HomeMy WebLinkAboutGeotechnical Investigation 06.06.2024Qecakuy'
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Huddleston-Berry
Engineering & Testing, LLC
2789 Riverside Parkway
Grand Junction, Colorado 81501
Phone: 970-255-8005
Info@huddlestonberry. com
June 6,2024
Project#02038-001 1
MIB Construction
789 25 Road
Grand Junction, Colorado 81505
Affention: Mr. Micah Berg
Subject Geotechnical Investigation
Parcel 217534300219
Rulison, Colorado
Dear Mr. Berg,
This letter presents the results of a geotechnical investigation conducted by Huddleston-Berry
Engineering & Testing,LLC (HBET) at Parcel 217534300219 in Rulison, 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 eastem portion of the site was occupied by an active natural
gas well. The remainder of the site was open and contained slight to moderate slopes down to the
north, east, and south, away from the investigated arca. The site was bordered to the north, west,
and east by rural residential properties, and to the south by federal land.
Subsurface nvesfioafion
The subsurface investigation included three test pits as shown on Figure 2 - Site Plan. The test
pits were excavated to depths of 6.0 and 7.0 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 fairly consistent.
The test pits encountered 0.5 feet of topsoil above tano moist, medium stiff sandy lean clay soils
to depths of between 2.0 and 6.5 feet below the existing ground surface. The clay soils were
underlain by tan to brown, moist, medium stiff to stiff sandy lean clay soils with trace gravel and
cobbles to the bottoms of the excavations. Groundwater was not encountered in the subsurface
at the time of the investigation.
Laboratorv Testing
Laboratory testing was conducted on samples of the native soils encountered in the test pits. The
testing included grain size analysis, Atterberg limits determination, natural moisture content
determination, 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 indicated that the netive clay soils are moderately plastic. In
general, based upon the Atterberg limits and our experience with similar soils in the vicinity of
the subject site, the native clay soils are anticipated to be slightly expansive.
Foundation 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, as discussed previously, the native
soils are anticipated to be slightly expansive. Therefore, 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 24-inches of structural fill. If a basement is
proposed, HBET should be contacted to evaluate the subsurface conditions below the basement
foundation elevation.
Due to their plasticity, the native soils are not suitable for reuse as structural fill. Imported
structural fill should consist of a granularo non-expansive, non-free druining material with
greater than l0o/o passing the #20Q 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 24-
inches below the turndown edges. Structural fill should extend laterally beyond the edges of the
foundation a distance equal to the thickness of struotural 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 + 2oA 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
95Yo of the standard Proctor maximum dry density for fine grained soils and 90%o of the modified
Proctor maximum dry density for coarse grained soils, within + 2Yo 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 O.l-feet of gravel should be placed below the footings or turndown edge as a leveling
course.
For structural fill consistiug of approved imported granular materials and foundation building
pad preparation as recommended, a maximum allowable bearing capacity ofJdQ0 g$.rqay be
used. In addition, a modulus of 200 pci may be used for approved imported structural fill
materials.Foundationssubjecttofrostshouldbeatleastalru::thefinishedgrade.
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. Laterul earth pressures should be increased as necessary to
reflect any surcharge loading behind the walls.
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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 24-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.
Drainage Recommendations
Gradine and drainage are critical for the lons-term performunce 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 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. [n addition, an impermeable membrane is
recommended below subsurface downspout drain lines. Dry wells should not be used.
In order to limit the potential for surface moisture to adversely impact the structure, a perimeter
foundation drain is recommended. In general, the perimeter foundation drain should consist of
prefabricated drain materials or perforated pipe and gravel with the flowline of the drain at the
bottom of the foundation (at the highest point). The prefabricated drain materials or gravel
should extend along basement walls to within 36-inches of the finished grade. The perimeter
drain should slope at a minimum of I .0o/o to daylight or to a sump with pump. The drain should
also include an impermeable membrane at the base to limit the potential for moisture to infiltrate
vertically down below the foundations.
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 in the test pits were fairly
consistent. However, 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.
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Parcel 217 534300219
#02038-001 1
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It is important to note that the recommendations herein are intended to reduce the risk of
structursl movement and/or damsge. to varving degrees, associated with volume chqnge of the
native soils. However, HBET cannot predict lone-term chanses in subsurface moisture
t:rttttlilittrts tlrttlhtr'flt,p. nret:ise masnilude or pxteilt of volune dtailse ln the nntivp sttils.IYhere
significant increases in suhsurface moisture. nccur due,lo nonr gradine, imnrone.r stormutate,r
management, utilitv line failure, excess irrieation, or other cause, either during construction
or the result of actions of the propertv owner, severul inches of movement are possible. I!
addition, anv failure to comnlv with the recommendations in this report releases Huddleston-
Berrv Ensineerins & Testins, LLC of anv liabilitv h,ith resard to the structure performance.
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
4Z:\2008 ALL PROJECTS\02038 - MIB\02038-001 I Prccl 2175343002 l9\200 - Ceo\02038-001 I LR060624.doc
FIGURES
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Date created: 5/ IO/2024
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FIGURE I
Site Location Map
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Site Location Map
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FIGURE 2
Site PlanDate created: 5/ LO/2O24
Last Data Uploaded: 5/ !O/2O24 2:43:37 AM
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APPENDIX A
Typed Test Pit Logs
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Huddleston-Berry Engineering & Testing, LLC TEST PIT NUMBER TP.2
PAGE 1 OF 1789 Riverside Parkway
Junction, CO 81501
970-255-8005
CLIENT MIB Construction PROJECT MME Parcel 217534300219
PROJECT NUMBER 02038-001 1 PROJECT LOCATION Rulison. CO
DATE STARTED 5I1OI24 COMPLETED 5/10/24 GROUND ELEVATION TEST PIT SIZE
EXCAVATION CONTRACTOR Client GROUND WATER LEVELS:
AT I'IME OF EXCAVATION
AT END OF EXCAVATION
AFTER EXCAVATION ._
EXCAVATION METHOD Trackh/Backhoe Drv
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APPENDIX B
Laboratory Testing Results
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Huddleston-Berry Engineering & Testing, LLC GRAIN SIZE DISTRIBUTION
789 Riverside Parkway
Junction, CO 81501
970-255-8005
CLIENT MIB Construction PROJECT MME Parcel 217534300219
PROJECT NUMBER 02038-0011 PROJECT LOCATION Rulison, CO
U,S. SIEVE OPENING IN INCHES I6 4 3 21.5 1314 112318 3 4 6
U.S. SIEVE NUMBERS HYDROMETER
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85
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GRAIN SIZE IN MILLIMETERS
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GRAVEL SAND SILT OR CLAY
coarse fine coarse medium fine
Specimen ldentification Classification LL PL PI Cc Cu
o TP-1, GB-l 5/10 SANDY LEAN GLAY(CL)u 22 12
Specimen ldentification D100 D60 D30 D10 %Gravel %Sand %sitt
o TP-1, GB-l 5110 2.36 0.088 0.0 4.7 55.3
Huddleston-Berry Engineering & Testing, LLC ATTERBERG LIMITS' RESULTS
I
970-25s-800s
CLIENT MIB Construction PRo.JECT MME Parcel 217534300219
PROJECT NUMBER 02038-001 1 PROJECT LOCATION Rulison. CO
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Specimen ldentification LL PL PI #200 Classification
a TP.l, GB.1 5110 u 22 12 55 SANDY LEAN CLAY(CL)
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PROJECT I{AME I
CLIENT
& Testing, LLC
?1
MO ry RE LA TIONS H IP
PROJECT NUMBER
PROJECT LOCATION
970-255-8005
Sample Date:
Sample No.:
Source of Material:
Description of Material:
5t10t2024
145 24-0306
TP.1 GB-1
LEAN crA
140 Test Method (manual)ASTM D698A
135 TEST RESULTS
Maximum Dry Density IOO.S pCF
Optimum Water Content - nn- n130
GMDATTON RESULTS (% PASSTNG)
#200 #4
100
314"
100
25
55
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o_tF6zt!o 20 ATTERBERG LIMITS
E.o LL PL PIu22 12
Curves of 100o/o Saturation
for Specific Gravity Equalto:
115
110 2.80
2.70
2.60
105
100
95
90
5 15
0 10
WATER CONTENT , o/o
20 25 30