Quantifying LID Triple Bottom Line Benefits Milwaukee Case Study Kimberly Brewer, A.I.C.P. Tetra Tech

Transcription

1 Quantifying LID Triple Bottom Line Benefits Milwaukee Case Study Kimberly Brewer, A.I.C.P. Tetra Tech Karen Sands, Manager of Sustainability, MMSD Heather Fisher, AICP, Tetra Tech 1

2 Background MMSD provides water reclamation and flood management services to 1.1 M customers in the Milwaukee, WI region In last 3 decades, invested 3B in grey infrastructure to reduce sewer overflows Proposed goal: eliminate all overflows by 2035 Green infrastructure now critical to meeting the goal 2

3 Background, cont. Study identifying the potential for and benefits of green infrastructure in flow reduction Screening level analysis for entire Combined Sewer Service Area (converting impervious to pervious) Detailed analysis for pilot area (this presentation) Identified maximum green BMP opportunities Determined most cost effective combination of BMPs for flow reduction Quantified other economic, social, and environmental benefits of recommended green infrastructure (TBL) 3

4 Identifying Maximum Green BMP Opportunities 4

5 Pilot Area 600 acres Urban land use

6 Identify Hydrologic Boundary

7 Establish Land Use Classification 2. Establish Land Use Classification

8 Identify Potential 3. Siting BMP Tool: Locations Identify Potential BMP Locations

9 Maximum Green BMP Potential - Sewershed B-East

10 Identification of Potential Practices Each practice evaluated based on a review of aerial imagery Applicability based on available land or roof area and proximity to sources of runoff Assessment also involved treatment trains On-site interception (e.g., rain barrels, green roofs) or on-site treatment (e.g., bioretention, porous pavement, infiltration trenches) Regional collection and treatment

11 Determine most Cost Effective Combination of Green BMPs 11

12 SUSTAIN System for Urban Stormwater Treatment and Analysis INtegration EPA Sponsored GIS-based framework to support decision-making Optimization 12 Interpretation (Post Processor)

13 Place BMPs and Network Linkages 5. Place BMPs & Network Linkages

14 Identify Assessment Points & Optimization Objectives/Constraints 6. Identify Assessment Points & Optimization Objectives/Constraints

15 Results Cost-Effectiveness Solution Cost ($ million) Annual Volume Reduction (%) 1 $ % 2 $ % 3 $ % 4 $ % 90% 80% Effectiveness (% Reduction) 70% 60% 50% 40% All Solutions Cost-Effectiveness Curve Preferred Solution Selected Solutions 30% $0.0 $10.0 $20.0 $30.0 $40.0 $50.0 $60.0 $70.0 $80.0 Cost ($ Million)

16 Benefits of Optimization Approach Provides recommended location, size, order and phasing of structural BMPs Greater long-term cost savings Higher assurance investments in BMPs will meet objectives Realistic assessment of what s achievable Supports adaptive approach

17 Determine Triple Bottom Line Benefits 17

18 Triple Bottom Line Analysis Why Do It? Social, economic, and environmental benefits of green infrastructure maximize return in investment Illustrate benefits to motivate change More beautiful neighborhoods, higher property values, improved safety and increased jobs Environmental stewardship benefits

19 Triple Bottom Line Analysis General Approach Analysis based on a literature review and relevant studies Cumulative benefits are reported over a 20-year horizon Applied to 600-acre pilot area Evaluated the suite of green infrastructure practices recommended in SUSTAIN as being most cost-effective

20 Triple Bottom Line Indicators Economic Job Creation Reduced Infrastructure Cost Social Improved Quality of Life and Aesthetics Increased Recreational Opportunities Environmental Reduced Pumping Costs Increased Property Values Reduced Stormwater Volume Carbon Sequestration Reduced Sediment Loading Reduced Energy Use Increased Groundwater Recharge

21 Job Creation - Key Methods and Assumptions Ongoing maintenance creates need for unskilled labor Results in reduced unemployment and associated funding for welfare and other social services Annual maintenance costs x ratio of jobs per O&M $ = direct recurring jobs Conservative estimate of job creation Over time, additional skilled and non-skilled jobs created 21

22 Triple Bottom Line Analysis- Job Creation Job Creation 22 permanent jobs for unskilled workers Present worth of $2.7 million reduction in social costs

23 Property Values - Key Methods and Assumptions Studies show green infrastructure can increase property values Improved aesthetics and drainage Recreational opportunities Reduced homeowners or tenants costs Based on studies, median increase in value is 4% Benefits realized if property is within 600 ft of green infrastructure 23

24 Recreation - Key Methods and Assumptions Potential recreational amenity = new greened areas associated with green alleys and bioretention Opportunities for greenways and wetlands not identified in pilot area should target for other sewersheds. 24

25 Triple Bottom Line Analysis Property Values & Recreation Increased Property Values Property value increase totaling $2.7 million Increased Recreational Opportunities 11-acre increase in recreation areas

26 Carbon Sequestration - Key Methods and Assumptions Milwaukee Urban Tree Effects and Values (USFS) 3,377,000 existing trees in Milwaukee Tree canopy covering 13,374 acres 1.16 tons CO 2 sequestered per greened acre Engineered green infrastructure also sequesters CO 2, however benefits not well documented Assumed engineered green infrastructure to be 75% as effective in carbon sequestration Needs more research/study 26

27 Energy Savings - Key Methods and Assumptions Trees and vegetation planted near buildings can affect energy consumption Shading Evaporative cooling Blocking winter winds Milwaukee s urban tree study energy savings per greened area due to trees: $864,000 per year (2002) 27

28 Energy Savings - Key Methods and Assumptions, cont. Green roofs estimated to provide approx 17,000 kwh/acre/year of reduced energy Not identified as cost effective BMP for pilot area Assumed other green infrastructure (such as bioretetion (with small trees), street trees, etc) yields half the energy savings (as trees and green roofs) needs more research/study 28

29 Triple Bottom Line Analysis Carbon & Energy Carbon Sequestration Reduction of 156 tons of carbon dioxide over 20 years = Annual carbon emissions from 2,652 autos or 1,318 single family homes Reduced Energy Use Reduction of 128,000 kwh in energy use over 20 years and $3,900 to $5,700 in energy savings

30 Triple Bottom Line Analysis - Stormwater Load Reductions and Runoff Benefits 68 Tons TSS removed per year Reduction in runoff 435 acre-feet per year Groundwater recharge Increased recharge 406 acre-feet per year

31 Triple Bottom Line Analysis Acre Pilot Area Reduction in Social Costs Due to New Low Skill Jobs Tracking the relative contribution of BMPs to TBL benefits Decreased Stormater Runoff Carbon Dioxide Avoided

32 Triple Bottom Line Analysis Extrapolated Extrapolation to the 23 sq. mi. service area include Increased property value of 68 M 275-acre increase in recreation area 550 jobs created, 68 M reduction in social costs 3,900 tons of carbon dioxide sequestered over 20 years = 32,950 single family homes or 66,300 autos Reduction of 1,800,000 kwh and $98,000 to $143,000 in energy savings over 20 years.

33 Triple Bottom Line Analysis Other Benefits Amenity and comfort ratings are % higher for a tree-lined sidewalk compared to a non-shaded street. 20% 60% 80%

34 Triple Bottom Line Analysis Other Benefits Amenity and comfort ratings are % higher for a tree-lined sidewalk compared to a non-shaded street. 20% 60% 80%

35 Triple Bottom Line Analysis - Other Benefits Desk workers who can see nature from their desks experience approx % less time off sick. 10% 25% 45%

36 Triple Bottom Line Analysis - Other Benefits Desk workers who can see nature from their desks experience approx % less time off sick. 10% 25% 45%

37 Triple Bottom Line Analysis - Other Benefits Study of green space amenity values related to customers price valuation, participants priced goods % higher in landscaped districts. 3% 9% 12%

38 Triple Bottom Line Analysis - Other Benefits Study of green space amenity values related to customers price valuation, participants priced goods % higher in landscaped districts. 3% 9% 12%

39 Triple Bottom Line Analysis - Other Benefits Survey of one community, % of the public preferred to patronize commercial establishments whose structures and parking lots have trees and landscaping. 50% 75% 100%

40 Triple Bottom Line Analysis - Other Benefits Survey of one community, % of the public preferred to patronize commercial establishments whose structures and parking lots have trees and landscaping. 50% 75% 100%

41 Triple Bottom Line Analysis - Other Benefits People make more walking trips when they are aware of natural features, and judge distances to be greater than they actually are in less green neighborhoods. True False

42 Triple Bottom Line Analysis - Other Benefits People make more walking trips when they are aware of natural features, and judge distances to be greater than they actually are in less green neighborhoods. True False

43 To maximize our return on stormwater infrastructure investment, we need to Target conventional and green BMPs that are most cost-effective and feasible. Consider the triple bottom line benefits that go beyond stormwater management. Use adaptive management!

44 Contact information Karen Sands Kimberly Brewer ext.101 Heather Fisher ext