CE&G was retained as a subconsultant to GEI for the Alameda County Flood Control and Water Conservation District’s project to raise the levee and redesign floodwalls. The improvements included installing a floodwall along the existing levee crest waterside hinge line and placing and compacting low permeability fill to raise the existing levee grade. The floodwall will be constructed on a reinforced concrete pile cap supported by a cast-in-drilled-hole pile foundation and be 2-4 feet above the existing ground surface. Services included preparing full PS&E for wingwalls and floodwalls, preparing a design memorandum, and assisting with the FEMA certification.
Zone 5 Line M, Union City, California
CE&G completed a geotechnical investigation, geotechnical report, and floodwall design for the improvement of a flood control channel and outfall structure in Union City. The project included investigations and design of 1,250 linear feet of pile supported floodwalls on an existing earth lined flood control channel. The project also included widening of the existing channel at the outfall structure, design of a new outfall structure headwall, end wall, wingwalls, and sluice gate well. Plans, specifications, and engineer’s estimate were provided to the District as project deliverables.
3959 Whitman Way, San Jose
CE&G was retained as part of a team of structural and geotechnical engineers and geologists to complete a landslide study, and Landslide Displacement Hazard Analysis (LDHA), and provide geotechnical design recommendations to prevent catastrophic failure due to an earthquake. The project includes three adjacent pipelines that service the Penitencia Water Treatment Plant (PWTP) which is located over the slow-moving Penitencia Creek Landslide. All three pipelines cross the stable Santa Clara Valley floor onto the landslide mass. The Penitencia Force Main (PFM), a 66-inch pipeline owned by the Santa Clara Valley Water District (District); Penitencia Delivery Main (PDM), a 60-inch pipeline, also owned by the District; and the South Bay Aqueduct (SBA), a 72-inch pipeline, owned by the California Department of Water Resources.
In 1983, the PDM pipeline failed due to large compressive forces from landslide movement and flexible expansion/contraction joints were installed within a vault to house the new joint assemblies. In 2004, the pipeline joints in the Penitencia Vault were replaced because they had compressed beyond the recommended levels. In 2011, observation of the flexible coupling adapter at the PDM Effluent Vault determined that it was near failure. Although the landslide movement is relatively slow, there is the potential for vertical and horizontal movement that could exceed the limitations of the existing joints during a large earthquake event.
CE&G’s scope included meetings and consultations with the project team, completion of seismic analysis of landslide, management of the geotechnical investigation, geotechnical review of design documents, evaluation of existing data, development and implementation of a subsurface exploration and laboratory testing program, engineering analyses, evaluation of existing implementation and development of a long-term geotechnical monitoring plan, preparation of a technical memorandum regarding Landslide and Seismic Hazards Evaluation, and development of geotechnical analyses models for alternatives feasibility. CE&G also coordinated with DWR, SCVWD, and the PWTP, during the project.
Bair Island, Redwood City, California
Working as a subconsultant, CE&G completed a geotechnical exploration for a proposed new 48-inch forced sewer main near Bair Island Slough in Redwood City, California. The new line is to be constructed by microtunneling in old bay mud deposits with several deep launching and receiving shafts. Duties for the project included historical research of the project area, collection of previous exploration data, coordination with local and state permitting agencies, coordination with multiple consulting and development agencies, coordination with the drilling subcontractors, field investigation, laboratory testing selection, and report development. The field investigation included four over-water exploratory borings utilizing a barge mounted drilling rig. The barge drilling rig was launched in coordination with the state and local agencies and private resident of the area and transported several miles along the San Francisco Bay creeks and waterways to the exploration location. The drilling operation lasted four days. The exploration required constant adjustment for tidal influences to maintain the near continuous sampling interval required for up to 92.5 feet below the sediment floor of the San Francisco Bay margin soils.
In accordance with our on-call service agreement with the City of Vallejo, Cal Engineering & Geology provided quality assurance testing services for a sewer rehabilitation project on Mare Island in 2011. The project consisted of new asphalt concrete pavement and slurry sealing at various sanitary sewer pump stations, installation of approximately 2000 lineal feet of 22-inch HDPE sewer main, boring and jacking of 32-inch steel casing at three locations, and preparation for the installation of five new emergency back-up generators. During the course of work, Cal Engineering & Geology attended weekly progress meetings, sampled and tested baserock materials, and performed field density testing of the placement of baserock and asphalt concrete. Field reports were delivered to the Public Works division on a timely basis, with a final quality assurance testing letter issued at the conclusion of the work. The services were provided on an as-needed, intermittent basis with 30 site visits over a two month period. This efficiency resulted in cost control that utilized only 47 percent of the estimated budget.
CE&G is providing geotechnical services related to the planned seismic retrofit of two earth dams owned by the Santa Clara Valley Water District. As a project subconsultant, CE&G has been assisting with the development and preparation of planning study documents including a Problem Definition Report, Planning Study Report, and CEQA. Services include document review and data collection, completion of a geotechnical foundation exploration for potential seismic retrofit alternatives for each dam, evaluation of alternatives for the retrofits, and a borrow and spoil siting study. The dams which were each built in 1936, were previously found to be unstable under current seismic evaluation criteria. The retrofits are being designed and will be constructed under the auspices of the California Division of Safety of Dams.
Martin Luther King Way, Oakland, California
Cal Engineering & Geology was retained to perform a geotechnical investigation and report for a new 60 inch diameter, 6,300 foot long gravity sewer line, with associated junction structures and access holes beneath West Grand Avenue between Wood Street and Martin Luther King Jr. Way in west Oakland, California.
The scope of work included the review of geotechnical and geologic maps of the area, evaluating historical maps and reports to determine the approximate limits of old fill pushed into the bay in the early 20th century, drilling and sampling a total of 17 borings to depths between 18.5 and 45 feet below finished grade, and preparation of a report with recommendations for design of the sewer and for temporary shoring.
Based upon both our historical evaluation of the site history and the subsurface borings, CE&G determined that the ground conditions along the line varied substantially and provided two sets of recommendations. CE&G also tied the recommendations to the project stationing so that the appropriate recommendations would be used for design of the shoring and final design of the sewer relief line.
CE&G completed the investigation and report in 2004 and then responded to minor comments and provided supplemental recommendations in 2006 during final design of the project.
In 2004, Cal Engineering & Geology was retained by the Alameda County Flood Control District to complete a subsurface exploration and prepare a geotechnical design report for the trenchless pipe jacking installation of a new 8 foot diameter concrete culvert adjacent to an existing culvert that passes beneath the Union Pacific Railroad (UPRR) yard in Union City. The work required extensive coordination with UPRR and the District during subsurface exploration. The geotechnical exploration project also incorporated environmental sampling to assess the potential contamination of soils through which the pipe would be jacked. Geotechnical design recommendations for the jacking pit shoring were also provided. The project was designed by District staff and was constructed successfully.
Cal Engineering & Geology was retained as a subconsultant to provide the Contra Costa County Flood Control & Water Conservation District with geotechnical consulting services to design and construct a new 1,000 acre-foot flood control basin in Antioch, California. The facility was subject to review by the California Division of the Safety of Dams and will include a 40 foot tall earth embankment dam and a 15 foot tall saddle dike embankment.
Geotechnical challenges at the site included liquefiable foundation materials and an ancient landslide on the right abutment of the planned dam. These geologic hazards were investigated and analyzed to determine potential impact on the dam and basin. CE&G provided field exploration services, geologic and geotechnical analyses of the ancient landslide, foundation characterization, and assistance in the preparation of construction plans and specifications. Exploration included approximately 14 boreholes and coreholes, 33 exploratory test trenches and pits, and downhole geotechnical testing.
I-880, Newark, California
In 2008, Cal Engineering & Geology was retained by the Alameda County Flood Control District to complete a subsurface exploration and to prepare a geotechnical data and design report for the trenchless pipe jacking of a 175 feet long, 96-inch diameter steel casing to house a 72-inch reinforced concrete pipe culvert below Interstate 880 on the border between Newark and Fremont. The culvert was to be installed adjacent to an existing reinforced concrete box culvert in order to increase the flood conveyance capacity below the freeway. Geotechncial design recommendations for the temporary excavations, shoring, permanent headwalls, and wingwalls were provided. CE&G was subsequently retained in 2010 to assist the District in the design of the project and to prepare the construction documents. CE&G teamed up with two subconsultants in order to complete the project within the timeframe specified. The greatest design challenge for the project involved jacking of the steel casing below a Caltrans masonry block soundwall supported on a cast-in-place concrete retaining wall. The retaining wall footing included a key that protruded below, which conflicted with the proposed plane elevation of the steel casing. The design therefore required permanent shoring for the retaining wall and sound wall to facilitate removal of the key during construction, and allowed the steel casing to abut the bottom of the footing. The permanent shoring system design consisted of cast-in-drilled-hole concrete piles, pile caps, and a concrete beam. The final design was reviewed and approved by Caltrans structural and water resources groups. CE&G also prepared the tunneling and concrete pipe specifications and assisted in preparing the engineer’s estimate for the project.