North County Regional Water Treatment Plant - Executive Summary
It is the policy of Collier County to operate safe water treatment facilities, reducing to the greatest extent possible any hazards associated with our processes and reducing any subsequent risk to the surrounding community, employees and the environment. It is also our policy to work with the surrounding community and local emergency response agencies, and promote a spirit of cooperation and teamwork to provide an effective contingency plan in the unlikely event that a process incident occurs at one of our facilities. |
The primary activity at the North County Regional Water Treatment Plant (NCRWTP) is municipal water treatment. Chlorine is the only 40 CFR 68 regulated substance at the facility. Chlorine is used primarily as a disinfectant. The maximum amount of chlorine at the facility is 17 tons.
Worst-Case Release Scenario (WCS)
The Worst-Case release scenario according to EPA's Offsite Consequence Analysis Guidance document is "the greatest amount held
in a single vessel." The worst-case scenario is the complete release of chlorine from a one-ton container. The worst-case scenario may not consider the use of active mitigation such as emergency scrubbers.
The chlorine toxic endpoint defined by 40 CFR Part 68 is 0.0087 mg/l which is equivalent to 3 parts per million by volume (ppm). According to the American Industrial Hygiene Association (AIHA) Emergency Response Planning Guideline (ERPG)-2, this toxic endpoint is specified 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 irreversible or other serious health effects or symptoms which could impair an individual's ability to take protective action."
The SLAB computer model was used to simulate the worst-case scenario. The maximum distance to toxic endpoint is 2.08 miles. This distance considered the mitigation provided by the building but did not include the use of
active mitigation measures such as the emergency scrubber.
A worst-case release is unlikely due to the materials of construction of the chlorine container. In addition, a comprehensive risk management program has been developed to prevent accidental releases.
Alternative Release Scenario
The alternative release scenario modeled is the worst-case scenario with the emergency scrubber in operation It is assumed that a one-ton container reputes and releases all of its contents within the Process/Chemical building. When the release is detected, the emergency scrubber is activated. There is no off-site impact for the alternative release scenario. This alternative release scenario is not likely to occur; however, it demonstates that off-site impacts do not occur even for the worst-case scenario when the active mitigation system is used.
Accidental Release Prevention Program
Collier County is in compliance with 40 CFR 68. The County has conducted a comprehensive review of the chlorine
system as well as administrative, technical, operating and maintenance procedures, in addition to the other required program elements of the regulations.
The County has both passive mitigation, an enclosed building, and active mitigation, an emergency scrubber, to minimize the consequences of an accidental release. The Risk Management Program addresses actions to minimize the likelihood of an accidental release and to minimize the impact if one occurs.
Five-Year Accident History
There was one incident which resulted in chlorine exposure to a contractor's employee. All available information on the accident is provided in the RMP form.
Emergency Response Program
This facility has an emergency response program that is coordianted with the Collier County Comprehensive Emergency Response Plan (ERP) that has been prepared in accordance with all local, state and federal regulations.
Planned Changes to Improve Safety
The hazard review resulted in the development of a list of improvem
ents and an implementation schedule. This is included in the Risk Management Plan (RMP). Continued training and practices documented in the RMP will continue to improve safety at the facility. Some of the more significant improvements are listed below:
To Be Completed by August 1999
To minimize the potential for product delivery trucks from damaging the buildings, equipment
and roadway, improvements to the roadway must be made. This work is currently in progress.
Chlorine containers must be rotated in the trunnions to properly align the valves prior to
connection. The wrench currently used is not adequate and procurement of this specialized
wrench is recommended.
The wrenches used to connect/disconnect chlorine containers are the proper Chlorine Institute
approved wrenches, however, they are old and worn. Replacement wrenches should be
purchased, and spare wrenches kept in stock.
Request Standard Operating Procedures for truck unloading and certi
fication that chlorine
meets AWWA specifications from the chlorine supplier. Inform plant personnel so that staff is
familiar with the supplier's safety and operating procedures.
Due to the chemical nature of chlorine, any work performed in the chlorine areas that involves
heat or sparks should be closely monitored. Hot work permitting should be implemented.
There is a danger that visitors or other untrained individuals may enter chlorine areas, which is a
potential risk. Signs should be posted in the chlorine storage area to designate it as a restricted
Proper use and maintenance of respirators is critical. A program for employees that wear
respirators should include medical exams, fit testing and training. Purchase spare parts for the
Develop an emergency evacuation plan for plant personnel. The evacuation plan should include
two egress routes and designate a location for staff members to reassemble.
The monorail u
sed to move chlorine containers has a potential of sticking in place. The monorail
should be lubricated with material that is compatible with chlorine use.
To be Completed By October 1999
There is a potential danger that the door to the building could shut while off-loading chlorine
containers. This could lead to dropping of the container, causing possible injury to the employee, or
otherwise compromising the integrity of the container. A door securing system
should be installed.
To Be Completed by November 1999
The existing vacuum regulators are old and require constant maintenance. It is recommended
that the regulators at this facility be replaced by November 1999 or earlier.
A preventive maintenance and replacement plan should be developed and implemented for the
vacuum regulators. Plugs should be utilized to prevent moisture and dirt from entering the
vacuum regulators when they are stored or immediately after servicing.
A spare vacuum
regulator should be purchased to enable continued operation while awaiting
An annual preventive maintenance program for the entire chlorine system should be prepared
and implemented. The preventive maintenance program should include the following equipment:
Valves on the solution line
Injector check valve
Pressure gauges on water or chlorine solution line
Flexible tubing from chlorine container to header (should be replaced at least once
Replace all gaskets and washers when servicing chlorinator
There are currently many false alarms regarding chlorine release, which leads to a tendency to
disregard alarms as likely to be false. An evaluation of the system and an established plan
should be implemented by November 1999.
The chlorine detectors and alarm system should be placed on an uninterruptable power supply
(UPS) to elimin
ate false alarms due to power outages.
Degradation of the PVC piping in the chlorine system occurs over time and it should be
replaced every five to seven years. An evaluation of the piping should be made by November
1999, and a replacement schedule implemented accordingly.
To Be Completed by January 2000
High speed vertical lifting of chlorine containers is not part of standard operations, however, it
is available and there is a risk of accidental use. The high speed vertical setting on the
monorail mounted hoist should be disconnected, if possible.
There is potential risk of a caustic gas release in an unsafe manner from the exhaust stack.
This is due to an inadequate rain cap. The rain cap should be modified or replaced.
The current location of the header vacuum gauge and valves is a trip hazard. The header
should be moved to a safer location to avoid potential falls, which could result in leakage at a
mplete modifications of the chlorine system alarms to minimize false alarms.
Consider providing position switches on normal ventilation dampers to notify plant personnel
of a failure to close during scrubber operation.
Several non-chlorine lines in the chlorine room are painted the same color as the chlorine
lines. Labeling and piping colors should be modified to be consistent with County or other
There is a potential for the motorized switch over system to fail during transfer of chlorine
containers to the scales. The motorized switch over system should be replaced with a
pressure operated switch over system or the system should be operated manually.
To Be Completed by October 2000
The monorail system used to off-load chlorine containers requires that the containers
eventually be rolled to their destination. The monorail system should be modified to allow
off-loading of chlorine containers without ro
lling or implement a system that does not require
To Be Completed by January 2001
The pressure relief valve will currently release chlorine gas to the room. The pressure relief
valve should be reconfigured so that released gas is directed to the chlorine scrubber. An
alarm should be provided for the pressure relief system. The alarm should initiate start of the
scrubber and notify plant personnel after the event.
Continued effort to reduce false alarms should include elimination of gas releases to the
atmosphere at the chlorine application point below the degasifiers, which potentially trip the
Install cable securing system for all ton containers. Securing the containers will provide
additional anchoring during a hurricane or other severe weather event.
NOTE: In Section 6 for the Accident History the quantity released, accident time, and accident release duration information is not available to us.