This map shows groundwater pollution potential in Williams County

This map shows groundwater pollution potential in Williams County as calculated by BGSU graduate student Ryan Dickerson using a modified DRASTIC model. The colors correspond to Pollution Potential Index Values determined by DRASTIC, with yellow, orange and red representing the areas of the county with the highest sensitivity to possible groundwater pollution. The black dots are the locations of existing confined animal feeding operations (CAFOs) in the county.

What’s the best site for a ‘factory farm’? BGSU student’s model may help

Some people advocate drastic action to keep confined animal feeding operations (CAFOs) out of their rural backyards.

Ryan Dickerson, a graduate student in geology, believes DRASTIC action is a good way to determine the best sites for such operations, sometimes known as “factory farms.”

DRASTIC, in this case, is an acronym for seven hydrologic parameters deemed crucial for assessing groundwater pollution potential, starting with depth to water and also including aquifer media, soils media and topography. Developed for the U.S. Environmental Protection Agency in 1987, the model uses an equation to calculate a number that represents a relative pollution potential value, Dickerson explained.

The master’s degree student from Arcadia has applied a slightly modified version of DRASTIC to Williams County, the site of three dairy CAFOs and rumored location of a multimillion chicken egg-laying facility. He presented his research April 12 at the joint meeting of the North-Central and South-Central Sections of the Geological Society of America, held at the University of Kansas.

Dickerson, who already holds a bachelor’s degree in environmental policy and analysis from BGSU, focused on Williams County due to what he called its “unique hydrological setup.” The county’s groundwater comes from a glacial outwash aquifer that makes its well yields more productive than the rest of northwest Ohio, he said. But because water moves quickly through the largely sand and gravel aquifer, it’s also more susceptible to pollution, he added.

At the same time, the water supply makes the county a prime target for development of CAFOs, which use a lot of water, Dickerson noted. And when wells draw a lot of water, he continued, the water table is lowered and water quality can be affected.

He summarized the primary concerns driving his research as “the potential for pollution from failure of manure lagoon liners and lagoon leakage, and the potential for contaminants to enter groundwater supplies from the application of manure wastewater as fertilizer.”

“These (CAFOs) are a developing feature of the Ohio landscape,” he said, maintaining that because livestock manure is laden with pathogens, antibiotics and heavy metals, as well as nutrients, and because a vast majority of the state relies on groundwater, a scientific approach should be taken from a hydrologic standpoint to finding sites for the large operations.

“I really just want to bring some science into the equation,” said Dickerson. He did so in his study by taking the parameters of DRASTIC; making a few alterations, including increasing the importance of soils media to reflect recent research that has shown complex fluid pathways downward in what were thought to be generally impermeable soils, such as clay; adding a land cover/use parameter, and applying Geographic Information Systems (GIS) software to manage the hydrologic data and create a “layer cake”-like map.

Land cover plays an important role in how wastewater-based fertilizer will react on the surface, he pointed out, saying that U.S. Geologic Survey data indicated 11 types of land cover in Williams County.

Dickerson concluded that the areas of the county most sensitive to possible groundwater pollution are along the St. Joseph River and generally in central Williams County. Noting that the findings will be shared with a local group interested in the integrity and protection of the aquifer, he added that his methods could also be applied elsewhere.

Because the Ohio Department of Natural Resources has constructed DRASTIC maps with GIS data for 68 of the state’s 88 counties—including Williams—his approach could be replicated for any of those counties, Dickerson said.

It provides a more thorough picture, he maintained, than the current assessment, which, with Ohio Department of Agriculture oversight, involves taking core samples as part of examining proposed CAFO sites. That method doesn’t fully take pollution pathways into account, according to Dickerson.

He wants his approach to be seen not as anti-business or anti-agriculture in nature, but as a “preliminary screening tool” to encourage site-specific investigations by land use planners and managers. It should help prioritize areas of importance for protection, indicating where water quality monitoring should be emphasized, and thus where resources should be allocated for that monitoring, he said.

Dr. Enrique Gomezdelcampo, Dickerson’s faculty advisor, said the research “is significant because of its direct application to a current concern in the region and its usefulness for decision makers.

“CAFOs are going to exist as long as we don’t incorporate the environmental costs of food production into its price,” added the assistant professor of geology and environmental programs. “Ryan’s modifications to a well-known hydrogeologic tool makes it easy for county planners to determine in what area of the county a CAFO would have the potential to cause the least amount of damage to the water resources.”

In addition to his presentation at the Geological Society of America meeting—which he called “a good environment to get feedback on work”—Dickerson plans to submit a manuscript describing his study to the Journal of Environmental Geology. He expects to receive his master’s degree from BGSU in August.

April 16, 2007