Using LID for TMDL Compliance: Stairway to Heaven or Highway to Hell? Dustin Bambic, PH Tetra Tech, Nashville TN

Transcription

1 Using LID for TMDL Compliance: Stairway to Heaven or Highway to Hell? Dustin Bambic, PH Tetra Tech, Nashville TN Jason Wright, PE Tetra Tech, Raleigh NC 1

2 Overview TMDL Compliance Planning for TMDL Compliance BMP modeling and optimization Case studies Site scale Watershed scale Regional scale Dramatic, Overarching Conclusions 2

3 TMDL COMPLIANCE 3

4 Status of TMDLs Over 92,000 miles of impaired waters due to urban stormwater Over 45,000 TMDLs adopted to date Bacteria (20%), metals (18%), Hg (16%), nutrients (11%) Less than 150 completed in year 1996 More than 9,000 completed in year 2008 More than 20,000 TMDLs yet to be completed Cost to implement one TMDL can exceed $1 billion 4

5 Phase 1 MS4 Permits + Strategic Partners (primes and subs) Phase 1 Stormwater Permitees 5

6 Narrative Permit Provisions (TN) 6

7 Numeric Permit Provisions (CA) 7

8 BMP based Permit Provisions (CA) 8

9 Recipe for Compliance 9

10 Scheduling the Recipe 10

11 BMP MODELING: REASONABLE ASSURANCE 11

12 10s of BMPs Site Watershed 1,000s of BMPs 12

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14 BMP Modeling Watershed Management Modeling System (WMMS) Linked models Loading Simulation Program C++ (LSPC) EPA s SUSTAIN Methods for optimization of BMP placement and design Locally derived BMP cost functions 14

15 SUSTAIN System for Urban Stormwater Treatment and Analysis Integration 15

16 Process based Modeling 16

17 BMP Optimization to Meet Permit Compliance Cost Effectiveness Curve 90% 80% Effectiveness (% Reduction) 70% 60% 50% 40% All Solutions Cost-Effectiveness Curve Selected Solution Selected Solutions 30% $0.0 $10.0 $20.0 $30.0 $40.0 $50.0 $60.0 $70.0 $80.0 Cost ($ Million) 17

18 $90.0 $80.0 $70.0 $60.0 $50.0 $40.0 $30.0 $20.0 $10.0 $0.0 83% 84% 84% 84% 84% 84% 85% 83% 38% 44% 48% 50% 54% 56% 58% 60% 61% 63% 65% 67% 68% 70% 72% 73% 75% 76% 77% 79% 80% 80% 81% 82% 82% 83% 83% BMP Optimization Cost Effectiveness Curve Rain Barrel Regional Bioretention Rain Gardens Green Alley Porous Pavement Block Bioretention Green Roof 0% 1% 17% 28% 6% 31% 17% Effectiveness (% Reduction) 18 Cost ($ Million)

19 REASONABLE ASSURANCE AND COST OPTIMIZATION: SITE SCALE 19

20 LID Performance 20

21 LID Performance Bioretention 21

22 22

23 REASONABLE ASSURANCE AND COST OPTIMIZATION: WATERSHED SCALE 23

24 City of San Diego 24

25 Green Streets Analysis Spatially optimized by suitability 1. Slope 2. Imperviousness 3. etc. Priority subwatersheds identified

26 26

27 REASONABLE ASSURANCE ANALYSIS Zinc Target WITH GREEN STREETS and WER: Cost: $480M Savings: $940M Copper Target Zinc Target Required Reduction: 73.2% Cost: WITH $1.42 WER: billion Cost: $780M Savings: $640M 27

28 REASONABLE ASSURANCE AND COST OPTIMIZATION: REGIONAL SCALE 28

29 Los Angeles County 29

30 Distributed BMPs for Defining Management Levels 4 treatment pathways from urban land use runoff Distributed BMP Types Permeable Pavement Bioretention Rain Barrels

31 Optimal Cu Scenario 75% Wet Days in Compliance 75% wet-weather compliance Total Treatment Cost: $0.59 billion Most locations are in compliance 31

32 Optimal Cu Scenario 85% Wet Days in Compliance 85% wet-weather compliance Total Treatment Cost: $2.76 billion Only a few areas are targeted for management 32

33 Optimal Cu Scenario 90% Wet Days in Compliance 90% wet-weather compliance Total Treatment Cost: $6.96 billion Most of the heavily urbanized areas are targeted for management, some more than others 33

34 Optimal Cu Scenario 95% Wet Days in Compliance 95% wet-weather compliance Total Treatment Cost: $13.73 billion* Some areas cannot achieve 95% compliance without additional centralized BMP controls * Distributed BMP cost estimate ONLY 34

35 Optimal Cu Scenario 100% Wet Days in Compliance 100% wet-weather compliance Total Treatment Cost: $24.98 billion* Most subwatersheds cannot achieve compliance without additional centralized BMPs. * Distributed BMP cost estimate ONLY 35

36 Watershed-scale Optimization 36

37 CONCLUSIONS 37

38 Conclusions MS4 NPDES permits are becomingly more numeric Increased expectations regarding reasonable assurance Quantitative linkage between BMPs and WQ standards Planning tools critical for linking different spatial scales Become cornerstone of SWMP and MS4 WQ program Support efforts to secure funding mechanisms Stairway to Heaven? Rights of way provide opportunities in urbanized watersheds For most stringent requirements, might required centralized/regional BMPs Triple Bottom Line analyses can incorporate other benefits 38