HomeMy WebLinkAboutGeotechnical Investigation 11.01.2023Huddleston-Berry
2789 Riverside Parkway
Grand Junction, Colorado 81501
Phone: 970-255-8005
Info @huddlestonberry. comEngineering & Testing, LLC
November 1,2023
Projecf#02734-0001
Grand Valley Drywallers, LLC
226EagLe Drive
Parachute, Colorado 8 I 63 5
Attention: Mr. Francisco Vicencio
Subject:6selsshni cal Investigation
41 Eagles Court
Parachute, Colorado
Dear Mr. Vicencio,
This letter presents the results of a geotechnical investigation conducted by Huddleston-Berry
Engineering & Testing, LLC (HBET) at 4l Eagles Court in Parachute, Colorado. The site
location is shown on Figure 1. The proposed construction is anticipated to consist of a new
single-family residence. 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 site was open with a general slight slope down to the north.
Vegetation consisted primarily of weeds and grasses. The site was bordered to the north, west,
and east by residential properties, and to the south by Eagles Court.
Subsurface Investigation
The subsurface investigation included one test pit as shown on Figure 2 - Site Plan. The test pit
was excavated to a depth of 7.5 feet below the existing ground surface. A typed test pit log is
included in Appendix A.
The test pit encountered 1.0 foot of topsoil above tan, moist, dense silty sand soils with gravels,
cobbles, and boulders to the bottom of the excavation. Groundwater was not encountered in the
subsurface at the time of the investigation.
Laboratory Testing
Laboratory testing was conducted on samples of the native soils encountered in the test pit. The
testing included grain size analysis, Atterberg limits determination, and natural moisture
content Gtermination. The laboratory testing results are included in Appendix B.
4l Eagles Court
#02734-0001
11/0v23
Ifsddlesaon-BElry
EnAinc{inA& Tc{irt. LLC
The laboratory testing results indicated that the native sand soils are slightly plastic. In general,
due to the presence of large particles and density of the material, the native sand soils are
anticipated to be fairly stable under loading.
f,'oundation Recommendations
Based upon the results of the subsurface investigation and nature of the proposed construction,
shallow foundations are recommended. Spread footings and monolithic (turndown) structural
slabs are both appropriate foundation alternatives. However, in order to provide a stable bearing
stratum and limit the potential for excessive differential movements, it is recommended that the
foundations be constructed above a minimum of l8-inches of structural fill.
The native soils, exclusive of topsoil, are suitable for reuse as structural fill; provided particles in
excess of 3-inches in diameter are removed. Imported structural fill should consist of a granular,
non-expansive, nonfug_Qryipigg material with greater than 10% passing the #200 sieve and
Liquid Limit of less than 30. However, all proposed imported structural fill materials should be
approved by HBET.
For spread footing foundations, the footing areas may be trenched. However, for monolithic slab
foundations, the structural fill should extend across the entire building pad area to a depth of 18-
inches below the turndown edges. Stnrctural fill should extend laterally beyond the edges of the
foundation a distance equal to the thickness ofstructural fill.
Prior to placement of structural fill, it is recommended that the bottom of the foundation
excavation be scarified to a depth of 6 to 9 inches, moisture conditioned, and compacted to a
minimum of 95o/o of the standard Proctor maximum dry density, within * 2o/o of the optimum
moisture content as determined in accordance with ASTM D698. Structural fill should be
moisture conditioned, placed in maximum 8-inch loose lifts, and compacted to a minimum of
95o/o of the standard Proctor maximum dry density for fine grained soils and 90o/o of the modified
Proctor maximum dry density for coarse grained soils, within L 2Yo of the optimum moisture
content as determined in accordance with ASTM D698 and D1557, respectively.
Stnrctural fill should be extended to within 0.l-feet of the boffom of the foundation. No more
than O.I-feet of gravel should be placed below the foofings 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 ol409!+sfrnay be
used. In addition, a modulus of 200 pci may be used for the native soils and/or approved
imported structural fill materials. Foundations subject to frost should be at least 36-inches bglow
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 45 pcf in
areas where no surcharge loads are present. An at-rest equivalent fluid unit weight of 65 pcf is
recommended for braced walls. Lateral earth pressures should be increased as necessary to
reflect any surcharge loading behind the walls.
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4l Eagles Court
#02734-000r
11/0|23
Water soluble sulfates are common to the soils in Western Colorado. Therefore, at a minimum,
Type I-II sulfate resistant cement 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 18-inches of structural fill
with subgrade preparation, structural fill materials, and fill placement be in accordance with the
Foundation Recommendations section of this report. It is recommended that exterior flatwork be
constructed above a minimum of l2-inches of structural fill.
I)rainaqe Recommendations
Gradine and drainaee are criticltl fo,r the lons-term per.formqryce of the structure 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 fwelve 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 imperrneable membrane is
recommended below subsurface downspout drain lines. Dry wells should not be used.
General Notes
The recommendations included above are based upon the results of the subsurface investigation
and on our local experience. These conclusions and recommendations are valid only for the
proposed construction.
As discussed previously, only one test pit was conducted at the site. Therefore, the precise
nature and extent of any subsurface variability may not become evident until construction. As a
result, it is recommended that HBET provide construction materials testing and engineering
oversight during the entire construction process. In addition, the homeowner and any
subcontractors working on the project should be provided a copy of this report and informed of
the issues associated with the presence of moisture sensitive subgrade materials at this site.
It is important to note that the recommendations herein are intended to reduce the risk of
structural movement and/or damage. to varviltg,degrees. associated with anv volume change
of the native soils. However,IIBET cannot nredict long-term changes in subsurface moisture
conditions and/or t4e or,ecise masnitqde or extent of volun e chanse. Where sisnificant
increases in suhsurface moisture occur due to poor grading. improner stormwater
manasement, utilitv line failure, excess irrisation. or other cause. either durins constrqction
or the result of actions of the nrooertv owner. several ,inches of movement arc nossible. In
addition, anv fgilufe to complv with the recommendations in this report releases Huddleston-
Berrv Ensineerins & Tesrins. LLC of anv liahilitv with resard to the structure nerformance.
Iluddlestm-Ber:r
fngir.dring& T.{int, LLC
3Z:V008 ALL PROJECTS\02734 - cmnd Valley Drywallem, LLC\02734-0001 41 Eagles Courtuo0 - Ceo\027321-0001 LRI l0l23.doc
4l Eagles Court
#02734-0001
11/01/23 @*,******
We are pleased to be of service to your project. Please contact us if you have any questions or
comments regarding the contents of this report.
Respectfu lly Submitted :
Huddleston-Berry Engineering and Testing, LLC
Michael A. Berry, P.E.
Vice President of Engineering
4Z:U008 ALL PROJECTS\02734 - Gmnd Valley Drywallen, LLC\02734-0001 4l Eagles CourtU0O - Geo\02734-0001 LRI l0l23.doc
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APPENDIX A
Typed Test Pit Log
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Laboratory Testing Results
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Huddleston-Berry Engineering & Testing, LLC GRAIN SIZE DISTRIBUTION
Riverside Parkway
Junction, CO 81501
97G.255-8005
CUENT Grand Vallev Drvwallers. LLC PR(IJECT }{AttE 41 Eaqles Court
PRO'EGT NUMBER o273+OOO1 PRO.TECT LOCAflON Parachute, CO
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Huddleston-Berry Engineering & Testing LLC ATTERBERG LIMITS' RESULTS
Riverside Parkway
Junction, CO 81501
970-255-8005
CUENT Grand Valley Drvwallers, LLC PRO.TECT }.lA,trlE 41 Eaqles Gourt
PR(UECT NUilBER 02734-0001 PROJECT LOCATION Parachute. CO
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