Field-Scale Application of in situ Reductive Dechlorination for High Concentrations of Mixed Solvents in Complicated Conditions – Northern France Dr Richard Sumner – URS Corporation (Paris) Dr Jeremy Birnstingl – Regenesis Ltd. (UK)

Background Former Dry Cleaner Site Contaminated area: m 2 Representative concentrations Chlorinated ethenes (TCE etc) – µg/L Chlorinated ethanes (TCA etc) – µg/L Chlorinated methanes (DCM) – µg/L Buildings covering ~50% of plume

Complications Practical – access and disturbance Geotechnical – risk of subsidence Geological – risk of pathway exacerbation Public health – proximity of human receptors Requirement to ensure full dechlorination (no VC stall)

Practical Complications Built-up area – noise / nuisance concerns 50% of plume located beneath site buildings Source zone adjacent to residential properties

Geotechnical Complication Dual Phase Extraction initially considered Geotechnical assessments undertaken Risk of fines wash-out leading to subsidence Advection-based in situ remediation high risk Diffusive in situ remediation selected – HRC ®

Source Area

Source area adjacent to occupied residential properties Disturbance issues Risk / receptor issues Subsidence issues – overcome by selection of passive technology Measures adopted: Vadose vapour monitoring and venting installation Noise monitoring and management during injection TCE ≤ µg/L TCA ≤ µg/L DCM ≤ µg/L

Hydrogen Release Compound ®

Formation of an Ester Glycerol Polylactate Ester = HRC ®

Why? Accelerated Remedial Closure: Hydrogen creates anaerobic plume and accelerates biodegradation 10x – 100x Time Release of Hydrogen saves money: Reduced installation costs (simple to apply) NO remedial hardware: Design costs Equipment capital costs Equipment O&M costs Ongoing site disturbance

Geological Complication Shallow gravelly silt 0.75 – 3.0 mbgl Medium permeability Heavy contamination Silty sand layer 3.0 – 5.5 mbgl Low permeability Medium contamination Coarse gravels 5.5 – 10 mbgl High permeability Low – medium contamination (still requires treatment) Risk of Pathway Creation – 92 HRC ® injection points

Solution: ‘Top down’ and ‘bottom up’ injection

(block figure of geology?)

Application by GeoProbe ®

HRC ® directly injected using grout pump 41 kg HRC per point 92 injection points 6 vertical metres ~ 0.15% of pore volume Easy injection, minimal hydrogeological disruption

Noise Monitoring

Treatment Results Predicted results (theory based on other sites) Actual results (field performance of this site)

Results – predicted

Results – actual (Cl-ethenes)

Results – actual (Cl-ethenes)

Results – actual (Cl-ethenes)

Results – actual (Cl-ethanes)

Results – actual (Cl-ethanes)

Results Summary TCE Concentrations (µg/L)TCA Concentrations (µg/L) WellDay 0Day 430% Red.WellDay 0Day 430% Red. PP >99%PP % PW %PW % PW %PW >99% PW341198%PW % PW %PW (increase)

Results – actual (Cl-methanes) Chloromethane non-detect throughout study (both wells)

Dichloromethane (DCM) Results Well PZ3 /PZ3bisWell PW2 Dateµg/LDateµg/L Oct Oct Dec Dec Jan-040.1Jan Feb Feb Mar Mar Apr Apr May May-0492 Jun Jun-0415 Aug-04(no data)Aug-0426 Oct-04550Oct-0428 % Reduction91% Reduction99%

Cost Comparisons Total HRC project cost approx. € (Fieldwork, 2 years monitoring and reporting, HRC material) Comparative dual-phase extraction cost approx. € € € system installation € per year O&M for 3-4 years HRC project presented 25% - 40% cost saving (Faster too?)

Project Status Currently frozen Client went into liquidation All activities on hold But discussions now restarting

Currently frozen Client went into liquidation All activities on hold But discussions now restarting Project Status

Technology Applicability in France Closing Comments (URS) 1.A great, “text book” reductive dechlorination case study 2.HRC worked very well – it has a place in the remedial tool kit 3.Would reach for this technology where machinery is impractical for reasons of noise and space, fouling (e.g. sparging, drip-feed donors) or wash-out / subsidence concerns, (and in low-permeability formations - Regenesis). 4.Also valuable where on-going operation is not attractive – ‘one-off’ field installation provides maintenance-free remediation for several years

Closing Statistics This was the first HRC application in France Also the first full scale reductive dechlorination project in France? URS have completed approx. 30 HRC projects worldwide out of more than 100 projects using Regenesis products Total worldwide HRC projects is > – HRC is the most widely used electron donor in the world Largest URS HRC project (currently underway) is kg in US – >ten times larger (presented project is ca kg) URS therefore offer significant corporate experience with this technology in France, Europe, and internationally Regenesis provide free technical support and project assistance

For More Information: URS Corporation (Paris) Dr. Richard Sumner +33 (0) Regenesis Ltd. (UK) Dr. Jeremy Birnstingl +44 (0)