HomeMy WebLinkAbout20060061.tiff r .� High Plains Engineering '1
735 Denver Avenue • Fort Lupton CO 8O821
Phone 3O3-857-928O • Fax 3O3-857-9238
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SUBSURFACE INVESTIGATION AND FOUNDATION
RECOMMENDATIONS
Prepared For:
Wayne's Electric
130 South Main Street
Brighton, CO 80601
Job Site Located At:
A Part of the SE V4 of the SE 'A of
Section 19, T1N, R66W of the 6th P.M.
Weld County, CO
Original: May 24, 2005 Job # 05-4604
Revised: October 25, 2005
JOB #05-4800
o REG/S
m:ti
•
Todd M. Schroeder P. 335.
S
2006-0061
AGREEMENT OF PURPOSE AND DISCLAIMER:
^ The parties specifically agree and contract that the purpose of the provided
subsurface investigation is to test, analyze, and provide geotechnical
recommendations for the proposed building and/or residence. This report presents a
description of subsurface conditions encountered at the site, recommended
foundation system, and design and construction criteria influenced by the subsurface
conditions. The opinions and recommendations presented in this report are based on
the data generated during this field exploration, laboratory testing, and our
experience. A foundation design sealed by a Professional Engineer is required to
obtain a building permit but is not included in this report.
The parties specifically agree that High Plains Engineering has not been retained nor
will they render an opinion concerning environmental issues, hazardous waste or any
other known and or unknown conditions that may be present on the job site, since this
is not our area of expertise.
LOCATION AND SITE CONDITIONS:
This report represents the results of the data obtained during the subsoil investigation
for the proposed single story office on A Part of the SE1/4 of the SE1/4 of Section 19,
Ti N, R66W of the 6th P.M., Weld County, CO.
The proposed building site is presently a vacant lot. The site is reasonably level with
approximate slopes of 0.5% to the East. The lot appears to be well drained with no
erosion evident.
The depths of foundation construction are anticipated to range from one (1) to three
(3) feet below grades that existed at the time of this investigation. It is anticipated that
final grades may be adjusted to accommodate drainage and construction depths. It
is recommended that we review the final grading plan to determine if any revisions to
the recommendations presented in this report are necessary.
SUBSOIL CONDITIONS:
Two, four inch diameter holes were drilled to a depth of twenty five feet at the building
site on May 19, 2005, as shown on the attached site map. Samples of the soil were
taken at two-foot intervals. These samples were analyzed in the field and laboratory
to determine the characteristics of the soil (per Unified Soil Classification System) for
identification and foundation design. In general, the soil profiles in test holes # 1 & #2
indicated Clay with Low Plasticity (CL) to a depth of 3 feet, underlain by Poorly
Graded Gravel (GP) to a depth of 9 feet. Poorly Graded Sand (SP) exists from 9 feet to
15 feet, and finally, Poorly Graded Gravel (GP) exists from 15 feet to a depth of 25 feet.
The Standard Penetration Test similar to ASTM D1586 showed 21 blows for 12-inch
penetration at a depth of 4 feet, and 19 blows for a 12-inch penetration at a depth of
HPE 3 Job#05-4800 Page 2 of 8
• 9 feet. Please note that actual subsurface soil conditions ...ay vary between samples
and locations tested.
One-dimensional swell/consolidation tests were not performed on selected samples to
evaluate the expansive, compressive and collapsing nature of the soils and/or
bedrock strata due to the amount of gravel in the soil. The soils in this report were
classified using the American Society of Testing Materials (ASTM) procedures.
The geotechnical practice in State of Colorado utilizes a relative scale to evaluate
swelling (expansion) potentials. When a sample is wetted under a surcharge pressure
of 500 pounds per square foot (psf), the measured swell is classified as low, moderate,
high, or very high. The following table represents the relative classification criteria.
Please note that the measured swell is not the only criteria for slab-on-grade
recommendations and additional factors are considered by the engineer when
evaluating the risk for slab-on-grade construction.
TABLE 1
SLAB PERFORMANCE REPRESENTATIVE
RISK CATEGORY PERCENT SWELL
(500 PSF SURCHARGE)
LOW 0 TO <3
MODERATE 3 TO <5
HIGH 5 TO<8
VERY HIGH >8
Source: Colorado Association of Geotechnical Engineers, Guideline for Slab Performance
Risk Evaluation and Residential Basement Floor System Recommendations(Denver
Metropolitan Area), 1996
GROUNDWATER:
Groundwater levels were not recorded at the time of our field investigation; however,
it may be possible for groundwater to exist at construction depths at a later date. The
groundwater can be expected to fluctuate throughout the year depending on
variations in precipitation, surface drainage and irrigation on the site. The possible
presence of shallow bedrock/dense clays beneath the surface is favorable for the
formation of "perched" groundwater. We recommend that the bottom of the
basement or crawlspace excavations be maintained at least 4 feet above the free
groundwater level.
The ground water levels recorded represent the free, static water levels after
equalization of hydrostatic pressures in the test hole borings. It is possible that the
groundwater levels recorded in the test hole borings may not be present at those
levels in the foundation excavations. Flow rates, seepage paths, hydrostatic pressures,
seasonal groundwater fluctuations, water quality and other factors were not
determined in this investigation. A program, which may include special well
HPE 3 Job#05-4800 Page 3 of 8
construction, test proceuures, long-term monitoring progr.,n and analysis would be
necessary to determine these factors.
- FOUNDATION RECOMMENDATIONS:
The Poorly Graded Gravel (GP) material has a bearing strength of 1750 pounds per
square foot (psf) and an equivalent liquid pressure of 30 pcf. We recommend the use
of a continuous spread footing, due to the low expansion-consolidation potential of
the analyzed soils. The foundation must be constructed at the location in which soils
investigation was performed.
An open hole observation is required at this site, which is not billed with this soil
investigation. The purpose of the open hole observation is to confirm the soil bearing
at the proposed site for the steel building is consistent with the original report that was
prepared for the previous lot owner at a different location on the site. The observation
will also determine whether any significant variation from this report exists and whether
the soils report and/or foundation design will require modification. The open hole
observation must be performed immediately after the excavation, and prior to
backfilling or placing the footings. Failure to obtain the recommendations from the
open hole observation, prior to placement of foundation elements, renders this report
and its recommendations null and void.
All loose and disturbed soil shall be removed before placing of the concrete for the
foundation. The bottom of the foundation shall be a minimum of 30" below final
grade (or that required by local jurisdiction; whichever is greater) for frost protection.
Soil settlement resulting from the assumed structural loads is estimated to be one inch
or less. Soil expansion at this site may be up to one inch in some areas. No foundation
wall is to exceed twenty-five feet in length without utilizing buttresses or counterforts
unless otherwise designed by the foundation engineer.
Engineered steel reinforcements shall be required in the footings and foundation walls.
This will give walls or footing beams the strength to span or bridge over any loose or
soft pockets of soil that may develop during construction.
Owners shall be made aware of all contents of this report, and the fact that water
accumulation around foundation elements is the primary cause of distressed
foundations.
To help prevent secondary damage that could be caused by slab movement, the
following construction techniques are additional recommendations for the foundation
construction.
HPE 3 Job#05-4800 Page 4 of 8
SLAB ON GRADE CONSTRUCTION:
. When and where slabs-on-grade are chosen and the owners are willing to
accept the risks associated with slab movement, the following
recommendations are to be followed:
a.)Slabs should be constructed as "free floating". Positive separations and/or
isolation joints should be provided between slabs and all foundation walls,
bearing members (columns), plumbing and utility lines. Isolation may be
achieved with 1 inch expansion material or by sleeving. Vertical movement
of the slabs should not be restricted.
b.) Eliminate plumbing under slabs where feasible. Where such plumbing is
unavoidable, it should be thoroughly pressure tested during construction.
c.) Place the slab directly on the undisturbed natural soils, or properly
compacted fill soil. Floor slabs and footings should not be constructed on
frozen sub grade. Slabs should be reinforced with rebar, wire mesh or fiber
mesh to help control crack separation.
2. Provide frequent scoring of the slabs to provide joints for controlled cracking of
the slab. Control joints should be placed to provide approximate slab areas of
150 square feet, with a maximum dimension of thirteen feet between joints. The
depth of sawed control joints should be '/4 of the slab thickness. Install a good
quality sealant in these joints to prevent surface discharges of liquid from
penetrating slab sub grades.
3. The soils that will support the concrete slabs should be kept moist during
construction by occasional sprinkling of water. The soils should be moistened to
+/- 2 % optimum moisture within 48 hours of pouring the slabs. This procedure will
help maintain the moisture content of the underlying soil. **Heavy watering or
pooling of any kind next to the foundation or within the backfilled area is not
recommended."
4. A minimum void or clear space of 3 inches should be provided at or near the
bottom of all non-bearing partitions. In finished room areas, all drywall and
paneling should be stopped approximately 3 inches above the top of the slab.
This will allow some space for upward movement of the slab before pressures
are applied to the wall and upper levels of the structure. The builder should
provide a 'h inch space at the bottom of all doorjambs to allow for limited
movement of the floor slab. The owner is hereby notified that it is their
responsibility to maintain these void spaces.
5. If a forced air heating system is used and the furnace is located on the slab, we
recommend provision of a collapsible connection between the furnace and the
ductwork. In the event a hot water heating system is used, the piping should not
be placed beneath the concrete slab.
I-IPE 3 Joh#05-4800 Page 5 of 8
BACKFILL AND SURFACE DRAINAGE:
The foundation and retaining walls must be well cured and well braced prior to
backfilling.
Any soil disturbed adjacent to bearing foundation components are to be re-
compacted to a minimum of 85% Standard Proctor Density (ASTM D698). Backfill that
bears concrete slabs shall be compacted to 95% Standard Proctor Density (ASTM
D698). Mechanical compaction methods shall be utilized, (water-flooding techniques
are strictly prohibited). See Compaction Section for more information regarding
compaction requirements and techniques.
Proper drainage away from the foundation walls shall be provided. The owners are
advised to immediately fill any settled areas to eliminate water accumulation near the
foundation. A minimum slope of 12 inches in the first 10 feet from the perimeter of the
building is recommended. Roof downspouts and sill cocks should discharge into long
concrete splash blocks (5 feet long min.) or into gutter extensions to deposit runoff
water beyond the limits of the backfill soil near the foundation walls. Plastic
membranes should not be used to cover the ground surface immediately surrounding
the structure; geotextile fabric should be utilized for weed control. Any drainage
water from uphill shall be diverted around the structure.
Sprinkling systems should not be installed or direct water to be within 10 feet of the
foundation. The owner/builder is also advised that irrigation lines can leak and/or
break, resulting in release of excessive amounts of water near the foundation. This can
cause damage to slabs and foundation walls. WATER ACCUMULATION AROUND
FOUNDATION ELEMENTS IS THE MAIN CAUSE OF DISTRESSED FOUNDATIONS.
COMPACTION:
Placing Fill: No brush, sod, frozen material, perishable material, unsuitable material, or
stones of four inches or greater in maximum dimension shall be placed in the fill. The
distribution of the material on the fill shall be such as to avoid the formation of layers of
materials differing substantially in characteristics from the surrounding materials. The
materials are to be delivered to the backfill surface at a uniform rate, and in such
quantity as to permit a satisfactory construction procedure. Unnecessary
concentration of backfill machinery travel tending to cause ruts and other hollows
more than six inches in depth, are to be re-graded and compacted. After dumping of
fill material on the backfill surface, the material is to be spread by approved methods
in approximately 6 inches compacted thickness.
Moisture Control: The material in each layer shall be compacted by rolling and shall
contain the optimum moisture required for maximum compaction, as nearly
practicable and as determined by the soils engineer. The moisture content shall be
uniform throughout all layers. If in the opinion of the soils engineer it is not possible to
HPE 3 Job#05-4800 Page 6 of 8
obtain moisture content oy adding water on the fill surface, the contractor may be
required to add the necessary moisture to backfill material in the borrow area.
Compaction: When the moisture condition and content of each spread layer is
satisfactory, it shall be compacted by a method approved by the soils engineer to
95% ASTM D698 (Standard Proctor Density) for slab areas, and 98% ASTM D698 for
footing and/or pad areas. A Standard Proctor test is to be performed for each typical
fill material and frequent tests of the density of the fill must be taken.
In general, to compact cohesion-less free-draining materials, the above guidelines
also apply.
When compacting cohesion-less free-draining materials such as gravel and sand, the
materials shall be deposited in layers and compacted by treads of a crawler type
tractor, surface of internal vibrators, pneumatic or smooth rollers, power or hand
tampers, or by any other means approved by the soils engineer. The thickness of the
horizontal layers after compaction is not to exceed 6 inches compacted thickness if
compaction is performed by tractor treads, surface vibrators or similar equipment, or
not more than penetrating length of the vibrator head if compaction is performed by
internal vibrators. When the moisture content and condition of each spread layer is
satisfactory, it shall be compacted by a method approved by the soils engineer to
95% ASTM D1557 (Modified Proctor Density) for slab areas, and 98% ASTM Dl 557 for
footing and/or pad areas.
RADON:
Most counties in Colorado have average radon levels (measured in home) above the
U.S. EPA recommended "action level" of 4 picocuries per liter of air (pCi/1). Results of
a 1987-1988 EPA-supported radon study for Colorado indicated that granite rocks, in
particular, generally have elevated levels of uranium. These rocks have the potential
of producing higher than average levels of radon gas in the home. Increasing
ventilation of basements and crawl spaces and sealing of joints can mitigate build-ups
of radon gas. This mitigation is best implemented during the design and construction
phases of residences.
The Colorado Geologic Survey {www.dnr,state.co.us/geosurvey} and the U.S. EPA
{www.epa.gov/iaq/radon} are both good sources for additional radon information.
CONSTRUCTION DETAILS - GENERAL COMMENTS:
In any soil investigation, it is necessary to assume that the subsurface soil conditions do
not vary greatly from the conditions encountered in the field and laboratory testing.
The accompanying design is presented using best professional judgment based on the
limits of the extent of testing commissioned by the client. Our experience has been
HPE 3 Job#05-4800 Page 7 of 8
that at times, soil conditions do change and variations do occur. These may become
first apparent at the time of excavation for the foundation system.
**If soils conditions are encountered which appear different from the test borings as
presented in this report, it is required that this office be called to make an observation
of the open excavation prior to placing the footings. The cost of this observation is not
part of this report.**
This project should be constructed by a qualified contractor with experience in similar
projects. The owner/builder is advised to observe and document the construction
process to ensure the construction is performed in accordance with the design
drawings and technical specifications.
This report does not address general hillside stability, landslide potential, and/or other
natural hazards. Several areas in the Colorado Front Range have known geologic
hazards associated with them. We recommend that readers of this report educate
themselves further as to the existence of geologic hazards on or around their specific
property of interest. The Colorado Geologic Survey {www.dnr.state.co.us/geosurvey
or 303-866-2611} is a good source for publications (maps, reports, etc.) dealing with
specific geologic issues and/or issues related to specific geographic areas. The
foundation and retaining walls must be well cured and well braced prior to backfilling.
DISCLAIMER:
We do not guarantee the performance of the project in any respect, but only that our
engineering work and judgments rendered meet the standard care of our profession.
The presence of underground workings (e.g. coal mines) and subsidence potential
from any workings was not part of this investigation. The owner should contact the
State and County agencies to determine if mining has been conducted in the area
and if any precautions are recommended.
THE PARTIES SPECIFICALLY AGREE THAT HIGH PLAINS ENGINEERING, INC. HAS NOT BEEN
RETAINED NOR WILL THEY RENDER AN OPINION CONCERNING ANY ENVIRONMENTAL
ISSUES, HAZARDOUS WASTE OR ANY OTHER KNOWN OR UNKNOWN CONDITIONS THAT
MAY BE PRESENT ON SITE.
DUE TO CHANGING TECHNOLOGY, BUILDING CODES AND CITY/COUNTY REQUIREMENTS,
THIS SOIL REPORT MUST BE USED WITHIN ONE YEAR OF THE DATE ON THE FRONT OF THE
REPORT OR MUST BE REVISED.
HPE 3 Job#05-4800 Page 8 of 8
• / 0 ' ^
% 1
CLAY WITH LOW PLASTICITY(Cu
2
r < 3
Blowcounts 21/12 4
5
POORLY GRADED GRAVEL(GP)
G
7
8
Blowcounts 19/12 9
��/� 10
/%/
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//' 12 POORLY GRADED SAND(SP)
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jv/i 14
15
IG
II7
18
19
20 POORLY GRADED GRAVEL(GP)
21
22
23
24
25
SOIL PROFILE
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;4iJ\ High Plains engineering
-^ N ,'� '`!o1/4 735 Denver Avenue • Fort Lupton CO 8062 I
Phone 303-857-9280 • fax 303-857-9238
FOUNDATION GRADING DETAIL
5' MIN.
II DECORATIVE GRAVEL
OR STONE AREA
4
■
�•�:��I:1:�. GRADE
II
it _
METAL OR WOOD EDGE
FOUNDATION WALL W/ 1/2' SPACE AT
BOTTOM TO ALLOW FOR
THE RELEASE OF WATER
GLOTLXTILE FABRIC
NOTE
I . PROVIDE A MINIMUM SLOPE OF 12 IN THE
FIRST 10'-0" FROM FOUNDATION ( I 0%)
2. DOWNSPOUTS AND EXTENSIONS SHOULD
EXTEND BEYOND THE GRAVEL OR STONE AREA
•
...„, ,, SITE MAP
A PART Of THE SE IM Of THE SE I/4 Of
SECTION 19, TIN, R66W OF THE 6TH P.M.
WELD COUNTY, CO
ar OPER1Y PIN
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Ki
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IN's
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A
F
in
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Proposed
Steel Building
V
WfLt n
re
120
128•
,AC„
fx5TING
(SCHOOL)
BUJ DING
LASTING DITCH(TO BE ABANDONED)
LEGEND X
., All locations shown above are based on specific information furnished by others or
'ercolat(on Holes estimates made in the field by High Mains Engineering personnel. The locations,
distances, directions, etc. are not the result of a property survey but are
X Percolation Profile Hole approximations and are not warranted to be exact. It is the owner/builder's
A Soil Profile Hole responsibility to define property - boundaries and ensure alf onsite improvements
are located within the platted site and out of inappropriate easements. All
-E Fence distances are to be verfied prior to excavation.
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