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
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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
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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
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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)
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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
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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)
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)
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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
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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.