Groundwater contamination can affect significantly construction activities in areas of the country where the depth to groundwater is relatively shallow. An innovative method of controlling groundwater contamination plumes during construction to prevent worker exposure to the contaminants and exacerbation of the contaminant plume is presented. Application of this method can reduce delay claims, injuries, and potential litigation related to the contamination. The plume capture principles were applied successfully at two sites with petroleum hydrocarbon groundwater contamination adjacent to a dewatering project in Orlando, Aorida. Contamination plumes were decreased greatly after plume capture, with no exacerbation of either plume.

Construction activities in areas with high groundwater often involve dewatering for installation of utilities, piping, and storm water control structures. The discovery of groundwater contamination in the area can affect the construction schedule since most roadway contractors are not equipped or certified to deal with exposure to contaminants. Initial impacts may include work stoppage, delay claims, and worker compensation claims. In addition, the parties responsible for the contamination may decide to sue if they can demonstrate that the plume was exacerbated. Exacerbation, in such cases, may be defined as enlarging or moving the plume from its preconstruction location. Any movement of this sort tnay prolong the time to remediate the site or require an increase in the number or size of equipment needed for remediation. Either possibility could increase substantially the cost of remediation. In current practice, groundwater contamination usually is addressed if it happens to be discovered during the construction of a transportation project. However, many states have begun procedures to identify contamination in and adjacent to the construction right of way. The Florida Department of Transportation (FDOT) has formalized its contamination assessment procedures in Chapter 22, Part 2 of its Project Design and Environment Manual. This manual has served as the basis for preconstruction assessment'activities for a number of states and countries. The institution of procedures similar to these greatly reduces the difficulty in addressing contaminated sites by allowing more time for avoidance or design and implementation of remedial measures. A firm understanding of the principles of groundwater movement. and control will allow a rapid response to the contamination. Two general situations may be encountered: the first, and most common, is construction through an area of groundwater contamination; the second is construction adjacent to but outside of an area of contamination. Both situations require that a preconstruction assessment be performed. The movement of the contaminated groundwater must be controlled so that the plume is not exacerbated during the project's progression.