HomeMy WebLinkAboutBRANDEE S-4964
4040 "B" STREET
ANCHORAGE, ALASKA 99503
(907) 278-1551
September 5, 1978
W.O. #Dl1220
Mr. Dee Walker and
Mr. Joe Sesto
SRA Box 290W
Eagle River, AK 99577
Subject:
Subsurface Investigation for Suitability of
9.~T~!te Sewage Disposal Systems for
~~nd Sesto Subdivision
~~ 1/4, Section I and the
NE 1/4, Section 2, T.14N., R.2W., Seward
Meridian, Alaska
Gentlemen:
As requested on August 11, 15, 16, and 23, 1978 a subsurface
investigation was performed on the above two referenced
subdivisions. The data from that investigation is presented
in the following format:
Conclusions
Discussions
Test Hole Locations, Brandee Subd.
Test Hole Locations, Sesto Subdivision
Test Hole Logs
Grain Size Distribution Curves
Standard Explanatory Information
Figure 1
Figure 2
Table A
Sheets 1-4
Sheets 5-6
CONCLUSIONS
It should be possible to construct on-site sewage
disposal systems on all of the lots within Brandee
Subdivision and Sesto Subdivision in conformance with
State of Alaska and Municipality of Anchorage regulations.
e
No high ground water or bedrock was encountered on the
site.
e
The site generally consisted of a thin cap of organic
overburden and topsoil with clean to somewhat Silty
~gnd~ ~ravels and Gravels below that. Drilling was
difficult because ~f the amount of boulders and cobbles
present. This was the reason for terminating some of
the holes shallower than 16'.
Mr. Dee Walker a- ~
Mr. Joe Sesto
September 5, 1978
Page 2
Following are the design percolation rates for all lots
within the subdivision.
Lot
Lot 1, Brandee Subd.
Lot 2, Brandee Subd.
Lot 3, Brandee Subd.
Tract A, Brandee Subd.
Tract A, Sesto Subd.
Tract B, Sesto Subd.
Tract C, Sesto Subd.
Tract D, Sesto Subd.
Percolation Rating
2.0 - 8.0' minutes/inch
estimated. No test hole
placed on this lOto
2.0 minutes/inch
8.0 minutes/inch
13.3 minutes/inch for TH#3
2.5 minutes/inch for TH#4
1.2 minutes/inch for TH#5
2.0 minutes/inch
8.0 minutes/inch
10.0 minutes/inch
13.3 minutes/inch
DISCUSSION
The test holes were placed using a Mobile Drill B-50 drill
rig owned and operated by Denali Drilling, Inc. The test
holes were logged and the drilling supervised by Mr. Tom
Sexton, staff geologist with Alaska Testlab.
The holes were drilled using continuous, solid flight auger,
with samples being taken at regular intervals directly off
the drill bit as it was raised to the surface. Each sample
was placed in a sealed plastic bag and transported to the
laboratory where its natural moisture content and dry strength
were determined. Samples of similar color, texture, grain
size distribution were given an arbitrary group designation.
The laboratory analysis was then performed on a composite
sample from the group rather than on individual samples.
A total of four distinct soil groups were encountered and
are described below:
Group A
is a brown Gravel that is non-frost susceptible,
being rated NFS. Its unified classification is GP
and its gradation is shown on Sheet 1. The per-
meability of this soil should be excellent.
Mr. Dee Walker a
Mr. Joe Sesto
September 5, 1978
Page 3
Group B
is a brown Silty Gravelly Sand that is moderately
frost susceptible, being rated F-2. Its unified
classification is SM and its gradation is shown on
Sheet 2. The permeability of this material should
be good to fair.
Group C
is a brown Sandy Silt that is highly frost susceptible,
being rated F-4. Its unified classification is ML
and its gradation is shown on Sheet 3. This
material is not very permeable, but it was found
only at a shallow depth. It should be possible to
place all systems below this layer.
~oup D
is a brown Silty Sandy Gravel that is moderately
frost susceptible, being rated F-1. Its unified
classification is GM and its gradation is shown on
Sheet 4. The permeability of this material should
be good to fair.
After all holes were drilled, it was attempted to case each
hole with slotted, 3/4" PVC pipe. This pipe was used as
casing to run the percolation tests. Because of the highly
cohesionless nature of most of the soils, it was impossible
to insert the pipe in test holes #1, #2, and #9. Each of
the remaining holes was then saturated with water and left
to stand overnight. Then the test holes were refilled with
water the next day. The rate at which the water fell in the
pipe was then measured at 10 minute intervals for a period
of one hour. The percolation rate was computed on the basis
of the lowest fall of the water during any 10 minute interval
of the test.
Though no actual percolation test was run in test holes #1,
#2, and #9, we feel the values listed under Item #4 of the
Conclusions are good estimates though probably a little
conservative. The values were arrived at by reviewing the
visual classification of the soils, the grain size distribution
curves and percolation rates in similar soils on the site.
We hope that this is sufficient for your present needs. If
we can offer any clarification with regard to this report,
please do not hesitate to contact us.
Very sincerely,
ALASKA TESTLAB
Melvin R. Nichols, P.E.
Laboratory Manager
MRN:rb
Enclosures
, ,~,a'oce '
'^~ ,,6£ ,~,0 oO 'N
'08
Test Hole
Table A
W0 #Dl1220
Logged By: Tom Sexton
Date: August 11, 1978
pepth in Feet
From To
0.0' - 7.0'
7.0' - 20.0'
Soil Description
NFS, tan Gravel, GP, dry, many cobbles,
occasional boulders, particles to 24",
Group A.
F-2, brown ~ Gravel}~ Sand SM, damp,
medium density, particles to 1[, Group B.
Bottom of Test Hole:
20.0'
Remarks: Would not stand open
to run percolation test.
Frost Line:
Free Water Level:
None Observed
None Observed
Sa~. pl~ Depth
3.0'- 5.0'
8.0'-10.0'
13.0'-15.0'
Type of Dry
M.} ~ample Strength Group Unified
3.3 G N A GP
4. I G N B SM
5.4 G N B SM
Remarks: 1.
3.
4.
5.
6.
Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, M=~edium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #2
Table A
WO #Dl1220
Logged By~ Tom Sexton
Date~ August 15, 1978
Depth in Feet
From To
0.0' - 16.0'
Soil Description
NFS, brown or tank Gravel, GP, dry to damp,
many boulders, Group A.
Bottom of Test Hole:
16.0' Remarks~
Would not stand open
to run percolation test.
Frost Line:
Free Water Level:
None Observed
None Observed
Test Hole 93
Table A
WO #Dl1220
Logged By: Tom Sexton
Date: August 15, 1978
Depth in Feet
From To
0.0' - 1.0'
1.0' - 6.0'
6.0' ' 15.0'
Soil Description
Organic overburden
F-4, brown Sandy Silt, ~{L, damp to wet,
cobbles at 6' Group C
F-l, brown Silty Sandy Gravel, GM, da.mp to
wet, partici~-~ To ']'~, Gr-~ 5.
Bottom of Test Hole:
Frost Line:
Free Water Level:
16.0'
None Observed
None Observed
Sampl~ Depth M%
1 5.0' 22.9
2 8.0'-10.0' 12.5
Type of Dry
Sampl.~. Strenqth Group Unified
G M-H C ML
G L D GM
Remarks: 1.
3.
4.
5.
6.
Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
~Dry Strength, N=None, L=Low, ~=Medium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #4
Table A
WO #D11220
Logged By: Tom Sexton
Date: August 15, 1978
Depth in Feet
From To
0.0' - 1.0'
1.0' - 16.0'
Soil Description
Topsoil
F-l, brown Silty Sandy Gravel, GM, damp to
wet, particles to 1", Group D.
Bottom of Test Hole:
Frost Line:
Free Water Level:
16.0'
None Observed
None Observed
Sample Depth
1 5.0'
2 10.0'
3 15.0'
Type of Dry
M% Sample Strength Group Unified
7.2 G N D GM
9.6 G N D GM
9.9 G N D GM
Remarks: 1.
3.
4.
5.
6.
Type of Sample, G=Grab, JP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, M=Medium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #5
Table A
WO #Dl1220
Logged By: Tom Sexton
Date: August 16, 1978
D~pth in Feet
From To
0.0' - 2.5'
2.5' - 4.0'
4.0' - 13.0'
Soil Description
Organic overburden.
F-4, brown Sandy Silt, ML, wet, Group C.
F-l, brown Silty Sandy Gravel, GM, damp to
wet, particles to I'~, Group D.
Bottom of Test Hole:
Frost Line:
Free Water Level:
13.0'
None Observed
None Observed
Sample D~.pth
1 4.0'- 5.0' 8.7
2 9.0'-10.0' 8.2
Type of Dry
Sample Strength Group Unified
G N-L D GM
G N D GM
Remarks: 1.
3.
4.
5.
6.
Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, M=Medium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole
Table A
WO #Dl1220
Logged By: Tom Sexton
Date~ August 16, 1978
Depth in Feet
From To
0.0' - 1.5'
1.5' - 2.5'
2.5' - 15.0'
Soil Description
Organic overburden.
F-4, brown Sandy Silt, ML.
F-l, brown Silty Sandy Gravel~ GM, damp,
Group D.
Bottom of Test Hole:
Frost Line:
Free Water Level:
15.0'
None Observed
None Observed
Sample Depth M%
1 4.0'- 5.0' 6.1
2 8.0'-10.0' 15.3
3 13.0'-15.0' 5.7
Type of Dry
Sa~plg. Strength Group Unified
G N D GM
G L D GM
G N D GM
Remarks: 1.
e
3.
4.
5.
6.
Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, M=Medium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #7
Table A
WO #Dl1220
Logged By~ Tom Sexton
Date: August 16, 1978
D~pth in Feet
From To
0.0' - 1.5'
1.5' - 4.0'
4.0' .- 15.0'
Soil Description
Organic overburden.
F-4, brown Silt, ML, wet to saturated, soft.
F-l/F-3, brown Silty Gravel, GM, with trace
of sand, wet, cobbles.
Bottom of Test Hole:
Frost Line:
Free Water Level:
15.0'
None Observed
None Observed
Sample Depth M%
1 8.0'-10.0' 19.4
Type of Dry
Sample Strength Group Unified
G L - GM
Remarks: 1.
3.
4.
5.
6.
Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, M=Medium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #8
Table A
WO #Dl1220
Logged By: Tom Sexton
Date: August 23, 1978
Depth in Feet
From To
0.0' - 2.5'
2.5' - 15.0'
Soil Description .
Organic overburden
F-l, brown Silty Sandy Gravel, GM, cobbles,
hand drilling, damp, Group D.
Bottom of Test Hole:
Frost Line:
Free Water Level:
15.0'
None Observed
None Observed
Sample Depth M~
4.0'- 5.0' 5.4
9.0'-10.0' 7.5
13.0'-15.0' 10.2
Type of Dry
Sample Strength Group Unified
G N D GM
G N D GM
G N D GM
Remarks:
3.
4.
5.
6.
Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, ~=Medium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #9
Table A
WO #Dl1220
Logged By: Tom Sexton
Date~ August 23, 1978
Depth in Feet
From To
0.0' - 2.5'
2.5' - 3.5'
3.5' - 13.0'
Soil Description
Organic overburden.
F-4, brown Saqdy Silt, ML, wet, soft.
F-l, brown Silty Sandy Gravel, GM, damp,
hard drilling, Group D.
Bottom of Test Hole:
Frost Line:
Free Water Level:
13.0'
None Observed
None Observed
Sample Depth M%
1
2
4.0'- 5.0' 6.3
8.0'-10.0' 10.8
Type of Dry
Sample strength Group Unified
G N D GM
G N D GM
Remarks: 1.
3.
4.
5.
6.
Type of sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, M=Medium, H=High.
Group refers to similar material, this study only.
General Information, see Sheet 1.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
,,LH~I]IMA~I R~NII~ IN'lO l:l'Zd
Test Hole LO9 - Description Guide
The soil descriptions shown on the logs are the best estimate of the soil's
characteristics at the time of field examination and as such do not achieve the
precision of a laboratory testing procedure. If the log includes soils samples,
those samples receive an independent textural classification in the laboratory
to verify the field examination.
The logs often include the following items:
Depth Interval - usually shown to 0.1 foot, within that zone no
significant change in soil type was observed through drill action, direct
observation or sampling.
Frost Classification - NFS, Fl, F2, F3, F4, see "Soll Classification
Chart"
Texture of Soil .. An engineering classification of the soils by particle
size and proportion, see "Soil Classification Chart", note tile
proportions are approximate and modifications to the soil group due to
stratification, inclusions and changes in properties are included.
Moisture Content this is a qualitative measure:
d_.~., no or little apparent surfi~ce moisture,
damp. moisture forms portion of color, less than plastic limit,
wet, no fret' water, often soft, if cohesive soil,
saturated, free water may be squeezed out, if a free draining soil;
dilatent at natural moisture content, if a non-plastic silt or fine
sand. (The moisture content is further definedby reference to PI,
LW, NP, M% or di]atency.)
Density - refers to more-or-less non-cohesive soils, such as sand gravel
mixtures with or without a fine fraction, derived from drilling action
and/or sample data: usually described as: very loose, loose, medium
dense, very dense. General intent' is to portray earthwork
characteristics.
Stiffness - refers to more-or-less cohesive soils and fine grained silts of
~h-~-clay-silt groups. Derived from drill action and/or sample data. Very
soft, soft, stiff, very stiff and hard are commonly used tertns.
Particle size -- The largest particle recovered by the split spoon is
1-3/8", Shelby tube 3", auger flights {minute-man} 2", Auger flights
(B-50 hollow stem) §"-8". Larger particles are described indirectly by
action of the drilling and are referred to as cobbles, 3" to 8", or
boulders 8"+. Therefore wheu reviewing the gradation sheets, if any,
the description on the hole log must be considered for an"indication of
larger particles.
Unified Soil Classification -. This is a two letter code. See Unified
Classification sheet for fm:ther definition. In some cases AASHO a,~d/or
FAA soil classifications may be shown as well as the unified.
Atterberg Limits - useful for fine grained and other plastic soils.
PI; natlual moisture content believed to be less than plastic limit
PI+; natural moisture content believed to be between plastic and liquid
ITmits
L___~; natural moisture content believed to be greater than liquid limit
NP; non-plastic, useful as a modifying description of some silty
materials.
Dil,atency - is the ability of water to migrate to the surface of a
saturated or nearly saturated soil sample when vibrated or jolted - used
as an aid to determine if a fine grained soil is s slightly or non-plastic
silt or a volcanic ash.
Rock flour - finely ground soil that is not plastic but otherwise appears
~ chyey silt.
Organic Content - usually described as Peat, PT, sometimes includes
d~screte particles such as wood, coal, etc. as a modifier to an inorganic
soil. Quantity described as: trace, or an estimate of volume, or, in case
of all organic, - as Peat. This may include tundra, muskeg and bog
material.
Muck -- a modifier used t, describe very soft, semi-organic deposits
usury occuring below a peat deposit.
Amorphus peat -. organic particles nearly or fully disintegrated.
Fibrous Peat - organic particles more-or-less intact.
Bottom of Testhole - includes last sample interval.
Frost Line - seasonal frost depth as described by drilling action and/or
samples at the time of drilling.
Frozen Ground - other than frost line, described by samples, usually
includes description of ice content, often will include modified Unified
Classification for frozen soils - this is a special case related to
permafrost studies.
Free Watar Level - The free water level noted during drilling. This is
not necessarily the static water table at the time of drilling or at other
seasons. Static water table determination m other than very permeable
soils requires observation wells or piezometer installations, used only in
special cases.
Btow/6" -- The nmnber of blows of a 140 weight free falling 30" to
advance a 2" split spoon 6"; the number of blows for a 12" advance is,
by definition, the standard penetration.
natural moisture content of the soil sample, usually not
p--~formed on clean sands or gravels below the water table.
Type of Sample -
~$P, refers to 2" split spoon driven into tile soil by 140 pound
weight, a disturbed sample,
S, thin wall tube, "Shelby" used to obtain undisturbed satnples
of fine grained soil,
G, "grab" disturbed sa~nple from auger flights or wall nf trench,
.Ce., cut sample, undisturbed sample frorn wall of trench.
Dry Strength - a nseful indicator of a soil's clayey fraction, N=None,
L=Low, M=Medium, H=High
-- Tile samples are placed into apparently similar groups based
or and texture and are arbitrarily assigned a group letter. Further
disturbed tests including Atterberg Limits, grain size, moisture-density
relationship, etc. may he performed on the group and are assumed to
reflect the general distrubed characteristics of the soils assigned to tile
group. This is an important phase of the soil analysis and is used to
standardize the various qualitative determinations and to reduce the
number of quantitative tests necessary to describe the soil mass.
SOIL CLASSIFICATION CHART
30% GRAVEL o\O
CLAY
CLAYEY CLAYEY CLAYEY CLAYEY
\
OR
SILTY
SILTY
SAND
SAN SANDY GRAVEL\
iGRAVEL:
GRAVELLY SAND SANDY GRAVEL GRAVEL
0 10 20 30 40 50 60 70 80 90 100
GRAVEL (+#4 SCREEN) % BY WEIGHT
NONFROST SUSCEPTIBLE SOILS ARE INORGANIC SOILS CONTAINING LESS THAN 3% FINER THAN 0.02 mm.
GROUPS OF FROST-SUSCEPTIBLE SOILS:
F1 GRAVELLY SOILS CONTAINING BETWEEN 3 AND 20% FINER THAN 0.02 mm.
F2 SANDY SOILS CONTAINING BETWEEN 3 AND 15% FINER THAN 0.02 mm.
F3 a. GRAVELLY SOILS CONTAINING MORE THAN 20% FINER THAN 0.02 mm. AND SANDY SOILS
(EXCEPT FINE SILTY, SANDS) CONTAINING MORE THAN 15% FINER THAN 0.02 mm.
b. CLAYS WITH PLASTICITY INDEXES OF MORE THAN 12. EXCEPT VARVED CLAYS.
F4 a, ALL SILTS INCLUDING SANDY SILTS.
b. FINE SILTY SANDS CONTAINING MORE THAN 15% FINER THAN 0.02 mm,
¢. LEAN CLAYS WITH PLASTICITY INDEXES OF LESS TFIAN 12.
d, VARVED CLAYS.
z
(83-341)F0 ~ '