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CITY of ORONO Municipal Offices Street Address: Mailing.Address: ' EggOg' 2750 Kelley Parkway P.O. Box 66 Orono, MN 55356 Crystal Bay, MN 55323.0066 June 29, 1998 Mr. &Mrs. Arne 125 Truffula Trail Long Lake, MN 55356 Dear Mr. &Mrs. Arne: A report from S-P Testing, Inc. was submited to the City in early June. The report is an evaluation of the function and the construction of the existing mound system. In summary, the report states that the septic system may have problems in the future because the tanks may be taking on ground water, the drainfield sand is saturated, and the mound does not have sufficient sand on the downslope side. Mr. Schirmers indicates that although the septic system is not discharging to the surface, ponding effluent was found in the downslope absorption area. Ponding effluent can and will occur in the downslope dike in a functioning drainfield. The drainfield could discharge to the surface if the drainfield has excessive ponding. Currently the drainfield is saturated, but not discharging to the surface. This condition does occur on newer septic systems and may dry up once the ground has stopped settling. In the S-P Testing, Inc. report, they found 14 feet of clean sand downslope of the rock bed on the south end and middle, but only 12 feet of sand on the north end. The required absorption width for this mound is 17 feet. On our inspection the south and middle of the downslope dike width was 16 feet and the north end was 13 feet, but rock was encountered for 13 feet wide instead of 10 feet at the north end. Some extra rock was probably pushed beyond the downslope edge of the rock bed which makes it appear that the sand area is too small. If the rock bed width is actually 10 feet wide on both ends as is likely the case,then the sand width is 16 feet. Ultimately the downslope absorption width is 1 to 4 feet short of what was designed. The S-P Testing, Inc. report also indicates that the septic tanks "show evidence of ground water seepage at the riser". As stated in previous letters from the City, the tanks have leaked significantly in the past between the septic tank and the manhole riser. The regrading of the backyard was completed to redirect the drainage away from both the drainfield and the septic tanks. The septic tanks did not leak during our inspection, but the tanks were wet at the manhole/tank seam and Telephone (612) 473-7357 • FAX 473-0510