Design Oversight Committee March 17, 2017 1 Agenda 1. Welcome and - - PowerPoint PPT Presentation

1

Design Oversight Committee

March 17, 2017

Agenda

• 1. Welcome and Introductions - Tully
• 2. Meeting Purpose - Sam
• 3. Report Summary - Peter
• Dam Removal Concepts
• Water Supply Mitigation Options
• 4. Project Funding and Project Completion Pathways – Sam
• 5. Dam Removal Concept Discussion and Selection - Peter
• 6. Next Steps – Tully
• 7. Closing - Tully

2 of 34

Dam Removal Concepts Evaluation

3 of 34

Background

• Contract Management Team

– VCWPD – CMWD – NOAA – SCC – Surfrider – BOR

4 of 34

Dam Removal Concept Descriptions

Six Initial Options narrowed down to three alternatives during the September 2014 Design Oversight Group/Technical Advisory Committee Meeting The Three Short-listed Dam Removal Concepts (DRCs)

• 1. DRC-1: Containment Berm with High Flow Bypass
• 2. DRC-2: Uncontrolled Orifices with Optional Gates
• 3. DRC-3: Temporary Upstream Storage of Sediment

5 of 34

DRC-1: Containment Berm with High Flow Bypass

Overview:

• Flow bypass system

around reservoir fine sediment (tunnel + cofferdam)

• Temporary

containment berm downstream of the dam

• Single-phase dam

removal

• Minimal sediment

handling

Bypass storms less than flushing storm of 3,000 cfs peak (1,700 cfs average daily flow)

6 of 34

DRC-1: Containment Berm with High Flow Bypass

7 of 34

DRC-1: Containment Berm with High Flow Bypass

Project Categories Construction Cost (2015) Low (-30%) High (+50%) Mobilization $3,500,000 Site Preparation $11,800,000 Sediment Components $0 Slurry System Components $0 Dam Removal Components $9,200,000 Site Restoration $2,500,000 Subtotal $27,000,000 Contingency (30%) $8,100,000 Subtotal $35,100,000 Construction Contingency (15%) $5,300,000 Total $40,400,000 $28,300,000 $60,600,000

• 0 to 3-year waiting period
• Resulting in 3 to 6-year construction

schedule

8 of 34

DRC-2: Uncontrolled Orifices with Optional Gates

Overview:

• Construct IO-02
• Installation of

gates, as needed

• Dam Removal

9 of 34

DRC-2: Uncontrolled Orifices with Optional Gates

10 of 34

DRC-2: Uncontrolled Orifices with Optional Gates (2A – no gates)

• 0 to 3-year waiting period
• Resulting in 2 to 5-year construction

schedule

Project Categories Construction Cost (2015) Low (-30%) High (+50%) Mobilization $1,600,000 Site Preparation $900,000 Sediment Components $0 Slurry System Components $0 Dam Removal Components $8,000,000 Site Restoration 1,900,000 Subtotal $12,400,000 Contingency (30%) $3,700,000 Subtotal $16,100,000 Construction Contingency (15%) $2,400,000 Total $18,500,000 $13,000,000 $27,800,000 Note – The ROM construction cost of each additional orifice would be $1,000,000. 11 of 34

DRC-2: Uncontrolled Orifices with Optional Gates (2B – add gates)

• Two 0 to 3-year waiting period
• Resulting in 3 to 9-year construction

schedule

Project Categories Construction Cost (2015) Low (-30%) High (+50%) Mobilization $1,800,000 Site Preparation $1,900,000 Sediment Components $0 Slurry System Components $0 Dam Removal Components $8,000,000 Site Restoration 1,900,000 Subtotal $13,600,000 Contingency (30%) $4,100,000 Subtotal $17,700,000 Construction Contingency (15%) $2,700,000 Total $20,400,000 $14,300,000 $30,600,000 Note – The ROM construction cost of each additional orifice with gate would be $2,100,000. 12 of 34

DRC-3: Temporary Upstream Storage of Sediment

Overview:

• Excavate channel

(1.6M CY)

• Disposal material

placement (1.6M CY)

• Removal of dam

13 of 34

DRC-3: Temporary Upstream Storage of Sediment

14 of 34

DRC-3: Temporary Upstream Storage of Sediment

15 of 34

DRC-3: Temporary Upstream Storage of Sediment

Project Categories Construction Cost (2015) Low (-30%) High (+50%) Mobilization $4,400,000 Site Preparation $3,600,000 Sediment Components $15,000,000 Slurry System Components $0 Dam Removal Components $8,000,000 Site Restoration $2,200,000 Subtotal $33,200,000 Contingency (30%) $10,000,000 Subtotal $43,200,000 Construction Contingency (15%) $6,500,000 Total $49,700,000 $34,800,000 $74,500,000 16 of 34

Dam Removal Concepts Evaluation

Evaluation Summary

17 of 34

Evaluation Summary

Evaluation Criteria:

Evaluation Category Evaluation Criteria Description A. Biological Resources Steelhead Passage Time to reach steelhead passage through dam/reservoir area Steelhead Health Scale of severity of impacts for suspended sediment to steelhead Ecological Health Acres of vegetation communities impacted by actions at dam/reservoir Ecological Health Acres of future vegetation communities within reservoir area of impact B. Technical & Implementation ROM Construction Cost Rough Order of Magnitude Construction Cost Risk Management Flexibility to manage risk and react to unanticipated conditions C. Sediment Transport & Water Quality Water Supply Wet cycle percent reduction in Lake Casitas water storage levels Water Supply Dry cycle percent reduction in Lake Casitas water storage levels

18 of 34

Evaluation Summary

Steelhead Passage:

1. Construction Duration 2. Flush Waiting Period 3. Post-Flush Passage Establishment

Dam Removal Concept Implementation Duration (years) DRC-1 3 to 6 DRC-2A/B 2 to 5 / 3 to 9 DRC-3 2 to 5

19 of 34

Evaluation Summary

Steelhead Health:

1. Function of magnitude and duration

• f TSS during Phase I and II erosion

Dam Removal Concept Phase I Severity Score DRC-1 13 DRC-2A 13 DRC-2B 13, but second flush possible with gate DRC-3 minimal

Fish Response to Suspended Sediments for Adult Salmonids (using the empirically generated model of Newcombe and Jensen, 1996)

20 of 34

Evaluation Summary

Ecological Health Impact:

1. Acres of existing vegetation communities impacted by project

Vegetation Community Impacts (acres) DRC-1 DRC-2 DRC-3 Mixed Chaparral 0.6 0.4 1.3 Freshwater Marsh 1.9 1.6 2.5 Oak Woodland 1.0 0.0 3.5 Riparian Scrub 7.2 5.7 15.5 Riparian Woodland 14.2 12.0 37.0 Coastal Sage Scrub 0.5 0.2 2.1 Total 25.5 19.6 69.0 21 of 34

Evaluation Summary

Ecological Health Benefit:

1. Acres of proposed vegetation communities (riparian of highest value)

Vegetation community DRC-1 (acres) DRC-2 (acres) DRC-3 (acres) Herbaceous Riparian 7.4 7.4 7.9 Riparian Scrub 17.5 17.5 15.8 Riparian Woodland 26.3 26.3 14.4 Oak Woodland 21.5 21.5 28.9 Coastal Sage Scrub 59.2 59.2 53.6 Mixed Chaparral 22.1 22.1 39.3 Total 154.0 154.0 159.9 22 of 34

Evaluation Summary

ROM Construction Cost:

• Alt. 4B (2015) cost is approximately $113,000,000

– not including downstream improvements – other costs (engineering, admin & legal, construction management,

• perations and maintenance, etc.)

DCR Range of Magnitude Construction Cost (ROMCC) (-30%) Estimate (+50%) DRC-1 $28,300,000 $40,400,000 $60,600,000 3 DRC-2A $13,000,000 $18,500,000 $27,800,000 1 DRC-2B $14,300,000 $20,400,000 $30,600,000 2 DRC-3 $34,800,000 $49,700,000 $74,500,000 4

23 of 34

Evaluation Summary

24 of 34

Evaluation Summary

Key Points:

• DRC-2 (without gate) ranks first overall, primarily due to having the lowest cost,

risk, and impact to existing vegetation. In addition, it does not rank last in any

• category. Gate could be added as a contingency measure (to adaptively manage

fine sediment), given considerations from evaluation (potential for subsequent temporary impact to aquatic health)

• DRC-3 ranks second, with its high impact to existing vegetation (large footprint),

high cost and lower long-term vegetation habitat benefit, pulling it below DRC-2 in overall score.

• DRC-1 ranks third given the selected criteria, primarily due to the fact that it
• nly ranks first in one of the criteria, generally failing to significantly

differentiate itself from the other concepts, but carrying the greatest risk and relatively high cost.

25 of 34

Water Supply Mitigation Concepts Evaluation

26 of 34

Mitigation Options

Mitigation Options Selection

• A total of 23 different options were evaluated
• Options were grouped into four categories:

– Diversion Replacement – Replacement Supplies – Re-use & Conservation – Treatment Alternatives

• Evaluated based on cost, environmental, technical

feasibility, and adaptability considerations

• 8 options are being recommended for further analysis

27 of 34

Mitigation Options

Type of Mitigation

Description

Cost Environ. Feasibility Adapt. Develop Further Diversion Replace.

Diversion from Matilija to Canal

   

Diversion from NF Matilija to Canal

   

Diversion from Matilija to NF Matilija to Canal

   

Replacement Supplies

Infiltration Galleries

   

Water Transfer from SWP

   

Water Transfer from MWD to Casitas via Carpinteria

   

CMWD Transfers to MOWD

    

Groundwater Transfers

   

Desalination

   

New Wells at Santa Paula Basin

    

New Well Heads at Foster Park

    

San Antonio Creek Diversion Expansion

   

Re-Use & Conservation

Recycled Water – Ojai Valley Waste Water Treatment Plant

   

Recycled Water – Ventura Water Reclamation

   

Recycled Water – Scalping Plants

   

Urban and Agricultural Conservation

    

Crop Idling Transfers

    

Treatment

Robles Diversion Dam Improvements

   

Robles-Casitas Canal Treatment

   

Casitas Reservoir Oxygenation Enhancement

    

Back-flushing of Meiners Oaks Wells 1 and 2

    

CMWD Water Treatment Plant System Modifications

    

CMWD Water Treatment Plant Roughing Filters    

28 of 34

Mitigation Options

Evaluation Recommendations:

Type of Mitigation Description Volume1. (AFY) Volume2. (% per year) Cost ($) Replacement Supplies CMWD Transfers to MOWD N/A N/A $20K New Wells at Santa Paula Basin 1,400 11% $250K New Well Head at Foster Park 750 5.9% $1.5M Re-Use & Conserve Urban and Agricultural Conservation 250 2.0% $191K Crop Idling Transfers 800 6.3% $5.95M Treatment Casitas Reservoir Oxygenation Enhancement N/A N/A $5K Back-flushing of Meiners Oaks Wells 1 and 2 83 0.7% $20K CMWD Water Treatment Plant System Modifications Varies3. Varies3. $250K + $10K/y ear 1. Potential additional or saved volume of water. 2. Potential percentage of loss water volume mitigated. 3. Amount of volume mitigated depends on level of additional treatment implemented. 4. Water volume losses are estimated at 12,700 AF per storm event when diversion operations are suspended.

29 of 34

Comments Received

DAM REMOVAL CONCEPTS EVALUATION REPORT

• Casitas Municipal Water District
• Matilija Coalition
• National Marine Fisheries Service
• Ojai Valley Sanitary District
• Stoecker Ecological

WATER SUPPLY MITIGATION OPTIONS EVALUATION REPORT

• Matilija Coalition
• National Marine Fisheries Service
• Ojai Valley Sanitary District
• Ventura Water

30 of 34

Matilija Project Completion Pathways

31 of 34

32 of 34

33 of 34

34 of 34