San Timoteo Creek Fluvial Study & Specialized Bank Protection/Restoration
PACE performed an engineering investigation that estimated the anticipated long-term streambank erosion limits and identified creek stabilization alternatives. The study included a portion of the San Timoteo Creek extending upstream from the confluence with Coopers Creek, traversing the entire length of the Heartlands development project. The technical analysis to evaluate the river engineering and stream erosion followed multiple procedures adopted by other agencies, including recommendations outlined by FEMA. The estimated lateral streambank erosion limits were identified based upon the results of the: (1) geomorphic, (2) historical, (3) geotechnical, and (4) hydraulic / sediment transport engineering analyses of lateral stability. The streambank engineering report was used as the basis to generate the final improvement plans for the stabilization improvements and provide technical documentation for the environmental reports. The stabilization improvements included soil cement streambank revetments along a one-mile portion of the San Timoteo Creek north and south banks. The 4,950 lineal feet of the north bank revetment was designed to allow floodwaters greater than the 2-year storm to overtop the revetment and enter the habitat restoration area. The 5,700 lineal feet of the south bank revetment was designed to provide long-term erosion protection from lateral migration of the bank and 100-year flood protection from the 11,680 cfs flowrate for the adjacent proposed development area.