALTERNATIVE SOLUTIONS FOR THE WASTE WATER DISPOSAL The protection ofthe coastl sea water bay as a combination of treatment and self-purification of the sea, is the most common method used in Mediteianean area as well as in Croatian coastal urban areas It is "treatment-submarine discharge" system This system is analyzed and applied as unique tecbnical-tecbnological unit with all its general and specific characteistics. It is possible because Croatian standards are recipient standard type which allow dilution of waste water in the sea water. The treatment plant effects a partial or complete purification of the waste water, but the location of outfalL and its relation to the coastal area and its depth, while the sea, i.e. submerged outfall is used for fiuther puification, so that the required standards of the open and coastal sea can be satisfied. This means that the required sea water quality is obtained by combination and location of the outfall and degree of preliminary purification in the plant The combination to be applied depends on the-local conditions and on the results of the selection perfonned to obtain an opfimal combination. If effluent is discharged in sensitive waters it is necessary to apply the higher treatment level, but if effluent will be discharged in less sensitive water then only mechanical treatment is sufficient, similarly to the EU directive concerning urban waste water treatment (91/27/EEC). Considering the possible effects of the common configuration of treatment plants, only certain combination are possible and analyzed. Three basic alternatives of the installation of the "plant- submarine discharge" system have been used. They are: 1. Treatment plant- total biological purification (or similar); outfall-minimum length (more than 300 m) 2. Treatment plant- total mechanical purification (or similar); outfall - necessary length according to computation 3. Treatment plant - partial mechanical purification; outfall - necessary length according to computations Alternative I represents an extreme case in regard to the treatment level, and minimum level in regard to the depth of the submarine outfall. This system is applied when assimilative capacity of the sea water is small, like closed bays and sea water with low water exchange rate and sensitive waters. The minimum length of submarine outfall must be 300 m in accordance with Croatian standards. Effluent from treatment plant must be disinfected. It is important to know that first 300 m of outfall are the most expensive part of the outfall because that is area under stronger influence of waves and coastal activities. Alternative 2 includes full mechanical or partial biological treatment which includes removal from waste water of settling suspensions, floating materials, oils and grease and partly BOD. Remaining waste in water is left to the autopurification processes of the sea water. This system is applied when assimilative capacity of the sea water is good, like open bays and sea water with moderate water exchange rate and less sensitive waters. In order to speed up autopurification processes and make substances in effluent less harmless, the waste water is released using diffusers, thus obtained high initial dilution. The computation of submarine outfill length is primarily based on satisfying the bacteriological standard as it is the most critical one. By a combination of dilution and the process of autopurification,the required bacteriological standard can be satisfied with the length of the outfall being ca 1000 m.
131 Altemative3 includesthe minimumpossible degree of prelimiary purificationand maximum possiblelength of outfill for the analyzedcase. Tnorder to satisfy the standardof the open and coastalsea consideringthe aestheticcriteon, and to protec the outfill from gettingclogged, it is necessary-touse minimummechanical purification to emovethe floatingmatter .grcaseand sed. Thusthe standardshould be satisfiedby dilutionand sea-wateractivties. The computation of submarineoutfall length is primarilybased on satisfyingthe bacteriologicalstandard as it is the most crtical one. This systemis appliedin case when assuimlativecapacity of the sea water is high, like channelsand sea water withgood waterexchange rate and nonsensitivewaters. Each alternativehas some specific characteristics,advantages and drawbackswhen compared accordingto the ranking criteria. But, each altemativemust satisfy the sea water standardin regardto short and longterm effectson the sea water.In accordancewith long termpractice the alternative3 can be safelyapplied in case of smallquantity of wastewater or in case when waste wateris releasedin the open and deep sea(channels), i.e. wihensea water has a high assimilative capacity.If the sea water assimilativecapacity can not accommodatewaste quantitiesreleased by outfal (if long termnegative impacts are possible)higher treatment level mustbe used. Whensolving the problemsof the wastewater disposalfor Split, Solin, Kaftela,Trogir, all three altenatives were-considered, i.e. It has been proposedthat system "Treatmentplant-submarine outlls" developsgradually in stages Alternative3 to be appliedin the initial phase when the waste waterquantity is small; alternative2, i.e. alternativeI to be appliedwhen the quantities increaseand when negativeinpacts upon the recipientare possibleaccording to the monitormng of the sea water quality (when it is necessaryin accordancewith results of monitoring and simulationdata or other requirements).According to the previous investigationsit is not planned to have a long-termdisposal of either untreatedor treated waste water into the Kastela and Trogir Bays as they consideredas sensitivewaters which will be continuouslyand increasingly influencedby air depositand otherdiffuse sources of pollution. In order to make proper decisions Computerid DecisionSupport Systems in Coastal Water ResourcesManagement have been proposedand pardy implemented.Computeized Decision Support Systems differ from traditional record-keepingand transaction-processinguse of computersprimarily because they requirea symbiosisbetween the users and the systemin order to be effective.DSS have a three main components:data subsystem(static and dynamic data base), model subsystem(planing models,management models and operation/controlmodels) and dialogsubsystem. This systemwill aid decisionmakers in the process of transformingdata intonecessary information to solveunstructured problems of coastalwater qualitymanagement. Resultsof calculations(Appendix 1 and Appendix2) show that in accordancewith the present knowledge such results can satisfy not only present standards but even the new Cratian standards(still in preparation)that are similarto EU standards,International protocols and EU standards(91/27/EEC; 76/160/EEC). Themain advantageof such approachis in rationaland reliable solvingof the problemof waste water disposalbecause dunng the initial periodof the operationof the systemthe shortageof qualified staff and resources for the system operation won't have negative impact on the required level of sea preservation.In the initial period the problem of sludge handling and disposalis also eliminated..During the initial periodthe operationalcosts are minimaLAfter the beginningof the systemoperation better informations about wastewater qualitycan be collected because waste wates will be united at the unique treatment plant, as well as about recipient condition.Therefore it will be possibleto betterplan a necessaryincrease of the treament leveL
132 This approach is aba more acceptablefor the local population that is gradually geting used to the existenee of the tament plant Local population wimgnotce advantges of Jhe henfi cility of tie solution and will accept biggerfinlancial liabilites and the deweopment of treatment woiks.. With this approach, during the initial period, the impacts on eco-system of the sea are bigger and impacts on terretrial eco-system and the area in the vicinity of the treatment plant are smaller. Increase of the treatment level will reduce the impact on eco-system of the sea and increase the impact on terrestrial eco-system and the sumounding area because of treatment plant development, treatment products and solids disposal, Figure 5.6. In order to protect sea water, treatment of industrial wastewaters at production site has to be instituted at the beginning of system operation and trade effluent policy has to be established except for biologically degradable effluents. Process of greening of industry has to start as soon as possible.
133 c,c . -0 5A. ALTERNATIVE SOLUTIONS FOR THE TREATMENT PLANTS TECHNOLOGY The selection of tecbnology for the waste water treatment for the Split-Solin sewer system included two main alternives: AB process and a traditional activated sludge process /10/. hbe pbased installaton program was designed depending on the development of collecting system, the final effluent quality requirements and the treatability of the wastewater. Each alterative included a preliminary design solution and a comparison after which the AB process was selected as a more efficient one. Both processes are similar in the costs and environmental impacts, but the AB process was selected since it ensures better construction in phases and makes possible partial biological treatment, which is considered to be long-term efficient considering the assimiative capacity of the Brac-Split ChanneL less sensitive waters /10/. No matter that all conducted researches imply that there is no need for a higher level of treatment, all installations were designed for tertiary treatnent level with INV desinfection in order to determine long-term required area and other resources. All alternatives require the sludge treatment to the level that enables its use for agricultural purposes in accordance with Croatian and EU standards. The basic requirement is adequate treatment of industrial waste water. In regard to large excavation in the suTroundingarea for purposes of cement manufachtring, there is enough space for sludge disposal if it wouldn't be used for agriculture.. Sludge can be composted and together with municipal waste used to cover solid landfill site. This option was discussed in the municipal waste treatment analyses. The two processes are identical considering the first phase of the construction with the partidal mechanical treatment Since there is no unique sewer system and, hence, there are no reliable samples of the waste water (combined system), it is considered that the final technology of higher treatment level should be selected according to the results obtained after the operation of a pilot plant It should start after the collection of the waste water at the plant after the first phase of construction. The present characteristics of the waste water in Split, due to great dilution, are of the same quality.as the effluent from the secondary reatment plant during the greatest part of the year (BOD5 25-50 mg/I). The same study was not developed for the sewer system Kastela-Trogir so that the results of the Split-Solin were used instead The same procedure to be used for the solution of this problem was proposed for this system as welL.
135 5.5. ANALYSESAND ALTERNATIVESOLUTIONS IFOR SUBMARINE OUTFALLS The studies included the analysesof altenative solutionsfor submarineoufalls, such as the atratives for the locationsof diffuser disposition,route for the land sectionand submarine section of the outfall and various typs of consruction for the diffusers and consftuction in phases...' These analyseswere developedacording to previous oceamographicinvestigations, modeling and computations(Appendix 1), taking into accountthe positionof the teatment plant and its constructionin phas (treatment Ilvel of the plant). These analyses also included the requirementsrelated to the use and functionof the sea in the area underconsideration. For the Split-Solin sewer system the reqrements for the submarine outfall and diffuser placementare not the same for the entire area of Brad Channelin the south of Split peninsula firomStobrec to city harbor, Fig. 1.9. In the cental part of that area of Brat Channelthere is shallowsea with submarine reefs (depth 8-18m) that disable the constructionof submarine outfalls.Therefore the possiblelocation for the outfall are fruther east towardStobrec or further west toward city harbor. Consideringthe waste water treatment.plant locationin the area of Stobrec,the most acceptablelocation for the outfall was the area of Brac Chanel in front of Stobre6. Environmentalrequirements for the diffuserlocation (place of discharge)frm Stupetreatment plant are relativelysimilar in the Brac Channelfor the entire area of Stobrec(depth from 30 to 50 m) becausedepths and velocitiesare similar in the entirearea. Depth is generallyincreasing with the distace from the shore and thereforethe disposalis enviroomentallymore favorable with the greater distancefrom the shore.,FigI.9. Mixing and exchangerate of water are more favorabletoward the middle of Brac ChanneLOutfall route is favorablein this area becauseuse of fishingboats with the net is prohibited.Therefore there are no restrictionsfor the construction of the outfal and the diffuserin this area.. Environmentaland constructioncharcteristics of the sea bottomin this part of Brac Channelare the same and thus don't have the significantimpact on the selectionof the diffuserlocation. Constructioncosts of the land sectionof the outfill have the biggestimpact on the selectionof the location.The existingdocmentation includesthe solutionswhich were selectedaccordig to multicriterionalanalysis. Within the Split-Solinsystem two routes for the outfallwere analyzed, Figure 5.7. The analysiswere performedaccording to preliminarysolutions for each alternative /1/. Both routes are in the Stobrec area. Themain differencebetween these two routesis the cost of implementationvwich is significantand partly the ecologicalcharacteristics which are similar at both outfall locations.Both routes are very expensive The route throughthe StobrecBay was selectedas a more efficientone. Waste water disposalrequirements for the Kastela-Trogirsewerage system on the south side of the tiovo Island and this part of Split Channelare pretty much the same becauseconfiguration of the sea bottomis similar,Fig. 1.14. Conditionsare favorablebecause of significantdepth of the sea (50 - 70 m) that increaseswith the distancefrom the shore towardthe middleof the bay and very good exchangerate of sea water. Environmentaland constuction characteristicsof the sea bottomin this part of Split Channelare the same and don't have the significantimpact on the selectionof the diffuserlocation. On the Ciovo peninsulatwo positions for the submarineoutfall of the Kakela -Trogir system were analyzed./14, 5/. Distancebetween them is about 1.5 knm.Conditions are more favorable
136 toward the west because the sea is deeper and therefore conditions for dilution. Construction conditions, costs and envirommental impacts for each of them are very similar. The selected location is more distant from the small islands (St Fumija) and other downsntm islands in this aquatorium, i.e. it is the location near the Mavascica bay., Figure 5.8. The diffuser is situated within the area where use offshing boats with the net is prohibited. Outfall route through the smaller bay Mavakica is more favorable because of the good protection of the pipeline on the bottom and smaller impact of the waves and therefore greater reliability of the disposal system and smaller construction costs.
137 I KA gTELr.A
Figure5.6. Alternativeroutes and positionsfor the submarineoutfalls for the Split-Solinsewer system
Fiaguie5.7. Altenative routes and positionsfor the submarineoutfalls for the KaXtela-Trogirsewer system
138 6. PROPOSED MEASURES TO PREVENT, REDUCE OR MMGATE THE ADVERSE EFFECTS OF THE PLANNED WASTEWATER DISCHARGE SYSTEM -
6.1. STRATEGICPREREQUISITES FOR THEPROTECTION OF KASTELAAND TROGIR BAYAND BRAt AND SPLITCHANNEL AGAINST POLLUTION FROM LANDBASED SOURCESAND ACTIVITIES Protectionof Kaitela and Troeir lBa In orderto ensure long-termprotection of Kaktelaand TrogirBay, consideredas sensitiveareas, it is necessaiyto: - eliminateall outfallsthat dischargemunicipal wastewater into the bays - eliminateall outfallsthat dischargeindustrial wastewater into the bays - reducediffuse sources of pollution (stormrunoff, air deposit,etc.), and - establishpermanent control of pollutionsources and monitoringof coastalwater. Protection of Brac and Split channel The permanentprotection of Brag and Split Channel,considered as less sensitiveareas, in the widerarea of Split, Solin, Kaitelaand Trogirshould be ensuredby the fullfinedthe following: a) General conditon I. Disposalof the wastewatervia long submarineoutfalls, and achievingappropriate initial and secondarydilution. 2. Purificationof the wastewaterprior to dischargeinto the sea -by longsubmarine outfals. 3. Pretreatment, prior to discharge into the municipal sewerage network, of industrial wastewaterthat canbe detrimentalto: - the operationof the biologicaltreatment plant - usageof the sludge producedat the treatmentplant - marineecosystems. 4. Eliminationof all existinguncontrolled coastal outfalls. 5. Appropriatepurification of stormrunoff and overflowwater. 6. Controlof all other diffusesources of pollution. b) Constructionof seweragesystem Constructionof appropnate seweragesystem (collecting system, treatment plant and submarine outffal) would create conditionsfor the fulfilledof the mostly abovelisted generalcondition. But its constructionall urban and industrialwaste waters generatedin Split, Solin, Kaitela and Trogir area will be collectedat two treatmentplants (Stupe and tiovo), treated at appropriate level and dischargedinto Brac and Split channelsvia long submarineoufalls. c) Design and quality of construction of colkecing system,treatment plants and submarine outfalls In orderto ensure efficientcollection of all wastwatersinto the collectingsystem, it is necessary to design and constructusing best availableknowledge and availablematerials and technology, and local characteristics,to ensurehigh-qualty construction.
139 d4 Effientt maagement and mintenance of sewerage *szem Efficient managementand maintenanceof seweragesystem is the key elemet for efficient protectionof environmentand sea water becausethe efficient orgaization, experienced,well trained and adequately paid staff are necessaryto ensure permanentefficient operation of the werage sstem (collectingsystem, treatment plant, submarineoutfal). e) PublCpriicni-ton The public (local communities,NGOs, representative of scientificcommunity, etc.) should be the main promoterof protectionmeasures as well as a proofreaderof measuresthat are already undertaken.Therefore it is necessaryto includethe publicin the developmentof entireproject. j) Monitoring and informaion Iniorder to collect necessary data for coastal water resources managementand to inform the public and all interestedsides about the level of sea water pollution,discharges and activitiesit is necessary to establish monitoring of sea water quality, discharges and all other elements associatedwith the seweragesystem and teatment plant (soids disposal,sludge use, costs,etc.). An appropriateinformation system to inform generalpublic and all interestedparty about all activitiesthat were or willbe undertakenas well as aboutachieved results should be developed. g) Computerbased Decision Support System for Coastal WaterResources Management Monitoringdata togetherwith other relevant data by computer-basedDecision Support System (DSS) have to be tnsformed intD necessary information'sto aid decisionmakers to take environmental sound decision in coastal water resourcrs management DSS will aid to scientificallyanticipate the measuresfor determinationof the level of pollutionof seawater in the entire area (simulationmodels), determinationof necessarymeasures for the sea water prtection (thetreatment plant development,increasing the treatmentlevel, correcton of system operation), determination of measures for expansion of the existing sewerage system, determination of other struchnal and nonstuctural measures for the protection of the environment,etc. By applying above listed it could be concluded that the sea water of Brac and Spilt Channels will be protected from: a) Bacterial pollution During the initial phase (preliminarytreatment only) the installationof long submarineoutfalls will be in accordancewith the calculationof dilution and time of bacterialdecay in order to ensure requiredstandards for the open sea (HI category)at the outfall location and standards for bathing and recreationalwater (II category)on the boundary300 m from the shore. To meet these requirementsthe outfallslength shouldbe 2600 m, lengthof diffuser400 for Stobred, and 2050 m and diffuserlength of 400 m for Liovo. During other phases (secondarytreatment) the protectionwill be ensuredwith UV disinfection of the effluentand submarineoutfall of such length that the distanceof the diffuserbeginning from the shore is alwaysgreater then 300 m. b) Aesthetic pollution During the initial phase (preliminarytreatment only) installationof screens,aerated geise/grit channelswill ensr that there is no visibleslick on ihesea surface.
140 During the second and other phases of construction of the wastewater treatment plant (Primary tretment, Secondary treatment) the protection will improve by installation of settling tanks. In order to reduce negative aesthetic impact it is necessary to install screens (6 mm opening) at overflows, and grit/grease channels where necessary (at the-location of significant sources of pollution). c) Organic poliution During the initial phase almost entire organic pollution will be discharged into the sea and according to the calculation output and the results of simulation model it will be accomodated without significant detrimental effects.. - During other phases of construction of the treatment plant (primary, secondary and tertiary), if necessary, the organic pollution will be significantly reduced (from 20 to 99%/O). d) Heavy metals and toxic materials During the initial and all other phases of the system development, the protection of sea water will be achieved by control and purification of industrial wastewater at the place of origin. e) Nutrient content The reduction of nutrient content of wastewater and therefore the protection of the sea water will be achieved by installation of higher levels of purification and especially tertiary treatment plant, if necessary.
141 62. SPECIFIC MEASURESPROPOSED TO PREVENT,REDUCED OR MIGATED THE NEGATIVEEFFECTS OF THE PLANEDSEWERAGE SYSTEM The adve effects of collectingsystem, teatnent plants and submanineoutfials may be reduced y respectivemeasures and proceduresduring their consfuction,use and mamt r 62.1. Legal and administrative measures during the construction The constuction of the seweragesystem installations must be in accordancewith legislationand especiallywith the BuildingLaw (NN 77/1992,N.N. 33/1.995)and other laws relevantfor this objects(Water Law, N.N. 107/1995). The constructionmust also be in accordancewith requirementsissued by differentauthorities such as: sanitary requirements,water authorities requirements and requirementof local seweragesystem organisation, requirements of harbourauirionties and roadbuildingauthorities, electrical supply requirements,requirements of other infiatructure organisations,location permit etc. Constructionmethods and proceduresare presentedin Buildingpermit In order to constuct as fast as possible and without negative environmentalimpacts-it is neesry to define the ImplementationSchedule taking in account local requirementsand characteristics.It is also necessaryto co-ordinatethe constractionwith all activitiesin the areaor activitiesthat will be influencedduring the constuction. It is always recommendedto contact the local population and discuss the most favourable constrwtion method. 6.22. The collectingsystem 62.2.1. Measures during design and construction Generd To eliminatethe dangersassociated with the systemthe need for safety shouldbe consideredin the design of such system.They shouldbe propely sized, closed,watertight and hard enoughto the sustain all possibleloads that may occur during normal operationor at damages.Sections which cross the water supply mains are separatelymade so to avoid any contact of sewage effluentwith supplywater mains or at a sufficientdistance apart Use of the most imperviousconcrete possible and consuction of pipes and canalswith elastic joints, leakagewill be almostcompletely prevented. Continuityof the operationof pumping stationsmust be ensuredwith the following:resrve pumps and reserve power sources - diesel power generator sets at all major pumpingstations (Dujmovaca,Duje, Lokvice, Pantana-Divulje),mobile diesel-powergenerator sets or double power sourcesat other smallerpumping stations. The seweragesystem should be plannedas to avoidtbreatening historic monumentsand passing through ecologicallysensitive areas. The same will be achievedwith consultingand observing the requirments of the servicesfor the preservationof historicmonuments in eachtown: Split, Solin, Kastela and Trogir. Design of the sewerage network and its objects should consider the planned urbanistic characteristicsof the sewer routes as well as planned municpal infrastructure(electricity, water supplyetc.)
142 In order to avoid negative impacts created by construction activities in tourist areas, especially in Trogir and (iovo island, construction should be organize out of tourist seasons Special plan of measure-for utilities supply should be prepared and implement during the collecting system construction in order to eliminated the negative impacts on local population, public and other institutions. For the protection of unknovm historic monuments especially in Solin and Trogir area earth works should be implemented after consultation with institutions responsible for protection of historic monuments. During design and construction period it is necessary consult Water authorities in Split in order to avoid negative impacts on surface water streams, especially in Kaitela area. Responsible authonties must establish legal act that prohibits any activity in the crossing areas of raisig mains of pum station Lokvice and Pnatana-Divulje that could damage the pipes (fishing boats with nets, anchoring etc.). The pipes position must be marked on both coast and nautical maps and corrections made on already existng maps The collecting system should be equip vith flow meters and pump station with control system. Odour and noise The problem of odour is solved by ventilators and filters for air cleaning. The problem of noise is solved by burying the structures under ground and sufficiently apart from residential areas. Noise associated with the operation of pumping stations can be reduced if diesel power generator set is housed inside an appropriate building or noiseless power generator sets were used. This should especially be considered for pumping stations Lokvice and Divulja-Pantana. Pumping station odour control consists of ventilation and air purification pnor to discharge into the atmosphere. It should be especially considered for pumping stations located within 20 m from the residential areas, if possible. Measures for prevention of health hazard The sewerage system is built to safeguard the health of the population. However, some parts of the sewerage system may be dangerous for human health if required measures are not undertaken. To prevent the production of aerosols, which may adversely affect the health of the surrounding population, there should be no open areas in the entire waste water collection system. Maintenance staff must be well training in the procedure for entry to confined space and control other hazard. Unauthorized access to the elements of sewerage system (pump stations, overflows, etc.) is prevented by the fencing or guard rail, locking up of the objects and posting the warning signs. Fire extin2uisbing measures These works are not source of any special danger of fire and no special measures are required. Prevention of accumulation of methane and other inflammable gases in sewers and pumping stations will be achieved with efficient ventilation system.
143 Other measures Existing collectionsystem in Split is combinedtype sewerage system. In order to preVCnt pollution aused by overflow war it is necessaryto install screes (6 mm openmg)at the overflows,and oil and gease separatorsif necessary. In order to determinethe real impactof these waters on the coastalsea water it is necssary to developthe mathematicalmodel of collectingsystem and determinefrequency of overflowsand total annualpollution loads. Based on obtainedresults it is necessaryto dimensionovrflows and belongingoufals for overflowwater. It is also necessaryto determinelong trme pollutionof storm runoff and its impact on marine environmentin orderto anticipatemeasures of protection.
6.2.22. Measuresduring operation - Negative impacts during operation of the system must be avoided by proper maintenance. Prlerquisite for proper mainenance is the developmentof maintenanceplan and its application, as well as appropiate stage of spearparts Maintenanceof the systemmust be regulary and duringthe maintenanceall necessarymeasures agamisthazard health impacts to workers must be applied. Appropriatetraining of stuff is necessary. The systemmust be regularlywash out, controland repairif necessary.Especial attention should be paid to matenance of raising main cssng the Kaktelabay, overflowsand pumpstation. Deposit and crustin pumpstation should be regularlycleaned. Illegal connection of stormwater to foul systemshould be eliminated. Regularlycontrol of flow in the systemmust be taken in orderto controlinfiltration waters: Screens on stormwateroverflows must be regularly clean especiallyduring and after rainfll season. The pumps mustbe regularlycontrolled and maintenance.From time to time standby systemfor energy supplymust be controlled. 6.23. Treatment plants Measures for irevention of air aNalitvimnairment Two kinds of preventivemeasures against unpleasant odors and aerosolsmay be distinguished: designingand operational.The formermeasures mean closingof all the stuctures which should be aestheticallyand functionallyadapted to the environmentin the best waypossible or buried. One of the operationalmeasures is the forcedventilation of the entireindoor space.Ventilated air will be releasedinto the atmosphereupon appropriatetreatment (using biofiltars).It should includeall elementsof preliminaryworks: Reception Chamber, Inlet Channels, Screens, Aerated Grit/GreaseChannels, Cess Tankerreception and screens.In additionthe row sludgeprocessing units must be coveredand providedwith ventilation/odourcontrol primary sludge thickening, secondarysludge thickening/dewatering, sludge blending and digestedsludge dewatering.
144 Measures for reduction of vibrations All the works that may produce vibrations such as: air blowers and power plant have to be appropriately mounted on vibration dampers to prevent transmission of vibration to -the surroimding terrain. The problem of vibration of the outfals as the result of air penetration into the pipes will be eliminated by the constructionof an appropriate ventilation shaft. Fire extiueuishinf measures These works are not source of any special danger of fire and no special measures are required. Hazard related to handling and use of digester gas are well recognized and current practice have to be used so that this hazard is minimized. Usual fire hazards measures is necessary to apply in accordance with low for all elements of the treatment plants. Measures for Drevention of health hazard The sewerage syseam is built to safeguard the health of the population. However, some parts of the sewerage system may be dangerous for human health if required measures are not undertaken. In general there are no hazard to the health of neighboring people from treatment plants- Hazard relation to the operation of treatment plants must be recognized and strictly controlled. The control of entry to confined space must be strict Works operation and maintenance staff must be fully trained in the procedures for entry to confined spaces and control of the other hazards associated with operation of treatment. Measures to minimized enission of bacterial aerosol spry have to be applied, such as tree screens, raised sides to aeration tanks, and selection equipment that minimizes the generation of spray. In order to prevent accidents and possible detrimental effects on the population, the area of the wastewater treatment plant must be fenced and permanent securty guard service established. Measures for Drevention of noise All equipment that will emit significant noise (like: power generation, aeration blowers, etc.) must be housed in sound attenuating buildings. Solids disposal Solid wastes associated with the operation of the treatment works have to be properly treated and disposed: screenings must be washed, dewatered and dispose at sealed landfill site or incineration on-site; grease and oils must be incineration on-site or collect and dispose with urban oil and grease waste; grit and sand must be wash and clean from organic material so that it can be used for landscaping; stabilized biosolids must have long term stability and to be suitable for agricultural or horticultual purposes. Aesthetic impacts L Appropriate solutions like tree planing have to be implemented in order to minimizing the visual impacts and wind effect on the operation of works and improve aesthetic conditions. Work buildings have to be finish in accordance with local building traditions and other buildings in the area.
145 Traffic Trafficto and out of plant must be properlyregulated. New road out of villageMavac ica should be consideredin order to avoidedall problemsrelated traffictbhroug esting inappropriateroad throu village Insect nuisance Althouproblem related insect (filter flies and mosques) is not problem for the proposedtype of plant usualcontol must be considered. Measures for prevention of noliution fresh and sea water against pollution by surface runoff In order to prevent pollution of fresh waters (river Irnovnica) and coastal sea (Stobrecand MavaWica bays) it is necessary take appropriate measures against storm water runoff (consuction of channelsand settlingbasins). 6.2A. The submarine outfa 6.2A.1. General To protectthe submarinepart of the oufalls from wave and anchorageimpacts as wel as from impactsresulting from variousother activitiesin the namrw coastal stip, it is plannedto bury and concretethe pipes to the point of 8 m of sea water depth (have to be determinedby design). The rest of the pipe wiU be protectedby forbiddingall the activitiesin the sewer surrounding that may damageit. To avoid eithervertical or horizontalshifting of pipes (as affectedby currentsor air penetration into the system)pipes shouldbe fixed by appropriateweightsL Since the submarineoutfll for dischargeinto the StobreZBay is passing throughthe possible locationof the future ferry port, pipelinemust be laid deep enough into the bottomto protectit from effectsof possibleanchonng of ships. Instuctions for the outfal consDtuctionwill be providedby Port authoritiesin Split To providenormal diffuser operation it will be placed on the supportsand elevateda I m above the seabottom. A flange is fittedat the diffuserend to permits cleansingfrom time to time. 6.2.4.2.Measures that should be undertaken during the construction of submarine outfalls As it was mentionedbefore, the constructionof submarineoutfalls won't have significantimpact on the marine environment In order to avoid and reduce assumed negativeimpacts during the constructionof submanne outfallsit is necessaryto undertakethe followingmeasures: - in the coastalarea, the outfalUpipes shouldbe buriedand protectedwith concretein suchway to causeminimum turbulence within the area. - during the installationof submarinepipeline it is necessaryto effectivelyand on time secure the aquatorium(especially in the Split Channel).It must be marked and made public in order to avoidaccidents and to securelives of the stuff on ships and workersthat will performthe installation.
146 6.2A3. Measures that should be undertaken during the operation of submarine outfails In order to secure the planned opeation of assumed submarine outfalls and therefore prevent negative impacts of the discharge of urban waste waters on mane eco-systems and to make possible the usage of sea for planned purposes it is necessaty to undertake the following measures that cam be classified as legal, technical and organisational ones. i) legal measures
- responsible authorities must establish legal act that prohibits any activity in the area of the submanne outfall that could damage the outfall (fishing boats with nets, anchoring etc.)
- fishing in area around the diffuser location (500 m) must be ban. ii) technical measures - the submarine outfall position must be properly marked on the land and on the sea;
- the outfall position must be marked both on the coast and on nautical maps and corrections made on already existing maps. Changes must be announced for the public especialy before the summer season starts, - -
- the control of accuracy of outfall operation and its maintenance must be done at least once a year (in the beginning of spring) by autonomous divers or submarine robot TV cameras; iii) technical measures
- the system of regular control of oufall operation and maintenance must be established and carried out in accordance with technical and technological requirements of the construction;
- establish and organise technical team that will immediately intervene to fix any damage that could prevent the planned operation ofthe outfall. 6.2.5. Tunnel Since the construction of the tunnels will have significant impacts on local and wider areas with respect, noise, dust, traffic, vibration, visual impacts and disposal of excavation materials it be necessary to prepare a separate environmental impact assessment for both tunnels. 6.2.6. Organization and management It is recommended to operation company that core team of operation staff recruited before the works development so that installation can be used for training. It is necessary to organize smaller team of chemist and laboratory staff for waste water monitonng and establishing good trade effluent monitorng. It is recommended to operation company to carry over necessary recruitment, training and built up of the drainage system management and control team. A study have to be carried out covering current organization and proposed organization (staffing levels and training requirements) in accordance with system development (new treatment plants, submarine outfalls and transmission mains). Operational company have to bay necessary equipment and tools for appropriate control and maintenance of the system.
147 6.27. Other measures and studies 1. In order to make proper decisions regardingnecessary treatment and improvementof collecting system ComputerizedDecision Support Systems in Coastal Water Resources Managementhave to be implementedIbis systemwill aid decisionmakers in the processof transforig data into necessaryinformation toDsolve uructuedproblems of coastalwater qualitymanagemenL 2. Monitonng and collectionof wastewaterchareristics data (flows and concentrations) includingand storMwater data shouldbe established. 3. Monitoringand collectionof meteorologicaland clinmalogicaldata at locationof treatment plans shouldbe establishedL 4. It is necessary set up wastewaterand effluentmonitoring system at the treatmentplants (flowsand concentrations). 5. It is necessaryto organize monitonng of agriculturalamd others land and crops receiving sludge fromteatment plant. 6. After installationof the first phase preliminarywork, pilot studies shouldbe canied out to charactrize the treatabilityof the waste water and provide design inormation for future process selection. 7. It is necessaryset up study of sludgedisposal outlets in accordancewith localconditions and needs includingsludge management and disposalpolicy study. 8. Trade effluent policy should be establishedand strict trade effluent monitoring controls instituted 9. Study have to be carried out to determinenecesry tvratmentof industrialwastewatr at the productionsite and necessarysteps for greeningof industry. 10. Strict controlsmust be appliedto settingand monitoringof standardsfor trade effluent
11. Prior to commissioning of the wastewater treatment plant, the sanitary landfill site for disposal of sludge and solids from treatment plants must be determined.
148 7. PROPOSED RESEARCH AND MONITORING PROGRAMME
7.L JUSTIICATIN FOR THE PROGRAMME Thenature and size of the inveswmet,as well as its potential environmental impacts, requires the good knowledgeand understandingthe marine ecosystemsin the area, in order to avoid undesirable negative impacts of discharged waste waters. Numerous studies of the Kaltela bay have shoved that the Kastela bay is threatened by urban and industrial waste and for is recovery would be necessary to stop the discharge the wastes. The study of the Split and Brac channels performed in September 1990 and April 1991 has shoved that the Brac and Split channels, even degraded in restriced coastal areas, due their relative large volume and the circulation of water masses were found to be the best available solution for the receiving the waste waters. The research of the Split and Brac channels was performed in September 1990 and April 1991, missing the summer the most critical season from the ecological point of view. In order to confirm the conclusions based on the available results and used for the design of the sewerage project, and gather further information necessary to evaluate the present state, it would be necessary to undertake further investigations of the marine environment of the area. The results of investigation are very important, also, for the decission on the final waste water treatment level, which will be made later taking into consideration impacts of pretreated waste water on the marine environment
149 72. AIMS OF TEE PROGRAMM The main aims of the programmeare: to collect informationon the dynamicof waternasses imthe areas of thesobmarine outfals --and in the entire chanels area during summer season, the most criticalperiod fiom the -ecologicalpoint of viiewand use of the coastl zone for bathingand recreation; to evaluatethe present level of the degradationof marine ecosems of Brat and Split channels and Katela bay, using different physical (transparency,TSS) chemical(oxygen concentration and saturation, nutrients concentration) and biological (str e and compositionof phytoplankton,zooplankton, bacteioplankton and benthic communities,and primaryand secondaryproduction) parameters to assessthe present levelof pollutionby selectedpollutants contained in urbanand industrial waste watrs.
150 7.3. OUTLINE OF THE RESEARCH PROGRAMMAE
1. Current measurements (by current meters) Period: January-February (period of homogenouous water), and July-August (period of intensive stratification) Duration: 25-30 days Locations: 13 stations (I-XMI)indicated on the Figure 7.1 Levels: 2 levels; surface (3 m) and bottom (3 m above the bottom) 2. Physical parameters (by ClID probe) Parameters: salinity, temperature, sigma T, Secchi disk Period: 6 times ( at a begining and end of the current mesaurements, and in May and October) Locations: 26 stations (1-26) and 13 current measuremant stations (I-XIII) indicated on the map Levels: profile from the surface to the bottom 3. Surface waves Parameters of wind generated surface waves are proposed to be measured in the period October- April) by anchoring waverider station in front of Split port (Figure 7.1) 4. Meteorological data Wimd speed and direction will be measured at 3 stations: main meteorological station Split- Majan, Rt Lasatna ant at island Drvenik Vei (Figure 7.1) Air pressure and temperature will be measured at the main meteorological station Split-Maijan. S. Chemical parameters Parameters: dissolved oxygen, nitrate, nitrite amonia, N,.. ortho-phosphate, P.,, ortho- silicate Locations: 30 stations (3,4,5,6,7,8,9,10,15,16,18,20,21,22,23,24,25,28 and ll-XII) indicated on the Figure 5.1 Levels: 4-7 levels (surface, 5, 10, 20, 30, 50 m, and bottom Period: same as for the physical parameters 6. Biological parameters Parameters: composition of the phytoplankton community, cblorophill _, primary productivity, density of heterotrophic bacteria, heterotrophic nanoplankton, bacterial production, structure and composition of microzooplnakton, structure and composition of benthic communities Locations: i) plankton on 30 stations (same as chemical parameters), exept the primary productivity which will be measured at stations IV, VII and 23 Levels: 3 levels (surface, 20m, bottom) exept for primary producticity 5 levels (0, 5, 10, 20, and 30 m) Period: same as the physical parameters ii) benthic communities on 10 profiles, up to 30 m depth as indicated on the Figure 7.2 Period: once 7. Spawing areas and Nursery grounds Parameters: temperature, salinity, oxygen, pl, nutrients, ichtioplankton, juvenille fish organisms
151 Locations: estuaries of Cetna, ±mnovnica, dro,- Pata, and shallow bay (Bene Supetar, Kakel Sucurac, Neujam, Lesimerova, Livka, Stiniva, Zastup, Lovre6ina, Luka-Povlja) Period: monthly - 8LIndicators of faeal pollution Parameters: faecaland total colliforms,faccal streptococci Locations: 17 stationsas indicatedon the Figure 7.3 Levels:surfice layer Peniod: monthly(V, VI, IX) and weakly(VII VI) 9. Concentration of heavy metals Parameters: i) surface sedimets: concentrtin of Cd, Zn, Hg, Pb, Cu, Cr, granulometric composition,and organicmatter content ii) shell fishMytilus gallopmvzndals- concentrationof Cd, Zn, Hg, Pb, Cu, Cr Locations:i) 15 stations(4,10,15,22,23,22,24,26, and II-EX)indicated on Figure7.1 ii) 15 stationsdisibuted all over the coastalregion Period: i) once ii) seasonally 10. Concentration of chlorinated hydrocarbons Parametres: i) surface sedimets: concentration of chlorinated hydrocarbons (Aldrin, Chlordane, DDT, Dieldrin, Dioxines and Furanes, Endnn, Heptachlor, Hexachlorbenzene, Mirex, PCBxand Toxaphene) i) shel fosb Mytilus galloprowncia1Ls:concentration of chlorinatedhyocarbons (Aldrin, Chlordane, DDT, Diedrnn, Dioxines and Furanes, Endrin, Heptachlor, Hexachlorbenzne, Mirex,PCBx and Toxaphene) Locations:i) 15 stations, sameas heavymetals ii) 15 stations,same as heavymetals Period: -i) once ii) seasonally 11. Consumption of dissolvedoxygen by sediments Consumptionof dissolvedoxygen by sedimentsfrom 5 stationslocated in the Kaktelabay and Split and Brat channels sholud be measured seasonally by -on board" method. The cost of the proposed research programme is estimated awthe level of 700,000-900,000US S.
152 7A. OUTLINE OF THE MONlTORING PROGRAMME Sewage effluent control as well as the observation of the changes occuring in the marine enviromnent due to the disposal of sewage effluents should be permanently carried out to: - collect information on the marine environment in order to prepare the proper decision on the reqired level of waste waters trtment, - evaluate the impacts of the outfalls on the surrounding marine environment - implement necessary measures for protection of the environment and health of the surrounding population. - to asses the recovery rate of the Kastela bay, - to complain the state of marine environment with the prescribed valuer Parameters to be monitored and frequency of measurements A) EFFLUENTS: - flow rate; - nutrients (total phosphorus, total nitrogen, nitrites, nitrates, ammonia);
- BOD 5 - total suspended matter, - heavy metals (Cd, Zn, Hg, Pb, Cu, Cr); - chlorinated hydrocarbons (Aldrin, Chlordane, DDT, Dieldrin, Dioxines and Furanes, Endrin, Heptachlor, Hexachlorbenzene, Mirex, PCBx and Toxaphene); Sampling should be performed on a seasonal basis at the manhole at the end of land sewer part, so as to permit the calculations of daily mean values. B) MARINE ENVIRONMNT: 1. Physical parameters - parameters: some as under the research programme - locations: same as under the research programme - period: 6 times in a year (I-I, V, VI, VIII, 1X, X) - levels: same as under the research programme 2. Chemical parameters Same as under the research programme, except period of measurements which should be the same as for the physical parmeters. 3. Biological parameters Same as under the research programme, except period of measurements which should be the same as for the physical parmeters. 4. Indicators of faecal pollution In the Split and Brac channels same as under the research programme. In the Kastela Bay at 10 stations. 5. Concentration of heavy metals Same as under the research programme. 6. Concentration of chlorinated hydrocarbons Same as under the research programme.
153 7. Consumption of dissolvedoxygen by sediments . Same as underthe researchprogramme. Yeariy cost of the proposedmonitoring programme is estimatedat the level of 300,000US S.
, J;L -, -1
154~ ~ ~ ~ *=? O LOCATIONOF THEOCEANOGRAPHIC ANDMETEOROLOGIC STATIONS (AREAOF SEWERAGESYSTEM)
_ 23 ~~~0
go~ ~ ~ ~ ~ ~ ~ ~~~@ 213
0~ 13 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 0
'i~~~~~~~~~~~~~~~~~~~~~~~~~~~~~7~~~~~~waerde i1
Elmaimeterological station
Figure 7.1. Location of the oceanographicand meteorological stations ! ! . S O L I N , :0~~~~~~~~SLI
Split channel Brac. channel 10
,<__\ < f3~~~~~R A C
Figure7.2. Locitlon of profilesfor the benthiecommunities study
156 A~~~~~~~~~~~~~~~~~~~
SOLIN~~~~~~~~~
.0 0
Split channel Brac channet
0~~~~~
R A C
Figure7.3. Location of stationsfor the controlof sanitaryquality of coastalwaters 157 7.5. COMbUTER-BASED DECISION SUPPORT SYSTEM FOR COASTAL WATER RESOURCES MANAGEMENT Compid decisionsupport systemsare intactive computer-basedsystems that aid decision makers in the process of tansforming data into necessary informationto solve unstruchtred problems of pollution and prtection of the coastal sea waters in the Split, Solin, Katela and Trogirregion. The main componentsof the DSS are: data subsystem,model subsystem,and dialogsubsystem, as illustratedon next figme.
Decision Maker
Si Centrl ProcessingUnit panning Static . Models Data Base Data Model. Management Dynamic D DBase Models Data Bace Management Management p ods System Syslem Models
Models
Figure7.4. Basiccomponents of a DecisionSupport System The data subsystemis directedto the acquisition,storage, management, retieval and processing of data and it will be subdividedinto static and dynamic database.The static data base will includethe physical,economic, demographic, environmental, land use, as well as other pertinent featres of the system The dynamic data base on the other hand, includes time series information such as hydrology, wastewaterflow, wastewater quality, sea water quality and cimatologic data sensing. The modelsubsystem is used for analysis,predicting and decisionguidance. This subsystem will include a variety of models ranging from simulation (collecting system, treatmientplant, submarineoutfall, sea water quality,etc.) to optimizationmodels, which may have variouslevels of sophistication- The dialog subsysm, is the componentof DSS which providesthe essentialhuman-machine interface.Dramatic advances in software and hardwaretechnology have providedthe meansfor
158 the development of user friendly interfaces,-including high resolution color graphic, animation and multimedia prestion.tain Experience showed that decision support systems have been used in many areas of water resources management to the, point that they have become an indispensable part of decision making process- Taking into consideration series of still unsolved problems connected to: the recovery of Kastela and Trogir Bay; long-term effects of the discharge of wastewater into Brac and Split Channel; the required treatmentlevel; the impactof overflow waters; the impactof industrial wastewaters, system operation, etc. it is considered that the implementation of such DSS is essential. Implementation of DSS would make the long-term co-ordination of work and system construction with aIl four municipalities much easier, the public will be better informed and necessary decisions concerning progress of the protection of this region will be made much easier. By the implementation of DSS the proposed monitoring system could be efficiently and completely used, as well as all data that should be collected during the project preparation phase. This system will unite in one place all existing data and knowledge that are necessary for the efficient management of coastal water resources. It is necessary to mention that at the Faculty of Civil Engineering University of Split such system is in the development phase. T-he costs for establishment of DSS for areas of Kastela and Trogir Bay, and Brac and Split ChanneL as wel as for towns of Split, Solin, XaAtelaand Trogir were estimated at 395,000 US$
159 8. ESTIMATION COST FOR CONSTRUCTION, RESERACH, MONITORING, TRAINIG AND MAINTENANCE EQUIPMENT
ilVmAL P SE i-.. initial costs of the constructionof structurs for the protecon of Kahtelaand Trgir Bay, and Bra and Split Chamel were esimated as: - collectingsystem Split/Solin 24,700000 $ _ preliminarytatment plant "Stupe" 7,600 000 S s---ubmaineoutfall "Stobre" -6,350000 $ _ collectingsystem Kaftela/Trogir 28,500000 $ preliminaryteatment plant -Ctiovo - 6,600 000 S submarineoutfall "Mava6ica 3,100 000 $ SUB-TOTAL 76,850,000$
Monitoing 300,000S/year Research 700,000- 900,000S Computer-basedDeion SupportSystem for CoastalWater Resources Management 395,000S Tnrning of staff 125,000S Equipmentand tools for nce and control 850,000$
FLRSTPHASETOTAL 79,220000S
SECOND PHASE For the secondphase of the constuction of collectingsystem and treatmentplant the costs wll be approximately: - expediture of collectingsystem Split/Solin 16,000000 S - priary and secondarytreatment plant "Stupe" 42,800000 $ - additionalsubmarine outfalll Stobrea" 3,100000 S - expenditureof collectingsystem Kaktela/Trogir 14,000000 S - primaryand secondawytatment plant "Ciovo" 23,000000 $ - additionalsubmanne outfall "Mavaica" 0 S TOTAL 98,900000 $
160 9. PUBLIC HEARING
On October 24th 1996. JVP Hrvatska Vodoprivreda informed the newspapers to inform the public that public hearing of EIA for sewerage project will be done on'October 29th 1996.; for Trogir-Kastela sewerage systern it will be done at noon in Ka§tela city hall and for Split-Solin sewerage system at 6 p.m. at the premises of Engineer and Technician Association in Split The newspaper Slobodna Dalmacija in its issue dated Saturday, October 26. announced the public hearing. At the public hearing in Kastel Sucurac that began at 12,05 and finished at 15,20 were present the representatives of NG organisation "Lijepa nasa", representatives of towns of Trogir and Solin, the president of the Business Chamber of the Split county, the representatives of Mavarstica settlement and citizens. The study was presented by its authors, and representatives of Hrvatska Vodoprivreda presented general informations about the project. Mr Pejakovic, the General Manager of Hrvatska Vodoprivreda OJ Split, began the public hearing, greeted the present representatives and citizens and explained the purpose and way of presentation. The purpose of the public hearing was to inform the population about the study and to let them express their opinion about the planned project and the study. Mr Braticevic greeted the present in the name of the Govermment of the town of Kasela and emphasised that that the planned project has great significance for the town of Kastela and expressed his hopes that WB and EBRD by the end of November will decide to finance the project. Mr Petkovic presented the subproject of the water supply of this area. Mr Ivanci6 gave brief information about the development of the subproject of the disposal of wastewaters of this area. Mlr Margeta co-author of the study presented the subproject of the Trogir-Kasela sewerage system, wastewater treatment plant planned on tCiovoIsland and submarine outfall for discharge into the Split Channel. Mr Baric co-author of the study presented the chapters concerning the environment and national legislation, intemational contracts and EU Directive that concerns collection, treatment and disposal of wastewater and sludge. He also presented expected negative and positive impacts that the planned sewerage system and its installations could have on the environment Mr Margeta then presented the alternatives that were analysed during the project development and measures that were planned or should be undertaken in order to prevent or reduce the negative impacts on the environment. In the end Mr Baric presented the proposed program of the research and monitoring of the sea. Participants of public hearing asked the following questions and stated their opinion: KallelSm6urac lvna Bucan, NGO "Lijepa nasa" asked the following questions: 1. Existing industry in the area of Katela Bay is presently not operating and therefore it is not a polluter. What will the impact of industry on the planned collecting system be if it is put in operation again, and will it have impact on the quality of sea water? 2. What will happen to the coast in the area of Mavarscica after the construction of the planned outfall? 3. Is the planned level of purification sufficient to
161 protect the sea water in which the wastewater will be discharged? 4. Will the wastewater of the city of Split be purified in the same way? Will construction start in the same time on both systems? Miro Matijaca. His objection was that th project has the .sam approach for the entire area of the Kaftela Bay, when it shouldn't In his opinion, the main problem is the eastern'part of the Ka&telaBay. Therefore the problem of pollution of eastern part of the bay has to be solved in order to solve the problem of the entire bay. Financial resources intended for the western part of Kastela Bay should be used to solve other problems in this area Boris gkara. He asked why the wastewater treatment plant (tiovo) wasn't located 1000 m to the east? After the wastewater treatment plant is constructed where will the screenings be disposed until the sanitary depot for municipal solid wastes is built? Igor Novak, environmental inspector, Trogir. He is worried that discharged wastewater will pollute the coastal sea water because only mechanical treatment is planned. Tomislav tiZek, President of County Business Chamber, Split Has the estimate of operational and maintenance costs for the entire system been done and who will finance it? He is worried because the construction of the sewerage -system in the northern part of Ciovo Island wasn't planned. In his opinion the secondary sewerage network has to be constructed as soon as possible in order to eliminate cess tanks in the entire area. Ivo Rokov, NGO "Lijepa nasa". Were any measures planned in order to eliminate methyl- mercury from Kastela Bay? The level of bacterial contamination is only one out of !2 parameters for determination of the quality of bathing water. The problem of propagation of radioactive slag that was deposited on the grounds of ex "JugoviLil" factoryis also present in thie area of Kastela Bay. Veselko Andromak. The higher level of wastewater treatment gives opportunity for profit and therefore the highest level of wastewater treatment should be installed at once. According to Urbanistic Plan for Kastela the construction of the new road between Kastela Road (Kastelanska cesta) and Adriatic Highway (Jadranska magistrala) is planned. Could this planned road be used to lie the main sewer instead the old Kastela road (Kastelanska cesta)? Marin Bedalov. NGO "Lijepa nasa"' The collecting system is the foundation for the further development of the Kastela Bay but it won't solve all problems present in the bay (mercury, radioactive slag). There is a worry that this system won't be constructed in planned construction period because the decision about its realisation has already been postponed several times. Construction of the collecting system will save local wells that are jeopardised by numerous cess tanks which are permeable. He also point out that the citizens of Kastela are giving full support for the Project. Ivica Mivoncic, journalist. He is familiar with the project and he is supporting it. He asked will the Mavarscica Bay be occasionally polluted after the construction of collecting system? Were the institutions for the preservation of historic monuments consulted during the planning period because a pre-romanic church of St. Mavro is located in the area of Mavarscica. Tonci Buble. He doubts that the location for the wastewater treatment plant is a suitable one. He suggested that location should be discussed at the meeting of the City Council of Trogir and its displacement further to the east considered. He also suggested to increase the level of purification of wastewater. He asked what would happen if there was a pump breakdown or' power failure during the operation? How is it possible'that quantity of wastewater for Kagtela is
162 5 times greater than the quantity for Trogir? Is there a possibility for treatment of wastewater of Kastela in the area of Kastela and can it be discharged into the sea from tiovo? Is the old part of Trogir -included in the first phase of construction of the collecting system? Where will the headquuters of the Agency that will manage the system be located? - Stipe Gujinovic protests against the construction of the wastewater treatment plant and outfall in the Mavarscica Bay where the untreated wastewater of Kastela will be discharged. He asked why can't the wastewater be treated at the place of its origin. Ante Beljan. Will the construction of the collecting system endanger the area planned for tourism west and east from Mavarscica Bay? Why weren't all local communities included in the Project and Agency for solution of the problem of wastewater disposal? After all the participants asked questions and expressed their opinion, the authors of the Study commented and reviewed the discussion and answered the questions. They haven't answered particular questions. Instead, comments and answers were made in regard to particular themes. Comments: The wastewater treatment plant and outfall location in the area of Mavarscica The proposed location for the wastewater treatment plant and submarine outfall in Mavars6ica Bay and problem of possible pollution of sea water in the Mavarscica area drew the greatest attention and raised a great number of questions. The concern about the location was only expressed from inhabitants (permanent and owners of weekend houses) of the Mavars6ica Bay. Regardless of all comments and worries, the location of the wastewater treatment plant situated in the bay behind Mavarscica village and 250 m (and possibly more than 300 m) from the nearest hosing and 400 m from the sea is the most favourable location in accordance with the information given in Report Chapter 1. The fear expressed by inhabitants is understandable because they don't have the real conception of the wastewater treatment plant and the outfall neither they had an opportunity to see how the plant operates in practice. They believe that such treatment plant will be odorous and noisy and it will endanger the quality of living in the surrounding area. In order to eliminate their concerns it is necessary to inform them (organise additional meetings on the spot) about the characteristics of the plant, its operation and measures that will be undertaken in order to eliminate negative impacts. It is proposed, if necessary, to inform the representatives of local population in practice about similar treatment plants in the country and abroad. It is necessary to undertake all measures proposed in the Report because they are sufficient to eliminate all negative impacts. The danger of the pollution of the sea water in the area of Mavarscica is very small because the sea currents are parallel to the shore and there is a small possibility that discharged wastewater will be brought to the shore.
163 Treatment level Proposed conceptual design of treatment and disposal of wastewater guarantees, with high probability, that there won't be unwanted detrimental effects on the marine ecosystem ifall - proposed measures are undertaken (similar solutions in the area of Croatian Adriatic coast also prove it). Even if there were unwanted negative impacts, the planned monitoring program would detect them on time and measures for a higher level of treatment could be undertaken immediately. Problems of the common solution for Kaltela and Trogir It is understandable that local population isn't in favour of puification of the wastewater brought from other areas. Meanwhile, ecological and economical reasons justiiy the construction of unique system with one treatment plant and one outfall. Industrial wastewater Industry has to be treated in accordance with proposed measures which means that industrial wastewater has to be treated at the place of its origin in accordance with proposed criteria. Other questions Other questions (problem of mercury, radioactive slag etc.) haven't referred to Studies, but appropriate comments were made.
Split Public hearing organised at Society of Engineers and Technicians lasted from 18.10 -to 21.05. Split/Solin sewerage system and belonging wastewater treatment plant located in Stupe and submarine outfall located in Stobrec were discussed. Public hearing started the same way as public hearing organised in Kastel Sucurac. Participants asked questions and expressed their opinion. Ognjen Bonacci, university professor. The hydrology of the bay hasn't been taken in consideration during the Study preparation and nobody talks about it which is inadmissible. Pollution is brought into the bay by surface and underground water and nobody knows its quantity. Marko Sparac. Mavarkica Bay is polluted with oil and grease after the sewerage ring of Split city harbour was built because grit/grease removal wasn't installed as part of the treatment plant He is also concerned for the future of Mavarscica Bay after the planned collecting system is built Where are locations where nothing will be constructed so he can move there? He will use all available measures in order to stop the planned construction in Mavarscica Bay. Ljubo Juric. Proposed solution is perfect and he supports it completely. Grit/grease removal channels are missing at the location of existing treatmnentplant on Katalinica Brig. - - Arsen Ivanisevic He praised the authors for such detailed inforrnation and presentation of the Study. He suggests that all available measures must be undertaken in order to protect Mavarscica Bay. He proposedto changelocation of the treatmentplant Mavascica. Marin Maravic&What are the dimensionsof Mavarscicatreatment plant and how big is the open water area?
164 Drago Matosic. The urban wastewater treatment plant has to be located out of the settlements. Is it possible to treat wastewater of Kastela in the area of Kastela and to transport purified wastewater to'tiovo? - - - Ina gparac. Why can't Kastela Bay become as clean as it used to be?. Comments: Questions and remarks that referred to the location of wastewater treatment plant and outfall in the area of Mavarscica were similar to those asked at the public hearing in Kastela and therefore the answers and comments from authors were similar and won't be repeated. There were no negative remarks that referred to Split/Solin sewerage system. Participants expressed their praise of such good solution. The remark that referred to hydrology is correct if total pollution of Kastela Bay were discussed. It is not correct for the solution of the urban wastewater problem which is the subject of this Study. It should be solved in accordance with the 'proposed measures for the protection of Kagtela Bay (diffuse sources of pollution).
165 LITERATURE
I. Margeta J.; Preliminary design of sewerage system Split-Solin, Faculty of Civil Engineering Split, Institute for Urbanism Split, Water Authorities Split, Split 1988. 2. The Natural Characteristics of the Sea Water in the Kastela Bay and the Impacts of the Waste Waters. UNEP-MAP-PAP/RAC, Split 1989. pp.13 1. 3. A.Baric J.Margeta i KGaEi6; Environmental capacity of Kaktela Bay, UNEP-MAP/PAP, Split 1988. 4. M. Orlic, M. Kuzmic i Z. Pasaric; Modeling wind inducted streams in Kaitela Bay, UNEP- -PAP/RAC,Split 1989. 5. Margeta J.; Conceptual design of the sewerage systern of Kastela, Gradevinski fakultet Split, 1989. 6. Oceanographic Study of the Brac and Split Channels for the Integral Ecologic Project Split- Solin-Kastela. Institute of Oceanography and Fisheries, Split 1990.pp.190 (in Croatian). 7. Oceanographic Study of the Brac and Split Channels for the Integral Ecologic Project Split- Solin-Kastela. Institute of Oceanography and Fisheries, Split 1991. pp.59 (in Croatian). 8. Project "Enviromnental Management of the Kakela Bay" Synthesis of the first research cycle 1988-1993. University of Split, Split 1994. pp. 196 9. Investigation of "red tide" phenonmena in the Kastela Bay. UNEP-MAP-PAPIRAC, Spli, 1991. pp. 34 (in Croatian) 10. Margeta J. and others; Preliminaiy design of sewerage system Split-Solin, Projects: Analyze of data, Tunnel Stupe, main trunk of north catchmnentarea, Submarine outfall Stobrec, Treatment plant Stupe, Study of long term effects of waste water discharge in Brac and Split channel, Faculty of Civil Engineering Split, SFC-Salzburg, 1990. 11. Margeta J.; Construction design of I phase wastewater treatment Stupe, Gradevinski Fakultet Split, SFC-Salzburg, 1991. 12. Margeta J.; Conceptual design of the treatment plant Katalinic Brig, Gradevinski fakultet Split, SFC-Salzburg 1991. 13a.Selection of the optimum Treatment Level for the Central Treatment plant, Volume L Final report. UNEP-MAP-PAP/RAC, Split, 1992. pp. 50. 13b.Selection of the optimum Treatment Level for the Central Treatment plant, Volume IL, Ocenographic Properties of the Split and Brac Channels as sewage Effluents Receiving Environment UNEP-MAP-PAP/RAC, Split, 1992. pp. 66. 13c.Selection of the optimum Treatment Level for the Central Treatment plant, Volume III, Evaluation of the Waste Water Influence upon the Brac-Split Channel by using a simulation Model. UNEP-MAP-PAP/RAC, Split, 1992. pp. 5 4 + Annexes. 14. Margeta J.; Study of the sewerage system of town Trogii; Gradevinski Fakultet Split, 1992. 15. Margeta J.; Concept of the solution of sewerage system of Split-Solin, Gradevinski fakultet Split, 1992.
166 16. Margeta J.; Environmental impact assessment study of the sewerage system Split-Solin, Gradevinski fakultet, Split 1992. 17. Margeta J., A. Baric, and others; Environmental impact assessment study of the I phase of submarine outfall Stobrec, Gradevinski fakultet, Split 1992. 18. URBS; Land use plan of community Split, Solin and Kastela, Split 1976. 19. URBS; Land use plan of community Trogir, Split 1978. 20. Margeta J, and others; Environmental impact assessment study for the sewerage system Kastela-Trogir, Faculty of Civil Engineering, Split 1995. 21. Oceanographic Properties of the Brat and Split Channels as receptors of waste waters. Institute of Oceanography and Fisheries, Split, 1991. pp.78 (in Croatian) 22. Environmental Imopact Assessment for the Split- Stobrec Wastewater Discharge System. UNEP-MAP-PAP/RAC, Split, 1991. pp.43 . 23. Oceanographic Investigation of the Trogir Bay for the purpose of the Environmental Impact Assessment of a Submarine Outfall for the First Phase of the Sewer System. Institute of Oceanography and Fisheries, Split, 1993. pp4 2 . (in Croatian). 24. Project 'Environmental Management of the Kastela Bay" Synthesis of the first research cycle 1988-1993. University of Split, Split 1994. pp. 196. 25. Oceanographic Properties of the Brac and Split Channels as receptors of waste waters. Institute of Oceanography and Fisheries, Split, 1991. pp.7 8 (in Croatian). 26. Environmental Impact Assessment for the Split-Stobrec Wastewater Discharge System. UNEP-MAP-PAP/RAC, Split, 1991. pp.4 3. 27. Investigation of "red tide" phenonmena in the KaYstelaBay. UNEP-MAP-PAP/RAC, Split, 1991. pp. 34 (in Croatian). 28. Oceanographic Investigation of the Trogir Bay for the purpose of the Environmental Impact Assessment of a Submarine Outfall for the First Phase of the Sewer System. Institute of Oceanography and Fisheries, Split, 1993. pp. 42. (in Croatian). 29. Preliminary Environmental Impact Assessment of the Sewer System of the Kastela. University of Split, Faculty of Civil Engineering, Split, 1995. pp. 100. (in Croatian). 30. Bari6, A., 1. Marasovi6, M. Gacic,(1992). Eutrophication Phenomenon with Special Reference to the Kastela Bay. Chemistry and Ecology, 6, 51-68. 31. GESAMP. 1986. IMO/FAO/UNESCO/IAEAIWHO/WMO/UN/UNEP Joint Group of Experts on the Scientific Aspects of Marine Pollution. An Oceanographic Model for the Dispersion of Wastes disposed of in the Deep Sea Rep. Stud. GESAMP 19. Rome: FAO. 32. Goldberg, E.D. 1979. Assimilative Capacity of U.S. Coastal Waters for Pollutants: Overview and Summary. In: Proc. of Workshop on Assimilative Capacity of U.S. Coastal Waters for pollutants at Crystal Mountain, WA, ed. E.D. Goldberg, pp. 1/7. U.S. Dept of Commerce NOAA Working Paper No.1.
167
APPENDIX 1
CALCULATION OF THE SUBMARINE OUTFALL LENGTH Ecological dimensioning of submarine outfalls "Stobreal and "tiovo"
Contents: Methodology of calculation Methodologyof calculation of initial dilution Lmear sourcesof Boliution Pont sourcesof oilution Methodologyof calculation of secondary dilution Brook Model CDR-2DModel Calculation of submarine outfall "StobreE" Input data and analyzed alternatives Results Calculation of submarine outfall "tiovo" Input data and analyzed alternatives Results
Bibliography Appendices Methodology of Calculation
After a discharge from sbmarie outfall orifice, wastewatr is mixed with the recipient water forming a pollutedplume that is gradualy spreadingthough the recipient. Sincethe concenations of somepollutions from the wastewaterare severaltimes smallerin the recipient,mixing of wastewaterand recipientwater causesthe dilutionof thesepoilutions. Basicaly there are two phasesof the wastewaterdilution in the recipientwater. First phase is the iniial dilution that follows immediatelyafter the discharge of wastewaterfrom submnaineoufall orifices Movenent of plwne consistedof wastewaterand recipientwater is under dominantinfluence of kinetic energy that wastewaterhad after the discharge from the submarine outfall ofice because of exit velocity and the difference betweendensity of wastewaterand rmcipientwater. There are two causesof dilution.The first is velocitygradient that existsplume jet and recipientas well as turbulencein that area; the secondis direct lateralflow of recipientwater into the plumeby meansof horizontalrecipient streaL Secondphase or secondarydilution follows after the plume densitybecomes equal to the recipientdensity so the movementis causedby movementof water masses (stream)of recipient itself Dilution generateddurmg this phase is the result of turbulenceswithin the recipientstreamL Methodology of Calculationof Initial Dilution Thereare two basic methodsthat are used to determinethe initialdilution. They are: - parametricmodels - models derivedfrom basic conservationlaws In this study parametricmodels were used. Parametricmodels are used to determne charactistics of initial dilutionprocess by dimensionalanlyses of fommulasthat are approved by experienceas functionsof one or several number of constants or parameters. Values of constants are dependent on hydrodynamiccharaistics of plumeconsisted of wastewaterand recipient waterand they are determinedexperimentally on physicalmodels. Parameterscan be classifiedinto three groups: - parametersthat characterize-thesubmarine outfall, - parametersthat characterizethe recipient, - parametersthat are combinationof the previoustwo. When wastewater is dischargedfrom point sources of pollution (outfall without diffuseror with diffuser with great distancebetween orifices), the followingparameters can be classifiedinto the frst group: - wastewater velocity at the diffuser orifice v0, - wastewater density po, - vertical angle of discharge cp, - volumeflow Q = v.4, - flow of mass quantityMo =vQ. For linear sources of pollution (dischargeof wastewaterthrough the diffuser with small distancebetween orifices) the followingparameters can be classifiedinto the first group of parametersthat chacterize submarineoutfall:- - wastewater density po,
2 - vertical angle of discharge Vaisal-frequency N = (g ) Uplift flows Jo andjo are classified into the third group of paramneters: - =$Qo; go,=P. pO- PO 9 jo= gAqo as well as several others undimensional parameters. For e.g. for linear sources of pollution they are: :1i =° ~lb=° * 1. =j213 F=v while for point sources of pollution, parameters are the following: IB =N314 ,1 = J11 s2 =V.3 s e=N Basically, any characteristic of the initial dilution process can be expressed as function of previous parameters. The following paraneters of the initial dilution process are the most important for the engineering practice (Figue 1): - minimum level of initial dilution S,,, defmed using the concentration of the observed parameter as: S. CO- C. C.c-c - maximum concentration level z,... - maximum upwelling of polluted plume z,, - thickness of polluted plume h., - length of the area of initial dilution xi, - width of wastefield in the end of initial dilution w1, - depth of discharge H 3 1 X. J. 'U'W .~~~~~~~~~~~~~~~~~~~~~~~. ve~ ~ ~ ~Ca ~ r Fi-gure). Brooksmodel of the initial dilution: S, = 0.3$gc"3q-2 3H [1] is the most commonly used in present engineeringpractice. It is used only for linear source of pollution in calm, unstratifiedrecipienL Since streamsin the sea are permanent,and uniformvertical profileof density only an exceptionalphenornenon, this model doesn't give a real picture of initial dilutionin stratifiedrecipients and recipientswith pronouncedhorizontal streams. The recent resech conductedby Roberts (1], 12], [3] and [4] will be used in this study. The result of these researches are several parametricmodels for linear sources of pollutionin unstatified and linearlystratified media that can be used in practice. For point sourcesof pollutionresults of researchesconducted by Lee [51will be used. He criticallyanalyzed previous models and offered few of his models that can be used in practice. Lmicarsoures of olfutfo For linearsource of pollutionand unstatified media with horizontalstreams, and for valuesF 4 4/A<0.2 and "lb<0. 31 . Under these conditions for values F<0.1, the influence of streams on initial dilution isn't significant, and therefore: *213 = 097 Jo, For values F>O.1 solution depends on F and 0. For e.g. for 0.1 5 *2/3 = 2.9F" - 0S2 Jo For angles OW010,for engineering purposes, in previous expressions projection of velocity vector to the axis of diffuser normal can be used. Beside the level of initial dilution, in linear stratified media significant are also: the height of minimum level of dilution within the polluted plume zm, that is maximum upwelling of polluted plume ze and its thickness he, as well as the length of the area of initial dilution x, and the width of the wastefield in the end of the process of initial dilution w,.. For F=O values of parameters ze, Zm and he can be determined from following ratios: 2,26h,~ 2 J '=2.6; = IS.E = 1.7 b b b Between F=0 and F=Q0. values z,, z, and he are slowly increasing, to become approximately constant till F=l. For angles 4S0 <8<90"and Froude number values of l 5 Point sourwcsof pollution The following outfalls should be treated as point sources of pollution: submanine outfalls where diffuser is situated on relativelysmall depths and the distancebetween the orifces is big enough so there is no mixing between adjacentpolluted plumes, as well as smaller outfalls where diffuser is not required since satisfying dilution is achieved by dischargefrom onlyone orifice. If the recipientis unsatified, pollutedplume is upwellingall the way to the recien surface.For suchrecipient and the conditionthat pollutedplume is underdominant influence of uplift (xA,<<1), minimun level of dilution for horizontal direction of dischargeof wastewatercan be determinedfrom followingratios: S. =0.31 ° H<5- S. =0.32 va.H ; Hz:5jv QO V.- For linearstratified recipient without stms and for horizontaldischarge of polluted plume that is under dominant influence of uplift, that is if WBad.6, minimum level of dilution S,., phumethickness he and maximun upwellingz., can be determinedfollowing expressions: 0.0 ; 4 =4.01.6 J11144T4 ff horizontalstreams exist in staified recipient,for vertical upwelling of pollutedplume from point source of pollutionthat is underdominant influence of uplift force,values of S.,, h. and z. can be determinedfrom ratios: 1.=2-) . ; _= 2.1i - Methodology of calculataon ofsecondaiy dilution Method that is most commonlyused in engineeringpractice to calculatesecondary dilution of wastewateris modeling of hydrodynamicsof sea masses using hydrodynamic models. The flow filed, generatedin that way, is used as input data for modelof dispersion and transformation of observed polution indicator. Results of initial dilution model (concentrationof observedindicator) are alsoused as inputdata for secondarydilution modeL Hydrodynamicsof sea massesis in this study determinedassuming the most negative forms of velocity field that are acceptablefrom the standpointof bacteriologicalpollution. For modeling of dispersionand transformationof pollutiontwo models were used: Brooks Model and CDR-2DModel that was producedat Civil EngineeringFaculty in Split Forrner was used for modelingof bacteriologicalpollution, BOD-5 and suspendedsolids, whilethe letter was used for modelingof bacteriologicalpollution only since it was proved to be effective. Brooks Modl -- Brooks Model is based on the assumptionof uniform and constant dischargeof wastewaterfrm linearsource of pollutionof lengthL, installedperpendicular to the direction of sea cunrnts v, (FIfgun2.3-X). Streams are timespaceconstant, and have the directionof x 6 axis. Vertical diffusionD. and diffusion in directionof sea streamsDs are disregarded. Results of initial dilutionmodel are used as input data for BrooksModel tirough maximrnum concentrationof observedparameter within polluted plume c.,e dx(D,oy)~ v - K:c= o where: c - concentrationof analyzedparameter, K - coefficientof reaction, v, - velocity of recipient stream, Horizontaldiffusion Dy dependson the widthof wastefieldL: Dy = aL 4 '3 where values of coefficient a are between 0.0015 and 0.0449 cm2' 3 /s. The value of 0.01 is most commonlyused in practice. Accordingto Brooks,the value of maxmumnconcentration of observedparameter at the x distancefron a diffuseris givenby followingexpression: -K;73/212DY C. c,e " erf vsL where: 24 erf(a)= le 2d* The widthof wastefieldL. at the distancex canbe determinedfiom ratios: Lx _(1+2i) L J3L) CDR-2D Model CDR 2D Modelis used to calculatesecondary dilution for unstrtfied recipient,when polluted plume is dischargedall the way to the surface of a recipient.Minimum level of dilution under these conditionswill be found at recipient surface.Polluted plume is then spreadingthrough recipient under the influenceof surfacestreams. Only the surfacelayer of the recipientwill be modeled (assumringthat vertical diffusioncan be disregardedbecause calculation is on safe side), and therefore2-D model will be used. Since the nature of phenomenonallows it (analyzedarea is relativelysmall and pollutionis travelingonly few hours beforeit reachesthe shore),this problemcan be regardedas stationary. The followingequation fonns mathematicalbase of the model: ac aca(&i)a( &)-- V-ar +vy a-=- aD- i)+ aD- (D, Kc X~~ Y -aX5-exay ~ay) where: v- and v, - components of velocity vector of velocity field in x andy direction, c - concentrationof observedindicator, D. and D. - turbulentdiffusion in x andy direction, 7 K -coefficientof reactionof idicator. Ibe solutionof equationis usualy searchedfor over observedarea LI for naturalboundry conditionson an open boundaryr, formedas: r - - (D. arv.s. +(D, w -v,Sy =q(xy) ; (xy) i r-- where n. and n, are componentsof nomal vector, and constraint boundaryconditions on boundaryr 2 formedas: 4X,y)=g(x,y) ; (xy)rEr2 The FmiteElernents Method was used to solvethis mahmmaticalproblem Weak formulationused in this model is determned assumingthat there is no diffusion on open boundaries. (D. c}z +{(Dy, S = 0 ; (x,y) r and it is formed as: _ |(v. &V y-+IDOO+YY ayaY wherew are test functions. Selected weak formulation allows certain flexibility in formulation of constraint boundary conditions.Formulation allows omting of boundary conditions through open boundarieswhere exists the flow of parametermass due to streams within recipient. It is assumed there is no diffusion of mass through these boundaries, which means that only convectivecomponent exists thrgh these boundaries.Possible enor due to this assunption is several times smaller that possible error due to arbitrary defined constraintboundary conditions. In order to secure unifonimtyof solution, it is enough to defme constramnt conditionin only one of the nodes. SDGM (spacediscontinuous Galerkmn method) 16] is used to fmd the solutionin form of linearcornbination of localizedbasic functions: c= c,4p,,;r = 1,2,...,n where qp,islocalized basic functionfor node r of finite elementsnet, and n is total nunber of nodesin the net. Test functionsare given in followingfonn: w. (P.>+8VS a. ov s;5-]2 where: v Ax+V Ay Pe, - Dc+D - Peclet-number 8 In previous expressions Ax and Ayare characteristic lengths of elements in x andy directions. Test functions will retain the form of standard Galjerlin method in regard to boundary conditions. The following system of linear equations is formed: M,,c,=D ; r,s=1,2.n where matrix is: "Vo 4. -wap +vPW rS Alf., tD. Xar0z +PY ayV OIy>s+ -D~'w, 5 +1y* lp w. +Kq,xYwk -SD-(-pr+DY w-W-O - 0~~~~~0Y Uniformnityof solutions is secured with constraint boundary conditions. If functions are linear, the last member of matrix Ms.r is canceled. Matrices and vectors of upper (global) system are built of finite elements matrices and vectors. Frontal procedure is used to arrange and solve global vectors and matrices. 9 Calculation of submarine outfall "Stobreo. Input data and analyzed alternatives Maximumdischarge of wastewaterat this subem outfall is 880 £I Wastewater will be mchanically purified prior to discharge. It is assumed that the concentrationof coliform bacteia m wastewaterafter mechanicalpurification will be 8.16f APN/lXinI. Wastewaterdensity is around 1000(gAri. Selected aLtemativeof submanne outfall is situatedaround 16W0m from the shore, diffuserlength is 400n7,and depthof dischargeis around 37m. From the results of oceanographicresearch of Bral and Split Channel sea water conductedin Septemberof 1990.and April of 1991.for purposesof pollutionmodeling, the followingfacts can be observed: - at the location in front of Stobrec there is distinct vertical stratificationof sea density, it can be acceptedthat the average sea density is around 1028 k&i&, a thermoclineis present at depth of around10 m. - time of bacterial decay T 0 in surface layers is between3 and 5 hours, and it is graduallyinmcreasing with the depth, - based on results of measuringof sea curents in Brac and Split Channelin frontof Stobred (measurng station is situated 2-3 km south from the outfall location), stream velocities m the surface layer were chosen that are, m regard to their frequency and duration, acceptable for calculation of propagationof bacterial pollution. Critical streamdirections are toward the shore and thereforeonly these values will be given: directionN v,=13.9aDh directionNE v ll=.8ank, directionNW v,=2O.2ans directionE v,=11.6cmA/s Minimumvelocities are around1.5 cm/s. Initial dilution will be determinedon parametricmodels and results will be used as inputdata for secondarydilution model. According to already existng uDl)ctive concerning classificationof water and coastalsea water", open sea of Brac and Split Channelis classifiedas ElT category,while the coastalsea belt of 300m widthis classifiedas if. caWoty, Thatmeans that submarineoutfall must have such characterstics to secure that bacterial concentrationm the outfall area is lowerthan maximumallowable for sea water of IZTcategoty (20000 MPN/IOOmlhn). Diffuser must be installedon such distancefrom the shoreto securethat bacterialconcentaion within pollutedplume that would reach the coastal area is less than maximumallowable for sea waterof H. category(5OMPN/IOml). Two characteristicaltematives were analyzed: - first alternative examined the winter period, analyseswere conductedassuming there was no verticalstratification of densitywithm the recipient, - second alternative analyzed the summer period when vertical stratificationis distinct assumingthat recipientis unstratifiedunder the thermocline(thennocline is present at depth of around10 m). 10 For calculationof initial dilutionbottom strearn velocitieswere used, while for calculationof secondarydilution surface velocities were used. Values of bottom velocities -wereused as half of surfaceones. Yor first alternativecalculation was conductedfor all four previouslymentioned criticaldirections of surfacestrearns toward the shore: - directionN, surfacevelocity 13.9 cmls, bottomvelocity 7 cm/s, - directionNE, surfacevelocity 11.8 cm/s, bottom velocity 5.9 cm/s, - directionNW, surfacevelocity 20.2 cmnls, bottom velocity 10.1 cm/s,; - directionE, surfacevelocity 1l.6 cn/s, bottomvelocity 5.8 cmls For these four alternativesBrooks Model and CDR-2D Model were used to calculate secondarydilution.. Area covered with CDR-2D Model (figure with discretisationmodel is given in Appendices)was the surface layer of sea water aroundthe outfall, and its part toward the shore that was appropriatefor deterninationof the concentrationof coliformbacteria at the entranceto coastalsea area.Thus, this modelwasn't analyzingonly the coastalsea belt where sea waterwas classifiedas II category(200m away frorn the shore),but the area out of that zone. Modeledarea wasdiscreted with the net consistedof 720finiteelernents. Nine-nodal 2- D elementswere selected,therefore the net consistedof 2993 nodes.In order to decreasethe osciDlationsof the solutionswhere differencesin concentrationsare the greatest,the fuiite elernentnet was mademore denseat the outfalllocation. Since this model was not requiring it, boundary conditionswere not defined on boundariesthat were in contact with discardedpart of the continuum,it was assumedthat there was no diffusionof mass throughthese boundaries.Model required solutionvalues to be defined in only one of the nodesof the net which was fulfilledin the model by assigning the results of initialdilution. Results of initial dilution were assigned as known values at the diffuser location. These valueswere assignedto sevennodes situatedon that location.In that way, the impact of wastefieldwidth on secondarydilution, and impact of diffuserposition in regardto wind directionwere included in a model to a certaindegree Coefficientof diffusionwas selected according to BrooksModeL For diffuserof 400 m its value is: DX = D, = Im2 /s. Assumedtime for 90% of bacterialdecay on the surfaceis T9035hours. Duringthe summerpolluted plume will be retainedand spreadunder the thermocline layer, and there would be no possibilityof its passing above that layer. Due to that reason calculationof initial dilutionusing paramneticmodels for second altenative was conducted using the assumptionthat seadepth was reduced for thermoclineheight. Second alternativeanalyzed three critical directionsof streams toward the shore. Bottomvelocities were used to determineinitial and secondarydilution: - directionN, bottomvelocity 9 cn/s, - directionNE, bottomvelocity 8 cn1s, - direction NW, bottom velocity 10 cm/s. As additional altemative, that was acceptablefor outfall location, calm recipient with minimum velocityin the area of plume upwellingof 1.S cns was also analyzedFor this alternativeonly the BrooksModel was used to calculatesecondary dilution. Assumedtime for 90%of bacterialdecay under the thermoclineis Tw,=5hours. 11 1 Results ;-dThem ling results are presentedon figuresand tablesthat are givenin Appendices. Results of CDR-2D Modelare presentedas isolines. Assignedline presentsthe bactad of SOOA (JWC&nsice it is maximumallowable concentration (according to existinglegislature) infte coastalsea area (coastalsea belt of 2W0mwidth). Selected step for drawig of isolinesis 500AMPN/I7anLSome winding of isolinesand appearanceof isolines of 0 concentrationsare the resultof smallernumerical oscillations. Resultsof initial dtion modelingshow that bacta] concentrationafter the process of inital dilutionhas ended, for the most criticalalternative of stagnat rocipient,are around 20000 APN/1Onl, which is maximum allowable concentration for sea water of ilL categmy.For other altemativesthese valuesare below legallyrequired. Thus, diffuserfulfills legal bacterial criteria at the outfall location. The same can be concludedfor suspended solids.Their concentrationare significantlybelow legally requiredof 60mng/ifor sea water of lTlctegoiy. Results of secondary dilution modeling using both models show that for neither altemativebacteral conentrationin the coastal sea area hasn't exceeded509 APN10X9nl, which is maximumallowable concentration for the sea water of ff categary.Concentrations of suspended solids are significantlylower than required 20 mg/I for the sea water.of II category That impliesthat chosen distanmcof diffuser from the shore is acceptablein regard to the preservationof coastalsea area frompollution. 12 Calculation of submarine outfall -tiovor Input data and analyzed alternatives Maximumdischarge of wastewateris 650 Us-It is assumedthat the concentrationof coliform bacteriain wastewaterwill be JdMAPPN/anl. Wastewaterdensity is around 1000 1g4W. Selectedaltemative of submarne outfall is situated around2050 m from the shore (measuredfrom the spot where submarne outfall enters the sea), diffuser length is 400 m, and depth of dischargeis around52 m. From the results of oceanographicresearch of Brac and Split Channelconducted in Septemberof 1990.and Aprilof 1991.,the followingfacts canbe observed: - at the outfall locationthere is a distinctvertical stratification of sea density, and it can be acceptedthat the averagesea densityis around1028 kg/r, a thermoclineis presentat depthof around12 m. - time of coliformbacterial decay T,v in surfacelayers is between3 and 3 hours,and it is graduallyincreasing with the depth, - based on results of measuringof sea cunrentsin Bral and Split Charmel at the outfall location, stream velocitiesin the surface layer were chosen that are, in regardto their frequencyand duration,acceptable for calculationof propagationof bacterialpollution. They are: directionN v,=15na" directionNE v,=l6a7/s, directionNW va=16mA/, Minimumvelocities are around1.5 cm/s. Initial dilution will be determinedon parametricmodels and results will be used as input data for secondarydilution modeL Twocharacteristic altematives were analyzed: - first alternativeexamined the winter period, analyseswere conductedassuming there wasno vertical stratificationof densitywithin the recipient, - second alternative analyzed the summer period. when vertical stratificationis distinctand thermoclineis presentat depth of around12 m, assumingthat recipient is verticaly unstratifiedunder the thermocline For calculationof initial dilution bottom stream velocities were used, while for calculationof secondarydilution surfacevelocities were used. Values of bottom velocities wereused as half of surfaceones. For first alternativecalculation was conductedfor three previouslymentioned critical directionsof surfacestreams toward the shore: - directionN, surfacevelocity 15 cm/s, bottomvelocity 7.5 cm/s, - directionNE, surfacevelocity 16 cm/s, bottomvelocity 8 cm/s, - direction NW, surface velocity 15 cmls, bottom velocity 8 cwu/s. For these altemativesBrooks Model and CDR-2D Model were used to calculatesecondary dilution.. Area covered with CDR-2D Model (figure with discretisationmodel is given in Appendices)was the surface layer of sea water around the outfall, and its part towardthe shore that was appropriatefor detenninationof the concentrationof coliforrnbacteria at the entranceto coastal sea area. Modeledarea was discretedwith the net consistedof 720 finite 13 elements.Nine-nodal 2-D elementswere selected,therefore the net consistedof 2993 nodes. The finiteelements net wasmade more denseat the outfalllocation. Boundaryconditions were derned similary as far the previousoutfalL - Results of initial diution were assigned as known values at the diffuser location. Thesevalues were assignedto sevennodes situatedon that location.- : Coefficientof diffusionwas selected accordingto BrooksModel. For diffuserof 4W 2 m its value is: DS D = 1m /s. Assumedtime for 90% of bacterialdecay on the surfaceis T.w=3.5hours. During the summerpolluted plume will be retainedand spreadunder the thermocline layer, and there is no possibilityof its passing abovethat layer.Due to that reasoncalculation of initial dilution using parametricmodels for altemativewith thermoclinewas conducted using the assumptionthat sea depth was reducedfor thenrocline height, and recipientwas unstratified. Three critical stream directions toward the shore were analyzed for second alternative..Bottom velocities were used to calculateinitial and secondarydilution: - directionN, bottomvelocity 9.5 cm/s, - directionNE, bottomvelocity 10 cm/s, - directionNW, bottom velocity 10 cmls, As additional alternative,a calm recipient with muinimumvelocity in the area of plume upwellingof 1.5 cmlswas also analyzed.Assumed time for 90% of bacterialdecay under the thermocline is T,w=6hours. Results The modeling results are presentedin Appendices.Results of CDR-2D Model are presentedas isolinesthe sameway as it wasdone for previousoutfall. Results of initial dilutionmodeling show that bacteral concetation afterthe process of initial dilution has ended, for neither alternativehas not exceeded maximunmallowable concentrationfor sea water of lZZ categy. The same is valid for suspendedsolids. Their concentrationare significantlybelow legallyrequired ones. Results of secondary dilution modeling using both models show that for neither alternativebacterial concentration in the coastalsea areahasn't exceededmaximum allowable concentrationfor the sea water of 11 categmryThe same can be concludedfor suspended solids. That implies that chosendistance of diffuserfrom the shore is acceptablein regardto the preservationof coastalsea area fron pollution. 14 Bibliography 1. Robczts P.J W; Line plume and ocean outfall dispersion;Journal of the Hydraulic Division,ASCE 105(HY4), 1979. 2. RobertsP W, Snyder W.H.,Baumgartner DJ.; Oceanoutfalls I: Submergedwastefield formation;Joumal of HydraulicEngineering, ASCE 115(1),1988. 3. Robets P1. W., Snyder W.H.,Baumgarter DJ.; Oceanoutfalls II: Spatial evolutionof submergedwastefield, Journal of HydraulicEngineering, ASCE 115(1), 1988. 4. Robrts P1 W., Snyder W-., BaumgarTerD]; Ocean outfalls III: Effect of diffuser designon submergedwastefield; Journal of HydraulicEngineering, ASCE 115(1), 1988. 5. Lee J.H W., Nevilke-ones P.; Initial dilutionof horizontaljet in crossflow;Journal of HydraulicEngineering, ASCE 113(5), 1987. 6. Kmwnousi DA.; A spacetimediscontinuous Galerkin method for the two-dimensional unsteadyconvection-dispersion problems; Water Resources Management 6: 35-45,1992. 15 Y .*.:...,.,...... ,'>.... . ::i...... ::. : X'.". 1' 2 E i W_2 _jrEi! P io, it ...... ?^ P;: .11MiFHIM~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~...... ...... r~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~....>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..1 .... : :, , 5' : : ,' ' , ' '. .', K , , ' . , ,. ,' '': / , \,' , t e , o ' ' ' : ' i ' : . ' '.,'' ' ' , S...: ...... :.:'E".//.:,..f:', ...... '0 , s' 'C"'' T \ ^ ''. : : . v \ ',','',E',",:,:,.f,,:,...... t,.': ',,,,, ...... :...' . ::0s'l ' :; ...... f .'w/\. .. , .. , t. l i i ag .i2< y/ ...... $ \? jgi:gi 0/ /- W: /bt/...... 7:,:: g L / N } / oJ~~~~~~~~~~~~~~~~~~~Ci ri7- ,i..j..,, .:E...... O,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Rhi/ z 18 RESULTS FOR THE NEARFIELD AND THE FARFIELD MIXING ZONE STOBREC: Unstratified ambient, north-west current 20.2 cm/s - effluentflowrate: 880 I/s - effluentdensity: 1000 kghn3 - diffuserlength: 400 m - angle betweendiffuser and current 900 - depth 37 m - heightto the top of the wastefield 37.00 m - currentvelocity at the bottomlevel: 0.1 m/s -currentvelocity at the levelof the top of the wastefield: 0.2 m/s - ambientdensity: - bottomlevel: 1028kg/rn 3 - surfacelevel: 1028kg/m 3 - effluentcomposition: IPN: 8000000(coli/lOOmI) BOD-5: 235 (mg/i) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: finimumdilution : 975 M bPN:: X 8201 (collOOMI) B01D-5: 0.241 (ig): Suspendedta: -; 0-287 (m/) Results for the farfield zone: DistanCe Minimum MPN BOD-5 I Susp. tot. (m) dilution I (cGliUlOml) (mng/I) (mg9I) 200 978 .6816 0.237, 0.286 400 1017. : 460 0225 0.275 600 1097 4218 0.206 0.255 800 1198 3216 0.185 0.234 1000 1313 24:46 0.167 0.213 1200 : 1436 1864 0.151 0.195 1400 1565 1424 0.136 0.179 1600 1700 1092 0.124 0.165 1800 1840 841 0.113 0.152. 2000 1984 650 W0103 0.141 2200 :2132 : ,504 0.095 0.131 2400 2284 392 0.087 0.1:23 2600 2440 306. 0.080 0.115 2800 2599 239 0.074 0.108 3000 2762'2- - 487 i-- - 0.069 .WO101 19 RESULTS FOR THE NEARFIELD AND THE FARHELD MvIINGZONE STOBREt: Unstratified ambient, north current 13.9 cm/s - effluentfowrte: - 880 its - effluentdensity: 1000 kglnn -diffuse length 400 m - angle betweendiffuser and current 45 ° -depth 37 m -height to the top of the wastefield 37.00 m - currentvelocity at the bottomlevel: 0.07 m/s - currentvelocity at the levelof the top of the wastefield: 0.139 rn/s - ambientdensity: -bottomlevel: 1028 kg/n? - surfacelevel: 1028 kgAln3 - effluentcomposition: MPN: 8000000(coli/lOn0l) BOD-5: 235 (mg/i) Suspendedtotal: 280 (mgI) Results for the nearfield zone: ,- M,n, u 4miton:- :-: '540:: -'-" '--"'''"" ' -" A9PN: 1'"'4806 (colihlOO "I ' --' - - '-BOtD-5. '(j350."'4 (mg/I)'''' -- - Suspendedtota 0.. (m_..) Results for the farfield zone: Distane Minimum :- MP -I BOD-5 Susp.-tot. (in) - .dilution .(co,liulOrl.0b)- '(jg/I) ~'- -(mg/I) 200 7- 11041 0.413 - 0.503 400'' : -'642 7372 - 0.352 0.436 :600 757 4809' ' 0293:' 0.370 '800: ' ' ,886 -- '- - 3160. '' 245 0.316. 1000 1024 2101. : .208 0,273 . 1200 1171 1413. '.0.178 0.239 1400 1,324 '0.154 961 , 0.211 1600. 1485 659 .0.135 . 0.189 18'gOO . 1:651. 456 . 0.119. 0.170 2000 .,.. 1824 . . 317 -0106'. 0.154 .'22000. 20 -222 0.094 0.140. .2400 2185' 157 0.085 0.128 :2-600 2374 111". ').076 0.118 2800 2569 79 0.069 0.109 3000 2768 56 - 0.063 0.101 20 RESULTS FOR THE NEARFBELDAND THE FARFIELDMIXING ZONE STOBREt: Unstradfied ambient, east cmTent 11.6 cm/s - effluentflowrate: 880 I/s - effluent density: 1000 kg/i 3 - diffuser length: 400 m - angle between diffuser and cufrent 450 - depth 37 m - heightto the top of the wastefield 37.00 m - cufrentvelocity at the bottomlevel: 0.06 m/s - current velocity at the level of the top of the wastefield: 0.116 rn/s - ambientdensity: - bottom level: 1028 kgk/3 - surface level: 1028 kgkn3 - effluent composition: MPN: 8000000(colillOOnl) BOD-5: 235 (mgA) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: MPN:i?t E 0i 14806 (6 OOMI) BOD-5:.: ..... 35... :.4 .: Suspendetotal:.03518 (mgAI Results for the farfield zone: Distance . Mi m MPN BOD-5 Susp.tot. (in) - -diiution . oIOl (mg/I) - (mgA). 7-0200 570 t -- ;5-10251 0.403 0.491 400 685 : 22 :t0685Q327 00.409- 600 832 3741 0.263 0.337: 800 995 2284 0.215' 0.281 1000 1169 1418 0.178 0.239 1200 1354 894: 0.150 0207 :1400 1.549 571 0.128 0.181 1600 1752 368 0.111A 0.160 18000 : 1963 240 0.097- 0.143 2000. 212 1 58 0.085 0.128 2200) 2409-- t 104 0.075 0.116- 2400: 2643 - 69 0.067- 0.106 2600 2885 46 0.060 0.097 2800 3133 31- 0.054 10.089 3000-. 3389 . -21 0.048 0.083 21 RESULTS FOR THE NEARFIELD AND THEFARFIELD MXIG ZONE STOBREt: Unstratified ambient, north-east currat 11.8 cm/s. - . - effluentfowrate: 880 Vs - effluaentdensity: 1000 kg/sn3 - diffuser length: 400 m - angle betweendiffuser and curent 0 ° - depth 37 m - height to the top of the wastefield 37.00 m - currentvelocity at the bottomlevel: 0.06 n/s - currentvelocity at the level of the top of the wastefield: 0.118 m/s - ambient density: - bouom level: 1028 kWMi3 - surface level: 1028 kg/rn' effluentcomposition: MPEN: 8000000(colilOOrnl) BOD-5: 235 (mg/¶) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: :Minimum-- diuon: 540 ..-. MN - 14806. --- (coir -B:D-5 -. -^. - 0.435 -(mg SusPendedtOta:058 zg Results for the farfield zone: ;Distance :Mii - ' - BO-5. Suap. .ot. 0 - 1738 - 337 f .'161. 400 . 36.66.062 1 192 - . 0.077 600 5504 536 0.037 0.047 o800 - 8537 272.- :0.0250.033 :1000 11476 148 0.(018. L0Q04 .1200 14691 - 5 .i 0.014 0A019 : j41J() - 1816i0 - 51 - 001 1 0.015 1600 218:66 31. 0.009. 0.013. . 1800 25795 -19. : 0.007 . .011 2!000-- -299134 : :12 0.:006 0.009 2-00 -- 34274 -8 -,-005 - 08 2400 38805 5: . 0.005 0.07. -O 2600 43520 3 . :O4 0.006,;: :2800 484 . 2 - 0.003.06 *`3000 53475 :.. 0.03 0.005... . 22 RESULTS FOR THE NEARFIELD AND THE FARFIELD MDXINGZONE STOBREt: Stratified ambient (thermoclina 10 m), north-west current 10 cm/s - effluentflowrate: 880 us - effluentdensity: 1000 kgftr? - diffuserlength: 400 m - angle betweendiffuser and cunrent go90 - depth 27 m - heightto the top of the wastefield 27.00 m - currentvelocity at the bottomlevel: 0.1 m/s - currentvelocity at the levelof the top of the wastefield: 0.1 M/s - ambientdensity: 3 - bottomlevel: 1028 kgkn 3 - surfacelevel: 1028 kgknm - effluentcomposition: MPN: 8000000(coli/lOOmI) BOD-5: 235 (mg/) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: Minimumdilution: ::712 :- :; -:C:--tMPN:: ::O23911: (coli/Om) 00: ;L BOD-5: 0330 (rag/A):..... Suspendeddtota t0393 mgIl): Results for the farfield zone: Distance :Minimum vMPN BOD-5-4 -Susp. toL (inX) ilutifaon;d -- i/lOIo :- (-mg/I) - (mg./ItX)-- . :200~- i-: 7420 7: : -- :8348 . :: -:0308:- -0.377. 400 875 :5487 0.254.' 0.320 0 1048 - 3547 Q 0206- 0.267 800 1241 - .:=2320 0.1:69 -0.226 -1000 1448 1540 0.141 - 0.193 1200 1,667 1036 -0.119: :0.168 134030 1897 705 0.102:z,:: 0.148 1600 02137 485 0.088 0.131, 1800 2386 336 0.077 0.117 2000 2645 235 - 0.067..':: 0.106 2200 2913 - 165 0.059 0.096 - 2400 . 3189 - 117 0.053. ; 0.088 2600 3473 83 -. 047 - 0.081 2800 3765 59 0.042.: 0.074 3000 4065 43 0038 -0:069. 23 RESULTSFOR THE NEARFIELD AND THE FARFIELD MIXING ZONE STOBRE6: Stratified ambient (thermoclina 10m), north current 9 cm/s - efuent flowrate 880 V/s - effluentdensity: 1000 kgwri1 - diffuserlength: 400 m - angle betweendiffuser and curent 450 -depth 27 m - height to the top of the wastefield 27.00 m - currentvelocity at thebottom level: 0.09 rns - currentvelocity at the level of the topof the wastefield: 0.09 rn/s - ambientdensity: - bottomlevel: 1028 kghri3 - surfacelevel: 1028 kgWn -effluent composition: MN: 8000000(coli/lOOml) BOD-5: 235 (mgO) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: Results for the farfield zone: Die,.,immX Mi ,.,'BO- fis..:ot 2.00 m.~ m12 .- VA55 m 400 - 64 -:i3437- -- ..35 600 5-A,4 4...... 4.. 10001207 (L1671602 i.232.4 1400 ~1650"' 64011 270~ ..w...... i-8Q::-:..0:7 200- .23 6 19O.M 2L 7 2200 26 120.6 2400~~n 29433 .0!.O049 .0~9' 2800> ~352,S' 3~ ..0.043 . 24 RESULTSFOR THE NEARFIELDAND THE FARFIELDMIXING ZONE STOBRE6: Stratified ambient (thermoclina 10m), north-east current 8 cm/s - effluentflowrate: 880 I/s - effluentdensity: 1000 kg/m3 - diffuserlength: 400 m - angle betweendiffuser and current 0 - depth 27 m - heightto the top of the wastefield 27.00 m - currentvelocity at the bottomlevel: 0.08 rns - cunrentvelocity at the level of the top of the wastefield: 0.08 m/s - ambientdensity: - bottomlevel: 1028 kgM3 - surfacelevel: 1028 kgkn3 - effluentcomposition: lPN: 8000000 (colill00iml) BOD-5: 235 (mg/I) Suspendedtotal: 280 (mgAl) Results for the nearfield zone: Results for the farfield zone: DiStanceMinimum MPN ~~BOD-5S Sus.tt 400 - 510 766 0.040 010 600 923 0 (W30 800100 191513990 teS)S10'tW2Xd557041 0 0.020010~ --1200 2474 ~ 4S 0.008' 0.01 J73, 7 4.04005' 0410530041106A-066' _.~~IS0~220 599307.: 4 aDw.0M.0 0.007 2400..67,335 3 .. 0.0 0.0 25 RESULTS FOR TBE NEARFELD AND TE FARFIELD MIXINGZONE STOBREt: Stratified stagnant ambient (thermoclina 10 m) - effluentflowrate: . 880 U/s 3 - effluentdensity: 1000 kgrn -diffuse length: 400 m - anglebetween diffuser and cufrent 900 -depth 27 m -heightto the top of the wastefield 27.00 m -currentvelocity at the bottornlevel: 0.015 m/s - currentvelocity at the levelof the top of the wastefield: 0.015 m/s - ambientdensity: - bottomlevel: 1028kglrn 3 - surface level: 1028kcg/r 3 - effluentcomposition: MPN: 8000000(coli/l00ml) BOD-5: 235 (mg/I) Suspendedtotal 280 (mg/I) Results for the nearfield zone: -- --- um .394-----.-:: - - -:MPN:--- :.20290 (coli10Omi) -BOD:5 - .- 96 (m/) Suspendedtotai:: : 01, (mgi)- Results for the farfield zone: Distanor, M- - - - :.MPN -N -'BQ:-5- Susp.to. -(m) dilufi -. (odl0i/ l ld) ___lm --200 1008-- 14 0.194 0.278 400 1977 134 0.082 0.42. 600 3144 15 0.043 -0.089 800 4479 2 0.2: 0.063 1000 5962 - 0- 0.016 0.047 1200 -7581 0 0.010 a.037 1400 9324 0 0.007 0.030: 1600 11183 0 0.005. 0.025 -1800 13152 .0. . 003 0.021: 2000 15224 : 0 . 0.002 0.018. -2200 1739: 0 0.002 0.016. :2400 19661 0 0.001 - 0.014 2600 22017 - 0 O.O1 0.013 2800 24460 0 0.001 0.011 3000 26988 0 0.001 0.010 26 .... '~.1 I ~~~~~~~~~~~It ...... ~."4 \ 1 ~~~~~~~~~~~~~~~~~~~~.'.'...... ''5'''':' .....''s.'55...... I'...... s.l \~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~...... |'\ //w1/g/\\ ' i \v \A,,, \H ''\Xi RESULTSFOR THE NEARFELD AND THE FARFIELDMIXNG ZONE CIOVO: Unstratified ambient, north-west current 16 cmsm -effluent flowrate: 650 U -effluentdensity: .io 1000kglm 3 -diffuscrlength: 400 m - anglebetween diffuser and current 30 0 - depth 52 m -heightto the top of the wastefield 52.00 m - currentvelocity at the bottomlevel: 0.08 rn/s - currnt velocityat the levelof the top of the wastefield: 0.16 n/s - ambientdensity: - bottomlevel: 1028kgMn 3 - surfacelevel: 1028kghn' - effluentcomposition: MPN: 10000000(coli/lOOmi) BOD-5: 235 (mg/1) Suspendedtotal: 280 (mg/l) Results for the nearfield zone: Results for the farfield zone: Distanc iimm MN (i) dilution. BOD- Sus.to 200.968... 8223. ~~~~.0.239 .0289 i'0.'0'V;'.""".'".11-39-.' ,50 . R 0... I" 2 600 ~~1362; 3702 0.6A 00 800 161] ~~~~2491.: 0,.136 ~0I7 -1000d 1879: J 1700~ 0115 019 1200 2121176 0.098 02 140 2459 823 '0.085 014 1600 2769 58 ;~0.074 00 .2000 346 | 29 0.058 .082D 2200 3772 ~~~~~215. 0.5 0.:~.074 .2400 .. 4128...47..i0.096. 0..8Z 2600i8Z16:---tu449,5 154 .0420 0.062,1 28S00 48 84- 0.038 . 30 . 5261 624 t.085.1.0.:34 29 RESULTSFOR THE NEARFIELDAND THE FARFIELDMING ZONE tIOVO: Unstratified ambient, north-east current 16 cm/s . -effluentflowrate: - 650ls - effluentdensity: 1000 kgftri3 -diffuserlength: 400 m -angle betweendiffuser and current 60 ° - depth 52 m - heightto the top of the wastefield 52.00 m -caent velocityat the bottomlevel: 0.08 ns/- -currentvelocity at the level of the top of the wastefield. 0.16 mls - ambientdensity: - bottomlevel: 1028 kgkr? 3 - surfacelevel: - 1028 kg1in - effluentcomposition: MPN: 10000000(colIfOOmI) BOD-5: 235 (mg/) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: Minimumd--ition- 1286-.---:: MPNf 7777 (cAol/oOrnl) ,,OD,-,5 0#3.183(g) Reut Suspendedtotali 0218,(mg/) Results for the farfield zone: Distance}Minimum MPN 'BOD-5' Susp.tot. (m) dilution , (coli/l0Omo) '(.mg/I) j .(mgOI) .200 1300 6121 .0.178 0.215 400 1416 4473 . 0.160: 0.198 600 1598 3155 0.140 0.175 800 1811 2217 ' 0.121 -0.155 1000 2042 1565 0.105'" 0.137 '1200 2288 1112 0.093 0.122 1.400 2545 796 ' 0.082 0.110 1600 2812 573 0.073, 0.100 1800 3089 415 .. 0.065 0.091 2000 3375 303 0..059 0.083 2200 3670 221 -.0.053 ' 0.076' :2400 3973 ' 163 '':0.048 -0.070 2600 42U4 .120 0.044' 0.065 .52800 ' . 4604 89 0.040- .061 3000. - '--,,,,4930 ' 0.03 :660.057. 30 RESULTSFOR THE NEARFIELDAND THE FARFIELDMIXING ZONE tIOVO: Unstratified ambient, north current 15 cm/s - effluent flowrate: 650 I/s -effluent density: iooo kgA 3 - diffuser length: 400 m - angle between diffuser and current 15 ° - depth 52 m - height to the top of the wastefield 52.00 m - current velocity at the bottom level: 0.075 m/s - current velocity at the level of the top of the wastefield: 0.15 m/s - ambient density: - bottom level: 1028 kglm' - surface level: 1028 kg/m3 - effluent composition: MPN: 10000000 (coli/lOOmi) BOD-5: 235 (mg/I) Suspended total: 280 (mg/I) Results for the nearfield zone: Miiimum dilution.: 29 M:N: 10761 0oli/looml)) :~ ~ BD5 ; - E- 0.2503 (mg/) i 2 Suspendedalot-:- 0.301(0mg/) Results for the farfield zone: .. Distance Minimum - MPN BOD-5 Susp. tot. M(i) dilution (colI:::ml)j (mg/1) (mgAI) 200 1071 7322 - 0215 0.262 400 1437 4277 0.158. 0.195 600 1869 2578 0.119 0.150 :800 2344 1611 A0.93 0.119 1000 2856 1-037 0M75 0.098 1200: 3401 683 0.062 0.082 1400 3978 458 0.052 0.070 1600 454 311 0.044 0.061 1800 5218 :14 - 0.38 - 0054 20010 5879 149 0.033 0.048 2200 6565 05 0.029. 0-043 2400 7277 74 0.026 0.038 2600 -8012 53 0.023 0.035 2800 8771 38 0-0021 0.032 ~-300- ... 9552M! - 27 ..- A0.019 0.029 31 RESULTS FOR THE NEARFIEUDAND THE FARFIELDMDXNG ZONE tIOVO: Straified ambient (thermoclina 12 m), north-west curent 10 cm/s - effluentflowrate: 650 I/s - effluentdensity: 1000 kgkn3 - diffuserlength 400 m - angle betweendiffuser and curent 300 - depth 40 m - height to the top of the wastefield 40.00 m - currentvelocity at the botton level: 0.1 m/s - currentvelocity at the levelof the top of the wastefield: 0.1 m/s - ambientdaisity: - bottomlevel: 1028 kgkn3 3 - smfacelevel: 1028 kgkn - effluentcomposition: MPN: 10000000(coli/lOn1) BOD-5: 235 (mgI) Suspendedtotal: 280 (mg/) Results for the nearfield zone: --Minimumilution: - 714. ' '' '-.'. 'MPN: -':''14008 (coliu0m) - O:: D 5: E- -0329 (magI) Suspendedtota: 0.392( Results for the farfield zone: Distance -inum I -- PN -- BOD-5 .Susp.toL. (m)1 diution (colihlOoml)|(nig/) (mg/) 200Q -- 815 9505 .281 0DI44 400 1083. 553 0'5O25- :. . 600 1401 3315 0.154 0.200 800 1751 2055 0.120 40.160 1000 2127 1310 0.096 0.132. 1200 2528 854 0.079 0.111 1400 2951 566 0.066 0.095 1600:. 3396 381 0.055 -0.082 1800 3861 260 0.047- 0.073 2000 4346 179 0o.41 0.064- 2200 4850 124 0.036 0.058 2400 5371 .87 0.031 ;0.052 2600 : 5911 61 -. 0.028 - 0.047. 2800. 6467. 4-3 0.025 0.043 :3000-- 7039 : 31 0.022 0.040 32 RESULTS FOR THE NEARFIELD AND THE FARFIELD MDXNG ZONE tIOVO: Stratified ambient (thermoclina 12 m), north-east curent 10 cm/s - effluentflowrate: 650 Ils - effluentdensity. 1000kg/rn - diffuserlength: 400 m - anglebetween diffuser and current 60 ° - depth 40 m - heightto the topof the wastefield 40.00 m - currentvelocity at the bottomlevel: 0.1 mn/s - cunrentvelocity at the levelof the top of the wastefield: 0.1 m/s - ambientdensity: - bottomlevel: 1028 kghn3 - surfacelevel: 1028 kg/m3 - effluentcomposition: NIPN: 10000000(coliulOCni) BOD-5: 235 (mg/I) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: Mimmumdlution 236 BOD-S: 0~'.,190(g/) 10 ~~- d---od' Results for the farfield zone: .Distnce~ Mlium j P O- Ss.tt 0 -975 : .214 4001576 4145 0~~~~~ ~~~.14107 600 191 2752 0 $.113 0.146- ;---80v;0 2297- ; 1857 -3 X :0.092-- - 1122--. -100 2704 - 1275 0.06 .0404 200 ;3134 889 0.063: - 89. 1400 1 3586 628 0.054 0.078 .1600 4.0459 448 .0.0, , . . . 2000 502 235 0.05 0.5 2400 .12,0..'7 0 2137 .0.4 2600 6706 4 0.02 0.042 - 30002'787352 - 43.020 .j .0,033 33 RESULTS FOR THE NEARFIELD AND THE FAFTIELD MIXNG ZONE CIOVO: Stratified ambient (thermoclina 12 m), north current 9.5 cm/s -efflnt flowrate: 650 Is -effluentdensity. 1000kg/m 3 -diffuserlength: 400 m -angle betweendiffuser and current 15 ° - depth 40 m -heightto the top of the wastefield 40.00 m - currentvelocity at the bottomlevel: 0.095 m/s - currentvelocity at the levelof the top of the wastefield: 0.095 mls - ambientdensity: - bottomlevel: 1028 kgkn3 3 - surfacelevel: 1028 kgAn - effluentcomnposition: lvIPN: 10000000(colinloomi) BOD-5: 235 (mg/I) Suspendedtotal: 280 (mg/I) Results for the nearfield zone: .. D-5: , 0. 32. ..(mg/I) Suspenedtoal: 0392 (gI Results for the farfield zone: Distance Minmm-I---. MPN:----- :- 5-1) 5. ::.400 93 477 0148 0. 87 600 91 244 0.103 -0.134 800 2754 1481 . 076 0.02 1000 3476 938 0.058 0.081 1200 .: :;4252 - 613:-: ::.46 -- : 0:066 14#00- 5079 -.- ;-410 - 0.0.38.:-.5. 18:.00- 687 .. 19 .0 .04. 2000 7834. 136 0.022 .036 2200 888960019. 03. '2600 192 , 49. .0015..12 '2800 .100 6O.1 0.2 3000 '.A13233. . .20010.1 34 RESULTSFOR THE NEARFIELDAND THE FARFIELDMIXING ZONE &lOVO: Stratified stagnant ambient, (thermoclizma12 m) - effluentflowrate: 650 I/s -'effluentdensity: 1000kghn - diffuserlength: 400 m - anglebetween diffuser and current 9o -depth 40 m - heightto the top of the wastefield 40.00 m - currentvelocity at the bottomlevel: 0.015 n/s - currentvelocity at the levelof the top of the wastefield: 0.015 m/s --ambientdensity: - bottomnlevel: 1028 kgfn3 - surfacelevel: 1028 kgrn3 effluente composition: MPN: 10000000(coli/lOOmI) BOD-5: 235 (mg/I) Suspendedtotal: 280 (mg/) Results for the nearfield zone: minimm diluion: 7-15 M- N: 13989 (coli/l00ml) -BOD-.B5 0X :0.329 (mg/I) Sed : .:-stotal:0392 (-mg/) Results for the farfield zone: Distance 1 N B -5Mii-mum'l s s in) ' I 'dilution I (coi:-OOti) j W- )- : -:200::E- 1827 -480 - 0.107 :0.153 40-0 3585 21 - 1l78.045 600 -: 5700 1 0.624 0.049 800 8120 0 0.014 0.034 1000 10810 0 0.009. 0.026 1200 13744 0 0.006. O.020 1400; 16904 0 0.00 0.017 1600 20275 0 0.003 0.014; 1800 23845 0, 0.002 0.012 20040 _27602 0 0.001 0.:010 -2200- 31538 :0.0010 0.009: 2400 35646 0 0-.001- 0.008 2600 39917 0o0.001 0.007 2800 44347 0 -0.000 0.006 3000 I 48930 0 -.-:0.00600 35 The main dcaracteristicof all these fresh water inflows Lt Sea cLrrents and se ec hag is a grt flucation in the course of the year, with the eception of the Cetina River whose inflow is paerly The Brac and Split channels form a semi-closed basin r-uated by a systm of resevoirs and s thus, uniform where the water is exchanged from three sides: from theus ent ditection of the Brac channel, Le. from the East, and though the Sola and Drvenik channel in the West. The The Sesh water fim the local ttg regions whayg' ftesatrog h ptsai n h atl relativel clean, so that it does not significantlyinfluence Bay is negligiblecoMpared with the prviously meioned the sea qualty. The wat from the Cetina and Jadro ones. The average penod of the sea exchange m these River is clemaand mninlybelongs to the first category.The chnns has been estimated to 2.25 months. The most iluence of the rivers and stream flows is evident in significant current are from the East westward which ii decreasedsalinty and temperature,and to a smaller extent. also the directin of the mmn sea exchange.These currents in increased concentation of oxygen and nutrient salts. are the strongest along the central axis and particularly in Tis, however, does not ply to the streamfioss which the surface layer. The measured ma.amum velocities range drain parts cf the urban and agricultal areas The water about 50 cm/s with a westward frequency of 49%. The from these rt-gons is poluted and significantlyifluences most frequent velocities are from 6-20 cmIS, with a the coastal sea water quaityan the areas around its decreasefrom the surface towardsthe bottom. dischw pomt, and to a smaller extent, in wider areas as Under the influence of loWlasting winds the currents we. field changes, both in the surface and bottom layer, where From the pollution standpoint the most sgnificant is compensaon currents are formed. Hence,eastem currents the communal hydrologic system wich icludes the are sgnificant in the summer months, with a smaller swwae system of both waste water and stom run-off intensity than the western ones, as well as southem These waters exert the greatest pemma influenceupon currents. In the central ara, where the channel is the the sea quality so that they are most importantfrom the sea wndest and in front of Stobrec, cyclonic vortices are formed, caused by the bottom configuration. Thus, it can Protectionstan be concluded that both global currents and the se The sea hydrologic systemunifies the influencesof a exchangeare orientedwestwards. wider boundary region, the naual fresh water hydrological system and the communal hydrological 12 ydrlogialsytandwastewater system of thecadered aam influence of the boundary regions is exemtd through the sea water The transportation of poLution is mainly effected exchange with the Brac Cbannel, the Solta ChanneL the throughthe hvdrologicalsystem and partly through the air. Dnk Channd, thwoughthe Split strait and through the This s"stemconsists of tbree main segmes (Fig.l): exchange with the Kastela and Tgir Bays. - natural fresh water subsystem Cnsequey, it can be wcluded that the hydrologic - naturalsea water sbystm systemof the Brac-SplitChannel is complex and varying: - commuunalsubsystem and henc it is difiEcultto analyze all types of influences The area of the Brac-Sphit Channel is relatively upon the sea quality.In the analyze the sea boundaryareas abundant in fresh water, the average precipitationis ca 0.8 represent diffuse eements of that influence, whereas the m. Significant quantities of rainfall and its frequency rivers and similar the elements in the fresh water (more than 100 days a year), result in great quantities of hydrologic subsystem are thated as point sources of fresh water which flows-into the sea (2510.78 million pollutio. The communal hydrologic system as a whole m3/yearas average). rpresets a point sourceof the influenceupon the Channel The fresh water flows from the three main catchnete eaqu areas: All these ldementsin hydrologic tems and all their - directly, by precipitation, upon the sea surface (189 charactcristicsare taken into account when analyzing the millionm 3Eyearas aage), sea water quality. It means it is necessarvto considerboth - indirectly from the coastal catchmient area (local their quaniy and quality,the avag values and a specific watershed)(215 million myear as average), time period. - by tbumaries whose catcment area is beyond border of the coastal wateshed line (2106 million m3year as 1.3 The conemptof the solutionfor the sewerag system avp)- The entire area for the waste water disposal covering The most significant indlowsare from the Ceuna river towns: Split, Solin, Kastela and Trogir includes two (awrage flow 55.22 m31s), Jadro river (9.2 mN3/) and independentsewer systnms:Split-Soln and Kastela-Trogir. Znovnica river (2.1 m3k) whose catchments are farther The solution concept is such that all waste water in each away in the hinterland Smaler inflows are from the local system should be deldied to one central treatment plant coastal area, mainly during the rainy period of the year. and one submarineoutfall. Consequently.in the futur this -whereasin summer these inflows are alnost negligible. area will have only twotrealuent plants and two outfalls. - - - .- ,~~~~~~~~~~~~~~~~~~~~~~~~-- - - ~ ~ ~ ~~ ~ ~ ~~ ~~ ~ ~ ~ ~~-~. -:~~~~~~~~PiCP?IO -- :,. _esus - - rltsctPlT r-- .. . . TI uj .r. .!-~<' . U=0s| b~~~lt: tOca NNTaJSLAND Ct 1 1 |X MAE REO7N EU _I?E I _ CES BRACand SPLIT CHANNEL sRl *C XcO "T"HS OLT l C"^" CHANtFL . zxcthara 1tH LtEL. EXCMNOt WITH V7#VXNX PAW CHANNEL . :XCHAOE MSTH Tt OOIJ p EXCHHANO 15ITH OPEN Figure 1. Hydrologicalsystem of the Brac-SplitChannel The planned sveir system is of separae type. Te long time be able to finance the functioningof the sewer industrial %aste water is delivered to te uftban sewer systemand paymentof the loans, accordingto the planned system,sunder the conditionthat its quality is te same or final solution which will ensue a high standard of sea better than the qualitv of typical domestic waste waler proteuiot. This primarily refers to the cost of the plant (except considering BOD),which has been prescribed by const=ction and operation. Consequently, system the respectivemunicipal regulations. Csutlaion in phases hasbeen planned, consideringboth The st.m nu-off is collected Thle storm run-off IS collected by a separatescparate sewerwftr cntutothe neterk andnp~ae the treatmentsta plantahnwivsmn,ie The objectiveof this system and is discharged into the coastal sea by satisfying constructionim phate s psthateach fsvestment, new s.et the sea standards at each outfal. structure, immediatelyhas posit= eLs upon the wastal The wAstewvater disposal system tncludes the treatmen sea quality,which is the particularlyattactive for the local T w oi thcneatmpopulation. This ojecuve will be achieved by the plant and the respectivesubnarine outfaJl. The plants and constructionof longsubmarine outalls wtich dislocatethe outfalls form a unique technological unit which will be disposalof wastewater iomthe asal sea inothte fxther constncted in phases in aCcordancewith needs Four auin off rgions. phaseshave been planned: . A questionto be asked is: what wilt happen with those 1. Mechanicaltreatsnent with sub-phlases: other parts of the sea? Since the greatest part of the Brac- - partial mechanical Split Channel is safe and clean, the following question - completemechanical treatment anses: will this conceptual solution ensure that the sea 2. A phase of AB physic-biologicalprocess quality remains the samnei.e., to what extent will the sea 3. B phase of AB proess qualitybe changed? It means that not only shon-term but 4. D.enitrxication,dephosphatizUtion and deshectio also long-term effects of waste water discharge upon the Each phase includes the cons=tion- of a respective sea qualityshould be considered submarineoutfall which together with the treatment level. The analysisof long-termeffes includes the procesws shouldsatisfy the requiredse staItds. identified by the oxygen and BOD concentration.The oxygenconcentration as a parameteris used to describe the - The present state of the systemis such that the planned s af sea wi regard to the releasedorganic matter. conept could not be completely rtalized in less than 10 which is dotminant in domestic wate sater, and with yeas, even if all the necessary fiundingwas available at regard to n-tnes antd possibleenvironmeatal long-term once. In addition, it should be born in mind that the hreardou effects inhabitants of this area, i.e. their standard, will not for a Short-term effects are related to bacteriological and Agency [2]. It is a three-dimensional stationary model physical pollution (oil and suspension materials). The which implies that the pollution is completelymixed both analysis of short-term effects makes it possible to - horizontallyand venically in each element of the system detemine the necessarylength and location of sumarine Theoretically, the -model is based upon the mass oatfals and the characteristics of the mechanical plant __conseration law with the possibility of modeling two which is usually constructedalso as a protective measure reaction variables in the feed forward form for the first for the fumctioningof the submarineoutfall itsel order kinetics. The program has been primarily developed The dojectiveof the preeted analysis is to determine in order to model the system BOD-dissolvedoxygen the allowable pollution quantities which can be relased (Fig.2), so that the model can be used also for determining into the Brac-Split Channel according to the planed the concentations of other parameters for analogous solution concept for the sewer system in tis repgon processes such as:, chloride, poliphosphates- This paper presents the analysis of long-term effects by ortophosphates, coliform bacteria. i.e. all oonventional applying a simulation model for calculation of oxygen polution parameters.and the parameterswhich decompose concentrationin the sea water. aording tothe first order kinetics. This is a regional model is used fof defining global states in a wider area so that the elementsare relativelylarge. 2. MAIN CHAR4CTERISTICS OF THE MODEL The analysis was performedusing the HARO-3 model- dveloped at the Umted States EnvironmentalProtection re o of aa reaeration inflow from the re . ;i photosinthesis NBOD . ~~~~~exchangewith I + . ~~~ 1 ~~~~~°2 . -^ adjacent aquatoria benthos demand sedimentation I Figure 2. Schematcal representationof the computationfor oxygen concentation by the HARO-3model The mathematicalbasis of the model is the equaton of for the carbon phase of BOD (CBOD=L,): convectivediffusion including the dements which describe k-k, L (3) the reaction, sinks and sources of the analyzed pollution parameters:, for the nitrogen phase of BOD (NBOD=L,): - & acc ac acc (4) , a +v = E. r+E E, +E,E-2 +kc±S, where: k, - reaction coefficientfor CBOD(1/day) -here :-s (Ik-coordinate reaction coefficientfor NBOD(I/day) whtere: k/ - reateiationcoefficient (l/day) n y, _- coordinatcdirections k, - benthosdemand (gO2lm2iday) 3 v. v,, i' - flowvelocities in directionsx, y. z k, - oxygen production(gO 2 hn/day) E. E,. E - dcspersionint directions x. y. Z c, - oxygensaturation value (g An3) c -concentrationof the treated parameter The reaction coefficientsare corectd according to the S,- sources and sinks of the parameter Tbe ton applyints relon: k -coefficientof the fist order reaction actual timpertore applng the ion: The element in the equation which descnbes the kXEY'z" - - -reactiondepends upon the simulatedparameter, so that the where: expression(kc) for oxygenbudget is as follows:- -, - t coefffciert k.(c2 -cj-k~L~ -k i, ---~+k (2) k4o- tempeature coefficientat 200 C H ' . e 9-e coefficientdependent upon the simulatedreaction Developingthe equationfor each discretizationelement increased to the value of 100 m-ls towardsthese regions. of the systemby the finite differencesmethod it is possible The vertical dispersion is significantlysmaller and it was to obtain n" linear equations of the system with In' taken with a value of I m2fs between the first and second umknowrs: layer,and with the value of 3 m2/s betweenthe second and 1C]=[A] ' 1 - - (6) thirdlayer. - with the matrices: The modelemploys a parametersand coefficients: IC] - matrixfor the computedvalues of the pollution paramder - - * - I - Re-aeration coefficient )-- [W]- matrx of externaleffects/loads (boundary The re-aeration coefficientwhich includes the oxygen conditions) exchange between the surface sea la)er and the [A] - mnatixof the elementsof effects(coefficients). atmosphere; k,(cr-c) includes the saturation value of -. -: - dissolved oxygen (c,) and the current *alue (c). The saturationvalue was computedaccording to equation: 3. MODEL OF THEEBRC-SPLIT CEkNNEL c, = a0.8127- 0.7496 t + 0.03718.r - 0.000'-J (7) The modelof the Brac-SplitChannel covers the area of where t i temperar, which is obtained accordingto the the westernpart of the Brac Channel and the entire Split measurement results at the stations, by processing data Channel westwardup to the Drvenik and Solta Channel. using the least squares method. The reaeration coefficient The model does not include the Kastela and Trogir Bays, (k.) was chosen accordingto the average %vindvelocity and but it includes the sea exchange occumng through the is 0.2 (llday)for the entire surfacelayer. straits of these bays. The model includes the sea exchange Benthos demand (kb) occurring through the Brac, Solta and Dnenik Channel, Since only geeraeommendatin forethes ves sherea the exchange through the Split strait is not taken were given by oceanographers,the coefficientvalues were into account, since it is not significant. The channel are determinedby the model calibration ranging,between 0.25 has been divided into 139 elements withthree depth lavers and 1.0 (g fhemo/day)e or fewer, accordingto bonomconfiguration (Fig.3). The systemof currents is determinedfor each element Reaction coefficients kj by using a hydraulicmodel or by adjusting it to the actual The adopted coefficient values for the first phase of values of the sea exchangeand the distributionof velocities organic matter decomposition CBOD (kD)and for the according to measurementsas it was done in this case. second phaseof NBODdecomposition (k,). are as follows: Since this is a stationaryregional modelit uses the average k,= 0.1 ( llday) expected vaies. The adjustmezttprocedure stars from the kI = 0.005 ( Iiday) quantity of the sea exchangein the channels. the measured values and the determined global currents. Such approach Oxygenp roduction kJ proved very useful since it made it possibleto introduce The oxygen productionwas computedaccording to the into the model all the specific features of the currents in chlorophyll?roduction and amounts to betmeen 001 and this area including the vortices and the compensation 0.02 (gO,jm /day) for the surfacelayer. No productionwas 3 currents. The average channel dischargeof 3500 m /s was - assumed to occur in the deep layers. obtained. The dispersioncoefficient wvhichgives the best . . - resultsin the greatest pan of the model. comparedwith the The polluon quantties were taken according to aste one measured at the gauging stations. is 20 m2ls. The only water disposal alternatives which uere analzd and exception are the parts of the sea around the Solta and accordingto the expectedfuture situationsin the area. Drvenik Channels which are directly influenced by the Table I presents the main input data for the urban waste open sea, so that the coefficient should be gradually ter and poltion quantities. Table 1. Quantities of wastevwater and organic pollution - Quantity Wastewater qualitv - Dailvq ties Seweragesystem (Ils) BOD-5 N-total BOD-5 N-total ______(mg/I) (mg/I) ft/day) (kg/dav) Split-Trogir 2000 250 40 43200 6912 Trogir-Kastela 650 270 40 15163 2246 Solta 120 270 40 2799 414 Brac 230 270 40 5363 933 The industrial waste water quantities were not The pollution delivered into the sea vith the urban specificallytaken into account since they were considered storm run-off was computed and the following average in the sewer systems solutions, i.e. all industrial waste loads were obtained: -- water is deliveredto the urban communal sewersystem. - BOD-5 1968 kg/day - - N total 118 kg/day Apart from dispersion,the greatest influenceupon the TIhepollutionentering the sea by diffuse flows from c results was exerted by the process of benthos oxygen remaining parts of the rspective catchmet area w demand folowed by the oxygen production by introduced into the comptuation throug the b dy photosynthesis;thus, special anention was paid to the conditions,i.e. the sea qualityin the boundaryareas. - - and selectionof these parameters. Pollutant loads, such as those flowig by the ground water or settling from the atmospher. which cannot be 4. RESULIS A-NDDISCUSSION easily predicted, ware introdAucedinto the modd thrugh the edstig state of the sea quality in the area under Accordingto the resultsobtained by calibration,present conderation. state and planned solutions for the waste water disposal In order to make it possible to apply the model it was into the Brac-Split Channel, it was possibleto perform the necesay to perform. the model calibration and simulationof the sea watr qualihtfor several alternatives verification The quant and quality of the available data lated to the waste water treatmentlevel. wme not qmte satisfacto* but could be considered Fig.3 prtect the results obtained according to the sufficient for a global evaluation of future states. By alternative in which the waste water uill be treated only adaptng the dispersionand reaction coefficientswitnhm the mechanically. nomnnalvalues it was possibleto achieve good agreement with the measuredvaitese - -. 14,013l,'0.3 -0.,;-0 .Z I . , IIS. 2 -- , - 1,0 0.-(l.31D.3(E 03.26 0394.329.4 Z94.8 95.8 97.0 - .,~~~~~~~~~~~~c :~~~~~~~~~~~~~~~~~~~M .. .2 I I A-,t3h .6g!K8.8Q.2/[email protected]. ) Figure 3. Oxygensatuation percentage-alternativeof the mechanicaltreatment The presented show that the sea quality regarding the the nutrient salts concentration. howvever, occum percentage of -oxygen--saturation Aconesponds to -th - dowaisreamfrom the Stobrecoutfall. in front of the Split .categoryof sea water (02 % of saturation > 70%). city port, where the currents stagnation is the greatest. Thegretesi oxgenconentatin dereae ocur in Considerin the vertical distributionof nitrogen and BOD The gmattomsealaerese in oxgncn taiz mi compounds,the model reflects quite well the influecemof the ottmnd sen Om2raaroudlaers te oufaU thethermoclunate 'The conocentationincreases in the (4%Y),as 'wellas on the element (sea areas) irlLfluICidby bottm layersof the sea near the dischargepoints, whereas the Cetina and Zrnovnica Rivers. The greatest increase in. it becomes vertically uniform towards more distnt elements. In the surface layers the oxygen concentration performed using a simulation model for the following exceeds 100% satUration which results from the biological pollution loads at the main Stobrec outall: prmceseson the surface,whereas in the bottom sea layers 1. Pollutioncorresponding to 90/o treatment levelwith the concentration decreases as the consequence of the regard to BOOS (equivalentto flow of 0.2 m3/s of row bentthos oixygen demand. Such'oxygen 'distnbution is water). commonand the obtainedvalues do not significantlydiffr 2. Pollution corresponding to 50°/o treatment level from the cunenUtstate. -regarding BOD-5 (equivalentlo flow of 1.0 m3/s of row The obtained results show that the greatest positive water). ch;nges with regard to the present state will occur in the coastal parts of the sea, whose quality il be signifcantlv 3. Pollution twice Lrger than the load obtained by improved and retained within the limits of the required mechanmcalwaste water treatment (equivalentto flow,of standards.The greatest negatie changes (adverseeffects) 2.0 m3Jsof row water). occur in the channel aas, around the outfalls themselves 4. Pollution load three times greater than the load and in the central part of the Brac channel in front of the obtained by mechanical waste water treatment (equivalent Split city port; however the degree of changes is not to flowof 6.0 m3 s of row water). significant and these effects do not threaten the required The resultspoint to the changeswhich are relativel sea standard. significantbut still do not threatenthe required standardof According to the obtained results it can be concluded the sea, (Fig.4). that the plannedconcept of waste water disposal.even with A similar analysis was performedfor the changed mexhanical treatment only, will not cause long-term state under boundary conditions(exchange rate of the sea adverse effects upon the sea quality in the Brac-Split water in the channel), and panicuarlv for the southern Channel rgrding oxygenand BOD concentration.A entranceinto the Brac Channld(Fig.5). same time it will ensure the realization of the planned otbjective,i.e. the protection of the coastal sea and the All the obtained results prove the relatively high achievementof the required sea quality in accordancewith recipientcapacity relted to organic load of the Brac-Split its function. Consequently,It can be concluded the sa i rChannel and shwapthere is no danger of significat long- thc Brac-SplitChannel has a satisfactoryrecipient capacity tern changes if the waste water is treated onlv for the expectedquantities of organic pollution load. mechanically and discharged into the sea be long In order to confirm this statementand to deternine the submarineoutfalls. sensitiity of the aquatorium to organic pollution an analysis of the sea quality (oxygen concentration) was lB0 -- 1.60 ...... 1.40. s 1 S I]0...... 0.sot------ } 040 - - sta'dad 0.00 1.00 2.00 3.00 4.00 5.00 6.00 wastewaternow (m'/s) Figure4. Oxygendeficit in the critical elementsdependent upon load average channeldischarge of 3500 m3/s 1.60 1-40 . . _ . I0 0 100 150..... 2'0 20...... e0OSO . _...._ '...... OAOi .- /.------..-..--- -~--.~- - -- X ~~~~~1csection_ 130 .0 so too ISO 200 250 exchange period of the sea water in the channel(days) Figure 5. Oxygendeficit in the critical elementsdependient upon exchangeperiod of the sea water in the channel 5. CONCLUSIONS sea states (regarding organic load) and thus it justifies its application for defining long-term effects of waste According to the mentioned facts and the experience water discharge (organic load) to the sea of the Brac- obtained in the course of this project, the following Split ChanneL conclusionscan be reached: - The model is simple and easily applicable. More complex models would rquire more input data Which - The recpient capacity of the Brac-Split Channel. should be collected to sati* modeling which is not consderng organic polution is high, and the expected considered necessary at the present moment of the organic pollution loads, according to the concepual problemsolution (prelimnary phase). soluton for the sae system in the catchment ar - Consequenluy.continuous monitoring of the changes in will not endanger the sea qualityoxygen concentrtion) the sea state should be effected and data should be for the planned function. ^ - - -- collected to satisfy modeling, requirements by appl3ing - The planned concepts for the realization of the sewer either this model or other models; the modelingresults system (sewers. treant plant and submarine outfall) shouldbe used for detemining the monitoringprogram are satisfactory. and their construction wil lead to (location.parameters, periods). significant improvement in the quality of the coastal - The applied simulation model as well as the sea water in the Brac-Spht Channel, which makes it methodologyof the problem solution can be equally possible to use it for the proposedfunctions (recreation useful for defining long-termglobal states and changes and swimming). in the sea quality for other parts of the AdriaticSea and - The apphed regional simulation model has prved wider. useful and precise enough for defining long-termglobal REFERENCES: 1. Thomann. V.R. "S,ystemAnalysis and Water Quality Management".McGraw-Hill. New York 1972. 2. United StatesEnvironenwtal Protection Agency,. Documentationfor HAR03 Program".New York, 1974. 3. Margea J.. Baric A. i Gacic M., "Project:Selection of the optimal treatmert level for the central treatnent plant of the seweragesystem Split-Solin. Part , H and III". faculty of CihilEngineering Split. 1992. 4. Institute for Oceanographyand Fishery, "Oceanographicstudy of the Brac and Split Channels".Splt, 1993. 5. Deininger.R.. "Modelsfor EnvironmentalPollution Control'. Ann ArborScience PublishersInc., Michigan. 1974. 6. Red, A. 'Ocean WasteDisposal Practices". Noyes Data Corporation,Park Ridge. New Jersey, 1975. 1: WRc, "OutfallDesign Guide for EnvironmentalProtection". Marlow, 1986. S. Helliwel and 3.Bossanyi, "Pollution Criteria for Estuaries".Pentech Press. London, 1975. 9. Rodney V. S. and Clark. RJ., "Marine and Coastal Prtected Areas: A Guide for Planners and Managers". IUNC. Gland, Switzerland,1989. APPENDIX 3 ANNEX 1, fi, m TO THE PROTOCOL FOR THE PROTECTION OF THE MEDITERRANEAN SEA AGAINST POLLUTION FROM LAND-BASED SOURCES ANNEX I ANNEX il A A The followingsubstances, families and groups of substances zie listed, not in order of priority, for the purposes of article 5 of this Protocol. They have been selected mainly Tt e following substances, farnilies and groups ot substances, or sources ol ori ithebasys of heir: pollution. listed not in order of priority for the Purposes of articte 6 ot Ihis Prolocol. have biieeiselected mainlyon the basis ot criteria used tor annex , while taktinginto account the Toxicity; tact that they are generally less noxiousor are more readily rendered harrnlessby natural Derstsi,rnce: processes and therefore generally affect more limited coastal areas. dioaccurulation. 1. The following elements and their compounds: 1. Organohalogencompoundsandsubsfanceswhichmayformsuchcompounds I. zinc 6. selenium 11. tin 16. vanadium ir1the marineenvironment. 2. copper 7. arsenic 12. barium 17. cobalt * 2. Organophosphorus compounds and substances which may form such 3. nickel 8. antimony 13. beryllium 18. thalliumr compounds in the marine environment.' 4. chromium 9. molybdenum 14 boron 19. tellurium 20. silver 3. Organotin compounds and substances which may form such compounds in 5. lead t0. titanium 15. urahlum the marine environment.' 2. Biocides and their derivatives not covered in annex t. 4. Mercury and mercury compounds. 3. Crude oils and hydrocarbons of any origin. 5. Cadmium and cadmium compounds. 4. Cyanides and fluorides. 6. Used lubricating oils. 5. Non-biodegradable detergents and other surface-6ctive substances. .7. Persistent synthetic materials which may float, sink or remain in suspension 6. Inorganic compounds of phosphorus and elemental phosphorus. and which may intertere with any legitimate use of the sea. 7. Pathogenic micro-organisms. 8. Substanceshaving proven carcinbgenic,teratogenic or mutagenic properties in or through the marine environment. 8. Thermal discharges. 9. Radioactive substances,including their wastes, when their discharges do not 9 Substances which have a deleterious effect on the taste and/or smell ol comply with the princIples of radiation protection as defined by the competent international products for human consumption derived from the aquatic environment, and compounds organizations, taking Into account the protection of the marine environment. liable to give rise to such substances in the marine environment. 8 10. Substanceswhichhave, directlyorindirectly, anadverseeffectontheoxygen content of the marine environmerit. especially those whichimnay cause eutrophicatiorn. The present annex does not apply to discharges which cortuain substaniceslisted 11. Acidoraikalinecompoundsofsuchcompositionandinsuchquantitythatthey in section A thal are below the limits delined jointly by the Parties. may impair the quality of sea-water. 12. Substances which, though of a non-toxic nature, may become harmful to the marine envirotiment or may intertere wlth any legitimate use of the sea owing to the quantities In 1vhichthey are discharged. B With the exception of thosewhich are biologicallyharmless or which are rapidly The control and strict limitation of the discharge of substances referred to it convertedinto biologicallyharmless substances. section A above must be implemented in accordance with annex Ill. 49 48 ANNEXIII 4. Dispersioncharacteristics such as effectsof currents,tides and wind on horizonlalIransport and verticalmixing. Witha view to theissue of an authorizationfor the discharge of wastescontaining substancesreferred to in annex Ofor in sectionB of annexI to this Protocol.paricular S. Receivingwater characteristics with respect to physical,chemical, blological accountwill be taken,as thecase may be.of thefollowing factors: and ecologicalconditions in thedischarge area. A. CHARACTERISTICS ANDA. CHARACTERISTICSCOMPOSITION ANDOF THE WASTE ~~~~~~~~without6.undesirable Capacityesfects.of the receMngmarthe environment to reeilve waste discharges 1. Typeand size o0 waste source(e.g. Industrial process). D. AVAILABILITYOP WASTE TECHNOLOGIES 2. Type of waste (origin,avrage composition). The methodsor waste reduction and discharge for Industrialeffluents as welt as 3. Formof waste (solid.liquid. sludge, slurry). domestdicsewage should be selectedtaking into accountthe availabillty and feasibility of: 4. Totalamount (volume discharged, e.g. per year). (a) Altemativetreatment processes; 5. bischargepattem (continuous, tntermittent, seasonally variable. etc.). (b) Ae-useor eliminationmethods; 6. Conntrions withrespect to mar consitunts,sustances isted In annex1 (c) On-lenddisposal attematives; and substancesNisted In annex11 and othersubstances as approprdate. (d) Appropriatetow-waste technologies. 7. Physlal, chemicaland biochemicatpropertles ot thewaste. L POTENTIAL AMPARMENtOFMARINE ECOSYSTEMS AND SEAWATER USES B. CHARACTERISTICSOF WASTE CONSTITUENtS WITH RESPECT TO THEIRHARMFULNESS I. Efects on hunan heat #wugI ponuton1naet on: 1. Persistence(phystcal. chemical, biological) In th marineenvironment. (a) Edle martneorganisms; 2. Toxkiy andother harmful effects. I) BathIngwaters; 3. AccumurnlaonIn biological materils or sediments. (e) Aesthetis. 2. Effectson marineecosystems. In partIcularliving resources, endangered 4. Biochemicaltransformation produdng harmful compounds. speciesand crlticalhabitats. 5. AdverseeNfets on theoxygen content and balance. 3. Effectson otherlegitmate uses of thesea, 6. Susceptiblityto physical,chemical and blochemlcactchanges and Interaction In the aquaticevilronment vwth other sea-water consituents which may produce harmftu biologicalor othereffects on any of the usesNlsted In sectionE below. C. CHARACTERISTICSOFDISCHARGE SITE AND RECEIVINGMARINE ENVIRONMENT 1. H-Iydrographicmetaorological, geological and topographical characteristics of the coastalarea. 2. Locatonand type of thedischarge (outlfall, canal outlet. etc.) andIts relaton to other areas(such as amenityareas, spawning, nursery, and ishing areas,shellfish grounds)and other discharges. 3. Initialdilution achieved at the polntof dischargeInto the receivingmarine environment. 50 V~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I I~~~~~~~~~~~~~~~~~~~~~~~