--- Surfactant Enhanced Aquifer Restoration at a Former Chemical Weapons Manufacturing Site

Transcription

1 25/03/2015 Amélioration de la réhabilitation d un aquifère pollué par du chloroforme et du triclorofluorométhane (Freon-11) par usage de surfactant sur un ancien site de fabrication d armes chimiques --- Surfactant Enhanced Aquifer Restoration at a Former Chemical Weapons Manufacturing Site Présenté par : Jérémie LEPLAT Responsable Technique BIOGENIE Europe Chris KING Directeur Technique BIOGENIE CELTIC (UK)

2 Avonmouth Site Details One of the most contaminated in the SW of England (near Bristol). Extensive Industrial past dating back to the First World War. Used for: Production of Chemical Warfare Agents Lead and Zinc smelting Sulphuric Acid production Pharmaceuticals, agrochemicals and refrigerants Closed in

3 Characterisation A large number of investigations (final one by ERM) had been completed at the site including: High Resolution Site Characterisation using combined CPT and Membrane Interface Probe (MIP) BAT sampler to collect discrete groundwater samples Detailed sequence stratigraphy Perched water ( 2mbgl) / GW ( 6mbgl) 0 2 Made ground Clay 6 Alluvium : soft to stiff sandy silts 12 Mercia Mudstone Sandy clay 3

4 Site Characterisation The key contaminants of concern were VOCs, including : carbon tetrachloride, chloroform, trichlorofluoromethane (CFC 11), hexachlorobutadiene, vinyl chloride and trichloroethene. Impacted zone : soils, perched water and deep ground water. Dissolved phase concentrations of chloroform (559mg/l) and CFC 11 (783mg/l) which were indicative of the presence of residual CFC DNAPL. 4

5 Remediation Objectives & Strategy Objectives: Achieve validation criteria for soils On site treatment preferred and minimise Off site disposal Groundwater Betterment Extraction and treatment of contaminated water contained within the deep aquifer Maximum mass recovery Must be completed within project timescale (6 months) No off site discharge Strategy: Shallow Soils ( m 3 ) : Excavation and ex situ Soil Vapour Extraction (SVE) Perched Water : Collection, on site treatment and re injection Deep Groundwater : Surfactant Enhanced Aquifer Restoration (SEAR) 5

6 Remediation Of Shallow Soils and Water Selected Remediation Technique Onsite Treatment using a bespoke ex situ SVE System Shallow water extraction and on site treatment On Completion 22,000 tonnes of material excavated, segregated and treated (about 6 months) No offsite Disposal Completed on programme 6

7 Remediation Of Deep Groundwater PHASE 1 Delineation Installation of 59 wells (using Sonic and Cable Percussive Techniques) Detailed Delineation Initial Plume Delineation (ERM) Refined Plume Delineation (CFC 11) 7

8 Remediation Of Deep Groundwater PHASE 2 Hydraulic Recovery 16 Active Extraction wells Submersible pumps (pneumatic) Dissolved air flotation (for sediment and product recovery) Air stripping (for dissolve VOC s treatment) GAC (for gas and water final treatment) Treated water re injection (flushing, hydraulic loop) 8

9 Remediation Of Deep Groundwater On going Assessment and Delineation Allowed continual assessment of how the plume was responding Important for the detailed design of the SEAR. Enabled Surfactant Enhanced Recovery to cost effectively target residual mass. SEAR injection based pilot trial (labs and site) 9

10 Enhanced Mass Recovery SEAR Hydraulic Recovery Enhancement This method is very site and contaminant specific. Detailed laboratory trials to determine type, amount and concentration Site pilot : injection pressure and Zone Of Influence Prelim Surfactant Selection Effluent Samples Column Tests 10

11 Application of SEAR Targeted localised residual mass. A Total of 8 surfactant injection wells were used. Extraction from 29 wells ensured capture of mobilised CoCs. 11

12 REMEDIAL ELEMENT D Deep GW Hydraulic Recovery Results Recovery post surfactant injection On Completion 13 millions litres of GW removed and treated ~2,500 kg of mass removed Target Criteria achieved on programme 12

13 Overview On completion of the remediation works: 22,000 tons of contaminated soils excavated segregated and treated 0 tonnes of soil disposed off site Successful use of Surfactant Enhanced Aquifer Remediation Removal and treatment of over 13,000,000 liters of groundwater Recovery of ~2,500 kg of VOCs Completion ahead of programme 13

14 Thank you for your attention Merci de votre attention!

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