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Tier 1 Workshop Blue Plains Users October 18, 2004

Strategic Process Engineering Liquid Treatment Processes at the Blue Plains Advanced Wastewater Treatment Plant. Tier 1 Workshop Blue Plains Users October 18, 2004. Today’s Agenda. Scope of Strategic Planning Blue Plains BNR Performance Planning Issues and Constraints Policy Issues

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Tier 1 Workshop Blue Plains Users October 18, 2004

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  1. Strategic Process Engineering Liquid Treatment Processes at the Blue Plains Advanced Wastewater Treatment Plant 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

  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?)

  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

  5. 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 WASA’s Implementation of Low Cost BNR

  6. Monthly Flow into Blue Plains 2001-2004

  7. Nitrogen Removal Performance

  8. 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

  10. Advanced Wastewater Treatment Plant at Blue Plains Rated Capacity 370 MGD with full plant denitrification Rated Capacity 370 MGD with half-plant denitrification Rated Capacity 309 MGD Rated Capacity 370 MGD

  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

  12. Blue Plains New Digestion Facility Proposed Digestion Facility Existing Solids Processing Building

  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?

  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?

  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

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

  17. 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)

  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

  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

  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.

  22. Stakeholder Activities Plan Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Introductory Alternatives/costs Draft Plan Technical Stakeholder Workshops Technical and Policy Stakeholder Workshops Draft Plan Public Meetings 2004 2005

  23. Inputs to WASA’s Decision Making Process DC WASA Strategic Planning Facilities Costs Pollutant/Nutrient Loads DC WASA BOARD PUBLIC COG Nutrient Analysis studies Nutrient Trading Opportunities Non-Point Sources of Nutrient REGULATORS Chesapeake Bay Program Tributary Strategies Bay Water Quality Model NPDES Permitting

  24. DiscussionWet 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

  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?

  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?

  28. Wet Weather FlowsTreatment options Ballasted Settling Compressible Filters

  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 TunnelBP Outfall 002 73,500 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 Goal

  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 • 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?

  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

  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

  35. Other Sidestreams • 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%)

  37. 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

  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?

  39. End of presentation Further Discussion

  40. Overview of Plan Development Process Long Term Control Plan Process model Feasibility Review Ease of Operations Real Estate Issues Capitalcosts Wet Weather Treatment Alternatives Ballasted Settling 2 or 1 Sludge System Centrate Treatment Denit Filters Sidestreamtreatment SWW EPA Proposed Rule for Wet Weather Flows O&M Costs Recommended Facilities and Costs Nitrogen Removal Alternatives Chesapeake Bay Program Increased Capacity Alternatives User Capacity Issues

  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 Storm Inflow = 560 MGD Dry Weather Diurnal Peak Flow = 416 MGD Infiltration Flow = 100 MGD

  45. Daily Average Influent Flow to Blue Plains 2002-2003 Average Dry Weather Flow 297 mgd

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