November 2012 Meeting

Monday, November 12, 2012
6:00 - 7:30 pm

Pellissippi State Technical Community College
10915 Hardin Valley Road, Knoxville
J.L Goins Administration Building, Cafeteria Annex


Assessing Pathogen Fate

Bob Hunter
Department of Earth and Planetary Sciences
University of Tennessee, Knoxville


Dairy farms typically produce large quantities of manure and other waste products which are often stored or treated in lagoons and then applied to local fields as fertilizer. Contamination of nearby streams by dairy farm wastes through surface runoff, drainage tile discharge, direct release of wastes, or inundation of waste storage facilities during seasonal flooding have long been recognized as major environmental concerns. However, much less attention has been paid to fate and transport of dairy wastes (including fecal microorganisms and nutrients) in the subsurface and their potential impact on water quality in aquifers or in groundwater discharge to streams. A challenge in evaluating the environmental impact of dairy operations is that there are relatively few field research sites where all of the potential pathways for waterborne transport of dairy wastes are monitored and quantitatively evaluated. There are even fewer sites where extensive baseline water quality monitoring programs were established prior to operation of the dairy. This is essential to distinguish between environmental impacts from dairy operations and other nearby sources, such as up gradient dairy farms, beef production, poultry and swine operations, as well as wildlife and human sewage from septic fields. This presentation describes the development of an integrated hydrogeologic/hydrologic site assessment and groundwater/surface water quality monitoring program at the University of Tennessee &ndash Little River Dairy Farm, located near Townsend, TN. The dairy was completed in late 2011 and is now operating with 80 cows with expectancy of 200 for full operation. Hydrologic/hydrogeologic investigations of streams and groundwater at the site have been underway for more than 4 years, and these are providing background data using E. coli and nutrients to help assess impacts of dairy wastes and for testing the effectiveness of different management practises. The lower half of the ~180 ha site consists of low-relief fields used for row crops, which are underlain by 4 &ndash 8 m of alluvial deposits (mainly medium to fine-grained sands interbedded with silt) on top of middle Ordovician black shale, limestone, and dolomite. Active sinkholes are present in the vicinity of a limestone/dolomite contact zone. The site is bounded on two sides by the Little River, a popular recreational river, and on the third side by Ellejoy Creek, which is on the state&rsquos 303(d) list for impairment by nutrients, sediment, and fecal microorganisms derived from upstream agricultural and rural residential development. Fields will be fertilized with treated dairy wastes and are the main area of concern for offsite migration of contaminants through groundwater, drainage ditches, and (eventually) a tile drain system. A secondary area of concern is the dairy waste treatment pond, located near the dairy barns on the upland portion of the site, underlain by 1-2 m of clay-rich residual soils developed on fractured shale bedrock. The monitoring program was recently expanded to include selected bovine pathogens at points of entry to, and exit from, the dairy farm property. This will provide a broader measure of the overall impact of the dairy and provide information that could be relevant to herd health assessment.


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