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� � � • t TOM SMITH ASSOCIATES inc Consulting Engineers October 19� 1983 Joe Backes 3It16 Jidana Iane Minnetonka� r�r 55343 SUBJECT: Evaluation for onsite sewage treatment system, Lots 3i & 32, Morse Island Park, Orano, Minnesota Job # 1980 Per your request we have condlzcted a site evalUation at the subject location. This report presents our finding�, recommendations, and design specifications for the sewage treatment for this site. EVALUATION: The site is on Bi� Island in Lake Minnetonka and falls within �the municipality of Orono. Zhe site is approximately 100 feet wide on the lakeshore dimension and almost 21�0 feet deep. Access is f'rom the lalse front where the site rises approximately �3 feet at the 75 foot setback from the lake� and then levels and slopes back slightJ,y away from the lake in the back areas. Three soil borings were put down to identify the subsurface profile, copies of the field logs of which ar�e attached hereto. The soils encount,ered are basically cla*yey silts and silty clays to the depth of the borings, a depth of 52 feet below grade. Surface elevations of the borings vary by about 22 feet� and they are about 20 feet higher t11an the level of the lake. No ground water or mottling was encountered to the depth of these borings� indicating seasonally high ground water levels can be expected below the depth to which the borings were taken. A total of �t percolation tests were conducted in the potential drainfield area. �e borings were put down on �e�tember 27th, and the percolation test holes were prepared and soaked also on September 27th. The depth of the bottom of the percolation test holes was from 19 to 22 inches below grade. Six inch holes were augered with a hand auger, the sides were scratched with. a large spi.ke, the loose material was removed from the bottom of the hole, and 2 inches of pea gravel was placed in the bottom of the holes, A minimum of 13 inches of water was maintained in the holes for at least four hours soaki.ng, maintained by automatic siphon. The holes were left to stand overnight and the percolation tests were performed the next day, September 28th. The percolation tests were run accordin� to 1�1PCA and City of Orono Standards. Results were 17.9� 1303� 2�t� and 10.4 minutes per inch in holes 1 through 1t respectively. Copies of the field percolation test data sheets are attached. Also attached is a site evaluation location sketch indicating the location of the borin gs and the percolation testso 5109 Kimberly Road, Minnetonka, Minnesota 55343 (612) 934-8031