HomeMy WebLinkAboutHERITAGE HILLS Tract D S-5064
DEPARTMENT OF HEALTH ANb ENVIRONMENTAL PROTECTION
PLATTING OR PLANNING AND ZONING CASE REVIEW
PETITION FOR REZONING
SPECIAL EXCEPTION
VACATION
~JJBDIVISION
FOR MEETING OF
COMMENTS:
ENVIRONMENTAL SANITATION:
PUBLIC WATER NOT AVAILABLE
of Cases
ENVIRONMENTAL ENGINEERING:
71-014 (9~76)
4040 "B" STREET
.January 15, 1979
W.O. %A18730
Grid %2737
J'.C. Foster & Mike Stevens
1205 W. 75th Avenue
· Anchorage, AK 99502
· Subject: Subsurface Investigation, Tract D
Heritage Hills, Huffman & Birch Area
Gentlemen:
Transmitted herein are the results of the subject investiga-
.tion. Included with the transmittal are the following:
Vicintiy Map
Test Hole Location Sketch
Test Hole Logs
Standard Explanatory Information
Grain Size Distribution Curves
Figure 1
Figure 2
Table A
Sheets 1-3
Sheets 4-6
The investigation was conducted December 14 through the
20th, 1978, and consisted of eight test holes. A Nodwell
mounted Mobile Drill B-50 rig equipped with a solid flight
auger was used to advance the holes. The drilling equipment'
is owned and operated by Denali Drilling, Inc. Drill%ng. was~.,
supervised and test holes logged by Mr. T.L; Barber,: 0.M.
Hatch, and James D. Mack from the Alaska Testlab staff. As
the test holes were advanced, soils types were logged and
the soils visually classified. Samples of the soil recovered
from the auger flights were sealed in plastic bags to protect
the natural moisture content. In the laboratory, the moisture
content and dry strength of each sample was determined.
Samples of similar color, texture, and particle size distribu-
tion were grouped together and given an arbitrary group
designations. Grain size analysis were then performed on
composite'samples of important groups rather than on individual
samples. The various groups are listed below by group for
reference to test holes. ..
Group A
Group B
is a brown Gravelly Sandy Silt to Silty Gravelly
Sand. This ~roup is highly frost susceptible,
rated ~3.t6 F-4. Unified classification is SM.
Grain $.i~e distribution is shown on Sheet 4.
Group A contains eleven samples.
is a brown Sandy. Silt. It is highly frost susceptible,
rated F-4. Unified classification is ML. Grain
S 50 6 4 ?
J.C. Foster & Mike Stevens
January 15, 1979
Page 2
size distribution is shown on Sheet 5. Group B
contains fourteen samples.
Group C
is a brown Silty Gravelly Sand. This group is
frost susceptibl~, rated F---2~ Unified classification
is SM. Grain size distribution is shown on Sheet 6.
Group C contains five samples.
Grgup D
is a brown' Silty Sandy Gravel. Frost classification
is F-1. Unified classification is GM. Group D
contains one sample.
When drilling was completed, a slotted PVC pipe was inserted
in each hole to keep the hole open in case of caving and to
aid in measuring the free water level. For the percolation
test, the hole was filled with water and left over night to
saturated. On returning the next ~ay, the hole was refilled
with water and the water level was then monitored carefully
for the next 60 minutes. The.percolation rate reported is
'the minimum rate observed during the .60 minute period.
Using the above tests, percolation rates were as follows:
Test Hole #
Percolation Rate
1
2
5
7
2.8 minutes/inch
3.2 minutes/inch
4.2 minutes/inch
5.0 minutes/inch
The soil where the percolation tests were run appears to be
more permeable than we would normally expect the soils of
this gradation. Therefore, we recommend that more conserva-
tive values be used for design for on-site wastewater disposal
systems. This is because fine grained soils such as these
sometimes'tend to clog with time when used for wastewater
disposal. We believe 150 s.f./bedroom would be a reasonable
design loading for wastewater disposal systems. This value
should be modified in the field if inspection of the seepage
trench walls reveal conditions substantially different
(better or worse) than these expected.
The general soil types encountered are quite uniform between
test holes. Thus, we.feel the percolation rates observed
are representative for. the soil in its native condition.
No free ground water was observed in any of the test holes.
The reader should be cautioned, .however, that ground'water
levels may not have been at a seasonal high during the time
of testing. The depth to'ground water may be shallower at
certain ~imes of year.
J.C. Foster & Mike Stevens
January 15, 1979
Page 3
It is trusted that the above meets your present requirements.
If you have any questions or 'if we may be of furtSer assistance,
please do not hesitate to contact us.
Very sincerely,
ALASKA TESTLAB
R. Mark Hansen
RMH:rb
Enclosures
APPROVED
Melvin R. Nichols,' P.E.
Laboratory Manager
(~
WOODS
CAMFI L
HEIGH~
SCHOOLS
OFFICES - FlitS! NATIONAL SAHK OF ANCHOllAOE
MUHtCIPAtlFY OF ANCHOI&OE OFFICES
Test Hole #1
Depth in Feet
From To
0.0' - 2.0'
2.0' - 20.0'
Table A
WO #A18730
Logged By: T.L. Barber
Date: 12-14-78
Soil Description
Brown Peat (Pt), dry, soft.
F-4, brown slightly' Gravelly Sandy Silt
(SM to ML) fine and medium sand fraction,
wet~ stiff to hard, NP, subrounded and
rounded particles to 1", very hard at 6.5'
Bottom of Test Hole:
Frost Line:
Free Water. Level:
20.0'
1.0'
None Observed While Drilling
Sample Depth
1 5.0'
2 10.0'
3 15.0'
4 20.0'
Type of Dry
M~ Sample Strength Group Unified
6.8 G N A SM%
18.5 G L B ML
16.2 G L B ML
13.7 G N A SM
Remarks: 1.
3.
4.
5.
6.
Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
Dry Strength, N=None, L=Low, M=~4edium, 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
Depth in Feet
From To
0.0' - 1.0'
1.0' - 7.0'
7.0' - 12.0'
12.0' - 20.0'
Table A
WO #A18730
Logged By: T.L. Barber
Date: 12-14-78
Soil Description
Browh Peat (Pt), damp to wet, soft.
F-4, brown Gravelly Sandy Silt (ML), damp,
all sand sizes, stiff to hard, NP, sharp to
rounded particles to 1-1,/2"
F-2, brown slightly Silty Sand (SM), fine
and medium sand sizes, wet, medium density.
F-4, brown Gravelly Sandy Silt (ML to.SM),
layered with sand and gravel, all sand sizes,
wet, stiff, NP, sharp and subrounded particles
to 1"
Bottom of Test Hole:
Frost Line:
Free Water Level:
20.0'
1.0'
None Observed While Drilling
sample. Depth
1 5.0'
2 10.0'
3 15.0'
4 20.0'
Type of Dry
M% Sgmple ~trength Group Unified
12.1 G N A SM
11.6 G N C SM
9.8 G N C S~4
11.8 G .L-N C SM
Remarks: 1.
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.
GeneFal Information, see Sheet 1.
Frost and Textural Classification, see Sheet 21
Unified Classification, see Sheet 3.
Test Hole #3
Depth in Feet
From To
0.0' - 1.0'
1.0' - 8.0'
8.0' - 11.0'
11.0' - 20.0'
Table A
WO #A18730
Logged By: T.L. Barber
Date: 12-18-78
Soil Description
Brown Peat (Pt) frozen, soft.
F-4, brown Sandy Silt (ML), trace gravel,
damp, stiff, NP, rounded and subrounded
particles.
F-4, brown Gravelly Sandy Silt (ML to SM),
hard, all sand sizes, sharp and subrounded
particles, NP.
F-4, brown Sandy Silt (ML), with layers of
'Silty Sandy Gravel (GM), fine and medium
sand sizes, damp to wet, hard, NP, sharp
and subrounded particles.
Bottom of Test Hole:
Frost Line:
Free Water Level:
20.0'
1.0~
None Observed While Drilling
Sampl~ Depth
5.0'
2 10.0'
3 15.0'
4 20..0'
Type of Dry
M% Sample Strength Group Unified
4.5 G L-N A SM
1314 G N A SM
11.0 G L-N B ~
14.6 G L B ML
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 ].
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #4
Depth in Feet
From To ·
0.0' - 1.0'
1.0' - 2.0'
2.0' - 7.0'
7.0' - 11.0'
11.0' - 15.0'
15.0' - 20.0'
Bottom of Test Hole:
Frost Line:
Free Water Level:
Table A
WO #A18730
Logged By: O.M. Hatch
Date: 12-19-78
Soil Description
Brow~ Peat (Pt), damp, soft.
F-4, brown Saqdy' Silt (ML), stiff, NP.
F-4., brown Gra3ell¥ Sa.n~ Silt (SM), poorly
graded, all sand sizes, damp, stiff, NP,.
subrounded particles to 3".
F-l, brown very Si~.~y Saq~y Gravel (GM),
poorly graded, occasional oobbles,' all sand
sizes, damp, .medium density, subrounded
particles to 6"
F-4, brown slightly Gravell~ Sandy Si'l.t (SM),
damp, stiff, NP, subrounded particles to 2".
F-4, brown Sandy Silt (ML), with trace gravel,
damp, stiff', NP.
20.0'
1.0'
None Observed While Drilling
Sample DePth
M%
1 5.0' 18.4
2 10.0' 12.9
3 15.0' 13.1
4 20.0' 17.1
Type of
Sample
G
Dry
Strength ' Group Unif±ed
L-N . B
L A
L B
SM
ML
SM
ML
Remarks:
4. Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
2. Dry Strength, N=None, L=Low,' ~4=Medium, H=High.
· 3. Group refers to similar material, this study only.
4. General Information, see Sheet 1.
5. FroSt and Textural Classification, see Sheet 2.
6. Unified Classification, see Sheet 3.
Test Hole #5
p~pth in Feet
From To
0.0' - 1.0'
1.0' - 8.0'
8.0' - 20.0'
Table A
WO #A18730
Logged By: T.L. Barber
Date: 12-18-78
'Soil Description
Browr~ Peat (Pt), damp, soft.
F-4, brown Gravelly Sandy Silt (SM), all
sand sizes, damp, sol% to ~i~ stiff to hard.
below 2', NP, subrounded and rounded particles
to 1"
F-4, brown Sandy Silt (ML), trace gravel, fine
and medium sand sizes, wet, stiff to hard,
NP to P1-.
Bottom of Test Hole:
Frost Line:
Free Water Level:
20.0'
1.0'
None Observed While Drilling
Sample ~epth
1 5.0'
2 10.0'
3 15.0'
4 20.0'
Type of Dry
M% $~mp~e Strength Group Unified
4.6 G N C SM
5.5 G N A SM
15.7 G L B ML
12.9 G L B ML
Remarks: 1.
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
Depth in Feet
From To
0.0' - 1.0'
1.0' - 12.0'
12.0' - 20.0'
Table A
WO #A18730
Logged By: T.L. Barber
Date: 12-18-78
...... Soil Description
Brown Peat (Pt), damp, soft.
F-2 to F-3, brown very Silty Sandy Gravel
(GM), few cobbles, all sand sizes, damp,
medium to high density, sharp and subrounded
particles to 1"
F-4, brown Sandy Silt (ML), trace gravel, fine
and medi'um sa-~sizes, wet, NP to P1-.
Bottom of Test Hole:
Fr'ost Line:
Free Water Level:
20.0'
1.0'
None Observed While Drilling
Sample ~e~t~
1 5.0'
2 10.0'
3 15.0'
4 20.0'
Remarks:
Type of Dry
M~ Sampl9 ~trength Group Unified
7.0 G N C SM
6.1 G N D GM
16.4 G M B MiL
17.2 G ~ B ML
1. Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
2. Dry Strength, N=None, L=Low, M=Medium, H=High.
3. Group refers to similar material, this study .only.
4. General Information, see Sheet 1.
5. Frost and Textural Classification, see Sheet 2.
6. unified Classification, see Sheet 3.
Test Hole ~7
Depth in Feet
From To
0.0' - 1 .0'
1.0' - 2.0'
2.0' - 6.0'
6.0' - 16.0'
Table A
WO #A18730
Logged By: O.~4. Hatch
Date: 12-19-78
Soil Description
Brow~ Peat (Pt), damp, soft.
F-4, brown Sandy Silt (ML), damp, stiff, NP.
F-4, brown Gravelly Sandy Silt (ML), damp,
stiff, NP, subrounded p~-~t~-~s to 2".
F-2 to F-3, .brown very S.il. ty Gravelly Sand
(SM), poorly graded, all sand sizes, damp,
medium density, subrounded particles to 2".
Bottom of Test Hole:
Frost Line:
Free Water Level:
16.0'
1.0'
None Observed While Drilling
Sampl9 Depth
5.0'
10.0'
15.0'
Type of Dry
M% Sample St'rength Group Unified
15.0 G L B ML
9.4 G N A SM
8.4 G N A SM
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 I.
Frost and Textural Classification, see Sheet 2.
Unified Classification, see Sheet 3.
Test Hole #8
Depth in Feet
From To
0.0' - 1.0'
1.0' - 4.0'
4.0' - 14.0'
14.0' - 20.0'
Bottom of Test Hole:
Frost Line:
Free Water Level:
Table A
W0 #A18730
Logged By: J.D. ~{ack'
Date: 12-20-78
''Soil Description
Brown'Peat (Pt) and topsoil.
F-4, brown slightly Gravelly Sandy Silt (SM),
poorly graded, fine sand fraction, damp, stiff
NP to Pi-, subrounded particles to 1"..
F-4, brown slightly Sandy. Silt (ML), fine sand
fraction, damp to wet, Pi±, stiff.
F-4, brown 'Sandy 'Silt (ML), fine sand fraction,
damp, Pi-, s~.--
20.0'
0.5t
None Observed While D~illing
Sample Depth M%
1 5.0' 13.4
2 10.0' 19.3
3 15.0' 19.8
4 20.0' 19.7
Type of
Sample
G
G
'G
Dry
S~rength Group Unified
L A SM
M B ML
M B ML
L B ML
Remarks.:
1. Type of Sample, G=Grab, SP = Standard Penetration,
U = Undisturbed.
2. Dry Strength, N=None, L=Low, M=MediUm, H=High.
3. Group refers to similar material, this study only.
4.- General Information, see Sheet 1.
5. Frost and Textural Classification, see Sheet 2.
6. Unified Classification, see Sheet 3.
Test Hole Lo~l - Description Guide
The soil descriptions shuwu on thc logs are the best estimate of the soil's
chua~terisrics at the rime of field examination and as such do not achieve the
precision of a laboratory testiug procedure. If the-log includes soils samples,
those samples receive an independent textural classification in th~. laboratory
to verify thc 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 ut sampling.
Frost Classification - NFS, Fl, F2. F3, F4, see "Soil Classification
Chart"
Texture of Soil -- An engineering classification of the soils by particle
size and proportion, see "Soil Classification Chart", note the
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:
dry, no or little apparent surface moisture,
damp, moisture forms portion of color, less than plastic limit,
wet, no free water, often soft, if cohesive soil,
saturated, free water may be squeezed out, ifa free draining soil;
da/stent 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 dilatency.)
Density - refers to more-or.less non-cohesive soils, such as sand grav~:l
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
~y-silt groups. Derived from drill action and/or sample data. Very
soft, soft, stiff, very stiff and hard are commonly used terms.
Particle size - The largest particle recovered by the split spoon is
1-3/8", Shelby tube Y', auger flights (minute-man) 2", Auger flights
{B-SO hollow stem) 6"-8", Larger particles are described indirectly by
action of the drilling and are referred to as cobbles, 3" to 8", or
boulders 8"+. Therefore when 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
Glass;fleas;on sheet t~r £u~ther definition. In some cases AASHO and/or
FAA soil classificatious may b~ shown as well as the unified.
Atterber8 Limits - useful for fine grained and other plastic soils.
PIs natural moisture content believed to be less than plastic limit
PI+; natural moisture content believed to be between plastic and liquid'
~'fi~nit s
~_._~i natural moisture co,rent believed to be greater than liquid limit
NP; non-plastic, useful as a modifying description of some silty
~-~t~:rials.
Dilatency - 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 a slightly or non-plastic
silt or a volcanic ash.
Rock flour - finely ground soft that is not plastic but otherwise appears
similar to a clayey silt.
Organic Content - usually described as Peat, PT, sometimes includes
~liscrete particles such as wood, coal, etc. as a modifier to an inorganic
soil. Quanti~y described as; trace, or an estimate of volume, or. ih case
of all organic, - as Peat. This may include tundra, muskeg' and bog
material.
Mock - a modifier used to describe very soft, semi-organic deposits
usually 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 Water Level - The free water level noted during drilling. This is
not necessarily the static water table at the time of drilling or at otber
seasons. Static water table determination in .other than very permeable
soils requires observation wells or piezometer installations, used only in
special cases.
Blow/6" - The number 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,
,,4% - natural moisture content of the soil sample, usually not
~e:tformcd on clean sands or gravels below the water table.
Type of Sample - ·
S__P, refers to 2" split spoon driven into the soil by 140 pound
weight, a disturbed sample,
..,~, thin wall tube, "Shelby" used to obtain undisturbed samples
of fine grained soil, .
C,~ "grab" disturbed sample from auger flights or wall of trench,
.~, cut sample, undisturbed sample from wall of trench.
Dry Stren~gth - a useful indicator of a soil's clayey fraction, N=None,
L=Low, M=Medium, H=High
Grou_~ - The samples are placed into apparently similar groups based
~ color ahd texture and are arbitrarily assigned a group letter. Further
disturbed tests including Atterberg Limits, grain size, moisture<lensity
relatiohship, etc. may be performed on the group and are assumed to
reflect the general distrubed characteristics of thc 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
!
.3o% GRAVEL
CLAY
CLAYEY
CLAYEY :CLAYEY
\ .
SILTY
SILTY ~ ~
SAND GRAVELLY S'AND iSANDY~ GRAVEL
\ , \
SAND GRAVELLY SAND 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. EXCE?T VARVED CLAYS,
F4 a. ALL SILTS INCLUDING SANDY SILTS.
b. FINE SILTY SANDS CONTAINING MORE THAN 15% FINER THAN 0.02 mm,
c. LEAN CLAYS WITH PLASTICITY INDEXES OF LESS THAN 12,
d, VARVED CLAYS.
~d
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