SECTION 1 INTRODUCTION

    On May 5, 1999 an Administrative Consent Order was issued to CSSA pursuant to §3008(h) of the SWDA, as amended by the RCRA, and further amended by the HSWA of 1984.  In accordance with the RFI requirements of the Consent Order, this RFI report has been prepared to document the environmental condition and site closure requirements of SWMU B-7 and to recommend further investigation, if necessary, or to provide documentation necessary for site closure.  The primary objective of the SWMU B-7 investigation is to determine if the site meets TNRCC requirements for closure, as described in Section 1.4, and to meet requirements of the consent order.

    This specific RFI was performed under AMC Contract F11623-94-D-0024, delivery order RL17, dated September 30, 1997.  AFCEE provided technical oversight for the delivery order.  Based upon the project SOW, a set of work plans were established to govern the fieldwork.  These include:

    For this RFI report, Section 1 provides the site-specific background, site description, a discussion of previous investigations, and closure standard.  Section 2 describes field actions and closure evaluation.  Section 3 summarizes the findings, evaluates the attainment of data quality objectives, provides recommendations, and certifies the site closure, if applicable.  References cited in this report are included in the Bibliography (Volume 1-1 of the Environmental Encyclopedia).

1.1           Background and Site Description

1.1.1   CSSA

    General information regarding the history and environmental setting of CSSA are 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.

1.1.2   SWMU B-7

1.1.2.1Site Description

    SMWU B-7 is a low priority site at CSSA that was reportedly used, at an unknown time, as an above-grade fired small arms ammunition brass disposal area.  CSSA personnel report finding live rounds at SWMU B-7, although this finding was not documented.  Prior to the initiation of this investigation, small arms ammunition brass and other metal debris was scattered on the ground surface at SWMU B-7.  Currently, SWMU B-7 is not used. 

    Background information regarding the location, size, and known historical use of SWMU B-7 is also included in the Environmental Encyclopedia (Volume 1-2, SWMU B-7).  Volume 1-2 includes a Chronology of Actions and a Site-Specific Work Plan for SWMU B-7.

1.1.2.2Potential Sources of Contamination

    As described above, small ammunition brass and other metal debris are the potential source of contamination at SWMU B-7.  Because munitions-related waste was disposed at the site, explosives are COCs.  Although there are no records indicating waste was burned at the site, it is considered to be a possibility.  Therefore, VOCs and metals are also COCs at SWMU B-7.

1.1.2.3Site Location

    SWMU B-7 is a 0.5 acre tract of gravelly sand and grass located in the North Pasture of CSSA (Figure B7-1).  The nearest CSSA boundary is located approximately 3,000 feet  to the west along Ralph Fair Road.  SWMU B-7 is approximately 350 feet long by 75 feet wide and is oriented northeast-southwest.  It is bounded by a gravel road to the west and a treeline/limestone embankment to the east.  Nearby environmental sites include AOC 43 located approximately 20 feet to the south of SWMU B-7, and SWMU B-24 located approximately 300 feet to the north of SWMU B-7.  The ground surface elevation at SWMU B-7 is approximately 1,270 feet above sea level.  The area ground surface slopes gently to the northwest.  Further details regarding the physiography of SWMU B-7 may be found in CSSA Environmental Encyclopedia, Volume 1-2.

1.2           Site Environmental Setting

1.2.1   Site Soils and Topography

    The soils at SWMU B-7 are representative of Tarrant Association, gently undulating (TaB) soils (Figure B7-2). The Tarrant Association, gently undulating, soils comprise approximately 14.3 percent of CSSA and are typical of prairie and plateau topography.  They occur in areas that lack streams.  Generally, Tarrant Association, gently undulating soils are dark colored, very shallow, calcareous, and clayey.  They are best suited for native grasses and range use.  Additional information about the Tarrant Association soils and other soils that occur at CSSA can be found in the CSSA Environmental Encyclopedia (Volume 1-1, Background Information Report).

    SWMU B-7 is located on a west-trending, very gentle slope.  There are no significant changes in topography and no ditches or trenches in the immediate vicinity of SWMU B-7.  An intermittent stream is located approximately 400 feet northwest of SWMU B-7.  This stream flows to the southwest.

1.2.2   Geology

    The Upper Glen Rose is the uppermost geologic strata in the area of SWMU B-7 and the north pasture (Figure B7-3). The Upper Glen Rose consists of beds of blue shale, limestone, and marly limestone, with occasional gypsum beds. Generally, it outcrops in stream valleys and at the ground surface. The thickness of the Upper Glen Rose is estimated to be between 0 and 150 feet at CSSA.  It is underlain by the Lower Glen Rose, which is estimated to be 300 feet thick beneath CSSA.  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 (regionally known as the Hensell Shale), 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 10 to 12 degrees to the south-southeast at CSSA.

    There are two major fault (shatter) zones at CSSA: the North Fault Zone and the South Fault Zone.  SWMU B-7 is located north of both the North and South Fault Zones.  Additional information on structural geology at CSSA can be found in the Environmental Encyclopedia (Volume 1-1).

1.2.3   Hydrology

    In general, the uppermost hydrologic layer at CSSA 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 Limestone.  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 that static well levels are discordant in adjacent wells completed in different beds.  Principal development of solution channels is limited to evaporate 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, principal 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, therefore 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.  Groundwater flow within the Middle Trinity aquifer is toward the south and southeast and the average transmissivity coefficient is 1,700 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.

    An intermittent stream is located approximately 400 feet northwest of SWMU B-7.  This creek runs southwest and joins another intermittent stream which in turn flows south and feeds into Salado Creek. 

1.2.4   Cultural Resources

    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.  The nearest cultural resource to the site is a World War II era trench located approximately 985 feet to the north.

1.2.5   Potential Receptors

    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 during December 15 and 16, 1999 in accordance with the TNRCC 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).

    There is no housing adjacent to SWMU B-7.  Generally, CSSA is a controlled access facility, so access is limited by a security guard and perimeter fence.

    The golden-cheeked warbler and black-capped vireo, which are both endangered species, may potentially reside in the area of SWMU B-7.  A potential habitat for the black-capped vireo lies directly south of SWMU B-7.

    A small herd of cattle is maintained on CSSA by the USDA-ARC.  The cattle roam freely throughout the Inner Cantonment and in 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 that overlook mechanical feeders and planted food plots is located in the Technical Approach Document for Risk Evaluation (Volume 1-6).  SWMU B-7 is located approximately 1000 feet west of hunting stand number 35.  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.

1.3           Previous Investigations

    Previous investigations performed at SWMU B-7 have been described in Volume 3-2, tab B-7 of the Environmental Encyclopedia.

    A field investigation conducted in 1993 revealed weapons crates, packing, and small caliber ammunition brass scattered over the ground surface at SWMU B-7.  An EM geophysical survey was performed in 1995 using an EM-31 Geonics instrument. No anomalies were found at the site (Parsons ES, 1995).

    Three surface soil samples were collected on March 5, 1996 at a depth of 0.5 to 1 foot as outlined in the work plan.  Sample numbers B7-SS01, B7-SS02, and B7-SS03 were obtained from the north, central, and south portions of SWMU B-7, respectively. The work plan indicated that soil borings were to be drilled if surface soil sampling results indicated that constituent concentrations exceeded background levels for soils.  However, the sample analyses, which were performed by ITS Laboratories, Inc., were deemed unusable by the EPA in 1999.  A Work Plan Amendment was subsequently created in support of resampling and analysis to replace the invalid laboratory data (RL17 Work Plan Amendment for Data Quality Rework at SWMU B-7).

1.4           Closure Standard

    As described in Section 4.3 of the Risk Assessment Technical Approach Document (Volume 1-6), CSSA has opted to pursue closure of SWMU B-7 under the Risk Reduction Rule (30 TAC §335).  If the site concentrations do not exceed background, then the site will be closed using RRS1.  If the site concentrations exceed 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.  However, if it is determined that the site cannot be closed to meet background concentrations, then the site will be closed under TRRP.  A notification of intent to close sites identified to date (including SWMU B-7) in accordance with the former RRR was sent to the TNRCC on July 12, 1999.  TNRCC 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 TNRCC Executive Director, then the owner is released from the deed recordation requirement.

    Since the COCs for SWMU B-7 soils are VOCs, metals and explosives, the cleanup levels should be the RLs for VOCs and explosives and the soil or rock background concentrations 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 Soils and Bedrock (Parsons, February 2002).

SECTION 3 CONCLUSIONS AND RECOMMENDATIONS

3.1           Conclusions

    SWMU B-7 is a low priority site reportedly used at an unknown time, as a fired small arms ammunition brass disposal area.  Live rounds were observed at the site by CSSA personnel, although the finding was not documented.  All surface debris was removed by UXO specialists during a sweep for UXO in March 1997.  The potential COCs were determined to be metals, VOCs, and explosives.  A geophysical survey performed in 1995 revealed no subsurface anomalies.

    In 1996, three surface soil samples were collected from SWMU B-7 (central, northern, and southern portions of the site) and in 1999, EPA rejected the reported results from these three samples due to data quality issues associated with the analytical testing lab, ITS Laboratories.  Surface soil re-sampling of the same three locations was performed as a closure activity in March of 2000.  The reported results were below RRS1 background levels and closure criteria for all COCs.  Therefore, investigations revealed no suggestion of contamination, including no geophysical anomalies.

3.2           Evaluation of Data Quality Objectives Attainment

    Overall data quality objectives (DQOs) for the investigations at CSSA are provided in Volume 1-1 behind the RFI Addendum tab (Section 11 of the Work Plan Overview).  A detailed list of DQOs for SWMU B-7, along with an evaluation of whether each DQO has been attained, is provided in Appendix C.  As described in Section 1, the main objectives of the SWMU B-7 investigation are to determine if the site meets TNRCC requirements for RRS1 closure and to meet requirements of the 3008(h) Administrative Consent Order.

    All data generated during the SWMU B-7 investigation were reviewed to confirm conformance with the AFCEE QAPP; the data verification reports are included in Appendix B.  All data are considered usable for site characterization and closure purposes.  All of the initial calibration, second source verification and internal standard criteria were within quality control limits, as described in the data verification reports (Appendix B).  Other than the “U” (nondetect) flag, the only other flag associated with the SWMU B-5 data was the “F” flag, which signifies results between the MDL and the RL. 

3.3           Recommendations

    The work plan indicated that, if surface soil sampling revealed constituent concentrations that exceeded background levels for soils, soil borings were to be advanced.  However, advancement of soil borings was not required because the surface soil samples collected in March 2000 met RRS1 closure standards.  Site closure is recommended under RRS1 for SWMU B-7 since RRS1 closure standards were met.  Furthermore, the site history and previous investigations do not suggest any below-surface contamination.  Closure certification is provided on the next page.

3.4           Certification

PARTIAL FACILITY CLOSURE CERTIFICATION
SOLID WASTE MANAGEMENT UNIT B-7

Department of the Army
Camp Stanley Storage Activity
Boerne, Texas

    I certify that the above-described closure was performed under my direction, in accordance with the work plan and 30 TAC §335 Subpart S, and as described in this report, and that, to the best of my knowledge and belief, said closure has been successfully accomplished.