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Ig40 POST ROAD * ~ 279'258tX
W0= $16915 .t~ ~
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Subject= SLtelD~rmoun iff Rocky Road Soil
Gentlemen= ,.
In response to your recent request, transmitted herein
is the log of the test hole placed as specified on 21 August
1974. The test hole was drilled with solid flight auger by
a Mobile B-50 drill mounted on a Nodwell tracked vehicle
provided by Denall Drilling, Inc. The test hole was logged
and sampled by Mr. Kenworthy of our staff. The samples are
cuttings removed from the auger bit upon complete withdrawal
of the auger from the hole.
The general topography in the area of the test hole is
such that the test hole is about 7'-8' below the highest
point with about a 20'-30' drop in elevation to north and to
the east of the test hole. The test hole was drilled in a
cleared path through a wooded area with scattered moss and
Hudson's Bay Tea being the ground cover. 20-35' birch with
dense undergrowth of younger spruce and a few scattered
alders are common in the area. The test hole is 100' north
of the road and 50' south of property line along the cleared
path.
The data indicates the soils to be relatively imperme-
able down to about 5-1/2'; below that depth, to the depth of
exploration 15-1/2', the soils are slightly permeable. They
tend to be very dry and may be expected to accept moisture
into the void system.by capillarity and to have some aspira-
'tion to the surface through the root system of the foliage.
MEMBER
Alaska Land Development
August 29, 1974
Page 2
The soils are generally highly frost susceptible with the
surface material and the layer from 4' to 5-1/2' being the
most active in this regard. We recommend that standard
subarctic design and construction techniques be followed and
that care be given to surface drainage and to the use of
perimeter footing drains and frost breaks for structures
· founded on these soils.
~~...W.ith respect to.disposal of'on-s~te effluent th'e.G.AAB
published relatlonshlp between the unlfled so~l classifica-
tion and the number of square feet of absorption area per
bedroom indicates this material which is a G~below 5-1/2'/
to require approximately 225 square feet per bedroom. We
expect from the action of the drill that layers of cleaner
material exist, interspersed within the GM. Therefore, the
probability is that an effluent field founded in these
materials will be more satisfactory than indicated by the
disturbed samples. The use of a narrow leaching pit to
increase the wall area for a similar volume may be advan-
We trust the foregoing is sufficient to your immediate
needs though not necessarily exhaustive of the possibilities.
The single test hole may or may not represent the entire
area however, it is sufficiently encouraging that we do not
recommend additional test holes for either structural or
effluent adequacy at this time.
Very truly yours,
ItRL: rb
Enclosure
Test Hole A
Elevation:
Depth in Feet
From To
TABLE A
W.O. 16915
Soil Description
0.0' 0.5'
0.5' 4.0'
4~0' 5.5'
5.5' 15.5'
F-4, Tan sandy silt with ash, dry M1
F-l, Tan sandy silty ~ravel, damp, hard
2"-~ GM
F-4, Tan sandy gravelly silt, dry to damp,
hard, M1
F-l, Tan silty sandy Travel with occasional
cobbles, damp, dense, 3"~, G~!
Bottom of Test Hole:
Frost Line: None
Free Water Level:
15.5'
None observed
T~P~ OF
Sample Depth '~A~PI~
1 5' Grab
2 15' ' Grab