Soil Contamination Assessment and Remediation

Summary of Expertise

  • Site Characterization
  • Construction Management
  • Remediation Design
  • Regulatory Agency Liaison

Is the soil contaminated? If so, is it contaminated above a level that requires remediation? If so, what is the best remediation methodology given the constraints of budget, site, and regulatory requirements? EarthFax has assisted numerous clients in evaluating these questions. Some of our experience includes:

REMEDIATION DESIGN FOR PETROLEUM CONTAMINATION IN A REMOTE SETTING. On the evening of March 30, 2011 a release of gasoline from a pinhole-sized leak in a refined products pipeline was discovered in a remote location approximately 6 miles southwest of Hagerman, Idaho. The release site is located on the western Snake River Plain and is adjacent to an ephemeral drainage that leads to the Snake River. EarthFax mobilized to the site on March 31 to begin assessing the extent and magnitude of contamination. Data collected from this effort served as the basis for developing a site remediation plan. Thirty-five boreholes were advanced using hollow stem auger and direct push drill rigs. Soil samples were collected from various depths in each borehole and analyzed for the presence of petroleum hydrocarbons to identify the concentration and distribution of gasoline compounds in the soil. Borehole soils were logged and subsurface conditions were modeled to estimate the potential for soil contamination to migrate vertically to groundwater. Groundwater was estimated to be approximately 100 feet below grade and located beneath a confining clay layer. Based on the information gathered from the site investigation, it was determined that remediation of the site using soil vapor extraction (“SVE”) technology would be feasible and could be economically applied in this remote location, due in part to the close proximity of a power pole that could supply electricity to the SVE blowers. Accordingly, an SVE system was designed for the site using a series of vertical underground wells connected to two separate regenerative blowers that extract vapors from the wells. Calculations confirmed that benzene emissions from the blowers would be below the Idaho Department of Environmental Quality emission rate standard. Thus, surface treatment of the emissions was not required. Monitoring and sampling activities are ongoing and will continue until cleanup standards for this site have been achieved.

HIGHWAY SALT STORAGE FACILITY INVESTIGATION, REMEDIAL DESIGN, AND CONSTRUCTION MANAGEMENT. EarthFax evaluated salinity conditions at a highway salt storage facility used to stage activities related to winter road maintenance in northern Utah. The scope of work for this project focused on determining the extent, if any, that salinity levels in soil and groundwater at the site could migrate off site and affect nearby surface and groundwater sources. Of particular concern was the threat of adversely affecting the quality of water in a local drinking water reservoir downstream from the site. EarthFax performed a field reconnaissance to better understand actual site conditions and collected soil and groundwater samples to evaluate subsurface conditions. Based on our investigation, we designed control measures to mitigate off-site migration of salt compounds associated with current and past activities at the site. These measures included controlling storm water run-on and runoff and installing asphalt pavement in salt staging and storage areas. We then provided construction and engineering cost estimates to implement our recommendations; provided construction plans and specifications; and provided construction management services during implementation of the design.

EXCAVATION AND DISPOSAL OF PETROLEUM-CONTAMINATED SOIL. Excavation and disposal plans were developed for sites in Michigan, Pennsylvania, and Utah for the remediation of soils that had been contaminated by refined petroleum products. These sites included an underground jet-fuel storage tank that overflowed during filling, an above-ground fuel-oil storage tank that spilled during filling, and underground gasoline storage tanks that had leaked during years of usage. Excavation of the soils was supervised. Samples of the remaining soils were collected to verify that excavation was complete. Liaison was provided between the clients, excavation contractors, regulatory agencies, and disposal companies during the projects.

EXCAVATION AND BENEFICIAL-REUSE OF PETROLEUM-CONTAMINATED SOIL. Detailed characterization investigations were performed at a former irrigation canal which was situated in a petroleum refinery in Utah. The canal, which had received runoff and seepage of petroleum-contaminated water for approximately 50 years, contained a layer of sludge which required excavation to eliminate future groundwater contamination. Following completion of the assessments to determine the extent and magnitude of contamination, potential disposal alternatives were evaluated, a plan was designed to excavate the 6,000 yd3 of contaminated soil and sludges, plans and specifications were prepared, bid documents were prepared, a contractor was selected, and construction inspection services were provided. Samples were collected during excavation to verify that the contaminated materials had been properly removed. Following excavation, the materials were shipped to a facility for incorporation into asphalt. A quality assurance audit was performed at the asphalt facility to ensure that the long-term liability of the client could be minimized. The excavated canal was then backfilled and graded to serve as a portion of the runoff-control system for the refinery.

SOIL-VAPOR EXTRACTION SYSTEM INSTALLATION. Soil-vapor extraction systems were installed at a propellant manufacturing facility and at a petroleum distribution facility, both in Utah. The propellant manufacturing site had been affected by spillage of contaminated water from a burst waste-water holding tank. The petroleum distribution site was scheduled for facility expansion in an area where soils had been contaminated over a period of several years by miscellaneous leaks and spills. Several vapor extraction wells, observation wells, and air-inlet wells were installed and connected into manifolds and vacuum pumps. Pilot tests were then performed to assess system performance. Following a brief period of performance, the contamination at the propellant manufacturing site had been remediated and the system was shut down. Vapor extraction continues at the petroleum distribution facility. Air samples, air-flow measurements, and vacuum measurements are collected on a regular basis during system operation.

BIOREMEDIATION OF PETROLEUM-CONTAMINATED SOIL. Soils at a natural-gas pipeline compressor station in Idaho, which were contaminated with motor oil and gas condensate due to underground storage tank leaks, had been previously excavated and stockpiled on-site for subsequent treatment. EarthFax supervised the performance of bench-scale biodegradation treatability tests of the soil in a slurry reactor to determine the efficacy of indigenous bacteria for degrading the contaminants. Based on these data, a lined-pad biocell was designed with a basal soil vapor extraction system and overhead nutrient/water application system. The biocell was constructed and operated, during which time air flow, moisture, hydrocarbon concentrations, and total heterotrophic organisms were monitored to track progress of bioremediation. Contamination in the soil was reduced from approximately 7,000 ppm to less than 10 ppm within the one-year treatment period. Approval was subsequently received by the regulatory authority to dismantle the treatment cell and surficially disperse the remediated soils on site.

FUNGAL BIOREMEDIATION OF PESTICIDE-CONTAMINATED SOIL. Toxaphene-contaminated soils present at a crop dusting facility in northern California were bioremediated using white rot fungi. The soils were mixed with a suitable substrate which had been inoculated with the fungi and placed in biotreatment cells. During operation of the project, toxaphene concentrations and environmental conditions (e.g., oxygen levels, moisture content, carbon dioxide levels, and temperature) within the treatment cells were monitored to track progress of fungal bioremediation. Cleanup to concentrations of less than 1 ppm were achieved within nine months from fall through spring.

FUNGAL BIOREMEDIATION OF SOILS AFFECTED BY A WOOD PRESERVATIVE. Approximately 750 tons of soil which had been contaminated by a wood preservative were bioremediated in North Carolina using white rot fungi. Primary contaminants of concern at the site included pentachlorophenol and lindane. An initial bench-scale test and subsequent pilot-scale test were used to develop design criteria for full-scale implementation of the technology. Full-scale construction and monitoring of the biocell were begun in February 1997 and completed in March 1999. Prior to excavation, PCP concentrations in the soil varied up to 2,300 ppm. Following mixing, initial PCP concentrations in the bioremediation cell ranged from 33 to 70 ppm, averaging 51 ppm. Within 31 days, the average PCP concentration had decreased 61% to 20 ppm, well below the industrial treatment goal of 48 ppm. PCP concentrations at the end of treatment averaged 3.0 ppm, compared with a residential treatment goal of 5.3 ppm. Lindane concentrations in the pre-excavation soil varied up to 13,000 ppm. Following mixing, initial lindane concentrations in the bioremediation cell ranged from 7.1 to 37 ppm, averaging 21 ppm. After 15 months of treatment, the average lindane concentration had decreased 82% to 3.8 ppm, which is below the industrial treatment goal of 4.4 ppm. At the end of treatment, lindane concentrations averaged 0.57 ppm, nearly reaching the residential treatment goal of 0.49 ppm. Click here for additional information on this technology and this project.

FUNGAL PILOT-SCALE EVALUATION OF DIOXIN DEGRADATION. EarthFax successfully demonstrated the field degradation of polychlorinated dibenzo-p-dioxins and dibenzo furans in soil at a former wood treatment facility in North Carolina. During the 282-day test, total equivalent concentrations of 2,3,7,8-TCDD were reduced by 63 to 69%, starting from initial concentrations of 13.5 to 16.8 ppb and ending at concentrations of 4.9 to 5.3 ppb. Degradation of individual congeners ranged from 61% to greater than 87%. This is the first known demonstration of this technology for the field degradation of dioxins in soil. Click here for additional information on this technology and this project.

PREPARATION OF AN EXCAVATION PLAN FOR DIOXIN-CONTAMINATED SOIL. An excavation plan was prepared for a former train loading facility that had been contaminated with pesticides and dioxins. The site was located in a high-use commercial/residential area. Haulage routes and handling methods were chosen to minimize potential impacts to adjacent areas.

INVESTIGATION AT THE SITE OF FORMER BAG-HOUSE DUST PITS. EarthFax conducted an investigation at the site of two former bag-house dust pits. The pits were located on the premises of a steel recycling and re-manufacturing facility. Electric arc furnace dust from the bag house, a listed hazardous waste (K061), was disposed of in these pits for a finite period of time. Following discontinuance of this activity and over-excavation of the pits to remove the dust, EarthFax was contracted to collect samples from the pits and submit them for analysis of cadmium, chromium, and lead in the underlying soils. Based on the analytical results of the soil samples, the client opted to pursue risk-based closure under residential criteria for achieving closure of the site. The ecological risk assessment which is required under this rule is currently in progress.

REMOTE DRILLING INVESTIGATION OF EXPLOSIVES CONTAMINATED SOILS. EarthFax participated in sampling and describing soils during an investigation of six former industrial wastewater collection basins located at a rocket motor manufacturing facility. Due to the explosive nature of the contaminants being investigated (ammonium perchlorate, RDX, HMX, nitroglycerin, di-nitroglycerin, nitrocellulose, and other explosive compounds), the borings were advanced using a remotely-operated drill rig and split spoon samplers in soil which ranged from clays to cobbles. Borings were advanced to depths varying up to 23 feet with sampling intervals in each boring ranging from 1 to 2 feet. Due to the potentially explosive nature of many of these compounds, special precautionary safety measures were implemented for field personnel, such as remote drill rig controls which allowed field personnel to work at a minimum distance of 100 feet from the drill site. Sample handling was also closely controlled. A photoionization detector was operated continually to monitor for presence of organic compounds that were also discharged to the basins.

SOIL CONTAMINATION INVESTIGATION AND REMEDIAL-ACTION PLAN DEVELOPMENT FOR A CHROME-PLATING OPERATION. The extent and magnitude of soil contamination was assessed near a chrome-plating facility. Past discharges of chromium-contaminated wastewater had resulted in both horizontal and vertical contamination of soils near the facility. Soil samples were collected and the volume of contaminated material was delineated. Liaison with regulatory agencies was provided during development of a Consent Order that required remediation of past contamination. A site remediation plan was then designed.

REMEDIATION OF CONTAMINATED SOIL AT AN OIL AND GAS PRODUCTION FIELD. Over the past several years, remedial measures for contaminated soil have been provided for an oil production company in southern Michigan. These services have been provided at approximately 130 wellheads and 55 facilities in the Albion-Scipio field as a result of hydrocarbon product losses. Remedial measures have primarily included excavation and disposal of contaminated soil at approved landfills and ex-situ bioremediation. EarthFax personnel provided services which included assessment of the extent and magnitude of contamination, evaluation and design of treatment alternatives, and oversight of remedial activities to ensure compliance with federal, state, and local regulatory constraints.

BASELINE ENVIRONMENTAL CHEMISTRY INVESTIGATIONS. Soil samples were collected at the sites of a proposed hazardous-waste incinerator and associated landfill to assess baseline soil chemistry prior to facility construction. Data were analyzed to determine statistical trends in background soil chemistry. Several monitoring wells were also installed to assess the rate and direction of groundwater flow at the site of the proposed landfill. Baseline groundwater-quality samples were also collected. The data were collected to support future decisions if remediation becomes necessary.

PERFORMANCE OF SOIL-GAS SURVEYS. Soil-gas surveys have been performed in the vicinity of several leaking underground fuel storage tanks and a refinery tank farm to determine the extent of soil and groundwater contamination. The tanks have often been located in areas of difficult access (beneath concrete pads, parking lots, and adjacent to electrical substations). Results of the surveys have been used to design groundwater monitoring networks and remedial-action plans.

CONTAMINATION ASSESSMENT OF PHOTO PROCESSING FACILITIES. Wastewater discharges, treatment system discharges, and soils were sampled at three photo processing facilities in Utah to determine treatment system efficiency and the extent of contamination from wastewater discharges. Chemical data were interpreted and a more-detailed sampling program was designed to allow collection of data required for development of a closure plan.

ASSESSMENT AND REMEDIATION OF ENVIRONMENTAL CONTAMINATION AT A PROPOSED RESIDENTIAL DEVELOPMENT SITE.  EarthFax provided extensive environmental assessment services at the site of a proposed residential development in southwest Utah.  The purpose of this project was done to identify potentially contaminated soil and rock left behind from historic silver and uranium mining activities on and adjacent to the 80-acre site.  Work performed by EarthFax was conducted in accordance with an agreement between the client and the Utah Division of Environmental Response and Remediation (“UDERR”) to assess and remediate the site under UDERR’s Voluntary Cleanup Program. 

Based on historic information and site visits, EarthFax identified areas of probable elevated soil contamination and probable low soil contamination.  We developed and implemented a sampling and analysis plan to investigate the presence of elevated metals and radiologic compounds in soil using guidance developed by U.S. EPA.  Sampling procedures, decontamination of sampling equipment, site survey control, sample handling and custody, and analytical methods were addressed in the plan.  A focal point of the plan was to identify areas where human health risk factors are evident and eliminate areas from further consideration where these risk factors do not exist. 

Following site characterization, we designed a remedial-action plan to remove impacted soil and meet target cleanup goals consistent with a residential land-use scenario.  We also prepared supporting documents (e.g., bids, plans, specifications, etc.) that would allow construction contractors to prepare bids to remediate areas of concern.  Project work was planned and implemented by EarthFax in such a way that the client was able to successfully assess and remediate the property using a phased approach.  This allowed the client to proceed with residential development in a timely manner while continuing to meet the requirements agreed to under the Voluntary Cleanup Program.

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7324 South Union Park Ave., Midvale, Utah 84047 | Phone: 801-561-1555

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