Risk Assessment and Closure Certification for the Former Bioplant Equalization Basin Radford Army Ammunition Plant US.A rmy Corps of Engineers Norfolk District Norfolk, Virginia 22 July, 1998 Environmental Resources Management 9701 Metropolitan Court, Suite A Richmond, Virginia 23236 - TABLE OF CONTENTS 2.0 DESCRIPTION/SITE HISTORY 2.1 DESCRIPTION 2.1.1 Facility Description 2.1.2 Former Bioplant Equalization Basin Description 2.2 SITE HISTORY 2.2.1 Facility Background 2.2.2 Bioplant Equalization Basin Background 3.0 SUMMARY OF CLOSURE ACTIVITIES 6 3.1 CLOSURE PERFORMANCE STANDARDS AND APPROACH 6 3.2 CLOSURE SPECIFICATIONS 7 3.3 DISPOSAL OF WASTE GENERATED DURING CLOSURE ACTIVITIES 7 3.3.1 Waste Characterization Sampling 7 3.3.2 Disposal of Wastes 8 4.0 SUMMARY OF RESULTS FOR BACKGROUND AND BASIN SUBSOIL SAMPLING 9 4.1 DEVELOPMENT OF BACKGROUND LEVELS 9 4.2 BASIN SUBSOIL SAMPLING 9 4.3 DATA USABILITY AND QMQC SUMMARY 10 4.4 RESULTS OF STATISTICAL CALCULATIONS 1 1 5.0 RISK ASSESSMENT FOR RISK-BASED CLOSURE 12 5.1 GENERAL 5.2 SITE EVALUATION 5.3 EXPOSURE ASSESSMENT 5.3.1 Media and Exposure Pathways 12 5.3.2 Site Conceptual Exposure Model (SCEM) 12 -. 5.4 HAZARDOUS CONTAMINANTS OF CONCERN (HCOC) 14 5.5 TOXICITY ASSESSMENT 15 5.6 CONTAMINANT CONCENTRATION AT THE POINT OF EXPOSURE 15 5.7 RISK EVALUATION AND SUMMARY 16 6.0 CLOSURE ACTIVITIES COMPLIANCE CERTIFICATION 18 7.0 RISK BASED CLOSURE ASSESSMENT COMPLIANCE CERTIFICATION 19 LIST OF FIGURES 1 Facility Location Map 2 Former BioPlant Equalization Basin Location Map - 3 Background Sample Location Map 4 Basin Subsoil Sample Location Map 5 Site Conceptual Exposure Model (SCEM) LIST OF TABLES 1 Toxicity Values 2 Summa y of Potential Exposure Pathways 3 On-Site Resident Human Exposure to Soils Won-Carcinogen) 4 Soil Screening Level Partitioning Equation for Migration to Ground Water ATTACHMENT 1 CLOSURE PLANS AND AMENDMENT 2 LANDFILL DISPOSAL REPORT 3 CLOSURE CONSTRUCTION SOLICITATION AND SPECIFICATIONS 4 DAILY REPORTS 5 FINAL SITE INVESTIGATION TABLES - 6 DEQ LETZER 22 OCTOBER 1997 - 7 DEQ LETTER 10 MARCH 1998 .- 8 RISK TABLES On behalf of the United States Army and Alliant Techsystems, Inc. the United States Army Corp of Engineers (USACOE) and Environmental Resources Management (ERM) have prepared this risk assessment and closure report for the former Bioplant Equalization Basin (United States Environmental Protection Agency (USEPA) ID No. VA1210020730). The purpose of this report is to document that the closure activities were conducted in accordance with the Closure, Contingent Closure and Contingent Post-Closure Plans for Radford Army Ammunition Plant's Equalization Basin HWMU-10 & SWMU-10, dated 12 December 1995 and amended 9 March 1998 (Closure Plan) and that clean closure has been achieved for all Hazardous Constituents of Concern (HCOCs) except for fluoranthene A risk assessment for risk-based closure has been performed for fluoranthene in accordance with the approved Closure Plan and is included in this report. This report includes the following items: Facility description/ history; Former Bioplant Equalization Basin description/history; Summary of closure activities, including depth of excavation; Summary of results for background and basin subsoil sampling; Data usability and QA/QC summary; Results of statistical calculations; Risk assessment for fluoranthene; Disposal of waste generated during closure activities; Closure activities compliance certification; Risk-based closure assessment compliance certification, and; Attachments providing figures, tables, and other relevant information for this project. Each of the items listed above will be discussed in the remaining sections of the report. - ERM 1 USACOE 28705.W.01-0 7/22/98 DESCRIPTlON/SIT'E HISTORY Fncilitj Description The Bioplant Equalization Basin is situated on the Radford Army Ammunition Plant (RFAAP), which is operated by Alliant Techsystems, Inc. RFAAP is a government owned industrial complex located in southwestern Virginia. It encompasses approximately 4,104 acres and is located in Pulaski and Montgomery Counties. The facility is located approximately five miles northeast of the city of Radford, 10 miles west of Blacksburg, and 47 miles southwest of Roanoke (see Figure 1). The New River divides the RFAAP into two portions commonly known as the "Horseshoe Area" and the "Main Manufacturing Area." The "Horseshoe Area" lies mainly to the north and west in Pulaski County. The "Main Manufacturing Area" lies in Montgomery County to the south and east. The former Bioplant Equalization Basin was located in the north central portion of the "Main Manufacturing Area" (see Figure 2). F mBiop lant Equalization Basin Description The Bioplant Equalization Basin was a soil/cement-lined, rectangular impoundment with dimensions of 255 x 160 x 10.5 feet deep. The basin met design capacity of 1,350,000 gallons with 7.5 feet of water. The basin received wastewater of widely varying characteristics, including non- acidic wastewater from propellant manufacturing (on both a batch and continuous basis); pre-treated wastewater from nitroglycerine manufacturing and alcohol rectification; and wastes from recovery of ethyl ether. STTE HISTORY Facility Background RFAAP was operated under contract by Hercules Aerospace Corporation from 1941 to 1995. Alliant purchased the operations of Hercules RFAAP in 1995 and is the current facility contractor. This facility, whch contains over 1,696 buildings and occupies close to 3.65 million square feet, is the top manufacturer of solid propellants in the United States. The major 2 - ERM USACOE- 28705.00.01 7/28/98 products manufactured at this facility are solvent and solventless propellants that include single base (nitrocellulose), double base (nitrocellulose and nitroglycerin), and triple base (nitrocellulose, nitroglycerin, and nitroguanidine) propellants; cast propellants; and high energy propellants. These propellants are ultimately used in small arms, anti-tank weapons, anti-aircraft weapons, rockets, torpedoes, missile systems, igniters, and other numerous ordnance-related items. Bioplant Equalization Basin Background In 1979, two incinerators were constructed and the incineration of waste and off-specification explosives and propellants began. These incineration operations became regulated subsequent to the promulgation of the federal hazardous waste regulations under the Resource Conservation and Recovery Act (RCRA) in 1980. Beginning in 1980, the Bioplant Equalization Basin operated as the first of nine components that make up a biological wastewater treatment system at RFAAP. The biological treatment system was built in 1978/1979 and became operational in 1980. Prior to 1980, these wastewaters were discharged directly to the New River. Operating procedures were such that influent flows were cut off if the Bioplant Equalization Basin capacity was reached. The facility did not submit its Part B permit application prior to 8 November 1985 and was, therefore, notified that a closure plan was required under RCRA and the Virginia Hazardous Waste Management Regulations (VHWMR). On 16 March, 1990, RFAAP was notified that a closure plan for the Bioplant Equalization Basin was required; however, the Virginia Department of Environmental Quality (VADEQ) notified RFAAP that it would allow the Bioplant Equalization Basin to remain in operation as a "newly regulated unit" until 15 March, 1994. A closure plan was submitted as part of the Part B Permit Application. VADEQ commented on the Part B application on February 2,1991, and requested additional information. On 28 June 1991, RFAAP submitted the requested information. On 2 December 1991, RFAAP re-submitted a RCRA Part B application for the biological waste water treatment plant. On 1J une 1992, RFAAP submitted a plan for sampling the equalization sludges in accordance with RFAAPs agreement with EPA. On 21 July 1992, VADEQ approved the groundwater monitoring plan for the Bioplant Equalization Basin via Section E of the Part B application. On 3 November 1992, a Final Draft Verification Investigation report was received by VADEQ which contained detailed studies of all SWMUs, including the sampled sludges 3 - ERM USACOE- 28705.00.01 7/28/98 from the Bioplant Equalization Basin. On 19 October 1993, EPA's Delisting Section recommended denial of petition number 0834 for the sludges from the Bioplant Equalization Basin, and thus they remain a listed hazardous waste. RFAAP contacted VADEQ's Roanoke Regional Office by phone on 11 March 1994, and notified VADEQ that RFAAP was not prepared to cease operation of the Bioplant Equalization Basin on 15 March 1994, as stipulated in the VADEQ's 16 March 1990 letter. On 21 March 1994, VADEQ notified RFAAP that the requirements for immediate closure had arisen from Section 30050)(6) of RCRA, that the unit was required to close, and should have ceased operations on 15 March 1994. The provision requires that "newly regulated surface impoundment units" meet the requirements of Section 3004(o)(l)(a)o f RCRA (minimum technology requirements) or cease receipt of hazardous wastes four years from the date the unit becomes subject to the regulations. The VADEQ notified RFAAP that continued operation constituted noncompliance. RFAAP was also notified that the Bioplant Equalization Basin was subject to the Toxicity Characteristics Final Rule (Federal register Vo1.55, No.61, 29 March 1990), by VADEQ on 21 March 1994. Since the Bioplant Equalization Basin received toxicity characteristic waste (D030, 2.4- Dinitrotoluene), RFAAP was notified that the unit must be retro-fitted or have the unit operation cease by 29 March 1994. The VADEQ notified EPA of the pending date for the Toxicity Characteristics Final Rule for appropriate action. RFAAP responded to the VADEQ notification correspondence the day before the final closure deadline and informed VADEQ that RFAAP would continue equalization operation while working toward a consent order with VADEQ's Office of Enforcement. On the same day, 29 March 1994, EPA notified RFAAP to immediately cease operation of the Bioplant Equalization Basin. Emergency measures were taken by utilizing several abandoned steel tanks to serve as temporary Bioplant Equalization Basins to store wastewater prior to the transmission of the wastewater to the holding chamber of the Bioplant Equalization Basin pump station (located at the southwest corner of the Basin). The pump station delivers the wastewater to the biological treatment plant. The pump station was sealed off from the Bioplant Equalization Basin by the installation of a steel plate and gasket at the bar screen at the inlet to the pump station. The Bioplant Equalization Basin was "closed " after the unit's pump station was taken off line, and RFAAP could route all wastewater directly to the newly constructed (2) concrete equalization tanks each holding 3.82 million gallons. All hazardous waste sludges and liquids that were ERM 4 USACOE- 28705.00.01 - 7/28/98 remaining in the Bioplant Equalization Basin have been removed. Copies of the Hazardous Waste Manifests are on file with the VADEQ. 5 - E RM USACOE- 2870J.Oa.01 7/28/98 SUMMARY OF CLOSURE ACTNITIES Closure of the Bioplant Equalization Basin included earthwork, demolition, removal and decontamination/disposal of piping, pumps, soil/cement liner and concrete, subsoil testing to verify soil requiring removal, removal and disposal of contaminated soil and backfill and grading. The closure activities were completed prior to the conduct of the risk assessment for risk-based closure (described in Section 5.0 of this closure report). The closure activities were conducted in accordance with the Closure Plan and are certified in Section 6.0 of this report. The disposal of waste generated during closure activities are discussed later in this section. CLOSURE PERFORMANCE STANDARDS AND APPROACH The closure performance standards and the general closure approach is detailed in Section 3.0 of the Closure Plan. The Closure Plan and the Closure Plan Amendment are included as an attachment to this report (see Attachment I). The following is a brief summary of the closure performance standards and the general closure approach. The closure plan was prepared and followed to meet the requirements of VHWMR Sections 9.6.L, 10.6 and 10.10.1. The basin was closed in a manner that: Minimized the need for further maintenance, and; Controls, minimizes or eliminates, to the extent necessary to prevent threats to human health and the environment, post-closure escape of hazardous waste, hazardous waste constituents, leachate, contaminated rainfall, or waste decomposition products to the ground or surface waters or the atmosphere. The general closure approach included the removal of water and sludges from the Bioplant Equalization Basin prior to closure. Pumps and ancillary piping were also removed for off-site disposal or decontaminated in accordance with Section 3.7 of the approved Closure Plan. The perimeter flood control wall was removed and disposed. Soil sampling and testing was conducted to determine that no additional soils were required to be removed. The excavation was then back-filled with clean soils, graded to promote positive drainage, and re-vegetated. Equipment was decontaminated in an approved manner. The contaminated materials, excluding the water and sludges previously ERM 6 USACOE 287m.oo.m - 7/28/95