Objectives:

1. Determine rates of seepage lose to the surficial aquifer from established lagoons in the coastal plain.

2. Develop methods for direct seepage assessment that can be used without disruption of normal operations.

3. Determine rates of nutrient loading to ground and surface waters,due to seepage.

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Accomplishments:

1. Almost 30 established, unlined lagoons have been examined for seepage losses, about half of which show negligible loss rates, while the remainder show significant local degradation of the local surficial aquifer.

2. The type of soil used in construction was found to be the major factor influencing seepage rates. Very sandy materials did not seal adequately, whereas fines (silt or clay) provided adequate containment.

3. The electromagnetic terrain conductivity survey method was shown to be a useful indicator of seepage, but cannot be interpreted reliably without auxiliary information about subsurface layering of sands and clays.

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Significance'

This work has been used by both producers and legislatures to help guide the recent development of the animal production industry in NC. The importance of having appropriate materials lining lagoons has been clearly demonstrated. State regulations now require adherence to the NRCS standards, which have been shown to be both necessary and adequate for protection of ground water.

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Future Plans:

1. Develop direct methods for assessment of seepage rates.

2. Develop ability to directly measure ground water discharge rates into still or flowing waters and capture samples for chemical analysis.

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Published by: North Carolina Cooperative Extension Service

Publication Number:

Last Electronic Revision: JULY 1996 (MSD)

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