Shades Mountain Filter Plant - Executive Summary
Risk Management Program |
Shades Mountain Filter Plant
40 CFR Part 68 Subpart G
The United States Environmental Protection Agency's (USEPA) Risk Management Program (RMProgram) rule, 40 Code of Federal Regulations (CFR) Part 68, was published on June 1996. This rule was developed to assist facilities in evaluating the relative risk and impact of an accidental release of highly toxic or flammable chemicals. The RMProgram applies to an owner or operator of a stationary source that stores or uses a listed chemical above a pre-determined threshold quantity (' 68.115).
The USEPA has established three tiers of requirements with different levels of detail. These tiers are known as Programs 1, 2, and 3. Program 1 applies to any process that has not had an accidental release with off-site consequences in the last five years and will have no off-site receptors in the event of a worst-case release, as defined by ' 68.22. Program 3 applies to facilities in sp
ecified industries, and to all processes subject to the Occupational Safety and Health Administration (OSHA) Process Safety Management (PSM) standard (29 CFR 1910.119). Program 2 applies to processes not covered by Programs 1 or 3.
The Shades Mountain Filter Plant (SMFP), a 80 MGD drinking water treatment facility, owned and operated by The Water Works and Sewer Board of the City of Birmingham (Board), uses gaseous chlorine, in amounts above the threshold quantity of 2,500 lbs., which is added to treated water for disinfection.
Due to the proximity of public receptors and that OSHA's PSM standard was not applicable, eligibility as a Program 1 or 3 facility was eliminated. Therefore, SMFP was reviewed and a RMProgram established under the requirements for a Program 2 facility (' 68.12).
' 68.155(a) Accidental Release and Emergency Response Policies
SMFP has procedures in place, including both onsite activities and coordination with off-site responders, that must be followed in the
event of a chlorine leak. These policies are presented in the Prevention Program (PP) and Emergency Response Program (ERP) sections of the RMProgram as required by 40 CFR Part 68 Subpart C and E.
' 68.155(b) Stationary Source and Substance Handled
The stationary source subject to 40 CFR Part 68 is the SMFP chlorination facility. The facility is divided into three individual areas: outdoor storage, chlorinator room, and scale room. One container is on-line at any one time yet the scales permit the attachment of up to six containers. A maximum of twenty-four containers may be stored off-line outside the scale room. These are manually transported to the scales when needed through the use of a hoist.
The scale and chlorinator rooms are equipped with chlorine detectors. Audible alarms automatically sound when chlorine levels reach 1 part per million, within the facility, which allows safety personnel time to respond to emergencies. In the unlikely event of a chlorine leak, an ala
rm in the control room of the SMFP informs the operator of the release and procedures in the Emergency Response section of the RMProgram are initiated.
' 68.155(c) Off-site Consequence Analysis
As a Program 2 process, two scenarios were assessed for the chlorine facility, one worst-case and one under alternative release conditions.
Wind Speed (m/s)
Direction of Wind
Atmospheric Stability Class
Ambient Temperature (0C)
Temperature Adjustment Factor
Dense or Buoyant Gas
Temperature of Released Gas (0C)
Amount of Release (kg)
Length of Time for Release (min)
Height of Gas Release (m)
Table ES-1: Off-site Consequence Analysis Parameters
Table ES-1 presents the required model inputs for the use of pre-calculated values found in Puglione
si et. al. (1998), which employed the use of the Aerial Locations of Hazardous Atmospheres (ALOHA) dense gas dispersion model. Default values, given in 40 CFR Part 68, were used in all cases except air temperature where an adjustment, based on local climatic data, was made (see Hazard Assessment section of the SMFP RMProgram).
As described in 40 CFR Part 68.25(b), the worst-case release shall be the greater of the following; (1) the greatest amount held in a single vessel or (2) the greatest amount in a pipe. The worst-case scenario was defined as the release of the contents of one 2,000 lb. container of chlorine, stored outside, to the air over a ten-minute period.
Alternative Release Scenario
A bad connection or valve failure was simulated for the alternative scenario, resulting in the release of gas through a 0.79 centimeter (5/16 inch) diameter valve. The hypothetical release simulated a container stored horizontally with chlorine escaping as a gas. The
hypothetical release occurred over 60 minutes at a rate of 4.76 kilogram per minute (10.5 lbs./min) (Puglionesi et. al., 1998).
Results of Off-site Consequence Analysis
For each scenario, the number of public receptors within the zone of influence was estimated, based on the 1990 United States Census Bureau data. Maps of the zone of influence and land usage can be found in the Hazard Assessment section of the SMFP RMProgram.
Radius of Influence (kilometers)
Radius of Influence
Table ES-2: Results of Off-site Consequence Analysis
' 68.155(d) Accidental Release Prevention Program
The PP elements are presented in the PP section of the SMFP RMProgram, as required by Subpart C. The following elements of the PP were developed with the intent of reducing the risk to employees and the public of injury or death from an accidental release of chemicals:
7 Safety Information ' 68.48
Hazard Review ' 68.50
7 Operating Procedures ' 68.52
7 Training ' 68.54
7 Maintenance ' 68.56
7 Compliance Audit ' 68.58
7 Incident Investigation ' 68.60
7 Management System ' 68.15
' 68.155(e) Five-year Accident History
SMFP has not had an accident, as described under 40 CFR 68.42(a), within the last five years.
' 68.155(f) Emergency Response Program
The ERP, as required by Subpart E, is provided in the SMFP RMProgram. Emergency response plans have been coordinated with local emergency planning agencies to minimize the duration and effects of an accidental release, thereby protecting the public health and environment.
' 68.155(g) Safety Improvements
Recommendations may be made upon the review of any accidents and/or when the RMProgram is update every five years.
Puglionesi, Peter S., Howard S. McGee, James Tittensor, and John O. Hammell 1998 Compliance Guidance and Model Risk Management Program for Water Treatment Plants, AWWA Research Foundation and A
merican Water Works Association. Denver, Colorado.