Big Creek Watershed Retrofit Ranking Project

Transcription

1 Big Creek Watershed Retrofit Ranking Project John Stein and Jennifer Olson Tetra Tech, Inc. Bob Gardin, FOBC Innovative Stormwater Conveyance Through Green Infrastructure May 13, 2014

2 Presentation Outline Big Creek Watershed Project Components Retrofit types Ranking and scoring system Field investigations Concept plan development Lessons Learned What works and what doesn t Looking ahead

3 Big Creek Watershed Overview Drainage Area: 39 square miles Population: 178,000 Encompasses 8 communities within Cuyahoga County Most urbanized tributary in Cuyahoga River Watershed (approximately 40% impervious)

4 Big Creek Watershed Balanced Growth Plan Overview Developed by FOBC, CRCPO, and local l stakeholders Received State endorsement in June 2011 Identified stormwater retrofits as a priority action Community goals include: Improve Water Quality in Big Creek Reduce Flooding

5 Project Overview Multi-phase project: Funding provided by Lake Erie Protection Fund, NEORSD, Freshwater Future, General Motors, FOBC Technical Advisory Committee provided oversight Cleveland Metroparks Cuyahoga River Community Planning Org (RAP) NEORSD Cuyahoga County Board of Health Cuyahoga County SWCD NOACA

6 Retrofit Types Conducted desktop GIS analysis to identify four types of potential retrofits Parking lots over 5 acres Existing detention basins Storage below outfalls (12 to 36 pipe) Storage at highway interchanges Expanded Watershed Plan recommendations to include large rooftop retrofits and source controls

7 Parking Lots over 5 Acres Add treatment to existing green spaces Bioswales/bioretention Rain gardens Pavement modifications Porous pavement Tree trenches

8 Modified Detention Basins Add water quality treatment and storage to existing ponds Excavation Outlet modifications Internal design features to improve performance Water quality bench Vegetation management

9 Storage Below Outfalls Divert flow from existing structures to new stormwater treatment facilities Works best for storm drain outfalls 12- to 36-inch diameter located near large open spaces

10 Storage at Highway Interchanges Use right-of-way for stormwater treatment Highway cloverleaf Median and wide right of way areas

11 Rooftops Divert runoff from large rooftops (> 5 acres) to stormwater facilities Underground storage Ponds or infiltration practices Need to be aware of internal drains and architectural plans Can be challenging to reroute internal drains Treat onsite Green roof Photo credit: Erik Larson, UMD

12 Source Controls Decentralized stormwater management Rain gardens Rain barrels and downspout disconnection Porous pavement Bioswales Green street concepts

13 Project Tasks Task 1: Preliminary screening (176 sites) Task 2: Field assessment and priority ranking (79 sites) Task 3: Conceptual designs and cost estimates (7 sites)

14 Task 1: Preliminary Screening Six types of retrofits evaluated Large amount of GIS data collected and reviewed Evaluated residential area characteristics (source controls)

15 Task 1: Preliminary Screening Ranking criteria for each site included: Drainage area Impervious area Total suspended solids load Treatment area Evaluated 196 sites (some were later grouped)

16 Example of drainage area delineation for aretrofitsite

17 Residential Area Evaluation

18 Task 2: Field Assessment Ground truth Task 1 criteria and existing conditions Identify other issues or opportunities on site Initial contact with landowner in some cases Cuyahoga County Board of Health and SWCD supported field work in Phase 2

19 Task 2: Priority Ranking Ranking Criteria: Presence and Extent of Existing Treatment Planned Priority: Planned Project or Stakeholder Interest Constructability: Known Utility or Site Constraints Coordination: Type and Number of Property Owners (e.g., private vs. public) Education Opportunity: Good Visibility for Demonstration Project Equal weight except for Planned Priority (weighted x 2) Contact landowners and discussed initial concepts to get preliminary feedback (e.g., presented concept plan to GM s Green Team) Presented draft conceptual plan to FOBC TAC