Gasworks Remediation - Kings Cross, London
29 January 2013, News release from Ecologia Environmental Solutions Ltd
Ecologia was appointed to design, manufacture, commission and operate a bespoke system for the remediation of a former gas works site located at Kings Cross, London.
The remediation equipment was required in order to meet the following client brief:
•Drill a predefined number of extraction wells in three gasholders;
•Dewater gasholders prior to excavation, in accordance with the overall site programme;
•Reduce VOC emissions using a Soil Vapour Extraction (SVE) system in the unsaturated soils, following dewatering and prior to excavation;
•Provide additional odour mitigation measures for temporary excavation and stockpiling of heavily contaminated soils.
Ecologia was also commissioned to prepare and submit to the Environment Agency a site-specific Deployment Form covering the proposed remediation activities on site.
Within two weeks of instruction, a pilot trail was carried out in one of the largest gasholders, using a small portable multiphase extraction unit, to determine the radius of influence for the extraction wells. The full scale system was subsequently commissioned five weeks after instruction, following approval of the deployment form by the Environment Agency.
Ecologia supplied various remediation systems, all manufactured in-house. These comprised the following main components:
•Water treatment system for dewatering of gasholders and excavations: Flow balancing / buffering tanks, oil /water separator and multiple Granular Activated Carbon (GAC) filters.
•Soil Vapour Extraction (SVE) system connected to an array of 15 extraction wells in order to dry out soil prior to excavation and minimise release of Volatiles Organic Compounds, discharging through a GAC filter.
•Engineered odour control blanket combined with SVE system to ensure negative pressure. This was necessary to reduce risk of uncontrolled odour emissions during excavation of contaminated soils from the gasholder and from temporary stockpiles.
Ecologia's engineers undertook regular operational system checks and CoTC visits to ensure continued operation of remediation equipment, Regulatory Compliance and minimal environmental impact.
The SVE system effectively captured diffuse odour emissions from the unsaturated soils and the same system was also used to capture VOC emissions from the water treatment system which utilised the GAC filters of the SVE system, to prevent escape of odours to the nearby St Pancras International railway station.
The modular water treatment was easily relocated several times to meet changes in the client's excavation programme and help overcome significant space constraints at the site.
The water treatment was operated over a period of 4 months, treating significant volumes of water heavily contaminated with tar residues, thus enabling our client's critical excavation programme to be completed on time.
This project was the implementation of the remediation strategy designed by Arup for King's Cross Central which was Highly Commended at the 2012 Brownfield Briefing Award for 'Best Conceptual Design'.
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