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

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

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

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

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

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

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

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

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

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

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

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

Vegetated Submerged Bed Wetland (VSBW)

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

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

Vegetated Submerged Bed Wetland (VSBW) Water Quality Pool

Vegetated Submerged Bed Wetland (VSBW) Moderate Storm Event

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

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

Other Components o Outdoor Classroom o Interpretive Sign o Pervious Concrete

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

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

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

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

A Transformed System

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