The addition of manure to an earthen storage further reduces seepage rates due to physical, chemical, and biological processes that contribute to the clogging of soil pores. Poorly designed and constructed liners as well as badly eroded liners can allow significant movement of contaminants into the soil below the storage structure. If they are to continue in use, they must either be fixed, or they must be closed. Soil borings may be necessary to accurately assess movement of nutrients below improperly sited, poorly constructed, or inadequately maintained liners. The contaminant from an abandoned earthen storage most likely to impact ground water is nitrogen, because it is relatively mobile in soil.
Soils provide excellent filtering media for pathogens.
Phosphorus chemically binds to soil to form a variety of non-soluble complexes. Phosphorus and pathogens should seldom be a concern to ground water contamination from an abandoned storage unless the water table is within 18 inches of the bottom of the facility. Estimating Condition of Storage Research from the University of Nebraska shows that the most likely area for seepage is at the junction of the sidewalls and the bottom of the storage. Therefore, if there is doubt about the storage, its condition can be estimated by pumping out as much liquid and sludge as possible and taking 5-foot deep core samples around the sides of the bottom. A hand auger should be used to avoid the risk of damage to the liner with a soil-drilling rig.