Weesp In Situ Chemical Reduction Volatile Chlorinated Hydrocarbons ***

In-situ remediation technique: (Enhanced) natural attenuation, anaerobic, In situ chemical Reduction (ISCR)

Project name: Weesp In Situ Chemical Reduction Volatile Chlorinated Hydrocarbons *** Case submitted by: Groundwater Technology BV Contact: Eric de Zeeuw Address: PO Box 12115 3004 GC ROTTERDAM The Netherlands Telephone number: +31 65 319 9211 Email-address: eze@gtbv.nl

Country: The Netherlands City/region/county: City of Weesp, Province of Noord Holland (future) use of location: Urban area Built-up location during the active remediation phase?: Yes

In situ saneringstechniek: (Enhanced) natural attenuation, anaerobic, In situ chemical Reduction (ISCR)

Explanation technique: A mix of microscopic zero-valent iron, organic substrate and water was injected in 35 injection points. Injection depth was 2.5 – 7 m below grade. The substrate is a carbon source to the indigenous bacteria. Consuming all available oxygen, deep anaerobic conditions result, leading to full sequential dechloration of the chlorinated hydrocarbons. The zero-valent ron leads to chemical dechloration, which degrades all chlorinated hydrocarbons at the same rate. Both processes actinf together lead to a quick and complete dechloration of the contaminants of concern. Residual products are harmless, such as ethane, ethane, chloride (ion) and (dissolved) iron. Also other remediation techniques applied?: No After care needed?: No Rationale for the chosen technique: A 16th century historic women’s fashion boutique on the water front in an medieval town centre in The Netherlands sits on contaminated land. The contamination originates from a dry-cleaner at the premises. The contaminants (Perc and Tri) slowly degrade to CIS, VC and ethene. However, the premises are sold and the new investor wants to terminate ‘perpetual’ monitoring. A thorough assessment leads the consultant to conclude that there is no cost-effective solution for this issue. The soil consists mainly of silt, clay and some peat, retarding migration to a trickle. Just monitored natural attenuation should suffice for this case. A back-up scenario is available in case of unexpected migration. Our client, a real estate investor, prefers to terminate the need for perpetual monitoring and is willing to invest a premium in a final solution, avoiding perpetual monitoring. However, active measures are required to achieve this goal. Active remediation is not a simple task: 1. The subsoil is very sensitive to subsidence (wet clay & peat). The premises (like all other buildings in the area) are not based on firm foundations such as pilings: subsidence is likely to damage the property. 2. Pump & treat is virtually impossible, and in view of the low permeability, probably will not affect contaminant migration. 3. The area is densely built-up, and many cables, lines, pipes, ducts and sewers are present in the subsoil. Shopping customers must not be hindered by remediation activities. 4. The area is a popular recreational-shopping area with fashionable boutiques, café’s, bars, restaurants and (in summer) boating

Treated contaminant(s): Chlorinated volatile organic compounds (CVOC) Contaminant phase: Soil/ pure product Groundwater Size contamination: 500 m3 Depth contamination: 7 meters below ground level

Soil type: Layered soil; clay/peat/sand Saturated/unsaturated zone?: Saturated zone Permeability: <0,01 m/day, estimated from bore logs Flow velocity or gradient groundwater: Not existent

Remediation goal: Stable and a situation without any requirement for monitoring Remediation goal achieved?: Yes Initial and final concentration and load removal: Perchloroethene Initial concentration 7800 ug/l final concentration: <0.1 µg/l total amount initial: 22.5 kg total amount final: 0 kg Trichloroethene Initial concentration: 13.000 ug/l final concentration: <0.2 µg/l total amount inital: 16 kg total amount final: 0 kg Dichloroethenes Initial concentration: 16000 ug/l final concentration: 0.37 µg/l total amount inital: 11 kg total amount final: 0 kg Vinyl Chloride Initial concentration: 5600 ug/l final concentration: <0.2 µg/l total amount initial: 2.2 kg total amount final: 0 kg Active remediation phase: 13/09/10 till 21/09/10 Passive remediation phase: The passive phase is finished. Execution period:13/09/2010 till 21/08/13 Total costs passive/after care phase: € 11.000 Total costs active phase: € 35.000

Problem owner: Dubbel R Projectontwikkeling BV Contractor: Groundwater Technology BV Remediation plan: Groundwater Technology BV Remediation research: Groundwater Technology BV Competent authority: Province of Noord Holland Contact information stake holders: Groundwater Technology BV

Lessons learned: 'Negative' CO2 footprint: that is, more CO2 is minaralized in the soil than emitted into the atmosphere Remarks: This remediation was implemented in a densely built area, without any nuicance to the general public or local residents

Related techniques: (Enhanced) natural attenuation, anaerobic, In situ chemical Reduction (ISCR)

Related HIP-pilots: HIP-pilot Assessing stable end situation CVOC 1, HIP-pilot Assessing stable end situation CVOC 2, HIP-pilot Direct push shock load protamylasse – radius of influence and effect substrate, HIP-pilot Field comparison 2 substrates for anaerobic degradation CVOC, HIP-pilot Specific monitoring biological degradation