Fresh and Wastewater Treatment Projects

Avalon is a development of 275 single-family ranchettes on 240 acres of the original 1,700-acres of ranch land. Villages 1 and 2 occupy the southern portion of the project and include a 2.75-million gallon water reservoir (steel tank) and three pump stations. A portion of site is within the State Earthquake Fault Zone of the Hayward Fault. For this project, we conducted a series of geotechnical and geological studies involving soils borings and exploratory test excavations. Evidence of subsidiary faulting was found east of the Hayward Fault and was addressed in a paper by McCormick, Burkland, and Raynak of Earth Systems, entitled "Subsidiary Faulting East of the Hayward Fault in Southern Alameda County", (CDMG Special Publication 113). Our reports addressed seismic hazards, slope instabilities, and requirements for site grading and drainage.

Our firm was retained to provide a geologic hazards study and a geotechnical engineering investigation for the Chorro Valley Transmission Pipeline, a segment of the California Water project that will extend through the County of San Luis Obispo. The pipeline route traversed a distance of approximately 11.5 miles, which included areas of steep, hazardous terrain before reaching the coastal plain. In the geologic hazards study, areas of landslide, potential landslide, and areas of excessive settlement risk were identified. The geotechnical report addressed design criteria for the pipeline, including seismic considerations; design criteria for sheeting and shoring of trenches and jacking pits; groundwater conditions and dewatering, and foundation design recommendations for areas where stream crossings were planned and for auxiliary structures. The feasibility of boring beneath stream crossings was also assessed.

Our firm was retained to provide a geotechnical engineering investigation and geologic hazards study for the Palmdale Water Treatment Plant, which is located south of the City of Palmdale within the San Andreas Fault Zone. The project also included a 0.5 megawatt hydroelectric plant. Site conditions included shallow bedrock, numerous fault traces, and alluvial fill. Subsurface conditions were evaluated by drilling and extensive trenching of the site. Following completion of the field and laboratory work, our firm developed mitigation measures to accommodate the site conditions. The project was constructed in two phases and currently operates with a capacity of 40 million gallons of water per day that is treated for municipal use.

The expansion of the Cambria Wastewater Treatment Plant consisted of extended aeration basins, clarifiers, and a blower facility.  For the expansion, our personnel provided geotechnical recommendations pertaining to site preparation, grading, utility trenches, foundations, retaining structures, pavement, and future expansions.  The spray field conversion project involved converting acreage devoted to spray irrigation to a series of recharge basins.  Wastewater from the sewage treatment plant is discharged into the basins, where it percolates downward to recharge the underlying aquifer.  Earthen berms contain the wastewater.  For this project, our personnel conducted a geotechnical evaluation and presented conclusions and recommendations related to percolation rates, groundwater depth, stability of berms, and grading.  During construction, our personnel observed grading operations and performed compaction testing of the berms.

The co-generation project consists of the installation of several turbine generators that will use waste gas to produce electricity for use at the wastewater treatment plant.  The generators were installed in two existing buildings, and in a new masonry building that was constructed adjacent to the existing buildings.  The new building is 14 by 23 feet and has a mat foundation with concrete slab-on-grade. Earth Systems Pacific’s scope of work for our soils engineering report included a site reconnaissance, subsurface exploration, laboratory testing, and engineering evaluation of data.  The primary soils engineering concerns were the presence of landfill debris, the potential for liquefaction, and the expansion potential of the soil.  Our recommendations included removal of landfill material in the building area, a mat foundation system bearing on firm recompacted soil, and utilities designed with flexible connections and adjustable attachments.  During construction, Earth Systems Pacific provided testing and inspection services including grading certification, compaction testing, certification of backfill for the methane drain vault, and masonry and concrete inspection. 

The Amargosa Creek Detention Facility is a 130,000 cubic yard earth fill dam, constructed to provide storm water detention facilities along Amargosa Creek. A reinforced box culvert extends through the dam. The California Division of Safety of Dams was the governing authority for this project. Our firm performed the preliminary geologic and geotechnical studies relative to the siting and design of the dam within the San Andreas Fault Zone. Our studies addressed issues such as active fault locations, slope stability of abutments and spillways, suitability of borrow-area soils for embankment fill construction, and suitability of bedrock foundations. During construction, we provided extensive materials testing and inspection.