HomeMy WebLinkAbout20070871.tiff Geotechnical Exploration Report for
Proposed Carr Community Church Building
9433 Gray Avenue
Carr, Colorado
Prepared For:
_ Carr Community Church
P.O. Box 55
Carr, CO 80612
—
Prepared By:
Laube Engineering, LLC
6250 W 10th Street, Ste 3
Greeley, CO 80634
(970) 356-3099
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Project No. 253
February 28, 2005
2007-0871
LAUBE 6250 W 10i° Street, Ste 3
Greeley, CO 80634-8856
ENGINEERING, LLC Telephone: (970) 356-3099
Fax: (970) 356-3143
February 28, 2005 Project No.: 253
Carr Community Church
_ do Ken Gunter
P.O. Box 55
Carr, CO 80612
Subject: Geotechnical Exploration Report
Proposed New Church Building
9433 Gray Avenue
Carr, Colorado
Dear Mr. Gunter:
Enclosed is a geotechnical report performed per our Agreement dated January 25, 2005 and
signed February 1, 2005. Please provide a copy of this report to your structural engineer for
foundation design. This report should be submitted to Weld County for their records and for
issuing a building permit.
It has been a pleasure being part of your project. If you have any questions, please call me at
(970) 356-3099.
Sincerely,
LAUBE ENGINEERING, LLC
.. .EST_.
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Keith A. Laube, P.E.
Civil/Geotechnical Engineer
Table of Contents
1 PROJECT INFORMATION 1
2 FIELD EXPLORATION 1
2.1 Sampling 1
2.2 Groundwater 2
3 LABORATORY TESTS 2
4 SUBSURFACE CONDITIONS 2
5 CONCLUSIONS AND RECOMMENDATIONS 2
5.1 Site Preparation and Earthwork 2
5.2 Foundations 3
5.3 Floor Slabs 4
5.4 Exterior Concrete 4
5.5 Underground Utilities 5
5.6 Construction Considerations 5
5.7 General Recommendations 5
6 CLOSURE 6
APPENDIX 7
Laube Engineering, LLC
Page 1
] Project Information
The purpose of this exploration was to provide foundation and earthwork recommendations
based upon soil samples obtained from two soil borings performed at the proposed building
location. You have informed us that the proposed building will be a single-story structure
without a basement. The new building will have a footprint of approximately 30 feet by 50 feet
and will be located 15 feet west of the existing church building. The foundation is anticipated to
consist of a perimeter foundation wall founded on continuous spread footings.
The proposed site is located 9433 Gray Avenue, Carr, Colorado. The site is on the north side of
Gray Avenue, between 4th Street and 5th Street. Gray Avenue is located approximately ''A mile
south of Weld County Road 126. The site is more specifically located in the north 'A of Section
27, Township 11 North. Range 67 West of the 6th Prime Meridian in Weld County. Colorado.
The site presently consists of a grass area and the topography is relatively level.
2 Field Exploration
The field exploration was performed on February 18, 2005, using 4-inch diameter continuous
flight augers powered by a truck mounted drilling rig. Two (2) soil borings were advanced to a
depth of 15 feet each within the staked building location. The approximate locations of the soil
borings are shown on the Boring Location Plan in the Appendix.
2.1 Sampling
A geotechnical engineer from Laube Engineering was present during drilling and sampling. A
field log was prepared by visually classifying the samples. The samples were sealed in zip locked
bags to prevent moisture loss and transported to our soil laboratory for further testing. Drilling
and sampling was performed according to the following standard procedure:
Sampling with a 2-inch outside diameter, split barrel (split spoon) sampler per ASTM
D1586 — "Penetration Test and Split Barrel Sampling of Soils". The standard penetration
test (SPT) results. "N" values, are shown on the Boring Logs. Fight (8) such tests were
performed.
Laube Engineering, LLC
_ Page 2
2.2 Groundwater
Ground water measurements were made upon completion of drilling and approximately 1 hour
later. Groundwater was not encountered within the boring termination depth of 15 feet.
3 Laboratory Tests
The following tests were performed on selected samples for classification and engineering
purposes:
Visual Classification Sieve Analysis
Moisture Content
The Sieve Analysis test result is presented in the Appendix. The remainder test results are
provided on the Boring Logs. The Boring Logs contain both factual and interpretive information.
The horizontal lines between soil layers on the Boring Logs represent approximate boundaries
between soil types. The transition between soil layers is typically gradual.
4 Subsurface Conditions
In general, the soils at the boring locations consist of loose to medium dense, silty sand with
gravel extending from the surficial topsoil to a depth of about 3 to 6 feet. Medium dense to
dense, poorly graded sand with silt and gravel was encountered extending from the silty sand to
the boring termination of 15 feet. Groundwater was not encountered within 15 feet of the surface
at the time of the exploration.
5 Conclusions and Recommendations
It is our opinion that the sandy soils exhibit adequate bearing capacity for the proposed
construction of the church building. Based our understanding of the project and data obtained
from the exploration, we make the following recommendations.
5.1 Site Preparation and Earthwork
I) Topsoil, weeds, surficial organic material, and soils containing organics and roots should
be removed from the proposed construction area.
Laube Engineering. LLC
Page 3
` 2) All footing and slab subgrades should be scarified at least 6 inches, moistened and
compacted to at least 95% of the Standard Proctor maximum dry density (ASTM D698).
3) Fill in areas of proposed buildings, structures, slabs, pavements, or walks should consist
of non-expansive, well-graded sand and gravel meeting approval of the geotechnical
engineer. Granular fill should be placed in maximum 8-inch lifts and compacted to at
least 95% of the Standard Proctor maximum dry density and within 3% of the optimum
moisture content as determined by ASTM D698. Fill materials should be tree of frozen
material, dried clods, organic matter and material greater than 3 inches in diameter.
4) Fill in areas outside of the influence of buildings. structures, slabs, and walks may consist
of non-organic soils available on site and should be compacted to at least 90% of the
Standard Proctor maximum dry density and within 2% of the optimum moisture content
as determined by ASTM D698.
5.2 Foundations
1) We recommend that the church building be supported by conventional spread footings
(continuous strip and/or individual pad footings) founded directly on the medium dense
sandy soils or on compacted granular fill material placed in accordance with section 5.1
Site Preparation and Earthwork.
2) Footings founded on the medium dense sandy soils or on compacted fill may be designed
based on a maximum net allowable soil bearing pressure of 2.000 pounds per square foot
(psf). Total settlement is estimated to be less than 1 inch and differential settlement is
estimated to be V2 to 3/4 of an inch.
3) Footings should be placed at a minimum depth of 30 inches below final exterior grade for
frost protection.
4) Footings should be sized to minimize differential movement. We recommend that
continuous spread footings be a minimum 16 inches wide and pad footings be at least 24
inches wide.
Laube Engineering, LW
Page 4
5) We recommend that footing subgrades be observed by a geotechnical engineer from our
office prior to placement of fill or concrete. Observation during construction verifies if
subsoils are consistent with the conditions revealed in the borings and provides an
opportunity for site specific recommendation if unsuitable subgrade conditions are
encountered.
6) Exterior foundation wall backfill not supporting walks, drives, or other structures should
be compacted to at least 90% of the Standard Proctor maximum dry density and within
2% of the optimum moisture content as determined by ASTM D698.
5.3 Floor Slabs
1) A minimum of 4 inches of free-draining aggregate should be placed directly beneath
slabs to provide uniform support and act as a capillary moisture break. The aggregate
should be compacted to at least 95% of the Standard Proctor maximum dry density
(ASTM D698).
2) Concrete slabs should be designed in accordance with current American Concrete
Institute (ACI) guidelines.
5.4 Exterior Concrete
1) A minimum of 4 inches of free-draining aggregate should be placed directly beneath
slabs to provide uniform support and act as a capillary moisture break. The aggregate
should be compacted to at least 95% of the Standard Proctor maximum dry density
(ASTM D698).
2) Exterior concrete should be sloped at least 1% (1/8 inch per foot) to provide adequate
surface drainage.
3) Concrete exposed to weather should be air-entrained to minimize frost damage. We
recommend that de-icing salt be avoided during the first year after construction.
Lauhe Engineering, LLC
Page 5
5.5 Underground Utilities
1) Buried water bearing utilities should be located below frost depth. Water lines should
have at least 4'/ feet of cover and sanitary sewer (septic lines) should have at least 3 feet
of cover, unless protected with insulation.
2) Utility trench backfill should be compacted to at least 90% of the Standard Proctor
maximum dry density and within 2% of the optimum moisture content (ASTM D698)
from 1 foot above the conduit to the final surface grade to minimize subsidence. Beneath
structures, walks, drives, and pavements, backfill should consist of approved granular
material compacted to least 95% of the Standard Proctor maximum dry density and
within 3% of the optimum moisture content as determined by ASTM D698.
5.6 Construction Considerations
I) Trench/excavation spoil. heavy equipment, and vibrating equipment should not be
permitted within a lateral distance of 'h the depth of the trench/excavation or within 3
feet, whichever is greater.
2) Excavation safety is the contractor's responsibility and should be conducted in strict
adherence to OSHA and other applicable codes.
3) Surface water should be directed away from open excavations and should not be allowed
to pond. The sandy soils that comprise the subgrade may soften or loosen if they become
wet. Any soils that become wet, loose, or disturbed should be removed and replaced with
compacted soils or the footing should be deepened to adequate bearing soils.
4) Special precautions should be taken for earthwork during cold weather periods. Footings,
slabs, and fill material should not be placed on frozen soils. Exposed subgrade soils
should be adequately protected with insulating blankets or hay.
5.7 General Recommendations
1) Foundations, floor slabs. and above grade structures should be designed by a qualified
structural engineer licensed in the State of Colorado.
Laube Engineering. LLC
Page 6
2) Rainwater from roofs and exterior concrete flatwork should be directed away from
structures. Permanent surface grades should provide adequate surface drainage away
from buildings. Final surface grades should slope away from buildings a minimum of
10% for a minimum distance of 10 feet (minimum 1 foot of vertical fall in 10 feet of
horizontal distance). Due to difficulty of obtaining proper compaction of wall backfill,
some settlement of the backfill may occur. Surface grades around the building should be
monitored during the first few years, and if required, additional backfill material may be
needed to maintain surface drainage away from the building.
3) Underground sprinkler systems should be installed at least 5 feet from foundations and
should not spray water within 5 feet of foundations. Landscape irrigation should be
minimized or eliminated within 5 feet of foundations and trees should not be planted any
closer than 15 feet from foundations.
6 Closure
This report was prepared for Carr Community Church for evaluation of the site for design and
—
construction of the proposed project. This report was prepared in accordance with generally
accepted soil and foundation engineering practices. No warranties are made, either expressed or
implied. The analysis and recommendations in this report are our opinions based upon the data
obtained from the field exploration. Variations may exist between soil borings or beneath the soil
boring termination depth. Such variations may not become evident until excavation or
construction. To determine if soil conditions revealed during construction are consistent with
those disclosed by the soil borings, we recommend that subgrades be observed by a geotechnical
engineer from our office prior to placement of fill or concrete.
Any reference to American Society for Testing and Materials (ASTM) methods in this report
shall apply only to the specified test. Referenced documents listed in the specified ASTM are not
to be implied or inferred.
The report may contain insufficient information for other uses or applications. Laube
Engineering should be notified if changes in the proposed project, building location, or design
are contemplated.
Laube Engineering, LLC
Page 7
Appendix
Site Location Map
Boring Location Plan
General Notes and Report Terminology
Boring Logs
Sieve Analysis
—
Laube Engineering, LLC
Site Location Map •
N
Proposed Carr Community Church Building
9433 Gray Avenue
Carr, Colorado
(North 'A, Section 27, Township I IN ,Range 67 West, 61h P.M., Weld County, Colorado)
U l 300m
900ft
126
126
Warner Ave Can
co
G+ay Ave
Paden Ave
McGuire Ave
Roosevelt St
2t
'9 5
124
- BORING LOCATION PLAN
Proposed Carr Community Church Building
9433 Gray Avenue
Carr, Colorado
— T
- N
PLAN
(NOT TO SCALE)
.-. 81
0 BOREHOLE, TYPICAL
- I 30' F
B10
PROPOSED EXISTING
50' CHURCH CHURCH
BUILDING BUILDING
15'
0B2
1
I-
50'
r
GRAY AVENUE
General Notes & Report Terminology
Abbreviations used on the boring logs
CAL: California lined tube sampler(3.0 inch outside diameter,2.5 inch inside diameter)
DD: dry density
LL: liquid limit(%)
N: "N" value, the blowcount representation of the penetration resistance of the soil
P200: percent passing the No. 200 sieve(0.075 mm)
PI: plasticity index (%)
PL: plastic limit(%)
SS: split spoon sampler(2.0 inch outside diameter, 1.375 inch inside diameter)
SSA: solid stem auger
SPT: standard penetration test
The soil penetration resistance (N) is the summation of the number of blows required to drive the 2-inch outside
diameter sampler 12 inches with a 140-pound hammer falling 30 inches. The number of recorded blows
commences after the sampler is seated 6 inches.
Fine Grained Soils (clays & silts) — more than 50% passing the No. 200 sieve (0.075 mm)
Liquid Limit < 50 Liquid Limit > 50
CL 9 lean clay CH 4 fat clay
CL-ML 9 silty clay(4 < PI < 7) MH 4 elastic silt
ML 9 inorganic silt OH 4 organic clay or organic silt
OL 9 organic clay or organic silt
_ "with sand"or"with gravel"when 15%to 29% is retained on the No. 200 sieve
"sandy"or gravelly"when more than 30%is retained on the No.200 sieve
Consistency:
Term "N" Value Tons/sq.ft.
Very soft <2 0.0 to 0.25
Soft 2-4 0.25 to 0.50
Firm 4-8 0.50 to 1.00
Stiff 8-I S 1.00 to 2.00
Very Stiff 15-30 2.00 to 4.00
Hard > 30 >4.00
Coarse Grained Soils (sands & gravels) — less than 50% passing the No. 200 sieve (0.075 mm)
More than 50%retained on 44 sieve (4.75 mm) More than 50%passing #4 sieve 14.75 nnrl
GC 4 clayey gravel (P200> 12%) SC 4 clayey sand (P200> 12%)
GM 4silty gravel (P200> 12%) SM 4 silty sand (P200> 12°%)
GP 9 poorly graded gravel (P200 <5%) SP 9 poory graded sand (P200<5%)
GW 9 well graded gravel (P200 < 5%) SW -4 well graded sand (P200 <5%)
"with sand" when at least 15%sand "with gravel'when at least 15%gravel
"with clay"or"with silt" when 5%<- P200 < 12% "with clay" or"with silt" when 5°n< P200< 12%
Relative Density:
_ Term "N" Value
Very Loose 0-4
Loose 4-10
"••—• Medium Dense 10-30
Dense 30-50
Very Dense > 50
Laube Engineering, LLC
1 Project: Proposed New Church Building Boring No.: 81
Location: 9433 Gray Avenue Date Drilled: February 18, 2005
Carr. Colorado LE Project No.: 253
Client: Carr Community Church
N.0 w
L
C U
U) C
w _
E a
a T O w-
Z H T
w w m z Soil Description E y,. LL
_ a ' E w PL Other
Depths E I- o 4.) PI Test
c
m m w a u) so (%) Results •
U' u' a N Surface - grass
0.0 Topsoil - to a depth of about 4 inches SM 11
_ 1 SS 12 28 SILTY SAND with GRAVEL - damp, medium
dense, brown.
2 SS 12 18 POORLY GRADED SAND with SILT & GRAVEL - ••• SP- 1 % Passing
.;. SM #4 = 72.4%
dry, medium dense, light grayish #40 = 28. 1%
brown. #200 = 6. 3%
5.0
3 SS 10 20 T SP- 1
SM
10.0
SP- 1
5 SS 15 47 . . .dense. ;••
; SM
15.0
End of boring at 15.0 feet.
20.0
_ I
25.0
Water Level Observations: Rig: CME Method: 4" SSA
Initial Observation During drilling: Dry
Time After Drilling: 1 hr.
Depth to Water: Dry
Cave-in Depth: 14' Laube Engineering, LLC
Project: Proposed New Church Building Boring No.: B2
Location: 9433 Gray Avenue Date Drilled: February 18. 2005
Carr, Colorado LE Project No.: 253
Client: Carr Community Church
N
Ul
L
L u
W C
E O. +
WEJ >. O
Z H T n c
m m w z Soil Description E yJ� LL
n n > N E PI Other
Depth E E u v o c Test
I--
m m w a m f 0 Results
mwmn Surface - grass " (%)
0.0 Topsoil - to a depth of about 4 inches SM 5
_ 1 SS 15 14 SILTY SAND with GRAVEL - damp, medium
dense, brown.
Tr
2 SS 8 5 . . . loose. SM 4
5.0
_ 3 SS 12 19 POORLY GRADED SAND with SILT & GRAVEL - SM 3
dry, medium dense, light grayish tt
brown.
4 SS 12 37 . . .dense. T SM 1
10.0 •
. . .drilled to 15 feet, sandy and
gravelly soils.
15.0
End of boring at 15 feet.
20.0
_ I
25.0
Water Level Observations: Rig: CME Method: 4" SSA
Initial Observation During drilling: Dry
Time After Drilling: 1 hr.
Depth to Water: Dry
Cave-in Depth: 9.5' Laube Engineering, LLC
Sieve Analysis
U.S. Sieve Opening (inches) I U.S. Sieve Numbers I Hydrometer
3 2 1 3/8 #4 #10 #20 #40 #100 #200
I I I I I I I I I I
100
90 H I I HI
I
I
80 i 4 I !IF ' F
I
I!
I
70 I. I I' '
I II
I. 1 ,I I .II 60 I .
—
CD I I I ,
'd
3 50 j ! I
.1.
a !
I '
w
c 40 . . . . .
^ is: , I
C I I ' ' I "
w I I
O
w 30 { L .-F II . .
0_
F ,
20 i I J i I I i I . I ,
10 -
- 0
100 10 1 0.1 0.01 0.001
Particle Size (mm)
—
Gravel Sand
Cobbles Silt or Clay
coarse I fine coarsel medium I fine
Source Classification % Moisture
Boring B1 Poorly Graded Sand with Silt and Gravel (SP-SM) - light 1
—
@ 3 - 4.5' grayish brown
Client: Carr Community Church Project No.: 253
Project: New Church Building Test Date: 2/24/05
-
Laube Engineering, LLC
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