Infiltration rates observed in Minnesota

Infiltration rates observed in Minnesota.
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Source of data	Range of infiltration rates (in/hr)	Number of monitoring sites	Brief description of site	Year construction	Monitoring dates
South Washington Watershed District	0.02 to 3.021	1	Infiltration trench located in regional basin CD-P85. These trenches are an average of 13 feet deep. Underlying material is sand and gravelly sand.	2004	1999 to 2005
Rice Creek Watershed District	0.03 to 0.59	4	Monitoring data collected at 3 rain gardens and an infiltration island located at Hugo City Hall. Soils in the basin consist of silty fine sand with a shallow depth to the water table. Trench receives significant pretreatment of stormwater prior to infiltration.	2002	2002 to 2003
Brown's Creek Watershed District	0.01 to 0.20	2	Monitoring data collected at 2 infiltration basins. Soils in the basins consist of silty sand and silt clay interspersed with clayey sandy silt.		2000 to 2005
Field's of St. Croix, Lake Elmo, MN.	0.02 to 0.14	3	Monitoring data collected at 3 infiltration basins located in a residential development. Soils in the basins consist of sandy loam and silt loam (HSG B).		2001 to 2003
Bradshaw Development, Stillwater, MN	0.26 to 0.28	1	Monitoring data collected in 1 infiltration basin located in a commercial develolment. Soils in the basin consist of a silty sand.	2005	2005
Gortner Ave. Rain Water Gardens, University of Minnesota, tested by St. Anthony Falls Laboratory, Water, Air, Soil Pollution, 2013: Assessment of the Hydraulic and Toxic Metal Capacities of Bioretention Cells After 2 to 8 Years of Service	0.104 to 5.76	1	Assessment of 40 locations within one bioretention basin. Testing was conducted 2 years after installation. The Raingarden receives runoff from adjunct grassed areas and a street. The underlying soils consist of sandy loam and silt loam over sand.	2004	2006 and 2010
St. Anthony Falls Laboratory, Minnesota Local Road Research Board, Minnesota Department of Transportation	0.29 to 1.55	5	Five highway ditches studied, with up to 20 measurements taken at each highway ditch segment, for a total of 96 measurements.		2011-2012
JAWA, 2009: Performance Assessment of Rain Gardens	1.29	1	Stillwater Infiltration Basin, 65 measurements		2012
JAWA, 2009: Performance Assessment of Rain Gardens Water, Air, Soil Pollution, 2013: Assessment of the Hydraulic and Toxic Metal Capacities of Bioretention Cells After 2 to 8 Years of Service	2.66	1	Burnsville Rain Garden is 28 square meters and was constructed in 2003 in a residential neighborhood. Underlying soils are sandy loam over sand. In 2006, 23 infiltration measurements were taken in a single rain garden in the third year of operation.	2003	2006
JAWA, 2009: Performance Assessment of Rain Gardens Water, Air, Soil Pollution, 2013: Assessment of the Hydraulic and Toxic Metal Capacities of Bioretention Cells After 2 to 8 Years of Service	6.30	1	Cottage Grove Rain Garden is 70 square meters in area, constructed in 2002 to receive runoff from a parking lot. Underlying soils are sands and gravels. In 2006 in the fourth year of operation, 20 measurements were taken in the single rain garden.	2002	2006
JAWA, 2009: Performance Assessment of Rain Gardens Water, Air, Soil Pollution, 2013: Assessment of the Hydraulic and Toxic Metal Capacities of Bioretention Cells After 2 to 8 Years of Service

¹The high end of this range (3.1 inches per hour) is not representative of typical rates for similar soil types. This facility is periodically subject to 25 foot depths of water, is underlain by more than 100 feet of pure sand and gravel without any confining beds and the depth to the water table is greater than 50 feet below the land surface. In addition, two infiltration enhancement projects have been constructed in the bottom of the facility to promote infiltration: five dry wells and two infiltration trenches have been operating in CD-P85 at various periods of the monitoring program.