Case study: A successful approach to fully characterizing DNAPLs in shallow ground water
- Jacobs Engineering Group, Martinez, CA (United States)
Historically, dense nonaqueous phase liquids (DNAPLs) in the subsurface have been difficult to recognize, and there is equal difficulty in establishing their magnitude and limits. However, through the use of conventional soil borings, cone penetration tests (CPTs) and structure contour mapping, DNAPLs have been successfully identified and fully delineated in a shallow unconfined aquifer at a site in northern California. The compelling nature of the approach is the coupling of standard investigative and mapping techniques with a strict model of depositional process. The site investigation was shifted, after the discovery of DNAPLs, to provide the lithologic detail required to locate and identify DNAPL. The DNAPL was encountered in a shallow sand and gravel aquifer with an underlying aerially extensive silty clay aquitard. The geology, alluvial/fluvial deposition of medium to low energy fan deposits, was the controlling model for the strategic approach of the investigation. Investigative tools were limited to hollow stem auger borings, cone penetration tests (CPTs), and a field screening photoionization detector (PID). Specific techniques were developed to identify the DNAPL in the field. Mapping techniques involved field surveying with a level transit, contouring of lithologic structure (in real time) using computer and manual techniques, and field sketched cross sections.
- OSTI ID:
- 6066407
- Report Number(s):
- CONF-9310166--
- Journal Information:
- Journal of Environmental Health; (United States), Journal Name: Journal of Environmental Health; (United States) Vol. 56:3; ISSN JEVHAH; ISSN 0022-0892
- Country of Publication:
- United States
- Language:
- English
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