STRATIGRAPHICS pioneered high capacity direct-push geo-environmental sampler deployment in the early 1990's, and optimized designs for use in tough, Midwestern USA glacial tills. Our experiences as early developers of CPT methods for geo-environmental applications are referenced in ASTM Direct Push Geo-environmental Sampling Standard D-6001. Penetrometer sampling offers great advantages for geo- environmental studies as the method is rapid, minimally intrusive, and capable of great depth. No drill cuttings requiring expensive disposal are generated during penetrometer direct-push operations. Exposure of personnel to contaminants is typically much less than exposure during drilling or Geoprobe™ operations. Penetrometer operations are also conducted inside the enclosed CPT rig, so they are less visually obvious, which can be of significance when working on sensitive projects.
Groundwater Sampling The STRATIGRAPHICS groundwater sampler is a shielded wellpoint sampler, deployed with the shield closed to avoid contamination and clogging of the sampler screen. The shield is retracted to allow groundwater to flow into the sampler. The sampler can then either be retrieved to decant sample without pumping, or inertial or small diameter bladder pumps are used to purge and pump large sample volumes.
Soil Gas Sampling The STRATIGRAPHICS soil gas sampler is a shielded sampler with a short, heavy slide assembly. The shield is retracted to open the sampler and rod string to the soil, allowing soil gas to flow to the surface. The sampler slide may be opened and closed for multiple depth interval sampling.
Soil Sampling STRATIGRAPHICS uses a piston soil sampler. The sampler is pushed with the piston locked at the tip of the sample barrel to prevent soil from entering the barrel. The piston is unlocked using a wireline tool. The barrel is then advanced, forcing soil to enter the sampler. The sampler is retrieved to extract the soil. Plastic or stainless steel liners can be used with our sampler.
Grouting System We pressure grout open hole using bentonite or bentonite-cement slurry. The grout is pumped into the small annular space between the rod string and soil formed by passage of the slightly larger diameter penetrometer. Additional grout is pumped into the hole during retrieval. Pumping grout around the rod string also can serve to control cross contamination.
Equipment Decontamination The CPT rod string is cleaned before handling by field personnel. All downhole equipment is wiped and can be pressure washed as it is pulled it through a multi-nozzle rod-washer during retrieval. Rubber wipers at the entry and exit of the rod-washing chamber control wash water leakage and wipe soil and grout off the rod string.