Stanislaus Regional Water Authority Water Treatment Project

Stanislaus County, California

This project is led by the Stanislaus Regional Water Authority (SRWA), which currently consists of the cities of Ceres and Turlock. The project will require water release from Don Pedro Reservoir located about 25 miles up the Tuolumne River. Water will then be diverted from an existing infiltration gallery in the Tuolumne River located immediately downstream of Geer Road. Turlock Irrigation District (TID) will then redirect the water to a new water treatment facility just south of Aldrich Road for treatment and distribution to two terminal tank sites (one in Ceres and one in Turlock). Finally, the water will be distributed to the Cities of Ceres and Turlock for municipal and industrial uses.

CAInc prepared a Draft Preliminary Geologic/Geotechnical Study Memorandum for use in preparation of a Feasibility Study. The geologic setting, subsurface data, groundwater, and site seismicity/fault rupture were studied based on existing documents and reports of the area. Preliminary conclusions were provided for the Water Treatment Facility, Open Cut Pipeline, Trenchless Pipeline, and Terminal Tanks. Recommendations for Excavation/Stability, Groundwater/Dewatering, Liquefaction & Seismic Settlement, and Corrosivity were provided.

Humboldt Bay Municipal Water District Water Transmission Pipeline Replacement under Mad River

Humboldt County, California

The project will replace an existing 14” ductile iron pipe where it presently crosses the Mad River attached to a 1930’s era North Coast Railroad Authority (NCRA) steel-truss bridge. The bridge is vulnerable to damage or failure during an earthquake or severe flood. The pipeline is the main water supply to the communities of Blue Lake, Fieldbrook and Glendale. Total length of the river crossing is about 540 feet.

CAInc prepared a Preliminary Geotechnical Report for Phase 1 of the project, which provided preliminary (Phase-1) geotechnical assessment for a proposed new aerial pipeline crossing and includes an initial assessment for a horizontal directional drilling (HDD) alternative. Four test borings were completed, two on each side of the Mad River, along with geologic reconnaissance and preliminary laboratory testing. Alternatives included a new aerial crossing with suspension towers located on each bank, or installed under the river by horizontal directional drilling (HDD) methods.

Based on the preliminary report, it was determined that horizontal directional drilling (HDD) would be a feasible and cost-efficient construction method pending verification of the subsurface conditions and hydrofracture risk. For Phase 2, CAInc prepared a Final Geotechnical Report which included project coordination and preparation; geologic reconnaissance; subsurface exploration; geophysical surveys; and laboratory testing. Recommended the HDD pipeline be maintained within the bedrock unit as shown on Figure 5 to reduce the potential for frack-out.

Linda County Water District – Well 17 Project

Marysville, California

CAInc prepared a Geotechnical Report for the proposed project. Foundation recommendations for the structures at each site include the following: Well 17 Site:

  • Below ground sump station and mist eliminator structure supported on a concrete mat foundation 10 to 15 feet below existing grade
  • Chemical & electrical control facility supported on an at-grade concrete mat foundation
  • 25-foot diameter steel backwash tank supported on a shallow perimeter ring foundation with crushed rock or aggregate base belly support
  • Ancillary structures/tanks including brine and fuel tanks, generator, pressurized filters, and transformer supported on shallow spread footings or concrete mat foundations

Storage Tank Site:

  • Approximately 1-million-gallon, 100-foot diameter steel storage tank supported on shallow perimeter ring foundations, interior column spread footings, and crushed rock or aggregate base belly support
  • Booster pump station supported on a 10 to 15 ft deep concrete basin/vault. Booster pump ancillary piping and equipment will be supported adjacent to the booster pump station on shallow spread foundations and concrete slab on grade

The project will also include approximate 1,000 linear feet of open cut water pipeline connecting the Well 17 and Storage Tank Site. To prepare the report, CAInc drilled, logged and sampled 8 borings at the sites and performed laboratory tests on the soil samples. Key Geotechnical considerations for the project include the presences of clayey soils that can make achieving proper compaction difficult during construction. CAInc used SETTLE 3D Version 3.0 software to evaluate immediate and consolidation settlement for both the storage basin tank and pump station. Grading, pavement, and utility trench recommendations were also provided.