Wyman-Gordon Company North Grafton Plant - Executive Summary
The Wyman-Gordon Company, North Grafton facility is a manufacturer of ferrous and nonferrous forgings. The facility serves such international markets as commercial and military aerospace and land based gas turbine and power generation. Processes conducted at the facility include stock cutting, forging presses, heat treating, chemical milling and etching, machining, and inspection. These chemical milling and etching processes utilize hydrofluoric acid, nitric acid, and hydrochloric acid. However, only hydrofluoric acid, approximately 52,000 pounds, is maintained at a level above the threshold quantity, thus requiring the facility to submit an RMP. |
The North Grafton facility has a fully-trained and equipped HazMat Team for responding to releases. This includes OSHA HAZWOPER Incident Commanders and Hazardous Materials Technicians. The Haz Mat Team has received training in emergency response procedures, personnel protective equipment usage, including Level A and B suits, confined sp
ace entry and rescue, lockout/tagout procedures, and CPR. In addition, several of the team members are certified as First Responders to medical emergencies. The Team meets on a monthly basis and conducts practice drills each year.
The North Grafton facility has working agreements with local agencies for emergency response, including the fire and police departments, several hospitals and an ambulance service, as well as an emergency response contractor. The local agencies and response contractor have copies of the facility's Contingency Plan. The Manager of Environmental Engineering is involved with the local emergency planning committee.
The Incident Commanders have received training in public notification procedures in the event of an emergency. This includes notifications to the Massachusetts Department of Environmental Protection (MADEP) and the National Response Center. All employees have received training in emergency evacuation procedures.
Hydrofluoric acid (HF) is recei
ved at Wyman-Gordon's (W-G) North Grafton, Massachusetts facility in 55-gallon drums and in 3,300-gallon bulk shipments delivered by tank truck. Drum containers of HF are stored in a drum storage shed in the southeastern portion of the property. W-G has a bulk storage facility for HF with a tank capacity of 6,500 gallons, which is housed in a building attached to the west wall of the P. & M. Building. W-G has evaluated release scenarios for two processes, the bulk storage of HF and the drum storage of HF.
W-G has administrative procedures and process alarms that do not allow for the filling of the bulk HF storage tank to a level greater than 5,000 gallons. The tank sits in a building with a 675 square foot sump area designed to hold the entire contents of the HF tank. When required, HF is transferred from the bulk storage facility to the process tanks via a piping system that runs through a tunnel below floor level in the P. & M. building. Negative air pressure is maintained
in the tunnel and in the bulk acid storage facility. The air from these areas is drawn into the facility's wet scrubber system.
The worst-case scenario involves the release of 5,000 gallons of HF into the storage building sump area to form a pool with a surface area of 675 square foot. The pool evaporates at 770F and the evaporated acid escapes through a roof vent or other aperture. Although the scrubber system would normally treat the air from this room, this effect is not considered because active mitigation cannot be included in the worst-case release analysis. Worst-Case meteorological conditions assumed for this analysis are a 1.5 m/sec wind speed and an F stability class, in accordance with EPA's Offsite Consequence Analysis (OCA) Guidance.
The estimated distance to the toxic endpoint, determined using the procedures in EPA's OCA Guidance, is 0.3 miles based on "rural" topography. The rural topography assumption is appropriate for this analysis since the facility buildin
gs are not extremely tall and the area is surrounded by relatively flat terrain.
There are approximately 400 people living within the worst-case impact radius of 0.3 miles.
For the alternative case scenario, the entire contents of 15 feet of ruptured 2-inch hose from the delivery truck was assumed to spill within one minute onto the pavement outside of the bulk storage facility during an HF delivery. The spilled acid then forms a pool with a 1-centimeter depth, and the pool evaporates at 770F.
The estimated distance to the toxic endpoint is 0.1 miles. According to Landview III, there are approximately 30 people living within the alternative case impact radius of 0.1 miles. However, this estimate of population is based on the block group proration method, which is statistical in nature. In reality, a distance of 0.1 mile from the release point reaches only to the Wyman-Gordon fence line. Therefore, the population would be zero.
W-G stores 55 gallon drums of HF that are u
sed to provide make-up acid for process tanks at the facility that are not connected with the bulk acid transfer system. Drums of HF are stored outdoors in a designated drum storage shed. When acid is needed for a process tank, the drums are transported into the P. & M. building using a fork truck. The worst-case scenario involves the unmitigated release of the contents of one (1) 55-gallon drum of HF outdoors, such as might happen if a drum were to fall off a fork truck during transport and rupture. This scenario assumes that the acid forms a pool with a depth of 1 centimeter and that the pool evaporates at 770F.
The estimated distance to the toxic endpoint, determined using the procedures in EPA's OCA Guidance, is 0.6 miles based on "rural" topography. It has been determined that approximately 1700 people live within the worst-case impact radius of 0.6 miles.
The alternative case scenario assumes that a drum is pierced near the bottom with a fork from the fork truck outdoo
rs and that the entire contents (55 gallons) is released onto the ground, forming a 1-centimeter deep pool, and evaporates at 770F. Further assumptions are that the truck fork makes a 15 square inch puncture in the drum and that the puncture is 4 feet below the acid surface.
The estimated distance to the toxic endpoint is 0.2 miles. There are approximately 110 people living within the alternative case impact radius of 0.2 miles.