Record of Decision System (RODS)
AMOCO CHEMICALS (JOLIET LANDFILL)
|Site Name:||AMOCO CHEMICALS (JOLIET LANDFILL)|
|Address:||ROUTE 6 NEAR ROUTE 66|
|City & State:||JOLIET IL 60434|
|NPL Status:||Currently on the Final NPL|
|ROD Type:||Record of Decision|
|Media:||Groundwater, Leachate, Sediment, Soil, Surface Water|
|Contaminant:||Base Neutral Acids, Inorganics, Metals, PAH, PCBs, Pesticides, VOC|
The Amoco Chemical Company (BP Amoco) is located approximately one mile southeast of the intersection of Illinois Route 6 and Interstate Highway 55. It is an active chemical manufacturing facility located on approximately 750 acres of land in a semi-rural industrial/agricultural area. The facility is near Joliet, Illinois in Will County on the west bank of the Des Plaines River.
The BP Amoco manufacturing facility has been in continuous operation since approximately 1958, manufacturing purified isophthalic acid, trimellitic anhydride, maleic anhydride, and polystyrene. The manufacturing wastes generated by the facility were contained in thin wall, rust away drums and disposed into two landfills (north and south landfills) on the site which were closed in the mid-1970s. The closed landfill areas cover approximately 26 acres. The former landfill areas are located in the southern portion of the property. A gravel road along the bluff above the Des Plaines River forms the eastern and southern boundaries of the landfills. The landfills are located within 600 feet of the western bank of the Des Plaines River. The landfills are sited on a bluff approximately 54 feet above the 100-year flood plain. Land to the east of the northern part of the site drops off sharply to a level bench which extends east for about 150 feet. This bench then drops again to the river flood plain. The first bench below the landfills is about 24 to 36 feet above the 100-year flood plain. Farther south, land drops rapidly to a lower bench, 12 to 18 feet above the 100-year flood plain. The bench area is greater than 300 feet wide in places. The banks then drop steeply to the river. Wetland areas, as defined by growth of cattails (Typha augustifolia), occur in red-orange stained soils located just upgradient of the present leachate collection system.
The contents of the landfill include approximately 5,900,000 cubic feet or 218,518 cubic yards of wastes, some in 55-gallon drums, including organics, inorganics, heavy metals, acids, and general plant refuse. Specifically, BP Amoco records indicate disposal of solid wastes, liquid slurries and "semi-solid" wastes in the landfill. Waste materials, including drums, solids and some liquids, were placed on the ground surface or in excavations and then covered with stockpiled dirt.
In 1972, a large portion of the landfill area was closed. In 1973, the smaller southern landfill area began receiving process waste. Disposal into the south landfill continued until 1975. No monitoring of landfill containment was performed subsequent to closure.
There have been several historical documented releases associated with the site. In July 1974, the State observed a reddish leachate discharging into the Des Plaines River and traced its origin to the landfill area. The plume extended 15 to 20 feet into a quiet backwater area of the river before the red staining was no longer observed. A leachate recovery system was installed by BP Amoco in March 1975. The system was upgraded in 1988. More recent visits (mid-1990s), however, suggest that groundwater and leachate may be escaping containment. This is evidenced by iron staining on the ground surface emanating from the south end of the collection system to 150 plus feet down gradient as well as iron staining on a small stream outcrop down gradient of the collection system near the backwater area east of the landfill.
The site was added to the National Priorities List (NPL) in February 1990.
On April 7, 1994, a Consent Decree requiring a Remedial Investigation/Feasibility Study, was entered. In early 1998, an agreement between the State and BP Amoco split the site into two operable units: one for the landfills and the other for the contaminated groundwater. A Record of Decision (ROD) for the Landfill Operable Unit was completed in July 1999.
Based on consideration of the requirements of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), the detailed analysis of the alternatives, and the public comments, both the State and the United States Environmental Protection Agency (U.S. EPA) have determined that Alternative SC-4, a double barrier (Resource Conservation and Recovery Act (RCRA)) cap, is the most appropriate remedy for the landfill cap operable unit at the Amoco Chemicals (Joliet Landfill) Superfund Site (the site). The selected remedy is a RCRA type double barrier cap. A new leachate collection system will be installed at the southern landfill and along the southern portion of the north landfill. Leachate will be collected and treated prior to surface discharge unless contaminant concentrations are below standards. The costs associated with the construction and operation of the new leachate collection system were not included in the estimated costs. New groundwater monitoring wells will be installed around the perimeter of the landfills to complement the existing monitoring wells and replace the wells that are abandoned during cap placement. Plus, restrictions regarding the usage of the capped area will be placed on the property deed. The waste will not be excavated to allow for treatment, but instead capped in place.
The chosen alternative includes the construction of an improved and more stringent cap over the existing landfill area. Specifically, the cap will conform to the RCRA landfill requirements. The cap profile will include a composite barrier consisting of two layers: a flexible membrane liner at least 40 millimeters in thickness over a 24-inch layer of clay compacted to 1E-7 centimeters per second permeability. The low permeability clay layer may be replaced with a geocomposite clay liner (GCL) that exhibits performance characteristics equal to or greater than the compacted clay layer (Alternative SC-4B). The layers above the barrier layers (topsoil, rooting layer, drainage layer) and below (subgrade layer) may consist of common landfill cap components and may vary based on cost, workability, and availability. At a minimum, these materials must be equivalent to the capping components as defined by the most stringent Applicable or Relevant and Appropriate Requirements (ARARs).
A system of passive vents to allow the release of vapors from the landfill waste will be installed. These vapors, produced by volatilization and/or decomposition of materials in the waste, may tend to migrate laterally after a low permeability cap is constructed. The quality of the gas emitted from the vents will be monitored semi-annually for a period of two years. If deemed necessary to protect human health and the environment, an active gas collection and treatment system will be designed and implemented.
A new leachate collection system will be designed and installed down gradient of the southern landfill at a sufficient lateral extent and depth to ensure the capture of the majority of the leachate escaping the landfill and a new leachate collection system will be installed down gradient of the southern portion of the north landfill near the existing culvert extending under the road to capture the historical leachate seeps in that area. Both collection systems will be designed to allow the monitoring of the quality and quantity of the leachate being collected. The collection systems will discharge to the BP Amoco wastewater facility for treatment prior to discharge provided the facility is in compliance.
The cap design will include surface water management features (e.g. berms, ditches, catch basins, etc.) to direct runoff away from the landfill while minimizing erosion and infiltration. A program for long-term maintenance and monitoring will be implemented as part of this alternative. Maintenance will include regular inspections of the landfill area, repair of any damage to structures or the soil cover, removal of excessive sediment from ditches and other areas, and mowing. Following the completion of the landfill cap operable unit remedial action, groundwater will be monitored quarterly for a minimum of one year to determine the effectiveness of the cap. Prior to the completion of the remedial action, groundwater monitoring wells will be installed around the perimeter of the landfills in sufficient numbers and location to complement the existing monitoring wells and replace the wells that are abandoned during cap placement. Several of these monitoring wells will be installed in a nested configuration to monitor all three water-bearing zones (shallow, intermediate, and deep).
Groundwater monitoring as part of RCRA post-closure groundwater monitoring requirements will be conducted following closure of the landfills. At a minimum, the Operation and Maintenance (O&M) Plan will include the monitoring of the groundwater wells as part of the post-closure care, the analytical parameters for testing, the monitoring frequency, the contaminant trigger levels, and the contingencies to be implemented if trigger levels are exceeded or any other problem arises.
Physical access restriction must be maintained so that trespassing will be minimized. Signs will be placed in strategic locations to warn anyone nearing the landfilled area about potential site hazards. The real estate deed will be amended to include prohibition of on-site groundwater use, on-site building construction, and on-site drilling except for the purpose of remedial design, sampling, monitoring, and remedial action. In addition, a program for monitoring the leachate seeps in the slope down gradient of the landfill will be included in the O&M plan.
Estimated Total Capital Costs: $5,349,000
Estimated Annual O&M: $96,000
Estimated Net Present Worth: $6,705,000
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