Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 3/15/2000
Publication Date: N/A
Citation: Interpretive Summary: Public attention has been focused on nutrient pollution of groundwater. As a result, feedlots have come under increased scrutiny. Research has shown that storage pond bottoms are well sealed, however, sidewall seepage has been a problem. This seepage comes from cracks formed during the wetting and drying cycles of filling and pumping. Root channels also help seepage. Objectives were to construct and evaluate a runoff control system that eliminated long-term storage. Amount of feedlot runoff and nutrient discharge were estimated with a computer model. A terrace was built to collect runoff, provide temporary liquid storage and accumulate solids, while distributing the liquid across a grass field. The grass field utilizes runoff water and nutrients to minimize pollution. Initial findings show large reductions in solids in the runoff released to the grassed field. Water volume held in the basin was greatly reduced compared to traditional storage systems. No runoff flowed from the grassed field during the 1999 season.
Technical Abstract: Research has shown nutrients from feedlot runoff can infiltrate beneath long-term storage ponds. Pond embankments' wetting and drying cycles and weed growth form channels that facilitate preferential flow paths. The project objectives were to construct and evaluate a simplified runoff control system that reduced or eliminated long-term storage. Runoff volumes, nutrient totals and peak discharge were estimated using the Nutrient Fate Model for Beef Cattle Feedlots. A dispersion field was sized based on these values. A flat-bottom terrace was constructed to collect runoff, provide temporary liquid storage and accumulate settable solids, while distributing the nutrient laden liquid fraction uniformly across this dispersion field. Preliminary findings indicate substantial total suspended solids (TSS), volatile suspended solids (VSS) and chemical oxygen demand (COD) reduction as the water moved through the treatment system. The nitrogen to phosphorus ratio of the basin solids removed during the 1999 season was approximately 2.7:1. This would indicate the solids could make an excellent plant fertilizer. No dispersion field runoff water was recorded during the 1999 season, indicating that the basin discharge was effectively utilized for grass production. The volume of water remaining in the basin available for deep infiltration was greatly reduced when compared to traditional long-term runoff storage systems. This was evident as the simplified runoff system began to accumulate solids, thereby reducing the total liquid storage volume of the basin.