JCCC Campus Stormwater Project: Retrofitting Yesterday s Parking Lots With Today s Best Management Practices

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1 JCCC Campus Stormwater Project: Retrofitting Yesterday s Parking Lots With Today s Best Management Practices

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4 JCCC CAMPUS SUSTAINABILITY o Student self-imposed green fee for campus wide sustainability o ARRA funding

5 Project Goals o Significantly reduce the pollutants and concentration of run-off o Create a laboratory for JCCC and a demonstration for the larger public o Don t overextend beyond campus s maintenance resources PBA to send o Plant native species for habitat o No loss in parking quantities

6 Pre-Construction Conditions o 14-acre watershed o 11.5 acres of paved parking o All surface water was piped south to Indian Creek o Existing detention basin was originally designed to attenuate larger storm events

7 Strategies o Divert rain s first flush, which contains a majority of pollutants to bioremediation areas o Slow water allowing soil and plant roots to naturally filter pollutants o Find opportunities to daylight the existing underground system o Target key areas where the biggest impact is made for the investment in maintenance. PBA to send o Provide overflow paths back to original system for larger storms

8 Proposed Plan Overview A. Bioswales B. Bioretention Cells C. Manufactured Filtration Units D. Forebay E. Vegetated Submerged Bed (Constructed Wetland) F. Extended Dry Detention Basins

9 Treatment Areas Bioswales o Linear islands with multiple curb cuts o Water conveyed to next treatment area

10 Treatment Areas Bioretention Cells o Detention avoids stagnant water and heaving opportunities o Utilized drainage wicks to slowly drain water back in to storm pipes o Offers emergency overflows back to original system

11 Manufactured Containment Units o Packaged wetland o Offers treatment opportunity in smaller islands

12 Treatment Areas - Forebay o Energy dissipater before entering wetland o Convenient litter removal

13 Vegetated Submerged Bed Wetland (VSBW) o Modified from existing detention basin o Most effective removal of nitrogen, phosphorus, oil and grease, other chemicals o Submersed condition ideal for campus and residential setting o Lower basin overflows to adjacent dry basins PBA to send

14 Vegetated Submerged Bed Wetland (VSBW)

15 Vegetated Submerged Bed Wetland (VSBW) Evapotranspiration/ Evaporation Inflow 4 Decorative Gravel Topsoil Infiltration 18 Aggregate Infiltration

16 Vegetated Submerged Bed Wetland (VSBW) WIER MAINTAINS WATER LEVEL IN SUBMERGED BED

17 Vegetated Submerged Bed Wetland (VSBW) Water Quality Pool

18 Vegetated Submerged Bed Wetland (VSBW) Moderate Storm Event

19 Vegetated Submerged Bed Wetland (VSBW) 25-year Storm Event

20 Native Plantings o Budget allowed for plants in lieu of seeding o Over 56,000 plants over 2.5 acres o Xeric and mesic species o Consistent border of grasses offset from curb PBA to send

21 Other Components o Outdoor Classroom o Interpretive Sign o Pervious Concrete

22 Construction Strategies o Work downstream to minimize contamination o Install curb cuts near end of work to reduce washout o Mixed engineered soils on site- percolation rates tested

23 Construction Challenges o Inclement weather extended construction schedule from July to October o Plantings were stored on-site in a refrigerated truck o Manually irrigated during peak of summer months

24 Construction Challenges July Flood o 4 inches over 3 hour period (25 year storm event) o Recently laid mulch clogged principal spillway sending mulch wattles and many plants over emergency spillway

25 Construction Challenges July Flood o Measures Taken Afterwards o Temporary weir o Revised grates

26 A Transformed System

27 Benefits of Retrofitting o Improved water quality downstream o Reduced peak flows o Increased native habitat o Public awareness of natural stormwater treatment methods o Aesthetic value