City of Terrell - Wastewater Treatment Plant - Executive Summary |
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1.0 REGULATED SUBSTANCES The City of Terrell Wastewater Treatment Plant (WWTP) uses four regulated chemicals, chlorine, sulfur dioxide, methane, and propane, in the treatment and processing of municipal wastewater. Chlorine is used in the disinfection of municipal wastewater. Chlorine is stored prior to and during use in 1-ton containers on an unenclosed, covered, concrete pad. The chlorine is stored as a pressurized liquefied gas, and is released into wastewater using a vacuum-regulated system. The maximum intended chlorine inventory at the facility is 12,000 pounds, which exceeds the RMP threshold quantity of 2,500 pounds. Sulfur dioxide is used in the removal of chlorine from treated wastewater. Sulfur dioxide is stored prior to and during use in 1-ton containers on an unenclosed, covered, concrete pad. The sulfur dioxide is stored as a liquefied gas and released into wastewater using a pressurized system. The maximum intended sulfur dioxide inventory at the facility is 1,200 po unds which does not exceed the RMP threshold quantity of 5,000 pounds. Methane is generated as a by-product of the digestion of organic materials during the wastewater treatment process. The methane is collected for burning in the heat exchanger employed in the digestion process. Methane is present only in the piping between the digester and the heat exchanger. The maximum quantity of methane stored in piping at the facility is approximately 700 pounds, which does not exceed the RMP threshold quantity of 10,000 pounds. Propane is used to supplement methane as a fuels source for the heat exchanger employed in the digestion process. Propane is stored in a 500-gallon (water capacity) tank. The maximum intended inventory of propane stored at the facility is approximately 1,850 pounds, which does not exceed the RMP threshold quantity of 10,000 pounds. 2.0 POLICIES Both toxic and flammable chemicals are used or generated at the facility. Precautions must be taken in order to prevent un necessary exposure to facility personnel and to reduce the threat of accidental release which might result in exposure to the surrounding community and to the environment. It is our policy to adhere to all applicable Federal, State, and industry rules, regulations, and guidelines. Chemical safety at the City of Terrell WWTP is dependent upon strict operating procedures, safe handling methods, and thorough training of employees. Safety devices are also inherent in the design of the facility and in the equipment used in the chemical processes involving toxic and flammable chemicals. 3.0 WORST CASE/ALTERNATIVE CASE SCENARIO ANALYSES INCLUDING ADMINISTRATIVE CONTROLS AND MITIGATION MEASURES TO LIMIT THE DISTANCES FOR EACH REPORTED SCENARIO EPA defines the worst-case scenario as total failure of the largest vessel. The alternative-case scenario is defined as a release that is more likely to occur than the worst case scenario. The alternative-case scenario should also reach an offsite en dpoint, unless no such scenario exists. Chlorine At the City of Terrell WWTP, the worst-case scenario for chlorine would result in a release of 2,000 pounds of chlorine gas. The impact radius would be 1.3 miles and affect 220 persons. Public receptors would include residences and major commercial or industrial areas. There were no environmental receptors within the impact radius. The alternative-case scenario for chlorine would result in a release of 2,000 pounds of chlorine gas. The impact radius would be 0.3 miles and affect 10 persons. There were no other public or environmental receptors within the impact radius. Sulfur Dioxide The worst-case scenario for sulfur dioxide would result in a release of 150 pounds of sulfur dioxide. The impact radius would be 0.2 miles, affecting 10 persons. Public receptors would include residences and major commercial or industrial areas. There were no other public or environmental receptors within the impact radius. The alternative-case scenari o for sulfur dioxide would result in a release of 300 pounds of sulfur dioxide. The impact radius would be 0.2 miles, affecting 10 persons. Public receptors would include residences and major commercial or industrial areas. There were no other public or environmental receptors within the impact radius. Methane The worst-case scenario for methane would result in a release of 700 pounds of methane. The impact radius would be 0.07 miles, affecting 1 persons. There were no other public or environmental receptors within the impact radius. The alternative-case scenario for methane would result in a release of 24 pounds of methane. The impact radius would be 0.02 miles, affecting 0 persons. There were no public or environmental receptors within the impact radius. Propane The worst-case scenario for propane would result in a release of 1,850 pounds of propane. The impact radius would be 0.1 miles, affecting 1 persons. There were no other public or environmental receptors within the impact radius. The alternative-case scenario for propane would result in a release of 1,850 pounds of propane. The impact radius would be 0.06 miles, affecting 0 persons. There were no public or environmental receptors within the impact radius. 4.0 PREVENTION PROGRAM AND CHEMICAL SPECIFIC PREVENTION STEPS The City of Terrell WWTP complies with the EPA's Accidental Release Prevention Rule and with all applicable State codes and regulations. Our facility has taken all the necessary steps to comply with the accidental release prevention requirements under 40 CFR Part 68. The following sections briefly describe the elements of the release prevention program that is in place at our facility. Safety Information The City of Terrell WWTP maintains a detailed record of safety information that describes the chemical hazards, operating parameters, and equipment designs associated with the wastewater disinfection process. Hazard Review Our facility conducts detailed studies to ensure that the haz ards associated with our chlorine and sulfur dioxide processes are identified and controlled efficiently. The studies are undertaken by a team of qualified personnel and are revalidated at least once every five years. Any findings related to the hazard review are addressed in a timely manner. Operating Procedures For the purposes of safely conducting activities within our chlorine and sulfur dioxide processes, the City of Terrell WWTP maintains written operation procedures. These procedures address various modes of operation such as initial startup, normal operations, temporary operations, emergency shutdown, emergency operations, normal shutdown, and startup after a turnaround. The information is regularly reviewed and is readily accessible to operators involved in the processes. Training The City of Terrell WWTP has a comprehensive training program to ensure employees who are operating the chlorine and sulfur dioxide processes are competent in the operations procedures associated with the processes. Maintenance The City of Terrell WWTP conducts regular maintenance checks on process equipment to ensure proper operations. Process equipment examined by these checks includes; pressure vessels, storage tanks, piping systems, relief and vent systems, emergency shutdown systems, controls, and pumps. Maintenance operations are carried out by qualified personnel with previous training in maintenance practices. Any equipment deficiencies identified by the maintenance checks are corrected in a safe and timely manner. Compliance Audit The City of Terrell WWTP conducts audits on a regular basis to determine whether the provisions set out under the RMP rule are being implemented. These audits are carried out at least every three years and any corrective actions required as a result of the audits are undertaken in a safe and prompt manner. Incident Investigation The City of Terrell WWTP promptly investigates any incident that results in, or could reasonably result in a catastrophic release of toxic or flammable chemicals. These investigations are undertaken to identify the situation leading to the incident as well as any corrective actions to prevent the release from reoccurring. All investigation reports are retained for a minimum of five years. 5.0 FIVE YEAR ACCIDENT HISTORY In the past five years, there have been no accidental releases of toxic or flammable chemicals that resulted in deaths, injuries, or significant property damage onsite, or known offsite deaths, injuries, property damage, environmental damage, evacuations, or sheltering in place. 6.0 EMERGENCY RESPONSE PROGRAM The City of Terrell WWTP employees will not respond to a chemical emergency at the plant. As required by 40 CFR Part 68.90, the City of Terrell is included in the community emergency response plan and appropriate mechanisms are in place to notify emergency responders when there is a need for response. 7.0 PLANNED CHANGES TO IMPROVE SAFETY The City of Terrell WWTP will develop and implement required chemical specific operating procedures, training procedures, and maintenance procedures to attain compliance with RMP regulation requirements as well as to ensure the safe operation and mechanical integrity of the RMP regulated processes. |