![Surface Area of Bioretention Cell
- Must hold 75% of Water Quality Volume
- Af = (WV*df)/[K*(hf+df)(tf)]
- WV = WQv
- df = filter bed depth
- K = coefficient of permeability
- hf = average height of water above filter bed
- tf = filter bed drain time (days)
Af = 4500 ft2
Dimensions of Cell: 15’ by 300’](https://image.slidesharecdn.com/midtermpresentation-141203000902-conversion-gate01/85/Midterm-presentation-17-320.jpg)
Midterm presentation
- 1. Clemson Parking Stormwater Management Carolyn Coffey Brendan Luther Karris Roland Chelsea Walker
- 2. Overview ● Introduction to Clemson stormwater ● Goal of the project ● Potential management solutions ● Governing equations and design ● Sustainability and Life Cycle ● Questions & Comments
- 3. Background and History of Stormwater Regulations - In 1972 the Clean Water Act prohibited any pollutant accessible to waters from a point source. - Runoff carries sediment, pollutants, grease, or oil into storm drains and surface waters - Water Quality Act of 1987 created a structure for different methodologies, including discharge permits for various classifications. On October 31, 1990 the US EPA issued the stormwater rule for the classifications of stormwater systems subject to regulation: ● Combined sewer overflows (both sanitary sewage and industrial processes) ● Wastewater are mixed with rainwater and land runoff ● Municipal separate stormwater systems ● Separate stormwater systems ● Non-point source runoff (all runoff that is not discharged to surface waters via a discrete pipe or conduit)
- 4. Clemson Watershed ● Runoff primarily flows to Hunnicutt Creek o Pollutants from parking lots o Soil displacement and erosion o High peak flow rates ● Nearly 22% of campus is impervious
- 6. Parking services ● Growing university calls for more on campus parking availability ● Proposed lot with additional 400 spaces ● Between the university and city watersheds http://reisasphalt.com/wp-content/uploads/parking-lot. jpg
- 10. Problem ● Runoff from parking lot could add to Clemson’s flooding problems ● Need for better management practices
- 11. Goal ● Prevent parking lot runoff from entering the Clemson watershed ● Filter stormwater pollutants ● Maintain pre-development hydrology ● Ensure infiltration using a bioretention cell
- 12. Constraints ● Budget: $1200 ● Heavy machinery might be necessary ● Permitting constraints ● Potential for large storm events ● Experience of design team
- 13. Considerations for Design Soil Type - Soil Conservation Service classifies more than 4000 different types of soils into four groups http://www.wetlandstudies.com/newsletters/2012/september/docs/hydro_soil_groups.pdf - The physical properties include infiltration rates and relative runoff potential - Web Soil Survey showed the area classified as Group B. - Group B has infiltration rates from 0.15 to 0.30 inches per hour and moderate runoff potential - A curve number is calculated for pre and post development to indicate the runoff potential for the area
- 16. Calculations Bioretention Cell Volume Requirement WQv = (P*Rv*A)/12 P - Rainfall in Inches Rv = Volumetric Runoff Coefficient A = Area in Acres WQv = 9598.5 ft2 Post Development CN = 99 for parking lots Maximum Soil Water Retention: (1000/99) - 10 = 0.1010 Water Quality Runoff Volume: P equals 1 inch for east coast of the United States 1”= 90% of average annual precipitation
- 17. Surface Area of Bioretention Cell - Must hold 75% of Water Quality Volume - Af = (WV*df)/[K*(hf+df)(tf)] - WV = WQv - df = filter bed depth - K = coefficient of permeability - hf = average height of water above filter bed - tf = filter bed drain time (days) Af = 4500 ft2 Dimensions of Cell: 15’ by 300’
- 19. Components of Bioretention Cell ● Filter Fabric ● Gravel ● Mulch ● Plants ● Sand ● Soil Mix
- 20. Design of Bioretention Cell
- 21. Budget
- 22. Life Cycle Assessment: Ecological
- 23. Life Cycle Assessment: Ecological
- 24. Life Cycle Assessment: Economical ● Can decrease cost from storm water conveyance systems ● Maryland constructed 400 ft2 bioretention cell o 50% reduced drainage costs
- 25. Efficiency - Grading the parking lot 1% to have a slight slope towards the bioretention cell - Runoff will be diverted from the Clemson watershed - Filter and stop pollutants from getting into the groundwater
- 26. Alternate Designs - Porous Pavement - Water quality: pollutants captured - Volume reduction and flood control: water flows through the porous pavement reducing the overall volume of runoff - Road safety and Durability - increases skid resistance and pavement lifespan increases http://www.clemson.edu/extension/hgic/water/resources_stormwater/introduction_to _porous_pavement.html
- 27. Time-line
- 28. Looking Forward ● Cost estimates of native plants ● Run dimensions against 10 and 25 year storms ● City of Clemson stormwater management ● Design primary overflow
- 29. Questions?