Bhlaraidh Reservoir

Project: Bhlaraidh Reservoir Desilting Works
Location: Bhlaraidh, Glenmoriston
Client: Scottish and Southern Energy Renewables

This complex and environmentally sensitive project involved the desilting of the Bhlaraidh Reservoir to restore operational capacity and ensure long-term functionality of the intake structure. The works were delivered with a strong focus on environmental protection, water management, and site reinstatement.

Mobilisation of specialist plant and equipment took place at the remote reservoir site, including a long-reach excavator and hydraulic pumping systems. Vegetation, including heather and peat, was carefully stripped and set aside for reuse. A temporary access road was constructed into the reservoir basin using 6F2 crushed material and rock armour, with a staging platform created for pump installation.

Three-stage settlement pools were formed in a natural hillside depression. These were reshaped using an excavator, lined with geotextile membrane and damp-proof membrane (DPM), and bunded to contain pump discharge and promote sediment settlement. Silt fencing and heather pools were installed between the settlement area and the adjacent river. In-river protection included silt fencing and hay bales downstream of the works, while silt blockers were installed at the outlet from the stilling basin to prevent downstream contamination.

Overland pipework was laid between the reservoir and settlement pools. A hydraulic pump head suspended from the long-reach excavator was used to dredge silt from the reservoir. As silt thickened beyond pumpable consistency, the excavator removed material manually and stockpiled it for transfer to the settlement area. Excavation continued until the full extent of the intake structure was exposed and rockhead was reached. Loose material was scraped from the intake channel and relocated to the holding area.

Pumps and pipework were dismantled and removed once works were complete. The access route was deconstructed, with rock and 6F2 repurposed to form a larger parking and turning area at the dam crest. Stored peat and heather were reinstated to restore the natural landscape. Settlement pool liners were removed, bunds regraded, and silt spread evenly across the area. All silt fencing and hay bales were removed, and waste materials cleared from site.

The stilling basin was pressure-washed and cleared of silt bungs. A final site walkover was conducted with SSER and Trees for Life to assess the future route for deer fencing.