25 APRIL 2023 WorldWide Drilling Resource® Exploration Diversity for PFAS by Craig W. Coolidge, P.E., Vice President - Principal Engineer Summit Geoengineering Services This article summarizes the advantages of exploration diversity for the investigation of PFAS (per-and-polyfluoroalkyl substances). PFAS are widely used long-lasting chemicals which break down slowly over time. The widespread use and persistence in the environment present a growing need for investigating PFAS within soil, bedrock, and groundwater. Multipurpose drill rigs can provide efficiency in performing PFAS subsurface investigations as they are capable of conducting a range of exploration techniques suited for variable subsurface conditions. Traditional exploration equipment is designed to perform specific exploration methods such as drill rigs for geotechnical test borings, direct-push rigs for environmental test borings, and heavy push rigs for piezocone penetration testing (CPTu). Results of CPTu are interpreted for soil type and groundwater conditions. Exploration equipment is now available which can perform a range of test boring methodologies along with the ability to conduct CPTu utilizing the same exploration machine. An example of exploration diversity is demonstrated by a recent subsurface investigation for potential PFAS performed by Summit Geoengineering Services with an AMS PowerProbe™multipurpose drill rig. The scope of work consisted of performing subsurface explorations and the installation of groundwater monitoring wells at a mixed-use facility in Maine. In total, 120 explorations were performed with 65 monitoring wells installed and 25 CPTu conducted for deep soil profiling. Bedrock coring and installation of a 2-inch PVC monitoring well was installed at one location of shallow bedrock. Rock coring was performed using an N-core barrel for a depth of 20 feet into bedrock. The use of a multipurpose drill rig provided flexibility to conduct CPTu, direct-push soil sampling, monitoring well installation, and shallow rock coring. This flexibility provided the following advantages to the project: • Potential cost savings due to the reduced number of subcontractors and/or task-specific drill rigs. • Use of CPTu improved identification of sand layers within deeper interbedded marine deposits which were targeted as part of the environmental investigation. • Significant reduction of drill water and soil cuttings by use of CPTu with directpush methodology for soil sampling and monitoring well installation as compared to using rotary wash with SPT (standard penetration test) sampling for deep test borings requiring containerization of materials and increasing exposure risk to the field crew conducting the work. • Ability of the multipurpose drill rig to adapt between shallow and deep exploration drilling techniques permitting efficient mobilization and setup at the site between boring locations. ENV eranhenderson@gmail.com New & Used Tricones PDCs Drag & Claw Bits Drill Collars Bit Tipping Subs & Stabilizers HDD Bits & Reamers DTH Hammer & Bits Custom Fabrication Junk Mills / Fishing Tools Rod Henderson 661-201-6259 Eran Henderson 661-330-0790
RkJQdWJsaXNoZXIy NDk4Mzk=