LAND & PROPERTY Groundwater and Ground Gas Assessment Storage and Distribution Unit Development, UK
Project Summary
Groundwater and Ground Gas Assessment Storage and Distribution Unit Development, UK
Project Value: £40,000 Key Project Elements Groundwater monitoring Ground gas assessment Liaison with relevant regulators Demonstrating protection of a sensitive receptor Safeguarding human health and property Discharge of a Planning Condition
CRA was commissioned by a ground works and construction contractor to conduct groundwater and ground gas assessments for the planning conditions relating to the development of a storage and distribution unit. The site was originally a biosolids drying lagoon that had previously undergone remediation, the method for which CRA had designed. Due to the site being located up-gradient of a river, the Environment Agency (EA) requested that groundwater sampling be undertaken at wells situated at appropriate locations along the river bank during the ground works. CRA undertook monthly monitoring of the groundwater quality for ammonia concentrations, which were compared to remedial targets agreed with the EA. CRA liaised with the EA throughout and reached an agreement to cease the monitoring as no detrimental impact was shown to the quality of the groundwater. As a result of the historical land use, a ground gas assessment was required to ensure appropriate levels of mitigation were employed to protect against ingress of gases into the site buildings. Once the ground works had been completed, a ground gas assessment was undertaken in accordance with UK guidance and comprised installation of 12 gas monitoring wells within the proposed buildings footprints. Six rounds of monitoring were carried out over an eight week period. Ground gas concentrations, flow rates, and pressures were measured in-situ at each well. The monitoring rounds were scheduled to enable data collection during various atmospheric pressure conditions. The ground gas data was used to calculate gas screening values (GSV) for the separate warehouse and office spaces to be built at the site. The GSVs allowed the level of required mitigation to be determined and recommended to the client. CRA presented the assessment results and proposed gas mitigation system to the Local Authority to gain approval and discharge of the planning condition. Ref: PS0100