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Former Gasoline Service Station
San Bruno, California
 TEC removed a total of 10 diesel and gasoline underground storage tanks (USTs) at a former service station in San Bruno, including several which were located beneath the street and sidewalk of El Camino Real, a throroughfare which had been widened since the tanks were installed in the 1930s.
Over 3,000 tons of impacted soil were removed from the site. Additionally, TEC designed and installed a high vacuum soil vapor extraction system to remove the remaining residual material in soil. The cleanup was challenging due to heterogeneous, silt-laden soils which caused flow to behave unpredictably and the presence of mat-forming toluene-eating microbes which were present in the soil and had caused system fouling and fouling of the formation.
A number of system modifications were implemented to reduce the impact of site-specific environmental factors (microbial mats) and to cost-effectively reduce concentrations of site contaminants, particularly the fuel oxygenate MTBE, to levels protective of human health and the environment.
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San Francisco, California
TEC identified sensitive receptors immediately downgradient of a former fueling facility that had an unauthorized gasoline release. Using site-specific contaminant concentration, geographical and hydrogeological data, TEC performed a human health risk assessment and back calculated cleanup goals protective of human health and the environment. Additionally, TEC measured direct contaminant concentrations in soil gas and ambient air using a combination of active vapor samples (Summa canisters), passive soil gas samples (sorbent materials), and ambient air samples.
TEC completed remediation of the contaminant source zone (former gasoline underground storage tank pit area) using dual-phase extraction (DPE) technology. In 2010 the DPE system was moved offsite in order to access monitoring/extraction wells within part of the groundwater plume that had detached from the original source area.
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Private Residence, Los Altos Hills
 TEC removed a 635-gal home heating oil tank from beneath a private residence in Los Altos Hills, California. The tank was estimated to have been installed in the 1930s and was composed of single-walled steel; numerous small holes and ruptures were observed in the tank at the time of removal. In less than two months, TEC completed two rounds of site assessment and over-excavated an estimated 15 cubic yards of contaminated soil from the tank pit area, acheiving regulatory site closure for the client under an expedited time frame.
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Gasoline Service Station and Mini-Mart, Richmond, California
 A gasoline service station in Richmond, California had as many as three separate unauthorized gasoline releases from leaking underground storage tanks (USTs) and associated dispenser system installed in the 1950s and removed in 1990s. Groundwater flow beneath the site is complex, involving a confined- to semi-confined aquifer, impacted clayey soils and apparent sinuous preferential groundwater flow pathways.
TEC wrote and implemented dynamic workplans designed to delineate the extent of contamination in a timely and cost-effective manner, including the use of direct push (DPT), hollow stem auger (HSA), and cone penetrometer testing (CPT) technologies, while minimally disturbing business activities at the active gas station. TEC is currently completing a feasibility study to determine the best remedial alternative that will clean soil and groundwater beneath the site and achieve water quality goals protective of human health and the environment.
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Former Gasoline Service Station, Redwood City, California
 TEC designed, installed and operated a dual phase extraction (DPE) system to extract gasoline-contaminated groundwater and vapor from beneath a former service station in Redwood City. Complex site geology and co-mingled contaminant plumes from neighboring service stations lead to the system design of a series of horizontal dewatering pipes, sumps, submersible pumps and air inlets to target high-permeability sandy layers and to prevent the "pulling" of neighboring contaminant plumes onto the client's site.
In order to monitor the DPE system remotely, TEC personnel built and installed a remote photo-ionization detector, which monitors influent concentrations of volatile organic compounds and transmits the data from the SCADA system to a telephone modem for remote access. As of May 2011, this case has been submitted by the county regulatory agency to the State Waterboard for closure review.
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Responded to a diesel fuel spill, caused by the over flow of a 100,000-gallon vertical tank, located within a quarter mile of the San Francisco Bay. This emergency response included product recovery through drilled monitoring well casings, soil and ground water sampling and analyses, and the design of a comprehensive remediation plan. Work was performed per the guidelines of the Code of Federal Regulations (40 CFR 110 and 112) entitled EPA Discharge of Oil (110) and EPA Oil Pollution Prevention (112).
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Design and construction of an impervious liner, drainage, and treatment beds for the remediation of 10,000 cubic yards of soil contaminated with heavy metals and volatile organic compounds.
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The site was an operating gasoline service station. TEC removed four underground storage tanks (USTs) from the site. Analysis of soil samples collected during removal of the USTs detected significant concentrations of petroleum hydrocarbons. The impacted soil was excavated and bio-treated onsite and returned to the excavation after the collection confirmation sampling and proved to be suitable for backfill. A series of soil borings and six monitoring wells onsite and offsite defined the extent of the remaining soil and groundwater impact with gasoline. TEC Accutite completed a site conceptual model (SCM) and a soil vapor survey. Based on non-detect to non-significant impact to nearby sensitive receptor, the site was closed.
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