Project: Former Distribution and HGV Maintenance Depot, Harthill
Timescale: 18 months
This former goods distribution and HGV maintenance depot had discrete areas of hydrocarbon impact associated with fuelling and maintenance activities. The client required a turn-key service to design and deliver a voluntary remediation scheme to protect a nearby watercourse and manage liability.
The outline proposals were for bioremediation of the main areas and in-situ soil flushing beneath a maintenance building. ERS prepared a detailed Remediation Method Statement and agreed this with all stakeholders. However, shortly after contract award the performance specification was amended and ERS were instructed to undertake further ground investigations. These was done by our in-house drilling team, allowing rapid results so the project schedule was not affected.
1500m² of concrete hardstanding was broken out and crushed for reuse as backfill. 1300m³ of impacted soils were excavated, screened and subjected to bioremediation in covered windrows. The windrows were monitored for bio-remediation parameters, supplemented with organic and inorganic nutrients and turned to aerate the soils and optimise biodegradation.
Early in the soil flushing phase it was discovered that contamination levels were not in line with with the data from previous site investigations (not done by ERS), meaning soil flushing alone could not be expected to meet the stringent remedial criteria required to protect a watercourse just beyond the site boundary. We quickly identified a feasible alternative that could meet remedial targets without requiring demolition of the building, and keep within the agreed value of the contract. This variation was accepted by all stakeholders.
During the bioremediation phase, the site owner identified a sale opportunity for the site which was conditional on remedial works being complete. ERS quickly responded to an instruction to remove the contaminated material from site and backfill with imported material. This was re-negotiated with all stakeholders and works were completed in a matter of weeks, allowing the sale of the site to proceed.