ROCKY CREEK WPCP - Executive Summary
EXECUTIVE SUMMARY |
Macon Water Authority maintains a Risk Management Plan for safe chlorine and
anhydrous ammonia handling that involves an approach that integrates technologies,
procedures and management practices to monitor potential hazards and minimize the risk
of accidental release. All applicable procedures of 40 CFR 68.170 are addressed in the
plan, which seeks to provide for employee safety, public health and response agency
Macon Water Authority utilizes chlorine to disinfect raw water pulled from the Ocmulgee
River at the Riverside Water Treatment Plant and operations will begin at the Town Creek Water
Treatment Plant sometime in the Fall of 1999. Once operations at Town Creek are at the
needed capacity the Riverside Water Treatment Plant will be closed. Chlorine is also used at the
Lower Poplar and Rocky Creek Wastewater Treatment Plants to treat wastewater before it
is returned to the Ocmulgee River. In addition, the Rocky Creek Pla
nt also uses
Anhydrous Ammonia to assist in treating wastewater. Chlorination processes include
(liquid) chlorination cylinders, chlorination equipment, and instrument room, electrical
equipment, and process specific safety equipment. Ammonia processes include (liquid)
Anhydrous Ammonia above ground tanks, an instrument room, electrical equipment, and
process specific safety equipment.
For each chlorination process accidental release modeling was performed for the respective
area to determine potential consequences associated with operating failures resulting in
accidental chlorine release. The first "worst case" scenario, defined by EPA, states that
"the owner or operator shall assume that the. . . maximum quantity in the largest vessel...is
released as a gas over 10 minutes." The "alternative scenario" is "more likely to occur than
the worst-case release scenario." Macon Water Authority has no incident history.
In each case, atmospheric dispersion modeling was performed to det
ermine the distance
traveled by the chlorine released before its concentration decrease to a theoretical "toxic
endpoint." This is defined by the American Industrial Hygiene Association as "the
maximum airborne concentration below which it is believed that nearly all individuals
could be exposed for up to one hour without experiencing or developing life-threatening
health effects." The residential population within a perimeter corresponding to the toxic
endpoint distance was defined to estimate the population potentially affected.
The worst case release scenario for the Macon Water Authority Plants involves a failure of
a one-ton cylinder yielding a cumulative release of 2,000 lbs of chlorine. When atmospheric
dispersion modeling for this unlikely scenario was performed using the RMP* Comp ver.
1.06 a distance to toxic .9 miles urban and 2.2 miles rural was obtained. The new Town
Creek Plant presently under construction is the only plant located in a rural area.
The alternative r
elease (more likely) scenario for all chlorination processes involves tubing
failure, bad connection, or valve failure resulting in the release of 317 lbs of chlorine.
When atmospheric dispersion modeling for this scenario was performed using the RMP*
comp Ver. 1.06 a distance to toxic endpoint of .1 miles urban or .1 miles rural was obtained.
The worst case release scenario for anhydrous ammonia involves a failure of a 10,000
pound tank yielding a cumulative release of 10,000 pounds of ammonia, when atmospheric
dispersion modeling for this unlikely scenario was performed using the RMP* comp ver.
1.06 a distance to toxic endpoint of .9 miles urban was obtained.
The alternative release (more likely) scenario was performed resulting in a release of 10
pounds/minute to a toxic endpoint of .1 miles.
Macon Water Authority Risk Management Program includes the following key elements to
mitigate the effects of potential chlorine release hazards:
Preventive Maintenance Program
Process specific safety equipment
Safe and effective standard operating procedures, written with operator
Hazard review of equipment and procedures and
Auditing and inspection programs
Comprehensive Management Program
Macon Water Authority has an active environmental, health and safety program with the
following elements specifically supporting the safe handling of chlorine and the anhydrous
Respirator protection (SCBA) program
Chlorine detectors, ammonia shut off valves
Chemical right to know program and
Personal protective equipment program
Macon Water Authority plants have an emergency response plan, which has been
coordinated with the City of Macon and Bibb County Fire Department which is a member
of the Local Emergency Planning Committee (LEPC). Emergency response dr
evaluations, and facility tours will be conducted annually, at which time emergency
operation and response procedures are also reviewed.
Macon water Authority takes a pro-active approach to risk management and emergency
response through continuous joint training sessions between MWA employees and local
response agencies. These preventive measures will provide for the continuous improvement
of communications and will maintain effective procedures for the safe handling of and
timely emergency response to potential chlorine or anhydrous ammonia incidents.