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. Pollution within the is mainly caused by sewage disposal, as such, occurrence of heavy metals at concentrations that will affect aquatic biota or people living in the area is not expected. However, sediment sample analysis at selected locations will need to be done. 7 Will the project cause localized flooding and poor drainage during construction Is the project area located in a flooding location? Low Annexures 4 a to 4 c indicate that the present canal sections are adequate to withstand 5- and 10-year design return period peak discharges under existing land use conditions. However, some low-lying embankment sections will be subject to overtopping and undergo flooding under 10-year design return period peak flow discharge and future (2025) land use conditions, presumably due to partial blockage to the flow at some bridge locations with improperly aligned cross drainage openings and
the low-lying areas within the project area. Therefore, the designs should be cross checked for at least a 25-year design return period flood event and consequences should be identified and addressed to minimize damages. 8 Will be any risks and vulnerabilities to public safety due to physical hazards during construction or operation of the Project? Yes Low Safety issue in terms of injuries caused by construction material, machinery and falling into excavated trenches by neighbors and commuters could take place. 9 Are there any transport routes on or around the location which are susceptible to congestion or which cause environmental problems, which could be affected by the project? Yes Low The access roads are wide enough to allow for construction equipment and machinery to be moved and hence impacts on residents and commuters near the canal from restricted access should be looked into. The residents will be temporarily impacted by access restriction during construction works. Where the bridges are located, traffic on the main road will be impacted when construction commences. However, there are many connecting roads so that impact would be mitigated. 10 Are there any routes or facilities on or around the location which are used by the public for access to recreation or other Yes Low to moderate Realignment of bridges, provision of culverts and road side drains will disruptions to road users, both vehicular traffic and pedestrians. Traffic on
15 Will the project cause the removal of trees in the locality? Yes Low It has been decided that mature large trees on the canal banks will be preserved and incorporated into the canal bank design during construction of the gabion walls. Removal of some vegetation would be unavoidable though. Where soft embankments are constructed (which is more in length than gabions) trees will not be removed. However in the case of maintenance road construction there will be a possibility of a few trees being removed which needs to be monitored but they seem to be common trees with no or low economic values. 16 Are any areas or features of historic or cultural importance on or around the location which could be affected by the project? No are no historic or culturally important areas or features around the project location. 17 Are existing land uses on or around the location e.g. homes, gardens, other private property, industry, commerce, recreation, public open space, community facilities, agriculture, forestry, tourism, mining or quarrying which could be affected by the project? Yes Moderate Where land is acquired for maintenance road, home gardens of those living bordering the canal will be affected.
surface waters, forestry, agriculture, fisheries, tourism, minerals, which could be 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 any areas on or around the location which are already subject to pollution or environmental damage e.g. where existing legal environmental standards are exceeded, which could be affected by the project? Yes Low Moragoda Ela and connected canals are highly or moderately polluted depending on the seasonal effects. However, the addition from the project seems to be very marginal or perhaps negligible. 7. Environmental Management Plan Key project activities Potential Environmental Effects Mitigation Measures Site preparation including provision of access roads, material storage yards Emission of dust Generation of noise Disturbance to pedestrian movements and children who play on the road Minimize use of heavy machinery in site clearance work, preparation of temporary access roads, storage sheds and storage areas. Select bare lands along the canal trace for storage of material and equipment should be strongly considered to avoid haphazard storage along the construction sites. Provision of proper site drainage, fencing and covering of material Should be ensured. Sprinkling in an appropriate manner to reduce dust.
Avoid using heavy machinery for transport of construction material along narrow access road along the banks of the canal Avoid cutting of trees unless they obstruct construction of designed- structures. Express approval of Project Manager to be obtained before cutting and removal of any tree exceeding 300 mm girth. Temporary shifting & relocating of utility posts (electricity & telecom). Community will lose the services for a short period Disturbance to pedestrian movement on the access road and children playing on the road Interact and communicate with relevant Govt. Agencies, Local Govt. Authorities and Employer to arrange for relocation as early as possible and with minimum disturbance to public. To erect barriers/ draw barricade tape to ensure security of public during removal/ relocation of utility posts. Canal bank/bottom excavation,, dewatering and disposal of bottom sediments Excavation of banks and bottom will generate a mixed spoilage consisting of soil from the banks, solid waste and sediments from canal bed Stockpiling of such excavated material may block surface drainage paths causing localized flooding during construction period. If not properly stored and adequately covered washout of fine material may Silt and sediment quality in the canal should be established to understand the potential risk of contamination by heavy metals (and the leachability) and to determine the most suitable disposal method for the excavated debris and sediments. If contamination is established according to accepted reference criteria, the following mitigation measures are proposed to be implemented. (Note: Sri Lanka does not have regulatory standards for sediment quality. Under MCUDP it was decided to use the ANZECC interim standards for sediment quality)