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Project 2 - Groundwater Remediation

Emcus Ltd undertook the investigation and then the subsequent design and supervision of remediation works of hydrocarbon and solvent contaminated groundwater encountered during the redevelopment of a former glass manufacturing factory in Nottinghamshire.

Local Contamination of the groundwater was first suspected when hydrocarbon staining of concrete was observed adjacent to the construction joints in a retaining wall at the second basement floor level (circa 7m bgl) of a building at the site. Emcus Ltd were asked to undertake an investigation of the suspected contamination, which included the advancement of boreholes from the first floor basement level of the building using restricted access plant. The investigation identified elevated concentrations of Hydrocarbons, Volatile Organic Compounds and Semi Volatile Organic Compounds in the groundwater perched within the granular Made Ground behind the lower basement wall.

Emcus Ltd subsequently designed and supervised a programme of works to remediate the perched groundwater. These remediations works included the installation of two large diameter wells in the course granular backfill behind the basement retaining wall, using a demountable cable percussion drilling rig, lifted into position within the basement of the building. Due to the limited head room in the basement, the wells were advanced from a 'ledge' part way between the first and second floor basement levels, with the tops of the wells below the level of the perched water table. To prevent the contaminated perched water from discharging into the basement, temporary casing was anchored and sealed onto the concrete floor of the basement prior to the construction of the wells.

installation of groundwater remediation wells

Following the construction of wells, a submersible recovery pump was used to recover the LNAPL's from the surface of the perched water, with the product pumped to several 1,000 litre IBC's positioned in the basement of the building, for subsequent disposal off site.