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La Quinta Inn

Portland, Maine

Stormwater Detention


La Quinta Inn


Acorn Engineering


CLH & Sons, Inc.


December 2017

Technical Description:

  • 1,598 LF of 84" and 96" perforated Aluminized Steel Type 2, 14 GA

La Quinta Inns & Suites suffered from frequent flooding in their parking lot which caused damage to the building and hindered service to customers. To alleviate this issue they sought guidance from Acorn Engineering to design a solution to the problem.

Acorn suggested the construction of a stormwater detention system under the parking lot. The addition of the subsurface infiltration would provide adequate storage for the design storm and minimize future impacts due to flooding.

The original specification called for plastic crates. Contech recommended a corrugated metal pipe (CMP) solution as an alternative to the crates. Fitting the volume of water in the small footprint made large diameter (84” and 96”) CMP an attractive option. The use of the large diameter pipe allowed for a smaller footprint, less excavation and backfill, and a faster installation. Installation of the plastic crate system was estimated at 40 days, while installation of the CMP system was estimated to take less than half that time. As a result, the contractor, CLH & Sons., Inc. was able to save approximately $130,000 over the specified plastic crate system.

The detention system consisted of 581 LF of 84" and 1,017 LF 96", 14 gage, perforated Aluminized Steel Type 2 providing 100,283 cf of storage. Twelve barrels were fabricated of various length to accommodate the footprint of the site.

The original design of the plastic crates had very small inspection ports that would allow for only minimal maintenance of the system. The CMP design provided three, 36” risers for complete maintenance access which will help to prolong the life of the system.

"Acorn appreciated partnering with Contech to develop a design alternative using large diameter CMP compared to high void stackable crates," said Mark Arienti, Senior Environmental Engineer with Acorn-Engineering. "The crates would have required onsite assembly by the Contractor. Considering the design included 750,000 gallons of detention, Contech’s CMP system required significantly less labor to install by utilizing the Contractor’s onsite equipment."

In the end, Contech reduced the cost of the originally designed system to meet financial requirements, provided a reliable system with ease of maintenance, and supported the contractors throughout the entire installation process.

Technical Description:

  • 1,598 LF of 84" and 96" perforated Aluminized Steel Type 2, 14 GA

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