Meeting of the Central Valley Flood Protection Board February 28, 2020
Staff Report for Permit No. 19153 Agenda Item No. 11B
Department of Water Resources Lower Elkhorn Basin Levee Setback Project, Yolo County
1.0 – ITEM
Consider conditional approval of Permit No. 19153 (Attachment A) to construct the Lower Elkhorn Basin Levee Setback Project (LEBLS) in Yolo County.
2.0 - APPLICANT
State of California, Department of Water Resources (DWR)
3.0 – PROJECT LOCATION
The LEBLS project includes the east levee of the Yolo Bypass from I-5 to the Sacramento Bypass and the north levee of the Sacramento Bypass in the Lower Elkhorn Basin (Attachment B) in Yolo County.
4.0 – PROJECT DESCRIPTION
This project will accomplish multi-benefit objectives. The primary objectives are to provide flood risk reduction for improved public safety and ecosystem benefits. These are achieved by enhancing the flood system capacity and protecting high risk communities in the Sacramento Basin through expansion of the Yolo Bypass and the Sacramento Bypass. The project will provide improved public safety for more than 780,000 people in the Lower Sacramento River Basin area by reducing flood stages for the 200-year flood event on the Sacramento River and I-5 in the vicinity of the Yolo Bypass.
Application No. 19153 Agenda Item No. 11B
The project will include the following flood-risk reduction elements:
• Widening the Yolo Bypass by constructing a setback levee approximately 1,500 to 1,800 feet east of the Tule Canal in the Lower Elkhorn Basin between I-5 and the Sacramento Bypass; • Widening the Sacramento Bypass by constructing a setback levee approximately 1,500 feet north of the existing levee; • Degrading 80 percent of the Yolo Bypass east levee, leaving approximately 500 feet long segments for upland habitat every 2,000 feet. The existing Sacramento Bypass north levee will be degraded; • Improving the Lower Elkhorn Basin interior drainage system to facilitate discharge of precipitation volumes up to the 100-year flood event; • Implementing ecosystem improvements in the Lower Elkhorn Basin to mitigate project impacts, which will provide multiple ecosystem benefits to the surrounding areas. These ecosystem benefits include: o Adding approximately 1,100 acres of inundated floodplain habitat that is compatible with agriculture; o The establishment of a Tule Canal buffer that can provide additional riparian habitat; o Direct ecosystem connectivity to the Sacramento Bypass Wildlife Area; o Providing a substantial portion of the connectivity needed to bridge the gap between Knaggs Ranch and the Fazio Wildlife Area; o The alleviation of fish-stranding concerns and promotion of operational flexibility for agriculture and food web distribution flows; and o Promoting an operational landscape that benefits agriculture and fish rearing habitat.
Several utility pipes will need to be relocated and deepened. Utility penetrations must comply with design requirements as defined by Title 23, Division 1. An existing 12-inch diameter steel pipe that delivers jet fuel to Sacramento International Airport was relocated in 2019 at least 50 feet below the Sacramento Bypass and the setback levee. AT&T will bore new fiber optic conduit approximately 20 feet below the setback levee at two locations. The existing pump station pipe outfalls will be modified and relocated. In addition, the Bryte Landfill site, north of the Sacramento Bypass, is currently being relocated. The relocation will be completed in 2020. The draft Permit No. 19153 in Appendix A includes the following project components:
• Construction of the setback levees on the Yolo and Sacramento Bypasses. • Placement of discharge pipes associated with the new pump station.
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Application No. 19153 Agenda Item No. 11B
• Degradation of 80 percent of the Yolo Bypass east levee; • Degradation of the existing Sacramento Bypass north levee; • Implementation of ecosystem improvements in the Lower Elkhorn Basin; and • Relocation of the AT&T fiber optic lines.
Parts of the project will be designed and constructed by other agencies and are either outside the Board jurisdiction or have/will apply for a separate Board encroachment permits. The Board Permit does not include the following project components:
• Design and construction of improvements to the Lower Elkhorn Basin interior drainage system of ditches, culverts, a new pump station, and detention basin. This work will be completed by the Sacramento Area Flood Control Agency (SAFCA); • Reconstruction of rural county roads; • Changes to overhead PG&E electrical lines; • Relocation of the Sacramento International Airport jet fuel line; and • Relocation of the Bryte Landfill.
A Board has already permitted the jet fuel line relocation effort. A “name change” Board Permit will need to be issued for the AT&T fiber optic lines.
5.0 – AUTHORITY OF THE BOARD
California Water Code § 8534, 8590 – 8610.5, and 8700 – 8710
California Code of Regulations, Title 23, Division 1 (Title 23): • § 6, Need for a Permit • § 108, Existing Encroachments within an Adopted Plan of Flood Control • § 116, Borrow and Excavation Activities – Land and Channel • § 120, Levees • § 121, Erosion Control • § 123, Pipelines, Conduits and Utility Lines • § 124, Abandoned Pipelines and Conduits • § 130, Patrol Roads and Access Ramps • § 131, Vegetation
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Application No. 19153 Agenda Item No. 11B
• Rivers and Harbors Act of 1899, Title 33 United States Code, § 408, hereinafter referred to as Section 408
6.0 - PROJECT ANALYSIS
6.1 – Project Background
Early in the twentieth century, United States Geological Survey recognized that the capacity of the Sacramento River channel was not adequate to convey river flood flows. As a result, levee construction along the Yolo Bypass began in 1917. The levees along the Yolo Bypass were constructed using a clamshell bucket dredger, loosely depositing high-plasticity clays with organics as the main embankment material. The clam shell excavation created what is known as the Tule Canal at the waterside toe. Available information indicates the foundation soils include soft to stiff clays with slickensides and some organic lenses from basin deposits.
The project site, located in the Lower Elkhorn Basin, is primarily used for agricultural production of row crops such as tomatoes, sunflowers and safflowers; alfalfa; and nut- bearing orchards. The population is fewer than 100 people with fewer than 100 structures including farm buildings, permanent and temporary residences, and commercial buildings. The Basin is subdivided by interior drainage canals forming three sub-basins identified as Reclamation Districts (RD): RD 537 in the southeast quarter of the Basin, RD 785 in the southwest quarter of the Basin, and RD 827 in the northern part of Basin. The RDs each operate their own interior drainage canals and pump systems for crop irrigation and interior drainage. The topography of the Lower Elkhorn Basin area is relatively flat and slopes gently from northeast to southwest. The ground surface elevations range from about 10 to 25 feet North American Datum of 1983 (NAD83). The Yolo Bypass is oriented generally north to south. The Sacramento Bypass channel is oriented east to west.
6.1.1 – Project Alteration Need
The project is needed for the following reasons:
• A high risk of flooding threatening life and public safety, property, critical infrastructure, and the environment exists throughout the areas protected by the Yolo and Sacramento Bypasses, including, but not limited to, portions of the cities of Sacramento, West Sacramento, and Woodland. • The project will provide increased system resiliency to convey large flood events as outlined in the 2017 Central Valley Flood Protection Plan Update for the Yolo
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Application No. 19153 Agenda Item No. 11B
Bypass upstream of I-5 in the City of Woodland and the Sacramento River in the City of Sacramento. • The project will address deficiencies in the existing Sacramento Bypass North Levee and portions of the Yolo Bypass East Levee, as evidenced by several slope failures, sloughing, and slope cracking that occurred in 2017 and 2019. • Long-term operation, maintenance, repair, replacement, and rehabilitation costs for the existing flood management facilities will continue to increase as these facilities age. • Climate change is expected to increase hydrologic variability, put further stress on the flood management system and erode the current level of flood protection. • Impaired hydrologic and geomorphic processes; eliminated, fragmented, and degraded habitat; and other stressors have reduced the abundance, distribution, and diversity of native aquatic and terrestrial species in the Sacramento Basin. • The project will improve native fish and riparian habitats that have been reduced in the Sacramento River Basin.
6.2 – Hydraulic Analysis
DWR conducted Hydrologic and Hydraulic (H&H) system performance and risk and uncertainty analyses to comply with Section 408 Engineering Circular 1165-2-216, and to determine H&H impacts within the overall Sacramento River Flood Control Project (SRFCP). The H&H analysis informs the levee design for setting levee height and identifying potential erosion impacts associated with the project.
The design water surface elevation (DWSE) for the project is the 100-year water surface elevation. The levee heights were determined by the 100-year DWSE plus 6 feet of freeboard, plus one additional foot for potential future climate change adaptation/resiliency.
Many different model results were evaluated for hydraulic impacts. The models assumed completion of a combination of different authorized and funded projects such as the Folsom Joint Federal Project and Sacramento Weir expansion, which change the dynamics of the local hydraulic conditions in various ways. Changes include a change in the flow-split at the Fremont Weir between the Yolo Bypass and Sacramento River, and stage reductions at the Yolo Bypass downstream of Fremont Weir as well as at Verona. The stage reduction in the Yolo Bypass will continue until the confluence with the Sacramento Bypass, where the stage reductions will be neutralized by increased backwater from the Sacramento Bypass flow. Downstream of the Sacramento Bypass, nominal stage increases in the Yolo Bypass will result from the increased Sacramento
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Application No. 19153 Agenda Item No. 11B
Bypass flow. Overall, the stages within the Yolo Bypass will be reduced from River Mile 56 to River Mile 47.
Board staff has reviewed the H&H information provided by DWR for their 100% design and has determined that the proposed project is expected to result in no adverse hydraulic impacts to the SRFCP levees. The current design is expected to comply with applicable Title 23 standards.
6.3 – Geotechnical Analysis
The scope of DWR’s geotechnical analyses for the 100 percent design included a design engineering analysis for seepage, slope stability, settlement, and erosion. The geotechnical design water surface elevation (GDWSE) for the proposed project is the 100-year water surface elevation plus an additional 1 foot of hydraulic loading for resiliency and climate change adaptation. The GDWSE approximately coincides with the 200-year water surface elevation and the setback levee is designed to withstand this higher water surface elevation. Where needed, seepage berms were designed along the 7 miles of setback levee to mitigate underseepage potential.
The levee will be constructed with additional overbuild heights up to 1.4 feet to mitigate long term foundation consolidation settlement. Slope protection from approximately the 10-year water surface elevation up to the crest of the levee will be provided to resist erosion due to wind-wave action. Additionally, the north levee tie-in to the Yolo Bypass will receive slope protection from levee toe to levee crest for approximately 1,000 feet, and the south tie-in at the Sacramento Bypass will receive a concrete liner from toe to crest for approximately 700 feet, connecting to the existing concrete liner.
The setback levee will be constructed from native borrow sources excavated within the project area, on the water side of the proposed levee alignment. The higher prevalence of fat clay with Liquid Limits over 50 in the project area will be mitigated by adopting 4:1 side slopes, a wider crown, foundation area improvement, and the establishment of native grass vegetation having deep root systems on the levee slopes. The flatter slopes increase the factors of safety and are expected to minimize potential maintenance from surficial sloughing associated with clay desiccation and softening. The wider crown adds resiliency to the levee prism, and the establishment of native grasses is anticipated to further minimize the potential for maintenance associated with erosion and surficial sloughing.
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Application No. 19153 Agenda Item No. 11B
Summary of Special Construction Details include:
• 4:1 (h:v) slopes for both waterside and landside slopes; less steep slopes improve stability allowing the use of locally sourced borrow materials that have higher Liquid Limits and Plasticity Indexes. • The setback levee foundation area will be over excavated to a depth of 3 feet and replaced with engineered fill. The bottom of the over excavation will be scarified an additional 8 inches and recompacted prior to placement of fill, for a total of 3.7 feet of foundation improvement. • 28-foot-wide crown to provide resiliency against potential seasonal shrinkage cracking and potential slope creep along the levee crest shoulder areas, thereby ensuring the minimum required 20-foot crown width is maintained over time. • Establish native grass vegetation with deep root structures to reduce potential for surficial slope creep and erosion.
Utilizing onsite borrow material has significant environmental benefits versus importing borrow material. Using onsite borrow material is a more efficient use of limited resources and reduces overall environmental impacts by reducing negative impacts to air quality and regional roadway impacts associated with having to import over 6 million cubic yards from offsite borrow sources.
After review of the geotechnical analyses, and plans and specifications, Board staff has determined that the proposed project is anticipated to be compliant with Title 23 standards, and that there are no anticipated adverse geotechnical effects or variances to the Title 23 standards required at this time.
6.4 – Real Estate Requirements
To construct the project, DWR must acquire property rights for the new setback levee footprint, the new floodway area created by setting back the existing levee, the riparian buffer area created where the existing levee footprint is degraded, the interior drainage improvements, and for the borrow sites. The LEBLS project will require acquisition of approximately 2,100 acres of real estate containing over 23 parcels and 9 landowners.
As of February 2020, DWR has acquired one (1) parcel of approximately 67 acres. DWR has concluded negotiations for two other parcels. In addition, DWR anticipates concluding its negotiations for two additional parcels soon. DWR has filed condemnation actions for two other parcels in Superior Court. Condemnation proceedings for these two more parcels will be commenced soon.
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Application No. 19153 Agenda Item No. 11B
7.0 – AGENCY COMMENTS AND ENDORSEMENTS
The comments and endorsements associated with this project, from all pertinent agencies, are shown below:
• RD 827, RD 785, and RD 537 endorsed the application in in December 2017 and January 2018 with no conditions; and • The USACE 408 permission approval is expected in March 2020.
8.0 – CALIFORNIA ENVIRONMENTAL QUALITY ACT (CEQA) ANALYSIS
The Board, as a responsible agency under CEQA, has reviewed the Lower Elkhorn Basin Levee Setback Project Draft and Final Environmental Impact Reports (EIR) (SCH No. 2016092015, May 2018 and March 2019, respectively), the April 2019 Addendum No. 1 to the Final EIR , the Statement of Overriding Considerations, and the Mitigation Monitoring and Reporting Program (MMRP) prepared by the lead agency, the California Department of Water Resources (DWR). DWR’s proposed project is covered by the Draft and Final EIR, and Addendum to the EIR. These documents, including project design, are available for review in hard copy at the Board and DWR offices.
DWR determined that the proposed project, as described in the EIR and Addendum to the EIR, will have a significant effect on the environment, and filed a Notice of Determination with the State Clearinghouse on March 21, 2019. DWR incorporated mandatory mitigation measures into the project plans to avoid or mitigate impacts. These mitigation measures, included in DWR’s Final EIR and MMRP, address impacts to Aesthetics; Air Quality; Biological Resources (Vegetation and Wildlife, Wetlands and Other Waters); Climate Change; Cultural Resources; Geology, Soils, and Paleontological Resources; Hazards and Hazardous Materials; Hydrology, Hydraulics, and Flood Risk Management; Land Use and Planning, and Agricultural and Forestry Resources; Noise and Vibration; Traffic and Transportation; Utilities and Service Systems; and Water Quality. These mitigation measures are within the responsibility and jurisdiction of DWR and have been adopted by DWR.
The Draft and Final EIR, and Addendum to the EIR, found less than significant/ beneficial impacts under hydrology for flood-related impacts associated with the construction of approximately seven miles of new setback levees in the Yolo (along the Lower Elkhorn Basin) and Sacramento Bypasses. A beneficial impact is an impact that is considered to cause a positive change or improvement in the environment and for
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Application No. 19153 Agenda Item No. 11B which no mitigation measures are required. To determine potential flooding impacts of the proposed project, the EIR analyzed the effects of the proposed project on water surface elevations and flood risk both upstream and downstream of the project site and vicinity. Hydraulic modeling was performed under Existing and Future Conditions, with the proposed project, for 100- and 200-year flood events. Analyses under Existing and Future Conditions, with the proposed project, for 100- and 200-year flood events did show a slight increase in water surface elevations (WSE) at three locations in the Yolo Bypass, in addition to small increases in the Sacramento River Deep Water Ship Channel; however, none of the WSE increases would expose people or structures to a significant risk of loss, injury, or death involving flooding.
Although not required for less than significant/beneficial project impacts, DWR will implement Mitigation Measure HH-1: Coordinate with Local Maintaining Agencies to Ensure Proper Maintenance of Yolo Bypass Levees from Sacramento Bypass to Cache Slough found on page 4.14.-23 in the Final EIR. Implementation of Mitigation Measure HH-1 will reduce the potential for any adverse effects from WSE increases in the Yolo and Sacramento Bypasses and river reaches, under both Existing and Future Conditions and 100- and 200-year flood events.
The proposed project will expand the existing flood conveyance capacity of the Yolo and Sacramento Bypasses by setting back the Bypass levees, so there will be flooding over the expanded floodplain area during high-flow conditions. The Sacramento Bypass will still receive floodwaters during managed overflow of the Sacramento Weir, and local agricultural drainages will still receive normal return flows and stormflows. The Yolo Bypass will still receive floodwaters from passive overflow of the Fremont Weir, managed overflow of the Sacramento Weir, agricultural drainage stormflows, and treated wastewater discharges into the Tule Canal and other local agricultural drainages. Frequency of inundation of lands in the Bypasses will be the same as current practice; however, inundation depths will be slightly reduced during the 100- and 200- year flood events, due to the wider channel profile of the Bypasses after the levees are set back.
The Board, as a responsible agency, is responsible for mitigating and avoiding only the direct and/or indirect environmental effects of those parts of the project which it decides to carry out, finance, or approve (CEQA Guidelines § 15096(g); Public Resources Code § 21002.1(d)). Here, the Board’s action is limited to approving an encroachment permit for work to construct approximately seven miles of new setback levees in the Yolo Bypass along the Lower Elkhorn Basin and the Sacramento Bypass, and the Board’s jurisdiction is limited to imposing conditions or mitigation related to effects on the State Plan of Flood Control.
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Application No. 19153 Agenda Item No. 11B
In accordance with CEQA Guidelines § 15096, Board staff independently reviewed DWR’s Draft and Final EIR, and Addendum to the EIR, and finds these environmental documents prepared by the lead agency adequately address hydrology impacts, including potential flood risk, for the Board’s approval of Permit No. 19153 to authorize work to construct approximately seven miles of new setback levees in the Yolo Bypass along the Lower Elkhorn Basin and the Sacramento Bypass, which is within the Board’s jurisdiction as it relates to effects on the State’s flood control system.
The Board, as a responsible agency, is required to make findings for each significant effect of the project (CEQA Guidelines § 15096(h) and § 15091). However, the Draft and Final EIR identified less than significant/beneficial impacts to flood risk, which is the only resource area within the Board’s jurisdiction. The EIR conclusions related to flood risk are further supported by the Lower Elkhorn Basin Levee Setback Project Hydraulic Impact Analysis, which includes risk and uncertainty analyses, prepared by DWR’s Division of Flood Management (Draft May 2017), relied upon by Board staff, which confirms the proposed project will result in less than significant hydraulic impacts. The project will not adversely impact the State Plan of Flood Control. Based on staff’s review of the EIR and the hydraulic analyses, there is no substantial evidence to support a fair argument that the project may result in significant impacts related to flood risk within the Board’s jurisdiction. The proposed project would expand the flood capacities of the Yolo and Sacramento Bypasses.
According to the EIR, the proposed project results in less than significant/beneficial impacts related to flood risk, which is the only resource area within the Board’s jurisdiction; therefore, the Board’s approval of the encroachment permit does not require additional findings unrelated to flood risk under CEQA Guidelines § 15096(h), nor is the consideration of alternatives required. In accordance with CEQA Guidelines § 15096(f) and (g), staff recommends that the Board make responsible agency findings that approval of Permit No. 19153 will not result in any significant adverse impacts related to flood risk, and no additional mitigation measures within the Board’s jurisdiction are required.
The documents and other materials which constitute the record of the Board’s proceedings in this matter are in the custody of the Executive Officer, Central Valley Flood Protection Board, 3310 El Camino Ave., Suite 170, Sacramento, California 95821.
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Application No. 19153 Agenda Item No. 11B
9.0 – CA WATER CODE SECTION 8610.5 AND OTHER CONSIDERATIONS
California Water Code, Section 8610.5 (c) provides that the Board shall consider all the following matters, if applicable:
1. Evidence that the Board admits into its record from any party, state or local public agency, or nongovernmental organization with expertise in flood or flood plain management:
Staff requests that the Board consider this staff report, any attachments and materials to which the report refers, and any evidence submitted to the Board prior to or at the hearing.
2. The best available science that relates to the scientific issues presented by the executive officer, legal counsel, the Department of Water Resources or other parties that raise credible scientific issues.
In making its findings, the applicant has used the best available science relating to the issues presented by all parties. On the important issue of hydraulic impacts, DWR used a one-dimensional and two-dimensional unsteady flow HEC-RAS model. This is considered one of the best available scientific tools for evaluating potential hydraulic impacts on water surface elevation and velocity with a sufficient level of analytical detail for the proposed project. The modeling showed improvements to the water surface elevation in the Yolo Bypass. No other credible scientific issues have been raised.
3. Effects of the decision on facilities of the State Plan of Flood Control (SPFC).
The proposed project is expected to result in no significant adverse hydraulic or geotechnical impacts on the facilities of the SPFC and is consistent with the 2017 Central Valley Flood Protection Plan Update (CVFPP) and current applicable and feasible Title 23 Standards because the project is anticipated to produce no significant increases in water surface elevation, significant increases in flows, or adverse geotechnical impacts on SPFC facilities.
4. Effects of reasonably projected future events, including, but not limited to, changes in hydrology, climate, and development within the applicable watershed:
The proposed project provides compliance with Federal and State regulations and guidance and is consistent with the goal to advance 200-year protection to urban areas. The project area results in no significant adverse hydraulic or
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Application No. 19153 Agenda Item No. 11B
geotechnical impacts; therefore, this project is not anticipated to create any adverse impacts to surrounding projects under current or projected future conditions.
10.0 – STAFF RECOMMENDATION
Adopt:
• The CEQA findings: The Board, acting as a responsible agency under CEQA, has independently reviewed and considered the environmental documents prepared for the project. Approving Permit No. 19153 will not result in any significant adverse impacts related to flood risk, and no additional mitigation measures within the Board’s jurisdiction are required.
Approve:
• Encroachment Permit No. 19153 in substantially the form provided in Attachment A pending Section 408 approval from the USACE; and
Direct:
• The Executive Officer to take the necessary actions to execute the permit and file a Notice of Determination pursuant to CEQA with the State Clearinghouse.
11.0 – LIST OF ATTACHMENTS
A. Draft Permit No. 19153 B. Location Maps D. Final Design Documentation Report (Appendices available electronically upon request)
Reviewers:
Technical Review: Connie Perkins, P.E., Plan Implementation & Compliance Branch Environmental Review: Jennifer Stewart, Senior Environmental Scientist Staff Report Review: Greg Harvey, P.E., Plan Implementation & Compliance Branch Chief Sarah Backus, Staff Counsel Michael C. Wright, P.E., Chief Engineer
Page 12 of 12 Agenda Item No. 11B Attachment A - Draft Permit
DRAFT STATE OF CALIFORNIA THE RESOURCES AGENCY THE CENTRAL VALLEY FLOOD PROTECTION BOARD
PERMIT NO. 19153 BD This Permit is issued to:
Department of Water Resources 3310 El Camino Avenue Sacramento, California 95821
Consistent with the Central Valley Flood Protection Plan, the project will expand the flood capacities of the Yolo and Sacramento Bypasses, which are both critical flood risk reduction elements for major urban and agricultural areas in the lower Sacramento River watershed. The project will lower flood stages in the Sacramento River and upper Yolo Bypass, reducing flood risks to portions of the cities of Sacramento, West Sacramento, and Woodland. Located in the County of Yolo, just west of the Sacramento River, the project site extends along the Sacramento Bypass and continues north along the east side of the Yolo Bypass terminating just south of I-5. The project includes the design, engineering, permitting, real estate acquisition, and construction of 1.5 miles of setback levee for the Sacramento Bypass north levee and 5.5 miles of setback levee for the Yolo Bypass east levee, adjacent to the Lower Elkhorn Basin. Additionally, construction will include seepage berms, erosion protection, access roads, partially degrading existing levees, borrow site restoration, and ecosystem enhancement through floodplain expansion and required project mitigation.
See description tab, at 38.67314˚N 121.64246˚W, Reclamation Districts 537, 785, and 827, Yolo and Sacramento Bypasses, Yolo County.
NOTE: Special Conditions have been incorporated herein which may place limitations on and/or require modification of your proposed project as described above.
(SEAL)
Dated: ______Executive Officer
Page 1 of 8 DWR 3784 (Rev. 9/85) Agenda Item No. 11B Attachment A - Draft Permit
GENERAL CONDITIONS:
ONE: This permit is issued under the provisions of Sections 8700 – 8723 of the Water Code.
TWO: Only work described in the subject application is authorized hereby.
THREE: This permit does not grant a right to use or construct works on land owned by the Sacramento and San Joaquin Drainage District or on any other land.
FOUR: The approved work shall be accomplished under the direction and supervision of the Central Valley Flood Protection Board (Board) or the California Department of Water Resources (DWR), and the permittee shall conform to all requirements of the Board or DWR.
FIVE: Unless the work herein contemplated shall have been commenced within one year after issuance of this permit, the Board reserves the right to change any conditions in this permit as may be consistent with current flood control standards and policies of the Board.
SIX: This permit shall remain in effect until revoked. In the event any conditions in this permit are not complied with, it may be revoked on 15 days’ notice.
SEVEN: It is understood and agreed to by the permittee that the start of any work under this permit shall constitute an acceptance of the conditions in this permit and an agreement to perform work in accordance therewith.
EIGHT: This permit does not establish any precedent with respect to any other application received by the Board.
NINE: The permittee shall, when required by law, secure the written order or consent from all other public agencies having jurisdiction.
TEN: The permittee is responsible for all personal liability and property damage which may arise out of failure on the permittee’s part to perform the obligations under this permit. If any claim of liability is made against the State of California, or any departments thereof, the United States of America, a local district or other maintaining agencies and the officers, agents or employees thereof, the permittee shall defend and shall hold each of them harmless from each claim.
ELEVEN: The permittee shall exercise reasonable care to operate and maintain any work authorized herein to preclude injury to or damage to any works necessary to any plan of flood control adopted by the Board or the Legislature, or interfere with the successful execution, functioning or operation of any plan of flood control adopted by the Board or the Legislature.
TWELVE: Should any of the work not conform to the conditions of this permit, the permittee, upon order of the Board, shall in the manner prescribed by the Board be responsible for the cost and expense to remove, alter, relocate, or reconstruct all or any part of the work herein approved.
SPECIAL CONDITIONS FOR PERMIT NO. 19153 BD
LIABILITY AND INDEMNIFICATION
THIRTEEN: The permittee shall defend, indemnify, and hold the Central Valley Flood Protection Board (Board), and their respective officers, agents, employees, successors and assigns, safe and harmless, of and from all claims and damages related to the Board's approval of this permit, including but not limited to claims filed pursuant to the California Environmental Quality Act. The Board expressly reserve the right to supplement or take over their defense, in their sole discretion.
FOURTEEN: The permittee shall reimburse the Board in full for all reasonable costs and attorneys’ fees, including, but not limited to, those charged to it by the California Office of Attorney General, that the Board incurs in connection with the defense of any action brought against the Board challenging this permit or any other matter related to this permit or the work performed by the State in its issuance of this permit. In addition, the permittee shall reimburse the Board for any court costs and reasonable attorneys’ fees that the Board/Indemnitees may be required by a court to pay as a result of such action. The permittee may participate in the defense of the action, but its participation shall not relieve it of its obligations under the conditions of this permit. Page 2 of 8 DWR 3784 (Rev. 9/85) Agenda Item No. 11B Attachment A - Draft Permit
FIFTEEN: The Board, Reclamation District No. (RD) 785, RD 537, and RD 827 and State Maintained Area ST008 shall not be held liable for any damages to the permitted encroachment(s) resulting from releases of water from reservoirs, flood fight, operation, maintenance, inspection, or emergency repair.
AGENCY CONDITIONS
SIXTEEN: All work approved by this permit shall be in accordance with the submitted drawings and specifications dated February 2020 except as modified by special permit conditions herein. No further work, other than that approved by this permit, shall be done in the area without prior approval of the Board.
SEVENTEEN: The permittee shall be responsible for the repair of any damages to the project levee, channel, banks, floodway, or other flood control facilities due to construction, operation, or maintenance of the proposed project.
EIGHTEEN: The permittee shall comply with all conditions set forth in the letter from the Department of the Army (U.S. Army Corps of Engineers, Sacramento District) dated XXXXXX, which is attached to this permit as Exhibit A and is incorporated by reference.
NINETEEN: The permittee shall provide the Board with fee titles granting the Sacramento and San Joaquin Drainage District flood control rights upon, over, and across the property to be occupied by the proposed flood control works. The fee titles shall include the area within the proposed floodway, the levee section, and the area 10 feet in width adjacent to the landward levee toe.
TWENTY: The Board reserves the right to add additional or modify existing conditions when there is a change in ownership and/or maintenance responsibility of the work authorized under this permit.
PRE-CONSTRUCTION
TWENTY-ONE: Prior to construction, the permittee shall have obtained all required access rights to all property where work is to be performed under this permit. Use of Sacramento and San Joaquin Drainage District (SSJDD) property held in fee is permitted for this project, notwithstanding GENERAL CONDITION THREE.
TWENTY-TWO: Upon receipt of a signed copy of the issued permit the permittee shall contact the Board by telephone at (916) 574-0609 to notify them and meet with the inspector from the Division of Engineering (DOE)'s Levee Repair Headquarters who is assigned to your project. Failure to do so at least 10 working days prior to start of work may result in a delay of the project.
TWENTY-THREE: During construction of the project, any and all anticipated or unanticipated conditions encountered which may impact existing levee integrity or flood control shall be brought to the attention of the Flood Project Inspector immediately and prior to continuation. Any encountered abandoned encroachments shall be completely removed or properly abandoned under the direction of the Department of Water Resources DOE Inspector.
Page 3 of 8 DWR 3784 (Rev. 9/85) Agenda Item No. 11B Attachment A - Draft Permit
TWENTY-FOUR: If the project results in an adverse hydraulic impact, the permittee shall provide appropriate mitigation measures, to be approved by the Board, prior to implementation of mitigation measures.
TWENTY-FIVE: The permittee shall cooperate with the Board to ensure that any encroachment (i.e., existing pump stations) that must be relocated, modified or otherwise altered to accommodate construction of the improvements permitted herein is relocated, modified or otherwise altered in a manner that complies with current applicable state and federal standards. If the affected encroachment has an existing Board permit or is subject to some other applicable Board authorization, the permittee shall cooperate with the Board to ensure the permit or other authorization is appropriately amended to reflect the changed condition as shown on as-built drawings for the encroachment and overall project. If the encroachment does not have a Board permit or other Board authorization, the permittee shall cooperate with the Board to determine whether a Board permit is required. If so, the permittee shall cooperate with the Board to ensure that the required permit application is made and, if granted, the permit reflects the changed condition as shown on as-built drawings for the encroachment and the overall project.
TWENTY-SIX: The permittee shall contact the U. S. Army Corps of Engineers regarding inspection of the project during construction as the proposed work is an alteration to the existing Federal Flood Control Project that will be incorporated into the Sacramento River Flood Control Project.
CONSTRUCTION
TWENTY-SEVEN: No construction work of any kind shall be done on the existing Federal Flood Control Project during the flood season from November 1 to April 15 without prior approval of the Board. Failure to submit a Time Variance Request to the Board at least 10 working days prior to the start of work may result in a delay of the project.
TWENTY-EIGHT: All addenda and contract change orders made to the approved plans and / or specifications by the permittee after Board approval of this permit shall be submitted to the Board's Chief Engineer for review and approval prior to incorporation into the permitted project. The submittal shall include all supplemental plans, specifications, and necessary supporting geotechnical, hydrology and hydraulics, or other technical analyses. The Board shall acknowledge receipt of the addendum or change submittal in writing within ten (10) working days of receipt, and shall work with the permittee to review and respond to the request as quickly as possible. The Board may request additional information as needed and will seek comment from the U.S. Army Corps of Engineers and / or local maintaining agencies when necessary. The Board will provide written notification to the permittee if the review period is likely to exceed thirty (30) calendar days. Upon approval of submitted documents the permit shall be revised, if needed, prior to construction related to the proposed changes.
TWENTY-NINE: Ditches, power poles, standpipes, distribution boxes, and any other above ground structures located within 10 feet of the waterward or landward levee toes shall be relocated a minimum distance of 10 feet beyond the levee toes on the new setback levee.
THIRTY: All irrigation and drainage ditches and swales shall be located and maintained at least 10
Page 4 of 8 DWR 3784 (Rev. 9/85) Agenda Item No. 11B Attachment A - Draft Permit
feet away from the landward levee toe and no deeper than 5 feet on the new setback levee.
THIRTY-ONE: Ditches greater than 5 feet deep shall be located 20 feet from the landward levee toe of the new setback levee or as required to ensure levee stability for the site-specific soil conditions.
THIRTY-TWO: All drains and abandoned conduits shall be removed from the site prior to levee construction.
THIRTY-THREE: No material shall be removed from within 100 feet of the adjacent property lines and proposed and remaining levee toes. The boundary of the removal area shall be permanently marked. The perimeter of the removal area shall be maintained with side slopes of 1 vertical to 3 horizontal or flatter to prevent progressive erosion.
THIRTY-FOUR: The borrow area shall be graded uniformly so that no holes or high spots remain.
THIRTY-FIVE: If periodic inspections reveal that a borrow operation will adversely affect flood control, additional permit conditions may be imposed or the permit may be revoked.
THIRTY-SIX: No excavation shall be made outside of the borrow area or made lower than indicated on the submitted plans.
THIRTY-SEVEN: Fill material shall be placed only within the area indicated on the approved plans.
THIRTY-EIGHT: All fill material for the proposed levee shall be impervious material with 20 percent or more passing the No. 200 sieve, a plasticity index of 8 or more, and a liquid limit of less than 50 and free of lumps or stones exceeding 3 inches in greatest dimension, vegetative matter, or other unsatisfactory material. Special construction details (e.g., 4:1 slopes) may be substituted where these soil properties are not readily attainable. Fill material shall be compacted in 4- to 6-inch layers to a minimum of 95 percent relative compaction as measured by the ASTM D698 standard.
THIRTY-NINE: Slopes of the proposed bypass levee shall be no steeper than 4 horizontal to 1 vertical on the water side and 3 horizontal to 1 vertical on the land side.
FORTY: All holes, depressions, and ditches in the foundation area shall be stripped of surface vegetation to a depth of 6-inches. Organic soil and roots greater than 1-1/2 inches shall be removed to a depth of 3 feet.
FORTY-ONE: The fill surface area shall be graded to direct drainage away from the toe of the levee.
FORTY-TWO: A minimum 14-foot-wide gate shall be provided at access locations to the levee crown roadway to prevent unauthorized vehicular access.
FORTY-THREE: Prior to placement of fill against the levee slope, within 10 feet of the levee toe, and on the new setback levee, all surface vegetation shall be removed to a depth of 6 inches. Organic soil and roots larger than 1-1/2 inches in diameter shall be removed to a depth of 3 feet.
FORTY-FOUR: The proposed access ramp shall be graded to direct all surface drainage away from the levee section.
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FORTY-FIVE: The waterward access ramp shall be a side-approach type and slope downstream.
FORTY-SIX: The access ramps shall be surfaced with a minimum of 4 inches of compacted, Class 2, aggregate base (Caltrans Specification 26-1.02A) underlain by geogrid in accordance with plans and specifications.
FORTY-SEVEN: Aggregate base material shall be compacted to a relative compaction of not less than 95 percent as measured by the current ASTM D1557 standard, with a moisture content sufficient to obtain the required compaction.
FORTY-EIGHT: Pipe installed in the levee section and within 10 feet of the levee toes shall be new steel and at least 7 gauge. Steel pipe shall be corrosion-proofed externally with a coating of coal-tar enamel; asphalt-saturated felt wrap; cement mortar; or PVC or polyethylene tape wrapped to a thickness of 30 mils, or equivalent. Steel pipe shall be corrosion-proofed internally with a continuous lining of cement mortar, asphalt, or equivalent.
FORTY-NINE: All pipelines shall be tested and confirmed free of leaks by X-ray, pressure tests, or other approved methods during construction or any time after construction upon request by the Board.
FIFTY: The invert of the pump station pipes through the levee section shall be above the design flood plane elevation of 30.98 feet NAVD 1988.
FIFTY-ONE: All pipe joints within the levee section shall be butt welded.
FIFTY-TWO: The pipes shall be installed through the levee section at a right angle to the centerline of the levee.
FIFTY-THREE: The annular space between the pipes shall be completely filled with grout (i.e., Controlled Low Strength Material (CLSM).
FIFTY-FOUR: The waterward end of the discharge pipes shall be constructed to direct the flow away from the bank to prevent erosion.
FIFTY-FIVE: A positive-closure device that is readily accessible during periods of high water shall be installed on the waterward side of the levee.
FIFTY-SIX: The pipe shall be buried at least twelve (12) inches below the levee slopes and twenty- four (24) inches below the levee crown.
FIFTY-SEVEN: An earth pad shall be constructed on the levee crown over the pipe to provide at least two (2) feet of cover and shall have end slopes no steeper than 10 horizontal to 1 vertical.
FIFTY-EIGHT: Pipe exit points located within a leveed bypass or floodway shall be a minimum of 300 feet from the waterside levee toe.
FIFTY-NINE: For wells that are nonproductive or abandoned within the floodway and 50 feet either
Page 6 of 8 DWR 3784 (Rev. 9/85) Agenda Item No. 11B Attachment A - Draft Permit
side, drill hole must be completely grouted and the area restored to the condition that existed before work started.
SIXTY: The revetment shall not contain any reinforcing steel, floatable, or objectionable material. Asphalt or other petroleum-based products may not be used as fill or erosion protection on the levee section or within the floodway.
SIXTY-ONE: The recommended minimum thickness of revetment, measured perpendicular to the bank or levee slope, is 18 inches below the usual water surface and 12 inches above the usual water surface.
VEGETATION / ENVIRONMENTAL MITIGATION
SIXTY-TWO: Cleared trees and brush shall be completely burned or removed from the bypasses, and downed trees or brush shall not remain during the flood season from November 1 to April 15.
SIXTY-THREE: The mitigation measures approved by the CEQA lead agency and the permittee are found in its Mitigation and Monitoring Reporting Program (MMRP) adopted by the CEQA lead agency. The permittee shall implement all such mitigation measures.
SIXTY-FOUR: No further tree planting or work, other than that covered by this application, shall be performed in the area without prior approval of the Board.
SIXTY-FIVE: Trees shall not be planted within 15 feet of the levee toe.
SIXTY-SIX: No wild rose, grape, blackberries, or other bushy thickets shall be propagated or otherwise allowed to grow at this site. Permittee shall promptly remove such vegetation.
SIXTY-SEVEN: If the planted trees result in an adverse hydraulic impact, the permittee will provide appropriate mitigation.
SIXTY-EIGHT: Should the riparian plantings need to be removed, the applicant shall (a) have an acceptable mitigation site available, including property rights, and (b) fund the removal of the project and the plantings of the mitigation site.
SIXTY-NINE: Any temporary irrigation system for the riparian plantings shall be secured to prevent flotation or detachment during high water.
POST-CONSTRUCTION
SEVENTY: All temporary fencing, gates and signs shall be removed upon completion of the project.
SEVENTY-ONE: All unwanted debris generated by this project shall be properly disposed of outside the Sacramento and Yolo Bypass and off all Project Works and project right-of-way.
SEVENTY-TWO: Any portion of the Sacramento and Yolo Bypass that is not part of the project shall
Page 7 of 8 DWR 3784 (Rev. 9/85) Agenda Item No. 11B Attachment A - Draft Permit
be restored to at least the condition that existed prior to commencement of work.
SEVENTY-THREE: Upon completion of the project, density tests by a certified soils laboratory will be required to verify compaction of the levee fill and trench backfill.
SEVENTY-FOUR: Within 180 days of completion of the project, the permittee shall submit to the Board and Department of Water Resources Flood Project Inspection Section an electronic copy of as- built drawings, stamped and signed by a licensed civil engineer registered in the State of California, certifying the work was performed and inspected in accordance with the Board permit conditions and submitted drawings and specifications.
SEVENTY-FIVE: Within 180 days of completion of the project, the permittee shall submit to the Board proposed revisions to the Corps of Engineers, Supplement to Standard Operation and Maintenance Manual(s) and associated "as-built" drawings for system alterations approved by this permit that are to be incorporated into the federal Sacramento River Flood Control Project.
SEVENTY-SIX: Within three years from completion of the construction of the work authorized under this permit, the permittee shall provide the Sacramento and San Joaquin Drainage District, acting by and through the Central Valley Flood Protection Board of the State of California, a permanent easement and/or a joint use agreement granting all flood control rights upon, over and across the property that is or will be occupied by the existing or to-be-constructed levee including the area of the cutoff wall and levee raise and realignment fill areas. The easement must include the new setback levee not presently encumbered by a Central Valley Flood Protection Board easement. For information regarding existing Central Valley Flood Protection Board Easements, please contact the Board at (916) 653-5654.
OPERATIONS AND MAINTENANCE
SEVENTY-SEVEN: After each period of high water, debris that accumulates at the site shall be completely removed from the Sacramento and Yolo Bypass, and off all Project Works.
SEVENTY-EIGHT: The permittee shall maintain the permitted encroachment(s) and the Project Works within the utilized area in the manner required and as requested by the authorized representative of the Board, Reclamation District No. (RD) 785, RD 537, and RD 827, or any other agency responsible for maintenance and shall, at all times, allow officials from these agencies to access the levee, levee slope, and any adjacent areas as necessary for flood control.
PROJECT ABANDONMENT / CHANGE IN PLAN OF FLOOD CONTROL
SEVENTY-NINE: If the project, or any portion thereof, is to be abandoned in the future, the permittee or successor shall abandon the project under direction of the Board at the permittee's or successor's cost and expense.
END OF CONDITIONS
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Source: DWR
CENTRAL VALLEY FLOOD Application 19153 PROTECTION BOARD
Project Vicinity Map
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Agenda Item No. 11B Attachment B – Location Maps
Source: DWR CENTRAL VALLEY FLOOD PROTECTION Application 19153 BOARD
Project Location Map
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Agenda Item No. 11B Attachment B – Location Maps
Source: URS
CENTRAL VALLEY FLOOD Application 19153 PROTECTION BOARD
Reclamation District Map
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Agenda Item No. 11B Attachment C - Design Documentation Report
Lower Elkhorn Basin Levee Setback
DESIGN DOCUMENTATION REPORT
February 2020
February 20, 2020
Prepared by: DEPARTMENT OF WATER RESOURCES Division of Flood Management 3464 El Camino Avenue, Suite 150 Sacramento, CA 95821 Agenda Item No. 11B Attachment C - Design Documentation Report
Lower Elkhorn Basin Levee Setback Project
Design Documentation Report
February , 2020
20 Agenda Item No. 11B Attachment C - Design Documentation Report
Table of Contents 1. General ...... 1 1.1. Project Description ...... 1 1.2. Previous and Ongoing Studies ...... 1 1.2.1. California Water Action Plan (CWAP) ...... 1 1.2.2. Central Valley Flood Protection Plan (CVFPP) ...... 2 1.2.2.1. CVFPP Conservation Strategy (CS) ...... 2 1.2.3. Lower Sacramento River/Delta North (LSDN) Regional Flood Management Plan (RFMP) ...... 2 1.2.4. Central Valley Integrated Flood Management Study (CVIFMS) ...... 2 1.2.5. Sacramento Basin-Wide Feasibility Study (BWFS) ...... 3 1.2.6. California Water Plan Update ...... 3 1.2.7. Sacramento River General Re-Evaluation Report ...... 3 1.2.8. American River Common Features General Re-Evaluation Report ...... 3 2. Project Information ...... 5 2.1. Project Objectives ...... 5 2.2. Coordination with Other Agencies ...... 5 2.3. Public Involvement ...... 6 2.4. Project Schedule ...... 6 2.5. Design Criteria ...... 6 2.6. Lands, Easements and Rights-of-Way ...... 7 3. Technical Studies ...... 8 3.1. Topography and Datums ...... 8 3.2. Hydrology and Hydraulics ...... 8 3.2.1. Purpose ...... 8 3.2.2. Design Criteria ...... 8 3.2.3. Pertinent Water Surface Elevations ...... 9 3.2.4. Overview of the H&H/R&U Analysis ...... 9 3.2.5. Hydrology ...... 13 3.2.5.1. Products and Tools ...... 13 3.2.5.2. Reservoir Simulation ...... 13 3.2.5.3. Event Selection ...... 13 3.2.6. Hydraulics ...... 16 3.2.6.1. One-Dimensional Hydraulics Model ...... 16 3.2.6.1.1. Model Selection ...... 16 3.2.6.1.2. Calibration and Validation ...... 16 3.2.6.1.3. Downstream Boundary Condition ...... 17 3.2.6.1.4. Existing Condition Model ...... 18 3.2.6.1.5. Existing With-Project Condition Model ...... 19 3.2.6.1.6. Future Without-Project Condition Model ...... 19 3.2.6.1.7. Future With-Project Condition Model ...... 19 3.2.6.1.8. Intermediate Cumulative Analysis Condition Model ...... 20 Agenda Item No. 11B Attachment C - Design Documentation Report 3.2.6.1.9. With-Project Cumulative Condition Model ...... 20 3.2.6.1.10. Hydraulic Impacts – Stages ...... 20 3.2.6.1.11. Design Water Surface Elevations ...... 22 3.2.6.2. Two-Dimensional Hydraulics Model ...... 22 3.2.6.2.1. Model Selection ...... 22 3.2.6.2.2. Calibration and Validation ...... 22 3.2.6.2.3. Baseline Model...... 22 3.2.6.2.4. Future Without-Project Model ...... 22 3.2.6.2.5. Future With-Project Model ...... 22 3.2.6.2.6. Existing With-Project Model ...... 23 3.2.6.2.7. Results ...... 23 3.2.6.3. Alternate Sacramento Bypass Alignment ...... 23 3.2.7. Conditional Risk Analysis ...... 23 3.2.8. Wind Setup and Wave Run-up ...... 26 3.3. Groundwater ...... 27 3.3.1. Hydrogeologic and Groundwater Conditions ...... 27 3.3.1.1. Regional Geology ...... 27 3.3.2. Groundwater Conditions ...... 27 3.3.2.1. Groundwater Levels and Flows ...... 27 3.3.3. Evaluation of Groundwater Conditions at Proposed Borrow Sites ...... 28 3.4. Summary of Geotechnical Data and Evaluations ...... 28 3.4.1. Proposed Setback Levee Overview ...... 29 3.4.1.1. Lower Elkhorn Basin Site Description ...... 29 3.4.1.2. Geometry and Onsite Borrow Materials ...... 29 3.4.1.3. Design Water Surface Elevation and Levee Height ...... 30 3.4.1.4. Rural Streets ...... 31 3.4.1.5. Utility Penetrations and Existing Land Features ...... 31 3.4.2. Geotechnical Investigations and Background Information ...... 31 3.4.2.1. Geotechnical Investigations ...... 31 3.4.2.2. Previous Geotechnical Studies and Reports ...... 32 3.4.2.3. Existing Bypass Levee Construction and Past Performance...... 32 3.4.2.4. Geomorphic Studies ...... 33 3.4.3. Design Analyses ...... 33 3.4.3.1. Reach Selection ...... 34 3.4.3.2. Geotechnical Evaluations ...... 34 3.4.3.3. Material Properties ...... 34 3.4.3.4. Analyses Criteria ...... 34 3.4.4. Geotechnical Design Results ...... 34 3.4.4.1. Reach A – 106+26 to 118+75 ...... 35 3.4.4.2. Reach B – 118+75 to 179+71...... 35 3.4.4.3. Reach C – 179+71 to 248+43 ...... 35 3.4.4.4. Reach D – 248+43 to 280+13 ...... 35 3.4.4.5. Reach E – 280+13 to 341+61 ...... 35 3.4.4.6. Reach F – 341+61 to 407+80 ...... 36 3.4.4.7. Reach G – 407+80 to 421+48 ...... 36 Agenda Item No. 11B Attachment C - Design Documentation Report 3.4.4.8. Reach H – 421+48 to 448+42 ...... 36 3.4.4.9. Reach I – 448+42 to 477+15 ...... 36 3.4.5. Slope Protection ...... 37 3.4.6. Construction Recommendations ...... 37 3.5. Environmental Evaluation ...... 37 3.5.1. Rare Plant Survey ...... 37 3.5.2. Environmental Controls ...... 37 3.5.2.1. SWRCB Stormwater General Permit Requirements ...... 37 3.5.2.2. Federal Endangered Species Act Requirements ...... 38 3.5.2.3. State Endangered Species Act Requirements ...... 38 3.5.2.4. CDFW Streambed Alteration Agreement Requirements ...... 38 3.5.2.5. Clean Water Act Requirements ...... 39 3.6. Hazardous and Toxic Waste ...... 39 3.6.1. Hazards Report ...... 39 3.6.2. Findings and Recommendations ...... 39 3.7. Cultural and Historic Resources ...... 41 3.8. Civil Analyses, Design, and Levee Improvement Alternatives Analysis ...... 41 3.8.1. Civil Design Process ...... 41 3.8.1.1. Terrain Model ...... 41 3.8.1.2. Project Corridors and Construction Limits ...... 41 3.8.1.3. Project Phasing ...... 42 3.8.2. Utilities and Encroachments ...... 42 3.8.3. Transportation ...... 42 3.8.3.1. Existing Conditions ...... 42 3.8.3.2. Design Criteria ...... 42 3.8.3.3. Design Approach ...... 43 3.8.4. Interior Drainage ...... 43 3.8.4.1. Design and Evaluation Approach ...... 43 3.8.4.2. Approach for Evaluation and Design of Downstream Agricultural Ditches ...... 43 3.8.4.2.1. Water Quality Control ...... 43 3.8.4.3. General Design Criteria ...... 44 3.8.5. Plans ...... 44 3.8.6. Specifications ...... 44 3.8.7. Opinion of Probable Project Costs ...... 44 3.9. Pump Station ...... 44 3.10. Construction Phasing Plan ...... 44 4. Inspection, Operation and Maintenance ...... 45 5. References ...... 46 6. Acronyms ...... 47
Agenda Item No. 11B Attachment C - Design Documentation Report Tables
Table 3-1: Summary of various water surface elevations pertinent to the analysis ...... 9 Table 3-2: Overview of H&H/R&U analysis ...... 11 Table 3-3: Event Selection for 100- and 200-yr Events (Based on Analysis Performed for the Sacramento BWFS) ...... 15 Table 3-4: Project Performance Results ...... 25 Table 3-5: Exploration Depths and Spacing ...... 32
Figures
Figure 1: Project Location Map ...... 49 Figure 2: TO 34 SRR Model Extent ...... 50 Figure 3: Baseline Conditions Projects ...... 51 Figure 4: Cumulative Improvements...... 52 Figure 5: Hydraulic Impacts for EWP Approximate 100-Yr Event (1997 x 95%) ...... 53 Figure 6: Hydraulic Impacts for EWP Approximate 200-Yr Event (1997 x 110%) ...... 54 Figure 7: Hydraulic Impacts for FWOP Approximate 100-Yr Event (1997 x 95%) ...... 55 Figure 8: Hydraulic Impacts for FWOP Approximate 200-Yr Event (1997 x 110%) ...... 56 Figure 9: Hydraulic Impacts for FWP Approximate 200-Yr Event (1997 x 110%) ...... 57 Figure 10: Hydraulic Impacts for FWP Approximate 200-Yr Event (1997 x 110%) ...... 58 Figure 11: Hydraulic Impacts for Intermediate Cumulative Approximate 200-Yr Event (1997 x 110%) ...... 59 Figure 12: Hydraulic Impacts for Intermediate Cumulative Approximate 200-Yr Event (1997 x 110%) ...... 60 Figure 13: Hydraulic Impacts for Full Cumulative Approximate 200-Yr Event (1997 x 110%) ...... 61 Figure 14: Hydraulic Impacts for Full Cumulative Approximate 200-Yr Event (1997 x 110%) ...... 62 Figure 15: Yolo Bypass Design Water Surface Profile (Sheet 1 of 4) ...... 63 Figure 16: Sacramento Bypass Design Water Surface Profile (Sheet 1 of 2) ...... 67 Figure 17: Soil Resistivity Survey Lines ...... 69 Figure 18: Project Schedule ...... 70
Agenda Item No. 11B Attachment C - Design Documentation Report Appendices
Appendix G-1: Geotechnical Basis of Design Report (GBOD) Appendix G-2: Geotechnical Data Report (GDR) Appendix G-3: Borrow Data Report Appendix H-1: Hydrologic and Hydraulic System Performance Analysis Ground Rules Appendix H-2: One-Dimensional Hydraulic Model Validation Appendix H-3: Wave Run-up and Wind Setup Analysis Appendix H-4: Interior Drainage Study Appendix H-5: Geomorphic Analysis Appendix H-6: Observed Drawdown Rates Appendix H-7: Conditional Risk Analysis Appendix H-8: System Performance Analysis Procedure Appendix H-9: Sacramento Bypass Tie-in Alignment Appendix H-10: Hydraulic Model Tabular Results Appendix M-1: SAR Meetings – Sign-in Sheets, Agendas, Notes Appendix S-1: Sacramento Weir GPS Base Control Report Appendix S-2: Sacramento Weir Additional GPS Base Control Report Appendix S-3: Yolo Bypass Levee Widening Survey Control Description Report Agenda Item No. 11B Attachment C - Design Documentation Report 1. General
1.1. Project Description The Department of Water Resources (DWR) has identified the Lower Elkhorn Basin Levee Setback (LEBLS) project as a near term action that will expand the capacities of the Yolo Bypass and Sacramento Bypass while improving public safety for more than 780,000 people in the Lower Sacramento River Basin area by increasing system capacity and reducing flood stages in the surrounding urban areas. Located just north of Sacramento, this project runs from east to west on the north side of the Sacramento Bypass and continues north along the east side of the Yolo Bypass terminating just south of I-5. This project provides the design, engineering, permitting, real estate acquisition, and construction of approximately 7 miles of setback levees that improve flood system capacity and provide opportunities for ecosystem enhancement. See Figure 1 for an overview of the project layout and design.
As part of the Central Valley Flood Protection Plan (CVFPP), Regional Flood Management Plans, Sacramento Basin-Wide Feasibility Study (BWFS), and the Conservation Strategy (CS) this project has refined multi-benefit solutions for an integrated system-wide approach in the Central Valley consistent with California Water Action Plan (CWAP) objectives.
This project was derived from the CVFPP recommendations to improve flood system flexibility and resiliency by implementing system scale multi-benefit improvements, these system improvements will be designed and implemented to create a sustainable water-related resources management system that achieves a resilient, dynamic balance between the societal values of public health and safety, vital ecosystems, stable economies, and opportunities for enriching experiences.
1.2. Previous and Ongoing Studies The Lower Elkhorn Basin Levee Setback project is a culmination of many previous studies that have occurred over the last few years. Below are some of those studies as well as projects that are interrelated to the LEBLS project.
1.2.1. California Water Action Plan (CWAP) The CWAP describes the challenges of managing California’s water resources to meet both human and ecological needs in a time of growing demands and dwindling supplies. The CWAP cites the challenges of uncertain water supplies, drought, declining groundwater supplies, poor water quality, declining native fisheries, loss of wildlife habitat, flood management challenges, supply disruption, climate change, and population growth. It sets three broad objectives as a means for addressing these challenges:
1. More reliable water supplies. 2. Restoration of important species and habitat. 3. More resilient, sustainably managed water resources system, which includes water supply, water quality, flood protection, and environment.
CWAP is a roadmap toward water sustainability and integrated resource management. The plan is intended to provide a high-level guide to State program development and budgeting decisions. Agenda Item No. 11B Attachment C - Design Documentation Report 1.2.2. Central Valley Flood Protection Plan (CVFPP) The 2012 CVFPP and the 2017 update is guiding California’s participation (and influencing federal and local participation) in managing flood risk along the Sacramento River and San Joaquin River systems, with planned updates every five years. Despite effective investments in flood management programs and infrastructure, flood risk remains high and is expected to increase over time due to population growth, development, and climate change. The CVFPP is a reconnaissance level study that evaluated an array of actions to improve flood protection for urban areas, small communities, and rural-agricultural areas. It included system improvements such as expansion of bypasses to enhance the resiliency of the flood management system, improved flood system operations, groundwater recharge, and ecosystem restoration. The CVFPP determined that it could effectively improve management of flood risk for urban, small community, and rural-agricultural areas given differing population, assets at risk, and other State interests. The next CVFPP update is scheduled for 2022.
1.2.2.1. CVFPP Conservation Strategy (CS) The CS presents guidance, data, and tools to facilitate multi-benefit planning while improving flood protection throughout the Central Valley. The CS was an integral part of the 2017 CVFPP. The purpose of the CS is to provide a comprehensive, long-term approach for improving riverine and floodplain ecosystems through multi-benefit projects that provide ecological and public safety benefits and a regional programmatic framework and platform for increasing the predictability and cost-effectiveness of permitting, while resulting in more effective and less costly conservation outcomes. The CS also provides goals and measurable objectives for monitoring and evaluating progress of conservation efforts within the SPFC.
1.2.3. Lower Sacramento River/Delta North (LSDN) Regional Flood Management Plan (RFMP) The RFMP for the LSDN reflects the recommendations of local agencies in the region regarding implementation of the CVFPP. As part of the RFMP development, a coalition of local agencies also developed a Corridor Management Framework (CMF) for the Lower Sacramento/Delta North Region, which encompasses the Yolo Bypass. The CMF was developed as a locally preferred approach to achieving federal, State, and local policy, regulatory, and ecosystem restoration purposes for the region. The CMF contains a number of projects and assurances that allow for the integration of competing purposes as part of the Yolo Bypass/Cache Slough Complex Management Plan (CMP). The CMP integrated with the guidance, data, and tools of the CS, and also with regulatory actions detailed in the Biological Opinion (BiOp), which may be implemented wholly, or in part, in the Yolo Bypass. As part of the CMF, local and regional agencies intend to develop specific Yolo Bypass actions to address flood management and agricultural sustainability concerns, as well as locally preferred plans to support implementation of the National Marine Fisheries Service (NMFS) and USFWS BiOp and California Endangered Species Act (CESA)/Incidental Take Permit (ITP) requirements in the Cache Creek Settling Basin (CCSB).
1.2.4. Central Valley Integrated Flood Management Study (CVIFMS) CVIFMS was a collaborative watershed study focusing on multiple objective solutions to identified problems and opportunities in the areas of flood risk management, environmental restoration, and water supply in the Central Valley. The study phase was limited to an evaluation of the Sacramento River Basin watershed. CVIFMS includes a complete list of recommendations for USACE implementation, as well as a reconnaissance-level evaluation of CVFPP initiatives. Agenda Item No. 11B Attachment C - Design Documentation Report 1.2.5. Sacramento Basin-Wide Feasibility Study (BWFS) The purpose of this study was to evaluate the feasibility of different alternatives for improving the flood management system, consistent with the State Systemwide Investment Approach (SSIA), including Improving flood management system flexibility and resiliency through expansion and extension of the flood bypass system and other system improvements Integrating ecosystem enhancements and other multi-objective projects with systemwide flood management improvements Combining regional improvements with system Improvements to identify the State’s systemwide investment package. The study informed the 2017 CVFPP update and FloodSAFE Financing Plan by: Establishing a framework for evaluating multi-objective project benefits, identifying beneficiaries, and allocating costs on a systemwide scale. The study also helped identify elements of the SSIA that can be further developed, in an efficient and timely manner, in ongoing or new federal cost-share feasibility studies.
1.2.6. California Water Plan Update The California Water Plan is prepared and updated by DWR. It provides a collaborative planning framework for elected officials, agencies, tribes, water and resource managers, businesses, academia, stakeholders, and the public to develop findings and recommendations and make informed decisions for California's water future. The plan presents the status and trends of California's water-dependent natural resources; water supplies; and agricultural, urban, and environmental water demands for a range of plausible future scenarios. The California Water Plan also evaluates different combinations of regional and statewide resource management strategies to reduce water demand, increase water supply, reduce flood risk, improve water quality, and enhance environmental and resource stewardship. The evaluations and assessments performed for the plan help identify effective actions and policies for meeting California's resource management objectives in the near term and for several decades to come. DWR’s goal for the California Water Plan is to receive broad input and support from Californians in producing a strategic water plan that meets California Water Code (CWC) requirements; guides State investments in innovation and infrastructure; and advances integrated water management and sustainable outcomes.
1.2.7. Sacramento River General Re-Evaluation Report The Sacramento River General Re-Evaluation Report (GRR) was initiated in October 2015 by USACE, with CVFPB and DWR as partner agencies. The reevaluation study included an analysis of the Sacramento River Flood Control Project (SRFCP). The general reevaluation assessed a combination of one or more ecosystem restoration and flood risk management measures, including widening existing bypasses, modifying existing weirs, optimizing weir operations, constructing setback levees, developing floodplain management plans, restoring riverine aquatic and riparian habitat, removing barriers to fish passage, and restoring natural geomorphic processes, among others. Changes or modifications to the SRFCP may also include updates or revisions to the operation and maintenance manuals in affected areas. The reevaluation eventually leads to Congressional authorization and federal funding for implementation of recommended actions.
1.2.8. American River Common Features General Re-Evaluation Report This report presents the findings of a general reevaluation study of the authorized Common Features Project. The study was conducted to determine whether there is a Federal interest in modifying the authorized project for flood risk reduction in the Greater Sacramento Area at the confluence of the Sacramento River and the American River. Flooding in the City of Sacramento and surrounding urban areas would have devastating economic, social, political, and demographic consequences for the region, Agenda Item No. 11B Attachment C - Design Documentation Report and for the State of California as a whole. The existing levees are not capable of safely passing large flood flows on the American River and the Sacramento River. This study proposes additional measures to reduce the risk of flooding in the Sacramento area. These measures are evaluated in the context of current and planned flood risk reduction measures elsewhere in the watersheds of both rivers. The Common Features Project is one of several flood risk management projects authorized within the American River Watershed in Northern California.
Agenda Item No. 11B Attachment C - Design Documentation Report 2. Project Information
2.1. Project Objectives This project will serve multi-benefit objectives. The primary objectives are to provide flood risk reduction for improved public safety and regional security, and ecosystem benefits. These are achieved by enhancing the flood system capacity and protecting high risk communities in the Sacramento Basin through expansion of the Yolo Bypass and Sacramento Bypass. The project would provide improved public safety for more than 780,000 people in the Lower Sacramento River Basin area by reducing flood stages for the 200-year flood event at the I Street Bridge (Sacramento River) and I-5 (Yolo Bypass).
As part of the project, DWR will construct setback levees to widen portions of both the Yolo and Sacramento Bypasses to increase conveyance capacity and reduce flood risk. Additionally, as part of this project under contract with DWR, the Sacramento Area Flood Control Agency (SAFCA) will design and construct improvements to the Lower Elkhorn Basin interior drainage system of ditches, culverts, and a new pump station and detention basin. The project will include the following flood-risk reduction elements:
• Widening the Yolo Bypass by constructing a setback levee approximately 1,500 to 1,800 feet east of the Tule Canal in the Lower Elkhorn Basin (between I-5 and the Sacramento Bypass). • Widening the Sacramento Bypass by constructing a setback levee approximately 1,500 feet north of the existing levee. • Degrading 80 percent of the Yolo Bypass east levee, leaving approximately 500 feet long segments for upland habitat every 2,000 feet. The existing Sacramento Bypass north levee will be degraded. • Improving the Lower Elkhorn Basin interior drainage system to facilitate discharge of precipitation volumes up to the 100-year flood event. (by SAFCA) • Implementing ecosystem improvements in the Lower Elkhorn Basin to mitigate project impacts.
In addition to the flood-risk reduction benefits, the project will provide multiple ecosystem benefits to the surrounding areas. These ecosystem benefits include:
• Adding approximately 1,100 acres of inundated floodplain habitat that is compatible with agriculture. • The establishment of a Tule Canal buffer that can provide additional riparian habitat. • Direct ecosystem connectivity to the Sacramento Bypass Wildlife Area. • Providing a substantial portion of the connectivity needed to bridge the gap between Knaggs Ranch and the Fazio Wildlife Area. • The alleviation of fish-stranding concerns and promotion of operational flexibility for agriculture and food web distribution flows • Promoting an operational landscape that benefits agriculture and fish rearing habitat. 2.2. Coordination with Other Agencies Close coordination with other agencies and entities has occurred throughout the project. The following agencies and entities have been engaged to date:
• Central Valley Flood Protection Board (CVFPB) • United States Army Corps of Engineers (USACE) Agenda Item No. 11B Attachment C - Design Documentation Report • Sacramento Area Flood Control Agency (SAFCA) • Yolo County • Sacramento County • Reclamation District 537 • Reclamation District 785 (consolidated with RD 537 in 2019) • Reclamation District 827 (consolidated with RD 537 in 2019) • DWR Flood Maintenance Office • Lower Elkhorn Basin Landowners • Native American Tribes with cultural and traditional affiliation in the project area • Others have been engaged through the public scoping meeting for the NEPA/CEQA
DWR has worked closely with the local entities throughout the investigations of the project. This includes geodetic, geotechnical, environmental, cultural surveys, and other studies. Furthermore, DWR contracted with SAFCA in early 2019 to design and construct improvements to the interior drainage system of ditches, culverts, detention basin, and a new larger pump station that will replace the existing three pump stations.
2.3. Public Involvement DWR has ensured that there has been public involvement at all stages of project development so the public is aware of what the project is proposing. Public involvement in the project to date has occurred in multiple forums, including the following:
1. Scoping meetings to satisfy requirements of the National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA) 2. Updates at CVFPB Board meetings 3. Meetings with Yolo County, RDs, landowners and their legal and technical representatives 4. Regular Project Delivery Team (PDT) meetings with the technical teams responsible for developing and reviewing the levee setback project design, and 5. Regular meetings with SAFCA’s PDT (consisting of landowners and the RDs) responsible for implementing improvements to the Lower Elkhorn Basin interior drainage system and pump station for DWR.
The scope of these meetings has focused on project alternatives and coordination.
2.4. Project Schedule The LEBLS project schedule was developed in collaboration with USACE. Great consideration was given to estimate tasks and review times so that DWR can meet its required goal of awarding construction in 2020. Figure 18 shows the flowchart of major project milestones and tasks to break ground for construction in 2020. The construction of the levee setback project is estimated to take 3 to 4 years, and an additional 5 years of monitoring for establishment of mitigation areas. Concurrent with setting back the levee, SAFCA will construct the interior drainage system improvements and the new pump station. Close coordination will be required between DWR and SAFCA to manage multiple construction contractors within the project area.
2.5. Design Criteria General design criteria includes, but are not limited to, those contained in 44 CFR 65.10, the Corps’ Engineering Manual 1110-2-1913 (The Design and Construction of Levees), CCR Title 23, Waters, and the May 11, 2012 Urban Levee Design Criteria (ULDC) published by DWR. Specific design criteria for each of the major Agenda Item No. 11B Attachment C - Design Documentation Report disciplines (Hydrology and Hydraulics, Geotechnical and Civil designs, etc.) was developed for this report and is located within the appropriate sections.
2.6. Lands, Easements and Rights-of-Way To construct the project, DWR must acquire property rights for the new setback levee footprint, the new floodway area created by setting back the existing levee, the riparian buffer area created where the existing levee footprint is degraded, the interior drainage improvements, and for borrow sites. The land is presently owned by private landowners and DWR is acquiring the real estate needed for the project. Temporary rights of entry for investigation purposes were established and DWR evaluated existing easements and right-of-way in the context of project needs. The LEBLS project will require acquisition of approximately 2,100 acres of real estate over 23 parcels and 9 landowners.
Agenda Item No. 11B Attachment C - Design Documentation Report 3. Technical Studies
3.1. Topography and Datums The topographic data included in the design was obtained from two sources: Central Valley Floodplain Evaluation and Delineation (CVFED) LiDAR, 2008-2010 data developed by DWR and design-level topographic surveys and survey control reports. The CVFED LiDAR data was also used to develop the geometry for the hydraulic models. The vertical project datum is North American Vertical Datum, 1988 (NAVD 88) and the horizontal datum is the North American Datum, 1983 (NAD 83).
3.2. Hydrology and Hydraulics
3.2.1. Purpose The purpose of the hydrologic and hydraulic (H&H) system performance analysis and the accompanying risk and uncertainty (R&U) analysis is to comply with the requirements of Section 14 of the River and Harbors Appropriation Act of 1899 codified in 33 USC 408 (referred to as Section 408). Under the terms of Section 408, any proposed modification to a federal project must not be injurious to the public interest and not impair the usefulness of the project. The system performance analysis follows U.S. Army Corps of Engineers (USACE) Engineer Circular (EC) 1165-2-216 (USACE, 2015) and USACE Hydrologic Engineering Center (HEC) Project Report (PR) 71 (USACE, 2009), which provides guidance for the analysis. Additionally, the H&H analysis helps inform the design of the levee setback based on the requirements in the Urban Levee Design Criteria (ULDC) developed by the CA Department of Water Resources (DWR, 2012).
The H&H analysis will also be used to determine the potential H&H impacts of the proposed alterations within the system. Examples of factors considered when evaluating H&H impacts include changes in stage, velocity, scour, and flow distribution upstream and downstream of the proposed alterations. The R&U analysis will be used to determine impacts by assessing changes in conditional annual exceedance probability (C-AEP) within the system. Here, C-AEP is the probability that the authorized design water surface elevation (DWSE) (or actual top of levee if it is greater) is equaled or exceeded in any given year. Conditional non-exceedance probability (CNP) will also be computed. CNP is the probability that the authorized DWSE (or actual top of levee if it is greater) will not be equaled or exceeded in any given year.
3.2.2. Design Criteria Although the setback levee is non-urban, it is being designed following the ULDC except for the top of levee (TOL) which is based on the 100-yr (instead of the 200-yr) DWSE. The H&H analysis informs the levee design primarily for setting the levee heights and ensuring adequate freeboard. Additionally, the hydraulic analysis will help identify potential erosion impacts associated with the project. Changes to the design will be considered to address these potential impacts.
To determine the top of levee elevation, DWSEs must first be determined using ULDC analysis
specifications, herein referred to as DWSEULDC (ULDC analysis specifications are focused on design and are different than the specifications for permitting). Agenda Item No. 11B Attachment C - Design Documentation Report 3.2.3. Pertinent Water Surface Elevations Three types of water surface elevations are pertinent in the analysis:
• DWSEULDC determined based on ULDC specifications for design purposes.
• The authorized DWSEs, herein referred to as DWSE1957. • Water surface elevations used for determining Section 408 hydraulic impacts based on permitting specifications.
Table 3-1 provides a summary of these water surface elevations.
Table 3-1: Summary of various water surface elevations pertinent to the analysis Water surface elevation Description
DWSEULDC DWSE through the system; determined based on ULDC specifications for design purposes. The pertinent design water surface elevations are the p=0.01 (“100-
yr”) or DWSEULDC100 for non-urban levees. The p=0.005 (“200-yr”) or DWSEULDC200, the standard for urban levees, will also be computed.
DWSE1957 DWSE through the system; determined based on USACE Sacramento District file 50-10-3334, dated March 15, 1957 (USACE, 1957). The water surface profiles shown on these sheets are known as the 1957 design water surface or, more commonly, the ’57 profile. This is the authorized design water surface elevation, which is used for evaluation of changes in C-AEP (and CNP) for the Section 408
permit. (That is, does the probability of exceeding DWSE1957 in any given year change between the baseline and with-project conditions?) Where the actual
top of levee is higher than the DWSE1957, the top of levee was used for evaluation of changes in C-AEP. Water surface elevation to This water surface elevation is computed based on permitting analysis determine hydraulic impacts specifications, namely EC 1165-2-216. It is used to compute changes in water for Section 408 permit surface elevation between the baseline and with-project conditions to assess Section 408 hydraulic impacts.
This water surface elevation may differ from DWSEULDC because it is determined based on flow routing assumptions from EC 1165-2-216 rather than the ULDC.
3.2.4. Overview of the H&H/R&U Analysis The major analysis steps for the H&H/R&U analysis are as follows:
1. Compute DWSEULDC for determination of top of setback levee. 2. Determine stage increases for multiple with-project conditions. 3. Determine whether C-AEP decreases for multiple with-project conditions. 4. Determine changes in velocities to inform revetment design 5. Revise project features and iterate if needed.
Table 3-2 includes a summary of these steps including the basis for the analysis specifications, questions that must be answered, and models and levee configurations used to answer those questions.
Agenda Item No. 11B Attachment C - Design Documentation Report For this design, the following major tasks were completed:
• Re-simulated the HEC-RAS 2-D models based on the revised grading plan for the setback area. This analysis was used to assess potential erosion impacts and is included as an attachment to Appendix H-5. • Sacramento Area Flood Control Agency (SAFCA) provided a more-detailed interior drainage alternatives analysis, which is included in Appendix H-4.
Agenda Item No. 11B Attachment C - Design Documentation Report
Table 3-2: Overview of H&H/R&U analysis Major analysis Basis of Questions that must be answered Model1 SPFC levee configuration step analysis specifications Compute ULDC The setback levee will be a non-urban levee designed based on Baseline • Urban TOL = Infinitely high DWSEULDC for DWSEULDC100. To determine DWSEULDC100, however, upstream (and 1D HEC- • Non-urban TOL = higher of determination downstream) urban levees must first be raised to DWSEULDC200 plus 3 RAS authorized or existing of top of ft of freeboard according to the ULDC. Thus, the first question that model setback levee must be answered is: What is DWSEULDC200 upstream (and downstream) of the project site? To determine this, flows are routed through the system assuming that urban levees are infinitely high. Urban top of levee elevations are then determined by adding 3 ft to DWSEULDC200. Once urban and non-urban levee heights are configured according to Baseline u/s (and d/s) of project site:
the ULDC, the next question to answer is: What is DWSEULDC100 at the 1D HEC- • Urban TOL = DWSEULDC200 + project site? RAS 3 ft To determine this, flows are routed down to the project site with the model • Non-urban TOL = higher of ULDC TOL levee assumptions in place upstream. (Here, the upstream authorized or existing levee assumption is key to flow delivery to the project site. Results downstream of the project site are not relevant.) At project site:
In addition, DWSEULDC200 at the project site is also computed in a • Infinitely high levee similar manner to evaluate the resiliency of the system without performing additional climate change analyses. According to the ULDC, wave run-up should be considered when — At project site:
determining the top of levee for design. Thus, the next question is: • DWSEULDC100 + 6 ft, setback What is the potential wave run-up at the project site with the project alignment in place? To compute this, hydraulic routing model results and separate calculations considering wind data are used.
Finally, given the computed DWSEULDC100 and estimated wave run-up, — — the next question is: What is the top of setback levee? To determine this, freeboard (max of 6 ft per ULDC) is added to DWSEULDC100 considering wave run up.
Agenda Item No. 11B Attachment C - Design Documentation Report
Determine EC 1165-2-216 Once the top of the setback levee is determined, the analysis shifts to Baseline u/s and d/s of project site: stage and PR 71 permitting analysis specifications. Instead of urban levees raised to and with- • Urban TOL = higher of increases with DWSEULDC200 plus 3 ft, the top of urban levees is the higher of the project 1D authorized or existing (or project authorized or existing elevation. (However, to limit the number of HEC-RAS ULDC configuration of configurations, the previous ULDC configuration with urban levees models DWSEULDC200 + 3 ft can be raised to DWSEULDC200 + 3 ft can be used if this configuration yields used if this configuration water surface profiles with negligible differences for large events yields water surface used to define the upper end of the frequency curve.) profiles with negligible As part of the hydraulic impact analysis, the first question is: What is differences) the change in stage from the baseline to with-project conditions for a • Non-urban TOL = higher of range of events throughout the study area? authorized or existing To determine this, flows are routed through the channel routing model configured based on the permitting analysis specifications. At project site: • Baseline: existing • With-project: as determined in previous step, setback alignment
Determine EC 1165-2-216 The H&H analysis results will be used as input to the R&U analysis HEC-FDA Baseline and with-project whether C- and PR 71 where a risk analysis model will be used to compute C-AEP (and CNP) baseline conditions:
AEP changes at specified impact areas. The question here is: What is the change in and with- • Top of levee or DWSE1957 with project C-AEP relative to the ’57 design or top of levee (whichever is project (whichever is greater) greater)? models To determine this, the risk analysis model is configured with top of levee elevations or DWSE1957 so that the probability of exceeding this elevation can be computed for the baseline and with-project conditions. Determine EC 1165-2-216 Lastly, with the setback levee alignment in place, velocities may Baseline n/a, inflows to this localized change in and PR 71 increase locally. A 2D hydraulic routing model will be used to evaluate and with- model are from the simulations velocity, scour velocity changes in the project area. This question will be answered: project 2D used to determine stage on training Do velocities increase at these locations with the setback alignment? hydraulic increases levee To determine this, a range of flows will be routed through the 2D routing model. (If so, changes to the design will be considered.) models 1Baseline and multiple with-project evaluation scenarios are defined in Appendix H-1: Hydrologic and Hydraulic System Performance Analysis Ground Rules. 2SPFC = State Plan of Flood Control. Non-SPFC levee-like embankments are modeled as the existing condition. Agenda Item No. 11B Attachment C - Design Documentation Report
3.2.5. Hydrology
3.2.5.1. Products and Tools The Central Valley Hydrology Study (CVHS) products and tools were applied to develop the hydrology. The CVHS was a joint project conducted by the USACE and DWR to support future planning and implementation efforts to reduce flood risk in the Central Valley. The CVHS developed products and tools that can be applied for developing design storm hydrographs, water surface elevations, and supporting risk analysis studies. This includes use of four specified historic flow patterns and the various scaled versions of that dataset.
As specified by the analysis ground rules in Appendix H-1, CVHS tools were used to perform reservoir simulations, including reservoir operating rules and starting conditions, using the USACE Hydrologic Engineering Center (HEC) ResSim software. The Task Order (TO) 34 HEC-RAS model for the Sacramento system was used for hydraulic routing of the flows downstream as described in Section 3.2.6.
3.2.5.2. Reservoir Simulation The CVFPP/BWFS Sacramento River HEC-ResSim system model (originally developed for CVHS by DWR and USACE) was updated for this analysis. Specifically, the forecast-based operation at Folsom Reservoir, which incorporates the new spillway and the proposed dam raise, was configured into the model. For the operations with the dam raise, the USACE model as of 12/7/2016, referred to as configuration of R702F3, was used. The reservoir operation baseline condition and all with-project conditions are the same (as specified by the analysis ground rules in Appendix H-1, so one model was developed. The selected events (as described in Section 3.2.5.3) were simulated using the updated reservoir operation model.
3.2.5.3. Event Selection The scaled event selection is based on the process utilized for the Sacramento BWFS to support CVFPP 2017. During the process, DWR ran the full set of CVFPP Baseline HEC-RAS models. The full set of models comprised of varying scales of historic flood events of 1956, 1965, 1986, and 1997. The simulated models were run without levee breaches while allowing overtopping. In-channel regulated flow-frequency curves were computed throughout the Sacramento system for 15 index points on the main river stems and bypasses. Combined regulated flow-frequency curves were computed from the four storm patterns. Since the 1997 storm was found to be the dominant event among the four observed, the 1997 scaled event that produced similar peak flows as the combined regulated flow-frequency curve was chosen to represent the 100- and 200-year Agenda Item No. 11B Attachment C - Design Documentation Report
recurrence interval flows. As shown in Table 3-3, for the median representation of the Yolo Bypass system hydrology, two scaled historic events were chosen- the 1997 x 95% and 1997 x 110%, which approximately correspond to the 100- and 200-year flows respectively. A separate at-latitude flow frequency analysis was conducted at the project location that concurred with the selected design events.
These scaled events were used for documenting the stage and flow changes for the baseline and with-project conditions and for setting the preliminary design water surface profiles.
Agenda Item No. 11B Attachment C - Design Documentation Report
Table 3-3: Event Selection for 100- and 200-yr Events (Based on Analysis Performed for the Sacramento BWFS) Combined Regulated Event based Peak Flow Frequency Curve Peak CVFPP (cfs) Bypass Location of Index Flows (cfs) Dominant Scale Scale Scenario Index point Event 100-yr 200-yr Point Q100-yr Q200-yr Q100-yr Q200-yr
SAC15 Yolo Bypass d/s of KLRC 382,866 412,344 1997 0.95 1.05 388,985 414,535 Yolo Bypass u/s of Sac SAC35 401,553 432,176 1997 0.95 1.1 402,560 445,638 EX Bypass Yolo Bypass d/s of I-80 SAC17a 499,540 536,139 1997 0.95 1.05 507,087 536,047 Bridge SAC15 Yolo Bypass d/s of KLRC 383,136 415,112 1997 0.95 1.05 389,396 415,129 Yolo Bypass u/s of Sac SAC35 401,653 433,177 1997 0.95 1.1 402,737 447,172 EWP Bypass Yolo Bypass d/s of I-80 SAC17a 506,738 543,394 1997 0.95 1.05 514,076 543,842 Bridge SAC15 Yolo Bypass d/s of KLRC 379,584 409,926 1997 0.95 1.05 386,055 411,903 Yolo Bypass u/s of Sac SAC35 398,125 429,228 1997 0.95 1.1 399,335 444,031 FWP Bypass Yolo Bypass d/s of I-80 SAC17a 511,508 548,744 1997 0.95 1.05 519,387 549,478 Bridge
Selected Scaled Event based on in-channel flow frequency analysis for 1997 0.95 1.1 Sacramento Basin with focus on 3-index points at LEBLS Site Note: A separate at-latitude flow frequency analysis was conducted at the project location that concurred with the selected design events Agenda Item No. 11B Attachment C - Design Documentation Report
3.2.6. Hydraulics
3.2.6.1. One-Dimensional Hydraulics Model
3.2.6.1.1. Model Selection Hydraulic modeling is used to route the flows downstream through the river basin to generate design water surface profiles, compare baseline and with-project peak stages and flows, and generate frequency and rating relationships for the conditional risk analysis. Details for the assumptions used for the hydraulic modeling are included in Appendix H-1.
The hydraulic model that was selected is referred to as the Task Order 34 Sacramento River Routing HEC-RAS model or “TO 34 SRR model.” The TO 34 SRR model was enhanced from the Central Valley Floodplain Evaluation and Delineation (CVFED) TO 25 model by extending the river reaches to upstream forecast points, gages, and flood control reservoirs. The TO 34 SRR model extents are shown in Figure 2. The TO 34 SRR model was developed and simulated using HEC-RAS version 4.2 Beta. The hydraulic models were converted to version 5.0.3 due to unavailability of version 4.2 Beta from the USACE Hydrologic Engineering Center website. Version 5.0.3 is the latest available version and has latest upgrades to the HEC-RAS software. There were no significant differences in the model results due to upgrading the models from version 4.2 Beta to 5.0.3.
3.2.6.1.2. Calibration and Validation The TO 25 CVFED model, from which the TO 34 model was enhanced, was calibrated for the 1997 and 2006 flood events and reviewed and accepted by the USACE Sacramento District (SPK) as part of the CVFED program. The TO 34 model differs from the TO25 CVFED model in that some additional upstream reaches were added. The TO 34 model was validated by comparing the 1997 and 2006 events with recorded gage data and high water marks. Changes to rating curves at the gages (due to scour or deposition) was not identified as a concern. Generally, the computed and observed hydrographs matched well and thus the model was adopted for use here. A few of the gages did not match very well. This could be a result of incorrect datums; however, this could not be confirmed. The results of the model validation are included in Appendix H-2. Agenda Item No. 11B Attachment C - Design Documentation Report
3.2.6.1.3. Downstream Boundary Condition Downstream boundary conditions for the selected events were determined as specified by the analysis ground rules described in Appendix H-1. The downstream stage hydrographs at Sacramento River, Threemile Slough and Georgiana Slough are represented by observed stage hydrographs during the 1997 storm event, which were obtained from USACE.
For the full suite of model runs the constant water surface elevation was used as the downstream boundary for all of the scaled models. The constant stage was selected as the maximum stage during a 10-year event. In order to represent the effect of tidal boundary condition for the index points affected by the tidal effect a total of ten scaled events from 1956, 1965, 1986 and 1997 historic events were selected to use the scale specific dynamic boundary conditions at the downstream end.
These dynamic downstream boundary conditions were developed from the RMA2 Bay-Delta model simulations that most-closely correspond with the selected events.
The RMA2 Bay-Delta model is a 2D, finite-element model that solves for depth-averaged velocity and stage throughout the model domain under the influence of tidally varying water levels at the ocean boundary; river and agricultural inflows; and diversions and exports from the system. The model has been calibrated and widely used in hydrodynamic and salinity transport studies in the Delta. The RMA2 model covers the region of the Delta under tidal influence, extending south from the junction of the Sacramento and American Rivers, north from Vernalis on the San Joaquin River, and east from the Golden Gate.
The dynamic tidal downstream boundary stages at Threemile Slough, Georgiana Slough, and Collinsville were determined in two steps. First, system-wide Sacramento and San Joaquin HEC-RAS models were run with constant stage boundary conditions at the aforementioned three locations for the Sacramento system and all downstream stage boundary locations for the San Joaquin system. The upstream flow boundaries for the RMA2 Delta model in the Sacramento system are based on the following RAS computed flows:
• Sacramento River downstream of the American River • Yolo Bypass • Deep Water Ship Channel Agenda Item No. 11B Attachment C - Design Documentation Report
• Levee overtopping from the American River towards the south
Similarly, the upstream flow boundaries for the RMA2 Delta model in the San Joaquin system are based on the following RAS computed flows:
• San Joaquin River near Vernalis • Spills from the Stanislaus River towards the north • Overbank flows to the east and west through lateral weirs between the Stanislaus River and the San Joaquin River • Flows at eastern tributaries (Cosumnes River, Mokelumne River, and Calaveras River).
In the second step, the RMA2 Delta model was run with a dynamic tidal boundary at the Golden Gate Bridge and flow boundary conditions upstream at the Sacramento and San Joaquin Rivers. The RMA2 model runs will give dynamic tidal downstream boundary conditions at the desired three locations. For the ten selected scaled events for dynamic downstream boundary conditions, the stage hydrographs were taken from the 2017 CVFPP hydraulic modeling due to the similarities in the hydraulics between the CVFPP 2017 model and LEBLS project.
3.2.6.1.4. Existing Condition Model The Baseline Condition HEC-RAS model includes the existing conditions plus the authorized and funded projects (Early Implementation Projects). The projects include the Folsom Joint Federal Project (JFP) improvements and new dam operation guidelines as well as several levee improvement and setback projects throughout the basin. These detailed projects are listed in Appendix H-1 and shown on the map in Figure 3. Some elements of the American River Common Features GRR recommended plan/ locally-preferred plan (LPP) are included- minor levee raises along the Sacramento River, Arcade Creek, and Magpie Creek. The Sacramento Weir extension and Sacramento Bypass setback are not included.
The projects that required geometry updates for the Baseline Condition model are listed below:
• Hamilton City Flood Damage Reduction and Ecosystem Restoration Project Phase 1: This project is located on the west levee of the Sacramento River at Hamilton City. The project comprises of construction of a 6.8 mile setback levee to provide flood protection to the community and agricultural areas. As Agenda Item No. 11B Attachment C - Design Documentation Report
shown in Figure 3, the setback and levee raise has been applied to the Baseline Condition geometry from Sacramento River Mile (RM) 200.782 to RM 198.262. • TRLIA Feather River Levee Improvement Project: Feather River east levee was setback from RM 104.85 to RM 97.50. • Star Bend Levee Setback: Feather River west levee was setback at RM 98.6 for 0.75 Mile. • Bear River Levee Setback: Bear River north levee was setback from RM 3.4 to RM 1.43. • Natomas Levee Improvement Project (NLIP): o Sacramento River east levee was raised from RM 78.933 to RM 67.132. o Natomas Cross Canal south levee was raised from RM 5.162 to RM 0.154 o Pleasant Grove Canal south levee was raised from RM 0.55 to RM 0 • Southport Levee Improvement Project: Sacramento River west levee was setback from RM 56.8 to RM 52.6.
For this and every other scenario, levees could overtop but not fail per EC 1165-2-216 (USACE, 2015).
3.2.6.1.5. Existing With-Project Condition Model The Existing With-Project (EWP) Condition RAS model is the same as the Existing Condition model with the addition of the levee setback along the Yolo Bypass and Sacramento Bypass as part of the LEBLS project. The project location is shown in Figure 1. The remnant levees are left in the cross-section data, but the lateral structures are placed at the new setback location to represent the additional conveyance area.
3.2.6.1.6. Future Without-Project Condition Model The Future Without-Project (FWOP) Condition RAS model is the same as Existing Condition model with the addition of Sacramento Bypass setback and Sacramento Weir expansion by 1,500 feet.
3.2.6.1.7. Future With-Project Condition Model The Future With-Project (FWP) Condition RAS model is the same as FWOP condition model with the addition of the levee setback along the Yolo Bypass as part of the LEBLS project. Similar to the EWP Condition model, the remnant levees are left in the cross-section data, but the lateral structures are placed at the new setback location to represent the additional conveyance area.
Agenda Item No. 11B Attachment C - Design Documentation Report
3.2.6.1.8. Intermediate Cumulative Analysis Condition Model The Intermediate Cumulative Analysis Condition RAS Model is the same as FWP model with the following features added from the March 2016 draft of the Sacramento BWFS recommended option:
• Fremont Weir Expansion and Upper Elkhorn Basin Levee Setback, • Lower Yolo Bypass Levee Setbacks south of RD 2068, • Degrade levees at Yolo Bypass RM 26, Prospect Island, and Lower Egbert, • Incorporate ecosystem features in the levee setback areas.
3.2.6.1.9. With-Project Cumulative Condition Model The With-Project Cumulative Condition RAS model is the same as the Intermediate Cumulative Analysis Condition model with the following features added from the March 2016 draft of the Sacramento BWFS recommended option:
• West Side Yolo Bypass Levee Setbacks, • 4,000 feet levee setback north of Willow Slough Bypass, • 5,000 feet levee setback north of Putah Creek, • Deep Water Ship Channel Tie-In with gated weir, • Incorporate ecosystem features in the additional levee setback areas.
A map showing these cumulative improvements is included in Figure 4.
3.2.6.1.10. Hydraulic Impacts – Stages The LEBLS project changes the dynamics of local hydraulic conditions in various ways. Comparing Existing With-Project model with the Existing Condition, it was noticed that it changes the flow-split at the Fremont Weir between Yolo Bypass and Sacramento River. The flow diverted to the Sacramento Weir also changes due to the LEBLS project changes. The stage reduces at Yolo Bypass downstream of Fremont Weir as well as at Verona. The reduced stage does not translate to reduced flow at Sacramento River near Verona. While there is a slight increase of flow towards Sacramento River and slight decrease of flow at Yolo Bypass downstream of Fremont Weir, the reduced stage was created by expansion of Yolo Bypass due to LEBLS project and also due to Sacramento Bypass setback. This is a complex network where American River flows in a reverse direction from the confluence with Sacramento River to the Sacramento Weir and eventually to the Yolo Bypass. These Agenda Item No. 11B Attachment C - Design Documentation Report
changes in the local hydraulic pattern are reflected in the comparison of peak stages at the indicator locations as shown in Figures 5 and 6.
Figures 5 and 6 also show that the stage reduction in the Yolo Bypass is more pronounced in the vicinity of the LEBLS project and that the effect propagates upstream to the Fremont Weir. The stage reduction in the Yolo Bypass continues until the confluence with the Sacramento Bypass, where the stage reductions are neutralized by increased backwater from the Sacramento Bypass flow. Downstream of the Sacramento Bypass, nominal stage increases in the Yolo Bypass results from the increased Sacramento Bypass flow under the Existing With-Project Condition. Along the Sacramento River, stage reductions occur downstream of the Fremont Weir because of Sacramento Weir diverting more flow towards the Sacramento Bypass due to expanded Sacramento Bypass and Yolo Bypass at LEBLS project location under the Existing With-Project Condition.
As shown in Figures 7 and 8, for the Future Without-Project Condition, the hydraulic impacts are similar to that of Existing With-Project Condition due to the similar flow split changes at the Fremont Weir and Sacramento Weir.
Figure 9 and 10 shows the hydraulic impacts of Future With-Project Condition where the flow and stage differences are similar to the previous two conditions but with slightly greater magnitude.
Figure 11 and 12 shows the hydraulic impacts of Intermediate Cumulative Analysis. The flow and stage differences are similar to the previous conditions but with slightly different magnitude. This is probably due to the additional improvements added to the hydraulic condition of the system.
Figure 13 and 14 shows the hydraulic impacts of With-Project Cumulative Condition. The flow and stage are greatly reduced in this condition at all indicator locations due to several levee setbacks throughout the system.
Additional hydraulic model results, including comparisons of peak flows, are included in Tables 1-4 in Appendix H-10.
The 1957 design flows were not explicitly modeled; however, it can be assumed that the impacts for those flow conditions would be less than Agenda Item No. 11B Attachment C - Design Documentation Report
the approximate 100-yr since those modeled bypass flows are less than the 100-yr.
3.2.6.1.11. Design Water Surface Elevations The preliminary design water surface profiles for the selected events are shown in Figures 15 and 16 (for the Yolo Bypass and Sacramento Bypass). The stages within the Yolo Bypass are reduced from RM 56 to RM 47 as shown in Figure 15 due to the project setback. The stage reduction is more widespread in the with-project cumulative condition model with the recommended options’ levee setback and Fremont Weir expansion. The final design will be based on the evaluation scenario that produces the maximum water surface elevations plus freeboard (or wind setup and wave-run-up heights).
3.2.6.2. Two-Dimensional Hydraulics Model The Two-Dimensional (2D) model is needed to evaluate the potential for geomorphic changes in the project area (see Appendix H-5), erosion and scour potential, and to inform the revetment design for LEBLS.
3.2.6.2.1. Model Selection The 2-D model was taken from the Yolo and Sutter Bypass 2D model prepared for Task Order 15-12 (TO 15-12). This model includes the entire Sutter Bypass and Yolo Bypass between the levees represented as two-dimensional area using 400-feet square grids. Other major rivers such as portions of Sacramento River and American River were modeled as one-dimensional.
3.2.6.2.2. Calibration and Validation The TO 15-12 model was calibrated for the 1997 storm event along the Sutter and Yolo Bypass.
3.2.6.2.3. Baseline Model The baseline model was not modified for Early Implementation Projects since the two-dimensional model extent was limited to Sutter and Yolo Bypasses.
3.2.6.2.4. Future Without-Project Model The Sacramento Weir and Bypass were both expanded by 1,500 feet to represent the Future Without-Project Model.
3.2.6.2.5. Future With-Project Model In addition to the Sacramento Weir and Bypass expansion, the Future With-Project model also includes Yolo Bypass expansion per the LEBLS project. Agenda Item No. 11B Attachment C - Design Documentation Report
3.2.6.2.6. Existing With-Project Model In addition to the baseline model, the LEBLS was added.
3.2.6.2.7. Results The 2-D model results for the Baseline, Future Without-Project, and Future With-Project are shown in Appendix H-5: Geomorphic Analysis. In addition to those results, additional verification runs were made with the Existing With-Project Model and are included as an attachment to Appendix H-5. For more information on the erosion analyses, including revetment considerations, see the Geotechnical Basis of Design (GBOD), Appendix G-1.
3.2.6.3. Alternate Sacramento Bypass Alignment The levee setback locations for Sacramento Bypass north levee were evaluated for several alignments due to the geotechnical considerations of the project. The detailed sensitivity analysis of the Sacramento River Bypass north levee alignment is included in Appendix H-9.
3.2.7. Conditional Risk Analysis DWR assessed the impacts of the LEBLS Project by comparing performance metrics for the authorized condition with performance metrics for the condition resulting from the project alteration. Those metrics are (1) conditional annual exceedance probability (C- AEP), which is the probability that the authorized design water surface elevation or top- of-levee, whichever is higher at the index point, is exceeded in any given year; and (2) assurance, also known as conditional non-exceedance probability (C-A). C-A is the probability that the authorized design water surface elevation or top-of-levee will not be exceeded in any given year. A significant increase in C-AEP or decrease in C-A suggests project features lead to an unacceptable change.
The authorized design water surface elevations, herein referred to as DWSE1957, for the LEBLS Project are established in USACE Sacramento District file 50-10-3334, dated March 15, 1957. The water surface profiles shown on these sheets are known as the DWSE 1957 or, more commonly, the ’57 profile which includes freeboard and varies between the rivers and bypasses. The top-of-levee information was obtained from the HEC-RAS CVFED TO 34 Model used in the 2017 CVFPP. Thus, the fundamental question that this analysis will answer is: What is the change in C-AEP, and C-A, due to the project relative to the authorized condition of the system based on the higher of either the DWSE1957 or top-of-levee for the selected index points, and are those changes significant?
The Existing, Existing with Project, and Future with Project modeling scenarios were evaluated to assess the potential impacts of the LEBLS. For a given scenario, 216 channel model simulations (120 using “best estimate” values and 96 for the sensitivity analysis) Agenda Item No. 11B Attachment C - Design Documentation Report
were completed. From those simulations, the peak flows and stages were extracted to develop the necessary inputs to HEC-FDA and evaluated using a target of the DWSE 1957. The C-AEP and C-A was computed and compared at 18 index locations for 2 evaluation scenarios using the Corps’ HEC-FDA version 1.4.1 software for the computations.
The computed C-AEP values are shown in Table 3-4: Project Performance Results. The impact of the LEBLS modeling scenarios is defined as the difference between the EWP or FWP scenario and Existing conditions scenario. Sixteen of the eighteen index points show either no change or a reduction in the C-AEP. Finding no appreciable difference in C-AEP is reasonable for these index points because at the target stage, there is no appreciable difference in the input functions for the EWP and FWP scenarios. Index points SAC17a and Rio Vista show small increases in the C-AEP as a result of the EWP and FWP scenarios. For the SAC 17a outflow-stage relationship, it did not exceed the target stage and would not cause an impact. For the index point at Rio Vista, a small increase in the C-AEP of 0.0002 was found in the EWP and FWP scenarios. These small increases can be attributed to small differences in the inflow-outflow relationships, outflow-stage relationships, and uncertainty distributions associated with both relationships. While there are small increases in the C-AEP relative to the target stage at this index point, the ULDC (May 2012) level of protection is still met in the EWP and FWP scenarios relative to the existing top of levee at these index points. For a given maximum flow, the corresponding peak stage increases in the EWP and FWP scenarios are documented in Appendix H-7: Conditional Risk Analysis.
Agenda Item No. 11B Attachment C - Design Documentation Report
Table 3-4: Project Performance Results Target Stage Annual Change in Modeling Scenarios Index Modeling Exceedance Probability (EWP, FWP - Existing) Point Scenario Median C-AEP 1 / C-AEP Median C-AEP 1 / C-AEP Existing 0.0001 0.0025 400 SAC14 EWP 0.0001 0.0023 435 0.0000 -0.0002 0 FWP 0.0001 0.0019 526 0.0000 -0.0006 126 Existing 0.0001 0.0002 5,000 SAC14a EWP 0.0001 0.0002 5,000 0.0000 0.0000 0 FWP 0.0001 0.0002 5,000 0.0000 0.0000 0 Existing 0.0001 0.0003 3,333 SAC15 EWP 0.0001 0.0002 5,000 0.0000 -0.0001 1667 FWP 0.0001 0.0002 5,000 0.0000 -0.0001 1667 Existing 0.0001 0.0003 3,333 SAC16 EWP 0.0001 0.0002 5,000 0.0000 -0.0001 1667 FWP 0.0001 0.0002 5,000 0.0000 -0.0001 1667 Existing 0.0001 0.0003 3,333 SAC17a EWP 0.0001 0.0004 2,500 0.0000 0.0001 -833 FWP 0.0001 0.0005 2,000 0.0000 0.0002 -1333 Existing 0.0001 0.0002 5,000 SAC34 EWP 0.0001 0.0002 5,000 0.0000 0.0000 0 FWP 0.0001 0.0002 5,000 0.0000 0.0000 0 Existing 0.0002 0.0013 769 SAC35 EWP 0.0002 0.0012 833 0.0000 -0.0001 64 FWP 0.0002 0.0013 769 0.0000 0.0000 0 Existing 0.0002 0.0080 125 SAC35a EWP 0.0001 0.0066 152 -0.0001 -0.0014 27 FWP 0.0001 0.0050 200 -0.0001 -0.0030 75 Existing 0.0001 0.0003 3,333 SAC36a EWP 0.0001 0.0002 5,000 0.0000 -0.0001 1667 FWP 0.0001 0.0002 5,000 0.0000 -0.0001 1667 Existing 0.0001 0.0006 1,667 SAC36 EWP 0.0001 0.0003 3,333 0.0000 -0.0003 1667 FWP 0.0001 0.0002 5,000 0.0000 -0.0004 3333 Existing 0.0001 0.0004 2,500 SAC38 EWP 0.0001 0.0002 5,000 0.0000 -0.0002 2500 FWP 0.0001 0.0002 5,000 0.0000 -0.0002 2500 Agenda Item No. 11B Attachment C - Design Documentation Report
Target Stage Annual Change in Modeling Scenarios Index Modeling Exceedance Probability (EWP, FWP - Existing) Point Scenario Median C-AEP 1 / C-AEP Median C-AEP 1 / C-AEP Existing 0.0001 0.0002 5,000 SAC38a EWP 0.0001 0.0002 5,000 0.0000 0.0000 0 FWP 0.0001 0.0002 5,000 0.0000 0.0000 0 Existing 0.0001 0.0006 1,667 SAC38b EWP 0.0001 0.0004 2,500 0.0000 -0.0002 833 FWP 0.0001 0.0002 5,000 0.0000 -0.0004 3333 Existing 0.0001 0.0006 1,667 SAC42 EWP 0.0001 0.0003 3,333 0.0000 -0.0003 1667 FWP 0.0001 0.0002 5,000 0.0000 -0.0004 3333 Existing 0.0002 0.0016 625 SAC44 EWP 0.0001 0.0010 1,000 -0.0001 -0.0006 375 FWP 0.0001 0.0004 2,500 -0.0001 -0.0012 1875 Existing 0.0002 0.0016 625 SAC45 EWP 0.0001 0.0010 1,000 -0.0001 -0.0006 375 FWP 0.0001 0.0004 2,500 -0.0001 -0.0012 1875 Existing 0.0001 0.0002 5,000 SAC52 EWP 0.0001 0.0002 5,000 0.0000 0.0000 0 FWP 0.0001 0.0002 5,000 0.0000 0.0000 0 Existing 0.0001 0.0002 5,000 SAC55 EWP 0.0001 0.0002 5,000 0.0000 0.0000 0 FWP 0.0001 0.0002 5,000 0.0000 0.0000 0 Existing 0.0001 0.0002 5,000 SAC59a EWP 0.0001 0.0002 5,000 0.0000 0.0000 0 FWP 0.0001 0.0002 5,000 0.0000 0.0000 0 Existing 0.0024 0.0029 345 SAC63 EWP 0.0024 0.0029 345 0.0000 0.0000 0 FWP 0.0023 0.0026 385 -0.0001 -0.0003 40 Existing 0.0022 0.0033 303 Rio Vista EWP 0.0024 0.0035 286 0.0002 0.0002 -17 FWP 0.0025 0.0035 286 0.0003 0.0002 -17
3.2.8. Wind Setup and Wave Run-up This analysis is required to assess the potential increase in stage along the levees due to wind setup and wave run-up. The analysis and results are included in Appendix H-3. Agenda Item No. 11B Attachment C - Design Documentation Report
3.3. Groundwater
3.3.1. Hydrogeologic and Groundwater Conditions
3.3.1.1. Regional Geology The Lower Elkhorn Basin lies within the California’s Sacramento Valley, a vast area of sediments and low relief. The Sacramento Valley makes up the northern part of the Central Valley, an approximately 400-mile-long and 50-mile-wide, structurally controlled basin (Helley and Harwood, 1985) filled with thousands of feet of marine and non-marine sediment dating from the late Jurassic through the Holocene periods. The eastern and western sides of the valley are dominated by broad coalescing alluvial fans that developed during the late Quaternary. The central part of the valley is dominated by expansive plains, with broad natural levees bounding the Sacramento River and its main channels, and extensive low-lying basins outboard of natural levees at the lowest elevations in the valley such as, the Butte, Colusa, Sutter, American, Sacramento, and Yolo basins.
Two major rivers, the Sacramento and American rivers flow through or near the area and drain runoff from the Sierra Nevada range. The Basin is located near the confluence of these two major rivers.
The American River tends to carry more granular material than the Sacramento River due to differing sediment source areas, distances to those sources, and gradients. Fine-grained sediments are generally present west of the Sacramento River upstream of the confluence, and granular soils are more prevalent downstream of the confluence. Both rivers tend to have natural levee structures with associated crevasse splay deposits (a sedimentary fluvial deposit that forms when a stream breaks its natural or artificial levees and deposits sediment on a floodplain) of sand near the rivers, and clay backwater deposits further from the rivers. This pattern is interrupted where old meander loops have been backfilled with either clay or sand.
3.3.2. Groundwater Conditions
3.3.2.1. Groundwater Levels and Flows Groundwater levels along the new setback levee alignment are largely controlled by the stages of the Sacramento River, Sacramento Bypass, and Yolo Bypass.
According to the California Groundwater Information Center Interactive Map Application (https://gis.water.ca.gov/app/gicima/), the depth to groundwater Agenda Item No. 11B Attachment C - Design Documentation Report
ranges from 10 to 20 feet in the Lower Elkhorn Basin; however, groundwater was encountered as shallow as 4 to 10 feet below the ground surface in several test pit explorations. The available data provides contours for spring and fall quarters only. The gradient in the spring is relatively flat across the Basin area and deepens to 30 feet to the west in the Yolo Bypass channel, likely due to recharge from the Sacramento River.
During the fall and late summer, areas of drawdown are evident within the Yolo bypass channel to the west. These are localized around the active irrigation wells. The drawdown depths range from 60 feet to 130 feet, but these cones of depression do not extend east into the project area.
3.3.3. Evaluation of Groundwater Conditions at Proposed Borrow Sites Evaluation of groundwater conditions is provided in the Borrow Data Report, Appendix G-3, attached. The Borrow Data Report includes groundwater conditions and piezometer data collected to date. In general, perched groundwater in the upper clay layer was encountered in test pit explorations as shallow as 4 to 10 feet below the ground surface. Additionally, confined groundwater conditions below the upper clay blanket layer were observed in piezometer data and several test pit explorations where groundwater was observed to rise several feet above the elevation it was first encountered.
3.4. Summary of Geotechnical Data and Evaluations The Geotechnical Basis of Design Report (GBOD) for the Lower Elkhorn Basin Levee Setback project is provided as Appendix G-1 to this Design Documentation Report (DDR). The geotechnical design elements of the project are primarily being performed by DWR staff and consultants. Consultants provided field geophysical testing and supplemental engineering services to support the levee setback project. The Safety Assurance Review (SAR) Panel and the USACE Levee Safety Program Manager are engaged to review geotechnical design milestones. Design team members are acknowledged in the GBOD, attached as Appendix G-1.
The following sections are intended to provide a summary of pertinent geotechnical findings, conclusions, and design recommendations.
The Geotechnical Data Report (GDR) is attached as Appendix G-2; the GDR contains geotechnical field data collected and lab test results. The Borrow Data Report is attached as Appendix G-3 and contains the field and laboratory data specific to the borrow area investigations. Agenda Item No. 11B Attachment C - Design Documentation Report
3.4.1. Proposed Setback Levee Overview
3.4.1.1. Lower Elkhorn Basin Site Description The 7 mile long levee setback project is located in the Lower Elkhorn Basin, just northwest of Sacramento, California. The Lower Elkhorn Basin is bounded by the Sacramento River on the east, the Sacramento Bypass on the south, the Yolo Bypass on the west, and Interstate 5 on the north.
The Lower Elkhorn Basin is primarily used for agricultural production of row crops (tomatoes, sun flowers, safflowers, etc.), alfalfa, and nut tree orchards. The Lower Elkhorn Basin population is generally less than 100 people, and has less than 100 building structures including farm buildings, permanent and temporary residences, pump houses, and commercial buildings. The basin includes several county roads, rural roads, drainage ditches, and an elevated rail road.
The Basin is subdivided by interior drainage ditches forming three sub basins identified as Reclamation Districts (RD), RD 537, RD 785, and RD 827. RD 537 covers the southeast half, RD 785 in the southwest half, and RD 827 in the north area. The RDs currently operate their own interior drainage ditches and pump systems for crop irrigation and interior drainage; however, in 2019 the three RDs consolidated to become RD 537. After the project completes, the consolidated RD 537 will operate a single larger pump station to discharge interior drainage from the basin. Ground surface conditions are relatively flat and range between Elevation 10 to 25 feet (NAVD 88).
3.4.1.2. Geometry and Onsite Borrow Materials The proposed setback levee will be designed and constructed in accordance with the State of California Code of Regulations Title 23 and USACE levee design criteria. According to Title 23, the geometry for bypass levees have a maximum steepness requirement of 4:1 (h:v) for waterside slopes, 3:1 for landside slopes, and a minimum crown width of 20 feet. The setback levee heights range between 20 and 26 feet.
Special Construction Details were designed in accordance with Title 23, Section 120, Paragraph 12, where soil properties required by Title 23 (i.e., Liquid Limit <50) are not readily attainable. Special Construction Details include:
• 4:1 (h:v) slopes for both waterside and landside slopes; less steep slopes improve stability allowing the use of locally sourced borrow materials that have higher Liquid Limits and Plasticity Indexes. Agenda Item No. 11B Attachment C - Design Documentation Report
• The setback levee foundation area will be over excavated to a depth of 3 feet and replaced with engineered fill. The bottom of the over excavation will be scarified an additional 8 inches and recompacted prior to placement of fill, for a total of 3.7 feet of foundation improvement. • 28-foot-wide crown to provide resiliency against potential seasonal shrinkage cracking and potential slope creep along the levee crest shoulder areas, thereby ensuring the minimum required 20-foot crown width is maintained over time. • Establish native grass vegetation with deep root structures to reduce potential for surficial slope creep and erosion.
The setback levee will be constructed from native borrow sources excavated within the project area, on the water side of the proposed levee alignment. The higher prevalence of fat clay with Liquid Limits over 50 in the project area will be mitigated by adopting 4:1 (h:v) side slopes, a wider crown, foundation area improvement, and the establishment of native grass vegetation having deep root systems on the levee slopes. The flatter slopes will increase the factors of safety and are expected to minimize potential maintenance associated with surficial sloughing associated with clay desiccation and softening. The wider crown adds resiliency to the levee prism, and the establishment of native grasses is anticipated to further minimize the potential for maintenance associated with erosion and surficial sloughing.
Utilizing onsite borrow material has significant environmental benefits versus importing borrow material. Using onsite borrow material is a more efficient use of limited resources and reduces overall environmental impacts by reducing negative impacts to air quality and regional roadway impacts associated with having to import over 6 million cubic yards from offsite borrow sources. Refer to the Borrow Data Report, Appendix G-3.
3.4.1.3. Design Water Surface Elevation and Levee Height The design water surface elevation (DWSE) for the Lower Elkhorn levee setback project is the 100-year water surface elevation. The levee heights are determined by the 100-year DWSE plus 6 feet of freeboard, plus one additional foot for potential future climate change adaptation/resiliency. In the GBOD report, the term geotechnical design water surface elevation (GDWSE) is used to identify the geotechnical design water surface elevation as being the 100-year plus 1 foot for geotechnical design analysis. The GDWSE approximately coincides with the 200-year water surface elevation. Agenda Item No. 11B Attachment C - Design Documentation Report
3.4.1.4. Rural Streets Existing rural streets will be reconstructed and/or relocated as part of the project. New pavement structural sections conform to Yolo County Improvement Standards.
3.4.1.5. Utility Penetrations and Existing Land Features Several utility pipe relocations and/or deepening efforts will be required to complete the project. Utility penetrations must comply with design requirements as defined by Title 23. An existing 12-inch diameter steel pipe that delivers jet fuel to Sacramento International Airport was relocated at least 50 feet below Sacramento Bypass and the setback levee alignment in 2019. AT&T will directional bore new fiber optic conduit approximately 20 feet below the setback levee at two locations. Utility relocations are designed and constructed by their owners. DWR is coordinating and reviewing all utility relocation plans and checking compliance with levee safety standards. The Bryte landfill site north of the Sacramento Bypass began relocation construction in 2019 and will complete in 2020.
3.4.2. Geotechnical Investigations and Background Information
3.4.2.1. Geotechnical Investigations To examine the feasibility of a levee setback and to obtain data for design level engineering analyses including seepage, slope stability, settlement, and erosion, geotechnical investigations were completed. The investigations included 182 borings, 117 cone penetration tests (CPT), three field vane shear tests, 72 test pit explorations for borrow study, in-situ and laboratory testing. In addition, approximately 14 miles of geophysical/soil resistivity survey lines (Figure 17) were performed; this data helped identify locations for geotechnical investigations. Refer to Appendix G-2, Geotechnical Data Report (GDR) for data obtained through geotechnical investigations.
The geotechnical investigation program was developed in compliance with the Geotechnical Levee Practice Standard Operating Procedure (SOP EDG-03) developed by the USACE (USACE, 2008) and Soil and Rock Logging, Classification, Description, and Presentation Manual developed by DWR, 2008. The geotechnical investigation plan was reviewed by the SAR Panel and the USACE Levee Safety Program Manager; comments were addressed and incorporated into the final plan.
The locations of the subsurface explorations were informed by previous geomorphologic studies and geophysical resistivity surveys (Figure 17). The project utilized the current practice of design exploration criteria with one exploration on average every 500 feet along the proposed levee alignment, and Agenda Item No. 11B Attachment C - Design Documentation Report
offset explorations left and right of the proposed alignment at the landside toe, waterside toe, and landside far field. Explorations for the landside toe and the landside far field were also spaced at approximately 500 feet intervals; waterside toe explorations were spaced at approximately 1000 feet intervals. Landside far field explorations were located approximately 300 feet from the landside toe of the proposed setback levee alignment. Design criteria require exploration depths to be at least three times the height of proposed levee, below the foundation, for centerline explorations. Refer to the GBOD report Appendix G-1 for the exploration locations.
Table 3-5: Exploration Depths and Spacing Location Target Depths Average Spacing Centerline 80 to 100 feet 500 feet Landside Toe 60 to 80 feet 500 feet Waterside Toe 60 feet 1000 feet Landside Far Field 50 to 60 feet 500 feet
Areas with past performance issues were evaluated along the existing levee or areas of concern with geomorphic features identified by the Reclamation Districts, along with existing boring data near the proposed exploration locations to confirm that the proposed locations provide the most useful data possible for levee design. Additional explorations and adjustments to exploration locations were made as necessary. In a few instances, additional explorations were completed based on comments from the SAR Panel and the USACE Levee Safety Program Manager.
3.4.2.2. Previous Geotechnical Studies and Reports No known borings were previously conducted within the project footprint or near the proposed setback levee alignment. A Geomorphic study covering the project area is available from the Non-urban Levee Evaluation (NULE) program, and further information relate to geomorphic study is provided in Section 3.4.2.4.
3.4.2.3. Existing Bypass Levee Construction and Past Performance The Sacramento Weir and Bypass levees were completed in 1916 by the City of Sacramento to divert flows from the Sacramento and American Rivers to the Yolo Bypass. DWR operates the weir according to regulations established by USACE. The opening and closing criteria have been optimized to balance two goals: (1) minimize sediment deposition due to decreased flow velocities downstream from the weir to the mouth of American River; and (2) limit the flooding of agricultural lands in the Yolo Bypass until after they have been inundated by floodwaters over Fremont Weir, north of the project area. Agenda Item No. 11B Attachment C - Design Documentation Report
Levee construction along the 40 mile long Yolo Bypass began in multiple areas between 1911 and 1917. The levees in the project area along the Yolo Bypass were completed around the same time as the Sacramento Bypass, and were constructed using clamshell bucket dredger, loosely depositing high plasticity clays (with organics) as the main embankment material. The clamshell excavation created what is known as the Tule Canal at the waterside toe of the Yolo Bypass levee. Available information indicates the foundation soils include soft to stiff clays with slickensides and organic lenses.
Based on review of existing data and past performance geotechnical levee distresses associated with the existing bypass levees include primarily slope instability due to wetting and drying of high plasticity clays with steep slopes.
3.4.2.4. Geomorphic Studies As presented in the Geomorphologic Technical Memoranda and Maps, North NULE Area Geomorphic Assessments (URS, 2011), Fugro William Lettis & Associates, Inc. (FWLA) performed a surficial geologic mapping and geomorphic assessment of the project area (FWLA, 2009) presenting the results of the assessment for the north NULE Program. The purpose of the surficial mapping and preliminary geomorphic assessment was to develop spatially-continuous geologic map data and a conceptual model for stratigraphic interpretations at and between borings.
In general, FWLA’s study involved:
• Integration and analysis of aerial photography. • Integration and analysis of topographic, geologic, and soil maps. • Reviewing other historical documents. • Reviewing readily-available geotechnical exploration data.
The results of FWLA’s geomorphic mapping and geomorphic assessment used in the GAR evaluations by the NULE program is included as an attachment to the GBOD. No updates were made to the geomorphic mapping; updating the geomorphic mapping is beyond the scope of design requirements for the LEBLS project.
3.4.3. Design Analyses Geotechnical design analyses have been completed for the proposed setback levee alignment. A brief discussion of analysis methodology, analysis results, and proposed design measures are provided below. Agenda Item No. 11B Attachment C - Design Documentation Report
3.4.3.1. Reach Selection Nine reaches are currently identified for design of the LEBLS project, namely Reaches A through I. Of those, two Reaches B and F were further subdivided into sub-reaches B1, B2, F1, and F2. Refer to the Geotechnical Basis of Design Report (GBOD), Appendix G-1, for detailed reach identification and analysis results.
In general, the proposed setback levee alignment was subdivided into reaches having similar geometric and subsurface conditions. The goal was to identify the minimum number of reaches that could represent the most critical geologic features for the proposed setback levee. Separate reaches and/or sub-reaches were identified when a major change in foundation conditions potentially affecting levee performance is noted. Reach selection and characterization was an iterative process of successive refinement. Reasons for identifying a separate reach include significant changes in levee geometry, including presence of a landside ditch, subsurface conditions, or levee performance during a highwater event. These conditions within each reach and/or sub-reach were then characterized by a transverse analysis cross section.
3.4.3.2. Geotechnical Evaluations Detailed discussion of reach selection, material properties, seepage and stability analysis, seismic evaluations, erosion, and settlement analysis are presented in the GBOD, Appendix G-1.
3.4.3.3. Material Properties Laboratory testing for moisture content, Atterberg limits, hydrometer, gradation, consolidation, shear strength, and compaction on selected soil samples was completed. Material properties used in the design were reviewed by the SAR Panel and USACE, and presented in the GBOD Report, Appendix G-1.
3.4.3.4. Analyses Criteria A Geotechnical Design Criteria and Approach Memorandum for the Lower Elkhorn Basin Levee Setback project was prepared, dated May 11, 2017 and updated February 12, 2018. Extracts from the design criteria and approach memo is reproduced throughout the text of the GBOD report and appended in full to the GBOD report, Appendix G-1.
3.4.4. Geotechnical Design Results The following sections provide a summary of geotechnical design results. Geotechnical design of the proposed setback levee is based on the 100-year Water Surface Elevation (WSE) plus 1 foot for resiliency/potential climate change adaptation and is referenced as the Geotechnical Design Water Surface Elevation (GDWSE) for the purpose of the geotechnical analysis. The 100-year WSE for the LEBLS Project was developed by DWR, Agenda Item No. 11B Attachment C - Design Documentation Report
Hydrology and Hydraulics design team. Recommended levee overbuild heights for foundation consolidation settlement were included for end of construction stability analysis. Refer to the Geotechnical Basis of Design Report (GBOD) Appendix G-1 for detailed geotechnical design results and analysis discussion.
3.4.4.1. Reach A – 106+26 to 118+75 The alignment for Reach A was moved south approximately 750 feet to avoid potential impacts to the Caltrans Interstate 5 corridor associated with drainage and 3D underseepage effects. Reach A is approximately 1,249 feet long with a proposed levee height of 23 feet. The design levee prism in Reach A did not meet underseepage and landside slope stability criteria at the GDWSE and requires un undrained seepage berm 250-foot-wide to mitigate underseepage (including 3D effects) and landside slope stability. To mitigate for foundation consolidation settlement, an overbuild height of 1.2 feet will be included in Reach A.
3.4.4.2. Reach B – 118+75 to 179+71 Reach B is approximately 6,096 feet long with proposed levee heights of 21 to 23 feet. Due to varying foundation conditions Reach B is further subdivided into sub reaches B1 (118+75 to 155+00, 3,625 feet long) and B2 (155+00 to 179+71, 2,471 feet long). The design levee prism in both Sub Reaches B1 and B2 did not meet underseepage and landside slope stability criteria at the GDWSE. Sub Reach B1 and Sub Reach B2 both require an undrained seepage berm 80-foot- wide. To mitigate for foundation consolidation settlement, an overbuild height of 1.2 feet will be included in Reach B.
3.4.4.3. Reach C – 179+71 to 248+43 Reach C is approximately 6,872 feet long with proposed levee heights of 21 to 23 feet. The design levee prism in Reach C meets the geotechnical criteria considered for design and does not require seepage berm improvements. To mitigate for foundation consolidation settlement, overbuild heights in Reach C vary from 0.7 to 1.4 feet; refer to the GBOD report, Appendix G-1, for specific station by station overbuild in Reach C.
3.4.4.4. Reach D – 248+43 to 280+13 Reach D is approximately 3,170 feet long with a levee height of approximately 23 feet. The design levee prism did not meet underseepage and landside slope stability criteria at the GDWSE. Thus, Reach D requires an undrained seepage berm 50-foot-wide. To mitigate for foundation consolidation settlement, an overbuild height of 0.7 feet is included in Reach D.
3.4.4.5. Reach E – 280+13 to 341+61 Reach E is approximately 6,148 feet long with proposed levee heights of approximately 23 to 25 feet. The design levee prism in Reach E meets the Agenda Item No. 11B Attachment C - Design Documentation Report
geotechnical criteria considered for design and does not require seepage berm improvements. To mitigate for foundation consolidation settlement, overbuild heights of 0.7 to 1.3 feet is included in Reach E; refer to the GBOD report, Appendix G-1, for specific station by station overbuild recommendations in Reach E.
3.4.4.6. Reach F – 341+61 to 407+80 Reach F is approximately 6,619 feet long with proposed levee heights of 24 to 26 feet. Reach F is further subdivided into sub reaches F1 (341+61 to 384+50, 4,289 feet long) and F2 (384+50 to 407+80, 2,330 feet long). The design levee prism in Sub Reach F1 meets criteria for underseepage and slope stability at the GDWSE. However, the proposed levee prism in Sub Reach F2 does not meet criteria for underseepage at the GDWSE (considering 3D underseepage effects), but it meets criteria for slope stability. Thus, Sub Reach F2 requires an undrained seepage berm 70-foot-wide. To mitigate for foundation consolidation settlement, an overbuild height of 0.8 feet is included in Reach F.
3.4.4.7. Reach G – 407+80 to 421+48 Reach G is approximately 1,368 feet long with a proposed levee height of approximately 25 to 26 feet. The design levee prism in Reach G meets the geotechnical criteria considered for design and does not require additional improvements. To mitigate for foundation consolidation settlement, overbuild heights of 0.8 to 0.9 feet is included in Reach G; refer to the GBOD report, Appendix G-1, for specific station by station overbuild in Reach G.
3.4.4.8. Reach H – 421+48 to 448+42 Reach H is approximately 2,694 feet long with levee heights of approximately 26 feet to 20 feet (decreasing to the east). The design levee prism in Reach H meets the geotechnical criteria considered for design and does not require additional improvements. To mitigate for foundation consolidation settlement, an overbuild height of 0.9 feet is included in Reach H.
3.4.4.9. Reach I – 448+42 to 477+15 Reach I is approximately 2,873 feet long with levee heights of approximately 21- 23 feet. Due to less favorable foundation conditions initially encountered parallel to the existing railroad embankment, an alternative alignment for Reach I was identified approximately 1,000 feet to the west (refer to site plan figures in the GBOD report, Appendix G-1). Explorations confirm more competent foundation conditions for this alignment. The design levee prism in Reach I meets criteria for underseepage at the GDWSE but does not meet criteria for slope stability. Therefore, Reach I requires an undrained stability berm 40-foot- wide. To mitigate for foundation consolidation settlement, an overbuild height of 0.7 feet is included in Reach I. Agenda Item No. 11B Attachment C - Design Documentation Report
3.4.5. Slope Protection Slope protection is recommended from approximately the 10-year WSE up to the crest of the levee to resist erosion due to wind-wave action. Additionally, the north levee tie- in to the Yolo Bypass will receive slope protection from levee toe to levee crest for approximately 1,000 feet, and the south tie-in at the Sacramento Bypass will receive a concrete liner from toe to crest for approximately 700 feet, connecting to the existing concrete liner.
Tied concrete block mats (TCBM) are suitable for slope protection in lieu of conventional Rock Slope Protection (RSP). Engineered products such as Flexamat or equivalent sources are recommended with the following justifications:
• TCBM can be manufactured onsite and requires significantly less truck loads to import the materials compared to the number of truck loads required to import RSP, thereby reducing air quality emissions and County roadway impacts. • TCBM provides ecosystem benefits and mitigation credits by allowing growth of native grass through the TCBM providing foraging habitat, while also providing the necessary slope protection. • TCBM is approximately one-half the cost per square foot when compared to a minimum 2 feet thick RSP and associated bedding layers.
3.4.6. Construction Recommendations Refer to the GBOD report, Appendix G-1, Section 8 for construction and earthwork recommendations that were incorporated into the construction plans and specifications, prepared under separate cover.
3.5. Environmental Evaluation The Final Environmental Impact Report (CEQA) was certified on March 21, 2019. The Final Environmental Impact Statement (NEPA) public review period was from November 15, 2019 to December 16, 2019.
3.5.1. Rare Plant Survey Special status plant species are plants that are legally protected under the federal Endangered Species Act (ESA), California Endangered Species Act (CESA), or other regulations, as well as species considered sufficiently rare by the scientific community to qualify for such listing. Field surveys and database searches have been completed, and no special status plants occur in the project area.
3.5.2. Environmental Controls
3.5.2.1. SWRCB Stormwater General Permit Requirements Most construction activities that disturb 1 acre of land or more are required to obtain coverage under the NPDES General Permit for Construction Activities Agenda Item No. 11B Attachment C - Design Documentation Report
(General Construction Permit) (Order No. 2009-0009-DWQ), which requires the applicant to file an NOI to discharge stormwater and to prepare and implement a stormwater pollution prevention plan (SWPPP). Work towards preparation of the Notice of Intent (NOI) and SWPPP will be prepared by the contractor.
3.5.2.2. Federal Endangered Species Act Requirements Section 7 requires that all federal agencies consult with the USFWS (with jurisdiction over plants, wildlife, and resident fish) and NMFS (with jurisdiction over anadromous fish, and marine fish and mammals) prior to approving or initiating a project that may result in “take” of a listed species. Habitat for the following federally threatened species was observed in the action area: valley elderberry longhorn beetle, giant garter snake, North American green sturgeon, Delta smelt, Central Valley steelhead, and Central Valley spring-run Chinook salmon. The action area also contains habitat for federally endangered Sacramento River winter-run Chinook salmon, and candidate species tricolored blackbird and longfin smelt. A biological assessment was written to analyze project impacts and as a result A Biological Opinion was prepared by USFWS for construction activities on May 2, 2019 for take of Valley Elderberry Longhorn Beetle and Giant Garter Snake. The Biological Opinion will be amended to include take of Giant Garter Snake due to long term O&M activities. The Biological assessment determined that the project was not likely to cause take of fisheries protected species. National Marine Fisheries Service issued a Concurrence Letter on March 1, 2019.
3.5.2.3. State Endangered Species Act Requirements Pursuant to CESA, a permit from the California Department of Fish and Wildlife (CDFW) is required for projects that could result in the take of a State listed threatened or endangered plant or animal species. Environmental scientists completed field surveys for special status species habitats in the project area. These surveys identified habitat for the State threatened Swainson’s hawk, and State listed fully protected white-tailed kite, in addition to the federally listed species identified above. These surveys will be used to support incidental take permit applications that will be prepared for the project. An incidental take permit for the take of one Swainson’s Hawk nest during construction activities and the take of Giant Garter Snake through maintenance activities for the 50 year life of the project is being sought.
3.5.2.4. CDFW Streambed Alteration Agreement Requirements A lake and streambed alteration agreement (LSAA), issued by CDFW in compliance with Section 1602 of the California Fish and Game Code, is required when a project will substantially divert, obstruct, or change the natural flow of a river, stream or lake; substantially change the bed, channel, or bank of a river, stream, or lake; or use material from a streambed. Environmental scientists Agenda Item No. 11B Attachment C - Design Documentation Report
completed a wetland delineation for the project area, including potential borrow sites, that identified waters potentially subject to LSAA requirements. Additional surveys identified riparian habitat in the project area, which would be included with LSAA supporting documentation. A LSAA notification package will be sent to CDFW. The notification package describes all activities that affect the drainages that may be jurisdictional streams, and include information on riparian areas.
3.5.2.5. Clean Water Act Requirements Section 404 of the Clean Water Act (CWA) requires that a permit be obtained from USACE for the discharge of dredged or fill material into “waters of the United States, including wetlands.” Section 401 of the Clean Water Act, and the Porter Cologne Water Quality Control Act require that a water quality certification is obtained from the Central Valley Water Quality Control Board for the project. Environmental scientists completed a wetland delineation, including identification of potential waters of the U.S. and waters of the State, for the project area, including potential borrow sites. Section 10 of the Rivers and Harbors Act does not apply to this project.
3.6. Hazardous and Toxic Waste
3.6.1. Hazards Report The purpose of a Hazards Report is to assess the likelihood that recognized environmental conditions (RECs) are present at the Site as a result of the current or historical Site land use or from a known and reported off-Site source; provide preliminary information in support of future Phase I Environmental Site Assessments (ESAs); collect sufficient information to evaluate the need for Phase IIs; and incorporate the findings of the assessment into Geographic Information System (GIS). A Phase I Environmental Site Assessment was prepared for the Lexington Ranch parcels and Riverby Ranch parcels. Remaining properties within the project footprint will do their Phase 1 ESA’s completed as their appraisals are completed.
3.6.2. Findings and Recommendations Lexington Ranch Parcels As per the definition in the ASTM E1527-13 standard practice, the assessment revealed no evidence of recognized environmental conditions in connection with the Site, but did observe the following supplemental concerns:
• The Old Bryte Landfill/West Sacramento Landfill located adjacent and south of the Site at 50035 County Road 126 came up in the Comprehensive Environmental Response, Compensation, and Liability Information System (CERCLIS), Voluntary Cleanup Program (VCP), Solid Waste Information System (SWIS), and Historical Solid Waste Facility (SWF) databases, as well as the Agenda Item No. 11B Attachment C - Design Documentation Report
EnviroStor database. This site has confirmed soil contamination (elevated levels of lead, zinc, dioxins, and polychlorinated biphenyls (PCBs)) and still needs further assessment to determine the extent of the contamination and cleanup needs. This site is considered a supplemental concern due to the fact that the extent of contamination has not been determined. ESAS recommends sampling of the Site adjacent to the Old Bryte Landfill to determine if the confirmed soil contamination has spread onto the Site.
• The age of the structures on the Site is unknown, and therefore, it is unknown if they contain asbestos-containing materials or lead-based paint. ESAs recommends research on the residence located on APN 042-330-006 to determine the extent of potential issues relating to asbestos-containing materials, lead-based paint, and possible historical significance. In addition, ESAs recommends that the debris, drums, containers of unknown contents, trailer, and aboveground storage tanks (ASTs) located around the residence be removed and properly disposed of.
• Because of the Site’s current and historical land use, there is a potential that pesticides that are persistent in the environment were applied and residual concentrations may remain in the soil. Environmental liability generally arises as the land use changes from agricultural to some other use where exposure to pesticides may be a concern. ESAs considers there to be a low risk of exposure to future occupants from the Site’s native soils. However, there may be regulatory liability if concentrations of pesticides are in excess of regulatory thresholds. ESAs recommends sampling of the agricultural soils to determine if pesticides are persistent in the environment.
Riverby Ranch Parcels As per the definition in the ASTM E1527-13 standard practice, the assessment revealed no evidence of recognized environmental conditions in connection with the Site, but did observe the following supplemental concerns:
• Because of the Site’s current and historical land use, there is a potential that pesticides that are persistent in the environment were applied and residual concentrations may remain in the soil. Environmental liability generally arises as the land use changes from agricultural to some other use where exposure to pesticides may be a concern. ESAs considers there to be a low risk of exposure to future occupants from the Site’s native soils. However, there may be regulatory liability if concentrations of pesticides are in excess of regulatory thresholds. ESAs recommends sampling of the agricultural soils to determine if pesticides are persistent in the environment. Agenda Item No. 11B Attachment C - Design Documentation Report
3.7. Cultural and Historic Resources DWR has coordinated with the USACE to prepare a draft set of cultural resource management methods and commitments that will satisfy the responsibilities of USACE for managing historic properties protected by Section 106 of the National Historic Preservation Act (NHPA). A Memorandum of Agreement and Historic Properties Treatment Plan has been signed between DWR, USACE, and SHPO to determine measures to be taken in the event of unexpected discoveries and specify mitigation for impacts to Levee unit 122, an eligible historic resource. Tribal consultation was complete, and it is anticipated that Tribes will request to monitor during ground disturbing activities.
3.8. Civil Analyses, Design, and Levee Improvement Alternatives Analysis Civil designs were developed for an approximate 1,500 feet levee setback for the project. The levee is proposed to have a 4:1 (h:v) slope on the water side and a 4:1 (h:v) slope on the land landside. Specifics of the civil design are described below.
3.8.1. Civil Design Process The design process utilized Autodesk Civil 3D software. The terrain models for the various portions of the project were refined based on the levee alignment and further design development. Seepage berm widths shown within the design documents are based on geotechnical recommendations. Additional real estate needs, project mitigation of impacted areas and project phasing were also considered in the design process.
3.8.1.1. Terrain Model Three-dimensional terrain models using Autodesk Civil 3D software have been developed to depict the existing and proposed conditions. The models include the existing ground, the levee improvements, the grading area, transportation corridors, and drainage features. The terrain models were used to develop sheets for the design elements and earthwork calculations.
3.8.1.2. Project Corridors and Construction Limits Project corridors associated with the levee improvement designs will include operation and maintenance (O&M) corridors, county road right-of-way (ROW), drainage/irrigation, and utility corridors. These corridors combined with the area occupied by the levee improvement features, borrow sites and the existing levees define the overall project footprint. O&M corridors will run the entire length of the proposed setback levee on the landside and waterside adjacent toe of the levee/seepage berm. O&M corridors along the levee toes have a minimum width of 20 feet. Preliminary utility corridor locations are included in the design. Coordination with utility companies is ongoing since utility relocation and setback levee construction will happen concurrently. Agenda Item No. 11B Attachment C - Design Documentation Report
3.8.1.3. Project Phasing Due to the size and complexity of the project, construction is expected to be carried out in multiple phases and construction seasons. Phasing of the work will become more certain through coordination with the contractor. Some factors influencing phasing include, property acquisition, transportation improvements, utility relocations, maintaining the integrity of existing levee system during construction and flood seasons, location and availability of borrow, volume of fill to be placed, weather, and the contractor’s means and methods.
3.8.2. Utilities and Encroachments The utilities affected by this project include power and communications. Power in the area is provided by PG&E, communications are provided by AT&T, although other service providers may be in the area as well. The power and communications services in the project area are primarily overhead, on shared poles. A 12 inch jet fuel line owned by Wickland Pipeline, LLC has been relocated in advance of the project. A major fiber optic cable is impacted by the project and will be relocated. Due to the lack of any community water or sewer systems, all single-family homes are assumed to have domestic wells and septic systems. Some single-family homes use propane tanks for heating gas. Numerous irrigation wells also exist in the area. Removing and consolidating RD 537, 785, and 827 pump stations will be required for the project, see Section 3.9 for more detail. Relocation of power and communications utilities will be required and utility corridors are provided for those utilities. Coordination for utility relocation is ongoing and requires real estate acquisitions.
3.8.3. Transportation This project includes relocation of portions of county roads C-126 and C-124. Proposed locations and road design and are shown in the plans. Refinements were based on coordination with Yolo County.
3.8.3.1. Existing Conditions C-126 is currently an asphalt concrete road located on top of the northern Sacramento Bypass levee. C-124 is an existing road that runs northward from the Sacramento Bypass levee. It typically parallels the existing Yolo Bypass levee in the southern portion of the Lower Elkhorn Basin, 2,000 feet to the east. The road is primarily asphalt concrete, but there are sections where it becomes a gravel road along the crown of the existing Yolo Bypass levee. It continues toward Old River Road as asphalt concrete. Please refer to the design plans for locations of the roadways.
3.8.3.2. Design Criteria DWR will design the project roadway and access improvements based upon the latest County of Yolo Improvement Standards. When necessary, additional Agenda Item No. 11B Attachment C - Design Documentation Report
references to the California Department of Transportation – Highway Design Manual, AASHTO – A Policy on Geometric Design of Highways and Streets, and the Manual on Uniform Traffic Control Devices are consulted.
3.8.3.3. Design Approach This project will reconstruct C-126 approximately 200 feet north of the proposed Sacramento Bypass landside levee toe. To get the road down and landside of the levee, there will be a transition from the existing top of the levee to the landside east of the proposed levee, refer to the design plans for more detail. C-124 is designed approximately 60 to 100 feet beyond the landside levee toe and it will be rerouted to avoid the top of the levee and will be designed to remove sections where there are gravel roads. Please refer to the design plans for more detail.
3.8.4. Interior Drainage Interior drainage is the drainage on the landside of the proposed levees, excluding flows from exterior water bodies such as the Sacramento River and the Yolo Bypass, due to under seepage and/or levee failures, have been evaluated. Drainage features for project facilities and impacts to the interior floodplain have also been evaluated. These features will be designed and constructed by SAFCA as a part of a separate contract. For more detail please refer to Appendix H-4.
3.8.4.1. Design and Evaluation Approach The general approach for design and evaluation of drainage features for the project will be to match existing internal drainage patterns as much as possible. Roadside ditches will be provided for all new, realigned, and paved roads, except where changes in runoff are not expected to be significant. Culverts will be provided to route the ditches under proposed roadway embankments. Roadside ditches and culverts will be configured to be consistent with existing drainage. A detention basin in the southern portion of the project area is included in the alternatives analysis by SAFCA, Appendix H-4.
3.8.4.2. Approach for Evaluation and Design of Downstream Agricultural Ditches Impacts of the proposed project drainage facilities to the existing downstream agricultural ditches has been evaluated in Appendix H-4.
3.8.4.2.1. Water Quality Control The stormwater runoff of certain project features and water from dewatering operations may require treatment before being discharged into waters of the United States. The primary project feature that would have this requirement is the proposed roadways. Roadside ditches will be designed as vegetated swales to provide post-construction water quality control treatment using a flow-based approach. Agenda Item No. 11B Attachment C - Design Documentation Report
3.8.4.3. General Design Criteria Drainage facilities are being designed and evaluated in accordance with the Yolo County Drainage Manual.
3.8.5. Plans Construction plan sets were developed using Autodesk Civil 3D. The plan set includes general sheets; general plans; demolition sheets; civil design sheets covering borrow plans; levee and roadway plan/profiles; signing and striping plans; plans and details for the pump station embankment, pipes, and appurtenances; tree removal and protection; and grasslands and planting. The plan set is available under separate cover.
3.8.6. Specifications Specifications are available under separate cover.
3.8.7. Opinion of Probable Project Costs Project cost estimates are available under separate cover.
3.9. Pump Station To accommodate the setback levee, the project will consolidate the existing three pump stations within the project area into one larger pump station for discharging interior drainage water into the Sacramento Bypass. The location of the new pump station and a section of the discharge pipes through the upper part of the levee are shown on Plan Sheets 158 through 168 (C7 series). The pump design capacity will be at least 160 cfs. This capacity was selected as part of the interior drainage alternatives analysis by SAFCA, Appendix H-4.
3.10. Construction Phasing Plan To complete the levee setback project, it will likely take the contractor a total of four construction seasons. For estimating purposes, one construction season is defined as the approximately 6-month period between April 15 and October 31 (i.e. not during flood season). Two seasons are estimated to construct the setback levee and roadways, and a third season to tie-in and degrade portions of the existing levee and restore the borrow area. An additional five years for monitoring and adaptive management will follow for establishment of mitigation planting, including the native perennial grass.
Constructing the tie-ins or degrading of the existing levee will not occur until after the setback levee is completed and approved by USACE. Furthermore, tie-in construction will not occur during the flood season (i.e. between November 1 and April 15). The contractor will need to closely coordinate with SAFCA’s contractors that will be constructing the ditches and the pump station, as well as utility relocations. Some portions of the levee cannot be constructed until the certain ditch improvements are constructed. During degrade and borrow area restoration, the grassland and riparian plantings can be completed. Agenda Item No. 11B Attachment C - Design Documentation Report
4. Inspection, Operation and Maintenance
The Lower Elkhorn Basin Levee Setback Project falls within unit no. 122 of the Sacramento River Flood Control Project (SRFCP). The SRFCP was authorized by the 1917 Flood Control Act and transferred to the CVFPB for operating and maintaining authority in accordance with USACE SRFPC O&M Manual and the supplement specific to unit 122. Reclamation Districts (RD) 537, RD 785, and RD 827 entered into agreements with the CVFPB to assume operation and maintenance responsibility for portions of the levees surrounding the basin. DWR maintains the north levee of the Sacramento Bypass as State Maintained Area 8, Unit 1.
As a part of this project, the Reclamation Districts have consolidated to increase the efficiency of operations and maintenance and are now collectively Reclamation District 537. Additionally, the Sacramento Area Flood Control Agency may assist in future operations and maintenance in the basin.
The levees in their current and any modified future configuration must be inspected at least four times a year, including prior to the flood season, immediately following each major high water period, and at any other times deemed necessary by the entities’ Superintendent(s). The findings of these inspections are to be reported to the Board’s Chief Engineer through DWR’s Flood Project Integrity and Inspection Branch (FPIIB). To meet Federal Flood Control Regulations (Title 33 of the Code of Federal Regulations, Section 208.10 (33 CFR 208.10) and state requirements (California Water Code §8370), each year the federal flood control facilities are to be inspected four times, at intervals not exceeding 90 days. The interior drainage system of ditches, detention basin, and pump station should also be inspected by the Reclamation District for signs of seepage or other damage following periods of high water in the flood system.
Agenda Item No. 11B Attachment C - Design Documentation Report
5. References
California Department of Water Resources (DWR) (2015). Guidance Document for Geotechnical Analyses. April, prepared by URS for DWR
DWR (2015). Central Valley Hydrology Study. November. Prepared by the U.S. Army Corps of Engineers, Sacramento District, and David Ford Consulting Engineers, Inc. Sacramento, CA.
DWR, port, North NULE Project Study Area, Volume 5 of 6: Appendix F, Area 4 Levee Segments, prepared by URS for DWR.
DWR. (2016). Sacramento River Basin-wide Feasibility Study. Sacramento, CA.
David Ford Consulting Engineers (Ford Engineers) (2016a). Lower Elkhorn Basin Levee Setback Project: Quality management plan. Prepared for DWR. Sacramento, CA.
Ford Engineers (2016b). Lower Elkhorn Basin Levee Setback Project: Work plan. Prepared for DWR. Sacramento, CA.
Hurdle, D.P. and Stive, R.J.H. (1989). Revision of SPM 1984 Wave Hindcast Model to Avoid Inconsistencies in Engineering Applications, Coastal Engineering, 12: 339-351.
US Army Corps of Engineers (USACE) (1957). Letter from District Engineer to Division Engineer (file SPKGP 824.3), Levee and channel profiles, Sacramento River flood control project. May 2, 1957.
USACE (1984). Shore Protection Manual (SPM).Waterways Experiment Station, Vicksburg, Mississippi.
USACE (1996). Risk-Based Analysis for Flood Damage Reduction Studies. EM 1110-2-1619. Headquarters. Washington, DC.
USACE (1997). Hydrologic Engineering Requirements for Reservoirs. EM 1110-2-1420. Washington, DC.
USACE (2002). Coastal Engineering Manual. EM 1110-2-1100. Washington, DC.
USACE (2009). Documentation and Demonstration of a Process for Risk Analysis of Proposed Modifications to Sacramento River Flood Control Project (SRFCP) Levees. Project Report (PR) 71. June. Hydrologic Engineering Center. Davis, CA.
USACE (2011). Sutter Basin Wave Runup Analysis. USACE, Sacramento District.
USACE (2015). Policy and Procedural Guidance for Processing Requests to Alter US Army Corps of Engineers Civil Works Projects Pursuant to 33 USC 408. Engineer Circular (EC) 1165-2-216. Headquarters. Washington, DC.
ASTM e1527(2015). Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process Agenda Item No. 11B Attachment C - Design Documentation Report
6. Acronyms
Acronym Term # 1D One-dimensional 2D Two-dimensional 3D Three-dimensional A ACM Articulated Concrete Mat AEP Annual Exceedance Probability ARCF American River Common Features B BWFS Basin-wide Feasibility Study C C-AEP Conditional Annual Exceedance Probability CDFW California Department of Fish and Wildlife cfs cubic feet per second CNP Conditional Non-exceedance Probability CS Conservation Strategy CVFED Central Valley Floodplain Evaluation and Delineation CVFPB Central Valley Flood Protection Board CVFPP Central Valley Flood Protection Plan CVHS Central Valley Hydrology Study D DWR Department of Water Resources DWSC Deep Water Ship Channel DWSE Design Water Surface Elevation E EC Engineering Circular EIR Environmental Impact Report EIS Environmental Impact Statement EIP Early Implementation Program EM Engineering Manual EWP Existing With Project F FDA Flood Damage Analysis FPIIB Flood Project Integrity and Inspections Branch FWOP Future Without Project FWP Future With Project
G GAR Geotechnical Assessment Report (NULE Program) GDR Geotechnical Data Report GBOD Geotechnical Basis of Design Report GDWSE Geotechnical Design Water Surface Elevation GRR General Re-evaluation Report
H H&H Hydrology and Hydraulics HEC Hydrologic Engineering Center h:v horizontal to vertical Agenda Item No. 11B Attachment C - Design Documentation Report
Acronym Term
I IPAST Information Processing and Synthesis Tool ITR Independent Technical Review
J JFP Joint Federal Project
K KLRC Knights Landing Ridge Cut
L LEBLS Lower Elkhorn Basin Levee Setback LPP Locally Preferred Plan
N NAVD North American Vertical Datum NLIP Natomas Levee Improvement Project NULE Non-urban Levee Evaluation (program)
O O&M Operations and Maintenance
P PR Project Report
Q QC Quality Control QMP Quality Management Plan
R R&U Risk and Uncertainty RAS River Analysis System RD Reclamation District ResSim Reservoir Simulation RM River Mile ROW Right of Way RSP Rock Slope Protection
S SAFCA Sacramento Area Flood Control Agency SAR Safety Assurance Review SPFC State Plan of Flood Control SPK Sacramento District SPM Shore Protection Manual SRFCP Sacramento River Flood Control Project
T TO Task Order TOL Top of Levee TRLIA Three Rivers Levee Improvement Authority TWL Total Water Level
U ULDC Urban Levee Design Criteria USACE United States Army Corps of Engineers USC United States Code USFWS United States Fish and Wildlife Service Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 1: Project Location Map Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 2: TO 34 SRR Model Extent Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 3: Baseline Conditions Projects Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 4: Cumulative Improvements
Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 5: Hydraulic Impacts for EWP Approximate 100-Yr Event (1997 x 95%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 6: Hydraulic Impacts for EWP Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 7: Hydraulic Impacts for FWOP Approximate 100-Yr Event (1997 x 95%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 8: Hydraulic Impacts for FWOP Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 9: Hydraulic Impacts for FWP Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 10: Hydraulic Impacts for FWP Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 11: Hydraulic Impacts for Intermediate Cumulative Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 12: Hydraulic Impacts for Intermediate Cumulative Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 13: Hydraulic Impacts for Full Cumulative Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 14: Hydraulic Impacts for Full Cumulative Approximate 200-Yr Event (1997 x 110%) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 15: Yolo Bypass Design Water Surface Profile (Sheet 1 of 4) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 15: Yolo Bypass Design Water Surface Profile (Sheet 2 of 4)
Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 15: Yolo Bypass Design Water Surface Profile (Sheet 3 of 4)
Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 15: Yolo Bypass Design Water Surface Profile (Sheet 4 of 4) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 16: Sacramento Bypass Design Water Surface Profile (Sheet 1 of 2) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 16: Sacramento Bypass Design Water Surface Profile (Sheet 2 of 2) Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 17: Soil Resistivity Survey Lines Agenda Item No. 11B Attachment C - Design Documentation Report
Figure 18: Project Schedule