Central Marin Sanitation Agency - Executive Summary |
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CMSA EXECUTIVE SUMMARY Accidental Release Prevention and Emergency Response Policies Central Marin Sanitation Agency (CMSA) is committed to protecting the health and safety of CMSA employees and the public. The CMSA wastewater treatment plant is staffed on a 24-hour basis with State of California certified Wastewater Treatment Plant Operators. At least once every 8-hour shift, all plant processes are directly observed. In addition, a plant process control computer monitors readings from approximately 2,000 sensors in the plant and alarms alert staff immediately to potential problems. The computer and sensors are maintained by three instrument technicians. In 1996, CMSA ceased use of gaseous chlorine and sulfur dioxide, converting use to the liquid equivalents of these chemicals. The change was implemented to avoid the risk these toxic gases represented to the surrounding community. As discussed below, CMSA has a written Emergency Response Plan which specifies procedures in res ponse to various emergency events. CMSA staff are trained for their roles in the procedures. The CMSA Facility and Regulated Substances Handled CMSA is a public agency which operates the regional wastewater treatment plant. The plant provides secondary treatment for sewage, prior to discharge to San Francisco Bay. Sewage solids are anaerobically digested, dewatered, and then used as daily cover at a local municipal landfill. Discharge to the Bay and disposal of treated biosolids are regulated under an NPDES permit issued by the State of California. A flammable gas is produced as a by-product in two one million-gallon anaerobic digester vessels. The flammable component of the gas is methane, which is the only Risk Management Program (RMP) regulated substance at CMSA. The gas is stored in the digester vessels and used as fuel to heat the digestion process and to generate a portion of the electricity that CMSA uses for the treatment processes. CMSA stores and uses substantial qu antities of hazardous substances which are not regulated substances under the RMP. These are sodium hypochlorite, sodium bisulfite, hydrogen peroxide, ferric chloride, propane, gasoline, and diesel fuel. The Worst-case Release Scenario The worst-case release scenario for CMSA's analysis was a "vapor cloud explosion" of the maximum quantity of methane that can be contained in one of the digester vessels (3,200 pounds). Using EPA's RMP*Comp software, the "endpoint" was estimated to be 0.1 miles (530 feet). The endpoint is the maximum distance at which the explosion would be expected to shatter glass windows. There are no "public receptors", as defined by the RMP, within a 0.1 mile radius of either digester vessel. The General Accidental Release Prevention Program and Chemical-specific Prevention Steps CMSA digester gas is eligible for "Program 1" of the RMP, and therefore a formal "Risk Prevention Program" is not required for digester gas. CMSA has reviewed existing O&M procedur es related to digester gas and determined that they are sufficient to protect employees and the public. The Five-year accident History There have been no accidents or identified "near misses" involving digester gas at CMSA since the plant went on-line in 1984. The Emergency Response Program CMSA's Emergency Response Plan (ERP) provides information and guidelines needed to effectively coordinate and and implement response to fire, earthquake, hazardous material spills, and other emergencies. The ERP incorporates elements of California's Standardized Emergency Management System. Elements of the ERP have been coordinated with the local responder, the San Rafael Fire Department. Planned Changes to Improve Safety CMSA has recently completed a hazard review for its storage and use of propane as emergency fuel. During the Summer of 1999, CMSA intends to implement the equivalent of a Risk Prevention Program for propane, including revised O&M procedures and employee training. |