02-27-1978 Planning Packet - Laserfiche WebLink

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MINUTES OF A PLANNING COMMISSION MEETING HELD NOVEMBER 21, 1977 - PAGE 3 COLPEPPER LAND COMPANY (Continued) (#306) DundaS-CPu) and Mlnnetopka Pit) - The maximum height of the seasonal water table in this soil as indicated by the presence of mottles is usually between 1 and 3 feet. If_jnpttling occurs at less than a 2 foot depth. Installation of absorption system is not recommended. These soils are shown as a blue cross-hatch on the enclosed soil map. grin (En), - Has a high clay content in the subsoil, ^^hich often results in percolation rates in excess of 60 minutes per inch. For this reason, it is recommended that an innovative mound system be installed on these soils. Mound systems cannot be installed on slopes ereater than 6 percent. The Erin soils with slopes from 6% to 12Z are shown on the enclosed soil map as a red cross-hatch. The Brin soils with slopes from 127. to 18% and from 18% to 35% are shown as solid red. Based on the Hennepin County preliminary soils report, there are major areas of the proposed plat where no type of soil absorption system is recommended and major areas of the plat where there would be serious difficulty with soil absorption systems due to water table, soil type and slope. A plan has been prepared for the proposed plat outlining the major steep slopes. Normal residential development can generally be accomplished on slopes up to a^roximately 12% without extra ordinary problems. From 12% slope up to about 18% slopes, very special design considerations must be incorporated into the development to prevent serious erosion problems. No development is recommended on slopes greater than 18%. 1-Ihen both the adverse soils and the steep slopes are overlaid on the proposed plat, there appear to be very few areas left for :uitable residential building and septic tank/drainfield placement. It is recommended that the proposed plat not be approved until the City of Orono can be assured that an adequate and acceptable individual sewer system can be provided for each lot to be platted. It must be understood that the Hennepin County soils report is a preliminary evaluation, but the report suggests that the magnitude of soil problems rela tive to ground absorption systems is serious enough to required additional in formation prior to any further consideration. The external boundary restraints on the proposed plat will allow access only from Orono via Orchard Road. The two narrow bridges on Orono Orchard Road at either end of the plat and the restricted sight distance suggest only one entrance as Indicated on the plat. The street alignment does traverse some very steep, wooded slopes throughout the plat and does intrude several exist ing marsh areas. The steepest slopes go through the middle of a number of proposed lets rather than along the edge, making placement of buildings more difficult. The terrain is very difficult to deal with from a development standpoint. However, it is suggested that alternate layouts be developed that may be more sensitive to the prominent topographical features of the land.