SCA Cogeneration Plant II - Executive Summary
Sacramento Cogeneration Authority has elected to file a Risk Management Plan with the EPA for the SCA Cogeneration Plant II following the Federal Accidental Release Prevention (ARP) Program regulations, even though the quantity of Regulated Substances does not exceed Federal thresholds. The Risk Management Program instituted by Sacramento Cogeneration Authority identifies the equipment, procedures, maintenance, inspection, and training associated with Regulated Substances (RS's) handled at this facility in excess of California 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 mitigat |
ion measures and auditing of program elements. This Risk Management Plan (RMP) is being filed as requested by Sacramento County Environmental Management Department, Hazardous Materials Division, in accordance with California 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 held at this facility in excess of California threshold quantities.
STATIONARY SOURCE AND REGULATED SUBSTANCES HANDLED
Carson Energy Group is the contract operator of a cogeneration facility, SCA Cogeneration Plant II, located at 5000 - 83rd St., Sacramento, CA in Sacramento County, owned by Sacramento Cogeneration Authority. Aqueous ammonia (25% solution) is used for selective catalytic reduction of nitrogen oxides in the gas turbine exhaust. This RS is handled in quantities greater than its California threshold quantity. The facility is located in an industrial area in south S
acramento with few residences nearby. There are 16 full-time employees at this site. Aqueous ammonia (25% solution) is received in bulk by truck into an enclosed steel storage tank. The aqueous ammonia solution is pumped from the storage tank at a metered rate into the flowing turbine exhaust gas at the location of a catalyst within the exhaust duct, and reacts chemically with oxides of nitrogen to form nitrogen gas, thus reducing air pollutant emissions in the stack gas.
ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES
It is the policy of Sacramento Cogeneration Authority that the receipt, storage and handling of aqueous ammonia (25% solution) at the SCA Cogeneration Plant II be done in a manner which meets regulatory requirements and minimizes the probability and severity of accidental releases of aqueous ammonia (25% solution) 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 Cogeneration Authority has gathered safety information on aqueous ammonia (25% solution) and on the process, equipment and procedures involving aqueous ammonia (25% solution); 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 releases; and established a written emergency response program coordinated with emergency response agencies.
WORST CASE RELEASE SCENARIO
A single "worst case" release scenario is required to be considered for each stationary source, resulting in the maximum distance to an endpoint for all toxic RS's contained on site above the threshold quantity.
The worst case release scenario for toxic chemicals is defined in the California ARP regulations as the release of the contents of the largest single container of RS (in this case aqueous ammonia (25% soluti
on)) over a period of 10 minutes. The scenario considered the release of the contents of the largest container of aqueous ammonia (25% solution) on site, in this case the contents of the 10,000-gallon storage tank containing 18,750 lb. of ammonia. The toxic endpoint reached a location outside the plant property line.
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.
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 case" considered for this facility is the release of aqueous ammonia (25% solution) from process piping due to component failure, with the rel
ease secured by operators after 5 minutes. The toxic endpoint reached a location outside the plant property line.
Administrative controls in effect at Carson Energy Group which were considered to mitigate the severity of the Worst Case and Alternative Case release scenarios include Carson Energy Group's written policies and procedures for training of operators and maintenance personnel, written procedures for control of the inventory of aqueous ammonia (25% solution) at the facility, and policies regarding quality level of replacement materials and components for the aqueous ammonia (25% solution) system.
Passive mitigation in the form of a concrete secondary containment structure surrounding the storage tank was considered to limit the severity of the Worst Case scenario. The same passive mitigation measure was considered to limit the severity of the Alternative Case scenario. Active mitigation was considered for the Alternative Case,
in the form of response of trained operators in a timely manner to close the valve on the suction side of the transfer pump.
GENERAL ACCIDENTAL RELEASE PREVENTION PROGRAMS
General accidental release prevention programs instituted by Sacramento Cogeneration Authority and Carson Energy Group are categorized as administrative (management) programs; procedures, training, and engineering controls; and emergency response programs.
Carson Energy Group maintains policies and procedures conforming to recognized industry standards covering the operation and maintenance of its selective catalytic reduction process, including quality standards for materials of construction, and training programs for personnel operating and maintaining equipment. This constitutes the general accidental release prevention program for Carson Energy Group's operations at the SCA Cogeneration Plant II.
CHEMICAL-SPECIFIC RELEASE PREVENTION STEPS
Release prevention steps specific to aqueous ammonia (25% solution)
have been identified and implemented. These include, among other things, changing the set pressure of a relief valve on the storage tank to a higher pressure.
FIVE YEAR ACCIDENT HISTORY
There have been no accidents involving aqueous ammonia (25% solution) at this facility within the past five years.
EMERGENCY RESPONSE PROGRAM
Carson Energy Group's Emergency Response Program applicable to aqueous ammonia (25% solution) 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. It consists of notification of the public agency assigned responsibility for First Response to hazardous materials release emergencies.
PLANNED CHANGES TO IMPROVE SAFETY
All of the improvements and mitigation measures identified in the process hazard analysis which Sacramento Cogeneration Authority committed to accomplish have been completed. 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.