OSU Extension is located on a site with Historic designation and as such, any changes to the site have to meet strict criteria. To date, we have been able to install two projects that meet these as well as city stormwater management manual criteria, managing over half of the large roof surfaces.
Both projects have been volunteer driven, from design to installation to maintenance, with two of the top regional native plant experts doing the planting plans for both stormwater facilities.
The first project made use of existing brick landscape planters on the north side of the building. All of the existing plants and soil were removed and replaced with appropriate soil and plants, and all 1,970 sq ft. of the north facing roofs were rerouted to these 475 sq ft. planters
The second project was designed by Lane Community College’s Stormwater Best Management Practices class which took advantage of the large lawn area to incorporate a teardrop shaped rain garden that manages just over 1,000 sq ft of the north facing roofs.
Restoration Techniques
Detention Pond and Swale: Original System designed to delay stormwater from the entire four-acre site, allowing particulates to drop out and dissolved pollutants to be treated by vegetation and soil before overflowing into adjacent Amazon Creek. The detention pond had filled in with sediment from the previous decade of use.
Tree Preservation and Planting: Provides a wildlife corridor between Amazon Creek and the adjacent wetlands in addition to providing stormwater management and urban heat island mitigation.
Rain Garden: Provides stormwater pretreatment from 11,000 sqft of the primary parking lot. Regardless of the twice daily vehicle leak checks, brakes and tires are a significant source of zinc which has been shown to kill salmon within minutes of exposure. It has also been shown that rain gardens are the cheapest and most effective method of removing heavy metals and other pollutants from stormwater.
Benefits
- Improved instream water quality – benefits fish, amphibians, and macro-invertebrates
- Reduction of urban pollutants – especially heavy metals and petrochemicals from entering Amazon Creek
- Reduction of erosion – by delaying the stormwater on site, the stormpulse pressure on Amazon Creek is reduced
- Wildlife habitat integration – native plants in urban landscapes benefit local song birds, pollinators, and wildlife
- Distinctive signage – highlights the sight as an example of Trout Friendly Landscaping, and reminds passersby, visitors, and employees that the water that falls on all urban sites is connected to trout habitat.