Final Second Five-Year Review Report Fort Ord Superfund Site ...

6.0 OU 2 ROD – FORT ORD LANDFILLS
This section presents background information on OU 2 ― Fort Ord Landfills; a summary of remedial
actions and a technical assessment of the actions taken at the site; identifies any issues related to the
protectiveness of the remedy based on the review; presents recommendations and follow-up actions, if
needed, to address issues identified during the review; and provides a statement regarding the
protectiveness of the site remedies.
6.1 OU 2 Background
Operable Unit 2 (OU 2), the Fort Ord Landfills site, consists of landfills covering approximately
150 acres, the immediate surrounding area, and the underlying contaminated groundwater (Plate 2).
The landfills were used for over 30 years for residential and commercial waste disposal. The landfills
include six cells, Cells A through F. Cell A was located north of Imjin Road and Cells B through F are
located south of Imjin Road. Cell A operated from 1956 to 1966. Cells B through F operated from 1960
until 1987, and may have received a small amount of chemical waste along with household and
commercial refuse. The landfill stopped accepting waste for disposal in May 1987 because of the
initiation of interim closure of the facility.
As a result of detections of VOCs in Fort Ord and Marina County Water District water supply wells, the
Regional Water Quality Control Board (RWQCB) issued Cleanup and Abatement Order (CAO) 86-87
that required Fort Ord to initiate studies of soil and groundwater to assess the potential impact of the
Fort Ord Landfills on underground water resources. The RWQCB also issued CAO Nos. 86-317
and 88-139 for the investigation and cleanup of groundwater contamination caused by the landfills and
Waste Discharge Report No. 87-153 requiring landfill closure by 1989. The Army initiated studies
(HLA, 1988) to evaluate whether chemicals from the landfills had affected either soil beneath the landfills
or the quality of groundwater beneath the sites, or both.
The Final Remedial Investigation Report (Dames and Moore, 1993a) indicated the presence of low levels
of semi-volatile organic compounds (SVOC) and pesticides in soil at maximum total detected
concentrations of 5.6 milligrams per kilogram (mg/kg) and 0.12 mg/kg, respectively. Metals were also
detected in all soil samples. Soil gas sampling detected VOCs and methane, and VOCs were also
detected in groundwater samples collected from both the A-Aquifer and the 180-Foot Aquifer. TCE was
the most frequently detected chemical in groundwater with a maximum concentration of 80 μg/l. Other
VOCs detected in groundwater samples included: tetrachloroethene (PCE), benzene,
cis-1,2-dichloroethene (DCE), and dichloromethane. Recent data indicates that a portion of the CT plume
described in Section 11 has migrated to the southeast where it commingles with the OU 2 plume.
6.2 Remedial Actions
6.2.1 Remedy Selection
The following five remedial alternatives were evaluated in the FS (Dames and Moore, 1993a):
• Alternative 1: NoA
• Alternative 2: Containment
• Alternative 3: A-Aquifer Cleanup and Landfill Capping.
• Alternative 4: A-Aquifer Cleanup and Landfill Capping – IA on the 180-Foot Aquifer
Final
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FORMER FT ORD 5YR REVIEW 2007_FINAL United States Department of the Army