Operation and Maintenance Cost Allocation Study for Multi-Jurisdictional Use Sewers

The District of Columbia Water and Sewer Authority (DC Water) charges suburban jurisdictions annually for the operation and maintenance (O&M) of jointly used sewer system facilities, known as Multi-Jurisdictional Use Facilities (MJUFs). The current procedure used by DC Water to determine flow shares for billing O&M costs to suburban jurisdictions contains formulae and methodologies developed more than 15 years ago. The rationale used to develop the current procedure is not documented, and as a result, the procedure for determining flow shares is not well understood by DC Water, Washington Suburban Sanitary Commission (WSSC), or the other suburban jurisdictions. Additionally, the 2011 MJUF Capital Cost Allocation Study identified new MJUFs and the 2012 Blue Plains Intermunicipal Agreement (IMA) led to recognition of a need to update the process and methodology used to calculate O&M costs for MJUFs on an annual basis.Each jurisdiction's flow share for determining O&M costs is based on the annual average flow discharged into MJUF sewers. Flow from suburban jurisdictions is metered at or near the District's boundaries. Flow from District sewersheds into MJUF sewers is not metered. Currently, District flows are estimated as fixed percentages of associated annual upstream metered suburban flows. This method of estimating District sewershed flows is not ideal, because it is completely dependent upon suburban flow. A new procedure for estimating District flows into MJUFs independent of suburban flows and associated cost allocation is needed.