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GEOTECHNICAL REPORTS
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2003-1107
JUL-01-2002 M0N 02:26 PM P. 1302/056
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GEOLOGIC AND PRELIMINARY
GEOTECHNICAL INVESTIGATION
PORTION OF
WHITHAM PROPERTY(NORTH HALF)
SOUTHEAST OF COUNTY ROAD 26 AND
COUNTY ROAD NO. 3%
WELD COUNTY,COLORADO
•
Prepared For:
PULSE HOME CORPORATION
100 Inverness Terrace East, Suite 200
Englewood, Colorado 80112
Attention: Mr. Jim Miller
Job No. FC-1107
November 17,1998
CTL/THOMPSON, INC.
CONSULTING ENGINEERS
'-' 375 5.HORSBTOOTH RD. ■ THE SHORES OFFICE PARK • BLDG.3,SUITE 201 ■ FT.COLLINS.CO 80525
(070)206.0456
JuL—UI—LUUL MN LIZ Lb eM P. 003/055
November 17, 1998
Pulte Home Corporation ^
100 Inverness Terrace East, Suite 200
Englewood, Colorado 80112
Attention: Mr. Jim Miller
Subject: Opinion Letter. Undeveloped Land _
Geologic and Preliminary Geotechnical Investigation
Portion of Whitham Property(North Half)
Southeast of County Road 28 and County Road 31/a
Weld County, Colorado
Job No. FC-110T
Gentlemen:
We understand that Pulte Home Corporation Is considering the purchase of _
the north portion of the Witham Property In Weld County, Colorado. Puke has
requested our professional assistance with respect to the feasibility of using the land for the construction of a single-family subdivision.
We acknowledge that:
1. We are professional engineers, licensed by the State of Colorado,
practicing geotechnicai engineering.2. We have professional errors and omissions Insurance coverage with
limits of one million dollars as evidenced by the attached certificate of —
insurance.
3. We have reviewed Puke's "Soils Investigation Policy", dated June, —
1996-Revised. We understand that this letter Is furnished to assist
Pelts In complying with their policy. —
4. We have inspected the land described above which Puke proposes to
purchase, and we have conducted and/or reviewed such tests as we deem appropriate to form a professional opinion that the land can be —
developed and used for the intended purpose. The parcel is located
southeast of the Intersection of County Road 26 and County Road No.
31/j In Weld County, Colorado (Fig. 1). The current land use is agricultural. The parcel is Irrigated by a series of ditches. The
improvements on the parcel Include perimeter fences and a graveled
road from the southwest corner of the parcel through the middle of the —
parcel toward the north end of the parcel. Storage tanks for oil and
gas production are located near the center of the parcel,and a pipeline
connects the tanks with another pipeline that trends east west along
the south property boundary. From the northeast corner of the site,
the ground surface slopes down gradually to the south and east. No
PULTT NOME CORPORATION ^` •_
wNRHAM PROPERtr(NORTH HALF( -�
CU'?PC.1107
- JUL-01-2002 M0N 02:27 PM P. 004/056
significant erosional features were observed. We have completed a
report titled "Geologic and Preliminary Geotechnical Investigation,
Portion of Whitham Property(north halt),southeast of County Road 28
and County Road 3%, Weld County, Colorado" that presents the
results of our Investigation and our opinions. A copy of our report is
Exhibit A attached.
Based upon our investigation, review and/or tests, it is our professional
opinion that there are soil conditions at the parcel which will materially increase the
cost of developing the property for the proposed use and require special design of
one or more of the following:foundations, basements, underground utility systems,
surface or subsurface drainage systems, paving cut and fill procedures, or other
development or construction activity. These soil conditions are as follows:
1. The ground under the parcel is a thin to thicker(2 feet to 28 feet thick)
layer of windblown clays over sedimentary (claystone, sandstone,
slltstone) bedrock. Ground water is comparatively shallow to deep (3
feet to 24 feet deep depending on location). The clays showed no
tendency to swell (expansion) and slight potential for consolidation In
our tests. The bedrock showed low swell In our tests.
•
The special design requirements are as follows:
1. The ground water depth is above typical residence basement depth
(measured from existing grade) under the south and east sides of the
a parcel. The parcel surface elevations could be raised using
engineered fill to increase the depth to ground water from the ground
surface so basement floors can be placed at least 3 feet above the
expected ground water surface or a parcel wide subdrain could be
installed to lower the ground water surface to at least 3 feet below
basement floors. A combination of the two alternatives might be the
more feasible. Draining the subdrain system by gravity will be
difficult, if possible, because of topographic constraints. This
suggests lift stations might be needed to lower the ground water using
a subdraln. In addition, to a form of parcel-wide subdraln the
proposed residences will need foundation drains connected to the
` parcel-wide subdraln.
2. A successful parcel wide subdrain will tend to lower the ground water
elevation under Oligarchy Ditch which bisects the parcel near the
south boundary. The affect on Oligarchy Ditch will need consideration
when evaluating the decision to install a parcel wide subdraln.
3. The clays at the site can be characterized as nil to low expansive and
the bedrock as low expansive. We believe footings can be the
foundations for the residences proposed for the subdivision if the final
lot grades are at or above the existing natural grades. The finally
selected site grading plan will determine if the foundation strata for a
given residence foundation will be footings bearing on clays or
PULTE HONE CORPORATION
WHITHAN PROPERTY(NORTH HALF)
CUR FC-11a7 2
JUL-01-2002 M0N 02:27 PM P. 005/056
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footings bearing on the bedrock. The tendency for swell In the -
bedrock will cause the footing design criteria to include criteria for a
minimum dead load for both bearing strata. -
Much lowering of the final grades below the existing natural grades
will probably result in drilled piers as the preferred foundation. —
4. The natural clays and bedrock can be the subgrade for slab-on-grade
basement floors. Considerations for slab-on-grade basement floors
are discussed in our report in Exhibit A attached.
5. The natural clays are a weaker subgrade for pavements. Residential
streets will probably require full-depth asphaltic concrete pavement
thicknesses of the order of 8 Inches (4 inches of asphaltic concrete
over 8 Inches of the compacted base course) and thicker pavement
sections for collector and arterial streets. These sections could be
thinned by strengthening the subgrade with lime or other strengthener.
6. Control of the surface water will Influence the performance of
foundations, slab-on-grade floors and pavements. Surface ground
contours and drainage structures must cause rapid runoff of surface .
water away from structures and removal of the water from the area.
7. The soils and bedrock should present no unusual problems for heavy
earth moving equipment, however, the shallow ground water has
resulted In softer, shallow clays that may cause stability problems
during construction.
8. Utilities will be burled. At this parcel, the ground water is shallow
therefore it Is probable dewatering will be needed to install the utilities —
•In the dry". Utility.trenches should be braced or sloped to meet local,
State and OSHA regulations.
9. The water soluble sulfates measured in some samples was high. ACI
(American Concrete Institute) recommends Type V cement or Type II
cement with 20 percent Class F fly ash when such conditions, are —
present.
Because of the special design and/or construction requirements noted above
in this Opinion letter,we will review any applicable site plans,engineering drawings
and/or house foundation plans when they have been completed and are furnished
to our office,and make sure they properly address the special soil conditions noted in this Opinion Letter. Prior to the initiation of the land development work and/or
foundation construction,we will submit a Pre-Land Purchase Letter to you stating
that
1. We have reviewed the applicable plans and they meet the requirements
cited in letter with exceptions being noted.
PULTE HOPE CORPORATION -.
WNRHAU PROPERTY(NORTH HALF)
CLYN PC-1107 3
JUL-01-2002 M0N 02:27 PM P. 006/056
2. We will list the Inspections which we believe must be performed if our
requirements, as reflected In the plans, will be met and who will
perform the Inspections.
We estimate the Plans/Inspections letter can be sent within 2 weeks of our
receipt of the needed site plans, engineering drawings and/or house plans. The
subject site considered for purchase by Pulte Is proposed for single-family
residential construction. We recommend continued monitoring of ground water
levels and a detailed ground water investigation be performed if loweringthe ground
water table is to be attempted. We recommend a detailed Soils and Foundation
Investigation and Subgrade Investigation and Pavement Design be conducted after
site grading is completed.
Furthermore,we will prepare a i and Deveinpment Final Notification Letter that
presents our opinion whether the requirements cited In this Opinion Letter related
to land development have been met after each phase of the land development work
has been completed and Inspected, as long as construction plans, inspection
records and field reports ars provided for our review. After the installation of each
of twenty-five special foundations(or more frequently if local conditions dictate),we
will prepare a House Final Notification I attar which will present a summary of our
opinions whether the requirements of our design-level investigation and the •
foundation plans prepared by the structural engineer have been met. If,at any point
- In the Inspection program, a problem is detected, we will notify the construction
superintendent or land development representative.
Very truly yours,
CTL/THOMPSON, INC.
-TAU
Th•fas A. Impel
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H;bic FRANK J. HOLLIDAY
(S copies sent)
PULTE HOME CORPORATION
WNRNAM►ROPERTY INORTN NALF).
CL7rt FC•t 107 q
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JUL-01-2002 MON 02:28 PM P. 007/056
CTLCOM
ACORDRI CERTIFICATE OF INSURANCE 11/13/98 .
PM:0M" THIS CERTIFICATE IS ISSUED AS A MATTER OF INFORMATION
Van Gilder Insurance Corp. ONLY AND CONFERS NO RIGHTS UPON THE CERTIFICATE
700 Broadway, Suite 1000 HOLDER. THIS CERTIFICATE DOES NOT AMEND. EXTEND OR
Denver, CO 80203 ALTER THE COVERAG AFFORDED BY THE POLICIES BELOW,
COMP INC COVERAGE
COMPANY
AHartfor Ins Group
INSURED =VAIN
CTL/Thompson,Inc.BColora ompensat4s ne.
Consulting Engineers
1971 West 12th Avenue C°"" "'
OSecurit In ompany
Denver, CO 80204
IANy N
COVERAGES - . . Y
s.. i d' t d':... <<...y ad.i e;
��^ . . .
TT35 IS TO CERTIFY THAT THE POLICES OF INSURANCE USTED BELLOW HAVE BEEN ISSUED TO THE INSURED NAMED ABOVE FOR THE POLICY PER100 _
INDICATED, NOTYATNSTANDINO Na REOWREMENr, TERM OR CONDITION OF ANY CONTRACT OR OTHER DOCUMENT WITH RESPECT TO WHICH THIS
CERTIFICATE MAY BE ISSUED OR MAY PERTAIN, THE INSURANCE AFFORDED BY THE POLICIES DESCRIBED HEREIN IS SUBJECT TO ALL THE TERMS. -_
-_ EXCLUSIONS AND CONDITIONS OF SUCH POLICIES.LIMITS SHOWN MAY HAVE BEEN REDUCED BY PAID CLAIMS.
co upTYPE OP INSURANCE POLICY NUMBER POLICY EFFECTIVE POLICY dNM7fON1
DATE BIRDONY) DATE OUNDLYFYI UWTE
-.
A E SINSPAL Larry 34UUNEX2070 10/01/98 10/01/99 GENERALAGGnEGAn 132, 000,000
FCCAIRRECIAL leak UNN TY PITowcrecOMP,OPAGO 32, 000. 000 ^^
Naaswoe ®OCOJR PER.4ONALIADVIWURY ,31, 000, 000
I OWNERS 3GOHTRACTORs PROT EICN wa OCCU ill, 000, 000CI
RITE DAMAGE(Am DiPOI 3300, 000
IMO DIP(Any omperson) 310, 000
A Augaa.EElwlnr 34USNEX2190 10/01/98 10/01 99
z ANYAuro CDMRunO3umEu3ur 31, 000, 000
I i AU.OWNe:AUTDE ^
I ••SCHCOW AUTOS
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- ^
1..._)_7 HIRED MROB
BODILY
1 X 1 NON-OWNED AIMS eracc ant) 3 —
,—J PROPnOYOMMOE I3
° °E AUTO oALYEAACCIo€a 1, ^iw
I I ANYAUTO
1 OTHER THAN AUTO OILY: ...
EACH AC233lNT 3
71
AOOIEOATE 3
A j e eeewwun 34XHUEX1980 10/01/98 10/01/99 EAa+omumweCE $2, 000. 000
120 UM3nB Ga LAFORM AReaTE 32, 000,000 ^
I OTMERTHANUMBRELLAPCPM Retention 1,10, 000
B I WORKERS COMFeYATMNMID 618052 10/01/98 10/01/99 XISTATUIDRYLWIn i .
I aeLOYBRC'UIINNIY •.. _
IEACH ACCIDENT $100,000
veAansRi n Iue PROWEETOW )( pia awARErcu ruMrt 3500f0 00
I OPPICERe ARC OIEEAEE-EACH EM0.0YR2 310 0, 0 0 0
CIms+L Architects/ PL70060B/DEX700608 10/22/98 10/22/99 $2, 000, 000 Each Claim
ngineera $2, 000, 000 Aggregate _
rofessional $100, 000 Dedt Ea Clm
iability _,
DBECPVRON OF ATIOM LCCATIDMenvROLEEMPECU LRJNE
Pulte Home Corporation is listed as an Additional Insured Under General &
Auto Liability only in respects to their interest in the work performed by
the insured on any and all projects as per written specified contract.
—
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cenwicATE;abSe:'.. r' ':J.CT4 i -`2 'A,�;, d ".• '.c
. ....r SHOULDANY OF THE ABOVE DESCRIBED POttU SE CANCELLED EERIER THE ^
Pulte Home Corporation (9) OVIRATIOI DATE THEREOF,THE FOUND COMPANY WILL ENDEAVOR TO MALL
Attnt Vicki M. Honeywell 3(L DAYS WNrrEN Nom To macarmMCAn,c.on NAMED TOTS LEFT, ^
100 Inverness Terrace East; SUT MIAMI TOMALL$UCHNOOCE SHALL IMPOSE NOOBLIGATWI oft LIABILITY _
Suite 200 OF ANY NE_UPON 111E COMPANY, ITS AGENTS OR REPRuueITA1NEe.
Englewood, CO 80112 Iy1l /gs 37 al -
ACORD 2S-S(DIES)];.of 1' *526272/M20571 - . 9JG E ACORD CORPORATION IBA
-.
Jut-Ul-2UO2 MON 02:28 PM P. 008/056
PULTE HOME CORPORATION 6101/$7
LAND DEVELOPMENT
ENVIRONMENTAL CHECKLIST
SOIL BORING EVALUATION FORM
Parcel: WAITHAM PROPERTY (NORTH HALF)
County: WELD
In Perforndng the requested work,the driller should also look for and record the following condition
If they occur on the parcel;
a
CHECK IF LOCATION OR
FOUND BORING NUMBER
1. Unusual Soil Coloration or Streaking
(Surface or Subsurface)
2. Disturbed Soil(Surface or Subsurface)
3. Fill Materials:
A. Sol)not Native to Site X TH-14. TH-16
B. Debris Fill(metal,glass,
concrete,garbage,etc.)
4. Areas of Sparse, Sick or Dead Vegetation
S. Drums,Storage Tanks or other Containers �_ TM-1 7
6. Discolored/Polluted Water(ground
or surface)
a 7. Unusual Odors:
A. chemical/Solvent
.. B. Gasoline
C. Rotten Egg/Sewage
D. Oil or Fuel Oil
COMMENTS AND SUMMARY: AN OIL AND AS WELL WAS LOCATED WEST OF TH-17
BETWEEN TH-16 AND TH-17 Ate A - IPELINE APPEARED TO BE BURIED FROM
THE PUMP STATION TO THE SOUTHW :7 C• •NER • THEA- "CEL. TH-10 THRU
TH-21 WERE DRILLED ON THE 4U- l F C-4t r? CAI Pt RPRCFR
NO OBVIOUS ENVIRONMENTAL CON NS .
Signed �i/�//,` �, ailyr° • :--S •C
FR K .1. OL , PE *t / %,
j� �
••�� ..ref 1
c -..
Company CTL/Thomason.inc.
JUL-01-2002 MON 02:28 PM P. 009/056
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EXHIBIT A GEOLOGIC AND PRELIMINARY GEOTECHNICAL INVESTIGATION
PORTION OF WHITHAM PROPERTY(NORTH HALF)
SOUTHEAST OF COUNTY ROAD 26 AND COUNTY ROAD 3% • _
WELD COUNTY, COLORADO
Job No. FC-1107
►ULT!NOM!CORPORATION
WHHTIAM PROPERTY INORTN MAIM
CLTIT FG1107
JUL-01-2002 MON 02:28 PM P. 010/056
^�
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GEOLOGIC AND PRELIMINARY
(3EOTECHNICAL INVESTIGATION
PORTION OF WHITHAM PROPERTY(NORTH HALF)
SOUTHEAST OF COUNTY ROAD 26 AND
COUNTY ROAD NO.3%
•
WELD COUNTY, COLORADO
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Prepared For.
Pulte Home Corporation
100 Inverness Terrace East, Suite 200
Englewood, Colorado 80112
Attention: Mr.Jim Miller
Job No. FC-1107
November 17, 1998
PULTE NOME CORPORATION
,., YMntAM PROPERTY WORM HALF)
CLT/T FC41a7
a
JUL-01-2002 M0N 02:29 PM P. 011/056.
`Qj
TABLE OF CONTENTS -
SCOPE 1
SUMMARY OF CONCLUSIONS 1 SITE 2
PROPOSED DEVELOPMENT 3
PREVIOUS INVESTIGATION 3 SITE GEOLOGY AND GEOLOGIC HAZARDS 4
SUBSURFACE CONDITIONS 6
SITE DEVELOPMENT 9 —
Ground Water 9 —
Grading 11
Slope Stability and Erosion 13 Utility Construction 13
Pavements 14
RESIDENTIAL CONSTRUCTION CONSIDERATIONS 14
Foundations 15
Slab-on-Grade and Basement Floor Construction 16
Basements 16 SURFACE DRAINAGE 17
CONCRETE 18
LIMITATIONS AND ADDITIONAL INVESTIGATION 19
FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS FIG.2- ESTIMATED BEDROCK DEPTH `
no. 3 - ESTIMATED BEDROCK ELEVATION
FIG.4- ESTIMATED GROUND WATER DEPTH
FIG. S- ESTIMATED GROUND WATER ELEVATION -
FIGS. 6 THROUGH 8 -SUMMARY LOGS OF EXPLORATORY BORINGS
FIGS. 9 THROUGH 16 -SWELL CONSOLIDATION TEST RESULTS -
FIG. 17 -GRADATION TEST RESULTS
FIG.18 -TYPICAL SEWER UNDERDRAIN DETAIL -
FIG. 19 -SANITARY SEWER MAIN UNDERDRAIN DETAIL
TABLE I -SUMMARY OF LABORATORY TEST RESULTS
APPENDIX A -GUIDE SITE GRADING SPECIFICATIONS
HUM HOME CORPORATION ..,
WHITMAN PROPERTY)NORTH HALF)
CLTIT PC.1107 -
JUL-Ill-AWL tIUN UZ:Z YM P. 012/056
i1
SCOPE
This report presents the results of our geologic and preliminary geotechnical
- investigation for the north about one-half(parcel) of the Whitham Property, located
^ southeast of the Intersection of County Road 26 and County Road No. 3'/, in Weld
County, Colorado(Fig.1). The Pulte Home Corporation is considering purchase and
plans to develop the parcel as a subdivision for single-family residences.
We Investigated the geology and subsurface conditions at the parcel to
evaluate the affect of the geology,the soils,the bedrock and the ground water on the
proposed development of the parcel and the design and construction of residences
•
in the proposed subdivision. This report presents the results of our field and
laboratory studies and our conclusions, opinions and recommendations regarding
the proposed development and the design and construction of the residences from
the geotechnical viewpoint Our conclusions are summarized below.
SUMMARY OF CONCLUSIONS
1. The ground under the parcel Is a thin to thicker(2 feet to 28 feet thick)
layer of wind blown clays over sedimentary (claystone, sandstone,
siltstone) bedrock. Ground water is comparatively shallow to deep (3
feet to 24 feet deep depending on location). The clays showed no
tendency to swell (expansion)and slight potential for consolidation in
our tests. The bedrock showed low swell In our tests.
2. The ground water depth is above typical residence basement depth
(measured from existing grade) under the south and east sides of the
parcel. The parcel surface elevations could be raised using
engineered fill to increase the depth to ground water from the ground
surface so basement floors can be placed at least 3 feet above the
expected ground water surface or a parcel wide subdrain could be
Installed to lower the ground water surface to at least 3 feet below
basement floors. A combination of the two alternatives might be the
more feasible. Draining the subdrain system by gravity will be
difficult, if possible, because of topographic constraints. This
suggests lift stations might be needed to lower the ground water using
a subdrain. In addition, to a form of parcel-wide subdrain the
proposed residences will need foundation drains connected to the
parcel-wide subdrain.
auuE HOME coavorunaN
WWT1W4 PROPOnY(NORTH HALF)
"' CTUT FC-1107
JUL-01-2002 M0N 02:29 PM P. 013/056
3. A successful parcel wide subdrain will tend to lower the ground water
elevation under Oligarchy Ditch which bisects the parcel near the
south boundary. The affect on Oligarchy Ditch will need consideration
when evaluating the decision to install a parcel wide subdrain.
4. The clays at the site can be characterized as nil to low expansive and
the bedrock as low expansive. We believe footings can be the
foundations for the residences proposed for the subdivision if the final
lot grades are at or above the existing natural grades. The finally
selected site grading plan will determine if the foundation strata for a
given residence foundation will be footings bearing on clays or
footings bearing on the bedrock. The tendency for swell in the
bedrock will cause the footing design criteria to include criteria for a
minimum dead load for both bearing strata.
Much lowering of the final grades below the existing natural grades
will probably result in drilled piers as the preferred foundation..
5. The natural clays and bedrock can be the subgrade for slab-on-grade
basement floors. Considerations for slab-on-grade basement floors
are discussed in "Slabs-on-Grade and Basement Floor Construction"
subsection.
6. The natural clays are a weaker subgrade for pavements. Residential
streets will probably require full-depth asphaltic concrete pavement
thicknesses of the order of 6 inches (4 Inches of asphaltic concrete
over 8 inches of the compacted base course) and thicker pavement
sections for collector and arterial streets. These sections could be
thinned by strengthening the subgrade with lime or other strengthener.
7. Control of the surface water will Influence the performance of
foundations, slab-on-grade floors and pavements. Surface ground
contours and drainage structures must cause rapid runoff of surface
water away from structures and removal of the water from the area.
SITE
The site(parcel) is located southeast of the intersection of County Road 26 _
and County Road No.31/2 in Weld County, Colorado(Fig. 1). The parcel is currently
planted with corn. From the northwest corner of the parcel, the ground surface
slopes down gradually to the south and east. No significant erosional features were
observed. The improvements on the parcel are fences and a graveled road extending
from the southeast corner through the middle of the parcel toward its north end.
Storage tanks for oil and gas production are located near the center of the site, and
KILT[MOM[CORPORATION
wMRMAM PROPERTY(NORTH HALF)
=UT FO-H07 2
JUL-01-2002 M0N 02:29 PM P. 014/056
a pipeline connects the tanks with another pipeline that trends east-west along the
south property boundary. The parcel is irrigated by a series of ditches.
County Road No. 3'% and County Road 26 bound the parcel on the west and
north, respectively. Residences are located southwest of the site across County
Road 3%. Single-family residences are completed and under construction in a
subdivision to the east. Highway 119 is located approximately' mile south of the
site. The subdivision to the east Is graded to drain to a detention pond to the north.
The ground to the south is irrigated farm land.
Oligarchy Ditch Is located near the south boundary of the parcel and flows
from west to east. Calkins Lake Is located northwest of the parcel. The St Vrain
River/Boulder Creek confluence is south of Highway 119, about one-half mite south
east of the parcel.
PROPOSED DEVELOPMENT
This parcel will be a single-family residence subdivision that will adjoin
additional development proposed on the adjacent land to the south. We have seen
no grading plans as of the writing of this report. Utilities for servicing the residential
lots and commercial area will be buried under the streets.
We have assumed for this analysis the residences that will be built in the
proposed subdivision will be mostly two-story wood frame structures with full
basements. Typically these kinds of residences will have some stone and/or
^
masonry veneer on the exteriors.
PREVIOUS INVESTIGATION
The parcel of land currently under consideration adjoins a 250 acre parcel
previously considered by Pulte Homes. CTL/Thompson, Inc. conducted a geologic
and preliminary geotechnlcal investigation at that site. Details regarding our
PULTE HOME CORPORAT1OH
^ WHnMAM PRO►f w 4NORTh MALI)
CrUT rc4,m 3
JUL-U1-2UU2 M0N 02:30 PM P. 015/056
investigations, observations, conclusions and recommendations are presented in
our report no. FC-1044, dated August 11, 1998.
Information from our previous exploratory borings, laboratory testing and
engineering analyses were used in preparation of this report, as appropriate. The
locations of the previously considered site and three of our exploratory borings for
that investigation are shown on Fig. 1 (attached). Exploratory borings for this
investigation are numbered sequentially following those of the previous
Investigation, and elevations are referred to the same temporary benchmark to
facilitate comparisons between the two projects.
SITE GEOLOGY AND GEOLOGIC HAZARDS
The parcel Is located within the Colorado Piedmont section of the Great Plains
physiographic province. The Piedmont is a broad erosional trench which separates
the Southern Rocky Mountain fromthe High Plains. Mapping by R.B. Colton (USGS
Map I-855-G, Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado 1978)
indicates the surface of the parcel is Eolian (Qe)deposits consisting of olive-brown-
gray windblown clay, silt and sand. The underlying bedrock consists of the Upper
Transition Zone of the Pierre Shale (Kptz), which Is described as interbedded
sandstone and shale with hard sandstone ledges and water with high sulfate •
content. The thickness of the Pierre Shale Is about 2,800 feet. We believe the Pierre _
Shale dips gently to the east in the area of the parcel. Our field exploration generally
confirmed the conditions described by published maps.
This section discusses geologic hazards that we believe could affect land
planning and zoning. Specific requirements of Colorado House Bill 1041 "Areas and
Activities of State Interest" and Colorado Senate Bill 35 "County Planning and
Building Codes" are addressed.
The claystone phases of the bedrock are expansive. This can result in more +
or less damage to Improvements or structures depending upon the characteristics
of the ciaystones and the increase in moisture that occurs. Engineered design of
PULTE NOME CORPORATION
WHITNAM PROPERTY(NORTH HALP) 4
CTUT PC-110
^
JUL-01-2002 MON 02:30 PM P. 016/056
iss.40'1
pavements, foundations, slabs-on-grade and surface drainage can mitigate the
effects of expansive bedrock. The soils and bedrock under this parcel are not
^ expected to be unusually corrosive to metal but may have sulfate concentrations that
can affect concrete. Natural slopes are gentle and appear to be stable.
Significant faulting and structural discontinuities are not expected in the
bedrock at this site. The soil and bedrock units are not expected to respond
unusually to seismic activity. The area is considered by the most recent editions of
the Uniform Building Code (UBC) as Zone 1, its least active zone designation.
Maximum bedrock accelerations at 4 to 7.5 percent of gravity are probable during
major earthquakes in the area. Only minor damage to relatively new, properly
designed and built residences would be expected.
Regarding the potential for radioactive substances on the parcel, it Is normal .
In the Front Range of Colorado and nearby eastern plains area to find significant
accumulations of radon gas in poorly ventilated spaces (i.e.,full-depth residential
basements) in contact with soli or bedrock. Radon 222 gas has been shown to be
a health hazard and is just one of several radioactive products with a short half-life
in the chain of the natural decay of uranium into stable lead. There is no geologic
.. property of the soils and bedrock at this parcel that would make radon gas any more
likely than other areas of the Front Range of Colorado. The amount of radon gas that
can accumulate in an area is a function of many factors, including the radionuclide
- activity of the soil and bedrock, construction methods and materials, soil gas
pathways, and accumulation areas. Typical mitigation methods consist of sealing
soil gas entry areas and ventilation of below-grade spaces. Radon rarely
accumulates to significant levels in above-grade living spaces.
The parcel does not appear to be flood prone. There are no highly-developed,
Incised drainages on the parcel.The very gentle topography of the parcel indicates
little, if any, water would be expected to flow onto the parcel from outside the
boundaries and there is no geologic indication of periodic flooding as evidenced by
the absence of recent quatemary alluvium. The erosion potential on the parcel is
- considered low, due to gentle slopes. The erosion potential can be expected to
PULTG Mown CORPORATION
WHTIAw PROP{RT')NORTH MALI)
^ a1Ln PC-1101
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increase during construction, but should return to pre-construction rates or less If
proper grading practices, surface drainage design and revegetatlon efforts are
implemented.
We do not believe the parcel is located above underground mines or is -
located In a subsidence hazard zone. The bedrock below the parcel is the Pierre
Shale formation which does not contain significant coal beds. There Is no evidence of past mining activities on the parcel.
No economically Important mineral deposits are expected on this parcel or are
known to occur nearby. We do not expect ground subsidence related to natural or —
mining processes. -
The borings we drilled on the parcel showed ground water was shallow under the parcel. It was above typical basement depth(measured from the existing ground
surface). The development strategy for a parcel with shallow ground water usually
includes consideration of a parcelrwlde subdraln, foundation drains around _
basements, raising the natural ground elevations with engineered fill to provide the _
needed distance above ground water for basements and probably other mitigating
measures.
No geologic hazards which would preclude the proposed development were
noted on the subject tract. The shallow ground water will require attention. We
believe the geologic hazards can be mitigated with proper engineering design and
construction practices, as discussed in this report.
SUBSURFACE CONDITIONS
Clays and sands overlying sedimentary, interlayered claystone, sandstone
and slltstone; claystone; and sandstone bedrock were penetrated by the 9 borings
we drilled to investigate the parcel subsurface and the 3 borings for our report no.
FC-1044. The approximate boring locations are shown on Fig. 1 and are labeled
PULTE HOME CORPORATION
WHITMAN PROPERTY(NORTH HALF)
ctJT PC-MIT a
JUL-01-2002 M0N 02:30 PM P. 018/056
TH-10 through TH,21. Our borings were drilled with a 4-inch diameter, continuous
flight auger and a truck-mounted drill rig. The drilling operations were observed by
our field representative who logged the soils and obtained samples for laboratory
testing. Graphic logs of the soils found in our borings Including results of field
penetration resistance tests are shown In Figs. 8 through 8. Samples obtained
during drilling were returned to our laboratory where they were visually classified
and selected for testing. The results of our laboratory tests are on Figs.9 through
17 and summarized in Table I.
Si!. Two of our borings,111-14 and 111-16, contained approximately 1 foot of
man-placed fill that consists of clayey sand and gravel mixed with sandy,silty clays.
The fill is base course placed on and adjacent to an existing road on the property.
Clays The upper subsoils found in our borings generally consisted of very
moist, medium stiff, sandy clay that was at depths of 2 to 28 feet. The clays are
comparatively weak so foundations bearing on the clays will need to be designed for
.. lower bearing pressures. We selected several samples of the clays for swell-
consolidation tests. The samples consolidated when wetted under an applied load
of 1,000 psi, as shown in Figs. 9 through 10. We believe the majority of the clays
possess nil to low expansion potential. The majority are more likely compressible
because they are wind blown (lower natural density) and have higher moisture
contents.The clay samples tested had moisture contents of 16 to 29 percent, liquid
limits of 30 to 39 percent, plasticity indices of 12 to 25 percent, and contained 83
percent silt and clay size particles (passing No.200 sieve).
Sand. One of our borings,TH-21,penetrated 3 feet of moist,medium dense,
silty sand at a depth of 10 feet. This strata was identified near the northeast corner
of the site and suggests a change in the subsurface toward the northeast
PULTE HOME CORPORATION
WHITMAN PROPERTY(NORTH HALF)
CM PC-110? 7
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i
)jttdrnck The bedrock found In our borings underlying the clays at 2 to 28
feet deep was claystone, sandstone and interbedded claystone, slitstone and
sandstone. The interbedded bedrock was predominant, however, the site geology
Indicates discontinuous lenses of bedrock may be cemented. A cemented
sandstone lense was encountered in boring TH-12 at about 8 feet. Our estimated ^_
depth to bedrock contours are shown on Fig.2 and our estimated bedrock surface
elevation contours are shown on Fig.3. The upper 1 to 2 feet of the bedrock In 2 of
the borings was weathered to a stiff clay. The underlying bedrock was hard to very
hard. The weathered claystone,sandstone,and interbedded claystone,slitstone and
sandstone bedrock Is Judged to be nil to low expansive. Samples of these materials
were swell tested in our laboratory and exhibited slight compression to low swell
when wetted under an applied load of 1,000 psf. The shallower claystone samples
tested were moist due to the shallow ground water conditions and exhibited lower ^
swell. The deeper claystones were less moist and can be expected to show low to •
moderate swell potential. Samples of the claystone had moisture contents of about
14 percent
around wntpr Free ground water was encountered in 9 of our 12 borings at
depths from 7 to 18 feet at the time of drilling and In all of our borings at depths of ^
2 to 24 feet when checked several weeks after drilling. Measurements were taken
June and July in boring TH-10 through TH-12, and in October when ground water
levels In the area tend to be comparatively low In borings TH•13 through TH-21. The
parcel was not being irrigated while we were drilling our borings TH-13 through TH-
21 and during the Urns we made subsequent ground water depth measurements in
these borings. However,future lawn irrigation,paving and development will likely
increase the local ground water elevations when the vicinity is fully developed. Fig.
4 shows our estimate of the depth to ground water and Fig. 5 shows our estimate of
the contours of the elevation of the ground water surface using our interpretation of _
both our June and July 1998 and our October, 1998 measurements.
The behavior of the ground water at this parcel is not yet well understood.
Calkins Lake is about one-half mile northwest of the parcel. Though we believe It
remote, It Is possible Calkins Lake influences the ground water in the vicinity of the
PULTE HOME CORPORATION
WHITHAM PROPERTY(NORTH HALF)
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parcel. We recommend continuing measurements of ground water depth in the
borings we drilled to better understand the ground water behavior. Temporary
perforated, plastic casings were placed in the borings to facilitate future ground
water depth measurements.
SITE DEVELOPMENT
We have identified no geologic or geotechnical conditions that should
preclude development of this parcel. The ground water is shallow, above typical
basement floor depth (measured from existing, natural grade). The clays overlying
the bedrock are lower strength and phases of the bedrock have lower expansion
potential. We have discussed our opinions and recommendations regarding each
of these Issues below. We have also discussed site grading,pavement construction,
utility installation and construction of permanent slopes for long term stability and
protection against erosion.
Ground Water
Present plans are to build residences with basements. The ground water
depths we measured in our borings are at or above typical basement depths if the
existing ground surface in the proposed subdivision is not altered much during
grading. Therefore, changes to the existing condition will be necessary to make
basements feasible. In our opinion, two alternatives seem technically feasible,
namely:
a. Install a parcel wide subdrain system to lower the ground water under
the parcel so it will be at least 3 feet below the basement floor
elevations at the residence locations and provide foundation drains
around all residences. Fig.18 shows conceptually this alternative; or
b. Raise the ground surface elevations enough that basement floor
elevations at the residence locations will be at least 3 feet above the
depths to ground water shown on Figure 3 and provide foundation
drains around all residences; or
c. A combination of(a) and (b) above.
•••••• PELT!HOME CORPORATION
WNRHAM PROPERTY(NORTH HALF)
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giihdralr1. Two complications we can visualize for the area wide subdrain are
topographic constraints and the Oligarchy Ditch. It will be difficult at best to drain
a subdrain by gravity. This suggests lift stations may be needed to drain the
subdrain. Regarding the Oligarchy bitch,the subdrain will tend to lower the ground
water elevation under the ditch also and may influence leakage from the ditch.
These complications will need to be reviewed as part of the decision to install a
parcel-wide subdrain. Additional investigation may be needed If a parcel wide
subdrain is a selected alternative. Such an investigation would be aimed at better
Identifying the possible sources of ground water, and measuring the permeability of _
the soil and bedrock to recommend a drain configuration and drain sizing.
The parcel wide subdrain we envision will be a combination of an Interceptor a
drain along most of the west,the north and a part of the east side of the parcel and
an underdrain below all the sanitary sewer mains under the streets. The invert •
elevation of the interceptor, it appears to us,will be dictated by the elevation of the
bedrock(Fig.5) near the southeast corner of the property, near the midpoint of the
south property boundary and the east boundary where the elevation is lower
compared with the remainder of the parcel. It is Important that the invert of the
interceptor everywhere be at least one foot below the bedrock surface but it musta
also be sloped from Its high point to drain. The underdrain system Installed belowa
the sanitary sewer mains will supplement the Interceptor and serve as an outlet for
individual residence foundation drains (see "Basements" subsection). The -'
underdrains should be provided with cleanouts so they can be regularly maintained.
If the sewer district will not maintain underdrains, the home owners' association
should be empowered to provide maintenance and be provided copies of"as-built"
plans.
The underdrains would be an appropriately graded filter material surrounding
a pipe. The pipe should be sized for the flow determined after the recommended
ground water investigation is completed.The drain pipe should consist of smooth, _
perforated or slotted rigid PVC pipe laid at a grade of at least 0.5 percent. The filter
material should have a cross-section of at least 2 square feet. A typical sewer
underdrain detail is shown on Fig. 19. A positive cutoff collar(concrete) should be
PULYI HOet CORPona'nON
wsmuu PROPtare NORTH Hal)
CTVTPC4107 10 '�
JUL-01-2002 MON 02:32 PM P. 022/056
constructed around the sewer pipe and underdraln pipe immediately downstream of
the point the underdraln pipe leaves the sewer trench. Solid pipe should be used
down gradient of this collar to the daylight or collection point The underdraln
should be designed to discharge to a gravity outfall or to a series of lift stations. If
lift stations or any system that could temporarily fail are used, we recommend a
a
check valve be placed on the underdraln service to each house, and cutoff collars
be constructed to prevent backflow through the filter gravels. We further
recommend backup pumps for each lift station pump and backup, on-site,electricity
generators that will automatically turn on when the subdivision power fails.
fligarchy Ditch. The effect of the parcel subdrain on Oligarchy Ditch needs
to be investigated during the recommended ground water investigation. Should the
study show a probable Increase in leakage from the ditch we believe the ditch will
need to be lined. Several liners are available but we believe the more feasible Is •
probably Portland cement concrete. This needs to be confirmed during the
-� Investigation to determine if the ditch will be affected by the subdrain.
Grading
Overlot grading should be engineered fill that Is compacted under controlled
conditions. Areas to receive grading fill need to be cleared, grubbed and stripped
of all vegetation,organic topsoil and other deleterious matter. The cleared, grubbed
and stripped materials should be discarded or placed In areas that will never be
under structures, utilities, sidewalk, curbs and gutters, driveways or pavements.
After stripping, the resulting subgrade should be scarified, moisture
conditioned to 0 to 3 percent above optimum and compacted to obtain a firm
platform for fill placement. Our borings indicate some soft soils exist on the parcel.
Where soft soils are encountered, they can be stabilized prior to placing fill.
Stabilization of soft subgrade soils is often accomplished by removal and
replacement, scarifying and drying, utilizing geosynthetics or"crowding" crushed
rock into the subgrade until a firm surface Is achieved.
PULTE HOME CORPORATION
^ WHITHAM PROPERTY{NORTH HALF)
OUT FO1107 11
^
JUL-U1-2UO2 MON 02:32 PM F. 023/056 —
The properties of the flit will affect the performance of foundations, slab-on- _
grade floor and pavements. The soils from the parcel are suitable for use as grading _
fill. Claystones should be broken down before placing as fill. If imported materials
are necessary, they should consist of sandy clays that are low plastic and low _
expansion like the on-site clays. A sample of all soils proposed for Import for fill _
should be submitted to our office for classification and approval prior to hauling
them to the site. Fill should be placed in thin loose lifts, moisture conditioned to 0
to 3 percent above optimum moisture content and compacted to at least 95 percent
of standard Proctor maximum dry density (ASTM D 698). Guide specifications for
overlot grading are in Appendix A. Placement and compaction of the grading fill
should be observed and tested by a representative of our firm.
For the most part,the soils and bedrock at this parcel are nil to low expansive.
in addition the shallow ground water appears to have"pre-wetted" and decreased •
the swell potential of the upper approximately 10 feet of soils and bedrock. Deeper
claystone bedrock was moderately expansive under the adjacent parcel. If the
existing grades are lowered by cutting, this claystone will begin to influence .
structure foundation type. If possible,site grading should be planned to provide at
least 4 feet of nil to low expansive clays or fill above the claystone bedrock so that
special foundations can be avoided.
Preliminary data shows that if the natural ground grades are lowered the
claystone bedrock may affect the choice of foundation type for our estimated 10
percent of the parcel area. The claystone under the parcel is not steeply dipping but
it has swell potential. Residences built In areas of expansive soils and bedrock are
susceptible to damage from heave caused by wetting and swelling of expansive
soils and bedrock. Special precautions are needed in the construction of
foundations and other elements to mitigate the effects of swelling soils/bedrock. In
our experience these techniques can and have reduced the damages to residences
when the expansive solls/bedrock like those on this parcel get wet.
PULTE HOME CORPORATION
AMMAN PROPERTY(NORTH HALM ,�Z
CM FC.1107
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•
� ,
Slope Stability and_E Design
We observed no evidence of slope Instability or significant erosion on the
parcel. For the type of soils present at this parcel, we believe permanent slopes
^' should be 3:1 (horizontal:vertical) or flatter. Surface drainage should not be allowed
to sheet flow across slopes or pond at the crest of slopes. Slopes should be
revegetated as soon as possible to reduce potential for erosion problems. Localized
slopes enclosing retention/detention ponds should be designed by a qualified Civil
Engineer with erosion control and slope stability in mind.
Utility Construction
The bedrock penetrated by our borings was hard to very hard and included
cemented, very hard sandstone lenses. We believe most of the materials can be
excavated with either heavy duty trenchers or large backhoes, however, ripping or
other means may be required to loosen the cemented, bedrock lenses.
Medium stiff clays and hard interbedded sandstone, claystone and siltstone
are predominant We believe the clay soils on this parcel can be classified as Type
C, and bedrock as Type A or Type B based on the Occupational Safety and Health
Administration (OSHA) standards governing excavations. Type C soils require
maximum slope inclination of 1.5:1 (horizontal:vertical), Type B soils require
maximum slope Inclination of 1:1 (horizontal:vertical) and Type A soils require a
maximum slope of 314:1 (horizontal:vertical). The contractor's competent person on
a site should Identify the soils encountered in excavations and refer to OSHA
standards to determine appropriate slopes. Excavations deeper than 20 feet should
be designed by a professional engineer.
Ground water will be encountered during utility excavation. The clays and
bedrock at this parcel are expected to be low to moderately permeable. Ground
water seepage will be slow to moderate. We anticipate trench dewatering may be
accomplished by sloping the trench bottom to collection areas where water can be
removed by pumping, however large, heavy duty pumps should be anticipated.
PULTI NOME CORPORATION
... WNmNAM PRO►ORTY(NORTH HALF( - 13
unit PC.ii0T
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•
Some zones of sandier clays and more permeable sandstone bedrock may exist
requiring the occasional use of well points or other means to lower ground water and
allow for excavation.
Water and sewer lines are usually constructed beneath paved roads.
Compaction of trench backfill will have . significant effect on the life and
serviceability of pavements. We recommend trench backfill be placed In thin, loose
lifts, moisture conditioned to 0 to 3 percent above optimum moisture content and
compacted to at least as percent of standard Proctor maximum dry density (ASTM
D 698). The placement and compaction of fill and backfill should be observed and
tested by a representative of our firm during construction.
Pavements'
•
The surficial soils found on-site have fair to poor pavement support qualities.For preliminary planning purposes, we suggest assuming 6 inches of full depth —
asphaltic concrete paving will be needed for local residential streets.A section using
asphaltic concrete and compacted base course would be 4 inches of asphaltic
concrete over 8 inches of base course. Thicker pavements will be needed for
collector and arterial streets. A subgrade investigation and pavement design should
be performed after overlot grading Is complete.
The softer clays we found may rut and"pump" during subgrade preparation.
Should this occur they can be stabilized as described above so that they will support
construction equipment.
RESIDENTIAL CONSTRUCTION CONSIDERATIONS
Two-story residences with full basements are planned for the proposed
subdivision. Ground conditions and characteristics across the parcel Include very
moist,medium stiff sandy clays near the surface underlain by ciaystone, sandstone
or interbedded ciaystone,siltstone and sandstone bedrock. The strata at foundation
level will depend upon finally selected finished grades. The following discussions
PULTE HOME CORPORATION
WHRHAM PROPERTY WORTH HAIR ,�4
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.-
are preliminary and are not intended for design or construction. After grading is
completed,a detailed soils and foundation investigation should be performed on a
lot specific basis.
Founriatinnc
The foundations that can be used to found the proposed residences will
depend upon how the parcel is graded. In our opinion, if the parcel finished grades
are at or above the existing natural grades at the residence locations the residences
can be founded with footings bearing on the soils/bedrock at footing elevation.
Some of the residences will likely be founded with footings bearing on the natural
clays and/or compacted overlot fill and others will be founded with footings bearing
on the bedrock. We expect the maximum design bearing capacity for footings
bearing on the clay will prove to be of the order of 1,500 pounds per square foot(psf) .
and the bearing capacity for footings bearing on the bedrock will prove to be of the
order of 8,000 psf. The maximum design capacity for footings In areas where the
bedrock is deeper may be of the order of 3,000 psf. It will be prudent to design all
footings for a minimum dead load of the order of 30 percent of the maximum design
bearing capacity.
A grading plan that results in finished grades lower than the existing natural
ground elevation we estimate will result In needing to found at least 10 percent of the
residences with drilled piers penetrating the bedrock. We expect the maximum end
bearing pressure for piers will prove to be of the order of 36,000 psi and the side
shear value In the bedrock 10 percent of the maximum end bearing capacity. The
minimum design dead load pressure will be of the order of 1000 psf.The minimum
penetration for piers Into bedrock will probably prove to be 6 feet, the minimum
length for piers will probably prove to be 16 feet and flinch void spaces will likely be
needed under grade beams between the piers. There is the possibility some piers
will need to be cased to dewater and clean the pier holes due to the ground water
found under the parcel.
PULTE NOM!CORPORATION
WHITMAN PROPERTY(NORTH HALF)
15
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•
Slah.en-Grads and Basement Flonr Pnnstruetinn
Slabs-on-grade are typically used for basement floors on lots with soil _
conditions similar to this parcel. Our firm generally recommends structurally
supported basement floors for high (4 to less than 6 percent) and very high (6
percent or greater) swell potentials. Preliminary data Indicate structural basement
floors will not be required on any of the lots on this parcel. Site grading cuts in
areas where bedrock is shallowest should be avoided to keep basement floors above
the bedrock or as far up In the more moist, lower swelling portions of the bedrock
as possible.
The following precautions will not eliminate slab-on-grade movement but will
reduce the potential for damage due to movement of slabs:
•
1. Isolation of the slabs from foundation walls, columns or other slab
penetrations;
2. Voids under Interior partition walls to allow for slab movement without
transferring the movement to the structure; —
3. Flexible water and gas connections to allow for slab movement. A
flexible duct above furnaces may also be required; and
4. Proper surface grading and foundation drain Installation to reduce
water availability to slab subgrade and foundation soils.
Rosemont%
Free ground water was shallow in our borings drilled during this investigation
and will affect basement construction. Control of ground water levels below
basements will be needed for basements. A parcel-wide subdraln is discussed
above. Foundation drains will be needed around all crawl spaces and basements.
This requirement will hold regardless of the finally selected finished grade —
elevations.
We suggest foundation drains be connected to the sewer underdraln system
with a piped connection. A typical detail for a connection from the foundation drain
RULl!NOW CORPORATION
WHRHAM PROPERTY(NORTH HALF)
CUR Fc.1to7 16
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to the underdrain is provided on Fig. 19. Sump pits with pumps should be Installed
as a backup if underdralns do not perform as intended.
We discussed drainage systems for control of ground water under the parcel
and the possible limiting affects of ground water conditions on providing basements
for the proposed residence. Typically,foundation drains are comparatively shallow
relative to the bottom of a slab-on-grade floor or the floor of a crawl(air) space under
a structural floor. Where the ground water is likely to within 3 or 4 feet of a floor we
recommend an undersiab gravel layer and deeper foundation drains. Further, we
recommend basement floors be at least 3 feet above the anticipated ground water
surface. If a parcel-wide subdrain is Installed the 3 feet should be measured from the
ground water level that will result from the subdrain design.
Basement excav
ations that penetrate the ground to near the ground water
surface may require dewatering and the soils In the excavation floor may be soft.
Should soft soils be encounters,the excavation floor may need to be stabilized so
it will support traffic.
Basement and crawl space walls will be subjected to lateral pressure from the
wall backftll. Such wails should be designed to resist the higher "at rest" lateral
earth pressure because they are not free to rotate and develop the internal strength
of the backfill. We expect the backfill will be the clays from required excavations for
the residences and suggest assuming for preliminary designs an equivalent fluid
density of 50 pcf for backfill in design calculations.
SURFACE DRAINAGE
The performance of improvements In this development will be Influenced by
surface drainage. When developing an overall drainage scheme, consideration
should be given to drainage around each residence. Drainage should be planned so
that surface runoff Is directed away from foundations and is not allowed to pond
adjacent to or between structures or over pavements. We recommend slopes of at
least 12 Inches where possible in the first 10 feet for the areas surrounding all
HILTR HOME CORPORATION
... WHITMAN PROPRRTY(NORTH HALF)
CnJT►C-1107
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residences or buildings. in areas between houses which are less than 20 feet apart,
the slope should be at least 10 percent toward the swabs used to convey water out
of these areas. Slopes marginally less steep than those recommended may be
necessary at the back of the houses on lots which drain to the front. Roof
downspouts and other water collection systems should discharge well beyond the
limits of all backfill around structures.
Proper control of surface runoff Is also Important to control the erosion of
surface soils. Sheet flow should not be directed over unprotected slopes. Water
should not be allowed to pond at the crest of slopes. Permanent slopes should be
revegetated to reduce erosion.
Attention should be paid to compact the soils behind curb and gutter adjacent
to streets and parking areas and in utility trenches during development. If surface
drainage between preliminary development and construction phases is neglected,
performance of the roadways, fiatwork and foundations will be poor. When
considering landscaping of common areas,we recommend the use of xerlscaping
which requires little Initial or long-term watering.
CONCRETE
We measured soluble sulfate concentrations for representative samples of the subsoils from our borings. Sulfate concentrations from this and the adjacent —
parcel ranged from 0.1 to 3.7 percent. Based on ACI standards,water soluble sulfate
concentrations In this range represent a severe to very severe sulfate exposure. ACI _.
recommends using a cement meeting the requirements for Type V(sulfate resistant)
cement, with a maximum water-cement ratio of 0.45 and air entrainment of 5 to 7
percent for concrete exposed to soils with this level of soluble sulfates. We _
understand Type V cement may not be readily available locally. As an alternative,
we believe cement which meets ASTM C 150 Type ll requirements and contains 20
percent fly ash can be used to provide similar resistance. The fly ash should meet
ASTM C 618 Class F requirements. The fly ash can be reduced to 15 percent in cold
weather months. ,..,
PULTS HOME CORPORATION -•
WHITHAMPROPERTY(NORTH HALF)
CnJTPc-11m 18
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LIMITATIONS AND ADDRIONAL INVESTIGATIONS
We based the discussions in this report on our understanding of the proposed
development and residences, conditions disclosed by exploratory drilling,review of
geologic maps,site observation,results of our laboratory tests,engineering analysis
of field and laboratory data and our experience. The criteria presented In this report
are intended for aid in purchase decisions and preliminary planning purposes.
Future geotechnical engineering investigations and analysis are required to
formulate design criteria for a parcel-wide subsurface drain system to lower ground
water, geotechnical design criteria for residence,foundations and floors, and street
pavement sections.
Our borings were widely spaced. In our opinion, the boring pattern provided
us the needed picture of the underground to provide the above report Intended to aid
Pulte Home Corporation in their purchase decision regarding the parcel that is the
subject of this report and the planning and development of this parcel. Variations
between the borings will occur. We recommend continuing to measure the depth to
ground water in the borings we drilled to better understand the behavior of the
ground water under the parcel and to guide future decisions regarding installing and •
then designing a parcel-wide, subsurface drain to lower the ground water under the
parcel.
A representative of our firm should be present during site grading and utility
trench backfiliing to observe fill placement and perform compaction tests. Detailed
investigations should be performed for design of residence foundations and slab-on-
grade floors and street pavement sections after overlot grading has been completed.
We should review the final grading plans prior to construction to look for potential
geotechnical problems_
^ PULTE HOME CORPORATION
,., WHRHAM PROPlRTY(NORTH KALE) 19
CUTFC-t1O7
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We believe this investigation was conducted in a manner consistent with that
level of care and skill ordinarily used by geotechnical engineers practicing In this
area at this time. No other warranty, express or implied, is made. If we can be of
further service in discussing the contents of this report or analyses of the influence
of subsurface conditions on the design of the proposed development, residences
and streets, please call.
CTLlTHOMPSON, INC
Tho as Chapel
Pro'= gineer ^
Revi>, :. by:
pi�a\�'yy •
1 1 } w
Fra J. H. '•ay, P C q' i r •
Gcr _
P clp- Engineer .1 i . r=,• ' ' r:•
(5 copies sent) PRANK J. .IGILL?WAY
PISTE HOME CORPORATION
WHITMAN PROPERTY(NORTH NAP)
CTUT FC-1107 20
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.
..
MYDRChflRAWI.YSIS I SIEVE ANALYSIS
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From TM-21 AT 9 FEET SILT s Cu—P-"62% DCUID LIMB 30 %
' PLASTICITY INS 12%
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. I MTaRa01ETE1tANALYSIS
I LEVIMALYSIS
arm TW6 lad AlAtta as.STANDAPD SERIES WPM3 M OMAN
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•
FIRST FLOOR
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GROUNDWATER SURFACE VARIES. FOR POSSIBLE STRUCTURAL
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_ JUL-01-2002 M0N 02:37 PM P. 042/056
•
L
SANITARY SEY/ER
4 PERFORATED
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PVC PERFORATED SUBDRAIN PIPE
SIZE VARIES
SPECIFIED TRENCH 3/$" PERFORATIONS AT 5",
WASHED ROCK 2 ROWS AT 60' FROM VERTICAL
MAXIMUM SIZE: 1" WIDTH PVC PIPE AND FITTINGS
LESS THAN 3% PASSING CONFORMING TO ASTM D 3034,
THE NO. 200 SIEVE SDR 35
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Job No. FC-1107 Fig. 1
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NATURAL ATTERBERG LIMITS UNCONFINED SOLUBLE PASSING lc
BORING DEPTH NATURAL DRY SWELL' LIQUID PLASTICITY COMPRESSIVE SULFATE NO. 200 SOIL TYPE
MOISTURE DENSITY LIMIT INDEX STRENGTH CONTENT SIEVE
�ft %} @d) (%) fl) (1 ) (paq (%) 96 �--��
TH-10 28.6 39 251T3`A D l
TH-10 9 142 117 02 INTERBEDDED CLAYSTONE/SANDSTONE
TH-10 14 13.9 116 0.0 INTERBEDDED CLAYSTONFJSANDSTONE
TH-11 2 242 100 CLAY,SANDY(CL)
_
TH-11 4 1 29.5 92 3.00 CLAY,SANDY(CL)
TH-11 9 11.9 123 0.0 CLAYSTONE
TH-11 14 19.8 109 2.0 _ CLAYSTONE
TH-11 19 12.5 • 125 36 19 73 CLAYSTONE
TH-12 19 18.6 105 0.0 INTERBEDDED CLAYSTONE/SANDSTONE
TH-13 4 18.9 103 0.3 CLAY,SANDY(CL)
TH-14 4 22.4 100 -02 CLAY,SANDY(CL)
TH-14 9 22.6 103 0.0 CLAYLSANDYjCL)
TH-14 14 12.9 123 0.11 CLAYSTONE
_ TH-15 4 182 105 38 23 83 CLAY,SANDY fCL)
TH-15 9 20.6 100 0.0 CLAY,SANDY(CL)
TH-16 4 17.4 102 3.70 CLAY,SANDY(CL)
TH-16 9 18.0 99 -0.7 CLAY,SANDY(CL)
TH-17 9 25.0 96 -
1796 CLAY,SANDY(CL)
TH-17 14 13.9 112 0.0 CLAYSTONE
TH-18 9 14.0 119 0.8 CLAYSTONE
TH-19 9 182 108 -0.1 CLAY,SANDY(CL)
TH-20 4 13.9 105 1.20 CLAY,SANDY(CL)
TH-21 4 22.8 99 -0.1 CLAY,SANDY(CL)
TH-21 9 23.4 102 30 12 CLAY,SANDY(CL)
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-Swell due to wetting at an applied pressure of 1,000 psf. Negative values Indicate consolidation. PAGE 1 OF l o
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JUL-01-2002 M0N 0Z:37 PM P. 044/056
•
APPENDIX A
GUIDE SITE GRADING SPECIFICATIONS
WHITHAM PROPERTY(NORTH HALF)
SOUTHEAST OF COUNTY ROAD 26 AND COUNTY ROAD NO.3%
WELD COUNTY, COLORADO
a
a
MULTI HOME CORPORATION
" YYMff PJA PROPERTY(NORM HALF)
Cliff FC41O7
JUL-01-2002 M0N 02:37 PM P. 045/056'
GUIDE SITE GRADING SPECIFICATIONS —
WHITHAM PROPERTY(NORTH HALF)
WELD COUNTY, COLORADO
1. PFRCRIPTION This item shall consist of the excavation, transportation, placement and .,
compaction of materials from locations indicated on the plans, or staked by the
Engineer,as necessary to achieve preliminary street and overlot elevations. These
specifications shall also apply to compaction of materials that may be placed outside
of the project.
2. GENFRAI
The Soils Engineer shall be the Owner's representative. The Soils Engineer
shall approve fill materials, method of placement, moisture content and percent
compaction, and shall give written approval of the completed fill.
3. CLEARING JOB SITE
•
The Contractor shall remove all trees,brush and rubbish before excavation or —
fill placement Is begun. The Contractor shall dispose of the cleared material to provide the Owner with a clean, neat appearing job site. Cleared material shall not _
be placed In areas to receive fill where the material will support structures of any —
kind.
4. SCARIFYINSS AREA TO BE FILLED
All topsoil and vegetable matter shall be removed from the ground surface
upon which fill Is to be placed. The resulting surface shall then be plowed or —
scarified until the surface is free from ruts, hummocks or other uneven features
which would prevent uniform compaction by the equipment to be used.
5. COMPACTING AREA TO BE FILLED .,
After the foundation for the fill has been cleared and scarified, it shall be disked
or bladed until it Is free from large clods, brought to the proper moisture content, (0
to 3 percent above optimum) and compacted to obtain a film platform for fill
placement.
6. FILL MATERIAI R
Fill soils shall be free from vegetable matter or other deleterious substances,
and shall not contain rocks having a diameter greater than six (6) inches. Fill
materials shall be obtained from cut areas shown on the plans or staked in the field by the Engineer or imported to the parcel. Concrete, asphalt, and other deleterious
materials or debris shall not be used as fill. Import materials shall be similar to on
site soils.
wLr@ HOME CORPORATOR —
WHITMAN PROPERTY(Name*041) A-1
JUL-01-2002 M0N 02:37 PM P. 046/056
CQJ
7. NIOISTURF CONTENT
,- Fill materials shall be moisture treated to within 0 to 3 percent above optimum
moisture content as determined by the Standard Proctor Compaction Test (ASTM
D 698). Sufficient laboratory compaction tests shall be made to determine the
optimum moisture content for the various soils encountered in borrow areas or
imported to the parcel.
The Contractor may be required to add moisture to the excavation materials in
the borrow area if, in the opinion of the Soils Engineer, it Is not possible to obtain
uniform moisture content by adding water on the fill surface. The contractor will be
required to rake or disk the fill soils to provide uniform moisture content through the
^ soils.
The application of water to fill materials shall be made with any type of
watering equipment approved by the Soils Engineer, which will give the desired
results. Should too much water be added to any part of the fill, such that the
a material is too wet to permit the desired compaction from being obtained, rolling and
all work on that section of the fill shall be delayed until the material has been allowed
to dry to the required moisture content. The Contractor will be permitted to rework
wet material In an approved manner to hasten Its drying. •
8. COMPACTION OF Ell L AREAS
Selected fill material shall be placed and mixed In evenly spread layers. After
each fill layer has been placed, It shall be uniformly compacted to not less than 95
percent of standard Proctor maximum dry density (ASTM D 698). Fill materials shall
be placed such that the thickness of loose material does not exceed 8 Inches and the
compacted lift thickness does not exceed 6 inches.
Compaction, as specified above, shall be obtained by the use of sheepsfoot
rollers,multiple-wheel pneumatic-tired rollers, or other equipment approved by the
Soils Engineer for soils classifying as CL, CH, or SC. Granular fill shall be
compacted using vibratory equipment or other equipment approved by the Soils
Engineer. Compaction shall be accomplished while the fill material is at the
specified moisture content. Compaction of each layer shall be continuous over the
entire area.
9. COMPACTION AF SI OPgJURFACFQ
Fill material shall be compacted by means of sheepsfoot rollers or other
suitable equipment. Compaction operations shall be continued until slope surfaces
are stable, but not too dense for planting, and there Is no appreciable amount of
loose soil on the slope surfaces. Compaction of slope surfaces may be done
progressively In Increments of three to five feet(3'to 5') in height or after the fill is
brought to its total height Permanent fill slopes shall not exceed 3:1
(horizontal:vertical).
As. PULTE HOME CORPORATION
WHITMAN PROPERTY(NORM HALF)
CnJT x04107 A-2
JUL-01-2002 M0N 02:38 PM P. G47/056
10. D NSIE��S Field density tests shall be made by the Soils Engineer at locations and depths
of his choosing. Where sheepsfoot rollers are used,the soil may be disturbed to a
depth of several inches. Density tests shall be taken in compacted material below
the disturbed surface. When density tests indicate the density or moisture content
of any layer of fill or portion thereof is below that required,the particular layer or
portion shall be reworked until the required density or moisture content has been
achieved.
Observation by the Soils Engineer shall be full time during the placement of fill
and compaction operations so that they can declare the fill was placed in general
conformance with specifications. All inspections necessary to test the placement
of fill and observe compaction operations will be at the expense of the Owner.
11. COMPLETED PRELIMINARY nIRAriP
All areas, both cut and fill, shall be finished to a level surface and shall meet
the following limits of construction:
•
A. Overlot cut or fill areas shall be within plus or minus 0.2 of one
foot.
B. Street grading shall be within plus or minus 0.1 of one foot The civil engineer, or duly authorized representative,shall check all cut and fill
areas to confirm that the work is In accordance with the above limits.
12, SUPERVISION AND CONSTRUCTION STAKING
All construction staking will be provided by the Civil Engineer or his duly
authorized representative. Initial and final grading staking shall be at the expense of the owner. The replacement of grade stakes through construction shall be at the
expense of the contractor.
13. ,4FARONAL I IMIT.
No fill material shall be placed, spread or roiled while it Is frozen, thawing,or during unfavorable weather conditions. When work is interrupted by heavy
precipitation,fill operations shall not be resumed until the Soils Engineer indicates
the moisture content and density of previously placed materials are as specified.
14. NOTICP REGARDING START OF GRADING —
The contractor shall submit notification to the Soils Engineer and Owner advising them of the start of grading operations at least three(3) days in advance of
the starting date. Notification shall also be submitted at least 3 days In advance of —
PULTE HOME CORPORATION
INHUMAN PROPERTY(NORTH HALFI
CTL?PC-1107 A'3
JUL-01-2002 M0N 02:38 PM P. 048/056
•
� I
any resumption dates when grading operations have been stopped for any reason
other than adverse weather conditions.
15. REPORTING OF FIELD DFNSITY TESTS
Density tests made by the Soils Engineer,as specified under"Density Tests"
above,shall be submitted progressively to the Owner. Dry density,moisture content
and percentage compaction shall be reported for each test taken.
16. DECLARATION REGARDING COMPLETED FLU
The Soils Engineer shall provide a written declaration stating that the parcel
was filled with acceptable materials, or was placed in general accordance with the
specifications.
17. DECLARATION REGAROWG GOh'P FT D .RAD E��ATIONS
A registered Civil Engineer or licensed Land Surveyor shall provide a
declaration stating that the site grading has been completed and resulting elevations
are In general conformance with the accepted detailed development plan.
•
PULTE HOME CORPORABON
W
H
IT
AM PROPERTY(NORTH NW) A-4
JUL-01-2002 M0N 02:38 PM P. 049/056 --
0 200
180 180 -
180 180
-
140 140 ^
LL TH-10
EL. 129 TH-11 TH-12 - t
11 EL. 126 a. 125
s 4 :-750/12 1�1p 50/12 -4 -
120 11/12 50/11 120 �-
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50/12 50/2
- -
50/3 _
-50/2 50/11 50/4 -
100 50/5 50/2 100
O 80
-
O 80
40 -
SUMMARY LOGS OF EXPLORATORY BORINGS
JOB NO. FC-110T FIG. 6
JUL-01-2002 MON 02:38 PM P. 050/056
200 280
180 180
^
180 TH-18 TH-17
EL. 155 EL. 154 180
TH-13 TH-14
a. 143 a. 148 20/12 -15/12
14/12 -7/12
140 29/12 s !: ::
-9/1 TH-15
1_ EL. 130 59/12 : �-50/8 _u
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50/9 `�/4is/12
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-50/e 5 -5� 120
-50/3 50250/11
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r 100 50/2 100
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0 80
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0 40
a
SUMMARY LOGS OF EXPLORATORY BORINGS
JOB NO. FC-1187 FIG. 7
J0L-01-2002 YON 02:38 PY P. 051/056 —.
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^
GEOLOGIC AND PRELIMINARY
GEOTECHNICAL INVESTIGATION
^ LIFEBRIDGE PLANNED URBAN DEVELOPMENT
SOUTHWEST OF COUNTY ROAD 26 AND
COUNTY ROAD NO. 3%
WELD COUNTY, COLORADO
A
a.
I.
Prepared For:
LIFEBRIDGE CHRISTIAN CHURCH
10345 Ute Highway
Longmont, Colorado 80504
Attention: Mr. Bruce Grinnell
a.
Job No. FC-2442
September 6, 2002
CTL/THOMPSON, INC.
CONSULTING ENGINEERS
375 E. HORSETOOTH RD. ■ THE SHORES OFFICE PARK ■ BLDG. 3, SUITE 100 ■ FT. COLLINS.CO 80525
(970)206-9455
^
TABLE OF CONTENTS
SCOPE 1
SUMMARY OF CONCLUSIONS 1
SITE 2
PROPOSED DEVELOPMENT 3
PREVIOUS INVESTIGATION 3
SITE GEOLOGY AND GEOLOGIC HAZARDS 3
.. SUBSURFACE CONDITIONS 6
Slightly Sandy to Sandy Clay 7
Silty Sand 7
_ Sandstone Bedrock 7
Claystone Bedrock 8
Groundwater 8
SITE DEVELOPMENT 9
Groundwater 9
Grading 11
.- Slope Stability and Erosion 12
Utility Construction 12
Pavements 14
RESIDENTIAL CONSTRUCTION CONSIDERATIONS 14
Foundations 14
Slab-on-Grade and Basement Floor Construction 15
Basements 15
SURFACE DRAINAGE 16
CONCRETE 17
LIMITATIONS AND ADDITIONAL INVESTIGATION 18
FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS
FIG. 2 - SUMMARY LOGS OF EXPLORATORY BORINGS
FIG. 3 - ESTIMATED BEDROCK DEPTH
FIG. 4 - ESTIMATED BEDROCK ELEVATION
FIG. 5 - ESTIMATED GROUNDWATER DEPTH
FIG. 6 - ESTIMATED GROUNDWATER ELEVATION
FIGS. 7 AND 8 - SWELL CONSOLIDATION TEST RESULTS
TABLE I - SUMMARY OF LABORATORY TEST RESULTS
APPENDIX A- GUIDE SITE GRADING SPECIFICATIONS
LIFEBRIDGE CHRISTIAN CHURCH
^ LIFEBRIDGE PUD
CTLR FC-2442
SCOPE
This report presents the results of our geologic and preliminary geotechnical
investigation for the Lifebridge Christian Church Property, located southwest of the
intersection of County Road 26 and County Road No. 31/2 in Weld County, Colorado
(Figure 1). The Lifebridge Christian Church plans to develop the parcel as a
subdivision for single-family residences.
We investigated the geology and subsurface conditions at the parcel to
evaluate the affect of the geology, the soils, the bedrock and the groundwater on
the proposed development of the parcel and the design and construction of
residences in the proposed subdivision. This report presents the results of our
field and laboratory studies and our conclusions, opinions and recommendations
regarding the proposed development and the design and construction of the
residences with respect to geotechnical engineering. Our conclusions are
summarized below.
SUMMARY OF CONCLUSIONS
1. The parcel is underlain by slightly sandy to sandy clay and claystone
and sandstone bedrock. Samples of the overburden clay exhibited low
swell potential when tested in the laboratory. Isolated layers of clay
with moderate or high swell potential should be anticipated in some
areas of the parcel. Sandstone bedrock was encountered in three of
our seven borings at depths ranging from approximately 8 to 22 feet.
Claystone bedrock was encountered in one boring at a depth of
approximately 25 feet.
^
2. Groundwater was encountered within our borings at depths ranging
from approximately 6 to 21 feet below the existing ground surface.
Groundwater should be anticipated above typical basement depths
in the southern portions of the site based on the current surface
topography. In addition, groundwater elevations are likely to rise
seasonally or in response to higher precipitation amounts in the
project area. Basement floors should be placed at least 3 feet above
the expected groundwater surface.
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
1 CTL?FC-2442
a
..
^ 3. Site grading or installation of a parcel wide subdrain system, or a
combination of these methods could be used to mitigate areas of
shallow water. The proposed residences will also need foundation
drains.
4. The clays and sandstone bedrock at the site can be characterized as
nil to low expansive. Claystone bedrock encountered at
comparatively deep depths may have a moderate to high swell
potential. We believe footings will be the predominate foundation
a type for the residences proposed for the subdivision if the final lot
grades are at or above the existing natural grades. The finally
selected site grading plan will determine if the foundation strata for
a given residence foundation will be footings bearing on clays or
a footings bearing on the bedrock. The tendency for swell in the
bedrock will cause the footing design criteria to include criteria for a
minimum deadload for both bearing strata.
5. The natural clays and bedrock can be the subgrade for slab-on-grade
basement floors. Considerations for slab-on-grade basement floors
are discussed in "Slabs-on-Grade and Basement Floor Construction"
subsection.
6. The natural clays are a weaker subgrade for pavements. Residential
streets will probably require full-depth asphaltic concrete pavement
thicknesses of the order of 6 inches(or 4 inches of asphaltic concrete
over 8 inches of compacted base course) and thicker pavement
s sections for collector and arterial streets.
7. Control of the surface water will influence the performance of
foundations, slab-on-grade floors and pavements. Surface ground
^ contours and drainage structures must cause rapid runoff of surface
water away from structures and removal of the water from the area.
SITE
^
The site (parcel) is located southwest of the intersection of County Road 26
and County Road No. 3' in Weld County, Colorado (Figure 1). The irregularly
shaped site is bound to the south by the Great Western Railway and to the east by
Weld County Road 3'/2. A single residence is present at the northeast corner of the
parcel. From the northeast corner of the parcel, the ground surface slopes down
gradually to the south and west. No significant erosional features were observed.
Surface improvements were not visible at the site.
UFEBRIDGE CHRISTIAN CHURCH
^ LIFEBRIDGE PUD 2
CM FC-2442
a
PROPOSED DEVELOPMENT
This parcel will be a single-family residential subdivision that will adjoin
a
additional development proposed on the adjacent land to the south and east.
Grading plans were not available at the writing of this report, however a plan
a showing the existing topography was provided by Rocky Mountain Consultants,
Inc.
We have assumed for this analysis the residences that will be built in the
proposed subdivision will be mostly two-story wood frame structures with full
basements. Typically these kinds of residences will have some stone and/or
masonry veneer on the exteriors.
PREVIOUS INVESTIGATION
The parcel of land currently under consideration adjoins two parcels
a previously considered by Pulte Homes. CTL/Thompson, Inc. conducted geologic
and preliminary geotechnical investigations for those sites. Details regarding our
investigations, observations, conclusions and recommendations are presented in
our reports dated August 11, 1998 (FC-1044) and November 17, 1998 (FC-1107).
Information from our previous exploratory borings, laboratory testing and
engineering analyses were used in preparation of this report, as appropriate.
a
SITE GEOLOGY AND GEOLOGIC HAZARDS
a
a The parcel is located within the Colorado Piedmont section of the Great
Plains physiographic province. The Piedmont is a broad erosional trench which
separates the Southern Rocky Mountain from the High Plains. Mapping by R.B.
Colton (USGS Map I-855-G, Geologic Map of the Boulder-Fort Collins-Greeley Area,
a Colorado 1978) indicates the surface of the parcel is Eolian (Oe) deposits
consisting of olive-brown-gray windblown clay, silt and sand. The underlying
a
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD 3
CTUT FC-2442
11-2
bedrock consists of the Upper Transition Zone of the Pierre Shale (Kptz), which is
described as interbedded sandstone and shale with hard sandstone ledges and
water with high sulfate content. The thickness of the Pierre Shale is about 2,800
feet. Locally the Pierre Shale dips towards the south. However on a larger scale,
we believe the general regional dip is towards the east. Our field exploration
generally confirmed the conditions described by published maps and our previous
reports.
This section discusses geologic hazards that we believe could affect land
planning and zoning. Specific requirements of Colorado House Bill 1041 "Areas
and Activities of State Interest" and Colorado Senate Bill 35 "County Planning and
Building Codes" are addressed.
The claystone phases of the bedrock are expansive. This can result in
damage to improvements or structures depending upon the characteristics of the
_ claystone and the increase in moisture content that occurs. Engineered design of
pavements, foundations, slabs-on-grade and surface drainage can mitigate the
_ effects of expansive bedrock. The soils and bedrock under this parcel are not
expected to be unusually corrosive to metal but may have sulfate concentrations
that can affect concrete. Natural slopes are gentle and appear to be stable.
Significant faulting and structural discontinuities are not expected in the
bedrock at this site. The soil and bedrock units are not expected to respond
unusually to seismic activity. The area is considered by the most recent editions
of the Uniform Building Code (UBC) as Zone 1, its least active zone designation.
^ Only minor damage to relatively new, properly designed and built residences would
be expected during an earthquake.
_ Regarding the potential for radioactive substances on the parcel, it is normal
in the Front Range of Colorado and nearby eastern plains area to find significant
accumulations of radon gas in poorly ventilated spaces (i.e., full-depth residential
LIFEBRIDGE CHRISTIAN CHURCH
.-. LIFEBRIDGE PUD
4
CTL/T FC-2442
basements) in contact with soil or bedrock. Radon 222 gas has been shown to be
a health hazard and is just one of several radioactive products with a short half-life
in the chain of the natural decay of uranium into stable lead. There is no geologic
property of the soils and bedrock at this parcel that would make radon gas any
more likely than other areas of the Front Range of Colorado. The amount of radon
gas that can accumulate in an area is a function of many factors, including the
radionuclide activity of the soil and bedrock, construction methods and materials,
soil gas pathways, and accumulation areas. Typical mitigation methods consist of
sealing soil gas entry areas and ventilation of below-grade spaces. Radon rarely
accumulates to significant levels in above-grade living spaces.
Anak
The parcel does not appear to be flood prone. There are no highly-
developed, incised drainages on the parcel. The very gentle topography of the
parcel indicates little, if any, water would typically be expected to flow onto the
parcel from outside the boundaries and there is no geologic indication of periodic
flooding as evidenced by the absence of recent quaternary alluvium. Union
Reservoir is adjacent to the property to the northwest and could present a hazard
.. in the event of catastrophic storms. The erosion potential on the parcel is
considered low, due to gentle slopes. The erosion potential can be expected to
increase during construction, but should return to pre-construction rates or less
if proper grading practices, surface drainage design and revegetation efforts are
implemented.
We do not believe the parcel is located above underground mines or is
located in a subsidence hazard zone. The bedrock below the parcel is the Pierre
Shale formation which does not contain significant coal beds. There is no evidence
of past mining activities on the parcel.
No economically important mineral deposits are expected on this parcel or
are known to occur nearby. We do not expect ground subsidence related to natural
or mining processes.
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTIJT FC-2442 5
- r
_ The borings we drilled on the parcel showed groundwater was shallow under
some areas of the parcel. We believe these groundwater elevations may be deeper
than normal based on the recent drought conditions in Colorado. We anticipate
groundwater will be encountered above typical basement depth(measured from the
existing ground surface) in some areas of the site. The development strategy for
a parcel with shallow groundwater usually includes consideration of a parcel-wide
subdrain, foundation drains around basements, raising the natural ground
elevations with engineered fill to provide the needed distance above groundwater
for basements and other mitigating measures.
Very hard sandstone bedrock was encountered on the southern and western
part of the property. Special excavation equipment and techniques may be needed
_ if deep excavations are planned.
No geologic hazards which would preclude the proposed development were
noted on the subject tract. The shallow groundwater will require mitigation. We
believe the geologic hazards can be mitigated with proper engineering design and
construction practices, as discussed in this report.
SUBSURFACE CONDITIONS
Seven borings were drilled with a 4-inch diameter, continuous flight auger
and a truck-mounted drill rig at the approximate locations shown on Figure 1. The
drilling operations were observed by our field representative who logged the soils
and obtained samples for laboratory testing. Graphic logs of the soils found in our
borings including results of field penetration resistance tests are shown in Figure
2. Samples obtained during drilling were returned to our laboratory where they
were visually classified and selected for testing. The results of our laboratory tests
are on Figures 7 through 8 and summarized in Table I.
LIFEBRIDGE CHRISTIAN CHURCH
^ UFEBRIDGE PUD
CTUT FC-2442 6
Slightly sandy to sandy clay overlying claystone and sandstone bedrock
— were penetrated by our borings. The following paragraphs provide general
descriptions of the soil and bedrock types encountered.
Slightly Sandy to Sandy Clay
Natural slightly sandy to sandy clay was encountered in our seven borings
from the ground surface to depths ranging from approximately 6 to 22 feet deep.
Swell-consolidation tests performed by wetting four samples after application of
a 1,000 psf pressure indicate the samples tested had a negligible to low swell
potential. Samples of the clay tested in the laboratory contained between 92 and
_ 96 percent clay-and silt-sized particles(passing the No. 200 sieve), had liquid limits
ranging from 45 to 52 percent, and plasticity indices ranging from 29 to 34 percent.
The highly plastic properties of some of these samples indicates layers of clay with
— moderate to high swell potential are likely in localized areas on the site. The
thickness and extent of such soils should be determined as part of lot specific,
design level geotechnical investigations performed after site grading.
.. Silty Sand
_ A thin layer of silty sand was encountered underlying the overburden clay
in one of the borings. The sand is non-plastic. Similar thin layers of sand should
be anticipated intermixed with the sandy clays underlying the site. The silty sand
is not anticipated to significantly impact project development.
Sandstone Bedrock
Sandstone bedrock was encountered underlying the overburden soils in
three of our seven borings at depths of approximately 8, 9, and 22 feet. Samples
of the sandstone tested were found to be non-plastic. The sandstone is non-
- LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD 7
CTL/T FC-2442
swelling and will not significantly impact foundation design. The hard to very hard
sandstone may require extra effort and/or special equipment or blasting to
complete deep excavations at the site particularly along the southern property
boundary and near the southwest corner of the property. Contours illustrating the
approximate depth to bedrock are shown on Figure 3, and the approximate
elevation of the bedrock surface is shown on Fig. 4.
Claystone Bedrock
Claystone bedrock was encountered in one of our borings at a depth of
approximately 25 feet. The claystone is anticipated to have variable swell potential.
At the depth encountered, the claystone is not anticipated to significantly impact
design or construction of the proposed residences. However, lenses of claystone
may be encountered within the sandstone bedrock at shallower depths in other
areas of the site. Contours illustrating the approximate depth to bedrock are shown
on Figure 3, and the elevation of the bedrock surface is shown on Fig. 4.
Groundwater
Groundwater was encountered in 4 of our 7 borings at depths ranging from
approximately 7 to 21 feet at the time of drilling and in all of our borings at depths
of 7 to 24 feet when checked several weeks after drilling. Our investigation
suggests water is generally flowing from north to south beneath the property.
Based on current topography, groundwater will impact residential construction on
about 30 to 40 percent of the site. Figure 5 shows our estimate of the depth to
groundwater and Figure 6 shows our estimate of the elevation of the groundwater
surface. We anticipate these groundwater levels may rise significantly should
drought conditions in Colorado ease.
UFEBRIDGE CHRISTIAN CHURCH
UFEBRIDGE PUD
CTL/T FC-2442 8
^
SITE DEVELOPMENT
We have identified no geologic or geotechnical conditions that should
preclude development of this parcel. Geotechnical constraints we identified for the
property include the following:
• The groundwater is shallow in some areas of the site, above typical
basement floor depth (measured from existing, natural grade);
• Clay with low swell potential was encountered at the site;
• Relatively shallow sandstone bedrock was encountered underlying the clay
in some areas of the site.
Discussions of these constraints and of site grading, pavement construction, utility
installation and construction of permanent slopes for long term stability and
protection against erosion are included below.
Groundwater
Present plans are to build residences with basements. The groundwater
depths we measured in some of our borings are at or above typical basement
depths if the existing ground surface in the proposed subdivision is not altered
much during grading. Therefore, changes to the existing condition will be
necessary to make basements feasible. In our opinion, two alternatives seem
a technically feasible:
a. Install a parcel wide subdrain system to lower the groundwater under
the parcel so it will be at least 3 feet below the basement floor
elevations at the residence locations and provide foundation drains
around all residences; or
b. Raise the ground surface elevations enough that basement floor
elevations at the residence locations will be at least 3 feet above the
groundwater and provide foundation drains around all residences; or
c. A combination of (a) and (b) above.
^ LIFEBRIDGE CHRISTIAN CHURCH
^ UFEBRIDGE PUD
CUT FC-2442 9
a
Subdrain. Topographic constraints may complicate installation of a
subdrain. Topography may not allow for gravity flow of the subdrain necessitating
the use of pump stations. Additional investigation may be needed if a parcel wide
subdrain is a selected alternative. Such an investigation would be aimed at better
identifying the possible sources of groundwater, and measuring the permeability
of the soil and bedrock to recommend a drain configuration and drain sizing.
The parcel wide subdrain we envision will be an underdrain below the
sanitary sewer mains that will serve as an outlet for individual residence foundation
drains(see"Basements"subsection)and will help to maintain the water level below
the planned basement floor elevations. The underdrains should be provided with
cleanouts so they can be regularly maintained. If the sewer district will not
maintain underdrains, the home owners' association should be empowered to
provide maintenance and be provided copies of "as-built" plans.
The underdrains would be an appropriately graded filter material
surrounding a pipe. The pipe should be sized for the flow determined after the
recommended ground water investigation is completed. The drain pipe should
consist of smooth, perforated or slotted rigid PVC pipe laid at a grade of at least 0.5
percent. The filter material should have a cross-section of at least 2 square feet.
A positive cutoff collar(concrete)should be constructed around the sewer pipe and
underdrain pipe immediately downstream of the point the underdrain pipe leaves
the sewer trench. Solid pipe should be used down gradient of this collar to the
daylight or collection point. The underdrain should be designed to discharge to a
gravity outfall or to a series of lift stations. If lift stations or any system that could
temporarily fail are used, we recommend a check valve be placed on the underdrain
service to each house, and cutoff collars be constructed to prevent backflow
through the filter gravels. We further recommend backup pumps for each lift
station pump and backup, on-site, electricity generators that will automatically turn
on when the subdivision power fails.
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTL/T FC-2442 10
Grading
Overlot grading should be engineered fill that is compacted under controlled
conditions. Areas to receive grading fill need to be cleared, grubbed and stripped
of all vegetation, organic topsoil and other deleterious matter. The cleared,
grubbed and stripped materials should be discarded or placed in areas that will
never be under structures, utilities, sidewalk, curbs and gutters, driveways or
pavements.
After stripping, the resulting subgrade should be scarified, moisture
conditioned to 0 and 3 percent above optimum moisture content and compacted to
obtain a firm platform for fill placement. Our borings indicate some very moist,
weak soils exist on the parcel. Where such soils are encountered, they can be
stabilized prior to placing fill. Stabilization of soft subgrade soils is often
accomplished by removal and replacement, scarifying and drying, utilizing
geosynthetics or "crowding" crushed rock into the subgrade until a firm surface is
achieved.
The properties of the fill will affect the performance of foundations, slab-on-
"" grade floors and pavements. The soils from the parcel are suitable for use as
grading fill. Claystone should be broken down before placing it as fill. If imported
materials are necessary,they should consist of sandy clays that have low plasticity
and low swell potential similar to the on-site clays. A sample of soils proposed for
importing as fill should be submitted to our office for classification and approval
prior to hauling them to the site. Fill should be placed in thin loose lifts, moisture
conditioned to between 0 and 3 percent above optimum moisture content and
compacted to at least 95 percent of standard Proctor maximum dry density(ASTM
D 698). Guide specifications for overlot grading are in Appendix A. Placement and
compaction of the grading fill should be observed and tested by a representative
of our firm.
... LIFEBRIDGE CHRISTIAN CHURCH
UFEBRIDGE PUD
CTIJT FC-2442 11
For the most part, the soils and bedrock at this parcel have negligible to low
swell potential. Deeper claystone bedrock was moderately expansive under the
_ adjacent parcel. If the existing grades are lowered by cutting, this claystone will
begin to influence structure foundation type. If possible, site grading should be
planned to provide at least 4 feet of nil to low expansive clays or fill above the
claystone bedrock so that deep foundations can be avoided.
_ Residences built in areas of expansive soils and bedrock are susceptible to
damage from heave caused by wetting and swelling of expansive soils and
— bedrock. Special precautions are needed in the construction of foundations and
other elements to mitigate the effects of swelling soils/bedrock. In our experience
these techniques can and have reduced the damages to residences when the
expansive soils/bedrock like those on this parcel get wet.
Slope Stability and Erosion
We observed no evidence of slope instability or significant erosion on the
parcel. For the type of soils present at this parcel, we believe permanent slopes
should be 3:1 (horizontal:vertical) or flatter. Surface drainage should not be
allowed to sheet flow across slopes or pond at the crest of slopes. Slopes should
_ be revegetated as soon as possible to reduce the potential for erosion problems.
Localized slopes enclosing retention/detention ponds should be designed by a
qualified Civil Engineer with erosion control and slope stability in mind.
Utility Construction
The bedrock penetrated by our borings was hard to very hard and included
cemented, very hard sandstone lenses. We believe most of the materials can be
excavated with either heavy duty trenchers or large backhoes, however, ripping or
— other means may be required to loosen the cemented, bedrock lenses.
UFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTL?FC-2442 12
Ecji
Medium stiff clays and hard interbedded sandstone, claystone and siltstone
are predominant. We believe the clay soils on this parcel can be classified as Type
C, and bedrock as Type A or Type B based on the Occupational Safety and Health
Administration (OSHA) standards governing excavations. Type C soils require
maximum slope inclination of 1.5:1 (horizontal:vertical), Type B soils require
maximum slope inclination of 1:1 (horizontal:vertical) and Type A soils require a
maximum slope of 3/4:1 (horizontal:vertical). The contractor's competent person
on site should identify the soils encountered in excavations and refer to OSHA
standards to determine appropriate slopes. Excavations deeper than 20 feet should
be designed by a professional engineer.
Groundwater will be encountered during utility excavation. The clays and
bedrock at this parcel are expected to be low to moderately permeable.
Groundwater seepage will be slow to moderate. We anticipate trench dewatering
— may be accomplished by sloping the trench bottom to collection areas where water
can be removed by pumping, however large, heavy duty pumps should be
anticipated. Some zones of sandier clays and more permeable sandstone bedrock
may exist requiring the occasional use of well points or other means to lower
groundwater and allow for excavation.
Water and sewer lines are usually constructed beneath paved roads.
Compaction of trench backfill will have significant effect on the life and
serviceability of pavements. We recommend trench backfill be placed in thin, loose
lifts, moisture conditioned between 0 and 3 percent above optimum moisture
content and compacted to at least 95 percent of standard Proctor maximum dry
density(ASTM D 698). The placement and compaction of fill and backfill should be
observed and tested by a representative of our firm during construction.
�.. LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
a CTL/f FC-2442 13
EFEI
Pavements
The surficial soils found on-site have fair to poor pavement support qualities.
For preliminary planning purposes, we suggest assuming 6 inches of full depth
asphaltic concrete paving will be needed for local residential streets. A section
using asphaltic concrete and compacted base course would be 4 inches of
asphaltic concrete over 8 inches of base course. Thicker pavements will be needed
for collector and arterial streets. A subgrade investigation and pavement design
should be performed after overlot grading is complete.
a
The softer clays we found may rut and"pump"during subgrade preparation.
Should this occur they can be stabilized as described above so that they will
support construction equipment.
RESIDENTIAL CONSTRUCTION CONSIDERATIONS
Two-story residences with full basements are planned for the proposed
a subdivision. Ground conditions and characteristics across the parcel include very
moist, medium stiff sandy clays near the surface underlain by claystone, sandstone
or interbedded claystone, siltstone and sandstone bedrock. The strata at
a
^ foundation level will depend upon finally selected finished grades. The following
discussions are preliminary and are not intended for design or construction. After
a grading is completed, a detailed soils and foundation investigation should be
performed on a lot specific basis.
a
Foundations
^
The foundations that can be used to found the proposed residences will
a
depend upon how the parcel is graded. In our opinion, if the parcel finished grades
are at or above the existing natural grades at the residence locations, the
residences can be founded with footings bearing on the soils/bedrock at footing
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTLR FC-2442 14
elevation. Some of the residences will likely be founded with footings bearing on
the natural clays and/or compacted overlot fill and others will be founded with
footings bearing on sandstone bedrock. We expect the maximum design bearing
capacity for footings will prove to be of the order of 1,500 to 3,000 pounds per
square foot (psf) depending on the bearing stratum. In areas where moderately to
highly swelling clays or claystones are encountered at or near foundation
elevations, drilled piers may be recommended. Piers will likely have maximum end
bearing pressure on the order of 35,000 psf and the side shear value in the bedrock
10 percent of the maximum end bearing capacity. Typical lengths will likely be in
the 20 to 25 foot range. There is the possibility some piers will need to be cased to
dewater and clean the pier holes due to the ground water found under the parcel.
Slab-on-Grade and Basement Floor Construction
Slabs-on-grade are typically used for basement floors on lots with soil
conditions similar to this parcel. Our firm generally recommends structurally
supported basement floors for high (4 to less than 6 percent) and very high (6
percent or greater) swell potentials. Preliminary data indicate structural basement
floors will not be required on any of the lots on this parcel. Site grading cuts in
areas where bedrock is shallowest should be avoided to keep basement floors
above the bedrock or as far up in the more moist, lower swelling portions of the
bedrock as possible.
Basements
Relatively shallow groundwater was encountered in our borings in some
areas of the site and will affect basement construction. Control of groundwater
levels below basements will be required. A parcel-wide subdrain is discussed
above. Foundation drains will be needed around basements regardless of the site
grading plan. We suggest foundation drains be connected to the sewer underdrain
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CM FC-2442 15
system with a piped connection. Sump pits and provisions for pumps should be
installed as a backup if underdrains do not perform as intended.
Typically,foundation drains are comparatively shallow relative to the bottom
of a slab-on-grade floor or the floor of a crawl (air) space under a structural floor.
Where the groundwater is likely to be within 3 or 4 feet of a slab-on-grade floor we
recommend an underslab gravel layer and deeper foundation drains. Further, we
recommend basement floors be at least 3 feet above the anticipated groundwater
surface. If a parcel-wide subdrain is installed the 3 feet should be measured from
the groundwater level that will result from the subdrain design.
Basement excavations that penetrate the ground to near the groundwater
surface may require dewatering and the soils in the excavation floor may be soft.
Should soft soils be encountered, the excavation floor may need to be stabilized so
it will support traffic.
Basement and crawl space walls will be subjected to lateral pressure from
the wall backfill. Such walls should be designed to resist the higher"at rest" lateral
earth pressure because they are not free to rotate and develop the internal strength
of the backfill. We expect the backfill will be the clays from required excavations
^ for the residences and suggest assuming for preliminary designs an equivalent
fluid density of 50 pcf for backfill in design calculations.
SURFACE DRAINAGE
The performance of improvements in this development will be influenced by
surface drainage. When developing an overall drainage scheme, consideration
should be given to drainage around each residence. Drainage should be planned
so that surface runoff is directed away from foundations and is not allowed to pond
.. adjacent to or between structures or over pavements. We recommend slopes of at
least 12 inches where possible in the first 10 feet for the areas surrounding all
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTL/f FC-2442 16
r-.
residences or buildings. In areas between houses which are less than 20 feet apart,
the slope should be at least 10 percent toward the swale used to convey water out
of these areas. Slopes marginally less steep than those recommended may be
necessary at the back of the houses on lots which drain to the front. Roof
downspouts and other water collection systems should discharge well beyond the
limits of all backfill around structures.
Proper control of surface runoff is also important to control the erosion of
surface soils. Sheet flow should not be directed over unprotected slopes. Water
should not be allowed to pond at the crest of slopes. Permanent slopes should be
revegetated to reduce erosion.
nia
Attention should be paid to compact the soils behind curb and gutter
adjacent to streets and parking areas and in utility trenches during development.
If surface drainage between preliminary development and construction phases is
neglected, performance of the roadways, flatwork and foundations will be poor.
When considering landscaping of common areas, we recommend the use of
xeriscaping which requires little initial or long-term watering.
CONCRETE
a
We measured soluble sulfate concentrations for representative samples of
the subsoils from our borings. The water soluble sulfate concentration was 0.04
percent. Sulfate concentrations ranging from 0.1 to 3.7 percent were measured on
the adjacent parcels. Based on ACI standards,water soluble sulfate concentrations
— in this range represent a severe to very severe sulfate exposure. ACI recommends
—
using a cement meeting the requirements for Type V(sulfate resistant)cement,with
a maximum water-cement ratio of 0.45 and air entrainment of 5 to 7 percent for
concrete exposed to soils with this level of soluble sulfates. We understand Type
V cement may not be readily available locally. As an alternative, we believe cement
which meets ASTM C 150 Type II requirements and contains 20 percent fly ash can
^ LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTLR FC-2442 17
be used to provide similar resistance. The fly ash should meet ASTM C 618 Class F
requirements. The fly ash can be reduced to 15 percent in cold weather months.
LIMITATIONS AND ADDITIONAL INVESTIGATIONS
We based the discussions in this report on our understanding of the
proposed development and residences, conditions disclosed by exploratory
drilling, review of geologic maps, site observation, results of our laboratory tests,
engineering analysis of field and laboratory data and our experience. The criteria
^
presented in this report are intended for aid in purchase decisions and preliminary
planning purposes. Future geotechnical engineering investigations and analysis
are required to formulate design criteria for a parcel-wide subsurface drain system
to lower ground water, geotechnical design criteria for residence foundations and
floors, and street pavement sections.
Our borings were widely spaced. In our opinion, the boring pattern provided
us the needed picture of the underground to provide the above report intended to
aid in planning the development of the parcel that is the subject of this report.
Variations between the borings will occur. We recommend continuing to measure
the depth to ground water in the borings we drilled to better understand the
behavior of the ground water under the parcel and to guide future decisions
regarding installing and then designing a parcel-wide, subsurface drain to lower the
ground water under the parcel.
A representative of our firm should be present during site grading and utility
a
trench backfilling to observe fill placement and perform compaction tests. Detailed
investigations should be performed for design of residence foundations and slab-
.— on-grade floors and street pavement sections after overlot grading has been
completed. We should review the final grading plans prior to construction to look
for potential geotechnical problems.
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CM FC-2442 18
^
We believe this investigation was conducted in a manner consistent with that
level of care and skill ordinarily used by geotechnical engineers practicing in this
area at this time. No other warranty, express or implied, is made. If we can be of
further service in discussing the contents of this report or analyses of the influence
of subsurface conditions on the design of the proposed development, residences
and streets, please call.
CTL/TI-I.OM P�SON,IINC
Juan C. Sorensen, PE
a Project Engineer
Reviewe • O• . O R:i Cj �` I .0\E of PAO£FgSo
^ use . 11;7'
•• '_(N\p\CATE4 y4(CA4
( 10504 elf*,
33848 r's ; N
Thomas A. 2 L � . .. G �;:
Associate Engin&eisa+ , q''ea, TS A. CNA Cez\
JCS:TAC:by
(6 copies sent)
a
LIFEBRIDGE CHRISTIAN CHURCH
^ LIFEBRIDGE PUD
CTL/T FC-2442 19
I irrit i - - - - - -1
Jr
1
/
I •.
, •
APPROXIMA oDSCALE: NI"' ='''s• - - 'TH-6 —� SITE
I / TH-5 •i
•
1 / I• 3 a
1
1 UNION . I
RESERVOIR I """""`"
•
I / I
1P
RO NO SCALE VICINITY��MA)
• T•3
•
/ I
I 1
•
I I
mo' TH_ ,
� Ro�°z6 '- J
Y`� ,
�gC�N�' •� /'NTH 1 TH 4 /•��
•
II 01 LEGEND :
CC TH-1 INDICATES APPROXIMATE
1 / • BORING N OF EXPLORATORY
I •/I•
O� O
1 I le* U r._..1 INDICATES APPROXIMATE BOUNDARY
/'•
S��F�N o L.,__j OF INVESTIGATED SITE
i • �#
it
• 3
� Gikv c.9
T•2 •''/ Pi
II •'/ w
Locations of
t Exploratory
LIFEBRIDGE CHRISTIAN CHURCH
Borings
JOB NO.FC-2442
FIGURE 1
1
1 Eg
TH-1 TH-2 TH-3 TH-4 TH-5 TH-6 TH-7
El. 4966 El. 4955 El. 4986 El. 4969 El. 4993 El. 4990 El. 4972
I
i 4995
4995
I -
_ F $&12
LEGEND:
I -
4985 11/12 4985 - 1 I CLAY,SLIGHTLY SANDY TO SANDY,MEDIUM STIFF TO STIFF,MOIST, BROWN(CL).
I - 11/12
1 - 6/12
1 - 15/12 77SAND,SLIGHTLY CLAYEY,MEDIUM DENSE TO DENSE,MOIST,LIGHT BROWN TO BROWN
( 12/12 --I (SC).
4975 13/12 4975
I - Y. 20/12 SANDSTONE,SLIGHTLY CLAYEY TO CLAYEY,MEDIUM HARD TO HARD,SLIGHTLY MOIST
-_ TO MOIST,BROWN,RUST,GRAY,OCCASIONALLY WEATHERED AT THE SURFACE
1 - (BEDROCK).
I - 41 / / _ CLAYSTONE,SLIGHTLY SANDY TO SANDY,SLIGHTLY MOIST TO MOIST,MEDIUM HARD TO
i ]9/12 -
I HARD,BROWN,RUST,GRAY(BEDROCK).
1 6n
4965 9/12 - 20/12 / I 4965
DRIVE SAMPLE. THE SYMBOL 12/12 INDICATES THAT 12 BLOWS OF A 140-POUND HAMMER
i - 12/12 / I]6/12 - FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D.SAMPLER 12 INCHES.
I - 50/6 / / _
1 - = 5/12 X / Al 15/12 - WATER LEVEL MEASURED AT TIME OF DRILLING.
I 4955 Q 50/2 i / / 4955 -
a- / w- 1 WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING.
5/12 / 0.
1 4/12 17 / -z
,r7 / O
_
P
I — / .]30/12 —ic
j
Lu
w 4945 25/12
1 - 4945 1°
I - 50/1 _•
50/8 III NOTES:
s
50/7 - 1. THE BORINGS WERE DRILLED ON AUGUST 26,2002 USING A 4-INCH DIAMETER
4935 4935 CONTINUOUS FLIGHT AUGER AND A TRUCK MOUNTED DRILL RIG.
-
-
50/6 2. BORING LOCATIONS WERE IDENTIFIED IN THE FIELD BY A REPRESENTATIVE OF
50/4 - CTLITHOMPSON,INC.
1 - .
I - 3. BORING ELEVATIONS WERE ESTIMATED FROM TOPOGRAPHIC SURVEY INFORMATION
4925 4925 PROVIDED BY ROCKY MOUNTAIN CONSULTANTS,INC.
4. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS AND CONCLUSIONS IN THIS REPORT.
4915
4915
_ SUMMARY LOGS OF EXPLORATORY BORINGS _
4905 4905
LIFEBRIDGE CHRISTIAN CHURCH
JOB NO.FC-2442 FIGURE 2
I
ill
Lii
I
I
i
APPROXIMATE SCALE: •
• N�
I' = 300' / • 'TH-6
TH-5 •
•• •
73"............N.."%4975
•
UNION
RESERVOIR •
r
T'3 4970 0 h 40 I j
�0 0 ii
1015 TH-7
-
4:j LEGEND :
V
R ON 26 -' A \4965
UNCV 96+ TH-1 INDICATES APPROXIMATE
(,O - /• • LOCATION OF EXPLORATORY
GVJE� •/' y9 • �l ( BORING
�sS\N •• • TH 1—_�sr SS TH-4 . et
o)
/ • 9AS agSO • N r----1 INDICATES APPROXIMATE
.0- 0 L„_„j LOCATION OF EXPLORATORY
I 4940 •• p BORING
0
I' , X4940- CONTOUR OF APPROXIMATE
I
Z BEDROCK SURFACE ELEVATION
-C--
0
NOTE: THIS ESTIMATE IS BASED ON A
w SUBJECTIVE ANALYSIS OF DRILL
• ��A1' HOLE DATA,AND MAY NOT
i -•- G�Si a REFLECT LOCAL VARIATIONS.
TH-2 ••/ p
• in
' / w
i Approximate Elevation
I LIFEBRIDGE CHRISTIAN CHURCH
of Bedrock Surface
JOB NO.FC-2442 FIGURE 4
)
I
I
lif
: if 20' r - - a - - 1 i ,-
•
I
APPROXIMATE SCALE: / 25'
1" = 300'
•
. - - - TH-6
� % TH-5 •I
* 25'/4
UNION
RESERVOIR I
I
) 2/7 . g
1 • / TH-3
I LEGEND :
TH-1 INDICATES APPROXIMATE
15' ' ' • LOCATION OF EXPLORATORY
TH-7 ' BORING
ROPp 26 '
•
pr J
O' -0°.°I ° -. rail INDICATES APPROXIMATE
(\NC'��co G /- ' - , L._.,J BORNG LOCATION OF EXPLORATORY
\S -'/T�1 TH-4 •
20'
•
•.' 15 cy 10, J` ESTIMATED DEPTH
10' 10' • c', TO GROUNDWATER
-- 0
I
' 0
•
/,I
rx y NOTE: THIS ESTIMATE IS BASED ON A
• SUBJECTIVE ANALYSIS OF DRILL
Z
HOLE DATA, AND MAY NOT
g -• pPD REFLECT LOCAL VARIATIONS.
0
al
,.I �. #SSS U
ITH-2 • F
I • �''
I' w
o______.
Estimated Depth
LIFEBRIDGE CHRISTIAN CHURCH
to Groundwater
JOB NO.FC-2442 FIGURE 5
)
1
)
# . , ,
if
. • /•
•
,,c _ _ _
APPROXIMATE SCALE • •TH-6
1' = aoo / TH-5 •I•
•
'
'
R91 UNION • /
I
RESERVOIR • e
/ i-a-a--/
a
•/
4965 I
ii LEGEND :
• TH-7 '
r al 26177e • TH-1 INDICATES APPROXIMATE
it° 4960 J • LOCATION OF EXPLORATORY
GaVN •• .‘•*"...
.• BORING
\s • •er •/ r.._..i INDICATES APPROXIMATE
Si- '•• T•-1 •T•-4 N L__,j LOCATION OF EXPLORATORY
. r BORING
I 4955 CO
' Q CONTOUR OF APPROXIMATE
•• �O -4945- GROUNDWATER SURFACE
ELEVATION
z
..
.................4950 .'/ Opp O NOTE: THIS ESTIMATE IS BASED ON A
i O SUBJECTIVE ANALYSIS OF DRILL
• 0 HOLE DATA,AND MAY NOT
•/•• •
�eg'C��� REFLECT LOCAL VARIATIONS.
' G�
TH-2 Z
I •
• •
4945 i ••/ w
i Approximate Elevation
of Groundwater Surface
LIFEBRIDGE CHRISTIAN CHURCH FIGURE 6
JOB NO.FC-2442
.
EiQ:1
3 , , I , ,• ,
a
i
EXPANSION UNDER CONSTANT I
3RE.SSURE DUE TO WETTING
..
0 °
iii
.. W
i
h o2 I I • I
i
co
ix I . I I
-3 - t - r 3
0.1 1.0 10 100
APPLIED PRESSURE-KSF
_
Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 106 PCF
"' From TH-1 AT 4 FEET NATURAL MOISTURE CONTENT= 18.4 %
3 I
... 2 . . . I ' I
i
w
ADDITIONAL COMPRES§I N
_
UtilDER CONS-ANT PRES URI
-- (7)
0 l I ' DUE I0 WETTrNG
1n I I
z
Q `
d -1 , _ l .
W
a
a0 _2 I 1I
a N
111
_3
a O
a -4 0I .
0.1 1.0 10 100
a APPLIED PRESSURE-KSF
Sample of CLAYSTONE NATURAL DRY UNIT WEIGHT= 116 PCF
From TH-2 AT 9 FEET NATURAL MOISTURE CONTENT= 16.7
a Swell Consolidaticn
a Test Results FIG. 7
LIFEBRIDGE CHRISTIAN CHURCH
JOB NO. FC-2442
-
- ...--, Ci;-Mi3
3 r I I
I
a ' I
2 I 1 _ f
I
1 -
{
z - . 1 _ 1
• 0 i EXPANSION UN i ER CONSTANT
a z
Q I I rRE�SURE DU TO WETTING
X -1
W
— o I I
a 0 _2 f i
- � '
CA
W l... IX .3 .
O.
— O
c..) y ,
0.1 1.0 10 100
— APPLIED PRESSURE-KSF
_. Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 107 PCF
From TH-3 AT 9 FEET NATURAL MOISTURE CONTENT= 19.4 %
3
- .. I I
H
2 - I I •
I
I
-- XPANSION UNDEN CJNSITAN
t .
PRESSURE DUE TO WETTING
- z 0 a
—
z
O.
x
1 I
W
a Z _2
O i
... N
Cl)
+ W
d -3 1.---
-.
2
a ( I
-4 , 1 , • I
- 0.1 1.0 10 100
APPLIED PRESSURE-KSF
Sample of CLAY,SANDY(CL) NATURAL DRY UNIT WEIGHT= 114 PCF
From TH-6 AT 9 FEET NATURAL MOISTURE CONTENT= 14.3 %
Swell Consolidation
Test Results FIG. 8
-
LIFEBRIDGE CHRISTIAN CHURCH
JOB NO. FC-2442
) ) ) ) ) ) ) ) ) ) 1 ) ) ) ) ) ) 1 ) ) 1 ) ) ) ) ) 1 ) ) ) ) ) ) ) ) 1 ) ) ) ► 1 ) )
) ) )
TABLE I Eg
SUMMARY OF LABORATORY TEST RESULTS
NATURAL SWELL TEST DATA SOIL ATTERBERG LIMITS UNCONFINED SOLUBLE PASSING
HOLE DEPTH NATURAL DRY SWELL APPLIED SUCTION LIQUID PLASTICITY COMPRESSIVE SULFATES NO. 200 SOIL TYPE
MOISTURE DENSITY PRESSURE VALUE LIMIT INDEX STRENGTH SIEVE
(FEET) (%) (PCF) (%) , (PSF) _ (pF) (%) (%) (PSF) _ (%) (%)
TH-1 4 18.4 106 1.5 1,000 ' _ CLAY, SANDY(CL)
TH-2 4 25.1 96 45 29 92 CLAY, SLIGHTLY SANDY(CL)
TH-2 9 16.7 116 -0.4 1,000 CLAYSTONE
TH-3 9 19.4 107 1.0 1,00G CLAY, SANDY(CL)
TH-4 9 13.7 109 NL NP 1,400 SANDSTONE
TH-5 4 52 34 96 CLAY, SLIGHTLY SANDY(CH)
TH-6 9 14.3 114 1.4 1,000 CLAY, SANDY(CL)
TH-7 4 15.9 49 31 0.040 CLAY, SANDY(CL)
LIFEBRIDGE CHRISTIAN CHURCH
JOB NO. FC-2442 Page 1 of 1
a
a
a
APPENDIX A
GUIDE SITE GRADING SPECIFICATIONS
LIFEBRIDGE PUD
SOUTHWEST OF COUNTY ROAD 26 AND COUNTY ROAD NO. 3 1/2
WELD COUNTY, COLORADO
a
a
a
a
^ LIFEBRIDGE CHRISTIAN CHURCH
^. LIFEBRIDGE PUD
CTL/T FC-2442
a
GUIDE SITE GRADING SPECIFICATIONS
LIFEBRIDGE PUD
WELD COUNTY, COLORADO
1. DESCRIPTION
This item shall consist of the excavation, transportation, placement and
compaction of materials from locations indicated on the plans, or staked by the
Engineer, as necessary to achieve preliminary street and overlot elevations. These
specifications shall also apply to compaction of materials that may be placed
a outside of the project.
,^ 2. GENERAL
The Soils Engineer shall be the Owner's representative. The Soils Engineer
shall approve fill materials, method of placement, moisture content and percent
compaction, and shall give written approval of the completed fill.
3. CLEARING JOB SITE
The Contractor shall remove all trees, brush and rubbish before excavation
or fill placement is begun. The Contractor shall dispose of the cleared material to
provide the Owner with a clean, neat appearing job site. Cleared material shall not
be placed in areas to receive fill where the material will support structures of any
kind.
4. SCARIFYING AREA TO BE FILLED
All topsoil and vegetable matter shall be removed from the ground surface
upon which fill is to be placed. The resulting surface shall then be plowed or
scarified until the surface is free from ruts, hummocks or other uneven features
a
which would prevent uniform compaction by the equipment to be used.
.� 5. COMPACTING AREA TO BE FILLED
After the foundation for the fill has been cleared and scarified, it shall be
disked or bladed until it is free from large clods, brought to the proper moisture
content, (0 to 3 percent above optimum) and compacted to obtain a firm platform
for fill placement.
6. FILL MATERIALS
Fill soils shall be free from vegetable matter or other deleterious substances,
and shall not contain rocks having a diameter greater than six (6) inches. Fill
a materials shall be obtained from cut areas shown on the plans or staked in the field
by the Engineer or imported to the parcel. Concrete, asphalt, and other deleterious
materials or debris shall not be used as fill. Import materials shall be similar to on
site soils.
LIFEBRIDGE CHRISTIAN CHURCH
^ LIFEBRIDGE PUD
CM FC-2442 A-1
a
7. MOISTURE CONTENT
Fill materials shall be moisture treated to within 0 to 3 percent above optimum
moisture content as determined by the Standard Proctor Compaction Test (ASTM
D 698). Sufficient laboratory compaction tests shall be made to determine the
— optimum moisture content for the various soils encountered in borrow areas or
imported to the parcel.
The Contractor may be required to add moisture to the excavation materials
- in the borrow area if, in the opinion of the Soils Engineer, it is not possible to obtain
uniform moisture content by adding water on the fill surface. The contractor will
be required to rake or disk the fill soils to provide uniform moisture content through
the soils.
The application of water to fill materials shall be made with any type of
watering equipment approved by the Soils Engineer, which will give the desired
results. Should too much water be added to any part of the fill, such that the
material is too wet to permit the desired compaction from being obtained, rolling
and all work on that section of the fill shall be delayed until the material has been
allowed to dry to the required moisture content. The Contractor will be permitted
to rework wet material in an approved manner to hasten its drying.
8. COMPACTION OF FILL AREAS
Selected fill material shall be placed and mixed in evenly spread layers. After
each fill layer has been placed, it shall be uniformly compacted to not less than 95
percent of standard Proctor maximum dry density (ASTM D 698). Fill materials
shall be placed such that the thickness of loose material does not exceed 8 inches
and the compacted lift thickness does not exceed 6 inches.
Compaction, as specified above, shall be obtained by the use of sheepsfoot
rollers, multiple-wheel pneumatic-tired rollers, or other equipment approved by the
Soils Engineer for soils classifying as CL, CH, or SC. Granular fill shall be
compacted using vibratory equipment or other equipment approved by the Soils
Engineer. Compaction shall be accomplished while the fill material is at the
specified moisture content. Compaction of each layer shall be continuous over the
entire area.
9. COMPACTION OF SLOPE SURFACES
Fill material shall be compacted by means of sheepsfoot rollers or other
suitable equipment. Compaction operations shall be continued until slope surfaces
are stable, but not too dense for planting, and there is no appreciable amount of
loose soil on the slope surfaces. Compaction of slope surfaces may be done
progressively in increments of three to five feet (3'to 5') in height or after the fill is
brought to its total height. Permanent fill slopes shall not exceed 3:1
^ (horizontal:vertical).
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
A-2
CTL/T FC-2442
10. DENSITY TESTS
Field density tests shall be made by the Soils Engineer at locations and
depths of his choosing. Where sheepsfoot rollers are used, the soil may be
disturbed to a depth of several inches. Density tests shall be taken in compacted
material below the disturbed surface. When density tests indicate the density or
moisture content of any layer of fill or portion thereof is below that required, the
particular layer or portion shall be reworked until the required density or moisture
content has been achieved.
Observation by the Soils Engineer shall be full time during the placement of
fill and compaction operations so that they can declare the fill was placed in
general conformance with specifications. All inspections necessary to test the
placement of fill and observe compaction operations will be at the expense of the
Owner.
11. COMPLETED PRELIMINARY GRADES
All areas, both cut and fill, shall be finished to a level surface and shall meet
the following limits of construction:
A. Overlot cut or fill areas shall be within plus or minus 0.2 of one
foot.
B. Street grading shall be within plus or minus 0.1 of one foot.
The civil engineer, or duly authorized representative, shall check all cut and
fill areas to confirm that the work is in accordance with the above limits.
12. SUPERVISION AND CONSTRUCTION STAKING
All construction staking will be provided by the Civil Engineer or his duly
authorized representative. Initial and final grading staking shall be at the expense
of the owner. The replacement of grade stakes through construction shall be at the
expense of the contractor.
�. 13. SEASONAL LIMITS
No fill material shall be placed, spread or rolled while it is frozen, thawing, or
during unfavorable weather conditions. When work is interrupted by heavy
precipitation, fill operations shall not be resumed until the Soils Engineer indicates
the moisture content and density of previously placed materials are as specified.
2-2
... LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTO-FC-2442 A-3
14. NOTICE REGARDING START OF GRADING
The contractor shall submit notification to the Soils Engineer and Owner
advising them of the start of grading operations at least three (3) days in advance
of the starting date. Notification shall also be submitted at least 3 days in advance
of any resumption dates when grading operations have been stopped for any
reason other than adverse weather conditions.
15. REPORTING OF FIELD DENSITY TESTS
Density tests made by the Soils Engineer, as specified under "Density Tests"
above, shall be submitted progressively to the Owner. Dry density, moisture
content and percentage compaction shall be reported for each test taken.
16. DECLARATION REGARDING COMPLETED FILL
The Soils Engineer shall provide a written declaration stating that the parcel
was filled with acceptable materials, or was placed in general accordance with the
r
specifications.
17. DECLARATION REGARDING COMPLETED GRADE ELEVATIONS
A registered Civil Engineer or licensed Land Surveyor shall provide a
declaration stating that the site grading has been completed and resulting
elevations are in general conformance with the accepted detailed development
plan.
LIFEBRIDGE CHRISTIAN CHURCH
LIFEBRIDGE PUD
CTL/T FC-2442 A-4
a
a
GEOLOGIC AND PRELIMINARY
GEOTECHNICAL INVESTIGATION
PORTION OF WHITHAM PROPERTY I
IORTHEAST OF COLORADO HIGHWAY 119 AND
COUNTY ROAD NO. 31/2
WELD COUNTY, COLORADO
a
CTL/THOMPSON , INC .
CONSULTING ENGINEERS
TABLE OF CONTENTS
^ SCOPE 1
SUMMARY OF CONCLUSIONS 1
SITE 2
PROPOSED DEVELOPMENT 3
SITE GEOLOGY AND GEOLOGIC HAZARDS 4
SUBSURFACE CONDITIONS 6
SITE DEVELOPMENT 9
Ground Water 9
Grading 11
Slope Stability and Erosion 13
Utility Construction 13
Pavements 14
RESIDENTIAL CONSTRUCTION CONSIDERATIONS 15
Foundations 15
Slab-on-Grade and Basement Floor Construction 16
Basements 17
SURFACE DRAINAGE 18
CONCRETE 19
LIMITATIONS AND ADDITIONAL INVESTIGATION 19
FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS
FIG. 2 - ESTIMATED BEDROCK DEPTH
FIG. 3 - ESTIMATED BEDROCK ELEVATION
FIG. 4 - ESTIMATED GROUND WATER DEPTH -
FIG. 5 - ESTIMATED GROUND WATER ELEVATION
FIGS.6 THROUGH 8 - SUMMARY LOGS OF EXPLORATORY BORINGS
FIGS. 9 THROUGH 19 - SWELL CONSOLIDATION TEST RESULTS
FIG. 20 -TYPICAL SEWER UNDERDRAIN DETAIL
FIG. 21 - SANITARY SEWER MAIN UNDERDRAIN DETAIL
1
TABLE I - SUMMARY OF LABORATORY TEST RESULTS
APPENDIX A -GUIDE SITE GRADING SPECIFICATIONS
^
PULTE HOME CORPORATION
WHITHAM PROPERTY
CLTIT FC-1044
^
^ �
a
3. A successful parcel wide subdrain will tend to lower the ground water
a elevation under Oligarchy Ditch (aligned approximately parallel to the
boundary of the parcel we investigated)just north of the parcel. The
affect on Oligarchy Ditch will need consideration when evaluating the
decision to install a parcel wide subdrain.
4. The clays at the site can be characterized as nil to low expansive and
athe bedrock as low expansive. We believe footings can be the
foundations for the residences proposed for the subdivision if the final
lot grades are at or above the existing natural grades. The finally
selected site grading plan will determine if the foundation strata for a
given residence foundation will be footings bearing on clays or
footings bearing on the bedrock. The tendency for swell in the
bedrock will cause the footing design criteria to include criteria for a
^ minimum dead load for both bearing strata.
Much lowering of the final grades below the existing natural grades
will probably result in drilled piers as the preferred foundation for 10
a percent of the residences.
5. The natural clays and bedrock can be the subgrade for slab-on-grade
basement floors. Considerations for slab-on-grade basement floors
are discussed in "Slabs-on-Grade and Basement Floor Construction"
subsection.
a 6. The natural clays are a weaker subgrade for pavements. Residential
streets will probably require full-depth asphaltic concrete pavement
thicknesses of the order of 6 inches (4 inches of asphaltic concrete
over 8 inches of the compacted base course) and thicker pavement
sections for collector and arterial streets. These sections could be
thinned by strengthening the subgrade with lime or other strengthener.
a 7. Control of the surface water will influence the performance of
foundations, slab-on-grade floors and pavements. Surface ground
contours and drainage structures must cause rapid runoff of surface
water away from structures and removal of the water from the area.
SITE
a
The site (parcel) is approximately 250 acres located northeast of the
intersection of Colorado Highway 119 and County Road No. 3'/2 in Weld County,
a Colorado (Fig. 1). The parcel is currently planted with corn and hay. From a local
high point at the northwest corner of the parcel, the ground surface slopes down
gradually to the south and east. No significant erosional features were observed.
The improvements on the parcel are fences and a graveled road extending from the
PULTE HOME CORPORATION
^ WHITHAM PROPERTY
CLT?FC-1044 2
SITE GEOLOGY AND GEOLOGIC HAZARDS
The parcel is located within the Colorado Piedmont section of the Great Plains
_ physiographic province. The Piedmont is a broad erosional trench which separates
the Southern Rocky Mountain from the High Plains. Mapping by R.B. Colton (USGS
Map 1-855-6, Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado 1978)
indicates the surface of the parcel is Eolian (Qe) deposits consisting of olive-brown-
-
gray windblown clay, silt and sand. The underlying bedrock consists of the Upper
Transition Zone of the Pierre Shale (Kptz), which is described as interbedded
sandstone and shale with hard sandstone ledges and water with high sulfate
content. The thickness of the Pierre Shale is about 2,800 feet. We believe the Pierre
Shale dips gently to the east in the area of the parcel. Our field exploration generally
confirmed the conditions described by published maps.
This section discusses geologic hazards that we believe could affect land
planning and zoning. Specific requirements of Colorado House Bill 1041 "Areas and
Activities of State Interest" and Colorado Senate Bill 35 "County Planning and
Building Codes" are addressed. This section was reviewed by our Engineering
Geologist, Mr. David A. Glater, PE, CPG.
The claystone phases of the bedrock are expansive. This can result in more
or less damage to improvements or structures depending upon the characteristics
of the claystones and the increase in moisture that occurs. Engineered design of
pavements, foundations, slabs-on-grade and surface drainage can mitigate the
a
effects of expansive bedrock. The soils and bedrock under this parcel are not
expected to be unusually corrosive to metal but may have sulfate concentrations that
a can affect concrete. Natural slopes are gentle and appear to be stable.
Significant faulting and structural discontinuities are not expected in the
bedrock at this site. The soil and bedrock units are not expected to respond
unusually to seismic activity. The area is considered by the most recent editions of
the Uniform Building Code (UBC) as Zone 1, its least active zone designation.
Maximum bedrock accelerations at 4 to 7.5 percent of gravity are probable during
PULTE HOME CORPORATION
WHITHAM PROPERTY
CLT/T FC-1044 4
a
a
No economically important mineral deposits are expected on this parcel or are
known to occur nearby. We do not expect ground subsidence related to natural or
mining processes.
The borings we drilled on the parcel showed ground water was shallow under
the parcel. It was above typical basement depth (measured from the existing ground
surface). The development strategy for a parcel with shallow ground water usually
includes consideration of a parcel-wide subdrain, foundation drains around
basements, raising the natural ground elevations with engineered fill to provide the
needed distance above ground water for basements and probably other mitigating
a measures.
No geologic hazards which would preclude the proposed development were
noted on the subject tract. The shallow ground water will require attention. We
^ believe the geologic hazards can be mitigated with proper engineering design and
construction practices, as discussed in this report.
SUBSURFACE CONDITIONS
Clays overlaying sedimentary, interlayered claystone, sandstone and
siltstone; claystone; and sandstone bedrock were penetrated by the 12 borings we
drilled to investigate the parcel subsurface. The approximate boring locations are
"' shown on Fig. 1. Our borings were drilled with a 4-inch diameter, continuous flight
auger and a truck-mounted drill rig. The drilling operations were observed by our
field representative who logged the soils and obtained samples for laboratory
testing. Graphic logs of the soils found in our borings including results of field
penetration resistance tests are shown in Figs. 6 through 8. Samples obtained
during drilling were returned to our laboratory where they were visually classified
and selected for testing. The results of our laboratory tests are on Figs. 9 through
^ 19 and summarized in Table I.
a
PULTE HOME CORPORATION
^ WHITHAM PROPERTY
1 CUM FC-1044 6
a
a.
V
percent, plasticity indices of 19 and 25 percent and 73 and 96 percent silt and clay
size particles (passing No. 200 sieve).
Table A - Summary of Swell Test Results. The following table reviews and
compares the swell behavior of the samples we tested.
No Range of Measured Swell (%)
Compressed Movement
Soil Type Wetting Very
Due to Low Moderate High High
Wetting 0 to <2 2 to<4 4 to <6
6
) Number and Percent of Samples
Sandy Clay 0 0 3 0 0 0
0% 0% 100% 0% 0% 0%
.. Weathered 1 0 0 0 0 0
Claystone 100% 0% 0% 0% 0% 0%
Interbedded 1 3 5 0 0 0
Sandstone/ 11% 33% 56% 0% 0% 0%
_ Claystone
Shallow 1 1 1 0 0 - ---0
Claystone 33% 33% 33% 0% 0% 0%
—
Deeper 0 0 2 1 0 0
Claystone 0% 0% 67% 33% 0% 0%
1 0 0 0 0 0
Sandstone
a 100% 0% 0% 0% 0% 0%
4 4 11 - 1 - -0 0
Overall
a20% 20% 55% 5% 0% 0%
— Ground Water. Free ground water was encountered in 10 of our 12 borings
— at depths from 7 to 32 feet at the time of drilling and in all borings at depths of 3 to
7.5 feet when checked several weeks after drilling. Measurements were taken in
June and July and ground water levels did not change appreciably between
measurements. The parcel was being irrigated while we were drilling our borings
"^ and during the time we made subsequent ground water depth measurements. We
believe the irrigation was started during the week between the staking of our boring
locations and drilling. We believe water was turned into Oligarchy Ditch shortly
PULTE HOME CORPORATION
... WHITHAM PROPERTY
MITT FC-1044 8
a
grading. This says something will need to be done to make basements feasible. In
our opinion, two alternatives seem technically feasible, namely:
a. Install a parcel wide subdrain system to lower the ground water under
the parcel so it will be at least 3 feet below the basement floor
elevations at the residence locations and provide foundation drains
around all residences. Figure 20 shows conceptually this alternative;
or
b. Raise the ground surface elevations enough that basement floor
elevations at the residence locations will be at least 3 feet above the
^ depths to ground water shown on Figure 3 and provide foundation
drains around all residences; or
c. A combination of(a) and (b) above.
Subdrain. Two complications we can visualize for the area wide subdrain are
topographic constraints and Oligarchy Ditch. It will be difficult at best to drain a
subdrain by gravity. This suggests lift stations may be needed to drain the subdrain.
—� Regarding Oligarchy Ditch,the subdrain will tend to lower the ground water elevation
under the ditch also and may influence leakage from the ditch. These complications
will need to be reviewed when deciding to install a parcel-wide subdrain. Additional
investigation may prove needed to finally decide for and design a parcel wide
subdrain. Such an investigation would be aimed at better identifying the possible
sources of ground water, and measuring the permeability of the soil and bedrock to
finally recommend a drain configuration and drain sizing.
The parcel wide subdrain we envision will be a combination of an interceptor
drain along most of the west, the north and a part of the east side of the parcel and
an underdrain under all the sanitary sewer mains under the streets. The invert
elevation of the interceptor, it appears to us, will be dictated by the elevation of the
bedrock (Figure 5) near the midpoint of the north property boundary where the
elevation is lower compared to the northwest and northeast corners. It is important
that the invert of the interceptor everywhere be at least one foot below the bedrock
surface but it must also be sloped from its high point to drain. The underdrain
system installed under the sanitary sewer mains will supplement the interceptor and
serve as an outlet for individual residence foundation drains (see "Basements"
PULTE HOME CORPORATION
^ WHITHAM PROPERTY
1 GLUT FC-7044 10
topsoil and other deleterious matter. The cleared, grubbed and stripped materials
should be discarded or placed in areas that will never be under structures, utilities,
sidewalk, curbs and gutters, driveways or pavements.
After stripping, the resulting subgrade should be scarified, moisture
conditioned to 0 to 3 percent above optimum and compacted to obtain a firm
platform for fill placement. Our borings indicate some soft soils exist on the parcel.
Where soft soils are encountered, they can be stabilized prior to placing fill.
Stabilization of soft subgrade soils is often accomplished by removal and
replacement, scarifying and drying, utilizing geosynthetics or "crowding" crushed
rock into the subgrade until a firm surface is achieved.
The properties of the fill will affect the performance of foundations, slab-on-
" grade floor and pavements. The soils from the parcel are suitable for use as grading
fill. Claystones should be broken down before placing as fill. If imported materials
are necessary, they should consist of sandy clays that are low plastic and low
expansion like the on-site clays. A sample of all soils proposed for import for fill
should be submitted to our office for classification and approval prior to hauling
them to the site. Fill should be placed in thin loose lifts, moisture conditioned to 0
to 3 percent above optimum moisture content and compacted to at least 95 percent
of standard Proctor maximum dry density (ASTM D 698). Guide specifications for
— overlot grading are in Appendix A. Placement and compaction of the grading fill
should be observed and tested by a representative of our firm.
For the most part,the soils and bedrock at this parcel are nil to low expansive.
In addition the shallow ground water appears to have "pre-wetted" and decreased
the swell potential of the upper approximately 10 feet of soils and bedrock. The
deeper claystone bedrock in one of our borings was moderately expansive. If the
existing grades are lowered by cutting, this claystone will begin to influence
structure foundation type. If possible, site grading should be planned to provide at
least 4 feet of nil to low expansive clays or fill above the claystone bedrock so that
special foundations can be avoided.
PULTE HOME CORPORATION
WHITHAM PROPERTY
CLT/T FC•1044 12
maximum slope of 3/4:1 (horizontal:vertical). The contractors competent person on
site should identify the soils encountered in excavations and refer to OSHA
standards to determine appropriate slopes. Excavations deeper than 20 feet should
be designed by a professional engineer.
Ground water will be encountered during utility excavation. The clays and
bedrock at this parcel are expected to be low to moderately permeable. Ground
water seepage will be slow to moderate. We anticipate trench dewatering may be
accomplished by sloping the trench bottom to collection areas where water can be
removed by pumping, however large, heavy duty pumps should be anticipated.
Some zones of sandier clays and more permeable sandstone bedrock may exist
requiring the occasional use of well points or other means to lower ground water and
allow for excavation.
Water and sewer lines are usually constructed beneath paved roads.
Compaction of trench backfill will have significant effect on the life and
serviceability of pavements. We recommend trench backfill be placed in thin, loose
lifts, moisture conditioned to 0 to 3 percent above optimum moisture content and
compacted to at least 95 percent of standard Proctor maximum dry density (ASTM
0 698). The placement and compaction of fill and backfill should be observed and
tested by a representative of our firm during construction.
Pavements
The surficial soils found on-site have fair to poor pavement support qualities.
For preliminary planning purposes, we suggest assuming 6 inches of full depth
asphaltic concrete paving will be needed for local residential streets.A section using
asphaltic concrete and compacted base course would be 4 inches of asphaltic
concrete over 8 inches of base course. Thicker pavements will be needed for
collector and arterial streets. A subgrade investigation and pavement design should
be performed after overlot grading is complete.
PULTE HOME CORPORATION
WHITHAM PROPERTY
CLT/T FC•1044 14
bearing pressure for piers will prove to be of the order of 35,000 psf and the side
shear value in the bedrock 10 percent of the maximum end bearing capacity. The
minimum design dead load pressure will be of the order of 1000 psf. The minimum
_^ penetration for piers into bedrock will probably prove to be 6 feet, the minimum
length for piers will probably prove to be 16 feet and 4-inch void spaces will likely be
needed under grade beams between the piers. There is the possibility some piers
will need to be cased to dewater and clean the pier holes due to the ground water
found under the parcel.
^
Slab-on-Grade and Basement Floor Construction
Slabs-on-grade are typically used for basement floors on lots with soil
conditions similar to this parcel. Our firm generally recommends structurally
supported basement floors for high (4 to less than 6 percent) and very high (6
percent or greater) swell potentials. Preliminary data indicate structural basement
floors will not be required on any of the tots on this parcel. Site grading cuts in
areas where bedrock is shallowest should be avoided to keep basement floors above
the bedrock or as far up in the more moist, lower swelling portions of the bedrock
as possible.
The following precautions will not eliminate slab-on-grade movement but will
reduce the potential for damage due to movement of slabs:
1. Isolation of the slabs from foundation walls, columns or other slab
penetrations;
2. Voids under interior partition walls to allow for slab movement without
transferring the movement to the structure;
3. Flexible water and gas connections to allow for slab movement. A
flexible duct above furnaces may also be required; and
4. Proper surface grading and foundation drain installation to reduce
water availability to slab subgrade and foundation soils.
^
PULTE HOME CORPORATION
' WHITHAM PROPERTY
CLT/T FC-1044 16
a
the residences and suggest assuming for preliminary designs an equivalent fluid
density of 50 pcf for backfill in design calculations.
SURFACE DRAINAGE
The performance of improvements in this development will be influenced by
surface drainage. When developing an overall drainage scheme, consideration
should be given to drainage around each residence. Drainage should be planned so
that surface runoff is directed away from foundations and is not allowed to pond
adjacent to or between structures or over pavements. We recommend slopes of at
least 12 inches where possible in the first 10 feet for the areas surrounding all
residences or buildings. In areas between houses which are less than 20 feet apart,
the slope should be at least 10 percent toward the swale used to convey water out
of these areas. Slopes marginally less steep than those recommended may be
— necessary at the back of the houses on lots which drain to the front. Roof
downspouts and other water collection systems should discharge well beyond the
limits of all backfill around structures.
Proper control of surface runoff is also important to control the erosion of
surface soils. Sheet flow should not be directed over unprotected slopes. Water
should not be allowed to pond at the crest of slopes. Permanent slopes should be
revegetated to reduce erosion.
Attention should be paid to compact the soils behind curb and gutter adjacent
— to streets and parking areas and in utility trenches during development. If surface
drainage between preliminary development and construction phases is neglected,
performance of the roadways, flatwork and foundations will be poor. When
considering landscaping of common areas, we recommend the use of xeriscaping
a which requires little initial or long-term watering.
PULTE HOME CORPORATION
a WHITHAM PROPERTY 1 S
CLT?FC-1044
investigations should be performed for design of residence foundations and slab-on-
grade floors and street pavement sections after overlot grading has been completed.
We should review the final grading plans prior to construction to look for potential
geotechnical problems.
We believe this investigation was conducted in a manner consistent with that
level of care and skill ordinarily used by geotechnical engineers practicing in this
area at this time. No other warranty, express or implied, is made. If we can be of
further service in discussing the contents of this report or analyses of the influence
of subsurface conditions on the design of the proposed development, residences
and streets, please call.
CTL/THOMPSON, INC
Howar• Perko
Proje• E gineer
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PULTE HOME CORPORATION
WHITHAM PROPERTY
CUR FC-1044 20
a
SCALE: 1"=400'
I
m
6 LI
oin 6 I "
c � � I
C HIGHWAY 119
Ill
COUNTY ROAD 3 12
eM VICINITY MAP
NO SCALE
• • • - • TH-10
TH-1 TH-4 TH-7
a) .
I - I
Q
ir-
Z _ • TH-11
CD I I
_ • TH-8 LEGEND:
• • TH-5
o
TH-2
Q • TH-1 INDICATES APPROXIMATE -
0 LOCATION OF EXPLORATORY
I Q I I BORING
Q _ - e TEMPORARY BENCHMARK
TH-6 TH-9 TBM WATER UMW MANHOLE
• TH-3 - • _ _ •_ (ASSUMED EL = totA)
TH-12
I-
t
Locations of
Exploratory
PUDE HOLE CORPORATIONWHOM PlIOMMY Borings
,�. 1
Jab No. �1aa
1
4
SCALE: 1"=400'
1
43p 8 a
COU {jj TY ROAD 3 1/
2
Jei
� - - • • TH-10
GI ,/� TH-1 TH-4 TH-7
Q
2 LEGEND:
I
2 Q • TH-11
O Al I I • TH-1 INDICATES APPROXIMATE
D � • TH-8�� 7S LOCATION OF EXPLORATORY
Q / • • TH-5L.. 120 BORING
IY TH-2
i 0 —100-- B aa�s EsnAn:
JO _ _ �g 110 EnRocN ELEVATION
U
I 103
• TH-3 •
TH-6 TH-9 \S\ "
Qp TH-12
Estimated
Bedrock
RAM HOME CORPORATIONWIMPY PROPERTY Elevation
Job No. F'F1 a4 Fig. 3
l LI1'
SCALE: 1"=400'
i
- COUNTY ROAD 3 1/2 -
A• ( TH10
\TH-1 5 TH-4 TH-7
rn 4 \../5
\//1
1 - 4 3 �
Q LEGEND:
\\LIDTH-11
' 0 INDICATES APPROXIMATE
_ /•`T -g • TH-1 LOCATION OF EXPLORATORY
• • TH- B BORING
O •
TH-2
' < / INDICATES ESTIMATED DEPTH
1 �. -5� . TO GROUND WATER (FEET)
O J' O
U TH-9• TH-3
- - � • TH-12
Estimated
Ground Water
PULlE HOME CORPORATION11141141.4 PIKIPIRIY Depth
Job No. FC-1044 Rg. 4
SCALE: 1"=400'
I
-
COUNTY ROAD 3 1/2
r — - - • — TH-10
' TH-1 TH-4 TH—
\' .CD125
100 105 110 115 120
r \..N........
QLEGEND:
• TH-11
=CD I 120 I • TH-1 INDICATES APPROXIMATE
• TH S LOCATION OF EXPLORATORY
TH-5 BORING
Q H-2 81 INDICATES ESTIMATED GROUND
' ( 110 115 —1 as — WATER ELEVATION (FEEL) -
O \\::
105
O 5
O TH-6 1��TH -
TH-3 — — � "—
\ is
TH-12
$ Estimated
„ON Ground Water
PULTE
WRNS PROPIRIV Elevation
Job No. FO-1O44 Flo. 6 •
V
LEGEND:
1
130 TH-11 130 I I CLAY, SANDY, SILTY, MEDIUM STIFF, MOIST TO WET, BROWN (CL).
TH-12
(EL.=125.7) (EL.=124.9)
y = PM _ CLAY, SANDY, STIFF, MOIST, OLIVE, BROWN (WEATHERED
= 10/120 50/12
120m50/12
CLAYSTONE).
11/12 ■50/12 120
Q "� INTERBEDDED CLAYSTONE, SILTSTONE AND SANDSTONE, HARD TO VERY
S MI _= \ HARD, SLIGHTLY MOIST, BROWN, RUST (BEDROCK).
25/12 ■50/5
_ CLAYSTONE, HARD TO VERY HARD, SLIGHTLY MOIST, BROWN, RUST
50/12 (BEDROCK).
110 050/2 110
1 \ -
50/11 `\ SANDSTONE, VERY HARD, SLIGHTLY MOIST, BROWN (BEDROCK).
.0 50/4
\.
f- ■ 50/5 F
ww 100 \\■50/2 100 w ; SANDSTONE, CEMENTED LENSE, VERY HARD, SLIGHTLY MOIST, BROWN
w w V - (BEDROCK).
I 1
DRIVE SAMPLE. THE SYMBOL 8/12 INDICATES THAT 8 BLOWS OF A
H
_t 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A
> > 2.5 INCH 0.0. SAMPLER 12 INCHES.
J 0 90 J
W W
- SZ INDICATES WATER LEVEL MEASURED AT THE TIME OF DRILLING.
- Y INDICATES WATER LEVEL MEASURED ON JUNE 22, 1998.
80 Y INDICATES WATER LEVEL MEASURED ON JULY 10, 1998.
s
_ NOTES:
_ 1. THE TEST HOLES WERE DRILLED ON JUNE 18 AND 19, 1998 USING A
TRUCK-MOUNTED DRILL RIG AND 4-INCH DIAMETER, CONTINUOUS FLIGHT
AUGER.
70 70
2. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND
CONCLUSIONS IN THIS REPORT.
-
3. BORING ELEVATIONS ARE APPROXIMATE AND SURVEYED WITH RESPECT TO
THE TEMPORARY BENCHMARK SHOWN ON FIG. 4.
60
0 50
SUMMARY LOGS OF EXPLORATORY BORINGS
JOB NO. FC-1044 FIG. 8
- 130 130
a
TH-4 -
120 (EL.=^-119)
120
_ ■6/12 -
■4/12 TH-5
az (EL.=110.6) -
a
110 \0 50/6 110
\ II 8/12 -
TH-2 II 8/12
\
(EL.=102.8) ■50/6 1 a �a -
r TH-1 _
w 100 (EL.=98.4) i�■ 3/12 \\050/! k.50/12
w
100
LL ■ 14/12(EL.=95.6) �� 2 ��
- Z y ■8/12 / �� _ : 1 50/2 -
\050/4 0
H ■6/12 �■ 50/8 _ 12/12 H
- ^ w Q \ 38/12 \ w
w 0 =
■6/12 a \■ 50/6 \ 90 w
\,\ 50/12 \ •50'1
MI 50/12 \1 50/5 \ , ■ 50/2
0
a
\ 50/6
■ 50/6 80
\\■ 50/4 -
a 50/5 -
�\I50/4 \ _ - -
a
\
Q 50/3
70 - 70
050/0 -
a
.. 0 60
..
a
0 50
a
SUMMARY LOGS OF EXPLORATORY BORINGS
JOB NO. FC-1044 FIG. 6
V
a TH-10
(EL.=129.2)
130 130
1 Y ■3/12 TH-7 - -
■3/12
- (EL.=121.8) -
TH-8
- (EL.=119.3)
120 ■ 14/12 \■50/12 120
a ■ 8/12 !■ 40/12
Q ■ 50/6 ■50/3
_, t
\\■ 50/12 TH-9 -
110 A- ■ 50/6 (EL.=108.6) 50/3 110
TH-6 '\ I50/12 \
(EL.=103.9) ■ 10/12 -
■ 50/6 • 14/12 \�50/2 -
7/12-
\• 50/6
a W 100 7/12 \ Q \\■ 50/5 .4-
\\•50/3 100 w
i Y \\■ 50/2 \ Q `\
/6 \\ z
H E150/12
50 \�50/4 -H
1- I--
C a
W 0 50/7 \■50/2 90 -w
_ \
50/6 ■50/2 -
a 0
50/5 \ 80
\U50/1 -I
a
70 70
a _
a
O 60
a
O 50
a
a
SUMMARY LOGS OF EXPLORATORY BORINGS
a SOB NO. FC-1044 FIG. 7
1 1 ► 1 1 ) ) 1 1 1 1 ) ► iI 1 1 ) 1 1 1 1 1 1 ) ) 1 ) 1 1 1 I 1 ) 1
I ) )
-n
3 N COMPRESSION % EXPANSION m fl COMPRESSION % EXPANSION
co 3
3 O N b 3 3 l• y N N O G
' z � a S W N - vo
• O m D- m r
9 ° r O :113
- m o
2 17
73
N X m X y
y r D m y ------ -
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Swell Consolidation
JOB NO. FC-1044 Test Results FIG. 11
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Swell Consolidation
JOB NO. FC-1044 Test Results FIG. 17
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Swell Consolidation
JOB NO. FC-1044 Test Results FIG. 19
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NO SCALE
Fit
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CONNECT UNDERDRAIN SERVIC ____
TO FOUNDATION DRAI
FIRST FLOOR
STREET
BASEMENT CRAWL
SANITARY SEWER SERVICE ----
TOP OF BASEMENT ---"Ti
SANITARY SEWER MAIN FLOOR 3'MIN
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r �/ w.w �an Y mow 8A" 1r6 - L2 1'MIN
'v AU11Y1wm
FIRST FLOOR
NDERDRAI IN
UNDERDRAlt. SERVICE
----- BOTTOM OF EXCAVATION
GROUNDWATER SURFACE VARIES. FOR POSSIBLE STRUCTURAL
�isseS, T ACTUAL GROUND WATER SURFACE MUST BASEMENT FLOOR
C �
C : ' BE CONFIRMS AFTER UNDERDRAIN
a SYSTEM IS INSIALLED.
1'IW,-'' • `3 `+
� oC'� :•^°'err — SLAB-ON-GRADE OR STRUCTURAL
FLOOR DEPENDING ON DESIGN
74 w
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011 Easton
5' \
' onto �
v CD Canasta
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SANITARY SEWER
l 4" PERFORATED
CORRUGATED POLY
PIPE (ASTM FP.
405)ET CONNECTION TO
RESIDENCE
a ' FOUNDATION
.4 . . HYLENE
DRAIN
PROVIDE - . '• ;,
MIRAFI
140N
6"MIN • • AC*MIN.
:w , d
• 6MI •
• • • • -
• Q •
V4;1 •4" •4-
` PVC PERFORATED SUBORAIN PIPE
SIZE VARIES
SPECIFIED TRENCH I 3/8" PERFORATIONS AT 5".
WASHED ROCK 1 2 ROWS AT 60• FROM VERTICAL
MAXIMUM SIZE: 1" WIDTH PVC PIPE AND FITTINGS
_ LESS THAN 3' PASSING CONFORMING TO ASTM 0 3034.
THE NO. 200 SIEVE SDR 35
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NOTE: NOT TO SCALE
-
Sanitary Sewer
- • Main
Underdrain
- I Job No. FC-1044 Fig. 21
) 1 1 1 1 ) 1 ) 1 1 1 1 ) ) ) ) 1 1 1 1 ), ) ) 1 1 ) ) ) 1 ) 1 ) 1 ) 1 ) ) ) 1 ) 1 ) ) )
)
JOB NO. FC-1044
irABLE I
SUMMARY OF LABORATORY TEST RESULTS
NATURAL ATTERBERG LIMITS : UNCONFINED SOLUBLE'PASSING
BORING DEPTH NATURAL DRY SWELL" LIQUID PLASTICITY 'COMPRESSIVE SULFATE NO.200 SOIL TYPE
MOISTURE DENSITY LIMIT INDEX STRENGTH CONTENT SIEVE
(ft) (%) cpcf) (%) (%) (%), (PO -(%°L (%)
l
TH-1 4 24.7 111 34 21 67 CLAY, SANDY (CL)
TH-1 9 27.8 91 CLAY, SANDY(CL)
TH-1 14 18.3 108 ' 0.0 INTERBEDDED CLAYSTONE/SANDSTONE
TH-2 4 21.3 106 0.1 CLAY, SANDY(CL)
TH-2 9 12.2 121 0.9 INTERBEDDED CLAYSTONE/SANDSTONE
_
TH-3 2 21.2 105 WEATHERED CLAYSTONE
TH-3 4 17.2 108 -0.1 CLAYSTONE
TH-3 9 33.3 101 42 25 96 CLAYSTONE
TH-3 14 12.9 120 0.4 CLAYSTONE
TH-4 9 15.5 115 0.2 INTERBEDDED CLAYSTONE/SANDSTONE
TH-4 19 13.8 109 -0.1 INTERBEDDED CLAYSTONE/SANDSTONE
TH-5 4 23.0 101 -0.1 WEATHERED CLAYSTONE
TH-6 ' 2 27.4 91 0.2 CLAY, SANDY(CL)
TH-6 9 13.6 122 0.6 CLAYSTONE
TH-6 14 12.8 117 0.4 CLAYSTONE
TH-7 _ 2 20.5 105 0.2 CLAY, SANDY(CL)
TH-7 4 23.5 101 CLAY, SANDY(CL)
TH-7 9 13.6 121 0.5 INTERBEDDED CLAYSTONE/SANDSTONE
TH-7 14 15.7 113 0.5 INTERBEDDED CLAYSTONE/SANDSTONE
TH-8 4 15.5 107 -0.1 ! SANDSTONE
TH-9 2 18.6 103 0.2 CLAY, SANDY(CL)
TH-9 4 19.3 103 CLAY, SANDY(CL)
_
TH-9 14 16.2 ; 31 6 40 INTERBEDDED SILTSTONE/SANDSTONE
TH-10 4 28.6 39 ' 25 77 CLAY,SANDY(CL)
TH-10 9 14.2 117 0.2 INTERBEDDED CLAYSTONEJSANDSTONE
TH-10 14 13.9 116 ' 0.0 INTERBEDDED CLAYSTONE/SANDSTONE
TH-11 2 24.2 100 CLAY, SANDY(CL)
TH-11 4 29.5 92 3,0 CLAY, SANDY(CL)
TH-11 ' 9 11.9 123 0.0
_ CLAYSTONE
_
TH-11 14 19.8 109 2.0 CLAYSTONE
"-Swell due to wetting at an applied pressure of 1,000 psf. Negative values iidicate consolidation. PAGE 1 OF 2
I
) ) ) ) ) ) ) ) ) ) ) ► ) ) ) ► ) ) ) 1 ► ) ) ) ► ) ) 1 ) 1 ) 1 1 ) ► ) ) ) 1 1 ) ) )
) )
JOB NO. FC-1044
TABLE I
SUMMARY OF LABORATORY TEST RESULTS
NATURAL ATTERBERG LIMITS UNCONFINED SOLUBLE PASSING
BORING DEPTH NATURAL DRY SWELL* LIQUID PLASTICITY COMPRESSIVE SULFATE NO.200 SOIL TYPE
MOISTURE DENSITY LIMIT INDEX STRENGTH CONTENT SIEVE
(ft) (%) (pc() (%) (%) (%) (psf) (%) (%)
TH-11 19 12.5 125 36 19 73 CLAYSTONE
- TH-12 19 16.8 105 0.0 INTERBEDDED CLAYSTONE/SANDSTONE
" -Swell due to wetting at an applied pressure of 1,000 psf. Negative values indicate consolidation. PAGE 2 OF 2
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APPENDIX A
GUIDE SITE GRADING SPECIFICATIONS
WHITHAM PROPERTY
NORTHEAST OF COLORADO HIGHWAY 119 AND COUNTY ROAD NO. 3 1/2
WELD COUNTY, COLORADO
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- PULTE HOME CORPORATION
WHITMAN PROPERTY
CLT/T FC-1044
-
GUIDE SITE GRADING SPECIFICATIONS
WHITHAM PROPERTY
WELD COUNTY, COLORADO
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1. DESCRIPTION
This item shall consist of the excavation, transportation, placement and
compaction of materials from locations indicated on the plans, or staked by the
Engineer, as necessary to achieve preliminary street and overlot elevations. These
specifications shall also apply to compaction of materials that may be placed outside
of the project.
2. GENERAL
The Soils Engineer shall be the Owner's representative. The Soils Engineer
shall approve fill materials, method of placement, moisture content and percent
compaction, and shall give written approval of the completed fill.
3. CLEARING JOB SITE
The Contractor shall remove all trees, brush and rubbish before excavation or
fill placement is begun. The Contractor shall dispose of the cleared material to
provide the Owner with a clean, neat appearing job site. Cleared material shall not
be placed in areas to receive fill where the material will support structures of any
kind.
4. SCARIFYING AREA TO BE FILLED
All topsoil and vegetable matter shall be removed from the ground surface
upon which fill is to be placed. The resulting surface shall then be plowed or
scarified until the surface is free from ruts, hummocks or other uneven features
which would prevent uniform compaction by the equipment to be used.
5. COMPACTING AREA TO BE FILLED
After the foundation for the fill has been cleared and scarified, it shall be disked
or bladed until it is free from large clods, brought to the proper moisture content,(0
to 3 percent above optimum) and compacted to obtain a firm platform for fill
placement.
6. FILL MATERIALS
Fill soils shall be free from vegetable matter or other deleterious substances,
and shall not contain rocks having a diameter greater than six (6) inches. Fill
materials shall be obtained from cut areas shown on the plans or staked in the field
by the Engineer or imported to the parcel. Concrete, asphalt, and other deleterious
materials or debris shall not be used as fill. Import materials shall be similar to on
— site soils.
PULTE HOME CORPORATION
^ WHITHAM PROPERTY CLTfT rc-1044 A-1
CUI
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7. MOISTURE CONTENT
Fill materials shall be moisture treated to within 0 to 3 percent above optimum
moisture content as determined by the Standard Proctor Compaction Test (ASTM
D 698). Sufficient laboratory compaction tests shall be made to determine the
optimum moisture content for the various soils encountered in borrow areas or
imported to the parcel.
The Contractor may be required to add moisture to the excavation materials in
the borrow area if, in the opinion of the Soils Engineer, it is not possible to obtain
uniform moisture content by adding water on the fill surface. The contractor will be
required to rake or disk the fill soils to provide uniform moisture content through the
soils.
The application of water to fill materials shall be made with any type of
watering equipment approved by the Soils Engineer, which will give the desired
results. Should too much water be added to any part of the fill, such that the
material is too wet to permit the desired compaction from being obtained, rolling and
all work on that section of the fill shall be delayed until the material has been allowed
to dry to the required moisture content. The Contractor will be permitted to rework
wet material in an approved manner to hasten its drying.
8. COMPACTION OF FILL AREAS
Selected fill material shall be placed and mixed in evenly spread layers. After
each fill layer has been-placed, it shall-be uniformly-compacted 1t-not-less-thole-95—
percent of standard Proctor maximum dry density(ASTM D 698). Fill materials shall
be placed such that the thickness of loose material does not exceed 8 inches and the
compacted lift thickness does not exceed 6 inches.
Compaction, as specified above, shall be obtained by the use of sheepsfoot
rollers, multiple-wheel pneumatic-tired rollers, or other equipment approved by the
Soils Engineer for soils classifying as CL, CH, or SC. Granular fill shall be
compacted using vibratory equipment or other equipment approved by the Soils
Engineer. Compaction shall be accomplished while the fill material is at the
specified moisture content. Compaction of each layer shall be continuous over the
entire area.
9. COMPACTION OF SLOPE SURFACES
Fill material shall be compacted by means of sheepsfoot rollers or other
suitable equipment. Compaction operations shall be continued until slope surfaces
are stable, but not too dense for planting, and there is no appreciable amount of
loose soil on the slope surfaces. Compaction of slope surfaces may be done
progressively in increments of three to five feet (3'to 5') in height or after the fill is
brought to its total height. Permanent fill slopes shall not exceed 3:1
(horizontal:vertical).
PULSE HOME CORPORATION
.� WHITHAM PROPERTY A-2
CLTfT FC-104d
10. DENSITY TESTS
Field density tests shall be made by the Soils Engineer at locations and depths
of his choosing. Where sheepsfoot rollers are used, the soil may be disturbed to a
depth of several inches. Density tests shall be taken in compacted material below
the disturbed surface. When density tests indicate the density or moisture content
of any layer of fill or portion thereof is below that required, the particular layer or
portion shall be reworked until the required density or moisture content has been
.. achieved.
Observation by the Soils Engineer shall be full time during the placement of fill
^ and compaction operations so that they can declare the fill was placed in general
conformance with specifications. All inspections necessary to test the placement
of fill and observe compaction operations will be at the expense of the Owner.
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11. COMPLETED PRELIMINARY GRADES
— All areas, both cut and fill, shall be finished to a level surface and shall meet
the following limits of construction:
A. Overlot cut or fill areas shall be within plus or minus 0.2 of one
foot.
B. Street grading shall be within plus or minus 0.1 of one foot.
The civil engineer, or duly authorized representative, shall check all cut and fill
areas to confirm that the work is in accordance with the above limits.
^
12. SUPERVISION AND CONSTRUCTION STAKING
All construction staking will be provided by the Civil Engineer or his duly
authorized representative. Initial and final grading staking shall be at the expense
of the owner. The replacement of grade stakes through construction shall be at the
expense of the contractor.
13. SEASONAL LIMITS
No fill material shall be placed, spread or rolled while it is frozen, thawing, or
during unfavorable weather conditions. When work is interrupted by heavy
precipitation,fill operations shall not be resumed until the Soils Engineer indicates
the moisture content and density of previously placed materials are as specified.
14. NOTICE REGARDING START OF GRADING
The contractor shall submit notification to the Soils Engineer and Owner
advising them of the start of grading operations at least three (3) days in advance of
the starting date. Notification shall also be submitted at least 3 days in advance of
PULTE HOME CORPORATION
WHITHAM PROPERTY
CLT/T Fc-1044 A-3
LEd
any resumption dates when grading operations have been stopped for any reason
other than adverse weather conditions.
15. REPORTING OF FIELD DENSITY TESTS
Density tests made by the Soils Engineer, as specified under"Density Tests"
above,shall be submitted progressively to the Owner. Dry density, moisture content
and percentage compaction shall be reported for each test taken.
^ 16. DECLARATION REGARDING COMPLETED FILL
The Soils Engineer shall provide a written declaration stating that the parcel
was filled with acceptable materials, or was placed In general accordance with the
specifications.
17. DECLARATION REGARDING COMPLETED GRADE ELEVATIONS
A registered Civil Engineer or licensed Land Surveyor shall provide a
declaration stating that the site grading has been completed and resulting elevations
are in general conformance with the accepted detailed development plan.
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PULTE HOME CORPORATION
WNmUW PROPERTY
CLTIT FC-1044 A-4
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CTUThompson, Inc.
1971 West 12th Avenue
Denver, Colorado 80204
(303) 825-0777
Commercial Testing Laboratories, Inc.
22 Lipan Street
Denver, Colorado 80223
(303)825-0777
�— CTUThompson, Inc.
5240 Mark Dabling Blvd.
Colorado Springs,Colorado 80918
(719) 528-8300
CTUThompson, Inc.
234 Center Dr.
�^ Glenwood Springs, Colorado 81601
(970) 945-2809
CTUThompson, Inc.
375 E. Horsetooth Rd.
The Shores Office Park
Building 3, Suite 100
Ft.Collins, Colorado 80525
(970) 206-9455
CTUThompson, Inc. C
4718 N. Elizabeth Street, Suite C-2
Pueblo, Colorado 81008
(719) 595-1287
Hello