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Determining Head and Pressure Distribution in Low Transmissivity Formations and Soils
Author(s) -
Kennedy K.G.,
Hollingshead S.C.,
Leech R.E.J.
Publication year - 1986
Publication title -
groundwater monitoring and remediation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 47
eISSN - 1745-6592
pISSN - 1069-3629
DOI - 10.1111/j.1745-6592.1986.tb01246.x
Subject(s) - head (geology) , borehole , hydraulic head , instrumentation (computer programming) , hazardous waste , pressure head , work (physics) , petroleum engineering , geology , soil water , environmental science , geotechnical engineering , soil science , engineering , computer science , mechanical engineering , waste management , geomorphology , operating system
There has been increased interest in low transmissivity formations as barriers to, and hosts for, different hazardous waste. Long periods of time are generally required to measure their in situ pressures or hydraulic heads. Sites need extensive instrumentation and monitoring schemes, which may be costly and may require long periods of time prior to providing well documented site‐specific data. A method has been developed that allows pressure and head distribution to be determined based on limited formation testing. This distribution can then be used to refine the final design of the borehole monitoring instrumentation. Recent work on shallow and deep, hazardous and nuclear waste disposal studies in Canada and Europe has provided the opportunity to investigate different methods for extrapolating and estimating the distribution of pressure and equivalent hydraulic head of the pore water in tight formations. The result is an approach that is cost‐effective, technically reasonable and relatively rapid. The technical basis of the method is not new. However, its application to determining profiles of either formation pressure or hydraulic head has not been well documented. This approach has potential for use in many site investigation studies. The method determines the profile of head or pressure between two “input” layers or formations, which have been well characterized with respect to their pressures or hydraulic heads and associated fluid characteristics. The pressure profile between the two layers is a function principally of the transmissivity of the tight formations between the input layers. Therefore, the primary objective of testing of the zones between the two input layers is designed to quantify this parameter. This testing can be relatively rapid compared to the time required to measure a representative formation pressure or water level. The technique is computerized for efficient tabulation and graphical data display. This paper presents the rationale associated with the extrapolation technique. Examples are given where the technique has been applied to both soil and rock formations with transmissivities less than 10‐8 m2/s and at depths up to 2,000m.