A Civil Action - The Woburn Toxic Trial > Learning Modules > Groundwater Flow

# Learning Module: Groundwater Flow

### Woburn Resources across the site

Overarching Questions:Expert Witness
Key Issues in the Trial: >Woburns water supply; Exploration and Construction of Wells G & H
Resource Collections: Historic Aerial Photos; Well Data

## Module Goal

- Provide an overview of the principles of hydrogeology.
- Complete groundwater contouring exercises.

### Student Assignment: Contouring Potentiometric Surfaces

### Student Assignment: Constructing a Potentiometric Profile

## Overview

When Judge Skinner divided the trial into three separate portions, it became crucial that the parties be able to explain how contaminants traveled from the Grace and Beatrice sites to Wells G & H. The experts employed by both the defense and plaintiffs struggled with familiarizing the jurors the principles of groundwater flow and how their explanations validated their positions.

## Basics of ground-water hydrology

The principles of groundwater flow are based on Darcy's experiments using flow-through cylinders containing porous media (sand). One of the difficulties with understanding ground-water characteristics is related to the inability to directly observed groundwater flow. Groundwater scientist (hydrogeologists) use measurements from wells drilled into the saturated zones along with models (analytical, numerical, scale representations, etc.) to analyze and predict groundwater flow and behavior. The US Geological Survey publication, Water-Supply Paper 2220, a PDF document, is a comprehensive document describing the principles of understanding and evaluating groundwater flow.

An important part of evaluating groundwater is determining groundwater flow directions. determining flow is accomplished by measuring water levels in Wells, correlating the water levels to a common datum (such as sea level) and contouring the water level elevations. when the contours have been drawn, the slope of the contours service reflects the flow direction with higher elevations flowing to those areas were lower elevations occur.

## Activities to help broaden the understanding of groundwater

There are probably several opportunities within the community where groundwater operations can be observed. If nearby communities are served by groundwater supplies, arranging to have students visit the wellfield and see the pumping and distribution operations will provide them with a greater appreciation of the complexity of groundwater as a resource. Industrial sites and gasoline service stations are another potential opportunity to observe groundwater dynamics. There is a possibility at these locations that remedial actions of groundwater have been, or are being implemented. Depending on the nature of the situation, property owners may be amenable to providing a tour of the groundwater collection or treatment operations. any of these opportunities would give students "hands-on" experience regarding some of the issues and professional opportunities related to groundwater science.

## Student Assignments

Constructing Potentiometric Surface Maps

Constructing a Potentionmetric Profile

## More information

Basic Ground-Water Hydrology: USGS Circular 1139

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