HomeMy WebLinkAboutUNITED STATES POSTAL SERVICE ASPEN STATON - 34 91 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT9
structure. Due to the topography of the site, it is anticipated that
extensive filling will be required below the proposed building. Proposed
grades were not available at the time of our investigation.
Site Grading, Excavation and Utilities
Specifications pertaining to site grading are included below and in
Appendix C of this report. It is recommended that the upper six (6)
inches of existing topsoil and fill and natural subsoils penetrated by root
growth and organic matter below building, filled and paved areas be
stripped and stockpiled for reuse in planted areas or wasted from the
site. The upper six (6) inches of the underlying subgrade below
building, paved and filled areas should be scarified and recompacted
between optimum moisture and two percent (2%) wet of optimum moisture
to a minimum of ninety-five percent (95%) of Standard Proctor Density
ASTM D 698-78. (See Appendix C.) Fill should consist of the on -site
natural soils and siltstone and sandstone bedrock, existing fill or
imported granular material approved by the geotechnical engineer.
Claystone bedrock material encountered at the site should not be used
as . fill below the proposed building or as backfill adjacent to the
building. In addition, it is recommended that a minimum of three (3)
feet of select granular fill be placed below the proposed building. The
granular structural fill should be approved by the geotechnical engineer
and have one hundred percent (100%) passing the four (4) inch sieve, a
maximum of twenty percent (20%) passing the #200 sieve, a. liquid limit
less thag 35 and a plasticity index between 3 and 15. Fill should be
placed in uniform six (6) to eight (8) inch lifts and mechanically
compacted between optimum moisture and two percent (2%) wet of
optimum moisture to at least ninety-five percent (95%) of Standard
Proctor Density ASTM D 698-78.
Heavy-duty construction equipment equivalent to a D-8 tractor and
ripper and/or large track mounted backhoe having a gross weight of
90,000 pounds may be needed to excavate the firm bedrock. Bedrock
used as fill should be broken into pieces less than six (6) inches in
diameter. Proper placement of the bedrock as fill may be difficult, and
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a disc or other mixing equipment may be needed to obtain uniform
moisture and proper compaction. It is suggested that the bedrock be
used in open and planted areas or in the lower portion of fill below
paved areas.
In computing earthwork quantities, an estimated shrinkage factor
of eighteen percent (18%) to twenty-three percent (23%) may be used for
the on -site clays compacted to the above -recommended density. A
shrinkage factor of fifteen percent (15%) to twenty percent (20%) may be
used for the on -site siltstone-sandstone bedrock used as compacted fill,
and a shrinkage factor of ten percent (10%) to fifteen percent (15%) is
anticipated for the imported granular pit run material compacted to the
required density.
All excavations should be dug on safe and stable slopes. The slope
of the sides of the excavations should comply with local codes or OSHA
regulations. Where this is not practical, sheeting, shoring and/or j
bracing of the excavation will be required. The sheeting, shoring and
bracing of the excavation should be done to prevent sliding or caving of
the excavation walls and to protect construction workers and adjacent
structures. The side slopes of the excavation or sheeting, shoring or ,
bracing should be maintained under safe conditions until completion of
backfilling. In addition, heavy construction equipment should be kept a
safe distance from the edge of the excavation.
All piping should be adequately bedded for proper load distribution. i
Backfill placed in utility trenches in open and planted areas should be
compacted in uniform lifts at optimum moisture to at least ninety percent
'(90%)- ofpStandard Proctor -Density ASTM D 698=78—the—full—depth—of—the
trench. The upper four (4) feet of backfill placed in utility trenches
under building and paved areas should be compacted at or near optimum
moisture to at least ninety-five percent (95%) of Standard Proctor
Density ASTM D 698-78, and the lower portion of these trenches should
be compacted to at least ninety percent (90%) of Standard Proctor
Density ASTM D 698-78. Addition of moisture to and/or drying of the
subsoils may be needed for proper compaction. Proper placement of the
bedrock as backfill may be difficult.
Stripping, grubbing, subgrade preparation, and fill and backfill
placement should be accomplished under continuous observation of the
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geotechnical engineer. Field density tests should be taken daily in the
compacted subgrade, fill, and backfill under the direction of the
geotechnical engineer.
Laboratory resistivity tests, pH, oxidation-reduction potential and
sulfide tests performed in the laboratory indicate that the subsoils at
the site are slightly corrosive, and protection of metal utility pipe, in
our opinion, is recommended. Our experience in this area indicates that
there is no evidence that deleterious substances exist in the soils at the
site that would effect the proposed utilities or foundation of the
proposed structure.
Foundation
In view of the loads transmitted by this type of structure and the
soil conditions encountered at the site, it is recommended that the
structure be supported by a drilled -pier foundation system. Using this
type of foundation system, the structure is supported by piers drilled
into the bedrock stratum and structural grade beams spanning the
piers. Piers should be straight -shaft and should be drilled within
plumb tolerances of one and one-half percent (1-1/2%) relative to the
length of the pier. The piers are supported by the bedrock stratum
partially through end bearing and partially through skin friction. It is
recommended that all piers have minimum ten (10) foot lengths and that
they be drilled a minimum of three (3) feet into the firm bedrock
stratum. Piers founded at the above level may be designed for a
maximum allowable end bearing pressure of thirty thousand (30,000)
pounds per square foot. It is estimated that a skin friction of three
thousand (3000) pounds per square foot will be developed for that
portion of the pier embedded into the firm bedrock stratum. To
counteract swelling pressures which will develop if the subsoils become
wetted, all piers should be designed for a minimum dead load of five
thousand (5000) pounds per square foot. Where this minimum dead load
requirement cannot be satisfied, it is recommended that skin friction
from additional embedment into the firm bedrock be used to resist uplift.
To help provide the required skin friction, the sides of the pier drilled
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into the bedrock stratum should be roughened. All piers should be
reinforced their full length to resist tensile stresses created by swelling
pressures acting on the pier. It is recommended that all grade beams
have a minimum four (4) inch void between the bottom of the beam and
the soil below. The predicted settlement under the above maximum j
loading should be negligible.
Drilled piers should be designed to resist all induced lateral forces.
The ultimate passive resistance of the upper overburden materials may
be computed using the equation Pp = 20OZ + 4000 pounds per square
foot, where Z is the depth below the top of the stratum. It is
recommended that a safety factor of 3 be used in conjunction with the
above equation. Where bedrock is encountered below ground water,
temporary casing of the drill holes may be required. For ease of
construction and inspection, it suggested that all piers should have
minimum eighteen (18) inch diameters.
It is strongly recommended that the geotechnical engineer be
present during the drilling operations to (1) identify the firm bedrock
stratum, (2) assure that proper penetration is obtained into the sound
bedrock stratum, (3) ascertain that all drill holes are thoroughly
roughened, cleaned and dewatered prior to placement of any foundation
concrete, (4) check all drill holes to assure that they are plumb and of
the proper diameter, and (5) ensure proper placement of concrete and
reinforcement.
A feasible foundation alternate for lightly loaded portions of the
structure outside the main structural system would be to support the
--str-ucturio -by conventional -type spread -footings and/or -grade-beams..—A•II
footings and/or grade beams should be founded on the original,
undisturbed soil, undisturbed bedrock or on a structural fill extended to
the undisturbed soil and/or bedrock. All exterior footings should be
placed a minimum of thirty (30) inches below finished grade for, frost
protection. In no case should footings be founded on the existing fill
encountered at the site. The structural fill should be constructed in
accordance with the recommendations discussed in the "Site Grading,
Excavation and Utilities" section. of this report. The structural integrity
of the fill as well as the identification and undisturbed nature of the soil
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should be verified by the geotechnical engineer prior to placement of any
foundation concrete. Footings and/or grade beams founded at the above
levels may be designed for a maximum allowable bearing capacity of three
thousand (3000) pounds per square foot (dead load plus maximum live
load). To counteract swelling pressures which will develop if the
subsoils become wetted, all footings and/or grade beams should be
designed for a minimum dead load of one thousand (1000) pounds per
square foot.
The predicted settlement under the above maximum loading, as
determined by laboratory consolidation tests, should be less than
three -fourths (3/4) inch, generally considered to be within acceptable
tolerances. Passive and active pressures in the upper overburden
materials may be determined using the following equations: Pp .=
20OZ + 4000 pounds per square foot and Pa = 75Z - 2300 pounds per
square foot.
Adjacent Foundation History
Empire Laboratories, Inc. has performed numerous geotechnical
investigations on the surrounding properties. In general, there are no
known foundation or structural problems in adjacent buildings.
However, the subsoils to the northeast in the High Pointe residential
development north of Boardwalk Drive are expansive. Highly expansive
claystone bedrock is located in this area. There has been some slab
heave and movement of walks and concrete pavement in the High Pointe
developriWnt. The commercial development, including a three-story office
building, shopping center and restaurant, located west of the project on
College Avenue has not experienced any structural damage, and the
buildings in this area have been constructed on conventional -type spread
footings or grade beams. There has been some slab movement in the
basement slab of the Harmony Presbyterian Church located to the east of
the project area. This structure is founded on a drilled pier foundation
system, and there is no evidence of any structural damage to the
foundation. The National Car Rental facility located to the southwest of
the project is supported on a footing and/or grade beam foundation
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system. The Pavilion shopping center located adjacent to the car rental
is also founded on conventional footings and/or grade beams. To our
knowledge there is not indication of, structural damage to either of these
structures.
Backfill, Dewatering System and Slabs on Grade
Backfill placed adjacent to the building should consist of the on -site
soils, on -site sands tone-siltstone bedrock which is broken into pieces
I
less than six (6) inches in diameter or imported granular material i
approved by the geotechnical engineer. Expansive claystone bedrock
encountered in the excavations should not be used as backfill adjacent to
I
the proposed structure. The backfill should be mechanically compacted
in uniform six (6) to eight (8) inch lifts to a minimum of ninety-five
percent (95%) of Standard Proctor Density ASTM D 698-78 (see Appendix
C) or eighty percent (80%) of Relative Density ASTM D 4253, D 4254.
Free-standing foundation walls backfilled with the on -site clays or
siltstone-sandstone bedrock may be' designed- using a hydrostatic
pressure distribution and equivalent fluid pressure of fifty-five (55)
pounds per cubic foot per foot depth of backfill. Foundation walls
backfilled with imported granular material may be designed using a
hydrostatic pressure distribution and equivalent fluid pressure of forty
(40) pounds per cubic foot per foot depth of backfill.
Slabs on grade should be placed a minimum of three (3) feet above
the bedrock stratum on a minimum of three (3) feet of select granular
.pit—r_un_,Lnaterial_ as _discussed above.----1.f -for---any--reason—the—slabs—are
placed"withina._three (3) feet of the bedrock, then a complete dewatering
system will bd7required around all portions of the building placed within
three- (3)- feet of the bedrock stratum. The dewatering system should
contain a properly sized; perforated. pipe, underslab gravel, a sump and
pump, and/or other suitable outlet. The perforated pipe should be
placed around all portions of the structure placed within three (3) feet
of the bedrock stratum. All piping in the perimeter trench should be
surrounded by clean, graded gravel from three -fourths (3/4) inch to the
#4 sieve in accordance with ASTM C 33-86, Size No. 67. The gravel
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should extend from at least three (3) inches below the bottom of the
pipe to within eighteen (18) inches of finished subgrade above the pipe,
the full width of the trench. To minimize the cost of gravel backfill, it
is suggested that the excavation be limited to the area necessary for
construction; however, the trench should be a minimum of twelve (12)
inches wide. The top of the gravel backfill adjacent to foundation walls
should be covered with filter fabric to help minimize clogging of the
medium with earth backfill. To minimize the potential for surface water
to enter the system, it is recommended that a clay backfill be placed
over the system and compacted at or near optimum moisture to at least
ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78.
We recommend that the drainage pipe be placed at least one (1 ) foot
below the finished slab elevation and have a minimum grade of one-half
percent (1/2%). All slabs surrounded by perimeter drains should be
underlain by a minimum of eight (8) inches of clean, graded gravel or
crushed rock devoid of fines. The drainage system should empty into a
storm sewer should one adequately sized to accept the anticipated flows
exist at the site, or the water from the drain should empty into a sump
provided in the building area. The sump should be sized for the
anticipated flows. Pump tests should be performed on -site to determine
ground water flows so that drain, pipe, and sump and pump sizes can
be adequately determined. An estimated flow of .0006 cubic feet per
second per linear foot of pipe may be used in the preliminary design of
the proposed drainage system. A minimum of one (1 ) foot of clean,
graded gravel meeting the above specifications should be placed adjacent
to the bWtom and sides of the sump. The sump should be provided with
a pump designed to discharge all flow to the sump. Water from the
sump should be disposed of by suitable means well beyond the foundation
of the building.
Due to the swelling pressures exerted by the materials at subgrade,
it is our opinion that the only positive solution for construction of the
slab where movement will not occur is a structural floor with a void
beneath it. However, the cost of this type of system may be prohibitive.
It is our opinion that, with certain precautions and knowing that some
risk is involved, a floating floor slab may be a reasonable alternative.
If the owner is willing to assume the risk of future slab movement and
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r,
related structural damage, the following recommendations may reduce slab
movement and its adverse effects.
Subgrade below slabs on grade should be prepared in accordance
with the recommendations discussed in the "Site Grading, Excavation and
Utilities" section of this report. If the subgrade below slabs on grade is
allowed to dry below the required moisture, the subgrade should be
rescarified and recompacted to two percent (2%) wet of optimum moisture
to the required density just prior to placement of underslab gravel and
concrete. Slabs on grade should be designed and constructed
structurally independent of bearing members. Slabs exhibiting heavy
floor loads should be underlain by a minimum of six (6) inches of
crushed aggregate base course meeting City of Fort Collins Class 5 or 6
specifications. The base course should be compacted at or wet of
optimum moisture to a minimum of ninety-five percent (95%) of Standard
Proctor Density ASTM D 698-78. Office and lightly loaded slabs should
be underlain by a minimum of four (4) inches of clean, graded gravel or
crushed rock devoid of fines.
To minimize and control shrinkage cracks which may develop in slabs
on grade, we suggest that control joints be placed every fifteen (15) to
twenty (20) feet and that the total area contained within these joints
be no greater than four hundred (400) square feet. In addition, if
building construction is done during winter months, it is recommended
that the slab on grade not be poured until the building has been
enclosed and heat is available within the building area so that
slab -on -grade concrete is not placed on frozen ground. This will also
aid in propercuring of the slab_ concrete.
We further recommend that nonbearing partitions placed on floor
slabs that are placed within three (3) feet of the bedrock stratum be
provided with a minimum one and one-half (1-1/2) inch slip joint (either
top or bottom). Slip joints reduce pressure applied by heaving floor
slabs and thus minimize damage to the portion of the structure above.
It is emphasized that if the subsoils are kept dry, movement of slabs on
grade should be minimal. However, if moisture is permitted to reach the
subsoils below the slabs, heaving will probably occur.
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Parking, Driveway and Loading Areas
Flexible Pavement
It is our opinion that flexible pavement is suitable for the proposed
pavement construction at the site. A flexible pavement alternate should
consist of asphalt concrete underlain by crushed aggregate base course
or asphalt concrete underlain by plant mix bituminous base course. The
design criteria described below was utilized in determining the pavement
thicknesses at the site.
Colorado Department of Highways "Roadway Design Manual" and the
new AASHTO Guide for Design of Pavement Structures dated July
1986
"R" value - 6
Reliability Factor - 70
Serviceability Index - 2
20-Year Design Life
Assumed 18 kip Equivalent Single -Axle Load Application - 5,000 for
parking areas and 10,000 for driveways and truck loading areas
Design Structural Number - 2.48 for parking areas and 2.77 for
driveways and truck loading areas
The following minimum pavement thicknesses are recommended:
Passgnger Car Parking
Asphalt Concrete 311
Crushed Aggregate Base Course loll
Total Pavement Thickness 13"
Asphalt Concrete 211
Plant Mix Bituminous Base Course 5"
Total Pavement Thickness 7"
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Driveways and Truck Loading Areas
Asphalt Concrete 4"
Crushed Aggregate Base Course loll
Total Pavement Thickness 14"
Asphalt Concrete 2"
Plant Mix Bituminous Base Course 51"
Total Pavement Thickness 7111
The crushed aggregate base course should meet City of Fort Collins
Class 5 or 6 specifications. The subgrade below the proposed asphalt j
pavement should be prepared in accordance with the recommendations
discussed in the "Site Grading, Excavation and Utilities" section of this
report. Upon proper preparation of the subgrade, the base course
should be placed and compacted at optimum moisture to at least j
ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78.
(See Appendix C.)
It is recommended that the asphalt concrete and/or plant mix
bituminous base course be placed in two (2) to three (3) inch lifts. All
plant mix bituminous base course and asphalt concrete shall meet City of
Fort Collins specifications and should be placed in accordance with these l
specifications. The crushed aggregate base course shall have an "R"
value between 70 and 77, the plant mix bituminous base course shall
have an Rt value of 90 or greater, and the asphalt concrete shall have
an Rt value of 95 or greater. The "R" value of the pavement materials
_.lused_sh&uld be -verified by laboratory tests. -Field --clens i-ty—tes ts—shou I d—
be taken in the aggregate base course, bituminous base course, and
asphalt concrete under the direction of the geotechnical engineer.
Rigid Pavement
A feasible pavement alternate at the site would be rigid pavement.
Using the eighteen (18) kip equivalent daily load application described
above, a modulus of subgrade reaction of one hundred twenty-five (125)
pounds per square inch per inch based on an "R" value of 6, a design
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REPORT
OF A
GEOTECHNICAL INVESTIGATION
FOR
ASPEN STATION
FORT COLLINS, COLORADO
U. S. POSTAL SERVICE
CHICAGO, ILLINOIS
PROJECT NO. 8558-90
ju
EMPIRE LABORATORIES, INC.
301 NORTH HOWES STREET
FORT COLLINS, COLORADO 80521
rd
life of
twenty (20) years, and
concrete designed
with a modulus of
rupture
of six hundred fifty (650)
pounds per square
inch, the following
minimum
pavement thicknesses are
recommended:
Passenger Car Parking
Nonreinforced Concrete - 5"
Driveways and Truck Loading Areas
Nonreinforced Concrete - 6"
Subgrade below proposed paved areas should be prepared in accordance
with the recommendations discussed in the "Site Grading, Excavation and
Utilities" section of this report. Concrete pavement should be placed
directly on the subgrade that has been uniformly and properly prepared
in accordance with the above recommendations. All concrete used in the
paving shall meet ASTM specifications, and all aggregate shall conform to
ASTM C 33 specifications. The concrete should be designed with a
minimum modulus of rupture of six hundred fifty (650) pounds per
square inch in twenty-eight (28) days. It is recommended that
laboratory mix designs be done to determine the proper proportions of
aggregates, cement, and water necessary to meet these requirements. It
is essential that the concrete have a low water -cement ratio, an adequate
cement factor, and sufficient quantities of entrained air. Joints should
be carefully designed and constructed in accordance with the Colorado
Department of Highways "Roadway Design Manual and the AASHTO Guide
for Design of Pavement Structures to ensure good performance of the
pavement, It is recommended that all concrete pavement be placed in
accordance with the above specifications. If paving is done during cold
weather, acceptable cold weather procedures as outlined in the above
specifications should be utilized. The concrete pavement should be
properly cured and protected in accordance with the above
specifications. Concrete injured by frost should be removed and
replaced. It is recommended that the pavement not be opened to traffic
until a flexural strength of four hundred (400) pounds per square inch
is obtained or a minimum of fourteen (14) days after the concrete has
been placed.
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GENERAL RECOMMENDATIONS
(1) Laboratory test results indicate that water soluble sulfates in
the soil are negligible, and a Type 1-II cement may be used in
concrete exposed to subsoils. Slabs on grade subjected to
de-icing chemicals should be composed of a more durable
concrete with low water -cement ratios and higher air contents.
(2) Finished grade should be sloped away from the structure on all
sides to give positive drainage. Five percent (5%) for the first
ten (10) feet away from the structure is the suggested slope.
(3) Gutters and downspouts should be designed to carry roof
runoff water well beyond the backfill area.
(4) Underground sprinkling systems should be designed such that
piping is placed a minimum of five (5) feet outside the backfill
of the structure. Heads should be designed so that irrigation
water is not sprayed onto the foundation walls. These
recommendations should be taken into account in the landscape
planning.
(5) Plumbing under slabs should be eliminated wherever possible
since plumbing failures are quite frequently the source of free
water which may cause slab heave.
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(6) Pier, footing and/or grade beam sizes should be proportioned to
equalize the unit loads applied to the soil and thus minimize
differential settlements.
(7) It is recommended that compaction requirements in the project
specifications be verified in the field with density tests
performed under the direction of the geotechnical engineer.
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(8) It is recommended that a registered professional structural
engineer design the substructure and that he take into account
the findings and recommendations of this report.
GENERAL COMMENTS
This report has been prepared to aid in the evaluation of the
property and to assist the architect and/or engineer in the design of
this project. In the event that any changes in the design of the
structure or its location are planned, the conclusions and
recommendations contained in this report will not be considered valid
unless said changes are reviewed and conclusions of this report modified
or approved in writing by Empire Laboratories, Inc., the geotechnical
engineer of record.
Every effort was made to provide comprehensive site coverage
through careful locations of the test borings, while keeping the site
investigation economically viable. Variations in soil and ground water
conditions between test borings may be encountered during
construction. In order to permit correlation between the reported
subsurface conditions and the actual conditions encountered during
construction and to aid in carrying out the plans and specifications as
originally contemplated, it is recommended that Empire Laboratories,
Inc. be retained to perform continuous construction review during the
excavation and foundation phases of the work. Empire Laboratories,
Inc. assumes no responsibility for compliance with the recommendations
includedp in this report unless they have been . retained to perform
adequate on -site construction review during the course of construction.
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APPENDIX A.
TEST BORING LOCATION PLAN
uo s
PROPOSED 9u1LGIN4
• � P RKWp.'f
SITE
NORTH
T.B.M.=
N.E. SONNETDOLT
ON r[REHYDRANT
EL: 5030.T
A -?-
EMPIRE LARUNATORIES INC
i
KEY TOBORING LOGS
j�
TOPSOIL
�•�••
GRAVEL
®
FILL
I,', I
SAND & GRAVEL
SILT
r. :
SILTY SAND & GRAVEL
CLAYEY SILT
o
v
COBBLES
SANDY SILT
SAND, GRAVEL & COBBLES
®
CLAY
®
WEATHERED BEDROCK
SILTY CLAY
SILTSTONE BEDROCK
SANDY CLAY
®
CLAYSTONE BEDROCK
F.
SAND
SANDSTONE BEDROCK
�•
SILTY SAND
LIMESTONE
V. CLAYEY SAND
GRANITE
I l R
SANDY SILTY CLAY
❑
' SHELBY TUBE SAMPLE
STANDARD PENETRATION DRIVE SAMPLER
WATER TABLE 24 hrS AFTER DRILLING
C HOLECAVEO
T
5/12 Indicates that 5 blows of a 140 pound hammer falling 30 inches was required to penetrate 12 inches.
•wWw
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®0 1III ®Q.7
c ®�
® ®®
LOG Of SMNGS
ELEVATION: NO.5 N0. b No.7
5030
5025
5020
5015
5010
5005
5000
4995
28
: _:
A
OVA
ML-
-
�=
C=E=WA
®��
y
®�
C=C=
®-Qs-®-W
m-®-®-'V
HMO"®-®
®mmmm
®�
__-'-
- m
A- 5
LOG OF BORINGS
ELEVATION: NOS NO. 10 NO. ti 0.12.
5040
5035
5030
5025
5020
5010
A- 6
cu.e.ae .•v.�•���. e� u�
TEST BORING LOG
BORING 1
CLIENT: U.S Postal Service PROJECT NO.: 8558
PROJECT: Aspen Branch DATE DRILLED: August 13 1990
DEPTH TO WATER (IMMEDIATE): Dry
GROUND ELEVATION: 5032.1 DEPTH TO WATER 1 24 hrs. ): Dry
FIELD ENGINEER: Doug Leafgren
)epth
(feet)
Sample
Type
Penetration
Slows/in.
Classification
Soil Description
M
DID
Qu
LL
PI
GI
1%1
(PCFI
(KSF)
I%)
1%)
0 0'-0 5' Sandy Silty
LjjU - tan, dry to damp
SS
32/12
15.8
ST
0.5-3.5' - Weathered
12.2
Siltstone - Sandstone -
SS
50/10
13.5
tan, damp, fine grained
5
' ' - Firm
Siltstone w/ Sandstone
ST
damp, fine grained,
well cemented at
12.7
97.6
2.8
SS
50/5
25.0 -27.0.
12.8
to
15 SS I 50/5 I I 113.1
a.
SS 1 50/5 T 1 113.2
01 I 25 d SS I 50/3 I I 113.4
30 SS 50/3 12.0
A=1
SS - SPLIT SPOON M - MOISTURE 1%) LL- LIQUID LIMIT 1%)
ST - SHELBY TUBE DD - DRY DENSITY (PCF) PI - PLASTICITY INDEX (%I
77. FINAL WATER LEVEL Qu - COMPRESSIVE STRENGTH (KSFI GI • GROUP INDEX
TABLE OF CONTENTS
Tableof Contents ..............................................
i
Letterof Transmittal ..........................................
Report.........................................................
1
AppendixA ....................................................
A-1
Test Boring Location Plan ....................................
A-2
Keyto Borings ...............................................
A-3
Logof Borings ...............................................
A-4
Descriptive Log of Borings ..................................
A-7
AppendixB....................................................
B -1
Consolidation Test Data ......................................
B-2
H veem Stabilometer Data .....................................
B-6
Summaryof Test Results .....................................
B-7
AppendixC....................................................
C -1
Ar
TEST BORING LOG
BORING 2
CLIENT: U.S Pustal Service PROJECT NO.: 8558
PROJECT: Aspen Branch DATE DRILLED: August 13,1990
DEPTH TO WATER IIMMEDIATEI: Dry
GROUND ELEVATION: 5033.3 DEPTH TO WATER ( 24 hrs. ): Dry
FIELD ENGINEER: Doug Leaf ren
Iepth Sample Penetration Classification M DD Ou LL PI GI
(feet) Type Blows/in. Soil Description I%1 (PCF) (KSF) (%1 1%G)
SS 50/9 A-6(1) Clay- tan, dry to damp 11.9 26.0 12.6 1.2
Sc '- ' - Weathered
Siltstone - Sandstone.
tan, damp, fine grained.
5 SS 50/6 2.0'-30.3' - Firm 11.9
Siltstone w/Sandstone -
damp CaCO3 cemented
lenses at 26.5'-28.0!
10I SS I 50/4 I I 112.3
1I SS 150/5 I I 113.5
-- 1-Ilr - -- - I — - - - -- - -- -- - 114.9
I" I 25 H SS I 50/5 I 1 112.7
30tj SS 1 50/3 1 1 112.1
SS - SPLIT SPOON
S�T7 SHELBY TUBE
X- FINAL WATER LEVEL
A-8
M MOISTURE 10.0
00 DRY DENSITY (PCF)
Ou COMPRESSIVE STRENGTH IKSFI
LL• LIOUID LIMIT 1%)
PI - PLASTICITY INDEX 190
GI - GROUP INDEX
CLIENT: U.S Postal Service
PROJECT: Aspen Branch
GROUND ELEVATION: 5031.6
TEST BORING LOG
BORING 3
PROJECT NO.: 8558
DATE DRILLED: August 13,1990
DEPTH TO WATER (IMMEDIATE): 231-6"
_ DEPTH TO WATER ( 24 hrs. ):
23'-6"
FIELD ENGINEER: DOug Leafgren_
lepth
Iteetl
Sample
Type
Penetration
Blows/in.
Classification
Soil Description
M
I%)
DID
IPCFI
ou
IKSFI
LL
1%1
PI
1%)
GI
0.0'-0.5' - Sandy Silty
SS
40/12
6.5
Clay - tan, dry to damp.
ST
SS
50/4
0.5'-3.0' -Weathered
8.3
8.0
Siltstone - Sandstone -
tan, damp, fine grained
5
_3.0'-30.4' - Firm
Siltstone vil/ Sandstone
damp, fine grained,
SS
50/8
CaCO3 at 25.0'.
14.5
10
15}� SS 'I 50/7 I I I14.4
"I SS 150/9 I 1p I 115.7
a
01 I 25 H SS 150/4 I I 112.4
Son SS 150/5 I I 113.1
A-9
SS - SPLIT SPOON M - MOISTURE
ST - SI4ELBY TUBE DO - DRY DENSITY IPCFI
Q- FINAL WATER LEVEL Qu - COMPRESSIVE STRENGTH IKSFI
LL• LIQUID LIMIT MI
PI PLASTICITY INDEX 1%)
GI - GROUP INDEX
CLIENT: U.S Postal Service
PROJECT: Aspen Branch
GROUND ELEVATION: 5032.7
TEST BORING LOG i
BORING 4
1
PROJECT NO.: 8558
DATE DRILLED: August 13,1990
_ DEPTH TO WATER (IMMEDIATE): Dry
DEPTH TO WATER ( 24 hrs. ): Dry
FIELD ENGINEER: Doug Leafgren
Depth
(foot)
Sample
Typo
Penetration
Blow&/in.
Classification
Soil Description
M
I%)
DD
(PCF)
Ou
(KSF)
LL
1%)
PI
(%)
GI
' ' - Silt
SS
15/12
Topsoil.
15.8
' 5' - Sandy Silty
Clay - brown, dry to
ST
damp.
10.3
5
SS
50/8
1.5'-5.0' - Weathered
11.2
Siltstone - Sandstone -
tan, damp, fine grained112.2
5.0'-30.3' - Firm
to
SS
50/6
Siltstone w/ Sandstone
damp.
is SS 50/6 13.7
SS' 50/6—r' - -- - - - — - 13.1
I 25H SS 150/7 I I 114.9
30tj SS 1 50/3 1 1 1 9.9
II I I I A-10 I 1 1 1 1
SS SPLIT SPOON M - MOISTURE 1%) LL. LIOUID LIMIT (961
S�T7 SHELBY TUBE 00 DRY DENSITY IPCF) PI - PLASTICITY INDEX 1%)
Y- FINAL WATER LEVEL Ou COMPRESSIVE STRENGTH IKSF) GI - GROUP INDEX
TEST BORING LOG
BORING 5
CLIENT: U.S Postal Service PROJECT NO.: 8558
PROJECT: Aspen Branch DATE DRILLED: August 13,1990
DEPTH TO WATER (IMMEDIATE): dry
GROUND ELEVATION: 5029.7 DEPTH TO WATER ( 24 hrs. ): Dry
FIELD ENGINEER: Doug Leafgren
I
)epth
Ifeetl
Sample
Type
Penetration
Blows/in.
Classification
Soil Description
M
I%)
DD
IPCFI
Du
IKSFI
'LL
I%)
PI
I%1
0.0'-1.0' - Fill -
SS
28/12
sandy silty clay, brown,11.7
dry to damp.
ST
1.0'-1.5' - Sandy Silty
11.8
Clay - brown, dry to
damp.
5
SS
50/11
13.4
1.5'-4.5' - Weathered
_Siltstone - Sandstone -
tan, damp, fine grained
4.5'-30.4' - Firm
10
SS
50/7
Siltstone w/ Sandstone
11.5
damp, CaCO3 cemented
lense at 8.0'-9.00.
15P SS 150/7 1 I 115.7
" fl SS 150/6 10 I 115.2
01 I 15 H SS 150/6 I I 115.5
3 N SS 150/5 I I 114.0
I i I I I A-11
SS - SPLIT SPOON M MOISTURE I%1
ST • SHELBY TUBE DO - DRY DENSITY IPCFI
n- FINAL WATER LEVEL Ou COMPRESSIVE STRENGTH IKSFI
LL- LIQUID LIMIT I%1
PI PLASTICITY INDEX (%I
GI GROUP INDEX
GI
TEST BORING LOG
BORING 6
CLIENT: U.S Postal Service PROJECT NO.: 8558
PROJECT: Aspen Branch DATE DRILLED: August 1311990
DEPTH TO WATER IIMMEDIATE): Dry
GROUND ELEVATION: 5028.4 DEPTH TO WATER ( 24 hrs. ): Dry
FIELD ENGINEER: Doug Leafgren
Depth
Sample
Penetration
Classification
Soil Description
M
DID
Du
LL
PI
GI
(feet)
Type
Blow,/in.
(%)
IPCF)
fKSF)
1%)
I%)
0.0'-1.5' - Fill -
SS
12/12
sandy silty clay with
17.5
gravel, brown, dry to
ST
A-7-6(18)damp'
17.8
107.4
10.3
43.0
23.3
17.8
SS
16/12
CL
1.5'-8.5' - Silty Clay-
-
14.1
5
gray, damp.
ST
8.5'-11.0' - Weathered
18.3
108.0
Siltstone - Sandstone
10
SS
18/12
18.2
-
damp, fine grained.
11.0'-30.3t - Firm
Siltstone w/Sandstone-
damp.
15
SS
50/5
13.3
50/5
----
---
13.4
25
SS
50/2
12.8
30
SS
50/4
12.5
A-12
SS • SPLIT SPOON M - MOISTURE 1%I LL- LIOUID LIMIT 1 0l
ST - SHELBY TUBE OD DRY DENSITY (PCF) PI PLASTICITY INDEX (%)
t7- FINAL WATER LEVEL Ou - COMPRESSIVE STRENGTH (KSF) GI - GROUP INDEX
TEST BORING LOG
BORING 71
CLIENT: U•S PDstal Service PROJECT NO.: H558
PROJECT: Aspen Branch DATE DRILLED: August 13,1990
DEPTH TO WATER (IMMEDIATE): Dry
_
GROUND ELEVATION: 502B.0 DEPTH TO WATER ( 24 hrs. ): Dry
FIELD ENGINEER: Doug Leafr1ren
Depth
(feet)
Sample
Type
Penetration
Blows/in.
Classification
Soil Description
M
DID
Du
LL
PI
GI
I%)
IPCFI
IKSFI
1%1
1%I
0.0'-1.0' Fill
SS
29/12
sandy silty clay, brown
13.7
dry to damp.
t t - Sandy
Clay - red -brown, dry
5
SS
44/12
to damp.
14.9
4.5'-9.0' - Weathered
Siltstone - Sandstone -
tan, fine grained.
9.0'-15.5'- Firm
10
SS
50/7
Siltstone - Sandstone -
tan, fine grained.
15
SS
50/6
16.1
20
25
30
A-13
SS - SPLIT SPOON M - MOISTURE 1%) LL- LIOUID LIMIT I?;1
ST - SHELBY TUBE DD - DRY DENSITY IPCF) . PI - PLASTICITY INDEX 19;1
V- FINAL WATER LEVEL ou - COMPRESSIVE STRENGTH (KSF) GI GROUP INDEX
CLIENT: U.S. PUstal Service
PROJECT:Aspen Branch
GROUND ELEVATION: 5029.7
)epth
Sample
Penetration
(feet)
Type
Blows/in.
SS
23/12
5I SS I 18/12
ion{ SS I 11/12
TEST BORING LOG
BORING 8
PROJECT NO.: 8558
DATE DRILLED: August 13,1990
DEPTH TO WATER (IMMEDIATE): Dry
DEPTH TO WATER ( 24 hrs. ): Dry
FIELD ENGINEER: Doug Leafgren
andSoil Description
0.0'-0.5' - Silty
Topsoil.
0.5'-16.0' - Sandy
Silty Clay — reddish —
brown, dry to damp.
75 SS 9/12
Comp site A-6(8)
Sample—
1 1 25
30
SS - SPLIT SPOON
ST-SHELBY TUBE
W FINAL WATER LEVEL
M DD au LL PI GI
1%) (PCF) IKSFI 1%) 1%1
15.0
12.0
22.7
24.0
A-14
M - MOISTURE 1%)
DD - DRY DENSITY IPCFI
Ou - COMPRESSIVE STRENGTH IKSFI
LL- LIQUID LIMIT 1%)
PI - PLASTICITY INDEX 1%)
GI - GRfN)P INnFX
TEST BORING LOG
BORING 9
CLIENT: U.S POstal Service PROJECT NO.: 8558
PROJECT: Aspen Branch DATE DRILLED: August 13,1990
DEPTH TO WATER (IMMEDIATE): Dry
GROUND ELEVATION: 5031.9 DEPTH TO WATER 1 24 hrs. ): Dry
FIELD ENGINEER: DDus Leafgren
Depth
((Bell
Semple
Type
Penetration
Slows/in,
Classification
Soil Description
M
DO
Ou
LL
PI
GI
1%1
IPCFI
IKSFI
1%1
1%1
i t
- Sandy Silty
SS
18/12
11.9
Clay - tan, dry to damp
1.0-5.5' - Weathered
Claystone - Siltston -
tan, fine grained
6
SS
34/12
A-7-6(3)t.5'-
' - Firm
19.4
55.4
26.3
29.6
Claystone - Siltstone-
CH-MH
tan, fine grained.
to
SS
50/9
15.9
is
SS
50/8
16.8
20
25
30
A-15
SS - SPLIT SPOON M MOISTURE 00 LL • LIQUID LIMIT 00
ST • SHELBY TUBE DO DRY DENSITY (PCFI PI PLASTICITY INDEX I%)
V- FINAL WATER LEVEL Qu COMPRESSIVE STHENGTH IKSFI GI GROUP INDEX
CLIENT: U.S Postal Service
PROJECT: Aspen Branch
GROUND ELEVATION: 5031.2
TEST BORING LOG
BORING 10
_ PROJECT NO.:
8558
_ DATE DRILLED:
August 13,1990
_ DEPTH TO WATER (IMMEDIATE): Dry
_ DEPTH TO WATER (
24 hrs. ): Dry
FIELD ENGINEER:
Doug Leafgren
lapth
Ifeet)
Sample
Type
Penetration
Blows/in.
Classification
Soil DescriptionM
I%)
DO
IPCF)
Ou
IKSFI
LL
1%)
PI
I%)
SS
50/12
'-0 ' - SandSilty
8.5
Clay - tan, damp to dry
0.5'-4.0' - Weathered
Siltstone - Sandstone
tan, fine grained.
5
SS
50/5
4.0'-15.5' - Firm
11.4
Siltstone - Sandstone -
tan, fine grained.
"M SS I 50/6 I I 112.1
15 n SS 50/6 1 I 113.8
1 1 25
30
.1 t
SS - SPLIT SPOON
ST - SHELBY TUBE
7- FINAL WATER LEVEL
A-16
M - MOISTURE 11'.)
DO - DRY DENSITY IPCF)
Ou - COMPRESSIVE STRENGTH IKSFI
LL. LIOUID LIMIT 10%)
PI - PLASTICITY INDEX 00
GI GROUP INDEX
GI I
TEST BORING LOG
BORING 11
CLIENT: U.S Postal Service PROJECT NO.: 8558
PROJECT: Aspen Branch DATE DRILLED: August 13,1990
DEPTH TO WATER (IMMEDIATE): Dry
GROUND ELEVATION: 5037.0 DEPTH TO WATER 1 24 hrs. ): Dry
FIELD ENGINEER: Doug Leafgren
Oepth
(feet)
Sample
Type
Penetration
Blows/in.
Classification
Soil Description
M
DD
u
Ou
LL
PI
GI
(%)
IPC F)
IK
I%1
(%.)
0.0'-0.5' Sandy Silty
SS
25/12
14.2
Clay - tan, dry to damp
0.5'-4.0' - Weathered
Claystone - tan, brown,
fine grained.
s
SS
50/9
4.0'-15.5' Firm
16.5
Claystone - brown, fine
grained.
10
SS
50/5
13.5
)s
SS
50/6
13.2
20
ss
30
A-17
SS SPLIT SPOON M MOISTUIiE ('-) LL- LIOUIU LIMIT (70
ST SHEI.UY TUUE DO • DRY DENSITY IPCF) PI PLASI"ICITY INDEX (161
Q• FINAL WATER LEVEL Ou - COMPRESSIVE STRENGTH (KSF) GI - GROUP INDEX
u
OORApr 9
i
Empire Laboratories, Inc.
GEOTECHNICAL ENGINEERING 8 MATERIALS TESTING
August 27, 1990
U. S. Postal Service
Facilities Service Center
222 South Riverside Plaza, Suite 1200
Chicago, Illinois 60606-6150
Attention: Mr. James S. Kinne
Real Estate Specialist
Senior Realty Acquisition Branch
Gentlemen:
CORPORATE OFFICE
P.O. Box 503 • 301 No. Howes
Fort Collins, Colorado 80522
(303) 464.0359
FAX No. (303) 484-C454
We are pleased to submit our Report of a Geotechnical Investigation
prepared for the proposed Aspen Station located on Boardwalk Drive in
south Fort Collins, Colorado.
Based upon our findings in the subsurface, it is our opinion the site is
suitable for the proposed construction, providing the design criteria and
recommendations set forth in this report are met. The accompanying
report presents our findings in the subsurface and our recommendations
based upon these findings.
Very truly yours,
EMPIRE LABORATORIES, INC.
JiR.
-/
Sherrod
Senior Engineering Geologist
�<
Reviewed by:
Af
Chester C. Smith, P.E.
a
President _
4808 >?
_
,Q: •
cic
o,•
ty� y LPN: r:7
011MICf1
P.O. Box 16859 P.O. Box 1135
fie
P.O. Box 1744
Colorado Springs. CO 80935 Longmont. CO 80502
Greeley. CO 80632
(719) 597-21 16 1303) 776.3921
(303) 351-0460
Member of Consulting Engineers Council
P O. Box 5659
Cheyenne, WY 82003
(307) 632-9224
CLIENT: U. S. Postal Service
PROJECT: Aspen Branch
GROUND ELEVATION: 5035.2
lapth Sample Penetration Classification
(feet) Type Blows
SS 50/12
5� SS 1 50/6 k-6(4)
10 � SS 1 50/3
15 LI SS I 50/4
i
25
3
SS SPLIT SPOON
ST SHELBY TUBE
V. FINAL WATER LEVEL
TEST BORING LOG
BORING 12
PROJECT NO.: 8558
DATE DRILLED: August 13,1990
DEPTH TO WATER (IMMEDIATE): _Dry
DEPTH TO WATER ( 24 hrs. ): Dry
FIELD ENGINEER: � Doug Leafgren
Soil Deu:ription M DD ou LL PI
1%I IPCFI IKSFI 1%1 1%1
an i
Clay -tan, dry to damp 9.5
1.01-4.0' - Weathered
Sandstone - Siltstone-
tan, fine grained.
4 0-15 3' - Firm
GI
Sandstone - Siltstone- 12.8 30.7 10.6 I4.0
tan, fine grained.
12.8
12.9
A-18
M MOISTURE 1 0)
OD DRY DENSITY IPCFI
Ou COMPRESSIVE STRENGTH (KSF)
LL. LIQUID LIMIT (90)
PI - PLASTICITY INDEX P01
GI GROUP INDEX
APPENDIX B.
SWELL - CONSOLIDATION TEST PRO. 5558
BOPPIG HQ.: I
DEPTH: 2.@
DF*( EIEH;ITY:1113.9 P,--F
I S T UPE 12.5 %
IT
cl
HII
I
H.1 cl . 25
4 .0
cl
ui
El lT
—2
4 .0
iii
-6 cl
0.5 1.0
APFLIED PPESSURE — TEF
WRTER RDBE0
0.5 1 . 0
FiFFLIED FFE-71SURE — TSF
EtIPIRE LFiB(:)FFIT(--IPIE,-. D-IC
B-2
5
5
le
10
5 4 C
LL
5 00 0 4`
4 P, cl
.440
.420
SWELL - CONSOLIDATION TEST PRO. 8558
4
DEPTH: 4.0
DRY DEr-j-BIT'e:lC'5.L Fr-F
MuISTUPE: 9.* %
ED
io. n 1.0 5
APPLIED PRESSURE — TSF
118TER RDDEO
.2 5 0.5 1.0
APPLIED PRESSURE — TSF
EtIPIRE LABOP19TOPIES INC
B-3
5 10
550
5 10
4,3
Ir
4'
LL
4 571
-
4:�: 0
4 10
cl
1
mm
LLI
4 .0
Ul
-16 .0
L
SWELL - CONSOLIDATION TEST FRO. ::: 5 5:?
i--1
DEPTH: :3 0
DRY DENSIT,(: 111:3. t Pr_F
rl 0 1 S T LIFE q.:?
0.25 0.5 1.0 5
RFPLIED PRESSURE - TSF
:.I I I I I
% WRTER ADDED
0.c5 0.5 1.0 5
APPLIED PRESSURE - TSF
EHFIFE Lt9Bt'_lRAT('-FIE-=I IHC,
B-4
I el
10
SWELL - CONSOLIDATION TEST PRO. 8558
.57
.56
5w,
LL
* 50!
* 49 !
FA
L
L-1
DEPTH: 8.0
DP' DEr-ISITY:111:3.4 Pr-F
MOISTURE: 1-0.0%
0.25 0.5 1 0
APPLIED PFE-5SURE - T-SF
WRTER ADDED
0.5 1.0
APPLIED PRESSURE - TSF
ElIFIRE LABORATORIES irJc,
B-5
5 10
5 10
RESISTANCE R-YRLUE HND EXPHNSION PRESSURE
OF COMPACTED SOIL
ATM - D 2844
CLIENT: UNITED STATES POSTAL SERVICE
PRl)JECT: ASPEN BRANCH
LOCATION lJF AMPLE: BORING 8 COHPOSITE @ 0.0'-5.0'
SAMPLE DATA
TEST SPECIMEN
1
2
3
COMPACTION PRESSURE
- PSI
0
70
120
DENSITY - PCF
93.6
100.0
101.1
MiiISTURE - .
26.6
22.8
20.7
E`.PAN'ION PRESSURE
- PSI
0.00
0.00
0.00
HORIZONTAL PRESSURE
@ 160 psi
155
145
138
SAMPLE HEIGHT - in.
2.45
2.44
2.47
EXUDATION PRESSURE
- PSI
143
207
342
UNCORRECTED R-VALUE
1.3
4.7
6.4
CORRECTED R-VALUE
1.3
4.5
6.4
R-VALUE AT 300 PSI
EXUDATION
PRESSURE =
6.3
1 O G1
LJ 6 0
4 0 E......................
0
0 Lu
100
1
.........................................
.........................................
.......................................
............j.............
......................
..........
............'.............
.............
..............
j.............
........................�.............0.............
i.............
................................................................
.......................................
.............
.........................
.............
i..........................
........................
..........................
............
00 300 400 500 600
E):.UDATION PRESSURE — psi
EI1FIFE LFIBORRTORIES INC.
B-6
700 g00
SUMMARY OF TEST RESULTS
Boring
No.
Depth
(F t.)
Moisture
(XI
Dry
Density
Compressive
Strength
Swell
Pressure
Soluble
Sulfates
pH
Liquid
Limit
Plasticity
Index
Group
Classification
AASHTO
Resistivity
Penetration
(PCF)
(PSF)
1PSF1
IXI
1%1
I%1
Index
LISCS
IOHM.CMI
Blows/In,
1
1.0-2.0
15.8
32112
2.0-3.0
12.2
3.0-3.8
13.5
50/10
7.0-8.0
12.7
97.6
9 2810
8.0-8.4
12.8
50/5
15.0-15.4
13.1
50/5
20.0-20.4
13.2
50/5
25.0-25.3
13.4
50/3
30.0-30.3
12.0
50/3
2
1.0-1.8
11.9
335
.0024
26.0
12.6
1.2
SC -A-6(1)
50/9
5.0-5.5
11.9
50/6
10.0-10.3
12.3
50/4
15.0-15.4
13.5
50/5
20.0-20.3
14.9
50/4
25.0-25.4
12.7
50/5
30.0-30.3
12.1
50/3
3
1.0-2.0
6.5
40/12
2.0-3.0
8.3
530*
3.0-3.3
8.0
50/4
8.0-8.7
14.5
50/8
15.0-15.6
14.4
.0014
50/7
20.0-20.8
15.7
50/9
25.0-25.3
12.4
50/4 ;eI
_
„ ,
50/5
4 .
SUMMARY OF TEST RESULTS
Boring
No.
Depth
IF t.)
Moisture
(%)
Dry
Dry
Density
(PCFI
Compressive
;Strength
(PSFI
Swell
Pressure
(PSF)
Soluble
Sulfates
(%1
pH
Liquid
Limit
I%)
Plasticity
Inde■
I%1
Index
Classification
AASHTO
LISCS
Resmivity
(OHM-CMI
Penatrauoo
BlowsAn.
4
1.0-2.0
15.8
15/12
4.0-5.0
10.3
I
5.0-5.7
11.2
50/8
10.0-10.5
12.2
50/6
15.0-15.5
13.7
;
.0019
50/6
20.0-20.5
13.1
50/6
25.0-25.6
14.9
50/7
30.0-30.3
9.9
i
50/3
5
1.0-2.0
11.7
28112
3.0-4.0
11.8
595
4.0-4.9
13.4
50/11
10.0-10.6
11.5
50/7
15.0-15.6
15.7
50/7
20.0-20.5
15.2
50/6
25.0-25.5
15.5
50/6
50/5
30.0-30.4
14.0
12112
6
1.0-2.0
17.5
3.0-4.0
17.8
107.4
110380
830
.0018
43.0
23.3
17.8
CL A-7-6(18
16/12
4.0-5.0
14.1
8.0-9.0
18.3
108.0
170
18/12
9.0-10.0
18.2
50/5
15.0-15.4
13.3
50/5
20.0-20.4
13.4
SUMMARY OF TEST RESULTS
Boring
No.
Depth
Wt.)
Moisture
(%)
Dry
Density
Compressive
Strength
Swell
Pressure
Soluble
Sulfates
pH
Liquid
Limit
Plasticity
Index
Group
Classification
AASHTO
Resistivity
Penetration
IPCF)
(PSFI
IPSFI
I%)
1%)
I%1
Index
LISCS
(OHM -CM)
Blowslin,
6
25.0-25.2
12.8
5012
30.0-30.3
12.5
50/4
7
1.0-2.0
13.7
29/12
5.0-6.0
14.9
44/12
10.0-10.6
15.6
50/7
15.0-15.5
16.1
50/6
8
1.0-.20
15.0
23/12
5.0-6.0
12.0
18/12
10.0-11.0
22.7
11112
15.0-16.0
24.0
9/12
Composite
Sample
0.5-5.0
33.2
15.6
8.0
CL A-6(8)
9
1.0-2.0
11.9
18/12
5.0-6.0
19.4
55.4
26.3
29.6
CH-MH A-7-6(
0)
34/12
10.0-10.8
15.9
50/9
15.0-15.7
16.8
50/8
10
0.5-1.5
8.5
50/12
5.0-5.4
11.4
50/5
10.0-10.5
12.1
50/6
15.0-15.5
13.8
50/6
REPORT
OF A
GEOTECHNICAL INVESTIGATION
crnpF
This report presents the results of a geotechnical evaluation
prepared for the proposed post office located at the southeast corner of
Boardwalk Drive and JFK Parkway in south Fort Collins, Colorado. The
investigation included test borings and laboratory testing of samples
obtained from these borings.
The objectives of this study were to (1) evaluate the subsurface
conditions at the site relative to the proposed construction, (2) make
recommendations regarding the design of the substructure, (3)
recommend certain precautions which should be taken because of adverse
soil and/or ground water conditions, and (4) make recommendations
regarding pavement types and thicknesses for the proposed parking,
driveways and truck loading areas to be constructed at the site.
SITE EXPLORATION
The field exploration, carried out on August 13, 1990, consisted of
drilling, logging, and sampling twelve (12) test borings. The number of
borings, their depths and their locations were determined by the U. S.
Postal Service. The test borings were located in the field by Empire
--L-aborat%ies; Inc. from -existing -property pins-- using conventi'on'al
chaining methods. The locations of the test borings are shown on the
Test Boring Location Plan included in Appendix A of this report.
Boring logs and descriptive logs prepared from the field logs are shown
in Appendix A. These logs show soils encountered, location of
sampling, and ground water at the time of the exploration.
The borings were advanced with a four -inch diameter, continuous -
type, power -flight auger drill. During the drilling operations, an
engineering geologist from Empire Laboratories, Inc. was present and
made continuous observations of the soils encountered.
SUMMARY OF TEST RESULTS
BoringDepth Moisture Dry Compressive Swell Soluble Liquid PlasticityClassification
Density Strength Pressure Sulfates pH Limit Index Group pq$HTO Resistivity Penetration
No. (Ft.) 1%1 (PCF) IPSFI IPSFI I%1 1 I%1 1 I%1 I Index USCS I IOHMLMI Blows/In,
12
1.0-2.0
5.0-5.8
10.0-10.4
15.0-15.5
0.5-1.5
5.0-5.5
10.0-10.3
15.0-15.3
14.2
16.5
13.5
13.2
9.5
12.8
12.8
12.9
*Den*es remolded jample
1390*
30.7
10.6
4.0
CL A-60)
25/12
50/9
50/5
50/6
50/12
50/6
50/3
50/4
SUMMARY OF TEST RESULTS
ring Depth Moisture Resistivity Oxidation -Reduction
(ft) % ohm cm Potential (mV) Sulfide PH
1
2.0
28.8
1200
307
trace
7.8
4
4.0
26.6
1200
325
trace
7.7
8
0.5-5.0
28.5
2000
310
trace
7.7
12
5.0
31.5
1600
305
trace
7.6
0
B-11
r
m
APPENDIX C.
r
APPENDIX C.
Suggested Minimum Specifications for Placement of Compacted
Earth Fill and/or Backfills
GENERAL
The geotechnical engineer shall be the owner's, architect's,
engineer's or contractor's representative to observe placement of
compacted fill and/or backfill on the project. The geotechnical engineer
or his representative shall approve all earth materials prior to their use,
the method of placement and the degree of compaction.
MATERIALS
Soils used for all compacted fill and backfill shall be approved by
the geotechnical engineer or his representative prior to their use. Fill
material shall be free from organic matter, frozen material and other
unsuitable substance and shall not contain rocks or lumps having a
diameter greater than six (6) inches.
SUBGRADE PREPARATION
All topsoil,
vegetation, trees, brush, timber, debris, rubbish and all
other unsuitable
material shall be removed to•a depth satisfactory to the
geotechnical engineer or his representative. The material shall be
disposed of by
suitable means prior to beginning preparation of the
subgrade. The
subgrade shall be scarified a minimum depth of six (6)
inches, moisture
conditioned as necessary and compacted in a suitable
.manner prior to
placement of fill material. Fill shall not be placed until
approval by the
geotechnical engineer or his representative; and in no
case, shall fill
material be placed on frozen or unstable ground.
Subgrade which
is not stable may require the use of imported granular
-material; ileotextiles-or--other-methods-#or
stab ifiiation as approved by the
geotechnical engineer.
FILL PLACEMENT
Fill material shall not
be placed during unfavorable weather
conditions. Material
proposed
for use as fill shall be
approved by the
geotechnical engineer
or his representative prior to use.
Proposed import
material shall be
approved
by the geotechnical
engineer or his
representative prior
to hauling
to the project site. Fill
material shall be
C-2
i
uniformly
mixed such as to preclude the formation of
lenses
of material*
differing
from the surrounding material. All clods shall
be
broken into
small pieces.
The contractor shall construct the fill
in approximately
horizontal
lifts extending the entire length of the fill.
The
thickness of
the layers
before 'compaction shall not be greater than
eight
(8) inches.
Fill being
placed on slopes or hillsides shall be benched
into
the existing
slope. A
minimum two (2) foot horizontal bench shall
be cut into the
existing excavated slope for each four (4) feet vertical of
fill,
or each lift
should be
benched slightly into the existing grade.
MOISTURE CONTROL
Prior to and during compaction operations, the fill material being
placed shall be maintained within the range of optimum moisture specified.
A general recommendation is to maintain the fill material within two
percent (2%) plus or minus of optimum moisture so that proper. compaction
to the specified density may be obtained with a minimal effort. In
building pad and paved areas, material exhibiting swelling potential shall
be maintained between optimum moisture and two percent (2%) wet of
optimum moisture content. The moisture content of the fill material shall
be maintained uniform throughout the fill. The contractor may be
required to add necessary moisture to the fill material and to uniformly
mix the water with the fill material if, in the opinion of the geotechnical
engineer, it is not possible to obtain uniform moisture content by adding
water on the fill surface. If, in the opinion of the geotechnical engineer,
the material proposed for use in the compacted fill is too wet to permit
adequate compaction, it shall be dried in an acceptable manner prior to
placement and compaction. Uniform mixing may require discing, blading
or other methods approved by the geotechnical engineer or his
representative.
Adjustments of moisture content shall be made on the basis of
determinations of moisture content by field tests as construction
progresses.
COMPACTION
The contractor shall furnish and operate the necessary types and
kinds of equipment to perform the operations required to obtain the
specified compaction. This equipment may include approved tamping
rollers, rubber tired rollers, smooth wheeled rollers and vibratory
rollers. If a sheepsfoot roller is used, it shall be provided with cleaner
bars so attached as to prevent the accumulation of material between the
tamper feet. Fill areas which are not accessible to full-sized construction
equipment shall be placed in maximum four (4) inch lifts and compacted
with power tampers to the specified density.
C-3
Compaction should meet the minimum percentages of maximum density
as set forth in the project specifications or the recommendations of the
report. The contract specifications supercede the recommendations given
in this report.
MOISTURE DENSITY RELATIONSHIP DETERMINATION
Samples of representative fill materials to be placed shall be
furnished by the contractor to the geotechnical engineer for determination
of maximum density and optimum moisture or relative density. Sufficient
laboratory moisture density or relative density curves will be made to
determine the optimum moisture content and maximum density for the
various soils placed as fill. Tests for this determination will be made
using the appropriate method conforming to the requirements of ASTM D
698 (Standard Proctor), ASTM D 1557 (Modified Proctor) or ASTM D 4253,
D 4254 (Relative Density). The materials used for fill shall be classified
in accordance with ASTM D 2487 in order to permit correlation between
the moisture density relationship data and the material being placed and
compacted. Copies of the results of these tests will be furnished to the
client and others as directed by the client. These test results shall be
the basis of control for all compaction effort.
FIELD DENSITY AND MOISTURE TESTS
The in -place density and moisture content of compacted fill will be
determined by the geotechnical engineer or his representative in
accordance with ASTM D 1556 (sand cone method) or ASTM D 2922, D
3017 (nuclear methods). Material not meeting the required compaction
and/or moisture specifications shall be recompacted and/or moisture
conditioned until the required percent compaction and/or moisture content
is obtained. Sufficient compaction tests shall be made and submitted to
support the geotechnical engineer's or his representative's
recommendations. The results of density tests will also be furnished to
the client and others as directed.
C-4
r,
SITE LOCATION AND DESCRIPTION
The site is located at the southeast corner of Boardwalk Drive
and
JFK Parkway in south Fort Collins, Colorado. More particularly,
the
site is described as a tract of land located in the West 1 /2 of Section
36,
Township 7 North, Range 69 West of the Sixth P.M., City of
Fort
Collins, Larimer County, Colorado.
The site is bordered on the north by Boardwalk Drive, on the
west
by JFK Parkway, on the south by Troutman Parkway and on the east
by
vacant land. Landings Drive intersects Boardwalk Drive adjacent to
the
northeast corner of the property. The site slopes from Boardwalk Drive
and JFK Parkway to the center of the site and has generally
poor
surface drainage. Regional drainage in the area is to the south
and
east. A large stockpile of material is located in the south portion
of
the property. It appears that material has been removed from the
site
to construct the adjacent streets. The property is vegetated with
cut
grass and weeds. An abandoned irrigation latteral is located in
the
southern portion of the site.
LABORATORY TESTS AND EVALUATION
Samples obtained from the test borings were subjected to testing in
the laboratory to provide a sound basis for evaluating the physical
properties of the soils encountered. Moisture contents, dry unit
weights, unconfined compressive strengths, water soluble sulfates,
swelling potentials, resistivity, sulfides, pH, and oxidation-reduction
potential and the Atterberg limits were determined. A summary of the
test results is included in Appendix B. Swell -consolidation and Hveem
stabilometer characteristics were also determined, and curves showing
this data are included in Appendix B.
e
-2-
V
i
SOIL AND GROUND WATER CONDITIONS
The soil profile at the site consists of strata of materials arranged
in different combinations. In order of increasing depths, they are as
follows:
(1) Silty Topsoil: A six (6) inch layer of silty topsoil was
encountered at the surface of Borings 4 and 8. The topsoil has
been penetrated by- root growth and organic matter and should
not be used as a bearing soil or as a backfill material.
(2) Fill Material: A one (1) to one and one-half (1-1/2) foot layer
of fill was encountered at the surface of Borings 5, 6, and 7.
The material is probably disturbed material left after
excavation. The fill consists of mixture of sandy silty clay and
bedrock fragments. It is not known whether the fill has been
uniformly or properly compacted; therefore, it should not be
used as a foundation soil. The upper six (6) inches of the fill
material has been penetrated by root growth and organic matter
and should be stripped and used in planted areas or wasted
from the site.
(3) Sandy Silty Clay: This stratum underlies the topsoil and fill
and was encountered at the surface in all but Boring 6 and
extends to the bedrock below or to the depths explored. The
— ,generally thin layer -of silty -clay contains --varying amountss of —
sand, is dry to damp and exhibits moderate bearing
characteristics. The upper six (6) inches of the clay material
where it was exposed at the surface has been penetrated by
root growth and organic matter and should be stripped from
below building and paved areas and used in planted areas or
wasted from the site.
(4) Silty Clay:
The dark gray
silty
clay was
encountered
in
Boring 6 at
a depth of one
and
one-half
(1-1/2) feet
and
Ime
extends to depths of eight and one-half (8-1/2) feet. The silty
clay is highly plastic, is damp to moist and exhibits moderate
bearing characteristics. When wetted, the silty clay stratum
exhibits moderate swell potential.
(5) Siltstone-Sandstone-Claystone Bedrock:
The bedrock was
encountered in all but Boring 8 at depths
of one-half (1/2) to
eight and one-half (8-1/2) feet below the
surface and extends
to greater depths. The upper one and
one-half (1-1/2) to
four and one-half (4-1/2) feet of the
bedrock is highly
weathered; however, the underlying siltstone,
sandstone and
claystone is firm to dense and exhibits
high to very high
bearing characteristics. The majority
of the bedrock
encountered consists of siltstone interbedded
with sandstone.
Claystone bedrock was encountered in
Boring 11. The
siltstone-sandstone exhibits slight swell
potential, and the
claystone exhibits high swell potential.
(6) Ground Water: At the time of the investigation, free ground
water was encountered in Boring 3 at a depth of twenty-three
and one-half (23-1/2) feet below the surface. No free ground
water was encountered in the remaining borings drilled at the
site to the depths explored. Water levels in this area are
subject to change due to seasonal variations and irrigation
demands on and/or adjacent to the property. In addition, it is
spur opinion that surface water from precipitation, runoff and
irrigation may percolate through the upper subsoils and/or
building backfill and become trapped on the relatively
impervious bedrock forming a perched ground water condition.
Due to the potential for a perched water condition to develop,
it is our opinion that water levels at the site could rise to the
top of the bedrock stratum in the project area.
-4-
GEOLOGY
The site is located within the Colorado Piedmont section of the Great
Plains physiographic province. The Colorado Piedmont, formed during
Late Tertiary and Early Quaternary time (approximately sixty-five million
(65,000,000) years ago), is a broad, erosional trench which separates
the Southern Rocky Mountains from the High Plains. Structurally, the
property lies along the western flank of the Denver Basin. During the
Late Mesozoic and Early Cenozoic Periods (approximately seventy million
(70,000,000) years ago), intense tectonic activity occurred, causing the
uplifting of the Front Range and the associated downwarping of the
Denver Basin to the east. Relatively flat uplands and broad valleys
characterize the present-day topography of the Colorado Piedmont in this
region. The site is underlain by the Cretaceous Pierre Shale Formation.
The Pierre formation is overlain by minor amounts of residual and j
alluvial soils of Pleistocene and./or Recent Age.
Bedrock underlies the majority of the site at depths of less than a
few feet below the surface. The regional dip of the bedrock in this area
is slight and in an easterly direction. Seismic activity in the area is
j.
anticipated to be low; therefore, from a structural standpoint, the
property should be relatively stable. Due to relatively flat nature of
site, geologic hazards due to mass movement, such as landslides,
mudflows, etc., are not anticipated. With proper site grading around
the proposed structure and parking areas, erosional problems should be
minimal. The site lies within the drainage basin of Mail Creek, a
---tr-ibutar---of Fossil Creek. - The- property- -is located —outside —the —flood
plain of these streams and should not be subjected to flooding by Fossil
Creek or its tributary.
RECOMMENDATIONS AND DISCUSSION
It is our understanding the proposed post office is to be a
single -story, slab -on -grade masonry structure. A loading platform and
service area is proposed in the southwest corner of the building.
Parking will be located along the north, east and south portions of the
-5-