36 NOVEMBER 2025 WorldWide Drilling Resource® Tools Used for Subsurface Investigation Adapted from Information by the Illinois Environmental Protection Agency (EPA) The Illinois EPA’s Office of Site Evaluation (OSE) primarily conducts subsurface investigations using two agency-owned Geoprobe Systems® direct-push machines, specifically models 5400 and 6600. These hydraulically powered machines utilize a combination of static force and percussion to drive sampling and logging tools deep into the ground. During soil boring procedures, a four- to five-foot Macro-Core® Sampler is pushed into the ground repeatedly to extract soil cores. The collected subsurface material is kept secure within a plastic liner residing inside the Sampler. Once the Sampler is extracted, the soil core can be examined, analyzed on-site, and sampled for further laboratory testing after removing the plastic liner. The X-Ray Florescence (XRF) analyzer employs high-energy x-ray photons that interact with atoms in the sample, causing them to emit secondary x-ray, or fluorescence. The XRF detector captures these signals and processes them to ascertain specific elemental concentrations in the soil directly beneath the device. This analysis yields accurate results which are instantly available for field personnel. The XRF has proven to be invaluable for assessing the extent of metal contamination during site characterization and remediation, as well as for ruling out certain areas for additional testing. The Illinois EPA relies on XRF for measuring metal concentration in soil and sediments at evaluated sites. The Geonics EM-61 is a high-sensitivity metal detector featuring twin coils, designed to locate both ferrous and nonferrous metallic objects underground. It operates by generating a pulsed primary magnetic field through a powerful transmitter, which induces eddy currents in nearby metal objects; these are then detected by the twin coils. The EM-61 can identify a 55-gallon drum buried up to ten feet deep while remaining sensitive enough to ignore surface metal objects like fences, buildings, and vehicles. Illinois EPA found the EM-61 to be particularly effective in assessing whether underground storage tanks at older sites have been removed or are still there. The Membrane Interface Probe (MIP), developed by Geoprobe Systems, is a direct sensing tool measuring the electrical conductivity of subsurface materials while detecting Volatile Organic Compounds (VOCs). The Illinois EPA’s OSE utilizes the MIP to receive immediate indications of VOC presence in soil and groundwater, eliminating the need for sample collection and laboratory analysis. Data contained from the MIP aids in pinpointing contaminated soil layers and aquifers from which laboratory samples can be taken. The electrical conductivity readings can also highlight variations in soil types. This system offers numerous advantages, including the detection of contaminants in both coarse and fine soil, saturated and unsaturated conditions, along with distinguishing between chlorinated and nonchlorinated VOCs. Multiple MIP logs produced at a site can help ascertain the contamination source area, movement and depth of contaminants, and are crucial for determining appropriate remediation strategies. With these Geoprobe Systems, the OSE can efficiently collect soil, groundwater, and soil gas samples, install two-inch monitoring wells through traditional rotary techniques, set up prepack monitoring wells and piezometers using direct-push methods, core concrete, as well as deploy direct sensing instruments. These machines have significantly streamlined the process of obtaining soil and groundwater samples, allowing them to reach depths exceeding 100 feet. X-Ray Fluorescence Geonics EM-61 ENV See us at Booth 2915 Groundwater Week 2025 in New Orleans
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