Sediment control practices for surface tile inlets

The effectiveness of slotted standpipes, slot-free standpipes, and grass buffers to remove sediment from flow through surface tile inlets, as well as impact of no-till farming, was investigated for two sites in Minnesota. Process-based simulation models were used to evaluate the impact of alternative designs and farming practices. Assessments were based on ensemble statistics from 400 years of runoff and sediment events. Comparisons among different practices were made relative to conventional tillage with a flush pipe inlet. For both sites, the most effective option for reducing the sediment loads was to change from conventional tillage to no-till farming. Mean effluent loads from this practice were approximately one-quarter of those loads obtained from conventional tillage. Slotted pipes were the most cost-effective practice to control sediment at the inlet itself. Median effluent sediment loads from these standpipes were approximately one-half of those loads obtained from flush pipes, and they had smaller flooded areas than obtained using slot-free standpipes. The usefulness of grass buffers was limited by ponded conditions for large events.