Matilija Technical Advisory Committee Meeting, May 28, 2014 1
Agenda 1. Meeting Purpose 2. Concept Matrix Presentation & Discussion a) Previous Concepts b) New Concepts c) Stakeholder Additional Concepts 3. Initial Screening Process Discussion a) Scope Overview b) Evaluation Categories 4. Potential Initial Options List 5. Closing 2
Meeting Purpose 3
Concept Matrix Presentation & Discussion 4
Concept Matrix - Key References Key References Summary: 1. Appraisal Report (USBR 2000) 2. Feasibility Study (USACE 2004) 3. Upstream Sediment Disposal Areas (USA; USACE 2010) 4. Fine Sediment Study Group Final Report (FSSG 2011) 5. Double Barrel Bypass (Stoecker 2011) 5
Concept Matrix – Tables/Figures Available Tables/Figures: 1. Full Matrix Details 2. Previous Concepts Summary Table 3. New Concepts Summary Table 4. Single-Phase Removal Concepts Diagram 5. Multi-Phase Removal Concepts Diagram 6. Fine Sediment Categories 6
Concept Matrix Overview Previous Concepts – Appraisal Study (2000) Detailed Technical Analysis (Previously Documented) ID Concept Name General Description Reference Fine Sediment Coarse Sediment Casitas Water Diversion Sediment moved to the right side of the reservoir and stabilized/restored. River Approx. 400 AF/yr less yield for Casitas MWD Move Sediment Upstream channel graded and restored on left side of Appraisal Report Accumulated sediment is removed from the river system by with dam removal. High flow sediment AP-Alt. 1A of the Dam and Stabilize stabilizing onsite. No sediment modeling of this alternative. reservoir. The dam would be completely USBR 2000 bypass at Robles Diversion to flush chronic (Alt. 1A) removed in parallel with the sediment sediment. excavation/placement. Partial dam removal with a fish ladder over the lowered dam. Sediment moved (down Partial Dam Removal & AP-Alt. 1A to revised dam elevation) to the right side of Appraisal Report Accumulated sediment is removed from the river system by Move Sediment Upstream Similar to AP-Alt. 1A stabilizing onsite. No sediment modeling of this alternative. - Future the reservoir and stabilized/restored. River USBR 2000 of the Dam and Stabilize channel graded and restored on left side of reservoir. Coarse material (accumulated) removed from the river system. Fine material (accumulated) Material would be excavated and removed from the river system. Sediment would be excavated and hauled hauled to either a downstream Approx. 400 AF/yr less yield for Casitas MWD Move Sediment to a Site or Material would be excavated and downstream (ocean or other site) by truck. Appraisal Report permanent disposal site, with dam removal. High flow sediment AP-Alt. 1B Sites Downstream by hauled to either a downstream The dam would be completely removed, but USBR 2000 downstream temporary disposal bypass at Robles Diversion to flush chronic Trucking (Alt. 1B) permanent disposal site, in stages. site, or the ocean. Material could sediment. downstream temporary disposal be processed for commercial sale. site, or the ocean. No sediment modeling of this alternative. Fine sediment (<=1mm) would be slurry Fine material (accumulated) Coarse material (accumulated) Remove Sediment to dredged and piped to the ocean and coarse removed from the river system by removed from the river system Approx. 400 AF/yr less yield for Casitas MWD AP-Alt. Ocean by Slurry Pipeline material would be excavated and Appraisal Report hydraulic dredging and slurry using a conveyor belt and trucking with dam removal. High flow sediment 1BB and Conveyor/Trucking conveyor/trucked to the ocean (or other USBR 2000 pipeline. After drying, could be system to transport to ocean or bypass at Robles Diversion to flush chronic (Alt. 1BB) downstream disposal location). Dependent hauled to the ocean for beach downstream temporary disposal sediment. on water availability for slurry. replenishment. site. 7
Concept Matrix Overview Previous Concepts – Appraisal Study (2000) Detailed Technical Analysis (Previously Documented) ID Concept Name General Description Reference Fine Sediment Coarse Sediment Casitas Water Diversion Accumulated reservoir area fines Accumulated coarse material Sediment deposition at Robles Diversion allowed to erode without other allowed to erode without other will increase. Sediment removal at diversion Dam would be removed in 9 separated stabilization during various stabilization during various may need to occur more frequently. AP-Alt. 2 Phased Natural Transport Appraisal Report phases (2-3 years btwn). Sediment would be phases. 6.0 MCY total sediment. phases. Sand: 54% of reservoir Turbidity a water quality problem in Casitas of Sediment (Alt. 2) USBR 2000 sluiced by natural creek flow. Silt/clay: 38% of reservoir sediment. Gravel/cobble: 8%. Reservoir; would need to restrict diversions sediment; assumed transport Total natural transport limited by during high turbidity periods. No mitigation £ 200,000 mg/l. sand transport using Yang (1973). provided. Appendix E, AP-Alt. 3 Combination of Alts. 1 & 2 Combination of Alts. 1 & 2 - not carried Appraisal Report Not addressed Not addressed Not addressed (Alt. 3) forward in Appraisal Study USBR 2000 Complete Removal of Dam Minimal removal of sediment to allow full in 1 Phase with single-phase dam removal. Sediment would Appendix E, Sediment deposition at Robles Diversion AP-Alt. 4 Uncontrolled Natural be left to erode slowly until large events Appraisal Report 6 MCY of sediments eroded during one or more high flow seasons. may increase. Erosion of Sediment (Alt. carry the sediment downstream. This was USBR 2000 4) not carried forward in Appraisal Study. Construction of Fish Fish ladder or bypass would be constructed Appendix E, Accumulated sediment stabilized in place by dam. As sediment AP-Alt. 5 Ladder or Bypass with No to allow upstream passage of steelhead past Appraisal Report accumulates behind the dam, eventually it would begin passing Not addressed Dam Removal (Alt. 5) the dam. USBR 2000 naturally over the dam. No modeling of this alternative. Leave the dam and sediment in place. Sediment would continue to accumulate in Appendix E, Accumulated sediment stabilized in place by dam. As sediment AP-Alt. 6 No Action (Alt. 6) the reservoir until storage is gone, at which Appraisal Report accumulates behind the dam, eventually it would begin passing Not addressed point the sediment load would be USBR 2000 naturally over the dam. No modeling of this alternative. transported downstream. 8
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