Corrective Action Decision Document for Corrective Action Unit 271: Areas 25, 26, and 27 Septic Systems, Nevada Test Site, Nevada, Rev. 0

Abstract

This corrective action decision document (CADD) identifies and rationalizes the U.S. Department of Energy, National Nuclear Security Administration Nevada Operations Office's selection of a recommended corrective action alternative (CAA) appropriate to facilitate the closure of Corrective Action Unit (CAU) 271, Areas 25, 26, and 27 Septic Systems, Nevada Test Site (NTS), Nevada, under the Federal Facility Agreement and Consent Order (FFACO). Located on the NTS approximately 65 miles northwest of Las Vegas, CAU 271 consists of fifteen Corrective Action Sites (CASs). The CASs consist of 13 septic systems, a radioactive leachfield, and a contaminated reservoir. The purpose of this CADD is to identify and provide a rationale for the selection of a recommended CAA for each CAS within CAU 271. Corrective action investigation (CAI) activities were performed from October 29, 2001, through February 22, 2002, and April 29, 2002, through June 25, 2002. Analytes detected during the CAI were evaluated against preliminary action levels and regulatory disposal limits to determine contaminants of concern (COC) for each CAS. It was determined that contaminants of concern included hydrocarbon-contaminated media, polychlorinated biphenyls, and radiologically-contaminated media. Three corrective action objectives were identified for these CASs, and subsequently three CAAs developed for consideration based on a review of existing data, future use, and current operations in Areas 25, 26, and 27 of the NTS. These CAAs were: Alternative 1 - No Further Action, Alternative 2 - Clean Closure, and Alternative 3 - Closure in Place with Administrative Controls. Alternative 2, Clean Closure, was chosen as the preferred CAA for all but two of the CASs (25-04-04 and 27-05-02) because Nevada Administrative Control 444.818 requires clean closure of the septic tanks involved with these CASs. Alternative 3, Closure in Place, was chosen for the final two CASs because the short-term risks of transportation were eliminated; long-term health risks were minimized by preventing public and worker access to contaminated media through physical and administrative controls; all waste will be managed in accordance with federal, state, and local requirements; and a cost-effective method for achieving protection and meeting closure requirements is provided. All CAAs were evaluated on technical merit focusing on performance, reliability, feasibility, and safety. These two alternatives were judged to meet all applicable state and federal regulations for closure of the site and reduced the potential for future exposure pathways to the contaminated soils at this site.