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iTech Preparatory School

Vancouver, Washington


City of Vancouver


Harper Houf Peterson Righellis 




April 2019

Technical Description:

  • 220' of 96" Aluminized Steel Type 2
  • (375) ChamberMaxx® stormwater chambers
The new 80,711 square-foot iTech preparatory school building unites middle and high school students for the first time since the STEM program in Vancouver, Washington, started in 2012. Now, all 400 students are under the same roof, with space for another 300 students.

The project included two detention basins, one under the north parking lot and one under the south parking lot.

The detention system's initial design in the north lot included plastic chambers that use geotextiles for pretreatment. The contractor reached out to Contech for an alternative, as they were looking for a solution that would reduce excavation and installation costs while still meeting the regulatory requirements. A Contech Stormwater Design Engineer developed a corrugated metal pipe (CMP) solution that met all of these goals.

Because of their shallow profile, chamber based stormwater detention systems require a substantial footprint. Also, each chamber has to be set by hand, which can be a time-consuming process. If soil conditions allow, large-diameter CMP systems almost always provide cost savings, as it requires much less excavation and installation is fast using standard construction equipment.  

Contech's solution consisted of 220' of 96" diameter aluminized CMP. The first 24' was solid wall CMP with a weir and draw down pipe used to mimic a county approved land-based pretreatment BMP. The remaining 196' of CMP was perforated to allow for infiltration. The system provides 23,500 cf of storage (including the stone backfill).

The Contech solution was first discussed with the county, which deemed it acceptable.  Contech was then able to confidently partner with the engineer of record to remodel the systems using our alternates.

The basin at the south lot is where the site connects to the public mainline. This portion of the site did not have the available depth for CMP, so 375 ChamberMaxx chambers were used. This system provides 39,000 cf of storage (including the stone backfill).

The project highlights one of the key benefits of working with Contech – a locally based, knowledgeable team that develops solutions that meet regulatory requirements while also saving customers money.

Technical Description:

  • 220' of 96" Aluminized Steel Type 2
  • (375) ChamberMaxx® stormwater chambers

800-338-1122 |

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