GREEN ON THE HORIZON. Challenges of Integrating LID into New Development. Southeast Stormwater Association

Transcription

1 GREEN ON THE HORIZON Challenges of Integrating LID into New Development Southeast Stormwater Association Annual Seminar, Charleston SC October 9, 2014 JENNIFER A. NUNN, PE THE BALMORAL GROUP

2 Acknowledgments Collaborative Effort Orange County Divisions / Departments Planning Division Department of Public Works Stormwater Management Division Development Engineering Division Roads & Drainage Division Environmental Protection Division Consultants Geosyntec Consultants prime The Balmoral Group - subconsultant 2

3 Outline Introduction and Project Overview Stormwater Master Planning and LID Integration Low Impact Development (LID) Practices Next Steps & Conclusions Questions

4 Outline Introduction and Project Overview Stormwater Master Planning and LID Integration Low Impact Development (LID) Practices Next Steps & Conclusions Questions

5 Introduction Wellness Way Sector Plan Horizon West Sector Plan Four Corners Area Disney World 5

6 Introduction Horizon West Area 6

7 Introduction What is Horizon West? 23,000 acres 1 st Sector Plan in Florida Former greenfield rural area close to Disney and new SR 429 Opportunity for new planning vision for Orange County Over 40,000 households within six Villages Regional-scale town center 7

8 Introduction Horizon West Town Center Employment and commercial hub Higher density urban environment Town Center development program: 3,500 acres 6,000 housing units 1,200 hotel rooms ~8,000,000 sq. ft. of commercial and office uses 8

9 Project Overview Orange County LID Manual project: LID Manual - 7 LID practices - Practices suitable for greenfield type urban development LID concept plans comparison - Traditional vs. LID site design - Comparison of costs and maintenance requirements LID maintenance cost projections - Annual maintenance costs for each of the LID practices - 10-year maintenance cost projections 9

10 Project Overview What is Green Infrastructure? Greenscaping and Green Streets Low Impact Development (LID) practices Stormwater master planning Open space component Land Management and Maintenance Source: Source: Source: 10

11 Project Overview Why Green Infrastructure for the Town Center? The County is in the process of developing the Town Center Development Code and Specific Area Plan encourages stormwater master planning. Greenfield and hydrologic conditions suitable for use of LID practices. ~ 70% of area basins are closed basins. Town Center could serve as a pilot area for application of the Green Infrastructure concept. 11

12 Outline Introduction and Project Overview Stormwater Master Planning and LID Integration Low Impact Development (LID) Practices Next Steps & Conclusions Questions

13 Stormwater Master Planning and LID Approaches integrated through the Green Infrastructure Code: Master Planning addresses flood protection Low Impact Development (LID) practices address water quality Outfall condition affects determination of storm event and selection of water quality treatment regime Codified incentives for use of LID practices 13

14 Stormwater Master Planning and LID Master Planning determined by: Size and location of basin(s) Type of land use district Basin property ownership Joint Use Retention/Detention Facilities 14

15 Stormwater Master Planning and LID Implementation Challenges: 1. Coding for a Green Infrastructure Approach District-based or Neighborhood-based 2. Timing of Master Stormwater Planning Unified Neighborhood Plan Planned Development Subdivision Plats/Construction Plans-Permits 3. Construction of Improvements Phased Implementation Capacity Reservations 4. Maintenance of Improvements Public or Private Performance Standards, Permitting Criteria 15

16 Outline Introduction and Project Overview Stormwater Master Planning and LID Integration Low Impact Development (LID) Practices Next Steps & Conclusions Questions

17 Low Impact Development (LID) Practices What is LID? Low Impact Development (LID) is an approach to land development that works with nature to manage stormwater as close to its source as possible. EPA Definition (Coffman, 2000) LID is a site design strategy with a goal of maintaining or replicating the predevelopment hydrologic regime through the use of design techniques to create a functionally equivalent hydrologic landscape. 17

18 Low Impact Development (LID) Practices Benefits of LID Focus on stormwater as a resource Pollutant Treatment (water quality) Volume Reduction (attenuation) Land Utilization 18

19 Low Impact Development (LID) Practices Challenges of LID Effective integration with traditional practices; Lack of familiarity of local contractors Lack of familiarity by county engineers Lack of familiarity by regional permitting authorities Lack of experience with maintenance procedures 19

20 Low Impact Development (LID) Practices LID Practices: Pervious pavement Bioretention Areas/ Bioswales Rain Gardens Planter Box Tree Box Filters Curb Cuts & Inverted Medians Stormwater Harvesting Cisterns 20

21 Low Impact Development (LID) Practices Pervious Pavement Applications Non-residential: (commercial/office) parking areas; Residential: driveways and sidewalks; Low-volume, low-speed areas; Open space area: sidewalks or bike paths. Typical pervious asphalt cross section (Source: Public Works Magazine) Typical pervious concrete paver cross section (Source: Interlocking Concrete Pavement Institute) Grass pave (Source: Stone Age Pavers) Interlocking concrete pavers (Source: CT DEP) Gravel-pave (Source: NDS Inc.) 21

22 Low Impact Development (LID) Practices Bioretention Areas/Bioswales Applications Non-residential: commercial/office; Residential: parking areas, street edges, rooftop runoff, adjacent to sidewalks and walking paths; Urban: parking areas, rooftop runoff; Street: within existing roadway ditch, curb cuts to bioswale, roadway median. Bioretention Swale Detail Not to scale (Source: LID Technical Guidance Manual for Puget Sound) Bioretention area in parking lot (Source: City of Santa Barbara Manual) Bioretention swale adjacent to roadway (Source: NRCS) 22

23 Low Impact Development (LID) Practices Rain Gardens Applications Non-residential: (commercial/office) and residential: adjacent to parking areas, driveways, sidewalks, walking paths and rooftops; Streets: adjacent to parking spaces; Urban: rooftop drainage; Open space: adjacent to parking areas and walking paths. organic (mulch) layer Typical cross section of a raingarden (not to scale) (Source: Adapted from Oregon Environmental Council) Raingarden installed on a residential lot (Source: Geosyntec) 23

24 Low Impact Development (LID) Practices Planter Box Applications Adjacent to non-residential (commercial/office) and residential buildings. Planter box designed to capture and treat rooftop runoff (Source: Geosyntec) Illustration of typical planter box cross section (Source: Bayou Land RC&D BMP Guidance Manual) 24

25 Low Impact Development (LID) Practices Tree Box Filters Applications Non-residential: commercial/office; Residential/Urban: parking areas, street edges, sidewalks; Open space: walking paths. Tree box filter along road edge (Source: Geosyntec) Illustration of tree box filter cross section (Source: Contech, Inc.) Illustration of typical tree box filter cross section (Source: Filterra) 25

26 Low Impact Development (LID) Practices Curb Cuts & Inverted Medians Applications Non-residential (commercial/office): parking decks and rooftops; Streets. (Source: NRCS) (Source: US EPA) (Source: North Central Texas) Curb cut along road is providing drainage to raingarden (Source: Geosyntec) Curb cuts and inverted median along four lane road (Source: City of Arlington Virginia) (Source: State of Massachusetts) 26

27 Low Impact Development (LID) Practices Stormwater Harvesting - Cisterns Applications Non-residential (commercial/office): parking decks and rooftops; Residential rooftops. Stormwater harvesting system adjacent to a children s museum (Source: Geosyntec) Above ground cistern used for irrigation purposes (Source: Duke University) Schematic of an underground cistern supplying adjacent building with grey water (Source: All Things Rainwater) 27

28 Low Impact Development (LID) Practices Cost Impacts: Capital Costs Reduced infrastructure ( ) Potentially smaller ponds ( ) More vegetation/plantings ( ) Contractor certifications ( ) Maintenance Costs Training/certifications for personnel ( ) Replace typical landscaping offset overall BMP maintenance area ( ) Infiltration/media testing ( ) 28

29 Low Impact Development (LID) Practices Concept Plans Comparison Purpose Show LID techniques can accommodate equivalent density/intensity development as traditional methods; Provide alternatives to structural stormwater facilities; Provide additional opportunities for infiltration; and Illustrate that water quality, water quantity, and nutrient loading criteria can be met or exceeded using LID practices. Project Site (29.09 acres): portion of Hamlin PD Commercial: - Grocery store 54,000 sq. ft. - Bank (Outparcel) 4,500 sq. ft. - Retail 4,500 sq. ft. Residential: MF units (7 buildings at 24 units/building) 29

30 Low Impact Development (LID) Practices 30

31 Low Impact Development (LID) Practices 31

32 Low Impact Development (LID) Practices 32

33 Low Impact Development (LID) Practices Comparison Results The LID Concept provides the same commercial and residential sq. ft. and parking LID Utilizes acres of the original acres a reduction of 3.78 acres (13%). The LID concept plan meets or exceeds the Traditional concept plan in all stormwater management criteria. 33

34 Low Impact Development (LID) Practices Cost Comparison Results with Land Savings Pay Item LID Cost Traditional Cost LID Description Traditional Description Pavement $ 741, $ 586, Pervious Pavement, Pervious Asphalt, and Pavers Asphalt and Concrete Sidewalk Bioretention Swale $ 645, $ 290, Bioretention Swale Landscaping Raingarden $ 408, $ 104, Raingarden Landscaping Planter Box $ 47, $ 9, Planter Box Landscaping Tree Box Filter $ 128, $ 6, Tree Box Filter Landscaping Curbing and Medians $ 86, $ 86, Valley Gutter, Type D curb, and Pavement Type D Curb and Pavement Stormwater Harvesting $ 212, N/A Stormwater Harvesting No item correlates Primary Storm System $ 398, $ 818, Two Dry Retention Ponds Secondary Storm System $ 354, $ 644, inch Pipe, Manhole, DBI C, 36-Inch MES Undeveloped Land N/A $ 849, No item correlates Totals: $ 3,023,047 $ 3,396,800 Two Dry Retention Ponds and One Wet Detention Pond 12-inch & 36-inch Pipe, DBI C, 36-Inch MES $200k/acre multi-family; $250k/ acre retail 34

35 Low Impact Development (LID) Practices Maintenance Costs Projections Project maintenance costs for each of the LID practices: - frequency - inspection activity - maintenance activity - labor/equipment/materials - costs of similar traditional stormwater management activities Compare example project data Compare to national data 35

36 Low Impact Development (LID) Practices Traditional vs. LID Maintenance Cost Comparison Maintenance Scenario Design Practice Size Estimated Annual Maintenance (2013 Dollars) Estimated 10-Year Maintenance (3% inflation) Pervious Pavement sf $1,333 $15,278 Bioretention sf $11,367 $130,311 Rain Garden sf $5,877 $67,377 Planter Box 2448 sf $1,804 $20,684 Tree Box Filter 10 boxes $1,586 $18,722 Curb Cuts / Inverted Medians N/A N/A N/A Stormwater Harvesting (w/ Cisterns) gal $9,120 $104,548 Dry Retention Pond sf $11,303 $133,462 Maintenance Scenario Design Practice Size Totals: $42,390 $490,382 Estimated Annual Maintenance (2013 Dollars) Estimated 10-Year Maintenance (3% inflation) Dry Retention Pond 132,675 sf $15,880 $187,512 Landscaped Area 30,546 sf $5,889 $69,542 Swale 73,843 sf $8,779 $103,663 Wet Detention Pond 63,319 sf $4,451 $49,095 Totals: $34,999 $409,812 36

37 Outline Introduction and Project Overview Stormwater Master Planning and LID Integration Low Impact Development (LID) Practices Next Steps & Conclusions Questions

38 Where Do We Go From Here? Evaluate cost benefit of master stormwater facility planning Evaluate practice performance criteria for differing site conditions (e.g., High GWT, poor soils, etc.) Evaluate stormwater code changes and enhancements necessary to facilitate lid Develop pilot program to proof practices 38

39 Where Do We Go From Here? Pilot Program Identify goals Identify candidate sites Developer partnerships County facilities Water quality grant projects Design & permitting Inspection & monitoring plan Hydrology Water quality Maintenance tracking Cost analysis 39

40 Conclusions Greater land utilization efficiencies Potential for enhanced water quality Grey infrastructure minimized Improved distribution and arrangement of open space resources Better integration of stormwater facilities and land uses Fewer conflicts between streets, utilities and green infrastructure Opportunities for water harvesting and reuse Enhanced aquifer recharge through LID practices LID has Comparable costs under right conditions (capital & maintenance) 40

41 Contact: Jennifer A. Nunn, PE Vice President The Balmoral Group Tel: / jnunn@balmoralgroup.us 41