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AOC 54 Final Closure Report
Section 1 - Introduction
On May 5, 1999 an Administrative Consent Order was issued to Camp Stanley Storage Activity (CSSA) pursuant to §3008(h) of the Solid Waste Disposal Act (SWDA), as amended by the Resource Conservation and Recovery Act (RCRA), and further amended by the Hazardous and Solid Waste Amendments (HSWA) of 1984. This report documents the closure activities at Area of Concern (AOC)-54.
The closure work was performed by Parsons under the U.S. Air Force Environmental Remediation and Construction (ENRAC) Contract F41624-01-D-8544, Task Order 19 (TO 0019). The Air Force Center for Environmental Excellence (AFCEE) provided technical oversight for the delivery order. Based on the project statement of work (SOW), a set of work plans to govern the fieldwork was established. These include:
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Work Plan Overview |
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Site-Specific Work Plan |
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Field Sampling Plan |
(Volume 1-4, TO 0019 Addendum); and |
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Health and Safety Plan |
Section 1 of this closure report provides the site-specific background and closure standard. Section 2 describes closure activities and the closure evaluation. Section 3 summarizes the findings, evaluates attainment of data quality objectives (DQO), provides recommendations, and certifies the site closure. References cited in this report can be found in the Bibliography (Volume 1-1 of the Environmental Encyclopedia).
As described in Section 4.3 of the Risk Assessment Technical Approach Document (Volume 1-6), CSSA opted to pursue closure of many of its sites under the Risk Reduction Rules (RRR) (30 Texas Administrative Code [TAC] §335). A notification of intent to close sites identified to date (including AOC‑54) was sent to the Texas Commission on Environmental Quality (TCEQ) on July 12, 1999 in accordance with the RRR. TCEQ acceptance of this notification was received on October 5, 1999.
Following RRR guidelines, if site concentrations are at or below background, and all waste and waste residue have been removed, then the site can be closed under Risk Reduction Standard 1 (RRS1). Background levels are the RRS1 criteria for metals concentrations, and laboratory reporting limits (RL) are the RRS1 criteria for organic compounds, if present. CSSA has opted to clean AOC‑54 to background levels and pursue closure under RRS1. If closure requirements under RRS1 are attained and approved by the TCEQ Executive Director, CSSA would be released from the deed recordation requirement.
1.2 - Background and Site Description
General information regarding the history and environmental setting of CSSA is provided in the CSSA Environmental Encyclopedia (Volume 1-1, Background Information Report). In that report, data regarding geology, hydrology, and physiography are also available for reference.
AOC‑54 is located in the southern portion of the Inner Cantonment near the deer processing station and has an area of approximately 0.2 acre. The site was used for battery storage. Figure AOC54-1 (based on a 2003 aerial photograph) shows the location of AOC‑54 within CSSA. Figure AOC54-2 shows a progression of historical aerial photographs of the site, starting in 1957 and progressing to the most recent photograph available, taken in 2003. This area has also been used for storage of general construction materials and it is a vehicle turnaround area along the dirt road. A thick metal plate, measuring approximately 6 feet by 8 feet by 2 inches thick, was situated at the site and is the presumed location that batteries were stored.
1.2.2.2 Potential Sources of Contamination
No formal waste management activities were known to occur at AOC‑54, although the site is in an area that was used for battery storage. Based on prior usage of the site, chemicals of potential concern only include metals (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, and zinc). Soil pH is also a concern which may be indicative of past battery acid spills. Explosives, volatile organic compounds (VOC), and semivolatile organic compounds (SVOC) are not a concern at this site since no evidence of waste disposal, burning activities, or ammunition is present.
AOC‑54 is located in the southern portion of CSSA, in the approximate center of the Inner Cantonment area. AOC‑54 is approximately 3,300 feet from the nearest facility boundary to the west. The site is approximately 1,800 feet to the east of SWMU B‑34 and approximately 1,800 feet west of SWMU B‑12 (Figure AOC54-1).
A detailed description of the environmental setting associated with CSSA is provided in the CSSA Background Information Report (Volume 1-1). Site-specific descriptions are provided below.
In general, soil at CSSA is thin, dark-colored, gravely clay and loam. The soil types are strongly influenced by topography and the underlying limestone. The soil at AOC‑54 is classified as Brackett soil, which covers a large portion of the Inner Cantonment area at CSSA (Figure AOC54-3). This loamy and clayey soil is thin (about 4 inches thick), grayish-brown, strongly calcareous, and occurs on slopes of 12 to 30 percent. In addition to Brackett soil at the site, Crawford and Bexar stony soil occurs in areas near the site. The elevation of the ground surface at AOC‑54 is approximately 1,290 feet above sea level, with the ground surface sloping toward the southwest.
The Upper Glen Rose (UGR) is the uppermost geologic strata in the area of AOC‑54 (Figure AOC54-4). The UGR consists of beds of blue shale, limestone, and marly limestone, with occasional gypsum beds (average thickness 50 feet). The UGR is underlain by the Lower Glen Rose (LGR) (average thickness 320 feet). The LGR is underlain by the Bexar Shale (BS) member of the Hensell Sand (average thickness 60 feet) and the Cow Creek (CC) Limestone (average thickness 76 feet). The geologic strata at CSSA dip approximately 10 to 12 degrees to the south-southeast.
The uppermost hydrogeologic layer at CSSA is the unconfined Upper Trinity aquifer, which consists of the UGR Limestone. Locally at CSSA, low-yielding perched zones of groundwater can exist in the UGR. Transmissivity values are not available for the UGR. Regionally, groundwater flow is thought to be enhanced along fractures and bedding contacts; however, the hydraulic conductivity between beds is thought to be poor. This interpretation is based on the observation of different static well levels in adjacent wells completed in different beds. Principal development of solution channels is limited to evaporite layers in the UGR Limestone.
The Middle Trinity aquifer is unconfined and functions as the primary source of groundwater at CSSA. It consists of the LGR Limestone, the BS, and the CC Limestone. The LGR Limestone outcrops north of CSSA along Cibolo Creek and within drainages in the central and southwest portions of CSSA. As such, the principal recharge into the Middle Trinity aquifer is via precipitation infiltration at outcrops. At CSSA, the BS is interpreted as a confining layer, except where it is fractured and faulted, therefore allowing vertical flow from the up-dip CC Limestone into the overlying, but down-dip LGR. Fractures and faults within the BS may allow hydraulic communication between the LGR and CC Limestones. Groundwater flow within the Middle Trinity aquifer is toward the south and southeast and the average transmissivity coefficient is 1,700 gallons per day per foot (gpd/ft) (Ashworth, 1983). In general, groundwater at CSSA flows in a north to south direction. However, local flow gradient may vary depending on rainfall, recharge, and possibly well pumping.
No site-specific information regarding groundwater is available. However, the nearest well, Well CS-MW18-LGR, is located approximately 1900 feet west of AOC‑54. Between September 2002 and June 2003, water levels within Well CS-G ranged from 145.11 feet below top of casing (BTOC) (September 2002) to 190.00 feet BTOC (June 2003) (Volume 5, Introduction to Groundwater Monitoring Program, Table 3). According to the Final September 2003 On-Post Quarterly Monitoring Report (Volume 5, Groundwater), toluene was detected in Well CS-MW18-LGR above the RL but below the maximum contaminant level (MCL).
The nearest surface water bodies are two intermittent drainages located near AOC‑54, approximately 450 feet and 1,500 feet southwest and northwest, respectively, from the site. Both of these drainages are usually dry except for periods following heavy rains. More detailed hydrology information for CSSA is included in the CSSA Background Information Report (Volume 1-1).
Four surface water reservoirs are maintained at CSSA for the purpose of fire protection and sport fishing. Two reservoirs are located in the northwestern and northeastern portions of the North Pasture and the other two reservoirs are located near the western boundary of the Inner Cantonment. None of the water reservoirs are within 0.25 mile of AOC‑54 and none receive surface water discharge from AOC‑54.
Cultural resources are prehistoric and historic sites, structures, districts, artifacts, or any other physical evidence of human activity considered important to a culture, subculture, or community for scientific, traditional, or religious purposes. There are no historical structures or buildings within the boundaries of AOC‑54. The nearest potentially significant cultural resources near AOC‑54 are sites 41BX1235 and 41BX1163, identified in two 1998 (March and April) Archeological Surveys (Volume 1-6, Other Plans and Approaches).
Site 41BX1235 in the Outer Cantonment, approximately 1 mile northeast of AOC‑54, consists of a series of military training trenches cut mostly into bedrock. Site 41BX1163, within the Inner Cantonment, approximately 0.75 mile northeast of AOC‑54, also consists of military training trenches. The 41BX1163 trenches were used as a movie set for Wings, the 1927 Academy Award winner for Best Picture, the first such award given. Both sites were recommended for potential eligibility status in the National Register of Historic Places after the 1998 surveys.
A land use survey identifying local and possible future uses of groundwater and surface water, a water well survey, and sensitive environmental areas at CSSA was completed on December 15 and 16, 1999. Results of that survey, along with results from a more in-depth survey to identify potential receptors, points of human exposure, and possible constituent pathways, are presented in Section 3 of the Technical Approach Document for Risk Evaluation (Volume 1-6).
A small herd of cattle is maintained on CSSA by the USDA. The cattle roam freely in selected areas of the North Pasture. CSSA also manages wild game species for the purpose of hunting. White-tailed deer, axis deer, and wild turkey all roam freely throughout CSSA. A map of deer hunting stands which overlook mechanical feeders and planted food plots is located in Figure 5.2 of the Technical Approach Document for Risk Evaluation (Volume 1-6). AOC‑54 is located approximately 900 feet north of hunting stand number 10 and approximately 1000 feet west of hunting stand number 7 (see Figure AOC54-1 above).
As mentioned previously, four reservoirs are maintained at CSSA. Two reservoirs are located in the northwestern and northeastern portions of the North Pasture, and the other two reservoirs are located near the western boundary of the Inner Cantonment.
The nearest potential habitat location for local endangered species for the Golden-cheeked warbler, which is approximately 1,500 feet southeast of AOC‑54. A Black-capped vireo habitat is also located approximately 4,000 feet northeast of the site area (ES, 1993b).
No previous investigations have been conducted at AOC‑54.