Sacramento Regional Wastewater Treatment Plant - Executive Summary |
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Sacramento Regional Wastewater Treatment Plant has instituted a Risk Management Program for their wastewater treatment facility, Sacramento Regional Wastewater Treatment Plant, as required by Federal Accidental Release Prevention (ARP) Program regulations at 40 CFR Part 68. The Risk Management Program identifies the equipment, procedures, maintenance, inspection, and training associated with Regulated Substances (RS's) handled at this facility in excess of Federal threshold quantities; describes the structured assessment of hazards which was conducted to assess possible effects on employees and offsite public and environmental receptors; provides the results of an offsite consequences analysis; defines a prevention program, emergency response program, and mitigation measures to reduce the probability and magnitude of accidental releases of RS's; and establishes a schedule and responsibilities for implementation of mitigation measures and auditing of program elements. This Risk Manage ment Plan (RMP) is being filed as required by ARP regulations in order to report the elements of the current Risk Management Program and to describe further measures planned to mitigate or prevent accidental releases of RS's. STATIONARY SOURCE AND REGULATED SUBSTANCES HANDLED Sacramento Regional Wastewater Treatment Plant treats wastewater collected from the City and County of Sacramento, and from the City of Folsom. It is located at 8521 Laguna Station Rd., Elk Grove, CA on 900 acres of a 3,400-acre site between Interstate 5 and Franklin Blvd., south of Meadowview Rd. The remaining 2,500 acres serve as a buffer between the Plant and nearby residential areas. There are 300 full-time employees at this site. The Plant treats 165 million gallons of wastewater per day (mgd) on average. The Plant uses chlorine for disinfection and sulfur dioxide for dechlorination and maintains quantities of these RS's greater than the Federal threshold quantities. Additionally, methane gas, an RS, is held in the digester gas system in quantities greater than the Federal threshold quantity. The chlorine and sulfur dioxide systems generally consist of railcar receiving, liquid chemical withdrawal from railcars, bulk sulfur dioxide liquid storage, liquid chemical vaporization, and gaseous chemical metering and dissolving into water for ultimate application to various points in the wastewater treatment process. Solids removed in the wastewater treatment process are introduced into the 11 anaerobic digesters at the Plant. Gas consisting of approximately two-thirds methane is formed in the digesters as bacterial digestion proceeds. The digester gas is scrubbed to remove hydrogen sulfide and other contaminants, stored in low pressure and high pressure gas holders, and piped to a cogeneration plant where it is used to generate electricity and steam. Whatever quantity of digester gas which cannot be used by the cogeneration plant is flared. The entire inventory of digester gas in the plant must be considered for the purpose of comparisin with Federal threshold quantity. ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES It is the policy of Sacramento Regional Wastewater Treatment Plant that the receipt, storage and handling of chlorine and sulfur dioxide, and the handling of methane, at its facility be done in a manner which meets regulatory requirements and minimizes the probability and severity of accidental releases of these RS's to the atmosphere, in order to protect the health and safety of its workers, the public, and the environment. In order to accomplish this goal, Sacramento Regional Wastewater Treatment Plant has gathered safety information on chlorine, sulfur dioxide, and methane, and on the process, equipment and procedures involving these RS's; performed a structured assessment of hazards of the process and external events which might affect the process; performed an offsite consequences analysis of defined release scenarios; established a written program for prevention and mitigation of accidental releases; and established a written emergency response program coordinated with emergency response agencies. WORST CASE RELEASE SCENARIO A single "worst case" release scenario for toxic materials is required to be considered for each site, resulting in the maximum distance to an endpoint for all toxic RSs contained on site. The worst case release scenario is defined in the ARP regulations as the release of the contents of the largest single container of RS (in this case sulfur dioxide) over a period of 10 minutes. The scenario considered the release of the contents of the largest container of sulfur dioxide on site, in this case a railcar containing 180,000 lb. (90 tons). This release scenario is not physically possible, due to the characteristics of sulfur dioxide. Additionally, a "worst case" release scenario is required for be considered for flammable materials. The worst case scenario considered is the e xplosion of the largest single container on site containing digester gas, a full LSG holder tank, containing 80,000 cu.ft. (3,200 lbs.) of methane. ALTERNATIVE CASE RELEASE SCENARIO An "alternative case" release scenario is required to be considered for each toxic RS handled in quantities greater than the threshold quantity at the site, and an additional "alternative case" release scenario is to be considered for all flammable RS's handled in quantities greater than the threshold quantity at the site. The "alternative case" scenario is described in the ARP regulations as a likely release resulting in offsite effects, considering administrative controls and mitigation measures in place, and is to be determined by the facility operators as part of the Process Hazard Analysis required to be performed during RMP development. The "alternative cases" for toxic substances considered for this facility are the release of sulfur dioxide from a broken pressure gauge connection on a liquid lin e at the rate of 24.2 pounds per minute for 10 minutes, due to mechanical failure, and the release of chlorine from a broken pressure gauge connection on a liquid line at the rate of 8.0 pounds per minute for 10 minutes, due to mechanical failure is included. The "alternative case" for flammable substances considered for this facility is the release of digester gas from an LSG holder tank's 18" relief valve, venting at 1800 scfm, or 72 pounds per minute, for 10 minutes. ADMINISTRATIVE CONTROLS Administrative controls in effect at Sacramento Regional Wastewater Treatment Plant which were considered to mitigate the severity of the Worst Case and Alternative Case release scenarios include Sacramento Regional Wastewater Treatment Plant's written policies and procedures for training of operators and maintenance personnel, written procedures for control of the inventory of chlorine at the facility, and policies regarding quality level of replacement materials and components for the chlorin e system. MITIGATION MEASURES No mitigation measures were considered to limit the severity of the Worst Case scenarios. Passive mitigation measures were considered to limit the severity of the Alternative Case scenarios for toxic RS's in the form of the use of custom-fabricated liquid chemical pressure gauge connection nipples (1/8" I.D. for sulfur dioxide and 1/16" I.D. for chlorine). No mitigation measures were considered to limit the severity of the Alternative Case scenario for flammable RS's. Active mitigation was considered for the Alternative Cases for toxics, in the form of response of trained employees to a leak alarm in accordance with written procedures to shut remotely-operated line isolation valves in a timely manner. GENERAL ACCIDENTAL RELEASE PREVENTION PROGRAMS General accidental release prevention programs instituted by Sacramento Regional Wastewater Treatment Plant are categorized as administrative (management) programs; procedures, training, and engineering co ntrols; and emergency response programs. Sacramento Regional Wastewater Treatment Plant has instituted a Process Safety Management (PSM) Program meeting OSHA requirements at 29 CFR 1910.119 covering its disinfection, dechlorination, and methane gas production process. This constitutes the general accidental release prevention program for Sacramento Regional Wastewater Treatment Plant's operations. The program and document management procedures included in the PSM Program will be used as the management system for the Risk Management Program. CHEMICAL-SPECIFIC RELEASE PREVENTION STEPS Release prevention steps specific to chlorine and sulfur dioxide have been identified and implemented. These include, among other things, fabrication of custom gauge connection nipples for liquid chlorine and sulfur dioxide pressure gauges to limit the rate of liquid release should the gauge fail, and creation of numerous facility-specific operation procedures for the chlorine, sulfur dioxide, and dig ester gas systems with check boxes for completion of critical steps. FIVE YEAR ACCIDENT HISTORY There have been no accidents involving chlorine, sulfur dioxide, or digester gas at this facility within the past five years resulting in injuries or offsite consequences. EMERGENCY RESPONSE PROGRAM Sacramento Regional Wastewater Treatment Plant's Emergency Response Program applicable to chlorine, sulfur dioxide, and digester gas has been coordinated with Sacramento County Environmental Management Department, Hazardous Materials Division, the local agency responsible for hazardous materials inventory reporting and release response coordination. Sacramento Regional Wastewater Treatment Plant maintains First Responder capability with respect to hazardous materials releases. PLANNED CHANGES TO IMPROVE SAFETY All of the improvements and mitigation measures identified in the process hazard analysis which Sacramento Regional Wastewater Treatment Plant committed to accomplish have been compl eted or are in progress. Any other measures identified by employees during workplace hazard surveys, or as a result of audit activities, will be thoroughly reviewed and considered for implementation. |