A piezocone is a direct push sensor probe consisting of a porous element connected to a customized transducer that converts pore pressure to water level. A high-resolution piezocone (HRP) (U.S. Patents 6,208,940 and 6,236,941) is a sensor probe capable of generating highly resolved hydraulic head values (plus or minus 1-inch of water level) while simultaneously collecting critical soil type information. The GeoVIS (U.S. Patent 6,115,061) is a Navy/SERDP-developed video microscope sensor probe capable of yielding real-time soil and contaminant images that can render effective porosity estimates.

The objective of this demonstration, conducted at the National Environmental Technology Test Site (NETTS) in Port Hueneme, California, was to demonstrate two innovative direct push sensor systems, the HRP and GeoVIS, to determine the direction and rate of groundwater flow in three dimensions (3-D).

The demonstration included: (1) modification of existing data collection and processing software to simplify and automate the two probe systems’ operational functions; (2) modification of Groundwater Modeling System (GMS) software, providing highly resolved 3-D conceptual and analytical renderings of seepage velocity and contaminant flux distributions; (3) validation of the probe systems and software for generating 3-D distributions of hydraulic head, hydraulic gradient, and effective porosity through statistical interpolation; (4) generation of technically defensible and representative data for regulatory consideration; and (5) technology transfer at government and private sector sites. A government/industry advisory committee was established to assist with overall scoping, development of performance metrics, and facilitation of technology transfer.

While the GeoVIS did not provide accurate effective porosity values in the silty soils encountered, the HRP provided representative hydraulic head, hydraulic conductivity, soil type, and effective porosity data, enabling users to develop highly resolved 3-D models and predictions of contaminant flux distributions that compared favorably to short screen well-based methods. Project results were incorporated into Interstate Technology & Regulatory Council (ITRC) guidance and ASTM standard 6067, and the HRP technology was licensed to the private sector.

This technology can replace costly and inappropriate conventional hydraulic assessments and will be useful during remedial action objective (RAO) and long-term monitoring (LTM) phases of a project. It can be used to determine the contaminant flux distribution and enable remedial project managers to prioritize and target areas for surgical removal, remediation, and containment. This technology facilitates generation of a high-resolution conceptual model, proper placement and design of monitoring wells, and generation of input to models for projecting time of remediation, exposure point concentration near potential receptors, and comparison to competing model designs. When compared to conventional approaches comprised of clustered well installations, aquifer tests, sample analyses, and 3-D and cross-sectional interpolations, cost savings for flux distribution determination using the HRP coupled with chemical characterization probe systems exceeds 60%. (Project Completed - 2008)