John Muir Elementary was built in 1970 and is named after the well-known naturalist and conservationist. In 2010, the Lake Washington School District decided to build a new K-5 elementary school, and wished to use sustainable, “green” design principles for the site and building to reflect the beliefs of the school’s namesake.
The project’s new site development involved the design of an efficient new stormwater system. To eliminate the high cost of underground detention vaults, consulting civil engineer Coughlin Porter Lundeen, working with geotechnical engineer AMEC Environment & Infrastructure, designed stormwater quality treatment within the catch basins before the water drained into the underground injection control (UIC) wells.
For the right stormwater management solution, Coughlin Porter Lundeen turned to Contech, with whom they have enjoyed a long, successful relationship. The Contech Stormwater Management StormFilter® was chosen because it removes the most challenging target pollutants — including soluble, heavy metals, oil, fine solids and total nutrients — using a variety of sustainable media. Contech’s StormFilter product has a proven, two-decade history, and is available in more than 30 configurations for use across the country. Two-year maintenance cycles mean fewer maintenance events throughout the lifetime of the system, and the one-of-a-kind, selfcleaning hood prolongs cartridge life and promotes long-term performance.
Contech worked closely with the consulting engineers to design a system specifically to meet this project’s unique needs. The new school infiltrates all stormwater onsite through 60-feet-deep UIC wells, drilled deep to infiltrate below a layer of impermeable soil strata 40 feet thick.
The UIC wells are located under catch basins and designed to accommodate the peak storm flow rate, eliminating the need for detention structures. Contech 42-inch and 72- inch diameter corrugated metal pipe (CMP) was used for concrete forms on the project.
Installing 17 retrofit StormFilter systems provided the water quality treatment required by local jurisdiction, as well as a cost savings over installing a large, underground detention facility.
“Contech was an excellent partner to assist us with this challenging stormwater project,” agreed J. Alan Jacobson, P.E., Associate Principal with Coughlin Porter Lundeen. “Through collaboration, we were able to come up with a custom and specific stormwater treatment design to allow the use of the UIC wells for the project.”
“Deep UIC wells were an effective low impact development (LID) tool for this site, with its limited space and low-permeability soils at the surface,” said AMEC Environment & Infrastructure’s Todd Wentworth, P.E., LG. “By placing the UIC wells under the catch basins and using Contech StormFilter kits, the project avoided the high cost of underground detention vaults.”