HomeMy WebLinkAboutSubsoils Report for Foundation Designr ti
Huddleston-Berry
Engineering & Testing, LLC
Stephen and Jennifer Wells
540 Panoramic Drive
Silt, Colorado 81652
Subject: Geotechnical Investigation
540 Panoramic Drive ADU
Silt, Colorado
Dear Mr. and Mrs. Wells,
2789 Riverside 41arkway
Grand Junction, Colorado 91501
Phone: 970-255-9005
Info(M,huddlestonberry.com
April 21, 2025
Project#02997-0001
This letter presents the results of a geotechnical investigation conducted by Huddleston-Berry
Engineering & Testing, LLC (HBET) at 540 Panoramic Drive in Silt, Colorado. The site
location is shown on Figure 1. The proposed construction is anticipated to consist of a new
Accessory Dwelling Unit (ADU). The scope of our investigation included evaluating the
subsurface conditions at the site to aid in developing foundation recommendations for the
proposed construction.
Site Conditions
At the time of the investigation, the western and eastern portions of the site were occupied by an
existing residence and a pond, respectively. The remainder of the site was open and generally
sloping down from the west and east to the south of the pond. Vegetation consisted primarily of
weeds, grasses, and sparse trees. The site was bordered to the north, west, and east by rural
residential/agricultural properties, and to the south by Panoramic Drive.
Subsurface Investigation
The subsurface investigation included six test pits as shown on Figure 2 — Site Plan. The test pits
were excavated to depths of between 6.0 and 8.0 feet below the existing ground surface. Typed
test pit logs are included in Appendix A.
As indicated on the logs, the subsurface conditions encountered at the site were slightly variable.
Test Pits TP-1, TP-2, and TP-3, conducted to the west of the pond, encountered 1.0 foot of
topsoil above brown, moist to wet, medium stiff to soft lean clay with sand soils that extended to
the bottoms of the excavations. Groundwater was encountered in TP-1, TP-2, and TP-3 at depths
of between 4.0 and 7.0 feet below the existing ground surface.
Test Pits TP-4, TP-5, and TP-6, conducted to the east of the pond, encountered 1.0 foot of topsoil
above brown to reddish -brown, moist to wet, medium stiff to soft sandy lean clay soils that
extended to a depth of 4.5 feet in TP-4 and to the bottoms of the excavations in TP-5 and TP-6.
The lean clay soils in TP-4 were underlain by brown to gray, moist, medium dense clayey sand
soils that extended to the bottom of the excavation. Groundwater was not encountered in TP-4;
however, groundwater was encountered in TP-5 and TP-6 at respective depths of 5.0 and 6.0 feet
at the time of the investigation.
540 Panoramic Drive ADU +P""`
Huddl
#02997-0001 tston-Berry
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Structural fill should be moisture conditioned, placed in maximum 8-inch loose lifts, and
compacted to a minimum of 95% of the standard Proctor maximum dry density for fine grained
soils or modified Proctor maximum dry density for coarse grained soils, within f2% of the
optimum moisture content as determined in accordance with ASTM D698 or D1557C,
respectively. Structural fill should be extended to within 0.1-feet of the bottom of the
foundation. No more than 0.1-feet of gravel should be placed below the footings or turndown
edge as a leveling course.
For structural fill consisting of approved imported granular materials and foundation building
pad preparation as recommended, a maximum allowable bearing capacity of 1,500 Dsf may be
used. In addition, a modulus o pet may a use or approve imported stnlctural fill -
materials. Foundations subject to frost should be at least 36-inches below the finished grade.
Any stemwalls or retaining walls should be designed to resist lateral earth pressures. For backfill
consisting of the native soils or imported granular, non -free draining, non -expansive material, we
recommend that the walls be designed for an active equivalent fluid unit weight of 55 pcf in
areas where no surcharge loads are present. An at -rest equivalent fluid unit weight of 75 pcf is
recommended for braced walls. Lateral earth pressures should be increased as necessary to
reflect any surcharge loading behind the walls.
Water soluble sulfates are common to the soils in Western Colorado. Therefore, at a minimum,
cement adequate for Sulfate Exposure Class S 1 is recommended for construction at this site.
Non -Structural Floor Slab and Exterior Flatwork Recommendations
In order to reduce the potential for excessive differential movements, it is recommended that
non-structural floating floor slabs be constructed above a minimum of 24-ind tructural fill
With SD iIde nrenara ton. structura 1 materla s. au i p acemeni be in accordance with the
Foundation Recommenrepnrr_ It tS rc
constructs above 'l nirrti fl2�irs -ef s# rctura]�'iU.
Drainage Recommendations
Grading and drainage are critical fdr the to►a -ter►n perfur►nance of the slructrrre and grading
around the structure should be designed to carry precipitation and runoff away from the,
structure. It is recommended that the finished ground surface drop at least twelve inches within
the first ten feet away from the structure. It is also recommended that landscaping within five
feet of the structure include primarily desert plants with low water requirements. In addition, it
is recommended that irrigation, including drip lines, within ten feet of foundations be minimized.
HBET recommends that downspout extensions be used which discharge a minimum of 15 feet
from the structure or beyond the backfill zone, whichever is greater. However, if subsurface
downspout drains are utilized, they should be carefully constructed of solid -wall PVC and should
daylight a minimum of 15 feet from the structure. In addition, an impermeable membrane is
recommended below subsurface downspout drain lines. Dry wells should not be used.
V:\2009 ALL PROJECTS\02997 - Stephen and Jennifer Wells\02997-0001 540 Panoramic Drive\200 - Oeo\02997-0001 LR041625.doc 3
FIGURES
#NgPublic.net" Garfield County, CO
FIGURE 2
Dateveated 4/16/2025 Site Plan
Last Data Uploaded: 4/16/20252:07:16 AM
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Huddteston-Berry Engineering & Testing, LI.0 TEST PIT NUMBER TP-1
2789 Riverside Parkway PAGE 1 OF 1
Grand Junction, CO 81501
970-255-8005
CLIENT _S n and Jennifer Wells PROJECT NAME 540 Panoramic Drive
PROJECT NUMBER 02997-0001 PROJECT LOCATION Silt CO
DATE STARTED 3/18125 COMPLETED 3/18/25 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR Wiseland GROUND WATER LEVELS:
EXCAVATION METHOD Trackh/Backhoe Q AT TIME OF EXCAVATION 7.0 It
LOGGED BY TC CHECKED BY MAB AT END OF EXCAVATION 7-0 ft
NOTES AFTER EXCAVATION
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Lean Clay with Sand and Organics (TOPSOIL)
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Huddleston-Beery Engineering & Testing, LLC TEST PIT NUMBER TP-5
2789 Riverside Parkway PAGE 1 OF 1
Grand Junction, CO 81501
970-255-8005
CLIENT Stephen and Jennifer Wells PROJECT NAME 540 Panoramic Ddye
PROJECT NUMBER 02997-0001 PROJECT LOCATION Sill, CO
DATE STARTED 3/18125 COMPLETED 3118/25 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR Wiseland GROUND WATER LEVELS:
EXCAVATION METHOD Trackch/Baekhoe Q AT TIME OF EXCAVATION 5.0 ft _
LOGGED BY TC CHECKED BY MAS 1 AT END OF EXCAVATION 5.0 It
NOTES AFTER EXCAVATION —
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Sandy Lean Clay with Organics (TOPSOIL)
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Sandy Lean CLAY (d), brown, moist to wet, medium stiff to soft
Bottom of test pit at 6.0 feet.
APPENDIX B
Laboratory Testing Results
Huddleston-Ben y F.nginecring & Testing, LLC
2799 Riverside Parkway
Grand Junction, CO 81501
970-255-8005
CLIENT Stephen and Jennifer Wells
PROJECT NUMBER 02897-0001
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CONSOLIDATION TESL
PROJECT NAME 540 Panoramic Drive
PROJECT LOCATION Silt CO
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Specimen Identification
01 TP-4, MC-1 2.0
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Classification
10,000
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1081 14