HomeMy WebLinkAboutLAURIE SUBDIVISION PUD - PRELIMINARY - 44-89C - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTPRELIMINARY SUBSURFACE INVESTIGATION
FOR
8 ACRES LOCATED IN THE
NE 1/4 S3, T6N, R69W of the 6th PM
Prepared for
Dr. William Musslewhite
5001 S. Shield Street
Fort Collins, CO 80526
October 27, 1989
Commission No. 1180-01-01-01
CONSULTING ENGINEERS
FOUNDATION ENGINEERING
320 N. CLEVELAND
LOVELAND, COLORADO 80537
FOUNDATION
ENGINEERING
41 0
Consulting
Engineers
October 27, 1989
Commission No. 1180-01-01-01
Dr. William Musslewhite
5001 S. Shields Street
Fort Collins, CO 80526
Dear Mr. Musslewhite,
The enclosed report presents the results of a subsurface soils investigation
for 8 acres, situate in the Northeast 1/4, Section 3, Township 6 North, Range
69 West of the 6th Prime Meridian.
It is our opinion that the proposed construction is feasible provided the
recommendations contained in the attached report are incorporated into the
design of the project.
If you have any questions, please call.
Respectfulhly,
/w
Kevin W. P t�
FOUNDATIO 21;
KWP/kmp
/ C
erson, P.E.
GINEERING
320 North Cleveland Avenue Loveland, Colorado 80537 (303) 663-0138
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TABLE OF CONTENTS
Letter of Transmittal
Table of Contents
Scope
Site Description
Field Investigation
Laboratory Testing
Subsurface Soil Conditions
Foundation Recommendations
Floor Slabs
Site Grading and Utilities
Landscaping and Drainage
General Information
Consolidation Swell Tests
Test Boring Location Map
Legend of Soil Symbols
Boring Logs
Summary of Test Results
Suggested Specifications for Placement of
Compacted Earth Fills and/or Backfills
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1
1
2
2
2
3
5
5
5
6
Figures 1 & 2
Figure 3
Figure 4
Figures 5 & 6
Figure 7
Appendix A
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S C O P E
•
The following report presents the results of a subsurface soils investigation
on eight acres, situate in the Northeast 1/4 of Section 3, Township 6 North,
Range 69 West of the 6th Prime Meridian, Larimer County, Colorado. The invest-
igation was performed for Dr. William Musslewhite. The purpose of this invest-
igation was to obtain the technical information and soils property data necessary
for the design and construction of foundations for the proposed residence. The
conclusions and recommendations presented in this report are based upon analysis
of field and laboratory data and experience with similar soils in the general
vicinity.
S I T E D E S C R I P T I O N
Generally the site is rectangular, consisting of eight acres fronting on the West
side of S. Shields Street, to the South of Harmony Road. Through the center of
the site, a deep ravine has been created by scouring action associated with dis-
charging from the Pleasant Valley and Lake Canal. Several areas of moisture
seepage was noted along the banks.
Fast of the Pleasant Valley and Lake Canal, the property slopes gently towards
S. Shields Street, all of which is currently in irrigated pasture. A house and
several out buildings are currently on the Southeast corner of the site.
To the West of the ravine, the property slopes at approximately fifteen percent
towards Fossil Creek. Vegetation consists of sparse grasses and sage brush.
1
F I E L D I N V E S T I G A T I O N
The field investigation consisted of two borings at selected locations on the
site. The borings were advanced with a 4-inch diameter continuous -flight power
auger. All borings were continued to hard claystone bedrock or refusal.
Complete logs of the boring operation are shown on the attached plates and in-
clude visual classifications of each soil, location of soil changes, standard
penetration test results, and water table measurement at the time of this in-
vestigation.
As the boring operation advanced, an index of soils relative density and con-
sistency was obtained by use of the standard penetration test, ASTM Standard
Test D-1586. The penetration test result listed on the log is the number of
blows required to drive the 2-inch split -spoon sampler one foot into undisturb-
ed soil by a 140-pound hammer dropped thirty inches.
Undisturbed samples for use in the laboratory were taken in 3" O.D. thin wall
samplers (Shelby), pushed hydraulically into the soil. All samples were sealed
in the field and preserved at natural moisture content until time of test.
L A B O R A T O R Y T E S T I N G
The laboratory testing program was undertaken to measure critical shear and con-
solidation -swelling characteristics of the soils. Additional testing included
tests necessary to verify visual classification and moisture content of soils
from borings.
S U B S U R F A C E S O I L C O N D I T I O N S
Soils at the site consist of twelve inches of topsoil, over a sandy pediment
2
which extends to the depths explored. No bedrock was encountered during drilling
operations, however, the upper Cretaceous Pierre Shale was exposed in the bottom
of the discharge canal which is located in the center of the property.
Topsoils were encountered in all borings, consisting of approximately twelve inches
of a dry, brown, silty sand. These topsoils have been penetrated by root growth
and other organic material. We suggest they not be used as a bearing material.
Instead, they should be stripped and stockpiled for later use in landscaped areas.
Guaternary pediments associated with erosion of the Front Range underlie the
topsoils and extend to the depths explored. These soils are generally sand, con-
taining varying amounts of clays and silts. Some gravel was noted at approximately
five to seven feet. Penetration indicates a moderate bearing capacity, while con-
solidation testing yielded no swell potential. Upon loading, these soils will
readily consolidate.
Ground water levels were recorded as the borings were being advanced and immediately
after completion of the drilling operation. At the time of our field investigation,
ground water was encountered in test hole number one at eleven feet, and test hole
number four at seventeen feet. However, the ground water table can be expected to
fluctuate throughout the year depending upon variations in precipitation, surface
runoff and application of irrigation water on the adjacent irrigated pasture to
the north. The ambient ground water table at the site, however, unless a source
of water not presently contributing becomes available, is not expected to rise to
a level which would affect the construction or utilization of the veterinary
clinic.
IF O U N D A T I O N R E C O M M E N D A T I O N S
The selection of the foundation type for a given situation and structure is govern-
ed by two basic considerations. First, the foundation must be designed so as to
3
be safe against shear failure in the underlying soils; and second, differential
settlement or other vertical movement of the foundation must be controlled at a
reasonable level.
Two basic controls are available to us in selecting the foundation type and
allowable loads. These are the standard penetration test and consolidation
swell testing. The ultimate bearing capacity of the foundation element, the
depth below the surface, and the physical characteristics of the supporting
soil.
It is our understanding that a veterinary clinic is planned for the site and
is to be located in the vicinity of test borings one and two. Construction is
to be typical wood frame type founded on a crawl space, and as such should gene-
rate only light loading, on the order of 1,000 to 1,500 PLF. Concentrated loads
should range between 4,000 to 8,000 pounds.
Based upon our evaluation of field and laboratory testing, we recommend the
clinic be founded upon conventional balanced spread footings proportioned using
a maximum bearing capacity of 1,500 PSF (1/2 live load + dead load). No minimum
dead load need be maintained on the footings.
Foundation walls and other structural elements should be designed by a qualified
structural engineer for the appropriate loading conditions. All footings should
be placed below any topsoil or fill unless the fill has specifically been placed
and compacted for support of footings. All exterior footings should be placed be-
low frost depth to provide adequate cover for frost protection, thirty inches in
this area. Foundation walls should be reinforced with rebar to span an unsupported
length of ten feet. Rebar should be run continuously around corners and be properly
spliced.
If isolated areas of loose soils are exposed during final footing excavation, these
soil areas should be removed down to undisturbed, acceptable soils prior to place-
ment of the footings. Footings can then be placed directly upon the acceptable
soils.
4
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F L 0 0 R S L A B S
Slabs should be constructed "free floating", isolated from all bearing members,
reinforced with wire mesh, and jointed frequently. Slabs -on -grade should be
underlain with a 4-inch layer of clean gravel or crushed rock to help -distribute
floor loads and provide a capillary break. Positive drainage should be provided
for the gravel underlayment to prevent pooling of water beneath the slab. Ex-
terior slabs exposed to de-icing chemicals or extreme weathering should be con-
structed using a more durable concrete using a Type II cement with higher air
contents and lower water -cement ratios.
S I T E G R A D I N G A N D U T I L I T I E S
Specifications pertaining to site grading are included below and in Appendix A
of this report. It is recommended that the upper twelve inches of topsoil below
building, filled and paved areas be stripped and stockpiled for reuse in planted
areas. The upper six inches of the subgrade below building, paved and filled
areas should be scarified and recompacted two percent wet of optimum moisture to
at least ninety-five percent of Standard Proctor Density ASTM D-698-70 (See Appen-
dix A).
Additional fill should consist of the onsite sandy soils or imported material
approved by the geotechnical engineer. Fill should be placed in uniform six to
eight inch lifts and mechanically compacted two percent wet of optimum moisture
to at least ninety-five percent of Standard Proctor Density ASTM D-698-78.
L A N D S C A P I N G A N D D R A I N A G E
Every precaution should be taken to prevent wetting of the subsoils and percolation
of water down along the foundation elements. Finished grade should be sloped away
from the structure on all sides to give positive drainage. A minimum of six inches
5
fall in the first ten feet is recommended. Sprinkling systems should not be
installed within ten feet of the structure. Downspouts are recommended and
should be arranged to carry drainage from the roof at least five feet beyond
the foundation walls.
14 Backfill around the outside perimeter of the structure, except as noted above,
should be compacted at optimum moisture, or above, to at least ninety percent
of Standard Proctor Density as determined by ASTM Standard Test D-698. A
10 suggested specification for placement of backfills is included as Appendix A.
1 The backfill placed immediately adjacent to the foundation walls, if not com-
pacted, can be expected to settle with resulting damage to sidewalks, driveway
aprons, and other exterior slabs -on -grade. To avoid settlement and disfigure-
ment of the slabs in the event that the backfill is not to be compacted, we
recommend that concrete slabs which must span the backfill be structurally
affixed to the foundation walls. This is conventionally done by including
horizontal reinforcing bars near the top of the foundation walls which sub-
sequently tie directly into the slab. The slab should be reinforced as nec-
essary for the span involved.
14 G E N E R A L I N F O R M A T I O N
10 The data presented herein were collected to help develop designs and cost esti-
mates for this project. Professional judgments on design alternatives and criteria
are presented in this report. These are based on evaluation of technical informa-
tion gathered, partly on our understanding of the characteristics of the structure
proposed, and partly on our experience with subsurface conditions in the area. We
do not guarantee the performance of the project in any respect, only that our engi-
neering work and judgments rendered meet the standard of care of our profession.
The test holes drilled were spaced to obtain a reasonably accurate picture of sub-
surface conditions for design purposes. Variations from the conditions protrayed
I.
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frequently occur. These variations are sometimes sufficient to necessitate
modifications in design.
We recommend that construction be continuously observed by a qualified soils
technician trained and experienced in the field to take advantage of all
opportunities to recognize some undetected condition which might affect the
performance of the foundation system.
7
Date October 27, 1989
Commission -No-. 1180-01-01-01
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LEGEN O
OF SOILS SYMBOLS
FILL
GRAVELS
SANDS N y SHELBY TUBE SAMPLE
SILTS
GRAVELS, SAND &
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STANDARD PENETRATION
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TEST SAMPLER*
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SILTY SANDS,
SANDY SILTS
SANDY CLAYS,
WATER TABLE AT
CLAYEY SANDS
TIME OF DRILLING
SAND, SILT & CLAY
COMBINATIONS
CLAYS
HOLE CAVED
WEATHERED BEDROCK
SILTSTONE
CLAYSTONE # 20112 indicates that 20 blows
of a 140 lb. hammer falling
SANDSTONE 30" was required to penetrate
1211
LIMESTONE
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Suggested Specifications for Placement of Compacted Earth
Fi l l s and/or Backf i l l s.
G E N E R A L
A soils engineer shall be the owner's representative to
supervise and control all compacted fill and/or compacted
backfi 1 1 placed on the project. The soi 1 s 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
The soi 1 s used for compacted fi 1 1 beneath interior floor
slabs and backfill around foundation walls shall be
impervious and non-swel' for the depth shown on the
drawings. No material shall be placed in the fill having a
maximum dimension of six inches or greater. All materials
used in either compacted fill or compacted backfill shall be
subject to the approval of the soils engineer.
P R E P A R A T I O N O F S U B G R A D E
Al 1 topsoi 1 and vegetation shaI 1 be removed to a depth
satisfactory to the soils engineer before beginning
preparation of the subgrade. The subgrade surface of the
area to be fi 1 led 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.
1 of 3
P L A C I N G F I L L
No sod, brush, frozen material or other deleterious 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 fi 1 1 surface in such a manner as wi 1 1
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.
M O I S T U R E C 0 N T R 0 L
The fill material in each layer, while being compacted,
shall as near]y as practical contain the amount of moisture
required for optimum compaction; and the moisture shall be
uniform throughout the fill. The contractor .,ay be required
to add necessary moisture to the backfiI 1 material in the
excavation if, in the opinion of the soils engineer, it is
not possible to obtain uniform moisture contact by adding
water on the fi l l Surface. If, in the opinion of the soil s
engineer, the material proposed for use in the compacted is
too wet to permit adequate compaction, it shall be dried in
an acceptable manner prior to placement and compaction.
C O M P A C T I O N
When an acceptab 1 e, uniform moisture content is obtained,
each layer shall be compacted by a method acceptable to the
so 1 s engineer and as specified in the foregoing report as
determined by the Standard Proctor Test (ASTM D698).
Compaction shall be performed by rolling with approved
tamping rol Iers, pneumatic -tired rol Iers, three -wheel power
rollers, or other approved equipment well suited to the soil
being compacted. 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. The
2 of 3
s 1 •
rollers should be so designed that the effective weight can
be increased.
M O I S T U R E- D E N S I T Y D E T E R M I N A T I O N
Samples of representative fill materials to be placed shall
be furnished by the contractor to the soils engineer for
determination of maximum density and optimum moisture for
® these materials. Tests for this determination will be made
using methods conforming to requirements of ASTM D698.
Copies of the results of these tests will be furnished to
the contractor. These test results shall be the basis of
® control for compaction effort.
D E N S I T Y T E S T S
The density and moisture content of each la;•t-r of compacted
F? 1 1 vi' be determined by the soi 1 s engineer in accordance
with AST;t D1556 or D2167. Any material found to not comply
with the minimum specified density shall be recompacted
duntil t�_ require- densit; is obtained. The results of all
density tests will be furnished to both the owner and the
ii contractor by the soils engineer.
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