Water quality protection and conservation have been major concerns of The Irvine Company during four decades of developing model communities on The Irvine Ranch. This tradition continues with long-range planning for the East Orange project, which has included a comprehensive Environmental Impact Report for runoff management issues and the development of a master plan to prevent flooding and maintain the quality of water in this region.
The Irvine Company consulted with scientific experts, public officials, government agencies and environmental groups, as well as community members, in developing the solutions outlined in two Runoff Management Plans (ROMPs)-one for Santiago Hills II/East Orange Planned Community Area 1 and the other for East Orange Planned Communities Areas 2 and 3. These solutions reflect an innovative approach that combines natural processes-creating landscaping features to remove pollutants from runoff, for example-water quality basins and vegetated swales.
The wide array of solutions constitutes a state-of-the-art "treatment train"-a carefully planned series of measures designed to manage the volume, rate and quality of stormwater runoff to protect receiving waters that could be impacted by development.
These solutions meet or exceed all requirements for flood control and water quality while also protecting habitat and preventing erosion. The ROMPs achieve all the objectives outlined by the City Council of Orange and also respond to feedback from the community that was received after the plans were made available to the public for review. The County of Orange has reviewed the ROMPs and has agreed that they address and satisfy all the concerns raised by the county regarding water quality and runoff management.
These plans ensure that the new communities east of Orange will not cause any significant environmental impacts to Irvine Regional Park or Irvine Lake and will not exacerbate existing water quality issues at Peters Canyon Reservoir.
Among the measures outlined in the ROMPs are:
- Existing eroding channels that flow into Peters Canyon Reservoir will be stabilized and restored, and storm flows will be diverted around sensitive natural drainages and wetlands to prevent erosion and protect habitat.
- Sensitive riparian habitat along Limestone Creek and Santiago Creek will be preserved and protected with buffer zones.
- To prevent flooding in improved areas of Irvine Regional Park during all storm frequencies, flows will be rerouted to locations upstream and downstream of the improved portion of the park.
- The existing flooding of Jamboree Road near Peters Canyon Reservoir will be eliminated and a 100-year flood protection will be provided for this major roadway.
In an extra step to address concerns about water quality at Peters Canyon Reservoir, The Irvine Company has offered to provide the County of Orange with a sophisticated aeration system which they have accepted. This system would pump air into the water to alleviate the problem of stagnation that is caused by the low level of dissolved oxygen in the reservoir.
Best Practices
A wide range of Best Management Practices (BMPs) will be used to ensure that the East Orange project will have no adverse impacts on water quality, flood control or habitat. These BMPs are proven techniques that represent the most effective strategies available to address the particular challenges in this project area.
The overall runoff management strategy includes a variety of treatment controls to remove pollutants before runoff reaches downstream water bodies. These range from techniques such as bioretention and vegetative swales, which use natural processes to absorb and cleanse water, to structures such as Hydrodynamic Separator Systems, which remove sediment and other pollutants from runoff.
Solutions also include extended detention basins, which are areas where the land is excavated to create a basin that collects and slowly releases stormwater. When the basin is full, water is released over a 36-hour period. This allows sediment and pollutants to settle so they won't be washed downstream.
Extended detention basins are considered one of the most effective ways of treating urban runoff. The Irvine Company has set aside a total of about 18 acres of land throughout the project area to create a network of extended detention basins that will help improve water quality in this watershed.
To learn more about the ROMPs, go to click here
