Valley Forge Sewer Authority - Executive Summary

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INTRODUCTION 
 
The health and well being of every employee and the surrounding community is of vital importance to the Valley Forge Sewer Authority (VFSA).  Accordingly, the Authority strives to maintain its facilities in a safe manner.   This program has been especially successful with respect with our chlorination system as indicated the fact that there has not ever been an accident or leak of chlorine from the start up of our chlorination facilities in 1976 that has resulted in injury of any person, or migration of chlorine gas from the chlorination facility. 
 
The Valley Forge Sewer Authority provides sewage collection, conveyance and treatment for communities located in eight townships all located in Chester County Pennsylvania.  The VFSA is an operating Authority created in 1968 by Charlestown, East Pikeland, and Schuylkill Townships.  The Authority is the owner and operator of a 9.2 million gallon per day wastewater treatment plant located at 333 Pawling Road, RD #1, Phoenixville, 
PA, 19460.  In addition to providing service to the charter townships the Authority's treatment plant receives sewage from Easttown township, East Whiteland Township, Malvern Borough, Tredyffrin Township, and Willistown Township.  The VFSA employs 30 full-time professionals to operate and maintain the wastewater collection conveyance and treatment facilities in accordance with Permit Number PA 0043974 issued by the Pennsylvania Department of Environmental Protection (PADEP). A condition of the PADEP permit is that the VFSA provide treated wastewater disinfection to eliminate the potential of adverse effects from microorganisms in the treated effluent.  In order to meet these conditions for treated wastewater disinfection, the VFSA utilizes chlorine as an additive to the treated wastewater.  Chlorine is purchased in one ton cylinders that meet the specifications of the US Department of Transportation (DOT) and the Chlorine Institute.  The maximum number of containers at the VFSA facili 
ty is currently 9.  With future improvements, the number of containers routinely on site will be reduced to 6.  The chlorination system has been designed, sized, and installed in a manner that is appropriate and in accordance with good engineering practice.   
 
 
The VFSA is subject to 40 CFR Part 68 pertaining to risk management planning (RMP Rule) because it uses chlorine in quantities that are above the regulatory thresholds.  
As part of an upgrade to accommodate new customers, the chlorination system will be improved in late 1999 to early 2000.  These upgrades will improve upon our existing system and further reduce any risk of an accident.  The improvements consist of:  
 
7 Providing new trunnions for chlorine cylinders to allow for easier movement of potential leading cylinders to move leaks to the gas portion of the cylinder.   
7 Modifying cylinder-lifting tools to allow chlorine to be delivered via two separate locations thereby eliminating the need to lift cylinders and move them 
above cylinders that are in operation. 
 
RELEASE SCENARIOS 
 
A requirement of the RMP Rule, is that the facility must assess the affected area or "end point" that results from a "worst case" chlorine release. The end point is the distance where the concentration of chlorine is low enough so that nearly all individuals could be exposed for at lease 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.  Some individuals inside of this endpoint could be exposed to concentrations of chlorine that are above this endpoint concentration.  This assessment has been performed by the VFSA and a summary is presented hereon.  It must be noted that the worst-case scenario is based on the guidance found in USEPA, "Risk Management Program for Wastewater Treatment Plants, Program Guidance", Chapter 4 which states that the worst case release quantity is the greatest amount held in a singl 
e vessel.  Further, the Guidance document indicates that for worst-case scenarios involving chlorine  it should be assumed that a total release of the tank's contents will occur over a period of 10 minutes.  Other assumptions and estimates regarding topography and climate conditions such as wind speed and temperature must also be made to provide the data to assess the end point radius of the "worst-case scenario".  With this input data, the Guidance Document provides data on the estimated end point distances that would result from a worst case release.  
 
The "worst case" assessment performed by the VFSA consisted the following input parameters and resulted in an endpoint of 1.3 miles. 
 
Table 1 - Worst Case Assessment 
 
Chlorine Container Contents    2,000 pounds 
Release Rate    150 pounds/minute 
Temperature    25 degrees C 
Topography    Forested (considered to be urban) 
Wind Speed    1.5 meters/second 
Distance to Endpoint    1.3 miles 
 
The facility must also evaluate the affected area that would occur fo 
r an "alternative release" scenario.  In order for VFSA to assess the alternate release, the EPA Guidance Document indicated that the scenario selected must be one that, "is more likely to occur that the worst-case scenario".  Selection of such a scenario is difficult, considering that there have been no chlorine leaks on record since chlorine use was initiated in the 1976 that has resulted in injury or migration of chlorine gas from the chlorination facility.  However, to complete the required analysis, an alternative release scenario was selected that consisted of the following. 
 
A release of vapor chlorine occurs from the break of a nominal 3/8" fitting.  The release occurs when the chlorine facility is occupied.  The leak is identified and stopped by an operator by closing the cylinder valve after a period of 30 minutes after the leak occurs. 
 
The following is a summary of the input data and results of the Alternate Release Scenario, based on the tables provided in the, "Risk Manag 
ement Program for Wastewater Treatment Plants, Program Guidance". 
 
Table 2 - Alternate Release Assessment  
 
Chlorine Container Quantity    2,000 pounds 
Release Rate    15 pounds/minute 
Release Duration    30 minutes 
Total Released    450 pounds 
Temperature    25 degrees C 
Topography    Forested (considered to be urban) 
Wind Speed    3 meters/second 
Distance to Endpoint    0.1 miles 
 
The distance to the endpoint at 0.1 miles would not extend much beyond the boundaries of the VFSA treatment plant. 
 
ACCIDENTAL RELEASE PREVENTION PROGRAM 
 
The elements of the Prevention Program for the VFSA chlorination system consists of the following components: 
 
7 Safety Information 
7 Hazard Review 
7 Operating Procedures 
7 Training 
7 Maintenance of Equipment 
7 Compliance Audits 
 
Whereas incident investigation would normally be a component of a Program 2 system, the VFSA has not experienced any incidents involving leaks of chlorine.  Accordingly, although the mechanisms are in place for incident investigation, such investigation 
s have not been necessary to date.  The following provides a summary of each element of Prevention Program as implemented by the VFSA. 
 
Safety Information 
 
material safety data sheets 
 
Material Safety Data Sheets (MSDS) are provided and maintained for review by those individuals that may come in contact with chlorine or chlorination equipment.  The MSDS information is posted in the chlorine facilities, in the standard operating procedures (SOPs) and in the Wastewater Treatment Plant Emergency Response Plans, maintained at the VFSA.  Of course, on going operator-training programs assure that individuals are thoroughly trained in the potential hazards associated with chlorine as well as all chemicals handled at the facility. 
 
maximum intended inventory 
 
Maximum intended inventory at the facility consists of nine (9) one ton chlorine cylinders. Design upgrades for the chlorination facility will include the modification of chlorine delivery and return of empty containers. Chlorine cylinder 
s must be ordered before they are delivered to the facility.  Therefore, the inventory may never exceed the maximum intended inventory. 
 
storage and process limits 
 
The chlorine is handled in electrically heated facilities.  Thermostats control the temperature in these facilities, and the relatively low capacity of the heaters would prevent the excessive heating of the one ton chlorine cylinders. However, there are no potentially flammable chemicals or potential sources of fire in or around the chlorination facility that would result in such an occurrence. 
 
Pressure in the piping from the chlorine cylinders to the vacuum regulators is controlled by the vacuum regulators, which are part of the system.  The amount of pressure that can build up upstream of the pressure regulator is limited by the vapor pressure of the chlorine in the cylinder.  The upstream piping, which is under pressure, may only be subjected to the pressure generated by the vapor pressure of the liquid chlorine in the  
cylinder. This vapor pressure is a function of the substance in the cylinder (chlorine) and the ambient temperature.  This pressure is well within the pressure rating of the piping. 
 
All piping downstream of the pressure regulators is under vacuum.  The vacuum is produced by an eductor, and the amount of vacuum produced is limited by the size of the eductor, and the eductor's water supply, which is limited by the capacity of the pump supplying water to the eductor.  These are single speed pumps, which can supply only one flow rate to the system.  The amount of vacuum produced is well within the vacuum rating of the piping. 
 
codes standards and equipment specifications 
 
All components of the chlorination system have been designed and installed in a manner that is appropriate to its intended service.  Piping is in accordance with American National Standards Institute (ANSI), and American Society for Testing Materials (ASTM) standards.  Chlorine cylinders are designed in accordance with D 
OT specification 106A500X.   Vacuum regulators, chlorine detectors, eductors, heaters, lights, exhaust ventilators, and doors were designed by reputable manufacturers such as Bailey Fischer, and Porter specifically for use in chlorination systems, as are all other components of the system.  System components were sized and designed in accordance with their capacity and good engineering practice.  Manufacturer literature on system components is maintained at the VFSA facility. 
 
updates 
 
Safety information is updated when major changes to the facility are made. 
 
Hazard Review 
 
A Hazard Review was conducted on 3 May 1999.  The VFSA utilized both checklists and an on site review of facilities.  As a result of the hazard review, the VFSA identified several possible upgrades to the system.  Some of these upgrades will be implemented while those involving capital improvements, will be considered for inclusion in the year 2000 capital program or the longer-term capital budget. In addition to t 
he short and long term upgrades to the system that are under either being implemented or are under review, there will be several improvements to the chlorination system that will be implemented resulting to the need to provide additional rated capacity of the treatment plant.  These improvements are due to be constructed in late 1999, early 2000.  A summary of the improvements are listed below: 
 
construction in late 1999, early 2000 
 
7 Providing new trunnions for chlorine cylinders to allow for easier movement of potential leading cylinders to move leaks to the gas portion of the cylinder.   
7 Modifying cylinder-lifting tools to allow chlorine to be delivered via two separate locations thereby eliminating the need to lift cylinders and move them above cylinders that are in operation. 
7 Providing new state of the art monitoring equipment to monitor and alarm if leaks are detected. 
 
Operating Procedures 
 
Written operating procedures for the chlorination facilities are maintained in the c 
omprehensive Standard Operating Procedures for the VFSA.  The SOPs are part of a comprehensive operator-training program that includes on the job training, training from outside agencies, and training tools such as videos. 
 
Training 
 
Operators receive training on a yearly basis.  The initial training for chlorination includes on the job training where inexperienced operators are accompanied by experienced operators when performing any task having to do with the chlorination equipment.  It is only when the Operations Manager is satisfied that the newly trained employee is totally capable of safely performing the tasks, that he is given that responsibility.   
 
Maintenance 
 
All equipment at the VFSA is part of a preventative maintenance (PM) program.  There is a computer program, that includes a compilation of maintenance SOPs, and a PM schedule.   All PM frequencies are at least as frequent as those provided in the manufacturer's operations and maintenance manual.  Critical equipment suc 
h as vacuum regulators, chlorine monitors, and cylinder connections are checked on a daily basis.  
 
Compliance Audits 
 
Compliance Audits are implemented in accordance with the RMP requirements at least once every three years.  This is to include checklists, a facility walk through, discussions with employees, and documentation of findings of the audit.   
 
Five Year Accident History 
 
There has not been an accidental release of chlorine since the chlorination system started up in 1976.  
 
EMERGENCY RESPONSE PROGRAM 
 
The VFSA has an emergency response plan that was developed in 1996, and periodically updated.  This "Preparedness, Prevention, and Contingency (PPC) Plan is a requirement of PA Code 25, Chapters 101.3 and 78.55.  The purpose of the PPC Plan is to minimize and abate hazards to human health and the environment from fires, explosions, or release of hazardous waste to air, soil, or surface water.  The appropriate response to leaks is an integral part of the VFSA SOPs, training pro 
grams, and PPC Plan. 
 
The Plan delineates the organizational structure, duties, and responsibilities of those individuals and organizations responsible for responding to emergencies in the facility.  It includes procedures for responding to spills, such as reporting, arrangements with emergency response agencies and hospitals, notification lists, and chemical information.  Spill countermeasures are described in the Plan.   
 
In addition, in cooperation with the Chester County Emergency Coordinator, the VFSA has participated in the development of a Community Response Plan.  The Plan was developed to meet the provisions of the Superfund Amendments and Reauthorization Act of 1986 (SARA) Title III, by the Local Emergency Planning Committee for the Emergency Planning District of Chester County.  The plan describes the response to a hazardous material incident emergency at the VFSA.  The elements of the Plan consist of: 
 
7 Categorizing types of releases according to the level of potential haz 
ard. 
7 Delineating responsibilities of the various response organizations, including notifications. 
7 Describing the concept of operations for an appropriate response. 
7 Describing training and exercises that will be implemented. 
 
Future Plans 
 
The following items are being considered by the VFSA for future implementation. 
 
7 Providing automatic shutoff valves on the chlorine cylinders with interlock to the chlorine monitor.  This will enable VFSA to automatically shut off valves on the chlorine cylinders if a leak is detected by automatic leak monitoring equipment. 
7 Providing additional warning signs. 
7 Indicating locations of underground chlorine vacuum conveyance lines. 
7 Implementing additions to the operating procedures to firm up safety during delivery of cylinders to the facility, and assure that contractors working at the facility are versed on potential hazards resulting from chlorine leaks.
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