Innovative remediation strategy bringing redundant former industrial land into productive re-use
Remediation Site assessments
EPS was commissioned to perform further remediation works at a heavily contaminated site located in a sensitive setting on an island in the middle of a large river. Diesel was found floating on groundwater and also seeping into the river. EPS worked to a particularly tight schedule and with a minimal budget to specifically focus on groundwater remediation, define targets and ensure those were met to the satisfaction of the Environment Agency.
- EPS arrived on site following a previous contractor who had demolished the buildings of a former scrapyard and completed a remedial excavation of contaminated soils. The ground beneath the site had been contaminated by oils and diesel fuels as a result of the historic activities. The soil contamination was also affecting groundwater resting within the gravels beneath the island, which forms a part of the local river system with water moving around it and also slowly through it bringing oil and diesel contamination with it and at the same time polluting the river. The ground contamination had already been remedied but work was still required to address the contaminated groundwater and to select the most appropriate remediation system for the site.
- The island was planned to become a specifically designed commercial viewing garden open to the public, containing a number of flower beds with a large bricked path meandering through the centre. Restricted by only having single phase electricity available on site and with severe budgetary constraints, EPS was able to use many off-the-wall alternatives and resourceful features in this remediation system to reduce costs without compromising on achieving the desired clean-up results. We worked closely with the Client’s landscaping design team to ensure the remediation system requirements discretely fitted in with the redevelopment, adjusting the locations of some wells accordingly.
- Using a combination of qualitative and quantitative assessment, EPS was able to confirm a “clean edge” in a large part of the site whilst also identifying that groundwater in one area of the site was severely impacted by oils and diesel fuel. Boreholes installed within the river bank, beyond the extent of the remedial excavation, found oil and diesel fuel floating on the groundwater surface, which was causing a sheen to emanate onto the river surface at times of high water level. With the commencement of works on the public garden imminent, it was not possible to trial remediation technologies and instead apparatus was installed to allow for deployment of any of several different technologies, including Vacuum Enhance Extraction (VER), pump and treat, bio-slurping, chemical oxidation and skimming, which scored the highest in the remedial options appraisal. Some 8km of pipework was installed beneath the site allowing for a trial approach to remediation, whereby the most favourable technologies could be applied, assessed and, if effective, scaled up.
- The public gardens were built and opened on schedule and the remediation system was successfully commissioned - on time and on budget. Three years from installation, the system has managed to significantly reduce groundwater contamination detected within the monitoring points with minimal impact to the commercial activities on site, to the satisfaction of the regulator. Following the latest round of groundwater monitoring in early 2017, all samples returned results below laboratory detection limits.