Enviro-Core - A Dual-Tube Direct Push System For Rapid Site Characterization

Abstract

Enviro-Core® is a patented dual-tube or “cased” soil coring system that uses small-diameter temporary drive casing to prevent the probe hole from collapsing between sampling runs. The small-diameter drive casing and inner sample barrel are simultaneously pushed, pounded, or vibrated into the ground. Soil cores are collected in liners inside the sample barrel. After being advanced, the sample barrel is retrieved, while the drive casing is left in place to prevent the borehole from collapsing. The drive casing ensures that subsequent samples are collected from the targeted interval, rather than potentially contaminated slough from higher up in the probe hole. The Enviro-Core system is most commonly used with portable sampling rigs that combine percussion hammer and high-frequency vibration to advance the tool, although the system can be used with any direct push (DP) sampling vehicle or conventional drilling rig. The design of the dual-tube sampling system allows consultants to collect depth-discrete soil gas samples, groundwater samples, and install small-diameter temporary or permanent monitoring wells. The system facilitates retraction grouting, the most effective method of sealing DP probe holes. The Enviro-Core® system was used during an accelerated environmental site investigation at Alameda Naval Air Station in Alameda, California. The site geology and contaminant plume were quickly defined in three dimensions, providing the design data necessary to install an experimental in situ funnel-and-gate remediation system.