Laserfiche WebLink
Stantec <br /> CITY OF CENTERVILLE -2018 LOCAL WATER PLAN <br /> PHYSICAL ENVIRONMENT <br /> HYDROLOGIC SOIL GROUP A - Low runoff potential, high infiltration rate <br /> HYDROLOGIC SOIL GROUP B - Moderate infiltration rate <br /> HYDROLOGIC SOIL GROUP C - Slow infiltration rate <br /> HYDROLOGIC SOIL GROUP D - Very slow infiltration rate, high runoff potential <br /> The runoff potential of an area is determined using these general soil characteristics in <br /> combination with land use classification, vegetation of the area, and rainfall intensities as <br /> determined from various design storms. As illustrated in Figure 3, the City contains a wide <br /> geographic variability of hydrologic soil groups, with most the City being in the B and C <br /> categories. <br /> 3.4 CLIMATE <br /> Centerville has a climate that is fairly uniform. Summers are warm, with a mean temperature of <br /> 70.7degrees in June, July, and August. Winters are cold, having a mean December, January, <br /> and February temperature of 16.8 degrees. About 70% of the precipitation occurs in the period <br /> of April through September. The yearly precipitation total is 27.9 inches. <br /> Climate data for the Twin Cities are published by the National Weather Service (NWS) station at <br /> Chanhassen, MN. The NWS is a branch of the National Oceanic and Atmospheric <br /> Administration (NOAA). Table 3.2 provides a summary of average precipitation data for the Twin <br /> Cities. <br /> TABLE 3.2-AVERAGE MONTHLY PRECIPITATION, 1971-2016 <br /> .................. <br /> inches 0.89 0.84 1.79 2.67 13.46 4.52 13.85 4.15 12.79 2.24 11.71 1.12 30.03 <br /> Rainfall frequency estimates are used as design tools in water resource projects. Rainfall <br /> frequencies are summarized in the National Oceanographic and Atmospheric Administration's <br /> (NOAA) Atlas 14-Point Precipitation Frequency Estimates. Previously, Technical Paper No. 40 <br /> (TP-40) Rainfall Frequency Atlas of the United States (NOAA) (published in 1961) was used to <br /> determine rainfall frequency estimates. TP-40 was developed using available rainfall information <br /> from far fewer stations than exist today; in Minnesota, there are 110 daily observation stations <br /> used in TP-40 estimates, whereas there are 320 daily observation stations used in Atlas 14. In <br /> addition to the fact that Atlas 14 estimates rely on a denser data network than TP-40, the <br /> stations have a longer period of record, and regional frequency analyses and new spatial <br /> interpolation techniques are used in the Atlas 14 method. Table 3.3 lists rainfall frequencies <br /> from Atlas 14 estimates, for the Twin Cities area, applicable to the City of Centerville. The data <br /> 3.6 <br /> 44 <br />