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ENGINEERS
1940 POST ROAD-ANCHORAGE, ALASKA- 9950l
TELEPHONE 907-279-2581
O'Malley Investment Company
C/O Dickinson-Oswald & Partners
800 Cordova Street
Anchorage, Alaska 99501
ATTENTION: Mr. Maurice Oswald, D & O,
and Mr. Earl Bell, O.I.C.
Gentlemen:
R S ADAMS PE
A N. CORTHELL RE, RET
H R LEE PE
F W 'NINCE PE, RE~
ASSOCIATES
K W BLEDSOE
P G HANSEN
R. ~ HUNT
d. L SCHEFFEL PE
March 5, 1973
W. O. 1 5748
In response to your recent request, nine test holes placed at
the staked locations, and three tests were added to provide
information regarding peat depths in the northerly portion of
the site. The data are arranged as follows:
Location of test holes - Figure 1
Soil Sections - Sheets 1 to 4
Test hole logs - Table A
Standard explanatory, information sheets
5 to 7.
The tes~ holes were placed with a Mobile B-50 Drill, mounted on
a Nodwell RN 75 tracked vehicle. The drill was fitted with
solid core and hollow stem auger. Samples were obtained from
the auger flights "grab" samples, and by means of a standard
two inch split spoon driven by 140 # weight free falling thirty
inches. The blows are recorded in number of blows/six inches,
(the number of blows to advance the spoon twelve inches is
defined as the "standard penetration").
The test holes were drilled by Denali Drilling, Inc., hole
logging and routine laboratory testing, Alaska Testlab,
analysis by the writer.
Three basic soils were encountered, peats, silts, and sands.
The peats are unsuitable for foundation purposes and should be
wasted in those areas where structures which cannot tolerate
differential movement are to be founded.
The silts include sandy silts, and gravelly silts, they are
the most common inorganic material in the shallow soil zone, ar,,.e
characterized by a relatively impermeable structure, and are
highly frost-susceptible. Structures founded on the silts which
cannot tolerate substantial differential movement require a heat
source which maintains the soil in a thawed state (heat loss
from building through basement or crawl space), avoidance of
O'Malley Investmen Company 2 March 5, 1973
surface water intrusion about the footings, and care to protect 'the
soils natural structure durina the construction sequence. Soils of
this nature are common to the general Anchorage Area, and have
sucessfully, in the past, been used to found structures when strict
attention to sub-artic constraints is maintained in design and
co ns tructi ons.
Sand including silty sands, were encountered in quantity only in
the southwest and northwest test holes. These materials, of those
common to the site, are the most easily adapted for foundation
purposes in either the disturbed or undistrubed state. They are
characterized by fairly high permeability, slight to moderate
frost heave potential, and by slight to moderate sensitivity to
moisture content during construction operations.
The soils section sheets 1 to 4 indicate the site to be fairly
complex A hump appears in the north that is not apparent from the
old topographic drawings, (based on the reported hole elevations)
which cause the peat depths to appear reasonable). However, the
reader is cautioned to utilize the profiles only for the roughest
of approximations with regard to the horizontal extent of the
various soils.
The inorganic soils generally were reasonably dense and stiff, and
should in their natural thawed state, provide adequate bearing, 'in
excess of 4,000 pcf.
The present free water levels are very likely linked to excess water
in the organic, peat, layer. However, in test holes 8, 7, and 5,
there is an indication of ground water independant of the peat deposit.
--Reviev~of the topQgraphic sketch indicates surface drainage is more or
less toward the site and could possibly be diverted.
The foregoing while intended to summarize the data for site planning
purposes, is not necessarily exhaustive of the possibilities. Therefore,
should there be questions or should we be of added assistance during
the further development of the project, do not hesitate to contact the
writer or Mr. Hatch of our staff.
Very truly yours
Harry R. Lee, P. E.
H RL: ds
TABLE A
TEST-HOLE LOGS
Test Hole 1
Depth in Feet
from to
0.0 0.5
0.5 2.0
2.0 6.0
6.0 8.5
8.5 15.0
Bottom of hole:
Free water level:
Sample
1
2
3
Soil Description
F4, brown peat, damp, soft, PT
F4, brown sandy silt, damp, MI.
NFS, brown, coarse sand, damp to wet, medium
density, SP
NSF, brown gravelly sand, wet, medium density,
1"-, SP
F4, grey silt, damp to dry, hard, (with gravel
and sand layers), 2' , ML
15.0'
None observed.
Depth (ft) B1 ows/6"
4 - Grab
7 - Grab
13 - 15 21/19/24/64' - Grab
* Hit a rock at 14.8'
Remarks: Possible seepage at 5'
Test Hole 2
Depth in Feet
from to
0.0 4.0
4.0 7.5
7.5 12.0
12.0 16.0
Bottom of hole:
Frost Line :
Free water level:
Sample
1
2
3
Soil Description
F4, brown meat and wood, near surface, changing
to organic silt near 4', damp, loose, PT
F4, grey sandy silt, damp, stiff, PLT, ML
(gradual increase in gravel content from 4' to
7.5').
F1 grey silty sandy gravel, damp, medium density
2"- , GM
F4 grey to olive gravelly sandy silt, damp, stiff,
3"- , ML
16.0'
2.0"
none observed
Depth (ft) Blows/6"
5 - Grab
10 - Grab
14 16 19/25/25/27 - Standard
Test Hole 3
Depth in Feet
from to
0.0 2.5
2.5 3.5
3.5 15.0
Bottom of hole:
Frost Line
Free Water Level:
Sample
1
2
~ 3
Soil Description
F4, brown peat, '(wood near surface) damp, loose,
F4, brown sandy silt, damp, stiff, PL-ML.
F4 grey to olive, 9ravellz sandy silt, damp,
stiff, ML, l'=
15.0'
1.5'
none observed.
Depth (ft) ~lows/6"
5 - Grab
l0 - Grab
13 - 15 12/17/31/30 - Standard
Test Hole 4
Depth in Feet
from to
0.0 6.0
6,0 13.0
Soil Description
F4, brown .peat wet to saturated, soft, PT
F4, grey gravellS sandy silt, damp medium
density, 1 ~-~,--~ L
Bottom of test hole 13.0'
Frost Line: 1.O'
Free water level 3.5'
Depth (ft) Blows/6"
8 - Grab
10.5 - 13 20/15/22/38/47 ~ Standard
Sam~_~9_
1
2
Remarks: Perforated pipe set 2' to 7' water enter at 3' and 6',
water level 7' at end of drilling 3.5' at 2 hours.
Test Hole 5
Depth in Feet
from to
0.0 6.0
6.O 11.0
11.0 14.0
Soil Description
F4 brown peat damp, soft
F2,grey silty gravelly sand, wet to saturated,
medium density, 2"- SM, (gravel fraction greatest
at 9')
F4, grey sandy silt, damp to dry, stiff to hard,
NP, ML
Bottom of hole: 14.0'
Frost Line : 2.0'
Free w a~er level: 2.5'
Sample Depth (ft)
1 7
2 l0
:: 3 12- 14
Blows/6"
30/34/40/34
Grab
Grab
- Standard
Remarks: water during drilling 4'
1 hour after drilling.
6' and 9'
ll', rise to 2.5' at
Test Hole 6
Depth in Feet
from to
0.0 4.O
4.0 15.0
Soil Description
F4, brown .peat, damp to saturated, soft, PT.
F4, grey ~ silt, damp to dry, stiff, PL-
or NP, ML (rand-~ layers of sand and gravel
below 11', color changes to olive below 11',
sand layers may contain free water).
Bottom of hole: 15.0'
Frost Line : 1.5'
Free wat'er level: 4.0'
~Sample Depth (ft) Blows/6"
1 5 Grab
2 l0 Grab
3 13 - 15 13/19/27/32
Remarks: Seepage at 2' and 4' stable at 4' at end of drilling.
Test Hole 7
Depth in Feet
from to
0.0 0.5
0.5 14.5
14.5 16.0
Soil Description
F4, brown organic debris (overburden) PT
F4, brown sandy silt, damp to saturated,
stiff, PL - ML
NFS, grey sand, wet to saturated, SP
Bottom of hole: 16.0'
Frost L~ne : 3.0'
Free water level: 12.0'
Sample _Depth (ft)
1 5
2 l0
3 14 - 16
Remarks: Observation well set with
Blows/6"
17/18/24/28
- Grab
- Grab
- Standard
~erforations ll' to 16'
Test Hole 8
Depth in Feet
t~rom to
0.0 10.0
10.0 15.0
Soil Description
F4, brown peat, damp to saturated, soft, PT
F2, grey gravelly sandy silt, saturated, 2", ML
Bottom of hole:
Frost Li ne :
Free water level:
15.0'
1 .5'
7.0'
Sample
1
2
D_~]~ t h (ft) Blows/6"
10 10.5
13 - 15.5 19/18/12/20
Remarks: Water intercepted at 8'
and 12'
Grab
Test Hole 9
Depth in Feet
from to
0.0 1t .5
11.5 12.5
12.5 15.0
Bottom of hole:
Frost Line :
Free water level:
Sample
Soil Description
1 15/21/25/26
F4, brown peat, damp to saturated, PT
F4, grey sandy silt, damp,stiff, PL - ML
F4, grey gravelly sandy silt, damp, stiff. PL-.ML
15.0'
2.0'
1.5'
Depth (ft) Blows/6"
13.5 15.0 - Standard
Remarks: Water encountered at 1' and 2', while dulling stable at
~ 1.5 at end of drilling.
Test Hole lO
Depth in Feet
from to
0.0 8.0
8.0 12.5
Soil Description
F4, brown peat, dampt to saturated, PT
F4, grey gravelly sandy silt, damp, stiff 2"-
Bottom of hole: 12.5'
Frost Line : 2.5'
Free water level: 4.0'
Sample
Depth (ft)
Blows/6"
I 10.5 - 12.5 10/14/19/52
Remarks: Water seepage at 4' and 8'
- Standard
Test Hole ll
Depth in Feet
from to
0.0 8.0
8.0 13o0
Soil Description
F4, brown peat, PT
F4, grey gravell$ silt, damp, ML
Bottom of hole:
Frost Li ne :
F'ree water level:
Sample
13.0~
1.0~
none observed
.D~p th ift)
10.5 to 13
B1 ows/6"
5/i2/27/26
Standard
Test Hole 12
Depth in Feet
from to
0.0 5.0
5.0 10.0
Soil Description
F4, brown peat, PT
F4, grey ,gravellS silt, damp, ML
Bottom of hole:
Frost Line :
Free wager level:
10.O'
1.5'
none observed
,Sample _Depth (ft) B1 ows/6"
10
- Grab
I I '
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SOIL CLASSIFICATION CHART
30O/o GRAVEL
N CLAYEY
CLAY E Y
\
/ OR
~/ ~ILTY
S 1 LT Y : \ ~, \
~ :/~ :~:~
SAND \
\ DY \GRAVE L
GRAVELLY \ SAND GRAVEL
o ~o 2o :~ 4o 50 60 70 eD 90 ~oo
GRAVEL. (+:b4S. C.REEN) % BY WEIGH,~T
NONFROST SUSCEPTIBLE SOILS ARE INORGANIC SOILS CONTAINING LESS THAN 3% FINER THAN O.O~'mm.
GROUPS OF FROST-SUSCFPTIBLE SOILS:
FI
F2
F3 o.
F4 o,
b.
¢.
d.
GRAVELLY SOILS CONTAINING BETWEEN 3 AND 20°/o FINER THAN O,OAmm,
SANDY SOILS CONTAINING BETWEEN 3 AND 15°/o FINER THAN 0,0;:' mm.
GRAVELLY SOILS CONTAINING MORE' THAN 20% FINER THAN O.02mm. AND SANDY SOILS
(EXCEPT FIN~.. SILTY, SANDS) CONTAINING MORE THAN 15% FINER THAN O,02mm.
CLAYS WITH PLASTICITY INDEXES OF MORE THAN 12, EXCEPT VARVED CLAYS.
ALL SILTS INCLUDING SANDY SILTS. ~
FINE SILTY SANDS CONTAINING MORE THAN 15% FINER THAN O,02mm,
LEAN CLAYS WITH PLASTICITY INDEXES OF LESS THAN 12,
VARVED CLAYS.
TEST HOLE LOGS
SOILS DESCRIPTIONS
The soft descriptions shown on the logs are the best estimate of the soil charac-
teristics at the ti~e of field examination. Such examinations do.not achieve the
precision of labo~tory tests for the various properties.
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
9.' untila 1" thick pat develops. The diameter of a thread 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.
.~.
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