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2021 Project of the Year Winner – Retention & Detention: Rialto Fulfillment Center

By: Contech Engineered Solutions

retention detention system stormwater managementA new distribution center complex was built in Rialto, California, to meet the growing demands of online shoppers. The site is over 120 acres and includes two buildings, each with over 1 million square feet of building space. The site also includes parking for 1,000 vehicles, over 900 off-dock trailer stalls, and 100% site concrete paving.

Developing and constructing a stormwater management system for a site of this size was a daunting task. There was initially a large retention basin, but due to the cost of land in southern California, the owner wanted to convert this area to a parking lot to optimize land use. The new direction prompted a shift to subsurface infiltration. Given the available depth, the most economical material to store this enormous amount of stormwater was a large diameter corrugated metal pipe (CMP) solution.retention detention system stormwater management

Initially 144” diameter CMP was considered, but through collaboration the team recognized an opportunity to decrease the footprint of the system. Having been manufacturing CMP pipe for nearly 100 years, Contech was able to produce this large diameter pipe while still ensuring its structural integrity.

The hole for the infiltration pit was already excavated, so Contech Stormwater Design Engineers had to fit the volume into the given footprint. Contech worked closely with Thienes and Boudreau throughout the project, providing value engineering estimates and storage calculations for multiple pipe diameters.

retention detention system stormwater managementA total of 11,100 LF of 162” diameter, perforated CMP was used, providing 1,588,038 CF of storage in the pipe. An additional 1,368,742 CF of storage is provided from the stone backfill. The system was made with 26 runs, ranging from 75’ to 698’ connected via a 60” manifold.

To meet the storage requirements and reach permeable soils, 10’ of rock was used below and 3.5’ above the pipe, resulting in the use of 240,000 tons of clean crushed stone.retention detention system stormwater management

A Contech Project Coordinator worked closely with Boudreau on the staging of the CMP material on-site to facilitate a seamless fabrication/delivery with the installation. The coordinated effort was to ensure enough material was available on-site to meet the 500 LF minimum production goal per day.