SEDIMENT CONTROL PRACTICES FOR SURFACE TILE INLETS

Abstract

The effectiveness of slotted standpipes, slotfree standpipes, and grass buffers to remove sediment from flowthrough surface tile inlets, as well as impact of notill farming, was investigated for two sites in Minnesota. Processbasedsimulation models were used to evaluate the impact of alternative designs and farming practices. Assessments were basedon ensemble statistics from 400 years of runoff and sediment events. Comparisons among different practices were maderelative to conventional tillage with a flush pipe inlet. For both sites, the most effective option for reducing the sediment loadswas to change from conventional tillage to notill farming. Mean effluent loads from this practice were approximatelyonequarter of those loads obtained from conventional tillage. Slotted pipes were the most costeffective practice to controlsediment at the inlet itself. Median effluent sediment loads from these standpipes were approximately onehalf of those loadsobtained from flush pipes, and they had smaller flooded areas than obtained using slotfree standpipes. The usefulness of grassbuffers was limited by ponded conditions for large events.