Journal Published Online: 23 April 2021
Volume 44, Issue 6

Using Public Well Data Banks to Improve Field Investigations for Excavations



ASTM D420-18, Standard Guide for Site Characterization for Engineering Design and Construction Purposes, states the need “to identify and locate, both horizontally and vertically, significant soil and rock types and groundwater conditions.” Knowing the hydraulic properties of soils and rock is vital for excavations. The project engineers and contractors should have information about expected pumping rate (Q), hydraulic conductivity (K), drawdown, and risks of instabilities. This information is often limited. Experience shows that many engineers and contractors do not consult public data banks for wells, which contain useful but frequently unused information, such as Q values at existing wells near the project. For soils, there are reliable methods to predict the K value. For rocks, the K value is difficult to predict and field results are often highly variable and poorly related to field conditions in excavations. However, a mean K value may be estimated from the specific capacity (SC) value at each tested pumping well (PW). This article presents new practical findings for local correlations between transmissivity and SC, after making a synthesis of over 100 publications. It explains how to derive useful statistics for the Q values distribution and the relative performance of drilling methods, which is rock-specific. This information is a key addition to a field investigation for all professionals involved in a project, especially contractors who have to install dewatering systems for temporary and permanent excavations.

Author Information

Chapuis, Robert P.
Department of Civil, Geological, and Mining Engineering, Polytechnique Montréal, Montreal, Quebec, Canada
Marefat, Vahid
BBA, Department of Earth and Infrastructure, Montreal, Quebec, Canada
Zhang, Lu
College of Construction Engineering, Jilin University, Changchun, Quebec, China
Pages: 22
Price: $25.00
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Stock #: GTJ20200202
ISSN: 0149-6115
DOI: 10.1520/GTJ20200202