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Duke Bitsko - Alewife Stormwater Wetland

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Duke Bitsko, landscape architect with Chester Engineers describes a large-scale project he worked on in the Alewife Reservation, transforming a degraded low-quality upland habitat into a constructed stormwater wetland and park. The interdisciplinary team incorporated green infrastructure strategies to create diverse upland and wetland native plant communities.

Presented at the Urban and Suburban Carbon Farming to Reverse Global Warming conference at Harvard University on May 3, 2015, organized by Biodiversity for a Livable Climate.

www.bio4climate.org

Published in: Environment
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Duke Bitsko - Alewife Stormwater Wetland

  1. 1. Alewife Stormwater Wetland Cambridge, MA Carbon Farming to Reverse Global Warming Duke Bitsko, Director of Interdisciplinary Design 3 May 2015
  2. 2. Presentation Outline 1. Project Overview 2. Native Habitat Planting Strategies 3. Vegetation Management Strategies
  3. 3. CSO Compliance Project – Cambridge MA • Federal mandate to clean Boston Harbor • Reduces CSO’s by 84% or 43.6 million gallons annually to Mystic River • Green Infrastructure includes downspout disconnect, porous paving, bioretention and constructed wetlands
  4. 4. Alewife Stormwater Wetland • Largest stormwater wetland in Northeast (3.5 acres/10.3 acre-feet) • Cleans, stores, reduces and releases stormwater to impaired stream system • Integrates recreation, education and ecology • Commitment to long-term management and monitoring • State and City partnership
  5. 5. Recreational Benefits
  6. 6. Educational Benefits
  7. 7. Project Components • Wetland Forebay; Water Quality Swale; Wetland Basin; Oxbow/Floodplain; and Parkland
  8. 8. Water Level Fluctuation Plan – Drought Condition
  9. 9. Water Level Fluctuation Plan – Dry Weather “Baseline”
  10. 10. Water Level Fluctuation Plan – 2-Year Storm
  11. 11. Water Level Fluctuation Plan – 5-Year Storm
  12. 12. Water Level Fluctuation Plan – 10-Year Storm
  13. 13. Water Level Fluctuation Plan – 100-Year Storm
  14. 14. Wetland Basin
  15. 15. Plant Communities Vegetative Zones • Permanent Pool 3’ – 5.5’ deep • Deep Marsh 18” - 3’ deep • Emergent Marsh: 6” - 1’ deep • High Marsh: 0 – 6” deep • Wet Meadow: Ephemeral, infrequent inundation • Upland Riparian: slopes and islands
  16. 16. Wetland Basin - Plant Selection • Pollutant removal capacity • Natural habitat community-based • Native to SE Massachusetts (no cultivars) • Wildlife and cover value • Commercially available
  17. 17. Wetland Basin - Plantings
  18. 18. Wetland Basin Plantings • Over 120,000 wetland plugs and tubers planted • Habitats include open water, deep marsh, emergent marsh, high marsh, and wet meadow
  19. 19. Wetland Basin
  20. 20. Oxbow and Floodplain  Compensatory flood storage and increased habitat diversity  Flap gate and flow connection to Wetland Basin  Open water habitat harbors alewife species  Spillway overflow and storage
  21. 21. DCR Parkland – Upland Habitat • Scrub/shrub, Riparian Woodland (wet and dry) habitats • All species native to SE Massachusetts; no cultivars used
  22. 22. Construction 2011-2013
  23. 23. Establishment Period Summer 2013
  24. 24. Develop O & M Manual
  25. 25. City of Cambridge: • Outfall/inlet structures • Forebay/WQ swale • Wetland Basin • WQ testing (TP, N, coliform) MA DCR: • Paths and boardwalks • Amphitheatre and signage • Non-wetland plantings Operation and Maintenance Responsibilities
  26. 26. Agency Responsibility Diagram
  27. 27. Add break slide Training Workshops
  28. 28. Vegetative Zones • Permanent Pool 3’ – 5.5’ deep • Deep Marsh: 18” - 3’ deep • Emergent Marsh: 6” - 1’ deep • High Marsh: 0 – 6” deep • Wet Meadow: Ephemeral, infrequent inundation • Upland Riparian: slopes and islands Stormwater Wetland – Deep Pool Sediment Removal
  29. 29. Deep Pool Sediment Removal – 2 Step Process 1. Inspection: • Kayak and measuring stick (hard clay bottom) 2. Sediment Removal: • Drought conditions (July -September) • Vacuum truck hose extension (from kayak) and/or manual removal
  30. 30. Water Quality Improvement • For the 1-month and 3-month storm event - projected water quality enhancements: 1-month 3-month Contaminant Expected Removal Rate Total Suspended Solids 65% 75% Lead 75% 80% Zinc 40% 40% Total Phosphorus 40% 40% Total Nitrogen 25% 30% Source: Schueler 1992
  31. 31. Water Quality Sampling Stations CambridgePark Drive Wetland Outlet
  32. 32. Post-Construction Activities – Invasive Management
  33. 33. Vegetation Management Plan Components • Qualification of Wetland Scientist • Statement of VMP Goals • Description of Target Vegetation • Vegetation Inventory • Methods of Control/Seasonal Schedule • Regulatory Compliance
  34. 34. Vegetation Management Plan
  35. 35. Inspection Checklists

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