11-21-1977 Planning Packet - Laserfiche WebLink

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:areous till, liar hills and le original veg- ?d in Hennepin relopment is dis- diian green. This lilltops. The T, sidehill seep ing wet seasons, t rolling slopes ,e) is low to mod- tely penr.eable. ed periods. diui!i green. Inis The soil is well eepage is not an :s. The rolling well (volune . The soil is left exposed for mned in calcareous ice. The native ’ one slope phase Page -o- > 1 -T ■ >: T-- ;!■ Light Green 5 1 VV 5 Dark Blue i' ri Nessel loam - 1 to 4 percent slope: The map symbol for this soil is .N’eB and the map color is light green. This soil is nearly level to gently sloping occupying areas of low relief and on a few hilltops that are above Hayden soil on the side slopes. Since this soil is nearly level little grading is generally required. This soil is wet for short periods with a seasonal watertable at a 3 to 5 foot depth. Shrink-swell (volume change) is low to moderate with changes in moisture content. The soil is moderately pemeable. Soil strength is adequate for residential development. Marsh: The map s>'mbol for this soil is Ma and the map color is dark blue. The upper 5 to iO feet of the marsh is peaty muck or muck. This covers other layers formed in vdiat was formerly a glacial lalce. The watertable is near or above the surface the entire year. Tlicse soils liave very low bearing capacity. The development characteristics of these soils are generally unfavorable. These areas are best used for natural water stor age and as scenic open space areas of developments. rV. POTENTIAL OF SOILS FOR ON-SITE WLASTE TREABIENT According to the recommended "Ordinance and Code Regulating Individual Sewage Disposal Systems" published by the Minnesota Department of Health in 1971 "No soil absorption system shall be installed in an area where the watertable is at any time less than 6 1/2 feet below ground level or 4 feet below the bottom of the drain field trench". This line of thinking has changed somewhat over the past 6 years to re flect research results conducted in various areas of the county. The proposed Minnesota Pollution Control Agency ^^-40 "Individual Sewage Treatment Systems Standards" states only that "The bottom of trenches and beds shall be at least three feet above the watertable or bedrock" and allows for installation of additional innovative systems other than the standard subsurface trench system to meet this retiuirement. /\n ex'ample of the innovative systems is the mound system. In the mound system the seepage bed or trench is elevated by the use of sand fill to provide the 3 foot separation distance between the bottom of the seepage trench and a barrier laver such as the watertable or bedrock. In the prelininaiy "Reconnnended Practices for On-Site Sewage Treatment Systems" prepared by the City of Orono the 3 foot separation distance is implied A\hen the highest point of groiindwater must be greater than 5 feet for installation of a standard soil absoi*ption system. ■r-i lb