April 2014
Gathard Engineering Consulting
Yuba River Fish Passage Improvement Investigation Final Report
National Marine Fisheries Service
Investigation of Dam Removal and Fish Passage Conceptual Options at Englebright and Daguerre Point Dams, Yuba River, California National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report
Tables of Contents
Executive Summary ...... 1 Introduction ...... 3 Authorization ...... 4 Goals and Objectives ...... 4 Design Criteria ...... 5 Examples and History of Development of Proposed Dam Removal Techniques ...... 7 Scope ...... 12 Background ...... 12 Water Use and Water Quality ...... 13 Hydrology ...... 14 Fisheries Downstream of Englebright Dam ...... 15 Water Diversion ...... 15 Description of Facilities ...... 19 Englebright Dam...... 22 Daguerre Point Dam ...... 26 Basis of Design and Analysis ...... 28 Removal Sequence ...... 28 Water Quality Associated with Reservoir Lowering ...... 29 Sediment Management ...... 30 Options Developed ...... 32 Englebright Dam ...... 32 Daguerre Point Dam...... 33 Complete Dam Removal Alternative ...... 35 Englebright Dam...... 36 Daguerre Point Dam ...... 38 Upstream Water Diversion Facilities ...... 39 Partial Englebright Dam Removal ...... 44 Remove to El. 460 – Improved Fish Passage Using Current Equipment at Operational Limits ...... 44 Remove to El. 430 – Fish Passage and Power Generation without Significant Sediment Release ..... 49 Retention of Daguerre Point Dam with Fish Passage Improvements ...... 52 Rock Ramp ...... 52 Downstream Weirs ...... 55 Full Height Gates ...... 57 Cost Opinions ...... 59 Conclusions ...... 68 References ...... 71
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Table of Figures
Figure 1 Yuba River Hydrology Daily Average and Maximum Flows ...... 14 Figure 2 Location of Surface Water Diversions near Daguerre Point Dam ...... 17 Figure 3 Browns Valley Pumped Diversion upstream of Daguerre Point Dam ...... 18 Figure 4 South Yuba- Brophy Irrigation Water Diversions near Daguerre Point Dam ...... 18 Figure 5 Historic Yuba River Upstream of Daguerre Point Dam ...... 19 Figure 6 Yuba River Basin in Yuba County ...... 21 Figure 7 Facilities at Englebright Dam ...... 25 Figure 8 Complete Daguerre Point Dam Removal Stages ...... 39 Figure 9 Complete Daguerre Point Dam Removal Elements ...... 41 Figure 10 Detail of Diversion Dam Conceptual Arrangement...... 42 Figure 11 Section through Bypass Channel ...... 42 Figure 12 Longitudinal Section through Diversion Channel ...... 43 Figure 13 Yuba River Elevation Upstream of Daguerre Point Dam ...... 43 Figure 14 Fish Ladder and Lowered Dam at Elevation 460 ...... 47 Figure 15 Multi Use Facility and Fish Ladder Entrance ...... 48 Figure 16 Section through Fish Ladder near Switchback ...... 48 Figure 17 Reservoir Volume versus Elevation ...... 50 Figure 18 Facilities Arrangement for Removal to Elevation 430 ...... 51 Figure 19 Proposed Sediment Flushing Gates at Englebright Dam ...... 51 Figure 20 Typical Ramp Section at Daguerre Dam ...... 54 Figure 21 Plan View of Proposed Ramp at Daguerre Dam ...... 54 Figure 22 Plan View of Proposed Weirs at Daguerre Dam ...... 56 Figure 23 Section through Weirs ...... 56 Figure 24 Elevation of Weir ...... 57 Figure 25 Section though Radial Gates proposed at Daguerre Dam ...... 58 Figure 26 Plan View of Gates at Daguerre Dam ...... 58 Figure 27 Overview of Complete Removal of Both Dams...... 62 Figure 28 Overview of Partial Removal to Elevation 460 with Fish Ladder Construction Schedule ...... 63 Figure 29 Overview of Partial Removal to Elevation 430 with Fish Ladder Construction Schedule ...... 64 Figure 30 Overview of Ramp Construction Schedule ...... 65 Figure 31 Overview of Downstream Weirs Construction Schedule...... 66 Figure 32 Overview of Full Height Gates Construction Schedule ...... 67
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List of Tables
Table 1 Power Generating Facility Details ...... 24 Table 2 Englebright Dam Details ...... 24 Table 3 Englebright Lake: ...... 25 Table 4 AACE Cost Estimate Classification ...... 59 Table 5 Summary of Costs ...... 60
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Executive Summary
The following report investigates approaches for providing improved fish passage in the lower Yuba River, located in northern California. Fish passage in the lower reach of the river has been impeded or blocked since the construction of Daguerre Point Dam in 1906. Current fish passage facilities at Daguerre Point Dam are substandard for anadromous fish species such as Chinook salmon, steelhead and sturgeon. A second, higher dam, Englebright Dam, was constructed in 1941. This 265 foot concrete structure prevents any further upstream passage of all migratory fish, and its presence results in fragmentation of the aquatic habitats between the upper and lower Yuba River.
Two approaches for providing passage improvements are investigated in this study:
(1) Complete removal of both Daguerre Point and Englebright Dams, and (2) Dam notching or other structural modifications to Englebright Dam, and modifications at Daguerre Point Dam to provide improved upstream and downstream fish passage facilities at both dams.
Two primary design criteria used to develop the designs for both complete and partial dam removal are listed, following.
Water diversion capabilities at the facilities adjacent to the Daguerre Point Dam location are to remain operational at all times during the removal and construction process. Sediment behind the dam would be removed primarily by eroding sediment in a prescribed fashion (instead of mechanically removing all sediment from the reservoir).
Analysis of sediment erosion and transport resulting from dam removal shown in this report has been conducted by Stillwater Sciences and is presented more fully in a 2013 report entitled: Modeling Sediment Transport Dynamics and Evaluating Flooding Risks in the Yuba and Feather Rivers, California, Following Modifications to Englebright and Daguerre Point Dams. (Stillwater Study). The engineering analysis in this report has been developed in coordination with modeling of sediment transport dynamics for dam removal/modification alternatives in the Stillwater Study. Together these studies present information necessary to assess project feasibility. They also provide information regarding likely impacts and available mitigation strategies.
The study concludes that completely removing both dams can be accomplished at a cost of approximately $123 million dollars in approximately 2 years. At Englebright Dam, the most rapid removal approach could be undertaken by excavating a hole at the base of the dam to release water and trapped sediment behind the dam. Alternatively, Englebright Dam could be removed in increments over a longer time period.
Removal of Daguerre Point Dam would be accomplished by constructing a new water diversion and fish screening facility, along with an in stream, fish bypass ramp, approximately 3 miles upstream of the dam. In this scenario, both dams would be completely removed. Demolished concrete would be
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report salvaged at nearby commercial aggregate mining operations, or recycled as “fill” or base material for other project construction uses.
Partially removing Englebright Dam to either 67 or 97 feet below the current spillway elevation would cost between $60 and $64 million. Both approaches would retain most of the reservoir sediment behind the dam. At the lower elevation (97 feet below the existing spillway) sluice gates would be installed to periodically remove sediment interfering with water entering the power tunnels and a new, lower, power tunnel entrance would be constructed.
The existing power intake tunnel would continue to be used if the spillway were lowered to an elevation 67 feet below the existing spillway and sluice gates would not be installed. Both partial dam removal approaches would construct a new fishway for upstream and downstream migrants to allow salmonids to volitionally pass the dam.
At Daguerre Point Dam, three additional approaches were developed that leave the dam in place and would provide volitional upstream and downstream passage for salmonids and sturgeon. These include the following:
1. Constructing a rock ramp from the top of the dam to approximately 3,000 feet downstream of the dam, which would provide improved passage for all target species at a cost of approximately $18 million.
2. Constructing a series of stepped weirs across the entire width of the river, which would provide a low gradient passage for all target species to migrate past the dam at a cost of approximately $64 million.
3. Constructing a full height radial gate through the dam to allow intermittent lowering of the reservoir to allow fish passage at a cost of approximately $21 million.
These three alternative approaches would leave the dam and existing water diversion facilities in operation without alterations.
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Introduction
Daguerre Point and Englebright Dams are located on the Yuba River, a major tributary in the Sacramento River watershed. These structures placed in operation in 1910 and 1941, respectively, were built to control hydraulic mining debris. Daguerre Point Dam currently contains two fish passage ladders that operate at below optimum capability to pass salmonids and do not allow sturgeon passage. Englebright Dam has never had fish passage facilities and completely blocks all upstream fish migration. The dams are currently owned and operated by the U.S. Army Corps of Engineers and their current functions include power production, flow regulation, and water diversion.
In February 2010, Montgomery-Watson-Harza, Inc., under contract with the National Marine Fisheries Service produced a report entitled: Yuba River Fish Passage: Conceptual Engineering Project Options (MWH 2010). That report was a conceptual engineering survey of several different potential options for fish passage facilities which might be considered in the future design and implementation of an anadromous fish reintroduction program. Because of budget constraints at the time, two prominent options were excluded from the scope of that study: (1) complete dam removal, and (2) dam notching or other structural modifications along with additional (or improved) upstream and downstream fish passage facilities.
This study was undertaken to complete the full range of conceptual fish passage alternatives analysis by focusing on these "unresolved elements" at this time. In conjunction with this study, a companion study has been undertaken to provide an analysis of sediment transport and erosion resulting from dam removal options shown in this report. That report, Modeling Sediment Transport Dynamics and Evaluating Flooding Risks in the Yuba and Feather Rivers, California, Following Modifications to Englebright and Daguerre Point Dams was prepared for National Marine Fisheries Service Southwest Region Habitat Conservation Division by Stillwater Sciences in June, 2013 (Stillwater Study).
The Stillwater Study investigated the following scenarios. a) Englebright Dam would be completely removed starting by constructing a tunnel at the base of the dam in a manner that would result in a rapid release of the reservoir contents before removing the dam.
b) Englebright Dam would be removed using a staged removal alternative that would remove the dam from the top‐down in 10 stages over a 10‐year period. The results of this investigation indicated that this approach provided no positive advantage over other methods. In fact, because it extended the period of high turbidity in the river downstream of the dam, no engineering investigation of this approach is provided in this report.
c) Englebright Dam would be removed to a crest elevation of 131 m (431 ft) and a fish ladder would be constructed to allow fish passage over the remaining 56 m (185 ft) of the dam.
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d) Englebright Dam would be removed to a crest elevation of 140.2 m (460 ft) with a fish ladder to allow fish passage over the remaining 65 m (214 ft) of the dam.
e) Daguerre Point Dam would be completely removed.
Analysis in this engineering investigation has been developed in coordination with modeling of sediment transport dynamics for dam removal/modification alternatives presented in the Stillwater Study. Both studies present important information vital to assessing feasibility and likely impacts, as well as possible mitigation strategies for potential project development going forward.
Authorization
This investigation of the removal of two dams on the Yuba River in northern California was conducted for the Habitat Conservation Division of the National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NMFS) West Coast Region. The study was performed within the purview of the facilities owner, the U.S. Army Corps of Engineers. The investigation includes approaches for full and partial removal of Englebright Dam and Daguerre Point Dam on the Yuba River. It also provides approaches to volitional fish passage options for the partial removal options.
Goals and Objectives
The goal of this investigation is to provide information and analysis to help enhance fish populations in the Yuba River. The objective of this report is to develop concepts that provide upstream and downstream volitional salmonid passage at Englebright Dam and enhance upstream and downstream volitional passage of salmonid and sturgeon at Daguerre Point Dam.
Specific Objectives include:
Investigate feasibility, costs, scheduling, and impacts of alterations to existing dam structures as a means to provide fish passage at Englebright and Daguerre Point dams on the Yuba River in northern California. The following activities are included to accomplish these objectives.
a) Strategies are developed that provide volitional upstream and downstream fish passage for salmonids and sturgeon. b) The feasibility and cost of full dam removal for both dams are analyzed. c) Feasibility and cost of volitional fish passage facilities and alternatives to the full dam removal approaches are analyzed. Included in the investigation are fish ladders and juvenile fish screening and collection devices in Englebright Reservoir. d) Analysis of effects of the dam removal approaches on downstream river and reservoir uses, including power, but not including recreation, is conducted. e) Mitigation measures and associated costs for impacts are proposed.
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Design Criteria
Criteria and assumptions used to develop specific engineering concepts for this report are generally discussed in the description of the specific design element. Criteria for managing trapped reservoir sediment must be developed prior to developing all other elements of the report since managing sediment controls the development of fish passage, water diversion, and dam removal concepts.
The method used for sediment management throughout this report is based on experience from numerous similar dam removal projects. Generally, the standards were developed to protect the natural and built environment from detrimental effects of increased sediment flows resulting from construction activities.
The proposed methods of sediment management - allowing the river to erode the sediment naturally including some mechanical equipment activity to augment movement of sediment on the river banks into the river during the first year, and dam removal - have been thoroughly studied and implemented on other recent dam removal projects. The following section: “Examples and History of Development of Proposed Dam Removal Techniques,” discusses the history and results of several previous large dam removal projects in the western United States.
Two of the primary concerns driving the investigation of sediment management methods for this investigation are: (1) minimizing or eliminating increased flood risks downstream to properties and population centers, and (2) addressing relative risks associated with transport of certain chemical constituents interspersed within the reservoir sediments. The Stillwater Study investigates flooding issues resulting from the proposed method of sediment management. That study was undertaken as a parallel, complementary study to provide additional science support and predictive insights for each approach discussed herein. The Stillwater Study looks at projected levels of turbidity following dam removal, but does not address water chemistry issues from a toxicology standpoint because such analysis was beyond the scope of that report. Further study of the water quality issues will require additional data collection, investigation, and specialized professional expertise.
In the past, some project planners initially assumed that Clean Water Act standards for general construction projects should apply to the short-term phases of dam demolition. However, imposing these strict water quality standards on projects which have long term goals to improve and enhance the natural environment may produce a project too costly to develop, potentially undermining the larger intention of environmental quality standards and ecosystem restoration, which is to enhance and protect the natural environment over the long run.
Removing structures that impede the natural flow of sediment, flora, and fauna in a river generally enhances the overall water quality and increases fish populations over time. For this reason, certain resource and regulatory agencies have been willing to consider short term exceedances of standards to allow developing dam removal projects that favor long term enhancement of the natural environment. Accordingly, for this project the assumption was made that exceeding water quality standards for
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report turbidity and suspended sediment downstream of Englebright Dam would be acceptable. The criterion for removing sediment from behind the dams for this report assumes, therefore, that the river would erode the sediment downstream.
Upstream fish passage can be provided either by completely removing the dams from the river or providing engineered facilities to allow fish to volitionally swim upstream of the dams. Likewise, removing the dam will allow downstream migrants to pass freely. In cases where dams remain in place, various methods are employed to aid downstream migrant passage. These usually involve use of juvenile fish screening and bypass systems, and can require mechanical devices to assist fish collection into passage ways.
When presenting these alternatives for dam removal and the supporting sediment transport model, we recognize the complexities and impacts of dam removal on this scale cannot be overly simplified. We present these approaches assuming the risks associated with short term impacts are worth the long-run benefits to environmental quality and fisheries resources, and that the identifiable impacts may be satisfactorily mitigated by strategic planning, thoughtful engineering, and advance preparation.
Specific Criteria Specific Design Criteria used to develop options presented in this document include:
All concepts must achieve volitional fish passage1 Complete removal of both dams as one approach to achieve volitional passage Partial removal of Englebright Dam including retention of power production capabilities o Down to the lowest elevation that can still use the current intakes and penstocks o Down to a lower elevation slightly above the surface of reworked sediment that does not cause significant release of trapped sediment from Englebright Dam Retention of irrigation water diversion capability at facilities adjacent to Daguerre Point Dam for all approaches
This report investigates complete removal of both dams, partial removal of Englebright Dam with a fishway, and retaining Daguerre Point Dam with downstream ramps and weirs as a means to attain the fish passage goals. Daguerre Point Dam currently uses pool and weir fishways at both the left and right abutments to provide some level of upstream passage for salmonids. Downstream migrants are screened at water diversion intakes, but the need for screening improvements and better upstream passage has been identified. Existing passage facilities are not considered to be adequate to pass all upstream and downstream migrants. No upstream passage is provided for green sturgeon at Daguerre Point Dam. A previous study by MWH 2010 investigated construction of a full height fish ladder as a
1 volitional fish passage is defined herein as a form of fish passage whereby a fish's opportunity and choice to move freely past some impediment is continuously available, and the aquatic conditions are within the swimming ability of the target life stage and species intended for passage, such that all healthy individuals of the population can pass at will, or..."of their own volition." (definition per NMFS-Engineering, Southwest Region)
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report volitional fish passage option at Englebright Dam, which currently has no upstream or downstream passage facilities.
Examples and History of Development of Proposed Dam Removal Techniques
The following discussion provides a brief history of the development of sediment management and dam removal techniques for projects in the western United States.
Sediment Management The first large dam removal project to be studied for enhancement of the river ecosystem on the West Coast of the United States was on the Elwha River on Washington State’s Olympic Peninsula. Investigation of techniques to remove the two dams, Elwha Dam and Glines Canyon Dam, began in late 1980’s. Challenges facing the project included: (1) no large dams of this size (105 feet tall and 210 feet for Elwha and Glines Canyon respectively) had been intentionally demolished, so investigators had no previous project removal documents to review for reference; (2) dam owners initially resisted removing dams on principle; and (3) until that time the scope of the issues that would require investigation and thorough analysis were not known.
Understanding of allowable and appropriate methods for managing the removal of sediment trapped behind the dams has changed dramatically from the early studies. The earliest study of dam removal was conducted by dam owner’s engineering representatives, Hosey and Associates. The work conducted by Hosey was based on assumptions regarding environmental and construction criteria and constraints that would be placed on construction activities.
The resulting project removal design was extraordinarily complex and costly. Hosey’s investigation of sediment removal on the Elwha River assumed that water quality criteria for turbidity resulting from the Clean Water Act (CWA) sections 401 and 404 regarding construction sediment discharges in or near rivers and streams would necessarily apply to dam removal projects. Based on this assumption, the proposed method of sediment removal was to first drain all the water in the reservoirs, divert the river around the dam structure, and completely dry all sediment before using mechanical construction equipment to load millions of yards of sediment into over the road trucks. The trucks would then haul the sediment approximately 15 miles to newly constructed piers where it would then be loaded on barges to be disposed of in the ocean. Even with these actions, meeting CWA criteria was never certain because some sediment would be eroded as the reservoir was lowered.
Because of this they concluded that dam removal would be technically challenging and was not economically feasible. The stated reason for this assumption was that increases in river turbidity associated with dam removal would be unacceptable. Based on this assumption dam removal was extremely costly and complex2 and proved not to be feasible from a constructability perspective.
2 The Elwha Report, January 1994, “Restoration of the Elwha River Ecosystem and Native Anadromous Fisheries, A report Submitted Pursuant to Public Law 102-495”
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However, its development was based on the assumption that short term water quality standards could not be waived for long term benefit.
The first analysis conducted by engineers (charged with the goal of removing the dams as a means to restore the ecosystem) investigated several alternatives to mechanically removing reservoir sediment - including eroding sediment and removing the sediment and placing it above the river banks using wet suction dredging techniques.3 While this approach reduced costs, was less complex, shortened project duration, and increased overall project feasibility, it did not accomplish dam removal without causing some level of high suspended sediment levels downstream.
Investigation of dredging techniques showed that not all sediment could be effectively removed by dredging and that dredging would involve sediment treatment with chemicals such as polyacrylamides in settling ponds that could have detrimental environmental impacts.4 In this plan, sediment was placed in settling ponds above the river banks; but it required treatment with flocculants to settle the material due to the relatively small area for settling, as compared to the reservoir.
Even with flocculants, silt curtains, and best management practices some increase in TSS was anticipated from the water coming from the settling ponds. Furthermore, hydraulic dredging was limited to approximately 20 feet of reservoir depth. In order to dredge all the sediment in the reservoir, the reservoir would need to be lowered in 20 foot increments. Each lowering of the reservoir would cause an increase in downstream TSS. Finally, even though the dredged sediment could be stabilized, natural erosive forces might eventually erode the material into the river resulting in high sediment concentrations many years after dam removal.
Piping the dredged material in a slurry line to the ocean was also investigated and included as an alternative in the Environmental Impact Statement. The complexity of piping the dredged material to salt water increased the possibility of a failure that would cause increased TSS. The cost for this approach was significantly higher than other approaches.
Dredging sediment, either by hydraulic or mechanical means, was investigated as a means to remove the Elwha River dams and Condit, San Clemente, and Milltown dams. That approach has been rejected for each project, generally, because other approaches have fewer negative impacts, less costs, less duration, and greater reliability. Several issues make hydraulic dredging technically challenging for most dam removal projects including:
Need for a large flat area to settle dredged fines Need for a large volume of water to transport fines Access issues to transport and assemble the dredging equipment
3 Summit Technology Consulting Engineers, 1991, “Elwha River Dam Removal and Sediment Management” 4 Daughlon, Christian G. (23 June 1988). "Quantization of Acrylamide (and Polyacrylamide): Critical review of methods for trace determination/formulation analysis & future-research recommendations" (PDF). EPA Environmental Sciences Division homepage. The California Public Health Foundation. Retrieved 2010-06-30
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Cost for excavating dredged material Limits on TSS from settling ponds Increased construction time and risks associated with dredging
Eroding reservoir sediment was investigated also. However, the impacts of this approach were considered too extensive at that time. It was assumed that high TSS levels would potentially destroy many, if not all of the fish trapped in the river’s mainstem during erosion due to extremely reduced dissolved oxygen levels and high TSS. Short term, water quality for downstream users would be dramatically impacted and require improvement before use. Further, software (HEC 6) used to model sediment erosion did not accurately predict outcomes.
The science of dam removal has progressed significantly since the first studies to remove two dams on the Elwha River were initiated. Removal of numerous dams on the U.S. West Coast, including Condit, Marmot, Iron Gate, Copco 1, Copco 2, J.C. Boyle, San Clemente, Milltown, Matilija, Gold Ray, Savage Rapids and Gold Hill has been extensively analyzed. Several of these dams have already been removed (Elwha, Condit, Marmot, Gold Ray, Savage Rapids, and Gold Hill) and results of the removal process are available for comparison to results anticipated in removal studies.
Knowledge of the scope of issues requiring investigation, i.e. - impacts to the ecosystem and built environment from removal; construction and demolition methods and approaches, and the role of environmental regulatory agencies and application of regulations under the Clean Water Act (CWA), has evolved through the numerous studies conducted for these removal projects. As a result, removal criteria and design assumptions have also substantially evolved over this period.
Generally, the CWA requires that “States and authorized Tribes adopt water quality criteria with sufficient coverage of parameters and of adequate stringency to protect designated uses.5” This requires them to adopt methods for protecting water quality within their regulatory authority including a sediment criterion that describes conditions of contaminated and uncontaminated sediments. This criterion for sediment has taken the form of numerical limits or “a description of conditions that will avoid adverse effects of contaminated and uncontaminated sediments.6” Limits for turbidity or suspended sediment are set by State permitting authorities under section 401 of the CWA. Permitting authorities issue a General Permit that allows construction activities to be conducted if water quality affected by the activities is within criteria provided in the General Permit.
However, applying General Permit criteria to dam removal would reduce the ability to accomplish long term improved environmental conditions in the river associated with dam removal. Therefore, under certain circumstances, exemptions and modifications from the criteria outlined in the General Permit are allowed. State regulations authorize Washington Department of Ecology, for instance, to issue
5 http://water.epa.gov/scitech/swguidance/standards/crit.cfm 6 http://water.epa.gov/scitech/swguidance/standards/crit.cfm
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report short-term water quality modifications on a site-specific basis if necessary to accommodate essential activities, respond to emergencies or otherwise protect the public interest7.
Dams restrict river access for migration by diadromous species, increase water temperature, reduce nutrient distribution along the river, reduce dissolved oxygen and sediment transport, and generally decrease the ecological integrity of a river.8 State agencies responsible for CWA implementation in Washington (Washington Department of Ecology) and Oregon (Oregon Department of Environmental Quality) have allowed water quality modifications for the Elwha dam removals, Condit Dam removal, and Marmot Dam removal (Oregon). California is considering similar modifications for removal of dams on the Klamath River. For these projects, agencies have been willing to allow short term water quality degradation associated with dam removal as a means to accomplish the much improved riverine environment associated with a free flowing river.
The approach to sediment removal finally chosen for the Elwha River Ecosystem Restoration project was to allow the river flow to erode reservoir sediments. This approach was not only feasible from a constructability perspective but also avoided some of the enormous engineering and construction complexity associated with mechanically or hydraulically dredging sediment before removing the dams.
In the selected preferred alternative9, it was concluded that no particular environmental advantage was accomplished by removing the sediment from the reservoir prior to dam demolition. Allowing the river to erode the sediment was chosen as the means for managing the trapped reservoir sediment for several reasons:
All the sediment in the reservoir was material that the river naturally would have mobilized had the dam not been present. Bedload material in the reservoir, which would be transported downstream by erosion, is an important component needed for spawning beds downstream to meet environmental goals. Degradation of the downstream river channel-bed, an unnatural consequence of dam construction, is reduced by introducing new material. Downstream river stability and morphology would be enhanced by release of the natural sediment supply withheld by the dam. Mitigation for short term water quality criteria exceedances for downstream water users was feasible from an economic and engineering perspective. Short term high suspended sediment events are natural to a river and might occur from locations upstream of the reservoir in spite of the best efforts to restrict release of the reservoir sediments. Most fish species have adapted strategies to survive these events either by moving into tributaries, not entering the river, or otherwise swimming away from the disturbance.
7 WSDOT, ESO, Permitting and Compliance Program, last updated March 2011 8 Ligon, F. K., W. E. Dietrich, and W. J. Trush. 1995. Downstream ecological effects of dams. Bioscience 45:183–192.
9Elwha River Ecosystem Restoration Implementation, Final Environmental Impact Statement, November 1996, Olympic National Park, Washington
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The development of the Elwha River Ecosystem Restoration Project resulted in an approach that allowed for a controlled release of sediment to create periods in which river TSS levels dropped to near normal, thus allowing fish to continue migrate and spawn in areas upstream and downstream of the dams. This requirement for spawning and passage extended the construction period over several years and subjected instream fisheries to several periods of high TSS levels.
Following the Elwha Project, further refinement of the natural erosion strategy on other dam removal projects resulted in a different approach for removal of the Condit Dam on the White Salmon River in Washington and the Marmot Dam on the Sandy River in Oregon. These projects created conditions that eroded the sediment by instantaneously breaching the dam. This more rapid removal approach temporarily increased the level of TSS, but it also intentionally decreased the duration of high TSS levels.
On the Condit Dam, the design involved constructing an un-gated low level outlet at the base of the dam to create a tunnel through the bottom of the dam to allow rapid evacuation of the reservoir contents. The objective of this approach was to move sediment over a shorter time period to avoid lingering, chronic impacts downstream.
The philosophy behind the “Condit approach” considered the fact that most feasible methods of dam removal would increase downstream TSS sufficiently to have a negative impact on fish, including methods that removed upstream sediment before dam demolition. Other approaches extended the time period of increased TSS over many months or years - as has been the case on the Elwha Project. In contrast, rapidly eroding reservoir sediments reduces the overall time period of high TSS levels in the river because the sediment rapidly erodes downstream; thereby allowing passage and spawning to resume sooner. Over the long-run, total fish (and wildlife) mortality was projected to be lower for the “rapid removal approach” because the duration of detrimental effects of high TSS was smaller compared to other approaches. This rapid reservoir evacuation approach was also implemented to remove Marmot Dam and is part of the preferred approach for removing four dams on the Klamath River in California and Oregon.
Structure Removal Similarly, approaches to demolishing and removing structures have also evolved over time as more analysis has been conducted on removal methods. For initial investigations for the Elwha River Ecosystem Restoration project, engineers assumed that dam removal could not be conducted unless water levels were lowered to allow demolition equipment to work in a dry environment. This required elaborate, complex, lengthy, and expensive measures such as specially built bulkheads to isolate areas of the structure, vertical lake taps to control water elevations, and bypass tunnels through rock abutments to divert river flow.
Again, after much analysis, consideration, and discussion, a consensus approach evolved for stream diversion and demolition techniques. For most of the projects mentioned above, the preferred
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report approaches involved allowing the stream flow to pass over or through the structure while demolition work was accomplished.
Several methods have been developed and employed to avoid the need for the elaborate bulkheads, tunnels, and lake taps of the early investigations. At Glines Canyon Dam, a floating barge was used to simply construct notches in the top of the dam through which river flow was diverted while upper portions of the structure were demolished in dry conditions. At Elwha Dam, a longitudinal channel diverted flow from one side of the structure while the opposite side was demolished in the dry. At Condit Dam, a large opening was constructed in the dam structure near the base which drained the reservoir before the structure was demolished using a conventional impact device mounted on excavating equipment.
Scope
This study is intended to build upon the MWH 2010 fish passage study conducted for the National Marine Fisheries Service. That study investigated several different potential options for fish passage facilities at Englebright and Daguerre Point Dams. This study also includes investigating two options that were excluded from the scope of that study: 1) complete dam removal, and 2) lowering the height of the dams and providing facilities necessary to achieve volitional fish passage.
This study provides an analysis of removal of both Daguerre Point Dam and Englebright Dam. It also provides analysis of two partial dam removal options with fish ladders at Englebright Dam. At Daguerre Point Dam, the full removal approach includes an upstream water diversion and fish bypass to preserve continuity of water diversion capabilities to the Hallwood-Cordua and South Brophy diversion canals. Three additional options are investigated at Daguerre Point Dam that leave the dam in place, but alter it to allow volitional passage of sturgeon and salmonids while maintaining the existing capacity of water diversion facilities.
Species considered in these analyses include anadromous salmonids and green sturgeon. Only the most general passage criteria were considered for development of this feasibility level analysis. No detailed passage criteria were developed for this study. The fish passage approaches, listed below, have been developed to a level sufficient to analyze their construction feasibility.
Background
Large diversions of water from the Yuba River watershed for hydraulic mining and agricultural purposes outside of the watershed started in the late 1800s. Hydraulic mining activities were no longer allowed in the lower Yuba River after 1930. Daguerre Point and Englebright Dams, currently owned and operated by the U.S. Army Corps of Engineers, are located in northern California on the Yuba River approximately 12 miles and 22 miles, respectively, from the confluence of the Yuba and Feather Rivers. The dams were built in 1910 (Daguerre) and 1941 (Englebright) as barriers to reduce high sediment loads from moving
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report downstream. Englebright Dam also diverts water into two power tunnels for power generation at the Narrows I and Narrows II facilities. PG&E operates Narrows I under FERC license 1403 which is rated at approximately 12 MW and YCWA operates Narrows II under FERC license 2246 which is rated at 55 MW. Both hydropower operations are authorized by the Army Corps via separate lease of power privilege agreements. Daguerre Point Dam started construction in 1906 and was most recently reconstructed in 1964 by the Corps due to extensive flood damage. Construction of these two dams terminated most of the sediment supply (except for suspended sediment) passing Englebright Dam and completely blocked upstream fish passage above Englebright Dam. The Yuba River supports a number of anadromous fish species under NMFS’ jurisdiction, including spring-run Chinook salmon, California Central Valley steelhead, and North American green sturgeon which are listed under the Endangered Species Act as Threatened. NMFS has also designated critical habitat on the Yuba River (downstream of Englebright Dam) for Central Valley spring-run Chinook salmon and California Central Valley steelhead. In addition, NMFS has designated the Yuba River as essential fish habitat (under the Magnuson-Stevens Fisheries Conservation and Management Act) in the lower and upper Yuba River – upstream of Englebright Dam - to the natural extents of historical fish passage. This report investigates volitional fish passage options at both dams including full and partial removal of the dams. Partial removal options at Englebright Dam would lower the height of the dam providing a lower-height fish ladder, which would likely improve passage efficiency when compared to a ladder that surmounts the full height of the existing dam. A previous report10 investigated fish passage options including fish ladders. This report builds on the work conducted in that report. Background information for this report was also based on Pre-Application Documents for FERC Project 2246 re-license application and other documents listed in the References section at the end of this report.
Water Use and Water Quality
Water use in the Yuba River between Englebright and Daguerre Point Dams includes fisheries, irrigation, hydropower, and recreational uses. Removal or alteration of Englebright Dam would affect hydropower production and recreational uses. Removal or alteration of Daguerre Point Dam would affect irrigation water diversions and fish passage functions of the dam. Both dams retain sediment. The Stillwater Study investigates the effects of sediment erosion and transport associated with removal or alteration of the dams. The relative amount of sediment captured behind Daguerre Dam is small in comparison to that which is impounded behind Englebright Dam. Alteration or removal of these structures would affect water quality downstream of the dams to varying degrees depending on the alternative. Significant sediment transport and turbidity impacts would be produced by removal of Englebright Dam.
10 Yuba River Fish Passage Conceptual Engineering Project Options, conducted by MWH Americas, Inc. 2010, National Marine Fisheries Service Southwest Region Habitat Conservation Division
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The impacts would be expected to accrue in the near-term following dam removal, decreasing over time as riverine conditions approach a new equilibrium.
TSS and bedload quantities downstream of Englebright Dam would be determined primarily by the approach to dam removal as well the sequence, timing, and magnitude of flood flows experienced in the Yuba River following the removal process.
Appraisal level investigation of dam removal or alteration effects on irrigation and fisheries are investigated in this report. Each of these topics will require additional study should a proposed project be further developed. No investigation of recreational or toxicology effects was undertaken as part of the scope of this study. These are two additional issues that will need to be addressed in separate studies.
Hydrology
A full discussion of Yuba River hydrology is provided in the Stillwater Study. The following chart showing the historical average daily and peak daily flows below Englebright Dam from October 1942 through October 2011 is provided for reference.
Flow below Englebright Dam Data for site 11418000 for Water Years 1942 to 2011 7,000 140,000
Average Daily Flow Maximum Daily Flow
6,000 120,000
5,000 100,000
cfs
-
cfs -
4,000 80,000
3,000 60,000
Average Daily Flow Daily Average Maximum Daily Flow Daily Maximum 2,000 40,000
1,000 20,000
- 0 10/1 10/31 11/30 12/31 1/30 3/2 4/1 5/1 6/1 7/1 8/1 8/31 9/30 Day of the Year
Figure 1 Yuba River Hydrology Daily Average and Maximum Flows
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Fisheries Downstream of Englebright Dam
Anadromous fish are present in the Yuba River downstream of Englebright Dam in every month of the year.11 Removal of the dams would release a large volume of sediment downstream which would affect water quality and impact fish in the river. Neither this investigation nor the Stillwater Study includes a study of optimum timing for release of the sediment. However, both GEC and Stillwater Sciences participated in a similar study for the removal of three Klamath River dams in California and one in Oregon. In that study, mid-November was determined to be the optimum time of the year for release of sediment. Based on the discussions undertaken for the Klamath River dams, dam breaching is assumed to occur in mid-November in this study.
Water Diversion
Although originally built as a sediment retention dam, Daguerre Point Dam’s primary function is now as a water diversion dam. The dam was built on a rock ledge, as shown in Figure 5, which helps maintain the water level for diversion. YCWA is the largest water right holder on the Yuba River. Various water districts, irrigation districts, water companies, and individuals contract with YCWA for delivery of water. Some of the parties that receive water from YCWA have their own appropriative or riparian rights for diversion of water. Investigation of the current state of water withdrawals and water rights are beyond the scope of this document. Some documents have indicated that YCWA’s water rights include the right to directly divert as much as 1,550 cfs from the lower Yuba River for irrigation and other uses from September 1 to June 30, and to divert a total of 961,300 acre-feet to storage in New Bullards Bar Reservoir from October 1 to June 30 for subsequent irrigation and other uses (SWRCB, 2001).12 However, a recent Biological Assessment document for operation and maintenance of Englebright and Daguerre Point dams states that the three diversions at Daguerre Point Dam have a total combined capacity of capacity of only 1085 cfs.13 Concepts developed for water diversion facilities that would replace the current facilities after dam removal or modification are based on diverting 1,085 cfs at or near Daguerre Point Dam. Originally the purpose of the Daguerre Point Dam was to retain hydraulic mining debris. Later, the dam began to be used for diversions of irrigation water, primarily between April and October. Daguerre Point Dam is the primary water diversion point for three irrigation users. Hallwood-Cordua Canal is entitled to divert 160,000 acre-feet annually at the dam on the right bank at a rate of approximately 600
11 Lower Yuba River Accord, River Management Team Interim Monitoring & Evaluation Report, Chapter 4, April 2013
12 Proposed Baldwin Hallwood Mine Expansion Project, Environmental Setting, Impacts, and Mitigation Measures, 4.7 Hydrology/Water Quality. 13 Biological Assessment for the U. S. Army Corps of Engineers Ongoing Operation and Maintenance of Englebright Dam and Reservoir, and Daguerre Point Dam on the Lower Yuba River, Draft, HDR Engineering, Inc. for U.S. Army Corps of Engineers, Sacramento District, October 2011
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report cfs. The South Yuba/Brophy Diversion Canal and Facilities diverts water at a location about 1,000 feet upstream of the dam on the left bank. The intake to the Brown’s Valley irrigation ditch diverts water for agricultural use less than one mile upstream of Daguerre Point Dam on the right bank. Water diverted from the Yuba River for Brown’s Valley is elevated just beyond the diversion point by a lift station. “Browns Valley Irrigation District (BVID) maintains a screened diversion upstream of all other proximal Daguerre Point Dam diversion facilities. The facility resides on a small channel that runs parallel to the main channel and rejoins after approximately 4,000 ft. The facility is composed of a fish screen, a diversion lagoon, and a pumping station. The diversion lagoon is approximately 250 ft long by 70 ft wide. The facility is rated for diverting up to 65 cfs and BVID is under contract with YCWA to have up to 9,500 acre-feet of water during the months of April to August. The fish screen was installed and became operational in April 1999. A gabion and steel structure supports the actual fish screens. The structure is anchored by 12 concrete-filled steel posts drilled into bedrock with steel members welded to those posts. The structure's abutments are rock-filled gabions, with three rows at the base of the abutment tapering up to one row at the top. The abutments are keyed into the gravel banks adjacent to the structure. The surface of the gabion abutments facing the diversion channel is coated with Gunite.14” “The Hallwood-Cordua Diversion, a gravity flow diversion facility located on the north bank of the lower Yuba River just above Daguerre Point Dam, has a diversion capacity of 625 cfs (SWRCB 2001). The diversion was originally screened in 1972, and the original screen was modified in 1977 (CALFED and YCWA 2005). The original screen was located in the North Canal about 0.25- mile downstream from the river diversion, and utilized V-shaped perforated plate screen construction. A bypass system diverted fish captured by the screen into a collection tank, and the collected fish were returned to the Yuba River either through a pipeline or by truck (SWRCB 2001). In 2001, the modified original fish screen was replaced with the existing fish screen that more closely conforms to CDFG and NMFS fish screening criteria. This screen is at the same location as the original screen, but has more appropriate-sized openings and sweeping and approach velocities to facilitate direct return of screened fish back to the river below Daguerre Point Dam. Additionally, the existing fish screen is operated for the entire diversion season (NMFS 2002). The South Yuba-Brophy Irrigation Diversion is located proximally above Daguerre Point Dam opposite the Hallwood-Cordua Diversion. The diversion headworks consist of an intake channel and bypass channel, a porous rock gabion fish screen, a diversion pond (approximately 1 acre in size) behind rock gabion wall, and an irrigation canal. The rock gabion is approximately 300 ft long and is 30 ft wide at its base narrowing to 10 ft wide at the top. Water flows into the small side channel
14 Study 7.12, PROJECT EFFECTS ON FISH FACILITIES ASSOCIATED WITH DAGUERRE POINT DAM, Yuba County Water Agency, Yuba River Development Project, FERC Project No. 2246, May 2012
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where it can be diverted through the gabion or flow through the channel back into the mainstem. Water entering the diversion pool percolates through the porous cobble-sized rock held together by mesh. Water can be released into the main irrigation canal through 5 ft diameter pipes, which is regulated by a gate at the head of each pipe. The pipe extends approximately 600 ft underground to the main irrigation canal.15 ” Figure 2 shows the three diversion locations with Daguerre Point Dam in the lower left corner of the figure. Figure 3 and Figure 4 show aerial close up views of the Browns Valley and South Yuba-Brophy diversions.
Figure 2 Location of Surface Water Diversions near Daguerre Point Dam
15 i.b.i.d.
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Figure 3 Browns Valley Pumped Diversion upstream of Daguerre Point Dam
Figure 4 South Yuba- Brophy Irrigation Water Diversions near Daguerre Point Dam
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Figure 5 Historic Yuba River Upstream of Daguerre Point Dam16
Description of Facilities
The U.S. Army Corps of Engineers (Corps) owns, operates, and maintains Englebright and Daguerre Point Dams. Although requests for structural design drawings for the dams were made on several occasions by NMFS personnel, drawing sets were not provided by the Corps of Engineers due to concerns about distribution of sensitive information. A plan view drawing of the dam from the original construction
16 Geochemistry of Mercury and other Trace Elements in Fluvial Tailings Upstream of Daguerre Point Dam, Yuba River California, August 2001, Figure3.
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The information upon which this study is based was taken from numerous documents that were already in the public domain. Computation of the volume of concrete that would be required to be demolished should Englebright Dam be removed, of primary importance for a dam removal investigation, was ultimately based on copies of original design drawings found in a published seismic analysis of the dam. Actual as-built drawings of Daguerre Point Dam were not provided or found.
Concrete removal volume for Daguerre Point was estimated based on photographs and similar structures. As a means to estimate concrete volume in the dam, photographs of the dam and its appurtenances were used to compare objects of known measurements, and these were used to develop a scale appropriate to the aerial photographs of the structure. In addition, height and width dimensions were taken from published materials. Subsurface volumes were estimated by extrapolating from the dam’s crest to the water surface, and then estimating the volume that would likely be in the foundation to support the elements that can be seen above the water surface. These estimates were also compared with proprietary knowledge and experience of similar structures.
Figure 6 shows the location of the dams in relation to the river and the basin.
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Figure 6 Yuba River Basin in Yuba County (From Figure 5-1 Proposed Lower Yuba River Accord June 2007 Draft EIR/EIS Page 5-2)
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Englebright Dam
Englebright Dam and Reservoir are located on the Yuba River approximately 22 miles (36 km) upstream of the confluence of the Yuba and Feather rivers and about nine miles downstream of New Bullards Bar Reservoir. It impounds the waters of the North, Middle and South Yuba Rivers. The concrete arch structure is approximately 260 feet tall (as measured from the original stream bed to the top of the non- overflow section) by 1,142 feet wide. It impounds a narrow reservoir with an area of approximately 800 acres and is approximately 9 miles long. The reservoir contained approximately 69,700 acre-feet (AF) at the time of construction (86.0 x106 m3) with 24 miles of shore line. It has an upstream contributing area of 1,108 mi2 (2870 km2). Approximately 365,000 cubic yards of concrete were placed in the construction of the dam. This includes concrete placed in the foundation below the river bed and in the rock abutments on each end of the dam. Approximately 210,000 cubic yards of that concrete would need to be removed to completely remove the visible portion of the dam above the abutments and foundation. Englebright Dam was constructed by the California Debris Commission in 1941. Its primary purpose, at that time, was to contain debris and sediment from anticipated future hydraulic mining activity in the Sierra Nevada foothills (although this mining activity did not resume after World War II) to help mitigate flood risk in the Central Valley near population centers in Marysville and Yuba City.
Since construction of the dam, a significant volume of sediment has deposited in the reservoir. The Stillwater Study that was conducted in conjunction with this report states: “According to the analysis of Snyder et al. (2004b), there were approximately 26 million metric tons (28.7 million tons, U.S.) of material in Englebright Lake deposits in 2001, of which 64.7 to 68.5% is sand and gravel.” Table 3a of Snyder et al. lists the total volume of trapped sediment as 21.9 million cubic meters (28.6 million cubic yards).
In addition to the original intended function as a debris dam, Englebright Dam and Reservoir has become a recreational facility and a keystone element of a hydroelectric power generation complex. The scope of hydropower operations involves a lease of power privilege rights, which the Corps granted by contracts to Pacific Gas & Electric and Yuba County Water Agency for operations of the Narrows I & II power plants, respectively. The Narrows I and Narrows II facilities effectively use the dam as a point of water diversion from the reservoir.
Narrows I hydroelectric plant (FERC No. 1403), features a 12.0 MW powerhouse owned and operated by PG&E downstream of the dam on the left bank, has a maximum gross head of 240 feet and a discharge capacity of 730 cfs at normal maximum gross head. The generators and powerhouse are located on the opposite side of the river about 500 ft. downstream of Narrows II. Narrows I intake is located on the left bank about 80 feet upstream of the dam. Water flows into a 9 foot diameter tunnel at elevation 450 and travels along the left bank to the powerhouse. Narrows II hydroelectric plant (FERC No. 2246), constructed in 1970, is part of the Yuba River Development - owned and operated by the Yuba County Water Agency. The 55 MW power plant is located on the Yuba River about 400 feet downstream of Englebright Dam on the right bank. Water to
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report the turbine is delivered from the intake structure located on the right bank of Englebright Reservoir about 200 feet upstream of the dam, through a 717- foot long power tunnel. At full load and full head (235.0 ft. gross head), Narrows II has a discharge capacity of about 3,400 cfs. The intake for the Narrows II Powerhouse is a tower located on the northwest side of Englebright Reservoir adjacent to Englebright Dam. The tower receives water from the surface of Englebright Reservoir down to an elevation of 439 feet, about 80 feet below the normal maximum water surface elevation. Access to the Narrows II power plant is gained via a narrow one lane paved road along the right bank of the river. The Narrows II Powerhouse Penstock is a tunnel 20 feet in diameter with a concrete lining in the upper 376 ft. The final 371.5 feet of the penstock is 14 feet in diameter and steel lined. The penstock has a maximum flow capacity of 3,400 cfs. Narrows II flow bypass is a valve and penstock branch off the main Narrows II penstock that was added to the Project in 2008 to provide the capability to bypass flows of up to 3,000 cfs around the Narrows II Powerhouse during times of full or partial Powerhouse shutdowns. The Narrows II Powerhouse is located at the base of the USACE’s Englebright Dam. The powerhouse consists of one vertical axis Francis turbine with a capacity of 55 MW at a head of 236 ft and flow of 3,400 cfs. Under most circumstances the Englebright-Narrows hydroelectric operations redirect the flow of the Yuba River through the power plant penstock(s) and turbine(s); thence the entire Yuba River flow is discharged from the powerhouse(s) at points downstream of the dam. Englebright Dam has no existing low level outlets or flow control gates, so water occasionally spills over the dam crest when the power plants are shut down, or uncontrolled floods exceed power plant capacity. Englebright Dam also impounds water to form Englebright Reservoir, which serves an important operational function as an afterbay for New Colgate Powerhouse, another YCWA hydroelectric facility located further upstream. Storage targets for Englebright Reservoir are used to provide space for attenuating power peaking releases from New Colgate Powerhouse, and tributary inflows. During flood events, uncontrolled spills overtop Englebright Dam.
Because these inter-related and inter-dependent facilities were constructed without upstream or downstream fishways, the Englebright Dam and the Narrows hydroelectric power complex constitutes the upstream limit of anadromous and resident fish migration, and no facilities are provided to prevent entrainment of fish from the reservoir into the turbines.
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Facility Details at Englebright Dam17
Table 1 Power Generating Facility Details
Narrows I Narrows II Intake Invert Elevation 450 msl Intake Invert Elevation 439 msl Tunnel diameter 9 ft Tunnel diameter 20 ft Tunnel length N/A ft Tunnel length 750 ft Flow Capacity 730 cfs Flow Capacity 3400 cfs Generating Capacity 12 MW Generating Capacity 55 MW Head 240 ft Head 236 ft outlet elevation 284 ft outlet elevation 284 ft Centerline of Narrows II outlet 292.0 ft Powerhouse Top Deck 348.0 ft
Seismic Design 18– The project site is located 3.7 miles (6.0 km) east of the Swain Ravine fault zone, which continues north to include the Cleveland Hill fault, source of the 1975 Oroville earthquakes. This fault zone is considered by DSOD to be capable of generating a M6.5 earthquake. Attenuation relationships indicate that this earthquake has a peak horizontal base rock acceleration of 0.50g at the site
Table 2 Englebright Dam Details
Dam Height19 260 feet Concrete Volume Above Original 210,000 cubic yards (CY) Grade20 Concrete Volume Placed during 365,000 CY Construction21
17 Where available, information was taken from Yuba County Water Agency, 2010, Pre-Application Document, Yuba River Development Project, FERC Project No. 2246. Information not available in these documents was supplemented as referenced. 18 U.S. Army Corps of Engineers, Sacramento District, November 1986, Seismic Evaluation of Englebright Dam, Harry L. Englebright Lake, Yuba River, California 19 Yuba County Water Agency, 2010, Pre-Application Document, Yuba River Development Project, FERC Project No. 2246. 20 Further discussion provided in Appendix C 21 California Department of Water Resources, Division of Safety of Dams, on-line dam base for Englebright Dam
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Table 3 Englebright Lake22:
Lake Area 800 Acres Lake Volume 69,700 Acre-feet Normal Max. Res. W. S. 527.0 ft Min Res. W. S. 475.0 ft Normal Tail water 290.0 ft Trapped Sediment Volume23 26 Million metric tons
Figure 7 Facilities at Englebright Dam24
22 Yuba County Water Agency, 2010, Pre-Application Document, Yuba River Development Project, FERC Project No. 2246. 23 Snyder et al. (2004b)
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Daguerre Point Dam
Daguerre Point Dam is located on the lower Yuba River approximately 11.5 River Miles (RM) upstream from the confluence of the lower Yuba and lower Feather rivers. The structure is a reinforced, overflow concrete ogee (“s shaped”) spillway with concrete apron and concrete abutments. The ogee spillway section is 575 feet wide and 26 feet tall. It is owned by the U.S. Army Corps of Engineers. The appurtenances consist of concrete abutments, concrete fishways on both abutments, and irrigation diversions at the northern and southern ends of the dam. The dam currently provides hydraulic head for these two diversions and one upstream diversion. Construction was completed, and Daguerre Point Dam became operational in 1910. The dam was equipped with two fish ladders in 1937 that Chinook salmon and steelhead have difficulty, under certain flow conditions, locating and navigating. Park personnel of the Corps administer the operation of the fish ladders and maintenance of the dam, in coordination with the California Department of Fish and Wildlife. The two fish ladders, and three licensed irrigation diversions, (Hallwood-Cordua, South Yuba/Brophy Diversion, and Browns Valley Irrigation diversion), depend on either the hydraulic head created by the dam (Hallwood-Cordua, South Yuba/Brophy Diversion) or the continuance of diversion capabilities due to the influence of the dam preventing additional channel incision above the dam (Browns Valley) .25 “According to John Nelson, DFG Region II, the three diversions generally extract water from late March through January (peak diversion season from March to October) with a potential diversion rate of 1,085 cfs. However, it is important to note that water diversions at Daguerre Point rarely approach capacity (Yuba County Water Agency 2003).26 ”
Construction started in 1906 on the Yuba River in Yuba County to prevent hydraulic mining debris from washing into the Feather and Sacramento Rivers. The Rivers and Harbors Act of 1902 authorized the construction of the Yuba River Debris Control Project, of which Daguerre Point Dam is a part. Upon decommissioning of the California Debris Commission, by passage of the Water Resources Development Act of 1986, administration of Daguerre Point Dam was transferred to the Corps. The dam is no longer operated for flood control. It impounds a reservoir volume of about 2.4 million cubic yards27 (1.8 million m3), and has been entirely filled with sediment for most of its history. The current position of the Yuba River behind the Daguerre Point Dam is north of its pre-mining channel and above its prior streambed elevation. Flood water is directed to and over the dam by large walls
24 Yuba County Water Agency, Pre-Application Document, November 2010 25 ENTRIX, Inc., Stakeholder Review Draft, June 2003, DAGUERRE POINT DAM FISH PASSAGE IMPROVEMENT PROJECT 2002 WATER RESOURCES STUDIES “The dam also functions to create head for water diversions to six area irrigation districts: Hallwood Irrigation Company, Cordua Irrigation District, Ramirez Water District, South Yuba Water District, Brophy Water District, and Browns Valley Irrigation District. Irrigation water is diverted through three separate diversions within the impoundment area upstream of the dam.” 26 Bulletin 250 -2005, Fish Passage Improvement, An Element of CALFED’s Ecosystem Restoration Program 27 Stillwater Study
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report constructed of tailings stacked by specially constructed dredges. These constraining walls are known locally as training walls and currently hold the Yuba River in its position upstream of the dam. The training walls, which were constructed using dredge tailings, force the Yuba River to flow as far north as possible to avoid erosion into the Yuba Goldfields. The Yuba Goldfields consist of more than 8,000 acres of dredged landscape. Figure 6 shows the approximate location of the dam and goldfields. By 1935 the training walls extended 85,100 feet which provided two 500- foot wide channels which held back millions of cubic yards of mining debris which would otherwise have been washed downstream. The flood of February 1963, estimated at about 120,000 cfs, washed out a section of Daguerre Point Dam between the mid-stream stations and, before significant repairs could be made, the flood of December 1964 washed out much of the rest of the dam and eroded the underlying rock foundation to an estimated depth of 15 to 25 feet (Corps 2007). The floods of 1964 also washed out nearly all of the sediments and debris that had accumulated behind the dam up to that time. The dam was rebuilt in 1964 following damage from floods. It sits on a bedrock bench in the piedmont plain of the ancestral Yuba River. A cut 600 feet wide and 25 feet deep was dug in the bedrock bench for the footing of the dam. An estimated 45,000 cubic yards of concrete were placed in the most recent construction. Removing the dam completely would involve removing approximately 27,000 cubic yards of concrete. The Daguerre Point Dam was constructed in a cut above and to the north of the original Yuba River channel.
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Basis of Design and Analysis
The Basis of Design has been established to state the goals of the project, the project extents and limitations, and the assumption made in the design process. The results of engineering analysis can vary widely depending on these initial assumptions and conditions. Results especially rely on the initial assumptions made regarding the nature of the various elements, with particular emphasis herein on assumptions dealing with sediment disposition. For this project the most important assumptions regarding feasibility and cost are discussed below.
The following discusses the general concepts and issues associated with dam removal decisions regarding the extent of removal, the timing of removal, the speed of demolition, and the impacts associated with these variables. While these concepts would generally apply at both Englebright and Daguerre Point Dams for any of the proposed actions, the volume of sediment and associated downstream impacts would be much smaller at Daguerre Point. Therefore, the following discussion regarding the rate of structure removal and associated water quality impacts applies primarily to Englebright Dam.
Removing the two dams concurrently or successively must be considered due to downstream impacts from sediment releases, water diversion, water quality, construction costs, fisheries considerations, and construction impacts. Timing of sediment releases from reservoir drawdown will affect water quality and fish. The extent of dam removal, i.e. - full or partial removal, will also have an effect on water quality and fish to varying degrees.
Removal Sequence
Generally, the sequence of dam removal can affect water quality and river flow volume downstream of the projects. Past dam removal investigations have considered removing upstream dams prior to downstream dams so that downstream reservoirs can be used as stilling basins to trap suspended sediment from upstream removals. The objective of this approach is to reduce overall water quality impacts. Since Daguerre Point Dam has very little storage capacity, it has no ability to trap or mitigate sediment releases from Englebright. Therefore, there is negligible water quality advantage gained by leaving Daguerre Point Dam in place while Englebright is removed.
Removing either dam will result in some increased sediment load downstream of the dams. The extent of the impacts will depend on the actual volume and composition of the sediment that is released, removal timing, rate of reservoir lowering, and extent of dam removal as discussed elsewhere in this report. However, since little sediment would be eroded by removing the Daguerre Point Dam, removal sequence will have little effect on downstream water quality issues associated with turbidity issues.
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Water Quality Associated with Reservoir Lowering
All discussion regarding the rate of drawdown of the Englebright Dam reservoir is based on the assumption that sediment in the reservoir is not removed before the reservoir is lowered and is eroded downstream as the reservoir level drops. The rate of lowering Englebright reservoir will determine the Total Suspended Solids (TSS) levels and duration downstream of the dam. Two approaches are considered for controlling the rate of lowering the reservoir – (1) notching, and (2) opening a low level outlet. The first of the two approaches lowers the reservoir (notching) at a much slower rate than the second (low level outlet).
Removal of the Glines Canyon and Elwha Dams on the Elwha River and Milltown Dam on the Clark Fork Rivers are examples of using a slower release of the sediment through erosion. Removal of the Elwha River dams is being conducted by controlling periods of time during which the demolition of the dams, reservoir lowering, and eroding the sediment are conducted. Within these “windows” of time, no significant erosion of sediment is allowed in order to improve water quality conditions for better fish passage.
The approach used to remove Glines Canyon Dam on the Elwha River, for instance, involved incremental notches in the top of the dam. Initially a section of the dam was demolished to create a notch in the top of the dam, thus allowing water behind the dam to flow through this lower elevation opening. Each time a section or notch reached a new lower elevation the reservoir water elevation dropped by the depth of the notch. In a matter of hours, the water elevation in the reservoir dropped to a level controlled by this new notch elevation.
The lowered reservoir allowed the dam concrete remaining above the water elevation to be demolished in dry conditions. Lower reservoir water elevations also eroded sediment upstream of the dam as the lower elevation exposed more sediment to river flow, causing erosion. While this approach allows for control of the timing of spikes in downstream TSS levels, it also extends the period of time during which elevated TSS level occur compared to the low level outlet approach.
Past investigations for removal of dams on the Elwha and Klamath Rivers concluded that the duration of the increased downstream sediment load should be reduced to as short a period of time as feasibly possible to reduce impacts to water users and wildlife. Water users that divert water from the river benefit from the shorter duration of high TSS and bedload because the period of time that mitigation measures are required is reduced. Fish and wildlife along the river benefit from a shorter duration of high TSS due the reduced time of exposure.
Rapidly eroding a large sediment volume will greatly increase TSS levels beyond acceptable values in the short-run; but this approach has the significant advantage of greatly decreasing the duration of high turbidity events. For that reason, rapid removal procedures were considered a better choice over the long-run on the Elwha River, as well as for the Condit and Marmot Dam Removal Projects.
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Planners determined that sediment concentrations following a dam removal process are high enough to reach lethal levels to certain aquatic organisms of concern regardless of the approach. Higher concentrations beyond those levels have no further negative effect. Furthermore, even though levels of TSS may be lowered by releasing sediment at lower rates over a longer period of time, even sub-lethal levels can have a greater cumulative detrimental impact on biology and human use of the water.
The recent removal of Condit and Marmot Dams successfully employed a more rapid drawdown approach than used on the Elwha River dam removals. Northwestern Lake, the reservoir behind Condit Dam, was drawn down in less than 3 hours by constructing a new low level outlet at the base of the dam. This low level outlet was essentially a large tunnel, constructed using explosive techniques.
Early dam removal studies on the Elwha River, Klamath River, for Condit Dam removal, and at Milltown Dam investigated dredging reservoir sediment as a means to eliminate or reduce downstream TSS to an acceptable level. The consensus conclusions for Elwha and Condit were: (1) dredging techniques, including use of silt curtains in the reservoir, would not reduce downstream TSS to an acceptable level, (2) dredging would significantly extend the time period of elevated TSS; thereby increasing the detrimental effects of TSS, and (3) benefits from dredging were not significant enough to justify the significant costs and construction time involved.
The Stillwater Study investigated release of the sediment over a period of years similar to the “erosion window” approach on the Elwha River. The study found that sediment deposition in the Feather River was not reduced by this slower erosion approach, but detrimental high suspended sediment concentrations above 5,000 mg/l existed for the duration of the erosion process. Since there is no specific apparent advantage resulting from a lower rate of reservoir removal, this report assumes that the most rapid means of dam removal which is feasible for the specific concept will be employed to remove the dams.
The rate of lowering the reservoir may be limited due to safety concerns associated with potential collapse of reservoir rim walls as the saturated walls become exposed. Since the Englebright Reservoir is bounded by rock walls and the reservoir behind Daguerre Point has very little depth, this report assumes that there is no practical limitation to the rate of lowering the reservoirs. The Stillwater Study report addresses flooding issues that might occur due to rapid drawdown of the reservoir and finds that this approach could increase extreme flood water elevations by approximately 4 feet (1.3 meters) but increased levee heights of 5 feet for a distance of one mile would protect against flooding.
The following provides a discussion of the engineering basis of dam removal, and includes a set of potential fish passage approaches that have not yet been described by others.
Sediment Management
Options for Sediment Management generally include: (1) removing the sediment either before, during, or after the dam is removed, or (2) leaving sediment in place and allowing the river to erode the
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report material as the dam is removed. Because of the steep terrain, high dams, and erodible soil in the arid western United States, many of the dam’s reservoirs contain a large volume of sediment. Most of the dam removal projects undertaken to date in this area have eroded the sediment either prior to dam removal (Condit Dam), or allowed sediment to erode as the dam was demolished (Elwha, Marmot, and Glines Canyon dams)
Managing trapped reservoir sediment for a proposed dam removal project is the largest cost and environmental consideration when developing feasibility and cost estimates for most large dam removal projects in the western United States. Where a dam has trapped a large volume of sediment, costs and complexity are greatly increased if the sediment must be handled, hauled, excavated, dried, separated, compacted, treated, and/or transported. Therefore, developing dam removal options must consider all approaches before an informed decision can be made. No final conclusion can be made without thoroughly examining the basis for an approach that mechanically removes reservoir sediment in advance of dam structure removal. If an initial, constraining assumption is that full sediment excavation and treatment is the only acceptable method of dam removal, any ensuing feasibility analysis may become radically distorted. Such a decision may also create a project that becomes more difficult to fund and undertake when compared to a project that allows natural processes to take place.
Except for the Milltown (at the confluence of the Clark Fork and Blackfoot rivers near Missoula, MT) and San Clemente (on the Carmel River in California) dam removal projects, all large dam removal projects in the western U.S. have been designed to manage reservoir sediments by allowing the river to erode the sediment. Sediment in Milltown’s reservoir were contaminated with materials from ore smelting that created very high levels of contaminants which were much greater than the natural levels in the surrounding water or land. While sediment analysis of reservoir sediments indicated areas of elevated contaminants, this situation was unique to this dam. One of the major reasons for removing the dam was that arsenic in the reservoir sediment was contaminating the groundwater aquifer used for Missoula’s domestic water supply. Eroding the sediment would have allowed the contaminated material to move to the next downstream reservoir. Sediment was ultimately removed using mechanical excavating equipment, loaded into rail cars, and transported to a secure location off site that permanently contained the toxic material.
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Options Developed
Based on the criteria previously discussed, and relying on information developed in the sediment transport analysis in the Stillwater Study, the following approaches to meeting the criteria were developed. Four separate alternatives were developed at both Englebright and Daguerre Point dams. Each of the alternatives could be implemented independently at each dam and are not dependent on implementation of a particular action at the other dam. However, some consideration of sequencing would be required due to potential aggradation and high sediment concentrations associated with complete removal of Englebright Dam, as discussed below.
Englebright Dam
Four alternatives for Englebright Dam were considered - featuring options for complete and partial dam removal. The partial dam removal alternatives include structural modifications to achieve fish passage objectives. Each option requires different sediment management and fish passage solutions. One partial removal option was reviewed, but not analyzed further. The alternatives investigated for Englebright Dam are described below:
1) Complete Removal: Complete removal of Englebright Dam down to the pre-dam surface along the abutments and to 5 feet below the pre-dam surface in the river thalweg (210,000 cubic yards). Power plants and appurtenances would be removed completely and power tunnels in rock or buried by soils would be plugged at both ends. Sediment behind the dam would be eroded downstream as the reservoir is lowered through a low level tunnel constructed for that purpose. Sediment remaining in the reservoir area following dam removal would be reworked, mechanically moved into the river as appropriate, and stabilized for public safety. The area would be graded, replanted, and restored to riverine riparian conditions over time. Appendix A provides further discussion and details of this approach. 2) Partial Removal to Operational Limits of Current Generating Equipment: Partial dam removal down to an elevation that allows use of the existing power tunnels with slight modifications. Elevation 460 was chosen, as discussed elsewhere in this report, to meet the existing operation criteria. Sediment above this elevation upstream of the dam would erode and fill in most of the reservoir leaving a small pool behind the dam. In this configuration the pool would not be capable of a large variation in elevation and the Colgate power operations might be reduced or compromised.
A 170 foot tall fish ladder for salmonids would be constructed to provide upstream volitional passage. Downstream passage facilities would also be provided in conjunction with the fish ladder – either integral to the fish ladder itself or constructed adjacent to footprint of the
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upstream ladder. The forebay would employ a method to screen and direct downstream migrants to a pipe, or some other suitable flow path for downstream passage. Appendix B provides further discussion and details of this approach.
3) Partial Removal to Retain All Sediment, Upgrade Intake Tunnels: Partial dam removal down to an elevation that retains the sediment currently stored behind the dam, with the exception of suspended sediment that would be created as upstream sediment is eroded further into the reservoir. Analysis of reservoir volume shows that an elevation of 130 feet above the base of the dam would retain all upstream sediment.28
A fish ladder would be designed and constructed with an adjacent (or integral) downstream fishway. Removing the dam to this lower elevation would require a reconfigured power intake and tunnel because the resulting reservoir elevation would be below the existing intake elevations. Gates would be installed in face of the dam to allow periodic flushing of sediment to keep the intakes free and provide a small pool for fish collection and migration from the ladder. More detailed analysis would be needed to assess whether the hydraulic and operational characteristics of such a system would satisfactorily meet power and in stream flow objectives. Appendix B provides further discussion and details of this approach.
4) Partial Removal to Limits of Conventional Fish Ladder: An option was also considered to lower the dam to an elevation approximately 100 feet above the tail water elevation so that fish ladder construction would fall into the “conventional” upper range of approximately 100 feet tall. Other passage facility components would be similar to those described in the previous two options. Preliminary analysis of this option, however, indicates that approximately half of the sediment in the reservoir, approximately 15 million cubic yards, would be eroded in this approach. Eroding this quantity of sediment would result in similar impacts to the complete dam removal option - without any significant advantage over the previous partial dam removal approaches. For this reason, this particular approach was not developed further in this report.
Daguerre Point Dam
Daguerre Point Dam elevates the water behind the dam allowing it to be used for diversion of water for several irrigation districts. One option for complete removal of Daguerre Point Dam with new upstream water diversion facilities was developed. Three options that would leave Daguerre Point Dam in place to continue providing water diversion capabilities, while also providing volitional upstream and downstream passage for salmonids and sturgeon, were developed. To provide passage for green sturgeon a flatter slope than is generally provided for ladders designed solely for salmonid passage would be required. No specific design guidelines for sturgeon fish passage were found or developed for
28 Stillwater Study
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report this investigation. However, based on literature reviewed29, a passage facility with approximately a 1% slope would allow all species of salmonid and sturgeon to pass. One percent is considered a fairly conservative criterion and should therefore address feasibility and costs if a slightly steeper facility is developed in future studies. The alternatives investigated for Daguerre Point Dam are described below:
1) Complete Removal: Complete dam removal would involve demolishing Daguerre Point Dam to approximately 5 feet below the downstream elevation of the river at the dam. To provide continuity of existing water diversion capacity, a new gravity diversion facility would be constructed approximately 2 miles upstream of Daguerre Point Dam. This facility would have a rock-lined, “nature-like fishway” which bypasses (or operates in tandem with) a new lower-head dam to provide effective upstream and downstream passage for salmonids, sturgeon, and other fish species. By moving the entire diversion point sufficiently upstream, elevation is gained to drive the existing (downstream) water diversions by gravity conveyance via connecting canals and siphons.
2) Rock Ramp Fishway: A second option would leave the dam in place and provide a rock ramp fishway to the top of the dam along the left bank of the river. For this conceptual study, the slope of the ramp would be about 1%. Approximately 10% of the river flow would be diverted through the ramp at average flows. A head gate would restrict higher river flows and limit excessively high velocities from diverting excessive water through the ramp
Developing design, operation, and construction criteria for this alternative is beyond the scope of work for this study. Actual flow requirements for specific times of the year and passage requirements would need to be set to develop this alternative further. Further study would be required to develop operational details for head gate control and water flow requirements through the ramp.
3) Downstream Weirs: The third option investigated would also leave the dam and water diversion facilities unchanged. This option would construct a series of weirs across the river. The first weir would be constructed at approximately 100 feet downstream of the dam and successive weirs would be constructed at lower elevations at 100 foot intervals downstream until the last weir was one foot above the natural streambed. Weirs would be constructed across the width of the river to intersect with both banks. A low flow notch would direct flow to the center of the river during drier conditions.
The midpoint elevation of each successive weir would be constructed one foot lower than the adjacent upstream weir. The weirs would be designed to allow volitional passage for both upstream and downstream migrants. Developing design and flow criteria for specific species, river flows, and fish passage timing is beyond the scope of this document. For the conceptual
29 Through-Delta Facility White Sturgeon Passage Ladder Study, Department of Water Resources, State of California, 2007
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design the weirs were located to develop a slope that would allow passage for sturgeon and salmonids. Conceptual design details are similar to a dam removal project successfully constructed near Shelton, Washington on Goldsborough Creek in 2003 by the U.S. Army Corps of Engineers.
Weirs would be constructed from driven steel sheet piles with concrete caps. The area between the weirs would be filled with material sufficiently dense to ensure that water passing the dam did not become subsurface flow. The gradient of the series of weirs would be approximately 1%.
4) Full Height Radial Gates: The fourth option studied involves a partial removal of a portion of the dam by installing full height radial gates. These gates would sit on a sill with an elevation near the elevation of the river at the base of the dam. Gates could be raised and lowered to allow free flow of the river. The existing fishways would be retained with this option to provide some degree of passage for salmon and steelhead under specific operational circumstances. Enhanced fish passage would be accommodated during periods when gates are opened to allow free passage of all fish in both directions. Operating or design criteria development is beyond the scope of this report. Operations of such a system would have to be coordinated with water diversion schedules and operations.
To fully develop this option, more information and analysis regarding water diversion quantities and timing would be required. However, conceptually, the gates could be opened for parts of a day, on particular days of the week, during particular seasons, or for particular migrations. To support this operation, some degree of surface water or ground water pumping may be needed to maintain continuity of water diversions temporarily when the radial gates are opened.
Development of this option would require investigation of water diversion timing and flow requirements, fish passage timing, and effects of lowering and raising the reservoir on resident fish near the dam. This option would also need to investigate means to restrict flow out of the water diversion intake facilities and canals at lower river water elevations. Gates would, generally, operate fully open or fully closed since water velocities would be too fast to allow passage of upstream migrants for partial openings. Downstream migration through partially open gates would require further investigation.
For reasons discussed elsewhere in this report, all of the removal options assume that river erosion will be the primary means of sediment management.
Complete Dam Removal Alternative
Completely removing both Daguerre Point and Englebright Dam would meet the goal of providing volitional passage for all fish species. Removal of Englebright Dam would eliminate power production at Narrows I and Narrows II power plants. No mitigation for the loss of power is proposed because it is
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report beyond the scope of this study. Specific mitigation measures associated with this alternative would need to be addressed in the future.
No power is produced at Daguerre Point Dam, but several water associations use the raised water elevation at the dam to divert water from the river for irrigation. As an integral part of the Daguerre Point Dam removal concept, a new upstream water diversion and bypass fishway is proposed to allow continuity of water diversions, as well as full volitional fish passage.
For the complete dam removal approach, removal of Daguerre Point Dam would be scheduled to occur concurrently with Englebright Dam. Further, more detailed study would be required to determine if removing Daguerre Point Dam several years after Englebright – in order to provide time for sediment released from Englebright to erode downstream - would provide any advantage. Aggradation at the proposed upstream diversion location, generated by sediment eroded due to removal of Englebright Dam, could require sediment removal to ensure continued operation of the bypass fishway and water diversion. Concurrent removal of both dams was chosen as the means to illustrate the conceptual removal because the Stillwater Study found that, in most flow scenarios, aggradation at the proposed upstream diversion site was not significant. Appendix A provides more details of complete dam removal at both dams. A brief description of the full dam removal proposals at each dam is provided below.
Englebright Dam
For full dam removal, the dam would be removed to an elevation 5 feet below the pre-dam river bed to ensure volitional fish passage past the dam and the reservoir. A tunnel would be constructed at the base of the dam to drain the reservoir and erode the sediment. Sediment behind the dam would be eroded downstream by river flow after breaching the tunnel. Any sediment remaining in the reservoir area after initial erosion would be graded and stabilized to ensure that the impact of sediment erosion is limited primarily to the first year after dam removal and to prevent safety hazards in the reservoir area. Details of the sediment erosion are provided in Stillwater Study.
Breaching the dam would occur in November to coincide with high river flows to avoid the majority of the Chinook salmon upstream migration and spawning period. The dam would be breached by constructing two tunnels, as discussed below, at the base of the dam to drain the reservoir over a period of approximately 4 days.
The dam would be demolished using a combination of the same drilling, blasting, and mechanical demolition techniques that were used successfully to remove concrete dams on the Elwha and White Salmon Rivers in Washington State. Access roads would be constructed on both the right and left bank of the river and would be used to remove demolished concrete to a reprocessing site for steel removal and crushing.
Approximately 250,000 cubic yards of concrete would be removed from the dam site. Much of the concrete in the original construction would remain below grade. Original construction documents
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report indicate that as many as 365,000 cubic yards of concrete were placed to construct the dam. However, analysis of cross sections of the dam, provided in Appendix C, indicate that only about 215,000 cubic yards of concrete were placed between the adjacent canyon walls above the riverbed. Foundation concrete accounts for the difference between the original construction volume and proposed removal volume.
To be conservative and to account for the low quality of the drawings used to analyze concrete volume, cost estimates and schedules assumed the removal volume to be approximately 250,000 CY, 15% greater than the volume computed. Appendix C provides further discussion and details of concrete volume calculations.
Temporary stock piles would be created near the dam sites to separate metal from the concrete and crush it for reuse and sale. Crushed concrete has an economic value. Several mining operations in the vicinity of the dams mine and sell rock for aggregate. Crushed concrete would be transported to one or several of these commercial establishments for resale as aggregate. Crushed concrete could also be used as aggregate or fill for other elements of the project, such as fill between weirs at Daguerre Point Dam if the downstream weir option were developed.
Cost estimates assume that demolished concrete would be sold as aggregate similar to the approach used for the Elwha dam removal. Temporary stock piles would be located within 2 miles of the dam. Land for these temporary and any permanent material relocation sites would be purchased or rented and rehabilitated after completion of dam removal.
The reservoir behind the dam would be graded and replanted to stabilize upstream sediments. Grading and reworking of the sediments would begin in the early spring of the year following the breach so that un-eroded sediment would have time to consolidate sufficiently to allow heavy equipment access.
A similar project, Condit Dam removal, was conducted on the White Salmon River near Bingen, Washington in 2011. After breaching the low level tunnel sediment behind the dam erode quickly but many areas of steep unstable sediment (slopes steeper than 1.5 horizontal to 1 vertical) remained on the banks adjacent to the river in the reservoir area. This material would have eventually experienced slope failures and eroded into the river; however, owners chose to use mechanical equipment to flatten bank slopes for safety reasons and to reduce future sediment erosion. An approach similar to the Condit Dam removal is proposed for this project. Stabilizing slopes would involve moving a portion of the un-eroded material into the river for immediate transport to reduce high sediment flows during future high flow events.
Construct a Low level Tunnel through the Base of the Dam To completely remove the dam, two tunnels would be constructed at the base of the dam, either by refurbishing the original bypass tunnel or constructing a new low level outlet through the base of the dam. Drawings of the downstream section of the dam, discussed in detail in Appendices A, B, and C,
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report show a plugged diversion tunnel between sections J and K. It may be possible to resurrect the tunnel for diverting flow during demolition. This tunnel also provides an indication of the opening size used for the construction of the dam and what size was structurally acceptable to dam designers.
Criteria for tunnel size construction would need to be developed in conjunction with other elements considering construction and other costs, structural impacts to the dam, timing of the breach, and impacts of the flow from the tunnel immediately after the breach. That level of investigation is beyond the scope of this study. Constructing a tunnel similar to the original tunnel size should meet structural safety considerations. Constructing a second tunnel near the bank on the opposite side was assumed to be structurally sound for this investigation.
Constructing a second tunnel would increase the amount of flow that could pass through the dam after the breach and would reduce the probability that rising water levels from high flows would overtop the construction activities during demolition. The Stillwater Study modeled the tunnel approach, called the Tunneling and Rapid Release alternative, using a 10 x 10 foot tunnel opening. Their results showed that a 10 x 10 foot tunnel would refill the reservoir in average and above flow years (Figure 25). Two tunnels with a larger flow capacity are proposed to reduce the probability of refilling the reservoir.
Breaching both tunnels simultaneously would produce an initial flow of approximately 22,000 cfs, similar to a two year flood event in this river.30 Breaching the tunnels consecutively would reduce the size of the initial flow to around 10,000 cfs. The second tunnel would be breached several days later to keep flows below this level. Keeping flows at this lower level would reduce downstream water levels and minimize sediment deposition on overbank areas. Appendix A provides further discussion of dam removal and tunnel construction.
Daguerre Point Dam
Complete removal of Daguerre Point Dam would involve demolishing the concrete dam and the adjacent fish passage facilities. Concrete in the river within the bank full channel would be removed to an elevation 5 feet below the pre-dam condition. Removing the dam would cause water diversion facilities at and upstream of Daguerre Point Dam to lose their ability to provide current water diversion capabilities.
Removal of dam concrete would be accomplished using drilling and impact hammer techniques. Gravel berms or steel sheet piles would be used to divert the river while sections of the dam were demolished in the dry in three stages as shown in Figure 8. The first stage of demolition would remove the southern section of the dam to create a diversion channel for river that would allow the northern section to be removed in dry conditions. The second stage would remove all but a small section of the dam where the sheet piles meet the dam structure. After stage II sheet piles and cofferdams were removed the
30 Stillwater Study, Table 3 lists the probability of 26,115 cfs (740 m3/s) event as having an exceedance probability of .477
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report remaining section that supported the dam sheet pile interface would be removed by accessing this section from the south shore in Stage III.
A full description of the removal approach is provided in Appendix E. A schedule for the removal and costs associated with full removal and upstream diversion are provided in Cost Opinions, below.
Figure 8 Complete Daguerre Point Dam Removal Stages
Upstream Water Diversion Facilities
Construction of upstream water diversion facilities would remove the need for Daguerre Point Dam. Removing the dam would significantly improve fish passage and protection in the Lower Yuba River. The complete dam removal alternative would include construction of an upstream facility that would maintain the reliability and continuity of existing water diversions during and after dam removal activities. Complete removal of Daguerre Point Dam would include moving the main point of diversion approximately 2 to 3 miles upstream of the present Daguerre Point Dam, in a reach beyond the effects of dam removal on the river gradient. The diversion facility would be located at a higher elevation - providing a new gravity water diversion capability through channels, pipes, and canals to the existing
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report water diversion facilities downstream. It would include fish screens and would regulate flows into the diversion facilities. By relocating to a higher upstream elevation, the new diversion would require a significantly smaller in-river diversion structure.
This approach would allow complete removal of Daguerre Point Dam without sacrificing the capability to maintain water diversions to existing water users. Facilities would include a low head dam with an adjacent nature-like fishway that would enable volitional passage for all fish species of concern. The diversion would consist of a flow splitter in the river, a low head rock or concrete dam downstream, and a grade control at the upstream end of the fish bypass ramp and diversion dam.
River flow would be split between the diversion channel and a fish bypass ramp. The diversion channel and dam would direct river flow into a canal which would deliver flow to concrete distribution chambers. The control chambers would divert and control flows into transport pipes. The pipes would deliver water under gravity flow to the existing diversion facilities. A screen at the entrance to the canal would remove debris. New fish screens upstream of Browns Valley diversion would direct fish back into the river before delivering it to irrigation facilities. The existing fish screens would continue to function as they currently operate for the Hallwood Cordua diversion. A similar facility has been constructed on the Elwha River in Washington State as part of the Elwha Dam Removal and River Restoration Project to replace pre-dam removal water diversion facilities and is currently operational.
Figure 9 through Figure 12 illustrate the conceptual elements of the upstream diversion facility. The proposed location would be beyond the influence of upstream erosion resulting from dam removal. Further study is needed to determine if a natural rock outcropping could be used to create a barrier to vertical changes in river thalweg or if a man-made grade control would be required. Figure 9 is for concept illustration purposes only. The concept could take other combinations and variations.
Further analysis of goals, objectives, and design criteria, will be required to fully determine the location alignment and details of this concept. For instance, a nature-like fishway that spans the entire river width may be desired to provide optimal fish passage and ensure long-term passage effectiveness. Future study would require, but not be limited to, hydraulic modeling and geotechnical investigations.
Removal of both dams would release a large volume of sediment downstream of Englebright Dam. The Stillwater Study indicates that river grades and elevations would vary for several years after breaching Englebright Dam. It concludes “Examinations of a full removal of Daguerre Point Dam with DREAM-2 indicate that erosion of impoundment deposits would extend for approximately 3 km (1.8 miles) upstream of the dam while sediment deposition would be limited to within approximately 3 km downstream of the dam.” Figure 13 shows the current river elevation with the approximate proposed diversion dam location and estimated long term profile above the dam after removal, as identified in the Stillwater Study.
Construction of water diversion facilities would start in the year before breaching Englebright. Diversion facilities would be completed prior to breaching Englebright and Daguerre Point Dams to
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report ensure water diversion was not curtailed due to dam removal. Temporary water supply enhancement may be required to ensure a steady supply during the times of diversion for irrigation. Both dredging to remove accumulated sediment and temporary well point construction would be included in this alternative.
Dredging would be employed to remove sediment from the channel during the first several years of operation. Well points are a standard technology, usually used for dewatering excavations. They consist of a pipe hydraulically inserted into the ground adjacent to a location from which water is to be withdrawn, a pipe to transport the water withdrawn from the well points, and a pumping system to raise the water from the ground. They are not wells in the conventional sense of a permanent vertical shaft installed with pumping facilities that operate over a long period of time. These temporary pipes would be employed to draw water from the alluvium when supplies from the diversion canal were insufficient. Appendix E provides further discussion and details of this approach.
Figure 9 Complete Daguerre Point Dam Removal Elements
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Figure 10 Detail of Diversion Dam Conceptual Arrangement
SEDIMENT BY-PASS PIPES RIGHT BANK
INTAKE CONTROL STRUCTURE TRASH SCREEN & GATE DIVERSION DIVERSION CANAL DAM LONGITUDINAL BARRIER FOR DIVERSION FISH BYPASS RAMP
SECTION THRU BY PASS CHANNEL 1 NTS
Figure 11 Section through Bypass Channel
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`
Figure 12 Longitudinal Section through Diversion Channel
Yuba River Thalweg Upstream of Daguerre Point Dam beginning 3,500 Feet Downstream of Dam Approximate 160 Location of River Profile before Dam Removal Proposed Diversion Dam
150 Estimated Long Term Profile after Dam Removal from Stillwater Study Conclusions
140 feet msl feet
- 130
Elevation Elevation 120
110
100 0 2500 5000 7500 10000 12500 15000 17500 20000 22500 25000 Distance - feet Starting 3,500 feet downstream of Daguerre Point Dam
Figure 13 Yuba River Elevation Upstream of Daguerre Point Dam
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Partial Englebright Dam Removal
Several partial removal options were explored at Englebright Dam as discussed previously. These options would provide a lower level of power production at Englebright Dam but would largely avoid effects from the large volume of sediment released in the full dam removal approach. Also, lowering the top of the dam would allow for a constructed fish ladder to operate within a more conventional height range. Details of the approach for concrete removal from the dam would be similar to those provided for full dam removal except that lowering the reservoir would occur by directing flow through the power tunnels or bypass tunnel instead of constructing a low level outlet at the base of the dam.
Lowering the reservoir would require that flow into the reservoir did not exceed the combined tunnel capacity. Demolition activities would necessarily need to occur during the period of the year when the river flow could pass through the power tunnels. Therefore, construction activities would be primarily confined to low flow months for these alternatives. As shown in Figure 1, river flows are higher in fall and winter months.
An alternative to using power tunnels to lower the reservoir not developed in this investigation would be to construct an outlet by tunneling through the dam with a tunnel invert elevation at the desired new dam overflow elevation. This approach would allow the reservoir to be lowered before demolition activities occur without using power or bypass tunnels. The option developed in this investigation would most likely be less costly since new tunnel construction would be costly relative to other types of demolition.
However, any modification of the dam structure would have an effect on the operating procedures for the dam including power production. Further study would be required to analyze power production options during and after modifications. For this study it is assumed that, for life safety and equipment protection reasons, power production at Englebright Dam would be curtailed during construction activities that modify the dam structure. New operating procedures would need to be developed for the lower head and storage conditions present after dam modifications.
Remove to El. 460 – Improved Fish Passage Using Current Equipment at Operational Limits
The height of the dam from the spillway to the pool at the base of the dam is currently about 237 feet (spillway elevation of 527 and pool elevation at 290 msl). This approach would remove Englebright Dam to an elevation just above the intake power tunnels for the power plants and lower the height of the dam from 237 feet to 170 feet. Flow through the power tunnels would lower the reservoir to allow demolition of the upper 67 feet of the dam. Approximately 60,000 cubic yards of concrete would be demolished using drilling and impact hammer techniques discussed in the Complete Removal approach. Appendices A and B discuss construction and demolition techniques in greater detail.
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Table 1 shows invert elevations for Narrows I & II power tunnels. The top of the tunnels are at elevation 458 and 459 for Narrows I & II respectively. Documents reviewed show the lowest operational lake level to be approximately elevation 475 msl without providing explicit details regarding the reasons for this elevation limitation.31 Partial removal of the dams would necessarily require a review and possibly development of new operating procedures for power production.
This investigation provides an analysis of removing the dam to the minimum elevation that would allow water to flow through the power tunnels, elevation 460. Further study would be necessary to develop details necessary for optimum power generation for a partially removed dam. Other alterations to the dam may be necessary to create the best operating solution such as extending the intake structures or installing flashboards.
This partial removal approach is developed to address the questions of cost and feasibility of partially removing the dam to provide enhanced fish passage while still allowing power production without extensively changing the power facilities. It illustrates the procedures and conceptual level costs associated with partially removing the dam. Results of investigating this approach are presented to show concept cost and feasibility. Because this is a concept level investigation, these results would remain applicable if further investigation showed that elevation 475 rather than elevation 460, some other elevation, or other modifications would provide a better compromise between fish passage and dam removal details.
The following approach, which investigates removing the dam to the lowest elevation that essentially retains all the trapped sediment, elevation 430, also investigates ways of providing continued power production by extending the intake to Narrows II at a lower elevation. That approach may also require other modifications to optimize power production. Details of both of these approaches are based on a criterion of providing a means for water to fully fill the penstock for power production. Further investigation and discussions with power generating organizations would be necessary to fully develop these concepts to meet power production and fish passage optimization criteria.
Water levels in the reservoir are currently raised and lowered to allow the facility to operate as a re- regulating dam. As discussed above, future investigations would be required to fully evaluate the lowest possible operational level; however, at this lower dam elevation water elevations could not fluctuate because the spillway elevation and intake tunnel elevations would limit the range. Therefore, if this design scenario were to be carried forward, it would be necessary to review the regulating function of the dam to determine whether additional lowering of the water intake structures is a feasible alternative.
In this approach, a vertical slot fish ladder would be constructed from the base of the dam to the top of the reduced height dam to provide volitional upstream passage for salmonids. Generally, it is thought
31 Fourth Five Year Safety Inspection Report, Yuba County Water Agency, New Narrows Powerplant, FERC Project No. 2246, Figure 3
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report that longer ladders create increased design and operational difficulty compared to shorter fish ladders at the same facility. A dam height of approximately 170 feet would require a shorter ladder compared to a fish ladder that would raise fish the entire 260 feet of the existing dam. Conceptually, resting pools and other physical and operational features could be designed for a fishway at this site to address engineering constraints and performance concerns. Further study would be required to determine design features of a full height fish ladder.
Figure 14 through Figure 16 show the proposed concept for a fish ladder and fish collection and handling facility that would be included in this approach. On these figures the fish ladder has been aligned so that the vertical profile follows the contour at a 10% slope along the adjacent hillside. In this approach the entire ladder and collection and handling facility would be constructed with the partial dam removal, this concept could potentially be a phased implementation of fish passage programs. For example, “phase one implementation” could involve a short ladder leading to a fish collection facility before dam removal occurred. This would enable collection and transport operations to reintroduce anadromous fish to targeted point(s) in the upper watershed. Phase two would be conducted as part of the dam modification and would involve a fish ladder extension to provide passage from the collection station (already raised above the river below) to the reservoir above the dam.
Additional details of the partial removal concept are provided in Appendix B. Appendix F provides further discussion on fish ladder construction. The actual layout of a fish ladder is subject to further design consideration, depending upon goals and objectives developed in a reintroduction planning process. For this investigation ladders were designed to follow the contour of the right bank up to the elevation of the partially removed dam at a ladder slope of 10 horizontal to 1 vertical.
A concrete ladder approximately 1,900 feet long would be constructed by blasting and excavating the rock walls of the canyon above the river on the north side of the river. The ladder would be constructed in a notch perpendicular to the power house access road where a bridge would be constructed over the ladder. The ladder would include upstream resting pools for approximately every 50 feet of vertical elevation rise and a multi-use facility to allow collecting, holding, evaluating, and tagging fish for transport.
The ladder’s entrance would originate near the discharge of the Narrows II power plant to take advantage of power tunnel flows which would be used as attraction flows at this location. It would enter a multiuse facility located adjacent to the power house access road where salmon could be inspected, counted, tagged, or loaded into trucks for transport upstream. This proposed facility would be located near the existing Narrows II powerhouse access road on the north side of the river approximately 50 to 75 feet above the river.
The road to the facility would be widened and paved to allow more space at the facility for maneuvering vehicles. A retaining wall and fill material would be constructed along the river bank to create a foundation for facility construction. A section of the dam where the ladder penetrates the dam would
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report remain at a slightly higher elevation (480 msl) than the spillway elevation of 460 msl to protect the ladder from damage from high flow during spillway operation.
Downstream migrants would be collected along the right bank of the reservoir just upstream of the Narrows II intake facility. Migrants would be guided to a multi-level weir collection facility by a full depth net across the forebay of the reservoir. For development of conceptual construction cost and schedule for this approach, it was assumed that juveniles would then travel in a 36-inch diameter pipe adjacent to the upstream fishway to the downstream river. Other approaches, not developed here, might also be possible such as guiding outmigrants into the fish ladder as an alternate to a closed pipe.
This investigation assumes the dam would be operated as a run of the river facility without storage after partial dam removal. In this condition water levels would remain fairly constant and would be controlled by the dam spillway elevation. A multi-level weir that would be adjusted to the water level or a floating weir that keeps a constant entry condition would direct flow into the pipe at the end of the net.
Figure 14 Fish Ladder and Lowered Dam at Elevation 460
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Figure 15 Multi Use Facility and Fish Ladder Entrance
Figure 16 Section through Fish Ladder near Switchback
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Remove to El. 430 – Fish Passage and Power Generation without Significant Sediment Release-
The second partial dam removal approach investigated would remove the dam to an elevation that allowed volitional upstream passage but avoided the impacts of releasing a large volume of sediment from the reservoir. The reservoir would be removed to elevation 430 msl, leaving the dam at approximately 140 feet in height. The sediment trapped behind the dam would reorganize itself to essentially fill the entire reservoir. Some sediment would be released in the form of suspended sediment as the reservoir water elevation declined.
This scenario would allow future sediment moving into the reservoir to move downstream but retain the existing sediment in the reservoir in a reworked condition behind the dam. The sediment volume behind the dam is estimated at 28.6 million cubic yards (21.9 million cubic meters). 32 The Stillwater Study provides additional details of sediment movement in the reservoir. Figure 17 shows the relationship between reservoir elevation and reservoir volume.
In the approach approximately 90,000 cubic yards of concrete would be removed from the top of the dam and a fish ladder and downstream fish collection system would be provided. The fish passage system would be very similar to the one discussed in the previous approach, except that the ladder would be shorter, reflecting the lower dam elevation.
Figure 18 shows the arrangement of the proposed facilities with Englebright lowered to an elevation of 430. Additional details of the partial removal process are provided in Appendix B. Appendix F provides further discussion on fish ladder construction.
With the reservoir essentially full, only a small pool near the dam would remain. Details of future sediment passage after notching the dam would depend on power system operations and will require further development. A conceptual approach to sediment passage developed for this report would use hydraulically operated gates cut into the face of the dam to periodically flush sediment away from the power intake tunnels. Periodic gate operations would lower the reservoir elevation and cause erosion of the sediment immediately upstream of the dam. A small pool would be formed in this area when gates were again closed. Power generation would be halted during this flushing operation because the water level would drop below the intake. At this lower elevation existing power tunnel intakes would be above the water elevation. Horizontal extension of the intake tunnels, starting at a lower elevation, would be required to allow continued power generation.
For this approach it is assumed that top of the power tunnel would be one foot below the lowest water surface elevation. As discussed in the previous section, operational considerations would need to be reviewed and new operating criteria developed before the optimum elevation of the power tunnel elevation could be determined. That level of investigation is beyond the scope of this conceptual study.
32 Stillwater Sciences Sediment Transport Study, 2013
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The elevation used for this investigation is the maximum elevation that would allow flow into the power tunnel. Appendix B has further discussion of this approach. Figure 19 illustrates the arrangement.
Englbright Reservoir Storage Volume versus Height above Dam Base Elevation - ft msl 295 345 395 445 495 545 60,000,000
50,000,000
40,000,000
Cubic Yards Cubic 30,000,000 -
20,000,000 Volume Volume
10,000,000
- 0 50 100 150 200 250 Height above Base of Dam - feet
Figure 17 Reservoir Volume versus Elevation
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Figure 18 Facilities Arrangement for Removal to Elevation 430
Figure 19 Proposed Sediment Flushing Gates at Englebright Dam
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Retention of Daguerre Point Dam with Fish Passage Improvements
Daguerre Point Dam was originally constructed to provide sediment retention but currently operates primarily as a means to elevate the river for water diversion upstream of the dam. Two approaches for retaining the dam with additional passage improvements are presented below that would allow the current water diversion arrangements to operate without change while providing passage for sturgeon and salmonids at the dam.
The two alternative approaches: a downstream rock ramp and a series of full width downstream weirs, were investigated as a means to improve volitional passage for salmonids and sturgeon. Alternative 1, a “rock-lined ramp,” would be built starting from a stable location between 2,500 and 3,000 feet downstream of the dam sloping at around 1% up to the top of the dam. Alternative 2, “downstream weirs,” would construct a series of weirs across the entire river downstream of the dam with approximately a 1 foot drop at each weir extending approximately 2,500 feet downstream. The ramp would require as much as 125,000 cubic yards of fill. Demolition of the upper portion of Englebright Dam could provide as much 90,000 cubic yards of fill material.
Rock Ramp
The rock ramp would be constructed at a relatively low gradient to accommodate upstream sturgeon passage. While studies have shown that green sturgeon can move upstream at gradients above 4% for short distances33, these studies have not been developed into formal passage criteria that have been vetted by regulatory and fisheries agencies. Therefore, for this initial level of design, the slope was assumed to be limited to an average of 1% to ensure feasibility of concept and a conservative cost estimate. It is assumed that if studies show acceptable passage viability at a 4% slope, those numbers would be at least the same (or likely better) in terms of overall project cost. Further investigation would be required to develop design criteria for this approach but this investigation was conducted to show the approximate cost and feasible construction techniques for this approach.
Details of pools and weirs within the ramp are beyond the scope of this design level but the ramp width was set wide enough to include low flow meanders and pools. The ramp would have a parabolic cross section in order to concentrate low flows to provide sufficient depth for passage. Higher flows would spill over the ramps sides to limit ramp flow and velocities.
At the downstream entrance to the ramp a grade control structure would be constructed to divert water for attraction to the entrance and direct fish to the ramp entrance. Flow in the ramp would be limited by gates at the upstream end to reduce velocities.
The ramp could be located along either the left or right bank of the river out of the high energy flow path to reduce potential erosion of ramp material during extreme high flow events. Figure 21 illustrates this concept with the ramp near the left bank. Figure 20 shows a section of the ramp near the dam.
33 Through Delta Facility White Sturgeon Passage Ladder Study, Department of Water Resources, State of California
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The base material, approximately 100,000 cubic yards, would need to be well graded material that would remain stable after compaction. Potentially this material could come from concrete removed from Englebright Dam or from sediment excavated from the Yuba Goldfields upstream of Daguerre Point Dam. Future investigation would be required to determine the suitability of the material, grain size, and ownership to assess the feasibility of using sediment in the gold fields for fill material. Approximately 25,000 cubic yards of rock surfacing material would come from nearby quarries.
A geotechnical liner would be placed beneath the upper layer of river rock to restrict water loss through the base of the ramp. The top of the dam would be notched approximately 1 foot to ensure that low flows move down the ramp. High flows that would increase velocities beyond desirable passage conditions in the ramp if not restricted, would be controlled by head gates at the top of the ramp. At the downstream end of the ramp, a grade control structure would direct low flows into the ramp entrance for attraction flows and to provide a barrier to restrict upstream migrant entry to the area immediately below the dam. A detailed discussion of weir construction is provided in Appendix D.
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Figure 20 Typical Ramp Section at Daguerre Dam
Figure 21 Plan View of Proposed Ramp at Daguerre Dam
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Downstream Weirs
Construction of full width weirs across the river downstream of Daguerre Point Dam would essentially bury the dam so that migrating fish would not be impaired at the dam. It would also allow water diversion facilities to remain operational and unchanged while still retaining all the upstream sediment.
An approach similar to this was constructed to remove the Goldsborough Dam near Shelton, Washington in 2003. Weirs were constructed from driven steel sheet piles to restrict loss of creek flow into material placed between the piles and provide structural stability. Concrete caps were placed over the steel sheet piles for smoother flow and abrasion reduction. A notch near the center of the weir concentrates low flow and directs the course of the stream.
For this approach downstream weirs would be constructed from driven steel sheet piles and capped with concrete. The slope of the river over the length of the weirs would be approximately 1%. Between the weirs the complexity of the stream could vary - possibly including resting and spawning areas. Notches near the center of the weirs would concentrate low flows to enhance passage for downstream and upstream migration. Beyond weir construction, no additional downstream enhancement would be required (other than screening the diversion intake structure, not included here).
Construction of the weirs would be in two phases to allow construction in the dry as the river is diverted from one side to the other in succeeding phases. Base material for fill between the weirs could come from uncontaminated sediment stockpiles upstream of Daguerre Point Dam, from concrete removed from the dam, or from any available fill material that would be stable as fill. Surfacing material would come from nearby aggregate supply companies.
A detailed discussion of weir construction is provided in Appendix D.
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Figure 22 Plan View of Proposed Weirs at Daguerre Dam
Figure 23 Section through Weirs
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Figure 24 Elevation of Weir
Full Height Gates
A third approach to fish passage investigated at Daguerre Point Dam involves installation of full height radial gates to allow intermittent lowering of the dam. Fish passage at Daguerre Point Dam could be accomplished by periodically eliminating the dam as a structural barrier. Installing radial gates would allow the barrier to be removed on an intermittent basis by raising the gates above the water surface. A free flowing river through the gate openings would allow upstream and downstream migrant passage. With the gates closed, water would be diverted through the canals. With the gates open, water would flow freely through the opening. Further study will be required to optimize the timing of gate opening considering fish passage timing, water diversion timing, and sediment erosion considerations.
Anadromous fish use the river nearly every month of the year. The gates would need to be opened for a sufficient time, on a regular basis, to accommodate fish migration. Some form of new surface or ground water diversion might be necessary to allow for make-up water to the canals during times when gravity diversions are not operating. Also as discussed in the Water Diversion section, above, water diversion occurs primarily between April and October. Whether a schedule of lowering the dam for fisheries could be found that would meet with approval by all stakeholders is unknown.
Figure 25 and Figure 26 provide conceptual details of the proposed gates. Appendix D provides more details of construction.
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Figure 25 Section though Radial Gates proposed at Daguerre Dam
Figure 26 Plan View of Gates at Daguerre Dam
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Cost Opinions
A summary of Opinions of Probable Costs for the individual task involved in the options presented in this report is compiled, below. Costs shown are for construction in 2013. Cost for a future construction date would need to consider inflation or deflation between 2013 and that date. These costs are considered consistent with AACE International Recommended Practice for Class 5 cost estimates as shown in Table 4. The approaches presented in this document are considered to be at a level of less than 10% of development. Cost estimates were compiled based on basic construction analysis without developing extensive details. Construction quantities were based on concepts developed and discussed above. They were, however, developed with as much detail as available and reliable data would allow. Dam demolition details, specifically, were developed in as much detail as possible at this stage. Demolition techniques used in recent dam demolition projects were reviewed and used here as a basis for the approaches presented. Means Heavy Construction Cost Data were used where reliable contractor information was not available.
Costs include an added contingency of 45% for unlisted, unknown, and undeveloped details and items. This contingency is similar to other cost assessments made in previous investigations for fish passage facilities at these dams.34 Estimates also apply a 30% increase over construction plus contingency costs for permitting, engineering, and construction management.
Table 5 provides a summary of costs for the individual elements of the various approaches described in previous sections of this report. Appendix G provides more details including unit prices and quantities used for developing costs.
Table 4 AACE Cost Estimate Classification
34 The MWH 2010 Report included a 20% markup for unlisted items, 25% for contingencies, and 30% for engineering, construction management, and permitting.
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Table 5 Summary of Costs
Remove Both Dams $ 123,310,000
Complete Removal of Englebright Dam $ 70,150,000 Complete Removal of Daguerre Point Dam $ 8,610,000 Upstream Diversion at Daguerre Point Dam $ 44,550,000
Partial Removal to Elevation 460 $ 60,300,000
Remove Englebright Dam to Elevation 460 $ 23,360,000 Fish Passage at Englebright to Elevation 460 $ 36,940,000
Partial Removal to Elevation 430 $ 64,410,000
Remove Englebright Dam to Elevation 430 $ 31,560,000 Fish Passage at Englebright to Elevation 430 $ 32,850,000
Rock Ramp at Daguerre Point Dam $ 18,030,000
Downstream Weirs at Daguerre Point Dam $ 64,090,000
Full Height Gates at Daguerre Point Dam $ 20,660,000
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Schedules
Schedules and time requirements are discussed in the discussion of the various approaches. An assumption was made that all approaches started in the year 2015. The schedules for each approach are shown in the following figures. Figure 27 provides an overview of the complete dam removal approach for both dams removed concurrently. It also includes the time line for construction of upstream water diversion and fish bypass facilities which are part of the proposed approach for complete Daguerre Point Dam Removal. Complete removal of both dams would require approximately 4 ½ years to complete. Other approaches would require approximately 1 year to complete, as illustrated by Figure 27 through Figure 32.
Development of construction schedules shown in the following figures has assumed that construction activities begin in the year 2015. These schedules have been developed to conceptually illustrate the anticipated timing of the various construction process elements.
The schedules for complete removal of both dams assume that Englebright Dam is removed three years before Daguerre Point Dam. For this approach upstream water diversion facilities would be constructed just prior to Daguerre Point Dam removal but nearly three years after removal of Englebright Dam to allow river conditions at the proposed new diversion facility to stabilize. Temporary water diversion facilities, such as well points or conventional wells, are not detailed in the following schedules. However, these schedules assume that temporary water diversion facilities such as wells or well points would be installed independently before removal of Englebright Dam.
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Figure 27 Overview of Complete Removal of Both Dams
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Figure 28 Overview of Partial Removal to Elevation 460 with Fish Ladder Construction Schedule
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Figure 29 Overview of Partial Removal to Elevation 430 with Fish Ladder Construction Schedule
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Figure 30 Overview of Ramp Construction Schedule
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Figure 31 Overview of Downstream Weirs Construction Schedule
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Figure 32 Overview of Full Height Gates Construction Schedule
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Conclusions
In February 2010, Montgomery Watson Harza produced a report for the National Marine Fisheries Service entitled: Yuba River Fish Passage: Conceptual Engineering Project Options. The report investigated conceptual approaches for providing improved fish passage at Daguerre Point Dam and new passage approaches at Englebright Dam.
This report expands on the MWH 2010 report. It develops additional fish passage approaches for Daguerre Point and Englebright dam - including, but not limited to, removal of both dams to allow fish to navigate a free flowing river. This report also develops conceptual alternative approaches for maintaining irrigation water diversion capacity in the event that Daguerre Point Dam is removed. A companion report: Modeling Sediment Transport Dynamics and Evaluating Flooding Risks in the Yuba and Feather Rivers, California, Following Modifications to Englebright and Daguerre Point Dams, was prepared by Stillwater Sciences in coordination with this report. It analyzes sediment behavior and potential flooding impacts associated with the various dam removal and dam alteration approaches presented here. The Stillwater Study concludes that sediment erosion is feasible without creating significant flooding hazards if adequate mitigation steps are taken. That report did not investigate water chemistry resulting from dam removal.
The general conclusions of this study are that several approaches are feasible at both dams that would provide improved fish passage at a cost between $18 million and $123 million. Full dam removal and partial dam removal with fish passage facilities is investigated at Englebright Dam. Both approaches were found to be feasible. The report also finds that it is feasible to remove Daguerre Point Dam to achieve better fish passage at the dam site. It finds that (with the existing dam left in place) it is possible to provide new fish passage facilities to accomplish better fish passage. For the approach that completely removes Daguerre Point Dam, it finds that an alternative means to supply water diversion for irrigation is possible.
The specific findings of this report conclude:
Removing Englebright and Daguerre Point dams is feasible. Sediment released by removing the dams would be eroded downstream shortly after demolishing the dams. A report conducted by Stillwater Sciences in 2013 in conjunction with this report investigates the impacts of sediment erosion downstream on flooding and turbidity. That report investigated several time frames for removing the dam to control the duration and rate of sediment release resulting from dam removal. Stillwater Sciences (2013) concludes that releasing the sediment over the shortest duration possible, using natural and mechanical methods to move the sediment out of the reservoir, has the least long term impacts on flooding and turbidity.
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This report finds that Englebright Dam can feasibly be removed by constructing tunnels at the base of the dam - to allow the river to flow through, which quickly releases the sediment. Once the reservoir is drained the structure can be removed within one year. Daguerre Point Dam can be removed concurrently within one year. The material taken from these two dams would be removed from the site and recycled. Cost for removing both dams would be approximately $79 million.
The report concludes that there are other methods that can feasibly supply gravity fed water for irrigation districts that now rely on Daguerre Point Dam to raise water levels to supply water. In conjunction with removal of the dams, construction of a new, much smaller, diversion dam (at higher elevation, 2 to 3 miles upstream of the present Daguerre Point Dam) would provide for gravity fed water for irrigation districts and a natural in-river fishway bypass around the diversion. The fishway and diversion facilities would be constructed in the year prior to initiation of dam removal activities. A temporary, supplementary pumped water supply system would be provided to ensure that water supplies would be available during and shortly after dam removal, even if high sediment flow created the need for maintenance and cleaning of the diversion facilities. The cost for new diversion and conveyance facilities, bypass fishway, a dredge for maintenance, and temporary pumped water supply during high sediment flow periods would be approximately $35 million.
Several alternate approaches to providing fish passage at Englebright Dam were investigated that involve removing only the upper portion of the dam to allow for better fish passage using a ladder constructed over the dam. The MWH 2010 report investigated construction of a 260 foot high ladder over the existing dam. This report investigates removing the dam to heights of 170 feet, 140 feet, and 100 feet.
o At 170 tall, the dam would create a water surface slightly above the top of the current power tunnels. Power production would be curtailed during the dam demolition activities. Operational procedures would need to be changed to reflect the changed water height but would continue after demolition. Upstream and downstream fish passage facilities would be constructed concurrently with the partial dam removal. All activities would take approximately 1 ½ years to complete. Partial dam removal would cost approximately $23 million and fish passage facilities would cost approximately $37 million.
o At 140 tall, the dam would retain most of the sediment behind the dam in a reworked configuration so that it essentially filled up the reservoir. Partial dam removal would create a water surface slightly below the bottom of the current power tunnels. Therefore, the power tunnels would be modified to allow continued power production by lowering and extending the intake tunnels. Power production would be curtailed during the dam demolition activities. Operational procedures would need to be changed to reflect the changed water height but would continue after demolition.
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Upstream and downstream fish passage facilities would be constructed concurrently with the partial dam removal. All activities would take approximately 1 ½ years to complete. Partial dam removal would cost approximately $32 million and fish passage facilities would cost approximately $33 million.
o At 100 feet tall the dam would be short enough to allow construction of a ladder that falls within the conventional concept of the upper height limitation for fish ladders. However, removing the dam to this height would also allow millions of cubic yards of sediment to erode. The impacts from this approach would be similar to the impacts of completely removing the dam. For this reason the approach was not investigated any further since full dam removal would be a better method to accomplish the fish passage objective.
At Daguerre Pont Dam three alternatives to full dam removal were investigated to provide better fish passage at the dam.
o Construction of a rock lined ramp along either the left or right bank of the river was investigated as a means to provide passage over the dam without removing it, or its water diversion capabilities. The slope of the ramp would be approximately 1% and the flow area width would be approximately 50 feet. It would be approximately 2,500 feet long and provide upstream and downstream passage for anadromous fish including salmonids and sturgeon. An upstream control gate would limit flow in the ramp to ensure that high flows did not limit passage and destroy the structure. The structure would take less than one year and would cost approximately $18 million to construct.
o An alternative approach that would also provide fish passage at Daguerre Point Dam without changing the current fish passage facilities and capabilities at the dam would construct weirs across the width of the river downstream of the dam - essentially burying the dam. The weirs would be constructed of concrete and steel sheet piles at approximately 100 foot intervals. Each successive weir would be constructed at an elevation one foot lower than the adjacent upstream weir until the last weir was only one foot above the streambed. The area between the weirs would be filled with locally available sand, gravel, or crushed concrete to create a river environment between weirs. Construction would take slightly more than one year and cost approximately $64 million to build.
o The final alternative approach to fish passage investigated at Daguerre Point Dam would construct new full-depth radial gates in the dam. These gates would be opened periodically to allow fish passage and lowered to provide water diversion. Details of operation would require further study to determine the feasibility of providing both adequate fish passage and water diversion using this approach. Construction would take less than one year to complete and cost approximately $21 million to construct.
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Childs, J.R., Snyder, N.P., and Hampton, M.A., 2003, Bathymetric and geophysical surveys of Englebright Lake, Yuba-Nevada Counties, California, U.S. Geological Survey Open-File Report 03-383 http://geopubs.wr.usgs.gov/open-file/of03-383.
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Stillwater Sciences, Modeling Sediment Transport Dynamics and Evaluating Flooding Risks in the Yuba and Feather River, California, Following Modifications to Englebright and Daguerre Point Dam, Yuba River Sediment Transport Study, for NMFS, 2013.
Stillwater Sciences, 2013. Modeling Sediment Transport Dynamics And Evaluating Flooding Risks In The Yuba And Feather Rivers, California, Following Modifications To Englebright and Daguerre Point Dams, Technical Report, prepared for National Marine Fisheries Service, Southwest Region, Habitat Conservation Division. Snyder, N.P., Allen, J.R., Dare, C., Hampton, M.A., Schneider, G., Wooley, R.J., Alpers, C.N., and Marvin- DiPasquale, M.C. 2004a. Sediment grain-size and loss-on-ignition analyses from 2002 Englebright Lake coring and sampling campaigns. USGS Open-File Report 2004-1080, 46 pages.
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report
Yuba County, Baldwin Hallwood Mine Expansion Project. Draft EIR, ESA/203431, October 2005
Yuba County Water Agency. 2007. Draft Environmental Impact Report/Environmental Impact Statement for the Proposed Lower Yuba River Accord. Prepared for the Department of Water Resources, Bureau of Reclamation and Yuba County Water Agency by HDR|SWRI. June 2007.
Yuba County Water Agency, Yuba River Development Project, Effects on Fish Facilities, FERC-Modified Study 7.12, May 2012.
Yuba County Water Agency, Yuba River Development Project, FERC Project No. 2246, Pre-Application Document, Public Information, November 2010.
Yuba County Community Development Department, Baldwin Hallwood Mine Expansion Project, Final Environmental Impact Report, State Clearinghouse No. 2004062016.
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National Marine Fisheries Service Final Report April 2014 Yuba River Fish Passage Improvement Investigation Report
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Gathard Engineering Consulting
APPENDIX A
Full Dam Removal
Yuba River Fish Passage Improvement Investigation
National Marine Fisheries Service
National Marine Fisheries Service Final Report April 2014 Appendix A Full Dam Removal
Appendix A
Dam Demolition Approaches for Removing Englebright Dam and Daguerre Point Dam
Table of Contents
Complete Dam Removal ...... 1 Removal of Englebright Dam ...... 1 Design Criteria and Assumptions ...... 2 Staging , Mobilization, and Access Roads ...... 6 Demolition ...... 11 Construction Equipment and Rates ...... 14 Removal of Daguerre Point Dam ...... 16 Design Criteria and Assumptions...... 16 Staging, Mobilization, and Access Roads ...... 17 Dam Demolition ...... 18 Construction Equipment and Rates ...... 21
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Table of Figures
Figure 1 Enlarged Portion of Drawing from Appendix C - Concrete Volume Calculations ...... 5 Figure 2 Water Depth versus Tunnel Flow through Englebright Dam ...... 5 Figure 3 Average and Maximum Daily Flows at Englebright Dam ...... 6 Figure 4 Loading and Stock Pile Areas ...... 8 Figure 5 Haul Roads for Concrete Removal ...... 9 Figure 6 Haul Road Contours ...... 9 Figure 7 Proposed Dam Removal Sequence ...... 10 Figure 8 Englebright Water Surface and Flow Rate through Tunnel ...... 12 Figure 9 Daguerre Point Dam Demolition Stages ...... 20
List of Tables
Table 1 Equipment Estimates for Demolition of Englebright Dam ...... 14 Table 2 Equipment Estimates for Transport from Englebright Dam to Salvage Site ...... 14 Table 3 List of Quarries in Vicinity of Daguerre Point Dam ...... 20 Table 4 Equipment Estimates for Demolition of Daguerre Point Dam ...... 21 Table 5 Equipment Estimates for Transport from Daguerre Point Dam to Salvage Site ...... 21
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Complete Dam Removal
Complete removal of both dams would allow large quantities of the reservoir sediment behind Englebright Dam and much smaller quantities behind Daguerre Point Dam to erode downstream. Complete removal would allow volitional fish passage at both dams for all species. No further mitigation for fish passage would be necessary at Englebright Dam. In the proposed approach Englebright Dam would be removed before Daguerre Point Dam to allow sediment to move past Daguerre Point Dam before water diversion upgrades are constructed.
Daguerre Point Dam is used as a sediment retention dam and to raise water levels as necessary to divert up to 1600 cfs water to water districts on the north and south sides of the river. To maintain water diversions located just upstream of the Daguerre Point location, a new low level diversion dam would be constructed between two and three miles upstream of the dam to divert water for irrigators. To avoid the anticipated significant changes in bed elevation1 upstream of Daguerre Point Dam immediately after the removal of Englebright Dam, Daguerre Point Dam would remain in place to provide water diversion for at least three years. New upstream water diversion facilities would be put in place starting the spring of the third year following the breach of Englebright Dam. After completing the new water diversion facility, Daguerre Point Dam would be breached in the fall of that year and removed, as flows allowed, over the following winter and spring months.
Analysis of sediment erosion and transport resulting from removal of Englebright and Daguerre Point dams was investigated by Stillwater Sciences and is presented more fully in a 2013 supplemental report entitled: Modeling Sediment Transport Dynamics and Evaluating Flooding Risks in the Yuba and Feather Rivers, California, Following Modifications to Englebright and Daguerre Point Dam, Yuba River Sediment Transport Study (Stillwater Study). A discussion of the removal approaches for both dams, a schedule for the work, and a manpower and equipment schedule are provided, following.
Removal of Englebright Dam
The following discusses one approach to lower the reservoir and demolish Englebright Dam. Many of the considerations involved in attempting to determine the optimum approaches are discussed in the main body of this report. While other approaches may be feasible, the approach outlined herein was developed to illustrate the construction feasibility, construction time requirements, impacts, and cost of dam removal. This approach is also based on discussions with contractors who have used these construction techniques for recent dam removal projects on the Elwha and White Salmon Rivers in Washington State.
1 Modeling Sediment Transport Dynamics and Evaluating Flooding Risks in the Yuba and Feather Rivers, California, Following Modifications to Englebright and Daguerre Point Dam, Yuba River Sediment Transport Study, Stillwater Sciences, 2013
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Design Criteria and Assumptions
Analysis of feasibility, cost, and schedule for complete removal of Englebright Dam is based on consideration of the following issues.
1. Sediment behind the dam would not be moved out of the reservoir area prior to removing the dam. All sediment removal would be accomplished by allowing the river to erode material downstream. Based on experience on the Elwha and White Salmon Rivers where recent dam removal projects have been conducted with sediment erosion as the means to remove sediment from the reservoir, the need to rework or move sediment into the reservoir is unclear. On the White Salmon, removal of Condit Dam left some material in unstable conditions along the river several months after the breach. Although not required to do so by permitting documents, the owners voluntarily moved the sediment into the river to reduce safety concerns from the presence of very steep slopes along the river bank in the reservoir area. Flattening slopes also reduced the amount of future erosion and the requirements for future monitoring. To account for this contingency approximately 10% of the sediment was assumed to be reworked for this analysis, consistent with conditions experienced on the Condit Dam removal project. 2. Impacts to fish and water users downstream of the dam from reservoir sediment should be minimized to the greatest extent possible. The Stillwater Study investigated various approaches to dam removal and sediment impacts downstream of Englebright Dam. The study concluded removing the dam in increments over a 10 year period had no significant impact on downstream flooding risks but extended the duration of extremely high turbidity. It concluded that rapid sediment erosion had fewer impacts than removing the dam over a period of 10 years. The criteria used for this analysis assumed that sediment would be eroded as quickly as possible. 3. Several approaches to rapidly lowering the reservoir to demolish dam concrete were considered. These include: a. rapidly creating a vertical notch in the dam from top to bottom, and b. constructing a low level outlet at the base of the dam. Constructing a vertical notch would allow the reservoir to drop to a lower elevation with each new increment of notch construction. Upstream sediment would erode downstream as the reservoir elevation dropped. Eventually the sediment would come to rest against the upstream face of the dam. The vertical notch approach would not release bedload sediment downstream until the notch dropped below the sediment elevation on the upstream face of the dam. The upper elevation notch construction would allow only suspended sediment to leave the reservoir. Most of the reservoir sediment would erode past the dam as the notch construction approached the base of the dam. Erosion of sediment over the notches would create very high total suspended sediment (TSS levels) downstream of the dam. However, high TSS levels downstream of the dam would be present for the entire period of time required for notch
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construction, approximately for a period of one year; since erosion of sediment upstream of the dam would also create high TSS levels. The vertical notch approach requires that construction of the notch in the lower portion of the dam be conducted with sediment against the upstream face of the dam. This condition would make construction more costly and difficult and could extend the construction time. Using the notch approach would reduce the rate of dewatering the sediment and possibly limit ability to access the sediment for re-grading steep slopes. The low level outlet approach erodes more sediment during the initial tunnel breach period, reduces the duration of high TSS, allows quicker access to the upstream sediment for re-grading, and allows demolition of the dam concrete to occur without restrictions from sediment on the upstream face of the dam. Based on analysis of sediment effects downstream, feasibility of demolition, cost, duration of high TSS in the river, and issues associated with stabilizing sediment in the post breach reservoir, constructing a low-level outlet was chosen as the best approach. A tunnel size of 12 feet wide by 15 feet high was chosen (the Stillwater Study proposed a minimum size of 10 feet by 10 feet opening, the same size as the original bypass tunnel used to construct the dam. A larger tunnel size opening does not impact the sediment analysis results. Appendix C discusses the drawings used for concrete volume calculations. These drawings show a tunnel on the downstream face of the dam labeled “Diversion Plug.” This drawing has been enlarged in Figure 1 to show the plug designation and dimensions. The total tunnel opening should be large enough to pass average daily flows after the breach without frequent construction stoppages due to rising water levels. Floods flows that exceed the tunnel capacity will cause water levels to rise above the top of the tunnel. When this occurs, tunnel flow capacity will vary with water depth at the upstream face of the tunnel as illustrated in Figure 2. To increase the tunnel opening during dam removal activities and help reduce the frequency of work stoppage associated with high water elevations in the reservoir, two 12 by 15 foot tunnels would be constructed. Constructing two 12 feet by 15 feet tunnels would provide sufficient flow capacity to pass all flows without causing the reservoir elevation to rise. The Stillwater Study analyzed the effects of reservoir changes using a 10 feet x 10 feet tunnel opening and found that, in years of average and higher flows, the reservoir completely refilled in the year following the breach. A full analysis of optimum tunnel size to reduce reservoir water levels will require additional study and is beyond the scope of this investigation. As can be seen in Figure 3, maximum daily flows can greatly exceed the capacity of the two tunnels even for a full reservoir depth. Table 3 of the Stillwater Study provides exceedance probabilities for maximum daily flows for 15 years. Peak daily flows for an average year based on this table would be around 26,000 cfs. As shown in Figure 2, water depth would need to be about 210 feet deep to pass that flow.
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During the initial tunnel construction, two 12 feet by 15 feet tunnels would be constructed near the base of the dam to within approximately 15 feet of the upstream face of the dam. One tunnel would first be breached to initiate the reservoir drawdown. Flow through that tunnel would initially be around 10,000 cfs which is less than the 2-year flood event.2 The 2nd tunnel would be breached several days later. The 2nd breach would create a larger opening at the base of the dam to allow higher flows to be passed through the dam during demolition activities. A larger opening at the base of the dam would reduce the chance that the reservoir water elevation would rise to the level of construction activities during the winter high flow months. Further study would be necessary to define the optimum tunnel size considering the risk of reservoir rising to the level of construction activities versus tunnel construction cost. Further criteria development would also be needed to include consideration of downstream impacts associated with the initial high flow event created by the breach and the timing of that flow. 4. All concrete above the pre-dam surface will be demolished and removed from the site. Concrete demolition will occur using blasting and mechanical equipment, as required to meet scheduling needs. Concrete along the river thalweg would be removed to 5 feet below the pre-dam river bed elevation to allow for future variation in bed elevation without causing a fish passage barrier at the dam location. Concrete would be removed from the dam by backhoes and loaders into 20 yard off road trucks for transport to nearby sites for separating reinforcing steel and further crushing. At the stock pile sites, concrete will be crushed, loaded into over the road trucks for transport to salvage sites, and sold for reuse. Reinforcing steel will be removed from the concrete, stored temporarily, and sold to recyclers. No value for the salvage was included in the cost estimate. 5. All demolition will occur in one year to ensure that work conducted near the bottom of the dam is conducted in the summer months following the breach - so that river flows are at a minimum and will not overtop the demolition elevation. However, because the reservoir will be drawn down in a matter of days, no detrimental effects would occur if demolition took more than one year. 6. Power generating equipment and structures will be demolished and removed from the site. No salvage value has been assigned to the generating equipment, but salvage value should be considered in any future development of studies and plans for dam removal. 7. Power tunnels will be used to draw the reservoir down as much as possible (approximately elevation 460 msl) during the summer prior to breaching the dam. After dam demolition the tunnels will be filled with concrete at both ends.
2 Stillwater Report Table 3
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Figure 1 Enlarged Portion of Drawing from Appendix C - Concrete Volume Calculations
Water Depth behind Englebright Dam versus Flow through Tunnels
250
Two Tunnels 12 by 15 feet 200
feet 150 -
100 Water Depth Depth Water
50
0 0 5,000 10,000 15,000 20,000 25,000 30,000 Tunnel Flow - cfs
Figure 2 Water Depth versus Tunnel Flow through Englebright Dam
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Flow below Englebright Dam Data for site 11418000 7,000 140,000
Average Daily Flow Maximum Daily Flow
6,000 120,000
5,000 100,000
cfs
cfs
- -
4,000 80,000
3,000 60,000 Average Daily Flow Daily Average 2,000 40,000 Flow Daily Maximum
1,000 20,000
- 0 10/1 10/31 11/30 12/31 1/30 3/2 4/1 5/1 6/1 7/1 8/1 8/31 9/30 Day of the Year
Figure 3 Average and Maximum Daily Flows at Englebright Dam
Staging, Mobilization, and Access Roads
The dam removal project would begin with mobilization of equipment to the site. One initial staging area and three stock piling and loading areas are proposed. The initial staging area would be above the Narrows II powerhouse for equipment to be used for the initial breach and cofferdam construction. Stock pile and loading areas would be cleared and leveled to the extent possible. On the west side of the river very little level area is available for sorting and loading due to the steep terrain. Two small sites were identified as possible stock pile areas on the west side of the river and one on the east side of the river. See Figure 4 for proposed locations.
The access road to the dam area on the west side of the river (unnamed) would be widened and paved to allow off road trucks to haul concrete out of the dam area. A new access road from the power house on the right bank to the base of the dam would be constructed to allow construction of the tunnel and downstream cofferdam placed to allow tunnel construction. Two additional new haul roads would be constructed to gain access from the upgraded access road to the dam structure. Englebright Dam Road would be repaved out to Money Flat Road and extended - from the parking lot just upstream of the dam to the top of the dam - to allow material removal from both sides of the dam.
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Haul roads from the existing power house access road to the dam would be cut into the rock hillsides at a relatively mild grade using the same technologies to be used for dam removal. The haul road to the bottom of the dam would be used for the initial access and for the final phase of demolition of the dam. Figure 5 and Figure 6, below, show the orientation and contours of the roads. Figure 7 shows the phases of construction associated with road construction.
Numerous possible methods of removing the concrete from the dam area are feasible. The concrete removal approach shown in Figure 7 is based on conversations with contractors that were involved in the removal of the Elwha Dam on the Elwha River and Condit Dam on the White Salmon River. A reasonable alternative approach would use a tower crane to load material continuously from the excavation location to a single haul road loading site. However, limits to the reach of a single crane would require either moving the crane or employing several cranes. Using haul roads along the top of the dam, as illustrated herein, was chosen as the most direct approach.
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Figure 4 Loading and Stock Pile Areas
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Figure 5 Haul Roads for Concrete Removal
Figure 6 Haul Road Contours
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Figure 7 Proposed Dam Removal Sequence
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Demolition
Dam demolition would begin with the construction of a temporary cofferdam across the width of the river approximately 100 feet downstream of the dam to allow construction of a drainage tunnel at the base of the dam. The pool at the base of the dam would be drained prior to tunnel construction and kept dry by a downstream cofferdam and pumps to remove any leakage. Two tunnels approximately 12 feet wide by 15 feet tall would be excavated, either in the location of the original diversion tunnel or near that location. The diversion tunnel used to construct the dam, of approximately the same dimensions, is shown in Figure 7.
Starting in June when flows drop sufficiently to ensure that water spill will no longer occur, tunnels would be advanced by drilling and blasting. Concrete would be removed from the tunnels after each blasting to advance the tunnels to within approximately 15 feet of the upstream face of the dam. To breach the dam the final 15 foot section in one of the tunnels would be blasted sometime in the fall of the year. Analyses presented in Stillwater Science’s Yuba River Sediment Transport Study are based on breaching the dam on November 15.
The second 12 by 15 foot tunnel would not be immediately breached. The second tunnel would be breached approximately 48 hours after the first tunnel to avoid extremely high flows in the river that would occur by simultaneously breaching both tunnels. Further development of this approach may show that breaching both tunnels simultaneously does not create unacceptable downstream flooding. The second tunnel would provide an opening through the dam large enough to allow most flows to pass during winter months so that the reservoir does not frequently refill to the elevation of the demolition and stop the work.
Complete drawdown of the reservoir would take approximately 4 days to complete. Rapid drawdown of the reservoir would increase sediment instability and aid in erosion of the sediment. The reservoir would be lowered, starting in late June or the beginning of July, using the two power tunnels to lower it to approximately elevation 475. Lowering the reservoir would allow demolition of the dam to begin as soon as the flow level was low enough to ensure no water passed over the spillway. Figure 8 illustrates the flow rate through the tunnels and water surface elevation immediately after the breach.
Haul roads would be constructed from the dam to the existing access roads on each side of the dam. The top of the dam is approximately 20 feet wide, barely enough but sufficient to allow passage of equipment to haul the concrete from the dam. However, by constructing stock piles on each side of the dam trucks could be loaded and continue forward to stock piles without requiring the truck to turn around or reverse directions on the dam, which would be dangerous considering the narrowness of the dam at the top.
Demolition would begin near the middle of the dam and proceed outward. Twenty cubic yard capacity off-road trucks would be used to move the concrete to the stock piles for transfer. Demolition would occur by mechanical impact equipment, drilling, and drilling and blasting techniques. Discussions with contractors conducting demolition at Elwha, Glines, and Condit Dams indicate that due to the large
GEC Yuba River Fish Passage Improvement Investigation Page A-11 National Marine Fisheries Service Final Report April 2014 Appendix A Full Dam Removal quantity of material to be removed in Englebright Dam, blasting may be the predominant method of demolition. However, for this investigation, drilling and mechanically breaking the concrete was used for time and cost analysis.
Water Surface and Tunnel Flow Immediately after Breach 14,000 475
Flow Out of Reservoir 12,000 Water Surface Elevation 450
10,000 425
feet msl feet -
400
cfs 8,000 -
6,000 375 Flow Out Flow
4,000 350 Water Surface Elevation Surface Water
2,000 325
- 300 - 10 20 30 40 50 60 Hours after Breach
Figure 8 Englebright Water Surface and Flow Rate through Tunnel
Stock pile locations on both sides of the dam would be used for better access and to reduce the need for vehicles to pass each other or turn around on the dam in the narrower upper portions of the dam. Estimates for demolition time were based on assuming that one hammer could demolish approximately 240 cubic yards of predrilled concrete per 8 hour day.3 For development of the schedule it was assumed that drilling would occur across the dam in a period of time when all other demolition activities were stopped due to interference with truck traffic. In the event, these activities may occur simultaneously at lower elevations where the dam is wider and trucks could bypass drilling operations.
3 Discussions with Condit Dam removal personnel confirm this rate when access to the site did not restrict work.
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Removing the dam in one year would require 5 impact hammers operating simultaneously, two back- hoes with 3 yard buckets to act as loaders, and four 20 yard off road trucks to remove the material from the dam to the stock piles.
At the stock pile sites, one backhoe would separate reinforcing steel out of the concrete at each site, ten over the road 10 yard trucks, or five tandems, would haul broken concrete to the salvage site. For construction time analysis it was assumed that the round trip distance would be 20 miles. An average speed of 40 mph was used to estimate haul time and costs. A crusher was not included in the analysis. Although some additional break down of the concrete may be necessary, that cost is reflected by adding one additional backhoe in the cost at each stock pile site.
Daily demolition production rates were calculated at 1200 cubic yards per eight hour day. Work would occur only on week days. Production rates and costs were based on information presented in RS Means Heavy Construction Cost Data, 2007. Costs were increased by 11% based on the Bureau of Labor Statistics CPI inflation calculations from 2007 to 2012 to reflect 2012 prices. Additional inflation costs were added to reflect anticipated costs in the proposed year of the work based on a start year of 2015.
Concrete could be used as fill for projects at Daguerre Point Dam, sold to one of the local aggregate mining operations, or removed to a remote site for permanent stabilization. Conversations with local mining operators indicate that concrete, crushed and delivered to their sites, could be worth approximately $12 per cubic yard. Cost estimates made for this report conservatively assign no value to the material but do assume that all material will be permanently relocated to the mining sites at no cost to the project except transportation costs.
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Construction Equipment and Rates
Table 1 Equipment Estimates for Demolition of Englebright Dam
Daily Hours/day Number of Rate/backhoe # Haul Cy/day/truck trips/day/truck rate Hoes Cy/Hr Trucks Cy/day 1,200 8 5 30 4 270 15 Cy/Truck Tip Time Truck Speed Truck Trip one Truck Speed Load Time Unload time Minutes miles/minute way miles/hr minutes minutes miles 18.00 32.00 0.33 2 20 10 10
Table 2 Equipment Estimates for Transport from Englebright Dam to Salvage Site
Daily rate Hours/day Number of Rate/Load Load Rate Bucket Load # Haul Cy/day Loaders Cy/Hr CY/day Size Cycle Trucks CY Time min
1,200 8 5 150 1200 3 6 13 Cy/day/truck trips/day/truck Cy/Truck Tip Time Truck Speed Truck Trip Truck Load Minutes miles/minute one way Speed Unload miles miles/hr Time minutes 90 9 10 50 0.666667 10 40 10
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Construction Sequence The following sequence of activities was used to develop construction sequencing and cost estimates.
1. Mobilize equipment to site, clear staging area near Narrows 2 powerhouse, and upgrade access roads. 2. Remove equipment and demolish Narrows 2 powerhouse as necessary for additional space. 3. Construct haul roads starting with the road to the base of the dam. 4. Construct cofferdam across the river downstream of the base of the dam and dewater the pool at the base. 5. Drill, blast, excavate, and remove concrete in tunnels for breaching the dam. 6. Drill vertical holes for blasting and breaking concrete from the top of the dam for breaking and blasting. These holes would go all the way to the base of the dam. 7. Begin lowering the reservoir through the power tunnels as soon as possible. Lower to elevation 475 through power tunnels. Start demolition during the lowering process when the reservoir is lowered by 10 feet. 8. Demolition will proceed starting in the middle and working towards both banks. Concrete would be removed in horizontal lifts until the concrete in Phase I is removed. Phase I concrete, about 50,000 cubic yards, would be removed to stock piles on both sides of the dam. Phase I is defined by a 20% grade extending from both ends of the dam towards the center of the dam as shown in Figure 7. This slope is approximately the limit that construction equipment can traverse. Most of Phase I and part of Phase II can be removed before breaching the dam by removing concrete to the left bank (southeast side) stock pile. 9. After breaching the dam in November, concrete demolition would continue by removing material to the left bank stock pile. Work would continue through the winter unless New Bullards was not able to restrict flows to levels that could safely flow through the tunnels and guard against high flow that would overtop the structure. 10. Phase II would be completed in the winter in an average year without overtopping. Phase II, about 60,000 CY, would mostly be removed to the left bank stockpile location. 11. Phase III, about 80,000 CY of concrete, would require a new lower elevation road to the right bank stock pile. A new road, starting at approximately elevation 375, extending from the dam to the existing access road for Narrows 2 would be constructed to remove demolished concrete. 12. Final removal, about 50,000 CY would be conducted in the summer of the year following the breach using the access road to the base of the dam. Flow would be diverted through the left bank tunnel and a ramp constructed from the base of the dam to the access road to remove the final segment of concrete. Alternatively, a temporary bridge could be constructed across the river to allow access to lowest point of excavation from Phase III.
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Removal of Daguerre Point Dam
At 25 feet tall and 575 feet long and containing only about 29,000 cubic yards of concrete, Daguerre Point Dam is relatively small by comparison to Englebright Dam. The dam removal concept developed here assumes that demolition work must be conducted in dry conditions. This single assumption causes the removal plan to be more complex than assuming that work can be conducted in wet conditions with slowly flowing water. In the approach developed in the following discussion, demolition of the initial breach in the dam is conducted behind a steel cofferdam wall upstream of the dam and a temporary concrete cofferdam barrier downstream of the dam to allow all work to be conducted in dry conditions.
This approach requires greater effort and cost than an approach that allows the dam to be breached while protected behind gravel berms (which are easier and less costly to construct, but may allow some seepage into the construction area). Because limited information was available concerning river base permeability and strength of the material immediately behind the dam, the approach developed below is more conservative than assuming the contractor will be able to demolish the dam in wet conditions or use gravel cofferdams constructed from local material. This more conservative approach was developed to ensure the feasibility of the approach.
Future investigations may reveal a faster, less expensive, approach is also feasible. In a less costly and less complex approach, for example, a gravel berm would divert water away from the initial demolition area, a mechanical impact hammer would start demolition at one end by creating a notch in the top of the dam approximately 20 feet wide and several feet deep allowing the river to flow through a notch, and the berm would be breached to allow the river to flow through the notch. This would allow the remaining portion of the dam to be demolished in the dry. A temporary access ramp would be constructed of crushed aggregate along the back face of the dam for demolition access from the opposite side of the dam. This approach would be similar to the approach used to remove Edwards Dam in Augusta, ME. It would likely result in a less expensive and faster project than details presented in the following discussion but construction in the dry is considered more conservative and more appropriate for a feasibility level analysis such as this.
While other approaches are possible, the approach outlined here was developed to illustrate the construction feasibility, construction time requirements, impacts, and cost of dam removal. This approach is also based on discussions with contractors who have used these construction techniques for recent dam removal projects on the Elwha and White Salmon Rivers in Washington State.
Design Criteria and Assumptions.
1. Sediment behind the dam would not be moved out of the reservoir area prior to removing the dam. All sediment removal would be accomplished by allowing the river to erode material downstream. No specific analysis of costs and time required to reshape or stabilize sediment remaining in the upstream reservoir was included.
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2. Impacts to fish and water users downstream of the dam from sediment erosion would be minimized to the greatest extent possible. The Stillwater Sciences investigation concluded that sediment erosion from removal of Daguerre Point Dam had little impact downstream of the dam either on flooding or on water users. 3. Water diversions at the dam and upstream of the dam would be protected from loss of capacity during dam demolition and after removal. 4. The rate of lowering the reservoir is not limited by concern for slope failures upstream of the dam. Since the small reservoir upstream of the dam is full of sediment, the sediment erosion rate will limit the rate of water surface decline after the initial breach of the dam. 5. Drawings of the dam were not available for this investigation. However, based on the known length and height of the dam and estimated width, a quantity of concrete that would be removed to an elevation approximately 5 feet below the downstream riverbed was estimated to be approximately 29,000 cubic yards. The assumed dimension were as follows: a. The length of the dam is 575 feet. b. The width of the base of the dam is 70 feet based on measurements from aerial photographs presented on Google Earth. Measurement of the length of the dam on Google earth provided a length of 576 feet corresponding well with the length provided in several documents. c. The height of dam removal was estimated to be 30 feet based the assumption that the crest of the dam was 25 feet above the downstream elevation. 6. Fish ladder concrete would be completely removed. Concrete demolition will occur using blasting and mechanical equipment, as required to meet scheduling needs. 7. Most of the concrete would be removed from the dam by backhoes and loaders into 20 yard off road trucks for transport to nearby sites for separating reinforcing steel and further crushing. At the stock pile sites, concrete will be crushed, loaded into over the road trucks for transport to salvage sites, and sold for reuse. Reinforcing steel will be removed from the concrete, stored temporarily, and sold to recyclers. No value for the salvage was included in the cost estimate. 8. All demolition activities would occur in dry conditions. Construction time would be less than one year.
Staging, Mobilization, and Access Roads
Activities to provide a stable water supply would begin a year prior to demolition activities. Water diversion facilities upstream of the dam, as discussed in the main body of this report, would be constructed prior to dam demolition activities.
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Dam Demolition
Dam removal activities would begin with mobilization of equipment on the right and left banks of the river just upstream of the dam. The dam would be removed in three stages. The first stage, Stage I as illustrated in Figure 9, would allow the reservoir to drain and divert flow away from demolition activities in the northern portion of the dam. Stage II would involve construction of access to the dam from the north shore and allow removal of the largest volume of concrete. The third stage, Stage III, not illustrated in Figure 9, would remove the last small remaining portion of the dam between Stage I and Stage II removals.
Stage I A small staging area would be required on the left bank to initiate demolition by removing the southernmost section of the dam. A stock pile area for storing material on the south side of the dam would be cleared and graded. Approximately 1 ¾ miles of unpaved roads from the dam to New Truck Road would be upgraded. Approximately 225 truck trips would be required to remove about 4500 cubic yards of concrete from Stage I demolition, the initial breach of the dam. Access to the southern portion of the dam would be gained by constructing a temporary ramp in the fish ladder area and placing a crane to construct a cellular sheet pile wall upstream of the dam. Limitations on the length of a crane’s reach would require that several sheet piles cells be created to block river flow over the dam. The first cells would be used as a staging area for the crane to set the next cell. A pad for the crane would be created in the cell by placing gravel in the cell, then moving the crane into the cell to provide access further into the reservoir, and using the new position to build the next cell. In Stage I, a section approximately 100 feet wide downstream of the sheet wall would be completely demolished to allow diversion of the river while the remaining portion of the dam is removed from the north side of the river. Immediately downstream of the dam in the area of the sheet pile wall a cofferdam would be constructed to allow removal of the southern diversion section in the dry. Concrete would be demolished using mechanical equipment, transported to temporary stockpiles by off road trucks for material separation, and then placed into over the road trucks for transport to a local aggregate recycling site. Discussions with local aggregate mine owners indicates that a site within 10 miles of the dam would accept the material. Table 3 provides a partial list of local quarries which might be acceptable repositories for demolished concrete. These are provided for reference only and to show the feasibility of finding local repository sites. Determination of a particular site or final use the concrete is beyond the scope of this investigation. After constructing an opening in the south side of the dam, the portion of the downstream cofferdam running parallel to the dam would be removed and the sheet pile wall would be incrementally removed to allow river diversion through the opening. The portion of the downstream cofferdam perpendicular to the dam would remain, and be extended to the north shore after sheet pile cell removal, to assist with removal of the remaining damn.
GEC Yuba River Fish Passage Improvement Investigation Page A-18 National Marine Fisheries Service Final Report April 2014 Appendix A Full Dam Removal
Constructing the sheet pile wall in cells (as shown in Figure 9) would allow each cell to stand independently; so that the crane can be set in the middle cell to remove the northern cell, and then moved to the southern cell to remove the middle cell. The southern cell could be removed from the initial crane location.
Stage II Stage II would involve building access to the northern portion of the dam, blocking flow from the northern section, constructing a downstream cofferdam to protect demolition activities, and demolition of the northern portion of the dam. After the southern section of the dam was removed in Stage I, a ramp constructed from crushed dam concrete would be built into the dewatered northern side of the reservoir to allow access for further concrete demolition. A sheet pile cutoff wall and extension of the downstream cofferdam would allow activities to be conducted in the dry. After demolition, concrete would be loaded into off road trucks and removed to a stock pile area just north of the dam for crushing, loading, and transportation to a recycling site. River flow would be diverted to the opening in the southern part of the dam by the Stage II sheet pile wall. The access ramp would also act as a diversion berm for any flow entering the northern branch of the river. Upstream erosion of the sediment in the southern branch will quickly lower the river elevation at the entrance to the northern branch and eliminate flow into it. Approximately 24,000 cubic yards of concrete between the bank and the north abutment (including the fish ladder) would be removed in Stage II activities. A small section at the southern end adjacent to the sheet pile wall and cofferdam ends would not be accessible because of river flow on the outside of the wall.
Stage III After removal of most of the northern portion of the dam - except that area immediately adjacent to the Stage I opening - the Stage II sheet piles and downstream cofferdam would be removed. A temporary gravel/crushed concrete ramp would be constructed into the river as a means to pull sheet piles and cofferdam elements and later removed as the wall sections are removed. River water levels would be only a few feet deep at this time. A low level cofferdam would be constructed from the south shore to divert river flow into the newly opened northern section and allow final removal off the section of the dam adjacent to the Stage I opening.
GEC Yuba River Fish Passage Improvement Investigation Page A-19 National Marine Fisheries Service Final Report April 2014 Appendix A Full Dam Removal
Table 3 List of Quarries in Vicinity of Daguerre Point Dam
Ore Number 1 Plant Parks Bar Quarry Pearson Quarry R-5 Gold Field Pit and Mill River Rock Sand and Gravel Simpson Lane Pit Speckert Pit Sperbeck Quarry Wheatland Pit
Willow Creek Pit Yuba Consolidated Gold Fields
Yuba River Pit Yuba Silica
Figure 9 Daguerre Point Dam Demolition Stages
GEC Yuba River Fish Passage Improvement Investigation Page A-20 National Marine Fisheries Service Final Report April 2014 Appendix A Full Dam Removal
Construction Equipment and Rates
Removal of Daguerre Point Dam will require demolition of an estimated 28,000 cubic yards of dam material. Analyses of the time required for concrete demolition, hauling broken concrete to stock pile sites, and transporting the material to salvage sites were based on information included in Table 4 and Table 5. In Table 4, the first group of heavily bordered cells shows the maximum rate at which 2 backhoes could demolish the dam concrete. The cells immediately to the right of these show the amount of concrete that 2 off road trucks could haul to a stock pile site, based on the information in the cells in the bottom two rows of the table. Table 5 shows that 1 loader can load 480 cubic yards per day which is greater than 393 cubic yards per day, the rate at which the material is delivered. These activities do not need to be concurrent since material must be separated.
Four over the road trucks would be loaded continuously and each make 12 trips per day to the disposal site, based on the assumptions listed in the lower two rows of Table 5. These assumptions were used to develop quantities and times used for schedules and costs for dam removal.
Table 4 Equipment Estimates for Demolition of Daguerre Point Dam
Max Demo Rate Hours/day Number of Rate/backhoe # Haul Cy/day/truck trips/day Cy/day Hoes Cy/Hr Trucks /truck 480 8 2 30 2 270 15 Cy/Truck Trip Time Truck Speed Truck Trip one Truck Load Time Unload Minutes miles/min way Speed minutes time miles miles/hr minutes 18.00 22.00 0.33 2 20 10 10
Table 5 Equipment Estimates for Transport from Daguerre Point Dam to Salvage Site
Material Hours/ Number Rate/Load Max Load Bucket Load Cycle # Haul Delivery day of Cy/Hr Rate Size Time Trucks Rate Loaders CY/day CY min Cy/day 270 8 1 60 480 2 2 3 Cy/day/truck trips/ Cy/Truck Tip Time Truck Speed Truck Trip Truck Load/ day/ Minutes miles/minute one way Speed unload truck miles miles/hr Time minutes 96 9 10 50 0.666667 10 40 10
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Gathard Engineering Consulting
APPENDIX B
Partial Removal of Englebright Dam
Yuba River Fish Passage Improvement Investigation
National Marine Fisheries Service National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam Appendix B
Partial Removal of Englebright Dam
Table of Contents
Partial Englebright Dam Removal 1 Remove Dam to Limits of Current Generating Equipment - Elevation 460 ...... 7 Dam Demolition Sequence ...... 13 Removal to Sediment Full Reservoir - Elevation 430 ...... 14
Table of Figures
Figure 1 Average Daily Flow and Maximum Flow - Yuba River ...... 6 Figure 2 Englebright Reservoir Elevation vs. Volume ...... 8 Figure 3 Narrows 2 Intake Tower ...... 9 Figure 4 Fish Ladder and Downstream Fish Collection at Elevation 460 ...... 10 Figure 5 Proposed Haul Roads for Partial Removal to Elevation 460 ...... 11 Figure 6 Proposed Haul Roads with Topo for Partial Removal to Elevation 460 ...... 11 Figure 7 Looking Upstream at Dam- Demolition Phases Removal to Elevation 460 ...... 12 Figure 8 Proposed Sediment Flushing Gates ...... 15 Figure 9 New Narrows 2 Power Tunnel ...... 16 Figure 10 Looking Upstream at Dam Elevation View of Removal to Elevation 430 ...... 16 Figure 11 Plan View of Dam Facilities at Elevation 430 ...... 17
List of Tables
Table 1 Equipment Estimates for Demolition of Englebright Dam ...... 4 Table 2 Equipment Estimates for Transport from Englebright Dam to Salvage Site ...... 5 Table 3 Concrete Removal Volume and Time to Elevation 460...... 5 Table 4 Concrete Removal Volume and Time to Elevation 430...... 5 Table 5 Power Generation Facility Details ...... 9
GEC Yuba River Fish Passage Improvement Investigation Page B-i National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Partial Englebright Dam Removal
Removal of two dams, Englebright and Daguerre Point Dam, on the Yuba River was investigated because the dams currently block passage of anadromous fish (completely or partially) that use the river as spawning and rearing grounds. Removing Englebright Dam, however, would eliminate power production at Narrows 1 and 2 power plants and release a large amount of sediment downstream. As an alternative to entirely removing the dams, removal of only the upper portion Englebright Dam was investigated, in conjunction with a proposed fish ladder. Fish ladders are a proven method for allowing upstream migrating fish to traverse instream obstacles such as locks and dams. However, the use of ladders above 200 feet tall has not been attempted in the United States.
At 260 feet tall, providing a fish ladder around Englebright Dam would be beyond the limits of current practice and experience. However, if the height of the dam were reduced, a fish ladder within the current use parameters could be constructed. Furthermore, the dam could be reduced in height and, with some modifications, still retain its current functions for sediment retention dam, hydropower production, and recreation. Partial removal was not investigated at Daguerre Point Dam since it is already a low head dam.
Several partial removal options of Englebright Dam were explored. These options would result in a lower level of power production at Englebright Dam but would still retain most of the sediment that is now trapped in the reservoir, and avoid effects from the large volume of sediment released in the full dam removal approach.
Partial removal presents several challenges not present for the complete dam removal approach. Without a low level outlet at the dam, the power tunnels would have to be used to lower the reservoir. However, power tunnel flow capacity is limited and is smaller than average inflows in the winter and spring months. If power tunnels are used as the means of lowering the reservoir, demolition of the dam will need to occur between the months of June and December so that the reservoir water level does not overtop the dam. In order to meet that schedule restriction, demolition schedules were developed to remove the upper portion of the dam during the June-December target period.
Other approaches which are feasible, but not developed in this investigation, would also be possible - such as a multi-year demolition schedule, and creating a notch to divert flow through the dam, thus keeping water elevations low even in higher flows. Both of these approaches create additional complexity, however, such as limits to the depth of notching from the top without cranes and impacts to power production for multi-year work.
As shown in Figure 1, river flow increases in fall and winter months. Lowering the reservoir through the power tunnels appears to be feasible if started on November 15 similar to the full dam removal approach. Lowering the reservoir would take approximately 10 days to accomplish under average flow conditions in November. By mid-December, flows into the reservoir will, on average, exceed the
GEC Yuba River Fish Passage Improvement Investigation Page B-1 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam capacity of the power tunnels and the reservoir water elevation will rise and overtop the dam removal activities.
The demolition approach developed here is based on conversations with engineers and contractors involved in the recent removal of three dams on the Elwha and White Salmon Rivers in Washington State. The methods shown are the methods used to remove these dams. Contractors indicated that methods such as blasting, expansive grouting, and diamond wire saw cutting were not cost competitive with direct impact methods. Drilling vertical holes in the concrete to increase hammer production (without blasting) was used extensively on Condit Dam concrete removal. Blasting could dramatically increase demolition production rates, but uncertainties regarding permitting requirements make the ability to use blasting unknown due to inability to keep all concrete from falling into the river. Therefore, for this investigation only impact demolition techniques were used. Cranes might also be set up on the dam to aid in removal. However, contractors considered this additional effort not to be cost effective.
The narrow upper portion of the dam will be the least efficient area for demolition activities because trucks may have to back into the loading area due to the inability make turns to change direction within the 20 foot width of the dam at the top. The removal approach constructs roads to each side of the dam to allow the option of one way truck traffic and no passing on the top of the dam.
The approach developed here shows several haul roads cut into the rock on the right bank leading to the top of the dam at various elevations. The grade limit on these roads was set at 20% which contractors advised was traversable for short runs with off road trucks. A contractor would most likely create several intermediate haul roads at closer elevations that reflect the limits of a loader’s height reach to access trucks. Cost and time for haul road construction was increased beyond the values for roads shown in sketches to account for those anticipated additional roads.
Two removal alternatives have been developed in the following discussion, removal to elevation 460 and elevation 430. Removal to elevation 460 allows continued use of existing intakes and power tunnels. Lowering further to elevation 430 requires changes to intakes and power tunnels, but would facilitate a shorter fish ladder. Both alternatives retain all existing sediment behind the dam, but they require more time to complete demolition than is available if reservoir drawdown were initiated on November 15.
Initiating the reservoir drawdown will cause a spike of suspended sediment in the downstream Yuba River. Starting the drawdown early enough in the year to allow time for completing the removal before December 15 would move the drawdown start date into July as indicated by the construction schedules. Reservoir drawdown start time calculations are based on concrete removal volumes and time requirements shown in Table 3 and Table 4.
November 15 was chosen for starting removal activities for the Complete Removal alternative to avoid, to greatest extent possible, impacts to fish rearing, spawning, and migration. The Partial Removal alternative, however, could begin on that schedule by constructing a deep notch through the dam that
GEC Yuba River Fish Passage Improvement Investigation Page B-2 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam would divert river flow away from the demolition and provide a means of continuing demolition through winter months. The notch would be constructed near the center of the dam down to the final demolition elevation and would be large enough to pass winter flows.
This “deep notch approach” was not investigated, however, because dam structural information was not available. Constructing a notch in the dam would eliminate the capability of the dam to act as an arch dam and sections above the dam would be cantilevered from the lower portions of the dam. Future investigations could resolve this uncertainty if structural drawings became available.
Production rates for removal and transport are based on Table 1 which shows the estimate of concrete demolition used to determine the time shown in the schedules in Appendix H and Table 3 and Table 4. It provides the assumptions used to develop costs and schedules. Should either of these partial removal options be developed, slower rates of demolition might be desirable - since the values shown in Table 1 are the upper limits imposed on production by the width of the dam and access to demolished concrete from the sides of the dam.
For this analysis 5 backhoes would demolish the concrete at a total daily production rate of 1,200 cubic yards (CY) per day. Two 3 cubic yard front end loaders would load the same volume per day into 5 off- road trucks with a capacity of 20 CY each (only partially filled -15 CY each). The truck haul capacity must exceed or equal that required to move 1,200 CY per day (5 trucks x 240 CY per truck per day = 1,200 CY per day). Demolished concrete and steel would occupy a greater volume of space in the truck than in the dam. For instance, removing a section of the dam that measured to be 15 CY in situ was assumed to occupy around 20 CY in the truck due to voids between the pieces of broken concrete. It was assumed for these calculations that the trucks would travel approximately 2 miles from the dam to the stockpile site at 20 mph where they would dump the load.
At the stockpile site, one backhoe would separate concrete and steel. Concrete could be further crushed and separated at this site depending on intended further use. For this investigation it was assumed that concrete would simply be loaded into 10 CY capacity over-the-road trucks and taken to a final deposition site within 10 miles of the stockpile site. Appendix A discusses these potential sites and provides a list of sites that accept recycled concrete. Further analysis would be required to determine salvage value and the best location for deposition of the broken concrete. These sites were listed in Appendix A to show that this type of site is available in the vicinity of the dam.
Table 2 provides the details assumed for schedule and cost analysis of transporting the material to the deposition site. Calculations show that five loaders would be required to load 15 trucks that would travel approximately 10 miles to the deposition site at 40 mph to remove all the concrete at the same rate that it was placed in the stockpile. A bulking factor of 10% was used for truck capacity. A 10 CY truck could then hold only 9.1 CY of concrete measured in situ in the dam. Depending on stockpile size, maintaining that rate may not be required. A large stockpile site could temporarily hold all the demolished concrete which would allow the contractor to use less equipment. Optimizing equipment use is beyond the scope of this investigation. The assumptions shown in these tables were made to show the feasibility of this approach.
GEC Yuba River Fish Passage Improvement Investigation Page B-3 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Table 1 Equipment Estimates for Demolition of Englebright Dam
Daily Concrete Demolition Rate
Daily Conc Hours/day Number of Rate/backhoe Demo rate Hoes Cy/Hr Cy/day 1,200 8 5 30
Loader Requirements
Number of Load Rate Maximum Bucket Load Cycle Loaders Cy/Hr Load Rate Size Time CY/day CY min 5 150 1,200 3 6
Maximum Haul Capacity from Dam Site to Temporary Stockpile Site CY per Truck # Haul Trucks CY/day/truck trips/day/ truck 15 5 240 16
Travel Time from Dam to Stockpile
Tip Time Truck Trip Truck Speed Load/Unload Minutes one way miles/hr Total Time miles minutes 30.00 2 20 18
GEC Yuba River Fish Passage Improvement Investigation Page B-4 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Table 2 Equipment Estimates for Transport from Englebright Dam to Salvage Site
Loader Number and Rate to fill Transport Vehicles Number Rate/Load Load Rate Bucket Load + Move of Cy/Hr CY/day Size Cycle Time Loaders CY min 5 150 1,200 3 6
Assumed Travel Requirements Trip Time Truck Trip Truck Speed Load/Unload Minutes one way miles/hr Total Time miles minutes 50 10 40 20
Number of Trucks and Haul Capacity Cy/day/truck trips/day/ Cy/Truck Number truck of Haul Trucks 82 9 9.1 15
Table 3 Concrete Removal Volume and Time to Elevation 460
Stage Stage area Stage Average Thickness Removed Working Time Daily Rate SF ft CY Days CY/hr 1 40,932 26 39,416 32.85 1200 2 16,636 30 18,484 15.40 1200 Total 57,900 48.25
Table 4 Concrete Removal Volume and Time to Elevation 430
Stage Stage area Stage Average Thickness Removed Working Time Daily Rate sf ft CY Days CY/hr
1 48,567 29 52,165 43.47 1200 2 28,419 35 36,839 30.70 1200 Total 89,004 74.17
GEC Yuba River Fish Passage Improvement Investigation Page B-5 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Average and Maximum Daily Flow at Station 11418000 Downstream of Englebright Dam
7,000 140,000
6,000 120,000
Avg Daily Flow Max Daily Flow
5,000 100,000
4,000 80,000
1942to 2011 cfs -
3,000 60,000 Average Daily Daily Average Flow cfs
2,000 40,000 Maximum Daily Flow
1,000 20,000
0 0
10/31 11/30 12/30
3/1 4/1 5/1 1/1 6/1 7/1
9/30 1/31 7/31 8/31
Day of the Year
Figure 1 Average Daily Flow and Maximum Flow - Yuba River
GEC Yuba River Fish Passage Improvement Investigation Page B-6 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Remove Dam to Limits of Current Generating Equipment - Elevation 460
This approach would remove Englebright Dam to an elevation just above the intake power tunnels for the power plants. The reservoir volume for a spillway elevation at 460 is approximately 50 million cubic yards, greater than the volume of sediment, approximately 28 million cubic yards, currently trapped behind the dam. Figure 2 shows the relationship between reservoir elevation and volume. The spillway lowered to elevation to 460 would remain above the reorganized sediment elevation at the face of the dam. Volume estimates were based on a 2004 estimate of sediment volume.1 Current sediment volume could be larger than this value, reducing the remaining reservoir water volume for elevation 460.
A pool sufficient for fish passage and flow into the power tunnels would remain near the dam. To provide volitional fish passage upstream, a fish ladder would be constructed from the base of the dam to the top of the reduced height dam. The ladder would include upstream resting pools for every 50 feet of vertical elevation rise. A multi-use, fish management facility would be built approximately 50-75 feet above the river and intersect with the fish ladder to allow tagging, holding, and sorting, as well as potential fish collection and transport operations.
The ladder would deposit fish in the pool upstream of the dam. As proposed, this lowered pool elevation would remain relatively constant because the power tunnels would not allow further drawdown and the spillway would not allow further rise in water elevation except as dictated by high flows over the top of the spillway. A fishway into this pool would not require the more sophisticated multiple exit openings into the receiving pool, unlike the requirements for fishway exit pools that vary in elevation. See Figure 4.
Downstream migrants would be guided by nets across the forebay into a collection facility. A new concrete flume would carry downstream migrants adjacent to the upstream fish ladder into the pool directly downstream of Narrows 2. A portion of dam on the right bank would remain above the spillway elevation to direct flow away from the fishway.
1 Snyder, N.P., Rubin, D.M., Alpers, C.N., Childs, J.R., Curtis, J.A., Flint, L.E., and Wright, S.A. 2004b. Estimating accumulation rates and physical properties of sediment behind a dam: Englebright Lake, Yuba River, northern California. Water Resources Research, 40, W11301, doi:10.1029/2004WR003279.
GEC Yuba River Fish Passage Improvement Investigation Page B-7 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Englbright Reservoir Storage Volume versus Height above Dam Base Elevation - ft msl 295 345 395 445 495 545 60,000,000
50,000,000
40,000,000
Cubic Yards Cubic 30,000,000 -
20,000,000 Volume Volume
10,000,000
- 0 50 100 150 200 250 Height above Base of Dam - feet
Figure 2 Englebright Reservoir Elevation vs. Volume
At elevation 460 the ladder height would be approximately 170 feet tall, still a very tall ladder by most standards but much lower than the 237 foot ladder required for the full height dam. A lower ladder would improve the operational feasibility. This option was explored to analyze feasibility, schedule, and cost associated with a fish ladder option that used the existing power tunnels with slight modifications.
Table 5 shows invert elevations for Narrows 1 & 2 power tunnels. The top of the tunnels are at elevations 458 and 459 for Narrows 1 & 2 respectively. Figure 3 shows the relationship of water elevation to the intake tower for Narrows 2.
For this investigation it has been assumed that the minimum operational elevation for power generation would be above the top of the power tunnels, elevation 460. This elevation was chosen as the lowest possible using the existing tunnels. Water levels in the reservoir are currently raised and lowered to allow the facility to operate as a re-regulating dam. Removing the dam to elevation 460 would eliminate the ability to significantly raise and lower water levels without altering the existing intake facilities.
GEC Yuba River Fish Passage Improvement Investigation Page B-8 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Table 5 Power Generation Facility Details
Narrows I Narrows II Intake Invert Elevation 450 msl Intake Invert Elevation 4392 msl Tunnel diameter 9 ft Tunnel diameter 20 ft Tunnel length N/A ft Tunnel length 750 ft Flow Capacity 730 cfs Flow Capacity 3400 cfs Generating Capacity 12 MW Generating Capacity 55 MW Head 240 ft Head 236 ft outlet elevation 284 ft outlet elevation 284 ft Centerline of Narrows 2 outlet 292.0 ft Powerhouse Top Deck 348.0 ft
Figure 3 Narrows 2 Intake Tower
2 Figure 3 is a drawing taken from “Yuba County Water Agency Fourth Five Year Safety Inspection Report, New Narrows Powerplant” G.S. Sarkaria, Consulting Engineer, October, 1989 that shows the center line of the power tunnel at elevation 447 instead of elevation 449 that can be calculated by Table 5. Information in this table are taken from Yuba County Water Agency, 2010, Pre-Application Document, Yuba River Development Project, FERC Project No. 2246
GEC Yuba River Fish Passage Improvement Investigation Page B-9 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Figure 4 Fish Ladder and Downstream Fish Collection at Elevation 460
GEC Yuba River Fish Passage Improvement Investigation Page B-10 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Figure 5 Proposed Haul Roads for Partial Removal to Elevation 460
Figure 6 Proposed Haul Roads with Topo for Partial Removal to Elevation 460
GEC Yuba River Fish Passage Improvement Investigation Page B-11 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Figure 7 Looking Upstream at Dam- Demolition Phases Removal to Elevation 460
GEC Yuba River Fish Passage Improvement Investigation Page B-12 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Dam Demolition Sequence
The following sequence of activities was used to develop construction sequencing and cost estimates.
1. Mobilize equipment to site, clear staging area near Narrows 2 powerhouse, and access upgrade roads. 2. Upgrade adjacent area roads and grade stock pile areas. 3. Construct haul roads at a 20% grade from dam to existing access roads starting with the roads to the top of the dam on both sides of the dam. These roads are required to allow several rock hammers to work simultaneously on the dam and meet tight schedules during low flows. 4. Lower the reservoir through the power tunnels over a period of 10 days. 5. Drill vertical holes for breaking concrete from the top of the dam. These holes will extend 67 feet deep from the existing spillway elevation to elevation 460. Holes will be placed on 5 foot centers across the top of the dam. Two to three drilling units will work simultaneously beginning near the center of the dam drilling over 1,000 three inch diameter holes over a period of approximately 42 days of drilling. Drilling holes will allow rock hammers to work more efficiently without the need for blasting. 6. Higher portions of the dam at elevation 542 adjacent to each bank will be removed to a slope of 20% to gain access to the central portion of the dam. 7. Demolition will proceed starting in the middle and working towards both ends of the dam. Concrete would be removed in horizontal lifts until the concrete in Phase I is removed to the limits of the ramps to the haul roads. Phase I allows trucks to enter the dam from one direction and leave dam on the opposite bank without maneuvering on the top of the dam. Ramps at a maximum slope of 20% up to the ends of the dam will allow concrete to be removed down to elevation 480 using both ends of the dam. 8. A new haul road on the right bank would be constructed for Phase II. Concrete nearer the right bank section of Phase II shown in Figure 7 (left side) could be removed to both sides of the dam. Concrete in near the left bank section of Phase II could only be removed to the northwest (right bank) side of the dam.
GEC Yuba River Fish Passage Improvement Investigation Page B-13 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Removal to Sediment Full Reservoir - Elevation 430
Several approaches to partial dam removal were explored as a means to bracket the challenges presented by partial removal of Englebright dam. The dam now provides power production, sediment storage, and recreation while eliminating anadromous fish passage. The current sediment volume behind the dam is estimated at 28.6 million cubic yards (21.9 million cubic meters).3
Figure 2 shows the relationship between reservoir volume and reservoir elevation. The lowest elevation the dam can be removed to and still retain its present uses is approximately elevation 430. This approach would allow future sediment moving into the reservoir to move downstream of Englebright Dam but retain the existing sediment in the reservoir in a reworked condition behind the dam. Also, lowering the hydraulic head would result in reduced hydropower production capacity.
Construction challenges discussed in the previous section will also apply to this approach, as well as present two additional challenges. Because the reservoir is completely filled with sediment in this approach, there will be no significant pool upstream of the dam. The pool allows sediment free water to be drawn into the power tunnels and would provide a means of depositing and collecting upstream and downstream migrants. The loss of a pool adjacent to the back of the dam will require installation of sluice gates to keep the fishway entrance and power tunnels free of sediment. Sluice gates would be opened in high flows to create a pool upstream of the dam. Figure 8 illustrates the arrangement.
Concrete demolition would follow the same process described in the previous section down to elevation 460, the lowest reservoir elevation that can be reached by directing river flow through the power tunnels. The existing power tunnels would not be functional with a reservoir pool elevation of 430. New power tunnels would be constructed to intersect with the existing tunnels and a new intake control structure would be built at the mouth of the tunnels. Figure 9 illustrates the approach for Narrows 2 intake tunnel.
Demolition below this elevation would occur after construction of new power tunnel intakes for Narrows I and Narrows II. After completion of the new tunnels and river flows receded sufficiently to allow further drawdown of the reservoir through the new intake tunnels, the reservoir would be lowered through the new tunnels to complete demolition of the dam to elevation 430.
Sluice gate construction would occur after lowering the dam spillway elevation to 430 by drilling and excavating a 20 x 50 foot wide notch in the dam. Concrete would be removed to within 10 feet of the upstream face of the dam. The gates would be installed before removal of the last 10 feet from the upstream face to allow construction in the dry. Figure 8, Figure 10 and Figure 11 illustrate the proposed gate structure and location. This option could also be an element of the Partial Removal to Elevation 460 approach if sediment volume at the time of construction increased to the point that sluicing was required to maintain a pool for power production needs. If structural analysis indicates the need, post tensioning steel would be used to reinforce the cantilevered section of the dam above the invert of the
3Stillwater Study
GEC Yuba River Fish Passage Improvement Investigation Page B-14 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam sluice way, to provide strength lost to removing the arch component of the dam in the sluice gate section.
Figure 10 shows the two phases of demolition for this approach. Phase I removal (green) shows the limits of material that could be removed to either side of the dam. Phase II removal (red) shows material that would necessarily be taken to the right bank due to access limitation discussed in the previous approach.
Figure 8 Proposed Sediment Flushing Gates
GEC Yuba River Fish Passage Improvement Investigation Page B-15 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Figure 9 New Narrows 2 Power Tunnel
Figure 10 Looking Upstream at Dam Elevation View of Removal to Elevation 430
GEC Yuba River Fish Passage Improvement Investigation Page B-16 National Marine Fisheries Service Final Report April 2014 Appendix B Partial Removal of Englebright Dam
Figure 11 Plan View of Dam Facilities at Elevation 430
GEC Yuba River Fish Passage Improvement Investigation Page B-17
Gathard Engineering Consulting APPENDIX C
Englebright Dam Concrete Volume Analysis
Yuba River Fish Passage Improvement Investigation
National Marine Fisheries Service
National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Appendix C
Concrete Removal Volume Calculations for Englebright Dam
Tables of Figures
Figure 1 Elevation...... 6 Figure 2 Elevation...... 7 Figure 3 Sections ...... 8 Figure 4 Sections ...... 9 Figure 5 Sections ...... 10 Figure 6 Sections ...... 11 Figure 7 Sections ...... 12 Figure 8 Sections ...... 13 Figure 9 Sections ...... 14 Figure 10 Sections ...... 15 Figure 11 Sections ...... 16
List of Tables
Table 1 Total Englebright Dam Volume Calculation Based on Horizontal Increments ...... 2 Table 2 Reproduction of Department of Safety of Dams Table Showing Englebright Dam Volume ...... 3 Table 3 Total Englebright Dam Volume Calculation Based on Vertical Cross Section ...... 4 Table 4 Concrete Removed above Predam Surface ...... 5
GEC Yuba River Fish Passage Improvement Investigation Page C -i National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Volume Analysis
Englebright Dam is owned by the Corps of Engineers. However, no documents showing details of the dam were available from the Corps of Engineers for use in this report. This lack of direct data lead to some uncertainty in the volume of concrete that would be necessarily removed to re-establish a free flowing river if the dam were removed.
Concrete volume calculations for full and partial removal of Englebright Dam were based on two documents available in the public domain. The first document is a plan view drawing of the dam created for the Sacramento Valley Utility Company Narrows Power Project dated March 15, 1939. Although the information presented in this drawing was not sufficient to precisely determine concrete volume, it was used to estimate the total concrete volume and the removal volume down to approximately predam elevations. That total volume calculation was compared to the volume listed for this dam on the California Division of Safety of Dams, Department of Water Resources web site for the dam.1 Values for the calculated volume and the stated volume compared well. See Table 1 and Table 2.
A more accurate analysis was conducted based on dam cross sections found in a 1986 seismic evaluation.2 Cross sections were presented in this document at construction joints denoted on original drawings. These were entered into AutoCAD and scaled to the dimensions shown on the drawings. The elevation of the limits of concrete removal was based on the elevation of the intersection of the cross section and the pre-dam surface shown in Figure 1 and Figure 2. Cross sections are shown in Figure 3 through Figure 11. These cross sections show the portion that would be removed for full dam removal in red outline, and partial dam removal to elevation 460 in green outline. Cross sections shown in the drawings do not show all of the concrete shown in dam elevations. Some additional concrete was placed near the right abutment that is not shown in the cross sections.
Based on the cross section area, calculated in AutoCAD, multiplied by the distance between the cross sections, Table 3 shows the volume of concrete to be removed for the complete and partial removal options. Table 3 calculates the volume of full removal to be approximately 215,000 cubic yards. Table 4 calculates that same volume in horizontal slices at a slightly higher volume of 223,000 cubic yards. The value used to determine total removal volume was increased to 250,000 cubic yards for cost and schedule analyses, because of the relatively poor quality of the information used to conduct the calculations.
1 http://www.water.ca.gov/damsafety/docs/Federal2012.pdf 2 Harry L. Englebright Lake, Yuba River, California, Seismic Evaluation of Englebright Dam, US Army Corps of Engineers, Sacramento, CA, November 1986
GEC Yuba River Fish Passage Improvement Investigation Page C -1 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Table 1 Total Englebright Dam Volume Calculation Based on Horizontal Increments
Total Volume of Concrete in Dam Vertical Increment Elevation ri re width Length Average Incremental Volume CY Total Volume CY ft ft Inside Radius exterior radius ft inside Length ft ft ft ft
542 20 575 8,889 15 527 480 500 20 1141 1025 12,915 21,804 17 510 472 493.7 21.7 1047 943 17,146 38,950 20 490 455 484.4 29.4 957 869 20,622 59,572 20 470 426 463.2 37.2 874 803 24,100 83,671 20 450 391 437.2 46.2 813 758 27,762 111,434 20 430 358 412.8 54.8 767 727 30,216 141,650 20 410 328 390 62 696 670 30,702 172,352 20 390 297 364.8 67.8 619 607 30,233 202,584 20 370 250 321.8 71.8 559 563 29,021 231,605 20 350 212 287.7 75.7 482 500 26,371 257,976 20 330 180.7 257 76.3 410 437 23,418 281,394 20 310 154.7 230 75.3 363 397 18,734 300,128 20 290 115.5 190 74.5 239 278 15,089 315,217 20 270 62 152 90 143 217 48,864 364,082
Total CY 364,082
GEC Yuba River Fish Passage Improvement Investigation Page C -2 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Table 2 Reproduction of Department of Safety of Dams Table Showing Englebright Dam Volume
GEC Yuba River Fish Passage Improvement Investigation Page C -3 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Table 3 Total Englebright Dam Volume Calculation Based on Vertical Cross Section
Full Removal Remove to 460 Remove to 430 Block Station Section Ground line Ground -5 Full removal Full removal Part removal Part removal Part removal Part removal Width ft Elev ft feet area SF Vol CY area SF Vol CY area SF Vol CY A 24.4 530 525 200 200 200 B 73.9 49.5 530 525 491 633 491 633 491 633 C 123.1 49.2 520 515 549 948 549 948 549 948 D 172.3 49.2 517 512 646 1,089 646 1,089 646 1,089 E 221.5 49.2 505 500 937 1,442 937 1,442 937 1,442 F 270.7 49.2 485 480 1684 2,388 1684 2,388 1684 2,388 G 319.9 49.2 462 457 2586 3,890 2164 3,506 3539 4,759 H 369.1 49.2 428 423 3760 5,782 1823 3,633 3198 6,138 I 418.3 49.2 403 398 6006 8,898 1836 3,334 3211 5,839 J 467.5 49.2 370 365 7900 12,670 1836 3,346 3211 5,851 K 516.7 49.2 320 315 11191 17,394 1836 3,346 3211 5,851 L 565.9 49.2 300 295 12461 21,550 1836 3,346 3211 5,851 M 615.1 49.2 290 285 13230 23,407 1836 3,346 3211 5,851 N 664.3 49.2 290 285 13127 24,014 1836 3,346 3211 5,851 O 713.5 49.2 300 295 12541 23,386 1836 3,346 3211 5,851 P 762.7 49.2 328 323 10131 20,657 1836 3,346 3211 5,851 Q 811.9 49.2 350 345 8368 16,855 1836 3,346 3211 5,851 R 861.1 49.2 380 375 5880 12,982 1800 3,313 3175 5,818 S 910.3 49.2 425 420 4083 9,077 2160 3,608 3535 6,114 T 959.5 49.2 488 483 1376 4,974 1376 3,222 1376 4,474 U 1008.7 49.2 530 525 493 1,703 493 1,703 493 1,703 V 1057.9 49.2 535 530 410 823 410 823 410 823 W 1107.1 49.2 535 530 214 569 214 569 214 569 1152.8 45.7 535 530 100 266 100 266 100 266 Total 215,396 57,240 89,812
GEC Yuba River Fish Passage Improvement Investigation Page C -4 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Table 4 Concrete Removed above Predam Surface
Excavation Depth ft Elevation Avg. Width of Dam- ft Average Segment Length ft Volume in Vert. Increment CY Total Volume CY
0 542 20 575 15 527 20 932 8,371 17 510 21.7 657 10,432 18,803 37 490 29.4 614 12,033 30,836 57 470 37.2 589 14,835 45,671 77 450 46.2 548 17,552 63,223 97 430 54.8 501 19,610 82,832 117 410 62 465 20,895 103,727 137 390 67.8 422 21,336 125,063 157 370 71.8 333 19,535 144,598 177 350 75.7 313 17,646 162,244 197 330 76.3 505 23,026 185,270 217 310 75.3 214 20,203 205,473 237 290 84.5 183 11,755 217,228 257 270 92 180 5,982 223,210
223,210
GEC Yuba River Fish Passage Improvement Investigation Page C -5 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
S F
Figure 1 Elevation of Englebright Dam Looking Downstream
GEC Yuba River Fish Passage Improvement Investigation Page C -6 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 2 Elevation of Englebright Dam Looking Upstream
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Figure 3 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -8 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 4 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -9 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 5 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -10 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 6 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -11 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 7 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -12 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 8 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -13 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 9 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -14 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 10 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -15 National Marine Fisheries Service Final Report April 2014 Appendix C Englebright Dam Concrete Volume Analysis
Figure 11 Sections
GEC Yuba River Fish Passage Improvement Investigation Page C -16
Gathard Engineering Consulting
APPENDIX D
Fish Passage Improvements
Alternatives
Daguerre Point Dam
Yuba River Fish Passage Improvements Investigation
National Marine Fisheries Service
National Marine Fisheries Service Final Report April 2014 Appendix D Fish Passage Improvements Alternatives at Daguerre Point Dam Appendix D
Fish Passage Improvements Alternatives at Daguerre Point Dam
Tables of Contents
Daguerre Fish Passage Approaches ...... 1 Rock Ramp ...... 2 Construction ...... 3 Downstream Weirs ...... 5 Construction ...... 5 Radial Gate Approach ...... 8
Table of Figures
Figure 1 Plan View of Ramp ...... 4 Figure 2 Typical Ramp Section ...... 4 Figure 3 Phase 1 Weir Construction...... 6 Figure 4 Plan View of Downstream Weirs ...... 7 Figure 5 Section through Weirs ...... 7 Figure 6 Elevation of Weir ...... 8 Figure 7 Section though Radial Gates ...... 10 Figure 8 Plan View of Gates ...... 10 Figure 9 Cofferdam for Demolition ...... 11
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Daguerre Fish Passage Approaches
Full removal of Daguerre Point Dam would allow anadromous fish passage at the dam. It would also eliminate the ability to divert water at facilities near the dam and immediately upstream of the dam. Alternatives to removal of the dam were investigated that would allow retention of present water diversions upstream of the dam but would also allow better volitional fish passage at the dam- including passage by green sturgeon, which currently cannot pass Daguerre Point Dam.
To provide fish passage three approaches were investigated, described below.
1. Rock Ramp: A low gradient ramp would be constructed extending from the top of the dam downstream, approximately 3000 feet. The ramp would provide a 50 foot wide access way for upstream migrants to pass over the dam. The low gradient would be sufficient to allow green sturgeon passage. Head gates at the top of ramp would restrict flow down the ramp during high flow events. A grade control across the river would control changes in grade and divert low flows to the entrance of the ramp. 2. Downstream Weirs: A ramp would provide upstream passage but would require screens or nets to direct downstream migrants to it. The low water depths would make nets or screens difficult or impossible to operate and maintain. Creating a ramp across the entire width of the dam would eliminate the need for directing the downstream migrants to the ramp. The weirs would be constructed to create a low gradient approach to the dam that would allow all species of anadromous fish to pass upstream and downstream of the dam. 3. Full Height Gates: Full height, steel radial gates would be installed as an added feature of the existing dam to allow intermittent lowering of the water surface. With the gates open, upstream and downstream passage would be available. With gates shut, gravity driven water diversion could occur. Criteria for water diversion volume and timing were not available to evaluate the feasibility of meeting both fisheries and water diversion requirements at the dam. Future study would be needed to determine whether these two competing demands could be met.
GEC Yuba River Fish Passage Improvement Investigation Page D-1 National Marine Fisheries Service Final Report April 2014 Appendix D Fish Passage Improvements Alternatives at Daguerre Point Dam
Rock Ramp
A “Rock Fill Ramp” approach would be constructed immediately downstream of the existing Daguerre Point Dam structure to provide volitional passage for upstream and downstream fish migration.
“Rock ramps are low gradient structures, incorporating either transverse or randomly placed ridge rocks. These ridges comprise large boulders placed at strategic points to create a series of pools and riffles that mimic flow conditions in the natural stream and allow fish to move from pool to pool and over the rock weirs through zones of low flow velocities and turbulence.1”
The following criteria were used to develop the feasibility level ramp design:
1. Gradient compatible with sturgeon and salmonid passage. 2. Protection against dewatering through ramp bed. 3. Ramp should contain several resting pools 4. Structure shall resist erosion in the 100 year flood. 5. Ramp shall be accessible for a range of flows.
Features of the ramp include:
1. The dam would be slightly notched to direct low flow to the ramp. 2. Water diversion facilities would remain operating as they currently operate. 3. The existing left bank fishway would be removed. 4. A downstream grade control would divert attraction water into the ramp. 5. Water depth at the dam crest can vary as much as 3 feet. A roller gate would be constructed at the top of the ramp to limit flow down the ramp in high flow conditions. 6. The ramp would be constructed at a low slope longitudinally to provide for green sturgeon upstream passage. A series of weirs and pools along ramp would create resting pools. 7. The ramp would provide downstream passage for some portion of the migrants.
The ramp would be constructed at approximately a 1% gradient to accommodate upstream sturgeon passage. While studies have shown that green sturgeon can move upstream at gradients above 4% for short distances2, for this initial level of design, the slope was assumed to be limited to an average of 1% to ensure feasibility. Details of pools and weirs within the ramp are beyond the scope of this conceptual design but the ramp width was set wide enough to include low flow meanders and pools. The ramp cross section would be sloped to the center to concentrate low flows. Higher flows would spill over the ramps sides and limit depth and velocities.
Total material volume required for ramp construction is estimated to be approximately 100,000 cubic yards. Surfacing rocks and rip rap would be purchased from local quarries.
1 Culvert Fishway Planning and Design Guidelines, Part H – Rock Ramp Fishways for Open Channels, James Cook University, Australia School of Engineering and Physical Sciences 2 Through Delta Facility White Sturgeon Passage Ladder Study, Department of Water Resources, State of California
GEC Yuba River Fish Passage Improvement Investigation Page D-2 National Marine Fisheries Service Final Report April 2014 Appendix D Fish Passage Improvements Alternatives at Daguerre Point Dam
The flow channel of the ramp would be constructed of grouted river rock. A geotextile liner would be placed between the fill material and grouted river rock channel to seal and prevent dewatering through the bed. Large rip rap would be used to stabilize the sides of the ramp.
At the downstream entrance to the ramp a grade control structure would be constructed across the river to divert attraction water to the entrance to the ramp and to direct fish to the ramp entrance. Flow volume and velocities in the ramp would be limited to reduce erosion. At the upstream entrance to the ramp a roller gate would limit the volume of water entering the ramp.
Construction The ramp would be located along the either the left or right bank of the river downstream of the dam out of the flow area to reduce potential erosion of ramp material during extreme high flow events. Figure 1 illustrates the concept with the ramp near the left bank. Figure 2 shows a section of the ramp near the dam. Construction of the ramp would occur in dry conditions. The base material could be constructed from sediment excavated from the gold fields upstream of Daguerre Point Dam, or concrete taken from demolition of Englebright Dam, or from local quarries. Future investigation would be required to determine the suitability of the material, grain size, and ownership to assess the feasibility of using sediment in the gold fields for fill material.
Cost analyses assumed that suitable material was available within 5 miles of the ramp. For this analysis we assumed that excavators with a 3 yard bucket could load 20 yard off road trucks which would transport the sediment to the ramp site. Graders would rework the material to form the ramp and vibratory rollers would compact the material.
A bedding layer of crushed aggregate 9 inches thick would support the grouted river rock channel. A geotechnical liner would be placed beneath the crushed aggregate to restrict water loss through the base of the ramp. The top of the dam would be notched approximately 1 foot to ensure that low flows enter the ramp. During high flow events water depth can be as high as 3 feet over the top of the dam. At the entrance to the ramp, high flows would be restricted by head gates to reduce flow in the ramp. Water depth and velocity would be monitored at the entrance to the ramp and automated controls would raise and lower the gates to control flow into the ramp.
At the downstream end of the ramp a grade control structure across the width of the river would direct low flows into the ramp entrance for attraction flows, and to provide a barrier to restrict upstream migrants’ entry to the area immediately below the dam. The barrier would be constructed of reinforced concrete, 6 feet deep by 4 feet wide.
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Figure 1 Plan View of Ramp
Figure 2 Typical Ramp Section
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Downstream Weirs
A “Downstream Weirs” approach would construct a series of weirs or grade controls across the width of the river downstream of Daguerre Point Dam. Weirs spanning the full width of the dam would eliminate the gates and allow for better downstream migrant passage. Instead of limiting the flow volume through the channel as the Ramp approach does, all river flow would pass down over the weirs.
Weirs would be constructed to create a gradient of approximately 1% downstream of the dam and would provide upstream and downstream volitional passage for sturgeon and salmonids. The Downstream Weir alternative would have similar capabilities as the Rock Fill Ramp alternative but would provide better passage characteristics for downstream migrants. This approach would also allow water diversion facilities to remain unchanged.
An approach similar to this was constructed to remove the Goldsborough Dam near Shelton, Washington in 2003. Weirs were constructed from driven steel sheet piles to restrict ground water flow and provide structural stability. Concrete caps were placed over the sheet piles for smoother flow and abrasion reduction. A notch near the center of the weir provides low flow and directs the course of the stream.
The following criteria were used to develop the feasibility level ramp design:
1. Gradient compatible with sturgeon and salmonid passage. 2. Protection against dewatering. 3. The weirs will contain a numerous resting pools. 4. The structure shall resist erosion in the 100 year flood. 5. The ramp shall be accessible for a range of flows.
Features of the Downstream Weirs approach include:
1. Water diversion facilities would remain operating as they currently operate. 2. Fishways would be removed. 3. Rip rap would provide protection against erosion around the structures. 4. A series of weirs and pools would create resting spots and a low gradient for sturgeon passage.
Construction Weir construction would require two phases to allow work to take place in the dry. The first phase would involve constructing a berm across the left half of the river to divert all flow to the right half of the dam. A temporary longitudinal sheet pile wall along the left edge of the river would be constructed to contain the fill material while the first phase was constructed and keep river flow out. See Figure 3. Steel sheet piles would be driven to create the weirs at approximately 100 foot intervals downstream of the dam. Areas where pools or other design features were desired may be spaced at greater intervals (not shown here). Weirs would be constructed from the temporary wall toward the bank. The top of each successive weir would be one foot lower in elevation than the adjacent upstream weir to create a longitudinal gradient of 1%.
GEC Yuba River Fish Passage Improvement Investigation Page D-5 National Marine Fisheries Service Final Report April 2014 Appendix D Fish Passage Improvements Alternatives at Daguerre Point Dam
A concrete cap across the top of the steel sheet pile would provide grade and erosion control. After construction of the weirs the area between the weirs would be filled with sediment excavated from upstream of Daguerre Point Dam. Fill material would be excavated by 3 yard front end loaders, placed into 20 yard off road trucks to be hauled to the weirs. Estimated round trip distance for the trucks would be approximately 5 miles.
Vibratory rollers would compact the sediment. The fill material would be graded and river rock would be placed over the fill material. It was assumed that sheet piles and compaction would provide sufficient resistance to subterranean flow to eliminate the need for a geotextile liner to restrict flow. Rip rap would be placed along the intersection between the end of the weir and the bank to stop potential erosion in high flows.
After completion of Phase 1 construction, the upstream diversion berm would be removed and relocated to the right side of the river. See Figure 4 through Figure 6. River flow would be diverted into the newly completed Phase 1 section of the river. Phase 2 construction would essentially mirror Phase 1 construction. However, the haul distance would change significantly from 5 miles round trip to approximately 20 miles. The nearest river crossing is approximately 6 ½ miles upstream of the dam. Fill material would have to be hauled to the crossing and back to the dam along Browns Valley Road.
After completion of Phase 2, the longitudinal sheet pile wall would be removed. The diversion dam would be removed and the river would be allowed to flow over the weirs.
Figure 3 Phase 1 Weir Construction
GEC Yuba River Fish Passage Improvement Investigation Page D-6 National Marine Fisheries Service Final Report April 2014 Appendix D Fish Passage Improvements Alternatives at Daguerre Point Dam
Figure 4 Plan View of Downstream Weirs
Figure 5 Section through Weirs
GEC Yuba River Fish Passage Improvement Investigation Page D-7 National Marine Fisheries Service Final Report April 2014 Appendix D Fish Passage Improvements Alternatives at Daguerre Point Dam
Figure 6 Elevation of Weir
Radial Gate Approach
Fish passage at Daguerre Point Dam could be accomplished by eliminating the dam as a structural barrier. Installing radial gates would allow the barrier to be removed on an intermittent basis by raising the gates above the water surface. A free flowing river through the gate openings would allow upstream and downstream migrant passage. With the gates closed, water could be diverted through the canals. Details of the rate and timing of diversion in the documents reviewed were inconsistent or not available. However, opening and closing gates on a daily basis would allow diversion and passage through the entire diversion and fish migration season. Further investigation would be required to determine the feasibility of this approach because of limitations imposed by water diversions, as well as other issues associated with riverine geomorphology and habitat impacts; however, this approach may be capable of allowing complete passage for both upstream and downstream migrants without significant loss of water diversion capacity.
An inflatable bladder or roller gates could also be used as alternatives. The following describes an approach to accomplish complete river diversion through radial gates.
Discussion and Assumptions:
1. An opening in the existing structure would be constructed 250 feet wide to accommodate the construction of a final opening dimension of 200 feet. See Figure 8 and Figure 9.
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2. Discussions with gate manufacturers indicate that the optimum operational ratio of height to gate width is approximately 1:1. Gate height was assumed to be 25 feet. For this analysis a gate width of 20 feet was chosen. Wider gates and fewer piers would also be possible but a study of dimensions would be required to determine optimal gate and opening dimensions. The conceptual design includes 10 gates, each 20 feet wide. Piers to support lifting and sealing apparatus would be 5 feet wide. A sketch of the proposed arrangement is illustrated below in Figure 7.
3. The upstream portion of the 250 foot section of the dam to be removed for gate construction would be protected against stream flow by placing a sheet pile wall in the sediment as illustrated in Figure 9 below. Demolition work would begin in the month of March. All concrete work would be finished by the end of November to avoid extreme river flows which have the potential to overtop the dam. Pumping capabilities would be included to ensure dry conditions for the placement of concrete and removal of demolition debris. 4. Gates would be constructed starting at least 50 feet from the left bank. Access for construction and demolition would be from the right bank. A ramp constructed from aggregate would allow access to the reservoir.
5. Sediment against the upstream face of the dam would be removed and placed in front of the dam to create an access ramp to the area for demolition and construction activities after the sheet piles were in place. 6. Demolition would occur using drilling and impact demolition techniques after sheet pile installation was complete. Dam concrete would be hauled in 10 cubic yard trucks to a site within 20 miles of the dam location. No economic value was assigned to the concrete but the demolished concrete would have value as crushed aggregate.
7. Proposed gate configurations are based on discussions with radial gate suppliers. An actual cost proposal from a manufacturer is provided in Appendix G – Cost Estimates, for reference. The proposal was the chosen bid for a different, smaller project. Based on discussions with suppliers, costs were scaled to be appropriate for this larger proposed project.
8. Pier and access bridge construction would begin immediately after dam demolition. Access to the gates would be by a 12 foot wide concrete or steel bridge with 11 piers above the dam at an elevation above the high water elevation. No additional foundation improvement was included for the bridge since the dam appears to be founded on rock. Similarly, no additional foundation improvements were considered necessary for the gate piers. Eleven 5 foot wide reinforced concrete gate piers would be constructed to seat and lift gates as illustrated in Figure 7.
9. Construction would require one year to complete. Sheet piles would remain in place over winter. Costs to winterize the unfinished construction would depend on cost versus risk assessments. Risk would include river elevations that would overtop the sheet pile cofferdam causing erosion of sheet pile support and loss of sheet piles. A lump sum place holder for winterization is included in the Opinion of Probable Cost, discussed in Appendix G.
GEC Yuba River Fish Passage Improvement Investigation Page D-9 National Marine Fisheries Service Final Report April 2014 Appendix D Fish Passage Improvements Alternatives at Daguerre Point Dam
Figure 7 Section though Radial Gates
Figure 8 Plan View of Gates
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Figure 9 Cofferdam for Demolition
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Gathard Engineering Consulting
APPENDIX E
Water Diversion
upstream of
Daguerre Point Dam
Yuba River Fish Passage Improvements Investigation
National Marine Fisheries Service
Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam Appendix E
Water Diversion Upstream of Daguerre Point Dam
Table of Figures
Figure 1 Well Point Example ...... 5 Figure 2 Showing Extent of Daguerre Sediment Impoundment ...... 5 Figure 3 Daguerre Point Dam Removal Elements ...... 6 Figure 4 Diversion Dam Conceptual Arrangement ...... 7 Figure 5 Section through Bypass Channel ...... 8 Figure 6 Longitudinal Section through Diversion Channel ...... 8 Figure 7 Yuba River Elevation Upstream of Daguerre Point Dam ...... 9 Figure 8 Aggredation for Funs 1 through 3 at Proposed Upstream Diversion Location ...... 9
GEC Yuba River Fish Passage Improvement Investigation Page E-i Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
Upstream Water Diversion Facilities
Yuba River water is elevated approximately 25 feet by Daguerre Point Dam. The higher river water elevation provides irrigation associations ability to divert water at three locations upstream of the dam. Removing Daguerre Point Dam would eliminate the ability to use gravity to divert water to these three locations. Therefore, a new facility - located at a higher elevation approximately 2 to 3 miles upstream of the dam - is proposed to provide gravity flow (via connecting canals, pipes and siphons) to these three locations.
One irrigation district, Browns Valley, also uses a lift station to divert up to 65 cfs. Browns Valley water diversion was assumed to be included in the gravity flow water diverted upstream of the dam for this investigation. However, since this water is pumped, a new screened diversion on the north side of the river near the current location could also be an option, but is not developed here.
The Hallwood-Cordua Canal diverts up to 625 cfs. The combined total diversion for these three diversions is reported to be 1,085 cfs. The following flow rates for each diversion location were assumed for the conceptual design of surface diversion facilities to replace the three existing facilities after removal of Daguerre Point Dam:
Hallwood-Cordua Canal 625 cfs South Yuba/Brophy Diversion Canal 455 cfs Browns Valley Irrigation District 65 cfs
To replace gravity water diversion facilities upstream of Daguerre Point Dam, a new low height diversion dam would be constructed approximately 2 to 3 miles upstream of the current dam in a reach beyond the effects on river grade of Daguerre Point Dam removal. A low-slope, rock-lined fishway would allow volitional passage around the diversion dam. The proposed facilities would consist of the following features:
A rock lined bypass ramp, approximately ¼ mile long, would allow upstream and downstream volitional fish passage. The slope of this ramp would be approximately 1%. A grade control structure at the upstream end of the ramp would split flow between the bypass ramp and diversion facilities. A longitudinal wall between the bypass ramp and diversion channel would keep flow for the ramp and the diversion facilities separate. The grade control structure and the location of the longitudinal wall would be constructed to distribute flow between bypass channel and diversion flows. Water diverted for irrigation use would flow into a rock lined channel and form a pool behind a low head dam at the end of the channel. Water would be diverted through a trash screen into a concrete head control box. The head control box would limit flow into a clay-lined diversion canal to approximately 3,000 cfs during high flow events, but allow 1,085 cfs during non-flood flow.
GEC Yuba River Fish Passage Improvement Investigation Page E-1 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
Flow entering the clay-lined diversion canal would be limited by head box controls. Automated gate controls to limit flow into the canal could be developed, but are beyond the scope of this conceptual investigation. Flow in excess of the desired diversion flow would spill over the dam at the end of the channel or over the side wall back into the river. Water diverted through the head box at the canal entrance would flow into a clay-lined delivery canal which would transport it to the irrigation districts intake pipes. Fish contained in the diversion water would be collected by longitudinal screens and returned to the river. Fish screens would be upstream of water diversion points. Browns Valley would divert up to 65 cfs of water by pumping at the end of a 5 foot diameter intake pipe approximately 2 miles downstream of the diversion point. Flow in the diversion canal in excess of 1,020 cfs allowed for the remaining irrigation purposes would be diverted back into the river approximately 2 ½ miles from the diversion point. An overflow weir in the side of the canal near the point of diversion for Hallwood Cordua would set water elevations in the diversion canal at that point to limit gravity flow diversions for Hallwood- Cordua and South Yuba/Brophy. Just downstream of the overflow weir a head box would control flow into 8 – five foot diameter HDPE pipes to not more than 600 cfs. The HDPE pipes that would deliver water to Hallwood Cordua would be buried beneath the alluvium and the river. Hallwood Cordua water would also be screened for fish at the existing fish screens just downstream of Daguerre Point Dam. The remaining flow for the South Yuba – Brophy diversion would enter a head box that would limit flow into the South Yuba/ Brophy diversion.
Flow velocity criteria for the conceptual level design of new fish screens for the approximately 3,000 cfs diverted into the canal would be 0.4 feet per second (f/s). Pipe flow velocities for the preliminary sizing calculations were assumed to be 4 f/s. The clay lined canal was assumed to be 150 feet wide and side walls were assumed to be 5 feet above the thalweg.
A similar, but smaller, facility has been constructed on the Elwha River in Washington State to replace pre-dam removal water diversion facilities and is currently operational. That facility diverts 200 cfs of river water which is used for the domestic water supply for the City of Port Angeles, a fish rearing facility, and for industrial facilities in Port Angeles. On the Elwha River, water was successfully diverted in this fashion while millions of cubic yards of sediment eroded downstream as a result of the removal of two upstream dams. Figure 3, below, illustrates the elements of the upstream diversion.
Figure 3 shows the overall configuration of the proposed bypass channel concept. Figure 4 illustrates the layout for the proposed upstream diversion dam. This sketch is based on placing the diversion dam in a location along the river that has a stable plan and vertical elevation configuration with a slope of less than 1%. As shown in Figure 7, the slope of the thalweg varies considerably upstream of the dam. The average slope in the vicinity of Daguerre Point Dam is slightly greater than 0.2% which would result in a fish ramp approximately ¼ mile long.
GEC Yuba River Fish Passage Improvement Investigation Page E-2 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
The approximate location of the proposed fish ramp and diversion, shown on the profile in Figure 7, intake would be beyond the influence of upstream erosion resulting from dam removal. Figure 2 shows the longitudinal profile and the influence of the sediment impounded by the dam. Figure 8, provided by Stillwater Sciences as part of their coordinated work with this project (but not specifically included in the Stillwater Study), shows the range of potential aggradation, at the proposed diversion dam location, that might occur if Englebright Dam were also removed. Further study of the river would be required to determine whether a natural rock outcropping could be used to create a barrier to vertical changes in river thalweg, or whether a man-made grade control would be required. Further study would also be required to determine the optimum timing of construction of the upstream diversions considering the potential aggradation if Englebright Dam were also removed. For this investigation it was assumed that upstream diversion facilities would be constructed before breaching Daguerre Point Dam as discussed in Appendix H.
To be conservative, a grade control structure is proposed for this conceptual study. Some bank enhancement and stabilization might also be required upstream of the grade control limit lateral migration and control river width. At the grade control structure, river flow would be split between the fish ramp and diversion channel by a longitudinal wall.
A screened weir with a gated control, approximately 100 feet long, would divert up to 3,000 cfs into the water diversion collection channel. The barrier wall along the right side upstream of the diversion dam would help control the elevation of the water entering the collection channel. High flows would spill over the dam and right side barrier wall. Figure 3 through Figure 6 illustrate details of the water diversion collection canal. The diversion canal would be approximately 14,000 feet long and the elevation would drop approximately 20 feet over this distance. The canal could include intermittent transverse weirs to control water velocities and flow volume.
If Englebright Dam were removed, a large quantity of sediment could move into the section of river where the bypass ramp is proposed to be located. High TSS and bed load would continue to move downstream for several months after dam breach. To reduce maintenance dredging and enhance operation of the canal, sediment would be continuously diverted through low-level openings in the intake channel walls and through pipes in the bottom of the inflow control box.
Some of the sediment would nonetheless enter the diversion canal. The canal would also function as a settling basin that would deposit much of the sediment entering it along the bottom of the canal. A small dredge would be purchased to allow sediment removal from the canal and diversion facilities as necessary. The amount of sediment entering the canal would diminish over time and dredging requirements would diminish accordingly.
Detailed information regarding the volume and timing of water diversion upstream of Daguerre Point Dam was not available for this report. Further investigation would be required to determine whether water diversion timing would coincide with high sediment flow and to confirm assumed diversion flows. For this investigation, upstream water diversion facilities would be constructed and Daguerre Point Dam would be removed three years after Englebright Dam to allow time the river to stabilize in the proposed
GEC Yuba River Fish Passage Improvement Investigation Page E-3 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam upstream diversion location. Sediment deposition and sediment flow at the existing diversion facilities after breaching of Englebright Dam will depend on river flows and details of the removal process. River water may carry more sediment than the diversion existing canals could reasonably remove.
To ensure that high sediment loads do not restrict water diversion capabilities, a temporary supplemental water supply for the diversions would be provided. Beginning immediately after Englebright Dam removal and continuing for several years after Daguerre Pont Dam, replacement water would be extracted by construction of well points along the river and in the gold fields upstream of Daguerre Point Dam.
While further investigation of the elevation of the water table, its connectivity to the river water surface, and the feasibility of driving well points will be required to fully analyze the feasibility of using ground water as a temporary supplement to surface water diversion, this investigation assumes that the porous nature of the material in the gold fields would be capable of producing sufficient temporary flows and that ground water elevations are hydraulically connected to the river water elevation in the immediate vicinity of Daguerre Point Dam.
For this conceptual design, approximately 1,500 well points spaced at approximately 10 feet apart would be constructed in this porous material to meet temporary water withdrawals. Each well point was assumed to be capable of producing approximately 100 gallons per minute of flow. This would supply approximately 1/3 of the total assumed maximum flow of 1085 cfs. The system could be conceptually expanded to provide the entire diversion. For this investigation we have assumed that the combination of dredging and temporary groundwater could ensure continued uninterrupted irrigation flow.
Conceptually, conventional wells could also be built to supply temporary water supplementation for several years after full removal of Englebright Dam. While conventional wells would initially supply more water per well they would be in fixed locations which could cause eventual clogging of the wells. Well points could be monitored and easily moved if clogging of a particular location occurs. This flexibility would allow for more immediate response and flexibility. For this reason well points rather than conventional wells are proposed.
“Well point systems are generally used to lower groundwater levels to provide stable working conditions in excavations and are particularly suited to dewatering for shallow foundations and trench works. This method is capable of dealing with a wide variety of ground conditions, particularly suited to non-cohesive soils. A well point system consists of a closely spaced series of small-diameter shallow wells. The well points are connected to a common headermain and are pumped with a high-efficiency vacuum dewatering pump. The well points are usually installed using a jetting tube and pump. The two combined are a rapid and cost effective method of installing disposable well points; the use of filters reduces undermining and produces clean discharge water, this system can be designed to suit most excavations.1 ”
1 http://www.groundforce.uk.com/Pump+Hire/Products/Well+Point+Dewatering
GEC Yuba River Fish Passage Improvement Investigation Page E-4 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
Figure 1 Well Point Example
Figure 2 Showing Extent of Daguerre Sediment Impoundment2
2 Taken from the Stillwater Study
GEC Yuba River Fish Passage Improvement Investigation Page E-5 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
Figure 3 Daguerre Point Dam Removal Elements
GEC Yuba River Fish Passage Improvement Investigation Page E-6 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
Figure 4 Diversion Dam Conceptual Arrangement
GEC Yuba River Fish Passage Improvement Investigation Page E-7 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
SEDIMENT BY-PASS PIPES RIGHT BANK
INTAKE CONTROL STRUCTURE TRASH SCREEN & GATE DIVERSION DIVERSION CANAL DAM LONGITUDINAL BARRIER FOR DIVERSION FISH BYPASS RAMP
SECTION THRU BY PASS CHANNEL 1 NTS
Figure 5 Section through Bypass Channel
`
Figure 6 Longitudinal Section through Diversion Channel
GEC Yuba River Fish Passage Improvement Investigation Page E-8 Gathard Engineering Consulting Final Report April 2014 Appendix E Water Diversion Upstream of Daguerre Point Dam
Figure 7 Yuba River Elevation Upstream of Daguerre Point Dam
Figure 8 Aggradation for Runs 1 through 3 at Proposed Upstream Diversion Location
GEC Yuba River Fish Passage Improvement Investigation Page E-9
Gathard Engineering Consulting
APPENDIX F
Fish Ladders for Partial Removal of
Englebright Dam
Yuba River Fish Passage Improvement Investigation
National Marine Fisheries Service
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
Appendix F
Fish Ladders for Partial Removal of Englebright Dam
Table of Figures
Figure 1 Plan View of Multiuse Facility and Fishway Entrance ...... 5 Figure 2 Section through Fish Ladder near Switchback ...... 6 Figure 3 Plan View of Fish Ladder and Downstream Migrant Facilities Removal to Elevation 460 ...... 7 Figure 4 Plan View with Photograph Removal to Elevation 460 ...... 8 Figure 5 Plan View of Fish Ladder and Downstream Migrant Facilities Removal to Elevation 430 ...... 9 Figure 6 Plan View with Photograph Removal to Elevation 430 ...... 10
GEC Yuba River Fish Passage Improvement Investigation Page F-i
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
Englebright Dam Fish Ladders
Partially removing Englebright Dam would involve removing the upper part of the dam to either elevation 460 or 430 as discussed in Appendix B – Partial Removal of Englebright Dam Removal. Lowering the dam was studied to determine cost, schedules, and feasibility of constructing a ladder that reduces the effects of long runs and water temperature rise that might be associated with a ladder running the full height of Englebright Dam.
Several challenges to the construction and operation of a ladder are present at this site. Construction of a ladder would require excavating a bench into the side of the rock canyon walls that confine the river downstream of Englebright Dam. The south canyon wall is nearly vertical. The most likely alignment would be up the north canyon wall which is still very steep at a slope of approximately 1 vertical to 1 horizontal.
To provide volitional upstream salmonid passage, fish ladder construction - from just downstream of Narrows II powerhouse outflow to an elevation approximately four feet below the crest of the spillway - would be required as part of either “Partial Dam Removal” concept. The concrete ladder would consist of 8 feet by 10 feet pools with a vertical slot configuration. Ladders similar to this have proven effectiveness up to at least 196 feet in vertical rise.1
Vertical rise for the Partial Removal options to elevation 460 and 430 would be 170 feet and 130 feet respectively - within the range of proven feasibility. While the height of a ladder is not necessarily a limiting factor; other factors are relevant to fish acceptance and use of a ladder. Ladders designed for strong swimming fish such as anadromous salmonids can be unsuitable for other types of fish. The ladder envisioned for Englebright would probably not pass all resident species well, or at all. Further assessment of the biological impact of this selectivity effect would be required.
To take advantage of a water supply from the penstock of Narrows II for attraction flows, the entrance to the ladder would need to be located near the power house. Ladder alignment would follow the contours of the bank and have to switch back and forth to reach the top of the dam. Access to the ladder would be from an adjacent roadway which would also need to switch back and forth.
While having the ladder entrance here may work well when there is no spill, during spill conditions fish might move into the pool at the base of the dam. Future studies would be required to assess ladder efficiency based on operational changes resulting from: 1) the lower reservoir elevation and lack of
1 North Fork Dam Fish Ladder, Upstream Fish Passage Survey, Pelton Round Butte Hydroelectric Project, Duke Electric Services, page 15
GEC Yuba River Fish Passage Improvement Investigation Page F-1
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam regulating ability, 2) smaller reservoir pool depth, 3) possible changes in spill timing and frequency, and 4) possible changes in water quality due shorter reservoir residence time and shallower depths.
The Partial Removal Option would reduce the surface area of the reservoir which would in turn reduce surface water temperature rise associated with large reservoirs. However, the depth of the pool behind the dam, typically a source for cooler water used for attraction flows in ladders, would also be greatly reduced or eliminated. The typical cold water discharges from Colgate powerhouse (upstream) may mitigate temperature issues associated with fish ladder performance; but further study of attraction flows and water temperature investigations are beyond the scope of this report. Future investigation to determine water temperature effects on operations with a reduced reservoir size and depth would be required to fully evaluate the feasibility of ladders for the Partial Removal approach.
The ladder would include upstream resting pools for approximately every 50 feet of vertical elevation rise and a multi-use facility to allow tagging and collecting fish for transport. This proposed facility would be located near the existing power house access road on the north side of the river approximately 50 feet above the river. The road to the facility would be widened and paved to allow more space at the facility for maneuvering vehicles.
The reinforced concrete ladder would be constructed in the rock walls of the canyon above the river on the north side of the river. Each pool in the ladder would be approximately 1 foot higher than the adjacent downstream pool and would be 10 feet long. The interior would be 8 feet wide to form an overall slope for the ladder of 1 vertical to 10 horizontal. This would create a ladder approximately 1700 feet long between the intake and exit of the ladder, not including the resting pools and a multi-use fish management facility. Resting pools were assumed to each be 50 feet long and the multi-use facility was assumed to be 100 feet long, creating a length of 1,900 feet between the intake and exit of the ladder. Figure 1 through Figure 6 illustrate the location and details of the ladder.
A fish collection and handling facility will undoubtedly be needed. Although a nominal facility is included in this report, development of its actual size and features is a separate task beyond the scope of this report. Recent trapping and sorting facilities in the Northwest have cost up to $20 million, but the actual cost at Englebright would depend upon site specific studies and the range of fish management capabilities desired.
MWH investigated the feasibility of upstream and downstream passage in the Yuba River Fish Passage Conceptual Engineering Project Options (MWH 2010). That document investigates a full height ladder and downstream migrant collection facilities. MWH 2010 proposed two juvenile fish collection facility alternatives which would include either a floating surface collector, or two vertical plate fish screens to collect downstream migrants into a conduit. In this study, a different reservoir situation is considered as a consequence of reduced dam height; the pool width behind the dam would be significantly smaller - from approximately 820 feet wide (currently) to less than 400 feet wide for the reduced crest heights of 170 and 140 feet.
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National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
A fish ladder exit (in top of reservoir) by itself would not attract a meaningful number of downstream migrating fish. They would follow the flow, either to the turbines, or over the spillway. A means is needed to encourage fish to utilize the downstream fishway as a migration corridor. In order to provide an alternative approach to the relatively more complex and expensive surface collection facilities outlined in the MWH 2010 report, barrier guide nets were investigated in this report as a means to divert downstream migrants to an intake facility, which would then direct fish to a collection pipe that would carry them along the fish ladder access way to the river adjacent to the ladder entrance. While barrier nets have the potential to improve downstream guidance (at a tenth of the cost of most alternatives including surface collectors2) they are not suitable for sites that have much debris, freeze frequently in winter months, where downstream migrant size may be too small for net openings that effectively pass flow to the power tunnel intakes, or where approach velocities are too great.
In practice, nets are taken out of the water or in some operational conditions, nets may be potentially lowered to a more protected subsurface elevation when conditions become too physically challenging or there are few fish present. Design must accommodate net configurations and operations that allow for boating traffic. Other behavioral fish guidance devices may also contribute to enhanced guidance performance. Specific hydraulic analysis of reservoir and attraction flow is needed to support design of a functional guide net system. Studying these variables at this site for these conditions is beyond the scope and knowledge available for this investigation. We offer no opinion on whether guide nets would be a feasible alternative at Englebright, how much they might improve guidance efficiency, or what guidance efficiency would be sufficient. Installation of barrier nets at Englebright would likely be an experimental process, developed over a number of years, until a solution was developed that met expectations. However, the suitability of the design proposed here likely depends largely upon effectively operating guide nets.
For this investigation, a nylon net approximately 450 feet long would be placed across the upstream end of the forebay to guide downstream migrants to a multi-elevation weir that would allow intake at several elevations. Weir intake elevation would be adjusted to match forebay elevation. For nets to be effective, velocities perpendicular and parallel to the nets must be sufficiently low to keep the fish from becoming caught in the net. Issues involved in net feasibility such as flow into the turbines, migration timing, water depth at the net, and ability to maintain the nets will determine whether nets are a feasible alternative to mechanical surface collection devices. For the partial dam removal approaches that would allow continued use of existing power intake facilities, lowering the spillway elevation would reduce the range of water surface elevations to approximately 3 feet, between elevations 463 and 460. This would reduce the complexity required both for entering the collection weir and exiting the fish ladder compared to the range of elevations the reservoir currently experiences. The entrance to the downstream collection facility would be approximately 200 feet upstream of the dam, just upstream of the Narrows II power tunnel intake.
2 Fish Passage Technologies: Protection at Hydropower Facilities, OTA-ENV-641, Chapter 4
GEC Yuba River Fish Passage Improvement Investigation Page F-3
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
The entrance to the fish ladder would be located just downstream of Narrows II powerhouse. Flow through the ladder would be between 30 and 40 cfs. Additional attraction water would be provided from the power tunnels as discussed in the previous MWH 2010 study. The auxiliary water system (AWS) would deliver approximately 340 cfs to the ladder entrance pool, which represents 10 percent of the peak discharge flow from the Narrows II powerhouse.3 A smaller, shallower pool will not provide the same cool water temperatures that the deeper current pool provides but the cold water discharge from Colgate powerhouse (upstream) may offset increased water temperatures. The ladder would be constructed up the river bank heading downstream and would switch back to head upstream so that it would cross the powerhouse access road. The fish ladder would pass beneath the access road with a water elevation at approximately 340 msl. A bridge with deck made of steel grating to allow light into the ladder would be placed over the tunnel to allow access to the powerhouse. After crossing the road, the ladder would be cut into the hillside running at a 10% slope. It would be intercepted by a multi-use fish management facility that would provide a fish resting area, and it would also be used to tag, collect, count, and inspect fish as they move up the ladder. The multi-use facility could contain two nominally 50 foot-long by 10 foot-wide holding ponds that could be used for tagging or collection for transport. A fish crowder or other devices could be provided to help direct and collect fish. An overhead crane would be used to move fish to trucks. A large paved area would be required for turning and loading trucks. To accomplish this, a new retaining wall would be constructed to allow the area in front of the facility to be expanded. Reclaimed concrete aggregate and other rock/soil fill material (from other aspects of dam demolition or deconstruction) might be recycled here to provide foundational material inside the retaining wall, helping to raise the foundational grade to a height where the multi-use facility can be constructed adjacent to the improved access road. Detailed design of the multi-use facility concept would be developed in a separate process. The proposed multi-use facility would be approximately 100 feet long by 35 feet wide. The width of the facility is limited by the retaining wall location and the extent of hillside excavation possible. The limits of the space in this location will need future investigation to accurately define the maximum width feasible at this location. The fish ladder would continue through the multi-use facility with gates to allow fish to be directed into the multi-use facility when trapping was being conducted. Resting pools would be approximately 20 feet long to create regions of water low velocity (1.5 to 4 fps) where fish could rest before proceeding. Alternatively, additional fish ladder resting pools might be designed with more depth in compensation for less length. Two additional resting pools would be constructed at intervals of approximately 50 feet vertically or 500 feet longitudinally. Optimal design and placement of resting pools should be investigated in future design efforts. The ladder would continue along the hillside and penetrate the dam at an invert elevation of approximately 4 feet below the spillway elevation. It would be extended at a constant elevation along the bank of the reservoir approximately 200 feet to extend beyond the barrier net. Three exit orifices
3 Yuba River Fish Passage, Conceptual Engineering Project Options, Montgomery Watson Harza for National Marine Fisheries Service, 2010
GEC Yuba River Fish Passage Improvement Investigation Page F-4
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam would allow exit from the ladder at three reservoir elevations from 463 to 460 extending the ladder another 40 feet into the reservoir. Construction of the fish ladder would require rock excavation, which involves techniques similar to concrete demolition. Rock would be demolished, loaded, and hauled in a similar manner to the methods described in the dam demolition appendices. Ladder construction would be of reinforced concrete. Formwork would proceed from top to bottom. Placing concrete would be via pump truck. A 9 foot wide vehicle access way would run adjacent to the ladder. A walkway would be provided for ladder inspection. The uphill side of the ladder, adjacent to the excavated hillside, would have a higher concrete wall to protect against falling debris. The sections without the extended concrete wall would have netting along the sides of the fishway extending vertically approximately 4 feet to keep fish from jumping out of the fishway. Construction in the region immediately adjacent to the dam may involve either retaining walls or a bridge to access the face of the dam. Future studies would be required to refine the details of ladder construction. Figure 3 provides a schematic representation of the ladder alignment. Figure 2 provides a cross section of the ladder and bench into the hillside showing the location of the access way relative to the ladder, near the switch back section.
Figure 1 Plan View of Multi-use Facility and Fishway Entrance
GEC Yuba River Fish Passage Improvement Investigation Page F-5
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
Figure 2 Section through Fish Ladder near Switchback
GEC Yuba River Fish Passage Improvement Investigation Page F-6
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
Figure 3 Plan View of Fish Ladder and Downstream Migrant Facilities Removal to Elevation 460
GEC Yuba River Fish Passage Improvement Investigation Page F-7
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
Figure 4 Plan View with Photograph Removal to Elevation 460
GEC Yuba River Fish Passage Improvement Investigation Page F-8
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
Figure 5 Plan View of Fish Ladder and Downstream Migrant Facilities Removal to Elevation 430
GEC Yuba River Fish Passage Improvement Investigation Page F-9
National Marine Fisheries Service Final Report April 2014 Appendix F Fish Ladders for Partial Removal of Englebright Dam
Figure 6 Plan View with Photograph Removal to Elevation 430
GEC Yuba River Fish Passage Improvement Investigation Page F-10
Gathard Engineering Consulting
APPENDIX G
Opinion of Probable Costs
Yuba River Fish Passage Improvement Investigation
National Marine Fisheries Service
National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs Appendix G
Opinion of Probable Costs
List of Tables
Table 1 Complete Removal of Englebright Dam ...... 4 Table 2 Complete Removal of Daguerre Point Dam ...... 5 Table 3 Upstream Diversion Dam and Fishway Bypass with Daguerre Point Dam Removal ...... 6 Table 4 Englebright Partial Removal to Elevation 460 ...... 7 Table 5 Ladder to Elevation - Englebright Partial Removal to 460 ...... 8 Table 6 Englebright Partial Removal to 430 ...... 9 Table 7 Ladder to Elevation - Englebright Partial Removal to 460 ...... 10 Table 8 Rock Ramp Fishway – at Unaltered Daguerre Dam ...... 11 Table 9 Full Width Weirs – at Unaltered Daguerre Dam ...... 12 Table 10 Full Height Tainter Gates at Daguerre Point Dam ...... 13
GEC Yuba River Fish Passage Improvement Investigation Page G-i National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Opinion of Probable Cost
The following cost opinions were developed based on conceptual level designs. These estimates are intended to be used for planning and comparison, but not for budgeting. Further development of concepts presented here would be required to develop them to a level required for budget purposes. Typically, further development will change the configuration of elements of a particular approach or by adding new elements and removing others.
Since the costs presented herein are the first assessment of the cost for each approach, a relatively large contingency, 45% of the total cost for the individual line items, was added to the assembled cost for the items listed for each element of the approach. Costs for individual activities that are common among construction projects such as excavation or hauling, were developed from historical information assembled and published in RSMeans, Heavy Construction Cost Data, 21st Annual Edition, 2007 (Means). Other costs, which are less common to most construction projects such as concrete demolition, blasting, and drilling, were developed based on conversations with contractors that have recently completed dam demolition activities at Elwha, Condit, and Glines Canyon dams, and from actual final bids presented for these projects.
Cost figures presented in the following tables are for the year 2013 even though schedules for construction activities are shown in 2015 through 2019. Inflation cost extensions reflecting future costs at the time of anticipated construction activities were considered too speculative. Since this is a conceptual study, addressing construction date would not be appropriate to the level of information available. Therefore, inflation is not included here. Furthermore, construction costs have varied greatly over the last five years and have not always increased as illustrated in Figure 1. As illustrated in Figure 1, the building cost index for 2007 is similar to 2012. Cost for individual items were taken from the 2007 edition of Means to reflect 2013 costs. The 2nd quarter Turner index currently is 8591, similar to the 2007 index.
The costs opinions shown below are considered to be a Class 5 level estimate by the AACE cost estimate classification, the initial level of project estimating. The following information describing the Class 5 estimates is reproduced from AACE International Recommended Practice No. 18R-97 Cost Estimate Classification System – As Applied In Engineering, Procurement, and Construction For The Process Industries
Description
Class 5 estimates are generally prepared based on very limited information, and subsequently have wide accuracy ranges. As such, some companies and organizations have elected to determine that due to the inherent inaccuracies, such estimates cannot be classified in a conventional and systemic manner. Class 5 estimates, due to the requirements of end use, may be prepared within a very limited amount of time
1 http://www.turnerconstruction.com/cost-index
GEC Yuba River Fish Passage Improvement Investigation Page G-1 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs and with little effort expended—sometimes requiring less than an hour to prepare. Often, little more than proposed plant type, location, and capacity are known at the time of estimate preparation.
Level of Project Definition Required:
0% to 2% of full project definition.
End Usage:
Class 5 estimates are prepared for any number of strategic business planning purposes, such as but not limited to market studies, assessment of initial viability, evaluation of alternate schemes, project screening, project location studies, evaluation of resource needs and budgeting, long-range capital planning, etc.
Estimating Methods Used:
Class 5 estimates virtually always use stochastic estimating methods such as cost/capacity curves and factors, scale of operations factors, Lang factors, Hand factors, Chilton factors, Peters-Timmerhaus factors, Guthrie factors, and other parametric and modeling techniques.
Expected Accuracy Range:
Typical accuracy ranges for Class 5 estimates are -20% to -50% on the low side, and +30% to +100% on the high side, depending on the technological complexity of the project, appropriate reference information, and the inclusion of an appropriate contingency determination. Ranges could exceed those shown in unusual circumstances.
Effort to Prepare (for US$20MM project):
As little as 1 hour or less to perhaps more than 200 hours, depending on the project and the estimating methodology used.
ANSI Standard Reference Z94.2-1989 Name:
Order of magnitude estimate (typically -30% to +50%).
Alternate Estimate Names, Terms, Expressions, Synonyms:
Ratio, ballpark, blue sky, seat-of-pants, ROM, idea study, prospect estimate, concession license estimate, guesstimate, rule-of-thumb
GEC Yuba River Fish Passage Improvement Investigation Page G-2 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Figure 1 Building Construction Cost Index and Inflation Rate2
2 Turner Building Cost Index, 2012 Fourth Quarter Forecast, Turner Construction Company
GEC Yuba River Fish Passage Improvement Investigation Page G-3 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 1 Complete Removal of Englebright Dam
Qty Unit Unit Cost Cost Mobilization 1 LS $2,000,000 $ 2,000,000 $2,350,000 Land for Stock Pile Sites 10 Acres $ 15,000 $ 150,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Water to Staging Areas 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 10 Acres $ 1,500 $ 15,000 $ 15,000 Upgrade Roads 4 Miles $150,000.00 $ 600,000 $ 600,000 New Haul Roads $2,725,000 Rock Excavation 15,000 CY $ 100 $1,500,000 Grading & Surfacing 3 Miles $ 75,000 $ 225,000 Upgrade Area Transport Roads 5 Miles $ 200,000 $1,000,000 Demolish Power Plants $2,102,000 Demolish Narrows 2 Intake Structures 1 LS $ 125,000 $ 125,000 Fill Narrows 2 Tunnel Ends Only 860 Cy $ 200 $ 372,000 Demo Narrows 1 Trashrack & Gate Well 1 LS $ 125,000 $ 125,000 Fill Narrows 1 Tunnel both Ends 400 Cy $ 200 $ 80,000 Remove Narrows 2 Powerhouse & Restore 1 LS $ 700,000 $ 700,000 Remove Narrows 1 Powerhouse &Restore Area 1 LS $ 700,000 $ 700,000 Tunnel Construction $ 472,400 Construct Downstream Cofferdam 560 CY $ 75 $ 42,000 Drill, Blast, & Muckout Tunnels 1000 CY $ 200 $ 200,000 Dewater Tunnel Construction Area 1 LS $ 75,000 $ 75,000 Blast out Final Section 1 LS $ 100,000 $ 100,000 Load Material 1000 CY $ 10 $ 10,000 Transport Material to Stock Pile 1000 CY $ 10 $ 10,000 Separate and Load Material 1000 CY $ 15 $ 15,000 Transport Material to Salvage Site 1000 CY $ 20 $ 20,000 Demolish Dam $26,250,000 Demolish Concrete 250000 CY $ 50.00 $12,500,000 Load Material 250000 CY $ 10.00 $2,500,000 Transport Material to Stock Pile 250000 CY $ 10.00 $2,500,000 Separate and Load Material 250000 CY $ 15.00 $3,750,000 Transport Material to Salvage Site 250000 CY $ 20.00 $5,000,000 Upstream Grading 400 Acres $ 1,500.00 $ 600,000 $ 600,000 Re-Vegetation 600 Acres $ 3,500.00 $2,100,000 $ 2,100,000 Subtotal $37,214,000 Contingencies 45% $16,746,300 Subtotal $53,960,300 Permitting, Engineering, & Construction Management 30% $16,188,090 Total $70,148,390
GEC Yuba River Fish Passage Improvement Investigation Page G-4 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 2 Complete Removal of Daguerre Point Dam
Daguerre Point Dam Removal Item Quantity Unit Unit Cost Cost Total Mobilization 1 LS $ 1,500,000 $ 200,000 $ 300,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 5 Acres $ 15,000 $ 75,000 $ 75,000 Upgrade Roads 2 Miles $150,000.00 $ 300,000 $ 300,000 Breach Section $ 687,750 Construct Upstream Cofferdam 9000 SF $ 21.00 $ 189,000 Construct Downstream Cofferdam 350 CY $ 75.00 $ 26,250 Demolish 100' of Southern Section of Dam 4500 CY $ 50.00 $ 225,000 Load Material 4500 CY $ 10.00 $ 45,000 Transport Material to Stock Pile 4500 CY $ 10.00 $ 45,000 Separate and Load Material 4500 CY $ 15.00 $ 67,500 Transport Material to Salvage Site 4500 CY $ 20.00 $ 90,000 Remove Northern Portion of Dam $3,504,450 Construct Upstream Cofferdam 22000 SF $ 21.00 $ 462,000 Construct Downstream Cofferdam 2130 CY $ 75.00 $ 159,750 Demolish 475' of Northern Section of Dam 23500 CY $ 50.00 $1,175,000 Load Material 23500 CY $ 10.00 $ 235,000 Transport Material to Stock Pile 23500 CY $ 10.00 $ 235,000 Separate and Load Material 23500 CY $ 15.00 $ 352,500 Transport Material to Salvage Site 23500 CY $ 20.00 $ 470,000 Construct Ramp 1500 CY $ 50.00 $ 75,000 Extend Ramp 5000 CY $ 51.00 $ 255,000 Remove Cofferdams 2130 LS $ 40.00 $ 85,200 Subtotal $4,567,200 Contingencies 45% $2,055,240 Subtotal $6,622,440 Permitting, Engineering, & Construction Management 30% $1,986,732
Total $8,609,172
GEC Yuba River Fish Passage Improvement Investigation Page G-5 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 3 Upstream Diversion Dam and Fishway Bypass with Daguerre Point Dam Removal
Item Quantity Unit Unit Cost Cost Total Mobilization 1 LS $ 1,500,000 $ 1,500,000 Canal $ 4,805,556 Long Canal 370,370 CY $ 3.26 $ 1,207,407 Grade 111,111 SY $ 1.00 $ 111,111 Geotech Liner 111,111 SY $ 13.95 $ 1,550,000 Compactable Surfacing 37,037 CY $ 25.00 $ 925,926 Compaction 111,111 SY $ 1.00 $ 111,111 Dewater 10,000 LF $ 90.00 $ 900,000 Fish Screens $ 2,360,000 Construction 1 LS $ 2,000,000 $ 2,000,000 Operation 36 Months $ 10,000 $ 360,000 Temporary Diversion Water Supply $ 2,092,500 Well Points 15,000 LF $ 91.50 $ 1,372,500 Operation 36 Months $ 20,000 $ 720,000 Pipe $ 8,125,600 Excavation & Backfill 29,490 LF $ 40.00 $ 1,179,600 Bedding 29,490 LF $ 25.00 $ 737,250 Temporary River Diversion 2 EA $ 50,000.00 $ 100,000 Cofferdam River Xing 40,000 SF $ 21.00 $ 840,000 Dewater 1,200 LF $ 90.00 $ 108,000 5 foot dia HPDE Pipe 29,490 LF $ 175.00 $ 5,160,750 Head Boxes $ 389,600 Excavation & Backfill 460 CY $ 10.00 $ 4,600 Concrete 90 CY $ 1,500.00 $ 135,000 Controls 1 LS $250,000.00 $ 250,000 Diversion Dam & By Pass $ 4,057,950 Excavation 1 LS $ 5,000 $ 5,000 Temporary Stream Diversion 1 LS $ 5,000 $ 5,000 Rock Dam 7,410 CY $ 100 $ 741,000 Rock for Ramps 23,000 CY $ 50 $ 1,150,000 Debris Screens 1,000 SF $ 50 $ 50,000 Grade Control 1,860 CY $ 750 $ 1,395,000 Guide Walls 420 CY $ 750 $ 315,000 Gates 20,390 LB $ 5.00 $ 101,950 Concrete 170 CY $ 1,500.00 $ 255,000 Piping 400 LF $ 100.00 $ 40,000 Upgrades at Diversion Inputs $ 300,000 New Gates and Controls 3 EA $ 100,000 $ 300,000 Subtotal $ 23,631,206 Contingencies 45% $ 10,634,043 Permitting, Engineering, & Construction Management 30% $ 10,279,574 Total $ 44,544,822
GEC Yuba River Fish Passage Improvement Investigation Page G-6 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 4 Englebright Partial Removal to Elevation 460
Englebright Dam Removal to Elevation 460 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,850,000 Land for Stock Pile Sites 10 Acres $ 15,000 $ 150,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Water to Staging Areas 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 10 Acres $ 1,500 $ 15,000 $ 15,000 Upgrade Roads 4 Miles $150,000.00 $ 600,000 $ 600,000 New Haul Roads $ 2,325,000 Rock Excavation 11,000 CY $ 100 $ 1,100,000 Grading & Surfacing 3 Miles $ 75,000 $ 225,000 Upgrade Area Transport Roads 5 Miles $ 200,000 $ 1,000,000 Extend Intake Structure $ 302,000 Construct Cofferdam 560 CY $ 75 $ 42,000 Concrete Pipe - LF $ 202,500 $ - Concrete Intake Structure 100 CY $ 2,000 $ 200,000 Intake Structure Screens 600 SF $ 100 $ 60,000 Demolish Dam $ 6,300,000 Demolish Concrete 60,000 CY $ 50.00 $ 3,000,000 Load Material 60,000 CY $ 10.00 $ 600,000 Transport Material to Stock Pile 60,000 CY $ 10.00 $ 600,000 Separate and Load Material 60,000 CY $ 15.00 $ 900,000 Transport Material to Salvage Site 60,000 CY $ 20.00 $ 1,200,000 Subtotal $12,392,000 Contingencies 45% $ 5,576,400 Subtotal $17,968,400 Permitting, Engineering, & Construction Management 30% $ 5,390,520 Total $23,358,920
GEC Yuba River Fish Passage Improvement Investigation Page G-7 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 5 Ladder to Elevation - Englebright Partial Removal to 460
Fish Ladder to Elevation 460 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,680,000 Land for Stock Pile Sites 2 Acres $ 15,000 $ 30,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Rock Demolition $ 3,365,500 Rock Excavation 20,800 CY $ 100 $ 2,080,000 Load Material 20,800 CY $ 50 $ 1,040,000 Transport Material to Stock Pile 20,800 CY $ 10 $ 208,000 Grading & Surfacing 1 Miles $ 75,000 $ 37,500 Construct Fishway $ 4,837,900 Formwork 41,600 SF $ 13 $ 520,000 Concrete 3,430 CY $ 530 $ 1,817,900 Entrance 1 LS $ 1,500,000 $ 1,500,000 Controls 1 LS $ 1,000,000 $ 1,000,000 Multiuse Facility $ 3,713,056 Building 3500 sf $ 500 $ 1,750,000 Rock Excavation, Hauling, etc 2,222 CY $ 160 $ 355,556 Paving 3750 SF $ 2 $ 7,500 Retaining Wall 300 CY $ 1,500 $ 450,000 Holding Pens 100 CY $ 1,500 $ 150,000 Utilities 1 LS $ 250,000 $ 250,000 Appurtenances 1 LS $ 750,000 $ 750,000 Auxiliary Water Supply 1 LS $ 5,000,000 $ 5,000,000 $ 5,000,000 Subtotal $19,596,456 Contingencies 45% $ 8,818,405 Subtotal $28,414,861 Permitting, Engineering, & Construction Management 30% $ 8,524,458
Total $36,939,319
GEC Yuba River Fish Passage Improvement Investigation Page G-8 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 6 Englebright Partial Removal to 430
Englebright Dam Removal to Elevation 430 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,850,000 Land for Stock Pile Sites 10 Acres $ 15,000 $ 150,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Water to Staging Areas 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 10 Acres $ 1,500 $ 15,000 $ 15,000 Upgrade Roads 4 Miles $150,000.00 $ 600,000 $ 600,000 New Haul Roads $ 2,325,000 Rock Excavation 11,000 CY $ 100 $ 1,100,000 Grading & Surfacing 3 Miles $ 75,000 $ 225,000 Upgrade Area Transport Roads 5 Miles $ 200,000 $ 1,000,000 Extend Intake Structure $ 1,502,000 Construct Cofferdam 560 CY $ 75 $ 42,000 Concrete Intake Structure 100 CY $ 2,000 $ 200,000 Excavate Tunnel 240 LF $ 5,000 $ 1,200,000 Intake Structure Screens 600 SF $ 100 $ 60,000 Demolish Dam $ 9,450,000 Demolish Concrete 90,000 CY $ 50.00 $ 4,500,000 Load Material 90,000 CY $ 10.00 $ 900,000 Transport Material to Stock Pile 90,000 CY $ 10.00 $ 900,000 Separate and Load Material 90,000 CY $ 15.00 $ 1,350,000 Transport Material to Salvage Site 90,000 CY $ 20.00 $ 1,800,000 Subtotal $16,742,000 Contingencies 45% $ 7,533,900 Subtotal $24,275,900 Permitting, Engineering, & Construction Management 30% $ 7,282,770 Total $31,558,670
GEC Yuba River Fish Passage Improvement Investigation Page G-9 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 7 Ladder to Elevation - Englebright Partial Removal to 460
Fishway Cost - Dam Removal to Elevation 430 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,680,000 Land for Stock Pile Sites 2 Acres $ 15,000 $ 30,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Rock Demolition $ 2,021,500 Rock Excavation 12,400 CY $ 100 $ 1,240,000 Load Material 12,400 CY $ 50 $ 620,000 Transport Material to Stock Pile 12,400 CY $ 10 $ 124,000 Grading & Surfacing 1 Miles $ 75,000 $ 37,500 Construct Fishway $ 3,896,500 Formwork 24,800 SF $ 13 $ 310,000 Concrete 2,050 CY $ 530 $ 1,086,500 Entrance 1 LS $ 1,500,000 $ 1,500,000 Controls 1 LS $ 1,000,000 $ 1,000,000 Multiuse Facility $ 3,713,056 Building 3500 SF $ 500 $ 1,750,000 Rock Excavation, Hauling, etc 2,222 CY $ 160 $ 355,556 Paving 3750 SF $ 2 $ 7,500 Retaining Wall 300 CY $ 1,500 $ 450,000 Holding Pens 100 CY $ 1,500 $ 150,000 Utilities 1 LS $ 250,000 $ 250,000 Appurtenances 1 LS $ 750,000 $ 750,000 Auxiliary Water Supply 1 LS $ 5,000,000 $ 5,000,000 $ 5,000,000 Subtotal $17,311,056 Contingencies 45% $ 7,789,975 Subtotal $25,101,031 Permitting, Engineering, & Construction Management 30% $ 7,312,809
Total $32,631,340
GEC Yuba River Fish Passage Improvement Investigation Page G-10 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 8 Rock Ramp Fishway – at Unaltered Daguerre Dam
Rock Ramp Fishway Downstream of Daguerre Point Dam Item Quantity Unit Unit Cost Item Cost Total Mobilization $ 800,000 Ramp Construction $ 7,396,750 Load Material 100,000 CY $ 3.00 $ 300,000 Haul Material 100,000 CY $ 5.00 $ 500,000 Grade Material 100,000 CY $ 2.00 $ 200,000 Compaction 100,000 CY $ 1.50 $ 150,000 3/4" Base Course 12" Deep 25,000 SY $ 16.00 $ 400,000 Geotech Liner 25,000 SY $ 13.95 $ 348,750 River Rock 15,000 Tons $ 150.00 $2,250,000 Rip Rap 33,300 CY $ 60.00 $1,998,000 Grouting 25,000 SY $ 50.00 $1,250,000 Grade Control Construction $ 959,000 Temporary River Diversion 2 EA $ 50,000 $ 100,000 Cofferdam River Xing 5,000 SF $ 21.00 $ 105,000 Dewater 800 LF $ 90.00 $ 72,000 Excavation 4400 CY $ 5.00 $ 22,000 Formwork 19200 SF $ 12.50 $ 240,000 Concrete 1400 CY $ 300.00 $ 420,000 Roller Gate $ 410,000 Steel 15,000 lbs $ 10.00 $ 150,000 Concrete Excavation 20 CY $ 500.00 $ 10,000 Controls 1 LS $250,000.00 $ 250,000 Subtotal $ 9,565,750 Contingencies 45% $ 4,304,588 Subtotal $13,870,338 Permitting, Engineering, & Construction Management 30% $ 4,161,101
Total $18,031,439
GEC Yuba River Fish Passage Improvement Investigation Page G-11 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 9 Full Width Weirs – at Unaltered Daguerre Dam
Full Width Weirs downstream of Daguerre Point Dam Item Quantity Unit Unit Cost Item Cost Total Mobilization $ 800,000 Ramp Construction Phase 1 $ 5,891,800 Load Material 185,200 CY $ 2.00 $ 370,400 Haul Material 185,200 CY $ 4.00 $ 740,800 Grade Material 185,200 CY $ 2.00 $ 370,400 Compaction 185,200 CY $ 1.00 $ 185,200 River Rock 77,800 CY $ 50.00 $3,890,000 Rip Rap 6,700 CY $ 50.00 $ 335,000 Grade Control Construction $11,652,500 Temporary River Diversion 2 EA $ 50,000 $ 100,000 Temporary Longitudinal Wall 1,200 Tons $ 1,750.00 $2,100,000 Transverse Sheet Piling 2,900 Tons $ 2,000.00 $5,800,000 Formwork 105000 SF $ 12.50 $1,312,500 Concrete 7800 CY $ 300.00 $2,340,000 Ramp Construction Phase 2 $ 6,077,000 Load Material 185,200 CY $ 2.00 $ 370,400 Haul Material 185,200 CY $ 5.00 $ 926,000 Grade Material 185,200 CY $ 2.00 $ 370,400 Compaction 185,200 CY $ 1.00 $ 185,200 River Rock 77,800 CY $ 50.00 $3,890,000 Rip Rap 6,700 CY $ 50.00 $ 335,000 Grade Control Construction $ 9,577,500 Temporary River Diversion 2 EA $ 50,000 $ 100,000 Remove Temporary Longitudinal Wall 1 LS $ 25,000.00 $ 25,000 Transverse Sheet Piling 2,900 Tons $ 2,000.00 $5,800,000 Formwork 105000 SF $ 12.50 $1,312,500 Concrete 7800 CY $ 300.00 $2,340,000 Subtotal $33,998,800 Contingencies 45% $15,299,460 Subtotal $49,298,260 Permitting, Engineering, & Construction Management 30% $14,789,478
Total $64,087,738
GEC Yuba River Fish Passage Improvement Investigation Page G-12 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 10 Full Height Tainter Gates at Daguerre Point Dam
Opinion of Probable Cost for Radial Gate Approach Item Quantity Unit Unit Cost Item Cost Mobilization and Demobilization 1 LS $1,545,000 $1,545,000 Construct Gates $9,414,917 Rent Sheet Piles 240 ton $220 $52,800 Construct and Remove D/S Cofferdam 6,500 CY $75 $487,500 Pumping 400 days $773 $309,000 Drive and Remove Temporary Sheet Piles 240 ton $1,133 $271,920 Excavate behind Dam 4,630 CY $10 $47,689 Demolish Concrete 7,250 CY $100 $725,000 Collect and Haul Concrete 7,975 CY $50 $398,750 Concrete Formwork 38,400 SF $10 $395,520 Concrete in Place 3,960 CY $250 $990,000 Concrete Reinforcing Steel 523,908 lbs $1.55 $809,438 Gates and Appurtenances 4,600 SF $361 $1,658,300 Reinforced Concrete Slab 370 CY $350 $129,500 Top of Structure Access Bridge Superstructure 4,500 SF $100 $450,000 Access Bridge Piers 11 Ea $12,000 $132,000 Hoist and Associated Equipment 10 EA $200,000 $2,000,000 3 Phase Power to Site 1 LS $300,000 $300,000 Automation 1 LS $257,500 $257,500 Subtotal $10,959,917 Contingencies 45% $4,931,963 Subtotal $15,891,879 Permitting, Engineering, & Construction Management 30% $4,767,564
Total $20,659,443
GEC Yuba River Fish Passage Improvement Investigation Page G-13 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
GEC Yuba River Fish Passage Improvement Investigation Page G-14
Gathard Engineering Consulting
APPENDIX G
Opinion of Probable Costs
Yuba River Fish Passage Improvement Investigation
National Marine Fisheries Service
National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs Appendix G
Opinion of Probable Costs
List of Tables
Table 1 Complete Removal of Englebright Dam ...... 4 Table 2 Complete Removal of Daguerre Point Dam ...... 5 Table 3 Upstream Diversion Dam and Fishway Bypass with Daguerre Point Dam Removal ...... 6 Table 4 Englebright Partial Removal to Elevation 460 ...... 7 Table 5 Ladder to Elevation - Englebright Partial Removal to 460 ...... 8 Table 6 Englebright Partial Removal to 430 ...... 9 Table 7 Ladder to Elevation - Englebright Partial Removal to 460 ...... 10 Table 8 Rock Ramp Fishway – at Unaltered Daguerre Dam ...... 11 Table 9 Full Width Weirs – at Unaltered Daguerre Dam ...... 12 Table 10 Full Height Tainter Gates at Daguerre Point Dam ...... 13
GEC Yuba River Fish Passage Improvement Investigation Page G-i National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Opinion of Probable Cost
The following cost opinions were developed based on conceptual level designs. These estimates are intended to be used for planning and comparison, but not for budgeting. Further development of concepts presented here would be required to develop them to a level required for budget purposes. Typically, further development will change the configuration of elements of a particular approach or by adding new elements and removing others.
Since the costs presented herein are the first assessment of the cost for each approach, a relatively large contingency, 45% of the total cost for the individual line items, was added to the assembled cost for the items listed for each element of the approach. Costs for individual activities that are common among construction projects such as excavation or hauling, were developed from historical information assembled and published in RSMeans, Heavy Construction Cost Data, 21st Annual Edition, 2007 (Means). Other costs, which are less common to most construction projects such as concrete demolition, blasting, and drilling, were developed based on conversations with contractors that have recently completed dam demolition activities at Elwha, Condit, and Glines Canyon dams, and from actual final bids presented for these projects.
Cost figures presented in the following tables are for the year 2013 even though schedules for construction activities are shown in 2015 through 2019. Inflation cost extensions reflecting future costs at the time of anticipated construction activities were considered too speculative. Since this is a conceptual study, addressing construction date would not be appropriate to the level of information available. Therefore, inflation is not included here. Furthermore, construction costs have varied greatly over the last five years and have not always increased as illustrated in Figure 1. As illustrated in Figure 1, the building cost index for 2007 is similar to 2012. Cost for individual items were taken from the 2007 edition of Means to reflect 2013 costs. The 2nd quarter Turner index currently is 8591, similar to the 2007 index.
The costs opinions shown below are considered to be a Class 5 level estimate by the AACE cost estimate classification, the initial level of project estimating. The following information describing the Class 5 estimates is reproduced from AACE International Recommended Practice No. 18R-97 Cost Estimate Classification System – As Applied In Engineering, Procurement, and Construction For The Process Industries
Description
Class 5 estimates are generally prepared based on very limited information, and subsequently have wide accuracy ranges. As such, some companies and organizations have elected to determine that due to the inherent inaccuracies, such estimates cannot be classified in a conventional and systemic manner. Class 5 estimates, due to the requirements of end use, may be prepared within a very limited amount of time
1 http://www.turnerconstruction.com/cost-index
GEC Yuba River Fish Passage Improvement Investigation Page G-1 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs and with little effort expended—sometimes requiring less than an hour to prepare. Often, little more than proposed plant type, location, and capacity are known at the time of estimate preparation.
Level of Project Definition Required:
0% to 2% of full project definition.
End Usage:
Class 5 estimates are prepared for any number of strategic business planning purposes, such as but not limited to market studies, assessment of initial viability, evaluation of alternate schemes, project screening, project location studies, evaluation of resource needs and budgeting, long-range capital planning, etc.
Estimating Methods Used:
Class 5 estimates virtually always use stochastic estimating methods such as cost/capacity curves and factors, scale of operations factors, Lang factors, Hand factors, Chilton factors, Peters-Timmerhaus factors, Guthrie factors, and other parametric and modeling techniques.
Expected Accuracy Range:
Typical accuracy ranges for Class 5 estimates are -20% to -50% on the low side, and +30% to +100% on the high side, depending on the technological complexity of the project, appropriate reference information, and the inclusion of an appropriate contingency determination. Ranges could exceed those shown in unusual circumstances.
Effort to Prepare (for US$20MM project):
As little as 1 hour or less to perhaps more than 200 hours, depending on the project and the estimating methodology used.
ANSI Standard Reference Z94.2-1989 Name:
Order of magnitude estimate (typically -30% to +50%).
Alternate Estimate Names, Terms, Expressions, Synonyms:
Ratio, ballpark, blue sky, seat-of-pants, ROM, idea study, prospect estimate, concession license estimate, guesstimate, rule-of-thumb
GEC Yuba River Fish Passage Improvement Investigation Page G-2 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Figure 1 Building Construction Cost Index and Inflation Rate2
2 Turner Building Cost Index, 2012 Fourth Quarter Forecast, Turner Construction Company
GEC Yuba River Fish Passage Improvement Investigation Page G-3 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 1 Complete Removal of Englebright Dam
Qty Unit Unit Cost Cost Mobilization 1 LS $2,000,000 $ 2,000,000 $2,350,000 Land for Stock Pile Sites 10 Acres $ 15,000 $ 150,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Water to Staging Areas 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 10 Acres $ 1,500 $ 15,000 $ 15,000 Upgrade Roads 4 Miles $150,000.00 $ 600,000 $ 600,000 New Haul Roads $2,725,000 Rock Excavation 15,000 CY $ 100 $1,500,000 Grading & Surfacing 3 Miles $ 75,000 $ 225,000 Upgrade Area Transport Roads 5 Miles $ 200,000 $1,000,000 Demolish Power Plants $2,102,000 Demolish Narrows 2 Intake Structures 1 LS $ 125,000 $ 125,000 Fill Narrows 2 Tunnel Ends Only 860 Cy $ 200 $ 372,000 Demo Narrows 1 Trashrack & Gate Well 1 LS $ 125,000 $ 125,000 Fill Narrows 1 Tunnel both Ends 400 Cy $ 200 $ 80,000 Remove Narrows 2 Powerhouse & Restore 1 LS $ 700,000 $ 700,000 Remove Narrows 1 Powerhouse &Restore Area 1 LS $ 700,000 $ 700,000 Tunnel Construction $ 472,400 Construct Downstream Cofferdam 560 CY $ 75 $ 42,000 Drill, Blast, & Muckout Tunnels 1000 CY $ 200 $ 200,000 Dewater Tunnel Construction Area 1 LS $ 75,000 $ 75,000 Blast out Final Section 1 LS $ 100,000 $ 100,000 Load Material 1000 CY $ 10 $ 10,000 Transport Material to Stock Pile 1000 CY $ 10 $ 10,000 Separate and Load Material 1000 CY $ 15 $ 15,000 Transport Material to Salvage Site 1000 CY $ 20 $ 20,000 Demolish Dam $26,250,000 Demolish Concrete 250000 CY $ 50.00 $12,500,000 Load Material 250000 CY $ 10.00 $2,500,000 Transport Material to Stock Pile 250000 CY $ 10.00 $2,500,000 Separate and Load Material 250000 CY $ 15.00 $3,750,000 Transport Material to Salvage Site 250000 CY $ 20.00 $5,000,000 Upstream Grading 400 Acres $ 1,500.00 $ 600,000 $ 600,000 Re-Vegetation 600 Acres $ 3,500.00 $2,100,000 $ 2,100,000 Subtotal $37,214,000 Contingencies 45% $16,746,300 Subtotal $53,960,300 Permitting, Engineering, & Construction Management 30% $16,188,090 Total $70,148,390
GEC Yuba River Fish Passage Improvement Investigation Page G-4 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 2 Complete Removal of Daguerre Point Dam
Daguerre Point Dam Removal Item Quantity Unit Unit Cost Cost Total Mobilization 1 LS $ 1,500,000 $ 200,000 $ 300,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 5 Acres $ 15,000 $ 75,000 $ 75,000 Upgrade Roads 2 Miles $150,000.00 $ 300,000 $ 300,000 Breach Section $ 687,750 Construct Upstream Cofferdam 9000 SF $ 21.00 $ 189,000 Construct Downstream Cofferdam 350 CY $ 75.00 $ 26,250 Demolish 100' of Southern Section of Dam 4500 CY $ 50.00 $ 225,000 Load Material 4500 CY $ 10.00 $ 45,000 Transport Material to Stock Pile 4500 CY $ 10.00 $ 45,000 Separate and Load Material 4500 CY $ 15.00 $ 67,500 Transport Material to Salvage Site 4500 CY $ 20.00 $ 90,000 Remove Northern Portion of Dam $3,504,450 Construct Upstream Cofferdam 22000 SF $ 21.00 $ 462,000 Construct Downstream Cofferdam 2130 CY $ 75.00 $ 159,750 Demolish 475' of Northern Section of Dam 23500 CY $ 50.00 $1,175,000 Load Material 23500 CY $ 10.00 $ 235,000 Transport Material to Stock Pile 23500 CY $ 10.00 $ 235,000 Separate and Load Material 23500 CY $ 15.00 $ 352,500 Transport Material to Salvage Site 23500 CY $ 20.00 $ 470,000 Construct Ramp 1500 CY $ 50.00 $ 75,000 Extend Ramp 5000 CY $ 51.00 $ 255,000 Remove Cofferdams 2130 LS $ 40.00 $ 85,200 Subtotal $4,567,200 Contingencies 45% $2,055,240 Subtotal $6,622,440 Permitting, Engineering, & Construction Management 30% $1,986,732
Total $8,609,172
GEC Yuba River Fish Passage Improvement Investigation Page G-5 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 3 Upstream Diversion Dam and Fishway Bypass with Daguerre Point Dam Removal
Item Quantity Unit Unit Cost Cost Total Mobilization 1 LS $ 1,500,000 $ 1,500,000 Canal $ 4,805,556 Long Canal 370,370 CY $ 3.26 $ 1,207,407 Grade 111,111 SY $ 1.00 $ 111,111 Geotech Liner 111,111 SY $ 13.95 $ 1,550,000 Compactable Surfacing 37,037 CY $ 25.00 $ 925,926 Compaction 111,111 SY $ 1.00 $ 111,111 Dewater 10,000 LF $ 90.00 $ 900,000 Fish Screens $ 2,360,000 Construction 1 LS $ 2,000,000 $ 2,000,000 Operation 36 Months $ 10,000 $ 360,000 Temporary Diversion Water Supply $ 2,092,500 Well Points 15,000 LF $ 91.50 $ 1,372,500 Operation 36 Months $ 20,000 $ 720,000 Pipe $ 8,125,600 Excavation & Backfill 29,490 LF $ 40.00 $ 1,179,600 Bedding 29,490 LF $ 25.00 $ 737,250 Temporary River Diversion 2 EA $ 50,000.00 $ 100,000 Cofferdam River Xing 40,000 SF $ 21.00 $ 840,000 Dewater 1,200 LF $ 90.00 $ 108,000 5 foot dia HPDE Pipe 29,490 LF $ 175.00 $ 5,160,750 Head Boxes $ 389,600 Excavation & Backfill 460 CY $ 10.00 $ 4,600 Concrete 90 CY $ 1,500.00 $ 135,000 Controls 1 LS $250,000.00 $ 250,000 Diversion Dam & By Pass $ 4,057,950 Excavation 1 LS $ 5,000 $ 5,000 Temporary Stream Diversion 1 LS $ 5,000 $ 5,000 Rock Dam 7,410 CY $ 100 $ 741,000 Rock for Ramps 23,000 CY $ 50 $ 1,150,000 Debris Screens 1,000 SF $ 50 $ 50,000 Grade Control 1,860 CY $ 750 $ 1,395,000 Guide Walls 420 CY $ 750 $ 315,000 Gates 20,390 LB $ 5.00 $ 101,950 Concrete 170 CY $ 1,500.00 $ 255,000 Piping 400 LF $ 100.00 $ 40,000 Upgrades at Diversion Inputs $ 300,000 New Gates and Controls 3 EA $ 100,000 $ 300,000 Subtotal $ 23,631,206 Contingencies 45% $ 10,634,043 Permitting, Engineering, & Construction Management 30% $ 10,279,574 Total $ 44,544,822
GEC Yuba River Fish Passage Improvement Investigation Page G-6 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 4 Englebright Partial Removal to Elevation 460
Englebright Dam Removal to Elevation 460 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,850,000 Land for Stock Pile Sites 10 Acres $ 15,000 $ 150,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Water to Staging Areas 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 10 Acres $ 1,500 $ 15,000 $ 15,000 Upgrade Roads 4 Miles $150,000.00 $ 600,000 $ 600,000 New Haul Roads $ 2,325,000 Rock Excavation 11,000 CY $ 100 $ 1,100,000 Grading & Surfacing 3 Miles $ 75,000 $ 225,000 Upgrade Area Transport Roads 5 Miles $ 200,000 $ 1,000,000 Extend Intake Structure $ 302,000 Construct Cofferdam 560 CY $ 75 $ 42,000 Concrete Pipe - LF $ 202,500 $ - Concrete Intake Structure 100 CY $ 2,000 $ 200,000 Intake Structure Screens 600 SF $ 100 $ 60,000 Demolish Dam $ 6,300,000 Demolish Concrete 60,000 CY $ 50.00 $ 3,000,000 Load Material 60,000 CY $ 10.00 $ 600,000 Transport Material to Stock Pile 60,000 CY $ 10.00 $ 600,000 Separate and Load Material 60,000 CY $ 15.00 $ 900,000 Transport Material to Salvage Site 60,000 CY $ 20.00 $ 1,200,000 Subtotal $12,392,000 Contingencies 45% $ 5,576,400 Subtotal $17,968,400 Permitting, Engineering, & Construction Management 30% $ 5,390,520 Total $23,358,920
GEC Yuba River Fish Passage Improvement Investigation Page G-7 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 5 Ladder to Elevation - Englebright Partial Removal to 460
Fish Ladder to Elevation 460 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,680,000 Land for Stock Pile Sites 2 Acres $ 15,000 $ 30,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Rock Demolition $ 3,365,500 Rock Excavation 20,800 CY $ 100 $ 2,080,000 Load Material 20,800 CY $ 50 $ 1,040,000 Transport Material to Stock Pile 20,800 CY $ 10 $ 208,000 Grading & Surfacing 1 Miles $ 75,000 $ 37,500 Construct Fishway $ 4,837,900 Formwork 41,600 SF $ 13 $ 520,000 Concrete 3,430 CY $ 530 $ 1,817,900 Entrance 1 LS $ 1,500,000 $ 1,500,000 Controls 1 LS $ 1,000,000 $ 1,000,000 Multiuse Facility $ 3,713,056 Building 3500 sf $ 500 $ 1,750,000 Rock Excavation, Hauling, etc 2,222 CY $ 160 $ 355,556 Paving 3750 SF $ 2 $ 7,500 Retaining Wall 300 CY $ 1,500 $ 450,000 Holding Pens 100 CY $ 1,500 $ 150,000 Utilities 1 LS $ 250,000 $ 250,000 Appurtenances 1 LS $ 750,000 $ 750,000 Auxiliary Water Supply 1 LS $ 5,000,000 $ 5,000,000 $ 5,000,000 Subtotal $19,596,456 Contingencies 45% $ 8,818,405 Subtotal $28,414,861 Permitting, Engineering, & Construction Management 30% $ 8,524,458
Total $36,939,319
GEC Yuba River Fish Passage Improvement Investigation Page G-8 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 6 Englebright Partial Removal to 430
Englebright Dam Removal to Elevation 430 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,850,000 Land for Stock Pile Sites 10 Acres $ 15,000 $ 150,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Water to Staging Areas 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Clear and Grub Stock Piles 10 Acres $ 1,500 $ 15,000 $ 15,000 Upgrade Roads 4 Miles $150,000.00 $ 600,000 $ 600,000 New Haul Roads $ 2,325,000 Rock Excavation 11,000 CY $ 100 $ 1,100,000 Grading & Surfacing 3 Miles $ 75,000 $ 225,000 Upgrade Area Transport Roads 5 Miles $ 200,000 $ 1,000,000 Extend Intake Structure $ 1,502,000 Construct Cofferdam 560 CY $ 75 $ 42,000 Concrete Intake Structure 100 CY $ 2,000 $ 200,000 Excavate Tunnel 240 LF $ 5,000 $ 1,200,000 Intake Structure Screens 600 SF $ 100 $ 60,000 Demolish Dam $ 9,450,000 Demolish Concrete 90,000 CY $ 50.00 $ 4,500,000 Load Material 90,000 CY $ 10.00 $ 900,000 Transport Material to Stock Pile 90,000 CY $ 10.00 $ 900,000 Separate and Load Material 90,000 CY $ 15.00 $ 1,350,000 Transport Material to Salvage Site 90,000 CY $ 20.00 $ 1,800,000 Subtotal $16,742,000 Contingencies 45% $ 7,533,900 Subtotal $24,275,900 Permitting, Engineering, & Construction Management 30% $ 7,282,770 Total $31,558,670
GEC Yuba River Fish Passage Improvement Investigation Page G-9 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 7 Ladder to Elevation - Englebright Partial Removal to 460
Fishway Cost - Dam Removal to Elevation 430 Qty Unit Unit Cost Cost Mobilization 1 LS $ 2,500,000 $ 2,500,000 $ 2,680,000 Land for Stock Pile Sites 2 Acres $ 15,000 $ 30,000 Power to Contractor 1 L.S. $ 50,000 $ 50,000 Power to Staging Area 1 L.S. $ 50,000 $ 50,000 Other Utilities 1 L.S. $ 50,000 $ 50,000 Rock Demolition $ 2,021,500 Rock Excavation 12,400 CY $ 100 $ 1,240,000 Load Material 12,400 CY $ 50 $ 620,000 Transport Material to Stock Pile 12,400 CY $ 10 $ 124,000 Grading & Surfacing 1 Miles $ 75,000 $ 37,500 Construct Fishway $ 3,896,500 Formwork 24,800 SF $ 13 $ 310,000 Concrete 2,050 CY $ 530 $ 1,086,500 Entrance 1 LS $ 1,500,000 $ 1,500,000 Controls 1 LS $ 1,000,000 $ 1,000,000 Multiuse Facility $ 3,713,056 Building 3500 SF $ 500 $ 1,750,000 Rock Excavation, Hauling, etc 2,222 CY $ 160 $ 355,556 Paving 3750 SF $ 2 $ 7,500 Retaining Wall 300 CY $ 1,500 $ 450,000 Holding Pens 100 CY $ 1,500 $ 150,000 Utilities 1 LS $ 250,000 $ 250,000 Appurtenances 1 LS $ 750,000 $ 750,000 Auxiliary Water Supply 1 LS $ 5,000,000 $ 5,000,000 $ 5,000,000 Subtotal $17,311,056 Contingencies 45% $ 7,789,975 Subtotal $25,101,031 Permitting, Engineering, & Construction Management 30% $ 7,312,809
Total $32,631,340
GEC Yuba River Fish Passage Improvement Investigation Page G-10 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 8 Rock Ramp Fishway – at Unaltered Daguerre Dam
Rock Ramp Fishway Downstream of Daguerre Point Dam Item Quantity Unit Unit Cost Item Cost Total Mobilization $ 800,000 Ramp Construction $ 7,396,750 Load Material 100,000 CY $ 3.00 $ 300,000 Haul Material 100,000 CY $ 5.00 $ 500,000 Grade Material 100,000 CY $ 2.00 $ 200,000 Compaction 100,000 CY $ 1.50 $ 150,000 3/4" Base Course 12" Deep 25,000 SY $ 16.00 $ 400,000 Geotech Liner 25,000 SY $ 13.95 $ 348,750 River Rock 15,000 Tons $ 150.00 $2,250,000 Rip Rap 33,300 CY $ 60.00 $1,998,000 Grouting 25,000 SY $ 50.00 $1,250,000 Grade Control Construction $ 959,000 Temporary River Diversion 2 EA $ 50,000 $ 100,000 Cofferdam River Xing 5,000 SF $ 21.00 $ 105,000 Dewater 800 LF $ 90.00 $ 72,000 Excavation 4400 CY $ 5.00 $ 22,000 Formwork 19200 SF $ 12.50 $ 240,000 Concrete 1400 CY $ 300.00 $ 420,000 Roller Gate $ 410,000 Steel 15,000 lbs $ 10.00 $ 150,000 Concrete Excavation 20 CY $ 500.00 $ 10,000 Controls 1 LS $250,000.00 $ 250,000 Subtotal $ 9,565,750 Contingencies 45% $ 4,304,588 Subtotal $13,870,338 Permitting, Engineering, & Construction Management 30% $ 4,161,101
Total $18,031,439
GEC Yuba River Fish Passage Improvement Investigation Page G-11 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 9 Full Width Weirs – at Unaltered Daguerre Dam
Full Width Weirs downstream of Daguerre Point Dam Item Quantity Unit Unit Cost Item Cost Total Mobilization $ 800,000 Ramp Construction Phase 1 $ 5,891,800 Load Material 185,200 CY $ 2.00 $ 370,400 Haul Material 185,200 CY $ 4.00 $ 740,800 Grade Material 185,200 CY $ 2.00 $ 370,400 Compaction 185,200 CY $ 1.00 $ 185,200 River Rock 77,800 CY $ 50.00 $3,890,000 Rip Rap 6,700 CY $ 50.00 $ 335,000 Grade Control Construction $11,652,500 Temporary River Diversion 2 EA $ 50,000 $ 100,000 Temporary Longitudinal Wall 1,200 Tons $ 1,750.00 $2,100,000 Transverse Sheet Piling 2,900 Tons $ 2,000.00 $5,800,000 Formwork 105000 SF $ 12.50 $1,312,500 Concrete 7800 CY $ 300.00 $2,340,000 Ramp Construction Phase 2 $ 6,077,000 Load Material 185,200 CY $ 2.00 $ 370,400 Haul Material 185,200 CY $ 5.00 $ 926,000 Grade Material 185,200 CY $ 2.00 $ 370,400 Compaction 185,200 CY $ 1.00 $ 185,200 River Rock 77,800 CY $ 50.00 $3,890,000 Rip Rap 6,700 CY $ 50.00 $ 335,000 Grade Control Construction $ 9,577,500 Temporary River Diversion 2 EA $ 50,000 $ 100,000 Remove Temporary Longitudinal Wall 1 LS $ 25,000.00 $ 25,000 Transverse Sheet Piling 2,900 Tons $ 2,000.00 $5,800,000 Formwork 105000 SF $ 12.50 $1,312,500 Concrete 7800 CY $ 300.00 $2,340,000 Subtotal $33,998,800 Contingencies 45% $15,299,460 Subtotal $49,298,260 Permitting, Engineering, & Construction Management 30% $14,789,478
Total $64,087,738
GEC Yuba River Fish Passage Improvement Investigation Page G-12 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
Table 10 Full Height Tainter Gates at Daguerre Point Dam
Opinion of Probable Cost for Radial Gate Approach Item Quantity Unit Unit Cost Item Cost Mobilization and Demobilization 1 LS $1,545,000 $1,545,000 Construct Gates $9,414,917 Rent Sheet Piles 240 ton $220 $52,800 Construct and Remove D/S Cofferdam 6,500 CY $75 $487,500 Pumping 400 days $773 $309,000 Drive and Remove Temporary Sheet Piles 240 ton $1,133 $271,920 Excavate behind Dam 4,630 CY $10 $47,689 Demolish Concrete 7,250 CY $100 $725,000 Collect and Haul Concrete 7,975 CY $50 $398,750 Concrete Formwork 38,400 SF $10 $395,520 Concrete in Place 3,960 CY $250 $990,000 Concrete Reinforcing Steel 523,908 lbs $1.55 $809,438 Gates and Appurtenances 4,600 SF $361 $1,658,300 Reinforced Concrete Slab 370 CY $350 $129,500 Top of Structure Access Bridge Superstructure 4,500 SF $100 $450,000 Access Bridge Piers 11 Ea $12,000 $132,000 Hoist and Associated Equipment 10 EA $200,000 $2,000,000 3 Phase Power to Site 1 LS $300,000 $300,000 Automation 1 LS $257,500 $257,500 Subtotal $10,959,917 Contingencies 45% $4,931,963 Subtotal $15,891,879 Permitting, Engineering, & Construction Management 30% $4,767,564
Total $20,659,443
GEC Yuba River Fish Passage Improvement Investigation Page G-13 National Marine Fisheries Service Final Report April 2014 Appendix G Opinion of Probable Costs
GEC Yuba River Fish Passage Improvement Investigation Page G-14 National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Gathard Engineering Consulting
APPENDIX H
Construction
Schedules
Yuba River Fish Passage Improvement Investigation
National Marine Fisheries Service
i. GEC Yuba River Fish Passage Improvement Investigation Page H-1
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Appendix H
Construction Schedules
Table of Figures
Figure 1 Daguerre Point Dam Removal Schedule ...... 2 Figure 2 Englebright Dam Removal Schedule ...... 3 Figure 3 Partial Removal of Englebright Dam to Elevation 460 ...... 4 Figure 4 partial Removal of Englebright Dam to Elevation 430 ...... 5 Figure 5 Construction of a Rock Ramp at Daguerre Point Dam ...... 6 Figure 6 Construction of Full Width Weirs at Daguerre Point Dam ...... 7 Figure 7 Construction of Full Height Gates at Daguerre Point Dam ...... 8
ii. GEC Yuba River Fish Passage Improvement Investigation Page H-i
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Construction Schedules
Development of construction schedules shown in the following figures assumed that construction activities begin in the year 2015. These schedules have been developed to conceptually illustrate the construction process elements of the construction.
The schedules for complete removal of both dams assume that Englebright Dam is removed three years before Daguerre Point Dam. For this approach upstream water diversion facilities would be constructed just prior to Daguerre Point Dam removal; but nearly three years after removal of Englebright Dam to allow river conditions at the proposed new diversion facility to stabilize. Temporary water diversion facilities, such as well points or conventional wells, are not detailed in the following schedules. However, these schedules assume that temporary water diversion facilities such as wells or well points would be installed independently before removal of Englebright Dam.
ii. GEC Yuba River Fish Passage Improvement Investigation Page H-1
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Figure 1 Daguerre Point Dam Removal Schedule
i. GEC Yuba River Fish Passage Improvement Investigation Page H-2
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Figure 2 Englebright Dam Removal Schedule i. GEC Yuba River Fish Passage Improvement Investigation Page H-3
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Figure 3 Partial Removal of Englebright Dam to Elevation 460
i. GEC Yuba River Fish Passage Improvement Investigation Page H-4
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Figure 4 partial Removal of Englebright Dam to Elevation 430
i. GEC Yuba River Fish Passage Improvement Investigation Page H-5
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Figure 5 Construction of a Rock Ramp at Daguerre Point Dam
i. GEC Yuba River Fish Passage Improvement Investigation Page H-6
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Figure 6 Construction of Full Width Weirs at Daguerre Point Dam
i. GEC Yuba River Fish Passage Improvement Investigation Page H-7
National Marine Fisheries Service Final Report April 2014 Appendix H Construction Schedules
Figure 7 Construction of Full Height Gates at Daguerre Point Dam
i. GEC Yuba River Fish Passage Improvement Investigation Page H-8