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HomeMy WebLinkAboutSTOLLE On-Site Wastewater Disposal System 4040 "B" STREET ANCHORAGE, ALASKA 99503 Ng%Oe7Ab~8-~ 5,511 9 8 0 W.O. #A19566 Grid #2043 Mr. Mike Stolle 814 West 2nd Avenue Anchorage, Alaska 99501 Subject: On-Site Wastewater Disposal System for Stolle Subdivision Located Within NE1/4 Section 6, Township 11N, Range 2W, Seward Meridian Gentlemen: This report presents the results of the subsurface soils investigatio~ of Stolle Subdivision performed on October 22 and 23, 1980 by Alaska Testlab. The purpose of this investi- gation was to assess the soil within the subdivision for suitability of on-site wastewater disposal systems. Included in this transmittal are: Test Hole Location Sketch Test Hole Logs Explanatory Information Figure 1 Figures 2-9 Sheets 1-3 The subsurface investigation was conducted using a Nodwell mounted Mobile B-50 drill fitted with a continuous flight solid stem auger. The drill is owned and operated by Denali Drilling, Inc. Drilling was supervised, the test holes logged and percolation tests performed by O.M. Hatch, geologist with Alaska Testlab. Test holes 1 and 7 were redrilled in locations shown in the Test Hole Location Sketch (Figure 1) because the ground water table was intercepted from 7 to 9 feet below the existing ground surface at the originally planned test hole locations. New holes were drilled until a location was found where the water table was below 12 feet from existing grade. The percolation tests were performed as follows: After drilling Was completed a 3/4 inch slotted PVC pipe was inserted into the hole to aid in measuring the free water level. The holes were then filled with water and left overnight to saturate for the percolation test. On returning blr. Mike Stollf~ November 4, 19~ ~ Page 2 the next day, the holes were refilled with water, and the drop in the water levels were carefully monitored over the next 60 minutes. Using the above test, the observed minimum percolation rate for each hole was as follows: TH 1 =2. TH 2 = 5. TH 3 = 5. TH 4 = 2. TH 5 = 2. TH 6 = 1. TH 7 = 6. 0 minutes/inch 0 minutes/inch 0 minutes/inch 9 minutes/inch 9 minutes/inch I minutes/inch 7 minutes/inch TH 8 = 2.0 minutes/inch We recommend that the seepage trenches be inspected prior to installing the system as the above percolation rates are based on the result of six inch diameter test holes. The seepage trench will provide a much clearer picture of the subsurface conditions than the test holes. If conditions are different from those encountered in the test holes, it may be necessary to lengthen or enlarge the trenches. We hope this report meets your present needs. If we can be of further service, please feel free to contact us. Sincerely, Engineering Geologist Approved by: Melvin R. Nichols, P.E. Manager TLB/mg/rb Attachments TH-7 W.T.=-9' 'H-8 ¸H-4 0 50 I00 SCALE IN FEET FIGURE I LOCATIONS OF TEST BORINGS 5 10 15 BORING NO. I ELEVATION = DEPTH ~GP:~ .NFS/F-l, BRO[~N SANDY GRAVEL WITfl TRACE SILT, ~.IOIST, :-[EDIU*'4 DE:~]SE, POOi{LY G~AD£D, .EUBROUNDED pARTICLES, BRO[~LN, SLIGR'iLY SILTY GRAVELLY SAND, MOIST, :.iEDIU:'I DENSE, POORLY ~ADED, SUBROUNDED PARTICLES, 2"+. BECODZES MORE SILTY WITH DEP~i'H. 'BOTTOM OF BORING = 16.0' COMPLETED 10/23/80 GROUNDWATER TABLE NOT ENCOUNTERED. MINIMUM PERCOLATION RATE MEASURED = 2 MIN/IN. KEY PP = UNCONFINED COMPRESSIVE STRENGTH {PENETROMETER)(TSF) TV: SHEAR STRENGTH (TORVANE)(TSF) MA= MECHANICAL ANALYSIS LL= LIQUID LIMIT (%) PI = PLASTIC INDEX []- GRAB SAMPLE []- SPT SAMPLE [] -- g,5" J, D. SPOON SAMPLE T 340~¢ WEIGHT~ 30" FALL [] - SHELBY TUBE- PUSHED ~7-GROUND WATER TABLE ? W.,LE B ,L,_,NG LOG OF BORING I0 15 BORING NO. 2 ELEVATION = DEPTH F-2, BROWN SAND, MOISq:, MEDIU[,I DEl{SE, POORLY F-2, BROWN GRAVELLY SILTY SAND, MOIST TO %~ET, MEDIUM DENSE, SUBR([U~DED PARTICLES, 3"+. F-4, BROWN GRAVELLY SANDY SILT, MOIST, STIFF, NON-PLASTIC, SUBROUN~ED PARTICLES, 2"+. BOTTOM OF BORING = 1~.0' COMPLETED 10/22/80. GROUNDUATER TABLE NOT ENCOUNTERED. MINIMUM PERCOLATION RATE MEASURED = 5 MIN/IN. KEY PP = UNCONFINED COMPRESSIVE STRENGTH (PENETROMETER) (TSF) TV= SHEAR STRENGTH (TORVANE)(TSF) MA= MECHANICAL ANALYSIS LL= LIQUID LIMIT (~/~} PI -- PLASTIC INDEX [] - GRAB SAMPLE [~- SPT SAMPLE [] - ~.5" I.D. SPOON SAMPLE T 340~¢ WEIGHT~ 30" FALL []- SHELBY TUBE-PUSHED ~- GROUND WATER TABLE ? WH,LE OR,LL,NG LOG OF BORING FIGURE 3 5 I0 15 2o .'*-"h W.O. NO. ,\~')5~,i, ~ LOGGED BY O.H. h,trciz BORING NO.3 ELEVATION: DEPTH F-2, BRO~'.u'N, SILTY GRAVELLY SAND WITH OCCASIONAL COBBLES, MEDIUm'4 DE~SE, POORLY GRADED, SUB- ROUNDED PARTICLES, 8"+. F-l, BROWN SILTY VERY SANDY GRAVEL. BOTTOM OF BORING = 16.0' COMPLETED 10/22/80. GROUND WATER TABLE NOT ENCOUNTERED. MINIMUM PERCOLATION RATE MEASURED = 5 MIN/IN. KEY PP = UNCONFINED COMPRESSIVE STRENGTH (PENETROMETER)(TSF) TV= SHEAR STRENGTH {TORVANE)(TSF) MA= MECHANICAL ANALYSIS LL= LIQUID LIMIT (%) PI = PLASTIC INDEX []- GRAB SAMPLE I'~- SPT SAMPLE [] -- 2..5" L D. SPOON SAMPLE T 3405 WEIGHT, SO" FALL [~]- SHELBY TUBE- PUSHED ~- GROUND WATER TABLE '~ WItILE DRILLING LOG OF BORING FIGURE 4 5 I0 15 BORING NO 4 ELEVATION = W.O. NO. A 19566 LOGGED DY O.M. Hatch D~PTN F-1, BROWN, VERY SANDY GR__A.V~E__L WITR OCCASIONAL COBBLES, .'.IOIST, NEDIUM ~E:;SITY, POORLY GP, ADED, SUBROUNDED PARTICLES, 6"+. BOTTOM OF BORING = 16.0' COMPLETED 10/22/80. GROUNDWATER TABLE NOT ENCOUNTERED. MINIMUM PERCOLATION RATE MEASURED = '2.9 MIN/IN. KEY pp = UNCONFINED COMPRESSIVE STRENGTH (PENETROMETER)(TSF) TV= SHEAR STRENGTH (TORVANE)(TSF) MA= MECHANICAL ANALYSIS LL= LIQUID LIMIT (%) PI : PLASTIC INDEX []- GRAB SAMPLE I~- SPT SAMPLE [] - 2.5" I.D. SPOON SAMPLE T 3,40:~ WEIGHT, 30" FALL []- SHELBY TUBE- PUSHED ~7_ GROUND WATER TABLE ? DR,L.,. GLOG OF BORING FIGURE 5 o BORING NO. 5 W.O. NO.. A IgGGG LOGGED BY O.M. Haich ELEVAT'ON: DEPTH F-2, BRO~,';N, SILTY SAND, .~iOIST ?0 WET, MEDIUM BRO~,x~N, GRAVELLY SILTY SAND, i~IOIST, blEDIUM DED~SE, POORLY GRADED, SUBROUND--~D PARTICLES, F-2, BROWN SILTY SANDY GRAVEL, >!OIST, MEDIUbi DENSE, POORLY GRADED, SUBROUNDED PARTICLES, 3"+. F-2, BROWN, GRAVELLY SILTY SAND, (DITTO 5'-10'). BOTTOM OF BORING = 16.0' COMPLETED 10/22/80. GROUNDWATER TABLE NOT ENCOUNTERED. MINIMUM PERCOLATION RATE MEASURED = 2.9 MIN/IN. KEY PP = UNCONFINED COMPRESSIVE STRENGTH (PENETROMETER) (TSF) TV= SHEAR STRENGTH (TORVANE) (TSF) MA-- MECHANICAL ANALYSIS LL= LIQUID LIMIT Pi = PLASTIC INDEX [] - GRAB SAMPLE []- SPT SAMPLE [] -- ?..5" LD. SPOON SAMPLE T 340~ WEIGHT, 30" FALL ~]- SHELBY TUBE- PUSHED ~7- GROUND WATER TABLE ? WHILE DRILLING LOG Oi:' BORING FIGURE 6 5 lO 15 BORING ELEVATION: .~-~ ~% ~%fO. LOGGED BY.O. Ni. Hatch 6 D~PTH !i !fl 1~_4, BRO;;N, SANDY SILT, WET, SOET, NON-PLASTIC. COBBLES, ~.!O]ST, ~4EDIU>i DENSE, POORLY GRADED, SUBROUNDED PARTICLES, 6"+. BOTTOM OF BORING = 1~.0' COMPLETED 10/22/80. GROUNDWATER TABLE NOT ENCOUNTERED. MINIMUM PERCOLATION RATE MEASURED = 1.1 MIN/IN. KEY PP = UNCONFINED COMPRESSIVE STRENGTH (PENETROMETER) (TSF) TV= SHEAR STRENGTH (TORVANE)(TSF} MA= MECHANICAL ANALYSIS LL= LIQUID LIMIT (%) PI = PLASTIC INDEX [] - GRAB SAMPLE []- SPT SAMPLE ~ - 2.5" I.D. SPOON SAMPLE T :540A~ WEIGHT, 30" FALL []- SHELBY TUBE- PUSHED r<7- GROUND WATER TABLE ----:- WHILE DRILLING LOG OF BORING FIGURE 7 0 15 P ,~--,~ BORING NO. 7 WO. NO. A IOSGG LOGGED BY. O. M. Hatah ELEVATION = DFPTH ..~OIS~, 51EDIU)I DENSE, F-2, BROWN SILTY SAND, " m POORLY GRADED. F-2, BROW~, GF~AVELLY SILTY SAND, 5JOIST, [4EDIUM DENSE, POORL~ GRADED',--S/~q~OUNDLD PARTICLES, 2"+. F-2, BROWN GRAVELLY VERY SILTY SAND, MOIST TO SATURATED, .qEDIUM DENSE, POORLY GR~RDED, SUB- ROUNDED PARTICLES, 2"+. BOTTOM OF BORING = 15.0' COMPLETED 10/23/80. MINIMUM PERCOLATION RATE MEASURED 6.7 MIN/IN. f KEY pp: UNCONFINED COMPRESSIVE STRENGTH (PENETROMETER)(TSF) TV= SHEAR STRENGTH (TORVANE) {TSF) MA= MECHANICAL ANALYSIS LL= LIQUID LIMIT (%) PI = PLASTIC INDEX []- GRAB SAMPLE ~- SPT SAMPLE [] - 2.5" I.D. SPOON SAMPLE T 540~ WEIGHT, 30" FALL ~- SHELBY TUBE- PUSHED ~- GROUND WATER TABLE -.- w,,.E DR,LL,NG LOG OF .lNG F~GURE 8 15 F-], BROWN, SILTY SANDY GRAVEL, MOIST, MEDIUM DE~;SE, POORLY GRADED, SUBROUNDED PARq'ICLES, 3"+. BOTTOM OF BORING = 16.0' COMPLETED 10/23/80. GROUNDWATER TABLE NOT ENCOUNTERED. MINIMUM PERCOLATION RATE MEASURED = 2 MIN/IN. KEY PP = UNCONFINED COMPRESSIVE' STRENGTH (PENETROMETER)(TSF) TV= SHEAR STRENGTH (TORVANE) (TSF) MA= MECHANICAL ANALYSIS LL: LIQUID LIMIT (%) PI = PLASTIC ~NDEX ED- GRAB SAMPLE []- SPT SAMPLE I~ - 2.5" I.D. SPOON SAMPLE T 340~ WEIGHT, 30" FALL []- SHELBY TUBE- PUSHED ~7- GRODND WATER TABLE ? WHILE DRILLING LOG OF FIGURE 9 Test Hole Lo9 - Description Guide The logs often include the following items: Depth Interval - usu4!]y shown to 0.1 foot, within that zone no significant change in soil type was observed through drill action, direct observation or sampling. Frost Classification - NFS, Fl. F2, F3, F4, see "Soil Classification Chart" Texture of Soil - An e::gmeering classification of the soils by particle size and proportion, see "Soil Classification Chart", note the proportions are approx:raa~'e and modifications to the soil group due to stratification, inclusions and changes in properties are included. damp. moisture :c:ms portion of color, less than plastic limit, sand. (]'he mo~stu.'e content is further defined by reference to PI, LW, NP, 84% or daatency.) mixtures with or wltho'-'t a fine fraction, derived from drilling action and/or sample data: usually described as: very loose, loose, medium Stiffness - refers to me.:e-or-less cohesive soi!s and fine grained silts of the clay-silt groups. Der:~ed from drill action and/or sample data. Very ~oft, soft, stiff, very st:f£ and hard are commoniy used terms. paxtide size - The largest particle recovered by the split spoon is I-3/8", Shelby tube Y'. auger flights (mnu e-man) 2", Auger flights (B-SO hollow stem) 6'-.v-''. Larger particles are described indirectly by action of the drilling ar, d are re(erred to as cobbles, 3" to 8", or boulders 8"+, Therefor: when reviewing the gradation sheets, if any, the description on the hoie log must be considered for an indication of larger particles. Unified Soil Classification - This is a two letter code. See Unified Classification sheet for :nether definition. In some cases AASHO and/or FAA soil classifications may be shown as well as the unifierS. Atterberg Limtts- usefu', for fine grained and other plastic soils. P_}l; hat.al moisture content beheved to be less than plastic limit Pi+; natural moisture content believed to be between plastic and liquid ~-lmit$ L.__~; natosal moisture contcltt believed to be greater than liquid limit NP; non-plastic, usef~:i as a modifying description of some silty mat&rials, Rock flour - finely ground soil that is not plastic but otherxvise appea/s similar to.a clayey silt. Organic Content - usually described as Peat, PT, sometimes includes discrete particles such as wood. coal, etc. as a modifier to an inorganic soil. Quantity described as: trace, or an estimate of volume, or, m case of all organic, - as Peat. ]'his may include tundra, muskeg and bog material. Muck - a modifier used to describe very soft, semi-organic deposits usually occuring below a peat deposit, Amorphus peat - orgamc particles nearly or fully disintegrated. Fibrous Peat - organic particles more-or-less intact. Bottom of Testhole - includes last sample interval. Frost Line - seasonal frost depth as described by drilling action and/or samples a~ the time of drilling. Frozen Ground - other than frost line, described by samples, usually includes description of ice content, often will include modified Unified Classification for frozen soils - this is a special case related to permafrost studies. Free Water Level - The free water level noted during drilling. This is not necessarily the static ss:alee table at the dine of drilling or at other seasons. Static water table determination in other than very permeable soils requires observation wells or piezometer installations, used oniy in special cas?. Blowl6" - The number of blows of a 140 weight free failing 30" to advance a 2" split spoon 6": the number of blows for a 12" advance is, by definition, the standard penetration. ,d% - natural moisture content of the soil sample, usually not p-~-rformed on clean sands or gravels below the water table. Type of Sample - S__P, teters to 2" split spoon driven into the soil by 1-40 pound weight, a disturbed sample, ..~ thin w.dl tube, "Shelby" used to obtain undisturbed samples of fine grained soil, C,, "grab" disturbed sample from auger flights or wall of trench, C, cut sample, undisturbed sample from wall of trench. Dry Stren't~ - a useful indicator of a soil's clayey fraction, N=None, L=Low,M=Medium, H=High Group - The samples .ire placed into apparently similar group~ based 0n color and texture and are arbitrarily a~.~gncd a group letter. Further .SOIL TEXTURAL CLASSIFICATION CHART GRAVEL 30 % CLAY ~!/ CLAYE ¢ OR SILTh SAND 0 I0 2.0 ' 30 40 GRAVEL (+ :b. 4. SILT GRAVEL 50 60 70 SCREEN) % BY WEIGHT GRAVEL 80 90 100 FROST CLASSIFICATION SYSTEM NONFROST SUSCEPTIBLE SOILS ARE INORGANIC SOILS CONTAINING LESS THAN 3% FINER THAN 0.02 mm. GROUPS OF FROST-SUSCEPTIBLE SOILS: F1 GRAVELLY SOILS CONTAINING BETWEEN 3 AND 20% FINER THAN 0.02 mm. F2 SANOY SOILS CONTAINING ~3EFWEEN 3 AND 15% FINER THAN 0.02 mm. F3 a. GRAVELLY SOILS CONTAINING !..IORE THAN 20% FINER THAN 0.02 mm. ANDSANOY SOILS · , (EXCEPT FINE SILTY. SANDS) CONTAINING MORE TITAN 15% FINER TITAN 0.02 mm. b. CLAYS WITH PLASTICITY INDt. XES OF MORE ¥1flAN 12. EXCEPT VARVED CLAYS. F4 a. ALL SILTS INCLUDING SANOY %ILFS. b. FINE SILTY SANOS CONTAINI~iCi MORE THAN 15% FINER THAN 0.02 mm. c. LEAN CLAYS WITH PLASTICITY INDEXES OF LFSS THAN ~2. d. yARVED CLAYS.