Our March  2006 report found that many large wastewater facilities have  discontinued, or are planning to discontinue using chlorine gas as a  disinfectant in favor of alternative disinfection methods such as sodium  hypochlorite delivered in bulk to the facility. The Clean Air Act requires wastewater facilities that use or store more  than 2,500 pounds of chlorine gas to submit to EPA a risk management  plan that lays out accident prevention and emergency response activities. Costs of Preparing Vulnerability Assessments and Risk Management Plans among Large Wastewater Facilities Vary Widely

Although accurate information on the costs of vulnerability assessments  and risk management plans is limited, available estimates suggest that  their costs vary considerably. A factor contributing to the cost differential  was whether they were contracted to third parties (such as engineering  consulting firms) or prepared in-house with existing staff. Despite higher  costs, some facilities preferred using contractors because their expertise  and independence lent credibility to their assessments, which may be  useful in obtaining support for security-related upgrades. Costs generally  did not relate to facility size, as measured by million of gallons of  wastewater treated per day. Vulnerability Assessment Costs Depend Primarily on Whether a Contractor Is Used

The reported cost of preparing vulnerability assessments at the 20 large  wastewater facilities where we interviewed officials ranged from $1,000 to  $175,000. Wastewater facility managers cited several reasons for using contractors  to complete vulnerability assessments. According to a wastewater security official, contractor expertise  and independence can give contractor findings and recommendations  greater credibility with utility governing boards that determine spending  priorities. Risk Management Plan Costs Also Influenced by Use of Contractors

Costs to prepare risk management plans ranged from less than $1,000 for  facilities that completed the plan in-house to over $31,000 for facilities that  used contractors. Costs of Converting to Alternative Disinfection Methods at Large Wastewater Facilities Depend on the Method Used and Other Factors

Large wastewater facilities that convert from chlorine gas disinfection to  alternative disinfection processes incur widely varying capital costs, which  generally depend on the alternative treatment chosen and facility size. Officials with  several of these facilities told us they considered ultraviolet disinfection,  but chose delivered sodium hypochlorite because of its lower capital  conversion costs. The remainder converted or plan to convert to sodium  hypochlorite generated on-site or ultraviolet light. The decision tool was designed to provide water  and wastewater utilities with the means to conduct assessments of  alternatives to chlorine gas disinfection. According to facility managers, the facility temporarily converted from  chlorine gas to delivered sodium hypochlorite in April 2002 at a cost of  $500,000, primarily for storage tanks, pumps, piping, and related  instrumentation. Reported costs included both actual and estimated costs. Reported costs were not adjusted for inflation. To identify the costs incurred by wastewater facilities in converting from  gaseous chlorine to an alternative disinfection process, we conducted  structured telephone interviews with a nonprobability sample of 26 of the  38 large facilities identified in the March report as having recently  converted or planning to convert from chlorine gas to an alternative  disinfection process.
Why GAO Did This Study

In 2006, GAO reported that many large wastewater facilities have responded to this risk by voluntarily conducting vulnerability assessments and converting from chlorine gas to other disinfection methods. The Clean Air Act requires all wastewater facilities that use threshold quantities of chlorine gas to prepare and implement risk management plans to prevent accidental releases and reduce the severity of any releases. In this study, GAO was asked to provide information on (1) the range of costs large wastewater treatment facilities incurred in preparing vulnerability assessments and risk management plans, and (2) the costs large wastewater treatment facilities incurred in converting from chlorine gas to alternative disinfection processes. To answer these questions, GAO conducted structured telephone interviews with a number of facilities surveyed for the 2006 report. The Environmental Protection Agency (EPA) agreed with the report and provided several technical changes and clarifications.

What GAO Found

Among the large wastewater facilities GAO examined, the costs reported to prepare vulnerability assessments ranged from $1,000 to $175,000, while costs to prepare risk management plans ranged from less than $1,000 to over $31,000. Whether the documents were prepared in-house or contracted to third parties such as engineering firms was a factor in cost differences. Despite higher costs, some facilities preferred to use contractors due to their expertise and independence. According to one wastewater security official, these attributes can give contractor findings and recommendations greater credibility with utility governing boards that determine spending priorities. One facility that used a contractor to complete a vulnerability assessment in 2002 did so because, at the time, vulnerability assessment software and training were not widely available. Since that time, EPA has increased funding for the development and dissemination of risk assessment software and related training. Overall, cost estimates for vulnerability assessments and risk management plans did not relate to facility size, as measured by millions of gallons of wastewater treated per day. For the large wastewater facilities GAO examined, reports of actual and projected capital costs to convert from chlorine gas to alternative disinfection methods range from about $650,000 to just over $13 million. Most facilities converted, or planned to convert, to delivered sodium hypochlorite (essentially a concentrated form of household bleach shipped in bulk to the facility). Managers of these facilities told GAO they considered other options, but chose delivered sodium hypochlorite because its capital conversion costs were lower than those associated with other alternatives, such as generating sodium hypochlorite on-site or using ultraviolet light. Overall, the primary factors associated with facilities' conversion costs included the type of alternative disinfection method chosen and the size of the facility. Other cost factors facility managers cited included (1) whether existing buildings and related infrastructure could be used in the conversion, (2) labor and building supply costs, which varied considerably among locations, (3) the cost of sodium hypochlorite relative to chlorine gas, and (4) the extent to which training, labor, and regulatory compliance costs were reduced for utilities that no longer had to rely on chlorine gas.