HomeMy WebLinkAboutSubsoils Report for Foundation DesignGrand Valley Consulting, LLC dba
RESIDENTIAL SOIL INVESTIGATION
51 Boulder Ridge Drive
Parachute, Colorado
Prepared For:
Aaron Sifuentes
970-274-4319
Asifuentes42PqmaiI.com
Job No. 5258
July 8, 2025
(970) 261-3415 • jwithers@geotechnicalgroup.net
832 North Crest Drive, Unit D, Grand Junction, Colorado 81506
TABLE OF CONTENTS
SCOPE............................................................................................................................1
SUMMARY OF CONCLUSIONS.................................................................................... 2
SITECONDITIONS.........................................................................................................3
PROPOSED CONSTRUCTION...................................................................................... 3
SITEGEOLOGY.............................................................................................................4
SUBSURFACE CONDITIONS........................................................................................4
RESIDENCE FOUNDATIONS........................................................................................5
FOOTINGFOUNDATION.................................................................................................... 6
TURNED DOWN REINFORCED SLAB FOUNDATIONS............................................................ 7
FLOORSYSTEMS.......................................................................................................... 8
BELOW -GRADE CONSTRUCTION.............................................................................11
CONCRETE..................................................................................................................11
SURFACEDRAINAGE.................................................................................................12
CONSTRUCTION MONITORING.................................................................................13
LIMITATIONS...............................................................................................................13
APPENDIX A — FIELD EXPLORATION
FIG. A-1 -Vicinity Map
FIG. A-2 — Location of Exploratory Test Borings
FIG. A-3 — Field Exploration Description
FIGS. A-4 and A-5 — Boring Logs
APPENDIX B — LABORATORY TESTING
FIG. B-1 — Laboratory Testing
FIGS. B-2 and B-3 — Swell -Consolidation Test Report
FIG. B-4 — Moisture -Density Relationship Test Report
TABLE B-I — Summary of Test Results, 1 page
APPENDIX C — SUPPORTING DOCUMENTS
FIG. C-1 — General Notes
FIG. C-2 — Unified Soil Classification System
FIG. C-3 — Interior Foundation Wall Drain Concept
FIG. C-4 — Exterior Foundation Wall Drain Concept
SCOPE
This report presents the results of a residential soil investigation for the proposed
residence to be located at 51 Boulder Ridge Drive in Parachute, Colorado. Our
investigation was conducted to explore subsurface conditions and provide
recommendations for design and construction of the proposed structure. The report
includes descriptions of subsoil and groundwater conditions found in two (2) exploratory
borings, recommended foundation systems, allowable design soil pressures, and design
and construction criteria for details influenced by the subsurface conditions. This
investigation was performed in general conformance with our proposal No. 25-1440 dated
June 4, 2025. Scope does not include slope stability analysis or recommendations for site
retaining walls, if any.
The report was prepared from data developed during our field exploration,
laboratory testing, engineering analysis and experience with similar conditions. A brief
summary of our conclusions and recommendations follows. Detailed criteria are
presented within the report.
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SUMMARY OF CONCLUSIONS
1. Subsoils found in the exploratory borings consisted of 19 feet of silty, sandy
clay underlain by sandy, clayey gravel to the maximum depth explored of
24.5 feet. Groundwater was not encountered at time of drilling.
2. Soils at foundation levels include silty, sandy clay. We recommend footing
foundations for the proposed construction. An alternative turned down slab
foundation system may be built if more risk of movement is acceptable to
the owner. There should be a moisture conditioned and well compacted soil
subgrade and a section of well compacted granular structural fill. A
discussion and recommendations for design and construction are included
in the text of the report.
3. We believe slab -on -grade construction supported by the soils encountered
will have potential for movement. We recommend structurally supported
floors in all finished areas unless slab type foundation/floor system is used.
There should be a moisture treated and well compacted soil subgrade and
at least 12-inches well compacted structural fill supporting other floating
slabs. Additional discussion, including design and construction criteria, is
included in the text of the report.
4. Surface drainage should be designed for rapid runoff of surface water away
from the proposed structure. It is very important to control water sources
and provide proper drainage as these are common causes of distress.
Heavy irrigation can cause significant increase in water levels, movement
and damages and should be controlled near the building areas. It is
important to grade the surface to promote positive drainage away from
building areas.
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SITE CONDITIONS
The subject site was located at 51 Boulder Ridge Drive in Parachute, Colorado as
shown on Fig. A-1, attached. The subject site was covered with scattered desert grass
and bushes. The ground surface in the first twenty feet north of Boulder Ridge Drive had
a drop in elevation of about 3 feet. The remainder of the subject site slopes down toward
the north at 3-5° (measured by hand inclinometer). There were soil fill piles on the subject
site in the southwest corner between 3 and 4 feet tall. Existing single family residences
were located east, south and west of the subject site. A golf course was north of the
subject site.
PROPOSED CONSTRUCTION
Proposed construction includes an approximate 2,000 square foot (SF) house with
attached 3 car garage. The house will be a ranch style one story, wood frame
construction with no below grade/basement. Shallow turned down slab foundations and
floors are desired. Wall loads of 1,000 to 2,000 pounds per lineal foot of foundation wall
are anticipated. The owner understands and accepts there is risk of cracking and
movement associated with slab floors. If proposed construction is different than what is
described above, we should be notified so that we can re-evaluate the recommendations
made, in consideration of the differences.
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SITE GEOLOGY
Near site geology was identified on the "Preliminary Geologic Map of the Grand
Valley Quadrangle, Garfield County, Colorado" by John R. Donnell, Warren E. Yeend,
and Marjorie C. Smith dated 1986 as mudflow and fan gravel deposits. Gravel was
encountered starting at 19 feet below ground surface at time of drilling.
SUBSURFACE CONDITIONS
Subsurface conditions at the site were investigated by drilling and sampling the
soils encountered in two (2) exploratory borings. Location of the exploratory borings are
shown on Fig. A-2. A summary description of field investigation methods is included in
Fig. A-3. Summary logs of the soils encountered in the exploratory borings and field
penetration resistance tests are presented on Figs. A-4 and A-5. Subsurface conditions
encountered consisted of 19 feet of silty, sandy clay underlain by sandy, clayey gravel to
the maximum depth explored of 24.5 feet. The silty, sandy clay was stiff to very stiff, dry,
brown and tan. The sandy, clayey, gravel was very dense, dry, brown and tan.
Groundwater was not encountered at time of drilling.
One silty, sandy clay sample from TH-1 at 9 feet depth was tested for one
dimensional swell/consolidation characteristics. The sample tested had a moisture
content of 3.5 percent, a dry density of 99 pcf and exhibited 0.8 percent consolidation
when wetted under a confining pressure of 1,000 psf. One clayey, sandy gravel sample
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from TH-1 at 24 feet depth tested had a moisture content of 7.9 percent, a dry density of
109 pcf and 35 percent passing the No. 200 sieve (silt and clay sized particles). One
silty, sandy clay sample from TH-2 at 4 feet depth was tested for one dimensional
swell/consolidation characteristics. The sample tested had a moisture content of 3.6
percent, a dry density of 101 pcf, exhibited 0.1 percent swell when wetted under a
confining pressure of 500 psf and had an estimated swell pressure of 640 psf. One
combined bulk sample from TH-1 and TH-2 at 0-5 feet depth tested had a moisture
content of 3.8 percent, a liquid limit of 26 percent, a plasticity index of 8 percent, 86
percent passing the No. 200 sieve (silt and clay sized particles) and 13 ppm water
soluble sulfates. Standard Proctor testing indicated a maximum dry density of 114 pcf
and an optimum moisture of 14.5 percent. Results of laboratory testing are shown in
APPENDIX B and summarized on Table B-I.
RESIDENCE FOUNDATIONS
This investigation indicates subsurface conditions at foundation levels consists of
silty, sandy clay with settlement potential. A consolidation of 3.8 percent over a distance
of 6 feet indicates potential settlement of almost 3 inches. We recommend footing
foundations for the proposed construction. An alternative turned down slab foundation
system may be built if more risk of movement is acceptable to the owner. Turned down
slab foundations can help reduce cost and may be desired for that reason. There should
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be a portion of the existing soils supporting foundations are removed and replaced by a
granular structural fill in a well compacted manner. Design and construction criteria for
footing foundations or turned down slab foundations are presented below in an order of
decreasing attractiveness. Combined foundations (such as footings with attached slabs)
are not appropriate and should not be used. These criteria were developed from analysis
of field and laboratory data and our experience. The additional requirements of the
structural engineer and structural warrantor (as applicable) should also be considered.
Footing Foundation
1. Footing foundations bearing on scarified, moisture conditioned and well
compacted native soil subgrade and at least 2 feet of well compacted
granular structural fill can be designed for a maximum allowable soil
bearing pressure of 1,500 pounds per square foot (psf). Bearing pressures
should be balance by the structural engineer as much as practical.
2. Grade beams should be well reinforced, both bottom and top, to resist a
simple span of at least 12 feet. Reinforcing should be designed by a
structural engineer registered in the state of Colorado. We recommend a
minimum continuous footing width of 18-inches and minimum isolated pad
of 30 inches square.
3. The completed excavation, within 2 feet horizontally of foundation bottom
in each direction, should be scarified a depth of 10-inches, moisture
conditioned to within 2 percent above to 2 percent below optimum
moisture content and compacted to at least 95 percent of standard Proctor
maximum dry density (ASTM D698) and tested prior to placing structural
fill. If initial subgrade compaction tests indicate low density, we may
recommend using an alternative system or extending thickness of
reworked/recompacted zone at that time. Soft subgrade areas identified at
time of excavation may require stabilization prior to structural fill
placement. Actual stabilization would depend on conditions observed at
time of excavation. Structural fill should consist of a crushed granular
material soil with a maximum particle size of 2 inches, a maximum liquid
limit of 30 and a maximum of 15 percent passing the No. 200 sieve. An
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imported CDOT Class 6 aggregate base course meets these criteria and is
recommended. Native onsite soils may be reused as a lower cost
alternative to imported road base. After excavation bottom proof roll using
a heavy pneumatic tired vehicle such as a front end loader with full bucket
and compaction testing show suitable subgrade preparation, structural fill
should be placed in 10-inch maximum loose lifts, moisture conditioned to
within 2 percent of optimum moisture content and compacted to at least
95% maximum modified Proctor dry density (ASTM D1557). Our
representative should be called to observe and test compaction of
subgrade (or provide stabilization recommendations, as applicable) and
test compaction of each foot of the structural fill, prior to placement of the
next proceeding lift of fill.
4. Exterior walls must be protected from frost action. We understand there is
a 36-inch mi imum frost depth in the Garfield County area. We
recommend referring to the local building code for frost protection
requirements.
5. Completed excavations should be inspected by a representative of our firm,
prior to fill placement, to confirm that the soils are as anticipated from the
exploratory test borings and to test compaction of native subgrade soil and
fill during placement.
Turned Down Reinforced Slab Foundations
1. Turned down reinforced slabs bearing on stabilized or well compacted
subgrade and 2 feet of well compacted, well graded, crushed granular
structural fill can be designed for a maximum allowable soil bearing
pressure of 1,500 pounds per square foot (psf). The recommended
structural fill should be placed beneath perimeter and interior load bearing
sections and a minimum of at least 24-inches structural fill should be a
uniform mat across the building pad. The slabs should be adequately
reinforced to evenly distribute structure loads over the slab area. Loose
soils should be completely removed from foundation bearing areas, prior to
placing concrete.
2. The completed excavation, within a 1 H:1 V slope from outside edge of
foundation to bottom of excavation, should be scarified a depth of 10-
inches, moisture treated to within 2 percent below to 2 percent above
optimum moisture content and compacted to at least 95 percent of
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standard Proctor maximum dry density (ASTM D698). If initial subgrade
compaction tests indicate low density, we may recommend using an
alternative system or extending thickness of reworked/recompacted zone
at that time. If loose or yielding conditions encountered in the open
excavation stabilization may be necessary. The excavation bottom should
be proof rolled, observed by our representative, using a heavy rubber tired
equipment load. Actual stabilization is dependent upon conditions found
during construction. The structural fill should consist of an imported,
crushed granular material with a maximum particle site of 2 inches, a
maximum liquid limit of 30 and a maximum of 15 percent passing the No.
200 sieve. Native on site soils may be reused as a lower cost alternative to
imported road base. Structural fill should be placed in 10-inch maximum
loose lifts moisture conditioned to within 2 percent of optimum moisture
and compacted to at least 95% of maximum modified Proctor dry density
(ASTM D1557).
3. We recommend thickened slab portions be at least 18 inches wide
continuous, where required. Perimeter foundations should be well
reinforced both top and bottom so that they will span an unsupported
distance of at least 12 feet.
4. The soils under foundations should be protected from freezing. We
understand the depth of frost protection usually assumed in the Garfield
County area is 36-inches. Refer to the local building code for frost
protection requirements.
5. Completed excavations should be inspected by a representative of our firm,
prior to forming, to confirm that the soils are as anticipated from exploratory
test boring and to test compaction. We should be called to make a record of
the prepared subgrade and each foot of fill placed.
FLOOR SYSTEMS
Some movement must be assumed from an increase in loading and change in
moisture by irrigation, site roof run off, snow melt and storm drainage. To our knowledge,
the only reliable solution to control floor movement is the construction of a structurally
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supported floor with at least a 12-inch (likely 36-inch or greater) air space between the
floor and subgrade. Structural floors are not considered practical with monolythic slab
foundations where slabs are integral. Structurally supported floors are also normally not
used in unfinished areas used only for storage, patio/porches and entry ways. Floating
slabs move. We recommend other site slabs be constructed on a minimum 12-inches of
well compacted granular structural fill. Care should be taken the fill subgrade soil and fill
is placed in a well compacted manner and tested prior to proceeding. Slabs -on -grade
can be used for driveway and flatwork areas provided the builder and owner are aware of
and accepts risk of potential movement and associated damage.
We recommend the following precautions for construction of floating slabs -on -
grade at this site. These precautions will not prevent movement in the event the
underlying soils become wetted; they only tend to reduce or mask damage if movement
occurs. The owner and future owners must accept the risk of further maintenance,
including possible replacement, of concrete slabs on grade.
1. Concrete slabs on grade should be supported on scarified, moisture
conditioned, well compacted native soil subgrade and at least 12-inch
thickness well compacted structural fill. The structural fill should consist of
imported crushed granular fill or native onsite soils as described above in
the RESIDENCE FOUNDATIONS section of the report. Prior to fill
placement, the resulting subgrade soil should be scarified a depth of 10-
inches, moisture conditioned to within 2 percent below to 2 percent above
optimum moisture content and compacted to at least 95 percent of standard
Proctor maximum dry density (ASTM D698) prior to fill placement.
Additional fill should be placed in thin lifts and moisture conditioned and
compacted as described in the RESIDENCE FOUNDATIONS section,
above. Each foot placed should be tested, as stated above before placing
the next lift. Any existing fill found on site during excavation should be
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removed and replaced in conformance with the recommendations above.
The recommended layer of compacted fill will not mitigate potential
movement of slabs -on -grade due to soil volume changes of soils supporting
the slabs. It will only help provide a more uniform support for the slabs -on -
grade. Our representative should be onsite prior to forming to verify soil
types and proper subgrade preparation and proper structural fill
compaction.
2. Slab -on -grade construction should be limited to areas such as exterior
flatwork.
3. Slabs should be separated from exterior walls and interior bearing members
with a slip joint, which allows free vertical movement of slabs.
4. The use of slab -bearing partitions should be avoided. Where such
partitions are necessary, a slip joint allowing at least 2 inches of free vertical
slab movement should be used. The owner should be advised of potential
movement and re-establish this void if it closes. Doorways and stairwells
should also be designed for this movement. Sheetrock should not extend
to slab -on -grade floors.
5. Underslab plumbing should be eliminated where feasible. Where such
plumbing is unavoidable, it should be thoroughly pressure tested during
construction for leaks and should be provided with flexible couplings. Gas
and water lines leading to slab -supported appliances should be constructed
with flexibility.
6. Plumbing and utilities, which pass through slabs, should be isolated from
the slabs. Heating and air conditioning systems supported by the slabs
should be provided with flexible connections capable of at least 6 inches of
vertical movement so that slab movement is not transmitted to the
ductwork.
7. Frequent control joints should be provided to reduce problems associated
with shrinkage and curling. The American Concrete Institute (ACI) and
Portland Cement Association (PCA) recommend a maximum panel size of
8 to 15 feet depending upon concrete thickness and slump, and the
maximum aggregate size. We advocate additional control joints 3 feet off
and parallel to grade beams and foundation walls.
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8. Exterior patio, porch and sidewalk slabs should be designed to function as
independent units. Movement of slabs -on -grade should not be transmitted
directly to the foundations. Stucco finish (if any) should terminate at least 6
inches above any flatwork.
BELOW -GRADE CONSTRUCTION
Below -grade construction is not anticipated at this site. Foundation drains are
recommended to help avoid a potential `bath tub' effect created by a granular fill. The
appropriate location of drain would be in the bottom of excavation and sloped toward a
positive gravity outlet or sump where water can be removed by pumping. It is possible a
foundation drain may not be used in case of turned down slab foundations where there is
no crawl space below exterior grades. The foundation drain concept is shown on Figs. C-
3 and C-4. A foundation drain may help reduce potential for water but may not relieve all
potential sources of water.
CONCRETE
One combined bulk sample from TH-1 and TH-2 at 0-5 feet depth was tested for
water-soluble sulfates. This sample had a sulfate concentration of 13 ppm, a negligible
exposure level. We recommend following the American Concrete Institute (ACI)
guidelines for sulfate resistant cement. ACI recommends an ordinary Type I or Type II
cement be used for concrete that comes into contact with soils that have a negligible
exposure on concrete. In addition, concrete should have a minimum compressive
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strength of 2,500 psi.
SURFACE DRAINAGE
Performance of foundations and concrete flatwork is influenced by surface
moisture conditions. Risk of wetting foundation soils can be reduced by carefully planned
and maintained surface drainage. Surface drainage should be designed to provide rapid
runoff of surface water away from the proposed structure. It is important to grade the
surface to promote positive drainage away from building areas. We recommend the
following precautions be observed during construction and maintained at all times after
the construction is completed.
1. The ground surface surrounding the exterior of the building should be
sloped to drain away from the building in all directions. We recommend a
slope of at least 12 inches in the first 10 feet around the structure, where
possible. In no case should the slope be less than 6 inches in the first 5
feet. The ground surface should be sloped so that water will not pond
adjacent to the structures.
2. Backfill around foundation walls should be moistened and compacted.
Clayey backfill soils are recommended for reuse (only) in the upper 24
inches of exterior wall backfill.
1 Roof downspouts and drains should discharge well beyond the limits of all
backfill. Splash blocks and downspout extenders should be provided at all
discharge points.
4. Landscaping should be carefully designed to minimize irrigation. Plants
used close to foundation walls should be limited to those with low moisture
requirements; irrigated grass and/or plants should not be located within 5
feet of the foundation. Sprinklers should not discharge within 5 feet of
foundations. Irrigation should be limited to the minimum amount sufficient
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to maintain vegetation; application of more water will increase likelihood of
slab and foundation movements.
5. Impervious plastic membranes should not be used to cover the ground
surface immediately surrounding the structure. These membranes tend to
trap moisture and prevent normal evaporation from occurring. Geotextile
fabrics can be used to limit the weed growth and allow for evaporation.
CONSTRUCTION MONITORING
Geotechnical Engineering Group should be retained to provide general review of
construction plans for compliance with our recommendations. Geotechnical Engineering
Group should be retained to provide construction testing services during earthwork and
foundation construction phases of the work. This is to observe the construction with
respect to the geotechnical recommendations, to enable design changes in the event
that subsurface conditions differ from those anticipated prior to start of construction and
to give the owner a greater degree of confidence that the structure is constructed in
accordance with the geotechnical recommendations.
LIMITATIONS
The scope of services for this study does not include either specifically or by
implication any environmental or biological (such as radon, mold, fungi, bacteria, etc.)
assessment of the site or identification or prevention of pollutants, biological hazards,
hazardous materials or conditions. If the owner is concerned about the potential for such
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contamination or pollution, other studies should be performed.
Two exploratory borings were drilled and sampled. The borings are representative
of conditions encountered only at the exact boring locations. Variations in the subsoil and
ground water conditions not indicated by the borings are always possible. Our
representative should observe open foundation excavations to confirm subsurface
conditions are as anticipated from the exploratory borings and foundations are prepared
as recommended herein. We should be called to test subgrade soils and structural fill
materials and compaction.
The scope of work performed is specific to the proposed construction and the
client identified by this report. Any other use of the data, recommendations and design
parameters (as applicable) provided within this report are not appropriate applications.
Other proposed construction and/or reliance by other clients will require project specific
review by this firm. Changes in site conditions can occur with time. Changes in standard
of practice also occur with time. This report should not be relied upon after a period of
three years from the date of this report and is subject to review by this firm in light of new
information which may periodically become known.
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GEG Job No. 5258
We believe this investigation was conducted in a manner consistent with that level
of care and skill ordinarily used by geotechnical engineers practicing in this area at this
time. No other warranty, express or implied, is made. If we can be of further service in
discussing the contents of this report or the analysis of the influence of the subsurface
conditions on the design of the residence, please call.
Sincerely,
Grand Valley Consulting, LLC dba
GEOTECHNICAL ENGINEERING GROUP
Chris Hill, P.E.
Project Engineer
Reviewed By:
64625
i 7/1012025
��4NAL
John Withers, P.E. '�i►°a,,p,�,,o4"
Engineer
(1 copy emailed)
Note: This report includes 17 pages text and 3 APPENDIXIES (34 pages total). It should
not be interpreted except in its entirety.
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APPENDIX A
FIELD EXPLORATION
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NOTE: THIS FIGURE WAS PREPARED BASED ON A SITE PLAN
PROVIDED BY CLIENT. DIAGRAM IS FOR GENERAL LOCATION - Indicates location of exploratory borings.
ONLY, AND IS NOT INTENDED FOR CONSTRUCTION
PURPOSES
Project Manager: Project No. JW 5258 LOCATIONS OF EXPLORATORY BORINGS FIG No.
P
Drawn by: Scale: .
CflH N.T.s 51 Boulder Ridge Drive
Date: e3eH.rtncr..la��.,u�nG Gr. J..U.n,CO815M Parachute, Colorado
A-2
7-7-2025 PH (We) 251d 15 J m- @ . t..hni.Jg—p.-
Field Exploration Description
The proposed boring locations were laid out in the field by a GEG engineer using aerial imagery,
stakes set in the ground by the client and measuring from available site features. The locations of
the borings should be considered accurate only to the degree implied by the means and methods
used to define them.
The borings were drilled with a truck -mounted rotary drill rig using continuous flight solid -stem augers
to advance the boreholes. Samples of the soil encountered in the borings were obtained using the
split -barrel and modified California barrel sampling procedures.
In the split -barrel and modified California barrel sampling procedure, the number of blows required
to advance the sampler the last 12 inches of the typical total 18-inch penetration by means of a
140-pound hammer with a free fall of 30 inches, is the standard penetration resistance value
(SPT-N). This value is used to estimate the in -situ relative density of cohesionless soils and
consistency of cohesive soils. The samples were tagged for identification, sealed to reduce
moisture loss, and taken to our laboratory for further examination, testing, and classification.
Information provided on the boring logs attached to this report includes soil descriptions, consistency
evaluations, boring depths, sampling intervals, and groundwater conditions. The borings were
backfilled with auger cuttings prior to the drill crew leaving the site.
An automatic SPT hammer was used to advance the split -barrel sampler in the borings performed
on this site. A significantly greater efficiency is achieved with the automatic hammer compared
to the conventional safety hammer operated with a cathead and rope. This higher efficiency has
an appreciable effect on the SPT-N value. The effect of the automatic hammer's efficiency has
been considered in the interpretation and analysis of the subsurface information for this report.
A field log of each boring was prepared by the staff engineer. These logs included visual
classifications of the materials encountered during drilling as well as the driller's interpretation of the
subsurface conditions between samples. Final boring logs included with this report represent the
engineer's interpretation of the field logs and include modifications based on laboratory observation
and tests of the samples.
Fig. A-3
LOCATION: See Figure A-2 ELEVATION: "
DRILLER: Lakota McCracken LOGGED BY: Chris Hill, P.E.
DEPTH TO WATER INITIAL: NATD AFTER 24 HOURS: Backfilled
DATE: 6-20-2025 DEPTH TO CAVING: -
DIAMETER: 4" Solid Stem TOTAL DEPTH: 24.5 Feet
o
Description
m
Notes
0
Clay, silty, sandy, stiff to very stiff, dry, brown and tan (CL)
4'
9'
14'
CAL
CAL
CAL
15/12
19/12
46/12
Bulk Sample From 0-5'
5
10
15
Gravel, clayey, sandy, very dense, dry, brown and tan (GM)
24'
CAL
50/3
Gravels Start at 19 Feet
20
25
Total Depth 24.5 Feet
30
35
This information pertains only to this boring and should not be interpreted as being indicative of the site
Project No.: 5258 LOG OF EXPLORATORY TEST BORING TH-1 Fig.
Client; Aaron Sifuentes
Drawn By: CDH ENGINEER R OGEOTECHNirA� 51 Boulder Ridge Drive
7-7-2025 832 North Crest Drive, Unit D A-4
Date: Parachute, Colorado
Grand Junction, CO 81506 (970) 261-3415
APPENDIX B
LABORATORY TESTING
Laboratory Testing
Soil samples were tested in the laboratory to measure their dry unit weight, natural water content,
grain size distribution (sieve analysis) and plastic characteristics (Atterberg Limits).
Swell/Consolidation tests of select samples were conducted to estimate soil response to loading
and wetting of the samples tested. The test results are included in Appendix B.
Descriptive classifications of the soils indicated on the boring logs are in accordance with the
enclosed General Notes and the Unified Soil Classification System. Also shown are estimated
Unified Soil Classification Symbols. A brief description of this classification system is attached to
this report. All classification was by visual manual procedures. Selected samples were further
classified using the results of gradation and Atterberg limit testing.
Fig. B-1
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13EDTECHNICAL
ENGINEERING GROUP
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Project No.: 5258
Drawn By: CDH
Client: Aaron Sifuentes
Date: 7-7.2025
SWELL -CONSOLIDATION TEST REPORT
200 300 500 1000 2000 3000 5000
Confining Pressure (psf)
832 North Crest Drive, Unit D, Grand Junction, CO 81506
(970) 261-3415
Test Results
Initial Consolidation = 0.6%
Swell/Consolidation = 0.1 %
Swell Pressures = 640 psf
Confining Pressure = 500 psf
TH-2 at 4 Feet Depth Fig
51 Boulder Ridge Drive B-3
Parachute, Colorado
MOISTURE -DENSITY
RELATIONSHIP TEST REPORT
Project No.: 5258
Project: 51 Boulder Ridge Drive
Elev./Depth:0-5 Feet
Source: TH-1 & TH-2
Remarks:
MATERIAL DESCRIPTION
Description: Clay, silty, sandy (CL)
Classification = USCS: (CL)
Nat. Moist. = 3.8%
Liquid Limit = 26%
140
130
120
.§
:m
70L
Date: 6-20-2025
Sample No. 1
SP.G. =
Plasticity Index = 8%
% < No.200 = 86%
Maximum Dry Density = 114 pcf
Optimum Moisture = 14.5%
Test specification:
ASTM D 696 Method A Standard
100% SATURATION CURVES
FOR SPECIFIC GRAVITY EQUAL TO:
7
5 10 15 20 25 30 35 40
Water content, % Fig. B-4
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APPENDIX C
SUPPORTING DOCUMENTS
GENERAL NOTES
DRILLING & SAMPLING SYMBOLS:
SS:
Split Spoon -1 3/e" I.D., 2" O.D., unless otherwise noted
HS:
Hollow Stem Auger
ST:
Thin -Walled Tube — 2" O.D., 3" O.D., unless otherwise noted
PA:
Power Auger (Solid Stem)
IRS:
Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted
HA:
Hand Auger
DB:
Diamond Bit Coring - 4", N. B
RB:
Rock Bit
BS:
Bulk Sample or Auger Sample
WB
Wash Boring or Mud Rotary
The number of blows required to advance a standard 2-inch O.D. split -spoon sampler (SS) the last 12 inches of the total 18-inch penetration
with a 140-pound hammer falling 30 inches is considered the "Standard Penetration" or "N-value".
WATER LEVEL MEASUREMENT SYMBOLS:
WL: Water Level WS: While Sampling BCR: Before Casing Removal
WCI: Wet Cave in WD: While Drilling ACR: After Casing Removal
DCI: Dry Cave in AB: After Boring N/E: Not Encountered
Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times
and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low
permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have
more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained
Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if
they are slightly plastic or non -plastic. Major constituents may be added as modifiers and minor constituents may be added according to
the relative proportions based on grain size. In addition to gradation, coarse -grained soils are defined on the basis of their in -place relative
density and fine-grained soils on the basis of their consistency.
CONSISTENCY OF FINE-GRAINED SOILS
Unconfined
Standard Penetration
Compressive
or N-value (SS)
Consistency
Strength, Qu, psf
Blows/Ft.
< 500
0-1
Very Soft
500 —1,000
2-4
Soft
1,000 — 2,000
5-8
Medium Stiff
2,000 —4,000
9 - 15
Stiff
4,000 — 8,000
16 - 30
Very Stiff
8,000+
> 30
Hard
RELATIVE PROPORTIONS OF SAND AND GRAVEL
Descriptive_Terms
Percent of
of other constituents
Dry Weiqht
Trace
< 15
With
15 — 29
Modifier
>_ 30
RELATIVE PROPORTIONS OF FINES
Descriptive_ TermTs
Percent of
of other constituents
Dry Weight
Trace
< 5
With
5-12
Modifier
> 12
RELATIVE DENSITY OF COARSE -GRAINED SOILS
Standard Penetration
or N-value (SS)
Relative Density
Blows/Ft.
0-3
Very Loose
4-9
Loose
10 — 29
Medium Dense
30— 50
Dense
> 50
Very Dense
GRAIN SIZE TERMINOLOGY
Major Component
Particle Size
of Sample
Boulders
Over 12 in. (300mm)
Cobbles
12 in. to 3 in. (300mm to 75mm)
Gravel
3 in. to #4 sieve (75mm to 4.75mm)
Sand
#4 to #200 sieve (4.75 to 0.075mm)
Silt or Clay
Passing #200 Sieve (0.075mm)
PLASTICITY DESCRIPTION
Term Plastici
Index
Non -plastic 0
Low
1-10
Medium
11-30
High
> 30
FIG. C-1
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
_
Soil Classification
Group
Symbol
Group Names
Coarse Grained Soils:
More than 50% retained
Gravels:
More than 50% of
coarse
fraction retained on
o. 4 sieve
Clean Gravels: Cu >_ 4 and 1 < Cc _< 3 E
Less than 5% fines c Cu < 4 and/or 1 > Cc > 3 E
GW
Well -graded gravel F
GP
Poorly graded gravel F
Gravels with Fines:
More than 12% fines °
Fines classify a
I fy s ML or MH
GM
Silty gravel F,G,H
Sil
classify
Fines classi as CL or CH
GC
CIa gravel
� YeY
on No. 200 sieve
Sands:
50% or more of coarse
fraction passes
No. 4 sieve
Clean Sands:
Less than 5% fines D
I Cu >_ 6 and 1 < Cc <_ 3 E
SW
Well -graded sand'
Cu < 6 and/or 1 > Cc > 3 E
SP
Poorly graded sand'
Sands with Fines:
More than 12% fines °
Fines classify as ML or MH
SM
Silty sand G.H.'
Fines Classify as CL or CH
SC
Clayey sand G.H.'
Fine -Grained Soils:
No. 200 0 sieve more passes the
No.
Silts and Clays:
Liquid limit less than 50
i
Silts and Clays:
Liquid limit 50 or more
Inorganic:
PI > 7 and plots on or above "A" line'
CL
Lean clay
PI < 4 or plots below "A" line'
ML
Silt'"-"
Organic:
Inorganic:
Liquid limit - oven dried
< 0.75
Liquid limit - not dried
PI ""
plots on or above Aline
OL
CH
Organic clay K,L,M,N
Organic silt K,L,M,O
ay I�X-1
Fat clay
PI plots below "A" line
MH
Elastic Silt KLM
Organic:
Liquid limit - oven dried
< 0.75
OH
Organic clay K,L,M,P
Liquid limit - not dried
Organic silt K,L,M,O
Highly organic soils:
Primarily organic matter, dark in color, and organic odor
PT
Peat
A Based on the material passing the 3-in. (75-mm) sieve
a If field sample contained cobbles or boulders, or both, add 'with cobbles
or boulders, or both" to group name.
Gravels with 5 to 12% fines require dual symbols: GW-GM well -graded
gravel with silt, GW-GC well -graded gravel with clay, GP -GM poorly
graded gravel with silt, GP -GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well -graded
sand with silt, SW -SC well -graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
z
E Cu = D60010 Cc = (D30)
D10 x D6o
F If soil contains >_ 15% sand, add 'with sand" to group name.
G If fines classify as CL-ML, use dual symbol GC -GM, or SC-SM.
60
For classification of fine-gralned
soils and fine-grained fraction
50
of coarse -grained soils
Equation of "A/(�LL-20)
d
Horizontal at P
W 40
then Pi�.73O
Equation of "UVertical
at LL=30
then PI-0.9 ('"020
i
io /
a
0
0 10 16 20
ML or OL
H If fines are organic, add 'with organic fines" to group name.
' If soil contains >_ 15% gravel, add 'with gravel' to group name.
If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add 'with sand" or'with
gravel," whichever is predominant.
L If soil contains >_ 30% plus No. 200 predominantly sand, add "sandy"
to group name.
M If soil contains >_ 30% plus No. 200, predominantly gravel, add
"gravelly" to group name.
" PI >_ 4 and plots on or above "A" line.
o PI < 4 or plots below "A" line.
P PI plots on or above "A" line.
° PI plots below "A" line.
W
30 40 50 60 70 so 90 100 110
LIQUID LIMIT (LL)
Fig. C-2
Footing or in case of deep J
foundation, bottom of grade beam.
*May also be extended to bottom of
structural fill in cases to help avoid
'bath tub' effect.
Encase pipe in washed concrete
aggregate (ASTM C33, No. 57 or
No. 67). Extend gravel at least
halfway up continuous footings
and void if pads or interrupted
footings are used
Project Manager. Project No.
JW 5258 ■
Drawn By: Scale:
arz Noel creep Dn.. Wid o crane gun .l . co 815W
CDHN.T.S. PH. (97r1)mi1 15 jMhe"&ede mlgroup nN
Note:
Drain should be at least 4 inches
below bottom of footing or
alternative deep foundation bottom
of grade beam at the highest point
and slope downward to a positive
gravity outlet or to a sump where
water can be removed by
pumping.
Provide positive slip joint
between slab and wall
Cover gravel with filter fabric
Or rootuty fell. Bottom of
" '+ Excavation
8�nre�o d� ram 1
4" Minimum
8" Minimum
or beyond
1:1 slope
from bottom
offooting
(Whichever is
greater).
flinch diameter perforated drain
pipe. The pipe should be placed
in a trench with a slope ranging
between 1/8-inch and 1/4-inch
drop per foot of drain
Interior Foundation Wall Drain Concept
51 Boulder Ridge Drive
Parachute, Colorado
FIG No.
C-3
Note:
Drain should be at least 4
inches below bottom of
footing or alternative deep
foundation bottom of grade
beam at the highest point
and slope downward to a
Slope per re rt positive gravity outlet or to a
sump where water can be
removed by pumping.
Backfill —\
Below grade wall
Slope per Reinforcing steel Footing or in case of deep
OSHA per structural drawings. foundation, bottom of grade
beam. *May also be
Cover gravel with extended to bottom of
filter fabric structural fill in cases to
or roofing felt. help avoid 'bath tub' effect.
6' Minimum
Encase pipe in washed concrete -
aggregate (ASTM C33, No. 57 or
No. 67). Extend gravel laterally
to void and as high as possible
up the side of void (1 to 2 inches).
Provide PVC sheeting glued
to foundation wall to reduce
moisture penetration.
8" Minimum or beyond 1:1
slope from bottom of
footing. (Whichever is
greater).
44nch diameter perforated drain
pipe. The pipe should be placed
in a trench with a slope ranging
between 1/8-inch and 1/4-inch
drop per foot of drain.
Project Manager: Project No. Exterior Foundation Wall Drain Concept FIG No.
Jw 5258 ■ 51 Boulder Ridge Drive
Drawn By: Scale: '' ' C_4
CDH �NW°MI-U1w°°°° G-@°-W.Ig-PnW Parachute, Colorado
N.T.S. PH (97p(261-3C15 jwAhere@gedecMiwlpraup nN