The Tulare Lake Composting Facility is a state-of-the-art, 175-acre composting facility located near Kettleman City in Kings County, California. At the facility, an eco-friendly process is used to combine agricultural and green waste from the Central Valley with biosolids from Los Angeles County to create an optimal mixture for composting. The facility currently has the capacity to convert up to 100,000 wet tons per year of anaerobically digested and dewatered biosolids into valuable, nutrient rich, Class A Exceptional Quality compost.
AES provided geotechnical services during the design and construction phases of the Phase 1 improvements. Facilities included composting pads, biofilter, mixing building, pump stations, mixing basins, stormwater reservoirs, wastewater treatment system, non-potable water system, buildings, roads, and pipelines. The site is underlain by several hundred feet of lakebed deposits consisting of soft to medium stiff high plasticity clays. Site constraints included presence of highly compressible clays, shallow groundwater, very high expansion potential and very high sulfate content. Our scope of services included:
Design Phase – Investigations included borings, CPTs, piezometers, geotechnical and chemical testing, falling weight deflectometer testing and settlement monitoring under surcharge loads. Conducted laboratory test trials for alternative stabilization methods including the use of lime treated soil (LTS), lime-flyash and soil cement (SC). The potential for ettringite formation was evaluated under the high sulfate environment.
Flexible pavement design was performed using Mechanical Empirical design (MEPDG) methods and KenPAVE programs were used for pavement performance analyses and design utilizing the results of the falling weight deflectometer data.
Geotechnical design recommendations included shallow and pile foundations; wick drains and surcharging for settlement control; rammed aggregate piers for structure support; soil stabilization to mitigate against expansive soils; protection measures to mitigate against very high sulfate and chloride content and potential for ettringite formation; and design of LTS, lime-flyash and SC mixes.
Construction Phase – AES provided CQA services during construction of the facility including ground improvement; wick drain installation and pre-loading; lime and soil-cement stabilization of subgrade; earthworks and grading; indicator pile program; driven pile installation; low permeability soil liner system installation; geomembrane pond liner installation; geomembrane moisture barrier systems for below grade structures; foundation systems for structures; AC paving; and biofilter media monitoring.