Agenda - Council - 09/14/2021 - Laserfiche WebLink

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Trott Brook Crossing EAW August 2021 on these features. Identify any project designs or mitigation measures to address effects to geologic features. The Geologic Atlas of Anoka County, Minnesota (Minnesota Geological Survey 2013) indicates the surficial geology of the area is characterized by the following three units: Richfield terrace - Sand and gravelly sand about 50 to 70 feet (15 to 21 meters) above the modern floodplain, ranging in elevation from about 870 feet (265 meters) in southern Fridley to about 915 feet (279 meters) in western Ramsey. Peat and muck - Partially decomposed plant matter deposited in swamps, commonly formed in ice - block melt -out depressions and in former meltwater channels. Generally mapped only where greater than 4 feet (1.2 meters) thick. Includes fine-grained organic matter laid down in ponded water, marl at depth in places, and small bodies of open water. Sand and clay facies -Generally thinly bedded, clay to sandy silt; silt predominates over clay in most places. Deposited in ice -block melt -out depressions by slack water of the Mississippi River at the Richfield terrace level. In places may include exhumed silt and clay of the New Brighton Formation (unit Qbc). The estimated depth to bedrock in the project area, based on the Geologic Atlas, generally ranges between 51 and 350 feet. Sinkholes and karst lands are not known to occur in western Anoka County where the project is located. Minnesota Karst Lands and Sinkhole Mapping prepared by Calvin Alexander and others (2006) does not shows karst lands or sinkholes in or near the project area. The site geology is not anticipated to be problematic. b. Soils and topography - Describe the soils on the site, giving NRCS (SCS) classifications and descriptions, including limitations of soils. Describe topography, any special site conditions relating to erosion potential, soil stability or other soils limitations, such as steep slopes, highly permeable soils. Provide estimated volume and acreage of soil excavation and/or grading. Discuss impacts from project activities (distinguish between construction and operational activities) related to soils and topography. Identify measures during and after project construction to address soil limitations including stabilization, soil corrections or other measures. Erosion/sedimentation control related to storrnwater runoff should be addressed in response to Item 11. b. ii. The Web Soil Survey indicates the project area includes fifteen soil mapping units that consist of mostly loamy sands (Table 4 and Figure 7). 8