Incorporating a New Standardized Strength Customer Class for Improving Equity Among High Concentration Dischargers

In the Butler County Department of Environmental Services (BCDES) wastewater service area, numerous customers contribute extra-strength waste but are not subject to surcharges because they are not part of the industrial permitting program. This policy represents an inequity in that such customers, primarily commercial with a few non-permitted industrial customers, pay the same base volume rate per thousand gallons (kgal) of wastewater discharged as those customers with domestic strength or lower strength waste.To address this inequity, BCDES and its consultant incorporated a customer classification approach suggested in the Water Environment Federation (WEF) Manual of Practice No.27, Financing and Charges for Wastewater Systems. This approach (referred in the manual as the hybrid approach) separates specific types of customers from the commercial and industrial classes based on waste strength data. These customers typically exhibit higher than domestic strength waste. A separate rate per kgal of wastewater discharged was calculated based on the estimated concentrations of chemical oxygen demand (COD), total suspended solids (TSS), ammonia, oil & grease, and total phosphorus (TP) and estimated flows for customers identified as standardized strength.