The Celtic, Mclaren and ERM team has just won the Best Use of a Combination of Remediation Techniques Award at the 2013 Brownfield Briefing Awards for the ASDA distribution hub site in Avonmouth. The success of the Mersey Gateway project was also recognised, gaining a Highly Commended Award in the same category.
The Avonmouth site was one of the most contaminated in south-west England and has a long industrial history as a munitions and chemical warfare plant during World War One, followed by zinc and lead smelting with sulphuric acid production until 1972, and then production of pharmaceuticals, agrochemicals and refrigerants until 2008, when the site was closed. During preliminary investigations undertaken to support a planning application for redevelopment of the site multiple contaminants were identified.
There were significant logistical and technical challenges as the remediation had to be undertaken in parallel with the redevelopment programme and in addition there were unusual Health and Safety management challenges due to the potential risk of unexploded devices and mustard gas. Despite the complexity of the project, the works were completed in less time than originally programmed through novel investigation and interpretation techniques and innovative remedial technology design and application.
A key aim of the remedial strategy was to minimise off-site disposal and enable the contaminated materials to be treated and re-used on-site. Prior to commencing remediation activities, approximately 22,000 tonnes of contaminated material was excavated. Martin Holmes, Celtic’s Regional Operations Director comments, “We were able to re-use 52% of the material immediately and 48% of contaminated material was treated in an 11 week period using Celtic’s ex-situ Soil Vapour Extraction system”. The soils were then reused as part of the wider redevelopment scheme through a site-specific Materials Management Plan in accordance with the CL:AIRE Code of Practice. The project achieved 100% material recovery and re-use.
The Surfactant Enhanced Aquifer Restoration (SEAR) designed by Celtic using laboratory scale trials in their UK and Canadian facilities enabled a 3 to 4 fold increase in contaminant recovery compared to conventional hydraulic pumping. A total of 11,690m3 of groundwater was treated culminating in the recovery of approximately 2500kg of contaminants.
The ERM/Celtic/McLaren project team gathered a considerable amount of data during the shallow soil remediation and were able to refine the site hydro geological model and present it to the regulators which resulted in significant cost-saving and removal of a number of development constraints.
Paul Hesketh, Technical Director at ERM concluded, “The ERM/Celtic and McLaren project team formed an excellent working relationship which resulted in the site being successfully remediated with a strong focus on carbon footprint reduction. The agreed performance criteria were met safely, on schedule, on budget and in a sustainable manner and to the satisfaction of all stakeholders”.
The 62 acre site which has been developed by Bericote Properties and includes a 51,097 sq m frozen warehouse is due to open in late 2013.