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HomeMy WebLinkAbout1978-01-24 Septic System Design ReportAn Expansion of Soil Engineering Services, Inc 'O MINNEAPOLIS/ST. PAUL 6880 S. County Rd. 18, P.O. Box 35108, Mpls„ Mn. 55435 / 612 941 5600 ❑ NORTHERN MINNESOTA 3219 E. 19th Avenue, Hibbing, MN. 55746 / 218-263-8869 ❑ CENTRAL MINNESOTA 200 Osao Avenue No., St. Cloud, Mn. 56301 / 612 253 9940 January 24, 1978 David Nitz, Inc. 464 Second Street Excelsior, MN 55331 Attn: Mr. Scott Abernathy Gentlemen: Braun" ENGIKEEAING TESTING 1 S BRAUN P E Pfa,drnr P K ANDERSON, Vr Pn OpprPrwnr L G KR USE P. E.. Vrctr AK Enpn ng Re: 78-008A SOIL BORING & PERCOLATION 'TESTS Lot 10, Block 1 Farview Addition Orono, Minnesota As you requested, we have recently conducted one power auger boring and ten percolation tests taken to determine the general soil and water conditions, as well as to provide information relative to the soil absorptivity rates for an individual sanitary System being constructed at the above referenced lot. Boring and percolation tests were taken at the locations shown on the attached sketch. Field locations were determined Sy our crew with reference to the staked house location. Surface elevations were referenced to the top of an iron at the northeast property corner with an elevation at this point assumed equal to 100.0. Initially, six percolation tests were conducted on the lot on January 6, 1978. As some of the tests indicated failing results, four additional percolation tests were conducted on January 13, as you requested. INVESTIGATION METHODS: The power auger boring was completed using a truck -mounted power auger unit. The soil classifications and depths shown on the attached log were inferred from the soils brought to the surface by the continuous flight feature of the auger. The depth of s`rata changes are thus considered approximate. CONSULTING ENGINEERS/SOILS AND MATERIALS Test Borings • foundation Engineering and Recommendations a Inspection of Construction • Material Testing of Sods. Concrete and Budding Components ' 78-008A ' David Nitz, Inc. -2- January 24, 1978 Mineral soils encountered in the boring were classified in ' accordance with the Unified Soils Classification System (ASTM D2487). A copy of that chart is attached. Representa- tive samples were then returned to our laboratory for ' verification of the field classification by a Soils Engineer. Representative samples will remain in this office for a period of 60 days to be available for your examination. ' The boring was probed immediately after its completion to check for the presence of groundwater. The boring was also rechecked prior to leaving the site at the time the percola- tion tests were read the following day. Groundwater was not encountered in both probings of the boring to its 17-foot termination depth. H J II II u 11 The percolation tests were run in 6-inch diameter holes drilled to an approximate depth of 36 inches, in accordance with pr;,,.edures recommended by the Minnesota Department of Health (WID) and with procedures recommended by the City of Orono. In accordance with these procedures, the bottom and sides of the holes were scr.:tched with a knife blade to remove any smeared soil surfaces and to provide a natural soil interface into which the water may percolate. Two inches of coarse sand was then placed in the bottom of the holes to prevent scouring. The holes were then carefully filled with clear water to a minimum depth of 12 inches over the top of the sand layer and allowed to soak overnight with the percolation tests being conducted the following day. RESULTS: The log of soils encountered in the boring and the water level observations are shown on the attached Log of Boring sheet. The soil boring generally encountered a coarse alluvial silty sand from the surface to the 5-foot depth. A silty clayey sand to sandy clay glacial till was then encountered to the termination depth of the boring. Soils encountered in the percolation tests generally ranged from sandy silty sand to a sandy clay glacial till. Results of the six initial percolation tests indicating the soil absorptivities in minutes per inch (mpi) are as follows: Surface Soil At Rate Test # Elevation Test Depth (m i P-1 83.1 Silty Sand 48 P-2 78.8 Sandy Clay 120 P-3 75.9 Sandy Clay 120 P-4 75.5 Sandy Clay 80 P-5 76.3 Silty Clayey Sand P-6 78.8 Silty Clayey Sand ENGINEERING TESTING 78-008A David Nitz, Inc. -3- January 24, 1978 As indicated, percolation tests aP-1, P-5 and P-6 met the percolation requirements, while tests NP-2, P-3, and P-4 indicated values outside the limits for a typical individual ' sanitary sewer system. At that time, in our opinion, it appeared likely that a suitable drainfield site can be located on the site further to the west of the drainfield area site, that was initially investigated. As you requested, on January 13, four additional percolation tests, P-7 through I'-10, were performed, approximately 30 ' feet further west than the location of P-1 and P-6 and at slightly higher elevations than those areas tested previously. Readings of the additional tests were conducted on January 13 with the following results. Surface Soil At Rate Test # Elevation Test Depth (mpi) ' P-7 88.4 Clayey Sand 36 P-8 84.2 Clayey Sand 2"' P-9 80.9 Clayey Sand 45 P-10 84.6 Clayey Sand 60 The average four additional tests, along with the passing ' results of P-1 and P-6, is then 45 mpi. REMARKS: In our opinion, a suitable drainfield can be situated imme- diately to the south and west of the proposed house loca- tion, with the start of the drainfield at or near the loca- tion of percolation tests #P-9 and P-10 and extending in a southeastward manner, following the contours of the slope. The system designed for Lot 10, Block 1 was based on the results of percolation tests P-1 and P-6 through P-10, which indicated an average of 45 mpi. For this system, a total of 295 lineal ''eet of absorptive trench per bedroom would be required, therefore, the drainfield system consisting of 885 s[. 44a*a4 feet of absorptive trench w.- based on a 3-bedroom U home for this lot. In order to meet this requirement, six 30-inch wide absorptive trenches 60 feet in length with 7 foot center -to -center spacing should be adequate for this lot. It has been our pleasure to be of service to you on this project. If we can be of further assistance in evaluating the enclosed data, kindly contact us at your convenience. I The content of this rr RtA N DIg SoMents are for the exclusive use of the we make no representation n assume no responsibihir to any other parties regart Very truly yours, irAIZVIL-W LANE BM. nPOF'/wN NE Qkao CORNER X4aV , L07-10,640Ct'Ile L 90, P 7,�� LINE a - AxEA i = �WER' L�!/GiER �i2�n1 G LOICAr/ay.5 409LWo /A-Arjr PE'MOLA7-10,4 TfsT W049 --..N BRAUR- TING '9- M S911 le0eJnIZ7 ,� rZSram, L O7 - /O, LCCJ< / ,�ARYr� ►� ,q0P/T, O�eo n/o, /- 9- 78 R"sod: 15 own: pMR SoM: � z � LOG OF BORINGS •_- PROJECT: 78-008 Soil Borings 6 Percolation Tests DATE: 1/6/78 Lots 8 and 10, Block 1, Farview Addition Orono, Minnesota SCALE: 1"-4' BORING: B-1 LOCATION: Lot 10, BORING: LOCATION: U RF.ELEV• Block 1, See Attached UR , 77.2 Sketch ASTM Depth Descri Lion o Materials D2487 WL DepthDescription of Materials WL SILTY SAND, fine to medium -grained, with a SM trace of fine Gravel, dark brown to brown, moist. I (Coarse Alluvium) 12 17 SILTY CLAYEY SAND, fine to medium -grained, with a trace of fine to medium M-SC Gravel, brown, moist. (Glacial Till) SANDY CLAY, brown to grayish brown, moist to CL wet. (Glacial Till) , Water level not encountered 10 minutes after completion of boring. Water level not encountered 24 hours after completion of boring. Bench Mark - Top of iron at N.E property corner with elevation assumed - 100.0'. DESCRIPTIVE TERMINOLOGY PARTICLE SIZE IDENTIFICATION SOIL INTRUSIONS ' Bowdon over 3" THICKNESS RELATIVE PROPORTIONS Gravel lense 0 - 1 /8" with a few 0 - 10% Cos. 1" - 3 seam 118" - 1" with sane 11 - 20% ' Medium 1/2" - 1" loyer 1" - 12" with over 20% Fine No. 4 - 1/2" varved alternating soomss or Send lenses of clays and Coana No. 4 - No. 10 silts in lake deposit Modums No. 10 - No. 40 Fine No. 40 - No.100 MOISTURE CONTENT ORGANIC CONTENT Very Fine No. 100 - No. 200 Sllt No. 200 - =5 rnm Dry lass than 5% 0-5% non to slightly organic ' Cloy, less then A06 mm Moist under optimum moisture 6 - 10% slightly organic Nbt over optimum moisture 11 - 25% rpnic Waterbsering saturated send 26 - 65% muck 65+ past ' RELATIVE DENSITY OF CONSISTENCY OF PLASTICITY OF SOILS WITH COHESION LESS SOILS COHESIVE SOILS LESS THAN 20%CLAY ' very loose 0 - 4 BPF very soh 0 - 1 BPF non plastic gritty, cannot thread loose 5 - 10 BPC soft 2 - 3 BPF slightly plastic rough to smooth, medum dense 11 - 30 SPF rothw soft 4- 5 BPF hard to thread denea 31 - 60 6PF medium 6- 8 BPF plastic smooth to waxy. ' very dense 50+ OFF rethsr stiff 9 - 12 BPF easy to thread stiff 13 - 16 BPF very stiff 17 - 30 BPF hard 30+ BPF ' RELATIVE PROPORTIONS OF GRAVEL LABORATORY TESTS ' • tram 0 - 5% DID Dry Density, pcf OC Organic Content, % a little 6 - 15% WD Mt Density, pcf S Percent of Saturation, % some 16 - 30% MC Natural Moisture Content, % SG Specific Gravity and 31 - 50% LL Uquid Limit, % C Cohesion ' PL Plastic Limit, % 0 Angle of Internal Friction PI Plasticity Index, % qu Unconfined Compressive Strength ' DRILLING NOTES: Standard penetration test borings were advanced by 2K" or 3%- I.D. hollow -stem augers unless noted other wise. Jotting water vw used to claw out sugar prior to sampling only whate indicated on logs. Standard penetration test borings are designated by the prefix "ST" (Split Tube). Power sugar borings were advanced by 4" or 6" diameter, con tinuous-fhto. solid stem augers. So,l dessificauon Y' and strata dept.se are inferred from disturbed sornples sugared to the surface and are therefore somewhat approximoee. Power sugar borings are designated by the prefix "B". Hand probings wore advanced manually with a 1 %" diameter probe and an limited to the depth from which the probe can be manually withdrawn. Hand probings we indicated by the prefix "N". ' CLASSIFICATION: Classification on logs is me* by inspection in accordance with the Unified Solis Classification System two attached chart) using viwal-manual procedures unless noted otherwise. GROUND WATER: Observations were me& at the times indicated. Porosity of soil stets, seasonal weather conditions, site topography. etc., may cause changas in the water levels indicated on the logs. SAMPLING: All "I Miles are taken with the standard 2" O. D. split -tube sampler, except where noted. TW indicates thin - . well undisturbed samplle. BPF: Nunsbs. indicate blows par foot recorded in standard penetration test, also known as "N" value The ssmpier is set 6" into undisturbad soil below the hollow -stem ougw. Driving resistances we then counted for second and third 6" increments and added to got BPF. Where they differ significantly, they we reported in the following form - 2/12 for the second and third 6" increments respectively. WH: WN indketes that sensplet psretrated soil under, weight of hammer and rods alone, driving not required. NOTE: All tests run in accordance with applicable ASTM standards. 0mun ENCiNiEERING TESTING CLASSIFICATION OF SOILS FOR ENGINEERING PURPOSES ASTM DESIGNATION D-2487 Group Typical Major Divisions Symbols Names Classification Criteria VWab, ^ c ,'_ �' 4- � N C U L t0 N u GT z q W o CM v 4A CC ipt �I N elf ` f SP to lam. WZ N SM qCq O 'Aa i A S�� Sc N M 1n *v o v� :3 " v2 J N Hell -graded gravels and Cu - Ddo � D10 Greater than 4 c gravel -sand mixtures, little or no fines �D 1B 0s -� Between 1 and 3 _ 10 d0 Poorly graded gravels and gravel -sand mixtures, Not meeting both criteria for OW tittle or no fines N " Silttyy ggravels, gravel- ilVsilt Atterberg limits plot below "A" line or Atterberg limits plot -San y mixtures plasticity index Ping 1ri hatched area c less than 4 are borderline pt •.� �.� Clayey gravel:,, gravel_ Atterberg s p o above "A" line and classifications re- qui ring use of dual i & r, sand -clay mixtures plasticity index symbols o � greater than 7 Hell -graded sands and ou ' D60 D10 Greater than 6 19 d gravelly sands, little (Dxn12 a N a or no fines C, - D10 X Od0 Between 1 and 3 st H Poorly graded sands and 8 gravelly sands, little Not meeting both criteria for SN N or no fines log Silty sends, sand -silt Atterberg limits plot below "A" line or Atterberg limits plot- mixtures plasticity index less Ling in hatched area than 4 are borderline clas- 5 5 Clayey sands, send -clay er s plot " above A line and sifications requiring use of symbols e N., mixtures plasticit index �, I""., A " greater thian Inorganic silts, rock flour, silty or clayey Ic fine sand Inorganic clays of low to medium plasticity, yrev- 60 a elly clays, sandy clays, silty clays, lean clays 50 Organic silts and organic OL silty clays of low 40 plasticity Inorganic silts, micaceous30 hig or diatomaceous silts, elastic silts a PO Inorganic clays of high w CIi plasticity, fat clays 1g 4 O Organic clays of medium OR to high plasticity Plaetiaiiv hart for otwe{fioation of fin•- gmined .oils and fine fivation of ooaree-grained soils. Atterberg limit# plotting in hatohed area are borderline ot"sifioatione requiring we of dual eymbote. lquation of A-Un4r., PI 0.78 (LL-!0 FQb W 0 10 20 30 40 50 60 70 80 90 100 Liquid limit Peat, muck end other Hignly organic soils Pt highly organic soils Vlsuai-manual identification BRAHH' ENGINEERING TESTING i BRAUN ENGINEERING TESTING, INC. 6800 S. COUNTY ROAD 18. P. O. BOX 35108 • MINNEAPOLIS, MINNESOTA 55435 PHONE 612-941.5600 MEMO -LETTER TO Mr. Scott Abernathy c/o David Nitz, Inc. 464 Second Street Excelsior, MN 55331 I- Mr. Abernathy: DATE March 8, 1978 S,SJECT Prudden Residence Lot 10, Block 1 Farview Addition The proposed drainfield for the 4 bedroom house (Prudden Residence) situated on Lot 10, Block 1 of the Farview Addition should consist of 6 lines, 80 feet in length with 7-foot center to center spacing. The system lc;cation is as shown on the attached sketch. $y 4A14 N72 TT, NP q 9 sd. 1. . ba 3W. 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