Strategic Process Engineering

Liquid Treatment Processes at the Blue Plains Advanced Wastewater Treatment Plant

Tier 1 WorkshopBlue Plains Users

October 18, 2004

Tier 1 WorkshopBlue Plains Users

October 18, 2004

2

Today’s AgendaToday’s Agenda

•Scope of Strategic Planning•Blue Plains BNR Performance•Planning Issues and Constraints•Policy Issues•Stakeholder Involvement Plan •Wet Weather Treatment Options•Nitrogen Removal Options

•Scope of Strategic Planning•Blue Plains BNR Performance•Planning Issues and Constraints•Policy Issues•Stakeholder Involvement Plan •Wet Weather Treatment Options•Nitrogen Removal Options

3

Current Regulatory Environment - Uncertainty

Current Regulatory Environment - Uncertainty

• Chesapeake Bay Program goals for 2010?• Tributary Strategies released, not yet final

• Maryland – Nitrogen goal of 3 mg/l?

• DC - Nitrogen goal of 7.5 mg/l?

• Virginia - Nitrogen goal of 4 mg/l?

• Long Term Control Plan?• Treat 193 MG tunnel pump out at Blue Plains over 2 days

• Complete Treatment Required?

• Implementation date? (>2010)

• Draft Blending Policy?• Goal to protect biological processes if water quality is met

• May require more stringent permit limits on 001

• Implementation date? (>2010?)

• Chesapeake Bay Program goals for 2010?• Tributary Strategies released, not yet final

• Maryland – Nitrogen goal of 3 mg/l?

• DC - Nitrogen goal of 7.5 mg/l?

• Virginia - Nitrogen goal of 4 mg/l?

• Long Term Control Plan?• Treat 193 MG tunnel pump out at Blue Plains over 2 days

• Complete Treatment Required?

• Implementation date? (>2010)

• Draft Blending Policy?• Goal to protect biological processes if water quality is met

• May require more stringent permit limits on 001

• Implementation date? (>2010?)

4

Need for PlanningNeed for Planning

• Blue Plains now at 90% of capacity• BNR process now degrades during storm flows• Chesapeake Bay Program calls for higher N removal

• Cost effective approach - limit peak flows to BNR

• LTCP Tunnel Pump out increases peak flow duration• Sustained flows at 450 MGD for 2 days after storm• Back to back storms could extend high flows one week• BNR performance will degrade further

• Goals introduce conflicting treatment requirements• BP Users flow management - Ave/Peak Capacity

• Holistic approach to planning is needed

• Blue Plains now at 90% of capacity• BNR process now degrades during storm flows• Chesapeake Bay Program calls for higher N removal

• Cost effective approach - limit peak flows to BNR

• LTCP Tunnel Pump out increases peak flow duration• Sustained flows at 450 MGD for 2 days after storm• Back to back storms could extend high flows one week• BNR performance will degrade further

• Goals introduce conflicting treatment requirements• BP Users flow management - Ave/Peak Capacity

• Holistic approach to planning is needed

5

WASA’s Implementation of Low Cost BNR

WASA’s Implementation of Low Cost BNR

• Use existing tankage

• Operational changes

• Use existing tankage

• Operational changes

• Denit Demonstration

• Full scale BNR @ 7.5

• DC 1st to achieve goal

• Waste Nitrification WAS to Secondary

• Improve process control – Nit/Denit Upgrade contract

• Ongoing DWT Research

• Denit Demonstration

• Full scale BNR @ 7.5

• DC 1st to achieve goal

• Waste Nitrification WAS to Secondary

• Improve process control – Nit/Denit Upgrade contract

• Ongoing DWT Research

6

Monthly Flow into Blue Plains 2001-2004

Monthly Flow into Blue Plains 2001-2004

0

50

100

150

200

250

300

350

400

450

500

Month

0

5

10

15

20

25

Rainfall (inches) TOTAL GW Fairland (relative elevation in feet)

Rainfall (inches)

Total Blue Plains Influent

Groundwater level (feet)

20032002

7

Nitrogen Removal Performance

Nitrogen Removal Performance

Twelve Month Rolling Average Since Full-Scale Denitrification

200

220

240

260

280

300

320

340

360

380

400

J-00M

-00M

-00J-00

S-00N-00

J-01M

-01M

-01J-01

S-01N-01

J-02M

-02M

-02J-02

S-02N-02

J-03M

-03M

-03J-03

S-03N-03

J-04M

-04M

-04J-04

12 Month Period Ending

Pla

nt

Infl

uen

t F

low

(m

gd

)

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

TN

Dis

char

ge,

Mlb

/Yr

Chesapeake Bay Agreement 1985 Total Nitrogen Discharged

Blue Plains Total Nitrogen Discharged 12 Month Plant Influent Average Flow

1985 Total Nitrogen Discharged

Chesapeake Bay Goal8,467,200 lb/Yr

2001 2002 2003 20042000

8

Nitrogen RemovalPerformance

Nitrogen RemovalPerformance

Total Nitrogen DischargeMonthly Average since Full-Scale Denitrification

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

Sep-01 Jan-02 May-02 Sep-02 Jan-03 May-03 Sep-03 Jan-04 May-04

Mo

nth

ly A

vera

ge

TN

Dis

char

ge,

m

g/l

0

50

100

150

200

250

300

350

400

450

Mo

nth

ly A

vera

ge

Pla

nt

Infl

uen

t F

low

(m

gd

)

TN Discharge Monthly Average Plant Influent Flow Monthly Average

2001 2002 2003 2004

9

Performance SummaryPerformance Summary

• Blue Plains has met CBP goals• BNR performance is most influenced by:

• Temperatures

• Groundwater infiltration

• Storm flows

• BUT, peak flows have been limited by:• Construction – lower peak wet weather flows

• Upstream pump station capacity

• ENR Design Challenge:Blue Plains has to handle years with above average rainfall and expected temperature range

• Blue Plains has met CBP goals• BNR performance is most influenced by:

• Temperatures

• Groundwater infiltration

• Storm flows

• BUT, peak flows have been limited by:• Construction – lower peak wet weather flows

• Upstream pump station capacity

• ENR Design Challenge:Blue Plains has to handle years with above average rainfall and expected temperature range

10

Advanced Wastewater Treatment Plant at Blue PlainsRated Capacity 309 MGDRated Capacity 370 MGDRated Capacity 370 MGD with half-plant denitrificationRated Capacity 370 MGD with full plant

denitrification

11

CHALLENGES FOR ENRCHALLENGES FOR ENR

• Blue Plains is at 90% capacity

• Primary clarifier capacity limits performance

• Biological Clarifier capacity also limited

• Full scale BNR has reduced plant safety factor

• New digesters will increase N load to BNR process by 30%

• Pump station rehabilitation will result in higher peak storm flows to Blue Plains

• LTCP tunnel pump out brings higher sustained flows to Blue Plains after the storm event

• Blue Plains is at 90% capacity

• Primary clarifier capacity limits performance

• Biological Clarifier capacity also limited

• Full scale BNR has reduced plant safety factor

• New digesters will increase N load to BNR process by 30%

• Pump station rehabilitation will result in higher peak storm flows to Blue Plains

• LTCP tunnel pump out brings higher sustained flows to Blue Plains after the storm event

12

Blue Plains New Digestion FacilityBlue Plains New Digestion Facility

Existing SolidsExisting SolidsProcessing BuildingProcessing Building

Proposed DigestionProposed DigestionFacilityFacility

13

WASA Needs AnswersWASA Needs Answers

• How does WASA respond to CBP initiatives for higher nitrogen removal? (2010)

• How does WASA achieve LOT for N removal, if a goal and if a permit requirement?

• What facilities are needed to treat combined sewer tunnel pump-out flow? (>2010)

• How does WASA achieve higher levels of treatment for excess flow?

• What are roles of nutrient trading and creative permitting?

• What is the impact of BP User wet weather flow reduction strategies?

• How does WASA respond to CBP initiatives for higher nitrogen removal? (2010)

• How does WASA achieve LOT for N removal, if a goal and if a permit requirement?

• What facilities are needed to treat combined sewer tunnel pump-out flow? (>2010)

• How does WASA achieve higher levels of treatment for excess flow?

• What are roles of nutrient trading and creative permitting?

• What is the impact of BP User wet weather flow reduction strategies?

14

Policy IssuesPolicy Issues

• Treatment level for wet weather flows• Excess flow

• CSS Tunnel pump out

• Peak flow ratio to complete treatment

• Bubble permit for Outfalls 001 and 002

• Blue Plains NPDES Permit• Relative to varying state Tributary Strategies

• TN removal – goal versus permit requirement

• Permit limits – daily, weekly, monthly requirements

• Nitrogen equivalency – still on the table?

• Treatment level for wet weather flows• Excess flow

• CSS Tunnel pump out

• Peak flow ratio to complete treatment

• Bubble permit for Outfalls 001 and 002

• Blue Plains NPDES Permit• Relative to varying state Tributary Strategies

• TN removal – goal versus permit requirement

• Permit limits – daily, weekly, monthly requirements

• Nitrogen equivalency – still on the table?

15

Planning ApproachPlanning Approach

• Define Performance-based alternatives for nutrient levels and wet weather flows

• Define new facilities/costs for alternatives• Define Worst-Case Scenario

• CS tunnel pump out requires complete treatment

• Excess flow requires complete treatment

• Limit of technology for nitrogen removal

• Define cost-effective approaches• Expert Technical Advisory Group• Stakeholder input to focus alternatives

• Define Performance-based alternatives for nutrient levels and wet weather flows

• Define new facilities/costs for alternatives• Define Worst-Case Scenario

• CS tunnel pump out requires complete treatment

• Excess flow requires complete treatment

• Limit of technology for nitrogen removal

• Define cost-effective approaches• Expert Technical Advisory Group• Stakeholder input to focus alternatives

Goal of the Facilities Plan: Identify & define projects for inclusion in the CIP

Goal of the Strategic Plan:Provide WASA with a blueprint to cost-effectively meet regulatory requirements

18

Two-tier Stakeholder Involvement Plan

Two-tier Stakeholder Involvement Plan

• Tier I – Blue Plains Users• BP Technical Committee and Regional Committee

• Loudoun County, invited to BPTC/RC for strategic planning topics

• Tier II – Blue Plains Users and Regulators• DCDOH (nutrient, CSO)

• EPA Region III (nutrient, CSO, capacity)

• EPA CBP (nutrient, CSO, capacity)

• EPA Headquarters (nutrient, CSO, capacity)

• MDE/ MD DNR (nutrient)

• VA DEQ (nutrient)

• Tier I – Blue Plains Users• BP Technical Committee and Regional Committee

• Loudoun County, invited to BPTC/RC for strategic planning topics

• Tier II – Blue Plains Users and Regulators• DCDOH (nutrient, CSO)

• EPA Region III (nutrient, CSO, capacity)

• EPA CBP (nutrient, CSO, capacity)

• EPA Headquarters (nutrient, CSO, capacity)

• MDE/ MD DNR (nutrient)

• VA DEQ (nutrient)

19

Tier 1-Blue Plains User Involvement Provides: Tier 1-Blue Plains User Involvement Provides:

• WASA an opportunity to provide information on technologies, benefits, and costs to the users.

• A forum for BP User input on the process and technical issues and relative merits of the alternatives.

• A forum to discuss the cost and benefits of alternatives and set priorities

• WASA an opportunity to provide information on technologies, benefits, and costs to the users.

• A forum for BP User input on the process and technical issues and relative merits of the alternatives.

• A forum to discuss the cost and benefits of alternatives and set priorities

20

Tier 2 Stakeholder Involvement Provides:

Tier 2 Stakeholder Involvement Provides:

• WASA an opportunity to provide information on technologies, costs and tradeoffs to the regulators.

• WASA with information from the regulatory agencies on acceptability of options.

• A forum to discuss the cost and benefits of alternatives and set priorities.

WASA wants to be proactive in the “creative regulatory” process

• WASA an opportunity to provide information on technologies, costs and tradeoffs to the regulators.

• WASA with information from the regulatory agencies on acceptability of options.

• A forum to discuss the cost and benefits of alternatives and set priorities.

WASA wants to be proactive in the “creative regulatory” process

21

Outreach ActivitiesOutreach Activities

Purpose:

• To inform the public and interested groups.

Target Audience:

• ANCs and environmental groups.Information Available:

• On WASA’s Website

• At public meetings

• Draft Facilities Plan for public review.

Purpose:

• To inform the public and interested groups.

Target Audience:

• ANCs and environmental groups.Information Available:

• On WASA’s Website

• At public meetings

• Draft Facilities Plan for public review.

22

Stakeholder Activities Plan Stakeholder Activities Plan

OctJul Aug Sep Dec Jan Feb Mar Apr May JunNov

2004 20052004 2005

Technical StakeholderWorkshops

Technical StakeholderWorkshops

Technical and Policy StakeholderWorkshops

Technical and Policy StakeholderWorkshops

Public MeetingsPublic Meetings

IntroductoryIntroductory

Draft PlanDraft Plan

Alternatives/costs Draft PlanAlternatives/costs Draft Plan

23

Inputs to WASA’s Decision Making Process

Inputs to WASA’s Decision Making Process

REGULATORS Chesapeake Bay Program

Tributary Strategies

Bay Water Quality Model

NPDES Permitting

REGULATORS Chesapeake Bay Program

Tributary Strategies

Bay Water Quality Model

NPDES Permitting

DC WASADC WASA

Strategic Planning

Facilities

Costs

Pollutant/Nutrient Loads

Strategic Planning

Facilities

Costs

Pollutant/Nutrient Loads

COGNutrient Analysis studies

Nutrient Trading Opportunities

Non-Point Sources of Nutrient

COGNutrient Analysis studies

Nutrient Trading Opportunities

Non-Point Sources of Nutrient

DC WASA BOARD

DC WASA BOARDPUBLICPUBLIC

DiscussionWet Weather Treatment Options

25

POSSIBLE OPPORTUNITIES

POSSIBLE OPPORTUNITIES

Blue Plains has “Overhead”• Wet Weather Flows

• Sludge Digestion Recycles

• Gravity Thickener Overflow

• Filter Backwash

Reducing the “Overhead”Could:• Improve BNR performance

• Reduce future BNR capital cost

• Reduce O&M cost

• Better manage wet weather flows

Blue Plains has “Overhead”• Wet Weather Flows

• Sludge Digestion Recycles

• Gravity Thickener Overflow

• Filter Backwash

Reducing the “Overhead”Could:• Improve BNR performance

• Reduce future BNR capital cost

• Reduce O&M cost

• Better manage wet weather flows

26

Policy IssuesPolicy Issues

• Treatment level for wet weather flows• Excess flow

• CSS Tunnel pump out

• Peak flow ratio to complete treatment

• Bubble permit for Outfalls 001 and 002

• Blue Plains NPDES Permit• Relative to varying state Tributary Strategies

• TN removal – goal versus permit requirement

• Permit limits – daily, weekly, monthly requirements

• Nitrogen equivalency – still on the table?

• Treatment level for wet weather flows• Excess flow

• CSS Tunnel pump out

• Peak flow ratio to complete treatment

• Bubble permit for Outfalls 001 and 002

• Blue Plains NPDES Permit• Relative to varying state Tributary Strategies

• TN removal – goal versus permit requirement

• Permit limits – daily, weekly, monthly requirements

• Nitrogen equivalency – still on the table?

27

Wet Weather FlowsWet Weather Flows

Excess flow & combinedtunnel sewer pump outflow scenarios:• Complete treatment• Equivalent to secondary• Primary

Policy Issues:• What level of treatment

is required?• Can storm peaks to

complete treatment be reduced?

Excess flow & combinedtunnel sewer pump outflow scenarios:• Complete treatment• Equivalent to secondary• Primary

Policy Issues:• What level of treatment

is required?• Can storm peaks to

complete treatment be reduced?

28

Wet Weather FlowsTreatment options

Wet Weather FlowsTreatment options

Compressible Filters

SLUD GE

HYDRO CYC LO NE

POLYMER

INJECTION M ATURATION

PLATE SETTLERW ITH SCRAPER

CLARIFIEDWATER

M ICR OSAND AND SLUDG ETO HYDROCYCLONE

M ICR O-SAND

RAW WATER

COAGULANT

Ballasted Settling

29

CSO Characterization for Tunnel Pump Out

CSO Characterization for Tunnel Pump Out

• Event Mean Concentrations*, mg/l• Total Suspended Solids – 156

• Total Nitrogen – 4.8

• Total Phosphorus – 1.0*Flow weighted, Source: CSS LTCP

Relative TN Loads, Lb/YearCSO Tunnel BP Outfall 00273,500 8,447,000 - 370 mgd @ 7.5 mg/l(untreated) 5,632,000 - 370 mgd @ 5 mg/l

3,379,000 - 370 mgd @ 3 mg/l

• Event Mean Concentrations*, mg/l• Total Suspended Solids – 156

• Total Nitrogen – 4.8

• Total Phosphorus – 1.0*Flow weighted, Source: CSS LTCP

Relative TN Loads, Lb/YearCSO Tunnel BP Outfall 00273,500 8,447,000 - 370 mgd @ 7.5 mg/l(untreated) 5,632,000 - 370 mgd @ 5 mg/l

3,379,000 - 370 mgd @ 3 mg/l

30

Effective Blue Plains2010 Annual TN GoalEffective Blue Plains2010 Annual TN Goal

JurisdictionAllocated IMA

Flows (MGD)

Various State TN Goals (mg/L)

DC 152.5 7.5

WSSC 169.6 3.0

Fairfax 31.0 4.0

Loudoun 13.8 4.0

Other VA 3.1 4.0

Blue Plains 370.0 4.98

31

Alternative Strategies for Additional Nitrogen Removal

Alternative Strategies for Additional Nitrogen Removal

• Alternative Total Nitrogen Discharge from Blue Plains• Current NPDES Permit – 7.5

• Current 2004 Tributary Strategies – 5.0

• Limit of Technology – 3.0

• TN Load to Potomac at 370 mgd

• Alternative Total Nitrogen Discharge from Blue Plains• Current NPDES Permit – 7.5

• Current 2004 Tributary Strategies – 5.0

• Limit of Technology – 3.0

• TN Load to Potomac at 370 mgd

• 23,140 lbs/d 8,447,200 lbs/yr 7.5 mg/l

• 15,430 lbs/d 5,631,600 lbs/yr 5.0 mg/l

• 9,260 lbs/d 3,378,900 lbs/yr 3.0 mg/l

• 23,140 lbs/d 8,447,200 lbs/yr 7.5 mg/l

• 15,430 lbs/d 5,631,600 lbs/yr 5.0 mg/l

• 9,260 lbs/d 3,378,900 lbs/yr 3.0 mg/l

32

Planning for Effluent NitrogenPlanning for Effluent Nitrogen

Alternatives for:• 5 mg/l and 3 mgN/L

Regulatory Issues• Does CSS Tunnel pump out

require complete treatment?• Possible to limit wet

weather peaks <740 mgd?• Impact of bubbles and

nutrient trading• Goal or permit requirement?• Daily, weekly, monthly

permit levels?

Alternatives for:• 5 mg/l and 3 mgN/L

Regulatory Issues• Does CSS Tunnel pump out

require complete treatment?• Possible to limit wet

weather peaks <740 mgd?• Impact of bubbles and

nutrient trading• Goal or permit requirement?• Daily, weekly, monthly

permit levels?

33

Nitrogen Removal OptionsNitrogen Removal Options

• Stay with two sludge system• Optimize primary treatment

• Optimize secondary process to remove TN

• Optimize centrate treatment

• Add nitrification reactor volume

• Convert to a single sludge system• Lowers clarifier overflow rates

• Reliability concerns?

• Add denitrification filters• Reliability – at significant capital cost

• New technologies available to reduce cost

• Stay with two sludge system• Optimize primary treatment

• Optimize secondary process to remove TN

• Optimize centrate treatment

• Add nitrification reactor volume

• Convert to a single sludge system• Lowers clarifier overflow rates

• Reliability concerns?

• Add denitrification filters• Reliability – at significant capital cost

• New technologies available to reduce cost

34

Sludge Digestion Centrate Treatment

Sludge Digestion Centrate Treatment

• Low flow; high ammonia load – increases load to BNR by 30%

• Side stream or main flow treatment options?

• Side stream treatment may:• Save operating cost

• Increase reliability

• Optimize TN removal

• Low flow; high ammonia load – increases load to BNR by 30%

• Side stream or main flow treatment options?

• Side stream treatment may:• Save operating cost

• Increase reliability

• Optimize TN removal

35

Other SidestreamsOther Sidestreams

• Filter Backwash• High “Instantaneous”

Hydraulic Peaks

• Removal of recycle will lower loading to clarifiers

• Gravity Thickener Overflow

• Filter Backwash• High “Instantaneous”

Hydraulic Peaks

• Removal of recycle will lower loading to clarifiers

• Gravity Thickener Overflow

36

Cost Assumptions for Improved Nitrogen Removal

Cost Assumptions for Improved Nitrogen Removal

• Increased wet weather peaks from pump station upgrades

• Digester recycle load adds 30% load to BNR

• LTCP Pump out to complete treatment

• Flows up to 740 mgd for a maximum of 4 hours and up to 511 mgd indefinitely

• Cost estimates are planning level (+50%/-30%)

• Increased wet weather peaks from pump station upgrades

• Digester recycle load adds 30% load to BNR

• LTCP Pump out to complete treatment

• Flows up to 740 mgd for a maximum of 4 hours and up to 511 mgd indefinitely

• Cost estimates are planning level (+50%/-30%)

37

Blue Plains UsersFlow Reduction Strategies

Blue Plains UsersFlow Reduction Strategies

• BP User peak flows above IMA targets

• DC WASA flow reduction plan in place

• BP Users have sewer inspection and correction programs

• Strategic planning will assume that flow reduction programs will bring each user within IMA allocations

• BP User peak flows above IMA targets

• DC WASA flow reduction plan in place

• BP Users have sewer inspection and correction programs

• Strategic planning will assume that flow reduction programs will bring each user within IMA allocations

38

Policy IssuesPolicy Issues

• Treatment level for wet weather flows• Excess flow

• CSS Tunnel pump out

• Peak flow ratio to complete treatment

• Bubble permit for Outfalls 001 and 002

• Blue Plains NPDES Permit• Relative to varying state Tributary Strategies

• TN removal – goal versus permit requirement

• Permit limits – daily, weekly, monthly requirements

• Nitrogen equivalency – still on the table?

• Treatment level for wet weather flows• Excess flow

• CSS Tunnel pump out

• Peak flow ratio to complete treatment

• Bubble permit for Outfalls 001 and 002

• Blue Plains NPDES Permit• Relative to varying state Tributary Strategies

• TN removal – goal versus permit requirement

• Permit limits – daily, weekly, monthly requirements

• Nitrogen equivalency – still on the table?

End of presentationFurther Discussion

40

Overview of Plan Development Process

Overview of Plan Development Process

Ballasted Settling

2 or 1 Sludge System

Centrate Treatment

Denit Filters

Sidestream treatment SWW

Ballasted Settling

2 or 1 Sludge System

Centrate Treatment

Denit Filters

Sidestream treatment SWW

User Capacity Issues

User Capacity Issues

EPA Proposed Rule for Wet

Weather Flows

EPA Proposed Rule for Wet

Weather Flows

Long Term Control PlanLong Term

Control Plan

Chesapeake Bay Program

Chesapeake Bay Program

Real Estate Issues

Real Estate Issues

Wet Weather Treatment

Alternatives

Wet Weather Treatment

Alternatives

Nitrogen Removal

Alternatives

Nitrogen Removal

Alternatives

Increased Capacity

Alternatives

Increased Capacity

Alternatives

Feasibility Review

Feasibility Review

Recommended Facilities and

Costs

Recommended Facilities and

Costs

Processmodel

Processmodel

Capital costsCapital costs

O&M CostsO&M Costs

Ease of Operations

Ease of Operations

41

Average Annual Influent Flows to Blue Plains

Average Annual Influent Flows to Blue Plains

JURISDICTIONS - 12 MONTH ROLLING AVERAGE FLOWS VS

IMA ALLOCATIONS (SHOWN SOLID)

179.424

1.96011.26229.700

152.023

374.369

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

450.0

APRIL 2003 - MARCH 2004

FL

OW

(M

GD

)

BLUE PLAINS WSSC FAIRFAX LCSA OTHER P.I.** USERS

D.C.

31.0

169.6

13.83.1

* 152.5

* - INCLUDES 4.5 MGD

P.I.** RESERVED

370.0

** POTOMAC INTERCEPTOR

42

IMA Allocated Peak FlowIMA Allocated Peak FlowTotal Peak Flow = 1,076 MGDTotal Peak Flow = 1,076 MGD

JURISDICTIONS - HISTORICAL PEAK FLOWS VS

IMA ALLOCATIONS (SHOWN SOLID)

308

33108

521

970

0.0

200.0

400.0

600.0

800.0

1000.0

FL

OW

(M

GD

)

BLUE PLAINS WSSC FAIRFAX LCSA D.C.

71.0

425

32

* - INCLUDES 4.5 MGD

P.I.** RESERVED

1076

** POTOMAC INTERCEPTOR

541

43

Estimated Infiltration and Inflow into Blue Plains

Estimated Infiltration and Inflow into Blue Plains

Based on assumptions for I/I used in the Regional Wastewater Flow Forecast ModelBased on assumptions for I/I used in the Regional Wastewater Flow Forecast Model

0

50

100

150

200

Jun-01 Aug-01 Oct-01 Dec-01 Feb-02 Apr-02 Jun-02 Aug-02 Oct-02 Dec-02 Feb-03 Apr-03

MG

D

D.C. WSSC FAIRFAX LCSA

44

Peak Influent Flow to Blue Plains during Storms

= 1076 MGD

Peak Influent Flow to Blue Plains during Storms

= 1076 MGD

Average Annual Flow = 370 MGD

Average Annual Flow = 370 MGD

Dry Weather Diurnal Peak Flow = 416

MGD

Dry Weather Diurnal Peak Flow = 416

MGD

Infiltration Flow

= 100 MGD

Infiltration Flow

= 100 MGD

Storm Inflow = 560 MGD

Storm Inflow = 560 MGD

45

Daily Average Influent Flow to Blue Plains 2002-2003

Daily Average Influent Flow to Blue Plains 2002-2003

Daily Average Influent Flow - 2002/3

0

100

200

300

400

500

600

700

01/02 05/02 08/02 12/02 04/03 08/03 12/03Date (mm/yy)

Flow

(mgd

)

Average Dry Weather Flow 297 mgdAverage Dry Weather Flow 297 mgd