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Rivergate Phase V

Portland, Oregon

Owner:

Trammell Crow Company

Engineer:

Mackenzie

Contractor:

Tapani Inc.

Installation:

January 2018

Technical Description:

  • (2) StormFilter Panel Vaults
  • (1) Peak Diversion StormFilter
  • (2) StormGate Diversion Vaults

Rivergate Corporate Center is a multi-phase project located at the confluence of the Columbia and Willamette rivers and nine miles northwest of downtown Portland. It is Oregon’s primary gateway for international trade.

This phase of the build-out consisted of the design and construction of a distribution and fulfillment center for a large internet retailer and cloud computing company. The facility is expected to bring 1,000 full-time jobs where workers will coordinate reception and delivery of items from manufacturers to customers. The goal of the new facility is to drastically decrease delivery times to Portland-area customers.

The addition of nearly 43.5 acres of new impervious surface at the site required treatment of stormwater runoff for pollutants, primarily sediment.  Engineers at Mackenzie followed the City of Portland’s 2016 stormwater management manual standards, which resulted in the requirement to treat for over 6 cfs of total peak design storm flow prior to outfall into the Columbia River.

Contech and Mackenzie worked together to assess the best solution for treatment and determined the Stormwater Management StormFilter was the best option from both a feasibility and cost position. The StormFilter is a stormwater treatment device that uses rechargeable, media-filled cartridges that trap particulates and adsorb pollutants such as dissolved metals, hydrocarbons, nutrients, metals, and other common pollutants found in stormwater runoff.

Two 11’x29.5’ panelized vaults with StormFilter cartridges were installed to treat nearly the entire site. Of the 35 acres treated by these vaults, the building roof alone contributes 21 acres to the overall drainage area. The vaults were placed offline using two, 48” StormGate flow control manholes that incorporate an orifice control and an adjustable weir to limit the flow to the filters to the approximate maximum treatment flow rate while diverting excess peak flows around the filter vaults.

On an adjacent site, an 8’x14’ Peak Diversion StormFilter was installed to treat another 4.4 acres. The Peak Diversion StormFilter provides treatment and high flow bypass in one precast vault, eliminating the need for an external bypass or junction structure. 

The three vaults were equipped with 184 cartridges filled with Perlite, a form of expanded volcanic rock. Perlite’s porous, multi-cellular structure and rough edges make it effective for removing TSS, oil, and grease.

Contech assisted with preliminary design, providing sizing and structure selection guidance to ensure the most cost-effective solution was selected. Contech also provided annual maintenance cost estimates.

The panel-formed vaults  arrived at the site in separate pieces, with the base slab on a “super load” truck that occupied two lanes and required escorting cars. The contractor assembled the vaults, with Contech providing on-site field support. Each panel vault was assembled and installed in a matter of hours, with the StormGate manholes and peak diversion vault being installed at later dates. Per the contractor’s request, the StormFilter cartridges were delivered and installed several weeks later in order to reduce the risk of construction flow reaching the filters and compromising the longevity of the new media.

With the help of Contech’s field support staff, the StormFilter structures were equipped with filters and placed online once the site was stabilized. At that point, the site was fully prepared to treat and convey the stormwater runoff from its drainage basins. Overall, the design and installation was trouble-free and Contech provided a cost-effective and complete stormwater management solution in a timely fashion.

Technical Description:

  • (2) StormFilter Panel Vaults
  • (1) Peak Diversion StormFilter
  • (2) StormGate Diversion Vaults

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