MGC’s recent contribution on safety procedure for rehabilitation of reservoir dams

Consultants Private Limited (MGC) submitted another set of six environment assessment reports to the Dam Safety and Water Resources Planning Project (DSWPP) funded by the World Bank, in October 2015. The environmental assessment is a prerequisite for rehabilitation of a reservoir dam. Timely rehabilitation of a dam prevents its breaching that may otherwise cause a disaster of losing lives and property bundled in the downstream. The six assessments include the reservoirs of Ulhitiya-Rathkinda, Henanigala, Pimburaththawa, Bambaravana, Pussalavinna and Moogammana. The reservoirs are operated by the Mahaweli Authority of Sri Lanka, the Ministry of Mahaweli Development and Environment. Thus, MGC continued to assist the rehabilitation of reservoirs undertaken by the DSWRPP.

The objectives of the DSWRPP include improvement of water resources management, reduction of water-induced hazards to the public and enhancement of the effectiveness of water-related investments. Accordingly, the DSWRPP has identified 32 dams of irrigation reservoirs with structural deficiencies due to their ageing. The ageing has reduced the operational efficiency in terms of intake, storage and distribution of irrigation water and has threatened the safety of the population and the socio-economic infrastructure of the downstream. Therefore, the intervention of the DSWRPP has become essential.

MG Consultants, the management staff of each reservoir and the beneficiary groups have verified the activities required for rehabilitation, calculated the time needed for the rehabilitation and described the anticipated negative impacts to the surrounding. Further, the possible impacts have been classified in terms of physical, ecological and socio-economic environments. The final product, of the six environmental assessment studies, consist of site-specific environmental management plans, options in mitigation measures, rehabilitation alternatives and a monitoring programme to achieve overall environmental sustainability.

Each report proposes a set of procedure that would make the least loss to the affected population during the rehabilitation of the dam and related structures. The public in the vicinity of the rehabilitation, especially the farming and fishing communities will be informed of the potential temporary disturbances to their livelihood. The seasonal behaviour of the reservoir in terms of the level of water will be maintained as much as possible by timing the rehabilitation activities and planning and completion of the construction work, taking the least period of time. With the inclusion of the concerns and wellbeing of the indigenous animals and plants potentially affected by the rehabilitation, the reports have been made comprehensive.

All of the major dams in Sri Lanka have been intensively inspected by the DSWAPP for potential risks. Among them, 32 dams are at high risk and require renovation; while the other dams need basic maintenance for safety. The six environmental assessments completed have contributed towards the rehabilitation of seven dams and related structures.