CME.14 – Santiago Creek Slope Stabilization in Orange County, California

• Andrew Ahmeti
• Aleah Brown
• Julianna Dinkha
• Starish Enonuya
• Cesar Nunez
• Michael Yonker

Flooding along the Santa Ana River, particularly along Santiago Creek, has been documented by project client Orange County, California, dating back to 1897. Large peak flow flooding events in 1938 and 1969 have previously been responsible for hundreds of deaths and millions of dollars in property damage. California has recently suffered from large-scale flooding due to unseasonably high precipitation. This project aims to minimize the hazards that Orange County residents could face during their next high water event. The scope of this project includes developing several slope stabilization design alternatives for water retention basins located near the city of Villa Park. The existing slopes are steep and are subject to sloughing and failure, particularly during high water events. The US Army Corps of Engineers (USACE) maintains that the reservoirs be modified to fill more often, thereby reducing downstream flooding and increasing water infiltration in this area. USACE also plans to improve the channel connected to the basins to further reduce flooding downstream; however, the scope of this project focuses on stabilizing the slopes of the basins. The project design process entails evaluating the basins’ cross sections using LIDAR data and available soil borings. Initial geotechnical analyses will provide a rationale for why steep slopes are presently stable and what impact the proposed project will have on these slopes. Proposed stabilization methods will include regrading, soil anchors, and soil nails at a minimum. Barring any time constraint issues, the project calls for an exploration of alternative designs for each subregion, which the USACE has identified as the Bond Pit, the Blue Diamond Pit, and the Smith Basin. These three subregions comprise the main reservoir, so they will all need to be considered when developing designs. Computer-aided design (CAD) drawings will be created for each proposed design alternative, as will cost analyses. Successful completion of this project will result in less frequent flooding of the residential area downstream from the reservoir in an attempt to prevent additional property damage or potential loss of life. Nearby residents can rest easy knowing that future floods will be mitigated because of the Corps’ handiwork.