Environmental Impact Statement for the Alimit Hydroelectric Power Plant (Alimit HEPP, 2019)

An Environmental Impact Statement (EIS) was prepared for the 140MW hydroelectric power plant (HEPP) in the Municipalities of Aguinaldo, Lagawe, Lamut, and Mayoyao in Ifugao. The project has two major generation components, the Alimit HEPP which is a 80 m dam with a total 120MW energy generation and the Olilicon HEPP which is a 14 m high weir with a 20MW energy generation. This project is in line with the Department of Energy’s goal to accelerate and develop more sources of renewable energy to meet Luzon’s electricity demand.

As part of the preparation of the EIS, Aperçu Consultants, Inc. was engaged in the following activities:

Land Module

Land Use

Reviews of the Comprehensive Land Use Plan (CLUP) of the covered municipalities, comparison of project site aerial view and NAMRIA maps, ground truthing, and  follow up site surveys were done to ensure the compatibility of the project with the land use of the area.

Geology & Geomorphology

Assessments of the geological characteristics and natural hazards of the area in relation to the siting and development of the project was done to evaluate the capacity of rocks to support the dam and related structures with consideration to hazards such as earthquakes, erosion, and mass movements. 

Pedology

Literature review and laboratory analyses of the soil was done to assess the soil erosion potential of the project site. Each soil unit was also rated for its erosion susceptibility by assessing contributing factors such as rainfall, slope erodibility, vegetation or land use, and slope. 

Terrestrial Ecology

Flora and faunal assessments were done to identify critical species (endemic, threatened, or vulnerable). Results were used to assess the project’s impacts during its construction and operational phases as well as provide preventive and mitigating measures to the identified potential impacts. A biodiversity management plan was also developed for this project. 

Water Module

Hydrology and Hydrogeology

The physical characteristics and flows of the Alimit River and Ibulao River were identified based on the drainage system and delineated watersheds. Potential project impacts due to changes in drainage morphology, potential to induce flooding, reduction in river volumetric flood, and depletion of water resources/water use competition were assessed. Results from the assessments were used to develop management and mitigating plans for the potential adverse impacts.

Water Quality

Physico-chemical characteristics of the upstream and downstream of Rivers Alimit and Ibulao were done. The water quality survey provided information on the baseline conditions as well as determined potential impacts of the project and its activities to the surface and groundwater quality. Management and mitigating measures of potential impacts were based on the water quality assessments.

Freshwater Ecology

Baseline surveys of the freshwater environment in Rivers Alimit and Ibulao included algae, zooplankton, benthic macroinvertebrates, and fish. Fisheries data and general uses of water sources were also identified through interviews with locals. These assessments were used to determine potential impacts of the project and its activities as well as provide suitable mitigating and preventive measures.

Air Module

Climate & Meteorology

Existing meteorological conditions and the potential impacts of the Alimit HEPP project to local climate and greenhouse gas emissions were identified. Mitigating measures were developed for the identified potential impacts on the local community and in relation to climate change. 

Ambient Air Quality

Total suspended particulates (TSP) and particulate matter of 10 micrometers (PM10) were measured and compared to various air quality standards. Air dispersion models were done to project maximum ground-level concentrations of TSP and PM10 as well as air pollution “hotspots” during the construction phase. Results were used to identify mitigating measures to minimize potential impacts on the ambient air quality.

Ambient Noise

Existing noise conditions were measured while noise impacts of the project and its activities were projected. Mitigating measures were recommended for the construction and operation phases of the project.

People Module

Baseline socio-economic, health, cultural heritage, and traffic of the province, municipalities, and barangays affected by the Alimit HEPP project was identified. Assessments focused on the people living in the direct impact area as well as resources that would be significantly affected by the project. Results were used to identify suitable social impact mitigating measures as well as identify benefits of the project to the local community.

Environmental Risk Assessment

This assessment focused on determining the probability of occurrence of accidents and their magnitude. Specific assessments for potential dam break  (i.e. breach or rupture) were also done. Possible mitigating measures were provided for the various risks identified in this assessment.

The Environmental Compliance Certificate (ECC) for the project was issued by the Department of Environment and Natural Resources (DENR) in February 2019 with ECC Reference No. ECC-CO-1603-0012. The ECC is available at the following link.