2022 Project of the Year Winner – CSP & Pipe Arch: Premier Storage – Hazel Dell

By: Contech Engineered Solutions, LLC

stormwater management system underground stormwater detention system

A 2,000-unit self-storage facility being built in Vancouver, WA required a robust stormwater management system. The original design called for Filterra Bioretention systems to treat the water before being conveyed to a stormwater pond. However, the county, required a more stringent discharge limit which drove the pond to be too large for the given site.

Engineers contacted Contech to provide an underground solution to fit a unique footprint. A uniquely-shaped 72-inch diameter corrugated metal pipe underground stormwater detention system was designed to store over 35,000 cf (262,000 gal) of stormwater. The system was carefully designed to avoid two proposed buildings on an oddly-shaped parcel.

stormwater management system underground stormwater detention system

Three Filterra Internal Bypass Curbs were insta lled at various locations to capture and treat the stormwater before entering the underground detention system. The Filterra Internal Bypass Curb incorporates a curb inlet treatment chamber and internal high flow bypass in a single structure. This eliminates the need for a separate bypass structure and enables placement in a “sag” or “sump” condition.

stormwater management system underground stormwater detention system

“The Hazel Dell premier storage project presented a lot of stormwater challenges, said John Megrditchian, P.E., Project Manager, at AAI Engineering.” “We were working with a limited footprint but still needed to maintain Department of Ecology’s stormwater detention standards. Contech’s CMP provided the perfect stormwater storage solution for a site that had a tight footprint and even tighter stormwater regulations. Due to it’s customizable arrangement and storage efficiency we were able to meet the site needs.”