HomeMy WebLinkAboutSubsoils Report for Foundation DesignHuddleston-Berry
Engineering &. Testing, I-LC
2789 Riversids PalkwaY
Grand Junction, Colorado 81501
Phone: 970-255-8005
Info@huddlesonborry. com
January 16,2025
Project#0296 l-0001
Ms. Catherine Placek
68 Scutter Ridge Road
Rifle, Colorado 81650
Subject: Geotechnical Investigation
Lot 14 Rapids View Lane
New Castle, Colorado
Dear Ms. Placek,
This letter presents the results of a geotechnical investigation conducted by Huddleston-Berry
Engineering & Testing, LLC (HBET) for Lot 14 Rapids View Lane in New Castle, Colorado.
The site loiation is shown on Figure I - Site Location Map. 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 northern portion of the site was occupied by the Colorado
River. The remainder of site was open and gently sloping down to the north. Vegetation at the
site primarily consisted of weeds, grasses, and bushes and trees in the northem portion of the
site. The site was bordered to the north by the Colorado River, to the west by a residential
property, to the east by a vacant lot, and to the south by Rapids View Lane'
Subsurface Investigation
The subsurface investigation included three test pits atthe site as shown on Figure 2 - Site Plan.
The test pits were excavated to depths of 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.
The test pits encountered 1.0 foot of topsoil above tan, moist, stiff sandy lean clay soils that
extendedlo depths of between 3.0 and 5.0 feet below the existing ground surface, The clay soils
were underlain by tan, moist, dense gravel, cobble, and boulder soils in a poorly graded sand
with silt matrix that extended to the bottoms of the excavations. Groundwater was not
encountered in the subsurface atthe time of the investigation'
Laboratorv Testine
Laboratory testing was conducted on samples of the native soils collected from the test pits. The
testing included natural moisture content and density determination, grain-size analysis,
Atterberg limits determination, swell/consolidation testing, and maximum dry density and
optimum moisture content (Proctor) determination. The laboratory testing results are included in
Appendix B.
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The laboratory testing results indicate that the native clay soils are slightly plastic, In
addition, the native clay soils were indicated to be very slightly collapsible, with up to
approximately 0.IYo collapse measured in the laboratory.
The poorly graded sand with silt matrix soils in the gravel, cobbles, and boulders were indicated
to be nonlplastic. In general, based upon the Atterberg limits of the matrix soils and Llpon our
e*perience with similar soils in the vicinity of the subject site, the native gravel, cobble, and
boulder soils are anticipated to be fairly stable under loading.
Foundation Recommendations
Based upon the results of the subsurface investigation and nature of the proposed construction,
shallow foundations are generally recommended. Spread footings and monolithic (turndown)
structural slab foundations are both appropriate alternatives. However, as discussed previously,
the shallow native clay soils are slightly collapsible. Therefore, in order to provide a uniform
bearing stratum and reduce the risk of excessive differential movements, it is recommended that
the foundations be constructed above structural fill extending to the dense gravel, cobble, and
boulder soils. However, aminimum of 18-inches of structural fill is recommended.
The native clay soils, exclusive of topsoil, are suitable for reuse as structural fill. The native
gravel, cobble, and boulder soils are also suitable for reuse as structural fill; provided particles in
J*rr5 of 3-inches in diameter are removed. Imported structural fill should consist of a granular,
non.eXpanSiu",@materialwithgreaterthanI0%,passingthe#200sieveand
Liquid Lirnlt of t"ss ttt* :0. Ho*ever, 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 24-
inches below the tumdown edge s.S fill extend laterally beyond the edges ofthe
foundations a distance equal to the ss of structural fill for both foundation types.
Prior to placement of structural fill, it is recommended that the bottom of the foundation
excavation in the dense gravel, cobble, and boulder soils be scarified to a depth of 6 to 9 inches,
moisture conditioned, and proofrolled to HBET's satisfaction. Structural fill should be moisture
conditioned, placed in maxirnum 8-inch loose lifts, and compacted to a minimum of 95V" of the
standard Proctor maximum dry density for fine grained soils and 90Y, of the modified Proctor
maximum dry density for coarse grained soils, within + 2o/o of the optimum moisture content as
determined in accordance with ASTM D698 and D1557, respectively.
Structural fill should be extended to within O.l-feet of the bottom of the foundation. No more
than 0.I-feet of gravel should be placed below the footings or tumdown edge as a leveling
course
For structural fill consisting of the native soils or imported granular materials, and foundatron
building pad preparation as recommended, a maximum allowable bearing of
mav be used. In addition, a modulus of subgrade reaction of 150 pci may be
fill consisting of the native soils and a modulus of 200 pci may be used for suitable imported
structural fill Foundations subject to frost should be at least 36 inches below the finished grade
Huddleston-Berry
Entinooring! 1.sint, l-lc
Zr\2008 ALL PROJECT5\0296 1 - Catherine Pleek\0296 1-0001 Lot 14 Ropids View Lme\200 - Geo\0296 1-0001 LRol l625.doc 2
Lot 14 Rapids View Ln.
#02961-0001
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Water soluble Sulfates are common to the soils in Westem Colorado
lAw Huddleston-Betry
Eillinrorinsd htrinf,, LLC
Therefore, at a minimum,
cement adequate for Sulfate Exposure Class Sl is recommended for construction atthis site'
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
,."o*-*d that the walls be designed for an equivalent active 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. Cobble and boulder soils should be screened to
6-inch minus prior to use as backfill behind walls or around foundations.
Non-Structural Floor Slab and Exterior Flatwork Recommendations
In order to limit the potential for excessive differential movements of slabs-on-grade it is
recommended that non-structural floating floor slabs be constructed above a minimum of 18-
inches of structural fill. Prior to placement of structural fill where clay soils are present in the
subgrade, it is recommended that the bottom of the foundation excavation be scarified to a depth
of d to 9 inches, moisture conditioned, and compacted to a minimum of 95%o of the standard
Proctor maximum dry density, within + 2%o of the optimum moisture content as determined in
accordance with ASTM D698. It is recommended that exterior flatwork be constructed above a
minimum of l2-inches of structural fill.
Drainage Recommendations
Grutlins and drainuge are critical to the lons-term performance of the structure. Grading
around the strucflrrr-.h*rld 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 automitic irrigation, including drip lines, within ten feet of foundations be
rninimized.
HBET recommends that surface 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 drains. 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, the subsurface conditions encountered at the site were slightly variable.
However, the precise nature and extent of 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 builder 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.
-1Zl\2008 ALL PROJECTS\02961 - Catherine Pleek\02961-0001 Lot 14 Rapids ViewLme\200 - Geo\02961-0001 LRoll625 doc
Lot 14 Rapids View Ln. A#02e61-oool 6G$)****tl*lrs0r/t6/25 \g
It is important to note that the recommendations herein are intended to reduce the risk Qf
ffiiEI movement and/or tlamase, to varvins desrees, associated v'ith volryme qhanse of the
T cannot n-edict lons-term chanses in subsqrface moisture
agnitude or extent of volume change in the native soils. ll/here
ffiificant increases in subsurface moisture oc,cur due t! poor gradilrg. it4or?oer stomwdter
ets irrisation, or qther.cause, either during constructio,
opertv owner, seversl inches of movement ure possible, IJ.
ffiomnlv with the recommendations in this report reles.ses Huddleston-
@sfins. LLC of anv liabilitv with resard to the structure oerformance.
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.
Respectfully Submitted:
Huddleston-Berry Engineering and Testing, LLC
Michael A. Berry, P.E.
Vice President of Engineering
4
3 10
L6/
2:\2008 ALL PROJECTS\02961 - Catherine Pleek\o2961-000I Lot 14RapidsviewLile\200. Geo\02961-0001 LRoll625.doc
FIGURES
GURE 1
Location Map
R01 3191
21 B1 043001 25
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GURE 2
Plan
Huddleston-Berry Engineering & Testing, LIC
2789 Riverside ParkwaY
C:rand Junction, CO 81501
970-255-8005
PAGE 1 OF 1
TEST PIT NUMBER TP.1
PROJECT LOCATIONPROJECT NUMBER
PROJECT NAME Lot 14CLIENTCatherinePlacek oids View Lane
GROUND WATER LEVELS:
AT TIME OF EXCAVATION
AT END OF EXCAVATION
AFTER EXCAVATION -.-
TEST PIT SIZE
CHECKED BY
COMPLETED
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GROUND ELEVATION
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APPENDIX B
Laboratory Testing Results
GRAIN SIZE DISTRIBUTION
PROJECT LOCATIONPROJECT NUMBER
PROJECT NAME Lot 14 RaCLIENT.:alharina v
Riverside
Junction,
Parkway
co 81501
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Huddlestou-Beny Engineering & Testing, LLC
970-255-8005
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GRAIN SIZE IN MILLIMETERS
COBBLES
GRAVEL SAND SILT OR CLAY
coarse fine coa rse medium fine
PI Cc CuLLPLClassificationldentification
21 I29SANDY LEAN12t20TP-1 GB.1
NP 0.59 43.73NPNPGB-1 12120 POORLY GRADED SAND with SILT and
%sitt o/oC%Gravel %SandD30Dl0Dl 00 D60imen ldentificationS
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ATTERBERG LIMITS' RESULTS
PROJECT LOCATIONPROJECT NUMBER
PROJECT NAME Lot 14 RaCLIENTCatherine \/iew I ane
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2789 Riverside ParkwaY
Grand Junction, CO 8150I
970-255-8005
CONSOLIDATION TEST
PROJECT LOCATIONPROJECT NUMBER
PROJECT NAME l at 14 RanidcLIENT Catherine Placek
MC%aClassificationSpecimen ldentification
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2789 Riverside ParkwaY
Crrand Junction, CO 81501
970-255-8005
MOISTU RE.DENSITY RELATIONSH I P
PROJECT LOCATIONPROJECT NUMBER
PROJECT NAME latlACLIENTCatherine
Sample Date:
Sample No.:
Source of Material:
Description of Material:
12t20t2024
24-0865
TP.1.GB-,I
145
SANDY LEAN
Test Method (manual):ASTM D698A
140
135 TEST RESULTS
Maximum DrY DensitY 104'5 PCF
Optimum Water Content 16'0 %
130 GRADATION RESULTS (% PASSING)
#200 #4 314"
58 100 100
125
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ATTERBERG LIMITS
I 20
LL PL
21
PI
29
1'15 Curves ol 100o/o Saturation
for Specific GravitY Equal to
110
2.80
2.70
2.60
'105
100
95
5 15
WATER CONTENT, %
90
0 10 20 25 30