2015 ASCE Region 9 Outstanding Project of the Year

Owner: Sutter Butte Flood Control Agency Michael Bessette, P.E. 1441 Garden Highway Yuba City, CA 95991

Engineer: HDR, Inc.Daniel Jabbour, P.E.2365 Iron Point Road, Ste. 300Folsom, CA 95630

Wood RodgersJonathan Kors, P.E.301 C Street, Building 100-BSacramento, CA 95816

Geotechnical Engineer: URS CorporationMichael Hughes, P.E.3807 Gateway Oaks Drive, Suite 150Sacramento, CA 95833

Contractor: Nordic- Magnus Pacific Joint VentureSean L. Rhodes, Program Manager6558 Lonetree Blvd.Rocklin, CA 95765

Contract Number & Title: Contract No. 01-2013CFeather River West Levee Project – Project Area C

Project Location: Sutter and Butte Counties, California

LEVEE HISTORY

Sutter and Butte counties are located in California approximately 40 miles north of Sacramento and along portions of the Feather River. The Feather River through both counties has been confined by man-made levees constructed in the late 1800’s. These levees were generally constructed on subsurface materials deposited by the current and historical Feather River and its tributaries. The Feather River West Levee (FRWL), located along the west bank of the Feather River from the Sutter Bypass at the southern end to Thermalito Afterbay at the north

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end, is maintained by several Maintenance Areas (MAs) and Levee Districts (LDs), including MA3, LD1, LD9, MA16, and MA7 in order from south to north.

The FRWL has been subjected to flood events in 1955, 1964, 1986, and 1997. Several areas along the FRWL have experienced cracking, boils, seepage, and breaks associated with these high water events. The 1955 levee break damaged/destroyed approximately 6,000 homes and resulted in 38 deaths. During high-water events in 1997, numerous sections of the Feather River West Levee experienced significant underseepage, through seepage, and erosion problems. Today, the Feather River West Levee protects a population of approximately 100,000 people and one of the world’s most productive agricultural areas.

The United States Army Corps of Engineers (USACE) enlarged the MA3 levee in 1943 and performed levee stabilization construction between November 1962 and April 1963. During the 1986 flood event a boil occurred near a drainage ditch located along the levee landside toe. During the 1997 flood, heavy seepage entered the same drainage ditch. The drainage ditch was converted to a pervious toe drain and as part of the Marysville/Yuba City Levee Reconstruction Project a permanent seepage/stability berm was constructed in 1998. In 1956, USACE performed emergency levee repairs at Shanghai Bend and from Garden Highway to the 10th Street Bridge. In 1995, LD1 constructed a new levee to bypass the Shanghai Bend. Under emergency action, Yuba City constructed a landside toe berm, which was later replaced by a permanent seepage/stability berm. In 1909, 1911, and 1955, the levee between Shanghai Bend and the Yuba City Airport broke leading USACE to perform emergency reconstruction and to installed relief wells along the levee landside toe.

Under a PL84-99 Action, USACE constructed a pervious toe drain and seepage/stability berm south of Star Bend, relief wells between Star Bend and Abbott Road, and a cutoff wall from the Yuba City Airport to the 5th Street Bridge. In 1990, Yuba City installed a shallow seepage interceptor system as well as relief wells at the Yuba City Airport. As a part of the Marysville/Yuba City Levee Reconstruction Project, the levee was raised by one-foot and a pervious toe drain and seepage/stability berm were constructed immediately south of Star Bend and at the Boyd Pump Boat Ramp.

The Sacramento River Flood Control Project, Phase II, Levee Reconstruction, Contract 3 project identified three sites in LD9 and MA7 that were deficient but have since been improved. Site 1 is located in MA7 and consisted of a levee raise to correct levee height issues. Site 2 is located in MA7 and consisted of constructing a 50-foot deep waterside toe cutoff wall to correct under seepage issues. Site 3 is located in LD9 and consisted of backfilling a landside irrigation ditch. In addition, a bentonite/shredded tire slurry wall was constructed at the southern portion of MA7.

The 1997 flood event led to renewed concerns regarding the adequacy of the FRWL. In 2007 the Sutter Butte Flood Control Agency (SBFCA) was formed with the intent of implementing flood control and levee rehabilitation measures within the basin and along the FRWL. SBFCA is a

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joint powers authority representing Sutter and Butte Counties, the cities of Biggs, Gridley, Live Oak and Yuba City, and Levee Districts 1 and 9.

PROJECT BACKGROUND

Evaluation and design work involved extensive seepage analysis, landside stability analysis, waterside rapid drawdown, and seismic deformation analysis. This work has shown that the majority of the levee system has underseepage problems.

The Geotechnical Engineer of Record, was responsible for all the geotechnical investigation, analysis and design work from the Pre-Design Formulation Report through final design for approximately 40 miles of levee along the west bank of the Feather River. Also, the geotechnical engineer participated in the development of the contract documents including plans and specifications.

Due to landside constraints, the geotechnical design included the extensive use of cutoff walls, both conventional trench methods and deep mixing methods, with the localized use of relief wells and seepage berms. Cutoff wall designs were optimized by differentiating zones needing deeper cutoff walls from those where relatively shallow walls could be utilized to “stitch” together interbedded zones of fine and coarse grained material to form a thickened blanket. Based on external review comments, URS developed a technical basis for evaluating “end-around” seepage effects at transitions between shallow to deep walls to justify that the location of transition points.

To facilitate cutoff wall construction the levee was degraded. For reconstruction of the degraded portion of the levee a zoned embankment with a central clay core and outer shell material was utilized. This relatively new concept in California enabled reuse of significant quantities of degrade material with considerable cost savings.

Based on exploration data, the levees along the west bank of the FRWL predominantly comprise granular materials. As such, an integral part of the design was identifying suitable borrow sources for the central clay core. The geotechnical engineer was directly involved in the evaluation and selection of borrow sites, which ended up being a pivotal part of the project, because of the lack of suitable borrow material in the immediate project vicinity.

PROJECT DESCRIPTION

Over the past four years, SBFCA has completed a comprehensive study of the FRWL and has identified levee through and under seepage, geometry, erosion, penetration, and encroachment deficiencies. To address these deficiencies, and to meet the goal of achieving 200-year level of flood protection for urban areas within Sutter and Butte Counties, SBFCA implemented the FRWL Project. The Project includes roughly 44 miles of levee rehabilitation stretching from the Sutter Bypass to Thermalito Afterbay.

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For the purposes of design and construction, the Project was divided into four Project Areas; A, B, C and D, with Project Area A located at the southern end of the Project and Project Area D at the northern end of the Project.

Construction documents have been prepared for Project Area C (approximately 12 miles) that include corrections to levee deficiencies from Shanghai Bend at the southern end of Yuba City to north of Campbell Road north of Yuba City (from Station 844+75 to Station 1625+00). Improvements include the construction of Soil-Bentonite and Soil-Cement-Bentonite cutoff walls, landside seepage berms, correcting levee geometry issues, and wet and dry utility modifications. Additionally, as a part of this Project, various right of way encroachments will be addressed and an operations and maintenance corridor will be established.

Also the scope of levee improvement included the following tasks:

Levee geometry corrections that bring the levee into compliance with USACE guidelines, which recommend 3 horizontal to 1 vertical (3H:1V) waterside embankment slopes, 20-foot levee crown width, and 2 horizontal to 1 vertical (2H:1V) landside embankment.

A 3-foot wide conventional soil-bentonite (SB) cutoff wall approximately 12 miles long. The cutoff wall ranges in depth from 30 to 80 feet and ties into foundation strata of low permeability.

A deep soil mixing soil-cement-bentonite cutoff wall (approximately 800,000 SF) that ranges in depth from 90 feet to 125 feet.

Land acquisition to provide a typical 50-ft wide landside and 15-foot Operation and Maintenance (O&M) corridors. Variations to these typical widths occur based on space limitations due to existing facilities.

A 16-foot wide aggregate base (AB) access road along the new levee crown.

In summary, over 3 million SF cutoff wall was constructed to a maximum depth of 125 feet, and over 500,000 CY of import embankment fill was utilized to upgrade the levee geometry. The cutoff wall with a maximum permeability of 5 x 10-7 cm/sec was constructed using eight large excavators working double shifts six days per week. The levee embankment fill was developed and imported from several borrow sites. The project included protection of existing underground utilities including a water main (coordinated not to interrupt service), irrigation lines, and a gas line; and the raising of and relocating of multiple overhead utility lines to accommodate construction of the slurry cutoff wall.

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FACTORS ADDING TO THE COMPLEXITY OF THE WORK

1. Very few contractors have the equipment, manpower, and expertise to construct the 80-125 foot deep cutoff wall. The construction had to meet strict qualifications and experience requirements to be awarded this construction.

2. Harvest season for agriculture crops needed to be accounted for in project scheduling; to allow local farmers access to the work area during harvesting.

3. High visibility due to the critical nature of this levee work in Sutter and Butte Counties and with the interest of the Department of Water Resources.

4. Encountering 15 sites containing prehistoric artifacts and human burial remains versus only two identified during preconstruction research. The project team partnered with Federal and State agencies and tribal government leaders to mitigate efforts to handle the culture site issues without significant impact to the project schedule.

PROJECT TEAM WINNING WAYS

1. The project team recognizing that this project required construction of over 3 million SF cutoff wall in two construction seasons, provided all essential elements to getting the project moving toward a successful start in June of 2013, including schedule, submittals, and mix design.

2. Staying forwarded on the submittals, starting the slurry wall mix design early and attaining the required permeability which allowed for work to proceed without the worry of costly rework and schedule impacts. All QC and QA testing proved materials remained in compliance throughout the project duration.

3. Keeping a weekly coordination meeting scheduled every Tuesday at 9:00 a.m. kept all parties aware of current activities, upcoming events and quick issue resolution. The meetings were well attended each week with State Department of Water Resources, USACE, Engineer, Safety and Quality Control/Quality assurance representatives.

4. Bentonite was ordered in advance and delivered and stored during the winter season to eliminate project shutdown during high demand for bentonite.

5. Local fuel and vendor companies were utilized to support the neighboring community and economy.

6. In the event of differing site conditions (mainly related to discovery of additional cultural sites), the project Team was proactive and cooperative in implementing the least time and cost impact solutions.

7. The proactive safety program resulted in approximately 80,000 exposure hours without any lost time accidents.

8. The project Team maintained a good public relative with the local residents and businesses.

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9. The project Team maintained displayed a true partnering spirit from the first weekly meeting, and was always willing to accommodate and cooperate.

NUMBER AND NATURE OF CLAIMS

There were no claims on this project. There were 11 contract modifications which addressed additional scope of work and quantity overruns/under runs.

PROJECT PHOTOS

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