HomeMy WebLinkAbout20241235.tiffGEOTECHNICAL EXPLORATION
FOR
PARCEL NO. 096110300022,
IN PART OF THE SW1/4 OF THE SW1/4 OF SECTION 10,
TOWNSHIP 5 NORTH, RANGE 65 WEST.
(GREELEY)
WELD COUNTY, COLORADO
FOR
DERICK MOORE
CDS ENGINEERING CORPORATION
LOVELAND, COLORADO
PROJECT NUMBER
21-0977
JULY 7, 2021
CS Engineering Corporation
July 7, 2021
Project No. 21-0977
Derick Moore
18255 Ranchland Road
Peyton, CO 80831
Dear Derick,
Enclosed is the report you requested of the geotechnical exploration for the proposed
residence to be located on Parcel No. 0961103 00022, in part of the S W 1/4 of the S W 1/4 of Section
10, Township 5 North, Range 65 West, (Greeley), Weld County, Colorado.
The site appears to be suitable for the construction of the proposed residence, provided
the design criteria and recommendations given in this report are followed.
If you have any further questions concerning the information in this report, please contact
this office.
Reviewed by:
A,,9
Kevin F. Becke
Enclosures
V
r
0
o=
kg:,
$,
co la
v1
8387 J°
•
(a y
• •
•
•
•
Ja
•aY•••
AL le
0
Respectfully,
FOR AND ON BEHALF OF
CDS ENGINEERING CORPORATION
� Eriz, Engineer' ,i g Technician
165 2nd Street S.W. • Loveland, CO 80537 • (970) 667-8010 • Fax (970) 667-8024 • www.cds-eng.net
TABLE OF CONTENTS
Page
Letter of Transmittal
Table of Contents
Scope
Site Investigation
Site Location and Description
Subsurface Conditions
Foundation Recommendations
Lateral Earth Pressures
Slab Construction
Foundation Drain System
Conclusions
ATTACHMENTS
Location of Test Borings
Symbols and Soil Properties
Log of Borings
Summary of Test Results
Post -Construction Site Preparation and Maintenance
Typical Perimeter Drain Details
Placement of Compacted Fill Materials
ii
i
ii
1
1
2
2
2
3
4
5
5
Figure No. 1
Figure No. 2
Figure No. 3
Table No. 1
Appendix 1
Appendix 2
Appendix 3
1
SCOPE
This report presents the results of our geotechnical exploration for the proposed residential
building to be located at the project site. The building is anticipated to be of typical steel frame
construction. Slab -on -grade construction is anticipated for this structure.
This exploration was conducted to provide recommendations pertaining to the type and
depth of foundation system, allowable soil bearing pressures, groundwater conditions, and to
identify any complications that may be encountered during or after construction due to subsurface
conditions.
This report has been prepared for the exclusive use of our client for the project discussed.
If the building location or the scope of the project should change, CDS Engineering shall be
notified prior to construction to review the report and provide alternate recommendations if
deemed necessary. Additional borings may be required to provide the alternate recommendations.
Additional fees may apply.
SITE INVESTIGATION
The field investigation performed on June 24, 2021, consisted of drilling, logging, and
sampling two (2) test borings within the approximate building envelope at the site. The borings
ranged in depth from twelve (12) to sixteen (16) feet. The location of the Test Holes is shown on
Figure No. 1.
The boring locations were established by a representative of CDS Engineering Corporation
based on locations provided by the client. Graphical logs of the borings are shown on Figure No.
3. The descriptions of the soils and/or bedrock strata are based, primarily, on visual and tactual
methods which are subject to interpretation.
The test borings were advanced using a truck mounted, four (4) inch diameter, continuous
flight auger drill rig. Laboratory samples were obtained by driving a two and one-half (2'/z) inch
diameter California -type, split barrel sampler twelve (12) inches (or as shown) into undisturbed
soils with a 140 -pound hammer falling thirty (30) inches. Bag samples of auger cuttings may have
also been collected.
2
Laboratory tests performed were - Natural Moisture and Grain Size Analysis. All tests
were conducted in accordance with ASTM standards. A Summary of Test Results is shown on
Table No. 1.
SITE LOCATION AND DESCRIPTION
The site is located east of Greeley, south of East 18th Street, and on the east side of Cherry
Avenue, Weld County, Colorado. The site is in a developed rural subdivision with paved roads
and utilities, and vegetation consists primarily of grasses. The site is relatively flat.
SUBSURFACE CONDITIONS
Based on the borings drilled within the proposed building footprint, the subsurface
conditions at the site consist of silty sand to the depths explored.
Groundwater levels were recorded after completion of the drilling operations.
During our field exploration groundwater was encountered at depths ranging from nine (9) to ten
(10) feet. The water levels listed above are the stabilized levels of the free groundwater surface at
the time of this exploration and may not properly define yearly groundwater levels. The
groundwater table should be expected to fluctuate throughout the year depending on seasonal
moisture variations. Refer to the Log of Borings, Figure No. 3, for additional details specific to
each boring.
Although evidence of underground facilities such as, but not limited to, septic tanks/fields,
cesspools, cisterns, foundations, utilities or mining operations were not observed during our
exploration, such features could be encountered during construction. If unexpected fill or
underground facilities are encountered, proper remediation should be taken. Alternate
recommendations, other than those provided in this report, may be required.
FOUNDATION RECOMMENDATIONS
The type of foundation best suited for a particular building site is dependent not only on
the characteristics of the soil and rock but also depends on the type of structure, depth to
groundwater, the proposed depth of excavation, and owner preference. The recommendations that
follow are primarily based on the type of soil or bedrock encountered.
3
Based on the conditions observed in the field and laboratory tests, we recommend the
foundation be a continuous spread footing and isolated pad foundation.
Continuous Spread Footing and Isolated Pad Foundation
The foundation should be a continuous spread footing and isolated pad foundation designed
for a maximum allowable bearing capacity of 1500 pounds per square foot (dead load plus full
live load). The bottom of the footings should be kept a minimum of three (3) feet above the
groundwater. The foundation is to bear on the native, undisturbed sands, and not on
unapproved fill, topsoil, or frozen ground. The bottom of all foundation components should
be kept at least thirty (30) inches (or per local code) below finished grade for frost protection.
The open excavation should not be left open for an extended period of time or exposed to
adverse weather conditions. Excessive wetting or drying of the excavation should be avoided
during construction. Excavations that are inundated with water may soften and require re -
compaction, or removal, of the exposed subgrade soils. The completed open excavation should
be observed by a representative of CDS Engineering Corporation in order to verify the
subsurface conditions from test -hole data.
LATERAL EARTH PRESSURES
Lateral earth pressures are forces exerted on earth retaining structures and foundation
components, by the soil. The pressure exerted is influenced by wetting of the backfill soils, type
and compaction of the backfill and the methods used to compact the backfill. For the soils, above
the free groundwater surface at this site, we recommend the foundation components be designed
using the following equivalent fluid pressures.
• Active Pressure = 35 pcf
• At Rest Pressure = 50 pcf
These values assume that the positive drainage will be maintained throughout the life of
the structure. It is our opinion that the on -site soils encountered could be used as backfill material
against foundation walls. The soils shall be moisture conditioned and well pulverized so that all
fragments are smaller than six (6) inches. Refer to Appendix 1 for additional backfill information.
4
If there is opportunity for the backfill soils to become saturated, we shall be notified to revise the
minimum equivalent fluid density. These values do not include a factor of safety or take into
account any surcharge loading.
SLAB CONSTRUCTION
Changes in the moisture contents may result in consolidation or swelling of the subsoil,
resulting in differential slab movement. The soils encountered and tested at this site are anticipated
to exhibit no swell potential as moisture contents are increased. According to the Guideline for
Slab Performance Risk Evaluation and Residential Basement Floor System Recommendations,
developed by the Colorado Association of Geotechnical Engineers, slab performance risk at this
site would be considered low. Slabs placed on the native, unaltered soils at this site may experience
slight heaving and cracking but should not be excessive.
If slabs -on -grade are chosen and the owner is willing to accept the risks of potential damage
from slab movement, slabs should be constructed to be "free-floating" and isolated from all
structural members of the foundation, utility lines, and partition walls. There should be a minimum
two (2) inch void constructed below partition walls located over slabs -on -grade. The void should
be increased to four (4) inches for slabs placed on potentially expansive bedrock stratum.
Eliminate under -slab plumbing where feasible. Where such plumbing is unavoidable, it should be
pressure tested before and after slab construction to minimize leaks which would result in wetting
of the subsoil. Failure to allow the slab to float independently could result in functional, structural,
architectural, and utility line damage. All slabs should be scored into maximum 225 square foot
areas or maximum dimensions of fifteen (15) feet with a minimum depth of one (1) inch to localize
and control any cracking due to heaving. Any slabs less than thirty (30) square feet should be
scored at least once in each direction. The minimum slab thickness should be four (4) inches, with
four (4) inches of clean, washed gravel under the slab. Slabs should be reinforced with welded
wire fabric, or equivalent, to help control cracking and separation. Fiber mesh shall not be
considered an equivalent substitute for the welded wire fabric.
5
FOUNDATION DRAIN SYSTEM
A perimeter drain system shall be installed where below grade habitable spaces are
constructed. The drain shall be constructed around the entire exterior perimeter of the foundation
of any below grade habitable space. Perimeter drains around crawl space areas, shall be installed
as required by the current building code or by local jurisdictions.
The drain system should contain a four (4) inch diameter perforated drainpipe surrounded
by clean, washed rock. There should be a minimum of six (6) inches of gravel over the top of the
pipe, for the full width of the trench. The gravel shall be covered with untreated building paper or
geotextile fabric to minimize clogging by backfill material. The drain should have a positive slope
to a non -perforated sump pit or to daylight, well away from the foundation. The sump pit should
be a minimum of twenty-four (24) inches in diameter by two (2) feet deep and should be
surrounded by at least six (6) inches of clean gravel similar to that provided around the drain. The
sump pit shall be capable of positive gravity or mechanical drainage to remove any accumulated
water. The drainage system shall discharge a minimum of five (5) feet beyond the backfill zone.
The discharge area should be placed so that it does not interfere with adjacent properties. Typical
drain details are provided in Appendix 2 of this report.
CONCLUSIONS
The soils encountered at this site are anticipated to exhibit no swell potential as moisture
contents are increased. Future owners should be cautioned of the risk of damage caused by the
introduction of excess water to the soils. All new and future owners should be directed to those
items under "Post -Construction Site Preparation and Maintenance" in Appendix 1, included in this
report. Our experience has shown that damage to foundations usually results from saturation of
the foundation soils caused by improper drainage, excessive irrigation, poorly compacted backfills,
and leaky water and sewer lines. The elimination of the potential sources of excessive water will
greatly minimize the risks of movement at this site. Homeowners must assume responsibility for
maintaining positive drainage around the structure and incorporating appropriate landscaping that
will not interfere with the positive drainage. It is recommended that a copy or summary of this
report be provided to any new or future owners of this property. A copy of A Guide to Swelling
6
Soils for Colorado Homebuyers and Homeowners, Colorado Geological Survey Special
Publication 43 should also be provided to any new or future owners of the property.
The findings and recommendations of this report have been obtained in accordance with
accepted professional engineering practices in the field of Geotechnical Engineering. However,
standard Geotechnical Engineering practices and related government regulations are subject to
change. The recommendations provided in this report are for the exclusive use of our client and
are not valid for use by others. If the construction takes place approximately three (3) years beyond
the date of this report, we should be contacted to review the information with regard to updated
governmental requirements or industry standards. Additional fees may apply. There is no other
warranty, either expressed or implied. We do not guarantee the performance of the project in any
respect, but only that our engineering work and judgments rendered meet the standard of care of
our profession. This report applies only to the type of construction anticipated in the area tested.
The current technology is not at a stage where a guarantee of "absolutely no damage" can be
assured by design and construction practices.
d
Mi
CC
06-
Q
cri
SITE
,0 i
di
TH-1
CHERRY STREET
J
i
L
100 0 100
SCALE 1"=1001
Proposed
Residence
TH-2
E 20TH STREET
LOCATION OF TEST BORING
Client:
Project:
Derick Moore
Parcel No 096110300022, part of the SW/4 of the
SW/4 of S10 -T5 -R65 (Greeley),
Weld County, Colorado
Engineering
Corporation
165 2nd St. S.W.,
Loveland, Colorado 80537
Tele: (970) 667-8010
Date:
07/03/21
Project No.
21-0977
Drawn:
JDE
Figure: 1
S I. A
a•
j .d , ,
e —
-7-
/ /
i//
///
/ 7
/ 1 /
\\`
�z
I
I
j
,--/ ,----0
Syn
Fill
bo
Gravel
Sand
Silt
Silty Clay
Clay
Weathered
Sil tston e
CI ayston e
Sandstone
Limestone
�grieou°
Bedrock
& So
C,iRF
etmmnrr)hic
Penetration Resistance and
are Based on The Standard
\umber of
Per
Blows
foot (N)*
0-4
4---10
10-30
30---50
50+
Relative Density
Cohesionless Soils
Very Loose
Loose
Medium
Dense
Very en se
* BLOWS PER FOOT - BLOWS OF 140 LB.'
HAMMER DROPPED 30 IN. TO DRIVE
SPLIT SPOON OR CALIFORNIA SAMPLER
12" (IN.) (ASTM DL586-67)
** EQUIVALENT TO PP/2 AND Qu/2
\O. 2
Pro
De
Os
N /12 CALIFOR
\IA
N/12 SPLIT SPOON
THIN WALLED (SHELBY)
BAG SAMPLE
PIT,HE
Strength Classifications
Penetration Test
Consistency
Cohesive Soils
Soft
Firm
Stiff
Very Stiff
Hard
R SAMPLE
Approximate
Cohesion ksf**
Less than 0.5
0.5- 1.0
1.0-2.0
2.0 4.O
Greater than 4.0
Eng
e�
O
z
D
'enn
rati
�z
165 2nd St. S.W.
Loveland, CO 8O537
Tele: (970) 667-8010
0
m
D -I
ITI
o =
Frl
r
s0
5 FT.
10 FT.
15 FT.
20 FT.
25 FT.
30 FT.
35 FT.
TH-1
TH-2
0
FT.
-
.
0
FT.
/'
15/12
.
12/12
18/12
13/12
•i
SAND: silty, tr. clay, dk. brown, damp
SAND: sl. gravelly to v. gravelly, tr. silt, tan to brown,
damp to moist, medium dense
O 0
• M
D-13
O —I
m
m
0
5 FT.
10 FT.
15 FT.
20 FT.
25 FT.
30 FT.
35 FT.
Borings drilled 06/14/21
using a 4' diameter, continuous flight
truck mounted drilling rig.
Goundwater @ drilling
All soil and/or rock contacts shown on boring logs are approximate and represent subsurface conditions at time
of drilling. Boring logs and information presented on logs are subject to discussion and limitations of this report.
Boring Logs
Client:
Project:
Derick Moore
Parcel No 096110300022, part of the SW/4 of the
SW/4 of S10 -T5 -R65 (Greeley),
Weld County, Colorado
Engineering
Corporation
165 2nd St. S.W.,
Loveland, Colorado 80537
Tele: (970) 667-8010
Date:
07/03/21
Project No.
21-0977
Drawn:
JDE
Figure:
3
SUMMARY OF TEST RESULTS
TABLE NO. 1
Project No.: 21-0977
Boring
No.
Depth
(ft)
# of
penetration
blows
/
Moisture
Natural
(%)
,
Natural
Density
(pcf)
Dry
Swell*
(%)
Swell
Pressure
(psf)
Atterberg
Limits
i
Unconfined
Compressive
Strength
(psf)
Passing
#4 / #200
Seive (%)
Surcharge
(psf)
Description
(%)
LL
PI
(%)
2
15/12
7.0
70.5/ 6.3
Sand
1
1
6
18/12
2.6
75.4
/ 3.1
Sand
1
16
BAG
2.1
71.1
/ 5.9
Sand
2
3
12/12
1.7
83.6/2.2
Sand
2
7
13/12
2.6
86.1
/ 2.6
Sand
2
12
BAG
2.2
69.1
/ 5.8
Sand
4
4
*Swell due to wetting under a specified surcharge - Negative values indicate consolidation
Sheet 1 of 1
APPENDIX 1
POST -CONSTRUCTION SITE PREPARATION AND MAINTENANCE
Backfill
When encountering potentially expansive or consolidating soils, measures should be taken to
prevent the soil from being wetted during and after construction. Generally, this can be
accomplished by ensuring only minimal settlement of the backfill placed around the foundation
walls. It should be understood that some backfill settlement is normal and should be anticipated.
Areas that do settle should be repaired immediately to prevent ponding around the foundation.
Water may need to be added to backfill material to allow proper compaction -- do not puddle or
saturate. Backfill should be mechanically compacted to at least 90% of Standard Proctor.
Compaction requirements could be verified with field tests by the Engineer. It is the contractor's
responsibility to contact the engineer for such tests.
Surface Drainage
The final grade should have a positive slope away from the foundation walls on all sides. At
minimum, the slope shall meet the requirements of the governing Building Code. Where site
grading allows, we recommend a minimum of six inches (6") in the first five feet (5'). Downspouts
and sill cocks should discharge into splash blocks that extend beyond the limits of the backfill.
Splash blocks should slope away from the foundation walls. The use of long downspout extensions
in lieu of splash blocks is advisable. Surface drainage away from the foundation shall be
maintained throughout the lifetime of the structure.
Lawn Irrigation
Do not install sprinkler systems next to foundation walls, porches, or patio slabs. If sprinkler
systems are installed, the sprinkler heads should be placed so that the spray from the heads under
full pressure does not fall within five feet (5') of foundation walls, porches, or patio slabs. Lawn
irrigation must be carefully controlled.
If the future owners desire to plant next to foundation walls, porches, or patio slabs, and are willing
to assume the risk of structural damage, etc., then it is advisable to plant only flowers and shrubbery
(no lawn) of varieties that require very little moisture. These flowers and shrubs should be hand
watered only. Landscaping with a plastic covering around the foundation area is not
recommended.
Check with your local landscaper for fabrics which allow evaporation when inhibiting plant growth
when a plastic landscape covering is desired.
Experience shows that the majority of problems with foundations due to water conditions are
generally due to the owner's negligence of maintaining proper drainage of water from the
foundation area. The future owners should be directed to pertinent information in this report.
REV 7/30/13
XTV R
OR
AND/OH
FOOT N
COMPACTED BACKFILL PER
SOIL.. REPORT
UNTREATED BUILDING PAPER OR
GEOTEXTILE OVER TOP OF GRAVEL
CLEAN WASHED ROCK.
MINIMUM OF 8" OVER THE
TOP OF THE PIPE
4" PERFORATED PIPE, RIGID OR
FLEXIBLE. SLOPE TO SUMP PIT
OR DAYLIGHT.
G
NFR
FOU
0
NDAT
RI
V
ON
F TFR DRA
FDN WALL, TYP.
REINFORCEMENT NOT SHOWN
N
OPTIONAL MOISTURE BARRIER 6 -MIL MINIMUM, GLUE
TO FOUNDATION WALL A MINIMUM OF 6" ABOVE
VOIDS OR GRAVEL (WHICHEVER IS GREATER).
CONTINUE BELOW PIPE AND UP SIDE OF TRENCH
AS SHOWN.
FL.00
3Y OTHERS
"Pe. rit41,4117,1042379441itittl'ePrlai
H. trezeranzeaw as as :tit"
a teas;
I"t�Tte.!�.!*T��T�
,y
rte.-�vTt+T-.
ADDT'L LATERALS
AS RECOMMENDED
10' TO 12'
DRAIN TRENCH SHALL NOT CUT INTO
1:1 SLOPE AWAY FROM THE EDGE OF THE FOOTING
HXT
flak
OR
AND/OH
DR
COMPACTED BACKFILL PER
SOIL REPORT
LL
UNTREATED BUILDING PAPER OR
GEOTEXTILE OVER TOP OF GRAVEL
CLEAN WASHED ROCK.
MINIMUM OF 8" OVER THE
TOP OF THE PIPE
4" PERFORATED PIPE, RIGID OR
FLEXIBLE. SLOPE TO SUMP PIT
OR DAYLIGHT.
NTEf� OR
D PHH FOUN
EH
JAT
V
FT
ON
R DRA
FDN WALL_, TYP.
REINFORCEMENT NOT SHOWN
MOISTURE BARRIER. 6-v11L MINIMUM, GLUE TO
FOUNDATION WALL A VINIMUV OF 6" ABOVE
VOIDS OR GRAVEL (WHICHEVER IS GREATER).
CONTINUE BELOW PIPE AND UP SIDE OF TRENCH
AS SHOWN.
FLOOR BY OTHERS
ADDT'L LATERALS
AS RECOMMENDED
10' TO 12'
CDS
Engineering
Corporation
165 2nd St. S.W.
Loveland, CO 80537
Tele: (970) 667-8010
TYPICAL -'HHVFTFH DPAI
RH _ C0M( iEl IDP,TICN`
SITE CONDITIONS MAY WARRANT REVISIONS TO TYPICAL
DETAILS
Scale: N.T.S.
APPENDIX 2
APPENDIX 3
GENERAL SPECIFICATIONS FOR THE PLACEMENT OF COMPACTED FILL
MATERIAL PLACED BELOW A STRUCTURE
Moisture -Density Determination
Representative samples of the materials to be used for fill shall be furnished by the contractor at
least seventy two (72) hours prior to compaction testing. Samples with higher moisture contents
will require extra time for test results due to the required drying for sample preparation. Tests to
determine the optimum moisture and density of the given material will be made using methods
conforming to the most recent procedures of ASTM D698 (standard Proctor) or other approved
methods, whichever may apply. Copies of the Proctor Curves will be furnished to the contractor.
These test results shall be the basis of control for the field moisture/density tests.
Materials
The soils used for compacted fill shall be selected or approved by the Engineer. The material shall
be free of vegetation, topsoil or any other deleterious materials. The material should be relatively
impervious and non -swelling for the depth specified in the soils report with no material greater
than six (6) inches in diameter.
Site Preparation
All timber, logs, trees, brush and rubbish shall be removed from the area and disposed in a manner
approved by the local governing agency. All vegetation and a substantial amount of topsoil shall
be removed from the surface upon which the fill is to be placed. Where applicable, the surface
shall then be scarified to a depth of at least six (6) inches, moistened or dried as necessary to allow
for uniform compaction by the equipment being used. The scarified surface shall be compacted
to not less than 95% of maximum dry density based on ASTM D698, or to such other density as
may be determined appropriate for the materials and conditions and acceptable to the Engineer.
Fill shall not be placed on frozen or muddy ground.
Moisture
The fill material, while being compacted should contain, as nearly as practical (typically +/- 2%),
the optimum amount of moisture as determined by the Standard Proctor Test ASTM D698, or
other approved method. The moisture shall be uniform throughout the fill material. The effort
required for optimum compaction will be minimized by keeping soils near optimum moisture
contents. Freezing temperatures and/or inclement weather conditions may impede moisture
control and compaction operations.
Placement of Fill
The Geotechnical Engineer shall be retained to supervise the placement of fill material. The fill
material shall be placed in uniform layers and be compacted to not less than 95% of maximum dry
density based on ASTM D698, or to such other density as may be determined appropriate for the
materials and conditions and acceptable to the Engineer. Prior to compacting, each layer shall
have a maximum loose layer height of twelve (12) inches (or as dictated by the compaction
equipment and/or soil conditions) with the surface relatively level. Test areas are recommended
to determine the optimum layer thickness. Thinner lifts may be necessary in order to achieve the
required compaction. Compacted layer thickness shall not exceed six (6) inches. Each twelve
(12) inches of compacted fill shall be approved by the Engineer prior to placing succeeding lifts.
Fill shall be compacted with machinery appropriate for the type of earthen material being installed.
Granular materials shall be compacted with vibratory type machinery. Clay and silt material shall
be compacted with a sheepsfoot or other segmented pad type compaction equipment. "Wheel
rolling" is not considered an appropriate method to achieve the recommended compaction
specifications. "Wheel rolling" is not recommended for extensive areas or depths and cannot be
relied upon to give uniform results.
Moisture and Density Testing
It is the contractor's responsibility to contact the Engineer with a minimum of 24 -hours notice to
schedule compaction testing. The density and moisture content of each layer of compacted fill
will be determined by the Engineer, or qualified technician, in accordance with ASTM D6938
(nuclear method), or other approved method. If the tests show inadequate density, that layer, or
portion thereof, shall be reworked until the required conditions are obtained. Additional layers
shall not be placed until each underlying lift has been approved. The results of all density tests
will be furnished to both the owner and the contractor by the Engineer.
Hello