Sweetwater Authority Reservoir, CA
Ninyo & Moore, a SOCOTEC Company, provided geotechnical and environmental services for sediment management at the Sweetwater Authority Reservoir in Spring Valley, California, as part of our on-call contract with Sweetwater Authority.
Key Information
Project Name: Sweetwater Authority Reservoir Sediment Study
Client: Sweetwater Authority
Location: Spring Valley, California
Services Provided: Construction Materials Testing
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The Challenge
Sediment Characterization and Field Access
Sweetwater Authority required a detailed assessment of sediment accumulation within Sweetwater Reservoir to support long-term reservoir management and explore potential reuse of sediments for construction materials.
Key challenges included:
Determining sediment thickness and distribution at multiple reservoir locations
Accessing submerged zones, which required specialized over-water drilling operations
Collecting representative samples from both submerged sediments and exposed deposits during low water conditions
Recovering continuous sediment profiles down to granitic bedrock
Generating reliable geotechnical data under complex field and access conditions
Meeting these challenges required precise field coordination, the right equipment, and consistent sampling methodology to ensure high-quality, defensible results.
The Solution
Advanced Field Sampling TechniquesÂ
Ninyo & Moore, a SOCOTEC Company, implemented a tailored investigation program combining advanced field sampling technology with laboratory analysis and comprehensive reporting.
Field and Analytical Services Included:
- Sediment Sampling and Logging: Continuous recovery was performed using a track-mounted direct push Geoprobe 7822DT rig and the Geoprobe DT325 system, capturing the full sediment column to bedrock.
- Barge-Based Drilling Operations: Over-water sampling from a barge allowed safe access to submerged areas while maintaining sample integrity.
- Onshore Sampling: Additional samples were collected from exposed sediment deposits during periods of low reservoir water levels.
- Laboratory Testing: Sediments were analyzed to determine physical properties and assess suitability for potential use as fine aggregate in construction materials.
- Data Interpretation and Reporting: A comprehensive report summarized sediment thickness, geotechnical conditions, and laboratory results to support informed decision-making.
Ninyo & Moore, a SOCOTEC Company, implemented a tailored investigation program combining advanced field sampling technology with laboratory analysis and comprehensive reporting.
Field and Analytical Services Included:
- Sediment Sampling and Logging: Continuous recovery was performed using a track-mounted direct push Geoprobe 7822DT rig and the Geoprobe DT325 system, capturing the full sediment column to bedrock.
- Barge-Based Drilling Operations: Over-water sampling from a barge allowed safe access to submerged areas while maintaining sample integrity.
- Onshore Sampling: Additional samples were collected from exposed sediment deposits during periods of low reservoir water levels.
- Laboratory Testing: Sediments were analyzed to determine physical properties and assess suitability for potential use as fine aggregate in construction materials.
- Data Interpretation and Reporting: A comprehensive report summarized sediment thickness, geotechnical conditions, and laboratory results to support informed decision-making.
The Results
Actionable Data for Reservoir Management
The study provided Sweetwater Authority with critical insights to guide reservoir management and infrastructure planning:
Clear understanding of sediment distribution across the reservoir
Reliable geotechnical data extending from sediment layers to granitic bedrock
Evaluation of sediment suitability for reuse in construction, supporting sustainability goals
Consolidated technical dataset combining field and laboratory findings for easy interpretation
Improved decision-making for maintenance planning, dredging operations, and long-term reservoir management
