DESIGNING AND COMMISSIONING AN ULTRAVIOLET LIGHT DISINFECTION SYSTEM TO MEET NATIONAL WATER RESEARCH INSTITUTE GUIDELINES AT WARDEN, WASHINGTON

摘要

The City of Warden, Washington, (City) previously operated a municipal wastewater treatment and disposal system that consisted of a three-cell facultative lagoon system and a sprayfield. As the treatment and disposal facilities were reaching capacity, the State of Washington (State) had begun to apply its groundwater quality standards and drinking water standards to the operation of the sprayfield disposal system under the City's State Waste Discharge Permit. The State's groundwater (GW) quality standards are equal to or more stringent than drinking water (DW) standards in order to protect groundwater as a drinking water source. Parameters of interest that are regulated under the State's groundwater and drinking water standards include nitrate (10 mg/L limit under both GW and DW standards), total coliform bacteria (1 cfu/100 mL under both GW and DW standards) and trihalomethanes (80 μg/L under the DW standards).