Corrective Action Investigation Plan for Corrective Action Unit 252: Area 25 Engine Test Stand 1 Decontamination Pad, Nevada Test Site, Nevada

Abstract

The Engine Test Stand-1 Decontamination Pad is located in Area 25 at the intersection of Road H and Road K and was designed for use as a mobile radiation checkpoint and for vehicle decontamination.The corrective action site consists of a concrete decontamination pad with a drain, a gravel-filled sump, two concrete trailer pads, and utility boxes. Contaminants of potential concern for the site include radionuclides, total volatile organic compounds, total semivolatile compounds, total petroleum hydrocarbons-as diesel range organics, Resource Conservation and Recovery Act metals, total pesticides, and polychlorinated biphenyls. Additional samples may also be collected at the discretion of the Site Supervisor. The formulation of a conceptual site model was used as an aid for the development of Data Quality Objectives for the site. The technical approach for investigating the site was discussed during the Data Quality Objective meeting held on April 28, 1999. The investigative strategy includes the following activities:• Conduct a utility survey prior to excavation activities.• Determine radiological field-screening levels using an Electra alpha/beta scintillator, a sodium iodide detector, or intrinsic germanium detector (or equivalent) by taking 20 background sample readings and calculating the mean plus two standard deviations.• Remove the gravel-fill from test pit locations in the sump with a backhoe prior to sampling soil in the sump.• Excavate three test pits with a backhoe. Samples will be collected at approximately 2-foot intervals to a maximum depth of about 12 feet below the ground surface (or the maximum reach of the backhoe). The planned locations for the test pits are as follows:-At the sump where the decontamination pad drain pipe discharged -Soil samples will be collected at the gravel-soil interface in each of the sump test pits. Soil samples will be collected from each test pit, at approximately 2-foot depth intervals until a sample has been collected below field-screening levels or to the maximum reach of the backhoe (about 12 feet below the ground surface or about 6 feet below the gravel/soil interface). At a minimum two depth intervals will be sampled.-At the test pit near the northeast corner of the decontamination pad, soil sampling will begin at ground surface and continue at approximately 2-foot depth intervals until a sample has been collected below field-screening levels or to the maximum reach of the backhoe (about 12 feet below ground surface). At a minimum two depth intervals will be sampled.-If field-screening results exceed field-screening levels at 12 feet below ground surface (or the maximum reach of the backhoe), then sampling will stop and the investigation will be rescoped.-If contaminants of potential concern are not detected above preliminary action levels, a Corrective Action Decision Document/Closure Report will be prepared.• Field screen for VOCs using a headspace technique with a photoionization detector.• Field survey for radioactivity using an Electra alpha/beta scintillato...