Strategic Process Engineering Liquid Treatment Processes at the Blue Plains Advanced Wastewater Treatment Plant Tier 1 Workshop Blue Plains Users October 18, 2004 Tier 1 Workshop Blue Plains Users October 18, 2004

2 Today’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 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 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 Use existing tankage Operational changes Use existing tankage Operational changes Denit Demonstration Full scale 7.5 DC 1 st to achieve goal Waste Nitrification WAS to Secondary Improve process control – Nit/Denit Upgrade contract Ongoing DWT Research

6 Monthly Flow into Blue Plains

7 Nitrogen Removal Performance

8 Nitrogen Removal Performance Nitrogen Removal Performance

9 Performance 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 Plains Rated Capacity 309 MGDRated Capacity 370 MGD Rated Capacity 370 MGD with half-plant denitrificationRated Capacity 370 MGD with full plant denitrification

11 CHALLENGES 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 Facility Existing Solids Processing Building Proposed Digestion Facility

13 WASA 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 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 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 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: 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: 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 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 OctJulAugSepDecJanFebMarAprMayJunNov Technical Stakeholder Workshops Technical Stakeholder Workshops Technical and Policy Stakeholder Workshops Technical and Policy Stakeholder Workshops Public Meetings Introductory Draft Plan Alternatives/costs Draft Plan

23 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 WASA Strategic Planning Facilities Costs Pollutant/Nutrient Loads Strategic Planning Facilities Costs Pollutant/Nutrient Loads COG Nutrient Analysis studies Nutrient Trading Opportunities Non-Point Sources of Nutrient COG Nutrient Analysis studies Nutrient Trading Opportunities Non-Point Sources of Nutrient DC WASA BOARD PUBLIC

Discussion Wet Weather Treatment Options

25 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 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 Flows Excess flow & combined tunnel sewer pump out flow 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 & combined tunnel sewer pump out flow 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 Flows Treatment options Compressible Filters Ballasted Settling

29 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/Year CSO Tunnel BP Outfall ,500 8,447, mg/l (untreated)5,632, mg/l 3,379, 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/Year CSO Tunnel BP Outfall ,500 8,447, mg/l (untreated)5,632, mg/l 3,379, mg/l

30 Effective Blue Plains 2010 Annual TN Goal Jurisdiction Allocated IMA Flows (MGD) Various State TN Goals (mg/L) DC WSSC Fairfax Loudoun Other VA Blue Plains

31 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 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 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 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 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 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 Users Flow 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 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 presentation Further Discussion

40 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 EPA Proposed Rule for Wet Weather Flows Long Term Control Plan Chesapeake Bay Program Real Estate Issues Wet Weather Treatment Alternatives Nitrogen Removal Alternatives Increased Capacity Alternatives Feasibility Review Recommended Facilities and Costs Process model Process model Capital costs O&M Costs Ease of Operations

41 Average Annual Influent Flows to Blue Plains

42 IMA Allocated Peak Flow Total Peak Flow = 1,076 MGD

43 Estimated Infiltration and Inflow into Blue Plains Based on assumptions for I/I used in the Regional Wastewater Flow Forecast Model

44 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 Infiltration Flow = 100 MGD Infiltration Flow = 100 MGD Storm Inflow = 560 MGD Storm Inflow = 560 MGD

45 Daily Average Influent Flow to Blue Plains Average Dry Weather Flow 297 mgd