Corrective Action Decision Document/Closure Report for Corrective Action Unit 560: Septic Systems, Nevada Test Site, Nevada, Revision 0

Corrective Action Unit 560 comprises seven corrective action sites (CASs): •03-51-01, Leach Pit •06-04-02, Septic Tank •06-05-03, Leach Pit •06-05-04, Leach Bed •06-59-03, Building CP-400 Septic System •06-59-04, Office Trailer Complex Sewage Pond •06-59-05, Control Point Septic System The purpose of this CADD/CR is to provide justification and documentation supporting the recommendation for closure of CAU 560 with no further corrective action. To achieve this, corrective action investigation (CAI) activities were performed from October 7, 2008, through February 24, 2010, as set forth in the Corrective Action Investigation Plan for Corrective Action Unit 560: Septic Systems, Nevada Test Site, Nevada, and Record of Technical Change No. 1. The purpose of the CAI was to fulfill the following data needs as defined during the data quality objective (DQO) process: •Determine whether contaminants of concern (COCs) are present. •If COCs are present, determine their nature and extent. •Provide sufficient information and data to complete appropriate corrective actions. The CAU 560 dataset from the investigation results was evaluated based on the data quality indicator parameters. This evaluation demonstrated the quality and acceptability of the dataset for use in fulfilling the DQO data needs. Analytes detected during the CAI were evaluated against final action levels (FALs) established in this document. The following contaminants were determined to be present at concentrations exceeding their corresponding FALs: •No contamination exceeding the FALs was identified at CASs 03-51-01, 06-04-02, and 06-59-04. •The soil at the base of the leach pit chamber at CAS 06-05-03 contains arsenic above the FAL of 23 milligrams per kilogram (mg/kg) and polychlorinated biphenyl (PCBs) above the FAL of 0.74 mg/kg, confined vertically from a depth of approximately 5 to 20 feet (ft) below ground surface. The contamination is confined laterally to the walls of the leach pit chamber and leach rock. The contamination present at CAS 06-05-03 within the leach pit was not feasible to remove. •The surface and subsurface soils within and surrounding the septic system at CAS 06-05-04 contained PCB concentrations above the FAL of 0.74 mg/kg. The lateral and vertical extent of COCs was determined for this CAS. Contaminated soils were removed up to within 18 ft of the building. The remaining contamination is confined to subsurface soils adjacent to and beneath Building CP-162 and was not feasible to remove. •The solid materials within the septic tank and soils immediately surrounding the inlet end of the tank at CAS 06-59-03 contained benzo(a)pyrene above the FAL of 0.21 mg/kg. The soils, tank contents, and tank were removed. Materials remaining at this CAS do not contain contamination exceeding FALs. •The solids contained within the septic tank and inlet pipe at CAS 06-59-05 contained the following contaminants above their respective FALs: PCBs, arsenic, lead, benzo(a)pyrene, and pesticides. The tank and inlet pipe contents were removed. Materials remaining at this CAS do not contain contamination exceeding FALs. Therefore, the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO) provides the following corrective action recommendations: •No further action for CASs 03-51-01, 06-04-02, and 06-59-04, as no contaminants of potential concern were present that exceed FALs. •Closure in place for CAS 06-05-03 under a corrective action with a use restriction (UR) for remaining PCB- and arsenic-impacted potential source material (PSM). The UR form and map have been filed in the NNSA/NSO Facility Information Management System, the FFACO database, and NNSA/NSO CAU/CAS files. •Closure in place for CAS 06-05-04 under a corrective action with a UR for remaining PCBs in soil adjacent to and beneath Building CP-162. The UR form and map have been filed in the NNSA/NSO Facility Information Management System, the FFACO database, and NNSA/NSO CAU/CAS files. •No further action for CAS 06-59-03, as the COC of benzo(a)pyrene in soil and PSM have been removed. •No further action for CAS 06-59-05, as the COCs in PSM within the septic tank and inlet piping have been removed and the tank was filled with concrete

Addendum to the Closure Report for Corrective Action Unit 427: Area 3 Septic Waste Systems 2, 6, Tonopah Test Range, Nevada, Revision 0

This document constitutes an addendum to the April 1999, Closure Report for Corrective Action Unit 427: Area 3 Septic Waste Systems 2, 6, Tonopah Test Range, Nevada as described in the document Recommendations and Justifications for Modifications for Use Restrictions Established under the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office Federal Facility Agreement and Consent Order (UR Modification document) dated February 2008. The UR Modification document was approved by NDEP on February 26, 2008. The approval of the UR Modification document constituted approval of each of the recommended UR modifications. In conformance with the UR Modification document, this addendum consists of: • This cover page that refers the reader to the UR Modification document for additional information • The cover and signature pages of the UR Modification document • The NDEP approval letter • The corresponding section of the UR Modification document This addendum provides the documentation justifying the cancellation of the URs for: • CAS 03-05-002-SW02, Septic Waste System • CAS 03-05-002-SW06, Septic Waste System These URs were established as part of Federal Facility Agreement and Consent Order (FFACO) corrective actions and were based on the presence of contaminants at concentrations greater than the action levels established at the time of the initial investigation (FFACO, 1996; as amended August 2006). Since these URs were established, practices and procedures relating to the implementation of risk-based corrective actions (RBCA) have changed. Therefore, these URs were re-evaluated against the current RBCA criteria as defined in the Industrial Sites Project Establishment of Final Action Levels (NNSA/NSO, 2006c). This re-evaluation consisted of comparing the original data (used to define the need for the URs) to risk-based final action levels (FALs) developed using the current Industrial Sites RBCA process. The re-evaluation resulted in a recommendation to remove these URs because contamination is not present at these sites above the risk-based FALs. Requirements for inspecting and maintaining these URs will be canceled, and the postings and signage at each site will be removed. Fencing and posting may be present at these sites that are unrelated to the FFACO URs such as for radiological control purposes as required by the NV/YMP Radiological Control Manual (NNSA/NSO, 2004f). This modification will not affect or modify any non-FFACO requirements for fencing, posting, or monitoring at these sites

Recommendations and Justifications for Modifications for Use Restrictions Established under the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office Federal Facility Agreement and Consent Order, Revision 0

This document is part of an effort to re-evaluate all FFACO URs against the current RBCA criteria (referred to in this document as the Industrial Sites [IS] RBCA process) as defined in the Industrial Sites Project Establishment of Final Action Levels (NNSA/NSO, 2006c). Based on this evaluation, the URs were sorted into the following categories: 1. Where sufficient information exists to determine that the current UR is consistent with the RCBA criteria 2. Where sufficient information exists to determine that the current UR may be removed or downgraded based on RCBA criteria. 3. Where sufficient information does not exist to evaluate the current UR against the RCBA criteria. After reviewing all the existing FFACO URs, the 49 URs addressed in this document have sufficient information to determine that these current URs may be removed or downgraded based on RCBA criteria. This document presents recommendations on modifications to existing URs that will be consistent with the RCBA criteria

Corrective Action Decision Document/Closure Report for Corrective Action Unit 266: Area 25 Building 3124 Leachfield, Nevada Test Site, Nevada

This Corrective Action Decision Document/Closure Report (CADD/CR) was prepared for Corrective Action Unit (CAU) 266, Area 25 Building 3124 Leachfield, in accordance with the Federal Facility Agreement and Consent Order. Located in Area 25 at the Nevada Test Site in Nevada, CAU 266 includes Corrective Action Site (CAS) 25-05-09. The Corrective Action Decision Document and Closure Report were combined into one report because sample data collected during the corrective action investigation (CAI) indicated that contaminants of concern (COCs) were either not present in the soil, or present at concentrations not requiring corrective action. This CADD/CR identifies and rationalizes the U.S. Department of Energy, Nevada Operations Office's recommendation that no corrective action was necessary for CAU 266. From February through May 1999, CAI activities were performed as set forth in the related Corrective Action Investigation Plan. Analytes detected during the three-stage CAI of CAU 266 were evaluated against preliminary action levels (PALs) to determine COCs, and the analysis of the data generated from soil collection activities indicated the PALs were not exceeded for total volatile/semivolatile organic compounds, total petroleum hydrocarbons, polychlorinated biphenyls, total Resource Conservation and Recovery Act metals, gamma-emitting radionuclides, isotopic uranium/plutonium, and strontium-90 for any of the samples. However, COCs were identified in samples from within the septic tank and distribution box; and the isotopic americium concentrations in the two soil samples did exceed PALs. Closure activities were performed at the site to address the COCs identified in the septic tank and distribution box. Further, no use restrictions were required to be placed on CAU 266 because the CAI revealed soil contamination to be less than the 100 millirems per year limit established by DOE Order 5400.5