Fort George G. Meade - Executive Summary
Fort George G. Meade's (Fort Meade) is a Department of the Army facility whose primary mission is to provide housing, training, and operations and maintenance activities in support of the approximately 114 tenant organizations from all four services and numerous Federal agencies. One facet of this support is the operation of an Advanced Wastewater Treatment Plant (WWTP) and a Water Treatment Plant (WTP). Both facilities use chlorine (for chlorination). Chlorine is the only substance stored or used at Fort Meade in quantities that trigger Risk Management Program (RMP) rule applicability. |
The chlorine is stored in standard 1-ton cylinders at the building housing each chlorination process. At the wastewater treatment plant, four 1-ton chlorine cylinders (8,000 pounds total) are normally in place (connected in line) in the scale room. At the potable water treatment plant, three 1-ton chlorine cylinders (6,000 pounds total) are normally in place (connected in line) in the scale room.
There are usually a few 1-ton cylinders in storage outside the each scale room, under roof. Because the wastewater treatment plant and water treatment plant chlorination processes separately store/use chlorine in quantites greater than 2,500 pounds (at any one instant in time), each process is subject to the RMP rule.
Based on RMP rule criteria, the chlorination process at each water treatment facility is subject to the requirements stipulated for a "Program 3" process. Program 3 requirements apply because each process is subject to the Occupational Safety and Health Administration's Process Safety Management rule. (Because the offsite consequence analysis demonstrated that a worst-case release would have the potential to affect the general public, the processes cannot be designated Program 1 processes.)
The hypothetical worst-case release scenario for each of the two chlorination processes is the same. The worst-case release scenario assumes release, over a 10-min period, of th
e total contents of a completely full 1-ton chlorine cylinder. The chlorine scale room in which the release is presumed to occur is in an enclosed building, which is a form of passive mitigation. Therefore, based on EPA guidance, the mitigated release rate of chlorine is 55% of the unmitigated rate. Thus, the mitigated release rate of chlorine is 110 lb/min. The distance to the toxic endpoint for each chlorination process is 2.2 miles, which would encompass off-site residential populations and various public receptors. Because the two treatment plants are in different locations, different sets of receptors may be impacted. These results are based on application of the widely-used and EPA-recognized SLAB accidental release model. Affected populations were estimated using the EPA-recommended LandView III software.
Because of the similarity in the chlorination processes, the hypothetical alternative release scenario for each of the two chlorination processes is also the same. The
alternative release scenario assumes that the metal tubing coming from a full, on-line cylinder is accidentally severed. The above-mentioned passive mitigation (building enclosure) is assumed. Also, as an active mitigation measure, the Fort Meade Fire Department (FMFD) manually shuts off the flow of chlorine. No other passive or active mitigation methods or actions are assumed. Based on this release scenario, the estimated release rate is approximately 30 lb/min. The distance to the toxic endpoint for each chlorination process is 0.37 mile, which encompasses no residential populations for either process. However, public receptors (recreation areas) are encompassed by this distance for each process.
Note that there have been no accidental releases of chlorine in the past five years that meet the qualifications for inclusion in the five-year accident history.
The FMFD has emergency response plans for accidental releases of chlorine at the water treatment and wastewater treatment
plants. Emergency response procedures for accidental releases of hazardous substances are outlined in the Installation Spill Contingency Plan (ISCP) for Fort Meade. The ISCP contains notification procedures for contacting emergency response agencies (e.g., Anne Arundel County Fire Department) in the event of an accidental release. Any public notification would be conducted in coordination with the Anne Arundel County Fire Department. (The FMFD has a mutual aid agreement with the Anne Arundel County Fire Department.) Information on training and certification requirements for FMFD Hazmat Material Response Team (HMRT) personnel is contained in the ISCP. The FMFD follows Army Regulation (AR) 420-90 (which includes the National Fire Protection Association codes) for inspection, testing, and maintenance of its equipment.
A combination of engineering controls and administrative procedures are in place to prevent an accidental release of chlorine gas or liquid emissions from the chlo
rination processes at the WWTP and the WTP. The major engineering controls at include: process design controls (e.g., gas-fed vacuum controlled system, stainless steel schedule #80 piping in conformance with Chlorine Institute guidelines, line traps to remove impurities and reduce corrosion), process operation controls (e.g., pressure gauges, pressure relief and pressure reducing valves), and safety systems (e.g., chlorine sensors and audible alarms). Administrative procedures include a policy of delegating leak response and repair responsibility to the trained and fully equipped HMRT fielded by the FMFD. WWTP and WTP operators have been certified by the Maryland State Board of Waterworks and Waste System Operators. All WWTP and WTP staff are licensed by the State. Process Hazard Analyses (under OSHA Process Safety Management) were conducted for the WWTP and WTP in 1999.