The Bolsa Chica Lowlands restoration project used vinyl sheet piling for groundwater barriers. Tests by the U.S. Army Corps of Engineers have concluded that vinyl sheet piling surpasses steel and wood in long-term durability because it is far less likely to corrode and succumb to parasitic infestations.

Adjacent to the famed surfing city, Huntington Beach, Calif., is the Bolsa Chica wetland ecosystem. After decades of environmental degradation, a restoration project covering about 1,247 acres has been taking place.

The effort is the largest, most expensive coastal wetland restoration project in Southern California, and the second largest construction project ever directed by the U.S. Fish & Wildlife Service.

A steering committee comprised of eight federal and state agencies coordinated the planning and design. Bringing the wetlands habitat back to life involved reconnecting the lowland areas to the ocean, allowing tides to flow into the marsh twice each day and creating a full tidal basin and managed tidal areas. Without these tides, the wetlands cannot support native plants and wildlife.

Elements of the restoration project included the design, construction and management of a muted tidal basin, pocket muted tidal basin, nesting islands and groundwater barrier. Initially a 4,500-linear-foot impermeable barrier wall was to be anchored into a low permeability silt/clay layer to prevent groundwater and salinity intrusion into the adjacent neighborhoods. A water extraction system on the neighborhood side of the tidal basin was added to control water levels in the neighborhood.

However, following subsurface modeling, a vertical barrier was chosen instead because it provided a positive cutoff against potential saltwater intrusion beneath the neighborhood and required an overall lower level of long-term maintenance than a linear drain-based system.

The U.S. Fish and Wildlife Service, along with outside engineers Moffat and Nichol, and prime contractor Kiewit Pacific (now called Kiewit Infrastructure West Co.), decided to construct the groundwater barrier from vinyl sheet piling manufactured by Crane Materials International, instead of using a traditional construction material such as steel.

According to the manufacturer, millions of feet of vinyl have been successfully used around the globe in residential, public and commercial projects and that the specific product, ShoreGuard325, has performed as intended since being installed at Bolsa Chica.

As further evidence of the project's success, the company states that several species of endangered birds have returned to this strip of coast in Huntington Beach.

Nearly one mile of the vinyl sheet piling was used. Installation was accomplished using CMI???????(R)???AE?????(R)???AE?s patented PileClaw installation equipment attached to a hydraulic, ABI pile-driving machine.