Geo-Environmental Ground Investigation, Public Sector, Surrey

Purpose

Delta-Simons was appointed to undertake a £375,000 geo-environmental ground investigation, to inform future remediation requirements and geotechnical design for a proposed redevelopment of the site. At the time of investigation, the 41-hectare site comprised a sewage treatment works, allotments, waste transfer station public services, a former landfill, former sludge lagoons and public open space.

The proposed redevelopment of the site comprises low to medium rise residential properties, commercial properties, public services and a new sewage treatment works.

Sensitive ecology including Japanese Knotweed, Giant Hogweed, reptiles, badgers and ground nesting birds required management by a Delta-Simons Ecologist.

Scope of Works

The Delta-Simons team comprised 35 employees and contractors, completing the ground investigation over a 20-week period. The investigation scope  comprised:

• Full time supervision by Delta-Simons engineers and ecologists to coordinate the drilling works, vegetation clearance and archaeological supervision.
• Cable Percussive, Rotary Cored Wireline and Dynamic Sampler boreholes and mechanically excavated trial pits.
• 120 intrusive locations advanced to a max. depth of 30m bgl.
• 1700 geotechnical and 500 environmental laboratory tests.
• 6 rounds of return ground gas and groundwater monitoring and continuous ground gas monitoring of the former landfill.
• Provision of daily progress reports, sample schedules, logs and laboratory results to the client.

Outcomes / Client Benefit

Delta-Simons successfully delivered this large specification over a large and active site in a COVID Secure manner, adapting to all relevant government guidance to ensure the client’s requirements and timescales were met.

Effective on-site coordination between the site team and the multiple site tenants and landowners ensured that a seamless programme was fulfilled with no delays due to logistical challenges whilst reducing impact to the site stakeholders.

Dense vegetation clearance, poor weather and soft surface conditions at the site presented difficult challenges to safely overcome. The site team was able to adapt the investigation methods to avoid unnecessary costs and delays.