Briefing on

IMA Negotiation Issues

Presented to:

Blue Plains IMA Negotiating TeamOperating Agency Work Group

March 11, 2010

District of Columbia

Water and Sewer Authority

1

2

Items to be Resolved O&M Cost

Joint use CSO facilities· CSO tunnels· Portions of Blue Pains Tunnel & Tunnel Dewatering Pumping Station

TN Facilities· Enhanced Clarification Facility (ECF)· Blue Plains Tunnel

Flow Allocation Does captured combined sewage count against D.C.

flow allocation? Assessment of flows for comparison against allocations

3

Sewer/Treatment System Overview

Potomac Tunnel

ECF

Jurisdictional Meters

Sewer system

BP Complete Treatment

Piney Br. Tunnel

Anacostia & Blue Plains Tunnel

DC

Lin

e

TDPS 001

002RWWPS

DCPeak flow reduction diversions to tunnel

Volume

Flow Rate

Information SourcesIt is not possible to explicitly meter how much of each jurisdictions flow ends up in each treatment system

(complete treatment vs ECF)

4

Agreed Capital Cost Allocation

Complete Treatment

Enhanced Clarification

Facility

Sewer System

1076 mgd

521 mgd

Tunnel Dewatering Pumping Station

225 mgd total

31 mg added for ENR

Outfall 002

Outfall 001

126 mg for CSO

170 mgd for CSO(7.1% suburbs per

LTCP split)

55 mgd added for ENR(60% suburbs per IMA

370 split)

225 mgdNot needed for CSO

Needed for ENR

555 mgd

157 mg total tunnel storage

Bolling Diversion Str. Centrate Treatment

New TN facilities

Blue Plains Tunnel 73 mg

Anacostia River & Northeast Boundary Tunnels - 84 mg

42 mg

(60% suburbs per IMA 370 split)

(60% suburbs per IMA 370 split)

(60% suburbs per IMA 370 split)

(60% suburbs per IMA 370 split)

126 mg for CSO(7.1% suburbs per

LTCP split)

5

O&M Cost for Joint Use CSO Facilities Joint use CSO facilities:

Anacostia, Northeast Boundary, Potomac & Piney Branch Storage Tunnels 42/73 of Blue Plains Tunnel (CSO portion) 170/225 of Tunnel Dewatering Pumping Station (CSO Portion) Other appurtenant CSO facilities (enumerated during CAO negotiation)

Past practice: base cost on actual measured volume entering tunnel for each jurisdiction

It’s not possible to measure volume by jurisdiction for DC or suburbs because flows are mixed

Alt Description Rationale Considerations

1Model it every year Accounts for year to year variations

• Costly & burdensome• Significant year to year

variations

2Use average year (7.1%)

• 7.1% is “difference in Annual Volume Exceeding Treatment Capacity in Average Year (Annual CSO Overflow Volume)”

• This is volume in tunnels

• Simple• Year to year variations will be

incorrect, but overall average will be correct

Additional item to be addressed: How will suburbs split up the 7.1 % of CSO costs – based on 370 mgd?

Est. O &M approx $6 M/yr

6

CSO Projects Determined to Be Joint Use During CAO NegotiationsProject Title

CY00 Anacostia CSS Facility PlanCY07 Special Counsel AssistanceCY08 Office Trailer Setup, (Trailer Offices for Anacostia Facility Plan)CY11 Anacostia CSS Facility Plan PM & Tech SupportCY12 Div H - Anacostia River TunnelCY13 Div I - Main Pumping Sta. DiversionsCY14 Div J - Northeast Boundary TunnelCY20 CSS NMC Project Impact AssessmentCZ00 Potomac CSS LTCP Facility PlanCZ01 Potomac Tunnel SegmentCZ02 Potomac Dewatering PumpCZ03 Potomac Outfall ConsolidationDZ00 Rock Creek CSS LTCP Facility PlanDZ01 Rock Creek CSS LTCP ProjectAV02 CSO Program ManagementK001 Replacement of CSO FabridamsK201 CSO - Long Term Control PlanK202 CSS LTCP Litigation CostBK01 CSO Event Indicators

7

O&M Cost for New TN Facilities

New TN Facilities: Enhanced Clarification 55/225 of Tunnel Dewatering Pumping Station 31/73 of Blue Plains Tunnel Bolling Diversion Structure

8

O&M Cost for New TN Facilities

Alt Description Rationale ConsiderationsCalc based on ECF O&M =

$2.3M/avg yr

1

Base on total volume delivered to Blue Plains

• All of ECF pollutant removal, storage & pumping is required for TN removal

• Suburbs = jurisdictional meter volume• DC = (001+002) minus suburban volume

• Consistent with why facilities are being built (CAO negotiation)

• Simple

• Suburban = 60% x $2.3M = $1.4M

• DC = 0.4*$2.3 = $0.9M

2

Use model to estimate how much of treated volume thru ECF is:• Due to peak

reduction• Due to CSO

Estimate about 50% of volume thru ECF is due to peak flow reduction in avg yr

• Ignores pollutant removal provided by ECF – the basis for approval of TN plan

• Costly & burdensome

50% of cost ($1.15M) due to peak flow reduction• Suburban cost = 60% x

$1.15M = $0.7M50% of cost is due to CSO• Suburban cost = 7.1% x

$1.15M = 0.08M

Tot. Suburban Cost = $0.78MDC Cost = $1.52M

3 Measure it

• Use jurisdictional meters to calculate volume of flow in a year which is between 1.5 peaking factor and 2.0 peaking factor

• Install flow meters at two major diversions to tunnel where peak reduction to BP will occur. Measure total volume into tunnel due to peak reduction.

• DC Volume = Total Volume – Suburban Volume

• Ignores pollutant removal provided by ECF – the basis for approval of TN plan

• Ignores flow routing of suburban flows (just because suburban flow exceeded 1.5 peaking factor doesn’t mean it ended up in tunnel)

9

Does Captured Combined Sewage count against DC’s Flow Allocation?Alt Description Rationale Considerations

1

Captured Combined Sewage counts against D.C’s allocation Plant is treating the flow

• Simple• Ignores design basis for plant

2

Captured Combined Sewage does not count against D.C’s allocation

• Plant is required to maximize treatment

• No additional facilities were built to treat captured wet weather flow per Blue Plains Feasibility Study

• Use nomograph generated from model to estimate captured combined sewage once per year

• Subtract captured combined sewage from total influent flow when calculating DC’s annual average flow

10

Example Captured Combined Sewage Nomograph

Currently estimate about 15 mgd of captured combined sewage is treated at Blue Plains in an average year. Estimate this will increase to 21 mgd after LTCP in place (net increase of 6 mgd)

11

D.C. Flows from 1999-2009 With and without Captured Combined Sewage

Impact of Captured Combined Sewage (CCS) on Allocation in Average Year

(Estimated for Discussion Purposes with Regard to Offloading)

1. Assumes D.C. flows remain at 133 mgd, excluding captured combined sewage2. Actual total D.C. flows from 2005-2009 have averaged 143.9 mgd (including captured combined sewage)

Current Conditions Future Conditions (After LTCP)

User

1985 IMA

Alloc. (mgd)

001 CCS

(mgd)

002 CCS

(mgd)

Total CCS

(mgd)001

Total

002 Total (mgd)

001 + 002 Volume if

CCS Counts Against

Allocation (mgd)

001 + 002 Volume if CCS Does Not Count

Against Allocation

(mgd)

001 due to Peak Flow Reduction (2.0 to 1.5)

(mgd)

001 CCS

(mgd)

002 CCS

(mgd)

Total CCS

(mgd)001

Total

002 Total (mgd)

001 + 002 Volume if

CCS Counts Against

Allocation (mgd)

001 + 002 Volume if

CCS Does Not

Count Against

Allocation (mgd)

District 148 2.6 12.4 15 2.6 145.4 148.0 133.0 1.46 3.65 17.35 21 5.11 148.9 154 133

WSSC 169.6 169.6 169.6Fairfax County 31 31 31PI Users 0

Loudoun 13.8 13.8 13.8Vienna 1.5 1.5 1.5Dulles 1.5 1.5 1.5Navy 0.07 0.07 0.07NPS 0.03 0.03 0.03Reserved for Future PI Users 4.5 4.5 4.5

Sum of Suburbs 222 222 222 2.19 2.19 219.8 222 222

Total 370 370 355 3.65 3.65 17.35 21 7.3 368.7 376 355

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Evaluation of Flows for Comparison Against Allocations in IMA

Alt Description Rationale Considerations

1

Base allocation on 001 + 002 Volume

• Suburban Flow = measured by jurisdictional meters

• DC Flow = 001+002 flow minus Suburban Flow minus Captured Combined Sewage

• Simple• Allocation is based on 370 mgd in 002.• No jurisdiction is specifically allocated flow

in 001. Outfall 001 is the safety valve for the system. All jurisdictions use Outfall 001 to accommodate wet weather flows to the degree necessary.

Add language to flow management sections of IMA requiring stewardship of plant capacity regarding control of infiltration and inflow

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Example Calculation – Average Year

002 Flow = 368.7 mgd

001 Flow = 7.3 mgd

Total flow = 376 mgd

Suburban meters = 222 mgd

DC flow = 376-222 = 154 mgd Subtract captured combined sewage for D.C. allocation comparison: 154 – 21 = 133 mgd DC flow

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Example Calculation – Very Wet Year (60” rain, based on 2003, extra 65 mgd of I/I in system)

002 Flow = 435 mgd

001 Flow = 17.4 mgd

Total flow = 452 mgd

Suburban meters = 261 (222 + 60% x 65 mgd I/I)

DC flow = 452-261 = 191 mgd Subtract captured combined sewage for D.C. allocation comparison: 191 – 25 mgd = 160 mgd DC flow (close to 133 + 40% x 65 mgd I/I)

16

Impact of 2003 (60” Rain) on Jurisdictional Flows

100

110

120

130

140

150

160

Jan-

99

Sep-

99

May

-00

Jan-

01

Sep-

01

Jun-

02

Feb-

03

Oct

-03

Jun-

04

Feb-

05

Nov

-05

Jul-0

6

Mar

-07

Nov

-07

Aug

-08

Apr

-09

Flow

(mgd

)

WSSC Flows (12 Month Rolling Average)

153-124 = 29 mgd Increase in 2003

15

17

19

21

23

25

27

29

31

Jan-

99

Sep-

99

May

-00

Jan-

01

Sep-

01

Jun-

02

Feb-

03

Oct

-03

Jun-

04

Feb-

05

Nov

-05

Jul-0

6

Mar

-07

Nov

-07

Aug

-08

Apr

-09

Flow

(mgd

)

Fairfax Flows (12 Month Rolling Average)

30-27.5= 2.5 mgd Increase in 2003

0

2

4

6

8

10

12

14

16

Jan-

99

Sep-

99

May

-00

Jan-

01

Sep-

01

Jun-

02

Feb-

03

Oct

-03

Jun-

04

Feb-

05

Nov

-05

Jul-0

6

Mar

-07

Nov

-07

Aug

-08

Apr

-09

Flow

(mgd

)

Loudoun Flows (12 Month Rolling Avg)

100

110

120

130

140

150

160

170

180

190

Jan-

99

Sep-

99

May

-00

Jan-

01

Sep-

01

Jun-

02

Feb-

03

Oct

-03

Jun-

04

Feb-

05

Nov

-05

Jul-0

6

Mar

-07

Nov

-07

Aug

-08

Apr

-09

Flow

(mgd

)

D.C. Flows (12 Month Rolling Average)

Total D.C. Flow

D.C. Flows Minus Cap. Comb Sewage Calculated Using Nomograph

180-155 = 25 mgd Increase in 2003

17

Summary of Recommendations

No. Issue Recommendation

1

O&M cost of Joint Use CSO Facilities• CSO Tunnels• Portions of Blue Plains Tunnel

and Tunnel Dewatering PS

2

O&M cost of TN facilities• ECF• 31 mg of Blue Plains Tunnel

3

Does Captured Combined sewage count against D.C. flow allocation?

4

Evaluation of Flows for Comparison against Allocations in IMA

• Suburban flow = from jurisdictional meters• DC flow = (001+002) – Suburban flow- Captured Combined Sewage• Allocate based on 370 mgd• No jurisdiction is specifically allocated flow in 001. Outfall 001 is the

safety valve for the system. All jurisdictions use Outfall 001 to accommodate wet weather flows to the degree necessary.