Given tightening budgets at Federal, state and corporate levels, there is a need to conduct environmental site assessments in a more time and cost effective manner. The expedited site assessment process (TRIAD) can be an effective approach to help obtain needed subsurface information within budget and time constraints. Direct push (DP) technology provides some powerful logging equipment and methods that can be very effective tools to achieve subsurface investigation goals with high resolution data. This information may then be used to support the design of remediation systems or guide removal actions.
This course will begin with a review of the Expedited Site Assessment (TRIAD) process and how this should be applied to investigating subsurface contamination of petroleum releases, other volatile organic compounds, as well as other common contaminants. The need for three dimensional site characterization will be emphasized. Next the course will introduce attendees to the basics of the hydraulic profiling tool (HPT) and membrane interface probe (MIP) systems. Both of these probes include an electrical conductivity (EC) array that assists with lithology identification. The HPT injects clean water into the formation through a screened port at a flow rate of about 300 ml/min. Logs of the flow rate, pressure and EC versus depth are obtained as the probe is advanced at about 2 cm/sec. The flow and pressure logs (along with EC log) provide information on the lithology and hydraulic properties of the unconsolidated materials being penetrated. Dissipation tests may be performed at selected depths with the HPT probe to assess the local water level and later to provide profiles of estimated hydraulic conductivity (Est. K). The MIP probe and system are primarily used to obtain logs of volatile organic contamination. The MIP probe is equipped with a semi-permeable membrane that is heated to enhance migration of VOCs across the membrane and into the trunkline. Carrier gas (nitrogen) flow transports the VOCs through the trunkline to selected gas chromatograph detectors (PID, FID, XSD, ECD) at the surface. The MIP system provides the operator with a log of total volatile contaminants that can be observed by the detectors in use. The MIP probe is advanced incrementally (often 1 ft/min) and provides a log for each detector, EC, and temperature verses depth. The DI Viewer software (provided free to the class) is used to open, review and print MIP, HPT and EC logs.
Field demonstration of the HPT system will be performed at the field site. Attendees will first see the equipment and set-up process for the HPT system. They will observe and assist with pre-logging QA tests. Once logging is begun attendees will be encouraged to assist with the logging operation. A large monitor/TV will be provided so that attendees can see the log being generated as the probe is advanced. At least one dissipation test will be performed during the log. After completion of the HPT log attendees will be given the opportunity to review the log and assess its quality onsite with the field team. Following lunch the same process will be repeated with the MIP probe and system.
Once field logging is complete the attendees will return to the classroom to use the DI Viewer software to review and interpret the logs obtained at the field site. The use of HPT and EC logs to evaluate lithology/hydrostratigraphy will be reviewed using logs from the field site. Data from a dissipation test will be used to graph the hydrostatic pressure at the site and determine the static water level; this can be compared to existing well data from the site. The HPT and EC logs can be used to locate potential migration pathways and select well screen intervals/locations. The class will also learn how to use the HPT logs and dissipation tests to create a log of estimated K for the logged location. The DI Viewer software also will be used to review and interpret MIP logs, evaluate contaminant levels and assess contaminant type based on differing detector responses. The software will be used to construct log overlays to help with log QC and to construct cross sections of lithology/hydrostratigraphy and contaminant distribution. The course will conclude with a brief summary of materials covered and Q&A session.
Gary Robbins is a Professor of Geology in the Department of Natural Resources and the Environment at the University of Connecticut in Storrs, CT. Professor Robbins is well known for his research work aimed at improving site investigations at contamination sites. Often called "the consultants consultant", he has offered training courses across the country for the private sector and the EPA. He is the author of Expedited Site Assessment: The CD and recipient of the University's Chancellor Information Technology Award. Prior to coming to UConn he worked for Woodward-Clyde Consultants and before that the Nuclear Regulatory Commission. He has been called upon as a private consultant, expert witness and arbitrator for the private sector and government entities. He is a CPG with AIPG, and a Registered Geologist and Certified Engineering Geologist in California.
Wesley McCall, Geologist, Geoprobe Systems, Inc., Salina, KS
Mr. McCall earned his B.S. and M.S. in Geology from Clemson University and the University of Missouri, respectively. He is a licensed geologist (KS28) and has managed investigations using direct push technology for over 20 years. Mr. McCall joined Geoprobe in 1995 where he conducts applications research related to groundwater and environmental investigations. He is active in the ASTM D18 Subcommittee on direct push technology where he has assisted in development of several standards. Wes worked with the Geoprobe R&D team to develop the Pneumatic Slug Test system used for the determination of hydraulic conductivity in wells. He also developed the Mechanical Bladder pump for low flow water quality sampling in small diameter wells. Recently, Wes has been involved with application of Geoprobe’s hydraulic profiling tool (HPT) logging system to evaluate formation permeability and provide high resolution estimates of formation hydraulic conductivity.