The Salt River Ecosystem Restoration Project (SRERP) is a multifaceted restoration project designed to restore ecological, geomorphic, and hydrologic function within the Salt River watershed, a tributary to the lower Eel River in Humboldt County, CA. Restoration activities within the project area will require excavation of an estimated 600,000 to 800,000 cubic yards of soil.
LACO provided engineering geologic, geotechnical, hydrogeologic, and topographic surveying services to support the project design. We provided the following services:
- Field exploration and soil sampling to characterize geotechnical and environmental soil conditions
- Definition of the limits of saline soils to support potential beneficial reuse options on agricultural lands
- Quantitative factor of safety slope instability analysis using Slide (version 5.0) to support design recommendations for both cut and fill slopes
- Quantitative settlement analysis of subgrade soils beneath proposed earthen berms
- Estimated seepage and soil moisture evaporation rates through in situ testing
- Topographic surveys of approximately 2 miles of channel with a robotic total station and RTK GPS to verify and supplement existing aerial mapping and photogrammetry
In preparing for the project, our team knew that excavated soils would be saturated and require moisture conditioning prior to reuse. We designed and implemented small-scale field tests to provide estimated moisture conditioning rates to support construction sequencing. Our team also knew that areas of proposed excavation would be below the water table and require management of nuisance water. LACO provided estimated seepage rates based on both in-situ aquifer testing and grain size analysis to help the project team address and manage excess water. Throughout the project, we utilized our cross-trained staff to accomplish multiple project tasks, reduce mobilization events, and increase productivity.
For more information about the Salt River Restoration project and its history, visit the Humboldt County Resource Conservation District’s website: https://www.humboldtrcd.org/SaltRiverProjectShortHistory.pdf