Laserfiche WebLink
SECTION 2 <br /> <br /> <br /> <br /> <br />Surface Water Management Plan Section 2: Land and Water Resource Inventory <br />City of Arden Hills <br />WSB Project No. 3455-200 Page 2 <br /> <br />previous Technical Paper 40 precipitation values. Selected rainfall frequencies for Arden Hills are <br />listed in Table 2-2. <br /> <br />Table 2-2 Atlas 14 Rainfall Frequencies <br />Recurrence <br />Interval (years) <br />24-hr Rainfall <br />Depth (in) <br />Chance of <br />Occurrence <br />Each Year <br />1 2.45 99% <br />2 2.82 50% <br />10 4.21 10% <br />50 6.27 2% <br />100 7.35 1% <br />100-year 10-day <br />Runoff 7.3 1% <br /> <br />Additional precipitation information for the area can be obtained from the NOAA website at <br />http://hdsc.nws.noaa.gov/. <br /> <br />2.1.3. Geology and Topography <br /> <br />Arden Hills is located in Ramsey County, which is dominated by the Eastern St. Croix Moraine. <br />This glacial and terminal moraine is characterized by steep hills interspersed with deep <br />depressions. The depressions are occupied by small lakes or are filled with peat. <br /> <br />The topography of the City is relatively diverse, with undulating to steep slopes. The highest point <br />in Ramsey County is in Arden Hills on the TCAAP property. The entire City is ultimately tributary <br />to Rice Creek. The specific drainage patterns, which depict topography for areas within the City, <br />are shown on the subwatershed delineation map (Figure 7). As can be observed from the <br />subwatershed delineation map, the City is divided into many small watersheds. <br /> <br />Detailed descriptions of the City’s bedrock geology can be obtained from the RCWD. In addition, <br />the Minnesota Geological Survey can provide maps detailing the bedrock hydrogeology of <br />Minnesota, addressing rock formations and aquifers. <br /> <br />2.1.4. Soils <br /> <br />Most of the soils within Arden Hills are glacial tills. The soils tend to be well drained and <br />moderately coarse textured. <br /> <br />The main source of information on existing soils found within the City of Arden Hills was prepared <br />by the Natural Resource Conservation Service (NRCS). The hydrologic soil classification map is <br />shown in Figure 2. The NRCS has established four general types of soil groups based on texture <br />and slope as described below: <br /> <br />Group A - These soils have high infiltration rates even when thoroughly wetted. The infiltration <br />rates generally range from 0.8 to 1.63 inches per hour. These soils consist chiefly of deep, well <br />drained to excessively drained sands and gravel. Group A soils have a high rate of water <br />transmission, therefore resulting in a low runoff potential. <br /> <br />Dr <br />a <br />f <br />t <br /> <br />11 <br />/ <br />2 <br />0 <br />/ <br />2 <br />0 <br />1 <br />7