In addition to the wastes generated directly from the primary mission activities, some waste streams are also generated from miscellaneous post support activities such as those associated with RFI activities, and waste removal activities in association with the Order. The specific activities that are anticipated in generating potential hazardous and nonhazardous wastes are discussed below.
This section describes activities in support of and in compliance with the USEPA Administrative Order on Consent, USEPA identification number TX2210020739, proceeding under Section 3008(h) of RCRA, as amended, 42 U.S.C. Section 6928(h).The objectives of the RFI include:
Identifying possible releases;
Investigating and preventing the further spread of identified releases of hazardous waste and /or hazardous constituents to the environment at and/or from the facility; and
Ensuring that corrective actions protect human health and environment.
In addition to this addendum to the SAP, the Quality Program Plans (QPP), are included in Volume 1-4 and Volume 1-5, respectively. The QPP includes the Sampling and Analysis Plan (SAP) and the Health and Safety Plan (HASP). The SAP consists of the Quality Assurance Project Plan (QAPP) and the Field Sampling Plan (FSP). The SAP is included in Volume 1-4 and the HASP is included in Volume 1-5. A detailed description of the RFI measures for each SWMU and AOC is provided in Volume 1-2 and Volume 1-3.
In addition to RFIs and other ongoing environmental investigations, CSSA has been undertaking a large-scale groundwater investigation and monitoring program to define the vertical and lateral extent of solvent plumes impacting the Middle Trinity Aquifer that serves municipal as well as domestic consumers in the vicinity of northwest San Antonio. Recent data suggest that the plume has moved beyond the boundaries of the government-owned facility, and has impacted off-post drinking water wells. The need for hydrologic characterization and plume delineation as soon as possible is the greatest priority to the facility.
To this end, CSSA has been aggressively implementing a groundwater monitoring program to address these issues in compliance with the Order. Phase I of this investigation, which included the installation of 15 new groundwater monitoring wells was recently completed. The Phase I wells took nearly a year to fully implement, and encountered many challenges including the handling of copious quantities of drilling material generated during their installation.
For Phase II, a total of 17 monitoring wells that are scheduled to be installed in three units of the Middle Trinity Aquifer underlying CSSA. The hydrologic units of interest are the Lower Glen Rose (LGR) Limestone, the Bexar Shale (BS), and the Cow Creek (CC) Limestone. The actual drilling depth will be a function of each well�s location and land surface elevation. In general, wells ranging between 120 to 500 feet below ground surface are to be installed during the Phase II drilling operation. The end product will be 13 wells with a nominal 4� diameter casing and maximum screen length of 25 feet. Additionally, four wells will be installed using the Westbay�s multilevel sampling system to approximate depths of 300 feet below ground surface. Depending on the hydrologic zone of interest, different well designs will be implemented to ensure the integrity of each monitoring point.
Drilling to depths up to 500 feet produces significant amounts of drill cuttings (soil and limestone) as well as groundwater. It is estimated that as much as 170 cubic feet (6.3 cubic yards) of soil drill cuttings can be generated from a single well. In addition, the relatively slow advance of the drill bit in relation to the pumping action inherent with the air rotary drilling methodology generates a large volume of extracted groundwater when drilling below the water table. As much as 28,000 gallons of groundwater may be produced during the course of drilling a single well.
Because of the previous experience of the Phase I drilling project, CSSA has estimated the amount of total solids and liquids that will be generated from the Phase II drilling as it is currently scoped. We anticipate approximately 100 cubic yards of solids (drill cuttings) and between 300,000 to 400,000 gallons of formation water (i.e. groundwater) to be generated during the well installation activities. As much as 100,000 additional gallons of groundwater will be generated during the development phase. Approximately 1,800 cubic yards (nearly 100 roll-off containers or 350,000 gallons) of drilling material (i.e., mud and groundwater) are expected to be generated over the 14-month drilling schedule.
Adequate storage capacity will be required to effectively handle the generated investigative derived media. Two options have been identified for management of the groundwater media. The first is use of 20-cubic yard containers during the Phase II well installation efforts. The second is the use of a settling basin located near CSSA�s outfall 002. CSSA believes the settling basin methodology is deemed to be a more economical and appropriate method of handling the generated drilling materials while continuing to be protective of human health and the environment. However, either management or a combination of both management methods may be used in managing the expected investigative derived media.
2.1.1 Management of Groundwater Investigation Derived Media
The first option allows for the use of approximately 140 20-cubic yard containers for management of Investigation Derived Waste (IDW) media. Approximately six containers per well will be required in order to handle the generation of media from well installations. Additionally, four containers will be staged at CSSA�s Outfall 002 for possible treatment requirements. This option assumes that all containers will be sampled before any resulting media management is to occur.
The second option allows for the use of settling basin(s) for management of groundwater investigative derived media. This options assumes that periodic sampling will occur before any resulting media management is to occur. At this time, CSSA does not anticipate using lined settling basins. Appropriate requirements will be met if the settling basins are used in the RFI, interim measures (IM) remediation, or other corrective action activities at CSSA.
For the second option, a drilling subcontractor would transport all generated drilling materials to the basins via vacuum truck. Depending upon the circumstances, two smaller ponds may be constructed to be more proximal to the two major areas of investigation, thereby reducing transport times. Multiple transportable 20 to 30-yard roll-off boxes will also be placed at each well cluster to temporarily contain drilling media when production occasionally exceeds the transportation capability of the drilling subcontractor. Periodically, sampling of the drilling materials will identify any additional management methods that may be necessary (i.e. if materials are above Texas Risk Reduction Program (TRRP) Tier 1 Protective Concentration Limits (PCLs) or Maximum Contaminant limits (MCLs) they would be routed through the granular activated carbon (GAC) unit at CSSA�s Outfall 002). If analysis of the materials indicates that the COCs are below the health based standards (PCLs or MCLs) they would be discharged to the ground surface. The use of TRRP Tier 1 PCLs or MCLs standards in determining management of investigative derived media are as applicable or relevant and appropriate requirements (ARARs).
Any remaining mud/solids will be sampled for Volatile Organic Compounds (VOCs) for characterization and managed as soil investigative derived media discussed in the following section 2.1.2.
2.1.2 Management of Solid Investigative Derived Media
Solids with VOC concentrations at or less than background will be transported and managed onsite as fill material. Concentrations of VOCs greater than subject criteria will require off-site disposal.
Periodically, sampling of solid investigative derived media will occur in order to identify appropriate management methods for the contained materials. If analysis of the materials indicates that the COCs are below the health based standards (i.e., TRRP Tier 1 PCLs) they will be discharged to the ground surface near the vicinity for which the media was generated. Otherwise, management of drilling materials will be in accordance with applicable laws and regulations.
The aforementioned management methods for the solid materials were authorized by letter dated August 12, 1996 from Mr. Richard Clarke of the TNRCC Corrective Action Section (attached), which specified Investigative Derived Waste (IDW) criteria for release to ground surface. Mr. Clarke indicated that any IDW which were below Risk Reduction Standard 2 criteria (identified in 30 TAC 335 subchapter S) were authorized for placement back onto the ground surface in the vicinity of extraction location. The use of TRRP Tier 1 PCLs standards in determining management of investigative derived media are as ARARs. CSSA intends to close all applicable sites under Risk Reduction Standard 1, as identified in 30 TAC 335 subchapter S, where practical.
As part of the Order, CSSA is to identify candidate technologies for a treatability studies program. The treatability studies program will include the following evaluations: (1) installation and operation of a system designed to recover and control migration of hazardous waste and constituents in ground water; (2) installation and operation of a system designed to recover and control migration of hazardous waste and constituents in soil; (3) installation and operation of a system designed to recover and control migration of hazardous waste and constituents in surface water; (4) installation and operation of a system designed to control migration of hazardous waste and constituents in air; and (5) any additional candidate technologies for a treatability studies program. The listing of candidate technologies will cover the range of technologies required for alternatives analysis. The specific data requirements for the testing program will be determined and refined during the RFI and corrective measures study (CMS) implementation. The treatability study(ies) shall include the following:
A literature survey to gather information on performance, relative costs, applicability, removal efficiencies, operation and maintenance (O&M) requirements, and implementability of candidate technologies. If practical candidate technologies have not been sufficiently demonstrated, or cannot be adequately evaluated for this site on the basis of available information, treatability testing will be conducted.
2.2.2 Evaluation of Technologies
Once a decision has been made to perform treatability studies, CSSA and USEPA will decide on the type of treatability testing to use (e.g., bench versus pilot). Because of the time required to design, fabricate, and install pilot scale equipment as well as perform testing for various operating conditions, the decision to perform pilot testing should be made as early in the process as possible to ensure that results are integrated into the evaluation of corrective measure alternatives within the CMS.
The program shall include innovative corrective action technologies when appropriate, especially in situations where there are a limited number of applicable existing corrective measure technologies.
The program shall rely on standard engineering practice to determine which of the previously identified technologies appear most suitable for the Facility. Technologies can be combined to form the overall corrective action alternatives. The alternatives developed should represent a workable number of option(s) that each appears to adequately address all site problems and corrective action objectives. Each alternative may consist of an individual technology or a combination of technologies.
The program shall evaluate and document the technology limitations of the corrective measure alternatives identified above which may prove infeasible to implement given the existing set of waste and site specific conditions.
Currently, CSSA�s treatability studies program has included Soil Vapor Extraction (SVE), Electrokinetic Remediation, Phytoextraction, Density Separation, and Stabilization. These technologies will continue to be investigated and are anticipated to generate potential hazardous waste and nonhazardous waste. A detailed description of the treatability studies planned is provided in Volume 1-2, Volume 1-3 and Volume 4.
Two SVE pilot systems are proposed for installation at AOC-65 to evaluate the potential for SVE to reduce the levels of contaminants detected in soils at the site. One system will consist of installing extraction wells beneath the floor of Building 90 will comprise the Building 90 subslab ventilation system. The second SVE system will consist of six vapor extraction wells (VEWs) and six multi-depth vapor monitoring points (VMPs) outside the building for use in the treatability study conducted at AOC-65. Building 90 subslab ventilation will be conducted in conjunction with the removal actions planned for AOC-65.
2.3 - Interim Removal Action(s)
Interim removal actions (IRAs) are planned for SWMU B-3 and AOC 65 are detailed in their respective workplans. Summaries of the planned removal actions are discussed below. Other IRA(s) will be presented in their respective workplan(s) as they are addressed.
The purpose of the IRA at AOC-65 is to excavate soil material with high VOC levels. Excavating the most contaminated areas will help reduce the amount of contaminants that migrate to the groundwater and surrounding areas. Another aspect of the removal action is installation of a subslab ventilation system in Building 90. The subslab ventilation system will act similarly to a soil vapor extraction system and will expedite reduction in the mass of accumulated VOCs beneath the building, as well as minimize any possible adverse impacts from soil vapors entering Building 90.
Based on results of previous investigations, it has been anticipated that any removal action inside the building will concentrate on the abandoned solvent storage pit former solvent tank vault and surrounding areas. The area to be excavated is preliminarily estimated to be 40 feet by 40 feet with an average depth of 5 feet, for a total of approximately 600 cubic yards of material.
If VOC levels present in fill material can be adequately reduced through subslab ventilation, excavation of fill materials beneath Building 90 and the contaminant removal of the former solvent tank vault and flooring may not be necessary. Parsons will prepare a comparative evaluation based on the soil boring samples and results of the subslab ventilation study to determine if any excavation activities are warranted.
If undertaken, excavation work inside Building 90 would include removal of the citrus cleaner storage container located on a metal plate above the former solvent tank vault. The outer dock of Building 90 might also be removed to facilitate better access to the excavation areas inside the building. Temporary wood walls with plastic lining will be constructed around the removal action area inside Building 90 and negative pressure airflow will be established to prevent unnecessary exposure to CSSA employees. One personal air monitoring station will be set up inside the excavation area and two stations will be set up inside the building outside the sealed temporary walls, to ensure that the engineering controls are effective. Since Building 90 is considered a historical building, coordination with the State Historical Preservation Office will be necessary if any modifications will be necessary.
The exact locations and extent of excavations to be performed outside Building 90 will be determined from results of the exterior soil borings. It is anticipated that asphalt and soil will be excavated along the abandoned drainpipe and the drainage ditch in the vicinity of the drainpipe outfall.
There are at least 20 gutters from Building 90 currently piped underneath the existing asphalt drive which discharge to the drainage ditch. Portions of the gutter system below the asphalt will also be excavated as part of the removal actions outside Building 90. Drainage from the gutters will be rerouted after completion of the removal actions so it is diverted from VOC source areas and disturbed recharge zones. Runoff diversion to the southwest or eastern side of the building is being considered.
All removal work will be performed in Level D personal protective equipment. The excavated material will be handled and disposed as determined by waste characterization testing. Confirmation samples will be taken from the drainpipe excavation and from the ditch. Depending on the size of the excavation, at least two samples will be collected to represent each excavated segment of pipe or ditch, or one sample for each 500 ft2 exposed area. Sampling methodology and quality control are described in the SAP addenda (AOC-65 Treatability Study Sampling and Analysis Plan Addendum, Parsons, April 2002).
An IRA will be performed to remove soils at SWMU B-3 to achieve closure of the soil zone under Texas Risk Reduction Rules, Standard 1. The closure methodology and procedures are described in Volume 1-1, Section 2. Background information on SWMU B-3 can be found in the RL74 RFI Work Plan Addendum and RL83 RFI Work Plan Addendum for Solid Waste Management Unit B-3 dated August 1999 (Volume 3-1 of the CSSA Environmental Encyclopedia).
Temporary stockpile areas, silt fencing for sediment control, and storm water diversion berms will be constructed as required for the work. The exact location of these features will be field-determined.
Prior to excavation, the existing SVE system will be dismantled. CSSA will remove the power to the SVE and disconnect electrical utilities, leaving all underground electrical utilities dead. Parsons will salvage the blower and remove above ground piping as needed.
Once the SVE system has been removed, the upper soil cover will be removed and stockpiled nearby for future use as fill or top soil. This clean fill stockpile will be sampled every 250 cubic yards to ensure no waste materials are placed back into the excavation. Waste characterization methodology is presented in Section 3 of this WMP. All foreign matter will be removed from the stockpile before using as a backfill material or it will be disposed of accordingly. Each of the trench�s contents and contaminated soils will be removed and placed in lined stockpile areas for eventual off-post disposal. Four stockpile areas will be constructed based on analytical data and field screening assessments:
Clean Stockpile,
Non-hazardous Class 1 Waste Stockpile,
Non-hazardous Class 2 Waste Stockpile, and
Scrap Stockpile.
The Class 1 and Class 2 waste stockpile areas will be lined with 20-mil plastic and bermed to divert run-on. Materials will be segregated based on the characterization performed during the RFI and photoionization detector (PID) readings taken during excavation. Metal debris that is deemed recyclable will be segregated into a scrap stockpile. The trench contents and impacted soil will be excavated to bedrock. Surveys of the excavation and stockpile will be made on a routine basis to document the volume of soil excavated and those designated for disposal. It is anticipated that as much as 8,000 cubic yards of soil will require some form of management.
Other IRA(s) for SWMUs and/or AOCs will be presented in their respective workplan(s) as they are addressed.