Synergy: Addressing Combined Sewer Overflows and Nitrogen

Transcription

1 District of Columbia Water and Sewer Authority Briefing on Synergy: Addressing Combined Sewer Overflows and Nitrogen to Anacostia Steering Committee August 27,

2 Introduction Background Addressing combined sewer overflows (CSO) Challenges for Enhanced Nitrogen Removal Synergy: Need for Integrated LTCP Plan and Total Nitrogen Removal Planning Summary

3 What is WASA? Independent Authority formed in 1996 Formerly Water and Sewer Utility Administration (WASUA) under Dept. of Public Utilities Services Provided Water Distribution Wastewater Collection and Treatment Serves District Parts of Maryland & Virginia Anacostia River in the District of Columbia Massive capital program that will improve water quality in the Potomac River, Anacostia River and Rock Creek 3

4 Blue Plains Advanced Wastewater Treatment Facility Serves over 2 million people in DC, MD, VA Largest advanced wastewater treatment plant in the world 370 million gallons per day average annual capacity Services combined & separate sewer system Excellent history of treatment performance (won annually the National Association of Clean Water Agencies Gold Peak Performance Award 8 times) Blue Plains Advanced Wastewater Treatment Facility 4

5 Blue Plains Service Area Blue Plains Wastewater Treatment Plant 5 5

6 Separate and Combined Sewer Systems 2 2 pipes 1 pipes 1 pipe pipe 100% of suburbs 66% of District of Columbia 0% of suburbs 33% of District of Columbia 6

7 Combined Sewer System Maryland District of Columbia Potomac N Rock River Creek Combined Sewer Area Maryland District of Columbia Anacostia River District of Columbia Maryland 1/3 area is combined (12,478 ac) 53 CSO outfalls 15 to Anacostia 10 to Potomac 28 to Rock Creek Potomac River Blue Plains Treatment Facility 7

8 Location of Anacostia CSOs 8

9 Why are CSOs a Concern? Can adversely affect quality of receiving waters Primary concerns: Bacteria levels Contribute to low dissolved oxygen in water Potential for fish stress or fish kills Affects other aquatic life Aesthetics - contributes to trash on waterways CSO 017 to Anacostia River during Hurricane Floyd 9

10 How is the District of Columbia Water and Sewer Authority Addressing CSOs? Near Term 40% CSO reduction by 2009 over 1996 levels Approx $170M mix of projects: pumping station rehabilitations inflatable dams replacement Long Term Implement comprehensive Long Term Control Plan (LTCP) Includes vast underground tunnel system that stores and conveys flows to expanded treatment facility 96% CSO reduction by 2025 over 1996 levels; 98% CSO reduction for the Anacostia River 10

11 Separate Luzon Valley Piney Branch Storage Tunnel Rock Creek Regulator Improvements Maryland D.C Rock Creek Low Impact Development- Retrofit at WASA facilities F Storage Tunnel Potomac River Potomac Storage Tunnel Rehab Potomac Pumping Station $ 2.2+ billion cost P Rehab Main & O Pumping Stations 96% reduction in CSO volume (98% on Anacostia) 20 year implementation ( ) Combined Sewer Area P P P F D.C. P Maryland Anacostia River Improvements to Excess Flow at Blue Plains Rehab Eastside Pumping Station Abandon Northeast Boundary Swirl Ft. Stanton CSO Pipeline Tunnel Dewatering P.S. Replace Poplar Point P.S. CSO Control: Final LTCP 11

12 How is WASA Addressing CSOs? Item Completed CSO Controls Pumping Station Rehabilitations on Anacostia Inflatable Dams Northeast Boundary Swirl Facility Netting System at CSO 018 Anacostia River Floatable Debris Removal Program Excess Flow Treatment at Blue Plains Tide Gate replacement Catch Basin Cleaning CSO Controls Being Implemented Pumping Station Rehabilitations on Potomac Long Term Control Plan (LTCP) Anacostia River Primary Benefit to: Potomac River Rock Creek 12

13 Typical Inflatable Dam 12 Inflatable dams at 8 locations (7 dams on Anacostia River) Replaced in % reduction in CSO by volume Courtesy of Bridgestone 13

14 Screening at Northeast Boundary Swirl Facility Treats CSO from largest drainage area in District (4000 ac+) Located near RFK Stadium\ Recent monitoring showed that about 85% of CSO at Northeast Boundary is treated by Swirl Swirl includes screens which remove trash Will be replaced by overflow facility when tunnel is constructed Northeast Boundary Swirl Facility 14

15 Solids and Floatables Demonstration Projects at CSO 018 to Anacostia River Demonstration project on Anacostia River to remove solids and floatables Operational since April 2000 Removes lbs/event 15

16 Anacostia River Floatable Debris Removal Program Continuing Program Remove about 400 tons/year Works cooperatively with U.S. Army Corps of Engineers 16

17 Tide Gate Replacement on Anacostia River Keeps river water out of sewer system Reduces extraneous water treated at Blue Plains CSO 005 Tide Gate Cross Section Thru CSO 005 Outfall 17

18 Performance: CSO Reduction Item Anacostia River Potomac River Rock Creek Total CSO Overflow Volume (mg/yr) WASA formed 2,142 1, , After Inflatable Dams & Pump Station rehab 1, , Complete LTCP in Place % Reduction 98% 93% 90% 96% # of Overflows/Average Year WASA formed After Inflatable Dams & Pump Station rehab Complete LTCP in Place / 4 1 Notes: 1. One overflow/avg. yr at Piney Branch (major CSO), 4 overflows/avg. yr at other small Rock Creek CSOs 18

19 CSO Control: What are the Benefits of LTCP? 1 CSO CSO Reduction 96% 96% Reduction: in in CSO CSO Volume Volume # # of of Overflows Reduced: Anacostia from from 2,142 2,142 to to mil mil gal/yr gal/yr Potomac from from 1,063 1,063 to to mil mil gal/yr gal/yr Rock Rock Creek from from to to 5 mil mil gal/yr gal/yr Anacostia from from to to 2/yr 2/yr Potomac from from to to 4/yr 4/yr Rock Rock Creek from from to to 4/yr 4/yr 98% reduction 2 Water Water Quality Quality Improvement Bacteria levels levels will will be be lower, lower, dissolved oxygen oxygen will will be be higher higher 3 Trash Trash Reduction Trash Trash from from CSOs CSOswill will be be practically eliminated 4 Flooding Relief in Northeast Boundary Area Flooding Relief in Northeast Boundary Area 19

20 Separate Luzon Valley (completed) Piney Branch Storage Tunnel Rock Creek Regulator Improvements Maryland D.C Rock Creek Low Impact Development- Retrofit (Multiple Sites throughout District) F P Known Flooding Problem Pumping Station Separate CSO 031, 037, 053 and 058 F Storage Tunnel Potomac River Potomac Storage Tunnel Rehab Potomac Pumping Station P Combined Sewer Area F P Anacostia River Abandon Northeast Boundary Swirl LTCP: LTCP: $ $ Billion Billion Nitrogen Nitrogen Removal: Removal: $950 $950 M Total Total > > $ $ 33 Billion Billion yr yr implementation implementation ( ) ( ) 96% 96% reduction reduction in in CSO CSO P P P P D.C. Maryland Enhanced Clarification Treatment & Nitrogen Removal at Blue Plains Separate CSO 006 Replace Poplar Point Pumping Station Tunnel to Blue Plains Tunnel Dewatering P.S. CSO and Nitrogen Removal 20 Programs

21 N McMillan Reservoir Anacostia River Projects Facility Plan: Key Facilities Poplar Point Pumping Station Potomac River Nationals Stadium Anacostia River RFK Stadium Tunnel to Blue Plains Anacostia River Tunnel Tunnels Shafts Diversions Tunnel Overflows Diversion Sewers Blue Plains 21 21

22 Tunnels Constructed by Tunnel Boring Machine 22

23 Tunnel Depth 23

24 Anacostia River Projects Facility Plan: Geotechnical Investigations Alignment alternatives evaluated during boring program 24

25 Construction Complete 2018 N RFK Stadium In operation by 2025 BPT (Blue Plains Tunnel) Nationals Stadium In operation by 2018 ART (Anacostia River Tunnel) Anacostia River Anacostia River Tunnel CSO Diversions I-295 Potomac River Tunnel to Blue Plains Blue Plains AWWTP 25

26 Construction Complete 2025 NEBT (Northeast Boundary Tunnel) Branch Tunnels R Street 1 st NW Rhode Island Ave. CSO Diversions 26

27 Sources of Nitrogen Loads to the Bay (Average Rainfall Year) Blue Plains is less than 2% of the estimated Total Nitrogen load to the Bay Wastewater Treatment Plants 19% Agriculture (Manure & Fertilizer) 34% Urban/Suburban Runoff (Chemical Fertilizer, etc) 10% Septic 4% Air Deposition 33% DC s CSOs are less than 0.05% of the estimated Total Nitrogen load to the Bay Source: Chesapeake Bay Program Phase 4.3 Watershed Model, data from: 27

28 Synergy with Other Programs: Nitrogen Removal Requirements LTCP was developed prior to nitrogen removal requirement at Blue Plains TN removal was a goal equivalent to about 7.5 mg/l No effluent limit April 2007 New TN permit limit added to NPDES Permit Hard annual cap effluent limit equivalent to about 4.16 mg/l TN WASA considered many alternatives By modifying the approach to treating wet weather flows, WASA could economically combine TN removal and wet weather treatment 28

29 Synergy with Other Programs: Nitrogen Removal Options Conventional Regulatory Approach Innovative Regulatory Approach High cost to provide BNR for this flow rate Complete Treatment ENR Blue Plains 370 mgd annual avg 740 mgd Peak Factor = mgd 336 mgd Excess Flow Treatment, Plain Settling, Add 4 Primary Tanks, $22 M Reducing peak flow to BNR reduces cost Complete Treatment ENR Blue Plains 370 mgd annual avg 555 mgd Peak Factor = mgd 521 mgd Transfer more wet weather flow to new technology 31 mg of storage 225 mgd Enhanced Clarification Proprietary Process, $239M Outfall 002 $1,435 M Cost Disbursement dollars Outfall 001 Outfall 002 $950 M Cost (Disbursement dollars) Outfall 001 Improve effluent quality so total pollutant loads are less than conventional approach Selected as WASA s Plan 29

30 Synergy with Other Programs: TN Removal Plan N McMillan Northeast Boundary Tunnel Extend tunnel by 3.5 miles: 23 feet diameter 1.5 miles of 3.5 miles holds 31 mg sewage for peak flow reduction at Blue Plains 2 miles of 3.5 miles is extended LTCP tunnel without increase in total LTCP tunnel volume (126 mg) Construct at Blue Plains: Nitrogen removal facilities Enhanced Clarification Facility (ECF) Tunnel Dewatering pumping station Main & O Branch Tunnel National s Stadium Potomac River Anacostia River RFK Stadium Anacostia River Tunnel Poplar Point Blue Plains Tunnel BP Tunnel Dewatering Pump Station Blue Plains ENR Enhanced Clarification 30

31 Synergy with Other Programs: Benefits Save rate payers more than $500 M Lower pollutant loads to Potomac River, better water quality Improves water quality sooner on Anacostia. Achieves LTCP level of CSO control on Anacostia by 2018 instead of 2025 Savings would not be possible without willingness to: Consider changing LTCP (changing consent decree) Propose innovative regulatory approach 31

32 Blue Plains Nutrient Removal History Before no nitrification / denitrification nitrification process started 1996 Pilot tested performing denitrification in same basins as nitrification 1999 Full scale operation of denitrification in same basins as nitrification Met Chesapeake Bay goal of 40% reduction by 2000 over 1985 levels Goal was million lbs/yr or 7.5 mg/l Optimizing existing facilities No new tankage constructed Innovative design April Permit modified to add TN removal requirement million lb TN limit Equivalent to 4.2 mg/l at 370 mgd Oct WASA submitted Final TN/WW Plan 2009 EPA issued draft Permit for public comment with slightly revised d TN limit Approx 4.3 million lb TN allocated to complete treatment outfall 002 as a permit limit) CSO outfall 001 load of about 0.3 million lbs listed in fact sheet et 32

33 Effluent Nitrogen (Million lbs/yr) Blue Plains has Exceeded Ches. Bay Goal of 40% Nutrient Reduction over 1985 Levels Blue Plains Nitrogen Effluent Performance Better than Ches. Bay 40% reduction over 1985 levels Mil. lbs/yr Better Than Goal Effluent TN Permit Goal Proposed Permit Limit 19.4 mil lbs better than goal since

34 The Solution: Innovative Approach to Handling Wet Weather Flows Expand CSO tunnel storage to even out flow peaks Construct wet weather treatment system for wet weather flow from tunnel Run Blue Plains at steadier flow rates during storms design nitrogen removal for these flows Minimizes stress on treatment system Cost = $950 Million vs. more than $1.44 billion for conventional approach 34

35 Total Investment $3+ Billion Tunnel Shaft Construction + Typical Enhanced Clarification System 35

36 Regulatory Requirements Long Term Control Plan Implementation: Required by 2 Consent Decrees that stipulate schedule for implementation TN Removal at Blue Plains Required by NPDES Permit that stipulates schedule for implementation 36

37 Schedule Activity Total Nitrogen Removal at Blue Plains: Deadline Place TN removal facilities in operation July 2014 CSO Long Term Control Plan: Anacostia Replace inflatable dams, complete pump station rehabs Complete Complete Anacostia sewer separation 2010 Place tunnel from Blue Plains to RFK in operation 2018 Complete remainder of tunnel 2025 Potomac Replace inflatable dams Complete Complete pump station rehabs (40% CSO reduction) 2009 Complete Potomac Tunnel 2025 Rock Creek Complete Rock Creek sewer separation 2011 Piney Branch Storage Tunnel 2025 System Wide Low Impact Development (LID) at WASA facilities

38 WASA is moving ahead with major investments in pollution reduction and water quality improvement on the Anacostia River, Potomac River and Rock Creek at a cost of over $3B paid by rate payers. Programs will achieve both CSO reduction goals and Chesapeake Bay (nutrient reduction) LTCP meets WQS Better effluent quality from Outfall 001 Lower TN and other Loads to the Potomac River Significant reduction in CSOs achieved to date (40%) Achieves LTCP level of CSO control on Anacostia River by 2018 instead of 2025 More Cost Effective More Reliable Flow Management High Rate treatment system is expandable Summary Supports revitalization of Poplar Point 38