City of Charleston Wastewater Treatment Plant - Executive Summary |
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The City of Charleston Wastewater Treatment Facility is a municipally owned sewage treatment plant that is permitted to treat up to 14 MGD. Dry weather flows average 11 MGD. The facility uses chlorine to disinfect the wastewater before it is discharged into Kanawha River at Charleston, WV. The Charleston WWTP has a good record of safe handling of chlorine with no major accidental releases ever, and no minor accidental releases in the past five years. The most chlorine ever kept on site is six (6) one ton chlorine containers. These containers are leased from a local chemical supplier (HVC) who reports that they are inspected prior to delivery. The worst case scenario for this facility was calculated using EPA's RMP Guidance for Waste Water Treatment Plants. Our scenario was a gas release of a full one ton container at 200 lbs/min for 10 minutes. Wind speed was 1.5 m/s and the atmospheric stability class was "F". This resulted in a toxic endpoint of 1.3 miles and an estimated ef fected population of 2000 people. The alternate release scenario involved a 1/4 inch hole in the chlorine piping. This resulted in a release rate of 640 lbs/min but atmospheric conditions were assumed to be class D and the wind speed increased to 3.0 m/s. This reduced the toxic endpoint to 0.4 miles and the effected population reduced to 750. The Charleston Sanitary Board was inspected by EPA on August 22, 1994 to determine whether our chlorine handling system was safe or not. EPA commended, in writing, our chlorine safety program which included 1) routine inspections of the chlorine area by operations personnel, 2) training program which includes confined space entry, lock out/tag out, 3) chlorine handling safety training using videos and instructors provided by the chlorine supplier, 4) the purchase of SCBA units and training from the Charleston Fire Department, 5) the availability of Chlorine Repair Kits B for contaier leak repair, and 6) proper operation and maintenance of a c hlorine monitor and alarm system. EPA recommended that we implement the following additions to our program: 1) Consider flexible stainless steel hose for the ton container connections to the manifold instead of rigid tubing, 2) install bollards sto prevent delivery trucks from backing into the containers, 3) attach dated calibration stickers directly onto the chlorine alarm system, 4) conduct a simulated chlorine relase drill with the fire department, 5) provide refresher courses on the use of SCBA units, 6) check the size of the ventillation fan in the chlorine room and change it if necessary, 7) expedite our plans for a preventive maintenance program, 8) develop an emergency response plan, 9) install a windsock. All of these recommendations were implemented except: 1) the use of a flexible connector hose (such piping is not available), 2) simulated emergency drill (we hope to be able conduct a drill as soon as the Fire Department can be available for it). Our current Emergency Res ponse Program calls for our plant operators to immediately respond to a chlorine alarm and make repairs, using the repair kit, as quickly as possible. Once the severity of the leak has been determined, they will call Metro Emergency Services (911) with a check list of information to provide. Metro Emergency Services will determine which emergency responders to deploy including Police, Fire Department and Emergency Medical Technicians. Our personnell are to be trained with refresher courses at least semi-annually on chlorine safe handling and emergency reponse procedures. |