Browsing by Author "Barr, Kelton D"
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Item Dye Tracing Sewage Lagoon Discharge in a Sandstone Karst, Askov, Minnesota(Proceedings of the 10th Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of Karst. © 2005 American Society of Civil Engineers. Published online: April 26, 2012, 2005-09-28) Alexander Jr., E. Calvin; Alexander, Scott C; Piegat, James J; Barr, Kelton D; Nordberg, BradAn investigation of the sandstone karst at Askov, Pine County, Minnesota was conducted utilizing fluorescent dye tracing techniques. Connections were documented between the effluent from WWTF lagoons discharged into a sinking stream and local residential water supply wells southwest of the stream sink, over kilometer-scale distances. The apparent velocity of dye from the steam sink to the residential well was 57 m/day, much faster than would be expected for porous-media flow in a sandstone but slower than expected for well-developed conduit karst in carbonate rock. The traces also document stage-dependent, divergent flow to the northeast and west from recharge to a sinkhole adjacent to the lagoons. A well-developed conduit system extends a few hundred meters under the northern portion of the lagoons with flow velocities greater than 128 m/day to the northeast. A slower flow system extends for at least a kilometer to the west and northwest with a range of apparent flow velocities that average about 9 m/day. The slower flow system reached a broad “fan” of residential wells to the west but was not detected in other wells in the same direction.Item Dye Tracing to Camp Coldwater Spring, Minneapolis, MN(Minnesota Ground Water Association Newsletter Volume 20 Number 4: December 2001 Page 4 - 6. Additional results from Sophie Kasahara's Senior Thesis "A Hydrological Study of Coldwater Spring, Minneapolis, MN." - UM Geoengineering Department, 2016., 2017-06) Alexander Jr., E. Calvin; Alexander, Scott C; Barr, Kelton D; Kasahara, Sophie M; Wheeler, Betty JCamp Coldwater Spring is a ~6.3 liter/sec spring that emerges from a Platteville Limestone ledge at the top of the west side of the Mississippi River gorge. It was the original water supply for Ft. Snelling in the early-mid 1800’s and is a registered Minnesota State Landmark. Potential impacts from nearby highway construction led to two successful dye traces to help define the groundwater basin feeding the spring. These traces are the first traces through the Platteville in the Twin Cities. Dye input trenches were dug with a backhoe to the top of the water table. Input B reached the top of the Platteville and the water table was a few inches above the bedrock surface. Eosin dye input into the trench reached Camp Coldwater Spring, 125 meters away in less than 1.5 hours. The minimum flow velocity in the fractured Platteville Limestone was 83 m/hr. Input C reached the water table while still in glaciofluvial sediments and was 305 meters from the spring. Fluorescein dye from Input C reached the spring in 16 days. The slower flow velocity is a combination of flow through the glaciofluvial sediments and through the fractured Platteville Limestone. These two positive traces demonstrate that Inputs B and C are inside the ground-watershed that supplies the Spring and support concerns about the potential impact of dewatering and construction activities on the Spring. The trace is ongoing.