The Gilson Road hazardous waste dump site is located in the City of Nashua, New Hampshire. The 6-acre site has been used as a sand borrow pit for an undetermined number of years. Some time during the late 1960's the operator of the pit began an unapproved and illegal waste disposal operation. Household refuse, demolition materials, chemical sludges, and approximately 800,000 gallons of hazardous liquid chemicals were dumped at the site. The ground water, air and to a lesser extent surface water have been contaminated. The original ROD was signed in July 1982 approving the installation of a slurry wall and surface cap as the first operable unit. The ROD also approved ground water treatment as the second operable unit but deferred selection of the specific treatment process until the technical analysis and evaluation of the pilot plant studies were complete. The cost-effective ground water treatment system selected for this site includes: inorganic chemicals removal; volatile organic chemicals removal; concentrated organic chemicals removal; and biological treatment of the sidestream. Also a treatment rate of 300 gpm has been selected to reduce the operating time to approximately 2 years.

"Sept. 1983." "PB85-225514." "Office of Emergency and Remedial Response." "EPA/ROD/R01-83/007."