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, � ' PxoNE: 763-633- F�: 763-633- Miller Environmental Inc. 11040 183rd Circle N.W.,Suite AA•Elk River,MN 5 May 23, 2007 Peter Thiss 34 Water Street; Suite 200 Excelsior, MN 55331 Subject: Onsite Wastewater System (OWS) Design Le�al Description - 270 Big Island; Lake Minnetonka; City of Orono; Hennepin County Site Conditions - The property is located on an island of Lake Minnetonka. From the lake the property slopes up an 8% - 12% incline with mature maple and oak trees to a plateau where the residence is located. Soil Conditions — The Hennepin County soil survey mapped the area as the Lester Series. The Lester Series is the Minnesota state soil and is very common in Des Moines Lobe glacial till deposits of central Minnesota, specifically Wright and Hennepin Counties. A copy of the description for the Lester Series is included in Appendix A. The soil survey indicates the soils in the Lester Series are very deep, well drained loamy soils formed in glacial till. Six soil borings were completed in the area of the proposed and alternate drain field areas, see Figure 1. The soil borings closely matched the soil survey description of the Lester Series in the proposed drain field areas. The site was initially investigated in May 2003 with then City of Orono Septic Inspector Matt Bolterman. It was determined during the completion of the initial soil borings that there existed high chroma mottles in the soil profiles. The presence of these features was somewhat confusing because of the landscape position and the elevation above the lake elevation. It was agreed to by the owner, Mr. Bolterman, and MEI to install piezometers and a monitoring well to determine if the mottles (redoximorphic feature� were the result of an active fluctuating water table or are relict features. .: ,.� . ��:.�,y.'"§ The�eb`at�'over~activ�e versus relict redoximorphic features in higher landscape positions in the Des "��fYi�'�"�:obe �ili'�c�f western and south central Minnesota has continued for several years. The "tTriiversify of Minnesota h�s instal�ed.piezometers and monitoring wells on some sites to try and draw some conclusions on this debate. The USDA Natural Resource Conservation Service in their � description for Lester soils (attached) indicates these redoximorphic features are relict. Our own personal experience in these soils, including the monitoring for the past four years on the subject site and other similar sites, indicates that the presence of these features and their classification as active or relict is dependent on several factors however predominantly by landscape position. When 1