1. Metro Colombo Urban Development Project

Public Disclosure Authorized

Environmental Screening Report for Embankment protection of Dehiwela Canal from the Galle Road Bridge to close to the sea outfall and removal of localized rock outcrops from the canal bed

Final Report

Public Disclosure Authorized December 2011

Uni‐Consultancy Services University of Moratuwa

Table of Contents

1. Project Identification 3

2. Project Location 3

3. Project Justification 5

4. Project Description 7

5. Description of the Existing Environment 10

6. Public Consultation 21

7. Environmental Effects and Mitigation Measures

7a. Screening for Potential Environmental Impacts 22

7b. Environmental Management Plan 31

8. Conclusion and Screening Decision 42

9. Details of Persons Responsible for the Environmental Screening 49

Annexes

1. Photographs of some of the important locations along project roads

2. Detailed drawings of project components

URBAN UPGRADING WORK

Metro Colombo Urban Development Project

Environmental Screening Report

1. Project Identification

Project title Embankment protection and demarcation of canal reservation of Dehiwela Canal from the Gall Road bridge to close to the sea outfall

Project Sri Lanka Land Reclamation and Development Corporation Proponent

2. Project Location

Location Location of the project is depicted in the Fig. 1.

Definition of The project area is along the Dehiwala Canal from the Bridge at Galle Road to Project Area the sea outfall.

(The geographical extent of the project & areas affected during construction)

Adjacent land See “Other features” in Section 5.2 and features

Figure 1. Location map showing the Dehiwela Canal and its sea outfall

3. Project Justification

Need for the project The Colombo Drainage System comprises a network of large open drainage canals, smaller tributary canals and low-lying marshes functioning as natural retention basins. It functions to serve the drainage needs of the Greater Colombo area and reduces incidence (What problem is the of flooding and thereby improves the health and sanitation project going to solve) conditions of the urban community, particularly of the urban poor who inhabit low-lying regions of Colombo.

The system could be broadly divided into two, with canals to the north of Sri Jayawardenepura Mawatha as Colombo North system and that to the south as the Colombo South system (see Figure 1. The system has four outlets and three of which Dehiwala and Wellawatte Outfalls and Mutwal Tunnel directly discharging in to the sea, while the North Lock discharges in to the Kelani River. There is a fifth outlet for the spill waters of the Beira Lake, via a circular weir near the old Parliament; the canal system is no longer connected to the lake to prevent highly polluted canal waters entering the lake. When the Kelani River level is high, the gate at the North Lock outlet to Kelani River is closed, so that reverse flow (from the river into the system) cannot take place. This operation is now carried out by the Department of Irrigation. Mutwal Tunnel of diameter 1.8 meters, functions as the outlet of the Main Drain. The head of the canal system could be considered as Parliament Lake, to the East of Kotte Lake. Under dry weather conditions the North Lock, Wellawatte and Dehiwala outfalls are the major outflow points. In a flood situation, with the North Lock closed due to high water level in the Kelani River, the system has to rely mainly Wellawatte and Dehiwala sea outlets. Also the Mutwal Tunnel helps ease the drainage problems of North Colombo to a great deal at times when the North Lock is closed. Dehiwala Canal Dehiwala Canal is one of the main storm water drainage canals discharging storm water directly into the sea from the Colombo Basin. It starts at the branch where the Wellawatta Canal takes off from the Kirillapone Canal. The length of the Dehiwala Canal is 3.8 km. It has a bottom width of 10 m up to the Bolgoda Canal confluence and it varies up to 24 m thereafter. Both banks of the canal are protected with gabion walls

and sheet pile walls up to the Galle Road Bridge from the starting point of the canal. The canal stretch from Galle Road Bridge to Railway Bridge is earthen and is unprotected. In several places of the unprotected stretch the canal banks have collapsed and eroded causing severe inconveniences in carrying out maintenance work. The proposed canal stretch between the Galle road and the railway bridge is about 30 m wide and groins have been constructed to prevent formation of sand bar closing the sea outlet. There are rock outcrops on the canal bed in three locations and flow guidance walls upstream of the railway Bridge causing hindrance to the conveyance capacity of this storm water drainage outlet canal. The project once implemented will facilitate undisturbed flow at the canal section and at the outfall.

Purpose of the project The purpose of the project is to derive the following benefits and the beneficiaries are listed below: (what is going to be Benefits achieved by carrying out the project) ∗ Enhancement of flood control. ∗ Increased land values in adjacent areas. ∗ Improved health conditions & reduction in health expenditure. ∗ Reduction in annual operation & maintenance cost to the central government for canal clean-up ∗ Increased use of the canal system for recreational purposes & waterfront development. Beneficiaries ∗ People residing close to the canal and with the combined effect, the entire Metropolitan area. ∗ The Government and the agencies managing the storm water drainage.

Alternatives considered No any other alternative is considered for the project as it is envisaged that there are no any other technically feasible and (different ways to meet the economically viable engineering interventions that could be project need and achieve accommodated in place of the proposed option. the project purpose)

4. Project Description

Proposed start date The tender documents are expected to be ready by December 2011. Awarding of the tender will take place only after the 16th of March 2011. Construction period is estimated to be one year.

Proposed completion It will take minimum 12 – 15 months to finish the project from the date date of opening bid documents.

Estimated total cost Estimate: 1.39 US$ million

Present land Entire project lies in areas belonging to SLLRDC. ownership

Description of the The detailed drawings of the project are given in Annex 2. project 1. Dehiwala Canal bank protection from Galle Road Bridge to the (with supporting outfall. material such as a. New gabion wall - 671 m maps, drawings etc b. Provision of flow guidance walls made of gabions at attached as upstream side of the railway bridge. required) 2. Reinstatement of storm water drainage connections (hume pipes) to Dehiwela Canal through gabion walls and introduction of catch pits wherever required. 3. Reinstatement of maintenance road (3 m) and construction of road side drain and cross drainage to the canal. 4. Temporary shifting & relocating of utility posts (electricity & telecom). 5. Removal of localized rock outcrops on canal bed obstructing water flow in three selected locations of the canal bed.

Project Management Agency: The agency responsible for design and supervision is the Team SLLRDC and the organization structure for the project is given in Figure 2.

Contact person: Ms.A.H.Thushari

Assistant General Manager (Special Projects) Sri Lanka Land Reclamation & Development Corporation

Nature of the consultation and input received:

Meeting and consultation at design office and site were done. Design drawings, master plans and other relevant information were too gathered.

Figure 2.Imeplemntation arrangements for MCUDP under SLLRDC

PROJECT

DEPUTY PROJECT

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Draughtsma Quantity Comput Projec Projec Projec Projec Surveyors er t t t t Offic Drive super‐ super‐ super‐ super‐ e

5. Description of the existing environment

5.1 Physical features – Ecosystem components

Topograph The topography of Sri Lanka is marked by great diversity caused by long years of faulting and erosion of the landscape. y and The central mountainous region with the highest elevations covered by virgin forests and grasslands rises up to about terrain 2,500 m above mean sea level. The surrounding plains, which rise to about 50 to 100 m above sea level, are largely used for agriculture and homesteads, but still have virgin scrubland where the population distribution is lower. This general topography of the country can be divided into three distinct geographical areas or well marked peneplains featuring the coastal belt, the plains, and the central highlands.

The Colombo district which incorporates the project area falls into the so called lowest peneplain of Sri Lanka (after P.G. Cooray – Geology of Sri Lanka, 1984). The elevation variation of Colombo district situated in this coastal peneplain ranges to a maximum elevation of 150 m from sea coast. The terrain in Colombo largely consists of gently undulating plains and low-lying flatlands with a high density of drainage paths formulating a geography consisting of a mix of land and water. The city has many canals and the 65-hectare (160-acre) Beira Lake situated in the heart of the city is one of the most distinctive landmarks of Colombo.

Dehiwala City is part of the Colombo Core Area and lies about 8 km to the south of Colombo City. Dehiwala Canal considered under the proposed drainage improvement and embankment strengthening is connected to Kirillapone Canal, Diyawanna Ela (canal) and Kolonnawa Ela in the upstream and drains a large area consisting of low-lying marshes and other local water bodies, eventually entering the sea at the sea outfall located about 1.2 km north to Dehiwala main city area. The canal which is 3.836 km in length is located within a mere 2.0 km inland from the coastal line and the elevation varies from 0 m above mean sea level (MSL) at the coast line up to a maximum of 15 m MSL only. Therefore, the slopes encountered in the project area are flat to mild (<1.0 %) and gently slope in seaward direction while the contour lines are aligned approximately parallel to the shoreline. The surface drainage in the area is largely determined by the trellis-patterned storm water drainage system consisting of both concrete-lined open canals and underground ducts connected to Dehiwala Canal in the downstream, diverting accumulated surface flows directly into

the sea through its outfall with a maximum capacity of 30 m3/s which runs across a short strip of bare sandy beach devoid of beach vegetation. Patchy sandstone reefs occur in the sea at about 1 km distance away from the shore, but presumably have no any direct impact on the discharge capacity of the outfall.

Soil (type The geology of Colombo is representative of the geology of the western coast of Sri Lanka and has existed for much of and the Quaternary era. Bore holes drilled in central Colombo City show that this area once formed an estuary of the Kelani quality) River and the Kalu Ganga River, the two main rivers that drain into the sea on the western coast. A few kilometers upstream in the inland valleys, there is a high-level gravel formation consisting of quartz pebbles embedded in a matrix of laterite separated with pebble-free layers of laterite. The floodplains along the rivers consist mainly of alluvial deposits. The floodplains of Kelani River also provide thick alluvial profiles for unconfined aquifers, in addition to the productive overburden along tributary banks.

Vast area (over 90%) of Sri Lanka is underlain by metamorphic crystalline rocks of Precambrian age, which includes the project area, which cover a variety of Gneisses. The geology of Colombo is representative of the geology of the western coast of Sri Lanka and has existed for much of the Quaternary era. This is shown in the 1:10,000 and 1:50,000 geological maps of Colombo region produced by the Geological Survey and Mines Bureau. The typical rock types of this basement include Biotite gneiss, Hornblende Biotite gneiss, Charnockites, Charnockitic gneisses, Quartzite and undifferentiated Meta sediments. The floodplains along Kelani River and the Kalu Ganga rivers consist mainly of alluvial deposits. The floodplains of Kelani River also provide thick alluvial profiles for unconfined aquifers, in addition to the productive overburden along tributary banks.

According to Survey Department soil maps (Figure 3) the main soil types in the project area are as follows. • Red Yellow Podzolic soils with soft or hard laterite and undulating terrain • Bog and Half bog soils: flat terrain • Alluvial soils of variable texture and drainage: flat terrain • Regosols on recent beach sands: flat terrain

Field surveys and observations carried out using trial pit holes have indicated that the local geology in the proposed project area is characterized by organic clays with sand and deep bedrock while the soil peaty clays with clayey laterite types are intermittently distributed in patches. It is presumed that these site-specific features are the most important ones as the environmental impact is considered.

Figure 3. Soil Maps of the Study Area (Source: Greentech, 2011)

Surface Sources water (sources, The most prominent source of surface water in the vicinity is the Dehiwala Canal and surface water drainage canal distance network that are connected with the main canal: from the Distance from the site: Project area is the banks of the canal and the outfall. site, local uses and Local uses: The canal plays an important role in conveying surface drainage and flood waters. Although the local people quality) do not derive other benefits than diverting their surface drainage into these canals, the intrinsic function is vital and most important in draining the flood waters of the area. There are numerous illegal discharge points of grey water from residences, commercial establishments and warehouses located adjoining the canal, and due to the appalling level of water pollution, no other local uses can be derived from the water body.

Quality

Table 1. Water quality fluctuations of Dehiwala Canal

Parameter Water Quality (during 1997-2009) pH 6.4 – 7.9 Conductivity (dS/m) 0.47-12.3 Turbidity (NTU) 13-37 Ammonia (mg/l) 0.84-6.2 Nitrates (mg/l) 0.3-16.1 Phosphates (mg/l) 0.4-3.4 DO (mg/l) 1.2-3.5 BOD (mg/l) 13-48 COD (mg/l) 17-134

The water quality measured at two locations of the Dehiwala Canal is given in Table 1.

COD, BOD, turbidity and total suspended solid content are very high in the water. Dissolved oxygen, and pH are within the normal range. Phosphate concentrations are relatively high which indicate nutrient enrichment due to disposal of domestic and industrial wastewater into the canal over time.

Ground Sources water (sources, According to the Land Use Division of the Irrigation Department, the project area falls within the local or discontinuous distance moderate to low aquifer in fractured rock. Only available source of ground water in the project site is shallow wells. from the However, ground water as a source of water is only been used for bathing at present. There are two bathing wells site, local located in the banks of the canal: one is been used and the other is abandoned due to bad water quality. This is due to uses and two reasons: availability of ample water supplies by NWS&DB and ground water being polluted. quality) Distance from the site

The ground water table is very shallow and is about 0.4 - 0.5 m on average close to the Canal, and can be at a level from almost at surface up to 1.5 - 3.0 m.

Local uses

Only a handful of households use shallow wells to abstract water. Even those who have shallow wells do not use water for daily consumption; they use the wells only occasionally for bathing and washing of clothes.

Quality

There are no data available for quality of ground water. However, it can be assumed that dissolved solid levels including salinity to be high as the project area is located very close to the coastal belt. The ground water can get contaminated due to dilapidated state of sewer connections and leakages.

Flooding The downstream catchment area has suffered from frequent flooding up to around two to three times per year, before the previous canal widening/dredging and drainage improvement works were carried out (2004/2005). The canal stretch and all road segments in the proposed project area appear to have adequate drainage capacity and systems in place at present. The terrain is either flat in most areas or consists of mild slopes, therefore, no historical records of recent flooding are available in the area under consideration. However, after extremely heavy storm events and especially due to temporary blockage of existing storm water drainage system, the water movement concentrates in the low-lying areas causing temporary ponding or minor flooding in the adjacent localities, as has occurred in the recent past. Another factor, besides clogged drains and lack of proper maintenance that contributes to the flash flood problem is that excessive and unplanned land filling especially in the upstream marshes, leading to devoid of retention and detention capacity in the basin. Nevertheless, these effects are yet not significant in the project area and can easily be avoided by ensuring that the existing drains are well maintained and routine checks are carried out, particularly after major storm events.

Tidal effects (on main drainage lines and sea outfall)

The tidal effects should be considered in determining design levels for the downstream drainage structures including sea outfall. Due consideration should be given to maximum tidal variations and maximum wave heights when establishing drainage line and sea outfall design capacities.

Tidal Levels and Periods The tide around Sri Lankan coast is mixed semi-diurnal type with two high waters and two low waters occurring approximately every 24 hours. First high water is almost twice high than the second high water. Amplitude of the tide in the west coast sea where the proposed project is located ranges from 35 cm at neap tide to 75 cm at spring tide.

Wave Heights, Periods, Dominant Directions and other Ancillary Offshore and Nearshore Wave Parameters Directional wave measurements near the project area are not available. However the wave conditions in the area have been established by a wave transformation study. According to Directional Wave Climate Study of Southwest Coast of Sri Lanka, dominant wave characteristics of the project area can be summarized as follows.

Wave Frequency Wave frequency has not been measured but seasonal variations need to be taken care of. Such data are given below.

Waves, tides and ocean current regimes Much of the swell that affects Sri Lanka originates in the South Indian Ocean under the influence of westerly depressions and storms. This moves northwards and is felt most along the coasts of the Southern half of the island. Most large waves have a southerly component, but they rarely reach a height of over two metres. The highest waves are during the SW monsoon season, but the effective fetch is only about 800 km between the Maldives Island chain and Sri Lanka. During the SE monsoon, the northerly winds blow over short stretches of water from the North, and even when blowing across the bay of Bengal, are not steady enough to generate large waves. The period between tides is approximately 12 hours and is thus semidiurnal.

Air quality Heavy vehicle movements along Galle Road (A2 Motorway) and other bye-roads in the project area lead to high levels

(any of air pollutant emissions, such as dust including particulate matter, smoke including CO, CO2, NOx, SOx etc. Such air pollution pollution episodes can aggravate during peak hours when traffic movements are impeded. Fugitive dust particles could issues) escape into the atmosphere during construction activities and during transportation and subsequent storage and handling. Emanation of foul odors from the canal, especially during dry weather when water levels are low, could take place from rotting solid wastes thrown in the water and sewage discharges.

Noise level Existing ambient noise and vibration levels in the area correspond to highly urban and light industrial, businesses, hotel and and restaurants. There is also heavy traffic noise from Galle Road, a road which carries heavy traffic during peak hours vibration as well as during the night time. Intermittent high levels of noise and vibration levels are observed due to train (Any operations, which is also one of the busiest railway sections of the country. All these urban activities contribute to high anticipated noise levels in the project area. issues)

5.2 Ecological features – Eco-system components

Vegetation Since the canal's embankment (one side) was encroached, there is neither ground cover nor natural vegetation in the project area. The other side of the canal is bordered by a road. Therefore, the canal embankment is (trees, ground cover, dominated by man-made environment and no ecological sensitivity has been found. However, there are some aquatic vegetation) common domestic tree species such as Mangifera indica (Amba), Cocos nucifera (Pol), Terminalia catappa (Kottan), Leucaena leucocephala (Ipil Ipil), Musa x paradisiaca (Kesel), Tabernaemontana divaricata (Watu Sudda), Filicium decipiens (Pehimbiya), Carica papaya (papol) etc. that are found in the site. No aquatic vegetation was found in the canal. No endemic or threatened plant species were recorded in this rapid screening survey.

Presence of wetlands No wetland habitats within or in the vicinity of proposed project area are recorded.

Fish and fish The canal water has entirely been converted into black colour and appeared to be a dead water body during site habitats inspection, unless there are fish species adapted to extremely low dissolved oxygen levels. However, fish sampling was not carried out.

Birds (waterfowl, Acridotheres tristis (Common Myna), Columba livia (Rock Pigeon), Copsychus saularis (Oriental Magpie migratory birds, Robin), Turdoides affinis (Yellow-billed Babbler), Corvus splendens (House Crow), Streptopelia chinensis others) (Spotted Dove) are common birds observed during the rapid screening survey and no endemic or threatened animal species were recorded.

Presence of special Neither special designations nor sensitive zones have been identified within and immediate surroundings of the habitat areas (special proposed project area designations & identified sensitive zones)

Other features

Residential/Sensitive The land use on the left bank includes a wide road and middle income housing while the right bank is occupied Areas by underserved settlements, known as Ranjan Wijerathne pura. The access road is 3 – 4 m wide and this (Eg, Hospitals, settlement has been developed along the canal bank. At several places encroachments to the canal to create Schools) some gardening space was visible. A small Buddhist worship place was located behind the settlement and the main Buddhist temple Anandaramaya is located on Galle road adjacent to the canal. A well has been established near to the canal for bathing purpose.

No sensitive land uses such as hospitals, schools are located within the project area.

Traditional No any traditional economic or cultural activities are located within the project area economic and cultural activities

Archeological No archeological resources are located within the project area. resources

6. Public Consultation

Public consulted Consultation Date Details/Issues raised method

Ms. Chandani – Informal 19.12.2011 This housing scheme to the present status was developed in early 1990s by Resident at the Interviews reclaiming the canal bank area and over 100 families are living. Wastewater is beginning of the connected to the Municipal system and therefore no wastewater is discharged into underserved the canal. The canal pollution is mainly due to the upstream activities due to which settlement from people of this settlement are affected. If heavy vehicles are used on this road during the bridge the construction of the proposed Gabion wall, it would create a danger particularly to children who are always playing on the road.

Mr. G.D. Wiggin It is good to have the bank protection gabion wall similar to the opposite of the – resident living canal so that people will not encroach. It is good if the strip of land between the at the centre of gabion wall and the road is permitted for people to plant. It is necessary to take the settlement care during construction as the access road is always full of people.

Mr. Careem – The bathing well located on the strip between the road and the canal is heavily used Resident living at by the people for bathing and washing. During the construction activities care must the end of the be taken to protect the well and reserve that land for the public well. settlement

Mr. Ranjith – It is good to pave the road so that people can use it without any problem during Resident living at rainy period. Further it is requested that he strip between canal and road be given to the end of the people for cultivation of different crops. settlement

7. Environmental Effects and Mitigation Measures

7a. Screening for Potential Environmental Impacts

Screening question Yes No Significance of the effect Remarks

(Low, moderate, high)

1 Will construction and operation of the Yes Moderate – Positive impact Project involve actions which will cause physical changes in the locality Most of the interventions are carried out along the canal hence no physical changes in topography and landform is anticipated other than strengthening of the canal banks with gabion structures, landscaping, paving of foot walks and road surfaces.

2 Will the Project involve use, storage, Yes Low transport, handling or production of substances or materials which could be Transport of material and construction activities, harmful to human health or the environment including excavation, demolition of existing or raise concerns about actual or perceived structure and material piles will emit dust and risks to human health? fugitive particles which may pose a health hazard to vulnerable persons on temporary basis. The winds will be the triggering factor for such impacts though it is sporadic in nature.

3 Will the Project produce solid wastes during Yes Moderate construction or operation? During construction:

There will be general spoilage (construction debris) produced during the wall construction.

In addition, constructing gabions along the canal banks is expected to generate a moderate quantity of excavated material mixed with bottom sediment which will need to be disposed so as not to pollute the environment. Therefore, the sediment quality at the site (the proposed stretch of the canal) needs to be established prior to preparing the canal banks for gabion placing in order to determine the disposal method.

During operations

There will be material excavated along the canal, solid waste collected along canal banks etc which need regular collection and disposal appropriately. In addition, debris and sediments, floating matter and other solid waste carried by surface drainage can get collected along the canal that needs proper disposal methods. Regular cleaning of side drains and road will too generate such material. Culverts will also generate spoil material.

4 Will the Project release pollutants or any Yes Low hazardous, toxic or noxious substances to air? Rock breaking of boulders in the canal bed with chemicals might potentially release hazardous

substances. However, this can be carefully planned and carried out using rock breaking technologies specifically designed to operate in inner city area with written clearance and supervision of the competent authority (the Geological Surveys and Mines Bureau) to minimize the risk.

5 Will the Project cause noise and vibration or Yes Low release of light, heat energy or electromagnetic radiation? Removal of rock outcrops will cause some level of vibration during drilling.

The project activities will cause noise and vibration during demolition of temporary structure along the canal (not houses), excavation of trenches, compaction, and during transport of material etc. These impacts are temporary in nature and cause only inconvenience to the neighboring people only.

6 Will the Project lead to risks of Yes Low contamination of land or water from releases of pollutants onto the ground or into The canal bank/bed at the base of the gabions will surface waters, groundwater or coastal need to be excavated to build a consistent base layer wasters? for the structure. Such excavated material should be disposed of safely. Stock piling of excavated matter mixed with soft sediments, soil, debris and other material may release pollutants back into surface waters, groundwater or coastal waters. If the excavated material would contain sediments

contaminated with heavy metals, it would have to be appropriately handled and disposed in order to avoid any potential environmental and health risks to the residents and downstream marine ecosystems.

It is anticipated that additional canal bank clearing, levelling and other preparatory activities may be needed prior to and during the proposed improvement of storm water drainage and embankment strengthening works in the canal. The surface soil and the topmost layers of subsoil in the proximity of proposed site areas are either Red Yellow Podzolic soils with laterite or sandy clay in subsurface layers. Laterite soils consist of reasonable grade distribution and are relatively more stable than typical clayey soils while clayey and sandy soils with their smaller grain sizes are less resistant to erosion and washout. Therefore, in those cases where the preparation of the canal banks would intersect sandy clayey sub-surface layers once exposed due to removal of land cover, loosened due to excavation and harrowing or heaped and left uncovered, these soil layers may pose a threat to the environment by causing washout of fine material degrading water quality, removing soil fertility, silting of the canal, degrading soil stability and risking slope and bank failures.

On the other hand, proper construction practices like soil compaction and stabilization, turfing, maintaining naturally stable slopes, vegetation replanting, etc. will improve soil stability, reducing erosion risk and siltation effects during the construction phase and in the aftermath of project completion. Proper treatment and disposal of excavated material will help control the aforementioned associated adverse effects to a minimal and acceptable level.

7 Will the project cause localized flooding Low and poor drainage during construction Raised embankments and raised finish levels, stock Is the project area located in a flooding piling of construction debris and other materials location? may block existing drainage flow paths, causing flow stagnation and localized flooding effects.

However, the proposed project area is not a flood prone area and the ensuring of proper construction practices like provision of improved drainage network, maintaining naturally stable slopes, vegetation replanting/turfing, etc. will improve drainage conditions, reducing flood risk during the construction phase and in the aftermath of project completion.

8 Will there be any risks and vulnerabilities to Yes Low public safety due to physical hazards during Safety issue in terms of injuries caused by construction or operation of the Project? construction material, machinery and falling into excavated trenches by neighbors and commuters could be anticipated.

9 Are there any transport routes on or around Yes Low the location which are susceptible to congestion or which cause environmental The road on the left bank is wide enough to allow problems, which could be affected by the for construction equipment and machinery to be project? moved and hence impacts on residents and commuters on the left side of the canal from restriction to access will be minimum. The road that goes through the underserved settlement on the right canal bank is narrow and hence residents will be temporarily impacted by access restriction during right bank construction works. However, there are many connecting roads so that impact would be mitigated.

10 Are there any routes or facilities on or Yes Low around the location which are used by the public for access to recreation or other Use of road to access for residential areas and the facilities, which could be affected by the restaurants down the lane may be temporary project? affected but not completely cut off.

11 Are there any areas or features of high No Since project mainly deals with work along canals landscape or scenic value on or around the and roads, no impact is anticipated. location which could be affected by the

project?

12 Are there any other areas on or around the Yes Low location which are important or sensitive for reasons of their ecology e.g. wetlands, No such sensitive areas are found in the project area watercourses or other water bodies, the other than the coastal area. coastal zone, mountains, forests which could be affected by the project?

13 Are there any areas on or around the No No such areas are found. location which are used by protected, important or sensitive species of fauna or Since the area has already been interfered by human flora e.g. for breeding, nesting, foraging, activities, neither important nor sensitive species of resting, migration, which could be affected fauna or flora were found. by the project?

14 Is the project located in a previously No No such green-field is encountered. undeveloped area where there will be loss of green-field land

15 Will the project cause the removal of trees Yes Low in the locality? Some of the trees along the canal will be removed during construction of the gabion wall. Most of these trees are coconut or fruit bearing trees, which have been planted by residents in the canal demarcated bank reservation.

16 Are there any areas or features of historic or No Low cultural importance on or around the location which could be affected by the There are several religious places located along the project? canal but not be affected during construction.

17 Are there existing land uses on or around Yes Low the location e.g. homes, gardens, other private property, industry, commerce, The strip of land between the canal and the access recreation, public open space, community road is used by the community as an open space and facilities, agriculture, forestry, tourism, home garden area.(This space is the canal mining or quarrying which could be affected reservation and has been demarcated by the by the project? SLLRDC) During the construction of the Gabion wall this area will be affected. However after canal bank fixing with the Gabion wall, a much organized strip of land would be available to create a linear park along the canal for the use of the community.

18 Are there any areas on or around the Yes Low location which are densely populated or built-up, which could be affected by the The project area is densely populated. However the project? project will not create major impacts as the construction activities of the project is in the canal only the access road of the settlement would be impacted during transportation of building materials and construction equipment.

19 Are there any areas on or around the Yes Low location which are occupied by sensitive land uses e.g. hospitals, schools, places of There is a temple located along the Galle Road worship, community facilities, which could bordering the canal, which can be slightly affected be affected by the project due to noise generated during project activities.

20 Are there any areas on or around the Yes Low location which contain important, high quality or scarce resources e.g. groundwater, The canal is the only freshwater resources that surface waters, forestry, agriculture, exists (being closed to the sea the water quality in fisheries, tourism, minerals, which could be this stretch would make it moiré brackish) in the affected by the project? immediate project area. However, water in the canal is polluted due to a high concentration of urbanization with poor waste disposal practices. No significant additional impacts are expected due to proposed project components and intended construction activities.

21 Are there any areas on or around the Yes Dehiwala Canal and connected canals are highly or location which are already subject to moderately polluted depending on the seasonal pollution or environmental damage e.g. effects. However, the addition from the project where existing legal environmental seems to be very marginal or perhaps negligible. standards are exceeded, which could be affected by the project?

7b. Environmental Management Plan

Key project activities Potential Environmental Mitigation Measures Effects

Site preparation including Emission of dust Clearing of the canal bank for on-site material storage and provision of access roads, material access has to be carried out with the minimum use of machinery storage yards Generation of noise and sprinkling of water should be done appropriately.

Disturbance to pedestrian Using the existing access and storage yards maintained and movement and children who used by the State Engineering Cooperation for the present play on the road. bridge construction site should be used as much as possible, which will mitigate most of the impacts. Cutting off of mainly coconut trees along the canal Not to use heavy vehicles for transportation of building reservation during site materials, especially along the narrow access road on the right preparation canal bank.

Cutting of the coconut trees should be avoided as much as possible.

Temporary shifting & relocating Community will lose the Take minimum possible time for shifting of such services, not of utility posts (electricity & services for short periods. using heavy machinery on the road and keeping the community telecom). adequately informed of the project activities and possible Disturbance to pedestrian cutting off of utilities until the temporary relocation is movement of the road and completed. children who play on the road.

Key project activities Potential Environmental Mitigation Measures Effects

Canal bank/bottom excavation,, Excavation of the canal bank Sediment quality in the proposed section of the canal should be dewatering and disposal of bottom and bottom will be necessary established to understand the potential risk of contamination sediments where the gabions are to be and to determine the most suitable disposal method for the placed. This will generate a excavated debris and sediments. If contamination is established mixed spoilage consisting of according to accepted reference criteria, the following soil from the bank, solid mitigation measures are proposed to be implemented. waste and sediments from the (a) given the small volume of excavated matter (mixed with canal bed. Stock piling of sediments, solid and solid waste) that will be generated from such excavated material, soil, this stretch of the canal (300 m) the project should explore the debris and other material may possibility of using the two existing (and only) small semi block surface drainage paths engineered landfills in Sri Lanka at Mawanella and Nuwara causing localized flooding Eliya. Since the anticipated volume of excavated matter in this during constructional and case would be small, the project should be able to obtain the operational periods. necessary clearances from the Central Environmental Authority and the relevant Pradheshiya Sabhas to use their facilities, or If not properly stored and (b) dispose to Holcim industrial incinerator as alternative fuel. adequately covered, fine There will, however, be a cost involved in incinerating the material washout may material at Holcim which is presumably not significant given significantly contribute to the the small quantities. further degradation of surface water quality in the canal, If contamination is ruled out, the excavated matter along with inland reservoirs and sea other construction debris can be disposed to a landfill operated outfalls, while increasing risk by the Dehiwela/Mt Lavinia Urban Council. of slope failures, siltation and As the excavated matter, when it includes debris/sediments from the canal bed, would be watery/slurry, drying is

Key project activities Potential Environmental Mitigation Measures Effects

blockage of structures. necessary prior to transport to the disposal site, which will prevent leachate from leaking out during material handling and If not properly disposed, the transportation. Drying can be done at the banks of the canal excavated material will where the leachate will flow back to the canal. pollute water sources at If the sediment analysis confirms the canal to contain locations where it is disposed. contaminated sediments, the SLLRDC should carry out excavation in such a way that bottom sediments/debris is The low water table in the isolated (to the extent possible) from the rest of soil/spoilage, so project area may cause that quantities needing special disposal would be minimal. dewatering a crucial issue to Also, separating excavated soil from the bank from the rest of reduce pore pressure build up, the debris should be pursued if the soil is considered suitable as slope instability and transport a backfill for the gabions. of fines. Dewatering may also

be needed to carry out Proper and adequate dewatering should be ensured either using construction activities a proper monitoring schedule or using an automated without interruption in canal submersible pipe with float device to ensure site activities are embankments especially for uninterrupted due to seepage water. gabion wall construction and for other excavations during the periods of high Proper surface drainage and retention-detention capacity should groundwater table. be provided to safely remove pumped-up water from the site to Dewatering may cause a natural drainage to avoid in site ponding effects. surface ponding of removed water if proper drainage is not Construction activities can be planned during the periods of low allowed, especially when the water table to avoid excessive dewatering requirements and

Key project activities Potential Environmental Mitigation Measures Effects

upper soil layers are saturated save costs while reducing risks of slope failures, increased due to recent storm events. erosion, etc.

Possibility exists for changing Suitably arranged barge may be used where access through the water quality of the public existing roads is not available. well that is used by the community for bathing and Make sure that the bathing well would be re-instated after washing. dredging of that part of the project is over.

Smothering of benthic fauna Due to the changes in the debris or sediments, particularly morphology temporary smothering effect for benthic fauna may be possible but the impact is marginal.

Removal of temporary structures, Emission of dust The demolished materials and debris intended for temporarily debris, demolition waste, trees and storage should be properly stockpiled in most appropriate areas other solid waste along the banks Generation of noise in the site to avoid disturbance to site mobility, local traffic and stored away from drainage paths and suitably covered to avoid Disturbances to local traffic, washout. residents and other road-users during storage of material and Demolition has to be carried out with the minimum use of debris. machinery and sprinkling of water should be done appropriately. Loss of flower and fruit bearing trees planted by Suitably arranged barge may be used where access through people along the canal existing roads is not available. reservation strip. People will

Key project activities Potential Environmental Mitigation Measures Effects

lose such home gardens. Develop a landscape plan to maintain this strip a linear park and mobilize the community to look after the areas in front of their properties. The landscape plan should include a line of trees similar to the existing one along the protected canal bank.

Excavation for the gabion wall The construction of gabion Suitably arranged barge may be used where access through construction and coffer damming walls along the canal existing roads is not available. embankment for bank strengthening and Proper dewatering plan must be made and stability of coffer stabilization would require dams during rainy period must be ensured. Excavated material substantial excavation close must be carefully managed as highlighted earlier due to the to the existing earth potential risks involved. embankments. Such deep excavations in saturated weak Cracks that are likely due to vibration should be monitored in soil could result in collapsible the immediate neighborhood and if appear either rectification or vertical soil faces and compensation should be made. Hence a background crack increased susceptibility to survey in the immediate vicinity must be done prior to erosion and liquefaction commencement of the rock removal leading to bank failures.

Coffer damming is required to contain and divert movement of canal water and to provide a reasonably dry construction area for the

Key project activities Potential Environmental Mitigation Measures Effects

laying of screed concrete base (if required by design) and interlocking rubble work arrangement during gabion wall construction. The excavations in saturated soil may lead to failure if collapsible soil faces and excavated material will pose health and environmental risks if not properly handled and disposed.

Excessive vibration during hydraulic driving of sheet piles for coffer damming may weaken adjacent soil layers while it may also affect nearby foundations and other structures.

Removal of rock outcrops on canal Noise and vibration issues Approval from Geological Survey and Mines Bureau for bed. removal of the rock outcrops should be obtained. Rock removal should be planned and calculated not to impact the nearby structures from vibration. In any case if there is damage to

Key project activities Potential Environmental Mitigation Measures Effects

structures they will be rectified to the original level or compensation should be paid, as per the contract of the executing agent.

Material transport and storage Emission of dust due to The construction materials intended for temporary storage transport of material should be properly stockpiled in most appropriate areas in the site to avoid disturbance to site mobility, traffic and stored Disturbance to pedestrian away from drainage paths and suitably covered to avoid movement and the children washout. playing on the road Dust emissions should be controlled by wet spraying of construction sites and roads which are used for transportation of construction materials at regular intervals. Dust barriers if there are nearby houses and tarpaulin covering are mandatory on trucks / lorries which are used for transporting materials.

Vehicles should be maintained in good condition and regular maintenance needs to be done.

Suitably arranged barge may be used where access through existing roads is not available.

No heavy vehicles for transportation of building materials are encouraged. Building materials should be stored in places that will not disturb the accessibility to the community.

Key project activities Potential Environmental Mitigation Measures Effects

Construction of flow guidance Excavations beyond root Adequate measures should be taken to minimize damages to walls made of gabions at upstream depth may affect existing existing structures due to vibration by applying minimum side of the Railway bridge (length trees and deep excavations driving power. Adequate support should be provided to nearby of the new gabion wall is 671 m) may pose risk of soil slope trees when excavation depth exceeds root depth. failures, disturbances to

structures, etc. Proper alignment of rock wall and adequate bottom support should be maintained by following appropriate design Improper alignment of gabion guidelines and correct construction methodologies to ensure wall and inadequate bottom precise interlocking of the rubble work. Lined concrete flow support, as well as erosion of guide walls should be used where necessary to control bottom soil loosening bank support and side erosion when the gabions walls are exposed to through will lead to weakening of the flow. interlocking of rubble used causing immature failure of Take adequate care in handling building materials so that no gabion structure before its accidents happen harming the people. intended design life.

Pedestrian movement and the children playing on the road will be disturbed, when the building materials are handled using the road. However this impact is very short time as this impact will not exists through out the

Key project activities Potential Environmental Mitigation Measures Effects

canal at once. At a given time a small section will be affected.

Reinstatement of storm water Erosion of soil adjacent to Storm water connections across the gabion walls should be drainage connections (Hume structures will lead to provided using hume pipes or box culverts of adequate size pipes) to Dehiwela Canal through loosening of bank support. according to pre-determined design storm events and return gabion walls and introduction of This will weaken the periods. catch pits wherever required interlocking of rubble used causing immature failure of Catch pits should be provided at suitable spacing to remove

gabion structure before its excessive fines through settlement. Catch pits should be intended design life. regularly cleaned and maintained in proper order. Fines Blockage due to removed should be properly disposed to avoid them joining accumulation of fines due to flow paths again. cross drainage flows will lead to pore pressure build-up behind the gabion structure, leading to unbalanced pressure forces, making the

structure susceptible to failure by toppling.

Backfilling of banks behind the Selection of below grade fill Backfill materials should be selected after proper analyses of gabions, turfing and replanting of materials will not attain soil characteristics. Adequate compaction should be applied to trees required soil strengths after

Key project activities Potential Environmental Mitigation Measures Effects

compaction and will lead to attain required soil strengths in banks and embankments. differential settlements causing the gabion walls to The construction materials intended for temporarily storage misalign and fail. should be properly stockpiled in most appropriate areas in the site to avoid disturbance to site mobility, traffic and stored Lose of vegetation (flowery away from drainage paths and suitably covered to avoid plants, vegetables, coconut washout. trees etc) Suitably arranged barge may be used where access through existing roads is not available.

Make such spaces available for development of a linear park for public use and get the community involved in voluntary maintenance.

Reinstatement of maintenance Lack of side drains and toe Side drains and toe drains of adequate design sizes should be road (width: 3 m) and construction drains of adequate sizes provided alongside of the maintenance roads and proper cross of road side drain and cross alongside of the maintenance drainage structure should be provided where necessary to divert drainage to the canal. roads will lead to localized accumulated flows to the main drains. ponding in road pavements and weakening of soil sub- The construction materials intended for temporarily storage base underneath. should be properly stockpiled in most appropriate areas in the site to avoid disturbance to site mobility, traffic and stored Pedestrian movement and the away from drainage paths and suitably covered to avoid children playing on the road washout. will be disturbed. Especially

Key project activities Potential Environmental Mitigation Measures Effects

children will be subjected to Suitably arranged barge may be used where access through accidents if construction existing roads is not available. equipment are not handled taking extreme care. Make the community adequately educated about the project activity. Exhibit sign boards in both Sinhala and Tamil languages at appropriate locations. Organize the re-statement activities in such a way so that alternate ways of accessibility to houses are made sure.

8. Conclusion and Screening Decision

Summary of environmental effects: Assuming that all mitigation measures are implemented as proposed, the following effects can be predicted

Key project activities Potential Environmental Effects Significance of the environmental effect with mitigation in place

NS- Effect not significant, or can be rendered insignificant with mitigation SP - Significant positive effect SN - Significant negative effect U - Outcome unknown or cannot be predicted, even with mitigation NA – Not applicable

Site preparation including Emission of dust NS provision of access roads, material storage yards Generation of noise NS NS Disturbance to pedestrian movement and children who play on the road.

During site preparation domestic trees will be NS cut-off.

Temporary shifting & relocating Community will lose the services for short NS of utility posts (electricity & periods. telecom).

Disturbance to pedestrian movement of the road NS and children who play on the road.

Canal bank/bottom excavation, Excavation of the canal bank and bottom will dewatering and disposal of be necessary where the gabions are to be bottom sediments SN placed. This will generate a mixed spoilage consisting of soil from the bank, solid waste

and sediments from the canal bed. Stock piling of such excavated material, soil, debris and other material may block surface drainage paths causing localized flooding during constructional and operational periods.

If not properly stored and adequately covered, fine material washout may significantly SN degrade surface water quality in canals and the sea outfalls, while increasing risk of slope failures, siltation and blockage of structures.

If not properly disposed, the material excavated from the canal banks and bottom will pollute SN water sources at locations where it is disposed.

The low water table in the area may cause dewatering a crucial issue to reduce pore NS pressure build up, slope instability and transport

of fines. Dewatering may also be needed to carry out construction activities without

interruption in canal embankments especially for gabion wall construction and widening, and for other excavated areas during the periods of high groundwater table.

Dewatering may cause surface ponding of removed water if proper drainage is not NS allowed, especially when the upper soil layers are saturated due to recent storm events.

Possibility exists for changing the water quality NS of the public well that is used by the community for bathing and washing.

Smothering of benthic fauna NS

Removal of temporary Emission of dust NS structures, debris, demolition waste and other solid waste Generation of noise NS along the banks Disturbances to local traffic and pedestrians NS

during storage of material and debris.

Many people have planted flowery plants, vegetables, banana and coconut trees on the NS strip between the road and the canal. People will lose such home gardens.

Excavation for the gabion wall The construction of gabion walls along the NS construction and coffer damming canal embankment for bank strengthening and stabilization would require substantial excavation close to the existing earth embankments. Such deep excavations in saturated weak soil would result in collapsible vertical soil faces and increased susceptibility to erosion and liquefaction leading to bank failures.

Coffer damming is required to contain and NS divert movement of canal water and to provide a reasonably dry construction area for the laying of screed concrete base (if required by design) and interlocking rubble work arrangement during gabion wall construction. The excavations in saturated soil may lead to failure if collapsible soil faces and excavated material will pose health and environmental risks if not properly handled and disposed.

Excessive vibration during hydraulic driving of NS sheet piles for coffer damming may weaken adjacent soil layers while it may also affect nearby foundations and other structures.

Removal of rock outcrops on Noise and vibration issues may occur due to NS canal bed using chemical chemical blasting. blasting.

Material transport and storage Emission of dust due to transport of material NS

Pedestrian movement and the children playing NS on the road will be disturbed.

Construction of flow guidance Excavations beyond root depth may affect NS walls made of gabions at existing trees and deep excavations may pose upstream side of the Railway risk of soil slope failures, disturbances to bridge (length of the new gabion structures, etc. wall is 671 m) Improper alignment of gabion wall and

inadequate bottom support, as well as erosion NS of soil loosening bank support will lead to weakening of the interlocking of rubble used causing immature failure of gabion structure

before its intended design life. NS Pedestrian movement and the children playing on the road will be disturbed, when the building

materials are handled using the road. However this impact is very short time as this impact will not exists though out the canal at once. At a given time small section will be affected.

Reinstatement of storm water Erosion of soil adjacent to structures will lead NS drainage connections (Hume to loosening of bank support. This will lead to pipes) to Main Drain through weakening of the interlocking of rubble used gabion walls and introduction of causing immature failure of gabion structure catch pits wherever required before its intended design life. Blockage due to accumulation of fines due to cross drainage

flows will lead to pore pressure build-up behind the gabion structure, leading to unbalanced pressure forces, making the structure susceptible to failure by toppling.

Backfilling of banks behind the Selection of below grade fill materials will not NS gabions, turfing and replanting attain required soil strengths after compaction of trees and will lead to differential settlements causing the gabion walls to misalign and fail.

Loss of planted species (flowery plants, NS vegetables, coconut trees etc.)

Reinstatement of maintenance Lack of side drains and toe drains of adequate NS road (width: 3 m) and sizes alongside of the maintenance roads will construction of road side drain lead to localized ponding in road pavements and cross drainage to the canal. and weakening of soil sub-base underneath.

Pedestrian movement and children playing on the road will be disturbed. Especially children NS will be subjected to accidents if construction equipment are not handled taking extreme care.

9. Screening Decision Recommendation:

Final Majority of the potentially adverse effects can be classified as general recommendation construction related impacts and are mitigatable with known technology. Public concern does not warrant further assessment. Therefore, a stand alone Environmental Assessment is not required and, the Environmental Management Plan provided with this report would be sufficient to mitigate the identified impact.

The following specific recommendations given in the EMP are of utmost importance to be implemented.

A sediment quality testing and the quantification of the excavated material that will be removal must be undertaken by the SLLRDC. Depending on the results of the sediment quality disposal method should be determined as specific in the EMP. If not the excavated matter can be stored in a suitable site and subsequently disposed to a municipal waste dump. Some parts of the excavated material such as soil from canal banks could be used by the SLLRDC for backfilling. But the suitability of the material for such a purpose needs to be confirmed.

Safe handling of material excavated from the canal including transport must be implemented.

Construction debris management plan must be worked out and implemented. Vibration monitoring survey must be undertaken prior to breaking the rock outcrops.

Heavy vehicles i.e., large trucks, should not be allowed for material transport. Only small vehicles such as tractors, carts will be promoted.

Construction activities should be encouraged during dry season so that impacts due to water levels will be minimal.

10. EMP implementation responsibilities and costs

The overall responsibility of ensuring compliance with safeguard requirements for the sub- project lies with the SLLRDC. Specifically, it will be responsible for undertaking sediment quality testing in the proposed section of the canal, estimation of excavated material quantities generated and guiding the contractor on suitable disposal methods. The contractor will be responsible for implementing all other provisions in the EMP that relate mostly to good construction planning, site management and public safety practices.

The additional cost involved in implementing the EMP relate to (a) undertaking sediment quality tests and (2) disposal of excavated material if contamination is established. Environmental monitoring will be carried out largely through compliance monitoring using the checklist provided in the EMF by the Environmental Officer of the SLLRDC and the contractor jointly.

As such, the only additional costs envisaged are explained below:

Item Cost (Rs) Implementation Responsibility

Sediment quality testing – 2 120,000 SLLRDC samples

For following physical and chemical parameters

Particle size distribution, pH, Sulphate, Chloride, Total Organic Carbon, Fe, Cd, Ni, Zn, Cu, Cr, Al, Pb, Mn, Ca, Mg, Hg, As and leachability test for heavy metals

The testing will be done in early January 2012

Disposal of excavated material The cost of mitigation is hard to Contractor estimate at this stage as the quantities of material, quality of pollutants/substances, detailed methodologies, and sites for disposal etc. are undecided. The consultant will work with the SLLRDC for estimating the mitigation cost once results of the sediment quality test

Screening report completed by Date

Dr. Mahesh Jayaweera, Team Leader

University of Moratuwa

Tel: 0777320590 email: [email protected] Signature

Name/Designation/Contact information

Screening report reviewed by Date

Name/Designation/Contact information Signature Approved by Date

Name/Designation/Contact information Signature

9. Details of Persons Responsible for the Environmental Screening

(1) Dr. Mahesh Jayaweera, PhD, BSc in Civil Eng (Hons.), MIE (SL), CEng. – Team Leader (Overall coordination and planning) Experience: Team Leader/Consultant/Expert for more than 60 EIA and IEE studies during the past 15 years

(2) Professor Mrs. Niranjanie Ratnayake, BSc in Civil Eng (Hons.), MSc, FIE (SL), CEng. – Environmental assessment specialist Experience: Team Leader/Consultant/Expert for more than 40 EIA and IEE studies during the past 20 years

(3) Dr. Jagath Manatunge, PhD, MSc, DIC, BSc in Civil Eng (Hons.), MIE (SL), CEng. – Environmental Engineer (Noise, Water, Wastewater, Vibration, Air) Experience: Team Leader/Consultant/Expert for more than 40 EIA and IEE studies during the past 12 years

(4) Dr. Lalith Rajapakse, PhD, MEng, BSc in Civil Eng (Hons.), MIE (SL), CEng. – Civil Engineer (Hydrology, Geology, other civil engineering aspects) Experience: Consultant/Expert for more than 20 EIA and IEE studies and assignments mainly related to hydrological during the past 6 years

(5) Mr. Hemantha Jayasundara, BA (Hons.), MSc (Town and Country Planning), PG Dip in Urban Development, PD Dip in Environmental Sci. –Urban Planner Experience: More than 20 years as a Consultant/Expert on Urban and Regional Planning, Urban Design, Disaster Management, Environmental Management, Projects Management etc.

(6) Dr. Anusha Kasige, PhD, MSc, BSc in Zoology – Ecologist (Flora, Fauna, Ecosystems) Experience: more than 15 EIA and IEE studies and ecological studies during the past 5 years

References

Cooray, P.G.(1984). An introduction to the geology of Sri Lanka (Ceylon), with a foreword by John Sutton, National Museums of Sri Lanka Publication, Colombo, Sri Lanka.

Greentech (2011). Environmental Assessment Final Report for Metro Colombo Urban Development Project, Vol. 1, Greentech Consultants (Pvt) Ltd., Colombo 5, Sri Lanka.

Annex 1:

Photographs of some of the important locations

Photographs of Dehiwala Canal

0 0 Fig.A‐ 1. Lat‐6.862810 Lon‐79.860130 Fig.A‐ 2. Lat‐6.86293 Lon‐79.86295

Fig.A‐ 3. Lat‐6.862610 Lon‐79.861660 Fig.A‐ 4. Lat‐6.862620 Lon‐79.861670

0 0 0 0 Fig.A‐ 5. Lat‐6.86272 Lon‐79.86070 Fig.A‐ 6. Lat‐6.86304 Lon‐79.86308

0 0 Fig.A‐7. Lat‐6.862650 Lon‐79.860020 Fig.A‐ 8. Lat‐6.86268 Lon‐79.86004

Fig.A‐ 9. Lat‐6.862680 Lon‐79.861370 Fig.A‐ 10. Lat‐6.862750 Lon‐79.860930

Figure A-1. A location at the canal where wastewater is discharged from a vehicle service station

Figure A-2. A general view of the canal

Figure A-3. Coconut trees along the bank of the canal, which needs removal

Figure A-4. A pave section of the road that runs along the canal bank

Figure A-5. Debris collected along the canal banks

Figure A-6. Garbage and debris collected at the banks of the canal

Figure A-7. The railway line that crosses the canal and the location of the sea outfall

Figure A-8. A general view of the canal towards upstream from railway line

Figure A-9. A smaller drainage canal connected to Dehiwala Canal

Figure A-10. Debris collected at the banks of the canal

Fig.A‐ 11. Lat‐6.862940 Lon‐79.862970 Figure A-11. The bridge across the Galle Road

Annex 2: Detailed drawings of project components

PLATE NO: 100 TEMPLE

GABIONS 399390.00E 399290.00E

484930.00N 484930.00N

600 Ø HP Ø 600 WALL

From Colombo From CONC. POST & FENCE DRAIN

Dehiwala Bridge

Galle Raod Galle H PROPOSED GABION WALL TYPE - II & 3m WIDE WALKWAY & SIDE DRAIN

P P H P Road IP EP IP 399240.00E Road Drain IP W

Road P W 484880.00N EP TP EP BM -D3/GPS ELV. 8.437M

DP Road 3+324 at 72 DC-CS P Dia. 0.6m DP Well IL 0.702m

P Drain HP EP EP

CB TP W

W DP MDN

P HP Dia. 0.3m

450Ø IL 0.395m W Dehiwala To

Road

Bo Tree P Drain W DP P PROPOSED GABION WALL TYPE - I P & 3m WIDE WALKWAY & SIDE DRAIN EP P TP P P HP U

EP TP MDN 3+349 at 73 CS - DC 1200Ø Dia. 0.3m HP 399440.00E P IL 0.472m P Dia. 0.4m 484830.00N

Drain P IL 0.900m DC - CS 74 at 3+374 at 74 CS - DC P W Gabion Wall Road Well P P TP P EP P Road U TP EP

Reservation P 3+418 at 75 CS - DC 600Ø HP

Dia. 0.4m IL 1.526m

20405

P Dia. 1.0m IL 0.920m HP

MDN

Gabion Wall 399390.00E

W B W To Galle Road 484780.00N

NOTES : MDN TP 1. This drawing is based on survey made by Hydrodynamics & Road Geophysical Survey (PVT) ltd in September 2011. TP 2. All dimenstions are in metres and all the levels are based on MSL unless otherwise stated .

3. Only canal banks and main features closely associated with the PLAN canal banks are indicated.

4. All details shall be verified by the contractor on site as required for his correct pricing , planning and execution of the work.

5. This drawing should be read in conjunction with Dwg. Nos.

DC - CS 76 at 3+480 at 76 CS - DC E - DC / P / 9.101 - 9.108 , E - DC / P / 9.110 , E - DC / CS / 9.201 - 9.202 , E - DC / LS / 9.301 - 9.304

DC - CS 77 at 3+527 at 77 CS - DC PROPOSED GABION WALL TYPE - I LEGEND

Proposed Bank 399240.00E

Existing Bank 484730.00N BY DATE CHKD AUTHO Existing storm water drainage hume pipes - not to be touched. Existing storm water drainage hume pipes - to be replaced by a new pipe. REVISION DATE AUTHORITY New storm water drainage connection. GOVERNMENT OF THE DEMOCRATIC Catch Pit (CP) SOCIALIST REPUBLIC OF SRI LANKA REFERENCE MINISTRY OF DEFENCE SRI LANKA LAND RECLAMATION AND DEVELOPMENT CORPORATION. EP Electric Post NO: 03, SRI JAYAWARDENAPURA MAWATHA , WELIKADA , RAJAGIRIYA. TP Telephone Post PROJECT : DP Dranaige Pit METRO COLOMBO URBAN DEVELOPMENT PROJECT HP Hume Pipe COMPONENT 1 ( STAGE - 1 ) FLOOD MITIGATION AND WATER FRONT MANAGEMENT IP Iron Post {Funded by World Bank} CB Cement Bank DEHIWALA CANAL W Wall TITLE : P Permanent Building PLAN SHEET - SHEET 9/10 B Bank SUBD : RECOMMD : APPROV : U Indifinite Boundary DESI : DRAWN : Nadeesha CHKD : PE Pipe Edge MDN Masonary Drain SCALE : 1:500 DATE : DWG.No : E - DC / P / 9.109 PLATE NO: 101 398940.00E 399090.00E 399190.00E

484880.00N 484880.00N 484880.00N

BRIDGE OVER DEHIWALA CANAL AT DEHIWALA FOR PROPOSED GABION WALL TYPE - II MARINE DRIVE EXTENSION & 3m WIDE WALKWAY & SIDE DRAIN ( 32.18m x 11.7m )

PROPOSED GABION WALL TYPE - I & 3m WIDE WALKWAY & SIDE DRAIN

BM-D1/GPS Breakwater

Road ELV. 2.818M Road P P P P P P P P P P P P P P P P P P P P P EP P EP TP P Beach EP P

TP Road U P Road

U P Drain B P HP EP P Breakwater W P Dia. 0.8m P 900Ø P Sea Outfall IL 0.983m P P P P Bridge EP P P P P P P P P P P P HP

600Ø EP Road Dia. 0.4m EP Dia. 1.2m W IL 0.807m IL 1.038m Dia. 1.0m B HP IL 1.070m HP B Dia. 0.8m

W IL 1.282m Beach HP B DEHIWALA ELA CB

U U Road B EP TP MDN TP EP EP TP PE TP Dia. 0.6m B MDN IL 0.793m CB PE HP BM-D2/GPS EP From Houses TP ELV. 2.835M MDN Road

DC - CS 83 at 3+787

DC - CS 84 at 3+827 at 84 CS - DC TP DC - CS 82 at 3+777 at 82 CS - DC

From Houses

MDN

DC - CS 81 at 3+727

DC - CS 80 at 3+677

DC - CS 79 at 3+626

PROPOSED GABION WALL TYPE - I

DC - CS 78 at 3+576 398890.00E 399140.00E 398990.00E

484730.00N 484730.00N 484730.00N

PLAN

LEGEND

Proposed Bank

Existing Bank BY DATE CHKD AUTHO Existing storm water drainage hume pipes - not to be touched. Existing storm water drainage hume pipes - to be replaced by a new pipe. REVISION DATE AUTHORITY New storm water drainage connection. NOTES : GOVERNMENT OF THE DEMOCRATIC Catch Pit (CP) 1. This drawing is based on survey made by Hydrodynamics & SOCIALIST REPUBLIC OF SRI LANKA Geophysical Survey (PVT) ltd in September 2011. REFERENCE MINISTRY OF DEFENCE SRI LANKA LAND RECLAMATION AND DEVELOPMENT CORPORATION. 2. All dimenstions are in metres and all the levels are based on MSL EP Electric Post unless otherwise stated . NO: 03, SRI JAYAWARDENAPURA MAWATHA , WELIKADA , RAJAGIRIYA. TP Telephone Post 3. Only canal banks and main features closely associated with the PROJECT : DP Dranaige Pit canal banks are indicated. METRO COLOMBO URBAN DEVELOPMENT PROJECT HP Hume Pipe COMPONENT 1 ( STAGE - 1 ) FLOOD MITIGATION AND WATER FRONT MANAGEMENT 4. All details shall be verified by the contractor on site as required {Funded by World Bank} IP Iron Post for his correct pricing , planning and execution of the work. CB Cement Bank 5. This drawing should be read in conjunction with Dwg. Nos. DEHIWALA CANAL W Wall E - DC / P / 9.101 - 9.109 , E - DC / CS / 9.201 - 9.202 , TITLE : P Permanent Building E - DC / LS / 9.301 - 9.304 PLAN SHEET - SHEET 10/10 B Bank SUBD : RECOMMD : APPROV : U Indifinite Boundary DESI : DRAWN : Nadeesha CHKD : PE Pipe Edge MDN Masonary Drain SCALE : 1:500 DATE : DWG.No : E - DC / P / 9.110