Tri-Cities North Regional Wastewater Authority - Executive Summary |
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The North Regional WWTP, located at 3777 Old Needmore Rd. in Daytion, Ohio, is operated by USFilter Operating Services (USFOS) for Tri-Cities North Regional Wastewater Authority (TCA) on behalf of the cities of Huber Heights, Vandalia and Tipp City. This facility utilizes two secondary anaerobic digesters for the digestion and stabilization of sludge. Combined, the two secondary digesters have the capability of storing up to 250,000 cubic feet (15,000 pounds--assuming digester gas has a density of 0.06 pounds per cubic foot) of digester gas. USFOS has general policies and procedures for the use of materials and equipment. These policies are provided to give each operating site a general format or structure in which to base Standard Operating Procedures specific to the site. USFOS conducts annual compliance audits at facilities to ensure that safety standards are met and to initiate action to remedy any shortcomings. The methane at the North Regional WWT facility is a Program 1 pr ocess since there are no public receptors within the distance to an endpoint from a worst-case release; the facility has not had any accidental releases within the past five years; and we have coordinated emergency response with the local fire department (local responder). The worst case scenario for the North Regional facility is based on the worst case scenario for methane outlined in the "Risk Management Program Guidance for Wastewater Treatment Plants" (document #EPA550-B-98-010, October 1998). In this scenario, only the pounds of methane gas in a single secondary digester is considered. The methane poundage determination is based on digester gas at the North Regional WWT facility averaging 64% methane at 98 degrees F (average) resulting in a methane density of 0.025 pounds per cubic foot (lbs/cuft). One secondary digester has the storage capacity of 125,000 cubic feet of digester gas, multiplied by the weight of methane (0.025 lbs/cuft) results in 3,158 pounds of methane gas. This scenario presented a toxic endpoint of 0.1 miles (528 feet) which is contained within the property of the North Regional WWT facility. Therefore, no public receptors are affected. An alternative scenario is not required since the methane located at the North Regional facility is a Program 1 process. As part of our operating procedures, the North Regional WWT facility is monitored by a security system that contacts the on-call operator when and alarm is activated. Part of the security system includes methane detectors at the digestion process. |