Hartford Water Pollution Control Facility - Executive Summary
The Metropolitan District's (MDC) Hartford Water Pollution Control Facility (HWPCF), operating since 1938, is located at 240 Brainard Road in Hartford, CT. Wastewater from Hartford and several surrounding communities is treated at the HWPCF, and final effluent is discharged into the Connecticut River. The wastewater treatment process includes preliminary screening, primary settling and treatment, secondary treatment and clarification, sludge processing, and chlorination of the final effluent before discharge. The HWPCF handles wastewater flows averaging 60 million gallons per day.
Chemicals are widely used in industry, in the home and in the environment. They are transported on roads, water and railways. The natural world contains more than 1,500 chlorine-containing compounds. Human cells generate hypochlorite, a form of chlorine, to fight infection. Chlorine purifies our drinking water, disinfects our swimming pools and is truly life saving. The HWPCF uses chemi
cals, too. For example, they use chlorine to disinfect treated wastewater prior to discharge to the environment.
Storing and using chemicals can be hazardous if not done properly. The HWPCF takes safety obligations in handling chemicals seriously. MDC has used chlorine at the HWPCF for over 29 years without an accidental release. MDC employees receive extensive on-going chlorine safety training.
This document summarizes MDC's existing safety systems, policies, procedures, and on-going actions that are designed to prevent or minimize impacts of accidental releases of chlorine to the environment.
Accidental Release Prevention and Emergency Response Policies
The HWPCF Risk Management Plan (RMP) complies with the U.S. Environmental Protection Agency's (EPA's) Risk Management Program, under Section 112 (r) of the Clean Air Act (CAA) Amendments of 1990, 40 Code of Federal Regulations (CFR) Part 68. The Risk Management Program requires facilities that use certain substances to devel
op a plan to reduce the likelihood of an accidental release of the substances to the atmosphere and reduce the likelihood of serious harm to the public and the environment.
The HWPCF has a chlorination system that uses chlorine gas fed from chlorine one-ton containers. Chlorine is stored in a quantity above the regulatory threshold (2,500 lbs.) at which a RMP is required. The HWPCF has prepared a detailed and comprehensive Emergency Action Plan to handle any potential releases. The Emergency Action Plan, along with the RMP program, describe what actions to take in the event of a release and how to prevent any releases from occurring.
MDC is committed to protecting its employees, the public, and the environment from any releases of hazardous materials used at its facilities. Throughout its history, MDC has had an excellent record in accident prevention.
Chlorine is used to disinfect the treated wastewater prior to discharging it to the Connecticut River during the mont
hs of May through September. The objective of chlorinating the wastewater is to destroy pathogenic microorganisms contained in the wastewater. Wastewater disinfection prevents the spread of diseases and protects surface waters used for recreation and as a habitat for aquatic life.
Chlorine is non-explosive and non-flammable, but, like other chemicals, it is capable of combustion under certain circumstances. It is also a respiratory irritant. Exposure through inhalation or eye or skin contact can cause severe health problems. The HWPCF has several safety systems that are a part of the chlorine system. These safety systems, along with the Prevention Program described below, greatly reduce the possibility of a leak occurring.
A chemical distributor delivers chlorine containers to the plant. Chlorine is withdrawn directly from the one-ton containers and delivered to the chlorination process. Two chlorine leak detectors continuously monitor for leaks. Leak alarms activate an audi
ble alarm throughout the plant and an alarm light in the monitoring room on the control panel. Other examples of safety systems include high and low gas vacuum alarms. Chlorine gas is delivered under vacuum. If a leak were to occur in this piping, outside air would be drawn into the piping rather than chlorine gas leaking out of the piping.
The chlorine containers are inside a fenced area with a surveillance camera. The camera operates 24 hours each day during the chlorine season (May-September) and a monitor is located in the control room, which is staffed 24 hours per day. There are entry alarms on the gate and doors to the area. MDC owns and keeps the following equipment on-site: self-contained breathing apparatuses (SCBA), response suits and a ton container repair kit. Approximately 25 employees are trained in proper operation of the chlorine system. They also receive extensive initial and annual safety training. Drills are held annually, with the operators wearing SCBA a
nd response suits. The training for chlorine emergency response is in compliance with 29 CFR 1910.120(q).
The HWPCF's effluent discharge permit, administered by Connecticut Department of Environmental Protection, requires the plant to chlorinate the wastewater effluent from May 1st through September 30th. Other than the few weeks prior to, during and the few weeks after chlorine season, no chlorine is on-site. A complete preventative maintenance program is administered on all chlorine piping and equipment.
The RMP consists of three major parts. The first part is the Hazard Assessment. The Hazard Assessment is performed to determine the effects that a release of a regulated substance could have on the public. The second part is a Prevention Program that consists of 12 elements designed to improve the system safety and decrease the likelihood of a release. The third part is the Emergency Response Program, which develops a plan for dealing with a release in the
unlikely event that one would occur. Because the regulations are very similar, the Prevention Program and the Emergency Response Program also serve as the OSHA Process Safety Management (PSM) plan. This document is therefore referred to as the RMP/PSM plan.
A Hazard Assessment was performed to determine the effects a release could have on the public. For chlorine, the distance a set endpoint concentration of the gas could travel was determined. In addition, an estimate of the population that could be affected by the release of chlorine was determined, and sensitive receptors such as hospitals, parks, and schools were identified. The Hazard Assessment considers two release scenarios - a "worst case" and an "alternative case."
Worst Case Scenario
The regulations require the development of a worst-case scenario based on conservative assumptions. For example, it is required to assume that the entire contents of the largest single container of chlorine will be
released over ten minutes. This is unlikely to occur since the properties of chlorine would cause a freeze and thaw cycle to occur at the leak, which would slow the release. In addition, only "passive" mitigation methods such as buildings or dikes for aqueous substances can be considered when determining the distance a release could travel. Passive mitigation, as defined, includes no mechanical, electrical, or human input. However, in many scenarios mitigating the release by isolating the process could significantly reduce the amount released. In addition, the worst-case scenario requires that conservative atmospheric conditions be assumed which results in a large area of impact. These conservative assumptions were set by EPA to ensure public notification and local emergency response planning takes into account the greatest possible impacted area surrounding the release point.
The worst-case scenario used for chlorine at the HWPCF is the rupture of a one-ton container, result
ing in a release of 2,000 pounds of chemical over a ten-minute duration. The container rupture resulting in a chlorine release could be caused by catastrophic events, such as a tornado. This type of a catastrophic release is unlikely to occur. The released liquid is assumed to quickly volatilize and to disperse as a vapor cloud. The hazard assessment requires a determination of the "toxic endpoint", or distance from the point of release to a location at which the chemical concentration equals a certain concentration. The distance to the toxic endpoint was estimated using the EPA-approved DEGADIS BREEZEHAZ+ model.
The RMP regulations define the toxic endpoint of a release of chlorine as the farthest distance at which a receptor would experience a chlorine concentration of 3 parts per million (ppm). The concentration at the circle surrounding the plant defines the boundary of the area that would be impacted by a release, and the concentration at the circle is 3 ppm. If a leak wer
e actually to occur, the vapor cloud would only travel in the direction of the prevailing wind, not in all directions around the facility. The 3 ppm endpoint concentration is the Emergency Response Planning Guideline Level 2 (ERPG-2) concentration defined as the maximum concentration at which most individuals could be exposed for up to one hour without experiencing irreversible or serious health effects. Because the cloud from a leak of chlorine would disperse relatively quickly, an individual located at the toxic endpoint would be exposed to a chlorine concentration of 3 ppm for much less than one hour. It has been demonstrated, through EPA approved DEGADIS BREEZEHAZ+ dispersion modeling, that an individual located at the toxic endpoint would be exposed to a chlorine concentration of approximately 3 ppm for only three to ten minutes compared to the ERPG-2 allowable exposure time of one hour.
The RMP rule also requires that at least one alternative release sc
enario be evaluated for chlorine. The alternative scenarios reflect a type of release that is more likely to occur compared to the worst-case scenario. Unlike the worst-case scenario, the alternative release scenario may consider "active" mitigation such as shutoff valves and a more realistic release quantity and release rate. Active mitigation is defined as requiring mechanical, electrical or human input. It assumes local, typical meteorology, which is more realistic than the conservative meteorological conditions that must be assumed for the worst-case scenario. The alternative release scenario for chlorine, modeled using the EPA approved ALOHATM model, a release through a 5/16-inch diameter vapor valve in the top of a horizontal tank. Under this scenario, the amount of chlorine released was calculated to be 175 pounds. For the second alternative release scenario, the same modeling approach was used as for the worst-case release scenario, except meteorological conditions were
adjusted to represent more realistic conditions. The results of the dispersion modeling analysis for both alternative release scenarios indicate that these scenarios have an offsite impact.
However, no chlorine releases that could have caused a safety or health hazard (no deaths, injuries, property or environmental damage, evacuations, or sheltering in place) have occurred at the HWPCF during the last 29 years. Chlorination began at the HWPCF on June 25, 1969. A chlorine release did occur at the HWPCF on July 23, 1969. The system at the time used a tanker truck, liquid chlorine and a pressurized system. The system was redesigned and chlorination resumed on July 9, 1970. The important differences in the 1969 system and MDC's current system are: 1) the container volume in 1969 was 16 tons; today one-ton containers are used. The result, if a release were to occur, would be significantly smaller with the current system. 2) In 1969, the chlorine was used as a liquid; today it is us
ed as a gas. This is important because liquid chlorine, upon release, expands tremendously. 3) Most of the system today is under a vacuum; in 1969 it was a pressurized system. 4) In 1969 there was minimal training with the chlorine system. Today, MDC operators undergo extensive initial and annual chlorine safety training.
The Prevention Program together with the Emergency Response Program make up the RMP/PSM. The Prevention Program consists of 12 elements designed to improve system safety and decrease the likelihood of a release. The elements are as follows.
The participation of the HWPCF staff in preparing the RMP/PSM program was critical to the program's successful implementation. Employee participation is valuable because it increases the safety awareness of the staff and it allows the staff's experience in operating and maintaining the processes to be incorporated into the plan.
HWPCF staff participated in the development of th
e Prevention Program through a series of meetings and workshops as well as the Process Hazard Analysis described below. HWPCF staff received RMP/PSM awareness training that instructed staff on how the RMP/PSM requirements may impact their jobs. Staff who operate and maintain the RMP/PSM were trained in how to safely maintain and operate the processes.
Process Safety Information
The RMP regulations require that information concerning process chemicals, technology and equipment be compiled as part of a RMP program. Emergency response planners can use such information to develop training programs and procedures, or as a general resource. The information will be supplied to contractors who will work in the chlorine process areas as part of the requirements outlined in the Contractor Safety element. All the required process safety information was compiled as required by the RMP regulations. The information meets or exceeds the minimum required by the regulations.
Process Hazard Ana
A Process Hazard Analysis (PHA) was conducted systematically to evaluate potential causes and consequences of accidental releases. This information was used by HWPCF staff to improve safety and reduce the consequences of accidental releases. Equipment, instrumentation, utilities, human actions, and external factors that might affect the process were the focus of the PHA that was preformed for the chlorine process
The chlorine PHA was conducted by an interdisciplinary team of HWPCF staff familiar with the process, operation and maintenance and plant management. The PHA was done using the "What-If" and "Checklist" methods. Based on the results of the PHA, several minor changes in the operating, maintenance and other process safety management procedures that would improve the overall safety of the HWPCF were identified.
Written operating procedures for the chlorination process have been developed as part of the RPM/PSM. Written operating procedures assu
re continuous, efficient and safe operation of the facility. The goal of the operating procedures is to provide clear instructions to safely operate the process. Operating procedures are also used to train new employees and to provide refresher training for existing staff.
The detailed operating procedures include startup, shutdown and emergency operating procedures. The procedures describe how the system should be operated in order to minimize the chances of an accidental release. The procedures emphasize safety considerations during operation and address hazardous situations that can occur and how to correct them.
An effective RMP/PSM training program can significantly reduce the number and severity of accidental release incidences. Employees involved in operating or maintaining the chlorination process must receive training that includes applicable operating and maintenance procedures and an overview of the process. Training must emphasize safety and health hazards
and safe work practices. HWPCF staff have received initial training on the operations and maintenance of the regulated process, an overview of each of the RMP/PSM plan elements, and the procedures that must be followed to comply with the requirements of the RMP/PSM plan. In addition to RMP/PSM plan training, select HWPCF staff have been trained to respond to an accidental release. Refresher process operation training will be provided at least every three years. Refresher training for emergency response is conducted annually.
The HWPCF must make contractors aware of the known hazards of the chlorine process related to the contractors' work. In addition, the HWPCF must make contractors aware of the applicable elements of its emergency response plan. The HWPCF screens contractors for those who can perform work on or adjacent to the chlorine process without compromising the safety and health of employees at the facility.
Before allowing a contractor to work on or adja
cent to the chlorine process, the HWPCF must obtain and evaluate information regarding the contractor's safety performance and programs. When a contract involving work on or adjacent to the chlorine process is to be bid, the bidding procedures must ensure that contractor safety management requirements are met. If a contractor is to work in or adjacent to the covered process, before work begins, an on-site contractor orientation on safe work practices, chlorine hazards, and the Emergency Action Plan is held, to make the contractor aware of the HWPCF's RMP/PSM plan requirements. Prior to commencement of work, the contractor will be presented with the Emergency Action Plan, Loss Control Procedures Manual, Line breaking procedure, and description of the chlorination process. Prior to commencement of work, the contractor must certify in writing, and maintain records, that the contractor's employees working on or around the HWPCF chlorination facilities have successfully completed contra
ctor training. Periodic evaluation of contractor safety performance is conducted using the Contractor Evaluation Form. Any violation by a contractor of the HWPCF safe work practices in or around the chlorine area will be immediately reported and followed by an investigation of the violation. Corrective action on the part of the contractor will follow to ensure safe work practices are followed in the future and follow-up evaluations are performed by HWPCF staff to verify the effectiveness of the corrective actions.
A pre-startup safety review must be conducted for any new covered process or for significant modifications to the existing chlorine process that necessitate a change in the process safety information. No new or significantly modified process will start up and no acutely hazardous chemicals will be introduced into such a process prior to the pre-startup safety review. The purpose of the pre-startup safety review is to ensure that the facility is ready
to operate new and modified regulated processes safely.
To initiate the pre-startup safety review, all updated elements of the Process Safety Management Plan are assembled for review. This includes all process safety information, process hazard analysis, operating procedures, employee training and mechanical integrity. The pre-startup safety review team consists of the Project Engineer and Plant Superintendent or Shift Supervisor at the HWPCF. The pre-startup safety review team will compete and sign a Pre-startup Safety Review Form. This form documents the process and helps ensure that the review has been properly performed. The Pre-startup Safety Review Form must be authorized by the Plant Superintendent, and all necessary corrective actions completed and thoroughly documented before startup.
An effective mechanical integrity program is one of the primary preventive measures against a release. The mechanical integrity program also addresses equipment tes
ting and inspection, preventative maintenance schedules, and personnel training. The intent is to ensure that equipment used to process, store or handle chlorine is maintained and installed to minimize the risk of releases.
The HWPCF maintenance staff uses a Critical Equipment List and Maintenance, Inspection and Testing schedule to store equipment information, generate and prioritize work orders, schedule preventative maintenance (PM), provide safety procedures for work orders, and maintain an inventory of parts and materials. The Plant Superintendent maintains records of all critical equipment maintenance activities and maintenance schedules, including inspection and testing. The HWPCF Maintenance, Inspection and Testing schedule generates work orders for preventative maintenance. In addition to preventative maintenance, the HWPCF staff performs corrective maintenance in the event of equipment malfunction or breakdown. The HWPCF mechanical integrity program indicates what safet
y precautions must be followed, including whether lockout/tagout or confined space entry provisions, are applicable. The staff that carry out maintenance are all trained as part of the RMP/PSM.
Hot Works Permits
RMP/PSM regulations require employees and contractors to employ safe work practices when performing " hot work" in, on, or around the chlorine process. To ensure that hot work is done safely, a Hot Work Permit Program has been developed that requires a permit to be issued before hot work is performed. Hot work is defined as the use of oxyacetylene torches, welding equipment, grinders, cutting, brazing, or similar flame- or spark-producing operations.
The process of completing the Hot Work Permit makes it necessary to identify the hazard, recognize what safeguards are appropriate, and then initiate the safeguards necessary to ensure a fire-safe workplace. Following the standards that are outlined in this section aid in complying with the OSHA Hot Works Regulations (1910.2
Management of Change
A system for the proper management of changes and modifications to equipment, procedures, chemicals and processing conditions is required under the RMP/PSM. Modifications to the chlorine system will be reviewed before they are implemented to determine if the modification would compromise system safety. An effective change management system will help minimize the chance for an accidental release.
If a modification covered under RMP/PSM is made, its effects must be addressed, employees must be informed, and the written procedures must be updated. The intent is to require that all modifications to equipment, procedures, and processing conditions other than "replacement in kind" be managed by identifying and reviewing them before implementation. All chlorine operators and maintenance personnel are responsible for understanding what a change is, and will not make a change without implementing a Management of Change procedure and completing Management of C
hange forms. The Maintenance Supervisor or Plant Superintendent will evaluate any modifications that are covered under the RMP/PSM. The Management of Change Form must be completed and submitted in order for the Maintenance Supervisor or Plant Superintendent to review and authorize prior to initiation of a covered change.
Each incident that resulted in or could reasonably have resulted in a release of chlorine must be investigated. A process to identify the underlying causes of incidents and to implement procedures for preventing similar events has been developed. To investigate an incident, an investigation team will be established. As part of the investigation, an incident report will be prepared to recommend system changes.
The investigation team should ask questions such as what equipment failed and which behavior failed. As part of the incident review, staff actions that may have contributed to the incident will also be reviewed. A determination wil
l be made as to whether it is necessary to institute additional training for the employees to prevent the incident from occurring in the future. On the incident report form, the Plant Superintendent (or, in his/her absence, the Senior Crew Leader) identifies which of the recommended system changes are approved for implementation. The incident investigation report, compiled by the Risk Services Analyst or designee, and any changes resulting from the report will be reviewed with all staff members who operate and maintain the applicable system during a monthly safety meeting.
The HWPCF is required to complete a compliance audit for the RMP/PSM program. The primary goals of conducting an internal compliance audit are to gather sufficient data to verify compliance with RMP/PSM requirements and good process safety practices, identify process safety deficiencies, and develop corrective actions, and increase safety awareness among plant staff.
The compliance audit method
ology is modeled after OSHA's guidelines for conducting regulatory PSM compliance audits: Compliance Guidelines and Enforcement Procedures, OSHA Instruction CPL 2-2.45A (September 18, 1995). An internal compliance audit must be conducted at the plant at least once every three years for the chlorine process. A team that has a minimum of three members including: (1) the Plant Superintendent, (2) Crew Leader or other person knowledgeable in the covered processes, and (3) the Risk Services Analyst or designee to serve as the audit leader knowledgeable in RMP/PSM requirements and audit techniques. The audit team will promptly determine an appropriate corrective action for each deficiency identified during the audit. The audit team will prepare an audit report documenting all findings and the corrective actions and the dates by which they must be taken.
Emergency Response Program
The OSHA PSM Process Safety Management regulation, 29 CFR 1910.119(n), and the EPA RMP regulation, 40 CFR
68 Subpart E, require that an accidental release Emergency Response Plan be prepared. The plan must be prepared in accordance with the provisions of another overlapping OSHA regulation - Employee Emergency Plans (29 CFR 1910-38(a)). In addition, provisions of the OSHA hazardous waste and emergency response standard, 29 CFR 1910.120(q) must be considered. MDC's Emergency Action Plan described in this section complies with the requirements of 29 CFR 1910.119(n), 40 CFR 68.95, 29 CFR 1910.38(a), and 29 CFR 1910.120(q).
The Emergency Action Plan provides specific emergency response procedures for accidental releases of chlorine at the HWPCF. The emergency response procedures cover a release from the initial alarm stage through either leak stoppage or HAZMAT assistance. As part of the emergency response procedures, there are plans for victim rescue, leak investigation, and communication with additional support agencies. In addition, critical plant operations are identified to insure
that, if possible, these critical functions are kept operational. The Emergency Action Plan also indicates the level of training needed to carry out the emergency response procedures. Only personnel trained at the Responder Level can attempt to stop a leak. The emergency response procedures refer to "The Metropolitan District Emergency Action Plan for Water Pollution Control Facilities" in cases where plant evacuation is necessary.