Company:
City of Irvine
Status:
Awarded
Awarded:
Flood Management Project of the Year
Additional Files





Additional Information

Agua Chinon Corridor

Project Location:

The site is located on the former Marine Corps Air Station El Toro military base, located in central-western Orange County, California. The site consists of approximately 3,580 acres located within the city limits of the City of Irvine.

Project Description:

Agua Chinon Wash is an urban stream, flowing southwest from its headwaters in the foothills of the Santa Ana Mountains, through the city of Irvine, in Orange County, California. In 1942, construction of the El Toro Marine Corps Air Station (MCAS) began in Irvine. Runways and roadways to aid base operations were built, resulting in a mixed open culvert being constructed over the top of Agua Chinon Wash. In 1993, under the authority of the Defense Base Closure and Realignment Act of 1990, it was announced that MCAS El Toro would be closed. Operational closure of the MCAS occurred in July 1999.  In 2005, four parcels of land comprising the former MCAS El Toro were sold to Heritage Fields, LLC (a joint venture between a private developer and several other firms), with the intention of redeveloping the site to include residential, golf, commercial, schools and the Orange County Great Park.

As part of the site redevelopment, the Agua Chinon Wash regional flood control channel (OC Facility No. F18) was completely re-envisioned as an open-space corridor, designed to be integrated into the community and the surrounding natural environment.  The Agua Chinon Corridor was designed to incorporate flood conveyance, natural open-space, environmental restoration, and passive recreational uses into an open-space spine which traversed the community and Great Park areas.

The Agua Chinon Corridor was designed to function as a natural drainage channel that can handle ultimate condition 100-year flood events while providing an associated riparian corridor and trail system that traverses the community. The establishment of this open-space corridor provides an opportunity to address specific needs generated by the Heritage Fields project, including:

• Mitigation for impacts to jurisdictional waters;
• Flood control/flood conveyance;
• Recreational trails and public information; and
• Natural functions and values including habitat, water quality, and hydrologic functions.

The project was designed and constructed in four (4) phases, and included a total length of approximately 1.7 miles.  The last phase of the Agua Chinon Corridor was completed in 2018.

The consultant team provided planning, hydrology, hydraulic, and sediment transport technical studies for development of the final system design, regulatory permitting for the construction, and native re-vegetation for the stabilization and restoration of the wash.  Twenty-plus acres of potential area available for wetland and riparian habitat were identified within the Agua Chinon Corridor, including a low-flow channel that would be flooded by up to two-year events, plus two additional terraces/zones that would be inundated between two- and ten-year events and ten- and 100-year events. The project included the reconstruction and restoration of the eroded existing channel through the use of grade control structures, re-grading the channel in tiered sections, removal of triple Reinforced Concrete Box (RCB), and the removal of invasive, non-native plant species.  As the rehabilitated Agua Chinon Corridor was designed to traverse areas that were covered by a series of runways associated with former military base uses, portions of the runways were removed and associated remediation was conducted. Grade control structures were installed to prevent future hydromodification including scour and low flow erosion and to allow the passage of a 100-year storm. Grading and native planting plans were prepared for the wash to rehabilitate the stream to a more natural condition.

The Agua Chinon Corridor was designed and constructed to function as riverine/riparian habitat providing functions and beneficial uses typically associated with natural riparian areas such as, conveyance of storm water discharge, energy dissipation, short-term storage of surface water, nutrient cycling, retention of particulates, natural wetland water quality function (removal of imported elements and compounds), and provision of habitat for a variety of invertebrates and avifauna.

The Agua Chinon Corridor provides wildlife habitat and related beneficial uses. The
vegetated stream channel and associated riparian corridor will provide habitat for invertebrates, amphibians, avifauna and associated prey species as well as foraging areas for larger wildlife species (including raptors). In addition, these natural, vegetated areas would provide cover, shelter and foraging areas for resident and migrating wildlife species as well as nesting and resting areas for resident species.

Project Justification:

The Agua Chinon Corridor is a successful example of reimagining a single use flood control channel as an open-space stream corridor with multiple beneficial uses including ecosystem restoration, habitat mitigation, passive recreational facilities, and flood conveyance.  The existing degraded channel system was upgraded to its ultimate design capacity and integrated with the surrounding natural and built communities to provide an example of sustainable engineering.

Special Circumstances:

The concept, design and construction of the Agua Chinon Corridor was made possible through an innovative public-private partnership between the City of Irvine and FivePoint’s partnership (Heritage Fields El Toro, LLC). Delivering on the goals and promises to the community for the redevelopment of the former Marine Corps Air Station El Toro has required public and private partners to work hand-in-hand to create multiple civic benefits. The Agua Chinon Corridor project upholds those goals and promises, providing the Orange County Great Park and the surrounding communities with an open-space stream corridor with multiple beneficial uses including ecosystem restoration, habitat mitigation, passive recreational facilities, and flood conveyance.

Project Attachments:

Marketing video prepared by the gabion structure vendor (Maccaferri), depicting the Agua Chinon Corridor project: https://vimeo.com/266981121

Award Citation::

The Agua Chinon Corridor project was a successful effort in reimagining, designing and constructing a multi-purpose open-space stream corridor, providing 20+ acres of habitat restoration, passive recreational facilities, as well as construction of the ultimate design for the flood control/flood conveyance channel.

Suggested Award Summary:

As part of the Heritage Fields El Toro Project, which is comprised of redevelopment of the former Marine Corps Air Station El Toro military base, the Agua Chinon Wash regional flood control channel (OC Facility No. F18) was completely re-envisioned as an open-space corridor designed to be integrated into the community and the surrounding natural environment.  The Agua Chinon Corridor was designed to incorporate flood conveyance, natural open-space, environmental restoration, and passive recreational uses into an open-space spine which traversed the community and Great Park areas.

The Agua Chinon Corridor was designed to function as a natural drainage channel that can handle ultimate condition 100-year flood events while providing an associated riparian corridor and trail system that traverses the community. The establishment of this open-space corridor provides an opportunity to address specific needs generated by the Heritage Fields project, including:

• Mitigation for impacts to jurisdictional waters;
• Flood control/flood conveyance;
• Recreational trails and public information; and
• Natural functions and values including habitat, water quality, and hydrologic functions.

The Agua Chinon Corridor was designed and constructed to function as riverine/riparian habitat providing functions and beneficial uses typically associated with natural riparian areas such as, conveyance of storm water discharge, energy dissipation, short-term storage of surface water, nutrient cycling, retention of particulates, natural wetland water quality function (removal of imported elements and compounds), and provision of habitat for a variety of invertebrates and avifauna.

The Agua Chinon Corridor provides wildlife habitat and related beneficial uses. The
vegetated stream channel and associated riparian corridor will provide habitat for invertebrates, amphibians, avifauna and associated prey species as well as foraging areas for larger wildlife species (including raptors). In addition, these natural, vegetated areas would provide cover, shelter and foraging areas for resident and migrating wildlife species as well as nesting and resting areas for resident species.

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