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Testlab
Alaska ':'
· 40~0 "B" Slreel 'Ar, chorage, Alaska 99503 Phone (907) 278-1551 ( Telecopler (907) 272-5742
Apr±l 17~ 1981
WoO. #A19708
Second and Fourth Anchorage
Limited Partnership
4611 Business Park Blvd..
Anchorage, Alaska 99503
Attention: Mr. Les Pace
Re: Subsurface investigation for Suitability of On-Site Sewage
Disposal,~Lot 4, Block 1;~Lot 2, Block 2; Lot 3, Block 2;
Lot 8, Block 2; Lot 9, Block 2; Lot 10, Block 2; Lot 17,
Block 2; Lot 19, Block 2; Lot 26, Block 2; Lot 3, Block 4;
~ot 4, Block 4; Lot 6, 'Block 4; ~ot 12, Block 4; LOt 13,
Block 4; Lot 14, Block 4, G~eenbrook Subdivision'
Dear Mr. Pace:
During March and April of 1981, we drilled a 15 foot boring on
each of the above lots and placed a perforated, 3/4 inch PVC pipe
in each hole so that the water table could be monitored over a
period of time and a percolation test run in the hole. The holes
were drilled using a Nodwell.mounted, Mobile B50 drill rig owned
and operated by Denali Drilling, Inc. The drilling was supervised
and the test holes logged by Mr. Ted Krupka, senior technician,
and Mr. O.M. ~atch, geologist with Alaska Testlab.
After the holes were drilled, our technician returned on several
occasions and checked the water level in each of the test holes.
After a period of time the holes were saturated, left to stand
overnight, saturated again and a percolation test run. The
percolation test was run by monitoring the'drop in the water
table elevation at 10 minute intervals for a minimum of one hour.
The percolation rate listed in this report was computed using the
slowest 20 minutes of that percolation test.
'Included with this report is a'test hole location sketch for each
lot an~ a log of the b0ri'ng placed on each lot.
The results of this exploration are described as follows:
Lot 4, Block 1
The water table elevation measured in the test hole at this site
remained fairly constant at about 12 feet. The percolation rate
measured on April 15 was 6.0 minute~/inch. Because of the need
to keep. the system shallow and %he high silt content, we recommend
a more conserw~tive design p~rcolation rate of 10.0 minutes/inch.
Second and Fourth Anchorage
Limited Partnership
April 17, 1981
Page Two
We recommend 'the sewage system be placed as high as possible, in
the upper 4 to 8 feet, to avoid high water problems during the
spring breakup.
Lot 2, Block 2
The test hole was placed in-the front of the lot, and this is
where we would recommend the on-site sewage disposal system be
placed. The lot slopes considerably to the back,' where it appears
there may be a high water table. The water table in the test
hole was observed at 8.0 feet on March 18, during the peak of
breakup then lowered to 10.5 feet by April 9. The percolation
rate measured on April 15 was 4.0 minutes/inch. However, we
recommend using a more conservative percolation rate of 10.0
minutes/inch, due to the silt content of the soils. We also
recommend that the disposal system be kept as'shallow as. possible.
It may require mounding to provide adequate insulation and yet
maintain the necessary separation between the system and the
ground water level during spring-runoff.
Lot 3, Block 2
The disposal system on this lot should also be located at the
front of the lot, near the test hole, as this lot slopes downward
to the back. The water level in the test hole was measured at
1].6 feet on April 18, but had measured at 8.1 feet on March 9.
The water level was encountered at 11.4 feet on March 15, and the
percolation rate on this date was 12.5 minutes/inch. We recommend
a mounded .sewage disposal system be used to maintain the necessary
separation from the seasonal high water level, and adequate
insulation of the system.
' 8, Block 2 ~
When drilling the test hole, no water was observed within the 16
foot depth hole at this site° The following day, April 9, water
was observed at 7.6 feet. The water level in the test hole was
8.2 'feet on April 15. This water is probably surface seepage
from thawing conditions. The percolation rate was measured at
5.5 minutes/inch, however, we recor~end a design rate of 10o0
minutes/inch because of the silt content. A mounded sewage
disposal system due to the high spring water level, should be
used.
No water was obse~'ved in the test hole while drilling, but was
found at 7.8 feet the next day, April 9. The water is probably
surface seepage from thawing conditions. The measured percolation
ALASKA '[ES'IFI. AB
Second and Fourth Anchorage
Limited Partnership
· April 17, 1981
Page Three
rate was 5.2 minutes/inch, however, we recommend a design rate of
10.0 minutes/inch. Since the seasonal.water level is quite high,
we recommend a mounded disposal system so sufficient separation
is achieved.
Lot 10, Block 2
The test hole was located in the southwest corner of the lot, and
we recommend that ~the sewage disposal system be,placed in this
area. The water level is quite near the surface towards the
front of the lot. The water level while drilling on April 8 was
9°0 feet, then was found at about 12 feet over the next few days.
On April 14, the percolation rate was measured at 2.5 minutes/inch.
We recommend that a more conservative rate of 10 0 minutes/inch
be used, due to the silty nature of the upper soils° The system
should, be placed as high as possible, in the upper 8 to ~0 feet,
to avoid conflicts with the seasonal high water, mounding may be
necessary for insulation.
Lot 17, Block 2
No ground water was encountered while drilling on this lot on
April 8, or when checked again April 9 and April 16. The measured
percolation rate was 5.4 minutes/inch, however, we recormmend a
more conservative design rate of 10.0 minutes/inch because of the
siltier nature of the soils.
Lot 19, Block
No water table was observed in the 16 foot test hole while drilling
on April 8, or on April 9. The percolation rate was measured at
8.9 minutes/inch, however, we recommend a more conservative
design rate of 10.0 minutes/inch because of the silty nature-of
the soils. The system should be placed as high as possible~ as
high seasonal water levels were found in the immediate area.
Lot 26, Block 2
The test hole was drilled nea.r the center of the lo't April 8, and
no water was observed. The test hole was als0 found dry April 9.
The measured percolation rate was 6.2 minutes/inch.
~~ was observed-in the test hole at this site while drilling
· on April 8, but was at 12.5 feet the following day. The measured
percolation rate was 14.6 minutes/inch. .The disposal system
should be kept as high as possible to avoid conflicts with the
Second and Fourth Anchorage
Limited Partnership
'April 17, 1981
Page Four
seasonal high water.
Lot 4, Block 4
The measured water level in the test hole at this si%e r~mained
fairly constant and high. Saturated conditions were encountered
at 12 feet while drilling on March 14. The water table elevation
was found at 6.8 feet on March 23, at 6.8 feet on April 9, and at
8.'3 feet on March 16. The measured percolation rate was 40
minutes/inch° Because of the high ground water, a shallow mounded
disposal system should be used.
Lot 6, Block 4
The high water level at this site necessitates a highly mounded
system; or using insulation to provide frost protection while
maintaining the necessary separation between the disposal system
and the seasonal high water. While drilling, saturated conditions
were encountered at 13 feet. On'April 18, the water level was
measured at 5.4 feet, then at 5.1 feet on April 23, the water
level had lowered to seven feet by April 9, and then to 7.5 feet
on April 15. However, much of this water is probably from surface
water and melting seasonal frost. The measured percolation rate
was 3.8 minutes/inch, however, we recommend a more conservative
design value of 10.'0 minutes/inch.
Lot 12, Block 4
Again, the disposal system should be placed as high as possible
at this site. The water level in the test hole remained fairly
constant at eight feet. The water level was measured at 2.8 feet
on March 8, but it appeared that ~his high level was caused by
infiltration of surface water, and was not the true water level
at the time. The measured percolation rate on March 17 was 3.4
minutes/inch, but it is recommended the more conservative value
of 10.0 minutes/inc~ be used, because of the high silt con%en% of
the.upper soils.
Lot 13, Block 4
The test hole was drilled near the center of the lot on April 7,
and no water was observed. Again on APril 9, no water was detected.
On April 15, the measured percolation was 9.0 minutes/inch. We
recommend the disposal system be placed between 5 and 11 feet, to
avoid the surface silts.
Lot 14, Block 4
No water wa's encountered while dril'ling, on April 7, or when ,
ALASKA lES 1-LAB
Second and Fourth Anchorage
Limited Partnership
April 17, 1981
Page Five
checked April 9. The measured percolation rate was 4.0 minutes/inch.
We recommend a more conservative rate of 10.0 minutes/inch be
used, since the upper soil is silt.
If you have any questions regarding these tests, please feel free
to call.
Very truly yours,
ALASKA TESTLAB
carl A. Bassle~
Geotechnical Engineer
Approved.by:
CAB/mg
Attachments
cc:
Manager
Ralph~ Westover, Tryck, Nyman & Hayes
Z
9
.." 00'£0~
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Lot 4', Block
Table A
WO #A19708
Date: 3/14/81
Logged by: T~ Krupka
Depth in Feet
From To
0.0 -. 0.5
0.5 7.0
7.0 15.0
Soil Description
Peat
F-3, Brown ~ Sand, SMt silt to 40%, moist
F-2/F-3, Brown Silty. Sand, SM, silt to 25%,
saturated below 12' ~
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation.
aerc Rate = 6.0 minutes/inch.
Recommended Design Perc Rate = 10.0 minutes/inch
Bottom of Test Hole:
Frost Line:
Free Water Level:
15.0 Feet
1.0 Foot
3/14/81 - 12.0 Feet
3/18/81 - 11.9 Feet
4/9/81 - 12o5 Feet
4/14/81 ~ 1.2.0 Feet
H86o24'
/5 ' 5
7
6
.30 .
~o
LOt 2, Block 2
Table B
WO #A19708
Date: 3/14/81
Logged by: T. Krupka
D_~pth in Feet
From To
0.0 - 0.5
0.5 15.0
Soil Description
Peat
F-3, Brown Silt~ Sand, SM, with 10% rounded
gravel, well graded sand, 40% silt, plastic,
moist, firm, occasional cobbles below 10',
saturated at 15'
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation.
,Perc Rate = 4.0 minutes/inc~.
Recommended Design Perc Rate = 10.0 minutes/inch
Bottom of Test Hole:
Frost Line:
Free Water Level:
15.0 Feet
3.0 Feet
3/14/81 - 15.0 Feet
3/18/81 - 8.0 Feet
3/23/81 - 8.9 Feet
4/9/81 - 30.5 Feet
4/15/81 - 9.0 Feet
Lot 3, Block 2
Depth in Feet
From TO
0.0 0.5
0.5 12.0
12.0 15.0
Table C
WO ~A19708
Date: 3/14/81
Logged by: T. Krupka
Soil Description
Peat
F-3, Brown Silt~ pand, SM, 10% rounded gravel
to 3/4", silt to 30%, moistt firm
F-2/F-3, grey Silt~ pand, SM, silt to 20%,
saturated,.firm
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation.
Perc Rate = 12.5 minutes/inch
Bottom of Test Hole:
Frost Line:
Free Water Level:
15.0 Feet
2.5 Feet
3/14/81 - None Observed
3/18/81 - 11.6 Feet
3/23/81 - 10.4 Feet
4/9/81 - 8.1 Feet
4/15/81 - 11.4 Feet
14,
Lot 17, Block 2
Table D
WO #A19708
Date: 4/8/81
Logged by: O. Hatch
Depth in Feet
From To
0.0 1 .0
I .0 2.0
2.0 16.0
Soil Description
Brown Peat, Pt
F-4, Brown Silt, ML, moist, stiff, N~
F-4, Brown Gravell~ San~ Silt, ML,.moist,
stiff, NP, 3" maximum
Set 3/4"'perforated PVC pipe to run perc test
and to monitor water table elevation.
Percolation Rate = 5.4 minutes/inch.
Recommended Design Perc Rate = 10.0 minutes/inch.
Bottom of Test. Hole:
F~ost Line:
Free Water Level:
16.0 Feet
1.0 Foot
4/8/81 - None Observed
4/9/81 - None Observed
4/16/81 - None Observed
Lot 10, Block 2
Table H
WO #A19708
Date: 4/8/81
Logged by: O. Hatch
Depth in Feet
From To
0.0 1 .0
1.0 2.0
2.0 12.0
12.0 15.0
Soil Description
Brown Peat
F-4, Brown Silt, ~L, stiff, moist, ~P
F-4, Brown Gravelly Sandy. Silt, ML, moist
to saturated, stiff, 3" maximum, NP
F-2/F-4, Silt~ ~and, SM~ saturated, stiff, NP
Set 3/4" perforated PVC pipe to run per¢ test
and to monitor water table elevation.
Measured Perc Rate = 2,5 minutes/inch.
Recommended Design Perc Rate = 10.0 minutes/inch.
Bottom of Test Hole:
Frost Line:
Free Water Level~
15.0 Feet
1.5 Feet
4//8/81 -
9/81
~_4~14/81
9.0. Feet
12.0 Feet
11.7 Feet
Lot ~9, Block 2
pepth in Feet
From To
0.0 1 o0
I .0 2.0
2.0 13.0
13.0 16.0
Table E
WO #A19708
Date: 4/18/81
Logged by: O. Hatch
Soil Description
Brown Peat
F-4, Brown Sand~ Silt, ML, moist, stiff, NP
F-2, Brown ~ilty Gravelly Sand,.SM, moist,
medium dense, 3" maximum
F-4, Brown Gravelly Sandy Silt, ML, moist,
stiff, 2" maximum, NP
Set 3/4" perforated PVC pipe to run perc test
~and to monitor water table .elevation.
Perc Rate = 8.9 minutes/inch.
Recommended Design Perc Rate = 10.0 minutes/inch.
Bottom of Test Hole:
Frost Line:
Free Water Level~
16.0 Feet
1o0 Foot
4/8/81 - None Observed
4/9/81 - None Observed
Lot 26, Block 2
Table I
WO #A19708
Date: 4/8/81
Logged by: O. Hatch
D__e~th in Feet
From To
0.0 1 .0
1 .0 8.0
8.0 11 .0
11.0 16.0
Soil Description
Brown Peat
F-2/F-4, Brown Gravell~ Si!tJ~ Sand, 'SM, occasional
cobbles, moist, medium dense
NFS/F-2, Brown pravelly. Sand, SP, trace silt,
moist, medium dense, 3" maximum
F-l, Brown Sil~ Sand~ Gravel, GM, occasional
cobbles, moist, medium dense
Set 3/4" perforated PVC pipe to'run perc test
and to monitor water table elevation.
Perc Rate = 6.2 minutes/inch.
Bottom of Test HolD:
Frost Line:
Free Water Level
16.0 Feet
1.5 Feet
4/8/81 - None Observed
4/9/81 -None Observed
Lot 3, Blbck 4
Depth in Feet
From To
0.0 1 .0
1 .0 2.0
2.0 7.0
7.0 16.0
Table J
WO ~.A19708
Date: 4/8/81
Logged by: O. Hatch
Soil Description
Brown Peat
F-4, Brown Sand~ Silt, ML, moist, stiff, NP
F-l, Brown Silty '~andy Gravel, GM, moist,
medium dense, poorly graded, 3" maximum
F-4, Brown Sand~ Silt, ML, trace gravel, moist,
stiff, NP
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation.
perc Rate = 14.6 minutes/inch.
Bottom of Test Hole:
Frost Line:
Free Water Level:
16.0 Feet
1.5 Feet
4/8/81 - None Observed
4/9/81 - 12.5 Feet
Lot 4, Block 4
D~epth in Feet
From To
0.0 0.5
O.5 6.0
6.0 15.0
Table K
WO ~A19708
Date: 3/14/81
Logged by: T. Krupka
Soil Description
Peat
F-4, Brown S_il.~ Sand, SM, moist, firm
F-3, GrRvell~ Sil__~_~ Sand, SM, occasional
cobbles, moist, firm, becomes saturated at
12'
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation°
Perc Rate = 40 minutes/inch.
Bottom of Test'Hole:
Frost Line:
Free Water Level:
15.0 Feet
1.0 Foot
3/14/81 - 12.0 Feet
3/18/81 - 6.0 Feet
3/23/81 - 6.8 Feet~
4/9/8't - 7.0 Feet
4/16/81 - 8.3 Feet
Lot 6, Black 4
Depth in Feet
From To
0.0 15.0
Table L
WO #A19708'
Date: 3/14/81
Logged by: T. Krupka
Soil Description
F-3, Brown Silty. Gravell~ Sand, SM, well graded,
particles rounded to 3/4", moist, firm, becomes
saturated at 13'
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation.
Perc Rate = 3.8 minutes/inch.
Recommended Design Perc Rate = 10.0 minutes/inch.
Bottom of Test Hole:
Frost Line:
Free Water Level:
15.0 Feet
2.5 Feet
3/16/81 - 13.0 Feet
3/18/81 - 5.4 Feet
3/23/81 - 5.1 Feet
4/9/81 - 7.0 Feet
4/15/81 - 7.5 Feet
Lot 12, Block 4
Depth in Feet
FrOm To
0.0 7.5
7.5 15.0
Table M
WO #A19708
Date: 4/14/81
Logged by: T. Krupka
Soil Description
F-4, Brown S__ilty Sand, SM, silt to 40%, firm,
moist
F-3, Brown Gravel~.~ Silty Sand, SM, occasional
cobbles, firm, moist, becomes saturated at 15'
Set 3/4" perforated PVC'pipe to run perc test
and to monitor water table elevation.
Measured Perc Rate = 3.4 minutes/inch.
Recommended Desing Perc RAte = 10.0 minutes/inch.
Bottom of Test' Hole:
Frost Line:
Free Water Level:~
15.0 Feet
1.0 Foot
3/14/81 - 15.0 Feet
3/18/81 - 2.8 Feet
(Apparently from surface'
water intrusion)
3/23/81 -
4/09/81 -
4/16/S -
7.8 Feet
7.~ 8 Feet
8.5 Feet
Lot 13, Block 4
Table N
WO #A19708
Date: 4/8/81
Logged by: O. H~ch
Depth in Feet
From To
0.0 1 .0
1.0 2.0
2.'0 8.5
8.5 11 .0
11.0 16.0
Soil Description
Brown Peat
F-4, Brown Silt, ML, moist, ~stiff, NP
F-4, Brown Gravelly San~ Silt, ML moist,
stiff, 6" maximum, NP
F-2, Brown Silt~ Gravell~ Sand, SM, moist,
medium dense, poorly graded, 2" maximum
F-4, Brown Gravellz Sand~ Cla~ Sil~, ML,
moist, stiff, 2" maximum, PL- to NP
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation.
Perc Rate = 9.0 minutes/inch. System should
be placed between 5.0 Feet and 11.0 Feet.
Bottom of Test Hole:
Frost Line:
Free Water Level:
16.0 Feet
1.5 Feet
4/7/81 -'None Observed
4/9/81 - None Observed
Lot 14, Block 4
Table O
WO #A1970'8.
Date: 4/8/81
Logged by: O. Hatch
p~pth in Feet
FrOm To
0.0 1 .0
1.0 11.0
11.0 16.0
Soil Description
Brown Peat
F-4, Brown Gravelly Sand~ Silt, ML, .moistf
stiff, occasional cobbles, NP
NFS/F-2, Brown Gravelly Sand, SP, trace silt,
moist, medium dense, 2" maximum
Set 3/4" perforated PVC pipe to run perc test
and to monitor water table elevation.
Measured Perc Rate = 4.0 minutes/inch.
Recommended Design Perc Rate = 10.0 minutes/inch.
Bottom of Test Hole:
Frost Line:
Free Water Level:
16.0 Feet
1.5 Feet
4/7/81 - None Observed
4/9/81 - None Observed.
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