Situated along the Los Angeles River and slightly over three miles from downtown Los Angeles, the 24-acre site known as Parcel C at Taylor Yard was once lush farmland as part of the Rancho San Rafael and, later, a major hub for the Southern Pacific Railroad.

This highly prized site is being transformed into a transit-oriented mixed-use development with 30,000 sq ft of retail and 401 new units, including affordable housing. It is currently being designed as an intricate network of pedestrian-friendly streets and blocks around a central linear green “alameda” that connects a new retail street to the 40-acre public park west of the site. The project’s proximity to the Los Angeles River and ongoing plans for its revitalization present an opportunity for new ways of thinking about similar sites throughout the Greater Los Angeles region.

The first two structures being built on the site are the Taylor Yard Apartments and Rio Vista Apartments, which will consist of 155 units of affordable rental housing for families. Future phases will consist of mixed-use space, as well as additional affordable rental housing for seniors and market-rate homeownership opportunities.

The problem

The civil engineers on the project, Hall and Foreman, needed to meet local storm water retention sizing requirements while maximizing the available land space at the site. The City of Los Angeles promotes LID design, so the engineer for this project first looked at infiltration to meet the storm water regulations. But when infiltration was not a viable option for some portions of the site, they turned to rainwater harvesting to retain the water onsite for these areas, with the added long-term benefit of reducing the potable water demand for the site’s irrigation system.

The initial retention design progressed to include rainwater harvesting. Ultimately, a unique hybrid rainwater harvesting/detention system with pretreatment and overflow treatment was designed. This solution would meet all the project requirements while staying within budget.

The solution

An UrbanGreen rainwater harvesting system consisting of a cistern made from 145 linear ft of 120-in.-diameter DuroMaxx steel reinforced polyethylene (SRPE) was installed on Lot 7. DuroMaxx was chosen because it provided the ability to create a large-diameter, economical, long-lasting cistern with watertight joints.

The cistern is designed to hold 168,300 gal of harvested rainwater that will be used for drip irrigation. Contech provided a turnkey solution by also providing all the pumps and controls needed to run the system.

For Lot 8, Contech provided a watertight metal cistern using 43 ft of 144-in. aluminized metal pipe with a proprietary watertight coating. This cistern holds 36,375 gal of water, which is also used for drip irrigation.

Contech also provided two CMP detention systems using 773 liner ft of 120-in.-diameter CMP and 192 linear ft of 114-in.-diameter CMP, all coated with aluminum to fulfill the surface area and active storage area requirements.

The Lot 7 and Lot 8 systems were designed with CDS units for pretreatment of the water before it enters the cistern and overflows to the detention systems. The CDS system uses a combination of continuous deflective screening, swirl concentration and gravity to remove sediment, trash and oil and grease from storm water runoff.

If the cistern and detention system are full, water will overflow to the peak diversion StormFilter, where it will receive polishing treatment before discharging to the storm drain system. The StormFilter system works by passing polluted storm water runoff through filter cartridges designed to remove trash, sediment, oil, nutrients and heavy metals.

The rainwater harvesting system for Lot 7 was designed to irrigate roughly 20,300 sq ft of landscaping and save over 122,800 gal of potable water per year. The Lot 8 system was designed to irrigate 20,800 sq ft of landscaping and save over 125,850 gal of potable water per year.

The result

The Taylor Yard Transit Village is an LEED for Neighborhood Development pilot program that integrates the principles of smart growth, urbanism and green building into the first national system for neighborhood design. The program emphasizes elements that bring buildings and infrastructure together and relates the neighborhood to its local and regional landscape. The Contech UrbanGreen rainwater harvesting and storm water management systems play an essential role in this initiative at the Taylor Yard site.

“The Taylor Yard Transit Village project presented unique storm water retention and treatment challenges, for which the Contech rainwater harvesting system provided the best solution,” said Deering Volkmann Viola, P.E., associate project manager at Hall and Foreman. “This system not only works with the project’s close proximity to the L.A. River and the complexities with regards to its history as a rail yard, but also utilizes available underground space, so the project esthetics were not impacted. Employing this system provided irrigation demand savings and was installed within the anticipated budget. The Contech team was consistently available for design consultations and [was] present throughout the installation process. We will definitely recommend this product on future projects.”