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Raceway Industrial

Carlsbad, California

Stormwater Management


W-H Carlsbad


 Thienes Engineering 


TFW Construction Development 


May 2023

Technical Description:

  • UrbanPond® Concrete Detention System
  • Modular Wetlands Linear® Bioretention System 

Raceway Industrial is an industrial logistics site located on 16.4 acres between interstates I-5 and I-15 in Carlsbad, California. Upon completion, a 222,959 square-foot warehouse space with loading docks will provide ideal service to the northern San Diego market.

The site is designed to maximize every square foot of warehouse space. This requires a complex grading plan with multiple retaining walls to create a level building pad, parking areas, and access routes for semi-trucks and trailers. Of course, this creates a lot of impervious surfaces that will generate stormwater runoff requiring treatment. The applications of Contech UrbanPond and Modular Wetlands contributed to the success of the Raceway Industrial project.

Thienes Engineering, located in La Mirada, contacted Contech Stormwater Solutions for their expertise in storing and treating the site's stormwater runoff. Two areas along the north and northwest borders were reserved as biofiltration basins. However, these areas were not large enough to store and treat the site's runoff. During the 100-year storm, the site is expected to generate over 71,000 cubic feet of runoff that must be detained to prevent flooding and damage to the site and adjacent properties. Surface-level solutions would take up too much of the site footprint and jeopardize the project's viability. Elevation changes and retaining walls further limited the options. The solution, proposed by Vicy Li of Thienes Engineering and Troy Frasure of Contech, was an underground storage system located beneath the northwest parking area.

Contech designed a highly efficient underground UrbanPond stormwater storage system with several site-specific features to meet the project's exact needs. The design holds 71,769 cubic feet of stormwater storage plus one foot of freeboard. Contech provided structural calculations, water quality calculations, and installation estimates to help the engineer better analyze the best cost-effective solutions for the site.

Water enters the UrbanPond system from four separate pipes that convey runoff from around the site and exits through a custom-designed outlet module. The 8-foot wide by 24-foot-long outlet module features six windows for high-flow bypass to allow large storms to flow through without causing flooding. A pair of low-flow orifices maintain the outlet flow rate to drain down the system over the required 72 hours. Each orifice is protected with a connector pipe screen (CPS) to prevent clogging. The storage system and outlet module are optimized to fit into a rectangular footprint, making excavation and installation fast and efficient for the general contractor.

The UrbanPond system is made from 123 precast concrete pieces as a stacked configuration with an inside height of 10'. The UrbanPond system included both 8'x8' and 8'x16' modules. Also included in the UrbanPond system was an 8'x24' outlet module with two 1.25" diameter orifices to convey low flows and a 28.5' total weir length for bypass 9' above the floor.

The final touch is a 4' x 6' Modular Wetlands Linear Biofiltration system located adjacent to the site's entryway. Runoff, which cannot be conveyed to the UrbanPond detention system, is routed to a catch basin and then treated via the Modular Wetlands system. The system is designed to treat 0.0613 cfs, fits seamlessly into the site's landscaping, and provides the last step of stormwater treatment for flowing offsite.

Installation took place over six days, and the modules were set using an All-Terrain Grove GMK5275 by Bragg Crane and the final installation day included setting the orifice plates and CPS screens over the outflow holes.

Contech reduced the cost of the system to meet the owner's financial requirements, provided a reliable system with ease of installation, and supported the contractors throughout the entire installation process.

Technical Description:

  • UrbanPond® Concrete Detention System
  • Modular Wetlands Linear® Bioretention System 

800-338-1122 |
Project #: 721286


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