Skip directly to: content | left navigation | search
  1. Home ›
  2. Chemical Weapons Elimination ›
  3. Reports and Publications ›
  4. VX Report Table of Contents ›
  5. Background

Background

    Report for Congress: Review of the U.S. Army Proposal for Off-Site Treatment and Disposal of Caustic VX Hydrolysate From the Newport Chemical Agent Disposal Facility

    The Chemical Stockpile

    The stockpile at Newport Chemical Depot, Newport, Indiana, consists of the chemical nerve agent O-ethyl S-[2- (diisopropylamino) ethyl] methyl phosphonothioate (VX) stored in bulk quantities (1,269 tons in 1,690 containers). VX contains phosphorus, oxygen, carbon, hydrogen, nitrogen and sulfur and is referred to as an organophosphate. VX is stabilized with several percent of either DIC or DCC or both to protect against decomposition. Forty-six percent of the stockpile at Newport consists of VX stabilized with DIC (potentially with small amounts of DCC stabilizer as a contaminant), 16% stabilized with DCC, and 38% stabilized with both DIC and DCC.

    The Newport Chemical Agent Disposal Facility

    NECDF was designed, and is to be operated, as a pilot-plant facility to destroy VX using caustic hydrolysis in a hot (194oF) aqueous solution of sodium hydroxide. This process forms CVXH, referred to in some reports as Newport caustic hydrolysate or NCH. The original plan was to further treat the resulting CVXH on-site by supercritical water oxidation (SCWO) to destroy organic components and then to ship the final SCWO effluent (brine) to a treatment, storage, and disposal facility. Because of mechanical problems encountered in the SCWO engineering scale test, conducted in Corpus Christi, Texas, in 2000, the Army initiated studies to directly ship NECDF CVXH off-site for disposal as an alternative to on-site SCWO treatment. The terrorist attacks of September 11, 2001, and continuing questions about the feasibility of implementing SCWO on-site within a reasonable timeframe supported the Army’s decision to adopt “Project Speedy Neutralization.” This approach involves shipping the CVXH to an existing treatment, storage, and disposal facility.

    Issues Related to Destroying VX

    Detailed testing of the caustic hydrolysis, as a process to destroy VX, began in the 1990s as part of the Army’s Alternative Technologies and Approaches program. Various “recipes” for the destruction of the VX chemical agent stored at NECDF using sodium hydroxide were tested. Initially, an agent loading of 33% by weight was chosen for the program.

    Confirmation of the completeness of destruction of VX depends on the analytical methods available to measure residual VX and EA 2192 (a degradation product) levels in the CVXH. During the past ten years, improvements in analytical techniques and instrumentation, coupled with increased personnel experience with these analyses, have lowered the detectable concentration of VX to the low parts per billion (ppb) levels and the detectable concentration of EA 2192 to the low tenths of parts per million (ppm) levels. However, the complexity and variability of the 33% VX loading caustic hydrolysate continued to complicate the VX analysis.

    In October 2003, the Project Manager for Alternative Technologies and Approaches began to investigate the use of reduced VX agent loading in the hydrolysis reaction as a means of resolving analytical problems related to characterization of 33% agent loading CVXH. The Army currently plans to begin operation destroying DIC-stabilized VX at the 8% agent loading level and then, through a carefully monitored ramping-up process, move to 16% agent loading of DIC-stabilized VX.

    The CVXH that will result from the caustic hydrolysis of VX at NECDF will consist of an organic phase and an aqueous phase. The organic phase exists both as an upper layer, floating on top of the aqueous phase, and as a suspension of droplets distributed throughout the aqueous phase (also known as an “emulsion”). The extent of organic layer forming above the aqueous layer depends on the amount of VX agent loaded into the batch to be treated. For instance, at 8% VX loading, only a thin sheen of organic layer reportedly is formed. However, at 33% VX agent loading, the organic layer comprises 3–5% of the mixture.

    The Army’s Proposal

    The Army is investigating shipping the untreated caustic VX hydrolysate to the DuPont Secure Environmental Treatment (SET) facility in Deepwater, New Jersey for final treatment and disposal. The stated SET process objectives are to treat 3,000 to 7,000 gallons per day of CVXH. Process objectives will be (1) control of wastewater and sludge odors, (2) control of SET wastewater treatment plant operations (e.g., effective dissolved organic carbon [DOC] removal, manageable foaming, pH control, solids management), and (3) meeting permit compliance limits for effluent biochemical oxygen demand (BOD5), whole effluent toxicity, total suspended solids, and ammonia.

    The pH adjustment of the CVXH is the first step of the pretreatment process prior to introducing the waste to the biologic treatment system. Peroxide treatment, to destroy odorous substances, follows CVXH pH adjustment. The final step in the treatment train utilizes a two-stage powder activated carbon treatment system® (PACT®); testing of the process was conducted under conditions emulating the actual plant flow rate and hydraulic retention time. The solids in the effluent will be settled, dewatered, and buried in a permitted hazardous waste landfill on site at DuPont. The remaining effluent, which includes other plant waste, then will be disposed in the Delaware River. A proposal to remove phosphonates from the effluent has been developed by DuPont, and this report was provided to CDC on March 2, 2005. This new process will be evaluated separately in a subsequent CDC report.

    Previous | Table of Contents | Next