Site Investigation & Corrective Action


Former Service Station Assessment & Cleanup

Blackshare was retained by a State agency when gasoline odor complaints were received in the basement of a residence that was once a country store and gas station. Air samples confirmed the presence of benzene in the basement. Although no longer used, there was also a water well located on the property. The underground tanks were located adjacent to the basement but had already been removed so the presumed source of benzene was residual soil and/or groundwater. Blackshare conducted an investigation and eventually designed and oversaw the installation of an interceptor trench to prevent the benzene vapors from entering the basement. The case was closed by the State with no further action.

Investigation and Cleanup of Subsurface PCB Leak

Blackshare conducted an investigation of the subsurface beneath two concrete transformer pads where PCB laden dielectric fluid had leaked over a substantial period of time. Using direct push technology to delineate the PCB contamination, our team discovered elevated levels of PCBs at depths up to five feet. The concrete pads were removed and disposed of as PCB contaminated waste. An excavation plan was developed based on the subsurface investigation and a grid pattern was established for the initial excavation and removal of contaminated soil. Field analysis kits were also utilized to guide the excavation activities and confirmation samples were shipped to a certified laboratory in order to verify field results. The PCB contaminated soil was shipped to a permitted hazardous waste landfill and the excavated area was backfilled with clean soil.

Cleanup of Illegally Dumped Glass Furnaces

Blackshare completed investigations of three separate sites where waste from the routine demolition of glass furnaces was illegally dumped. The material consisted mainly of fire brick, glass cullet and silica sand. Upon discovery of the sites, a Notice of Violation (NOV) was issued to both the waste generator and the disposal contractor who actually dumped the waste. Which required full characterization of each of the sites. The characterization process involved drilling to determine the horizontal and vertical extent of buried waste and potential associated groundwater impact. Significant chemical and geotechnical analyses were involved with the characterization. Blackshare prepared and implemented a plan, certified by a PE, to safely and successfully remove and properly dispose of all buried waste.

Groundwater Recovery and Treatment System

Blackshare was contracted by a large manufacturing company to operate and maintain the operation and maintenance of a groundwater recovery and treatment system. The treatment system was installed to remediate a plume of dissolved-phase aromatic and chlorinated hydrocarbons which resulted from two leaking underground storage tanks. Over forty monitor/recovery wells have been installed and the treatment uses soil vapor extraction and aquifer air sparging technology. In addition to bi-weekly maintenance and quarterly monitor well sampling, modifications were made to improve the performance of the treatment system.

Voluntary Cleanup Program (VCP)/Brownfields Project of Commercial Development

Blackshare was retained for two different sites when Phase I ESA activities discovered historical industrial activities had resulted in subsurface contamination. Because the developments were for a large, national chain, they required that any contamination be disclosed to the appropriate regulators and concurrence received that no further action was necessary. With Blackshare’s assistance, the client determined that the VCP option was best for both sites. Blackshare completed all site characterization field work and proposed risk-based cleanup levels to the regulatory agency. The levels were approved which required minimal soil excavation and resulted in a “no further action” letter for both sites.

Ivestigations of Subsurface Hydrocarbon Contamination

Blackshare routinely conducts investigations of subsurface hydrocarbon contamination, usually resulting from USTs, for state regulation agencies and/or municipalities. These investigations are often done as part of larger road construction widening projects. These involve the installation of soil borings on monitoring wells, collection of soil and groundwater samples, analysis and completion of a Risk-Based Corrective Action (Risk Assessment), site remediation and closure activities including but not limited to disposal of auger cuttings and purged well water and plugging of all wells. Utility trenches are located and evaluated as well, as they are often pathways for contaminants to travel and impact other properties.

Natural Gas Foundation Venting - Residential Property

Complaining of natural gas accumulating around the foundation of his house, a Tulsa homeowner engaged Blackshare to disperse the gas and locate its source. Blackshare designed and installed a collection system which consisted of a series of buried collection pipes and a blower which safely vented the gas above the roof line. Blackshare then assisted in locating the natural gas source, which turned out to be an unplugged gas well. The well was plugged and the source was eliminated.

Mercury Cleanup - Oil & Gas Meters

Following an investigation by a client which revealed mercury contamination in the soil, Blackshare was retained to negotiate cleanup levels with the state regulatory agency under the Voluntary Cleanup Program (VCP). Direct negotiations with the agency resulted in risk-based cleanup levels which were less stringent and less costly for the client while still achieving protection to human health and the environment. Blackshare conducted an initial soil event sampling to better define the area of contamination based on the negotiated cleanup level. After defining the contaminated area, soil was excavated using high-vacuum technology. The impacted soil was containerized and Blackshare arranged for soil disposal at a permitted landfill facility. The excavation and disposal was approved granting a "No Further Action" letter to the client.

Pipeline Terminal Gasoline Release Cleanup

A pipeline company discovered a gasoline release at one of its storage terminal. The initial site investigation confirmed that subsurface soil and groundwater near the point of release were affected by petroleum products. A series of geoprobe borings located and delineated the gasoline plume. Free product ranging in thickness from a sheen on the water to over two inches was recorded in twenty-one of the borings. Based on physical site factors, Blackshare recommended Mobile Dual Phase Extraction (MDPE) technology in order to remove the free product and achieve the required cleanup levels at the site. The MDPE process was successful in extracting, under high vacuum pressures, hydrocarbons at the water interface as well as the unsaturated zone. Hydrocarbon contaminants in ground water were reduced to risk-based levels that allowed the case to be closed.

Oilfield Disposal Site Assessment & Cleanup

Blackshare was hired by an attorney when an oilfield disposal site was cited for illegally dumping oilfield waste in unlined pits. Blackshare developed a work plan which was submitted and approved by the State. Next, Blackshare conducted field activities to delineate the degree and extent of contamination from the illegal dumping. Eventually, a remediation plan was developed and approved by the State. Once it was completed, the project was approved by the State and the enforcement action closed.