ABCs and BMPs

Aug. 28, 2009

Student populations continue to rise across the country, and school enrollment is projected to continue increasing through 2013. School districts from coast to coast are investing in new facilities or renovating and expanding their existing buildings. McGraw-Hill Construction is predicting an increase in construction activity and spending within the environmental sector over the next couple of years.

Although regulations vary by region and type of project, new construction or renovation and expansion designs almost always include a storm water management plan to protect downstream waterways. No two projects are alike, and with tight budgets and many solutions available, it is important to select a design approach that cost-effectively meets water quality goals and best fits a site’s unique needs. A few recent examples are highlighted below.

University Expansion Project

To accommodate its ever-growing program, the University of Southern California recently built a new facility for its School of Cinematic Arts in Los Angeles. The local regulatory agency required onsite infiltration of storm water runoff with pretreatment. Land was scarce, so efficient use of space was essential. Project Engineer KPFF Consulting Engineers, Los Angeles, chose a below-ground storm water solution in order to maximize the available land.

A ChamberMaxx infiltration system was installed. This corrugated, open-bottom plastic arch system from CONTECH is injected-molded using structurally efficient and corrosive-resistant polypropylene resin. A CDS system, also from CONTECH, will be installed upstream to remove solids, trash and debris. This pretreatment system will extend the life cycle of the ChamberMaxx system and significantly reduce maintenance costs.

Elementary School Parking Lot Renovation

Mission Park Elementary, located in Salinas, Calif., had severe parking and access issues. It needed a quick fix prior to the opening of the school year, and the site improvement project triggered a need for storm water management. The city required a low-impact development solution, so rainfall had to be managed on site using uniformly distributed micro-scale controls.

Project Engineer EDA Design Professionals, San Luis Obispo, Calif., faced a limited time frame and small footprint, so the group turned to CONTECH for assistance. Ultimately, two UrbanGreen BioFilter systems were specified and installed. This enhanced biofiltration system combines biological and engineered media filtration to effectively remove pollutants from storm water runoff. A key benefit to the system—and why the design engineers chose it—is its internal bypass, which eliminated the need for and cost of installing an external bypass and enabled the system to be placed anywhere on site.

Junior High School New Construction

Bethel School District is one of the fastest growing in the Puget Sound region. Part of a bond passed by voters included construction of Liberty Junior High in Spanaway, Wash. Because the state of Washington has some of the strictest storm water regulations in the country, storm water management was a factor.

The site of the new school was highly infiltrative, so rain gardens were designed for most of the water quality treatment. However, there were a couple of areas impossible to pick up. Project Engineer Coughlin Porter Lundeen, Seattle, specified two CatchBasin StormFilter systems from CONTECH. The catch basin systems utilize the storm water management StormFilter, which is the first proprietary best management practice to achieve General Use Level Designation approval from the Washington Department of Ecology. Siphon-actuated filter cartridges, which trap and adsorb pollutants, feature a surface cleaning system that prevents blinding and extends maintenance intervals.

Portable classrooms were added to the site later in the project, and a third CatchBasin StormFilter was installed to treat the additional impervious area.

About the Author

Becky Metivier