WHIPPS RAVINE: A CONCEPTUALLY NEW APPROACH FOR SOLVING AN OLD PROBLEM

Whipps Ravine was identified as one of the largest sources of sediment being delivered to Sand Creek during a turbidity TMDL study. The ravine, located east of Highway 21 and south of Jordan, MN, was the focus of intensive data collection including: cross-sections, longitudinal profiles, pebble counts, particle size distributions and soil shear stress measurements. Ravines in the Minnesota River basin (MRB) have been identified as important sources of sediment contributing to excessive amounts of TSS in the Minnesota River. The results gathered from this effort were used in a ravine design charrette (EOR, 2011) to discuss options for managing sediment from ravines in the MRB. Upland water detention was identified as the most cost effective solution if possible. Another solution involved the use of Water & Sediment Control Basins (WASCOB’s) to be placed at the heads of actively cutting ravines. Lastly, instead of rip rap or moving large volumes of earth, we proposed the use of brush/tree cutting crews to selectively harvest woody material and selectively place woody debris in the ravine channel; and do this on an annual basis over the next decade. This approach provides light penetration for understory growth, use of available woody material to trap sediment and a relatively low implementation cost including the built-in maintenance.