SWMU 23, Heart Lake Drum Disposal Area
Background
This site is located in an undeveloped field about 2 miles southwest of downtown Adak. It occupies a hillside between two small-unnamed lakes less than ½ mile from Heart Lake. The site, 7 acres of a grassy open field, was apparently used to dispose of about 20 drums and one storage tank in the 1940s. The original contents of the drums are unknown. When they were removed in 1994, all the drums and the storage tank were empty, and no evidence of releases was observed (US Navy 1995c).
The remedial action objective for SWMU 23 is maintain this area as an outdoor recreational area land use due to the presence of arsenic at levels that pose an elevated residential ICR.
Identified Contaminants
Arsenic was identified in the OU-A ROD as the Chemicals of Concernt (COC) for this site. It was identified at a maximum concentration of 10 mg/kg which exceeds the ADEC residential soil cleanup level of 4.5 mg/kg. The presence of arsenic at this site was estimated to have a residential ICR of 1x10E-5. The current use recreational ICR was estimated at 3x10E-7 and the industrial ICR at 6x10E-7.
CERCLA Institutional Controls
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CERCLA Engineering Controls
Engineering controls encompass a variety of engineered remedies to contain or reduce contamination, or physical barriers intended to limit access to property. Engineering controls, as they relate to Adak Island, include fences, signs, caps or barriers, and treatment systems including monitoring wells. The engineering controls identified in the OU A ROD, petroleum cleanup sites, and those that will apply as interim measures to OU B are described below.
Under the OU A ROD signed in 2000, fishing advisory signs were posted for subsistence fishers because of low levels of PCBs detected in bottom fish (rock sole) and shellfish (blue mussels) of Sweeper Cove and Kuluk Bay. The OU A ROD Amendment removes the requirement for fish advisory signs. Instead, the Navy will provide an information pamphlet to the residents of the City of Adak, because they are the most likely people to eat locally caught fish and shellfish as part of a subsistence diet. Fish information pamphlets will be updated as new information is collected and trends are analyzed. Copies of the updated pamphlets will be put in residence mail boxes, and copies will be placed at the City of Adak and U.S. Fish and Wildlife offices. The consumption of rock sole or blue mussels by recreational fishers poses no unacceptable health risks.
Ordnance hazard signs are in place on fencing around the part of the perimeter of the access restricted area adjacent to Lake Andrew. As of the end of the 2002 field season, remediation has been completed on all areas outside the access-restricted area adjacent to Lake Andrew. For this reason, with the exception of the signs at the perimeter of the Lake Andrew area, these signs are no longer required and were removed in 2003. Fences and gates at the access-restricted areas adjacent to Lake Andrew will be retained and maintained until the OU B-2 ROD is executed. Thereafter, ICs and ECs will be subject to the terms of the OU B-2 ROD.
| Other Engineering Controls Other engineering controls/remedies listed in the Comprehensive Monitoring Plan, Revision 1 are listed below.
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