GAC Chemical - New England - Executive Summary
RMP Executive Summary |
General Alum & Chemical Corporation
Searsport, Maine 04974
June 18, 1999
General Alum & Chemical Corporation is committed to the safe and environmentally responsible handling and production of all chemicals and materials at its facility in Searsport, Maine.
Both of the substances regulated under the Risk Management Program at this facility, anhydrous ammonia and aqueous ammonia, are included in the facility's Process Safety Management Plan.
The safety program has been very effective in Searsport. The last lost-time injury was nearly four years ago (October 4, 1995).
The facility is ISO 9002 certified.
General Alum & Chemical Corporation manufactures primarily inorganic chemicals at its Searsport facility. With regards to 40 CFR Part 68, anhydrous ammonia and aqueous ammonia (>20% concentration) are handled and stored at quantities exceeding the threshold quantities.
Anhydrous ammonia was first used at the site in 1956 with th
e startup of an anhydrous ammonia synthesis plant. The facility included two 2000 ton refrigerated storage spheres. This production unit operated until 1966 when it was shutdown due to business conditions. The production facility was sold and dismantled in 1967. One of the storage spheres was used for storage of refrigerated anhydrous ammonia until 1988 when its use for storage was discontinued. The second sphere was maintained in serviceable condition for backup purposes only. The spheres were dismantled and sold for scrap in 1994.
After the use of the spheres for storage was discontinued, anhydrous ammonia was stored in smaller horizontal pressure vessels. The larger vessel (16,700 gallon working capacity) is located in the ammonia receiving area while the smaller vessel (3,900 gallon working capacity) is located in the ammonium sulfate production area.
Anhydrous ammonia is used at the facility to produce aqueous ammonia and ammonium sulfate. No anhydrous ammonia is shipped f
rom the facility.
The anhydrous ammonia is received in 86 ton capacity rail cars. It is unloaded in a closed system using a compressor to remove the vapors from the larger storage vessel and pressurizing the rail car with this vapor. The resultant differential pressure pushes the liquefied anhydrous ammonia to the storage vessel. The maximum pressure in the anhydrous ammonia system during unloading and storage is 120 psig. The operational pressure rating for the storage vessel is 250 psig.
Transfers of anhydrous ammonia from the larger storage vessel to either aqueous ammonia production or the smaller storage vessel is via small transfer pumps.
The aqueous ammonia unit started production in May 1995. Aqueous ammonia is produced by injecting a controlled volume of anhydrous ammonia in a recirculating flow of unfinished aqueous ammonia. The batch production process is continued until the desired concentration of ammonia in the solution is reached. The maximum batch size (limited
by the working capacity of the production tank) is approximately 9,000 gallons. Finished aqueous ammonia is stored in a 28,400 gallon working capacity tank. Both of the aqueous ammonia vessels are located in a common containment structure.
Ammonium sulfate has been produced in Searsport since 1949. A new modern production unit went into service in October 1992. The older unit was shutdown in August of that year.
Anhydrous ammonia is supplied to the ammonium sulfate process as a vapor. The smaller anhydrous ammonia tank is coupled with a small vaporizer. The combined units are maintained at a constant level to permit steady-state vaporization of the ammonia. The maximum pressure in this anhydrous ammonia system during ammonium sulfate production is 120 psig. The operational pressure ratings for both the smaller storage vessel and the vaporizer are 250 psig each.
No regulated waste ammonia, anhydrous or aqueous, is generated by any handling or processing at the Searsport facility
. The conversion of anhydrous ammonia in both processes is 100%.
Three regulated processes exist at the facility.
Process 1: Anhydrous ammonia receiving and storage
Process 2: Aqueous ammonia production and storage
Process 3: Ammonium sulfate production
All release scenarios were analyzed using RMP*Comp for the impact radius calculation and Landview III for estimating the effected population within the impacted area.
Process 1: Catastrophic failure of an anhydrous ammonia rail car containing 172,000 pounds of material. No containment or passive mitigation was used. The calculated impact radius is 6.9 miles. The estimated population that may be impacted is 11,000. A catastrophic failure is extremely unlikely since it would require a structural failure of the stationary rail car or the impact and penetration of the vessel shell by some object of significant mass and/or velocity. The rail cars are maintained (inspections, external coatings) b
y their owners to prevent external corrosion from the weather. The anhydrous ammonia grade shipped to General Alum (includes trace quantities of water) is not corrosive to the steel tank interior. The possibility for an object piecing the rail car vessel is very unlikely due to the isolation of the anhydrous ammonia unloading location and the absence of other activities or traffic in the area.
Process 2: Catastrophic failure of the aqueous ammonia (30% concentration) storage tank containing 212,200 pounds of solution (63,660 pounds of 100% ammonia). The tank is located within a containment structure with a surface area 1424 square feet and a depth of 39 inches. The calculated impact radius is 0.4 miles. The estimated population that may be impacted is 10. A catastrophic failure is extremely unlikely since it would require a structural failure of the tank. The tank is maintained (inspections, coatings) to prevent external corrosion from the weather. The aqueous ammonia is not
corrosive to the steel tank interior. External impact is not possible due to the physical installation barriers.
Process 3: Catastrophic failure of an anhydrous ammonia process tank in the ammonium sulfate area containing 20,700 pounds of material. No containment or passive mitigation was used. The calculated impact radius is 2.6 miles. The estimated population that may be impacted is 1,900. A catastrophic failure is extremely unlikely since it would require a structural failure of the stationary storage tank or the impact and penetration of the vessel shell by some object of significant mass and/or velocity. The vessel is maintained (inspections, external coatings) to prevent external corrosion from the weather. The anhydrous ammonia grade used (includes trace quantities of water) is not corrosive to the steel tank interior. The possibility for an object piecing the tank is very unlikely due to the location of the vessel and the absence of other significant activities or
traffic in the area.
Process 1/Alternate 1: The partial failure of a transfer hose connecting the unloading anhydrous ammonia rail car and the fixed transfer piping. The partial transfer hose failure scenario is a 0.5 inch diameter hole due to fatigue of the hose. The calculated impact radius is 0.5 miles. The estimated population that may be impacted is 10. Before a hole or tear in the hose would occur, a blister or bubble on the surface of the hose would be visible to the operator. It is the standard operating policy in this area to routinely inspect the hoses prior to and during their use. Any suspect hose is either tested or replaced. It is not likely that hose deterioration would progress unnoticed to the point where a breach could occur.
Process 2/Alternate 2: The complete separation of a truck loading hose from its fitting during the loading of an aqueous ammonia tank truck. For this scenario, it is assumed that the end of the hose that is outside the stor
age containment is the end the came loose. The calculated impact radius is 0.1 miles. No population would be impacted since the endpoint is within the company boundaries. The loading operation is done under the direct observation on an operator. If a hose fitting were to come loose, the operator would be able to immediately stop the pump. There is no pressure in the aqueous ammonia system that would permit the continuance of the flow of aqueous ammonia through the open hose after the pump stopped. Since the beginning of the aqueous ammonia operation in 1995, there have no instances of a hose separation during the loading of tanker trucks.
Process 1/Alternate 3: The release of ammonia vapor via a faulty pressure relief valve on the larger anhydrous ammonia storage tank. The release calculation assumed full, unrestricted vapor flow from one of the two valves on the tank at a pressure of 225 psig. Normal maximum operating pressure of this vessel in 120 psig (via process and oper
ator controls). The calculated impact radius is 0.4 miles. The estimated population that may be impacted is 10.
Process 3/Alternate 4: The release of ammonia vapor via a faulty pressure relief valve on the smaller anhydrous ammonia storage tank located in the ammonium sulfate production area. The release calculation assumed full, unrestricted vapor flow from one of the two valves on the tank at a pressure of 225 psig. Normal maximum operating pressure of this vessel in 120 psig (via process and operator controls). The calculated impact radius is 0.4 miles. The estimated population that may be impacted is 10.
Process 3/Alternate 5: The release of ammonia vapor via a faulty pressure relief valve on the anhydrous ammonia vaporizer located in the ammonium sulfate production area. The release calculation assumed full, unrestricted vapor flow from one of the two valves on the tank at a pressure of 225 psig. Normal maximum operating pressure of this vessel in 120 psig (via process
and operator controls). The calculated impact radius is 0.3 miles. The estimated population that may be impacted is 10.
All aspects of ammonia handling and use at the facility are covered by the facility's Process Safety Management Plan. The standard operating procedures (SOPs) are reviewed and updated whenever a operation change is made. If no operational changes are made, the SOPs are reviewed annually and updated as necessary.
The ISO 9002 program at General Alum requires rigid compliance to SOPs, preventive maintenance procedures, and instrument calibrations. All procedures must be reviewed annually. The ISO program is audited internally every year (audit components are distributed throughout the year) and recertified by a third party annually.
Mandatory monthly training sessions are attended by all production and maintenance employees. The subjects include annual training of SOPs, hazards communications, fire safety, electrical safety, and pollution
General Alum supports a fully trained and equipped Hazmat Team to address incidents that may occur at the facility and in the transportation of product shipped from the facility. Depending upon the circumstances of an on-site or transportation incident, a contract responder such as Clean Harbors may be called-in for assistance.
FIVE-YEAR ACCIDENT HISTORY
There have been no accidental releases of anhydrous ammonia (vapor or liquid) or aqua ammonia in the last five years.
EMERGENCY RESPONSE PLAN
The Emergency Response Plan for the facility was first published in April 1991. It was completed reviewed and updated in February 1999. The plan covers all the processes and chemicals handled at the facility. The plan is coordinated with the Waldo County Emergency Management Agency and the Waldo County LEPC. Copies have been supplied to the Maine Emergency Management Agency, the town of Searsport and the neighboring town of Stockton Springs.
PLANS FOR MPROVEMENTS
al Alum's safety record has been good for many years. Management continues to place the highest priority on the safety and environmental programs for the facility. Improvements in the programs occur through ongoing review and annual updates by employees in all areas of production, maintenance, supervision and management.
The arrangement that General Alum has with third party Hazmat responders is on an as-needed basis. Formalizing the relationship with a contract agreement is being considered for implementation. A decision will be made before the end of 1999.