TO 0009 Environmental Cleanup Plan
Section 4 - Removal Action
The purpose of the removal action is to excavate soil and waste material from AOC 55. Excavating the identified areas will help reduce the amount of trash that migrate to the creek and surrounding areas.
Planning for the removal action will include determining the extent of excavations to be performed and securing the necessary approvals to proceed with the removal action (e.g., permitting). Detailed scopes of work will be prepared for drilling, analytical, and removal action subcontractors.
An investigation, described below in section 4.3 will be performed to provide a more reliable estimate of contamination in fill materials within AOC 55 and along Salado Creek. Data collected during the investigation, including laboratory testing of representative soil sample from the test trenches/pits will be used to assess the removal/disposal options for this project. The areal limits and depth of any excavations to be performed will be determined based on results of the investigation, plus the waste classification profile will be integrated into the SOW for the removal action subcontractor.
Exploratory investigation trenches will be excavated over areas of geophysical anomalies in an effort to verify or “ground-truth” the results of the geophysical surveys. Exploratory trenching will further define lateral and vertical extents of the geophysical anomalies, determine thickness of cover materials, as well as assist in the calculation of landfill material volume. Figure 4 shows the proposed locations of the trenching. The contents of the trenches will be examined and the waste material contained within them will be tested to confirm it is either hazardous or non-hazardous.
Soil samples will be collected from the soil overlying the landfill as well as from the trench material itself. AOC-55 COCs include VOCs, explosives, and metals but selected samples will be tested for SVOCs to ensure that they are not present.
Sample methodology and quality control procedures are described in the Sampling and Analysis Plan (SAP) for Solid Waste Management Unit (SWMU) Closures at Camp Stanley Storage Activity (CSSA) (Environmental Encyclopedia Volume 1-4, Field Sampling and Analysis Plan tab and QAPP tab) for Area of Concern (AOC) 55 Remedial Actions and additional details are provided in the AOC-55 SAP Addendum. Analytical results from the soil samples will help to further define the limits of the planned excavation(s), and should provide a relatively accurate estimate of the concentration of contamination in soils.
4.3.2 - Calculation of Waste Volume
Investigation results from the trenching efforts and soil samples will be used to estimate the waste volume of fill material within AOC 55. Using depth information from the trenching and geophysical contours, the volume of soil will be calculated.
4.4 - Implementation of Removal Action
4.4.1 - AOC 55 Removal Actions
Based on results of previous investigations, it has been anticipated that any removal action within AOC 55 will require UXO avoidance and identification efforts. The preliminary estimate of the area to be excavated is to be represented by a right triangle with an estimated 300-foot base, 550-foot side, and an estimated 10-foot depth, for a total of approximately 30,500 cubic yards of material. The remaining areas of AOC 55 located to the north and east of the main trench are estimated to contain 4,500 cubic yards of waste material for a total waste volume of 35,000 cubic yards.
As mentioned, during the preliminary investigation efforts, O/E scrap materials were identified. Due to these conditions additional efforts for continuing O/E scrap and UXO identification for the remaining material will be continued.
Parsons anticipates that all removal work can be performed in Level D personal protective equipment and will coordinate with CSSA operations so that traffic through the area will be at a minimum. The excavation equipment will remove landfill materiel starting on the eastern most landfill limit and moving west until all material has been visually screened for O/E scrap and/or UXO material. The excavated material will be handled and disposed of as determined by waste characterization testing. Confirmation samples will be collected for analysis following completion of the excavation activities.
One sample for each 1000 yds3 of excavated material will be collected. The number of trench material samples to be collected is therefore estimated to be thirty-five. Sample methodology and quality control procedures are described in the Sampling and Analysis Plan (SAP) for Solid Waste Management Unit (SWMU) Closures at Camp Stanley Storage Activity (CSSA) (Environmental Encyclopedia Volume 1-4, Field Sampling and Analysis Plan tab and QAPP tab) for Area of Concern (AOC) 55 Remedial Actions and additional details are provided in the AOC-55 SAP Addendum.
After completion of any excavation work at AOC 55, the excavation area will be grated to allow proper flow of Salado creek within the area.