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Home My WebLink About1976-08-16 Septic System Design ReportAn Expansion of Soil Engineering Services, Inc. MINNEA►OUS/ST. ►AUL M S. Cewny Ad.1S. P.D. An 38105. Mph- Mo. $5425 / 112-141.5600 NORTHERN MINNESOTA 7219 E. IN Aveew, MiNiq. Me. 55746 / 210-263-88E1 August 16, 1976 Johnson & Peterson, Inc. 18104 Minnetonka Blvd. Wayzata, MIX 55391 Attn: Mr. Terry Johnson Mr. Johnson: E117JUT00- ENGINEERING TESTING 1 L MMN P.1. Aiw4w r. aw A1e1a. On AM Q L KAIAI P.1. Vin Aft fowmw y & a 119WIY V. 1. vb Am rwl.y 19OR/NG Z-0jr- / AL. Z- F-A-A-VIE-ZAJ Re: 76-301. PRELIMINARY SOIL BORINGS $ PERCOLATION TESTS Fairview (County Road 84) Orono, Minnesota As requested, we have recently conducted a preliminary soils investigation consisting of 8 power auger borings and 6 percolation tests. The borings were taken to determine the general soil and water conditions over the above referenced subdivision. The percolation tests were conducted to provide preliminary information relative to the soil absorptivity rates. The borings and percolation tests were taken at the locations shown on the attached sketch. Field locations were determined by topographical features shown on the topographical survey provided by you. Surface elevations were interpolated from the contour elevations shown on this survey. Investigation Methods: The power auger borings were completed using a 04E-45 truck - mounted power auger unit. The soil classifications and depths as shown on the attached Logs were inferred from the soils brought to the surface by the continous flight feature of the auger. The depth of strata changes is thus considered approximate. Pf1M�111 TIMI: r%ormiitA!/4tnll[ •wn waTi N1111' 76-301 Johnson 6 Peterson, Inc. -2- August 16, 1976 Mineral soils encountered in the borings were classified in accordance with the Unified Soils Classification System. A copy of that chart is attached. Representative samples of the soils brought to the surface by the auger will be retained in this office for a period of 60 days to be available for examination. Percolation tests were run in 6-inch diameter holes, drilled to a depth of 36 inches, in accordance: with the procedures normally used on lots that will be developed residentially. In accordance with standard procedures, the holes were permitted to soak overnight before conducting the tests. Each of the borings was probed immediately after completion to check for the presence of groundwater. Results: The Log of Soils encountered in the borings and the water level observations are shown on the attached Log of Boring - sheets. Boring B-1 encountered brown, silty sand overlying slightly silty sands to the respective termination depth of 18h feet. Borings B-3 and B-4 typically encountered a sandy clay to a clayey sand overlying a stratum of slightly silty sand to silty sand at or near the termination depth of the borings. $Arinag $-2 and�B-S through B-8 all encountered a dark brown to black silty sand to depths on the order of 2 to 6 inches and then encountered strata of verying thickness and depths of sandy clay and silty clayey sand glacial till termination depth of each of these borings. black sandy depth o o:ing 8-7. water was not encountered in borings B-S and B-6. a er was in B-2 and B-4, 12'f feet in B-3, 9h feet in B-7 and 17h feet in B- 8. A fairly large swampy area and Lake Minnetonka are :ocated at the southwest edge of the property. The contour elevation of the edge of this swamp to be r6ughly 9301. It then appears from this information that the groundwater table over the area under investigation would be above elevation 930. In boring B-1, water was encountered at an elevation of 94S. In boring B-4, water was encountered at elevation 934.5. There i-s considerable variation between these water level readings. Because of the cohesive nature Of the soils encountered, considerable time is required it order for the groundwater to stablize in the borings. It 76- 301 Johnson & Peterson, Inc. -3- August 16, 1976 does not appear that the groundwater levels were completely stabilized atthe time the water level checks were made. Also, some of these are possibly "perched" water levels. Water levels should be expected to show normal seasonal and annual fluctuations. Percolation tests indicated soil absorptivities, in minutes per inch (mpi) as follows: Surface Soil At Test 4 Elevation Test Depth Rate (mpi) P-1 9S6.0± Silty Sand (SM) S P-2 955.01 Clayey Sand (SC) 240 P-3 953.01 Sandy Clay (CL) 120 P-4 9S3.0± Clayey Sand (SC) 240 P-S 978.0± Clayey Sand (SC) 48 P-6 943.S± Sandy Clay (CL) 240 Preliminary Recommendations: You have indicated that current plans call for developing this site as a single family, residential area. Lot sizes currently planned are on the order of 2 acres with each dwelling having an individual sanitary disposal system. Borings were taken generally in the low areas across the site and provide preliminary information relative to the general soil types encountered in this area. The borings did not encounter any highly organic soils such as peat or muck, how- ever, a black mineral soil was encountered to a depth of 3 feet in boring B-7 which was put down in a low area near the southeast corner of the site. Power auger borings do not provide information relative to the strength parameters of the various soil types encountered, however, mineral soils of the types brought to the surface by the auger generally are of sufficient strength to support single family dwellings without detrimental settlement. Black mineral soils are likely quite soft and would not provide an adequate foundation. For any houses in low areas soft black soils will likely have to be removed in their entirety from building areas. There is considerable variation in the results of percola- tion tests conducted. Percolation test I1, which was conducted in a more sandy material, was found to have a percolation rate Of S mlli, which indicate that the soil in this area can absorb water relatively quickly. Results of percolation test P-S put down in a more cohesive soil, indicates that these soils are less permeable with a rate of 48 mpi. however, - ercolation rate of this magnitude would be considered accel. able. 76-301 Johnson & Peterson, Inc. �4- August 16, 1976 Percolation tests P-2, 3, 4, and 6 indicate individual absorptivities of 120 or 240 mpi. These values are outside the limits for typical individual sanitary sewer systems. Unless additional investigations would reveal more absorptive soils in other areas of these lots, specifically designed systems would be necessary to meet individual requirments and provide a system to function satisfactorily. Of necessity, the area of the power auger borings and percolation tests in relation to the area of the subdivi- sion and the depth of the borings are limited. Suggestions and/or recommendations of this report are opinions based on the data obtained from the borings. If we can be of further assistance in evaluating these data, taking additional borings or percolation tests, kindly contact us at your convenience. DMR/,;SB: skf Very truly yours, H ENGINEERING TESTING, INC. is M. Riet chel Bngineerin�g Assistant 0 ot% .%S. Braun, P.E. resident IMMOOR swf�wcce� te..wlt 0 k c.n I _ COlJNTY Rom �'� LOG OF 'B O-R I N G S PROJECT: 76-30. Preliminary Soil Borings DATE: 8/5/76 Fairview (Co. Rd. 84) SCALE: Orono, Minnesota BORING: g-5 LOCATION: 150'E, 100' S. of N.W. corner Lot 3 B RING: B-6 L TION:110'W, 110 S. f N.E. corner Lot SURF. EV• �978.0 Block 2. Block 2. Depth Description of Moterials 0 ' 7 WL D!!pth Description o Moterials OU Wi SANDY CLAY, fine to medium SANDY CLAY, black, moist. grained, brown, moist. CL (Topsoil) C. (Till) 3 SANDY,fine—t—o-w-Mun- grained, grayish brown. Cl. moist. (Till) 12 . SILTY CLAYEY SAND, fine to medium -grained, brown, moist. SM-S 15 (Till) SILTY CIATBY SAND, with a SH-S trace of gravel, brown, moist. . 18.5 (Till) 18.5 Water level not encountere 1=sdiately after withdraw 1 Water level not encounters of au:;-r. im ediately after withdraw 1 of auger.