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Record of Decision System (RODS)



City & State:  WARMINSTER TOWNSHIP  PA  18974
County:  BUCKS
EPA ID:  PA6170024545
EPA Region:  03
NPL Status:  Currently on the Final NPL
ROD Type:  Record of Decision
ROD ID:  EPA/541/R-00/014
ROD Date:  09/27/2000
Operable Unit(s):  12
Abstract:  The Pennsylvania Department of Environmental Resources (PADER) recommended excavation and disposal of fire residuals and contaminated soils at Site 8 in October 1986. The Site was proposed for inclusion on the National Priorities List (NPL) also in 1986, and placed on the final NPL on October 4,1989. By October 1988, the double soil berms on Site 8 had been removed. Naval Air Warfare Center (NAWC) personnel reported that these berms, fire residuals, trapped liquids, and soil from eroded areas had been analyzed and removed. The berm material was deposited in an area adjacent to Site 8 and the area was regraded.

The Phase I Remedial Investigation (RI) was initiated in late 1988. The RI was completed and the Phase I RI Report was released on September 11, 1990. Phase I initiated the investigation of sites 1 through 8 by screening these sites for volatile organic compounds via soil gas analysis, electromagnetic surveys, soil borings, and by installing and sampling shallow monitoring wells.

On September 20, 1990, the Navy and EPA signed an Interagency Agreement (IAG) which established a procedural framework for developing and implementing investigative and response actions at the Site in accordance with CERCLA and the National Contingency Plan.

The Phase II RI was initiated in late 1991. This work included installing additional monitoring wells, analyzing groundwater, and evaluating aquifer characteristics. Four off-site wells were sampled during the Phase II RI. Based on the results on the investigations of Phases I and II, the Navy completed RI and Feasibility Study (FS) Reports addressing contaminated groundwater in OU-1 in April 1993.

In October 1993, a focused RI was initiated to further investigate the nature and extent of contaminated groundwater attributable to Areas A, B, and C, as well as in the vicinity of the main building complex at the base (Area D).

On September 29, 1993, the Navy Jointly signed a Record of Decision with the EPA for OU-1. The ROD for OU-1 selected an interim remedy which included the pumping and treatment of groundwater to limit the migration of contaminated groundwater attributable to Areas A and B.

From April 28, 1993 through September 30, 1994, the Navy sampled more than 500 wells to assess the impact of contaminated groundwater attributable to NAWC on off-site groundwater users in Areas A and B. Seven residential wells sampled exceeded EPA Removal Action Levels, while an additional thirty-nine residential wells exceeded Maximum Contaminant Levels (MCLs). At least part of this contamination is potentially attributable to the Site. In response, the Navy has conducted a CERCLA removal action, installing a water treatment system in each residence whether either EPA Removal Action Levels or MCLs have been exceeded.

The EPA determined this off-site groundwater contamination may present an imminent threat to human health. In response, the EPA and the Navy have conducted additional CERCLA removal action work which provided residences exceeding EPA Removal Action Levels, as well as residences in the immediate path of the groundwater contamination, with connections to public water supply systems. The work completed under this Removal Action is considered to be Operable Unit Two (OU-2).

In August 1994, The Navy released a Focused Feasibility Study (FFS) Report for OU-3 (contaminated groundwater attributable to Area C) at the Site. The FFS for OU-3 developed several remedial alternatives for addressing contaminated groundwater attributable to Area C. From June 1994 through December 1994, the EPA initiated and completed construction of the removal action for OU-2. In January 1995, the Navy initiated construction of the remedy for OU-1.
Remedy:  · Component 1: Existing Groundwater Extraction System
This component shall use the existing interim remedy Area A groundwater extraction system to contain the source area (DNAPL (dense non-aqueous phase liquid) zone), contain/remediate the source area groundwater dissolved contaminant plume and remediate a portion of the down gradient groundwater contaminant plume. The existing pumping of Warminster Municipal Authority Well No. 26 (WTMA 26) shall capture and remediate the balance of the down gradient groundwater contaminant plume.
· Component 2: Existing Groundwater Treatment System
This component shall consist of continued treatment of extracted Area A groundwater in the existing interim remedy groundwater treatment system (GWTS). This component shall include operation and maintenance of the existing system and monitoring of its performance.
· Component 3: Existing Discharge of Treated Groundwater
This component shall consist of the continued discharge of the treated Area A groundwater from the existing GWTS to an existing interim remedy chlorine contact chamber and to Outfall 001 through the existing pipeline to Little Neshaminy Creek. This component will also include regular monitoring and reporting of the quality of discharged water.
· Component 4: Institutional Controls
Institutional controls shall be implemented to prevent the use of Area A groundwater as long as it presents an unacceptable risk and to protect the integrity and effectiveness of the extraction well network. The institutional controls addressing current Naval Air Warfare Center (NAWC) property shall consist of restrictions to be included in deeds entered into for transfer of the property. The controls for current off-base property in Warminster Township will consist of the continued enforcement of a municipal ordinance that regulates well drilling. The controls for current off base property in Ivyland Borough will consist of enforcement of a well drilling regulation ordinance to be promulgated by Ivyland Borough.
· Component 5: Groundwater Monitoring
Groundwater monitoring shall consist of regularly collecting water level measurements and analyzing groundwater samples both from within and outside the contaminant plume to assess progress of remediation and to evaluate contaminant migration.

Estimated Capital Cost: $8,000
Estimated Annual O&M Costs: Not Present
Estimated Present Worth Costs: $5,044,000
Text:  View full-text ROD [ 2.13M ]
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