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Guaranteed Fixed Price Remediation, Brooklyn, New York, USA

Project Summary:

The owner of a 5.5-acre industrial site requested WSP to design a remedy that would restore the site to state cleanup standards. Of particular concern was the site’s location adjacent to a canal in Brooklyn, New York.

The Client’s Challenge:

The site had been used since 1904 for industrial and commercial purposes—including manufacture of vinyl stabilizers and plastic adhesives. Both the soil and groundwater beneath the site were impacted with a wide range of compounds of concern (COCs), including benzene, toluene, xylenes, acetone, tetrachloroethene, trichloroethene, methylene chloride, phenol, and naphthalene. The site was underlain with up to 20 feet (6 meters [m]) of historic urban fill. Underlying the fill was relatively impermeable silty clay that was formerly the bottom of the canal. Groundwater was located within the fill layer between 2 and 9 feet (0.6 to 2.7m) below ground surface (bgs).

Our Work:

Based on the successful results of a pilot test, WSP Environment & Energy applied steam-enhanced dual-phase extraction (DPE) at the site. The test demonstrated potential for rapid remediation and recovery of the more recalcitrant compounds. While state-specific standards remained the site’s cleanup goals, the agreed-upon Consent Order allowed termination of the remedial system operation after concentrations of COCs have reached an asymptotic state (i.e., level off to nearly constant concentration).

The treatment area encompasses approximately 1.6 acres that were subdivided into four separate treatment zones based on the type of compounds being addressed in a particular area. WSP installed 47 injection wells and 43 extraction wells that are operated within all or any portion of each treatment zone as necessary.

The Outcome:

Within four years of system startup, approximately 14,509 pounds of VOCs were removed via vapor phase extraction. In addition, more than 1,650 gallons of separate phase hydrocarbons, more than 4,020,000 gallons of groundwater, and more than 743 pounds of VOCs and SVOCs were removed in the aqueous phase.

Steam-enhanced DPE has been very effective at removing significant COC mass from the subsurface within a relatively short time period. Results for groundwater samples collected before and after treatment have indicated a significant decrease in VOC concentrations, some to nondetectable values, and over 92% reduction in phenol concentrations, the primary SVOC COC.

Cumulative dissolved VOC concentrations decreased by approximately 31% between system startup and steam breakthrough. Vapor sampling has shown a decrease in total VOCs over the course of treatment activities within a particular treatment zone.