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Home My WebLink AboutSLY-FOX SOIL INVESTIGATIONHARDING-LAWSON ASSOCIATES SOIL INVESTIGATION SLY -FOX SUBDIVISION GREATER ANCHORAGE AREA BOROUGH ALASKA JOB NO. 5518,001.08 Prepared for M & B ENGINEERING 8505 Rangeview Anchorage, Alaska 99504 by 17�!�/� YM. ENGLAND Civil Engineer 1943-E HARDING-LAWSON ASSOCIATES 127 West Fireweed Lane Anchorage, Alaska 99503 279-7011 December 17, 1973 HARDING--LAWSON ASSOCIATES INTRODUCTION This report presents the results of our soil investigation of the Sly -Fox Subdivision, Greater Anchorage Area Borough, Alaska. The sub- division consists of four lots, each about 50,000 square feet in area, located in the SWI/4, NEI/4, Section 24, Township 12 North, Range 3 West, Seward Meridian. The lots will be developed for single family residences and in- dividual wells for water supply and septic tank type sewage disposal facili- ties are planned for each lot. The purpose of our investigation was to explore the soil and ground water conditions in the subdivision by drilling a test boring on each lot. FIELD EXPLORATION AND LABORATORY TESTS We drilled test borings at the locations shown on Plate 1 using a Nodwell mounted, hydraulic rotary rig. The borings were advanced to depths ranging from eight to 20 feet using six-inch continuous flight augers, Our field engineer directed the exploration work, examined and logged the ma- terials encountered and obtained disturbed samples from the auger bit for visual classification and laboratory grain size analysis. The materials encountered in the borings, sample locations and other data are presented on the Logs of Borings, Plates 2 through 4. The soils are classified in accordance with the Unified Soil Classification System, described on Plate 5. In our laboratory we performed a grain size analysis on a sample repre- sentative of the material ten feet below the surface at each boring location. The results of these tests are presented on Plates 6 and 7. - 1 - HARDING-LAWSON ASSOCIATES SITE AND SOII, CONDITIONS The subdivision is presently undeveloped and is overgrown by seat- tered white spruce and locally thick alder underbrush. The ground sur- face is irregular and hummocky and generally slopes downward from east to west. The steepness of the downslope increases on the rear (west) half of the lots. An unimproved trail adjoins the east side of the lots. At the time of our exploration, the ground surface was blanketed by about four inches of loose snow and the surface soils were not frozen. The soil conditions encountered in our borings consists of a surface layer of forest litter about two feet thick underlain by silty, sandy and gravelly soils to the depths explored. The soils are of glacier origin, are chiefly till and were apparently deposited in this area as lateral moraine. Scattered cobbles (material in the 3 to 12 inch size) and boulders (over 1?. inches) are also present. Ground water was encountered in two borings (Boring 1 and 3, 3A) while the remainder of the borings were dry. We judge that the ground water is a localized seepage condition and that the water is migrating downslope confined in thin lenses of pervious sand and gravel. DISCUSSION Based on our investigation, it is our opinion that the lots are suitable for development for single family homes. Sewage disposal by septic tank - drainfield methods are feasible but the presence of natural seepage and silty soils on some of the lots will require that the systems be carefully designed. Percolation tests should be performed in each drainfield location to determine its size, - 2 - HARDING-LAWSON ASSOCIAT59 depth and layout and where natural seepage is present, subdrains may be necessary upslope to intercept and conduct groundwater away from the sewage drain field. We recommend that percolation test be delayed until the house and well locations are known and the size and orientation of the houses and any grading requirements have been determined. PLATES The following plates are attached and complete this report: Plate 1 Boring Location Plan Plates 2 through 4 Logs of Borings Plate 5 Soil Classification Chart Plates 6 and 7 Particle Size Analysis - 3 - Shear Strength (lbs/sq ft) Particle Size Analysis Particle 3ize knaly3is LOG OF BORING_1 Equipment 6" Flight Auger —� Elevation Date 11-26-•73 FOREST LITTER (Pt) roots, leaves, humus BROWN SILTY, GRAVELLY SAND (SM) with occasional. cobbles and/ .5 or boulders V water level 11-26-73 9.6 }p seepage @ 10' GRAY GRAVELLY SILT (ML) L O G O F BORING 2 Equipment 6" Flight Auger _ Elevation Date 11-26--73 ( i FOREST LITTER (Pt) roots, IL leaves, humus BROWN SILTY GRAVELLY SAND (SM) pz'-� /'f- GRAY SILTY SAND (SM) slight (about 10&) gravel 12.6 1 15 increasing gravel content @ 15' refusal on cobble or boulder @ 17'. No free water encount. HARDING-LAWSON ASSOGIA'TES PLATE rgN Consulting Engineers and Geologists L O G OF BORINGS 1& 2 SLY -FOX SUBDIVISION JobNo.5518,001.08 _Appr:-)me Date 12/73 -5- or } 21 w s p >1 c a E V 0 Lon 0". LOG OF BORING_1 Equipment 6" Flight Auger —� Elevation Date 11-26-•73 FOREST LITTER (Pt) roots, leaves, humus BROWN SILTY, GRAVELLY SAND (SM) with occasional. cobbles and/ .5 or boulders V water level 11-26-73 9.6 }p seepage @ 10' GRAY GRAVELLY SILT (ML) L O G O F BORING 2 Equipment 6" Flight Auger _ Elevation Date 11-26--73 ( i FOREST LITTER (Pt) roots, IL leaves, humus BROWN SILTY GRAVELLY SAND (SM) pz'-� /'f- GRAY SILTY SAND (SM) slight (about 10&) gravel 12.6 1 15 increasing gravel content @ 15' refusal on cobble or boulder @ 17'. No free water encount. HARDING-LAWSON ASSOGIA'TES PLATE rgN Consulting Engineers and Geologists L O G OF BORINGS 1& 2 SLY -FOX SUBDIVISION JobNo.5518,001.08 _Appr:-)me Date 12/73 -5- Shear Strength (lbs/sq ft) Particle 3ize knaly3is 14.2 ) 61 LOG OF BORING 3 Equipment_6" Flight Auger _ Elevation Date 11-26-73 FOREST LITTER (Pt) roots, leaves, humus water level 11-•26-73 BROWN SILTY SANDY GRAVEL (GM) GRAY GRAVELLY .SANDY SILT (ML) refusal on cobble or boulder @ 8' L O G O F BORING 3A Equipment 6" Flight Auger Elevation Dote 11-26-73 FOREST LITTER (Pt) roots, leaves, humus GRAY SANDY SILT (ML) slight (about 10%) gravel. water level 11-26-73 lense of sandy gravel @ 12' seepage @ 12' increasing gravel content @ 15' HARDING-LAWSON ASSOCIATES LOG OF BORING 3 & 3A PLATE 4 , Consulting Engineers and Geologists - -- SLY -FOX SUBDIVISION Job No.5518,001.06 _Appr:smeDate 12/73 -6- E u a� � N 0 c .c 0 w E E tJ 8 A 0tr- 14.2 ) 61 LOG OF BORING 3 Equipment_6" Flight Auger _ Elevation Date 11-26-73 FOREST LITTER (Pt) roots, leaves, humus water level 11-•26-73 BROWN SILTY SANDY GRAVEL (GM) GRAY GRAVELLY .SANDY SILT (ML) refusal on cobble or boulder @ 8' L O G O F BORING 3A Equipment 6" Flight Auger Elevation Dote 11-26-73 FOREST LITTER (Pt) roots, leaves, humus GRAY SANDY SILT (ML) slight (about 10%) gravel. water level 11-26-73 lense of sandy gravel @ 12' seepage @ 12' increasing gravel content @ 15' HARDING-LAWSON ASSOCIATES LOG OF BORING 3 & 3A PLATE 4 , Consulting Engineers and Geologists - -- SLY -FOX SUBDIVISION Job No.5518,001.06 _Appr:smeDate 12/73 -6- O 0 0 O s o r•N Ow -w PW m in O N „Ny R� +n m On v i 00 z(n 2Z y� 2 ro, gdd tiw � vq ray wW o yzL, o rz ItAN WQp y- w A N < W W m c D tr m � A 2 0 A DN m N y C �LCLpA sO hO�w O 5 Dym< WW<w -IDO-1 D rRyy:OA N rf ZDRIAymN WNpr S'0 ;�4C m z_ mfn°m-°11m o0 �o t�rD z�zc m e Elm w M1;21 n yn 2 m n P5 AW-io$ m>c � yzN==0 ��c �O D -Im s2cA Op ZD ocAP m,n m=C ALF�c �n�NO Otmi�r c- aD zoKmm ,,m. �nxomm �=nz OOL-imw Ow0 UD, KW` iln'DZo iZ 22moym c. mp 23D W�prw 3RZ-AI �Oni�1�i Z j, >0H i0 C3 nTC Z•U0 ry' of I'm OMOMJ'D zn cq O n m.W Z m y a m o Ly JZC dim irli KZ 2 s FnA�n m m m i - IAA 4 L ol O Z o p}m CJ I r N A � I� �J IAA 4 L ol O Z o p}m CJ I r N A � W ` 1/ /1 / 4& I� W ` 1/ /1 / 4& IEe„ RD O o _HILLSIDE D\ Raw 112W n m N LL LL Q: Shear Strength (lbs/sq ft) v a LOG OF BORING 4 Equipment 6" Plight Auger V [� [�' D ,° Elevation_ Date 11-7--.6-73 TTFOREST LITTER (Pt) roots, leaves, humus Silllll GRAY GRAVELLY SANDY SILT (ML) GRAYSILTY GRAVELLY SAND (SM) 6.4 10 witY occasional cobble or boulder sizes pp'd'' V No free water encountered -LO—CL OF _ Equipment _ Elevation _ Date HARDING-LAWSON ASSOCIATES Consulting Engineers and Geologists 5518,001,08 JobNo._Appr: 7meDate 11/73 -7- L O G O F BORING 4 SLY—PDX SUBDIVISION PLATE E 0 z SCALE 1" = 100' EXISTING RESIDENCE IHARDING-LAWSON ASSOICIATES ® Consulting Engineers and Geologists Job No. 5518,001.08Appy: 7meDate 12/73 -4- E+ W Ej H th m 0 U TRAIL STREET NOTE: Locations of borings determined by pacing and are approx- imate only. REFERENCE: Plat by M & B Engineering dtd. Nov. 1973 dwg 5283. . BORING LOCATION PLANPLAT E SLY -FOX SUBDIVISION BOROUGH OF ANCHORAGE 1 LOT 1 p.-.- TEST .4 BORING 3A *_ 3 LOT J. LOT 3 2 LOT 4 1 EXISTING RESIDENCE IHARDING-LAWSON ASSOICIATES ® Consulting Engineers and Geologists Job No. 5518,001.08Appy: 7meDate 12/73 -4- E+ W Ej H th m 0 U TRAIL STREET NOTE: Locations of borings determined by pacing and are approx- imate only. REFERENCE: Plat by M & B Engineering dtd. Nov. 1973 dwg 5283. . BORING LOCATION PLANPLAT E SLY -FOX SUBDIVISION BOROUGH OF ANCHORAGE 1 MAJOR DIVISIONS 'TYPICAL NAMES —• OW ,: WlLI GRAND GRAVtL3, GRAVEL - SAND MIXTURES CLEAN GRAVELS WITH LITTLE OR co a, GRAVELS NO FINES Tor POORLY ORADID GRAVIIS, ORAVIL - SAND ...I GP::a. MIXTURES v GM SILTY GRAVELS, POORLY GRADED GRAVEL - SAND - FA MOR! THAN HALF COARSE FRACTION ZS IS LARGER THAN GRAVELS WITH SILT MIXTURES Q NO. d SIEYE SIZE OVER IR%FINES w C GC CLAYEY GRAVELS, POORLY ORADID GRAVEL -SAND- a 'g7LAY CLAY MIXTURES a• 4SW as WELL GRAND SANDS, GRAVELLY SANDS ED CLEAN SANDS WITH rTLE OR I$ SP POORLY GRADED SANDS, GRAVELLY SANDS W Z SANDS NOFI NOFI Q MORE THAN HALF COMSE FRACTION SM . SILTY SANDS, POORLY GRADED SAND- SILT IS SMALLER THAN SANDS WITH MIXTURES No. / SIEVE SIZE OVER IS% FINS Sc CLAYEY SANDS, POORLY GRADID SAND - CLAY MIXTUSAES INORGANIC SILTS AND VERY FIN! SANDS, AOCX ci3 ML FLOUR, SILTY OR CLAYEY FINE SANDS, OR '^ CLAYEY SILTS WITH SLIGHT PLASTICITY —J 0 SILTS AND CLAYS INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY, InGRAVELLY CL CLAYS, SANDY CLAYS, SILTY CLAYS, LIQUID LIMIT LESS THAN SO LEAN CLAYS I 1 1 I ORGANIC GUYS AND ORGANIC SILTY CUPS OF d W I I LOW RUSTICITY INORGANIC SILTS MICACIOVS OR DIATOMACIOUS FINE SANDY OR SILTY SOILS, ELASTIC SILTS SILTS AND CLAY W ID GUYS OF HIGH PLASTICITY, IAT LIQUID LIMIT GREATER THA501: CLAY FA7 GUYS /i / ORGANIC CLAYS OF MEDIUM TO HIGH PIASTICITY, ORGANIC SILTS HIGHLY ORGANIC SOI PEAT AND OTHER HIGHLY ORGANIC SOILS UNIFIED SOIL CLASSIFICATION $YSTE:M SAMPLE 0E310NATION ®-Vndhtvrba d' SsnPla ® Sulk or Clmrlllcalloo Somplo STRENGTH TESTS 7'=0'Z74 VANE SHEAR TEST F • Halal L • Laboratory � UNCONFINED COMPRESSION TEST '.1000 (70.0) L—� DIRECT SHEAR TEST 1000 (30.0) TRIAXIAL COMPRESSION TEST } } CD Cenrvllda rad - Drolnad VU Unavmolidvbd - Un dralnad L CU • Con elide rad - r tUndro load Mol ura Canran, aNar Fart (%) CD Comollda rad - Dra load Sirau Normal ro Shaer Plana (pr l) I/E Devlaror Sirau (P.F) L7TMbbrara Co.,.., otlar Tnr (%) — Canllntnp Slrarr - OS (Irl) — KEY TO TEST DATA HARDING-LAWSON ASSOCIA'TECS SOIL CLASSIFICATION CHART PLATE Consulting Engineers and Geologists A%iw N _- KEY TO TEST DATA 5 Job No. 5518,001.08_Appr: 7meDate 12/73 SLY -FOX SUBDIVISION -8- -10- ..Illiril r �IIIri1 IYIII� 1■IIYIYII III 1 111111 111111 ■ ��1i111 1111111 `� 111111 111111 VIII 11111 � 11111■ 1111 .11111 11111 ■ ■ �II11 VIII I 1'll1 �..IIII �� 1 II II�II� 11 � � � III 1111 1 ■■ ■■ . Ill 11111 III ■I ■1111�„�1 II ►1 � 1 Ill�r. 1111111►. 111111 1111 � ■III ■ 1 111 1 ■■ ■■ •.1 111111 111111 1111111■1111 �� 1 � 1111 ■ ■ 1 I 1 1■ 1111 1►. HIM ,11 1■ 11111111 . �� 11 ■ 11111 111111 II 111 11111■ 11 ■ 111111 1111111 HIM 1 11111■■ 11� 1111111 iI11I11 SII 1 .III HIM 1111111 HIM 1111 II 11 ■ • 111111 VIII HIM ► 11111 1111 ■ 111111■ 11111 111111 ■ 1111111 1111■ 1 ■ . HIM III 111■ 111111 VIII 1 111111 111111 111111 II 111 ■ 1111 III11 ■ 'III III 111 rl ■11111 11111 1 1111111 1111111 II�I11 11111 11111 11111 , III II 111111 111111 HIM III II ,. CLAY s BORING 3A at 101 BORING PARTICLE Consulting Engiveers and Geologists SLY—FOX SUBDIVISION -10-