 | |  | | Indoor Streamlab looking upstream |
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Updated May 27, 2008.
Facility Overview
The Indoor StreamLab (ISL) is an ongoing project being conducted in the Main Channel at the St. Anthony Falls Laboratory (SAFL).
SAFL (Univeristy of Minnesota) is located on the Mississippi River adjacent to the St. Anthony Falls in Minneapolis. The building was constructed in 1938 as a hydraulics lab by the Works Progress Administration, and has transformed itself into an internationally recognized, multidisciplinary teaching and research facility. Over the last 60 years researchers at SAFL have made significant contributions to the fields of hydraulics, environmental engineering, fluid mechanics, and geomorphology and sedimentology.
Main Channel
The Main Channel (see schematic) is 9 ft wide and 6 ft deep. It has a total length of 275 ft. The auger pit is the full width of the channel (108 inches) and is located about 200 ft from the upstream end of the channel. At the downstream end of the channel is a mechanical wall that can be used as a weir or sluice.
Water Intake Structure
We take water into our building from upstream of the Falls through an intake structure with bar trash racks and a set of traveling screens. Discharge is controlled at the intake by adjusting the opening of a large mechanical gate. Once the water passes through the screens it falls to the main channel level and is routed into the channel. Measurement of discharge is made in a volumetric tank at the downstream end of the channel.
Auger Pit & Sediment Recirculation
The auger pit is a large 108"x40" opening in the channel. At the bottom of this pit is a steel auger that is used to convey sediment out of the pit toward the recirculation pump. The motor driving the auger is variable speed so can be adjusted to match the rate of material accumulating in the pit. Once out of the pit, the rock is drawn into a large vortex pump that moves the material upstream. The rock is conveyed in an 8" steel pipe with river water. The system was designed to handle 2.5" rock.
Volumetric Tanks
Once the water is discharged over the end weir it flows outdoors and into a pair of large volumetric tanks. The tanks are used to measure volume and are used in tandem. By recording the fill time of a tank and calculating the captured volume we are able to determine the flow rate in the channel.
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