Multi-Jurisdictional Use Facilities O&M Flow Share Review February 28, 2013 Update with 4 Alternative Approaches

Agreed Issues (TechSc meeting 01/24/2013) Current assumptions regarding District versus Suburban flow ratios are old and not well understood. Unmetered District flow data probably should be updated but additional metering cost should be borne by DC. Costs for Interceptor O & M are relatively low compared to plant and pump station O&M costs therefore a more streamlined approach to allocating MJUF O&M Costs for interceptors would be desirable.

Existing Methodology Current O&M flow calculation estimates DC flow as a % of Suburban flow. D 1 = % of Suburban flow (S) Methodology Alternative No.1 (Cost share Calculated Node to Node) Suburban Flow (S) D1 D2 D… D11 X1 X2 % = D 1 /(D 1 +S) D1 to D11 = DC Catchments = DT D t = P p - S Total District flow between pump station and boundary input Oxon Runs D t = B - (X1 + X2) - S Total District flow between pump station and blue Plain Recommended Methodology The proposed methodology relates each flow component to the total DC contribution in that segment D T. D 1 = % of District Flow (D t ) Watts Branch Pump Stations (P) Blue Plains (B) Poplar Point PS (Pp) CSO % = D t /(D t +S) Anacostia Potomac

Methodology Alternative No.2 (Cost share Calculated per Interceptor) Suburban Flow (S) X1 X2 % = Dt/(Dt+S) D t = P p - S Total District flow between pump station and boundary input Oxon Run D t = B - (X1 + X2) - S Total District flow between pump station and Blue Plains Pump Stations (P) Blue Plains (B) CSO % = D t /(D t +S) Anacostia Potomac District flow discharged directly into Pump Station DC Flow normalized over the length of each interceptor

Methodology Alternative No.3 (Cost share calculated by averaging previous 10-year data and prorating using 2009 BPRFF data Suburban Flow (S) X1 X2 S1 to Sn Oxon Run Pump Stations (P) Blue Plains (B) Anacostia Potomac D i % x D 2009 = D i based on 2009 data S i % x S 2009 = S i based on 2009 data S cost share = S i2009 / (D i S i2009 ) S i % = S n / S t based on past data D i % = D n / D t based on past data ( D t = P-S i ) D 2009 Total district flow in 2009 S i Suburban flow at each route D i District flow at each route S 2009 Total suburban flow in 2009 D cost share = D i2009 / (D i S i2009 ) Same principal as above.

Methodology Alternative No.4 Do Nothing (Except Improve data processing and ensure that all O &M Costs are captured)

Proposed Cost Cost ItemCost Alternative No.1Alternative No.2Alternative No.3 Alternative No.4 Study and Report $217,500.00$187, Flow Metering $242,000.00$128, $0.00 Developing Billing and Reporting Software $41, $0.00 $41,000 Total $500,500.00$316,460.00$187,500.00$41,000.00

Advantage and Disadvantage Alternative No.AdvantagesDisadvantages 1 More accurate and current representation of flows More costly to do study and implement. More administrative work and costs for billing. Longer learning curve. 2 Simple to implement Less costly to do study and implement. Shorter time to learn. Less flow metering than No1 and 4 Less administrative effort for billing. Flows not accounted for as accurately ( Cost share not as accurate ( normalized per route) 3 Simpler to implement than all except No2 Less costly to do study and implement. Shorter time to learn. No Flow metering needed. Almost no administrative effort. Flows not accounted for accurately Cost share not as accurate (normalized per 2009 base flow) 4 No time required for training No study required, only revised billing SOP and software. Shorter time to learn. More administrative work and costs for billing (metering etc) Does not account for new MJUFs