Publication Summary

The potential effects of the Sunland land application facility on ground water quality were evaluated. The evaluation was based on the facility's records and a consultant's hydrogeologic report, as well as a site inspection and effluent sampling.

The potential effects of the Sunland land application facility on ground water quality were evaluated. The evaluation was based on the facility's records and a consultant's hydrogeologic report, as well as a site inspection and effluent sampling.

The potential for ground water contamination at the spray field is high for the following reasons: (1) The spray field overlies a shallow water table aquifer; (2) The effluent application rate far exceeds recommended fertilization rates; (3) Sixty percent of the effluent is applied during the non-growing (dormant) season when plant uptake of nitrogen is low; and (4) Nitrogen removal from the field does not occur, because the grass crop is mowed and left to decompose in the summer.

As currently operated, the estimated nitrate contributions from the land application site could elevate downgradient nitrate-N concentrations by 11 to 15 mg/L. Pulses of higher concentration may also occur due to application scheduling.

The existing ground water monitoring network is inadequate. The ground water flow direction cannot be determined with the current well network. The upgradient and downgradient monitoring wells are in different water-bearing zones and are therefore not comparable. Wells do not meet current construction standards. Existing ground water data are of limited value for three reasons: 1) lack of an upgradient well; 2) poor well seals; and 3) lack of quality assurance sampling.