Modeling Microbial Transport in Soil and Groundwater Microbiologists can assist in the development of models of contaminant transport

Federal, state, and local govermnent agencies are issuing more and more regulations to protect groundwater from microbial contamination. Regulations being proposed include the establishment of wellhead protection zones, drinking-water standards for viruses and parasites, and septic tank placement ordinances. Microbiologists are being called upon more frequently than ever to work with the engineers, hydrologists, geologists, and soil scientists who are developing and using predictive models of contaminant transport. Because microbiologists frequently lack training in modeling and the modelers have little or no knowledge of microbiology, communication problems can develop. Modelers require information about the factors that affect microbial transport, but many times that information is not available in a directly usable form. With a better appreciation of what modelers need to know, microbiologists can help overcome some of these communication problems. The use of contaminant transport models for purposes of groundwater protection and bioremediation will likely increase in the future. Such use can help in establishing wellhead protection zones within which potential sources of contamination may not be placed and in granting variances from a mandatory groundwater disinfection requirement (to inactivate viruses and Giardia spp. in drinking water) that the U.S. Environmental Protection Agency plans to publish in the near future. Typical contaminant transport models are designed to predict how many microorganisms applied to the soil at point A reach point B. Point B may be a