Monocacy Water Treatment Plant - Executive Summary
The Department of Public Works for the City of Frederick, Maryland operates the Monocacy Water Treatment Plant (MWTP) in the northwestern area of the city. Surface water from a tributary of the Monocacy River is treated at the facility using various chemical treatments prior to being distributed to City water users. Based on an assessment of the chlorine system used at the facility (chlorine storage greater than 2,500 pounds), the MWTP is required under Title 40 of the Code of Federal Regulations (CFR) Part 68 and the United States Environmental Protection Agency (USEPA) to develop and implement a Risk Management Plan (RMPlan). The chlorine treatment system consists of twelve (12) 150-pound cylinders (six on-line, six on standby). Approximately thirty 150-pound cylinders of chlorine are also stored on site. The City operates the chlorine treatment system in accordance with standard industry practices and monitors the performance of the system on a regular basis. The safety of all M |
WTP operations are continually reviewed and improved through an internal safety committee that meets monthly. It is the policy of the City of Frederick to adhere to all applicable federal, state, and local laws.
USEPA's RMPlan provisions are intended to have facilities 1) prepare for and prevent the potential for a catastrophic release or explosion and 2) coordinate emergency response activities both internally and externally with local emergency planning officials. The likelihood of the worst-case release described in this plan is very low at the MWTP. However, should such an event occur, the MWTP will follow the contents of this plan in response to the emergency or potential emergency.
Under 40 CFR 68, facilities are required to comply with the RMPlan requirements by June 21, 1999. Compliance with this rule includes an electronic submittal to USEPA of required data elements using EPA's RMP*SubmitTM Software. The RMPlan and the data elements required in the submittal were dev
eloped based on USEPA's and American Water Works Association guidance documents including: General Risk Management Program Guidance (July 1998); Compliance Guidance and Model Risk Management Program for Water Treatment Plants (1998); and Risk Management Program Guidance for Wastewater Treatment Plants (October 1998).
After determining that the chlorine treatment system was an applicable processes, the City MWTP performed a program applicability assessment to determine the specific RMP requirements for the treatment system. This assessment is dependent on the following three factors.
(1) Five-Year Accident History: The chlorine system has never had an accidental release since they were installed in 1985.
(2) Worst-Case Release Consequence Analysis: The worst-case release for the chlorine system is estimated to be 900 pounds based on a failure of six 150-lb cylinders. Using a Slab Dense Gas Dispersion Model, the distance to the maximum allowable concentration [3 parts per millio
n (ppm) for chlorine] is estimated to be 3.14 miles. Such a release would affect a variety of offsite public receptors including a hospital, schools, recreation areas, and major commercial areas. The residential population within the 3.14 mile distance was estimated to be 33,584.
(4) Applicability of OSHA Process Safety Management (PSM) Regulations: The treatment process is subject to the OSHA PSM standard outlined in 29 CFR 1910.119. Since the worst case analysis identified impacted offsite public receptors and the facility is subject to OSHA's PSM regulations, the treatment processes are subject to Risk Management Program 3.
As required by the regulations, the facility also performed an alternative-case release consequence analysis for a more realistic (yet still unlikely) release scenario. Under this scenario, the facility assumed that an accidental gaseous chlorine release would originate from a damaged pipe. Based on the anticipated reaction of MWTP personnel, a conservat
ive estimate of fifteen pounds of chlorine would be released. Using this release scenario along with the USEPA's consequence analysis guidance, the City of Frederick estimates the distance to the maximum allowable concentration (3 ppm for chlorine) to be less than 0.1 miles. Given this distance, the release would not affect any off-site public receptors or residential populations.
The City of Frederick has also ensured that the facility is in compliance with the elements required under Program 3 of the prevention program. These requirements include implementing an emergency management system, maintaining pertinent safety information, conducting necessary hazard reviews, implementing appropriate operating procedures, providing necessary employee and contractor training, conducting routine preventative maintenance activities, and performing compliance audits.
If there is an accidental release from the chlorine treatment system, the MWTP will initiate the Emergency Response Plan an
d notify the local emergency planning committee (Frederick County Emergency Division).