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GEOTECHNICAL INVESTIGATION REPORT
OF
BEEBE DRAW FARMS AND EQUESTRIAN
CENTER, FILING 2.
LOCATED IN SECTIONS 4,5,8,9,10 AND 17,
TOWNSHIP 3 NORTH, RANGE 65 WEST OF
THE 6TH PRINCIPAL MERIDIAN, WELD
COUNTY COLORADO
U
FOR
BEEBE DRAW FARMS METROPOLITIAN
DISTRICT
11409 WEST 17TH PLACE
LAKEWOOD COLORADO 80215
MAY 12, 2000
N
I
AN_ T. . HORIZON
CONSTRUCTION
• _ _? 'i SERVICES, L.L.C.
■ --
3310 State Street FAX:s o-s �s
Evans, Colorado 80620 fnx: �»o� s39-szF
2000-2209
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HORIZON
CONSTRUCTION
'rip- SERVICES, L.L.C.
■ •
■ •
_ _• ' II ENVIRONMENTAL - GEOTECHNICAL - MATERIALS TESTING
■
May 12., 2000
Mr. Jim Fell
Beebe Draw Farms and Equestrian Center, Filing 2
11406 West 17Th Place
Lakewood Colorado 80215
•
Re: GEOTECHNICAL INVESTIGATION FOR THE BEEBE DRAW FARMS AND
EQUESTRIAN CENTER, FILING 2 PROPOSED CONSTRUCTION SITE LOCATED IN
SECTIONS 4,5,8,9,10, AND 17, TOWNSHIP 3 NORTH, RANGE 65 WEST OF THE 6TH
PRINCIPAL MERIDIAN, WELD COUNTY, COLRADO.
Dear Mr. Fell:
We are pleased to submit this Geotechnical Investigation Report for the proposed
construction at the above referenced site, as you requested.
Based upon our investigation of this site and the subsurface conditions encountered, it is our
opinion the site is suitable for the proposed construction, providing the design criteria and
recommendations set forth in this report are followed. The enclosed report presents our
findings of the subsurface conditions and our recommendations based upon these findings.
Sincerely,
HORIZON CONSTRUCTION SERVICES, LLC
Reviewed by
Darrick Turner Thomas Cope, P.E. 2499 °:
Geologist /
S�Voc
�G `7i
- 7
Terry Toler
President
CF: 200029 File
Milestone Engineering
3310 STATE STREET, EVANS, COLORADO $0020
(970) 330-3771 (970) 330.521E - FAX
HORIZON CONSTRUCTION SERVICES, LLC PROJECT NO. 200039
Beebe Draw Farms
May 12, 2000
GEOTECHNICAL INVESTIGATION REPORT
SCOPE
This report presents the results of a geotechnical investigation for the
proposed Beebe Draw Farms and Equestrian Center residential subdivision.
located in Weld County, Colorado. The Milton Reservoir borders the property
on the east, Weld County Road (WCR) 39 borders on the west, WCR 32
borders on the south and WCR 38 borders the property on the north The
investigation included 100 test borings to obtain soils, percolation rate and
groundwater data.
The objectives of this study were to:
1 . Evaluate the subsurface conditions at the site relative to the proposec
construction,
2. Make recommendations regarding the design of the substructures,
3. Recommend certain precautions that should be taken because of adverse
soil and/or groundwater conditions,
4. Evaluate Percolation Rates, and
5. Recommend pavement design options.
The conclusions and recommendations presented in this report are based
upon analysis of field and laboratory data and experience with similar
subsurface conditions in the general vicinity.
SITE LOCATION AND DESCRIPTION
The proposed subdivision is located in part of Sections 4, 5, 8,9,10 and 17 ,
T3N, R65W, of the 6th PM, Weld County, Colorado. Based on the informatiol
provided, the proposed residential structures will normally be built with wood
"stick" frames with basements. The footings will be placed on bearing
materials approximately 4 to 8 feet below existing grade.
The existing site's topography is generally sand hills covered with grasses,
sage and cactus. Elevation changes of approximately 160 feet exist
throughout the site with positive drainage to the south, southeast. There are
numerous oil and gas wells throughout the proposed development. Natural
low areas exist throughout the proposed residential areas, which are generally
designated for green belts. The previously investigated and developed
residential area located in the center of the area has previously been
developed and this geotechnical investigation does not include information
concerning this previously studied area.
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT NO 200039
Beebe Draw Farms
May 12, 2000
SITE INVESTIGATION
The field investigation was conducted from April 13 to May 5, 2000, and
consisted of 83 geotechnical borings and 17 percolation bore holes which are
located approximately as shown on the Site Plan (Appendix A). The 83
geotechnical borings were drilled to obtain soil samples for laboratory
examination, determine field parameters and determine groundwater levels.
Boring field logs include field visual classifications and Standard Penetration
Tests (SPT) of the materials encountered during sampling. The 17 percolation
borings were drilled to determine field visual classifications and determine
preliminary percolation rates for the site.
Borings were advanced using 4.0-inch diameter continuous flight augers
powered by a truck mounted Mobile drilling rig. Soils were obtained to
determine an index of the soils relative density and consistency with the
Standard Penetration Test (SPT) split spoon sampler. The "N" values listed
on the Summary of Test Results is the number of blows required to drive the
2-inch diameter split-spoon sampler and California Sampler, 12-inches into
undisturbed soil by a 140-pound hammer dropped 30 inches. The "N" values
are listed on the boring logs.
Boring logs are provided in Appendix A and include visual or laooratory
derived classifications of each soil, location of subsurface changes, and "N"
values. A qualified soils technician and geologist from Horizon Construction
Services, LLC, was present during all drilling activities and continuously
observed the fieldwork. Final boring logs in this report represent the field
findings and additional information determined by laboratory observations and
tests.
LABORATORY TESTS AND EXAMINATIONS
Samples obtained from test borings were subjected to testing and inspection
in the laboratory to provide a sound basis for determining the physical
properties of site subsurface soils. Moisture contents, dry unit weights,
consolidation determination, swelling potentials, Atterberg Limits and Unified
Soil Classification Standard System were determined. A summary of the test
results and laboratory analyses can be found in Appendix B.
Preliminary percolation rate values were evaluated over the entire site of
which all failed to meet minimum percolation rates. Our evaluation found that
all sites would most likely require an engineered leach field. Percolation rates
and locations can be found in Appendix D. A brief Beebe Draw USCS Soil
Survey can be found in Appendix E.
A pavement design based on the poorly graded sands was performed to
determine road base and asphaltic concrete thickness. Subgrade soil
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT NO. 200039
Beebe Draw Farms
May 12, 2000
characteristics and pavement design data can be found in Appendix F.
Borehole Elevations and Coordinates with WGS84 elevations can be found in
Appendix G.
SUBSOIL AND GROUNDWATER CONDITIONS
The soil at the site consisted mostly of very loose to medium dense dry to
slightly damp poorly graded sands. Sands located down to four feet are
typically very loose with a bearing capacity of one thousand pounds (1000)
pounds per square foot (psf). Sands located from four feet to eight feet are
typically loose with a bearing capacity of 2000 psf. Sands located below eight
feet range from loose to medium dense, however the soils were mostly loose
with a bearing capacity of 2000 psf.
The soils located on the south end along WCR 32 of the proposed site are
typically loose poorly graded sands with maximum bearing capacities of 1500
psf to a depth of three to four feet. A clayey sand stratum was found below
I
the sand stratum, in the southern portion of the site, with stiff to very stiff soils
with a maximum bearing capacity of 4000 psf. These materials also exhibited
moderate to high swell potentials with swell potentials ranging from 500 to
1500 psf.
tr. Ground water was not encountered throughout the proposed subdivision to a
depth of 15 feet below grade.
RECOMMENDATIONS AND DISCUSSION
Our recommendations are based on the assumption that the subsurface
conditions are similar to those disclosed by the borings. If variations are noted
during construction or if changes are made in the site plan, foundation type or
floor levels, we should be notified so we can supplement our
recommendations, as applicable. It is our understanding the proposed
residences will normally consist of a frame structure founded on spread
footings. We do not anticipate foundation loading to be unusual for this type of
construction. We recommend that all footer and floor slab subgrades are
Ill moistened and compacted to 95% Standard Proctor with a vibratory
compactor to reduce settlement. We recommend excavation inspections be
performed on all of these lots prior to the placement of footers.
FOUNDATION
In view of the loads transmitted by the proposed structure and the soil
conditions encountered at the site, a conventional spread footing foundation is
recommended. The following design criteria should also be observed:
1) All exterior footings should be placed a minimum of thirty inches below
finished grade for frost protection.
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT N0 200039
Beebe Draw Farms
May 12, 2000
2) We recommend that all footer and floor slab subgrades that are founded in
the poorly graded sands are moistened and compacted to 95% Standard
Proctor with a vibratory compactor prior to the placement of forms and
concrete.
3) Footings founded on poorly graded sands and silty sands, from one to five
(5') below grade may be designed for a maximum allowable bearing
capacity (dead load plus maximum live load) of one thousand pounds per
square foot (1000 PSF).
4) Footings founded on poorly graded sands and silty sands below five feet
(5') below grade may be designed for a maximum allowable bearing
capacity (dead load plus maximum live load) of fifteen hundred pounds per
square foot (1500 PSF).
5) The predicted settlement or heave under the above loading should be less
than one-inch (1"), generally considered to be within acceptable tolerances.
These loads were based on the in-situ material remaining partially
saturated and the engineer's recommendations provided as discussed in
this report.
6) Minimal swell potential is anticipated in the poorly graded sands, therefore
the minimum deadload is zero pounds per square foot (0 psf) for these
soils. The clayey sands and sandy clays exhibited moderate to high swell
potentials and will require minimum dead loads_ of fifteen hundred pounds
per square foot (1500 psf). If clayey sands or sandy clays are encountered
within four feet of the footer subgrade then the potentially expansive soils
will require over excavation and replacement with moistened and
compacted granular material. The granular material, such as pitrun,
should be compacted and tested to 95% Standard Proctor.
7) Footings should be proportioned as much as practicable to minimize
differential movement. Spread footings should be a minimum of 18 inches
in width. Pad footings should be a minimum width of 24 inches.
Continuous concrete foundation walls should be well-reinforced top and
bottom.
8) The base for structural fill should include all areas within a 2:1 horizontal to
vertical slope from the edge of the footings.
9) The geotechnical engineer should complete any required inspections
and testing of all subbase and imported material prior to the
placement of footer forms or other permanent structures. Required
subgrade repair actions could result in the removal of placed forms,
footers or foundations walls.
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT NO. 200339
Beebe Draw Farms
May 12, 2000
10) A geotechnical engineer should inspect all subbase and mported
material prior to placement of any foundation concrete. We suggest that a
geotechnical investigation be conducted if a builder should wish to reduce
recommended minimum dead load and soil replacement requirements for
structures founded above expansive clayey sands or sandy clays.
LATERAL EARTH PRESSURES
Lateral pressures on walls depend on such factors as the type of wall,
hydrostatic pressure behind the wall, type and slope of backfill material,
degree of backfill compaction, allowable wall movements, and surcharge
loading conditions. Where anticipated wall movements are greater than
approximately 0.5 percent of the wall height or wall movement is constrained
lateral earth pressures should be estimated for an "at rest" condition Where
anticipated wall movements are greater than 0.5 percent of the wall height,
lateral earth pressures should be estimated for "active" condition. Walls
backfilled with on-site silty sands material should be designed for an
equivalent fluid lateral earth pressure of 55 pounds per cubic foot for the
"active" condition and 45 pounds per cubic foot for the "at rest" condition
We recommend a coefficient of sliding resistance between the concrete and
bearing soils of 0.4 be assumed in the analysis. These values do not consider
sloping backfill, surcharge loading, hydrostatic pressures, or horizontal
swelling pressures. If any of these conditions are anticipated, lateral earth
pressures will need to be adjusted.
Disturbed subbase material and fill against footings, stem walls and retaining
walls should be compacted to a density of 95% of maximum density and within
3% of optimum moisture, in accordance with ASTM D698. Medium to high
plasticity clay soils should not be used as subbase or structural backfill
material.
FLOOR SLABS
The following recommendations are to be provided during construction:
1 . Slabs should be designed for the imposed loading, any expansive or
settling soils in the subgrade, and be structurally independent of bearing
members and utilities. Any additional recommendations for reducing
expansiveness or settling called out under the FOUNDATION section
should also be followed in this section.
2. To minimize and control shrinkage cracks that may develop in slabs,
control joints are recommended every '15 feet and at areas of potential
cracking. The total area contained within these joints should be no greater
than 225 square feet.
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT NO 200039
Beebe Draw Farms
May '2, 2000
3. Slabs should be continuously reinforced with wire mesh or equivalent.
4. A minimum of 4 inches of clean granular material such as squeege should
be vibrated in place beneath all concrete slabs
5. Granular structural fill, as needed, beneath footings or slabs should be
placed in maximum 8-inch lifts compacted to ninety-five percent (95%) and
three percent (3%) of optimum moisture in accordance with ASTIM D698.
6. Proposed material to be used for structural fill should be evaluated by a
geotechnical engineer prior to installation. A geotechnical engineer should
closely observe and or test structural fill installation.
7. The geotechnical engineer should complete any required inspections
and testing of all subbase and imported material prior to the
placement of footer forms or other permanent structures. Required
subgrade repair actions could result in the removal of placed
concrete.
8. Exterior slabs exposed to de-icing chemicals or extreme weathering should
be constructed using Type II cement with higher air contents and higher
compressive strengths.
SUBSURFACE DRAINAGE
Groundwater was not encountered at the site at the time of the subsurface
investigation. For structures founded on the silty sands and poorly graded
sands, we do not recommend subsurface drainage for these soil types
For structures with subsurface living spaces founded on the sandy clays and
clayey sands, the following is recommended:
1) The installation of a drain system during construction is recommended due
to possible changes in groundwater levels or future drainage problems
caused by broken pipes or the irrigation system. The perimeter drain
should be installed around the top of the footer sloping to a sump area at a
slope of one-eighth inch per foot (1/8"/1'). The drain should be constructed
with four inch (4"), or greater, perforated pipe and should be surrounded in
a gravel bed with a minimum of eight inches (8") of one and one-half inch
(1-1/2") or three quarter inch (3/4") clean washed gravel. Building paper
should be placed above the gravel prior to backfilling.
2) Dampproofing measures should be included during construction. and may
include waterproofing sprayed onto the foundation wails and/or an
IPimpervious membrane installed adjacent to the exterior of the foundation
wall. A clean granular backfill placed adjacent to the barrier should be
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT NO. 2)0039
Beeoe Draw Farms
May 12 2000
installed to allow surface water to enter the perimeter drain described
above.
GENERAL RECOMMENDATIONS
The following recommendations should be followed during construction and
maintained by the owner at all times after the structure has been completed.
These recommendations are provided to minimize cracking, heaving or
settlement of structures due to exposure to moisture caused by irrigation,
pooling or runoff of water or breaks in water lines.
1 . Finished grade should be sloped away from all concrete structures on all
sides to give positive drainage. A minimum slope of 6 inches for the first
10 feet is suggested. The installation of any object or structure that may
imede add t onal the precalutions.ve drainage
the other require
builder, homeowner
landscaper should ensure that the drainage slope from one structure does
not cause runoff waters to flow around or onto any other structure that may
be harmed by the pooling or flow of water.
2. Gutters and down spouts should be designed, installed, and maintained to
carry roof runoff water at least five feet beyond the limits of the foundation
backfill area as well as all concrete structures to include: sidewalks
porches, steps, driveways and foundations. The pooling of water or the
flow of water around or under any structure may cause erosion, settlement,
or swelling of soils. The owner must ensure that that all landscaping and
structure drainage systems are designed and installed to remove water
from around all structures without creating ponding or water flow that will
erode the soils and gravels below or around the structures.
3. Underground water supply lines and sprinkling systems should be
designed such that piping is installed a minimum of 5 feet outside the
backfill of the foundation wall and 2 feet away from all other structures
Heads should be designed so that irrigation water is not sprayed withir
three feet of foundation walls and two feet of driveways, sidewalks, porches
or other structures. These recommendations should be taken into accoun
for planned landscaping. Any excavation into subgrade materials below o
around any that the effected structure
concrete structure does not
not fail due to subgrade failure. sc
ion system must be repaired
terior 4 'Backfill
mfoistened and coxmpacted to foundation
walls non-structural
least ninety percent (90%) of Standard
Proctor in accordance with ASTM D698. Backfill below porches ,
sidewalks, garages and driveways should be compacted to ninety-five
percent (95%) of Standard Proctor in accordance with ASTM D698.
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT NO 200039
Beebe Draw Farms
May 12, 2000
5. Lawn edging used around the exterior of the structure should be perforated
to prevent surface water ponding in the vicinity of backfill soils. Sod or
other vegetation that requires regular watering should not be placed within
three feet of the foundation wall area or two feet of other structures to
include porches, steps, sidewalks, and driveways.
6. The exterior backfill should not be covered with polyethylene moisture
barrier. A weed suppressant geotextile fabric, to allow for natural
evaporation of the backfill soils, should be used instead. Sheeting placed
below soils or gravel should be installed so that water is not directed
toward any structure to include porches, steps, sidewalks, foundation walls
or driveways.
7. Footings should be proportioned as much as practicable to minimize
differential movement.
8. Compaction requirements should be completed as described in Appendix
C, " Suggested Specifications for Placement of Structural Fill".
9. A Registered Professional Structural Engineer should design the sub-
structures, and they should take into account the findings and
recommendations of this report.
10.Backfill material should be free of frozen soil, dried clods and organic
matter. Backfilling should only be accomplished when concrete strength
and adequate support to foundation walls are applied and acceptable to the
Structural Engineer.
11 .The site soils are susceptible to moderate erosion when ground cover is
removed, therefore erosion control measures will be necessary during and
after construction at each building site.
GENERAL COMMENTS
This report has been prepared to aid in the evaluation of the property and to
assist the architect and engineer in project design. In the event any changes
in the design of the structures or their locations are contemplated, the
conclusions and recommendations contained in this report will not be valid
unless said changes are reviewed and conclusions of this report modified or
approved in writing by Horizon Construction Services, LLC.
The professional judgments expressed in this report meet the standard of care
of our profession. Every effort was made to provide comprehensive site
coverage through careful locations of the test borings, while keeping the site
investigation economically viable. Variations in soil and groundwater
conditions between test borings may be encountered during construction. In
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HORIZON CONSTRUCTION SERVICES, LLC PROJECT INC!. 200039
Beebe Draw Farms
May 12, 2000
order to permit correlation between the reported subsurface conditions and the
actual conditions encountered during construction and to aid in carrying out
the plans and specifications as originally contemplated, we recommend that a
geotechnical engineer be retained to perform continuous excavation and
foundation construction review. Horizon Construction Services, LL.C assumes
no responsibility for compliance with the recommendations included in this
report unless we are retained to perform adequate on-site review during
construction.
Analyses were performed and this report was prepared for the exclusive
purpose of providing geotechnical engineering and/or testing information and
recommendations. Environmental and flood plain assessments were not
conducted and are not within the scope of this study. ASTM methods, if any,
used in this report apply only to the specified test and any cross references
listed in that specific ASTM are not implied or to be inferred. We were not
provided with information or have knowledge of any hidden structures or other
historical events which may effect this property.
At least five separate oil companies maintain oil batteries and accompanying
lateral underground lines throughout the property. These companies should
be notified prior to any future excavations or subsurface investigations. Other
utility companies should also be notified prior to any subsurface work.
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