r
r 1 DEMOCRATIC SOCIALIST REPUBLIC OF r SRI LANKA MINISTRY OF TRANSPORT AND fflGHWAYS MINISTRY OF FINANCE AND PLANING
COLOMBO-KATUNAYAKE EXPRESSWAY PROJECT '.r^ DESIGN BUILD & TURNKEY
CONTRACT NO. RDA/CKE/01
VOLUME V- ANNEX 16
Engineering Consultants Limited - May 1999 (Interim Report replaced by Final Report, refer Addendum No. 04)
BETWEEN ROAD DEVELOPMENT AUTHORITY OF SRI LANKA AND DAEWOO - KEANGNAM JOINT VENTURE L REPUBLIC OF SOUTH KOREA L I ROA:) r»EVE!.0PM3!NTAUTH0Rm'
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F)NAL REPORI
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No. JOSS. SriJcvctfür May 19^^^ •m'.-' '..••'t •.. iv-«*:" «fe -.^. •^ 1 ROA!> DKVE:.OFM?NTAUrHOR:rV I l: FINAL ïtEFORr L ,u\ }09S. Sri,'cvci^cire'i:r..ij7iii-aÄ4a-i-aihü. Ü'elikada. L F.ajasSriw. L. May l'») 1 . "•.:.'•.'•.••.• •'• L :: •.*•> p • L .:••;-•;•:•••' . 'i.'«11 ••- ';- .-•..:;•;:::•:•.-1.:, . -i- '•- i \ p-'afci.>; DETAILED IIYDROLOGICAL STUDY FOR PROPOSED COLOMBO - KATUNAYAKE EXPRESSWAY PROJECT FINAL REPORT CONTENTS Page EXECUTIVE SUMMARY Es-1 L Objectives of Study 1-J M Preamble M 1.2 Terms of Reference 1-2 1.3 Reports Submitted to date 1-3 1.4 Special Comments M 2. IdeDtification of Catcbmeots aad Sub-cafcfameats 2-] 2.1 Drainage Patterns 2-1 2.2 Major Catchments 2-1 2.2.1 AttanagaluOya J-1 2.2.2 Kalu Oya 2-2 2.3 Minor Catchments 2-2 2.3.1 MudunEIa ' 2-2 2.3.2 Micro Catchments 2-3 3. Rainfall Analysis 3-1 3.1 Available Run-ofTData 3-1 3.2 Available Rainfall Data 3-2 3.3 Rainfall Intensity Studies 3-2 3.4 Catchment Rainfall 3-3 3.5 Flood Experienced in Colombo City in June 1992 3-3 4. Catchment Parameters 4-1 r Page r 5. Development of Flood Hydrographs 5-1 5.1 Available Data 5-1 5.2 Alternatives for Development of Flood Hydrographs 5-1 5.2.1 Model I -SCS Model 5-1 5.2.2 Model 2-HECl Model 5-1 5.3 Model Selected for the Study ' 5-2 5.4 Flood Hydrographs Developed for Pre-project Conditions 5-2 5.4.1 Model Parameters Used 5-2 5.4.2 Flood Routing - Dandugam Oya, Ja Ela and Kaiu Oya 5-3 5.4.3 Flood Routing - Minor Catchments 5-4 6. Hydraulic Conditions Downstream of A3 and CKE 6-1 6-1 General 6-1 6.2 Mudun Ela Catchment 6-1 6.3 Kalu Oya Catchment 6-1 6.4 Micro Catchments 6-1 6.5 Ja Ela Catchment 6-2' 6.6 Dandui^am Oya Catchment 6-2 6.7 Section of CKE Traversing along and through a part of the Lagoon 6-2 7. Hydraulic Design of Drainage Crossings under Proposed CKE 7-1 7.1 Methodology 7-1 7.2 Estimation of Flood Levels 7-1 7.2.1 Description of the Model 7-2 7.2.2 Results obtained from the Model 7-3 L 7.2.3 Estimation of Flood Levels along CKE Trace 7-3 7.3 Design of Major Drainage Crossings & other Watenvay Openings 7A L 7.4 Impact of CKE on Flood Levels upstream of A3 7-4 7.4.1 General 7-4 7.4:2 Mudun Ela Catchment 7-5 7.4.3 Kalu Oya Catchment 7-5 7.4.4 Micro Catchments between Mabole and Ja Ela 7-5 L- 74.5 Ja Ela Catchment 7-5 7.4.6 Dandugam Oya Catchment 7-5 L L 11 L •rj;..."^^^.'"-" "•' •-'«F^ . 1-1.' ' Jrf »W^» Page 7.5 Validation of Road Embankment Levels 7-5 75,1 General 7-5 7.5.2 Mudun Ela Catchment 7-6 7.5.3 KaluOya Catchment 7-6 7.5.4 Micro Catchments from Maboie to Ja Ela 7-6 7.5.5 Ja Ela Catchment 7-7 7.5.6 Dandugam Ova Calchmenl 7-7 7.5.7 Area Draining into Negombo Lagoon 7-8 7.6 Inventory of Drainage Crossings across A3 7-8 8. Improvements to DowDstream Drainage System to Mitigate the Impact of High Floods 8-1 8.1 The Concept 8-1 8.2 Mudun Ela Catchment 8-1 8.3 Kalu Oya Catchment 8-1 8-4 Micro Catchments from Maboie to Ja Eia 8-1 8.5 Ja Ela Catchment 8-2 8.6 Dandugam Oya Catchment 8-2 9. Floods Mapped Out 9-1 9.1 Dandugam Oya Catchment 9-1 9.2 Ja Ela Catchment , 9-1 9.3 Kalu Oya Calchmeni 9-2 9.4 Mudun Ela Catchment 9-2 9^ Field Surveys Done 9-3 10. Mapping of Flood Inundation Areas Corresponding to High Return Periods lO-I 10.1 Methodology 10-1 10.2 Estimation of Flood Levels for Different Return Periods lO-I 10.3 Duration of Flooding . 10-2 Hi r Page 11. Additional Flood Deteation Areas to Mitigate the r Impact of High Floods 11-1 1 1 11.1 The Concept ll-l * 11.2 Mudun Ela Catchmenl ll-l 11,3 Kalu Oya Catchmenl 11-1 11.4 Micro Catchmenis 11-2 11.5 Ja Ela Catchmenl 11-2 [ ' 11.6 Dandugam Oya Catchment 11-2 12. Monitoring System Recommended during Construction 12-1 13. Identifying Areas on Verges of Negorabo Lagoon for Expanding its area 13-1 13 1 The Problem 13-1 13.2 Selection of Areas for Investigations I3-I 13.3 Augur Hole Survey Carried Out 13-1 13.4 Report on Soil Survey 13-1 13.5 Identification of Areas 13,2 13.6 Recommendations 13-2 14. Baseline Survey of Ground Watei Levels and Water Quality' in Project Area 14-1 14.1 Objective 14-1 14.2 Selection of Wells 14-1 14.3 Ground Water Survey Done 14-1 14.4 Location of Wells 14-1 14.5 Water Level Observations 14-1 14,6 Chemical & Physical Parameters 14-1 14,7 Microbiological Tests 14-1 L 14.8 Comments on Water Quality of Samples Tested based on Standards for Potable Water 14-2 L 14,8.1 Colour 14-2 14.8.2 Turbidity 14-2 14,8.3 PH 14-2 14,8.4 Eleclrical Conductivity 14-2 14,8.5 Chloride 14-2 14.8.6 Total Alkalinity 14-2 L 14,8.7 Nitrate 14-2 14,8.8 Nitrite 14-3 L L iv L •--;;ÏX' i4.8.9TotaI Phosphates 14-3 14.8.1 OTolal Hardness 14-3 MS.IlTotallron 14-3 14.8.12Free Ammonia 14-3 14.8,13AIbuminoid Ammonia 14-3 14.8. MBacteriological Examination Reports 14-3 IS. Concluding Remarks IS-1 r LIST OF TABLES r. Tabic 3.1 List of Raiafall Stations Table 3.2 Rainfall Intensities Table 4.1 Catclimcot Parameters Tabic 5.1 Ordinales of Outflow Flood Hydrographs Table 7.1 Ncgombo Lagoon Flood Routing Table 7.2 Drainage Crossing and other Waterway Openings Table 7.3 Impact of 100 year Return Period Floods Table 7.4 Inxentory of Drainage Crossings Across A3 Table I O.I Flood Levels for Different Return Periods Table 12.1 Tentative Sampling Program for Lagoon Turbidity Table 14.1 Baseline Survey of Ground Water-Ground water Surface Elevations Table 14.2 Results of Ground Water Ana I) sis-Sam pled in November 1998 Table 14.3 Results of Ground Water Analysis-Sampled in February 1999 vi .'«.^ LIST OF FIGURES Figurcl.1 - CKE Trace (in the docket) Figure 2.1 - Schematic Sketch showing Ilydrologicaf and Hydraulic characlerisfics Affecfing Proposed CK£ during storm conditions Figure 3.1 - Location of Rainfall Stations Figure 3.2 - Depth - Duration Cune for Vincit Estate Flgffre 3.3 - Depth - Duration Cune for Katunayaka . Figure 3.4 - Depth - Duration Cur^'e for Colombo Figures.! - Schematic diagram for development of Inflow Ilydrographs by SCS Model Method Figure 5,2 - Schematic diagram for development of Inflow Hydrographs by HECl Model Method Figure 5.3 - Flood Hydographs -50 year return period- Dandugam Ova Catchment Figure 5.4 - Flood Hydographs -100 year return period- Dandugam Oya Catchment I' Figure 5.5 - Flood Hydographs -200 year return period- Dandugam Oya C Catchment Figure 5.6 - Flood Hydographs -50 year return period- Ja-EIa Catchment Figure 5.7 - Flood Hydographs -100 year return period- Ja-EIa Catchment Figure 5.8 - Flood Hydographs -200 year return period- Ja-EIa Catchment Figure 5.9 - Flood Hydographs -50 year return period- Kalu Oya Catchment Figure 3:10 - Flood Hydographs -100 year return period- Kalu Oya Catchment Figure 5.U - Flood Hydographs-200 year return period-Kalu Oya Catchment Figure 6.1 - Schematic of Simplified Drainage System. vn ^_..-.^' •->i,':'^ -V . ! I Figure 7.1 - Schematic of Negombo Lagoon Hydraulic Characteristics-under r Storm Conditions Figure 7.2 - Methodology For Estimation Of Flood Levels at Ja Ela r Dandugam Oya Road Crossings Figure 7.3 - Schematic High Flood Water Surface Profile Dandugam Oya Figure 7.4 - Schematic High Flood Water Surface Profile Ja-EIa Figure 7.5 - Schematic High Flood Water Surface Profile Kalu Oya Figure 12.1 - Location of Monitoring Points Figure 14.1 - Location of Areas Selected for Auger Hole Survey Figure 14,2 - Location of Auger holes I L L- L- L L viii • 'J -i s^ LIST OF ANNEXES Annex 1 - Monthly Rainfall Data - 7 no Rainfall Stations Annex 2 - Bacteriological Examination Reports L be :-•- •w.-yrjiBM'ï ...... -, ^ -l^p EXECUTIVE SrM.\ÏAR\ DESCRIPTION OF CKE TR\CE AND CATCHMENTS INTERCEPTED The proposed trace commencing from the left bank of Kelani Ganea, crosses Kelani Ganga and runs in a northerly direction intercepting the catchments of Mudun Ela, Kalu Oya, Lfruwal Oya (Ja-EIa), Dadugam Oya and the micro catchments intervening these basins. Of (he above, Mudun Ela and Kalu Oya are right bank tributaries of Kelani Ganga, while Dandugam Oya and Ja-Ela drain into the Negombo Lagoon. The .micro catchments drain directly into Muthurajavvela marsh. The proposed trace at its furthest point is about 3.5km from the sea and is essentially located within the flood plains extending from Kelani Ganga to the Negombo Lagoon. The catchment areas of these drainage basins are as follows: Catchment Area in sq. km Basin At A3 At CKE Dandugam Oya 587 589 Ja-Ela 183 183 Kalu Oya 54 52.5 Mudun Ela 8.2 5.9 Micro Catchments (6 No,) - 13.5 Figure LI (in th<* docket) shows the trace of the CKE, the existing A3 Hrghway and the catchments inter."^ opted. Rainfall Analyses Due to the absence of reliable flow data within these basins, flood hydrographs have to be developed applying Mathematical Models using available rainfall data and other catchment parameters. The daily rainfall records were collected from different sources for ten rainfall stations in and around the project area, (Please 'sees Fig, 3,1) V The project area is located in the Hydrological Region UL which covers the North Western part of Sri Lanka. Available rainfall intensity studies are based on Katunayake and Colombo rain gauges and therefore more site-specific analysis was carried out for this study. Daily rainfall i: data at Vincit Estate and Katunayake rain gauges for the most recent 30 years were collected to carry out a fresh intensity analysis and these Depth Duration Curves [DDCj are shown in Figures 3.2 and 3.3. These two DDCc were used in addition to the DDC for Colombo, which is shown in Figure 3.4. Table 3.2 shows the results of this rainfall intensity analysis. For Katunayake and Vincit, analysis was done for a duration of 5 days. For the frequency analysis. Extreme Probability- Type [ distribution [Gumbel] was adopted. ES - 1 L t*ai: ^.-' *.-^. - •''• r For Dnndugam Oya basin, rainfall iniensiiy analysis of both Vincit and Kaiunayake were used. For Jn-EIa only Katunayake rainfall was used as the catchment is mostly coastal. ForKaluOya, rainfall intensity for Colombo was used. For all these stations, rainfall corresponding to 50, 100 and 200 year return periods were used as design storms. 05-day durations for the design storms were considered for both Dandugam Oya and Ja Ela and 04 day storni was considered for Kalu Oya as the catchment is smaller. By extracting the intensities from the DDCc of three rain gauges, 50, WO and 200 year storms uere developed for 03 hour time resolutions. For the design of storms the standard procedure in storm designs by the application of unit hydrographs technique was adopted. Mathematical models use rainfall information and the catchment characteristics to develop a Flood Hydrograph. There are many mathematical models for river flow simulation but some of these models require very extensive field data, collection of which is time consuming. Considering the time frame of this study, only limited field data could be collected and therefore the consultants decided to use two different models to assure the designer that the results obtained by applying both models are varying within acceptable limits. Model I - SCS Model This model was used in the Interim Report and was developed by the USDA Soil Conservation Services [SCS] in 1955. It is applicable from small to medium sized watersheds. Figure 5.1 is a Schematic Diagram for Development of Inflow Hydrographs by the SCS Model Method- Model 2 - EEC I ^^odel This model consists of two modules namely: the rainfall-tunoff relationship and reservoir routing. Developed by the US Army Corps of engineers this model is also adopted widely in the United States and other countries. Figure 5.2 is a Schematic Diagram for the development of Inflow Hydrographs by the HEC 1 Model Method. Flood Routing of Major Catchments Routed flood hydrographs were developed for Dandugam Oya, Ja Ela and Kalu Oya catchments for Return Periods of 50, 100 and 200 years, using the Storm Rainfalls Computed from Depth- Duration-Frequency Curves and the Catchment Parameters. Figures 5.3 to 5.11 consisting of 09 No, printouts show these flood hydrographs. Each printout indicates the Inflow Hydrograph and the Outflow Hydrograph. Minor Catchments In the case of minor catchments an empirical formula was used to estimate flood peaks. ES - 2 •f- • . V"iT' r ir IIVDR-AULIC CONDITIONS DOWTS'STREAM OF A3 AND CKE The schematic in Fig.2.1 indicates the complex nature of ihe drainage network 'm the area traversed by the proposed CKE. Detail inspections and studies revealed that, for the pu^wse of this study the drainage partem under storm conditions could be schematically represented as in Fjg. 6,1, Mudun Ela Catcbmcnt CKE traverses mainJy through marsh lands within this basin and the drainage system comprises of a network of interconnected channels covered with weeds The flood levels in the areas are dependent on the flood stage in Kelani River. The high flood elevation con-esponding to the 1947 flood is 2,5 m-MSL. * • Kalu Oya Catchment CKE intercepts the main Kalu Oya drainage line at three locations and also crosses 2 other tributaries. The terrain is mainly marshy land, the elevation of which is close to mean sea level. The flood elevation is dependent on the flood stage in Kelani Ganga and the observed HFL is about 2.5m - MSL. Micro Catchments Micro catchments between the catchments ofKalu Oya and Ja-EIa drain into Muthurajawela marsh. Under storm conditions, the backwaters of Negombo lagoon submerge the Muthurajawela marsh. Ja-£la Catchment Ja Ela flows into Negombo Lagoon. Because of the canal embankments Ja-Ela does not give rise to overland flows in the marsh traversed by it. Water elevations in the canal are directly dependent on the water surface elevations of Negombo lagoon. L Dandugam Oya Catchment The drainage waters flow into Negombo Lagoon through Dandugam Oya, an e.xtrabutary and L through charmels taking off Mahadora Ela, Under flood conditions part of Dadugam Oya discharge drains into the lagoon as over land flow. Water elevations in Dandugam Oya are n directly dependent on the water surface elevations of the lagoon. Section of CKE traversing along and through a part of the lagoon Wliere tlie CKE trace runs along the lagoon only minor drainages are intercepted and drainage crossings need be provided to cater tp these discharges. l ES ~ 3 iL • <—'i r The part of CKE passing through the lagoon will isolate hydrauücally two areas of the lagoon. Adequate openings on the roadway are required to provide for interchange of water between these r areas and the main lagoon. HYDRAULIC DESIGN OF DRAINAGE CROSSINGS UNDER PROPOSED CKE Methodology adopted in the hydmuWedesign of^kginage crossings is set out below: [a] Estimation of pre-project\100 year and 200 year Sod levels at the proposed drainage -crossing site [b] Estimation of available waterway area [c] Estimation of flow velocity through the structure with the 100-year peak discharge , [dj Estimation of velocity of approach based on available sectional area of flow, hydraulic gradient and Mannings "n" [e] Calculation of flood afflux (h) at the structure. Estimation of Flood Levels The high flood levels pertaining to Mudun Ela and Kalu Oya were estimated on the basis of historical flood elevations in and around the intersections with CKE, Flood elevations in and around Dandugam Oya, Ja-EIa and Muthurajawela marsh are defiendent on Negombo lagoon. In order to estimate lagoon water surface elevations under flood conditions a mathematical model was developed with data obtained from site investigations. Results Obtained from the Model The maximum water surface elevations at the southern end of the lagoon caused by the 100-year and 200 year flood inflows are estimated at 0.776 m and!.002 m respectively. Estimation of Flood Levels along CKE Trace Methodology for the estimation of flood levels in Dandugam Oya, Ja-ela and the Muthurajawela marsh is presented in Figure 7.2. ES ~ 4 V .-X-"•--. ' --m Design of Major Drainage Crossings & Other W'atenvuv Openings /The watenvay areas required to limit the hundred year return period flood afHiix to a maximum of 10 (cm were computed using the peak value of flood hydrographs, channel sections, estimated velocities lof natural channels In the case of Ja Ela it is proposed to provide a bridge spanning the existing walerv\ay and roads on either bank. Hence there is no change in pre project conditions. In the case of Dandugam 0>a the bridge will span the Oya and the roads on either bank, but the overiand flood flows which occurred in pre project conditions had to be routed through 2 No./l 5 m span bridges and a 10 m span bridge over e.xisting drainage channels. The location, spari, required waterways, HFL and other details are given in Table 7.2, Impact of CKE on Flood Levels Upstream of AJ CKE will have no impact on the flood levels upstream of A3 excepting Mudun Ela where due to inadequate waterway area in the existing culverts along A3 a rise of 14 cm is anticipated in the 100 •year flood level. Validation of Road Embaakment Levels Embankment levels are to be determined on the basis of the following: Hvdraulic Considerations: L [ 1 ] 1.1 m ab [3] 0,5 m abovfthe 200 year flood level Clearance and Alignment Considerations ^L [4] 100 year flood level + clearance for boats or traffic + deck thickness [in the case of bridges] [5] Elevation to suit vertical alignment Criteria (2) and (3) v\-ere found to be satisfied if criterion (1) is complied with. Inventor}- of Drainage Crossings across A3 This is presented in Table 7.4, ES - 5 [ "U."- •'••«ï't-^--T.- n"-• wu T"'..«•-•"•;riigii»tk',Tis-jjr-",- I.MPROV t.MENTS TO DOWNSTREAM DRAINAGE S^ STEM TO MITIGATE THE IMPACT OF UIGU FLOODS The proposed roadway is mainly conHned lo the tlood plains orihe river basins intercepted by it and the flood levels are directly dependent on the tlood stages in Kelani Ganga or Negombo Lagoon. As such dovv-nstream fiood elevations cannot be appreciably reduced using cost effective means. However in the case of Mudun Ela the flood discharge has to cross existing A3 mainly through two openings, one at I + 100 and the other at 2 + 150 (culvert no. 3/1). The effective waterway areas at these culverts are grossly inadequate and if the waterway area at culvert no. 3/1 is increased flood levels and floodingtime s can be reduced appreciably. FLOODS i\L\PPED OUT AND FLOOD EVUNDATION AREAS • This exercise involved much interaction between Consultant, Licensed Surveyor and the infomiants. The Consultants also had to ensure that the ma.ximum flood levels indicated by any informant were cross-checked by further independent inquiries. They had also to ensure that the flood was caused by the natural build up of storm conditions and not by any disaster e.g the May 1991 fl(?od in the Dandugam 0>a is always associated with an anicut^dam failure upstream in the Attanagalu Oya Irrigation Scheme. Hence, the flood level was the result of a sudden flood wave travelling downstream and not caused by a natural build up of slorm conditions. The following procedure was followed in mapping out at least one historical flood for each major catchment intercepted by the CKE: • Field inquiries were made to ascertain the approximate date of a historical flooü • The maximum flood level observed at A3 on the upstream was noted. This flood level was converted to MSL by field levelling using the 25 No. Bench Marks set up along the CfCE trace • This flood contour was then traced on the ground so as to establish the inundated area upto a distance of about 02 km east of A3 [as an environmental requirement] • Suitable cross sections were taken so thai floods of other return periods [higher or lower] can be plotted too • From the results of the Rainfall Analyses, the return period of the floods mapped out for each major catchment was estimated » For Return Periods of 50, 100 and 200 yean, the rainstorms for each catchment WBS extracted from the results of the Rainfall Analyses and the corresponding Flood Peak Levels were estimated using hydraulic principles • The contours corresponding to the Flood Peak Levels for the 50, 100, and 200 year storms for each major catchment was plotted using the cross sections taken along the historical flood contour Maps on Scale 1:10.000 were prepared showing the flood contour of the historical flood as well as the flood contour of floods with Return Periods of 50. 100 and 200 year slonns. I.- ES - 6 .i Basically the study revealed tdai the construction of the CKE does not increase Ihe flood levels upstream of A3, significantly, Chapters 9 and 10 provide all the details. ADDITIONAL FLOOD DETENTION AREAS TO .MITICATE THE EMPACT OF FLOODS Detailed studies have shouii ihat the waterway openings proposed in Section 7,3 will limit the rise in the post-project 100 year flood levels immediately upstream of CKE, to 05 cms excepting Mudun Eia catchment where the estimated nse is 15 cm. Even here the rise in flood levels could be limited to 05 cms with increase in the waterway at culvert No. 3/1 on A3, Therefore additional deteniion areas or other methods of lowering flood levels would not be required, r MONTTORTSG SYSTEM RECO.VLVIENDED DURING CONSTRUCTION. The risk of sedimentation of Ihe lagoon is best to be left to the constriiction stage with prior warning to the Tenderers to device suitable measures to counteract ihe problem. We propose that the Madabokka area which is vulnerable in the context of prawn spawning, be sampled on two locations on eithersides of the road trace at a distance of 60.0 m from the centre line. The area close to the sea be sampled at 02 locations 60.0 m away from the centre line of the road trace. The time interval for sampling shall be as shown in Table 12. L n)ENTIF\TsG AREAS ON VERGES OF NEGOMBO LAGOON FOR EXPANDEVC ITS AREA i2Si iTi of the proposed expressivav will traverse through the lagoon .The area lost due to the construction of the roadway embankment is 45,000 m-^2 ( 0.13% of the 'area of the lagoon). Compensation area is to be created by the excavation of suitable areas selected on the verges of the lagoon. From preliminary studies and reconnaissance field visits areas were selected for flinher investigations Augur Hole Survey A soil survey of the selected areas was carried out by means of50 augur holes drilled to a depth L of 2 m. Identification of Areas Two areas AI and A2 have been identified as suitable areas for expanding the lagoon area. Area Al covers an extent of about 10 ha and Area A2 covers an extent of 9 ha. The extent required to compensate for the area lost due to the roadway is only 5 ha. If it is decided to proceed with the expansion of the lagoon area, an environmental impact assessment [EIA] need be carried out as the entire area covered by Ihe survey forms part of mangroves surrounding the southern part of the lagoon, i ES ' 7 L r BASEIJVE SI RVE\ OF GROl \D WATER LEVELS AND WATER QLALITV PROJECT AREA 48 dug uells and two water holes were selected so as to provide representative samples from the area traversed by the CKE. Ground WaterSuncv Ground water levels were monitored in 50 wells for a period of five months with 2 observations per month. Chemical analysis was performed on 50 samples and microbiological tests were carried out on 25 samples. Water Level Obser>'ations Water level observations are presented on Table 14.1 Chemical & Physical Parameters Results of analysis are presented in Tables 14 2 and 14.3 Microbiological Tests Results of microbiological tests are presented in Amiex 2. The results indicate that the sources of the water samples are highly polluted. ES - & ^••^ 1..V .. DETAILED H YDROLOGICAL STUDY OF PROPOSED COLOMBO - KATUNAYAKE r EXPRESSWAY PROJECT r I. OBJECTIVES OF STUDY 1.1 Preamble The need for a road link between Ihe International Airport at Kalunayake and Colombo was identified by the Road Development Authority [RDA] more than 02 decades ago. Despite being considered a priority project at national and local levels, it is yet to be implemented as a result of being beset by numerous financial administrative and social constraints. The Colombo Katunayake Expressway [CKE], when completed, will be the first expressway and one of the largest investment projects in the highway sector in Sri Lanka. The CKE, nearly 25 km in length is lo be constructed, connecting the International Airport to the city of Colombo. It wll be a fully access-controlled four-lane design, expandable to a six-lane divided toll roadway; between the intersection of the new Kelani Bridge and KandyRoad [Al] in Colombo and the Canada Friendship Road and Putlalam Road [A3] in Katunayake. The CKE will be constructed to international standards with a design speed of 100 km/h and four diamond-type grade separated intersections [or interchanges] located at Peliyagoda, Kerawalapitiya [where there is a 400 acre area reclaimed from the Muthurajawela marsh by sandfill]. Ja Ela and the final at Katunayake ' [linking the Sri Lanka Canada Friendship Road]. The expressway commencing at the new Kelani Bridge will proceed northward past the Hunupitiya Railway Station, and then swing leftwards to cross the present A3 road at a point close to Mabole in Wattala. It will then follow a northward trace along the corridor of the old Dutch Canal upto the southern end of the Negombo lagoon. The roadway will then enter the lagoon and proceed for about 1.5 km, at an approximate distance of 30 meters from the eastern shoreline of the lagoon, upto the point where the westward extension of the Canada Friendship Road meets the lagoon. Figure I. l(in the docket) shows the trace of the proposed CKE, It must also be stated that this present trace was selected and is referred to as the western trace after an eastern trace was earlier identified between new Kelani Bridge arid Katunayake Airport. The eastern trace had to be subsequently abandoned due to many L adverse sociological problems which cropped up. But in the case of the presently selected western CKE trace, there will not be much displacement on the CKE as around 75% of the proposed highway will be moving over marshy land or lagoon, where there are no permanent settlements. A major hurdle that has been cleared in relation to the implementation of CKE proposal is that the Central Environmental Authority [CEA] has granted approval to this proposed venture subject to many conditions and guidelines. One of the major concerns is the I-Ï r Hydrology and Drainage aspects along the CKE trace and Hydrology and Hydraulics of the Negombo Lagoon. These concerns were highlighted by the Technical Evaluation Committee [TEC] which evaluated the Environmental Impact Assessment Report [EIAR] submitted by the RDA in respect of the proposed CKE. Engineering Consultants Limited are therefore pleased to submit this Final Report on a "DETAILED HYDROLOGICAL STUDY OF PROPOSED COLOMBO-KATUNAYAKE EXPRESSWAY PROJECT", and the results of the study will not only satisfy a major concern expressed by the CEA, but will also provide relevant information to the Design Engineer to finalize the following design parameters: Location of proposed under crossings like culverts and bridges along CKE trace * Area of Flow needed at each such under crossing « Approximate Level of Flooding for different return periods Minimum Finished Road Level of proposed highway at all critical points like under crossings and bridges 1.2 Terms of Reference (TOR] The TOR was made available to the Consultants by RDA letter dated 30* June 1998. Preparation and submission of proposals, evaluation of proposals and subsequent negotiations ended in August !998. The study commenced on 0?"' October 1998. The comprehensive TOR was essentially aimed at bringing out the hydrological and hydraulic characteristics of the systems influencing the design of the proposed CKE. This included: • Studying the hydrological and climatic conditions of the area. • Selecting suitable rainfall stations within the respective river basins [catchments] influencing the proposed CKE and carrying out rainfall analyses and produce Rainfall Intensity - Duration Curves, for return periods of 10, 25, 100 and 200 years. • Estimating flood discharges at major drainage crossings for 50, 100 and 200 year return period. • Examination of lead away conditions of major drainage crossings to ensure the mitigation of water levels during a flood to safer downstream locations, • Hydraulic design of bridges and culverts at strategic locations along CKE indicating the opening sizes to keep the pre-determined pre-project 100 year flood levels as much closer closer to the post project high flood levels. 1-2 '•" •.•.x.^^i'^" . •• • -1 ^-.^ • Validation of the posl-project 100 year design flood levels with the new road r embankment, 1.1m above the design high flood level [HFL] on the proposed CKE by considering the additional cross drainage due to interference of the embankment with the natural drainage system. I • Inventory of all Drainage Crossings across the existing Colombo-Katunayake [A3] with salient parameters to facilitate the design of drainage structures for the proposed CKE andjustification of same. • Propose any Improvements to Downstream Drainage System to Overcome Any Physical Constraints. • Carrying out field investigations and necessary surveys, so as to establish details of maximum observed historical floods in the area including water spread areas. An attempt to be made lo establish the return period of these floods by studying the rain storm causing those floods. • Predicting probable areas inundated and duration of flooding, caused by these storms of 50, 100 and 200 year return period, • Inundated areas corresponding to 50, 100 and 200 year stomis to be mapped out. I • Propose any retention area which is necessary to mitigate the impact of post-project , ' 100 year flood, in case these levels are significantly higher than the pre-project high flood levels. • Prepare a suitable monitoring system during the construction of the profwsed road to ensure the control of excessive turbidity and sediment loads to Negombo Lagoon during construction. I • Identify suitable land areas along the lagoon verges for expanding the water area of the lagoon to compensate [or if possible over compensate] for the loss of water area due to the construction of the Expressway. I • Cany out a baselinesurvey of the ground water levels and water quality in the project area. L 1.3 Reports Submitted To Date In keeping with the TOR and as confirmed in the Technical Proposal submitted, the following reports have been submitted prior lo the submission of this Final Report: * An Inception Report within 3 weeks of commencement of study L * Monthly Progress Report No. 1 covering the period 07.10 98 to 06.11.98 * Monthly Progress Report No. 2 covering the period 07,11,98 to 06.12.98 L- * Monthly Progress Report No. 3 covering the period 07,12.98 to 06.01.99 L [ U3 L È!^ . . • .• ..jVi' -->' *!.-3*'..'^»---•'•••"•• Monthly Progress Report No. 4 covering the period 07,01.99 to 06.02.99 * Monthly Progress Repon No. 5 covering the period 07.02,98 to 06,03.99 « Interim Report after completion of 03 months of the study, which incorporated results obtained in respect of Rainfall Data collected and development of Rainfall - Intensity - Duration Curves Estimation of flood discharges for return periods of 50, 100 and 200 years Inventory of Drainage Crossings on existing A3 Hydraulic Design of Bridges and Culverts at strategic locations indicating opening sizes for proposed CK.E Validation of the post-project 100 year design flood levels with the new road embankment, allowing a minimum free board of 1.1 m. Draft Final Report after completion of 6 months of the study. 1.4 Special Comments 1.4.1 Additional Surveys In order to assist in the hydrological and hydraulic studies the following additional surveys, not envisaged at the proposal stage, were carried out: Depth measurement along sea outfall canals and Negombo Lagoon Cross sections of sea outfall canals at the bridges « Water surface profiles of Dandugam Oya, Ja Ela and Kalu Oya dowTistream of A3 * Cross sections of Dandugam Oya, Kalu Oya and Mahadora Ela 1.4.2 Booklet with Bench Mark Details Based on the setting up of T.B.M.M., approximately I km apart, along the CKJE trace, a booklet giving the following details was submitted. * A serial number for each BM commencing from the southern end; which included already existing BMM too * The elevation in MSL « A descriptive location of the 32 No. BMM * Some relevant remarks where possible Location of the 32 No, BMM sho\vn on a 1:50,000 scale map * Location sketches for each BM so that each BM can be identified/located by any technically qualified officer 1.4.3 Meanders of the Right Bank Tributary of the Kalu Oya Basin The proposed CKE trace cuts through the meanders in the RB tributary 3 times thereby necessitating 3 No. bridges over the same river. By acquiring an additional strip of private property it is possible to straighten out 2 of the L 1-4 meanders by cutting a wide trench, the dimensions of which meet the geometry of the tributary and eliminate the need for 2 out of the 3 No. bridges. This may be a cost effective alternative which deserves further study. 1.4.4 Road Intersections 04 No, road intersections have been identified along the CKE trace In order to assess the hydraulic requirements of these intersections, it is necessary to have a flat plan showing each intersection in full. The computations done and some parameters detemiined during the hydrological study for the CKE trace can then be effectively used. 1.4.5 Perimeter Survey of Flooded Areas Flood levels were ascertained by means of local enquiries and the fiood contours shown are for the average value obtained from a number of "observed flood levels" as shown by local residents. The high flood levels shown correspond to a flood peak in that particular catchment and may not be related to the storms causing the flood peaks in adjoining catchments. Also it is to be noted that high flood levels in Kalu Oya and Mudun Ela are dependent on water levels in Kelani Ganga and therefore the observed high flood levels may not correspond to flood peaks in these catchments. In other words the high flood levels in these basins are the result of a combination of high stages of Kelani along with catchment inflows. The probability of a 100 year flood peak coinciding with a 100 year flood stage in lower Kelani are extremely low. L L L L L [ 1-5 I 2. IDENTIFICATION OF CATCHMENTS AND SUB-CATCIIMENTS 2.1 Drainage Patlcra The proposed CKE trace can be said to traverse approximately in a northerly trace from Colombo lo Katunayake and running parallel to the western coast and at a distance of about 3-4 km from it. This trace intercepts a number of cross drainages consisting of minor steams, major streams and rivers during its course. All these cross drainages flow from East to West ultimately draining into the sea along the western coast. The existing A3 highway between Colombo and Katunayake, similarly travels in a northerly direction and also intercepts most of the cross drainages intercepted by the CKE. Hence an identification of all the catchments and sub-catchments and their main drainage courses, which cross the proposed CKE and discharge into the sea, is absolutely essential. Moreover a study of the hydraulics of the drainage system upstream ofCKEas well as downstream is also necessary to enable quantifying peak flows for difTerent return periods that could occur at each identified drainage crossing under the proposed CKE. 2.2 Major Catchments 2.2.1 Attanagalu Oya Attanagalu Oya is located between Kejani Ganga and Maha Oya river basins and has a catchment area of 761 sqkms The upper catchment is approximately 250 sq.kms., consisting of rubber and coconut estates and the highest elevation is 300 m MSL. at Galapitamada. The lower catchment is predominantly ciiliivated u-ith paddy and there are 3870 ha. of paddy irrigated, under Attanagalu Oya Irrigation Scheme (AOS), the largest irrigation project in the basin. The river flows westward and meets Diya Ella Oya near the Gampaha town. At its lower reaches it joins with Uruwala Oya and at this point the river name changes to Dandugan Oya. The AOS itself consists of 10 major diversion schemes for irrigation with 34 minor diversion weirs in the lower reaches. There are also numerous other rainfed, minor and medium irrigation projects within the basin. The Ananagalu Oya rises in low hills situated at the eastern boundary of the basin and flows from East to West up to Kotugoda, where it turns towards the North and gradually flows to the South, till it reaches the Seeduwa bridge, across Colombo-Negombo road. From the bridge it again flows westwards to the Negombo lagoon. Above Kotugoda, a man made canal called the Ja Ela, directly drains a part of the catchment flow. Hence the runofTfrom the Attanagalu Oya basin is shared between, the flow through Ja Ela and that through Dandugan Oya. The Ja Ela crosses the Colombo-Negombo road at Ja Ela and also flows in a westeriy direction (south of the Dandugan Oya), into the Negombo Lagoon, The longest length of the river course is about 57 km at the A3 crossing. 2-1 ^.V- 1-^ »^.i-'"" For the purpose of Ihe study, it is very necessar}- to apponion definite sectors of the catchment for Dandugan Oya which cross the A3 at Seeduwa and Ja-EIa which crosses at Ja- Ela. Accordingly detail studies of Ihe available topographical maps of the river basin and detail field inspections were carried out with a view to establishing these 2 catchments. Accordingly the following break up has been determined, DandugainOya At A3 At CK£ (also called Attanagalu Oya) 587 sq.km 589 sq.km JaEla 183 sq.km 183 sq.km These 2 sub catchments have been shown in the catchment map in the docket (Fig, M). 2.2.2 Kalu Oya This catchment of 52.5 Sq.kni is one of the lowest sub catchments of the large Kelani Ganga basin and is intercepted by the CKE upstream of the existing A3. This catchment, due to its proximity to Colombo city, is characterised by its large urban population, and its lower reaches consists of marsh which too has been partly reclaimed. The flooding pattern of this catchment is greatly influenced by river levels prevailihg in the Kelani Ganga caused by storm conditions occurring in the large 2292 sq km. Kelani ganga basin with its source in the Adams peak range at elevations exceeding 2000 m MSL, experiencing rainfalls which can be considered to be among the highest in the island. 2.3 Minor Catchments 2.3.1 Mudun £la This is another minor basin of 8.2 sq.km at A3 and 5.9 sq.km at CKE within the Kelani Ganga Basin, but closest to the city of Colombo and is highly industrialised. Due to the low lying nature of the land, drainage of this basin cannot be adequately effected by gravity and a pumping scheme is necessary (minor flood protection scheme). The SLLR&DC is in the process of implementing such a major pumping scheme in order to assure the safely of the large industrial complex that is envisaged within this catchment. Under gravity conditions the Mudun Ela drains into Kelani Ganga mainly through 2 No. drainage crossings under A3. The other culverts are either insignificant or are malfunctioning. 2-2 II 2.3.2 Micro Catchments There are 6 No. such micro catchments identified between the southern end of the Ja Ela catchment and the northern end of the Kalu Oya catchment. All these catchments are intercepted by the CKE along its trace which lies west of the existing A3. Some of them even have the major part of their micro catchments between the existing A3 and the proposed CKE. They originate in the highland urban areas around A3 and drain towards Muthurajawela through stretches of marsh, and paddy tracts. These micro catchments are detailed below: Location Estimated catchment Area at CKE (Sq.km) I. Between Ja-ela and 2.5 Nadurupiliya 2. Between Nadurupitiya and 3.99 Nagoda J. South of Nagoda 1.79 4. South of Nagoda to 3.48 Mahabage 5. Mahabage to Mathumagala 0.77 6. Mathumagala to Mabole 0.95 Fig. 2.1 gives in schematic form the relative positions of the respective catchments and sub-catchments and the drainage conditions which prevail during storm conditions. Figure i. 1 (scale -1:63,360) in the docket shows the different catchments, the river networks and their drainage in relation to A3, the proposed CKE, the Negombo Lagoon, Muthurajawela, the Dutch Canal and Kelani Ganga. 2-3 SM^ • ::^- I in Hg 2.1 [\\ in NEGOMBO UGOON fiUiM ratfUfttuiP flftirr m taOKKA r in in in in m in in in ATTANAGALU OYA in DANDUGAM OYA in CATCHUENT in in URUWAL OYA CATCHMENT JA-ELA l.l CATCHMENT MUTHURAJAWEU MINOR SUB MARSH k CATCHMENTS in RESERVATION (6 NOS.) NETWORK OF in CANALS ;-w 1 •• 1 in lU KALU OYA CATCHMENT in m \\\ MUDUN ELA in CATCHMENT m m m EXISTING A1 Ml H^iiiiiiiinm nNiniiiniiiiiiiiiiiiii in \\\ x;>o^K;>?ö^e>>^^ :>=:>=fi :=Ä>>-±fxK>5>>:=Ä:^>^^^^ SCHEMATIC SKETCH SHOWING HYDROLOGICAL & HYDRAULIC CHARACTERISTICS AFFECTING PROPOSED CKE DURING STORM CONDITIONS 3. RAINFALL ANALYSIS 3.1 Available Run-ofTData Flow data within the catchments intercepted by CKE have been systematically recorded only at one upper tributary of the Attanagalu Oya. at Karasnagala. Flow measurements for this station are available fora period of 25 years from 1971 to 1995. The catchment area at the gauging station is 53.4 sq.km., which is only 7% of the entire Attanagalu Oya and Ja Ela Catchments. Furthermore, the catchment characteristics at Karasnagala differ significantly from those of the entire 770 sq.km. catchment, especially in terms of gradient, land use, and flood detention. Hence it is not possible to use this data to simulate run-ofTcharacteristics of Attanagalu Oya and Ja Ela at A3 or proposed CKE, Relevant Hydrographs have therefore been developed applying Mathematical Models using available rainfall data and other catchment parameters and have been described in Chapters 4 and 5. L 3-1 3.2 Available Rainfall Data The daily rainfall records were collected from different sources for ten rainfall stations in and around the project area.(Please see Fig. 3.1) Rainfall Station Period of Record No, for the Study Ambepussa Govt Farm 1967- 1997 1 Chester Ford Estate 1967- 1997 2 Kirillawala Group 1987- 1997 ^ ' Halgahapitiya Group 1967- 1997* 4 Colombo 1967-1997* 5 I . Katunayake 1967- 1997* 6 Henaraihgoda Bot. Gardens 1967-1997* 7 Vincit Estate 1967- 1997* S Pasyala 1967' 1997* 9 Walpita 1967- 1997* 10 L • These Rainfall Stalions aie more relo anl lo the study area, (Please sec Ani\c\ I,) Table 3,1 : Lisi of Rainfall Stations L 3.3 Rainfall Intensity Studies A Rainfall intensity study in Sri Lanka has been carried out by V R Baghirathan and E M Shaw in 1978, This original work was up dated by the Hydrology Division cfthe Irrigation Department in 1990 [Ref: Dharmasena G T, Engineer, Quarterly Journal of lESL Vol. 18 Dec 1990]. The project area is located in the Hydrological Region III, L which covers the North Western part of Sri Lanka, However, the rainfall intensity study already carried out is based on Katunayake and Colombo rain gauges and therefore it was L- L L 3-2 L /• •".••sS^TTTCF... ••.:'-^;^k J':,t*'a^-. FIGURE 31 Kii4«A«prit/l PjlY*'* N r i ili!!| 1 • • • •—»—— •« — ^ •—'^f 11i Hn ; • uo ' ! ( 1 1 0 1 AOrj ( 1« I n! I; II 1" - I I Tl Sca'« Ijtl H M lO km iMiiuiifH 1iHiiiiitn i ' miiiniifi LOCATION OF RAINFALL STATIONS ..'jjte.'«-t>^i^'ii., I r decided to up dale and cany out more site specific analysis for this study as stipulated in the TOR. Therefore, daily rainfall data at Vincit Estate and Katunayake rain gauges for the most recent 30 years were collected to carry out a fresh intensity analysis and these r Depth Duration Curves [DDC] are shown in Figure 3.2 and Figure 3.3, These two DDCc were used in addition to the DDC for Colombo and is shown in Figure 3.4, Table 3.2 shows the results of this rainfall intensity analysis. For Katunayake and Vincit, analysis was done for a duration of 5 days. For the frequency analysis. Extreme Probability Type I distribution fGumbel] was adopted. 3.4 Catcfameot Rainfall The major catchments considered for this study are listed below with the catchment areas at the intersection of the A3 road. Dandugam Oya - 587 sq km Ja Ela - 183 sq km KaluO>a - 05) sq km For Dandugam Oya basin, rainfall intensity analysis of both Vincit and Katunayake were used. For Ja Ela only Katunayake rainfall was used as the catchment is mostly coastal. For Kalu Oya, rainfall intensity for Colombo was used. For all these stations, rainfall corresponding to 50, 100 and 200 year return periods were used as design storms. Regarding the duration of the design storms 05 day were considered for both Dandugam Oya and Ja Ela and 04 day storm was considered for Kalu Oya as the catchment is smaller. By extracting the intensities from the DDCc of three rain gauges, 50, 100 and 200 year storms were developed for 03 hour time resolutions. For the design of storms the standard procedure in storm designs by the application of unit hydrographs technique was adopted. 3.5 Flood Experienced in Colombo City in June 1992 Dharmasena has analyzed this flood in his study "An Act of God - The Great Flood in Colombo on 05^ June 1992; and is attached at Annex A. The essential features that can L be observed from this study are: The rainfall was intense and occurred over a period of approximately 12 hours I The centre of the storm was Colombo City and depleted in areas around it in the Kelani and Bolgoda Catchments L- In relation to the proposed CKE, while Colombo experienced a 24 hour rainfall of about 494 mm Katunayake experienced only 72 mm L 3-3 [ I o o o o o o o o o «o o o 2 9*» N •V <, ' .£KtMB' •• f-ig.y.3 r V- V- O ( o. o o \\\ \ \ \ \\\ « < ^ < V < \\\ z 3 1- ^\ V O O o o o o o O o o o o o to m N ~ •WW NmvjNiVä o < Hl o: z o H^ (O > 1-1 Q >- O O -J o Q: O >• X o 2 o liJ o: o O u o: o t _ < tr roï I X (- n. u G o m o in o n o n V * 10 n N Ci «) «•V3U1 - Hi.d3a ^^vJNlva *' t' •„.tésbv« • •^^*'^^ Table 3.2 n O cj n tn o in CO o r-i o in n in r- r- T o CO O) to n O) •q- CN o CO CM CM n -v to in (M n -T T m O ro •v "q- in O T- TÏ- (M O o in o o o o o o CO in -q- 1- r^ Tj- 01 O CO CM r— r^ in o in O) p) n "V •v CM ro V «ir in CM co "T "^ "O" E T in a> •^ fo in in in in in o tn in o «o r- co co fo co •>- co fO O) •^ CM (D T- (O fsl fO CM "^ UJ o CM to co T -tr CM co fO ^r ^ z LU >% •D i. T r- co CD rO co o ID 03 CM o CM in u> O ™ T- co in CT) T in o T vT) CM OJ fO co TT CM en co r- T- CM CM co co T o. f^ CM co co n < u. CE: in CM iD co co co tn in co CO CM in O in ra •<- r- O) n co in o -^ O) o> in co CM in CM CM CM co »- cxj co co co •t- CJ CM co co o L L CM co "ïT T- (M CO ^ tn CM n T in Q L ca V) O c XI 5, .£ E co L- '^ o o I e: W o 3 C5 co L ie: [ l ••iÄ„.i- "üTl r Rainfall Frequency Analysis by difTeretil methods, of this recorded storm, revealed that r the Return Period of this stonn was in excess of 500 years fora 01 day storm Hence, considering these aspects, it is concluded that his storm has no significance to the design return periods required in the CKE study. 3-4 .^ -m'-'-.. - .*.." -. •-j*te-...""-ft.>'-i - I 'fi'i tJK 1111 r r 4. CATCHMEIVT PARAMETERS r Since long terms flow data recorded in Ja Ela and Dandugam Oya is not available. Mathematical Models have to be utilized. These models use rainfall information and the catchment characteristics in order to develop a Flood Hydrograph of any known return period. Different models use different catchment characteristics in order to develop a hydrograph which simulates actual flooding patterns both in magnitude of flow as well as time. Some important catchment parameters of the 03 major basins in the study area are r given in Table 4.1: '—' ™~- " -^'^—' River Basin Dandugam Ja Ela Kalu Oya Ova Catchment Area at A3 [sq km] 587,0 183.0 51.00 Catchment Area at CKE [sq km] 589.0 183.0 52.50 Stream Length at A3 [km] 057.0 030.0 13.20 . Stream Length at CKE [km] 057.0 031.0 11.70 Stream Slope [%] 000.1 000.3 00.15 1 Detention Area at A3 [Ha] 9,550 2,970 533 Detention Area at CKE [Ha] 9,750 2.970 521 Table 4,1 : Catchment Parameters L a-i [ r r 5. DEVELOPMENT OF FLOOD HYDROGRAPHS 5.1 Available Data . There are many mathematical models for river flow simulation but some of these models require very extensive field data. Collection ofthis necessary field data is time consuming and considering the time frame ofthis study, only limited field data could be collected. Hence, the consultants decided to use different mathematical models to develop the required flood hydrographs. 5.2 Available Alternatives for Development of Flood Hydrographs 5.2.1 Model 1 - SCS Model Salient features of the model are given below: • This model was described in "The National Engineering Handbook No. 4 - Hydrology by the USDA Soil Conservation Services [SCS] published in 1955, which presented a method for Synthetic Unit Hydrograph development. It is applicable to small to medium sized water sheds. * This method uses a dimensionless unit hydrograph to provide a standard unit hydrograph shape. An average veIocii>- method is used to calculate lag time. In this method the ratio of lime to peak to hydrograph duration is fixed at 05, * This method assumes that the main portion of the unit hydrograph has the approximate shape of a triangle. * Catchment characteristics are used to develop a SCS run-ofF curve number. Figure 5.1 is a "Schematic Diagram for Development ot Inflow Hydrographs "by the SCS Model Method". 5.2.2 Model 2 - HEC 1 Model This model consists of two modules namely: the rainfall-runoff relationship and reservoir routing For the rainfall-rxmoffmodule, the synthetic unit hydrograph developed by Snyder is used and flood routing through a reservoir is based on the normal step by step method of water balance applicable to reservoir routing. Engineers in Sri Lanka are very familiar with the Snyder Technique for the development of a unit hydrograph. This model -developed by the US Army Corps of engineers - is also adopted widely in the United States and other countries. i 5-1 r FiG, 5'l SCHEMATIC DIAGRAM FOR DEVELOPMENT OF INFLOW HYDROGRAPH? r RAINFALL RECORDS TEMPORAL RAINFALL PROFILE r CATCHMENT RAINFALL -fcÄi'CHMENT AREAJ ANALYSIS HYDRAULIC LENGTH WATER SHEO SLOPE INTENSITY-DURATION- FREQUENCY CURVES rrDESIG; N RAINFALLS ANTECEDANT MOISTURE CONDITION HYDROLOGIC SOIL CROUP -^SOIL CONSERVATION SERVICES -V RUNOFF CURVE NUMBER PROCEDURE; HYDROLOGIC CONDITION UND USE AND TREATMENT • SUa-CATCHMENT HYDROGRAPHS • • DISTRIBUTED CATCHMENT DYNAMICS USING KINEMATIC WAVE FORMULATIONS L *._. I INFLOW HYDROGRAPH AT A3 & CKE CROSSINGS L L [ The salient features of this model are; r • An initial loss is apphed to the storm rainfall and a constant rate ofloss thereafter is adopted. • A coefficient Cp is computed under the Snyder Technique and is indicative of the catchment slope • The time to peak tp of the unit hydrograph is estimated using the catchment parameters • The outflow hydrograph is computed by considering the catchment as a reservoir with a known width of spill, through which the inflow hydrograph is routed. Many catchment parameters are used in simulating the reservoir which is a major component of (he model. • The Snyder Technique is used to develop the unit hydrograph, which also uses many catchment parameters. Figure 5.2 is a "Schematic Diagram for the development of Inflow Hydrographs by the HEC 1 model method. 5,3 Model Selected for the Study In the absence of long term stream flow data for the major river basins in the study arf-a, the use of mathematical modeis to develop flood hydrographs is very necessao'- Although mathematical models are developed and tested, no such model can be said to be applicable to any catchment. Every model therefore endeavours to simulate actual behaviour of the catchment by using catchment parameters as well as formulae and assumptions which characterize each model Hence it is preferable to do a flood study of a catchment using more than one catchment model. Although the developed hydrographs using the 02 models may not be identical, the results can serve to assure the designer that the results obtained by applying both models are varying within acceptable limits say 10 to 20%. It is with this mtention that the Consultants have selected the HEC 1 model to develop the flood hydrographs presented in this Draft Final Report, as the SCS model was used in developing the preliminary flood hydrographs indicated in the Interim Report. 5.4 Flood Hydrographs Developed for Pre-Projecl ConditioDS 5.4.1 Model Parameters Used For flat catchments, the Snyder's Coefficient Cp = 0.3 has been used for all catchments. 5-2 F ig. 5.2 r r SCHEMATIC DIAGRAM FOR DEVELOPMENT OF INFLOW AND OUTFLOW HYDROGRAPHS RAINFALL RECORDS TEMPORAL RAINFALL DISTRIBUTION DEPTH DURATION FREQUENCY ANALYSIS — 0 D F •— CATCHMENT AREA BASIN RAINFALL TOTAL BASIN RAINFALL STORM DESIGN TIME OF CONSENTRATION INITIAL LOSSES * SNYOERS MODEL SNYDERS Cp UNIFORM LOSS RATE BASIN INFLOW HYDROGRAPH RESERVOIR INITIAL DETENTION DETENTION VS I ROUTING LEVEL ELEVATION RELATIONSHIP i MODEL L BANK OVERFLOW CHARACTORlSTlCS OUTFLOW HYDROGRAPH Applying catchmenl parameters, Time to Peak [Tp] has been computed to be as r follows. Dandugam Oya - 12.0 Hrs Ja Ela - 06,0 Hrs Kaiu Oya - 05.0 Hrs Catchment Losses for all catchments has been applied as follows: First Hour of Storm - 0.25 mm Thereafter - 1.25mm/hr Flood plain width, needed for the model as estimated from field data is: Dandugam Oya - 400 m Ja Ela - 500 m Kalu Oya - 300 m 5.4.2 Flood Routingof Major Catchments Dandugam Oya, Ja Ela and Kalu Oya using the Storm Rainfalls Computed from Depth- Duration-Frequency Curves [Figure 3.2, 3 3 and 3.4], the Catchmenl Parameters and the computed model parameters, routed flood hydrographs were developed for Dandugam Oya, Ja Ela and Kalu Oya catchments for Return Periods of 50, 100 and 200 years. Figures 5.3 to 5.11 consisting of 09 No. printouts show these flood hydrographs. Each printout indicates the Inflow Hydrograph and the Outflow Hydrographs. Dandugam Oya Hydrographs The Inflow and Outflow hydrographs represent the flood at A3. The outflow hydrograph together with the Ja Ela outflow hydrograph and the hydraulics of the system downstream of A3 is then used to estimate the flood flow pattern at the CKE crossing and to estimate the flood levels in the marsh and lagoon for the different return periods. Ja Ela Hydrographs The Inflow and Outflow hydrographs represent the flood at A3 as well as at CKE, since the Ja Ela is confined between flood bunds in the reach from A3 to CKE. This outflow hydrograph is then used together with that of Dandugam Oya to estimate the flood levels in the marsh and lagoon for the different return periods. 5-3 Fig.5.3 r w ? < o. Ml IA 3 O Q < E O O O _i o LX. o o o o o o o o o o o o g 00 sK UI UI •V M w soaiuno u| aBjeqosjQ i.ittj'i r t-"ig.5.4 SDauina u\ aGnsi^osiQ Fig.5.5 w <0 X L' o o o o o o o o o o L r< o co u> CM SDauino ur aßjeqDsia [ r F ig. 5.6 r CO X D. rf CO O > o:? O soaiuno ui aßjeqDSfQ Kig.5.7 r X o: g o -^ >- X 3 o UJ o o < * l. L soaiunDUiaßJBM^Sia L L Fig.5.8 5= X Q. (A 3 w o 2O 01 O < UJ 0) >- E a: o o> o oX Csl o 3 Ü sosLuno uf aSjeq^siQ -' .-tt:^!..^- r Fig. 5.9 r r. 5 CO X Q. < LU O >• O o • <£ o >- >- O Q 3 O 5 L L 1 soawno NI aoyvHosia -.r^p^w».* f-'ig.5.iü CO O g CC ^ iili :::^ o5 • cr' soawnoNiaodVHosiQ r Fig.S.U r r. r si co w a: < LJJ >- O O Qo: CSl o ' È o 1 O 3 O ^ ' o 2 • soawno NI aodVHosia r-'h9r r Kalu Oya Hydrographs Since the CICE runs East of the A3, the inflow and outflow hydrographs have been directly computed for the CKE crossings. These outflow hydrographs together with the hydraulic parameters downstream of CKE have been used to estimate the flood levels at CKE and A3 for 50, 100 and 200 year Return Periods. Table 5.1 shows the ordinates of outflow hydrographs for 50, 100 and 200 year Return Periods for the 03 No. catchments. 5.4.3 Flood Routing of Minor Catchments An empirical formula has been developed for small catchments relating a flood jKak and the catchment area as: Q CM''* Where M Catchment Area in Square Miles Q Flood Peak in Cusecs C A Coefficient representing catchment characteristics and rainfall Since Kalu Oya is a comparatively small catchment and the flood peak is known, it is possible to compute the coefficient C for Kalu Oya for the different return periods and apply this to the Minor catchments encountered by the CKE; as these micro catchments are hydrologically similar to that of the Kalu Oya, On this basis the flood peaks for Mudun EJa and the 06 No. Micro Catchments for the different return periods has been estimated. For Kalu Ova' Applying Q = CM V* Return Period [Yrs] Coefilcient [C] 50 365 100 404 200 434 L 5-4 Table 5.1 r r TTT^ ^^ p (^ Ö O- U-l 00 T o •1 l^\ Art l—i tfy. r*\ CPO^ 0nn0 Oi^^ O^-x <ÉA0 (ÏOA O«^t' — o o PI O P —< 00 r^ (s o\ r-- -o — rj 1^ fO ^ •* 1.*1 VI V-, V~l fO 1*1 CN rj f^ ~ ^ O O o O O o fN o o O o o o 00 O OO »n DO (N O f^ o o C3 o o O (~i vS K — — r<>o^oor-iM — i/-it^oooooo>otn(N — o-Smr^ — Oït^'ï ^—'(^{Nmt^t^fiii^r-i ;^ mmmnMcsrJtN™ — M ^e2£s?:s;^g^:3;ssE:^?ssgsS2^§222lS^lE£i 00 •O o f^ c> o o fs o- •O- «^ 1^ wSö^oood'öcK'o^oo'ö^'oov«O 0\ MM U-1 — (N f»l P W'Orl'TfSOOT — oo'or-iöit-ii-ii-- •o- TT ooooo^Of^nmw)!^ — v-i—•(vocooSchO'oo'o o ö 1-1 o »d W M rn 'T "O t^ — K o.' "^ ld H H ed ^ o' >d t oC bd ^ — — fN^-t•o(so^-o^r~^—<0Ol/^(Nc^ü0^- OOOOOv-''"f^>/-)~C3«-,»-l^—.V' —'^^-p*> -. O_ f^ m -o o 0\ o r~- o o o SSt- - rJ (N o r^ o o\ d ö ö s Ö> UI o o f»l (-J u-i r-' r>i ^ m ö o\ m r^ r-' o 'v' t^ 'O "O T m —• — cNtNcsr^ts—•—• — —1 a t/i o^::!2ss;^5!^^gsPPssgÄSi|wg^li rr cJ f^ — O (N o 1-- •o o Tl o o o o S •o «o m o. o ööf-iodoo^c^ö'dö'ÖMf^öo—; Oi 'T (N I y CS OOOOQOOOO OOOOQpOOp o o W-I -ir o •-. vS -d r-' r-' (^ 00 OJ OCJ fS f^ 00 lo c^« o ö ö — m S o o 00 -o 1-1 1 ;^ ^ s o u~o o o vi m —• 00 00 r^of-r-ooooojN poopp—••-•>oiof-_ •qmffi'ïp^opQq öocsr-*ö--"viöt-^t~'rS(SC' Q ^ 1/1 oo^ïïSR^5'^;?;8;spfss«2§ïï . , -.'.TftiEJ r Mudun Ela r Catchment Area = 5.9 sq km at CKE Return Period [Yrs] Peak Flow [Cumecs] 50 19.3 100 21.4 |200 23.0 Micro Catchments [06 No.] Total Catchment Area = 13,48 sq km Return Period [Yrs] Peak Flow I [Cumecs] j j50 35.5 1 1 100 39.8 1 |200 42.7 1 5-5 HMêt: 6. H\ DRAULIC CONDITIONS DOWNSTREAM OF A3 AND CKE r 6.1 General The proposed trace commencing from the left bank of Kelani Ganga, crosses Kelani Ganga and runs in a northerly direction intercepting the catchments of Mudun Ela, Kalu Oya, (Jruwal Oya (Ja-Ela). Dadugam Oya and the micro catchments intervening (hese basins. Of the above, Mudun Ela and Kalu Oya are right bank tributaries of Kelani Ganga, while Dandugam Oya and Ja-Eia drain into the Negombo Lagoon. The micro catchments drain directly into Muthurajawela marsh. The proposed trace at its furthest point is about 3.5km from the sea and is essentially located within the flood plains extending from Kelani Ganga to the Negombo Lagoon. The schematic in Fig. 2.1 indicates the complex nature of the drainage network in the area traversed by the proposed CK£. Detail inspections and studies revealed that, for the purpose of this study the drainage pattern under storm conditions could be schematically represented as in Fig. 6.1 in view of (a) the section of old Dutch Canal between Kalu Oya confluence and Ja-Ela is clogged up with weeds and does not play any significant part in the drainage of flood flows, (b) minor catchments discharge directly into Muthurajawela marsh ,(c) (he? marsh, because of its proximity and low elevation can be considered as an extension of the lagoon under flood conditions and (d)Ja-ela because it is canalised discharges directly in to Negombo Lagoon. 6.2 Mudun Ela Catchment CKE traverses mainly through marsh lands within this basin and the drainage system comprises a network of interconnected channels covered with weeds. The flood levels in the areas are dependent on the flood stage in Kelani River The high flood elevation corresponding to the 1947 flood is 2,5 m-MSL. 6.3 Kalu Oya Catcbment CKE intercepts Kalu Oya drainage at three locations crossing its three tributaries. Further the trace crosses and re-crosses the right bank tributary thrice. Right bank tributary area I mainly comprises marshy land, the elevation of which is close to mean sea level. The flood elevation is dependent on the flood stage in Kelani Ganga and the observed HFL is 1 about 2.5m-MSL. 6.4 Micro Catchments •r Micro catchments between the catchments of Kalu Oya and Ja-EIa drain into Muthurajawela marsh which is hydraulically interconnected with the Negombo Lagoon, Under storm conditions Muthurajawela marsh is submerged by the back waters of Negombo lagoon. 6-1 SCHEMATIC OF SIMPLIFIED DRAINAGE SYSTEM rUNDER STORM CONDITIONS^ r Discharges from ihe micro catchments into the marsh on the easiem side of CK£ need be passed on to the western side of the marsh through suitable openings. r 6.5 Ja-£la Catchment Drainage from this basin flows along the Ja-Ela canal and drains into Negombo lagoon. Because of the canal embankments Ja-Ela does not give'rise to overland flows in the marsh traversed by it. Oyerlandjlow^is limited^to spill overs from low sections of the earthen embankments- Water elevations in the canal are directly dependent on the water surface elevations of Negombo lagoon. CK£ intercepts Ja-Ela about 4600 m upstream of the lagoon and about 1460 m downstream of A3. 6.6 Daodugam OyB Catchment Drainage from this basin flows into Negombo lagoon through Dandugamoya, an extrabutary and through channels taking off Mahadora Ela. Under flood condiljons part of DadugamOya discharge drains into the lagoon as over lari^d flow. Water elevations in •Dandugam Oya are directly dependent on the water surface elevations of the lagoon. CKE intercepts Dandugam Oya 4250 m upstream of its confluence with the lagoon and 750m downstream of A3, With the construction of CKE overland flows need be routed through adequate openings on either side of Dandugam 0>a. 6.7 Section of CKE traversing along and through a part of the lagoon. Where the CKE trace runs along the lagoon minor drainages are intercepted and drainage crossings need be provided to cater to these discharges The part of CKE passing through the lagoon will isolate hydraulically two areas of the lagoon. Adequate openings on the roadway are required to provide for interchange of water between these areas and the main lagooa L I [ 6-2 -m~ »TUT.» 7. HYDRAULIC DESIGN OF DRAINAGE CROSSINGS UNDER PROPOSED CKE 7.1 Methodology Methodology adopled in the hydrauhc design of drainage crossings is set out below; a) Estimation of pre-project 100 year and 200 year flood levels at the proposed drainage crossing site. b) Estimation of available waterway area (upto 100 year HFL estimated in (a) with assumed bridge span and stream bed levels. In the case of pipe culverts a minimum diameter of 900 mm was adopled in view of the length of the structure (over 35 m). The Inventory of Drainage Crossings Across A3 presented in paragraph 7.6 was used as a guide in arriving at the waterway area. c) Estimation of flow velocity through the structure vnth the 100 year peak discharge arrived at in Chapter 5. d) Estimation of velocity of approach (and get away) based on available sectional area of flow, hydraulic gradient and Manning's 'n". e) Calculation of flood afilux (h) at the structure using the relationship H = contraction loss + expansion loss = vf*C/2g ^ (V,- V,7/2g where Vj = velocity through structure V = velocity of approach C = coefficient dependent on the ratio of V, / V \'| A'2 O.I 0.2 0.3 0.4 0.5 0.6 0.7 C 0.36 0.34 0.31 0.28 0.22 0.16 0.1 Reference: Indian Practical Civil Engineers Handbook by P.N Khanna. 7.2 Estimation of Flood Levels The high flood levels pertaining to Mudun Ela and Kalu Oya were estimated on the basis of historical flood elevations in and around the intersections with CKE. Due to the lack of reliable data on historic flood stages of Kelani Gänga at the confluences of Mudun Ela and Kalu Oya (old Dutch canal), flood levels at CKE intersections could not be correlated with available flood records on Kelani (at Nagalagam street). L 7-1 r Flood elevations in and around Dandugam Oya, Ja-Ela and Muthurajawela marsh are dependent on Negombo lagoon. In order to estimate lagoon water surface elevations under flood conditions a mathematical model was developed with data obtained from site r investigations- 7.2.1 Description of the Model A schematic of the hydraulics of Negambo Lagoon is shown in fig 7.1 Negambo Lagoon covers an extent of 35 Sq km and holds about 45 MCM of water at 0 MSL. The water surface elevation is dependent on : inflow into the lagoon * flow in the channel connecting to the sea * detention capacity of the lagoon The flow in the channel connecting the lagoon to the sea is a function of the difference bet^veen the lagoon and sea water levels which are subject to tidal variation. A maximum tidal variation of + 0.5 m to - 0-5 m applicable to the months of November and May were used in the model as floods could occur during these months. Interchange between lagoon and sea can be considered as taking place through two channels, the parameters of which are given below: [. Channel No I Channel No 2 Length of channel in metres 1400 3000 Area of Section A (M^2) 333.1 167 Mannings'n' 0,0225 0.0225 R = Hydraulic Depth 1.75 1.66 Q(M^3/S) = AxR^.666 21520.2xS'O.5 10398.0 xS'H). A part of the Muthurajawela maish extending from the southern end of the lagoon up to Jayasuriya Road which acts as a physical bamer between northern and southern parts of the marsh, can be considered as providing additional detention storage during storm conditions. The area of this portion of the march has been estimated at 16 sq km and the average elevation is assumed to be + 0.15 MSL. The model takes account of the additional detention storage when the water surface elevation exceeds + 0,15 MSL at the southern end. The inflows fed into the model corresponds to the lagoon inflow resulting from 100 and 200 year return period floods with a storm duration of 120 hours. L 7-2 .' •••äfr*« Fig. 71 CHANNEL No. I CHANNEL No. 2 r L = 1400 m L = 3000 m A« 333-1 m2 A = 167 m2 D = 2-6 m D « 2-5 m R = !.75 m R = I • 6e m NECOMBO LAGOON AREA - 35 Km2 AVE WIDTH « 3000 m AVE DEPTH = 1-76 m LOCAL DRAINAGE -f-^ •"t^H- -H-f DANDUGAM OYA •JA- ELA Ml/THURAJAWELA MARSH < 2: AVE EL +0.15 MSL < o EFFECTIVE DETENTION z AREA « 16 Km2 o < X _ _DRAINAGE_BOUNDARY^ __ _ DRAINS VO KEUNI GANGA SCHEMATIC OF NEGOMBO LAGOON HYDRAULIC CHARACTERISTIC UNDER STORM CONDITIONS •••i**":;-Tsw»5" - «Si^fW?- r Direct precipitation over Ihe surface of the lagoon and Ihe effective area of the marsh has been added to the detention storage. Losses due to evaporation and infiltration into the ground have been neglected as these are negligibly small dunng storm r conditions. In operating Ihe model if has been assumed that at lime zero, (the beginning of the storm) both lagoon and the sea are at MSL Since the storm duration is ten limes the period from maximum to minimum sea levels, this assumption will not appreciably affect the estimated maximum value of the water surface elevation. 7.2.2 Results Obtained from (he Model TTie maximum ivaler surface elevations at the southern end of the lagoon caused by the 100 year and 200 year flood inflows are estimated at 0.776 m andl.002 m respectively. The maximum water surface elevations are reached 20 hours and 28.5 hours after the peaks owing to the moderating effect of the large detention capacity of the lagoon. The water surface elevation corresponding to the 100 year peak inflow is 0.686 mMSL. Flood routing is given in Table 7.1. 7.2J Estimation of Flood Levels along CKE Trace Methodology for the estimation of flood levels in Dandugam Oya, Ja-ela and the. Muthurajaweia marsh is presented in Figure 7.2. Reach of CK£ within the Lagoon (22+250 to 24 + 200) High flood elevation within this reach (in the northern part of the lagoon) is estimated at 0.77m MSL, This level is higher than the observed flood levels in the area estimated at about 0.3 m MSL. Dandugam Oya (18+ 725) The water surface gradient of the Dandugam Oya downstream of A3 under flood conditions was estimated as 0.0000968 and the estimated high flood level at CKE is + 1.19 m MSL. JaEla(I5 + 360) Water surface gradient of Ja Ela downstream of A3 under flood conditions was estimated as 0.00025. and Ihe estimated high flood level at CKE is + 1.93 m MSL. Reach of CKE between Ja Ela Crossing (15 + 360) & A3 Crossing ( 7 + 120) b L L 7-3 L • • ti- '^jTi'-rr-i' u • • -1 i • • Il • f'"- 11 Ift . . jf r r r. Table 7.1 Negombo Lagoon Flood Routing 100 year Flood - 6 No. Sheets 200 year Flood - 6 No. Sheets L L L [• [ L [ r ö ö ö ö ö ö ö ö ö ö o ö ö ö ö ö ö o ö ö ö ö ö ö ö ö ö ö ö ö ö ö ö o ö ö o ö ? 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AT CKE TRACE (WITHOUT ROAD) FOR DESIGN Q WATER WAY AREA PROPOSED AT STREAM CROSSING FLOOD EL. U/S OF CKE ! LENGTH, AREA OF SECTION OF •^ ^ STREAM & 'n' VALUE ' FLOOD EL. D/S OF A3 • • f WATERWAY OF EXISTING „, ^ __— BRIDGE AT A3 ' ' FLOOD EL. U/S OF A3 -'(t. ....1--J^.,^, ^^ -^•^'- .. .. -. L. V v'Mjk I r Within this reach drainage from minor catchments discharge into the marsh on the eastern side of CKE trace. Openings provided in the roadway will lead this drainage onto the marsh on the western side. Drainage within the marsh is through the many r channels which connect the Old Dutch Canal to Hamilton Canal and channels discharging directly into the lagoon. Under flood conditions marsh is submerged and drainage is mainly through overland flows. Flood levels under these conditions cannot be estimated with any degree of accuracy. The flood gradient has been calculated on the basis of overland flow and its value is 0.0000334 Reach of CKE bet\veen A3 Crossing (7 ^ 120) & 4 + 400 Flood elevations are those of Kalu Oya. Based on historical flood levels the hundred year return period flood level at Kalu Oya RB is estimated at 2.65 m and 2.60 m at Kalu Oya LB. Reach of CKE from New Kelani Bridge to 4 -*• 400 Flood elevations are those of Mudun Ela. Based on historical flood levels the hundred year return period flood is estimated at 2.30 m MSL. 7.3 Design of Major Drainage Crossings & Other Waterway Openings The watenva\' areas required to limit the hundred year return period flood afflu-x to a maximum of 0.1 m were computed using the peak value of flood hydrographs, channel sections, estimated velocities of natural channels. In the case of Ja E!a it is proposed to provide a bridge spanning the existing watenvay and roads on either bank. Hence there is no change in pre project conditions as the waterway is confined by stream banks. In the case of Dandugam Oya the bridge uili span the Oya and the roads on either bank, but the overland flood flows which occurred in pre project conditions have to routed through two no. 15 m span bridges and a 10m span bridge over existing drainage channels. h. The location, span, required water ways, HFL and odier details are given in Table 7.2. 7.4 Impact of CKE on Flood Levels Upstream of A3. 7.4.1 General The impact of a 100 year flood upstream of A3 and CKE is shown in Table 7.3 and the Schem'aiic High Flood Water Surface Profiles of Dandugam Oya, Jaela and Kalu Oya are shown in Fig. 7,3, 7.4, and 7.5 respectively. Catchmentwise impact is discussed in the following paragraphs. L L L l-e. Table 7.Z / r Table 7.3 r €0 < 0> UI I 6 E tr u> r li^sSos" UJ er I- UJ u. > go _j < I u UJ o oir o z liJ —1 O o V) o ir O O r Q. in d o >- o é _j d UJ h- Z lU I o LU UJ LLI W -I w -) tr Q O LU o O o ir O o d ir I o a. u. 't 5 u- z UJ < H < O o: o: > 3 UJ UJ U < UJ C < Q. UJ v_ (O ^ > Z o < ü O. co o Z) 1" I o U r z m f- < lll 5 a ir °l UJ 8ä O o Uï O) 1 >• o < U o r< (- o Q O z UJ LU ü < < UJ CL o o ir UJ Q- UJ U. < _l Q UJ UJ UJ oO: > < n to UJ 2 U o £ I ffi »o < < o o O lli •Of < o O ob. hl É ü UJ O -3 f. O ir tE Q. O. bJ ü » « < O O ü. CL a 3 M (T UJ a ü 8 o UJ o r? < O o ä (E Q. o O bJ X a o o o o o o: a: < a o. z Ut J (.O bJ o. o. X O w u o • tH r r r O) u X < o 1 u w 1 ï < < UJ — — < ^- si u. 1 o z < ï ^ UJ o _I 1- X Z ü. o w o o UJ o o: O z < o (L o: (C 0. o ü • UJ H u (A • < I3 O i, UJ U 3 O. V) z (C < UJ 1- < ü ï UJ a -B o o UJ 0. -9 o X -j 1 O o: o u. UJ o. o o X o: o < (9 0. o' _J X UJ O o ffi Q z o u UJ UJ - UzJ til u O ~> -» z X O o a: cc < u X co ÜJ o u cc O 0. 0. o o z z UI ' kot J J T 8 f o N $ z o X 5 V) O (/> o z _J < o bJ 3C y- < X > H O UJ I- bJ o LJ < UJ O o Q: o. a. LJ O < u. o oc D. - O o r o LÜ tiJ U o. < z üi z < bJ O v> < X Z UI o u C!> IL. X LU o X < m O O 3 u u S U UJ ^ -> o o o: o: o. a' I- UJ «) Q: O •zr< o. o. -IZ UJ < tu t bi M t • *^ • -^ *' •- in' jn'l r r 7.4.2 Mudurt Ela Catchment Wilhrn Mudun Ela Catchment CKE runs about 760 iii upstream of M. The embankment fill results in a loss of detention in the catchment resulting \n an increase in flood peak at A3 crossing. The rise in flood level is estimated at 14 cms. this effect could be mitigated by the provision of an increased water way at culvert 3/1. The available waterways at the existing A3 crossings are grossly inadequate giving rise to increased flood levels and flooding times even under prevailing conditions. 7.4J Kalu Oya Catchment The CKE trace is about 1500 m upstream of A3 and will have no effect on the flooding conditions immediately upstream of A3. 7.4.4 Micro C'atchmenis between Mabole and Ja Ela The estimated rise in 100 year flood level upstream of CKE is 3 cm. The backwater effect ofthis rise upstream of A3 is negligibly small. 7.4.5 Ja Ela Catchment The proposed CKE crossing at Ja Ela intersection will not interfere with theja Ela watens-ay and will have no effect on flood levels upstream of CKE or A3. 7.4.6 Dandugam Oya Catchment CKE intercepts Öandugam Oya 750 m downstream of A3. The estimated rise in 100 year flood level upstream of CKE is 3 cm. This rise will have no effect on flood levels upstream of A3 due to the relati\ely large difference in flood levels(over 0.75 m) 7.5 Validation of Road Embankment levels 7.5,1 General Embankment levels at any point along the road is determined on the basis of the following Hydraulic Considerations '•* [Ij I.I m above 100 year flood level [" [2] IÜÜ year flood level + wave height [for reach of roadway within Negombo lagoon and Muthurajawela marsh] L L L 7-5 [3] 0.5 m above Ihe 200 year flood level Clearance and Alignment Considerations [4] 100 year flood level + clearance for boats or traffic +• deck thickness [in Ihe case of bridges] [5] elevations to suit vertical alignment 7.5.2 Mudun Ela Catcfimenf [0 + 400 to 3 + 209 of CKE] Estimated 100 year flood level = 2 49 m Estimated 200 year flood level = 2-69 m Minimum road elevation to meet requirements 1 to 4 is 3.59 m. 7.5J Kalu Oya Catchment p + 209 to 7 + 108j Estimated 100 year flood level = 2.70 m Estimated 200 year flood level = 3.00 m Minimum road elevation to meet requirements I to 4 is 3.8 m. 7.5.4 Micro Catchments from Malabe to Ja Ela |7 + 108 to 15 + 350] Estimated 100 year flood level = 1.18m Estimated 200 year flood level = 1.43 m During high flood conditions Muthurajawela marsh on the western side of Ihe roadwa> will be submerged and will be an extension of the Negombo Lagoon. This body of water could generate waves. Wave height is estimated using Saville Formula H = 1/X 0.0026 x[gF f'^ g U2 Where H = wave height in ft. U o: wind velocity in fVsec F B fetch in fï. Following Australian Practice for the condition of the marshal 100 year flood level a wind velocity of 96 km/hr [2/,6'7m/sec] is used. Fetch, which is the horizontal distance over Ihe water bod/^^ndicular to the roadway is about 2,190m. Wave height calculated using the above formula works out to 0.94 m. Due to the presence of marsh vegetation and canal bunds the actual wave height could be much lower. 7-6. r Since the wave height is less than lim this criterion is not the determining factor. r Minimum road elevation to meet criteria 1 to 4 is 2.28 m. 7.5.5. Ja FJa Calchmcnt - Bridge at 15 + 360 |r. Estimated! 00 year flood level = 1.93 m Estimated 200 year flood level = 2.43 m Clearance for trafïic on either bank = 4 m froads on either bank assumed to be at HFL] Assumed deck thickness = 1.0 m Minimuin road elevation at the bridge = 6,93 m 7.5.6 Dandugam Ova Catchment ' " [a] Reach from Ja Ela to Dandugam Oy a [ 18 + 700j Estimated 100 year flood level = 1.21 m ' • Estimated 200 year flood level = 1,46 m . ' Wave Height Fetch in this area is about 2,800 m and the W3ve height as calculated from . Saviile Formula is 1.05 m. Due to presence of sand banks and marsh vegetation the actual wave height could be much less. Since the wa-.e height is less than I i m this extension is not the determining factor. Minimum road elevation to meet criteria 1 to 4 is 2,31 m, [b] Dandugam 0>a Bridge [18^ 730] Estimated 100 year flood level ^ 1,21 m [ Estimated 200 year flood level = 1.46 m Clearance for traffic on either bank ~ 4m I [roads on either bank assumed to be at HFLJ Assumed deck thickness = 1,0m ' Minimum road elevation at the bridge = 6.21 m I' • [c] Reach Dandugam Oya to 21 + 075 .. • Estimated 100 jear flood level ^ 1.21 m I Estimated 200 year flood level = 1.46 m L . L 7-7 L Wave Height The fetch in this area is about 3,000ni and the wave height calculated from Saville Formula is 1.09m Since the wave height is less than 1.1m this criteria is not the determining factor. Minimum road elevation to meet criteria 1 to 4 is 2.31 m 7.5.7 Area Draining to Negombo Lagoon 21 + 075 (o 24 + 582 Estimated 100 year flood level = 0.78 m Estimated 200 year flood level ^ 1.02 m Wave Height = I.09m Minimum road elevation to meet criteria 1 to 4 is 1.88 m. 7.6 Inventory of Drainage Crossings Across A3 This is presented in Table 7.4 7-e 'r.!!>lf .'.-I - bllCClS t of 2 r -m^ 1 . N X UJ "O •^ Cfl f- 'T "H ^6 00 H B d d r X (/; d w UJ X X o: ft UJ t >• ig UJ ^ 0- "> eo Sr V1 hUI 1- > S- UJ d d 0. C X a in u - UJ .-X> < 2 z cOa —to E: £ _J O o Cl. •ca < z c 1- O < < < 5 S2 O l/l if. o 1 < l z Ä < u z 7. 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IMPROVEMENTS TO DOWTVSTREAM DRAINAGE SYSTEM TO MITIGATE r IHE LVfPACTOF HIGH FLOODS 8.1 The Concept In general upstream flood levels could be reduced by improvements to the downstream drainage system However as detailed in chapter 6 the proposed roadway is mainly confined to the flood plains of ihe river basins intercepted by it and the flood levels are directly dependent on the flood stages in Kelani Ganga or Negombo Lagoon. As such downstream flood elevations cannot be appreciably reduced using cost efl^eciive means, Catchmentwise r examination of the downstream lead away conditions are presented in the following paragraphs. 8.2 Mudun £la Catchment CKE intercepts Mudun Ela drainage streams about 800 m upstream of the confluence with Kelani Ganga The bed slope of the main stream is 0.0006 and Ihe waterways have adequate capacity. However the flood discharge has to cross existing AJ through two main openings one at I + 100 and the other at 2 + 150. The effective waterway area at these culverts are those of a 900 mm diameter pipe and two 1300 mm pipes respectively. If the upstream water\vay areas are increased to those of the screw type lifting gates at the downstream end, the discharge capacities can be more than doubled thereby reducing flood levels and flooding time. 8.3 Kalu Oya Catchment CKE intercepts the three tributories of Kalu Oya about 4500 m upstream of the confluence with Kelani Ganga [2000 m upstream of A3], The bed slope of the Oya in this reach is 0,000064 and the waterways have adequate capacity. As such appreciable reduction in flood levels cannot be achieved using cost effective techniques. 8.4 Micro Catchments between Mabole and Ja Ela TTiese drain directly into the Mulhurajawela marsh. In this reach (he CKE trace runs through the marsh parallel to the Old Dutch Canal which excepting fora distance of 1093 m is on the western side of the trace. Water surface elevations in the marsh under high flood conditions are directly dependent on the water level at the southern end of Negombo Lagoon, As mentioned in the Report of the Technical Evaluation Committee [para 5 page 4] the feasibility of improving downstream drainage by effecting improvements to Old Dutch Canal was examined. Although it is feasible to achieve slight reductions with improvements to the Old Dutch L t 8-1 I Canal and the nelwork of canals linking Old Dutch Canal and the Hamilton Canal, such improvements are not proposed due to: [a] high cost of construction and maintenance Section of Old Dutch Canal from its confluence with Kalu Oya to Ja Ela is choked with weeds due to the very low discharges and will need regular maintenance to keep it clear of weeds as appreciable canal velocities can be expected only during flood conditions. [b] Provision of an efficient drainage system in the marsh will result in the lowering of the marsh water levels during dry seasons promoting saline intrusion. These changes may not be acceptable from ecological considerations. [c] The projected rise in post project 100 year flood levels are less than 0.5 cms and the flood conditions downstream of CK£ will remain unchanged. [d] Effectiveness will be seriously hampered during high stages of Kelani Ganga, 8.5 Ja Ela Catcbmeot CKE trace intersects Ja Ela 1460 m downstream of A3 and this reach of the canal [as well as i 200 m downstream of CKE] is canalised with earthen embankments on both banks rising above projected high flood levels. The proposed under crossing at CKE will ' span clear of the canal and the roads on either bank and therefore the project will have no effect on the hydraulics of this waterway. Downstream improvements are therefore not considered. However if the proposal to increase the area of the lagoon is implemented, the excavated material could be used to widen and strengthen the embankments on either bank. 8.6 Daadugani 0}a Catchment CKE intercept Dandugam Oya 4250 m upstream of its point of its entry into the lagoon. Drainage from this basin flows into Negombo Lagoon through Dandugam Oya, an e.xtrabutory and through channels taking ofTMahadora Ela. Under high flood conditions the area upstream of the lagoon up to A3 [750 m upstream of CKE crossing] is submerged and becomes a part of lagoon. Flood levels are dependent on parameters of the lagoon and tidal fluctuations in the sea. Downstream improvements can increase the discharge capacity of the streams but will have very little effect on the upstream flood levels. 8-2 •....¥^tSäb.J^ -Ü r r 9. FLOODS MAPPED OUT 9.1 Dandugam Oya Catchment r. Inquiries in the field revealed that a significant flood occurred in May 1991 and the informants always associated that with a "dam bursting" upstream in the Atlanagalu Oya irrigation system which caused an unusual and sudden flood wave. Hence it was decided to take the maximum flood recorded at A3 during another significant flood that occurred in May 1967. The estimated catchment rainfall for this storm is given below: Days Catchment Rainfall [mm] 1 220.7 2 319.9 3 398.3 4 430.0 5 455.8 From the Depth Duration Analysis done in chapter 3 the following rain storms can be identified. Return Period 05 Days Ramfali [mm] 50 477.5 100 519.0 200 552.5 Hence the 05 day rafn storm which occurred in Ma\' 1967 can be concluded to be a storm of 50 years Return Period. 9.2 Ja Ela Catchment Similarly the estimated rainfall in May 1967 for the Ja Ela Catchment '\s: Days Catchment Rainfall [mm] 1 179.3 2 283.4 3 348.1 • 4 375.7 5 391.7 L From the Depth Duration analysis the following rainstorms can be identified: L L 9-1 I Return Period [years] 05 Day Rainfall [mm] 50 460 100 498 200 • 545 Hence it can be concluded that the 05 day rain slonn which occurred in May 1967 was about 50 year Relutn Period. 9.3 Kalu Oya Catchment Informants in the field always referred to the major storm of August 1947, which flooded Colombo City caused by storm rainfall in the Kelani Basin The flood conditions in the Kalu Oya are influenced not only by the rainfall within the Kalu Oya basin but also by the level of the Kelani Ganga, vvhere the Kalu Oya meets near Hekitta, Hence in this case the frequency of occurrence has to be decided by the storm conditions that prevailed over the Kelani Basin in August 1947. Ref. Report on Kelani Ganga Basin Scheme - Technoproexport - Moscow - 1961. The maximum daily basin rainfall during the storm was 457 mm. By an analysis of maximum daily rainfall for the basin the following results were obtained: Probabilir>' of Exceedence [%] 0.5 Return Period [yrs] 200 Average Basin Rainfall [inches] 17.9 Average Basin Rainfall [mm] 455 The following notes were also included in the report: The intense storm lasts 03 to 05 days. The maximum 24-hour rainfall is about 30% of entire storm. This indicates that the 1947 flood was due to a 200-year stonn. 9.4 Mudun Ela Catchment Since this catchment too is influenced in the same manner as the Kalu Oya catchment it can be concluded that the 4-day rainstorm which occurred in August 1947 was about 200-year return period. 9-2 r r 9.5 Field Surveys Done The Perimeter Survey necessary to identify the flood contour of a known flood that r occurred vvas organized in the following manner: The maximum level, which occurred during a known storm, was identified at the A3 drainage crossings viz Dandugam Oya Bridge, Ja Ela Bridge, Kalu Oya Bridge and Mudun Ela crossings. These levels were checked utilizing the nearest bench mark The surveyor set out the contour corresponding to this level within the catchment but upstream of A3. Using this contour as the centre line, cross sections were taken at 500-meter intervals. Flat plans were prepared to a scale ofl; 10,000 showing relevant nood contours identified in each catchment and the location of the cross sections taken were also indicated. Cross sections were plotted separately to a convenient scale. The following flood contours were identified for the respective catchments: Ï •• 1 1 Flood Catchment \ Ideniified Storni Return 1 Contour Period Level [Yrsl [MSL] Danducam Ova Mav 1967 50 1.8 Ja Ela May 1967 50 2.2 Kalu Oya August 1947 200 2.5 Mudun Ela August 1947 200 2.5 [" L L 9-3 L 10. MAPPING OF FLOOD IMJNDATION AREAS CORRESPOiVDIiNC TO HIGH RETURN PERIODS lO.I Methodology The following procedure was adopted: The flood level of ihe known flood originally investigated was noted and the return period of this storm was also estimated as shown in chapter 9. From the outflow hydrographs developed for this catchment, the peak values for other Return Periods were noted. Applying hydraulic principles, the corresponding flood levels of the other return period floods were computed. Using the perimeter sur\'ey plans and cross sections the contours corresponding to other return period floods were indicated in the flat plans [1:10,000 scale] and on the corresponding cross sections. Eg. consider the flood levels observed at Dandugam Oya From field investigations the observed highest flood level was 1.8 m MSL at A3, which was cross-checked by actual levelling. The surveyor traced this contour in the field, upstream of A3 and within the Dandugam Oya Catchment and also took cross sections at 500-meter inter\als. The dates of the storm was checked and, found to be a 5-day storm in May 1967. The total 05-day storm for the catchment was estimated to be 455.8 mm. The Rainfall Intensity Duration Tables for Vincit Estate and Katunayake revealcii that the 50 year Return Period Storm fora 05-day rainfall was 477.5^ '•>^ ?) Hence it was concluded that the 05 day rainfall of May 1967 was a 50 year Return Period Storm, Using the observed flood level of 1,8 m MSL fora re3tum period of 50}'e3rs, the high flood level at AJ for 100 year return period and 200 year return period was estimated using the peak outflows computed for these return periods. These flood contours for 100 year and 200 year return period storms were computed, applying hydraulic principles, and estimated to be 2.0 m MSL and 2,5m MSL respectively. These contours were then plotted on the survey plan using the 1.8 m MSL contour already plotled by the surveyor, 10.2 Estimation of flood I^cvels for Different Return Periods Based on the methodology described above, the high flood levels were computed for all the high return periods for the Catchments of Dandugam Oya, Ja Ela, Kalu Oya and Mudun Ela as shown in Table 10,1, 10-1 r Flood Levels for Different Return Periods r Table 10.1 OBSERVED COMPUTED FLOODS r FLOODS CATCH RETURN FLOOD RETURN FLOOD RETURN FLOOD MENT PERIOD LEVEL PERIOD LEVEL PERIOD LEVEL AT YEARS ATA3- YEARS ATA3- YEARS A3-m m m Dandugam 50 1,8 ioo 2.0 200 2.5 Oya JaEla 50 2.2 100 2.3 200 2.8 Kalu Ova 200 2.5 100 2.2 50 1.95 Mudun Ela | 200 2.5 100 2.3 50 L85 10.3 Duration of Flooding Flooding times eslimated on the basis of flood flows exceeding bankfull discharge are as follows. CATCHMENT DURATION OF FLOODING IN DAYS 50 year 100 year 280 year Danduoam Oya 05 05 '/ï 06 Ja El?. 02 02 % 02 Vi Kalu Ova 01 VA * 02 • ' 2 '/4 * Mudun Ela 05 to 07 days as Ihe flood levels are directly dependent on Kelani J Ganija levels. 1 Flooding could be 3 ^2 to 4 Vi days depending on the flood levels in Kelani Ganga. L L tO-2 I II. ADDITIONAL FLOOD DETENTION AREAS TO MITIGATE THE IMPACT OF FLOODS II.I The Concept If the anticipated post-project lOOyear fiood levels were significantly higher than the pre-project flood levels, it was envisaged that additional detention areas would be necessary to mitigate the effects of these floods. However detailed studies presented in this report have shown that the waterway openings proposed in Section 7,2 will limit the rise in the post-project 100 year flood levels immediately upstream of CKE, to 05 cms excepting Mudun Ela catchment where the estimated rise is 15 cm. Even here the rise in flood levels could be limited to 05 cms with increase in the watenvay at culvert No. 3/1 on A3, Therefore additional detention areas or other methods of lowering flood levels would not be required. It is relevant to mention here that there is a proposal to construct a reservoir in the upper reaches of Attanagalu Oya lo meet projected domestic and industrial demands during the next two decades. When this reservoir becomes a reality the fiood peaks in Dandugam Oya will be appreciably moderated and will help to mitigate the effects of high flood in Dandugam Oya catchment Muthurajawela Marsh and Negombo Lagoon. Catchmentwise descriptions of the anticipated flood conditions are presented in the following paragraphs: 1L2 Mtidun Ela Catchment Estimated rise in 100 year fiood level upstream of CKE is less than 15 cnib. Decrease in catchment detention due lo construction of roadway embankment is 404.000 M' and is about 30% of catchment detention. Rise in 100 year flood level upstream of A3 [due to decrease in catchment detention] is estimated at 02.5 cm. Pre-project fiood levels and rise in flood levels due to CKE could be reduced by increasing the waterway at culvert No. 3/1 on A3. 11.J Kalu Oya Catchment Estimated rise in 100 year fiood level upstream of CKE is less than 05 cm. Decrease in catchment detention due to construction of roadway embankment is 339.000 m' and is less than 02.7% of the catchment detention. This volume is partly compensated by the increase in detention due to rise in fiood level. Rise in 100 year fiood level upstream of A3 [due to decrease in catchment detention] is negligibly small. ii-i r 11.4 Micro Catchments Estimated rise in 100 year flood upstream of CKE is less than 03 cms. r Effect on flood levels upstream of A3 - due to backwater is negligible. 11.5 Ja Ela Catchment No change due to project as the existing waienvay of Ja Ela at CKE crossing and reaches upstream and downstream of the roadway will be maintained without any interference. The stream is canalised with embankments on either bank rising above projected water levels. Hence no impact on flood levels upstream of A3. 11.6 Dandugam Oya Estimated rise in 100 year flood level upstream ofCKE is less than 02 cms. Effect on flood levels upstream of A3 due to backwater is negligible as there is a difference of over 0.75 m within a distance of 750 m between CKE and A3 crossings. f. [• L L 11-2 L L\ 12. MOMTORING SYSTEM RECOMMENCED DURING CONSTRUCTION. <• As stated in our Inception Report the risk of sedimentation of the lagoon is best to be lefi to the construction stage with prior warning to the Tenderers to device suitable measures to counteract the problem. 7' There is not point in recommending elaborate procedures of water sampling and testing continuously, if the sedimentation problem is not seemingly, to be developed to alarming proportions. Therefore, the best option available at the moment is to be aware of the problem and to be prepared with an early warning system. This system should consist of t visual observations by persons charged with the specific activity. In the case of filling by reclamation of sea sand the normal practice is to remove the scum and sediment by proper drainage channels and pipes back into the sea. Hence there will be no sedimentation problem It is advisable to bring this factor also to the notice of the Tenderers so that they may device appropriate methods to eliminate the depositing of sediments. The placing of fill, will disturb the existing bottom layers of soft mud and sediment. As such turbidity should be seen during the construction stage. However, we propose that a monitoring system as described below should be undertaken at the four sites shown in Figure 12.1. Zone I is the Madabokka area which is \ulnerable in the context of prawn spawning, is to' be sampled on two locations on either sides of the road trace at a distance of 60,0 m from the centre line. Zone 11 consisting of the area close to the sea is to be sampled at 02 locations 60.0 mm away from the centre line of'he road trace. The time interval for sampling shall be as shown in Table 12.1 Table 12.1 1 Condition Interval of Sampling [days] 1 Clear weather 10 1 Rainy weather 03 1 When construction activities are close to the lagoon area 03 12-1 rr-'-- FIG 12,1 LOCATION OF MONITORING POINTS 13. IDENTIFYING AREAS ON VERGES OF NEGOMBO LAGOON FOR EXPANDING ITS AREA 13.1 The Problem 1281 m of Ihe proposed expressway will traverse through the lagoon thereby decreasing N its effective area. The surface area is the primary factor that drives the tidal flow which f determines the volume of water that is exchanged semi-diumally with Ihe ocean ensuring the continued functioning of the lagoon. Although the area lost due to the construction of the roadway embankment is only 0.13% of the area of the lagoon, it is considered V ( necessary to compensate for this loss specially in view of the fact that there is an existing \ • problem of encroachment in the lagoon and of siltalion in the entrance channels. V Compensation area is to be created by the excavation of suitable areas selected on the \\ verges of the lagoon. Area lost due lo CKJE is 45,000 m'. 13.2 Selection of Areas for Investigations L From preliminary studies and reconnaissance field visits areas were selected for further investigations and Client's concurrence was obtained before proceeding with the soil \ investigations. These areas are shown in Figure 13.1. The considerations which led to the selection of these area are; I [a] non-interference with existing developments on the lagoon shore and ; • [bj likelihood of sandy material being available at very shallow depths [c] non-interference with the western shore which consists of a narrow strip of sand I ,. dunes between the sea and the lagoon I [d] feasibility of increasing Ihe Madabokka area which is considered the most productive area of the lagoon, 13.3 Augur Hole Survey A soil survey of the selected areas was carried out by means of 50 augur holes drilled to a depth of 2 m. The location of the augur holes are shown in Figure 13.1. 13.4 Report on Sou Survey The logs of the augur holes are presented In Figure 13.2 sheets I to 5. In Ihe area covered by Ihe soil survey the top soil cover of about 15 cm in thickness is underlain by silt or clay organii? [OL] to a depth of about 80 cm. Below this level the soil consists of clay organic [OH] and clay fal [CH] to Ihe full deplh of 2m investigated excepting holes 29, 30,41,42, 43, 44, 47 and 48 where the material is poorly graded sand [SP]. Well graded sand was found in holes 39 and 40 belovv a depth 100 cm. 13-1 •7 "-. • - •»:-''f^-zT CKE TRACE SGOMBO lAGOON L E] AREA IDENTIFIED \ L l.iicaiion of Area Selected for Auger Mole Survey L i , Kig.l3.2 Logs of Auger Holes .7 r r LOG OF AUGER HOLES r LEGEND f = TOP SOIL OL = SILT OR CLAY ORGANIC C2 OH zz = CLAY ORGANIC L SP = SAND POORLY GRADED SW = SAND WELL GRADED CL = CLAY LEAN CH m. = CLAY FAT L L L Sh^zt 1 Qi 5 o VI 3 X Q.2 u o U o 3 O IM ITN T ""• X < • < X O X < 0. _J X 3 o u O o 2 n ^2 n CS X < Q. TTTT j. • •" "£:":: © ... -j- ; 'X' • • ^ ...J - _J nx • :, X ^ ' "f _,„ :::i.:-- o t/l 2 X X O O O u O CM IM cn s s s :::: s s s s 1 > s .,., s - ^1 .... S 0 > X ••• ¥ X 1^^ ^ rw— o; < Ï < ft ^1 J •.-v-K-VitM jrittt i. u^ :? o O O a.:i u u 3 OCJ 3 o O o. O ra in r s t/l r-4 © ^? ff r < < 3 _J X O •3 O tv TTT • s s 1 H i^\ ' X Êï < r i i i i 3 O. Q. °3 U o PS o 3 3 t/l IM IS (SI 1$ X X < < O O o: 3 o u tn 3 o (M ID © •?^^.jl 11 (11111 ::"""-:::|::": : :T ._ ..,;-.,-,>--_! ,1-" IN " 1 ' ' ' ' ' ' 1 1 1 ' ' 1 ' 1'^ ' ' L J ineet ^ of, t> ::: - — . V V \V\\V\V\'s • -. - J ^*^x\\\x\x\\\ • • - \ N,^^^ \^\^\^^^ \^\^^v \^ X — < Si 0". _i 3 O. ï o O 3 ' ••!' ^ {^ • 4 1 • * f • \ !ZJ f |, r- X • i 1 f •i rr _— i~ < -' 21 O m 3 O l/l g O © X < -3 o \ X < N L J •^ifii 1 •^._ • ^Ft^^l. T UJf J r o 1/1 u s O 0.3 o. g r Ol ;^i^uV;-;:v^S-| (D 1h^-.-v>:: ill:cj:t:<^-v':i^^:: X r < r ^ 5 IA 0. X "-u o 3 ^^ r-4 f. sWW ^^^^^^^^ ^^^^^ iÜ]^\\\ \ N\\\\ < >$^^^^S^ 3 _l 5 I 03 3 X O o o 3 — — • T-1 •'t —~1 -h 1 \.^i.^\.^S^\. '"" 1 [ ~t" -R f \\\\N .É. 1 ^\\^\.^\.^ "'il J j © ^^^\\\^ X --- . . . _ • • • 1^ \W\\ i i \\\\V X < < cc o X X ü O § •y \ o 5 > 11 _J o: S5 o »^ o o in 3 h^ y. 1 ^ ^P \\\ W CM" ::: "" "TT" ___... 1 1 X 1 ::: ~ _ Wvv f ::::: \\\>N X ._^._ [•. i:'^::: t1 ' 1 1 1 M !vv\\ I\ ^ -. \V < UU.;::::: = M L L J L Sheef 5 0^ 5 I o 3 o (/I 3 O a. 3 u O \ 3 è5 O o o o 1' (V DK_^ tN —- - - — --^ "" "ir (D J •i 5 i~ _i i u 3 ^ Q. o u (/I o 3 o o t/y 3 o o {-J rg • • • "— , , • • " • • ~ • • " " J-..\;'^;>.:.>..^^s-M'iV..- L';-V;>r:rJ^-:.-v-^.-*-.!^,-'.. r lj>.V;v;f,^:,(;.v^.U;^^;.;ï-, < . • |-:'^.-''^;;^:^.v^-r^:^.-: ms^ ^ m 5 O o P o r*. OL UI 3 o IA o u o ^ °E • • , ^ " • " • •* • ^ T J.v^^Vi'i''-Vw'-:'^ • * T I V~-.-'-L'-. ".••-','iL *fr-''" •'''' ... i ^•:\--^,--VV'^i4^'v^ï~r"'- ... p. - nX--i''-*"*-^'^^'.'^-;^-;->-;--V < _- B B B _ ^ p. - L J ifl-^.A. • • •Hf •• im r r 13.5 Identification of Areas Two areas A i and A2 have been identified as suitable areas for expanding the lagoon r area. These areas have been selected in view of: [a] availability of sand at depths less than Im [b] excavation of these areas will improve hydraulic conditions at the mouth of Dandugam Oya . Area Al covers an extent of about IQ ha and is bounded by the right bank of Dandugam Oya and the lagoon Area A2 covers an extent of 9 ha and is bounded by the left bank of Dandugam Oya and the lagoon. If excavation of one of these areas is solely for the purpose of expanding the lagoon area , the average depth of excavation will be about 1 m. The areas could also be used as a source of embankment fill material with deeper- r excavation depths. The extent required to compensate for the area lost due to the roadway is only 5 ha. 13.6 Recommendations If it is decided to proceed with the expansion of the lagoon area, an environmental impact assessment [EIA] need be carried out as the entire area covered by the survey L forms part of mangro\es surrounding the southern part of the lagoon -. L L [ IÏ-2 i 14. BASELINE SURVEY OF GROUND WATER LEVELS AND WATER QUALITY IN PROJECT AREA 14.1 Objective Ground water levels and water quality is to be surveyed with a view to establishing baseline data for moniioring during the construction and post project phases. 14.2 Selection of Wells After reconnaissance visits, 48 dug wells and two water holes were selected so as to provide representative samples from the area traversed by the CKE, As far as possible sample wells were lo represent conditions on either side of the roadway. In the reach from Mabole to Kalunayake where the trace runs along the Muthurajawela marsh very few wells could be found on the western side and observations were mainly limited to the eastern side. 14.3 Ground Water Survey Ground water levels were monitored in 50 wells for a period of five months with 2 observations per month. Reference levels at each well were established to MSL datum. Chemical analysis were performed on 50 samples during the observation period. Microbiological tests were carried out on 25 samples. Since the period of observation [Oci.ober to March] included both rainy and dry periods, testing for chemical and physical ptiramelers was carried out on water samples collected from 25 wells in November 1998 and the same 25 wells in February 1999, Microbiological tests were performed on 12 samples collected in November 1998 and 13 samples collected in Febniarj' 1999 including the 12 wells from which samples were obtained in November 1998,, 14.4 Location of Wells The location of the 50 no, observation wells is given in Annex 2. u-i I r 14.5 Water Level Observations Water level observations are presented on Table M.I. Well water levels especially those r close to the lagoon are subject to tidal fluctuations. 14.6 Chemical & Physical Parameters Results ofanalyses are presented in Tables 14.2 and 14 3 together with maximum acceptable/allowable concentrations of physical and chemical water quality parameters. 14.7 Microbiological Tests Results of microbiological tests are given in Annex 2. 14.8 Comments on Water Quality of Samples Tested based on Standards for Potable Water 14.8.1 Colour About 70% of the samples did not conform to the allowable standards. 14.8.2 Turbidit> L About 50% of samples did not conform to the allowable standards. 14.8.3 pH All samples conformed to allowable standards. 14.8.4 Electrical Conductivity All samples conformed to allowable standards. 14.8.5 Chloride Ali samples conformed to allowable standards. 14.8.6 Total Alkalinity Only 14% of samples conformed to allowable standards. 14.8.7 Nitrate I:- All samples conformed to allowable standards. L L 14-2 L • -'•••;:»fflLVï( r-u ..-. • Ttarawr •«*«. .••vi.-»»-.-«i 14.8.8 Nitrite All samples conformed to accepiable standards, 14.8.9 Total Phosphates All samples conformed lo acceptable standards, 14.8.10 Total Hardness All samples do not confom to acceptable standards. 14.8.11 Total Iron About 50% of samples do not conform lo acceptable standards. 14.8.12 Free Ammonia All samples conform to acceptable standards. 14.8.13 Albuminoid Ammonia All samples conform lo accepiable standards. 14.8.14 Bacteriological Examination Reports All samples were unsatisfactory due to evidence of recent faecal pollution. 14-3 V iW^:. r Table n.l - Sheet 1 of 2 r M •- 00 V) -* 00 — o: f-1 ^O ^ •"» 00 -H l/l •^ n o I-J r4 00 r- n (») 00 ^ "O o IJS O OO r- 00 r- U- (N 00 O -» o O r- -* 1 3 c; t-^ n o •/ O- o vj d d d d d d o d o o d r o 1 II « d d - LU (S 00 sa fs| rj ri M 00 rt 1 r m f) 3 r- S3 »3 V3 SS r- f w c CS UJ • — 3 O o r- < r 00 o -r r- o o o o o o o o d O e- o d I 1- 1 1 1 1 1 o (/} I --4 in IS r- S3 rt 00 rt z «5 , o i~- r- •o 00 va S *sl o 1*1 o v o 00 O va 00 p LU IXr d d d d d IN d o 0 o d • d • d 1 d d d d r H d O v4 < z 00 lO OO n ca »-• 00 >0 sa rj 00 rj < > H 00 1/1 o 00 os n o I-- ri rt OO n U o »o o I7> o sa 00 ri l/l o -T < o o O so Li. < 5* o •* M CS_ va Ol o d d d d d d d d d d d d O > 1 1 1 1 d d r4 d O. 1- 90 00 »o 00 -3 IN r) rt 00 rt co o oo CS r« o s o >a 00 rj 00 os va UJ 1 = O p l/l l/l 1© sa v3 Ov oi o' d d d d d d 00 UI 00 (S >3 fS rJ rj rt 00 r- rt < co 00 If) in o o CS OO in 00 t *^ LU u •o l/l T o S3 rt Ov UI o ri O •r S3 O o^^ d d d d d d d ri n d d 1 d d d d d ri ri < < VI •'t- H z •o 00 o 00 S3 n n oc rt M o o UI l/l 00 va 00 va l/l "1 1-1 [E. o l/l LU < -* "7 't l/l s» •r S3 p p 1-1 o d d d d d d d d d d d d ri r-i ri d d ri O CS u. t/l 00 1/^ \2 rJ 0^ 00 •N rsi rt rt rt (-1 o n oc r- O o 00 o O sa 00 r- t~ 00 1/1 va V) o •3 00 90 l/l p l/l SO 1/1 os p M OS v3 Ov H d d 1 d d d d 1 d d d d d rj d d d r« CO Ui < LU H cc (-4 i/> 13 00 00 rvi >a r- n rt 00 r- rJ «•. r-i •< o o Cs >3 r- 00 W o T o t t/l -T 00 os rl rt 00 -* 30 < "1 o' d d d d d •I d d o' d > d d d d d rJ z < Q g Z < r4 «1 rJ r4 n 00 r- rt 1- ff' o m vi> < < O' p l/l -t ' va Ov O d d d d 1d ri ri ri o z o; i^- o F- O _J 't 00 ft os 00 T U M U U Ld W LU l/l 00 Ov 1/-, 00 o r-l (-1 00 o cl •* VO o 1- •* T T •tl ri 1^ 1-1 -f o i z L L L Table \iiA - Sheet 2 of :; oor^CT.r--ooJS°'^ ffv 00 r- IN U. rï — *^ *- •»ir)(s-^f^'0S:'0*'C7\r-~ •V .O o v: < 2 »^ 'i o>of^ociois^knr~i»o oom— isSS'^I; O d o d d d d "" "7 — = 1 1 — o t- oo ir "1 0« ff. ao eo ff. 00 cv LU [-- t 1^ 00 ff. £ Hi ff. t ^- 00 (S .O fS OO IIJ o o [-- Vï r- o -T V o c o o o VI o o o O O o o d X 1" 1 d o 1 o d ty> ffv DO Z. oo .<3 ff. 00 1^ 00 fS oo OV IS (S o IS fS E fS V r- r- O 00 T oc ff\ i*; r- -r v^ 0 ffl o 0« n 1 o d ri F— d d d d d d d r 1 d r •*4 Z. > oo ^0 ff. 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V) DO f) ff. *s DO cv UI P > M UJ UJ UJ P U u ï Cl ió' ff. /l [^ 30 CV o rs •T •o o 00 3 o (N rs r-i rs U J« iauj.e iH.i^ r E - qooqoooo qoooooooooooo < O» o o O O ^ O' ó ö ö ö o o ö o o' o ö ó d ö ö d ö o ö ö r V V V V V V V V V V vvvvvvvvvvvvv E =r g o o o o qopoooooooqooqooo < < O) o d 2 d d d d d'óödóöciódcióóöóöö ó ?• u: ^ V V V V V V vvvvvvvvvvvvvvvv o s r > <• < < X noao^ < < E = 9 o o < CT o ö o o LL V V < C _ 9 O < Q: O O O O E Ë 0. a (O V 00 U) < < X < 2 f m ü u, < LU tn u> >• CT < E >- X 0. < o o o o o z z o o o o o o o < >- o o I- Q: < 5 Ê :^ O (O CD S Ul o UJ U, O O f^ o o o X .. V V V V IJ o-I o <^ o ü «J fM o o lO o> CM irt CM Si ei CM CM > O « H ü W o z z> UJ (O Q ?- t < :2 t $ CD CM u> u> U) o u> lO lO tJ _j co O tr ^ _j oj M UI (f> m « <0 00 01 UJ LU ^- r 5 o < o. UJ f-' h-^ I r IS. Concluding Remarks. r After delailed studies the following conclusions were reached : 1. The proposed expressway will have very little effect on the flood levels east of A3. 2. The anticipated rise in 100-year flood peaks due to the expressway is less than 5 cm. except in the case of Mudun Ela where a rise of 15 cm. is projected upstream of CKE and 14 cm. upstream of A3. However the projected rise in flood levels could be reduced by over 10 cm. if the waterway area in culvert No." 3/1 on A3 is increased lo 16 sq, meters. Even under prevailing conditions the flood levels and flooding limes in Mudun Ela are aggravated due lo the constricted passages in A3. 3. Since the anticipated rise in high flood levels upstream of CK.E and A3 are minimal there is no need tor the provision of additional detention areas. 4. The (lood levels downstream of CKE are controlled by the water surface elevation of Negombo Lagoon in the case of Dandugam Oya, Ja Ela and micro-catchments, and Kelani Ganga in the case of Kalu Oya and Mudun Ela. Appreciable reduction in downstream levels cannot be achieved with cost effective techniques. However in the case of Mudun Ela it is recommended that the watenvay area in culvert No. 3/1 be increased. 5. Adoption of 1.1 meters as free board over the 100 year return period flood, in the preliminary design isjustified, after comprehensive analyses done during the study.which included estimation of probable wave heights and allowing a free board of 0 5 meters above the 200 year flood level. 6. The area of the lagoon lost due to the expressway traversing a part of the lagoon is only 0.13% of the Negombo Lagoon surface area. 7. The volume of water in the lagoon at MSL is estimated at around 45 MCM, based on depth measurements. This figure is higher than the value given in published reports (22.5 MCM). The average depth works out to 1.3 meters. b L L 15-1 L tr ANNEX I MONTHLY RAINFALL DATA HALGAHAPITIVA - JANUARY 1965 TO DECEMBER 1998 COLOMBO - JANUARY 1965 TO DECEMBER 1998 KATL'NAYAKE - JANUARY 1965 TO DECEMBER 1998 HENARATHGODA - JANUARY 1965 TO DECEMBER 1998 VINQT ESTATE - JANUARY 1965 TO DECEMBER 1998 PAS VALA - JANUARY 1965 TO DECEMBER 1998 WALPITA - JANUARY 1965 TO DECEMBER 1998 (DAILY RAINFALL DATA FOR TFHS PERIOD IS AVAILABLE ON D1SK£TTE| , _-. #}:.i ^«H.^ - .-.AM- r STöTIOff NflNE : HflL6AHftPi:!/a BlïOiJP r LflT; 7.;;N 'M: Sti.i" ELEV: IIJIJI' tl.Ef1c.ll r P'ecio.Totäi nU m fiiüüetïrs r flissins iiti values are cotJsd a -9.?ff YE^if JflH FEB "!flR JPR ?!flï JW J'JL a'J5 '::• DC? VOV SEC 1965 19,2 105.5 64.3 !aï.' '49.e 126.7 41,3 \i^,ö 233.5 3rS.( 2!8.0 214.2 l?6i 100.3 124.0 133.6 4Sï.i 123.6 1')3.5 6:.? 95.:" 577.5 540.3 192.0 136.1 19i7 71.3 n.b 23;. 3 pl.7 2J4.4 322.2 193.0 125.5 177.' 513.7 331.6 108.0 19tS 49.4 23.3 153.0 ïti.; -9.9» 473.4 354.5 20.7 234.2 340,5 336.1 43.6 19i9 50.6 159.9 64.0 4f!.-: 505.1 i5i.4 7. i ;79.£ 74.2 4i%2 235.2 425.0 1'7Ö 15.5 ;:,i 107.7 3ï=.5 301.6 222,; 245.: 21,3 152.5 Sl^.O 234.0 109.0 1971 33.1} 154.B 135.3 Xl" 7 365.] 395.9 ;7ó.7 2lo,9 480,2 137.4 44.7 159.7 1972 ?.0 .0 105.4 2:5.- 471.1 127,3 78.? ï4.* 293, ï 442.! 2E1.3 163.9 197; li,5 3S.7 149,5 :cC.4 229.7 273.5 126.7 ;:'.- M.' 340.6 414,6 293,9 1974 .0 161.9 115,1 '"j.: 245.! 171,8 231,5 Ï7,i 435.6 17!.: 142.7 202,5 1975 113,9 201.5 190.3 (>i. L r - 490.3 :v5,; l;''.6 ^lÜ. 1 2M,3 253,; 45^7 134.0 1976 '.7 .0 257.1 £ • .' j 95.7 43,5 55.3 13:.5 43.S 557. i 578.0 100.8 1977 11.9 102,3 443.2 3K,: 954. i 1'4.0 30,c l?"-' 86,6 602,^ 233,2 13.7 197S .0 130.3 336.9 ici.; 50;.3 21i.9 It.^ 2".2 210," 305.0 4'!4,3 136,0 1979 .0 119.2 103.4 '£,; 94.8 435.7 73.2 16.8 m.^ 341.? 363.5 46,0 1980 2,3 .0 152,2 23;.^ 203.4 264.7 95.3 17:.i 313.4 316,4 425,5 97.1 1981 Ibè.b S2.6 122.2 171.' 311.7 303.5 93,8 :5i.7 380,0 280.^ 349.4 71.4 • "^T C 1932 .0 ,0 Ir:.- 353.: iü. ;> -.-». I ;3'.' i 10:.:• 405.3 5:S.' 93.2 I'53 il.7 .0 E 154.6 2:3,S 131,7 •40.0 -9,"^ 147.? :':.6 213.1 J9a4 276. Z 242.7 4B7.9 i'^ï-J Jäl.3 201.3 271.2 22.5 lil,5 253.5 440.S 55.4 1985 90.5 257.4 221.8 :s:.: 386.4 4-7.0 121.3 :;ï.8 179.( S6e.6 406.9 125,5 ;_c 19S6 200.4 132.4 71.7 y.i.: 177.3 •.'•.'•: ::2.3 21?,: 24;,: 2*0,0 105.4 1987 6.7 .0 15.2 2;v,, ;6i.7 21:,ï 10.2 i'5.: 133,; COÈ.2 2Sr.9 39.5 19S8 .0 231.! 47.3 475.0 119.4 3ê:,: -ï.ïil -••,-?' -5,W -;.5H -?,9n -9.'!«l JÏ3Ï -9.9« -9.9H -9.'* 19C.i 204.5 352.7 343.') i:.2 132.2 J47.6 403.0 8Ë.4 1990 !68.1 .0 i'S.S ';03.: 35*. 3 i::.i! 13*, e :.3 ?• 1 36^,1 554.2 178.2 * ~ 19?: 75. = IM y:.i :'.'.:: 2:'.: ::-,e '6.2 -.^ • J - j . f ^ r,'. t'. 46,5 Ifl92 12.7 .0 .0 215.7 413.0 217.4 209. T li'.! 42'.? 4*2,8 54.8 1993 Ï7.Ö 3S.7 161.3 22".^ 2B6.é 53,1 185.8 '9.9' 229.0 73d.7 335. s 257.3 1994 175.3 98.9 m.7 52t.2 385.2 ïl." 89.7 J;.: 166.5 792.6 ie?,( -9.911 1995 196.3 Ï.J 189.3 7'J:.- 4ÏC..7 i::.4 llO.i; •'T -', 125,1 44".3 ;2-.3 13.8 1996 34.2 134.5 a.8 2^2.7 Ó4.B i;2.7 168.2 • -e :. 37^« 17', 5 'i.'-l.'i 58.5 1997 .0 29.3 34.8 300,3 33S.8 133.2 29S.7 3:.5 4D1. 3 573.7 456,3 175.7 1999 20,: .0 '4.1 i!t, j 295,9 •:i\l 23^6 2!i.2 257,: 360.4 liS.S 207.9 L i i 3:STI5N HWt : CJtOrEO lü'i O.90N LON! 7?.8/: ElEv: '.3f! ELEHEW' ! PreciD.Istal Hlv if Jtilliieters hissino dëta values i'e titii a; -?.9.H y-»lfi JAfl F:r flriS fiPf ffjï' JJS m SEf OCT NOV DEC 19i5 42.4 105.4 43,7 355.0 609,7 74,7 54,6 J3:.3 227,0 507.2 220.2 227.3 • iï&ó ;u,; 25.7 2;;.4- :J4.5 147.31 135.: :02,: 2S.- 551,3 357.9 2i6.J 6\2 . Hé? 15.S 7;.5 ;;4.ï lC-3.4 5^:.! i5i.5 239.' 152,0 25o.: Bi9.5 3:9,5 3*7.3 1?Ï3 93.3 13.5 56.5 224.7 97.3 270.9 27i.3 47.3 151,2 200.5 285,1 120.6 1 196' is;. 9 76,0 58.4 ;Si.4 5i2.1 05.6 2i.2 212.4 55,7 559.2 255.5 427.2 1970 95.2 95. Ï 170.fi 411.0 602,5 129.3 242,6 27.8 201.9 307.7 476,1 60.1 1Ï71 S5.3 6T.4 35,5 24i.S 195.1 21s, 3 103. i 94,1 366.1 3B6.5 36.é iao.7 1972 15.5 .1) 63.3 157.0 ii', 1 146.1 42.1 6i,3 197.5 i63.2 315.1 163,7 1973 10.5 43.2 IIC.3 254.0 317.5 250.3 9;.? 56.5 40.5 416.5 411.1 244,4 1 1974 .0 143.5 62.7 :i2.1 *39.8 2'1.1 193.5 108.1 210.5 127.2 ISO.5 139,3 1975 20.5 29.2 151.2 i-J.B 293.3 303,5 152.4 63.5 270.9 124,9 530.4 73.7 197i 20.0 .0 67,2 140.6 208.9 S".3 192,7 29.3 527.6 473,2 274.: 1977 ;i.2 :i6.: ;5B.S IVVtJ 750.: 2:8.5 51.2 JI9,7 145.9 871.2 IBB.4 51.4 ! • 1978 6.2 11,3 117.0 15:.3 565,1 110.1 S7.7 27.9 103.1 187.0 367,2 170.6 1 1979 3.2 124.9 77.' 225.8 143.11 241, ;• 111.7 SO. 5 453.7 254.5 466.9 294.6 19SÖ .6 ,0 29,' 223,1 214.8 377.9 35.7 141.5 176.2 451.9 267.0 172.3 1981 ii7.4 93.3 102.5 199.7 441.3 182,4- 34.5 79.9 120,1 193.1 460,2 54,1 1982 4.1 .2 311.3 i08.8 323.7 195. Ü lèO.9 125,6 104,9 186.6 454.9 51.0 # 19S3 .0 43.0 60.3 83.0 356.5 iIB.6 163.1 94.0 291.5 94.8 241.7 223.4 198i 2il.5 179.i ;i2.5 254.0 ^^..O !7t.= 127.8 4.9 339.3 141.3 360.2 24.j. • I 1935 33.5 160.8 :i6.: ?i..3 253.: 31c.' 19,6 111.2 275.7 343.4 244,9 230.9 • 19Êi 344.9 7B.I 91,J 216.3 23'). 9 ir.E !0.5 76.2 128.4 163.0 53.9 203.4 • B 1987 93.4 .0 73.2 179.3 \U,i lie.: 12. C 404.8 509.6 506,5 217.4 136,0 1933 "-0 63.6 lOi.i 135.0 :4c.: 552." :0].S :22 4 374.3 117.9 'ibb.n ?ó.o; 1931 :"5.8 6,^ 14ó,3 332.9 39-, 1 ii • i 138.21 49.11 174.5; 450.1 234.7 31.5 . 1990 182.7 36.' iSi.O 3ii.9 32 J. 3 m.i 206.3 17.9 29,6 374.1 255.8 173.8 199! 73. B :ii.4 142.1 y.'.i 30-,' i21.0 38,8 112,4 353.1 292.7 79.1 1992 19.B 3.5 15i.5 43:, 7 60:,3 218.1 TO." 323.0 216.7 *01.5 78.4 :9': .b 1?.:' Ï-, •• 2:5.3 ^e:.- 5c. ^ 3^. c :-:.4 502.1 ;?s.4 263.0 1994 34.7 117.4 IJ4.4 101.4 480.1 8!,^ 104,7 73.4 370.3 477.9 127.4 30.5 1995 92.3 12.Ï 30.7 374.6 4*6.5 3iJ.3 93,9 135.9 97.11 320.8 405.7 1?.2 rt 19S& 97.9 102.1 291.9 126,5 12«,-! 209,7 206.6 232.3 305,9 239.2 lis.6 1997 .0 70.? I'.J 92,2 J'*.2 jc- - SB7,C 69,2 '17.3 618,7 440.3 138.2 199S 57.9 .i 3fl.4 119.8 :'>.: 2:;.; 4&:.i 127.3 209.0 304.1 267.3 327.6 •I '.; \ -.;-:ii:«a r r SlflTIOH Hm : HflJUNftïflKfl r LflJ: 7.i7N LOH: 79.BSE ELEV: 8.5N ÉLEHENI : Preciojotsl Mly in Hilliieters Kissing data values are coded as -f.fn im m FEB HflR m «av m M m SEP OC? NÜV DEC 1965 9.8 ;;.5 15.0 186.6 m.i 60.6 22.0 331.4 147.7 519.9 226.3 206.7 1966 108.4 H.7 97.2 271.0 108,4 121.2 55.1 9,9 474.3 449,3 213.6 100.7 1967 32.1 j;.3 163.6 86.1 350,3 188.0 )59.1 111.4 339.1 706,6 427.9 62.1 1968 5.0 ll-3.i 63.4 255.8 117,6 253.5 247.0 2d.l !59.4 343.7 2Jv.il 129.71 i9i9 46.0 97.9 fiö.2 453.8 30', 2 66.6 26.6 lo3.0 27.6 7B4.0 2i2.7 345.6 i¥70 118.4 36.9 204.4 626.0 331.2 166.0 201.2 l.i 242.5 476.9 45^.7 '114.5 1971 79.6 1*0.2 93.1 172.9 155.1 264,9 51.S 82.2 41S,e 235.1 -.6 170.2 1972 2.5 .0 66.4 109.4 459.3 86,6 69.2 *8.9 204.1 417.0 &.1 185.7 1973 1.2 '.0,5 186,7 322.3 2'ïi.4 203.6 90.9 44.5 40,5 397.6 2i-,4 215.6 1974 .0 29.Ó 117.5 391.0 258.6 140.6 192.1 91,5 323.8 69.5 i;3,' 181.2 1975 8.4 i;.6 67.1 264.6 255.9 198.? 166.9 66.4 211,8 162.6 40-. 4 163.6 1976 12.4 .0 155.4 236.0 135.3 49.0 75.4 126.0 6Ï.7 465.7 44e. 9 153.6 1977 6,8 3Ü.6 321.7 57.1 781.9 108.2 33.6 118.) 124.1 606.2 256. i 14.9 1978 1.6 22.9 252.3 204.7 581.6 137.4 6.JI 7.6 64.4 353,1 «",4i 42.0 1979 1.3 233. J 168.1 210.6 37.9 247,4 76.0 9,0 307.3 256,5 36;. 1 197.3 1980 .0 .0 100.2 296.6 76.6 324.2 I2.Ö 120,7 221.6 35S.5 222.6 100.7 1961 124.2 64.3 42.0 H2.4 366,3 1B4.4 26.9 100.1 191,6 27f.9 432.4 50.4 1982 .7 .0 148.2 231.9 330,7 314.0 l?o,9 163.6 71.7 2:4.3 ;i;.5 jf,4 198-3 .0 .0 ,0 35.3 15/.4 109.8 76.9 150.0 325.3 136,4 252.3 20i.6 1934 174,6 157.0 196.5 361.0 392,3 151.3 105.2 .5 123.4 268.0 3!;.e 54.9 1935 35.0 192.5 ,62.3 69.2 362.S 263.6 36,0 200.5 91,1 217.9 306.3 127.0 1986 72.1 168.7 146.7 165,0 341.5 48.0 43.5 121.0 152.8 411.9 134,7 213,9 i9B7 25.2 .il a4.9 -9.9« J53.i 153.0 9,8 300.3 404.2 617.i 26-;. 7 35.6 19S8 .0 144.1 148.1 247.1 130.0 229.7 69,4 131.7 322.6 162.4 359,61 51.4 1989 25.0 .0 64.4 248.5 129.1 189.2 140,4 26,61 135.41 253.7 27B,4 50.1 1990 172.3 8.7 140.4 191.7 214.4 53.7 110,9 i,0 11.7 313.5 676,2 173.6 1991 83.2 !0,9 235.7 97.5 197,2 296.3 127.1 33.4 97,3 251.5 143.; 79.6 1992 5.0 .3 .0 100.9 557.5 152.1 101,6 01.3 337.3 335.2 2e2.5 5i.3 1993 6.2 12.1 88,5 206.6 408.2 7ö.7 56.7 4ä.5 260.7 378.0 284.4 204,8 1994 59.9 66,9 111.4 98.7 326.7 90.6 97.9 36,2 32o,0 430.5 311,9 9.6 1995 59.8 12.0 54.6 279.7 557.3 285.8 87.5 71.3 70.41 224.3 442,7 34.7 1996 106.0 64,6 2.7 232.'S 106.3 65.0 lil.8 287.7 211,3 2'2.6 19?.2 164.6 1997 2.0 99.0 33.7 137.4 254.7 117.9 195.5 25.5 340.0 362.3 435.6 121.9 1996 13.6 2.2 87.8 287.9 287.3 181.9 263.5 136.6 174.2 366.2 310.6 313.4 [• L L -»/•• STfllION NAHE ; ËflHPAHfl, HENflSflTHEODfl Lfll: 7.10H LDH: 79.93E EL£V: 9.Jfl ELEMENT : PrecioJoUl Mly in Milliieters ' Hissing data values are coded as -9.911 (Ei^R JfiN F£6 m m m M JUL m SEC OCT NDV m J965 1.2 109.1 IJl.9 ISö.ï 451.8 119.4 43.6 428.0 2%.b 47].5 122.a 182.5 I9i6 60.e 69.7 223.5 27Ö.9 9Ï.B lOO.fl 67.ï JS.S 483.6 384.5 214.7 151.5 1967 73.1 70,0 134.8 94.7 403.0 293,6 184.1 209,3 287.3 846.1 347.8 133.4 1968 25.1 71,1 208.0 267.8 104.2 482.5 377.3 53.1 254,6 142.7 W3,ö 56.2 1969 118.3 121.9 49.2 505.0 49?.6 101.2 5.7 152.7 76.4 438.0 275.2 347.4 1970 ne.8 90.4 148.2 456.5 56S.6 226.4 149.5 20.4 123,8 91&.5 )i:.0 73.7 1971 116.8 72.9 107.4 114.6 275.3 228.8 120.7 251.& 346.9 438.5 J;, • 188.0 1972 2.0 .0 127.2 1J9.0 544.8 134.4 82.4 65.5 277.0 413.6 323.4 217.7 1973 6.2 35.7 145,4 296.7 393,4 238.2 135.7 70.9 25.5 276.6 257.2 239.0 1974 .0 179.5 103.4 361.8 512.3 290,3 223.4 109.3 403.9 72.2 1-JC. 3 151.6 1975 6.5 72.4 160.5 23fl.O 401.5 238. S 138.6 K-1.9 341.1 269.1 026.5 175.6 1976 .0 ,0 124.0 181.9 93.8 71.1 145.1 133.7 53.4 241.2 357.5 2J3.4 1977 54,4 51.4 204. S 223.7 985.7 189.1 15.2 105.6 139.5 -9.9n -9.9« -9.9H 1978 3,1 60.5 21S.5 136.6 575.4 151.7 16.7 20.6 141.8 393.6 465.7 64.5 [979 e. 9 113.9 118.5 147.5 91.0 414.6 80.6 39.6 367.6 295.2 351.4 382. i I9S0 .0 .0 56.4 241.0 25o.2 -9.9« 74.1 :'3.8 206.9 276.7 291.9 183.4 • 1981 180.9 S7,4 82.2 125.0 334.2 292.5 71.2 165.5 283,6 266.6 442.2 52.5 1992 .0 .0 122.7 151,2 346.2 -9,9ft 176,7 335.6 76,0 254.6 457,5 -9.9fl 1983 .0 .0 .0 126.4 5Ö0.4 163.B 160,7 133.2 -9.9n lil.9 163.6 257.7 1984 255.9 205.1 203.9 526.3 437.1 216.4 205.2 3.5 185.0 293,2 235.2 12.', I9B5 71.8 182.5 288.1 155.4 322.5 376.0 26.1 194,2 147.2 393.3 326.5 237.1 1986 202.1 72.1 110.S 164.6 201.4 68.6 27.5 148.2 252.8 233,2 207,3 117,5 1987 16.9 .0 11.7 309.6 183.6 292,4 4,9 284.6 428.9 7|4,4 224.6 26.4 1988 .0 167.6 99,4 2bZ.k 290.9 37.1.6 101.i 29".0 363. • 50.7 i-'-.I iis, ': 1989 16.1 .0 84.B 212.5 202.0 347.3 267.3 61.1 295.1 228.5 :i5.ä 55,6 1990 165.5 .0 172.6 177.6 338.0 112.8 187.4 .0 47.3 357.4 430.5 143,4 1991 127.: 19.1 166.ï 97.5 740.0 472.6 152,0 68.2 96.3 446.4 347,4 59.9 1992 1.3 .0 .0 167.0 443.2 190.9 172.0 53.4 35-.Ö 2ij5.4 26J,J 59,6 1993 2.0 25.2 134.8 175.1 280.3 109.4 95.1 43.8 3o3.4 54i.e 510.9 161.3 1994 69.0 107.2 51.6 160.8 429.2 98.0 93.9 81.6 350.3 427.3 263.4 3.4 1995 107.7 29.7 10.2 556.7 434.J 353.9 143.9 123.1 79.1 213.1 404.8 17,1 1996 123.4 44.3 26.1 148,0 90.9 79.0 134.0 220.1 451.4 -9.911 220.3 !7l.; 1997 24.5 36.2 13.6 136.3 340.9 202.4 176.4 45.1 338.8 388.6 44e.6 2/5.6 1998 45.8 16.8 94,2 220.8 252.4 233.8 482.9 208.7 271.8 352.7 296.6 293.6 I r r STATIÜD nm ; MMM.m (VlNCJTl LfiT: 7.08N LON; 80.22E ELEV: Ilimfl ELEnENi : Precip.Totdl Nly in nilliieters niBjino data values are co(l?d as -f.<)n VEAR m FEB m APR mi m JUL m SEP Dcr NOV DEC l9iS 13.5 211.0 212.7 313.0 586.2 135,6 85. t 437.6 258.3 449.6 160.6 i»;.* IfM BJ.7 79.8 200.3 536.7 196.0 238. i 98. (> 147.8 727.6 444.2 232.2 157.8 1967 9J.0 108.8 263.0 132.5 331.4 461.1 204.4 196.5 222.9 664.5 378.2 172.6 lïi8 M.6 6.7 263.7 235.8 'M.Z 608.8 372.0 49.7 430.9 362.7 304.7 145.2 1969 82.2 60.5 123.8 673.3 307.7 179.1 20.0 272.8 142.3 672.4 265.5 561.3 1970 164.9 208.3 170. B 709.0 332.2 260.3 304.13 60.4 262.7 548.4 329.0 110.9 1971 71.6 137.0 155.6 498.9 394.7 251.3 19?.ip J34.5 499.0 376.1 118.6 287.2 1972 78.0 .0 249. B m:i 573.1 223.9 l?4.i 160.4 316.2 576.1 544.3 235.6 1973 10.4 94.0 381.9 4ni.5 364.0 340.7 335.1- 110.9 72.6 302,7 438.9 197< .0 235.7 JÖ6.1 722.0 246.8 293.8 312. ï 108.1 484. Ï 240.2 128.0' 293.'S 1975 25.5 174.4 276.7 427.4 596.8 330.3 2!'.^ 216.7 4S4.4 332.9 1002.4 184.7 1976 23,9 .0 127.4 430.6 94.6 122.1 167.5 235.3 65.1 526.? 632.4 197.3 1977 26.2 183.8 253.4 42ó.e 994.7 247.3 43. B 283.4 130.6 739,8 589,8 28.9 197B 17.7 181.5 287.6 199.2 617.7 178.6 77. t 74.1 225.2 239.9 588.1 164.8 1979 14.3 176.6 144.9 134.2 185.2 533.3 [ti.i 48.7 634.8 430. J 474.9 409,9 1980 3.6 .0 132.0 5!'. 3 396.5 278.0 1.1: ^ - 169.8 394.3 ;a:.- 490.6 lit.2 1981 102.1 43.4 1S7.8 -'i.'sn 390.0 349.3 iol.5 178.5 423.1 34 J.; 340.7 78.3 198Ï 1.3 .0 161.0 -9.9H 567.0 559.8 238.3 265.0 230.5 647.2 554.9 83.3 1'83 .0 32.3 .5 74.a 2B3.5 163.4 155. / 304.2 477.1 16(1.1 36J.5 502.5 1984 374.9 170.9 507.3 545.5 494.7 311,5 415. t 28.8 190.4 377.* 491,4 95.2 1985 94.Ó 359. Ï 310.1 256.5 576. i 765.9 171.0 279,1 209. U 6B3.' 461,5 305,6 19B6 225.3 20i.5 153.1 445.9 168.6 134.8 92.2 177.4 291.2 326.2 243.6 273.7 1987 51.8 .0 68.4 • , 409.8 321.6 347,5 J.; 418.9 440.0 863.9 401.5 75.2 1988 1.3 366.9 210.1 575.5 298.2 473.2 3«*.i 475.0 607.5 J 22.4 563.4 24.7 1989 )0.7 .0 137.7 H3.9 351.5 624.2 431. i 69.8 299.'; ^v5.2 jji, J r2.- 1990 164.1 79.0 459.6 IB5.2 364.0 207.5 304.2 10.7 63,0 -9.91) 683.8 226.1 1991 128.4 2.9 329.3 314.1 513.1 451.0 18Ö.1 68.6 61.6 300.2 348.3 94. e 1992 6.3 .0 5.6 181.6 188.2 282.2 268.1 131.7 380.6 561.5 505.5 140.3 IWJ 8.1 76.0 148.B 299.1 422.7 334.3 15a, 2 120.0 33^,* 677.2 464.1 207.2 1994 64.6 180.5 122.0 156.7 379.3 170.5 148.3 94.5 226.6 689.0 520.2 3.0 1*95 161.5 42.9 42.Ï 558.7 561.7 405.0 *(..4 271.3 106.9 525.5 474.5 33.0 1996 87.5 96.2 81.1 273.1 126.3 377.9 150.3 177.9 6lS.b 319.0 152. Ï 74.6 1997 4.0 53.5 65.0 232.5 502.3 165.0 466.0 109.S 609.6 903.6 633.6 m.^ 1998 56,1 .0 73.9 329.9 456.1 272.9 527.3 275.0 486.1 3 • Hf- L m L t -nK-n •-•»;"r-,M L I STfllIOJi NflH£ : PUSYflLfl Lfll! 7.15N LON: S0.13E EL£V: IltllJ.I ELENcNi : Precip.IatJl ?llv i" Bilhaeter; fliïsifio data valjs; are coasa as -ï.9.^ mfi m FEB HAR APR «AY m ! l?i5 15.2 160,2 IÜ.5 iS7.5 677,3 143.5 54,3 460.6 240.5 370.3 158,6 136. ï 1^64 138.0 99,3 2::.5 5M.5 97,7 •i.'in 81.4 81.4 605.6 336,0 26i,o 135.B IW 82.1 6É.0 356.0 221.5 243,7 354.8 173.4 105.1 199.0 732.0 323,5 172.6 l%i il.5 26.1 ISi.O 277.2 ioe.2 S1S,0 445.0 51.3 322.3 472.0 233.3 61.e 19t? 108,2 250,6 63.6 5i0,8 677,7 117.2 I5.S 146.3 58.5 536.5 205.7 577.4 I!70 292.4 164.8 n5.^ t^iS-l 568.6 32!.: 334,0 40.6 195.4 695.3 312.5 101,2 1971 82.7 192.9 116.' 27B.5 366,9 294.9 133,4 270.4 459.: 281.0 6!.6 313.S .1T72 12.4 .0 142.: 211.5 536.3 108,8 131.3 88.2 377.9 552.7 55;. 9 224.9 :m Ï4.4 100.1 223.: 3^2.1 240.5 339.: 204.3 1*3.9 58. B -9.9H -9,90 -9.9.1 IÏ74 .0 215.6 I9C.5 753.6 4'i;.5 225.5 297,1 116,3 536.9 58.6 !24,0 316.0 1975 56.0 137.3 141.6 411.8 443.6 275,7 135,8 164.2 313.7 331,1 683,4 95..; i576 9.7 3.0 145,0 253.7 113.3 BS.7 152,9 131.6 73.5 563.0 401,3 134.3 197? 19.1 172.5 262,5 403.7 95Ï.0 219.6 :7,9 190.2 H2,5 799,7 476,9 84,6 1973 6.9 137.5 302,9 178,6 567.2 146..^ 53.9 46,3 106,7 326.7 614.3 124.; 1979 2.8 176,3 134.9 131,3 SS.i 53.-,' 116.1 30,6 -',91 522.0 449,: Ï9,v I9B0 .0 ,0 95.9 3i0.6 2:3.4 233,5 160,3 175.7 167.1 283.2 357.6 127,3 198! 231.0 31.3 91,: 151,9 38a. ï 30!. 9 64.5 134.8 370.2 393.8 296.6 105.9 19B2 .0 .0 175.9 M9.5 377,7 4!:,e 137.7 315.6 Hl.5 541.2 534.5 137.7 1983 .0 /) .(1 1 ur • D 2£-.; 2^:,; 63,6 iis.5 :07,5 j2^3 34t,; 274.s i93t 23Ï.3 314.6 374.7 390.0 326.1 !si.; 44£. 1 30.6 54,3 181.2 346.5 36.4 33,4 1965 51.S 226.7 2t3.5 ir.s iJ 1 .' • .. 331.7 62,4 105.3 3?1.2 40'. 5 163.0 1986 255.9 147.8 153.5 291.7 15!.- 53,7 ',i 92.8 241,0 291.0 155.3 91,9 71 n 1-^ •; 19S7 10.5 .0 254.' 1 . k - 2*5,- _^ 1*4.3 21S.5 749.5 203.1 15,5 •1' ! 1733 .0 233.2 92. c 29., 3 i* j '-^ 2<;,: ^^ . j _ 37i,i 30.: 5y:,ä 3:;,^ 1989 20,1 .0 90.7 -9.9H 17:.7 -9.911 -9.9» 30.0 64.1 J96.9 302.9 60.4 199D 239,1 20.4 111.9 J30.3 229.2 12i,5 92.9 ,0 ,0 314.3 633,4 165,0 J991 1S6.0 13,0 136.0 150.5 Ï74.1 354,0 170.0 33,0 99,0 463.2 376.0 30,0 f 1992 .0 .0 253,0 35:, 5 303.3 424.2 314.9 267.1 459.1 322,6 116,0 1993 .0 -9,9n 136.3 499,9 4::. 2 176.5 227. b 75.6 233,6 523.5 450.3 234,1 1994 113.9 110.9 90.: 261.2 2^:.2 9i,; 110.6 110.9 193,9 556.9 474.Ë 4,1 1995 103.7 lÖ.E 56.S 732. S M;,v 338.^ 144.6 203,5 135.3 433,3 472,4 ,0 1996 69. B 130.4 97.: 317,: Ó;,2 186.6 1 1 J i 0 174,0 459.6 -9,9n 1 = 7,1 100,2 1997 .0 60,3 11.4 1!5,1 319.4 123.9 403.0 S7.0 40ï,4 687.0 373.0 366,0 1998 29,0 '.C 35.0 203,2 3:-', 4 275. C 322.5 291,0 349.3 405.5 269.0 311.0 .1 - "r, - . .-."TPV r r r STATI3») NflftE : K^L-ITA LiT: 7.27N LON: 80-05E EL:»;: Uttm ELEHENT : Precip.Totjl HIv in Hiiiiieters Hissins iiti vslusi are :odsd as -?<9N ÏEflR JAN FES HAR APR HflV JUN JUL AtJC- SEP OCT NOV DEC I9éS 10.4 44.9 100.8 280,6 333.7 136.1 60, i 356.4 187.5 380.4 163. i 176.1 •jf- - 19Èi 32.7 34.B 101,ó 341.2 135.1 123.2 56.S 524,3 4:4.7 16:.: 135.4 1167 58.3 119.8 191.0 173,3 163.6 349.5 109.4 ï3,o; 157.0 596.7 359.1 244.2 ï%5 3.7 34.2 141.8 204,7 91.1 23-, 6 416,5 • V 211.7 27i.9 70.4 21.3 IW 55.9 88.3 32.5 145.3 344,7 75.3 7,6 104.3 54.2 331.0 135.5 318.7 1970 56.1 101.5 114.2 (42.8 431,0 373.2 143,9 T e 144.7 563.5 331.0 110.i 1971 70.7 137.S 124.9 2Ï0.4 233,: 341.6 107,! 39. C 422.4 2". 9 t.v 137,4 1972 .0 _fl 101.4 179.2 413.? 7:.0 03.£ tl.b 278.6 337.01 205.7 109.0 - 1973 2.7 123.0 275.8 328.9 203.9 24*. 5 90.3 34.2 359.9 444.9 185.2 1974 .0 123.! 82.9 442,1 177,=i 124.5 229.7 flo.:' 297,4 165.3 223.! 234.8 1975 49.0 122.9 112.3 224,9 516.0 224.0 143.E !?6.: 248,7 237.0 573.21 126.5 1976 16.3 - 3.3 154.B 326.0 82,0 36.8 41.S 127,3 58.5 417.7 535,3 248,3 1977 .0 18C-.7 245. B 208.5 824,3 164,9 33.3 150.1 B5.7 545,9 235.4 5.1 1978 .e 19.1 154.7 99.1 4S9.0 155,0 13,3 23.4 49. B 121,'' 459.1 103.1 1979 53.3 102.0 73.7 104.3 B5.: 331.1 ;1.2 12,0 377.4 312,4 317.2 111.3 1930 .O .0 74.4 138.1 15S,3 54.1 9",4 196.4 -9,9« 143, i 47.7 i'ei 37,6 32.3 21,3 73.4 BC,= 41.5 as. 2 131.5 123.4 221.3 345.7 43.3 1937 .0 .0 165,2 137.3 284,7 422,2 193.1 273,4 30.2 354.7 451,9 49,1 193; .0 .0 .0 75,5 171.0 257.5 n'.o ï7,7 236.6 -?.ÏX 192. •: 112,7 1984 2Ï0.3 259.0 332.3 453,7 530.» 134.^ 175.7 ji." 190.4 209.31 472.: 77.5 19S5 43.5 176.9 167.7 ::6.' 359.3 274.- ''IJ 125.1 124.0 ja;,9 3or.s 79.7 !9eó IIO.B 44.5 65.7 227,0 170.6 8:,3 ;r.2 92,1 142,4 249.7 253.2 4Ï.2 1?D7 !2.7 .01 6.4 " -291,1 184,4 216.4 32.8 152.5 1B5.6 453.8 232.! -9,9H "T3 ,' •"" 7 21;.; i':: 1 C 233.:: -3 1 ^ :33.. Tl • •• :"5.E 301.' :è;.' '? ' 1989 30.8 .0 69.4 -9.9M -9.911 -9.9fi -9,9n -9.9(1 -9. il« -9.9fi -9.911 -r.^H 1990 H.l 7.1 115.8 93.9 257.5 34.7 153.2 .0 14.5 346,9 554.9 127.3 1991 50.5 46,3 205,2 139,0 246,2 414.4 -9.9N -9.9H -9.9» -9.9H 130.0 74.9 1Ï92 ,0 .0 ,0 98.4 252.ó :7".6 148.9 52.9 355.« 379,9 360.6 74,9 1993 10.5 33.3 138.9 223.7 255.5 34.5 59.3 53.6 206.0 379,1 230.9 234.6 1994 42.2 84.0 99,0 228.1 263.5 49.9 101.6 23.9 77,1 421.2 28*. 4 .0 1595 117.7 4.2 97.5 451.0 303.2 249,2 53.1 107.3 31,4 293,1 492.8 10.1 1996 58,1 126.2 3.5 345.2 35.0 83,7 76.1 121.2 246.7 160.5 208.6 105.91 1997 5.4 15.8 38.6 291,8 232,9 86.7 321.0 6S.8 375.4 624.4 535,5 142.4 1995 48.0 .0 57,6 131.0 280.0 210.9 204.7 200.9 305.9 344.8 267,7 201.4 r L L L ANNEX 2 BACTERIOLOGICAL EXAMINATION REPORTS LOCATION OF WELLS 12 No. WATER SAMPLES COLLECTED ON 16/11/98 13 No. WATER SAMPLES COLLECTED ON 23/02/99 • .-,i-' fi r r LOCATION OF WELLS W,l On l''iumofrfromPeiiyagodaonKandyRoadBridgetoieft There is a temple. Well is in Temple r W,2 On l" tum off from Negombo [i.e. at l" culvert] there is a three wheeler garage Dugwell islhere. W.3 On Dutugemunu Mawaiha well is just opposite ihc Assessment No. 279/A, l.'JOO km from junction on Negombo Road. W 4 On Telangapatha RHS of road, Wanawasala Road about 500 m before (he Meegahawatie Bench mark. W.S On Wanawasala Road, after crossing the proposed highway 'ï^ permanent house Well on RHS of Road. W.6 Turn right just after railway crossing Hunupitiya on Dharmaramaya Road. Well at Dharmaramaya Temple W,7 Cross the railway line from Temple and find the bathing well. W 8 Hunupitiya Station Road LHS. Last house before railway line. W.9 Along Waltala Road from Hunupitiya after passing the WatlaJa Court House behind Shan Agency Post Office. W 10 Pass Enderamulla railway crossing about 300 m RHS of road, well at 633 A. W, 11 On Duwa Road before Dias Garage, Waltala after crossing the proposed highway, well is about 100m from centre line on LHS of road. Just at gravel road junction. W. 12 After passing DIas Garage I well on lane, L W 13 Turn left on Container Road before proposed highway crossing on I" house RHS House No. 777/5. W 14 Turn off from Gunesekera Mawaiha before filling area after passing marshy area l" house (under construction] Well on RHS W. 15 On Gunasekera Mawaiha before filling area RHS of road al the Dancing School. W.I6 After passing the centre line of CKE on left hand side lane, house No. 400/18. L W. 17 Waltala on Percy Dias Mawaiha l" well on LHS. W. 18 On St, Saviour's Road. Weligampiliya, Elapara. W. 19 At Tapowanaramaya Temple. W,20 On Usweiakciyawa Road RHS last house before filling area. W,21 Turn right from Uswetakeiyawa before bridge. Well is on RHS l" boutique. W.22 RHS of Wewala Cemciary 1^ house. W.23 Opposite house No. 68 on St. Mary's Road, Mabolc turn from Negombo Road opposite Ragama Road, W.24 On RHS last house before bridge on Pamunugama Road, L L t j W 25 On RHS Same Road on Dammika Hardware Stores W.26 On Lankamatha Mawalha 1/95. W 27 On Amunupiijya Thoiupala Road, Auction land. W.28 On last house on Morawatta Road W.29 • On house before (asl on RHS on Thoiewatie Wcwala, W.30 Just after gravel road from Wahiliyagama i" welJ on RHS Ncgombo Road. W.31 Ai last house on Pathirana Place. W 32 After bridge on Mullewatie footpath l" well on LHS, W.33 Ja Ela Bund Road 2"^ house after passing Heen Ela bridge. W.34 Tudella Ganuneda para, W.35 On Negombo Road on LHS I'weil after 18/3 culvert, W.36 On Ranasinghe Road. Indiritiya. W.37 No. 40, Jacob Mawalha W,38 At No. 73, Gammeda Para ai AinbalanmulJa. W,39 First well on LHS after 18 km road. W.40 After Pamunugama Road l" well on Negombo Road. W,41 I "Lane, 2 house pit after Wahitiyagama bridge. W.42 Negombo Road i" well on LHS after Dandugani Oya bridge. W.43 Gammeda Para Junction LHS AmbalanmuIIa W 44 Well next to Co-operative Wholesale Shop. W.45 Weil opposite Seeduwa Police Station on LHS. W.46 Well next to Priyantha Holdings LHS. W 47 Well on l" Lane before Airport Gardens Hotel [at Siriweda Medura] on LHS. W.48 Well on IJiS opposite Singapore Garden. W,49 Well just opposite the bus halt before Airport Junction on LHS. . ••. ,jw- r r r N:iliu[iat Water Supply & Drainage Uuard CLNTRAL LABOKATOKY Tl l.AWtLA RÜAÜ. RATMALANA Ddie : 199. WAltR QUALITY REPORT 1. Laboiatory Sample No 2. Dato Et Time of Collection 3. Sample Collected By; 4. Report lo be Sent lo : 5. Source of Sample ;, 6. Olher Details : PHYSICAL QUALITY Max. Concentration Acceptable /Allowablo Colour : 5,30 Turbidity ; 2/8 CHEMICAL QUALITY pH : 7,0/8.5-6.5/9.0 Electrical Canductiviiy : 750/3, 500 fis/cm Results in mg/1 Chloride (as CI) 200/1200 Free residual Chlorine (as CI2) 0.2 Total Alkalinity (as CaCOj) 200/400 Free Ammonia 006 Albuminoid Amonia 0.15 Nitrate (as N) 10 Nitrate (as N) 0.01 i. Fluorido (as F) 0.6/1.5 Tola! Phosphates (asP0 4) 20 Total Residue 500/2000 Total Hardness (as CaCO») 250/600 Total Iron (as Fe) 0.3/10 Sulphate (as SO 4) 200/400 This report is issued for the information of the client. It shall not be published in total or in part without the written authority of the General Manager, National Water Supply & Drainage Board. This report is limited specifically to this specimen- Lab Assistant Chemist •'iwi National Water Supply & Drainge Board •oioS CnamM at. oo aoea atj&io 635281 -3,635247. 163448 8 635883 Qu. ffiu I ]4 Vice Chairmaairman J General 0'lico 635887, 635996, Ml. Lavinia Chairmairman J ") P , 0 Box J aßxscnSetC Tele« ;214B2NWSDBCE ödes» 636449 Fax : 636449, 6371 78. 635999 ^{7^1il«UJTAiCir. General Managlaqeer J Galle Road, Ralmalana, Sri lanka Scdtroc(foOOo 1 tJ ff" I 199. My No. > Youf No, J CENTRAL LABORATORY TELAWALA ROAD .RATMALA-NA Date 199d/il/l-ó Bacteriological E>-,3minatiDn of Water La.'z . "^.eg . No 5r-,..'?S/420 BoLtrce D"f Sample W - 3 Ds'^e ^'. Tice '^' Col l^iriof. J7~^3.'ll/.l,T St -VC.f.> A,M. Tate .^ Ti.-i-? ^•" .'lic-e •. ;•, i-- ..sj i-^€ 'i: i •> -iv >=.: r A, 1, RSEort ReQi.-.i'-ea 3"' Mr .G.E.M.Gor^ez Team leader, E . C, •_ Results;- TeiT 'De'-e-ijre -^c Tote. 1 i^e1:e^o^.r.3^hl•r Eacteri;-. oer 100 ml o-f Tor. i'vïufT.ero'-is to count. Sample Jt 34.f Z. Tot?.l .-iumb = r CÏ &i 1 cypes of M3 e thai-. .'-100 col if ore, bi*.ct&r ia o -erert \r> J.OO":il of saTüie ft 37 C. Mumber cf E ^c Ti ir .1 OCT I c' f ?.'-tO. sam:.'lEr at 44 C, Remarks:- Unsatisfactory, There is evidence of recent faecal pollution. This report is issued for the information o'? the clent.It shall not be published in total or in part without aathcrity of the General Manager. National Water Supply 5< Drainage Board.This report is limited specifically to th.s ^Ps^,'-^^^^ ^MARAKOON MINISTRY OF Hg^4|^?§^g§^i^^EL0PMENT TÊtAWAUROAD ^ Chi^f of ...ab . ;ervice3 u kVvt 1 k ivt». r dD^ss) d(3 e3©ö]^£55 COD dcDoDeosa i-s^^ögcs ^ r , —J.i-J r National Water Supply & Drainge Board - CD caioffl Ä DO. OOOO \ tnSeeto e352S1 -3,635247, 1- «•""""" 1 63 635883 Chairman J Vice Cfiairman General Office 635887, 635996. =. O.Box J Mt. Lavin ia • a>eiau^£ajß Telex : 21462 NWSDBCE ts»i axi. - 636449 Fax : 636449, 63717Q. 635999 General Manager Galle Road, flalnialana, Sri lanka ( «.ujei ff™, f 199. My No. J Your No. > CENTRAL LABORATORY TELAWALA RQAD,RATMALfiNA :>-..tB Bacteriologie al E^xamination oi Water . t-i - 5 Wel: at ^'O. 'ly/b Teiangapatha ;-:3ad • l?^~/:.I '1^ at .i:..iC- A.^1. iV-^'i '3 l i^ =>-; 0?..:.5 A.M. Mr.G.E.M.Gomez Team leader, E . C. L Resul te:- Ter.-;per^.tw "E i 29 C L Bac ctjr -.0 ;>••;• '-O^ü "^i". Jtf ; Too ^iu'neroLis zn CCUHT:. sample ^"•: ".'^ ? C . Tctal r'-in!.;:e-" cf e.'. \ t/pes ov Mo^-e thar 1100 coliform :-sctery8 Dr^ecent in lOOmT cf =äiT.c).-= st 57 C. Number c-f £ :;cli iri lOOmi '_vf. : 240. sam3:.e at "^4 C. t: Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for t^e inforn-iation of the clent.It shall not be published in total o.'- in part without authority of the General Manager., National Hater Su'^ply & Drainage Board.This report is limited L specif .ic&l iy to this specin^en . H. A- K. AMARAKOON r~) ^^^ [ MINISTRY OF Hgl^lg^^^^^^ELOPMEf^^^ HAT\Ö'{iSii^W^'m>9fP9ii^nfHf>im^ZB0Mo)^^^^^ of.Lab.bervice. [ TELAWALA ROAD Tl National Water Supply & Drainge Board •oca CO dSlofl 6352B1 -3,635247, CK. oa eoco 634488 a.u tnnitun | 6358B3 «. Qu St\i. C half man Vice Chairman ) General OHice 635887, 635996. Mt. La vin la P. O. Box ]" Telex : 21482 NWSDBCE 636449 Fax : 636449, 637178, 635999 0!>sod. QiJ ^uiwiTtwiar, General Manag' e1 Ralmalana, Sri Ian I Galle Road, aoer ' SoSQoaa 1 •^"ft eeWTRflL LABORATORY 199- My No. I "^T^fiWALft ROAD.RATNALANfl Date Subject : Bacteriological Examination of Wati Lab. '^^^.g, . I'^o I Sa::.'?'3/42'? Source of Sample : W - IS We' 't at Totunola i~"'f.d, tJel isar?, , Racama- Date Ï TirT = 3-f J^c'. 1;TL li^n Date Si Ti'T.e OT fteceij-. in Lao : ;.99i^:/.li/17 at 09.1:. -i. r. Kepof": RRC'-I:. r"??-:; By Te?- leaTi'^"^, E T . L - Resmits:^ TeiriDerature ?9 Tct." I HEterctrophj c Sac ce -.i.a per 100 ml of Too ^ume.TuF. ^o "3i.snt, sampl» at 34.5 C Total nuir.ber of al 1 types '_•* CDliforn bacteria orecent tr^i Mere thar li^-O, iOOml of 5a.T)pl& at 37 C. NLimlL'er of E col i in lOOml o ' 240. safnple at 44 C. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the clent.It shall not published in total or in part without aathority of the General Manager, National Water Supply ic Drainage Board .This report is liinili specifically to this specimen. * u A K AMARAKOON ^ /2w«-^^rr:^ "' fiRNioR CHEMIST l;5i.-----^r::^-^-^''" MINISTRY OF HOUSING M^A,r5:s^^ïM^^^ "Water-Every Drop i3Rreti*)iieO"*"**''i J .^.'ir^siai r ^S.-i r National Water Supply & Drainge Board eaaS IK. oa cjoaa i Ou.«, ^0^«-^.^ 635281-3,635247. ßatfütv 6344Ba 635863 fi Ou- S'ni \ ' 1 Vice Chairman ) General Ctlice •) 635887, 635996. Ml. Lavinia lan ! Telex : 21482 NWSOB CE Chairman tWesm 636449 Fax : 636449,637178,635999 P.O.Box J ' } Ralmalana, Sri lanka Gene rat Manage Bcao««£E'i''"R'^'- LABORATORY t^tEfe«l4ALA R0AD,RATMALAr-ÏS9Galle. Road, Your No: J My No, Date Subj eü t Bacteriological Examination of Water wS.b.Reg . Ne Bäc/^B/42*i 5=urce of Bampl^ •A - 21 Weil at Date S< "^ime o-f "cllectJon 19^8/11 'léj a-- :r-,0^-. P.i-1. Date 4/ Tims cf ^sceipt i,r- ^.-t. ..V93. 11/1.7 ä-. "5 X5 A.>-. Repart Reauired By .•^r , 5. E.>;.S3r-: :. Results:- • •: :•:.= - =. ur." Total HBteroti-cpT:,c 3acte^:.a v-^r- lOO TT.I C?- .'i'.rerou? -o cnuf^. saTiple s*: 34 . c C Total n-imber of all t\-prs cf col iforn". bscteri-a precrsrit ir icr^ thsn llOO. iOOm' of =3fnple st 37 C, Namber of E coli ir. iOO^ril of Ml' sample at 44 C. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of t.^e clent.It shall not ti published in total or in part without authorit/ of the General Hsnager, National Water Supply 8, Drainage Board.This report is limitec specifically to this specitTien. H, A. M. AMARAKOON SENIOR CHEMIST MINISTRY OF HpAÄ^^dÄ^if g^BltaL "Waler - Every DfBaHAFWjtlöVsROAD "^ RATMALANA; •,-rtzsr=T^.-s:-^ _..•• y- — :- :-r-..'.:.'a7.^si3Bes zS:^ National Water Supply & Drainge Board CooswA 635281 -3,635247. fi^Mu^ l 5344S8 tu awiiuiu,*. 1I 635383 635887, 635996. Chairman J Vice Chairmanan J General Office ) P. 0. Box Ml. Lavinia TetBX : 21482 NWSOBCE sqox). 636449 Fax : 636449, 637178. 635999 Geneial Ma naga J GalJe Road. Rdlmalana, Sri lanka 199. My No. J 'JTRAL LABORATORY TELfiWALA R0AD,RATP1ALANA Subject Bacteriological Examination of Water Lab.Rsg . .^c Bac.'9S-'4::'" Source of E^.Tiple W - "It i^ei ' a" Paavjnuga.-na ROSG ^ Date t. Ti'Te of Col lee tic n 19^1/3 1-i-. At 0">.F;5 (-•.'^. Date & Ti.TE- c-^ Receipt -.r l??a/i -./.-.T fir ':.^.Xb P-.-'\. ~:s.:iO -1 Rea-. i .'• 'Jd Bv rr (^..H./l.tTcfiy;. 7eA~. l-TTa je-r, 8.e.5'J.l.t5.Jr Te.Tiperat jre :: -.-:•.- .-,eL = - i:. -^ D,.--..- Êac teria p'?!* 100 T-1 sf Toz- '^>-'mei-oas tc - our. t t=.ample at S'^ . 5 C Tote, 1 riutr.ber rj-f all tyoes nf coliforrr, bacteria precent in «Dra nhan iiCO. 1 -'td-m 1 of sample at 37 C. MLini t:e r of E coli in •. OOn 3 o f r4.:'. sa'Tiple at 44 C. Remarks: - Unsatisfactory . There is evidence q^f ^ r ec en t „faecal pollution. This report is issued for the information of the clent.It shal] not be pub 1 ished in total or in pa^-t without authority of tne General Manager, National Water Supply t. Drainage Board -This report is 1 imite; specif ica 1 ly to this specimen . /J H, A. K. AMARAKOON „ ^ J,u<^ MINISTRY OF 'Wa^KTf&M>CK Kkapäs ßta«106ironAiMAO£ fOAfUtief of .Lab. Services TeLAWALA ROAD r r National Water Supply & Drainge Board oo»ä CO oonod sMda 634488 B.LI »imuni/^ } 635083 1 635281-3.635247. °'^'Tl Chairmalirman j Vice Chaimiaairman j General Office ƒ 635687, 635996. P. a^ei")Box J " Mt. Uvlnla Telex : 21482 NWSOB CE OcMon (ifl«nBiu)t,ini(i ) 636449 Fax : 636449, 637178, 635999 General Manager J Galle Road. Flatmalana, Sri lanka 6ocd CfooQ «IfV' ^ ff». I My No. i Y^Jf^gEfJTRAL LABÜRATDRY ^^3- TEUfiWALA RQAD,RATMALANA Date i99e/.ll/2é) Sub j a:t Bacteriological Exömination of Water Lab . .-;pg . !MD Source of Saniole W - 38 i^sll at Ganrnu.l la Road, Amb?. lanmul Is SeedLi-^a . Ja-,e i-. "iriE -i Zoi ..??:: cic-n i9'c-/ii/ió ät 05 j--:. ^.^•. Tate '.•• Ti-n-3 o-f Rereirt ir. Lab 1995/11/17 ^t 09.:.5 A.l^. F . r;. L . Temrs-"?.tu.''= : 29 C 0ac-ceria p;?^ lOO ml cf I Ci3 Ni.imercus to coun;. san-pie at 3-+. 5 C Total PLiiT.bar of all types of coi if DT. bacteria precent ir ^'o'•e then 1100. lOOml cf s^iTjple st 37 C. Number of H coli in lOOnil of 240. sample at 44 C. [• Remarks:- Unsatisfactory. There is evidence of recent faecal pollution• This report is issued for the information of the c lent. It shal 1 not b.- pLtblished in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is 1imite L spec ificsily to this specimen . -*ft,VCOO^ MINISTRY OF HOUJ L •Walt »[^^OwJ^ I •..ijeii-.'.,.-: *»£üï--«-.,..v.*«(a;''i:^ ^^••.'•?.ïi£asmu I Mt Iccfco • >;mJ t'ty I National Water Supply & Drainge Board CDOtsna tu.» crixDo \ iséBeo 635281 -3,635247. I 634480 635883 ß Ou ^ 14 «luiOiii«. 635887. 635996. Cha.imiai n J Vica Chairman Gene rat OFTjce ) P. 0. BOK 1 Ml. Lavinia TeleK,2t482NWSD8CE cg4o;ö. 636449 Fax : 636449. 637178, 635999 «nu;) tSfi. 'General Manager Gälte Road. flatmalana. Sri lanka SoSCMOO ] eoSvaa 1 199. My No. / You( No, I CENTRAL LABORflTORY TELAWALA ROAD,RATMALANA Ds te Su reject : B.3Cteriological Examination of Water L_e D.Reg. No SjLirce of Sample ! k - 1 t' •! 1 at -'el iy^coas Keecradaramsye r - Ti;.! 1 e C^-'-s ?• T-.fr,e o-f :'c' =:t;.o- ; l-"93/.ll-'16 at 10.-O A.M.' r Ätü ?( Tire zi-' Rscviis" -.r -.ad : i-'93/il/17 at 0-/ ^5 A.M. ; Mr.G.f^.M.EofT.ez Results;- Töfra^t-a-.. '-'= :? c Total ^:e"ero^r-opfic 3ócie^ 1 •; 5er .tOO ml a"* Too Numerous to count, sample j c 3'^. f C. Tctai ni..rfttr'ê-'" of all types of 1100 < colifopir bs'.teria prece<' Number o.' E coli in iOO-.iJ of 9L-. sample s'^ '54 ", Remarks:- Unsatisfactory. There is evidence of recent faecal poliution. This report is -ssued fo' the information of the clent-It shall not be published in total or zn oart without authority of the General Manager, National Nater Supply & Drainage Board.This report is limited specifically to this specimeW, A. K. AMARAKOON SENIOR CHEMIST MINISTRY OF HOUSII^MerÄfWW^Wftfflm^KCÖPNmNT'T^ UA^,-^-'^''-'}^^ ^TELXWALA flOAD Chief of .Lab.Serviccee s R ATM ALAN A: ^• r National Water Supply & Drainge Board ^"Ä^ VBI" \ 634466 635883 635281 -3,635247, r irman J 635887, 635996. Cha Vice Chairman General Ollice '1 ^ 0 Box i Ml, Lavinia DlSjOlfflOOO Telex:21482NWSDBCE is>s on. atesra 636449 Fax : 636449,637178,636999 ' 1 Galla Road, Ratmalana. Sri lanka General Managaoeer / 199. CÈMTWAJ LABORATORY MyNo. TELfiWALA ROAD,RATMALANA De.ts Subject ; Bacteriological Examination of Wat^r Laa.Reg . ^'C : Ba(-/ Source of Bsr^^Ie ; W - 9 Well at No.3? Station Road, Wattela. Data ^'-: Tl,:? -' Col leci-Liran : i990'Ll/-.; =..- li.10 A.S. Diite f Tir= .:; - seceip-^: i.n : iq?3/.V'./i7 st 09.15 P . >1. r.e3or'L .';ac u - :• • = •.' By ! Mr.G.E.M.Gomez Team leader, E . C. L Tem^iere.tU'^e ; 29 C Total He'csr^nrDoM': 3s-ia.'ia per iOO Til c^ : Tco jV .i.TieroLiB to count, sanpie at 3-1.5 C. Total nudber of all types ei : More than 1100 ccliform bacteria precent ir l'l'Cm'i of safTiple at 37 C. Nu-nber of E coli in lOOml 3f : 93. ^Atfiiitlit^- at 44 C. Remarks:- Urnsatisfactory. There is evidence of recent faecal pallution. This report i= issued for the information of the clent.It shall not be pLvblished in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is limited specifically to this specimen. MINISTRY OF HOUSINg JM^tf öeWïa»I'MBi;(l^f of.Lab.Services "wSAr'DB«.y^laS>rÄPAT0n^yl i...^'t..-.-z : ..-•j-rv^Jfi. 'yy?^^*^ .j._.-T, ,, ^. ,^_ I SMitltel» • ^oioM^I National Water Supply & Drainge Board s^ pswfl 1 gQnaxsSiOT *"""•"" [ 634488 635883 O""«/ J(Bi Date 199H/ . . •• .•.- Bacteriolagicöi Examination of Water ' I i • Lab.Ret. N'c Source of Sample •i • i=. Gona=e ..-re Ms-jstna. VJiï' 1 ï: •:•.'" ^ , -Ja'. r. =• 1 a . Dête >••. TirjE o-f Cv "..' ec - i":;- : i--t;/_*'' 6 a-: ;i.O-:i ?.S, Date f; "irrn o" RacfciJi--. i , :_5b ; :.°'^i/l- - ..'• f..:. --J. 1= A.-- ; .'^- , 3..£. -i.5rr, = 7 Tc-a' it-üce'", Ke_sy_l tg !_-: Tota'. i"let'?rüt."Dprii z Bact5r:.a per" IGO nl o-;- 'i'cc' ^-Li.TierQu^i to count. samnie at ^'i. 5 f. Total r.umber- of al i typs^. j-f coli^'^Di-ffi bact=r ia c recsn ; in i.to;.. lOOml u-f ïiarnple at 37 C. Na.T.ütr- a-* ä ccii irv '*-00.->l -uf sample i>t 44 u. Remarks!- Unsatisfactory. There is evidence of recent faeqal pollution. [ ( This report is issued for the information of the clent.It shall not bet publ ished in total or i.i part without ant.iQri t'- of the General Manager. National Water St^pply f< D'-ainage Boara. This report is limited specif ical ly ti this speci^.en. H. A. K. AMARAKOON MINISTRY OF HOUSt^^f3lfiHJEBÄ^4DEVELOPMENT «üroT/^Ml^i*'^»^^^ ^^-^ of.Lab.Services TBLAWALA flOAD r .... 1. '.z^:^ r National Water Supply & Drainge Board asicß coosmCoosnoAa ] 01.00. oooo r 635281 -3,635247, 63-1483 B.L1 ««>ni(u<^ I 63S883 Chairman 635887, 635996, Vice Chairman J General Office ") p. 0. Box }" MI. Lavinia Telex : 21482 NWSD8CE sDfioa. 636449 Fax : 636449. 637178. 635999 General Manage ,) Galls Road, Ralmälaria. Sri lanka My No. Y^u^NSti^TRAL LABORfiTORY '^Q' TELAWALA ROAD,RflTMALANA Date : 199a/Jl/2A £ur:Bct : Bacteriological E>:amination of Water Source of Sample : W - 44 :ijell at N'o.?-:5, Anbalanmul la , 3 *etiuwa. Da'-.e ?^ Tine cf Co'lectiai : •9?8'n/lö at r-^ ?0. -.:'•. Date ?. Tine -f Receipt i"- Lab • •. = 98'l:!/i7 SI 09.15 A..vi, Rspor- Retii. ired B •' 1 tir . S.E.i'^. Sor^fS . Team ie=id2'-, E. C. L. Temperature J 29 r Total Heter'ctrcpi'iic Bacteria per iOC ml o" ; Tor' NuRfeT'ijUs •cr, count. saTiple at 31. 5 C Total number of all type= o^f coliform bacterta D-'ecent in : Mo'-s than liOO. lOOtnï of sample at 37 C Number of E coli in 100ml of ; 4tjC, sar.iple at 44 C. '^' ' Remarks! - Unsatisfactory. Ihere. j^. evidence of recer>t , faecal pollution. This report is issued for the inforir.ation of the clent.It shall not be published in total or in part without authority of the General Manager, National Water Supply ft Drainage Boa-d.This reoort is lo/tnitec specifica 1ly to this spec imen. L H.A.K. AMARAKOON SENIOR. CHEMIST MINISTRY OF HOUSING(*tAJftfl^rtBRJf»CtORMENT • L "Walff^llÖfliyJÏWFlWft'i^rc^^D"*"**^^"'*'^'^^^'^ of .Lab.Services TELAWALA ROAD -f^ L n ATMALANA; (•• •\\"'?ïMtó.4s. i.ni= -?'4:F--: V^V National Water Supply & Drainge Board asoof) CO coma gÖTO QIEél»3 DL co. 0MK9 1 634488 635883 635281 -3.635247. « Qu. fffli I Chairmalan J Vice Chairman General OHice 635887, 635996, Mt. Lavfnia •} P.O.Box J Talex;21482NWSDBCE ttfi*n%ntüminspfi 636449 Fax ; 636449, 637178, 635999 ®:9 0)ö, Cenäral Manage J Galle Road. Ratrr^alana, S'ri lanha eoSooco My No. YouYourNo'-^'JTRAr NO.CE/'J L LABORATORY '^^• TELAWAUA RGADJRATNALANA Date 199e/ll/2/- Subject Bacteriological Ev: ami nat ion of Wate Lab.PeQ . t Source Df Ba^^Tple W - 47 Well ï Date f.; T:,n-.:L. --= Coliectiari 1993/:..'.Zit -z 0^.45, ~\'.-'. Da te ?' T i r.e T' ^ Receipt ir l 1'^93-li-.'i:' B- 09.1':- C,M. .REport Reri'-ri^ed By Kr-, 3 .;~ , >! V GoTer ;> Tearr. lea'-T-r, rr. C-. :.. R_es'jlts_!- Tei7ipe.re.ture ' otai Hetsrz' -:-cr.rij.c Bacteria per i00 ii;i of TcQ Numerous to cüunt, B^mpie at 34 . c. w Total nuiTiber af all types of CQüform bacteria precent ir. y^zjrB than 1100 iOOml of sample at 37 C. Number af E coli in lOOml of 460. sample at 44 C. •• «e. Remarks:- Unsatisfactory. There is evidence of .recervb__.. faecal pollution• : This report is issued for the information of the clent.It shall not b published in total or in part without authority of the General j Manager, National Water Supply & Drainage Board.This report is limit^ specifically to this specimen. H.A.K.AMARAKOON ' SENIOR CHEMIST •/ MINISTRY OF HOUSir«^fiIABed»DIWKnOri>MENT "WfllfloÄWrvßrepfiM'fWlA.S«*'"*'*"''*"^! ^^^^-^ of .Lab.Service= TELAWÄLA ROAD -^ . n A.TMMJANA: .T-"' '•^•;... •. ./.•p.-»V.-."J»>AJ-.., •,, ... t\-' j...:. •. - mm>^^'' r dDïS£3) dg e3®ö3^S5 C03 £5^3002025 ê^^^Qc^ National Water Supply & Drainge Board r co osnfl c 63SBB3 e. Ou. ffni.l Chairman ) VicIce Chairman j General Office 635887, 635996. ^0. Box J Ml. Lavin ia a;ftQ»OaC Telex: 21482 NWS08 CE 0119 on. öcMWD ty 636449 Fax : 636449, 637178, 635999 «nni) tig. Generaleral ManaaeManager ) Galle Road, Ralmalana, Sri Ian ka 199. My No. ) Yout No. I CENTRAL LABORATORY TELAWALA ROAD^RATMALANA Date : 199B/11'2.:> J Bacteriological Examination of Water Lab.Reg. No : Sac/9S/ß2" Source of 5=.rT;ple : k - 13 Wei1 at M^Dola, Watte'.a . Date 3> Tine of CoL 1E.'C ti c" : i99&/ll/lÄ at 12.30 P.M. E-ate &- Tif7;'= of Rsceip'i in .?.L ; i?-9/'i'iy at 09.1? A.r, Reocrt R=quirec By : Mr.G.E.N.Gomez Team leader, E . C. L Results:- Tempsr-?.tL.-e 29 C Total HeT:sr-.jt'i3p.-,_c 9act=r;!.a pe- 100 v'l of 930 sample at 34.5 C. Total number of a?, 1 types of 09 coliform bacteria precent in lOO.Ti: c-f siample e-. 37 C. Ntim'oer 3f E co.' i ..r, iOOrri 1 of 00 sanple at 44 Z. b Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the clent.It shall not be published in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is 1 imited L specifically to this specimen- H-A. K. AMARAKOON L MINISTRY OF HO KATÏiH*lt''W^Virvflre|üflfo««t**Q6BOAftOChief of .Lab.Services T£LAWALA ROAD ^' tt ATnm «WA. L . t::-\ .- <^ I ^fJaaBl^MJ'^n National Water Supply & Drainage Board CO MUOS p£MD eooboa ESLOaCMtO «344S« LU ^d&BjDJl4 G3SM) ».Qu. f^ Cuirman ) . P.O. Bai J ML Uvink, Ttlac 21461 KW50B CE m>a eaö, ótf»3ia. •"•ei ghu- •-US' ä^' f MrNo. ïour No. I 199 CENTRAL LABORATORY TELAWALA ROAD,RATMALANA Date : 1999/03/18 Subject s Bacteriological Examination of Water Lab.Reg. ND : Bac/99/85 SaurcB of Sample : W - 01 Date & Time of Collection : 23/02/1999 at 01.35 PM. Date & Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.C.L, Sri Jayawardenapura Mawatha, Welikada, Rajagiriya. Results:- Temperature ; 29 C Total number of all types of coliform bacteria precent in : More than 1100. 100ml of sample at 37 C. Number of E coli in 100m1 of : More than 1100. sample at 44 C. Total Bacteria Count : More Than 1100. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. .- ta This report is issued for the information of the clent.It shall not be published in total or in part without authority of the General Manager, National Water Supply ft Drainage Board.This report is limited specifica1ly to this specimen. Lab.Assistant i. S/= MINISTRY OF HOUSING & URBAN DEVELOPME^^• 'Water • Every Drop la Precious' dDSsS) Ö© Ca^OD^SD ODD d©3O0CD® @05Ö©C3 r •joi t*ii m tKH «^ol National Water Supply & Drainage Board CO OSOOS QO» arabes siUM. qido 1 ««OM r «SMI-I. USZ47. tiM«g a Ou. (iiM. US«M Vk«Cti*nwi } GwiMionic* ) PO.Ow J HLUvUvInMk . T*l«:11tUHWS0eCE ( MjFNO. I ïogf No. 199. CENTRAL LABORATORY TELAWALfl ROAD,RATMALANA Date : 1999/03/18 Subject : Bacteriological Examination of Water Lab.Reg. No : Bac/99/86 Source of Sample : W - 03 Date & Time of Collection ; 23/02/1999 at 01.25 PM. Date ft Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.6.E.M.Gomez, Team Leader - E.C.L, Sri Jayawardenapura Mawatha, Welikada, Raj agiriya. Results:- Temperature. : 29 C Total number of all types of coliform bacteria precent in : More than 1100. 100ml of sample at 37 C. Number of E coli in iOOml of Ï More than 1100. sample at 44 C. Total Bacteria Count : More Than 1100, Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. . This report is issued for the information of the clent.It shall not be. published in total or in part without authority of the General Manager, National Water Supply ft Drainage Board.This report is limited specifically to this specimen. r '^•hu ^Sfh(^ Lab.Assistant Chemist L S/ = MINISTRY Of HOUSING & URBAN DEVELOPMENT L 'Water - Every Drop Is Precious' L -V" .-- •~rm. National Water Supply & Drainage Board OSDOfi co OODOA BtOO. VoCM9 ^ a>«Sddi «du- 0x 1) tMtU ns*u aim CM*iran Vkc* Chilnivvi } ) P.O.Boi I MLLnk T*lu: 21 *a; NWSOB CE sog OM). tM44( Fut i(3«44l.e]717l,(3}m Gananl ManapH GafMKcM. RdKHlana. SH L«nki. Bod ihaa 1 Hf Na. I Vt« ND. I 199. CENTRAL LABORATORY TELAWALA RÜAD,RATMALANA Date ! 1999/03/ia Subject : Bacteriological Examination of Water Lab.Reg. No ! Bac/99/87 Source of Sample : W - 05 Date 8( Time of Collection -. 23/02/1999 at 12.45 PM. Date & Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.C.L, Sri Jayawardenapura Mawatha, Welikada, Rajagiriya. Resultsi- Temperature : 29 C Total number of all types of col iform bacteria precent in : 460. iOOml of sample at 37 C. Number of E coli in lOOml of : 460. sample at 44 C. Total Bacteria Count : More Than 1100. Remarks:- Unsatisfactory. There is evidence "of recent faecal pollution. This report is issued for the information of the clent.It shal1 not be published in total or in part without authority of the General Manager, National Water Supply & Drainage Board -This report is limited^ specifically to this specimen. HKXX c<-iei MINISTRY Of HOUSING & URBAN DEVELOPMENT "Water - Every Drop is Precious" . . .' f. •I'.'. iiOi.iii'^ r dDS® d© csiaDC® eo3 d©Do0eo© ®05Ê)(gC3 /^S^\ National Water Supply & Drainage Board r MnoA CO OOUDA m^Odo. U Sil 1-3. CMM7. (M.eo, qoa ÏM4U I15U) «SM« Chfllrnvn VIcvChAiMn } ') . P.O. OOI }" Ml.L Veur No. I 199, CENTRAL LflBORATORY TELAWALA RGAD,RATf1ALANA Date ï 1999/03/18 Subject : Bacteriological Examination of Water Lab.Reg. No : Bac/99/ea Source of Sample : W - 09 Date &' Time oi Collection ! 23/02/1999 at 12.15 PM. Date & Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader — E.C.L, Sri Jayawardenapura Mawatha^ Welikada, Rajagiriya. Resultsi- Temperature . : 29 C Total number of ail types of coliform bacteria precent in : 1100. 100ml o-f sample at 37 C. Number of E coli in 100ml of : 1100. sample at 44 C. Total Bacteria Count : More Than 1100. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. M This report is issued for the information of the clent.It shal1 not be published in total or in part without authority of the General Manager, National Water Supply St Drainage Board.This report is limited [• specifically to this specimen. Lab.Assistant Chemist. L S/= MINISTRY Of HOUSING & URBAN DEVELOPMENT L "Water - Evary Drop Is Precious" I ,»-. National Water Supply & Drainage Board oawS eaaeoaS gCba öDofoijo eis;«!-], (jsMr, «tl». »«OO 1 IDMtfO. t344U Lu ^•••jaj^ UMU E3SM« a Qu fiwu Cnalrmin VIcaCTufrran ) GwltmOM« I HL Uvinla. T*I«:31M1NWSDBCE Eng OK). (^•nMKMx .,}) UMI« Fm : Ut44>, U7I7I. tUt9a «••II ali). SoD 9)00 1 MfNO. VMT No. I 199. CENTRAL LABORATORY TELAWALA ROAD,RATMALANA Date ! 1999/03/lB Subject : Bacteriological Examination of Water Lab.Reg. No : Bac/99/89 Sot-irce of Sample -. W - 13 Date & Time of Collectian : 23/02/1999 at 11.40 AM. Date Sc Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.C.L, Sri Jayawardenapura Mawatha, Welikada, Rajagiriya. Resultsï- Temperature : 29 C Total number of all types of coliform bacteria precent in : 150- 100ml of sample at 37 C. Number of E coli in iOOml of : 93. sample at 44 C. Total Bacteria Count : More Than 1100. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the clent.It shall not "fae published in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is 1 imited specifically to this specimen. .^^'W^VE^fCt Lab.Assistant Chemist S/= .'. :• ;-.-,r>: MINISTRY OF HOUSING & URBAN DEVELOPMENT 'Water • Every Drop Is Precious' ft- .-^.ir- .^ .. ^ ': ^. v-ß.-. '••A', r National Water Supply & Drainage ßoard OODOA co CKUOA BOMB anobaa (Moa. qMM eiSIII-l. t3S34T. 1941Bt «3SH3 Cndnnin Owmfortk« "} P.O. Bot MLL^vL^vInlb L r (S>*iatuSB)0 T*I«:2IU3NWS08CE aug oM. «36449 Fu : I3M4R, 117171, USïM •••il •!£. (j*rHr4l Uant^r auMRoHi, RMinWni. Sri LanU. •ocd ii>90 Mr No. } 199. CENTRAL LflBORftTORY TELflWALA ROADjRftTMALANA Date : 1999/03/18 Subject : Bacteriological Examination af Water Lab.Reg. No : Bac/99/90 Source o-f Sample ! W - 15 Date & Time of Collection ; 23/02/1999 at 10.25 AM. Date ?< Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.CL, Sri Jayawardenapura Mawatha, Welikada, Rajagiriya. Temperature 29 C Total number of all types of coliform bacteria precent in : 240. 100ml of sample at 37 C. Number of E coli in 100ml of : 240. L sample at 44 C. Total Bacteria Count ! More Than ilOO. Remarks!- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the dent.It shal1 not be published in total or in part without authority of the General Manager, National Water Supply ?< Drainage Board,This report is limited specifically to this specimen. Lab.Assistant Chemist, S/= MINISTRY OF HOUSJNG & URBAN DEVELOPMENT 'Water - Every Drop is Precious' •-551 br-M r -'»:-'."" É.'-"BW^^-,!•'• National Water Supply & Drainage Board oaMtawboa K.0O 9iaa t3»l1-9. (35247. «MIU UU» VlcaCTiikrMn GWMfMOflIca "} P.O. Bot UlUvInlê. B)S)BI0&(UO óMoxa. «36449 FM :t}»44«.U717l,«]»M •n*II idil. HMmalwi*. Sri Lantu. My rio. T CENTRAL LABaRATORY TELAWALA ROAD^RATMALANA Date : 1999/03/18 Subject : Bacteriological Examination of Water Lab.Reg. No ! Bac/97/91 Source of Sample : W - 17 Date & Time of Col lection : 23/02/1999 at 11.30 AM. Date ft Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.C.L, Sri i7ayaMardenapura Mawatha, Welikada, Rajaqiriya. Results;- Temperature : 29 C Total number of all types of coliform bacteria precent in : More Than 1100. 100ml of sample at 37 C Number of E coli in 100ml of : More Than 1100. sample at 44 C. Total Bacteria Count More Than 1100. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the clent.It shall not be published in total or in part without authority of the General Manager, National Water Supply S< Drainage Board.This report is limited specifica1ly to this specimen. ^?^4^f.iï(^ Lab.Assistant Chemist. MINKTRY OF HOUSING & URBAN DEVELOPMENT ;- 'Water - Every Drop Is Precious* •^>.'^'-^Sfo'.-. . - < . . f_' ^.iii' r r National Water Supply & Drainage Board oeao6 e]S2tl-3. »S»T, e5utt US(M OMiTTWl VkiaCtidnMii CwwttOKK* •) Mt Lnbuiuw . TiKi: I1U2 HWSOe CE r F*i :l3MM,(]ri7ll.t3SÏM OtMt ftMinatona, EH Lanka. •o« 41013 You> Na. 199 CENTRAL LABGRATORY TELftWALA ROAD,RATMALANft Date : 1999/03/lB Subject : Bacteriological Examination of Water Lab.Reg. No Ï Bac/99/92 Source of Sample : W - 18 Date ?< Time of Col lection : 23/02/1999 at 10.55 AM. Date ?< Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez , Team Leader - E.C.L, Sri Jayawardenapura Mawatha, Melikada, Rajagiriya. Results:- Temperature, : 29 C Total number of al1 types of caliform bacteria precent in : 240. 100ml of sample at 37 C. Number of E coli in 100ml of : 240. sample at 44 C. Total Bacteria Count : More Than 1100. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This reJDOrt is issued for the information of the dent. It shal 1 not be published in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is limited r specifically to this specimen. Lab.Assistant Chemist. L S/ = L MINISTRY OF HOUSING & URBAN DEVELOPMENT "Water • Every Drop Is Precious' I -f.-rr-iwr.-^ I -Ä2^ ¥ Am B i^.:m Mt» I National Water Supply & Drainage Board m.00. 9tOO •-U ^^w>&rt t3U«1-]. (ISHT. •"•*" J S3*. MMU B Qu. glu VlMCnatnnwi «SSM } CtiwifOnica } P.O. Boi 1 MlUvMI«. T»llll:Z<4«ZNWS0aCE «Ufl 010. (3^41 F» : NM4«. tI7i;>. KStn GdtiRoM. nalmalwu, Sil Link* Ooi anOQ My No. Your No. CENTRAL LflBQRATaRY TELAWALA ROAD,RATMALANA Date : 1999/05/18 Subject : Bacteriological Examination .of Water Lab.Reg. ND ! Bac/99/93 Source of Sample : W - 21 Date & Time of Collection : 23/02/1999 at 09.15 AM. Date & Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By Ï Mr.6.E,M.GDmez, Team Leader - E.C.L, Sri Jayawardenapura Mawatha, Weiikada, Raj agiriya. Results;- Temperature : 29 C Total number of all types of col iform bacteria precent in ; More Than 1100. 100ml of sample at 37 C. Number of E coli in 100ml of : More Than 1100. sample at 44 C. Total Bacteria Count : More Than HOO. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the clent.It shall not be published in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is limited specifica1ly to this specimen. • B • • • • • h u f i t • Lab.Assistant Chemist. S/ = MINISTRY OF HOUSING & URBAN DEVELOPMENT "Water - Every Drop Is Precious' ...ï -^ifcffc • <»-«!?^3rï'ïrj.' ."•• National Water Supply & Drainage Board co osuoS endo, tftoa 't ei^Saa Lu ^aMwoiA t)M«) ».Ou. |i\H. I „ kiuil** crmiimin J Wc« atlliTTitn P.O. a« I UL UvlrAt. lug CDÖ. öa>9 600} giCBO 1 1.11(1 (iki. ) Uf No. J Yout NO, I 199 CENTRAL LABaRflTORV TELAWALA ROAD,RATMALANA Date : 1999/03/18 Subject : Bacteriological Examination of Water Lab.Reg. No ! Bac/99/95 Source of Sample : U - 36 Date & Time of Collection ! 23/02/1999 at 07.25 AM. Date & Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.C.L, Sri Jayawardenapura Mawatha, We1i k ad a, Raj ag i r iya. Results!- Temperature 29 C Total number of all types of coliform bacteria precent in More Than 1100. 100ml of sample at 37 C. Number of E coli in 100ml of Mare Than 1100. sample at 44 C. Total Bacteria Count : More Than liOO. Remarkai- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the clent.It shall not be published in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is limited specifically to this specimen. .H^iic^kfiJ ' Lab.Assistant Chemist. S/= MINISTRY OF HOUSING & URBAN DEVELOPMENT "Water • Every Drop lo Precious" •,i»-rS' r National Water Supply & Drainage Board osuoA co CMuoS BKoa tM**t • .<9u r Cmknun "1 P.O1.. BDI J Ml. Lavlnla. T*l« : 21W2 NWSOB CE (MA mö. tltut •" J G*ncial Utm^ F*i : E3e44t,uriTt,ijsïw GMwnowi. Don 9ise ^ Mr No. 199. ÏOurNc.. I CENTRAL LflBÜRftTDRY TËLAWALA RDAD,RATMALANA Date : 1999/03/lB Subject : Bacteriological Examination of Water Lab.Reg, No = Bac/99/96 Source of Sample : W - 44 Date & Time of Collection : 23/02/1999 at 07.15 AM. Date & Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.C.L, Sri Jayawardenapura Mawatha, Welikada, Rajagiriya. Results:- Temperature : 29 C Total number of all types of col iform bacteria precent in : More Than 1100. 100ml of sample at 37 C. Number of E coli in 100ml of ! 460. sample at 44 C. Total Bacteria Count : More Than HOO. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the dent.It shall not be b published in total or in part without authority of the General Manager, National Water Supply & Drainage Board-This report is limited specificaIly to this specimen. Lab.Assistant Chemist, L S/= L MINISTRY Of HOUSING & URBAN DEVELOPMENT I 'Water - Every Drop la Precious' -•-wr^vi" daSss) d© C3®03ca) COD d@3oe)eoeD ®Ê/5©©C3 JZ^\Y National Water Supply & Drainage Board aeoaS CO (MXjfi OCDa BDobso stoo. 4>sa UMM «35U1 ^^f •MV*"'* ß.Qu (ijw ChMman VInCtalnnn Cwwraioni» MStM ") P.O. Boi HLLndLnini«r . T*l*I:11«tZNWSC:BCE GWMÏ Fu :«HM»,U7I7B. t»MI ' Gwwnl Uaugtr GalURoK; Hnmilvu. Sd LviU. sua v>oa ] VotM No. ! 199. CENTRAL LABORATORY TELAWALA ROAD,RATMALANA Date ! 1999/03/18 Subject : Bacteriological Examination of Water Lab.Reg. No ! Bac/99/97 Source oi Sample : W - 47 Date & Time of Collection : 23/02/1999 at 07.45 AM. Date & Time of Receipt in Lab : 23/02/1999 at 02.55 PM. Report Required By : Mr.G.E.M.Gomez, Team Leader - E.C.L, Sri JayaHardenapura Mawatha, Welikada, Rajagiriya. Results:- .-' Temperature : 29 C Total number of all types of col iform bacteria precent in : More Than 1100. 100ml of sample at 37 C. Number of E coli in 100ml of : More Than 1100. sample at 44 C. Total Bacteria Count Ï More Than 1100. Remarks:- Unsatisfactory. There is evidence of recent faecal pollution. This report is issued for the information of the clent.It shall not be published in total or in part without authority of the General Manager, National Water Supply & Drainage Board.This report is limited specifically to this specimen. \ t, ^^CLi MINISTRY OF HOUSING & URBAN DEVELOPMENT "Waler - Every Drop Is Precious' "-r*"w< •,*ic^:5' - r-_ oo_ •«'_ M o_ w% •»•_ -3-_ r-) (N_ (~-_ M t--_ fN F: /*\ r^ï r^ —.- ^_" (^" r^" ,-" -j" «^ 'Ö lA f^ co ^^ '- ^- ^ C^ ï^ [^ r-1 —' o O - - ". ~ o «n ? a o K S o 3 S £ s "-"- '^. 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