E.H. Huestess Waste Water Treatment Plant - Executive Summary |
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The E. H. Huestess Waste Water Treatment Plant is committed to safety and the implementation of safe procedures through various training, safety, emergency and accidental release prevention programs, and overall process safety management. The City is responsible for the training of all employees at the waste water treatment plant. All new employees are provided training in the following topics, at a minimum: the requirements of Hazard Communication Standard 29 CFR 1910.1200, chemicals used in the plant, how to read and get information from MSDS's, process hazards, use of personal protective equipment, emergency procedures, understanding process safety management, and the location of MSDS's, PSMP, and other safety information. In addition to initial training, employees are trained on various topics related to the facility and its processes once every two weeks. The E.H. Huestess Waste Water Treatment Plant (WWTP) is located in southeast Cayce, adjacent to the Congaree Rive r. The plant currently has a daily process capacity of 8 million gallons per day. The following processes provide both primary and secondary treatment and disinfection: bar screens and grit removal system, activated sludge, disinfectioin using chlorine, dechlorination using sulfur dioxide, pH adjustment using sodium hydroxide, aerobic sludge digestion, and sludge thickening using belt press and drying beds. The following substances (and the maximum quantity stored of each) are used in the treatment processes: chlorine (4000 lbs), sulfur dioxide (4000 lbs), sodium hydroxide (600 gal. - 50% solution), and Clarifloc C-9490 Polymer (300 gal.). Of these substances, only chlorine is held above EPA's threshold level, which is 2500 lbs. Worst case and alternative case accidental release scenarios were determined using EPA's RMPComp. The estimated distance to the worst case release scenario toxic endpoint of 0.0087 mg/L reaches public receptors beyond the property boundaries of the facility. This worst case scenario is the failure of two one-ton chlorine storage tanks, taking into account the passive mitigation measures of dikes, basins, contact chamber and the enclosure of the chlorine storage area. The scenario for the alternative case release was based upon a release which would result from the sheering off of one of the connector pipes which connect the storage cylinder to the manifold. The estimated distance to the alternative case release scenario toxic endpoint of 0.0087 mg/L reaches a single public receptor beyond the property boundaries of the facility, as the WWTP is located in a relatively remote part of the city. This alternative release scenario also takes into account the same passive mitigation measures considered in the worst case scenario. The WWTP currently holds a complete Process Safety Management Plan as required by 29 CFR 1910.119, a Stormwater Pollution Prevention Plan as required under NPDES Permit No. SC0024147, and an Operations and Maintenance manual which outline various procedures involving, training, maintenance, inspections, process safety, process chemical safety information, accident prevention and emergency response procedures. Over the past 5-year period, no accidents have occurred involving the release of any chemicals held above a threshold quantity as defined by 29 CFR 68.130. The WWTP has within its PSM Plan a detailed Emergency Planning and Response Plan outlining coordination with local responders and individual response roles and responsibilities including names, titles and phone numbers. Personnel safety measures and emergency health care responsibilities are also outlined in this plan. Training which includes drills for practice in the event of an emergency release is provided at the time a new employee is hired and is also provided in refresher training courses which are provided at least every three years to current employees. Additional safety training is provided every two weeks on a variety of topics related to processes specific to the plant. |