HomeMy WebLinkAboutFOOTHILLS PARKWAY PUD - PRELIMINARY - 36-89 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTREPORT
OF A
SOILS AND FOUNDATION
INVESTIGATION
FOR
JONES--NOWELL, DESIGNERS
FORT COLLINS, COLORADO
PROJECT NO. 1362-73
RF : STELE' S MARKET
FORT COLLINS, COLORADO
BY
EFSPIRE LABORATORIES, INC.
214 NORTH HOWES STREET
roRT COLLIHS , COLORADO
80521
I
TABLE OF CONTENTS
Table of Contents ................................. i
Letter of Transmittal 11
Report / ........................................... 1-5
Test Boring Location Plan �j
Key to Borings .................................... 7
Log of Borings .....................:.............. 6-9
Consolidation Test Data ........................... 10
Summary of Test Results ........................... 11-12
Appendix A ........................................ 13-14
-i-
Empire Laboratories, Inc.
Materials and Foundation Engineers
February 18, 1973
Jones -Nowell, Designers
ES89 South College Avenue
Century Malt
Fort Collins, Colorado 80681
Attention: Burton I. Nowell, Jr.
Gentlemen:
We are pleased to submit our Report of a Soils and Foundation
Investigation prepared for the proposed Steele'& market, looa-
ted in South Fort Collins, Colorado, as requested.
Based upon our findings in the subsurface, we feet that the
site is suitable for the proposed oonatruotion, providing
the design criteria and recommendations as set forth in this
report are suet. The accompanying report presents our findings
in the subsurface and our recommendation* based upon these
findings.
Very truly yours,
EI4PIRZ LABORA?ORISS, INC.
x kk+1,04
Aa� R. Sherrod
Engineering Geologist
rre
oo: Mr. Merrill Steels
Reviewed by: RsTC�,,�?'1l
G 040i :10; 02/
' * TD Q d
Chester C. Smith, P.B.
Vioe President
CP� Per[ P
�Pg�RAto
All
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`v 7 OFFICE AND LABORATORY-214 NORTH HOWES • P-O. BOX 149 • FORT COLLINS, COLORADO 80521 • TELEPHONE AREA 303/484-0359
0
REPORT
OF A
SOILS AND FOUNDATION INVESTIGATION
SCOPE
This report presents the results of a Soils and Foundation
Investigation prepared for the proposed structure located on
South College Avenue, Fort Collins, Colorado. The investiga-
tion was carried out by means of test borings and laboratory
testing of samples obtained from these borings.
The objectives of this investigation were to (1) determine
the^suitability of the site for construction purposes, (2) make
recommendations regarding the design of the substructure, and
(3) recommend certain precautions which should be taken Lecause
of adverse soil and/or groundwater conditions.
SITE INVESTIGATION
The field investigation, carried out on February 2, 1973,
consisted of drilling, logging and sampling six test borings.
The locations of the test borings are shown on the Test Boring
Location Plan included on page 6 of this report. Boring logs
prepared from the field logs are shown on pages g and 9.
These logs show soils encountered, location of sampling and
groundwater at the time of the investigation.
All borings were advanced with a four -inch diameter,
continuous -type, power -flight auger drill. During the drilling
operations, a field engineer from Empire Laboratories, Inc., was
present anu made a continuous visual inspection of the soils
encountered.
SITE LOCATION AND DESCRIPTION
The proposed site is located west of South College Avenue
and north of Foothills Drive, Fort Collins, Colorado. More
particularly, the site is described as the Fisher Subdivision
a tract of land situate in the Southeast 1/4 of Section 26,
Township 7 North, Range 69 West of the 6th P.M., Fort Collins,
Colorado.
The site, currently under vegetation, is relatively flat
and has good, positive drainage to the north and east. The
northern portion of the site has been filled with several feet
of loose, uncompacted fill. The Larimer County Canal No. 2
traverses the western and southern part of the site.
•
LABORATORY TESTS AND EXAMINATION
Samples obtained from the test borings were subjected to
testing and inspection in the laboratory to provide a sound
basis for determining the physical properties of the soils en-
countered. Moisture contents, dry unit weights, unconfined com-
pressive strengths, water soluble sulfates and the Atterberg
Limits were determined. A summary of the test data is included
on pages 11 and 12. Consolidation characteristics were also
determined, and a curve showing this data is included on page 10
SOIL AND GROUNDWATER CONDITIONS
The soil profile at the site consists of strata of materi-
als arranged in different combinations. In order of increasing
depths, they are as follows:
(1) Silty Topsoil and Fill Material: The north-
ern part of the site is overlain by one*.(1)
to three and one-half (3h) feet of fill mater-
ial. The fill consists of sandy, silty clay,
asphalt, concrete blocks, and debris. Some
of the material placed at the site is not suit-
able as fill material and should be wasted
from the site. The fill has not been compacted
and the topsoil below the fill has not been re-
moved. Therefore, this material is not suita-
ble as a foundation soil. A one (1) foot layer
Of silty topsoil overlies the southern part of
the site and underlies most of the fill mater-
ial. The upper six.(6) inches of the topsoil
have been penetrated by plant roots and organic
matter anti should not be used as a bearing soil
or as a backfill material.
(2) Sand and/or Sandy, Gravelly, Silty Clay: This
stratum underlies the topsoil and fill and ex-
tends to the bedrock stratum below. This soil
layer consists of a non -homogeneous mixture of
sand, gravel, silt and clay. The upper portion
of the stratum consists mostly of highly plas-
tic, sandy, silty clays while the lower portion
of the layer is composed mostly of silty sands
and gravels. The sandy, gravelly, silty clays
exhibit low to moderate bearing characteristics
in their generally moist natural state.
(3) Sandstone (Bedrock): The bedrock underlies the
_. upper soils at depths of eleven (11) to thirteen
and one-half (13�) feet below the surface and
extends to greater depths. The upper one-half
(�) to two and one-half (2�) feet of the bedrock
is highly weathered. However, the underlying
rock is firm, dense and exhibits very high
bearing characteristics.
-2-
0
(4) Groundwater: At the
re�oundwater was
four (4) to five (5)
However, these water
change depending upon
irrigational flows in
Canal.
RtCOMPIENDATIONS AND DISCUSSION
Foundation
time of the investigation,
encountered at depths of
feet below the surface.
levels are subject to
soasonal variations and
the Lariimer County uo. 2
In view of the type of structure proposed and the soil con-
ditions encountered at the site, it is recommended that the sub-
structure be supported by conventional -type, spread footings.
All footings should be founded on the original undisturbed soil
a minimum of thirty (30) inches below finished grade for frost
protection. The undisturbed nature of the soil should be veri-
fied by a soils engineer prior to placement of any foundation
concrete. In no case should footings be founded on the existing
fill material. Footings founded in the undisturbed soil may be
designed for a maximum allowable bearing capacity of fifteen
hundred pounds (1,500#) per square foot (dead load plus maximum
live load).
The predicted settlement under the aLove Maximum loading
should be lass than 0.75 inch, generally considered to be within
acceptable tolerances.
Slabs on Grade
All slabs on grade should be underlain by a minimum of four
(4) inches of gravel or crushed rock devoid of fines. The gra-
vel layer will act as a capillary break and will help to distri-
bute floor loads. Fill material supporting slabs on grade shoul,
be an approved, granular -type material compacted at optimum mois
turn to at least ninety-five percent (950) of Standard Proctor
Density. All slabs on grade should be reinforced with reinforc-
ing running through the construction joints. To Minimize and
control shrinkage cracks which will develop in slabs on grade,
it is suggested that control joints be placed every fifteen (15)
to twenty (20) feet and that the total area contained within f
these joints be not greater than four hundred (400) square feet.
Parking Area
The required total thickness for the pavement structure is
dependent primarily upon the foundation soil or subgrade and
traffic conditions. Since the proposed parking area is to be
filled, it is recommended that additional testing be performed
in the parking area after the area has been filled. It is rec-
ommended that a minimum thickness of six (6) inches be provided
for the pavement structure. This thickness should consist of
-3-
•
four (4) inches of a well -graded base course overlain by two (2)
inches of asphaltic concrete. This minimum pavement thickness
should be modified if necessary after the fill material in the
parking area is classified and tooted.
All topsoil, organic matter and other unsuitable material
should be removed from the proposed parking area. All subgrade
should be scarified a minimum of six (6) inches and recompacted
to at least ninety-five percent (95%) of Standard Proctor Den-
sity (See Appendix A).
Fill material placed in the parking area should ba an
approved type material compacted at or near optimum moisture to
at least ninety-five percent (95%) of Standard Proctor Density
(See Appendix A). The surface of the'subgrade should be hard,
uniform, smooth and.true to grade. To prevent the growth of
weeds, it is suggested that all suLgrade under parking areas be
treated with a soil sterilent.
The baso course overlying the subgrade should consist of a
hard, durable, crushed rock or stone and filler and should have
a minimum C.B.R. value of eighty (80) . The composite base courai
material should be free fron vegetable matter and lumps or balls
of clay, and should meet the following requirements:
Sieve Size
t Passing
1-
90-100
3/4-
60-90
#4
30-65
#10
20-53
#200
5-15
Liquid Limit 25 Maximum
Plasticity Index 5 Maximum
The base course should be placed on the subgrade at or near
optimum moisture and compacted to at least ninety-five percent
(95%) of Standard proctor Density (See Appendix A). It is im-
portant that the base course be shaped to grade such that proper
drainage of the parking area is obtained.
GENERAL RECORIONDATIONS
(1) Laboratory test results indicate that water solu-
ble sulfates in the soil are positive, and a
Type II cement should be used in all concrete
exposed to the soil.
(2) Finished grade should be sloped away from the
structure on all sides to give positive drain-
age. It is suggested that ten percent (10%)
for the first ten (10) feet away from the struc-
ture be provided.
-4-
•
(3) Rackfill around the outside perimeter of the
structure should be mechanically compacted at
optimum moisture to at least ninety-five per-
c®At (951) of Standard Proctor Density. Pud-
dling should not be permitted as a means of com-
paction. (Sea Appendix A).
(4) All plumbing and utility trenches underlying
Blabs and paved areas should be backfilled
with an approved material compacted to at least
ninety-five percent (95%) of Standard Proctor
Density. Puddling should not be permitted as
a means of compaction. (See Appendix A)'.
(5) Gutters and downspouts should be provided on
the structure in such a manner that water from
the roof area is discharged well beyond the
backfill area.
(6) An attempt should be made to proportion foot-
ing sizes in such a manner that the unit loads
applied to the soil are nearly equal in order
that differential settlamnt s will be mini-
mized.
(7) It is recommended that all compaction require-
ments specified herein be verified in the field
with density tests performed under the super-
vision of an experienced soils engineer.
(8) It is recommended that a registered profes-
sional engineer design the substructure and
that he take into account the findings and rec-
ommendations, of this report.
GENERAL COMMENTS
This report has been prepared in order to aid in the evalua
tion of this property and to assist the T.rchitect and/or Engi-
neer in the design of this project. In the event that any
changes in the design of the building or the location, however
slight, are planned, the conclusions and recommendations con-
tained in this report shall not be considered valid unless the
changes are reviewed and conclusions of this report modified or
approved in writing by the Soil and Foundation Engineer.
This report does not reflect any variations in the soil
which may exist between test borings. The nature and extent of
any variations Lotween the borings may not become evident until
construction. If variations do appear, it will then be neces-
sary to make a re-evaluation of the recommendations of this re-
port. To aid in this re-evaluation, on Bite observations and
tests by the soils engineer of the noted variations might become
necessary.
-5-
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A ccEss
No. ?
No. J
TEST BORING LOCATION PLAN
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KEY TO BORING
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SHELBY TUBE SAMPLE
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WATER TABLE 24 HOURS AFTER DRILLING
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_7—
EMPIRE LABORATORIES, INC.
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LOG OF BORINGS
EL EY.4T/D o. o. o.
5025
5020
5015
5010
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MAP
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Note: Bench mark ton of northeast wingway culvert
under South College Avenue for the T.arimf-r
County Canal No. 2, elevation = 5031,13,
-8-
EMPIRE LABORATORIES, INC
•
LOG OF BORINGS
ELEV.4T/O1w1 No. o. 5 o.
5025
5020
5015
5010
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CONSOLIDATION --SWELL TEST
BORING NO. 4 DEPTH 3 . 5
DRY DENSITY 10 3 . 9 # 1T 3
% MOISTURE 21 . 8 %
0.1 0.5 1.0 5 10
APPLIED PRESSURE-TONS/SQ. FT.
0.1 0.5 1.0 5
APPLIED PRESSURE-TONS/SQ. FT.
-10-
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ATTERBERG SUMMARY
Boring Number
& Depth 3 @ 4.0 5 @ 3.0
Liquid Limit 45.8 34.9
Plastic Limit 19.0 15.6
Plasticity Index 26.8 19.3
% Passing 200 44.6 60.6
Group Index 7.4 8.6
Classification
Unified SC CL
A.A.S.H.O. A-7-6(7) A-6(9)
3
-12-
APPENDIX A
Suggested Specifications for Placement of Compacted Earth Fills and/or
Backfills
GENERAL
A soils engineer shall be the owner's representative to inspect and
control all compacted fill and/or compacted backfill placed on the
project. The soils engineer shall approve all earth materials prior
to their use, the methods of placing, and the degree of compaction
obtained. A certificate of approval from the soils engineer will be
required prior to the owner's final acceptance of the filling operations.
MATERIALS
Soils used for all compacted fill beneath interior floor slabs shall be a
granular, non -expansive type. Compacted earth backfill placed adja-
cent to foundation walls shall be an impervious, non -expansive material.
No material having a maximum dimension of greater than six inches
shall be placed in any fill. All materials proposed for use in com-
pacted fill and/or compacted backfill shall be approved prior to their
use by the soils engineer.
PREPARATION OF SUBGRADE
All topsoil and vegetation shall be removed to a depth satisfactory to
the soils engineer before beginning preparation of the subgrade. The
subgrade surface of the area to be filled shall be scarified to a
minimum depth of six inches, moistened as necessary, and compacted
in a manner specified below for the subsequent layers of fill. Fill
shall not be placed on frozen or muddy ground.
PLACING FILL
No sod, brush, frozen material or other deletrious or unsuitable
material shall be placed in the fill. Distribution of material in the
fill shall be such as to preclude the formation of lenses of material
differing from the surrounding material. The materials shall be
delivered to and spread on the fill surface in such a manner as will
result in a uniformly compacted fill. Prior to compacting, each layer
shall have a maximum thickness of eight inches; and its upper surface
shall be approximately horizontal.
-13-
0
MOISTURE CONTROL
The fill material in each layer, while being compacted, shall as
nearly as practical contain the amount of moisture required for
optimum compaction; and the moisture shall be uniform throughout
the fill. The contractor may be required to add necessary moisture
to the backfill material in the excavation if, in the opinion of the
soils engineer, it is not possible to obtain uniform moisture content
by adding water on the fill surface. If, in the opinion of the soils
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.
COMPACTION
When an acceptable, uniform moisture content is obtained, each
layer shall be compacted by a method acceptable to the soils engineer
and as specified in the foregoing report as determined by the standard
Proctor test (ASTM D698-70). Compaction shall be performed by
rolling with approved tamping rollers, pneumatic -tired rollers, three -
wheel power rollers, or other approved equipment well -suited to the
soil being compacted. If a sheepfoot roller is used, it shall be pro-
vided with cleaner bars so attached as to prevent the accumulation
of material between the tamper feet. The rollers should be so designed
that the effective weight can be increased.
MOISTURE -DENSITY DETERMINATION
Samples of representative fill
by the contractor to the soils
density and optimum moisture
determination will be made u:
of ASTM D698-70. Copies of
furnished to the contractor.
control for compaction effort.
DENSITY TESTS
materials to be placed shall be furnished
engineer for determination of maximum
for these materials. Tests for this
ing methods conforming to requirements
the results of these tests will be
Chese test results shall be the basis of
The density and moisture content of each layer of compacted fill
will be determined by the soils engineer in accordance with ASTM
D1556-68, D2167-66, or D2922-71. Any material found to not comply
with the minimum specified density shall be recompa.cted until the
required density is obtained. The results of all density tests will be
furnished to both the owner and the contractor by the soils engineer.
—14—