Record of Decision System (RODS)
NINTH AVENUE DUMP
|Site Name:||NINTH AVENUE DUMP|
|Address:||7357 W NINTH AVE|
|City & State:||GARY IN 46402|
|NPL Status:||Currently on the Final NPL|
|Media:||groundwater, sediments, soil|
|Contaminant:||Ketones, chlorinated ethanes, BETX, PAHs, phenols, pesticides, PCBs, plasticizers, dioxins, furans, VOCs, pesticides, metals|
Please note that the text in this document summarizes the Record of Decision for the purposes of facilitating searching and retrieving key text on the ROD. It is not the officially approved abstract drafted by the EPA Regional offices. Once EPA Headquarters receives the official abstract, this text will be replaced.
The purpose of this Record of Decision Amendment is to present a change for the final site remedy for the Ninth Avenue Dump site.
The Ninth Avenue Dump site is an inactive chemical and industrial waste disposal site and is located in Gary, Indiana. It occupies approximately seventeen acres and is situated in an area of mixed industrial, commercial, and residential property use.
The site is located in a low-lying area with poor drainage. Prior to filling, the site consisted of parallel ridges separated by wetland areas. The site is relatively flat with small depressions and mounds remaining from waste disposal or cleanup activities. A slurry wall surrounds the area of the site that contained groundwater contamination which was known or suspected, at the time of the construction of the wall, to exceed acceptable concentrations. The wall is keyed about three feet into a clay formation that is approximately 30 feet below the ground surface. Situated within the slurry wall is a pond and wetland area. A fence had been installed around the site, which now includes portions of adjacent properties.
The site had been used for the disposal of hazardous wastes from the early to mid 1970s. Buried wastes at the site include foundry sand, wood, concrete, bricks, metals, slag, non-containerized liquids and sludges, and drummed liquid and solid materials. Depth of fill ranges from zero to ten feet. The water table is about three feet below the surface. Most of the filling appeared to have been in the central and southern portions of the site, with filling apparently having stopped at the ponded area in the southern portion. During the remedial investigation (RI), it was found that some of the soils were contaminated with a variety of ketones, chlorinated ethanes, BETX (benzene, ethylbenzene, toluene, and xylene), polycyclic aromatic hydrocarbons (PAHs), phenols, pesticides, polychlorinated biphenyls (PCBs), plasticizers, and dioxins and furans. On- and off-site surface water bodies and sediments contained only low levels of volatile organic compounds (VOCs), PAHs, pesticides, and metals at low frequencies of detection. An oil layer was found floating on the groundwater in the central and south central portions of the site. The groundwater under the site was found to be contaminated with approximately 100 organic and inorganic substances, including many of the compounds found in the oil layer. However, groundwater contamination was found, for the most part, to have not migrated beyond the site boundaries, except on the eastern and northern sides of the site. The groundwater on the site is also contaminated by high concentrations of dissolved solids, including chlorides, that have migrated from an off-site source south of the site.
The remedial action for the site consists of two operable units. The first operable unit addressed an oil layer floating on the groundwater by means of oil and groundwater extraction, oil storage, reintroduction of the groundwater, containment with a slurry wall, and management of excess surface water. The extracted groundwater was treated prior to reintroduction. The second operable unit, which is being amended by this decision document, addresses the remaining threats at the site.
The major components of the selected remedy for the second operable unit include: installation of an intermediate slurry wall that will separate the surface water area from the contaminated area (primary containment area); removal of debris and contaminated sediments from surface water bodies on the site that are to remain, and placement of this material under the cap; installation of a soil vapor extraction system covering the portions of the primary containment area known to be contaminated (after necessary dewatering) and subsequent operation of the system to provide a performance that is appropriate and acceptable while maintaining the water level about 10 feet below the present surface; disposal of the oil extracted during implementation of the first operable unit in a manner which is appropriate and acceptable, most likely in an off-site incinerator; installation of a cap over the primary containment area, landscaping of the site, and establishment of a storm water management system which includes discharge of excess water; containment or extraction and disposal of contaminated groundwater or sources of groundwater contamination found outside the primary containment area; removing or securing any equipment which was used during implementation of the first operable unit that will not be used as part of this remedy; maintenance of an acceptable water level within the primary containment area and disposal of the excess water; deed and access restrictions that prohibit use of groundwater at the site and protect the remedy; and operation and maintenance of the remedy, including the fence and slurry wall installed in the first operable unit, and monitoring of the site to ensure protectiveness.
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