Transmissivity and storage coefficient estimates from slug tests, Naval Air Warfare Center, West Trenton, New Jersey

• Home
• List of Figures and Tables
• Conversion Factors
• Abstract
• Introduction
• Methods
• Results
• Summary
• Acknowledgments
• References Cited
• Index

Introduction

Slug tests are a simple and efficient method for evaluating aquifer hydraulic properties in the immediate vicinity of a well’s open interval. In fractured-rock aquifers, hydraulic properties are very heterogeneous, so information on aquifer properties at multiple locations is useful for characterizing groundwater flow. The former Naval Air Warfare Center (NAWC) in West Trenton, New Jersey, is a chlorinated volatile organic compound contaminated site that overlies fractured shale, mudstone, and sandstone bedrock aquifers of the Newark Supergroup (Lacombe, 2000; Lacombe and Burton, 2010). Slug testing is one of several methods being used to estimate aquifer properties at NAWC to further the understanding of groundwater flow and contaminant transport at the site (Goode and others, 2007).

Purpose and Scope

This report documents estimates of transmissivity (T) and storage coefficient (S) for aquifer material surrounding 56 wells at NAWC (fig. 1) obtained by analysis of data from slug tests performed during November 2012–July 2013. The observation wells tested are open to the fractured bedrock. Shallow wells open to regolith, wells containing packer strings, and wells in the pump-and-treat system active at the site were not tested.

Previous Investigations

International Technology (IT) Corporation (1994) conducted slug tests in 12 observation wells at NAWC, including three shallow wells open to regolith. The U.S. Geological Survey (USGS) conducted slug tests in 42 bedrock wells, 7 pumping wells, and 31 shallow wells at NAWC in 1997 (Lewis-Brown and Rice, 2002). Several bedrock wells were not tested during those studies, and many wells have been drilled at NAWC since. Aquifer-test estimates of T and S were made by IT Corporation (1994), EA Engineering, Science, and Technology, Inc. (1996), and Lewis-Brown and others (2005). However, aquifer-test results represent a relatively larger volume of aquifer surrounding a well, so discrepancies may occur between aquifer-test and slug-test estimates of aquifer properties. Tiedeman and others (2010) estimated spatially variable T and S at the site scale by calibration of a groundwater flow model to water–level responses during multiple pumping-well-shutdown tests. Williams and others (2007) conducted cross-hole borehole flowmeter logging to identify hydraulic connections between wells and estimate T of discrete fracture zones.