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SWMU I-1 RCRA Facility Investigation 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 Safe Drinking Water Act (SDWA), as amended by Resource Conservation and Recovery Act (RCRA), and further amended by the Hazardous and Solid Waste Amendments (HSWA) of 1984. In accordance with the RCRA Facility Investigation (RFI) requirements of the Consent Order, this report has been prepared to document the environmental condition and site closure requirements of solid waste management unit (SWMU) I-1 and to recommend further investigation, if necessary, or to provide documentation necessary for site closure. The main objectives of the SWMU I-1 investigation are to determine if the site meets Texas Commission on Environmental Quality (TCEQ) requirements for closure, as described in Section 1.4, and to meet the requirements of the Consent Order.
This specific RFI was performed by Parsons under the Air Mobility Command (AMC) Contract F11623-94-D-0024 (Delivery Orders [DOs] RL17 and RL53). The Air Force Center for Environmental Excellence (AFCEE) provided technical oversight for the DO. The following work plans were prepared to govern the fieldwork:
|
Work Plan Overview |
(Volume
1-1,
RL17 and
RL53
Addendum) |
|
Site-Specific Work Plan |
|
|
Field Sampling Plan |
|
|
Health and Safety Plan |
For this report, Section 1 provides the site-specific background and closure standard. Section 2 describes field actions and the closure evaluation, Section 3 summarizes the findings, evaluates attainment of data quality objectives (DQOs), provides recommendations, and certifies the site closure, if applicable. References cited in this report can be found in the Bibliography (Volume 1-1, Environmental Encyclopedia).
1.1 - 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 the geology, hydrology, and physiography are also available for reference.
SWMU I-1 consists of an incinerator located in Building 294 and the immediate area surrounding Building 294. Building 294 is constructed of red brick and rests on a concrete riser that elevates the building above the ground surface. From 1943 to the late 1960s, SWMU I-1 was reportedly used for burning paper trash. Subsequently, during the late 1980s, the SWMU was used as a storage facility for electrical transformers. At present, there is no plan to demolish or remove Building 294.
The site area is small, covering approximately 0.25 acres in area. A gravel road, west of and a paved road immediately north of the site, which intersect to the northwest of the area (Figure I1-1).
Background information regarding the location, size, and known historical use of SWMU I-1 is also included in the Environmental Encyclopedia (Volume 1-2, SWMU I‑1). Volume 1-3 also includes a Chronology of Actions and a Site-Specific Work Plan for SWMU I-1.
1.1.2.2 Potential Sources of Contamination
Incinerator Building 294, located on SWMU I-1, was used to dispose of waste material from 1943 to the late 1960’s. In the 1980’s, Building 294 was also used as a storage facility for electrical transformers. Since the site was used for burning wastes and storage of electrical transformers, the contaminants of concern (COCs) include volatile organic compounds (VOCs), metals, dioxins and furans, and polychlorinated biphenyls (PCBs). VOC analyses are included to test for the presence of contaminants commonly associated with disposal sites. Metals (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, and zinc) are included due to the metallic nature of waste generated at CSSA. A dioxins and furans wipe sample was collected because these compounds can be associated with incineration activities. PCB analyses are included because the electrical transformers stored in the building may have contained oils with PCBs present.
The site is located in the southwestern portion of the Inner Cantonment area of CSSA, approximately 1,000 feet east of the western boundary of CSSA and approximately 650 feet from the southern boundary (Figure I1-1). The CSSA wastewater treatment facility is located approximately 200 feet south of I-1 and SWMUs B-29, B-30 and AOC 50 are all located within 300 feet, on the eastern side of the site.
1.2 - Site Environmental Setting
1.2.1 Site Soils and Topography
SWMU I-1 rests on a thin extension of Krum Complex soil, which is surrounded by Crawford and Bexar Stony soils (Figure I1-2). Krum Complex soils are typically dark grayish-brown or very dark grayish-brown, calcareous, and approximately 30 inches thick. Detailed descriptions of the various soil types present at CSSA are located in the CSSA Environmental Encyclopedia (Volume 2, Description of Soil Types and Bedrock). The soil profile at SWMU I-1 extends from approximately 0.7 to 1.5 feet below ground surface (bgs) before weathered limestone bedrock is encountered (see borings logs in Appendix A). Native grasses and shrubs cover the site area. A thicket of oak trees surrounds the south and southeastern portions of the site.
SWMU I-1 sits at approximately 1,180 to 1,185 feet above sea level and the ground surface at the site dips gently to the east-southeast (Figure I1-2).
The Lower Glen Rose is the uppermost geologic stratum in the area of SWMU I-1 (Figure I1-3). The Lower Glen Rose is a massive, fossiliferous, vuggy limestone that grades upwards into thin beds of limestone, marl, and shale. The Lower Glen Rose is underlain by the Bexar Shale faces of the Hensell Sand, which is estimated to be from 60 to 150 feet thick under the CSSA area. The Bexar Shale consists of silty dolomite, marl, calcareous shale, and shaley limestone. The geologic strata dip approximately one to two degrees to the south-southeast at CSSA.
Based on current published information, there are two major fault (shatter) zones at CSSA: the North Fault Zone and the South Fault Zone. SWMU I-1 is located approximately 400 feet north of the southern fault zone (Figure I1-3). Additional information on structural geology at CSSA can be found in the Environmental Encyclopedia (Volume 1-1, Background Information Report).
At CSSA, the uppermost hydrogeologic layer is the unconfined Upper Trinity aquifer, which consists of the Upper Glen Rose Limestone. Locally at CSSA, low-yielding perched zones of groundwater can exist in the Upper Glen Rose. Transmissivity values are not available for the Upper Glen Rose. Regionally, groundwater flow is thought to be enhanced along the bedding contacts between marl and limestone; however, the hydraulic conductivity between beds is thought to be poor. This interpretation is based on the observation of discordant static water levels in adjacent wells, completed in different beds. Principle development of solution channels is limited to evaporite layers in the Upper Glen Rose Limestone.
The Middle Trinity aquifer is unconfined and functions as the primary source of groundwater at CSSA. It consists of the Lower Glen Rose Limestone, the Bexar Shale, and the Cow Creek Limestone. The Lower Glen Rose Limestone outcrops north of CSSA along Cibolo Creek and within the central and southwest portions of CSSA. As such, principle recharge into the Middle Trinity aquifer is via precipitation infiltration at outcrops. At CSSA, the Bexar Shale is interpreted as a confining layer, except where it is fractured and faulted, allowing vertical flow from the up-dip Cow Creek Limestone into the overlying, but down-dip Lower Glen Rose. Fractures and faults within the Bexar Shale may allow hydraulic communication between the Lower Glen Rose and Cow Creek Limestones. Regional 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 feet (gpd/ft) (Ashworth, 1983). In general, groundwater at CSSA flows in a northeast to southwest direction. However, local flow gradient may vary depending on rainfall, recharge, and possibly well pumping.
No site-specific information regarding groundwater is available. The nearest wells CS-MW10-LGR and CS-MW10-CC are approximately 1,000 feet to the west (Volume 5). These monitoring wells monitor both the Lower Glen Rose and the Cow Creek portions of the Middle Trinity Aquifer. Water levels have been monitored on a weekly basis since July 2002. Water levels in CS-MW10-LGR were measured at a high of 32.54 feet below top of casing (BTOC) in July 2002 and a low of 203.64 feet BTOC in June 2002. Similarly, CS-MW10-CC was measured at a high of 39.37 feet BTOC in July 2002 and a low of 195.99 feet BTOC in June 2002.
The nearest surface water body is the “W-Tank”, which is a pond located approximately 500 feet north of the site (Figure I1-1).
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. All of the structures on the
installation, including Building 294 (SWMU I-1), are considered historical
resources.
Aside from
Building 294 itself, the next closest cultural resources are warehouses to the
west, including Building 94, 96, and others.
The trenches, which have retained much of their original design
features, are located approximately 2,500 feet northeast of SWMU I-1.
A land use survey discussing local and possible future uses of groundwater and surface water, a water well survey, and sensitive environmental areas at CSSA was completed on December 16, 1999 in accordance with the TCEQ Texas Risk Reduction Program (TRRP). The results of this survey, along with results from a more in-depth survey to identify potential receptors, points of human exposure and possible constituent pathways is presented in Section 3 of the Technical Approach Document for Risk Evaluation (Volume 1-6).
Land use within ¼-mile of SWMU I-1 is classified as “Commercial and Services,” “Residential,” and “Evergreen Forest Land” in Figure 1.1 of the Technical Approach Document for Risk Assessment. Several warehouses are located within ¼-mile on the west side of the site. A full-time staff of approximately 25 employees mans these warehouses. The residential area within ¼-mile of SWMU I-1 is the Leon Springs Villas subdivision which has numerous residences and is located just south of the CSSA perimeter fence.
Well LS-1, which is a public drinking water supply well maintained by Bexar-Metropolitan Water District, is located approximately 1,000 feet southeast of the site. Several new monitoring wells were installed on CSSA, west and northwest of I-1 in 2001. These wells, MW7-LGR, MW7-CC, MW8-LGR, MW8-CC, MW10-LGR, and MW10‑CC are all within ¼-mile of SWMU I-1. In addition, several more monitoring wells are scheduled or will be installed in the near future. All of these wells are used to monitor selected portions of the Middle Trinity Aquifer.
A small herd of cattle is maintained on CSSA by the United States Department of Agriculture – Agricultural Research Center (USDA-ARC). 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). SWMU I-1 is located approximately 1,400 feet west of hunting stand number 12. Four water tanks are maintained at CSSA for the purpose of sport fishing. Two of the tanks are located in the north western and north eastern portions of the North Pasture while the other two tanks are located near the western boundary of the Inner Cantonment. “W-Tank” is located approximately 500 feet north and upgradient of SWMU I-1. \
SWMU I-1 is located over 1.5 miles southwest of the nearest identified potential
habitat for the Black-capped Vireo, which is a local endangered species. The nearest identified potential habitat for
another endangered species, the Golden-cheeked Warbler, is located approximately
1,500 feet east of the site (Parsons ES, 1993).
No previous investigations were performed at SWMU I-1.
As described in Section 4.3 of the Risk Assessment Technical Approach Document (Volume 1-6), CSSA has opted to pursue closure of SWMU I-1 under the Risk Reduction Rule (RRR) (30 Texas Administrative Code [TAC] §335). If the site concentrations do not exceed background, then the site will be closed using Risk Reduction Standard 1 (RRS1). If the site exceeds background, then a determination will be made regarding the feasibility of cleaning the site to meet background concentrations. If the decision is made to clean the site to background, closure under RRS1 will be sought. A notification of intent to close sites identified to date (including I-1) in accordance with the former RRR was sent to the TCEQ on July 12, 1999. TCEQ acceptance of this notification was received on October 5, 1999.
RRS1 requires that the site be closed following removal or decontamination of waste, waste residues, and contaminated operation system components; and demonstration of attainment of cleanup levels (30 TAC §335.554). If closure requirements under RRS1 are attained and approved by the TCEQ Executive Director, then the owner is released from the deed recordation requirement.
Since the COCs for SWMU I-1 are VOCs, PCBs, dioxins and furans, and metals, the RRS1 standards should be the reporting limits (RLs) for VOCs, PCBs, dioxins and furans, and the CSSA soil or rock background values for metals. Background metals levels were statistically calculated for CSSA soils and the Glen Rose Limestone, and are reported in the Second Revision to the Evaluation of Background Metals Concentrations in Soil Types (Parsons, February 2002). TCEQ approved the revised background evaluation on April 23, 2002.