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HomeMy WebLinkAboutSLEEPY HOLLOW #1 Soils Logs
CONSULTING
ENGINEERS
1940 POST ROAD-ANCHORAGE, ALASKA-99501
TELEPNONE; 907-279-2581
PARTNERS ~ -~
AFFILIATED
'" '""wl/ill~ F. '¢/.WI~CE RE., RET
ALASKA TESTLAB-- .ASSOCIATES
K W BLEDSOE
P G HANSEN
R W. HUNT
~. L $CHEFFEL RE.
July 24, 1972
W.O. 11722
Gross Construction Company
841 West 74th Avenue
Anchorage, Alaska 99502
SUBJECT:
Soils, Sleepy Hollow Subdivision, Addition #1,
Peters Creek, GAAB, Alaska
Gentlemen:
In accordance with your request, we are currently making a sub-
surface investigation of the subject project; included herein
is our preliminary report.
Following the text are:
Test-pit logs Sheets 1 to 5
Standard explanatory information Sheets 6 and 7
Test-pit location sketch Attached
The proposed subdivision is located within West 1/2 of Sec. 15,
T. 1S N, R.1 W., S.M., Alaska, and totals approximately 100
acres. The bulk of development will be confined to 27 parcels
totaling about 80 acres; two tracts comprise the rema~nlng 20
acres.
In order to adequately evaluate the subsurface conditions within
this subdivision, we have recommended that a minimum of ten
test holes or test pits be made within the 100 acres. However,
because of access problems due to steep grades at the present
time, you were able to excavate by backhoe only four test pits
to the recommended depth. Efforts were made to complete the
remaining test pits by blasting, but these were not successful.
As soon as access becomes satisfactory for Arilling or backhoe
equipment to reach the remaining localities, the subsurface
investigation should be completed.
All test pits were logged by Mr. Ozias Hatch,
nician, on July 19, 1972. The writer visited
22, 1972.
our senior tech-
the site on July
The five test pits, including one 5-ft. test pit, indicate that
the site soils consist of a thin ground cover of organic materials
about six inches thick, and frost-susceptible sandy silt and silty
sand, 1 to 2-1/2 feet in thickness, all overlying extensive glacial
deposits of nonfrost-susceptible (NFS) sandy gravel and gravelly
sand to the depths of exploration.
Gross Construction Co. 2 W.O. 11722
With regard to subsurface conditions for the proposed development,
the only precaution item should be slope stability only in those
areas with significant grades (not road grades) where residences
are planned, as the subdivision has a prominent bluff area below
the higher ground (plateau). If construction in these steep areas
is the case, routine slope-stability analyses should be performed.
In all other aspects, the granular soils (sandy grave], and gravelly
sand) within the subdivision appear to be consistent, well-drained,
and sufficiently dense to provide a more-than-adequate performance
for foundation and development purposes. The sandy gravel and
gravelly sand deposits are sufficiently permeable, and thus are
very suitable for percolation of individual seepage pits. Cor-
relation between and consistency of the test pits is excellent,
and we anticipate that the remaining test pits will indicate
similar subsurface conditions. In our opinion, no foundation
conditions have been found to date which are unsatisfactory or
prohibitive~ and which would warrant impedence to this project.
As soon as site access is improved, the remaining exploration can
be completed.
Very truly yours,
ACLW Consulting Engineers
/ Paul G. Hans'~n, E'.I.T.
Approved:
Herr? R. Lee:.E.
PGH:ld
PROJECq.~.SL_~.EPY H_ OLLO~W
DATE JULY ]9, 1972
W.O. NO.. 11722
-TEST PIT ~. ...... EXISTING GROUND
CLIENT GROSS CONSTRUCTION
SIIEET ~. OF 7
JULY ]9~ 1972 :.,.;
W. O. NO..__I. 1722 ' ~z
Z
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C'LIENT GPOqS cn~'S'~'t~Uf"PTOx [~'07i'x;~,I DATE ,JULY ]9, 1972
PROJEC~Y ItOLLOI.~~ SUBD~N W.O.NO. 11722
· TEST PIT ~ __ELEv.~XISTING GROUND
~ CL. ENF GROSb CO, IS.RUCTION [~O25.~ DA~E ,IIII,Y ]9, ].97~ ~ .,
m PROJEC~ SLEEPY HOLLOIV SUBD~N XV O NO 11722
· TEST PIT ZI.EV EXISTING GROUND
CLIENT GROSS CONSTRUCTION
PROJECZ ~'P7 }~-L-~fi SUBD~N
TEST PIT ~ ELEv. EXISTING GROUND
DATE JULY ]9, 1972
W.O~.N0._11722 __7
ALASKA TESTLAB
CONSULTATION ~, TESTING ~ EXPLORATION © CHEMICAl_ Q MATERIALS ¢~ INSPECTION
SOIL CLASSIFICATION CHART
/
~0% GRAVEL
\
0 I0 20 30 40 50 60 70 80 90 100
G.~R AV EL (-F~SCREEN) % B~Y WEIGFLT=T
NONFROST SUSCEPTIBLE SOILS ARE INORGANIC SOILS CONTAINING LESS THAN 5% FINER THAN O,02mm.
GROUPS OF FROST-SUSCEPTIBLE SOILS:
FI GRAVELLY SOILS CONTAINING BETWEEN 3 AND ~0% FINER THAN O.02mm,
F~> SANDY SOILS CONTAINING BETWEEN 3 AND 15% FINER THAN O.02mm,
F3 o. GRAVELLY SOILS CONTAINING MORE THAN 20% FINER THAN O.02mm. AND SANDY SOILS
(EXCEPT [=INF~ SILTY, SANDS)CONTAINING MORE THAN 15% FINER THAN O,O2. mm.
b, CLAYS WiTH PLASTICITY INDEXES OF MORE THAN 12. EXCEPT VARVED CLAYS.
F4 o, ALL SILTS INCLUDING SANDY SILTS,
b. FINE SILTY SANDS CONTAINING MORE THAN 15% FINER THAN O,02mm,
¢. LEAN CLAYS WITH PLASTICI'['Y INDEXES OF LESS THAN 12.
d, VARVED CLAYS.
TEST HOLE LOGS
SOILS DESCRIPTIONS
The soil descriptions shown on the logs are the best estimate of the soil charac-
teristics at the time of field examination. Such examinations do not achieve the
precision of laboratory tests for the various properties.
1. The relative type of soil and the frost classification is shown on the sheet
"Soil Classification Chart."
2. Other criteria:
Boulder - greater than 8"
Cobble - approximately 3" to 8"
Blow Count - blows/6" of 140 lb. weight falling 30"; 2" split spoon. (The
standard penetration is blows/12".)
Density - estimated by the rate of drilling, type of soil, blow count and
moisture range
PL - Plastic Limit, moisture content being approximated as; above (+) or
below (-) plastic limit (PL) or liquid limit (Lw) as appropriate
Lw - Liquid Limit, see PL
Dilatency - is the ability of water to migrate to the surface upon vibration
or jolting of a sample, an aid in determining whether a soil is pre-
dominately a clay or silt
Well graded - uniformity coefficient greater than 7
Poorly graded - uniformity coefficient less than 7 (Uniform particles,
gap graded)
Organic Content - estimated by volume, not particularly precise
Clayey Soils - a field method now being used as an aid to identification
of these soils as a combination ball drop, and rolled thread test in
which a 2" diameter ball of the Sand-Silt-Clay fraction is dropped
2' until a 1" thick pat develops. The diameter of a Ihread at
crumbling rolled from the resultant pat determines whether clay.
or silt predominates.
Dry Strength - a small sample of the soil is formed into a cube and air
dried, and crushed between the fingers. High dry strength indi-
cates clays and low indicates silts.
Water Table ~ the apparent water table at the time of observation. Often
the actual water table may be higher unless the hole is allowed to
remain open or is converted to an observation well.
Capillary Fringe - change from moist to very damp, or saturated soil,
usually indicates that water table is close.
Peat - Fibrous material of macroscopic and microscopic fragments of de-
cayed vegetable matter; very compressible, unsuitable for founda-
tion or embankment. Color light brown to black.
Ao - The upper layer, surface soil or topsoil, containing humus and/or
organic debris, not satisfactory for foundation.
ALASKA TESTLAB
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