Mid-Set Cogeneration Company - Executive Summary
EXECUTIVE SUMMARY |
Accidental Release Prevention and Emergency Response Policies
Mid-Set Cogeneration Company stores and utilizes anhydrous ammonia in a
selective catalytic reduction (SCR) process at their facility near Fellows,
California. It is Mid-Set Cogeneration Company's policy to comply with all
applicable governmental regulations. Further, it is Mid-Set Cogeneration
Company's objective to be a responsible citizen of the community in all of its
Mid-Set Cogeneration Company emphasizes safe and environmentally sound
operating practices and procedures through their employee training programs. In
addition to job specific training, operators and maintenance personnel receive
training in fire prevention, fire control, accident prevention, safety, and first aid.
Additionally, an emergency action plan has been prepared for Mid-Set
Cogeneration Company and a chain of command to respond to emergencies has
Mid-Set Cogeneration Compa
ny has developed a detailed Compliance Audit
Checklist which is used to evaluate compliance with the Process Safety
Management (PSM) standard and 40 CFR Part 68 (RMP regulations). At least
every three years, Mid-Set Cogeneration Company audits these programs and
any findings of noncompliance are documented and responded to and the
deficiencies are corrected.
Description of the Stationary Source and Regulated Substances
Texaco Midway Sunset Cogeneration Company, a wholly-owned subsidiary of
Texaco Producing Inc., formed a general partnership with the Del-Mar Energy
Company, a wholly-owned subsidiary of Edison Mission Energy Company, for
the development of the cogeneration plant. The partnership, named Mid-Set
Cogeneration Company, owns and operates the facility. The plant began
commercial operation in April, 1989.
The Mid-Set Cogeneration Company facility is located in Section 36, T31S/R22E,
MDB&M in the sparsely populated Midway-Sunset oil field. Fellows is the clo
community to the plant.
Cogeneration, in the case of the Mid-Set project, is the simultaneous production
of thermal energy and electrical energy from the combustion of a single fuel
source. Combustion of the fuel takes place in a gas turbine that is physically
coupled to an electric generator. Waste heat from the gas turbine's exhaust
flows into a heat recovery steam generator (HRSG). The HRSG extracts the
heat from the exhaust gases and produces steam for thermally enhanced oil
recovery. Electricity is produced at the same time via the electric generator
coupled to the combustion turbine.
Anhydrous ammonia is used at the Mid-Set Cogeneration Company facility to
create a reducing atmosphere in the selective catalytic reduction (SCR) process.
This reducing atmosphere in the flue gas helps convert nitrogen oxides to
nitrogen and water as it passes through the catalytic reactor. The operation of
the SCR system substantially lowers the emissions of nitrogen oxide
s from the
Liquid ammonia is stored in a 15,000 gallon (water capacity) storage tank. The
maximum intended inventory of the anhydrous ammonia storage tank is based
on the American National Standard Institute's K61.1 safety requirements and the
Occupational Safety and Health Administration (OSHA) regulations published in
Section 1910.111 of 29 CFR (and Section 509 of Title 8, CCR). These standards
and regulations limit the maximum ammonia storage capacity of the tank to
approximately 69,960 pounds.
For purposes of the offsite consequence analyses, the RMP regulations define
the toxic endpoint for anhydrous ammonia as 0.14 mg/l (200 ppm). This
concentration has been established by the American Industrial Hygiene
Association as the Emergency Response Planning Guideline Level 2 (ERPG-2).
ERPG-2 is the maximum airborne concentration below which it is believed that
nearly all individuals could be exposed for up to one hour without experiencing or
rreversible or other serious health effects or symptoms which could
impair an individual's ability to take protective action.
Worst-Case Release Scenario and Alternative Release Scenario
Offsite consequence analyses are used as tools to assist in emergency response
planning. The RMP regulations require the owner or operator of a stationary
source to analyze the offsite impacts due to an accidental release of a regulated
substance. The offsite consequence analysis for a Program 3 process must
analyze the worst-case release scenario and an alternative release scenario.
Since Mid-Set Cogeneration Company's SCR system is considered a Program 3
process, both release scenarios were evaluated in the offsite consequence
The offsite consequence analysis must include an estimate of the residential
population within an area potentially affected by the accidental release scenarios.
This area is defined as a circle with a radius equivalent to the distance the
ld travel with concentrations at or above the endpoint. This circle
also defines the area in which potential environmental receptors must be
The worst case release is defined by the U.S. EPA as the total release of the
contents of the single largest vessel or pipe within 10 minutes. For liquefied
gases stored under pressure, the entire contents of the vessel or pipe are
assumed to be released as a vapor. A total vapor release is highly unlikely.
However, this standardized worst case scenario was developed for emergency
response agencies to use for planning purposes.
An alternative release scenario is a release that is more likely to occur than the
worst-case release scenario. For Mid-Set Cogeneration Company, the
alternative release scenario was selected based on the results of the Hazard and
Operability Study for the ammonia-based SCR process. The worst credible
release event with the highest discharge rate would potentially have the greatest
pact. A failure of the ammonia delivery hose was identified in the
Hazard and Operability Study as the worst credible release event having the
highest release rate, and therefore, was chosen as the alternative release
Mid-Set Cogeneration Company has analyzed the offsite consequences of the
worst-case and alternative release. For the worst-case release scenario, the
release of 69,960 lbs. of ammonia within 10 minutes, the plume would travel 3.1
miles at concentrations at or above the endpoint. Using 1990 Census data, the
population potentially affected within the worst-case release scenario circle is 58.
There were no sensitive or environmental receptors within the worst case release
In the alternative release scenario, a failure of the delivery hose was modeled as
a release of liquefied ammonia stored under pressure. For a release of 554
lb/min of anhydrous ammonia, the plume would travel 0.2 mile at concentrations
at or above the endp
oint. No residences are located within the 0.2 mile area
around the Mid-Set Cogeneration Company facility. As such, there would be no
population impacts from the alternative release scenario. There were also no
sensitive or environmental receptors within the alternative release scenario circle.
The modeling performed as part of this offsite consequence analysis does not
take into account the use of the remote operated shutoff valves that were
installed at the ammonia tank. These isolation valves take approximately 10 to
15 seconds to fully close and could greatly reduce the impact of a hose failure
General Accidental Release Prevention Program and Chemical-Specific
A PSM program, which meets the requirements of the general accidental release
prevention program, has been developed at Mid-Set Cogeneration Company to
address the anhydrous ammonia system. The PSM program includes the
following chemical-specific prevention steps:
cess safety information, including information pertaining to the
hazards of ammonia, the technology of the process, and the equipment in
the process has been compiled.
An initial Process Hazard Analysis (PHA) was performed and has been
updated and revalidated at least every five years.
Written operating procedures have been developed and implemented, and
are reviewed at least annually.
Safe work practices, such as lockout/tagout, confined space entry,
opening process equipment or piping, and control over entrance into the
facility have been developed and implemented.
Each employee involved in operating the ammonia system has received
initial training and refresher training at least every three years.
Written mechanical integrity procedures have been established and
A Management of Change (MOC) program has been developed and
implemented to address all proposed changes to the ammonia system.
Pre-startup safety reviews are performed when a modifi
cation is made to
the ammonia system that is significant enough to require a change in the
process safety information.
Audits are conducted at least every three years to evaluate compliance
with the RMP regulations.
Incident investigation procedures have been established.
A written plan of action regarding the implementation of employee
participation has been developed and implemented.
Hot work permits are issued for all hot work operations conducted on or
near the ammonia system.
A Contractor Safety Policy has been developed and implemented.
To ensure that the general accidental release prevention program and the
chemical-specific prevention steps are implemented, Mid-Set Cogeneration
Company has assigned overall responsibility for the RMP elements to the
Executive Director. The Executive Director has the overall responsibility for the
development, implementation, and integration of the RMP elements.
Five-Year Accident History
Mid-Set Cogeneration Company h
as not had any accidental releases from the
ammonia-based SCR system that have resulted in deaths, injuries, or significant
property damage on site, or known offsite deaths, injuries, evacuations,
sheltering in place, property damage, or environmental damage in the last five
Emergency Response Program
Mid-Set Cogeneration Company has established an emergency action plan and
a chain of command to respond to emergencies and to notify emergency
responders when there is a need for a response. However, an emergency
response program does not need to be developed for the facility since Mid-Set
Cogeneration Company employees will not respond to accidental releases of
ammonia, the facility is included in the community emergency response plan, and
appropriate mechanisms are in place to notify emergency responders.
Planned Changes To Improve Safety
The PHAs were most recently revalidated in March, 1996. Several changes to
inspection and offloading procedures were recommend
ed based on the PHA
revalidation. These changes were implemented by March, 1998.
Through the accidental release prevention program, Mid-Set Cogeneration
Company regularly evaluates the need for any changes to improve safety.
Currently Mid-Set Cogeneration Company does not have any additional changes
planned to improve safety.