Ground Investigations

Scottish & Southern Electricity Networks (SSEN) commissioned CGL to undertake intrusive ground investigation works at a proposed new 275/132kV substation with overhead line connections to Dalmally, Inveraray, and Taynuilt substations in Scotland.

The purpose of the ground investigation was to provide factual information to assess the prevailing ground conditions, including in-situ and laboratory geotechnical testing and geoenvironmental testing. This information is required to aid the design and construction of a substation with associated access routes and earthworks for which CGL acted as Principal Contractor.

These works were undertaken within an environmentally sensitive area, with particular concern surrounding the River Array, which flows through the site. As part of the Risk Assessment, CGL liaised with the Scottish Environment Protection Agency (SEPA), determining whether CAR licencing (to control surface water discharges), was required given the site area was greater than four hectares.

Due to the limited water discharge amounts anticipated SEPA agreed that CAR licencing was not required. However, a stringent Pollution Prevention Plan was incorporated into the Construction Phase Plan and RAMS, to minimise, control and treat site run-off and general site pollution management using General Binding Rules.

Mitigation measures included using biodegradable lubricants, minimising water run-off by creating small sumps immediately downslope of each borehole and enforcing a 30m no-go area surrounding the River Array, within which no works were allowed and no persons or plant were permitted to enter for the duration of the works.

SEPA confirmed acceptance of this approach to working within an environmentally sensitive area, allowing the works to progress and the programme schedule to be maintained.