ABSTRACT
This paper reviews literature on the quality of highway runoff and potential impacts on karst ground water quality from construction, maintenance, and operation of highways and associated facilities. This review is part of a preliminary phase of a project being conducted by P.E. LaMoreaux & Associates, Inc. (PELA) for the Federal Highway Administration (FHWA). The primary goal of the project is the development of practical remedial technology for improving the quality of highway runoff in karst areas. Stormwater runoff is an important source of nonpoint pollution to surface and ground water, transporting solids, heavy metals, nutrients, bacteria, road salt, herbicides, and hydrocarbons from highways. Factors affecting highway runoff contamination include traffic characteristics and adjacent land use patterns, as well as other design, administrative, and environmental considerations. Local hydrogeologic conditions also influence the impact of highway runoff on ground water quality. In particular, highway runoff may have a more significant impact on ground water quality in karst terranes, where soils may be thin or nonexistent and where ground water recharge occurs directly through fractures, sinkholes, and sinking streams. Impacts to karst aquifers have been documented from highway-related particulate material, oil and grease, heavy metals, and chlorides. While it has also been suggested that highways are minor contributors of karst ground water pollution compared to other land uses, relatively little attention has been focused specifically on this topic. Most studies on highway runoff and ground water quality have been conducted in areas of relatively thick soils, which immobilize many runoff pollutants. The results of these studies cannot be applied in many karst areas, where percolation through soil is minimal or nonexistent.
