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Home My WebLink AboutGOMBART Plat# 74-143 Soils Log S-3192 GEOLOGICAL SOIL INVESTIGATION OF GOMBART PROPERTY Located in the SE 1/2, SE 1/4, SE 1/4, NE 1/4, Section 25, Township 12 North, Range 3 West, Seward Meridian, Alaska September 14, 1973 PREPARED FOR: Dr. A. K. Gombart 5010 Abbott Road Anchorage, Alaska 99507 PREPARED BY: H. V. Lounsbury & Associates 723 West 6th Avenue Anchorage, Alaska 99501 W. O. #73-404 TABLE OF CONTENTS INTRODUCTION SITE DESCRIPTION FIELD INVESTIGATION SUB-SURFACE CONDITIONS CONCLUSIONS AND RECOMMENDATIONS LOCATION MAPS AND FIELD DATA INTRODUCTION This report is the result of field investigations taken September 13, 1973, on the subject property off Upper DeArmoun Road, Greater Anchorage Area Borough. It comprises 5.0 acres. The purpose of the investigation was to determine feasibility of on-site sewage-disposal and proposed foundation construction within existing regulations con- cerning this matter. SITE DESCRIPTION The property is located mostly north of and adjacent to Upper DeArmoun Road. It is in its natural state except for entry road, shack, and cleared area on its eastern portion. The land is on the side of a mountain escarpment and slopes to the south and southwest at an even an uniform grade. Vegetation consists of occasional large birch and spruce trees in groups together with heavy brush and alder. A small drain runs through the approximate center of the property. The roadway encroaches inside the southern boundary. FIELD INVESTIGATION Test trenches were dug to determine the representative sub-surface soil strata. The field data shows the results of visual inspection of these trenches. Penetration onto the west portion of the property proved impossible with available equipment due to heavy brush, trees and high embankments from the road. Road cuts of five through seven feet were examined. SUB-SURFACE CONDITIONS The "Generalized Geologic Map of Anchorage and Vicinity, Alaska, 1972" published by the U. S. Geological Survey defines soils in the immediate area as colluvium (slope deposits). These deposits generally consist of poor to well graded and sorted sandy gravels with some silt and clay. They are usually bedded parallel to the slope° Depth varies over bedrock. Findings 'from representative test trenches confirmed the above de- signations and revealed silty gravels or silty, sandy gravelly soils. In lower parts of the trench, soils were moist but not wet. No evidence of ground water was present. Road cuts in the lower one-third of the property also confirmed test trench data along the ~ntire l~ngth of the property. The U. S. Geological Survey, Water Resources Division, reports water wells 100 feet through 155 feet in the imnediate area with bedrock anywhere from 50 feet to 144 feet. We would estimate bedrock at greater than 50 feet throughout the property with the water table being variable but deeper than 15 feet in most locations. CONCLUSIONS AND RECOMMENDATIONS From field investigations and other data available, the land under investigation appears suitable for the proposed residential development. The following recommendations are made: 1. For foundations, bearing values on undisturbed soils may be in the medium to high range, not exceeding six tons per square foot, Structures should not be placed immediately above high road cut banks. Large or deep fills over existing ground should receive special consider- ation of a registered engineer. Special structures with singular foun- dation characteristics will require more detailed soils investigations for the specific case, 2. Water wells will probably be in excess of 100 feet in depth and should be placed on the upper two-thirds of the property. Existing regulations should be consulted concerning location and construction of water wells. 3. On-site residential sewage disposal will require a design factor of at least 225 square feet per bedroom; one alternate location for seepage pits constructed should be provided for each system. Lo- cation and design of such disposal facility should be in accordance with existing regulations. Seepage pits when constructed should be as deep as possible, especially adjacent to down-sloping cut banks and should be backfilled with appropriate filler material. A minimum lot siz,~ of 1.25+ acres is recommended when using on-site disposal systems. Respectfully submitted, HEWITT V LOUNSBURY & ASSOCIATES hn R. Clark, P.E. - ...... , .:- ,., Dat~ C~mpleted ~jecl Nome ~ac~tion Method U~ed ~eot~er Geo/ogixt Sheet ~-~ of . Total Depth ( [ ' ~: 'D~epth Ground Water Fable t'~- Aa FL J Dale DE'SCR IP T I 0 N $oil /?pe, co/or, lex/ute, esl/mo/ed particle sizG sampler driving notes, depths Cl~CulalMn lost, no/es on drilhng ease, b//s uxed, etc. Locahbn /Votes £ Dlbgram: ,, · ' ~ ' ' ~!9 ~-.~. Vegetation; -C,L.~,~'~t?O C-~'D Pooe. o~c. tz'o %~( ~h-.'~'(¥5:Q,;,$ U~7/e~,$ ot.,~rw,;e nst~d o.'/ $~rnp/o5 .qro lgken i~;//.-t ,',) .g/a,vd~rd /':,,-,el/ct, os 50mLHsr drllvcn ~'//';tO lb ,5oa,,~50r ~0" d.'?P. Dol~ Con;~let~d e).la_--?3 "eY/itt g. L'ounsbury '~ Assoc' Engineers ~ Surveyors Ancboroge~ · Al~zskcz . ~.g~ ~ 1~ ~CUe~ Geologist e ct;~ ' //a m e Loc~1ion Method Used Field Part), W~otlwr Sampling Hole No. Sheet Total Dep/h .. Ground kVoter Table Depth in FZ T/me ~oF~' ~ ~b~C~k D_ate. I Locolk~n Notes DESCR I P TI ON uw~rum: $oil lype~ colo6 texture, sampler drlw~g notes, notes on dr/'lh;w ease, ] , ~Z?/ess ol,~.,rw;$e 70" w, i.-, ,O .t~,.d~rd ,. ,~l~c,,o Sar, valor dr/yen w/14O Ib. ,~a,~,mer ., dr?p. ~Jl~61 O,'/ Fom,n/e.~ 9re t,3~en / ~'" ~ ~ ~-~ ~ ' ' .