Location and Description
Brea Dam is a flood risk reduction project located in Fullerton, about 22 miles east of Los Angeles, on Brea Creek approximately one-half mile from the intersection of State Highway 72 and Brea Boulevard.
Brea Dam impounds 22 square miles of drainage from Brea Creek and its tributaries. Below the dam, the creek flows southward through the central business district of Fullerton, where it turns westward to join Coyote Creek, a tributary of the San Gabriel River.
Construction on the Brea Dam began in July 1940 and ended in March 1942. Brea Dam, one of the units of the flood risk reduction project for the San Gabriel River Basin and Orange County, was authorized by the Flood Control Act of 22 June 1936.
Dam Safety Issues
The primary objective of the Corps’ Dam Safety Program is to maintain public safety by making sure dams owned and operated by the Corps are safe, and the risks to the public are minimized. An integral part of the program is the risk-informed screening process. Dams are classified based upon confirmed or unconfirmed dam safety issues, the combination of life or economic consequences should failure occur and the probability of failure. This process enables us to prioritize dam safety actions to correct deficiencies, which include interim risk reduction measures to be undertaken while further investigations are conducted and remedial actions are implemented.
Brea Dam received a Dam Safety Action Class III, or DSAC III, rating in March 2009 based on a Screening Portfolio Risk Analysis, or SPRA, completed in May 2008. A DSAC III rating is given to dams where the dam is significantly inadequate, or the combination of life, economic or environmental consequences with probability of failure is moderate to high.
Brea Dam received a DSAC III rating because of the potential for:
- Failure from seepage and piping through internal drain at foundation/embankment contact at main embankment.
- Failure from seepage and piping along conduit through main embankment.
- Failure of saddle dike due to seepage and piping along or through corrugated metal pipes penetrating the saddle dike.
- Failure from overtopping of a Project Maximum Flood.
- Failure from erosion of downstream spillway channel.
As a result of Brea Dam’s DSAC III rating, the Corps has implemented the following Interim Risk Reduction Measures, or IRRMs:
· Inspection and monitoring by the Special Dam Inspection Team (SDIT) when the pool elevation reaches trigger elevations of 252 ft NGVD. The frequency of inspection and monitoring increases with increasing pool elevation.
· Awarded in advance an emergency response contract to perform flood fighing operations and emergency repairs, if needed.
· Update the emergency action plan annually
· Conduct a video inspection of the three saddle dike corrugated metal pipes in 2014
· Conduct a video inspection of the Main Embankment Internal Drainage System in 2014
· Conduct a study for pre-positioning of materials utilized for emergency operations in 2014
· Conduct an orientation seminar for a dam safety exercise by 2016
· Update flood mapping by 2017
· The Corps will conduct an Issue Evaluation Study (IES), based on the national priority list and availability of future funding, to be completed approximately one year after initiation, in order to reevaluate the Lopez Dam DSAC Rating.
· If modifications are needed to address potential failure modes at the dam, the Corps will begin a Dam Safety Modification Study (DSMS) to be completed approximately 36 months after initiation.
Public Safety is Number One Priority
Public safety is our number one priority. While we cannot completely eliminate risk, we can reduce it. Our screening and classification of Brea Dam does not mean that failure is taking place. It means we have identified dam safety issues that don’t meet industry standards and the risk to public safety is unacceptable. Routine inspections and operation of the dam will continue and emergency action plans have been developed in coordination with local emergency management officials. Currently, there is no evidence to suggest an emergency situation exists or is about to occur.
The U.S. Army Corps of Engineers owns and operates 694 dams that serve a variety of purposes, including navigation, flood damage reduction, water supply, irrigation, hydropower, recreation, environmental enhancement and combinations of these purposes. As part of our responsibility in managing these dams, the Corps has a comprehensive Dam Safety Program that has public safety as its primary objective. Corps dams are routinely inspected and continually evaluated for safety in compliance with the Federal Guidelines for Dam Safety issued in 1979 and Engineering Regulation ER 1110-2-1156, Safety of Dams – Policy and Procedures.