Multi-Jurisdictional-Use Facilities Flow Analysis Study Update

Presented toBlue Plains Regional Committee

March 24, 2011

District of ColumbiaWater and Sewer Authority

Agenda Original Purpose & Background Review of Modeling Assumptions What Changed?

• Strictly Flow Analysis• Removed all prior agreements (except IMA)• Improved as a Reference function

Cost Implications if adopted

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Purpose & Background

BACKGROUND:• DC Water developing a method to allocate capital

costs among multi-jurisdictional facility (MJUF) users that is proportional to the demands they place on the peak capacity of the facilities

PURPOSE:• To determine each user’s peak capacity as a

percentage of the modeled flow capacity for each major MJUF

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ApproachAnalyze multi-jurisdictional flow routes with the MIKE URBAN model used in developing the Long Term Control Plan for CSO

Determine peak flow conditions using IMA Peak Transmission Limits for suburban users and modeled peak flows for the District

Determine each User’s share of the peak flow, as peak flow rate and as percentage of the modeled peak flow rate, for each segment (node to node) of each MJUF

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MIKE URBAN Model Assumptions Suburban IMA peak flow allocations were introduced as a

constant at the DC boundaries / upstream end of the MJUF

Within the District, modeled peak flows were incrementally added along the route as determined by the sewersheds for the MJUF

For District sanitary sewers – the model predicted peak hourly sanitary flows, base groundwater, I/I and private property stormwater allowances.

For District combined sewers – the model predicted stormwater runoff from a 15-year, 6-hour frequency design storm as well as peak hourly sanitary flows, groundwater and I/I allowances.

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Flow Analysis Report Revisions Report drafted as a flow analysis for the Users to assist for

future capital cost allocations for MJUF CIP• Removed funding considerations from past projects as a constraint

Flow analysis “constraints” limited to IMA allocations and firm pumping capacity of MJUF stations

District flows routed through WSSC and back to the District have been accounted for at the boundary conditions.

Known CIP projects that have or will alter MJUF peak flow in a known capacity have been included (UPI Rehab, etc.)

Increased reference information for ease of use

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Potomac Interceptor (UPIRS) Assignment of Peaks to UsersJurisdiction Sum of Peaks in

IMA (mgd)User share of IMA Total (%)

User share of 151 mgd Design Peak (mgd)

WSSC 83.2 41.7% 62.9

Fairfax 81.2 40.6% 61.4

LCSA 31.9 16.0% 24.1

Other PI Users 3.5 1.8% 2.6

Totals 199.8 100% 151

• IMA allocations total 199.8 mgd for Potomac Interceptor outside of the DC-MD boundary. Design basis for PI and model is 151 mgd at the DC-MD boundary. User %’s proportionate to IMA but volumes based on design basis. 7

Flow Splits ~ WSSCRoute #

Description User Flow Rate (mgd)

Boundary / Upstream %

Downstream %

1 Little Falls Trunk 20.8 65.6% 55.1%2 Upper Potomac Interceptor 23.3 100% 54.9%3 UPIRS (PI in DC) 62.9 (note 1) 41.6% 41.0%4 Rock Creek Main Interceptor 56.6 86.8% 29.5%5 Potomac Force Mains From Route 3 29.8% 29.8%6 B St / NJ Ave From Route 4 29.5% 5.9%7 East & West Outfall From Route 6 9.3% 9.3%

8 Anacostia Force Main 185 93.0% 75.8%

9 Watts Branch & AMI 5.9 100% 12.4%

10 UOX and LOX Sewers 34.8 100% 72.7%

11 East & West Outfall Relief Swrs From Rts 5 & 8 45.8% 45.8%

• Note 1 – 151 mgd design flow apportioned based on IMA peak flow allowances 8

Flow Splits ~ Fairfax & LCSARoute #

Fairfax Flow Route Description User Flow Rate (mgd)

Boundary / Upstream %

Downstream %

2 Upper Potomac Interceptor From Route 3 0% 13.4%3 UPIRS (PI in DC) 85.0 (note 1) 40.6% 25.4%5 Potomac Force Mains From Route 3 18.5% 18.5%11 East & West Outfall Relief Swrs From Rts 5 & 8 12.1% 12.1%

• Note 1 – 151 mgd design flow apportioned based on IMA peak flow allowances; Fairfax Flow includes 23.6 mgd introduced from Chain Bridge

Route #

LCSA Flow Route Description User Flow Rate (mgd)

Boundary / Upstream %

Downstream %

2 Upper Potomac Interceptor From Route 3 0% 3.8%3 UPIRS (PI in DC) 24.1 (note 1) 16.0% 7.2%5 Potomac Force Mains From Route 3 5.2% 5.2%11 East & West Outfall Relief Swrs From Rts 5 & 8 3.4% 3.4%

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How Potomac PS affects MJUF analysis

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PotomacPS

Rock Creek PS

Potomac Interceptor(UPIRS)

Upper Potomac Interceptor (UPI)

Little Falls Trunk Sewer

Rock Creek Main Interceptor (RCMI)

Chain Bridge

Structure 35A

• To B St / NJ Ave Trunk Sewer• To Potomac

Force Mains

Rock Creek PS

Differences in FlowPotomac Interceptor(UPIRS)

Upper Potomac Interceptor (UPI)

Little Falls Trunk Sewer

Rock Creek Main Interceptor (RCMI)

Chain Bridge

Structure 35A

• To B St / NJ Ave Trunk Sewer• To Potomac

Force Mains

PotomacPS

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User 9/10 Report

3/11 Report

WSSC 118.8 mgd 137.1 mgd

Fairfax 73.4 mgd 85.0 mgd

LCSA 31.8 mgd 24.1 mgd

Other PI 7.16 mgd 2.6 mgd

DC 228.8 mgd 211.2 mgd

• Prior report constrained suburban flow at the Potomac Pump Station. Constraint was based on the Potomac Pump Station cost sharing agreement.

MJUF Pump Station ComparisonSept 2010 Report WSSC (%) Fairfax (%) LCSA (%) Other PI

Users (%)DC (%)

Rock Creek PS 36.2% 12.7% 6.7% 1.5% 42.9%Potomac PS 25.8% 16.0% 6.9% 1.6% 49.7%Main & O PS 6.6% 0 0 0 93.4%Poplar Pt PS 13.1% 0 0 0 86.9%

March 2011 Report WSSC (%) Fairfax (%) LCSA (%) Other PI Users (%)

DC (%)

Rock Creek PS 58.3% 13.0% 3.6% 0.4% 24.7%Potomac PS 29.8% 18.5% 5.2% 0.6% 45.9%Main & O PS 9.3% 0 0 0 90.7%Poplar Pt PS 13.1% 0 0 0 86.9%

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CIP Implications of MJUF Current CIP Projects with identified MJUF

$395M

Future CIP Projects to be added from Facilities Plan with identified MJUF$144M

Summary does not include SLRP projects (locations prioritized based on site rankings)

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Current CIP for Multi-Jurisdictional Analysis

Projects CIP Budget ($M)

Projects w/ Prior Agreements $ 87.2 MProjects w/ Construction Completed $ 2.7 MProjects in Construction $ 72.4 MBPIS Rehab Project $ 56.0 MProjects in Planning / Design $ 177.2 M

Totals $ 395.0 M

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• $233 M

D201 – BPIS Rehab Flow AnalysisJurisdiction % Based on

Sept 2010 Report

Funding Based on Sept 2010 Report ($ M)

% Based on March 2011 Report

Funding Based on March 2011 Report ($ M)

DC 83.4% $46.7 M 84.6% $47.4 M

WSSC 15.1% $8.5 M 14.0% $7.8 M

Fairfax 0.94% $0.52 M 1.1% $0.61 M

LCSA 0.41% $0.23 M 0.31% $0.17 M

Other PI Users

0.09% $0.05 M 0.04% $0.02 M

Totals 100.0% $ 56.0 M 100.0% $56.0 M

• $56.0 M is project total budget including design, cm and construction 15

Upcoming MJUF CIP – $177 MJurisdiction % Based on

Sept 2010 Report

Funding Based on Sept 2010 Report ($ M)

% Based on March 2011 Report

Funding Based on March 2011 Report ($ M)

DC 66.9% $118.5 M 65.3% $115.6 M

WSSC 29.3% $51.9 M 31.5% $55.8 M

Fairfax 2.4% $4.3 M 2.5% $4.4 M

LCSA 1.1% $1.9 M 0.7% $1.2 M

Other PI Users

0.24% $0.43 M 0.08% $0.14 M

Totals 100.0% $ 177.1 M 100.0% $177.1 M

• For the 10-year CIP, includes identified locations and budgets for MJUF projects in planning and design; not including PI

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Next Steps User review of revised Flow Analysis Tech

Memo for acceptance as a reference

Develop SOP for cost allocations for MJUF CIP projects

Update User CIP cost allocations based on SOP

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