University of California, San Francisco - Executive Summary
This section is specified in 40CFR68.155 and 19CCR2745.3 |
The University of California, San Francisco (UCSF) is replacing the existing Parnassus Heights Campus power and steam generation facility with a new Central Utilities Plant (CUP). The plant will provide electricity, steam and chilled water to meet current and future campus demand. The CUP will contain two gas turbine generators rated at 4.75 megawatts (MW) each, two heat recovery steam generators (HRSG's) and associated duct burners, one steam turbine generator (rated at 3.75 MW), two auxiliary boilers (each rated at 90,000 lb/hr of steam), and three diesel generators (each rated at 2 MW) for emergency electric power.
In order to meet the nitrogen oxides (NOx) emissions limit required by the Bay Area Air Quality Management District's (BAAQMD) Regulation 9, Rule 7, the two HRSG's and two gas turbines will be equipped with a selective catalytic reduction (SCR) system. The SCR system will use ammonia, in the presence of a catalyst
, to convert NOx contained in the gas turbine exhaust into nitrogen gas and water vapor. The ammonia gas will be obtained from a 29.5% solution of aqueous ammonia (aqua ammonia) which will be stored in an 8,000-gallon steel underground storage tank located on UCSF property at the corner of Parnassus Avenue and Medical Center Way. Aqua ammonia was chosen over anhydrous ammonia because it is significantly less hazardous. The aqua ammonia system will consist of unloading, storage, transfer, and injection systems.
The aqua ammonia unloading system will receive and transfer the contents of the delivery tanker truck from the unloading station to the underground double wall steel storage tank in the containment structure. This tank is anchored to a concrete slab in a pit filled with pea gravel and covered by the containment building floor slab. All lighting and equipment in the building are designed as "explosion proof". Smoking and other ignition sources in the vicinity of the containm
ent structure will be strictly forbidden. Outside the containment structure, bollards (steel cylindrical posts filled with concrete) will be placed at strategic locations to prevent traffic from impacting the containment structure.
Deliveries to the containment structure will be prescheduled between UCSF and the deliverer. The route of the delivery truck to Parnassus Avenue will be discussed with interested UCSF neighbors and representatives from the San Francisco Fire Department (SFFD), Local Emergency Planning Committees (LEPC's), and San Francisco Department of Public Health Hazardous Materials Unified Program Agency (SFDPH/HMUPA). The delivery truck will be met by a UCSF plant operator at the entrance of the containment structure. Prior to delivery, appropriate containment structure systems will be activated such as the ventilation system. The UCSF plant operator will remain at the containment structure until the unloading process is completed. After the delivery truck re
aches Parnassus Avenue, it will proceed easterly crossing Medical Center Way and entering the west end of the containment structure.
Once the truck is inside the containment structure, the doors will be lowered, hose connections will be made, and the driver and UCSF operator will enter the vestibule/observation room. From the vestibule/observation room, the driver and UCSF operator will initiate the unloading process (transfer by gravity) and monitor its progress until completion. The filled storage tank will contain an approximate thirty-day supply of aqua ammonia; however, regular deliveries to refill the tank are planned at 15-day intervals by a 3200-gallon tanker truck. The 30-day supply provides for potential deferrals of deliveries in inclement weather without depleting the tank supply. Upon completion of delivery, the hose will be uncoupled. It should be noted that the hose coupling is a dry lock coupling type similar to those used in gasoline transfer hoses. The east end
door is then raised and the delivery truck will drive out and proceed easterly along Parnassus Avenue. This delivery configuration ("drive through") will maintain traffic flow along Parnassus Avenue and Medical Center Way. No backing maneuvers are required by the driver nor is the delivery truck required to drive on Medical Center Way. The "drive-through" procedure minimizes impact on both vehicle and pedestrian traffic.
The aqua ammonia transfer system will convey aqua ammonia as needed from the storage tank to the CUP facility via a 700 foot, 3/4 inch, double-walled underground carbon steel pipe. The aqua ammonia transfer system consists of a pump and associated piping. The pump is self contained and located inside the containment structure.
The injection system which is located at the CUP is computer controlled to minimize NOx emissions. The system receives, vaporizes, and regulates the rate of ammonia fed into the SCR catalyst bed. Ammonia emissions from the plant are limite
d by BAAQMD permit to less than 10ppm.
The administering agency, SFDPH/HMUPA, has required UCSF to prepare and submit a Risk Management Plan (RMP) in accordance with the federal, state and local laws. The federal law is provided under the provisions of the Clean Air Act (CAA) Section 112(r); state law is specified in the California Health and Safety Code (Article 2, Chapter 6.95, Division 20) and in the California Code of Regulations (19CCR2735-2785.1); and the local law is found in the San Francisco Municipal Health Code (Article 21, Chapter 5).
The RMP has been reviewed and evaluated by design, construction, operations, and health and safety personnel. The prevention program has resulted in the identification of potential problems and allowed for modifications to upgrade the facility. UCSF is committed to maintaining the highest standards in the design, construction, operation, and maintenance of the new facility.
The following information is presented as required in 40CFR
68.155 and 19CCR2745.3 and their subparts.
(a) UCSF policy requires adherence to applicable federal, state, and local laws, rules, and regulations. The safe handling of ammonia is enhanced by designing the facilities to include multiple safety devices and engineering controls, by implementing effective training programs for personnel, and by following standard operating procedures. Both passive and active mitigation measures have been incorporated into the facility design.
These measures are complemented by the presence of a robust emergency response program. In particular, UCSF maintains an Emergency Response Team (ERT) that is knowledgeable and trained to handle hazardous material spills such as might occur with the aqua ammonia system. The ERT can resolve accidental releases of a hazardous material by controlling and mitigating the release to allow a safe return to normal operations. This RMP identifies the system/process controls to further clarify the extent to which UC
SF has identified and implemented the necessary measures to ensure the safe and efficient operation of the facility. The UCSF accidental release prevention program has been established to provide to the maximum extent possible a risk free environment for employees, patients, visitors and neighbors.
(b) The stationary source consists of an aqua ammonia unloading facility and underground storage tank located on the corner of Parnassus Avenue and Medical Center Way on the Parnassus Heights campus. A transfer pump and piping delivers the aqua ammonia to the selective catalytic reduction unit located on the first floor of the Central Utilities Plant. The regulated substance is 29.5% aqua ammonia, an ammonia solution consisting of just over 70% water. The regulated substance will have a maximum inventory of 8,000 gallons at any given time. The maximum delivery quantity will be approximately 3,200 gallons.
(c) Worst Case Release Scenario: The worst case release offsite Consequence Ana
lysis (OSCA) scenario for the purposes of the RMP involves a spill of the entire delivery quantity during the unloading process. Many parameters needed to describe the spill are required by regulations. For example, regulations require that the accidental spill include the entire volume of ammonia contained in the delivery tanker at the time of filling the underground storage tank and that the contents be completely spilled within 10 minutes.
The spill is mitigated passively with controls such as an emergency containment basin (spill chamber). The spill chamber is sized to be four times larger than the delivered quantity of ammonia and contains a floating polypropylene ball blanket to further reduce by 91% the evaporation area. The spill chamber is located below the custom designed containment structure (building enclosure) to limit offsite ammonia vapor release. The containment structure will provide an additional 90% reduction of ammonia vapor to the outside atmosphere. Other mi
tigation measures are discussed later in this RMP.
This aggressive passive mitigation approach results in no offsite impacts from the worst case release scenario. Specifically, the 200 ppm ammonia concentration level (the regulatory endpoint) occurs within a distance of 10 feet as measured from the center of the spill chamber, a point which is located on UCSF property.
Alternative Release Scenario: The alternative release scenario involves a seal leak at the injection pump in the CUP. Since 99% of the aqua ammonia system is underground, the CUP ammonia injection unit is the only other location where a spill could occur. Aqua ammonia is pumped from the storage tank at a rate of 9 gallons per hour (gph). After thirty minutes (plant operators would normally respond within just a few minutes) of pumping with a seal leak occurring, 4.5 gallons would be spilled. Plant operators in the control room would recognize a low-pressure alarm, alarms from detectors of ammonia, and increased
NOx levels in the exhaust. The aqua ammonia would collect in a floor drain adjacent to the injection unit that is connected to an oil/water separator tank where the material would be diluted. This spill poses no threat to the operators since the operator's control room is provided with an independent ventilation system separate from the first floor where the injection unit is located. The distance from the injection seal (leak) to the 200 ppm ammonia concentration level is less than 50 feet but the mixing volume in the building containment is expected to quickly dilute the concentration to less than 25 ppm. The alternative release OSCA scenario, like the worst case release OSCA scenario also has no offsite impacts.
(d) The general accidental release prevention and chemical-specific prevention steps are based on passive and active mitigation systems. The passive mitigation measures have been discussed in (c) above. Active mitigation measures include a foam spray vapor suppressant s
ystem, fog misters, fire sprinkler system, emergency response program, and process controls. In addition, the interior air is exhausted to the outside atmosphere through a gaseous ammonia scrubber (impregnated activated charcoal) system.
An ammonia leak detection system is provided to monitor the ambient air concentrations near the aqua ammonia storage tank. In particular, gaseous ammonia detectors are located inside the containment structure, inside the catchment basin, outside the structure at the vent exhausts and other selected ambient air locations, and in the interstitial annular space of the double walled storage tank and piping. Ammonia concentrations above 25 ppm will be alarmed at the control room of the CUP.
The CUP is staffed 24 hours a day. A visual inspection of the exterior components of the aqua ammonia system will be performed daily by plant operation personnel. Preventative maintenance procedures will be followed. Low and high-pressure alarms are provided t
o monitor the underground storage tank, transfer system, and the ammonia injection unit. If a leak (release) is detected in the aqua ammonia system, the extent of the leak will be identified and the entire system will be rigorously inspected. A record keeping process will begin upon detection of a leak and continue to document subsequent inspections and appropriate actions taken to mitigate leaks, including repair efforts, until such time as the system is properly functioning.
Delivery times will be scheduled after consulting with the San Francisco Fire Department and with interested UCSF neighbors. Delivery times between 6am - 8am and 8pm - 10pm are proposed to eliminate weather stability, traffic congestion, and noise nuisance issues.
(e) This is a new facility with no accident history. The existing power facility has had no accidents and has an excellent operating history. According to the Ammonia Safety and Training Institute in Watsonville, CA there have been no reportable
accidents involving the handling of aqua ammonia in similar cogeneration facilities in California. The aqua ammonia delivery vendor, Hill Brothers Chemical Company, located in San Jose, CA, is a major supplier of aqua ammonia in the Western United States. They have been in business since 1923 and have had no reportable accidents in the transport and delivery of aqua ammonia.
(f) The UCSF Emergency Response Program is well established and has Standard Operating Procedures (SOPs) that are regularly reviewed and updated. SOPs specific to the aqua ammonia process are kept in the Plant Manager's office in the CUP. In addition, there are extensive and comprehensive references located at the UCSF Environmental Health & Safety Office to assist in addressing hazardous material situations. The Emergency Response Program meets local, state, and federal standards for training and competency. The aqua ammonia facility is included in this program and appropriate personnel from EH&S, plant ope
rations, and the UCSF Police Department will be trained to respond to potential aqua ammonia spills. Training will be coordinated with the San Francisco Fire Department, San Francisco Department of Public Heath and with the aqua ammonia vendor. UCSF maintains a liaison with the local responders and has a full time Fire Marshal on staff. The ERT is on call 24 hours/day, 7 days/week.
(g) Planned changes to improve safety are an on going UCSF commitment. The aqua ammonia process facility has been designed to meet and exceed applicable codes and regulations. UCSF has conducted hazard assessments (Hazard Operability Study - HAZOP) with the intent to identify and improve the facility. UCSF will conduct regular inspections, audits, and training and will continue to solicit ideas for modifications that could enhance and improve plant safety. UCSF will review and update the RMP as needed, but at a minimum of every three years.