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This closure report (CR) provides documentation for the closure of the Roller Coaster RADSAFE Area (RCRSA) Corrective Action Unit (CAU) 407 identified in the Federal Facility Agreement and Consent Order (FFACO) (Nevada Division of Environmental Protection [NDEP] et al., 1996). CAU 407 is located at the Tonopah Test Range (TTR), Nevada. The TTR is approximately 225 kilometers (km) (140 miles [mi]) northwest of Las Vegas, Nevada (Figure 1). The RCRSA is located on the northeast comer of the intersection of Main Road and Browne's Lake Road, which is approximately 8 km (5 mi) south of Area 3 (Figure 1). The RCRSA was used during May and June of 1963 to decontaminate vehicles, equipment, and personnel from the Double Tracks and Clean Slate tests. Investigation of the RCRSA was conducted from June through November of 1998. A Corrective Action Decision Document (CADD) (U.S. Department of Energy, Nevada Operations Office [DOEN], 1999) was approved in October of 1999. The purpose of this CR is to: Document the closure activities as proposed in the Corrective Action Plan (CAP) (DOEM, 2000). Obtain a Notice of Completion from the NDEP. Recommend the movement of CAU 407 from Appendix III to Appendix IV of the FFACO. …

1.1 Purpose The purpose of this investigation is to collect data to confirm the presence or absence of contamination, evaluate the potential for contaminant migration, and select appropriate closure methods for these sites. The potential closure methods for these sites involve either clean closure, closure in place, or no further action. 1.2 Scope The scope of this investigation includes collecting surface and subsurface soil samples at the Roller Coaster Lagoons; and collecting surface soil samples at the North Disposal Trench and the small spill area associated with the Voluntary Cotiective Action (VCA) that was conducted in 1995.

The North Disposal Trench, located north of the eastern most lagoon, was installed in 1963 to receive solid waste and construction debris from the Operation Roller Coaster man camp. Subsequent to Operation Roller Coaster, the trench continued to receive construction debris and range cleanup debris (including ordnance) from Sandia National Laboratories and other operators. A small hydrocarbon spill occurred during Voluntary Corrective Action (VCA) activities (VCA Spill Area) at an area associated with the North Disposal Trench Corrective Action Site (CAS). Remediation activities at this site were conducted in 1995. A corrective action investigation was conducted in September of 1996 following the Corrective Action Investigation Plan (CAIP); the detailed results of that investigation are presented in Appendix A. The Roller Coaster Lagoons and North Disposal Trench are located at the Tonopah Test Range (TTR), a part of the Nellis Air Force Range, which is approximately 225 kilometers (140 miles) northwest of Las Vegas, Nevada, by air.

This Corrective Action Plan (CAP) has been prepared for the Roller Coaster RADSAFE Area Corrective Action Unit 407 in accordance with the Federal Facility and Consent Order (Nevada Division of Environmental Protection [NDEP] et al., 1996). This CAP provides the methodology for implementing the approved Corrective Action Alternative as listed in the Corrective Action Decision Document (U.S. Department of Energy, Nevada Operations Office, 1999). The RCRSA was used during May and June of 1963 to decontaminate vehicles, equipment, and personnel from the Clean Slate tests. The Constituents of Concern (COCs) identified during the site characterization include plutonium, uranium, and americium. No other COCS were identified. The following closure actions will be implemented under this plan: (1) Remove and dispose of surface soils which are over three times background for the area. Soils identified for removal will be disposed of at an approved disposal facility. Excavated areas will be backfilled with clean borrow soil fi-om a nearby location. (2) An engineered cover will be constructed over the waste disposal pit area where subsurface COCS will remain. (3) Upon completion of the closure and approval of the Closure Report by NDEP, administrative controls, use restrictions, and site postings will be used to …

This Corrective Action Plan (CAP) provides the selected corrective action alternative and proposes the closure implementation methodology for the Roller Coaster Sewage Lagoons and North Disposal Trench Corrective Action Unit (CAU) No. 404. The site is located on the Tonopah Test Range. CAU 404 consists of two Corrective Action Sites (CAS): the Roller Coaster Lagoons (CAS No TA-03-001-TA-RC) and the North Disposal Trench (CAS No TA-21-001-TA-RC). A site map of the lagoons and trench is provided. The Roller Coaster Sewage Lagoons are comprised of two unlined lagoons that received liquid sanitary waste in 1963 from the Operation Roller Coaster Man Camp and debris from subsequent construction and range cleanup activities. The North Disposal Trench was excavated in approximately 1963 and received solid waste and debris from the man camp and subsequent construction and range cleanup activities. A small hydrocarbon spill occurred during the 1995 Voluntary Corrective Action (VCA) activities in an area associated with the North Disposal Trench CAS.

This Corrective Action Decision Document identifies and rationalizes the U.S. Department of Energy, Nevada Operations Office's selection of a recommended corrective action alternative (CAA) appropriate to facilitate the closure of Corrective Action Unit (CAU) 407, Roller Coaster RADSAFE Area (RCRSA), under the Federal Facility Agreement and Consent Order. Located on Tonopah Test Range (TTR), CAU 407 is located approximately 140 miles northwest of Las Vegas, Nevada, and five miles south of Area 3. The RCRSA was used during May and June of 1963 to decontaminate vehicles, equipment, and personnel from the Clean Slate tests. As a result of these operations, the surface and subsurface soils in the area have been impacted by plutonium and other contaminants of potential concern associated with decontamination activities. In June and July 1998, corrective action investigation activities were performed at CAU 407 (as outlined in the related Corrective Action Investigation Plan [CAIP]). The purpose of this investigation was to determine if any analytes were present at the site in concentrations above the preliminary action levels (PALs). The results indicated in the detection of plutonium above the PAL in samples taken from surface and subsurface soil within the exclusion zone, and uranium and americium detected above …

This Corrective Action Investigation Plan (CAIP) has been developed in accordance with the Federal Facility Agreement and Consent Order (FFACO) that was agreed to by the US Department of Energy, Nevada Operations Office (DOE/NV); the State of Nevada Division of Environmental Protection (NDEP); and the US Department of Defense (FFACO, 1996). The CAIP is a document that provides or references all of the specific information for investigation activities associated with Corrective Action Units (CAUs) or Corrective Action Sites (CASs). According to the FFACO (1996), CASs are sites potentially requiring corrective action(s) and may include solid waste management units or individual disposal or release sites. CAUs consist of one or more CASs grouped together based on geography, technical similarity, or agency responsibility for the purpose of determining corrective actions. This CAIP contains the environmental sample collection objectives and the criteria for conducting site investigation activities at CAU No. 407, the Roller Coaster RADSAFE Area (RCRSA) which is located on the Tonopah Test Range (TTR). The TTR, included in the Nellis Air Force Range Complex, is approximately 255 km (140 mi) northwest of Las Vegas, Nevada. CAU No. 407 is comprised of only one CAS (TA-23-001-TARC). The RCRSA was used during May …

This document constitutes an addendum to the September 1998, Closure Report for Corrective Action Unit 404: Roller Coaster Lagoons and Trench, 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 TA-03-001-TARC Roller Coaster Lagoons • CAS TA-21-001-TARC Roller Coaster N. Disposal Trench 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 …

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Post-closure monitoring requirements for the Roller Coaster RadSafe Area (Corrective Action Unit [CAU] 407) (Figure 1) are described in Closure Report for Corrective Action Unit 407, Roller Coaster RadSafe Area, Tonopah Test Range, Nevada, report number DOEN-694, October 2001. The Closure Report (CR) was submitted to the Nevada Division of Environmental Protection (NDEP) on April 24,2001. No issues with the post-closure monitoring plan, Section 5 .O, were raised. However, other concerns raised by stakeholders required that the CR be revised. Revision 1 of CR was issued in December of 2001 and was approved by NDEP on January 7,2002. Section 5.2 of the NDEP-approved CR calls for site inspections to be conducted within the first six months following completion of cover construction. Following the first six months, site inspection are to be conducted twice yearly for the next two years. This report provides the results of the six month post-construction site inspection. As stated in Section 5.2 of the CR, Post-closure site inspections at CAU 407 consists of the following: (1) Visual site inspections done twice a year to evaluate the condition of the cover and plant development. (2) Verification that the site is secure and condition of the fence and …

Post-closure monitoring requirements for the Roller Coaster Lagoons and Trench (Corrective Action Unit [CAU] 404) (Figure 1) are described in Closure Report for Corrective Action Unit 404. Roller Coaster Sewage Lagoons and North Disposal Trench. Tonopah Test Range. Nevada, report number DOE/NV--187, September 1998. The Closure Report (CR) was submitted to the Nevada Division of Environmental Protection (NDEP) on September 11, 1998. Permeability results of soils adjacent to the engineered cover and a request for closure of CAU 404 were transmitted to the NDEP on April 29, 1999. The CR (containing the Post-Closure Monitoring Plan) was approved by the NDEP on May 18, 1999. As stated in Section 5.0 of the NDEP-approved CRY post-closure monitoring at CAU 404 consists of the following: (1) Visual site inspections done twice a year to evaluate the condition of the cover and plant development. (2) Verification that the site is secure and condition of the fence and posted warning signs. (3) Notice of any subsidence, erosion, unauthorized excavation, etc., deficiencies that may compromise the integrity of the unit. (4) Remedy of any deficiencies within 90 days of discovery. (5) Preparation and submittal of an annual report. In addition to the above activities, vegetative monitoring …

This document constitutes an addendum to the September 1998, Closure Report for Corrective Action Unit 404: Roller Coaster Lagoons and Trench, 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 modification of the UR for CAS TA-03-001-TARC Roller Coaster Lagoons. This UR was established as part of Federal Facility Agreement and Consent Order (FFACO) corrective actions and was based on the presence of contaminants at concentrations greater than the action levels established at the time of the initial investigation …

This Closure Report provides the documentation for closure of the Roller Coaster Sewage Lagoons and North Disposal Trench Comective Action Unit (CAU) 404. CAU 404 consists of the Roller Coaster Sewage Lagoons (Corrective Action Site [CAS] TA-03-O01-TA-RC) and the North Disposal Trench (CAS TA-21-001-TA-RC). The site is located on the Tonopah Test Range, approximately 225 kilometers (km) (140 miles [mi]) northwest ofLas Vegas, Nevada. . The sewage lagoons received ~quid sanitary waste horn the Operation Roller Coaster Man Camp in 1963 and debris from subsequent range and construction cleanup activities. The debris and ordnance was subsequently removed and properly dispos~, however, pesticides were detected in soil samples born the bottom of the lagoons above the U,S. Environmental Protection Agency Region IX Prelimimuy Remediation Goals (EPA 1996). . The North Disposal Trench was excavated in 1963. Debris from the man camp and subsequent range and construction cleanup activities was placed in the trench. Investigation results indicated that no constituents of concern were detected in soil samples collected from the trench. Remedial alternative proposed in the Comctive Action Decision Document (CADD) fm the site was “Covering” (DOE, 1997a). The Nevada Division of”Enviromnental Protection (NDEP)-approved Correction Action Plan (CAP) proposed the “Covering” niethodology …

The fifth sentence of the first paragraph on Page 1 of the Post Closure Inspection Report for Corrective Action Unit 407: Roller Coaster RadSafe Area, Tonopah Test Range, Nevada erroneously states that Revision 1 of the CR was issued in December of 2001 and was approved by NDEP on January 7, 2002. The sentence should state that Revision 1 of the CR was issued in December of 2001 and was approved by NDEP on February 22, 2002.

Post-closure monitoring requirements for the Roller Coaster Sewage Lagoons and North Disposal Trench (Corrective Action Unit [CAW 404]) (Figure 1) are described in Closure Report for Corrective Action Unit 404, Roller Coaster Sewage Lagoons and North Disposal Trench, Tonopah Test Range, Nevada, report number DOE/NV--187. The Closure Report (CR) was submitted to the Nevada Division of Environmental Protection (NDEP) on September 11, 1998. Permeability results of soils adjacent to the engineered cover and a request for closure of CAU 404 were transmitted to the NDEP on April 29, 1999. The CR (containing the Post-Closure Monitoring Plan) was approved by the NDEP on May 18, 1999. Post-closure monitoring at CAU 404 consists of the following: (1) Site inspections done twice a year to evaluate the condition of the unit; (2) Verification that the site is secure; (3) Notice of any subsidence or deficiencies that may compromise the integrity of the unit; (4) Remedy of any deficiencies within 90 days of discovery; and (5) Preparation and submittal of an annual report. Site inspections were conducted on June 19, 2000, and November 21, 2000. The site inspections were conducted after completion of the revegetation activities (October 30, 1997) and NDEP approval of the …

An aerial radiological survey was conducted of major sections of the Tonopah Test Range (TTR) in central Nevada from August through October 1993. The survey consisted of aerial measurements of both natural and man-made gamma radiation emanating from the terrestrial surface. The initial purpose of the survey was to locate depleted uranium (detecting {sup 238}U) from projectiles which had impacted on the TTR. The examination of areas near Cactus Springs Ranch (located near the western boundary of the TTR) and an animal burial area near the Double Track site were secondary objectives. When more widespread than expected {sup 241}Am contamination was found around the Clean Slates sites, the survey was expanded to cover the area surrounding the Clean Slates and also the Double Track site. Results are reported as radiation isopleths superimposed on aerial photographs of the area.

Corrective Action Unit 485, Corrective Action Site TA-39-001-TAGR, the Cactus Spring Ranch Soil Contamination Area, is located approximately six miles southwest of the Area 3 Compound at the eastern mouth of Sleeping Column Canyon in the Cactus Range on the Tonopah Test Range. This site was used in conjunction with animal studies involving the biological effects of radionuclides (specifically plutonium) associated with Operation Roofer Coaster. The location had been used as a ranch by private citizens prior to government control of the area. According to historical records, Operation Roofer Coaster activities involved assessing the inhalation uptake of plutonium in animals from the nonnuclear detonation of nuclear weapons. Operation Roofer Coaster consisted of four nonnuclear destruction tests of a nuclear device. The four tests all took place during May and June 1963 and consisted of Double Tracks and Clean Slate 1, 11, and 111. Eighty-four dogs, 84 burros, and 136 sheep were used for the Double Tracks test, and ten sheep and ten dogs were used for Clean Slate 11. These animals were housed at Cactus Spring Ranch. Before detonation, all animals were placed in cages and transported to the field. After the shot, they were taken to the decontamination area …

The Clean Slate sites discussed in this report are situated in the central portion of the Tonopah Test Range (TTR), north of the Nevada Test Site (NTS) on the northwest portion of the Nellis Air Force Range (NAFR) which is approximately 390 kilometers (km) (240 miles [mi]) northwest of Las Vegas, Nevada. These sites were the locations for three of the four Operation Roller Coaster experiments. These experiments evaluated the dispersal of plutonium in the environment from the chemical explosion of a plutonium-bearing device. Although it was not a nuclear explosion, Operation Roller Coaster created some surface contamination which is now the subject of a corrective action strategy being implemented by the Nevada Environmental Restoration Project (NV ERP) for the U.S. Department of Energy (DOE). Corrective Action Investigation (CAI) activities will be conducted at three of the Operation Roller Coaster sites. These are Clean Slate 1 (CS-1), Clean Slate 2 (CS-2), and Clean Slate 3 (CS-3) sites, which are located on the TTR. The document that provides or references all of the specific information relative to the various investigative processes is called the Corrective Action Investigation Plan (CAIP). This CAIP has been prepared for the DOE Nevada Operations Office (DOE/NV) …

This report provides the results of the annual post-closure inspections conducted at the closed Corrective Action Unit (CAU) sites located on the Tonopah Test Range (TTR), Nevada. This report covers calendar year 2008 and includes inspection and repair activities completed at the following ten CAUs: #2; CAU 400: Bomblet Pit and Five Points Landfill (TTR) #2; CAU 404: Roller Coaster Lagoons and Trench (TTR) #2; CAU 407: Roller Coaster RadSafe Area (TTR) #2; CAU 423: Area 3 Underground Discharge Point, Building 0360 (TTR) #2; CAU 424: Area 3 Landfill Complexes (TTR) #2; CAU 426: Cactus Spring Waste Trenches (TTR) #2; CAU 427: Area 3 Septic Waste Systems 2, 6 (TTR) #2; CAU 453: Area 9 UXO Landfill (TTR) #2; CAU 484: Surface Debris, Waste Sites, and Burn Area (TTR) #2; CAU 487: Thunderwell Site (TTR)

During the period April to June 2008, at the behest of the U.S. Department of Energy (DOE) National Nuclear Security Administration, Nevada Site Office (NNSA/NSO); the Desert Research Institute (DRI) constructed and deployed two portable environmental monitoring stations at the Tonopah Test Range (TTR) as part of the Environmental Restoration Project Soils Sub-Project. The TTR is located within the boundaries of the Nevada Test and Training Range (NTTR) near the northern edge, and covers an area of approximately 725.20 km2 (179,200 acres). The primary objective of the monitoring stations is to evaluate whether and under what conditions there is wind transport of radiological contaminants from one of the three Soil Sub-Project Corrective Action Units (CAUs) associated with Operation Roller Coaster on TTR. Operation Roller Coaster was a series of tests, conducted in 1963, designed to examine the stability and dispersal of plutonium in storage and transportation accidents. These tests did not result in any nuclear explosive yield. However, the tests did result in the dispersal of plutonium and contamination of surface soils in the surrounding area.

During the period April to June 2008, at the behest of the Department of Energy (DOE), National Nuclear Security Administration, Nevada Site Office (NNSA/NSO); the Desert Research Institute (DRI) constructed and deployed two portable environmental monitoring stations at the Tonopah Test Range (TTR) as part of the Environmental Restoration Project Soils Activity. DRI has operated these stations since that time. A third station was deployed in the period May to September 2011. The TTR is located within the northwest corner of the Nevada Test and Training Range (NTTR), and covers an area of approximately 725.20 km2 (280 mi2). The primary objective of the monitoring stations is to evaluate whether and under what conditions there is wind transport of radiological contaminants from Soils Corrective Action Units (CAUs) associated with Operation Roller Coaster on TTR. Operation Roller Coaster was a series of tests, conducted in 1963, designed to examine the stability and dispersal of plutonium in storage and transportation accidents. These tests did not result in any nuclear explosive yield. However, the tests did result in the dispersal of plutonium and contamination of surface soils in the surrounding area.

The purpose of this paper is to derive the necessary parameters to be used to establish a defensible methodology to perform explosive dispersal modeling of respirable plutonium using Gaussian methods. A particular code, MACCS2, has been chosen for this modeling effort due to its application of sophisticated meteorological statistical sampling in accordance with the philosophy of Nuclear Regulatory Commission (NRC) Regulatory Guide 1.145, ``Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants``. A second advantage supporting the selection of the MACCS2 code for modeling purposes is that meteorological data sets are readily available at most Department of Energy (DOE) and NRC sites. This particular MACCS2 modeling effort focuses on the calculation of respirable doses and not ground deposition. Once the necessary parameters for the MACCS2 modeling are developed and presented, the model is benchmarked against empirical test data from the Double Tracks shot of project Roller Coaster (Shreve 1965) and applied to a hypothetical plutonium explosive dispersal scenario. Further modeling with the MACCS2 code is performed to determine a defensible method of treating the effects of building structure interaction on the respirable fraction distribution as a function of height. These results are related to the Clean Slate …