Cone Penetrometer Testing and Discrete‐Depth Ground Water SamplingL Techniques: A Cost‐Effective Method of Site Characterization in a Multiple‐Aquifer Setting

Abstract

Cone penetromcler testing (CPT). combined with discrete‐depth ground water sampling methods, can significantly reduce the time and expense required to characterize large sites that have multiple aquifers. Results from the screening site characterization can then be used to design and install a cost‐effective monitoring well network. At a site in northern California, it was necessary to characterize the stratigraphy and the distribution of volatile organic compounds (VC)Cs) to a depth of 80 feet within a ½‐mile‐by‐½‐mile residential and commercial area in a complex alluvial fan setting. To expedite characterization, a five‐week field screening program was implemented that consisted of a shallow ground water survey, CPT soundings and pore‐pressure measurements, and discrete‐depth ground water sampling. Based on continuous lithologic information provided by the CPT soundings, four predominantly coarse‐grained, water yielding stratigraphic packages were identified. Individual coarse‐grained units within each package are discontinuous, as they coalesce and pinch out in longitudinal and transverse directions. Seventy‐nine discrete‐depth ground water samples were collected using either shallow ground water survey techniques, the BAT Enviroprobe, or the QED HydroPunch I, depending on subsurface conditions. Using results from these efforts, a 20‐well monitoring network was designed and installed to monitor critical points within each stratigraphic package. Good correlation was found for hydraulic head and chemical results between discrete‐depth screening data and monitoring well data. Understanding the vertical VOC distribution and concentrations produced substantial time and cost savings by minimizing the number of permanent monitoring wells and reducing the number of costly conductor casings that had to be installed. Additionally, significant long‐term cost savings will result from reduced sampling costs, because fewer wells comprise the monitoring network. We estimate these savings to be 50 percent for site characterization costs, 65 percent for site characterization time, and 60 percent for long term monitoring costs.

Metals in Surface, Ground, and Mineral Waters

“…37 Sampling for trace metals has also been the subject of a review with 59 references. 39 In a seven-year study, tritium has been used to monitor groundwater movement through a nuclear test site. 32,33 Cone penetrometer testing combined with discrete-depth groundwater sampling were found to reduce the time and money required to characterize a large site with multiple aquifers.…”

Development and preliminary evaluation of a cone penetrometer-based method forin situ determination of volatile organic compounds in groundwater

“…2 In addition, CPT has been used over the last decade for a broad range of sampling and analytical techniques for the chemical characterization of the subsurface. 3 In situ chemical samplers can be driven into the subsurface by CPT to collect soil gas, 4,5 groundwater, [6][7][8][9][10][11][12][13][14] or soil samples 15 at depth, thus providing a means of determining the vertical and horizontal extent of contamination. Furthermore, CPT has also been used as a means of delivering various in situ subsurface sensor probes, including laser-induced fluorescence spectroscopy for organics, [16][17][18][19][20][21][22][23][24][25] x-ray fluorescence 26,27 and laser-induced breakdown spectroscopies 28,29 for heavy metals, gamma ray spectroscopy for radionuclides, 30 and optical and electrochemical sensors for chlorinated organics 31 and explosives, 32 respectively.…”