Meadow Walk at Lynnfield Design, Permitting and Implementation for Low Impact Development in 2008

Transcription

1 Meadow Walk at Lynnfield Design, Permitting and Implementation for Low Impact Development in 2008 June 23, 2008 EOEA Low Impact Development Conference for Developers

2 P Project Perspectives Developer Ed Marsteiner - National Development Stormwater Consultant - Bethany Eisenberg, LEED AP VHB Engineer- Danielle Spicer, P.E., LEED AP Stantec

3 Developer Perspective - Ed Marsteiner National Development Meadow Walk Design Process Permitting Process Technical Design/Stormwater Cost /Benefits

4 Meadow Walk History Purchased Colonial (Summer 2006)

5 Key Elements of Sustainable Design High pedestrian access to multiple uses Sustainable Landscape Design -Water/Habitat 114 Acres Open Space -Habitat/Wetland Protection Stormwater Management dispersed throughout the site I-95 Higher density development close to highway access Land Conservation Buffer Zone Restoration Water Balance/Hydrology Mixed Uses Decrease Carbon Footprint Low Impact Development (LID) Practices

6 Permitting Hurdles Natural Heritage Mass Audubon Local Conservation Commission 2 towns DEP Stormwater MEPA MWRA Saugus River Watershed Council Lynn Water Sewer Commission

7 Key Resources to Protect Wildlife Wetland Open Space Water

8 Consistent Thread for All Reviewers Low Impact Development Stormwater Management Land Preservation Resource Buffers LEED Water Use Reduction Transportation Management Program

9 Benefits Tenant Perspective Permitting efficiency Peace of mind of design Complex system not typical

10 Additional Soft Costs New Stormwater Regs ~$310,000 in Additional Testing & Consultant Review Geotechnical Additional test pits, borings & probes Mounding analysis & groundwater modeling Design Engineer (Stantec) Design Adjustments (Calcs& Plans) Internal Technical Review (VHB) Additional Peer Review Time/Money Time Timing of Filing & Complexity of New Regs Added 1-2 months to permitting time frame (carrying costs)

11 Hard Costs Subsurface Storage $13-$15 PSF HDPE Corrugated Pipe Manholes Gravel Does not include excavation ($3 to $4 per yard assuming material used on site) Quantity of over 100,000sf

12 Hard Costs Porous Pavement $85/sy 30+ Stratified sub-base Filter fabric Piping (Overflow Drain) Asphalt Does not include excavation and removal of existing material (if necessary) - $10/cy

13 Hard Costs Porous Pavement Intangibles Elimination or Downsizing of Traditional Stormwater Components Basins Grading, liners, fencing, slope stabilization, structures, etc. Space Elimination or downsizing of stormwater basins may allow more program or a more efficient site layout Aesthetics More attractive than basins

14 Hard Costs Vegetated Swales $95/sy Amended soil ($50/cy) Wood guard rail ($30/lf) Check Dams Overflow CB Does not include landscaping which can vary greatly (Trees, shrubs, plugs, wetland seed mix, etc.) We budget $45/sy

15 Hard Costs Stormceptors Buy stock in Stormceptor 15 on Meadow Walk project alone O&M costs TBD

16 Stormwater Management/LID Bethany Eisenberg LID BMP Selection Site specific info needed Significant field investigations Developing new details Modifying for new MA Standards

17 LID Selection Focus on Existing Water/Wetland Resources to Protect Key existing resources were identified and drove the proposed design: Lynn Water Supply Lynn water supply: reedy meadow, canal, No Outstanding Resource Waters (ORWs) Wetlands Natural Heritage/MA Audubon Reedy Meadow Water Balance Saugus River Water Balance (follow this slide with graphic that has fly ins of each of these things)

18 LID Practices Protection of Wetlands with Land Conservation Principle Concept for LID

19 LID Protection of Resources with Buffers, Set backs and Wetland Edge Restoration Need Better Slide from Stantec and discussion points

20 Site Hydrogeology Drove LID Selection for the Development Area 64 Test Pits 25 Monitoring Wells 14 Percolation Tests 9 Falling Head Permeability 10 Rising Head Permeability 15 Grain Size analysis Mounding analyses

21 LID selection for a Bedrock Hill with Sands at the Wetland Edge

22 LID Practices Bioretention Swales for Water Quality Treatment in High Traffic Areas

23 Bioretention Swales in Parking Areas High water quality treatment before infiltration or detention Overflow to subsurface detention or surface detention Under drains required due to subsurface conditions Double shredded hardwood mulch 2 ft. min bioretention media 6-9 inch ponding depth Can be landscaped to match desired look of the development 23

24 LID Practices Dispersed Infiltration, Detention Water Balance Consistent with National (i.e. LEED) and MADEP Standards for LID

25 LID Practices Porous Pavement in Sand at the Wetland Edge Higher Permeability Less vehicular trips Permanent residential area with more control of use and O&M

26 LID Practices Extensive Landscaping

27 Low Impact /Sustainable Landscaping Native Species Draught tolerant Species Integrated Pest Management Shade Trees 27

28 LID Benefits of Planting Trees One mature tree can increase a property value by 15% Trees around a home can reduce summer cooling costs by 30% Winter heating costs can be reduced using trees as windbreaks (30% ±) Pollutant removal (carbon, nitrous dioxide, sulfur dioxide) 1 tree removes 13 1lbs ±carbon per year Puget Sound: Estimated 78M lbs. of pollutants removed per year Cost $19.5M if removed by industrial treatment process

29 Integration of Trees Image by GreenbergFarrow

30 Integration of Trees Image by GreenbergFarrow

31 Screening Image by GreenbergFarrow

32 Screening Image by GreenbergFarrow

33 Full Build Project - focused on resource protection

34 Engineer s Perspective Danielle Spicer - Stantec Questions the design engineer must now face How to meet the new MA Stormwater Handbook regulations? Design a sustainable site? Keep the project on budget? Keep the client happy?

35 Engineer s Perspective The New MA Stormwater Handbook Regulations The new regulations are requiring more detailed engineeringand more existing site specificinformation. This can result in a lengthier time to finalize the design which results in higher costs to the client.

36 Meadow Walk 200 acres

37 Extensive Geotechnical Investigations 64 Test Pits 25 Monitoring Wells 14 Percolation Tests 9 Falling Head Permeability 10 Rising Head Permeability 15 Grain Size analysis Mounding analyses That s 137 tests!

38 Engineer s Perspective 13 Proposed Stormwater Basins

39 Engineer s Perspective There are three substantial changes in the new regulations that require more engineering. Recharge Water Quality Land Uses with High Potential Pollutant Loads (LUHPPL)

40 Engineer s Perspective Recharge Higher Recharge Volumes Hydrologic Group A Old Recharge Depth x Total Impervious Area New Recharge Depth x Total Impervious Area 0.40 inches 0.60 inches B 0.25 inches 0.35 inches C 0.10 inches 0.25 inches D waived 0.10 inches

41 Engineer s Perspective Recharge - Additional treatment required before recharging At least 44% of the TSS MUST be removed prior to discharge to an Infiltration structure if: Within a Zone II or Interim Wellhead Protection Area Near a Critical Area From Land Uses with higher Potential Pollutant Loads (LUHPPL) In an Area with Rapid Infiltration Rate (>2.4 inches/hour) At least 80% of the TSS MUST be removed prior to discharge to an Infiltration structure if: Using the Dynamic Field Method

42 Engineer s Perspective Water Quality The TSS removal efficiencies have all been updated There are more requirements that need to be met in order to use a Proprietary Separators. Proprietary Separators now have an individual TSS removal efficiency based on the manufacturer (see UMass Amherst website) Need to show not only 80% removal at end of treatment train, but may need to show pretreatment TSS removal rates.

43 Engineer s Perspective Water Quality Treatment Train with 44% TSS pretreatment removal shown

44 Engineer s Perspective Land Uses with Higher Potential Pollutant Load (LUHPPL) Recharge from a LUHPPL is now required in Zone II Drinking Water Areas Specific Pretreatment for LUHPPL required (44% TSS removal prior to discharge to an infiltration basin) More water quality treatment required 1 rule Updated list of BMPs that are appropriate for LUHPPL based on latest science

45 Engineer s Perspective Conclusion The overall goal is to provide better environmental protection for future developments

46 Engineer s Perspective