Former Bus Depot, Redclyffe Road, London

Jo Strange

Jo Strange

Technical Director

Tel: 01483 310600

Email

Client

Telford Homes plc

Services

  • Remediation Strategy
  • Detailed Quantitative Risk Assessment
  • Additional Ground Gas Assessment
  • Quantitative Gas Risk Assessment
  • Verification Services

Geoenvironmental Services – Gas Monitoring, DQRA and Verification Reporting

The development of the former bus depot at Upton Park is located in east London, close to the former Boleyn Ground of West Ham FC. The site and surrounding area were part of a gravel pit before being infilled to form a series of ponds then further infilled when the site was developed into a garage and later a bus depot.

A previous ground investigation by another consultancy identified contamination in the soil and groundwater that posed a risk to human health and controlled waters, including asbestos, heavy metals, polycyclic aromatic hydrocarbons and total petroleum hydrocarbons. A remediation strategy had been proposed but CGL noted that ground gas monitoring wells had not been installed within the organic pond deposits of the former gravel pit.

Telford Homes instructed CGL to complete a review of the available information and undertake a Detailed Quantitative Risk Assessment (DQRA) to further assess the geoenvironmental risks.

CGL’s DQRA results concluded that additional remediation measures were required to address benzene within the groundwater. Furthermore, vapours from soils and groundwater posed a risk to future residents and further investigation of the potential gassing risk of the pond deposits was required due to the high Total Organic Carbon (TOC) present. Using the results of the DQRA and in discussions with the chosen remediation contractor, CGL revised the original remediation strategy and integrated it with the overall construction works, utilising treatment by soil stabilisation to provide a working platform for subsequent piling.

CGL recommended that installation of gas wells and gas monitoring were undertaken after ground stabilisation in the Pond Deposits area, to take account of the effects of the stabilisation on the gassing potential of the treated soils.

CGL worked around the construction schedule to install monitoring boreholes in the treated and untreated zones and took samples for chemical (organic matter) analysis. Based on the results of the ground gas monitoring, chemical analysis and pond deposits CGL recommended that gas protection measures within the development conform to CS2 conditions.

As the works have progressed CGL has provided technical support on remediation details, liaised closely with the local Environmental Health Officer, remediation and main works contractors, and monitored the remediation works to provide third-party verification.