HomeMy WebLinkAbout20052455.tiff •� FONT City of Fort Lupton
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ll,, , °; m Planning and Building
enon.0 Department
Performance,Integrity,Teamwork,
Accountability and Service
(303)857-6694 x 125
Tom Parko,Planning Director Fax(303 857-0351
130 S.McKinley Avenue e-mail:planner@fni.net
Fort Lupton,Colorado 80621 http://www.fortlupton.org
August 8, 2005
Weld County
Attention: Board of County Commissioners
915 Tenth Street
P.O. Box 758
Greeley, Colorado 80632
Dear Commissioners:
Enclosed please find the annexation impact report for the proposed Cottonwood Greens
annexation to the City of Fort Lupton. Per Colorado Revised Statutes and Fort Lupton
Municipal Code, the City is required to submit this report to the governing County, which
currently has jurisdiction over the unincorporated parcel. The Fort Lupton City Council
will have the first public hearing and first reading of the annexation ordinance on
September 7, 2005 at 7:00 P.M. If you have any questions please do not hesitate to
contact me at the number listed above.
Sincfely,,
/; . giO
Tom Parko
Planning Director
City of Fort Lupton
Cc: Cottonwood Greens Annexation File.
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; C }n/so I /p L 2005-2455
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fon City of Fort Luptonr Q, m Planning and Building
o` � Department
Performance,integmy,Teamwork,
Accountability and Service
(303)857-6694 x 125
Tom Parko,Planning Director Fax(303 857-0351
130 S.McKinley Avenue e-mail:plannertifrinet
Fort Lupton,Colorado 80621 http://www.fortlupton.org
August 8, 2005
COTTONWOOD GREENS
ANNEXATION IMPACT REPORT
Statement of Purpose
This Annexation Impact Report, which has been prepared pursuant to Section 31-12-108.5 of the
Colorado Revised Statutes, is based on the Annexation Petition, Annexation Plat, and
Annexation Master Plan submitted by the Applicant. It is being reviewed and evaluated by the
City of Fort Lupton Staff, and is scheduled for review by the City of Fort Lupton Planning
Commission and City Council at hearings scheduled for August 23, 2005, and September 7,
2005, respectively. Please contact Tom Parko, City Planner, Planning Director at the address on
the cover of this report, or at telephone number 303.857.6694, with comments and/or questions
regarding this report.
Project Description
The property proposed for annexation consists of approximately 173.417 acres situated in
Section 32 & 33, Township 2 North, Range 66 West of the 6th PM. The annexation is contiguous
to the City of Fort Lupton boundary for a distance of approximately 6514.55 feet. The
annexation has a total boundary of 15893.96 feet.
Requested zoning for the annexation property is PUD (Planned Unit Development) compliant
with City of Fort Lupton Zoning Regulations, permitting a mixed-use development of
commercial uses, a wide range of residential uses, and areas of open space, particularly along the
Fulton Ditch. Downtown Fort Lupton is located to the west of the annexation property, the
Montview residential subdivision is located southwest of the Property, and the Coyote Creek golf
course and subdivision is located directly to the south. The land is currently zoned agricultural
(AG) in Weld County. The Master Plan submitted in support of the annexation and zoning is
attached along with the Vicinity Map.
- 1 -
This report is divided into six elements, which correspond to C.R.S. 31-12-108.5 (1)(a) through
(0 and are set forth as follows:
(a) a map or maps of the municipality and adjacent territory to show the following:
(I) The present and proposed boundaries of the municipality in the vicinity of
the proposed annexation;
(II) The present streets, major trunk water lines, sewer interceptors, and
outfalls, other utility lines and ditches, and the proposed extension of such
streets and utility lines in the vicinity of the proposed annexation and;
(III) The existing and proposed land use pattern in the areas to be annexed.
(b) a copy of any draft of final pre-annexation agreement, if available;
(c) a statement setting forth the plans of the municipality for extending to or otherwise
providing for, within the area to be annexed, municipal services performed by or on
behalf of the municipality at the time of annexation;
(d) a statement setting forth the method under which the municipality plans to finance the
extension of the municipal services into the area to be annexed;
(e) a statement identifying existing districts within the area to be annexed;
(f) a statement on the effect of annexation upon local public school district systems
including the estimated number of students generated and the capital construction
required to educate such students.
The following maps have been attached as required in subparagraph (a) of C.R.S. Section 31-12-
108.5:
• The present and proposed boundaries of the City of Fort Lupton in the immediate vicinity
of the proposed annexation (Map #1) as more specifically depicted on the Annexation
Plats for the Cottonwood Greens Annexation (Map #2);
• The present streets major water transmission mains, primary sanitary sewer outfalls,
storm drainage infrastructure, ancillary utility mainlines, irrigation canals and ditches,
and the proposed extension of such streets and utility services in the vicinity of the
proposed annexation (Maps #3 and Map #4);
• The existing land use pattern in the area to be zoned Agriculture as depicted in the Weld
County Zone District Map (Map #5). The proposed land use pattern in the subject area to
be annexed is Planned Unit Development (P.U.D.) as depicted upon the Cottonwood
Greens Master Plan(Map#3).
In addition pursuant to the requirements of Subparagraphs (b) through (f), inclusive of said
section, the following items have addressed or presented:
(b) A draft and final Annexation Agreement and Annexation Ordinance shall be
submitted to the Weld County Planning Department and to the Weld County
Attorney, upon completion.
(c) The plans of the City of Fort Lupton for extending municipal services to, or
otherwise providing for municipal services to the subject property to be annexed as
follows:
1. On — Site / Off -Street Improvements: The Applicant intends to dedicate
rights-of-way for public streets, and improve them to public and private
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standards approved by the City. Design and improvements will include all
bridge crossings within the subject Property.
2. Dry Utilities to Service Property: Electrical, telephone, cable television and
natural gas facilities are located in the immediate vicinity of the properties to
be annexed and developed. Preliminary investigations confirm that such
facilities are of existing size and capacity to serve the property although line
extensions and oversizings may require rebate or recoupment arrangements
for the benefit of the developer.
3. Water Transmission and Sanitary Sewer Interceptors: The Applicant is
investigating options for the development of water transmission and sanitary
sewer systems to serve the Property and how they may be integrated with
systems already planned for the surrounding area.
4. Police, Fire, and Other City Services: Police protection will be provided by
the City of Fort Lupton. Fire protection will be provided by the Fort Lupton
Fire Protection District, pending inclusion of the subject property into the fire
protection district. Impact fees to offset municipal services expansion will be
set forth in the Annexation Agreement and in a P.U.D. Developer's
agreement.
5. Water Distribution and Sewer Collection: The Applicant will cause the
installation of water distribution and sewer facilities within the boundaries of
the Property.
6. Storm Drainage: The Applicant intends to provide on site detention for
storm drainage in accordance with City of Fort Lupton approved standards.
7. Public Lands / Open Space: The dedication of public lands by the Applicant
will be described in the PUD Plans for the Property as approved by the City.
The Applicant plans to meet or exceed the City's current parks and open space
dedication standards.
8. Public Facility Extension: The applicant has the obligation to develop and
install all on-site and off-site transmission infrastructure facilities necessary to
serve the annexed property with water, wastewater, and stormwater facilities
and services. Off-site utility service transmission facilities costs and certain
on-site infrastructure facility costs may be subject to (a) recoupment
provisions from other adjacent and benefiting property owners and/or(b) upon
review and approval of the City, a rebating to the Applicant of a portion of the
water and wastewater plant investment fees. The City will consider the rebate
of a portion of the water and wastewater plant investment fee to the extent (a)
the infrastructure item for which the rebate is sought is an item which is
normally included in the City's plant investment fee and (b) to the extent the
City, in its sole discretion, determines that there is a system wide funding
surplus available for rebate.
(d) The extension of municipal services to the annexed property and the development
of future water, sewer, and stormwater infrastructure within the Property, shall be
accomplished by one or more of the following Financing Methods:
1. Development Fees and Surcharges collected by the City of Fort Lupton
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2. Direct Developer Financing
3. Metropolitan District
4. Special Improvement Districts
5. Otherwise by agreement between City and the Developer as deemed
appropriate.
(e) Consistent with C.R.S. 31-12-108.5, the following Districts and all taxing entities
are identified with the current 2005 property tax mill levy.
(1) The project's impact on the Weld County RE-8 Fort Lupton School District, in
terms of the number of students to be generated by the project at full development,
is as follows:
Elementary School: 309 students
Middle School: 155 students
High School: 166 students
*Based on 954 dwelling units.
In accordance with City of Fort Lupton Fee Schedule the Applicant will
comply concerning fair contributions for the public schools with the
current assessment fees for each dwelling unit. These fees will be paid
directly to the appropriate school district and a letter from the school
district must be presented to the Building Department before the building
permit will be issued.
Attachments:
Map #1: Cottonwood Greens Annexation Vicinity Map
Map #2: Cottonwood Greens Annexation Plat
Map #3: Cottonwood Greens Annexation Master Plan
Map#4: Cottonwood Greens Annexation Preliminary Utility Plan
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211 N. PUBLIC ROAD SUITE 200
LAFAYETTE, CO. 80120
Annexation CO CD PHONE: 303-664-5301
FAX:303-664-5313
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Consulting Engineers & Scientists
r
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
PROPOSED MIXED-USE DEVELOPMENT
COTTONWOOD GREEN PUD
PARCEL NO. 1 (127 ACRES)
WELD COUNTY, COLORADO
TERRACON PROJECT NO. 25005427
Revised - February 22, 2001
Prepared for:
_ Cottonwood Greens Inc.
c/o Cimarron Consultants, Inc.
6551 South Revere Parkway, Suite 265
Englewood, Colorado 80111
Attn: Mr. Karl Kasch
Prepared by:
Terracon
_ 10625 West 1-70 Frontage Road North, Suite 3
Wheat Ridge, Colorado 80033
Phone: (303) 423-3300
Fax: (303) 423-3353
• 1rerracon_
Form 101-107
Revised - February 22, 2001 1 Terracon
Consulting Engineers 8 Scientists
Cottonwood Greens Inc. Terracon Consultants. Inc.
Go Cimarron Consultants, Inc. 10625 West I-70 Frontage Road North, Suite 3
6551 South Revere Parkway, Suite 265 Wheat Ridge, Colorado 80033
Englewood, Colorado 80111 Phone 303.423.3300
Fax 303.423.3353
www.terracon.corn
Attn: Mr. Karl Kasch
Re: Preliminary Geotechnical Engineering Report
Proposed Mixed-Use Development
Cottonwood Green PUD
Parcel No. 1 (127 Acres)
Weld County, Colorado
Terracon Project No. 25005427
Terracon has completed a preliminary geotechnical engineering exploration for the
proposed project to be located near the southeast corner of 14th Street and Weld County
Road No. 29 in Weld County, Colorado. This study was performed in general accordance
with our proposal number D2500620 revised December 18, 2000.
The results of our engineering study, including the Boring Location Map, laboratory test
results, Logs of Borings, and the preliminary geotechnical recommendations needed to aid
in the design and construction of foundations and other earth connected phases of this
project are attached. The accompanying geotechnical report presents our findings and
preliminary recommendations concerning the design and construction of foundations and
general site development. Further details are provided in this report.
The surface and subsurface soils consisted primarily of sand with varying amounts silt and
clay with some areas of lean clay with varying amounts of sand. Claystone and sandstone
bedrock were generally encountered beneath these soils at depths ranging from about 2 to
22-'/4 feet below existing site grade, and extended down to the full depth of exploration.
Bedrock was encountered at the ground surface in one boring and was not encountered to the
full depth of exploration in several of the borings. Our experience in the area and laboratory
testing for this study indicates that the clay soils and claystone bedrock at shallow depths
should be considered moderately to very highly expansive. The sands and sandstone bedrock
are considered non-to low expansive.
Groundwater was encountered in the majority of our initial borings at depths ranging from
about 2 to 14 feet below existing site grade during drilling operations. When checked several
days after drilling, groundwater was encountered in these borings at depths ranging from
about 1 to 19 feet below existing site grade. Groundwater was encountered in the majority of
the groundwater monitoring borings (piezometers), at depths ranging from about 5 to 6 feet
below existing site grade. When checked three days after drilling, groundwater was measured
^. in each of the piezometers at depths ranging from about '/ to 10 feet below existing site
Delivering Success for Clients and Employees Since 1965
More Than 70 Offices Nationwide
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
grade. We anticipate that the existing Fulton Ditch, located along the eastern and a portion of
the southern boundaries of the site, is a likely source for the water encountered beneath the
site. Interceptor drains or cutoff walls could be used to collect this potential leakage and divert
it elsewhere on the site. In addition, underdrain systems could be used in areas of shallow
groundwater to aid in site development. In some areas, underdrain systems may make
basement construction more feasible. Details regarding site dewatering are presented in
subsequent sections of this report.
Based upon the results of the field exploration and laboratory testing for the project, it is
anticipated that foundations consisting of grade beams and straight-shaft piers drilled into
bedrock will be appropriate in areas where claystone bedrock is encountered at shallow
depths. Spread footing foundations will likely be acceptable in areas where low to moderately
expansive materials are encountered at or near foundation bearing elevation or where a
significant amount of fill is placed to raise site grade. Post-tensioned slab foundations can
also be considered as an alternative foundation system for support of some of the planned at-
^
grade structures.
Slab-on-grade construction is considered acceptable only when bearing on non- to low
expansive materials; therefore, where moderately to highly expansive materials are
encountered at shallow depths on the site, the use of structural floor systems will likely be
required for basement construction for the residential structures. Removal and replacement of
moderately to highly expansive materials and the use of slab-on-grade floor systems will likely
be required for slab-on-grade use in commercial structures, provided some risk of movement
can be tolerated.
Supplementary geotechnical engineering exploration should be performed for each
_ proposed structure at the site when mass grading operations are complete or final design
plans become available. Supplemental geotechnical explorations will be used to confirm or
modify the recommendations contained in this preliminary report.
Preliminary pavement sections are presented in the report based upon the clayey soils.
A final pavement design will need to be completed for each public roadway within each
phase of the development. This will include supplemental geotechnical exploration as
required by the City of Fort Lupton, subsequent to mass grading operations, to confirm or
modify the preliminary pavement thickness alternatives. Accordingly, the actual thickness
may vary from those outlined in this report, based on the actual subsurface conditions
encountered along each proposed alignment.
di
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
We appreciate the opportunity to be of service to you on this phase of your project. If you
have any questions concerning this report, or if we may be of further service to you, please
do not hesitate to contact us.
Sincerely,
TERRACON "oo REpier.
" • '
.� � .�in
Prepared by: `r : Reviewed by:
3;7 ••fig
eiONALer
Andrew J. arner, P.E. Michael E. Anderson, P.E.
Staff Engineer Geotechnical Department Manager
Copies to: Addressee (6)
iv
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
TABLE OF CONTENTS
Page No.
Letter of Transmittal ii
INTRODUCTION 1
PROPOSED CONSTRUCTION 1
SITE EXPLORATION 2
Field Exploration 2
Laboratory Testing 3
SITE CONDITIONS 4
SUBSURFACE CONDITIONS 4
Geology 4
Soil and Bedrock Conditions 4
Field and Laboratory Test Results 5
Groundwater Conditions 5
ENGINEERING ANALYSIS AND PRELIMINARY RECOMMENDATIONS 6
Geotechnical Considerations 6
Foundation Systems 7
Spread Footings 7
Drilled Piers 8
Post-Tensioned Slabs 9
Basement Construction 10
Lateral Earth Pressures 11
Seismic Considerations 11
Floor Slab Design and Construction 12
Preliminary Pavement Design and Construction 13
Earthwork 16
General Considerations 16
Site Preparation 16
.. Subgrade Preparation 17
Fill Materials and Placement 17
Slopes 19
Shrinkage 19
Excavation and Trench Construction 19
Additional Design and Construction Considerations 20
Exterior Slab Design and Construction 20
Underground Utility Systems 20
Corrosion Protection 20
Surface Drainage 20
GENERAL COMMENTS 21
V
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
TABLE OF CONTENTS (Cont'd)
Figure No.
BORING LOCATION MAP 1
APPENDIX A: LOGS OF BORINGS
APPENDIX B: LABORATORY TEST RESULTS
APPENDIX C: GENERAL NOTES
^
vi
PRELIMINARY GEOTECHNICAL ENGINEERING REPORT
PROPOSED MIXED-USE DEVELOPMENT
COTTONWOOD GREEN PUD
PARCEL NO. 1 (127 ACRES)
WELD COUNTY, COLORADO
TERRACON PROJECT NO. 25005427
Revised - February 22, 2001
INTRODUCTION
This report contains the results of our preliminary geotechnical engineering exploration for the
proposed project to be located near the southeast corner of 14th Street and Weld County
Road No. 29 in Weld County, Colorado. The majority of the site is located in the southwest
quarter of Section 33, Township 2 North, Range 66 West of the 6th Principal Meridian.
Portions of the site also lie in the eastern one-half of Section 33 as well.
The purpose of these services is to provide information and preliminary geotechnical
engineering recommendations relative to:
• subsurface soil and bedrock conditions;
• groundwater conditions;
• foundation design and construction;
• basement construction;
• lateral earth pressures;
• floor slab design and construction;
• pavement design and construction;
• earthwork; and
• drainage.
The conclusions and preliminary recommendations contained in this report are based upon
the results of field and laboratory testing, engineering analyses, and experience with similar
soil conditions, structures and our understanding of the proposed project.
PROPOSED CONSTRUCTION
Based on information provided by Cimarron Consultants, Inc., the proposed project will
include the development of an approximate 127-acre parcel. As currently planned,
development may include the construction of single-family and multi-family residential
structures, and commercial structures.
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
—
We assume that the single-family residences will be one to two-story buildings utilizing
wood frame construction. We assume that basement construction will be incorporated into
the design of the residences where not limited by shallow groundwater conditions.
Maximum wall and column loads are assumed to be 2 to 3 kips per lineal foot and 30 to 50
kips, respectively.
We assume that the multi-family residences will be one to three-story buildings utilizing
wood frame construction. We assume that basement construction will not be incorporated
into the design of the residences. Maximum wall and column loads are assumed to be 3 to
5 klf and 50 to 80 kips, respectively.
We assume that the commercial buildings will be one to two-story buildings utilizing wood
frame, steel frame, and/or load bearing masonry walls. We assume that basement
construction will not be incorporated into the design of these structures. Wall and column
loads are assumed to be 2 to 5 klf and 30 to 80 kips, respectively.
Preliminary site grading plans were not available prior to preparation of this report. We
anticipate that mass grading operations will be required to bring the site to construction
grade, with maximum cut and fill depths less than about 20 feet.
Other site development will consist of the construction of asphalt concrete or Portland
cement concrete paved interior roadways and private parking areas/drives, along with the
installation of utilities.
SITE EXPLORATION
The scope of the services performed for this project included site reconnaissance by a field
engineer, a subsurface exploration program, laboratory testing and engineering analysis.
Field Exploration: A total of 21 test borings were drilled to depths of about 20 to 25 feet
below existing site grade at the approximate locations shown on the Boring Location Map,
Figure 1. The initial 11 borings (designated 1 through 11) for the geotechnical study were
drilled on December 29, 2000 and January 10 and 11, 2001. The additional 10 borings for
groundwater monitoring (piezometers, designated P1 through P10) were drilled on February 7,
2001 for the purposes of monitoring groundwater; slotted PVC pipe was placed in these
borings for subsequent groundwater measurement. All borings were advanced with a truck-
mounted drilling rig, utilizing 4-inch diameter solid stem and 6-inch diameter hollow stem,
continuous flight auger.
The boring locations were obtained by pacing from property lines or existing site features. The
ground surface elevation at each boring location was obtained from the P.U.D. Sketch Plan
2
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
provided. The accuracy of boring locations and elevations should only be assumed to the
level implied by the methods used.
Lithologic logs of each boring were recorded by the field engineer during the drilling
operations. At selected intervals, samples of the subsurface materials were taken by driving a
ring barrel or split-spoon sampler.
Penetration resistance measurements were obtained by driving the ring barrel or split spoon
sampler into the subsurface materials with a 140-pound hammer falling 30 inches. The
penetration resistance value is a useful index to the consistency, relative density or hardness
of the materials encountered.
Groundwater measurements were made in each initial boring at the time of site exploration
and several days after drilling. In addition, groundwater measurements were made three days
after drilling in the piezometers.
Laboratory Testing: All samples retrieved during the field exploration were returned to the
laboratory for observation by the project geotechnical engineer, and were classified in
accordance with the Unified Soil Classification System described in Appendix C. Samples of
bedrock were classified in accordance with the general notes for Rock Classification. At that
time, the field descriptions were confirmed or modified as necessary and an applicable
laboratory testing program was formulated to determine engineering properties of the
subsurface materials. Logs of Borings were prepared and are presented in Appendix A.
Selected soil and bedrock samples were tested for the following engineering properties:
• Water content • Expansion
• Dry density • Grain size
• Consolidation • Plasticity Index
• Water soluble sulfates
The significance and purpose of each laboratory test is described in Appendix C. Laboratory
test results are presented in Appendix B, and were used for the geotechnical engineering
analyses, and the development of preliminary foundation and earthwork recommendations.
_ All laboratory tests were performed in general accordance with the applicable ASTM, local or
other accepted standards.
.— SITE CONDITIONS
The majority of the site was vacant and bounded on the north by an existing agricultural
parcel, on the east and south by Fulton Ditch, and on the west by Weld County Road 29
3
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
(Northrup Avenue). Vegetation observed on the site consisted of a moderate growth of native
grasses, weeds and brush. Sparse clusters of trees were observed mainly located adjacent to
Fulton Ditch.
The ground surface was soft to moderately firm and sloped generally down to the north and
west. A maximum elevation differential of about 40 feet was estimated from the P.U.D.
Sketch Plan provided. Site drainage was generally in the form of surface sheet flow to the
north and west. A relatively small parcel containing oil storage tanks was observed within the
northeastern portion of the site. No evidence indicating the presence of underground utilities
was observed; however, we assume that there may be underground piping associated with
the oil storage tanks.
SUBSURFACE CONDITIONS
Geology: Surficial geologic conditions at the site, as mapped by the U.S. Geological Survey
(USGS) ('Colton, 1978), consist of eolium of Upper Pleistocene and Holocene ages and
colluvium of Upper Holocene age. These materials have been described as light brown to
tan windblown deposits of clay and silt (loess) and wind drifted sand. These materials, as
mapped in this area, are generally on the order of about 5 to 20 feet in thickness.
Bedrock underlying the surface units consists of the Denver and Arapahoe Formations of
Paleocene and Upper Cretaceous age. These formations within this area have been reported
to include sandstone, claystone and siltstone, interbedded within pebble conglomerate. The
thickness of these units has been reported on the order of 300 to 900 feet.
Due to the relatively flat and gently sloping nature of the site, geologic hazards at the site are
anticipated to be low. Seismic activity in the area is anticipated to be low and, from a
structural standpoint, the property should be relatively stable. With proper site grading around
proposed structures, erosional problems at the site should be reduced.
Soil and Bedrock Conditions: As presented on the Logs of Borings, surface and
subsurface soils consisted primarily of sand with varying amounts silt and clay with some
— areas of lean clay with varying amounts of sand. Claystone and sandstone bedrock were
encountered beneath these soils at depths ranging from about 2 to 2244 feet below existing
_ site grade, and extended down to the full depth of exploration. Bedrock was encountered at
the ground surface in one boring and was not encountered to the full depth of exploration in
several of the borings.
'Colton, Roger B., 1978, Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado, United States Geological Survey,
Map l-855-G.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
Field and Laboratory Test Results: Field test results indicate that the sand soils vary from
very loose to medium dense in relative density. The clay soils were stiff to very stiff in
consistency. The claystone and sandstone bedrock varies from weathered to hard in
hardness.
Our experience in the area and laboratory testing for this study indicate that the clay soils and
claystone bedrock at shallow depths should be considered moderately to very highly
expansive. The sands and sandstone bedrock are considered non- to low expansive. Water
soluble sulfate testing indicated values of 25 and 800 mg/L.
Groundwater Conditions: Groundwater was encountered in the majority of our initial borings
at depths ranging from about 2 to 14 feet below existing site grade during drilling operations.
When checked several days after drilling, groundwater was encountered in these borings at
depths ranging from about 1 to 19 feet below existing site grade. Groundwater was
encountered in the majority of the piezometers, at depths ranging from about 5 to 6 feet below
existing site grade. When checked three days after drilling, groundwater was measured in
each of the piezometers at depths ranging from about '%to 10 feet below existing site grade.
These observations represent only current groundwater conditions, and may not be indicative
of other times or at other locations. Groundwater levels can be expected to fluctuate with
varying seasonal, surface flows, and weather conditions.
We anticipate that the existing Fulton Ditch, located along the eastern and a portion of the
southern boundaries of the site, is a likely source for the water encountered beneath the site.
Based upon review of U.S. Geological Survey Maps (2Hillier, et al, 1979), regional
groundwater beneath the project area predominates in colluvial, landslide or windblown
materials, or in fractured weathered consolidated sedimentary bedrock located at a depth
near ground surface. Seasonal variations in groundwater conditions are expected since the
aquifer materials may not be perennially saturated. Groundwater is generally encountered
at depths ranging from 5 to 20 feet below ground surface; depth to seasonal groundwater is
generally 10 feet or less.
Terracon will perform subsequent groundwater measurements and issue additional
recommendations for dewatering (as required) in accordance with the scope of work
outlined in our proposal for the project.
2Hillier, Donald E. and Schneider, Paul A.,Jr., 1983, Depth to Water Table(1976-1977)In the Boulder-Fort Collins-Greeley
Area, Colorado, United States Geological Survey,Map I-855-I.
5
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
ENGINEERING ANALYSES AND PRELIMINARY RECOMMENDATIONS
�- Supplementary geotechnical engineering exploration should be performed for each
proposed structure at the site upon completion of initial design studies. Supplemental
geotechnical explorations will be used to confirm or modify the recommendations contained
in this preliminary report and provide final design criteria for residential construction.
Geotechnical Considerations: The site appears suitable for the proposed construction.
Based upon review of geologic maps and the results of the field exploration and laboratory
testing program, the clay soils and claystone bedrock which were encountered at relatively
shallow elevations in some of the borings are moderately to very highly expansive. These
expansive materials along with the shallow groundwater conditions encountered on portions of
the site will require particular attention in the design, development, and construction of the
proposed project.
As discussed, relatively shallow groundwater conditions were encountered on the site. The
shallower groundwater conditions are most predominant in the eastern and northern
portions of the site. Shallow groundwater conditions will likely inhibit basement construction
in some portions of the site currently planned for single-family residential use. As
discussed, groundwater monitoring in two of the proposed single-family residential parcels
will continue as presented in our proposal for the project. Based on recent groundwater
�— measurements in these areas, it is unlikely that the groundwater elevation will lower enough
for below grade construction unless site grades in these areas are raised significantly.
We anticipate that the existing Fulton Ditch, located along the eastern and a portion of the
southern boundaries of the site, is a likely source for the water encountered beneath the site.
Interceptor drains or cutoff walls could be used to collect this potential leakage and divert it
elsewhere on the site.
Consideration should be given to the installation of an underdrain system in conjunction with
the proposed sanitary sewer system, in order to collect and divert potential groundwater.
Depending upon the depth and location of the sewer trenches, groundwater may not be
collected from all impacted areas. Therefore, interceptor drains may also need to be
constructed within easements throughout the site. The additional interceptor drains should
be placed deep enough to reduce groundwater impact on basement construction on these
lots. Once these measures are implemented, additional exploration could be performed to
assess the feasibility of below ground or basement construction.
Non- to low expansive materials were encountered in the majority of the borings on the site.
In these areas and in areas where a significant depth of fill is placed over shallow claystone
bedrock, we anticipate that the use of spread footing foundations will likely be acceptable.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
.. Where the expansive claystone bedrock is encountered at relatively shallow elevations and
in cut areas, grade beams and straight shaft piers drilled into bedrock may be applicable for
support of the proposed structures. Post-tensioned slabs can also be considered as an
alternative for support of at-grade structures on the site, provided that the undisturbed
claystone bedrock is not located within about 5 to 7 feet of proposed slab subgrade
elevation. The post-tensioned slabs may be designed to bear on engineered fill comprised
of processed and moisture conditioned claystone bedrock.
As previously outlined, preliminary grading plans had not been developed at the time of this
investigation. We anticipate that maximum cut and fill depths will be on the order of about 20
feet. It is imperative that supplemental investigations be performed prior to design of
foundations for specific structures. Preliminary design criteria for the alternative foundation
systems are subsequently outlined.
Slab-on-grade construction is considered acceptable only when bearing on non- to low
expansive materials; therefore, where moderately to highly expansive materials are
encountered at shallow depths on the site, the use of structural floor systems will likely be
required for basement construction for the residential structures. Removal and replacement of
moderately to highly expansive materials and the use of slab-on-grade floor systems will likely
be required for slab-on-grade use in commercial structures, provided some risk of movement
can be tolerated.
Foundation Systems: Design and construction recommendations for alternate foundation
systems and other earth connected phases of the project are outlined below.
Spread Footings: In areas where non- to low swelling soils are encountered
subsequent to mass grading operations, spread footing foundations bearing upon
undisturbed subsoils, recompacted native soils, and/or engineered fill may be feasible
for support for the proposed structures. The footings may be preliminarily designed for a
maximum bearing pressure of 1,000 to 2,500 pounds per square foot (psf). The
preliminary design bearing pressures apply to dead loads plus design live load
conditions. The preliminary design bearing pressures may be increased by one-third
when considering total loads that include wind or seismic conditions.
Exterior footings should be placed a minimum of 36 inches below finished grade for frost
protection and to provide confinement for the bearing soils. Interior footings should bear
a minimum of 12 inches below finished grade. Finished grade is the lowest adjacent
grade for perimeter footings and floor level for interior footings.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
Footings should be proportioned to reduce differential foundation movement. For
preliminary design, proportioning to relative constant dead load pressure will also reduce
differential settlement between adjacent footings.
Footings, foundations, and masonry walls should be reinforced as necessary to reduce
the potential for distress caused by differential foundation movement. The use of joints
at openings or other discontinuities in masonry walls is recommended.
Drilled Piers: Due to the presence of moderately to very highly expansive clays and
shallow claystone bedrock on the site, a grade beam and drilled pier foundation system
can be considered applicable for support of the proposed structures. Straight shaft
piers, drilled a minimum of 6 to 10 feet into medium hard or harder bedrock, with
minimum shaft lengths of 18 to 20 feet can be used for preliminary design purposes.
For axial compression loads, piers may be designed for maximum end-bearing pressures
ranging from 20,000 to 30,000 pounds per square foot (psf), and skin friction values
ranging from 2,000 to 3,000 psf for the portion of the pier in medium hard or harder
bedrock.
It should be noted that thin lenses of lignite, a soft dark brown to black carbon-based
substance, have been encountered within the claystone bedrock formation in our studies
on nearby sites. Significant lenses of lignite may be encountered at or near pier bearing
depth. Piers that encounter the lignite strata must be extended through the lignite lens to
penetrate competent bedrock. The thickness of lignite lens should not be included when
calculating actual bedrock penetration of the pier.
To reduce potential uplift forces on piers, small diameter piers and long grade beam
spans, which increase individual pier loading, are recommended. A void space should be
provided beneath grade beams, between piers. The void material should be of suitable
strength to support the weight of fresh concrete used in grade beam construction and to
avoid collapse when foundation backfill is placed.
Drilling to design depths should be possible with conventional single flight power augers.
Shafts will probably remain open without stabilizing measures. However, pier concrete
should be placed soon after completion of drilling and cleaning. Due to potential
sloughing and raveling, foundation concrete quantities may exceed calculated geometric
volumes.
Post-Tensioned Slabs: Based on the soil conditions encountered, use of post-
tensioned slabs will be feasible for support of at-grade structures on the site. Post-
^ tensioned slabs should be preliminarily designed using criteria outlined by the Post-
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'— Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
Tensioning Institute3 based on the following for compressible or expansive conditions as
noted for sands/imported soils or clays/processed claystone bedrock, respectively:
• Maximum Allowable Bearing Pressure 1,000 to 2,500 psf
• Edge Moisture Variation Distance, em
• Center Lift Condition 5.5 feet
• Edge Lift Condition 2.5 feet
• Estimated Maximum Settlement (sands and imported soils) 1 to 1-1/2 inches
• Estimated Differential Settlement (sands and imported soils) % to1 inch
• Differential Soil Movement, ym (clays and processed claystone bedrock)
• Center Lift Condition 2 to 4 inches
• Edge Lift Condition 1 to 2 inches
• Slab-Subgrade friction coefficient, µ
• on polyethylene sheeting 0.75
• on cohesionless soils 1.00
• on cohesive soils 2.00
Post-tensioned slabs, thickened or turndown edges and/or interior beams should be
designed and constructed in accordance with the requirements of the Post-Tensioning
Institute (PTI) and the American Concrete Institute.
Post-tensioned slabs should not bear directly on undisturbed claystone bedrock, as
estimated differential movement values would likely be more than the allowable limits
presented in the PTI design methodology. It is recommended that post-tensioned slabs
bear a minimum of 5 to 7 feet above undisturbed claystone bedrock.
The above outlined differential soil movement values should also be considered as the
potential amounts for tilting of the structures, which could be caused by non-uniform and
significant wetting of the subsurface materials below the foundation, resulting in
potential differential movements.
Exterior slab edges should be placed a minimum of 36 inches below finished grade for
._ frost protection. Finished grade is the lowest adjacent grade for perimeter beams.
3 (1996), Design and Construction of Post-Tensioned Slabs-on-Ground Post-Tensioning Institute, Second
Edition.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
Basement Construction: Groundwater was encountered in the majority of our initial borings
at depths ranging from about 2 to 14 feet below existing site grade during drilling operations.
When checked several days after drilling, groundwater was encountered in these borings at
depths ranging from about 1 to 19 feet below existing site grade. Groundwater was
encountered in the majority of the piezometers, at depths ranging from about 5 to 6 feet below
existing site grade. When checked three days after drilling, groundwater was measured in
each of the piezometers at depths ranging from about '/to 10 feet below existing site grade.
The shallower groundwater conditions are most predominant in the eastern and northern
portions of the site. Shallow groundwater conditions will likely inhibit basement construction
in some portions of the site currently planned for single-family residential use. As
discussed, groundwater monitoring in two of the proposed single-family residential parcels
will continue as presented in our proposal for the project. Based on recent groundwater
measurements in these areas it is unlikely that the groundwater elevation will lower enough
for below grade construction unless site grades in these areas are raised significantly.
We anticipate that the existing Fulton Ditch, located along the eastern and a portion of the
southern boundaries of the site, is a likely source for the water encountered beneath the site.
Interceptor drains or cutoff walls could be used to collect this potential leakage and divert it
elsewhere on the site. Provided this is the source for the majority of the water, we anticipate
that there are several alternatives for decreasing or stopping the leakage from this source,
including lining the ditch and construction of cut-off walls and/or interceptor drains.
^ Consideration should be given to the installation of an underdrain system in conjunction with
the proposed sanitary sewer system, in order to collect and divert potential groundwater.
Depending upon the depth and location of the sewer trenches, groundwater may not be
collected from all impacted areas. Therefore, interceptor drains may also need to be
constructed within easements throughout the site. The additional interceptor drains should
be placed deep enough to reduce groundwater impact on basement construction on these
lots.
Full-depth basement construction is considered acceptable on portions of the site where
basement subgrade can be maintained a minimum of about 3 to 5 feet above existing
groundwater elevation. Based on current groundwater elevation measurements, this is most
likely to occur in the western portions of the site or in areas where significant amounts of fill
are placed to raise site grade.
Perched groundwater conditions could develop due to the shallow claystone bedrock beneath
the site and the irrigation practices associated with residential development. To reduce the
potential for groundwater entering the basement of the structure, installation of a perimeter
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
drain system will likely be required. The drainage system, at a minimum, should include an
exterior or interior perimeter drain system sloped to an appropriate outfall or sump.
In areas where the groundwater elevation is within about 3 to 4 feet of basement subgrade
elevation, a dewatering system consisting of an interior drain system and underslab
drainage layer will be required. Additional recommendations for dewatering systems will
depend on proposed site and basement elevations and subsurface conditions encountered
during supplemental geotechnical engineering explorations.
Lateral Earth Pressures: For soils above any free water surface, recommended preliminary
equivalent fluid pressures for unrestrained foundation elements are:
• Active:
Cohesive soil backfill (on-site clays) 40 to 55 psf/ft
Cohesionless soil backfill (on-site sands and processed sandstone) 30 to 45 psf/ft
On-site claystone bedrock not recommended for use
• Passive:
Cohesive soil backfill (on-site clays) 275 to 375 psf/ft
Cohesionless soil backfill (on-site sands and processed sandstone) 400 to 475 psf/ft
Shallow grade beam foundation walls 250 to 350 psf/ft
Drilled piers 400 to 500 psf/ft
Where the design includes restrained elements, the following preliminary equivalent fluid
pressures are recommended:
• At rest:
Cohesive soil backfill (on-site clays) 60 to 75 psf/ft
Cohesionless soil backfill (on-site sands and processed sandstone) 50 to 65 psf/ft
— On-site claystone bedrock not recommended for use
The lateral earth pressures herein are not applicable for submerged soils. Additional
recommendations may be necessary if such conditions are to be included in the design.
Seismic Considerations: The project site is located in Seismic Risk Zone I of the Seismic
Zone Map of the United States as indicated by the 1997 Uniform Building Code. Based
upon the nature of the subsurface materials, Soil Profile Type "Sc" should be used for the
design of structures for the proposed project (1997 Uniform Building Code, Table No. 16-J).
Floor Slab Design and Construction: Slab-on-grade construction is considered acceptable
only when bearing on non- to low expansive materials; therefore, where moderately to highly
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
expansive materials are encountered at shallow depths on the site, the use of structural floor
systems, supported structurally independent of the subgrade, is a positive means of
eliminating the potentially detrimental effects of floor movement and will likely be required for
basement construction for the residential structures. Removal and replacement of moderately
to highly expansive materials and the use of slab-on-grade floor systems will likely be required
for slab-on-grade use in commercial structures. If the owner is willing to accept the risk of
floor slab movement in these areas, overexcavation of the expansive materials to depths of
about 3 to 5 feet and replacement with non- to low expansive materials can reduce the risk
of floor slab movement.
To reduce potential slab movements, the subgrade soils should be prepared as outlined in the
"Earthwork" section of this report. Additional floor slab design and construction
recommendations for floor slabs are as follows:
• A minimum 1-1/2 to 2-inch void space should be constructed above, or below non-
bearing partition walls placed on the floor slab. Special framing details should be
provided at doorjambs and frames within partition walls to avoid potential distortion.
Partition walls should be isolated from suspended ceilings.
• Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns or utility lines to allow independent movement.
• Contraction joints should be provided in slabs to control the location and extent of
cracking as recommended by the American Concrete Institute (ACI).
• Interior trench backfill placed beneath slabs should be compacted in accordance
with recommended specifications outlined below.
• If moisture sensitive floor coverings are used on interior slabs, consideration should
be given to the use of barriers to minimize potential vapor rise through the slab.
• Floor slabs should not be constructed on frozen subgrade.
• Other design and construction considerations, as outlined in the ACI Design Manual,
Section 302.1R are recommended.
Preliminary Pavement Design and Construction: Preliminary Design of pavements for the
project have been based on the procedures outlined in "City of Fort Lupton- Standards and
Specifications"dated June 1994, referred to hereafter as the "Standards" and the Colorado
Department of Transportation (CDOT) specifications.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
Street classification and the recommended Equivalent Daily Load Application (EDLA) values
for the proposed roadways were presented in the Standards and are summarized below:
Roadway Classification EDLA
Minor Arterial 225
Major Collector 130
Minor Collector-Residential 50
Local Residential serving greater than 80 D.U. 20
Local Residential serving between 10 and 80 D.U. 10
Based upon AASHTO criteria, Colorado is located within Climatic Region VI of the United
States. This region is characterized as being dry, with hard ground freeze and spring thaw.
The spring thaw condition typically results in saturated or near-saturated subgrade soil
moisture conditions. The AASHTO criteria suggest that these moisture conditions are
prevalent for approximately 12-'/: percent of the annual moisture variation cycle.
Local drainage characteristics of proposed pavement areas are considered to vary from fair
to good depending upon location on the site. For purposes of this preliminary design
analysis, fair drainage characteristics are considered to control the design. These
characteristics, coupled with the approximate duration of saturated subgrade conditions,
result in a design drainage coefficient of 1.0 when applying the AASHTO criteria for design.
For preliminary flexible pavement design, a terminal serviceability index (SIt) of 2.0 was
utilized along with an inherent reliability of 80 percent for Local streets and an Slt of 2.5 with
a reliability 90 percent was used for design of Minor Arterial and Major Collector streets. A
design life of 20 years was used in the design. The preliminary design presented herein is
based on subgrade materials being comprised of the on-site soils. Using a correlated
design R-value of 20, appropriate EDLA, environmental criteria and other factors, the
structural numbers (SN) of the pavement sections were determined on the basis of the 1993
AASHTO design equation.
In addition to the preliminary flexible pavement design analyses, a preliminary rigid
pavement design analysis was completed, based upon AASHTO design procedures. Rigid
pavement design is based on an evaluation of the Modulus of Subgrade Reaction of the
soils (K-value), the Modulus of Rupture of the concrete, and other factors previously
outlined. The preliminary design K-value of 100 pci for the subgrade soil was determined by
correlation to the laboratory tests results. A modulus of rupture of 650 psi was used for
pavement concrete. The rigid pavement thickness for each traffic category was determined
on the basis of the AASHTO design equation.
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— Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
Preliminary alternatives for flexible and rigid pavements, summarized for each traffic area,
are as follows:
Preliminary Pavement Section Thickness (inches)
Traffic Alt.
Area Asphalt Aggregate Portland -
Concrete Base Cement Total
—
Surface Course Concrete
Local Residential A 6-'/z 6-%
— Streets serving B 4 8 12
between 10 and 80 DU C 5 5
Local Residential A 7 7
Streets serving greater B 4 10 14
than 80 DU
— C 5-'/: 5-'A
A 8 8
Minor Residential
—
Collector Streets B 5 10 15
C 6-'% 6-'%
— A 10 10
Major Collector Streets B 6-% 12 18-'/
— C 8 8
A 10-'/ 10-'/
Minor Arterial Streets B 7 12 19
—
C 8-'/z 8-1A
A final pavement design should be completed for each roadway with supplemental
geotechnical exploration as required by the City of Fort Lupton, subsequent to mass grading
operations, to confirm or modify the preliminary pavement thickness alternatives. The final
design will account for variations in the pavement subgrade soils within paved areas.
Accordingly, the actual thickness may vary from those outlined above. We anticipate that in
— many cases the designs will result in thinner sections due to the prevalence of sand soils on
the site.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
For preliminary analysis of pavement costs, the following specifications should be considered
for each pavement component:
Colorado Department of
Pavement Component Transportation Criteria
Asphalt Concrete Surface Grading C and CX or S and SX
Aggregate Base Course Class 5 or 6
Portland Cement Concrete Class P
Future performance of pavements constructed on the clay soils and claystone bedrock at
this site will be dependent upon several factors, including:
• maintaining stable moisture content of the subgrade soils and
• providing for a planned program of preventative maintenance.
Since the clay soils and claystone bedrock on the site have shrink/swell characteristics,
pavements could crack in the future primarily because of expansion of the soils when
subjected to an increase in moisture content to the subgrade. The cracking, while not
desirable, does not necessarily constitute structural failure of the pavement.
The performance of all pavements can be enhanced by minimizing excess moisture which
— can reach the subgrade soils. The following recommendations should be considered:
• use of on-site sands in fill areas within planned roadways;
• overexcavation of expansive claystone to a depth of 2 to 3 feet and replacement with
non- to low expansive materials during site grading;
• site grading at a minimum 2 percent grade away from the pavements;
• compaction of any utility trenches for landscaped areas to the same criteria as the
pavement subgrade;
• sealing all landscaped areas in or adjacent to pavements to minimize or prevent
moisture migration to subgrade soils;
• placing compacted backfill against the exterior side of curb and gutter; and
• placing curb, gutter and/or sidewalk directly on subgrade soils without the use of
base course materials.
Earthwork:
General Considerations: The following presents recommendations for site preparation,
excavation, subgrade preparation and placement of engineered fills on the project.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
All earthwork on the project should be observed and evaluated by Terracon. The
evaluation of earthwork should include observation and testing of engineered fill,
subgrade preparation, foundation bearing soils, and other geotechnical conditions
exposed during the construction of the project.
— Site Preparation: Strip and remove existing vegetation, debris, and other deleterious
materials from proposed building and pavement areas. All exposed surfaces should be
free of mounds and depressions which could prevent uniform compaction.
Stripped materials consisting of vegetation and organic materials should be wasted from
the site, or used to revegetate landscaped areas or exposed slopes after completion of
grading operations. If it is necessary to dispose of organic materials on-site, they should
be placed in non-structural areas and in fill sections not exceeding 5 feet in height.
The site should be initially graded to create a relatively level surface to receive fill, and to
provide for a relatively uniform thickness of fill beneath proposed building structures. If fill
is placed in areas of the site where existing slopes are steeper than 5:1
(horizontal:vertical), the area should be benched to reduce the potential for slippage
between existing slopes and fills. Benches should be wide enough to accommodate
compaction and earth moving equipment, and to allow placement of horizontal lifts of fill.
All exposed areas which will receive fill, once properly cleared and benched where
necessary, should be scarified to a minimum depth of 10 inches, conditioned to near
optimum moisture content, and compacted.
Although evidence of soft or low density fills or underground facilities such as septic
tanks, cesspools, basements, and utilities was not observed during the site
reconnaissance, such features could be encountered during construction. If unexpected
soft or low density fills or underground facilities are encountered, such features should
be removed and the excavation thoroughly cleaned prior to backfill placement and/or
construction.
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. Excavation penetrating the bedrock or cemented
soils may require ripping, jackhammering, and the use of specialized heavy-duty
equipment to facilitate rock break-up and removal.
Depending upon the final depth of excavation and seasonal conditions, groundwater will
likely be encountered in excavations in several areas on the site. Pumping from sumps
and/or interceptor drains may be utilized to control water within excavations. Well points
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. do Cimarron Consultants, Inc.
Terracon Project No. 25005427
may be required for significant groundwater flow, or where excavations penetrate
groundwater to a significant depth.
Based upon the subsurface conditions determined from the geotechnical exploration,
subgrade soils exposed during construction are anticipated to be relatively stable.
However, the stability of the subgrade may be affected by precipitation, repetitive
construction traffic or other factors. If unstable conditions develop, workability may be
improved by scarifying and drying. Overexcavation of wet zones and replacement with
granular materials may be necessary. Use of lime, fly ash, kiln dust, cement or
geotextiles could also be considered as a stabilization technique. Laboratory evaluation
is recommended to determine the effect of chemical stabilization on subgrade soils prior
to construction. Lightweight excavation equipment may be required to reduce subgrade
pumping.
The individual contractor(s) is responsible for designing and constructing stable,
temporary excavations as required to maintain stability of both the excavation sides and
bottom. All excavations should be sloped or shored in the interest of safety following
local and federal regulations, including current OSHA excavation and trench safety
standards.
Subgrade Preparation: Subgrade soils beneath interior and exterior slabs, and
beneath pavements should be scarified, moisture conditioned and compacted to a
minimum depth of 10 inches. The moisture content and compaction of subgrade soils
should be maintained until slab or pavement construction.
Fill Materials and Placement: Clean on-site soils or approved imported materials may
be used as fill material. The use of claystone bedrock as fill beneath structural or
pavement areas will may require the use of more costly foundation types, the use of
structural floor systems, thicker pavement sections or other mitigation prior to
construction. Imported soils (if required) should conform to the following:
Percent finer by weight
Gradation (ASTM C136)
6" 100
3" 70-100
No. 4 Sieve 50-100
No. 200 Sieve 35 (max)
• Liquid Limit 30 (max)
• Plasticity Index 15 (max)
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
• Maximum expansive potential (%)* 1.5
*Measured on a sample compacted to approximately 95 percent of the ASTM D698
maximum dry density at about 3 percent below optimum water content. The sample
is confined under a 100 psf surcharge and submerged.
Engineered fill should be placed and compacted in horizontal lifts, using equipment and
procedures that will produce recommended moisture contents and densities throughout
the lift. Recommended compaction criteria for engineered fill materials are as follows:
Minimum Percent
Material JASTM D698)
Scarified subgrade soils 95
On-site fill soils:
Beneath foundations (on-site clays) 95
Beneath foundations (sands or imported soils) 98
Beneath slabs 95
Beneath pavements 95
Miscellaneous backfill (non-structural areas) 90
_ On-site clay soils or processed claystone bedrock should be compacted within a
moisture content range of optimum to 4 percent above optimum. On-site sands and/or
imported soils should be compacted within a moisture range of 3 percent below to 3
percent above optimum unless modified by the project geotechnical engineer.
Slopes: For permanent cut slopes or slopes in compacted fill areas less than 20 feet in
height, recommended maximum configurations for on-site materials are as follows:
_ Maximum Slope
Material Horizontal:Vertical
Cohesive soils (on-site clays) 3:1
Cohesionless soils (on-site sands and imported soils) 2-Y2:1
Bedrock 2:1
If steeper slopes are required for site development, stability analyses should be
completed to design the grading plan.
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
The face of all slopes should be compacted to the minimum specification for fill
embankments. Alternately, fill slopes can be over-built and trimmed to compacted
material. If fill slopes greater than 20 feet in height are planned, Terracon should be
contacted to review the grading plans prior to construction
Shrinkage: For balancing grading plans, estimated shrink or swell of soils and bedrock
when used as compacted fill following recommendations in this report are as follows:
Estimated Shrink(-) Swell (+)
On-Site Material Based on ASTM D698
Sandy Clays +5 to -10%
Silty and Clayey Sands and Sandstone Bedrock -5 to -15%
Claystone +5 to +10%
Excavation and Trench Construction: Excavations into the on-site soils will encounter
caving soils and possibly groundwater, depending upon the final depth of excavation.
The individual contractor(s) should be made responsible for designing and constructing
stable, temporary excavations as required to maintain stability of both the excavation
sides and bottom. All excavations should be sloped or shored in the interest of safety
following local and federal regulations, including current OSHA excavation and trench
safety standards.
The soils to be penetrated by the proposed excavations may vary significantly across
the site. The soil classifications presented are based solely on the materials
encountered in widely spaced exploratory test borings. The contractor should verify that
similar conditions exist throughout the proposed area of excavation. If different
subsurface conditions are encountered at the time of construction, the actual conditions
should be evaluated to determine any excavation modifications necessary to maintain
safe conditions.
As a safety measure, it is recommended that all vehicles and soil piles be kept to a
minimum lateral distance from the crest of the slope equal to no less than the slope
height. The exposed slope face should be protected against the elements.
Additional Design and Construction Considerations:
Exterior Slab Design and Construction: Exterior slabs-on-grade, exterior architectural
features, and utilities founded on, or in backfill may experience some movement due to the
volume change of the backfill. Potential movement could be reduced by:
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Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
• minimizing moisture increases in the backfill;
• controlling moisture-density during placement of backfill;
• using designs which allow vertical movement between the exterior features and
adjoining structural elements; and
• placing effective control joints on relatively close centers.
Underground Utility Systems: All underground piping within or near the proposed
structure should be designed with flexible couplings, so minor deviations in alignment do
not result in breakage or distress. Utility knockouts in foundation walls should be
oversized to accommodate differential movements.
Where utilities are excavated below groundwater, temporary dewatering will be required
._ during excavation, pipe placement and backfilling operations for proper construction.
Utility trenches should be excavated on safe and stable slopes in accordance with
OSHA regulations as discussed above.
Corrosion Protection: Results of soluble sulfate testing indicate that ASTM Type II or
modified Type II Portland cement should be specified for all project concrete on and
below grade. Foundation concrete should be designed for moderate sulfate exposure in
accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4.
Surface Drainage: Positive drainage should be provided during construction and
maintained throughout the life of the proposed project. Infiltration of water into utility or
foundation excavations must be prevented during construction. Planters and other
surface features, which could retain water in areas adjacent to the building or pavements
should be sealed or eliminated. In areas where sidewalks or paving do not immediately
adjoin the structure, we recommend that protective slopes be provided with a minimum
grade of approximately 10 percent for at least 5 to 10 feet from perimeter walls. Backfill
against footings, exterior walls, and in utility and sprinkler line trenches should be well
compacted and free of all construction debris to reduce the possibility of moisture
infiltration.
Downspouts, roof drains or scuppers should discharge into splash blocks or extensions
when the ground surface beneath such features is not protected by exterior slabs or
paving. Sprinkler systems should not be installed within 5 feet of foundation walls.
Landscaped irrigation adjacent to the foundation system should be minimized or
eliminated.
GENERAL COMMENTS
20
Preliminary Geotechnical Engineering Report Terracon
Cottonwood Greens Inc. c/o Cimarron Consultants, Inc.
Terracon Project No. 25005427
Supplemental exploration and analyses should be undertaken in order to develop final
design parameters and to confirm and/or modify the preliminary recommendations and
conclusions contained in this report.
Terracon should be retained to review the final design plans and specifications so
comments can be made regarding interpretation and implementation of our geotechnical
recommendations in the design and specifications. Terracon also should be retained to
provide testing and observation during excavation, grading, foundation and construction
phases of the project.
The analysis and recommendations presented in this preliminary report are based upon the
data obtained from the borings performed at the indicated locations and from other
information discussed in this report. This report does not reflect variations which may occur
between borings or across the site. The nature and extent of such variations may not
become evident until construction. If variations appear, it will be necessary to reevaluate
the recommendations of this report.
The scope of services for this project does not include, either specifically or by implication,
any environmental assessment of the site or identification of contaminated or hazardous
materials or conditions. If the owner is concerned about the potential for such
contamination, other studies should be undertaken.
This preliminary report has been prepared for the exclusive use of our client for specific
application to the project discussed and has been prepared in accordance with generally
accepted geotechnical engineering practices. No warranties, either express or implied, are
intended or made. In the event that changes in the nature, design, or location of the project
as outlined in this report, are planned, the conclusions and recommendations contained in
this report shall not be considered valid unless Terracon reviews the changes, and either
verifies or modifies the conclusions of this report in writing.
21
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•1 APPROXIMATE BORING LOCATION
GPI APPROXIMATE PIEZOMETER BORING LOCATION NOT TO SCALE
FIGURE 1 BORING LOCATION MAP
FORT LUPTON NORTH
FORT LUPTON. COLORADO
PRWECT Meet 26602427 tlgWN JANUARY 26, 200I IN LOS 1 rem,
LOG OF BORING NO. 1 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
O J
}
DESCRIPTION = F F m aE i=
U C CC
W CC
a
F en`' w wF O O Z �u
m O 5J ,n
o_ y a O O J ¢p �' ZF "'a0x¢O
O Approx. Surface Elev.: 4965 ft O 2 2 o! m 3 o x m ae o J
SILTY SAND, fine grained, very loose, tan to medium brown, dry to wet
1 —SM 1 RS 12 6/12 8 104 -0.2/
_ 500psf
—SM 2 RS NR 5/12
5
10-
15
20-
- 25 4940 - -
25
Stopped boring at 25 feet
8
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 1-11-01
- WL 75 WD = 3 2/10/01 irrracon BORING COMPLETED 1-11-01
WL 2 Y RIG CME55 FOREMAN SF
WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 2 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m > ca w
U re W z F u- -'
S N W > Y1 K W Z Z Z Lu Q
0. S WZ
K m a 0 o �z >- O¢ co ZK¢
C9 Approx. Surface Elev.: 4966 ft o S 'z m (E3 o g y ae'6822
POORLY GRADED SAND, fine grained,with silt, very loose to loose, tan to light
brown, dry to wet 1
— SP 1 RS 12 5/12 4 97
- SP 2 RS 12 8/12 3 102 -0.9/
5 500psf
— SP 3 RS NR 7/12
10
4 =
4951
-' SILTY, CLAYEY SAND, fine to medium 15
grained, light to medium brown, wet
20—
/ 25 4941 —
25
Stopped boring at 25 feet
5
C,
z
8
Ui
w
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 1-11-01
WL Q 12 WD Y 2 2/10/01 1 t err acon RIG BORING COMPLETED
FOREMAN 1-11-01
SF
• WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 3 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
(f J
DESCRIPTION 5 w n W
_ cc z
T e_' Z F —F Q
o_ I—= N F-
ig W O H wI- D p2 N=
w O o_ w ¢O ¢'� Oct XODOQ r3 Approx. Surface Elev.: 4963 ft o S 2 o: m 3 0 o X DX ae o O cn
SILTY SAND, fine grained, very loose, tan —
to light brown, wet
SZ
—SM 1 RS NR 3/12
-SM 2 RS NR 6/12
5
-SM 3 SS NR 3/12
-- 10
1 -
•
•
15
20—
4938 25
Stopped boring at 25 feet
u
z
0
U
K
W
0 The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradua
WATER LEVEL OBSERVATIONS, ftBORING STARTED 1-10-01
WL 4 2 WD 11 2/10/01 ir BOerracon RIGR CME55 CO FOREMAN 1-10-01
SF
_ S WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 4 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m > w W
U c H H ?H ¢
EC z u- J
0.
O K W Z Z Z O
a U a U O IW-Z D OJz ziza
ra Approx. Surface Elev.: 4967 ft o o z W a o g o w p
PP > K mJ K zcO 30 n X �u a �mJ
SILTY SAND, fine to medium grained, dark -
-` 1.5 brown moist to wet ♦ 4965.5 -
SANDY LEAN CLAY, stiff, brown to black, — CL 1 RS 12 9/12 26 94
calcareous, petroleum odor, moist
- CL 2 RS 12 13/12 21 103
5
p,/./
o — CL 3 RS 12 15/12 18 110 +0.3/
/ — 500psf
%414 4953 -
SANDSTONE, fine to medium grained, 4 RS 12 30/0
hard to very hard, moderately to strongly 15
cemented, grey to orange brown, moist to -
wet —
— 5 RS NR 50/7
20
25 4942 - 6 SS 12 50/2
25
Stopped boring at 25 feet
0
K
W
ei The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 12-29-00
- g WL 71.5 WD 5 1/10/01 1lBOerracon RGRING COMPLETED
FOREMAN1229SF
m WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 5 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
9 DESCRIPTION m } ae w - w
C } cc w ,s z
_ Co K W z z Z
Q o W ❑
w o- w o a0 �� zt5 N :2?)2
o Approx. Surface Elev.: 4958 ft ❑ � z � o: m 3� ❑ � E m 4 o�y
SILTY SAND, fine grained, very loose to -
- loose, dark brown to medium brown, dry to
wet SM 1 RS 12 11/12 9 112
-SM 2 RS NR 5/12
5
2 -
10 4948 -SM 3 RS 12 21/12 17 101 +0.2/
CLAYSTONE, weathered to medium hard, 10 - 500psf
light to medium grey, iron staining, moist
— 4 RS 12 44/12
15
- 5 RS 12 50/9
20 4938 20
Stopped boring at 20 feet
0— 0 The stratification lines represent the approximate boundary lines
t between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 1-10-01
WL 2 7,5 WD WCI@16
ir
erracon RIG RING COMPLETE
FOREMAN 1-10-01
SF
WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 6 Page 1 of t
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
^ o J
DESCRIPTION m ae 5 z=
m >- cc w Z F LL(99 �¢
N w Z Z W
O >re w ❑
are
O a O ¢p ER z� N�Oz)p¢o Approx. Surface Elev.: 4966 ft ❑ D Z I- K m 3 O ❑ 8 g',7, O 0 u,J
SILTY SAND, fine to medium grained, —
loose, medium reddish brown, moist
SM 1 RS 12 10/12
3.5 4962.5
CLAYEY SANDSTONE, fine grained, 1
weathered to firm, weakly to moderately — 2 RS 12 24/12 14 114 +0.1/
cemented, orange brown, moist to wet, 5 — SOOpsf
interbedded with sandy claystone —
9 v 4957 —
CLAYSTONE, weathered to hard, light to 3 RS 12 31/12 17 113
dark grey, iron staining, moist 10
4 RS 12 50/12
15
20
25 4941 5 RS 8 50/8
25
Stopped boring at 25 feet
b
— oo The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 1-10-01• WL tu
o Q 9 WD s 4 1/10/01 lierracon RIG CME55OREMAN BORING CO F 1-10-01
WL SF
WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 7 Page 1 of 1
CLIENT
Fort Lupton North, LLC
.- SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m ae w w
ix =C cc
cc w
2 C N w w O (z� e'w Z Z Z uii O 2
^ a d O C I Iw-z 7 O reOw $ NOD
o EC
Approx. Surface Elev.: 4954 ft o z F- cr m 3 O ER Et; aREPASI
SILTY, CLAYEY SAND, fine to medium —
2 grained, medium brown, dry -
4952
LEAN CLAY, with sand, very stiff, grey to — CL 1 RS 12 25/12 9 105 +3.6/
13.5 yellow, mottled, dry to moist 4950.5 — 500psf
SILTY SAND, fine to medium grained, with SM 2 RS 12 25/12 6 120
claystone fragments, medium dense, light 5
6 brown, dry 4948 —
CLAYSTONE, medium hard to hard, light to —
dark grey, iron staining, moist
3 RS 12 50/12
10
4 RS 12 50/12
15
1 -
20-
^, _25 4929 25 - 5 RS 7 50/7
Stopped boring at 25 feet
8
LU
w
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 12-29-00
o WL Y a WL NONE WD Y 17 1/10/01 lerracon R GRING COCME55 FOREMANMPLETE 12-29-00SF
m W L APPROVED MEA JOB# 25005427,
LOG OF BORING NO. 8 Page 1 of 1
CLIENT
Fort Lupton North, LLC
p-. SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m > W
z= 7
U c W '_ Z F LL~ cc
^ Q 2 V) co > 0) e_W Z z z
a co co w o 3 Hz = Ow moo
CC
w CO a O ¢O >- - Z� *Has
o Approx. Surface Elev.: 4960 ft o S z m 3 o ER E w *o o w
e TO SANDY LEAN CLAY,
% grained,
3d, mediu
m dense, light brown, 4957
—SC 1 RS 12 31/12 7 107
CLAYSTONE, medium hard, tan to grey, —
^ dry to moist, varies to SANDSTONE with - 2 RS 11 50/11 11 115 +4.9/
depth 5
500psf
— 3 RS 12 50/12 3 100
10
^ 13.5 4946.5
CLAYSTONE, weathered to medium hard, 12 4 RS 12 23/12
grey, iron staining, moist to wet 15 —
1 —
20 4940 - 5 RS 9 50/9
20
Stopped boring at 20 feet
^
O
a
.� 0
O
W
'— o The stratification lines represent the approximate boundary lines
r between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 12-29-00— S WL o WL 2 14 WD Q 19 1/10/01 lierracon RIG BORING COMPLETED CME55 FOREMAN12-29-00SF
O WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 9 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
(J J
C c
DESCRIPTION r ale 0
_9 > W Z 2 z w
N W
2
woo
cc
O Approx. Surface Elev.: 4935 ft o S 2 Lt2 m o $ m ae O o u,J
%// CLAYEY SAND, fine grained, reddish
brown, moist
2
4933 —
CLAYSTONE, weathered to medium hard, — 1 RS 12 17/12 21 104 +3.1/
light to medium grey, iron staining, moist _ 500psf
— 2 RS 12 18/12 22 103
5
i
- 3 RS 12 25/12 23 101 +3.0/
10 500psf
— 4 RS 12 27/12
15
-20 4915 5 RS 10 50/10
20
Stopped boring at 20 feet
$
u The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 12-29-00
WL 4 NONE WD 6 1/10/01 ir rr acon RIG BORING COCME55 FOREMANMPLETE 12-29-00SF
$ WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 10 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
9 DESCRIPTION m } s z= ce
o
U c N W W Z Z z0 J OQ
S
a a U E ui O wz E Ow 250
LEI
ur M a w OJ ¢p >- iL NrrOerp
O Approx. Surface Elev.: 4935 ft o z r o: m 3 8 Ea Ern e o 8 m J
SILTY SAND, fine grained, very loose to —
loose, medium brown, dry
—SM 1 RS 12 13/12 4 107 -1.3/
500psf
—SM 2 RS NR 7/12
5
6.5 4928.5 -
CLAYEY SAND, fine grained, loose to —
medium dense, moist
- /10 y 4925 - SC 3 RS NR 32/12
10
SILTY SAND, fine grained, tan to light Q —
brown, moist to wet -
15-
20-
25 4910 25
Stopped boring at 25 feet
5
0
0
.... z
8
a
if,
— cx The stratification lines represent the approximate boundary lines
Xt between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 1-11-01
11 WD 10 2/10/01 rerracon R CME55OREMAN BORING CO F 1-11-01
WL Q SF
WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. 11 Page 1 of 1
CLIENT
Fort Lupton North, LLC
_ SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
O J C W
DESCRIPTION m >: •
w -
V m w -- z H -
E cc
LCF1 w o
o_ o_ O ¢O r•- ilk- Nmoo¢O
O Approx. Surface Elev.: 4946 ft o S z m 3 0 0 x D w 6e000_,
sILTY SAND, fine grained, loose, tan to —
medium brown, dry to wet
—SM 1 RS 12 9/12 8 116 -0.5/
' 500psf
—SM 2 RS NR 10/12
5
�- 10
15-
20-
22.5 4923.5 -
CLAYSTONE, grey to olive brown, moist —
25 4921 25
Stopped boring at 25 feet
5
b
K
H
The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 1-11-01
WL 2 6 WD 8 2/10/01 re rr acon R GRING COCME55 FOREMAN MPLETE 1-11-01
SF
° WL APPROVED MEA JOB# 25005427
.. m
.. LOG OF BORING NO. P 1 Page 1 of 1
CLIENT
Fort Lupton North, LLC
.- SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION °m y ae $ a w
c
U c )- ¢ w z -
..-. a !_- CO _co w 0 [MaOW (96.
re
W O a a W 2H NreOeap
<5 Approx. Surface Elev.: 4959 ft o S z m 3 O O 8 m ae o o m
SILTY SAND, fine to medium grained, light =to medium brown, moist to wet —
V 5
10
15
^ >20 4939 20
Stopped boring at 20 feet
0
0
0
i
8
- The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
g- WL 5 WD 1 2/10/01 ir BOCOMPLETED
D2-7-01
W 7 e CME55 FOREMAN SF
$ WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 2 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m y Cl
9 c W S H F ZF K
f CO W > C CC W Z Z z 1Uis1I Q
••••• a > Dw ❑
ce w 0 o_ w OI ¢0 cc.- z� Ncc OD¢p
Approx. Surface Elev.: 4961 ft ❑ z o m o ❑ b o w ae o o o
SILTY SAND, fine to medium grained, light -
brown to grey, dry to wet
1 _
_ S 5_
t0_
• 15
20 4941
20
Stopped boring at 20 feet
5
u
8
cc
s
w
0 The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
- g WL 5 WD 2 2/10/01 1 rerr acon RIG BORING COMPLETE
FOREMAN 2-7-01
SF
to
WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 3 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m }cc ae a "a w
Q.
o- a CNi CO O 5 uffi z c zz wo
ur a w ¢O �� z� c, ZOt<
O Approx. Surface Elev.: 4964 ft o z ¢ m 3 0 o 5. mu) aR O o w
SILTY SAND, fine to medium grained, —
medium brown, moist to wet —
1
Q 5-
10
15-
20 4944 20
Stopped boring at 20 feet
s
O
z
8
u,
w
0 The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
IWATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
o WL Y 5 WD Y 2.5 2/10/01 re rr acon RIG BORING
GRING COCME55 FOREMAN MPLETE 2 7 SF
011 WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 4 page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m ae w -
z= c7
_ ai w z z wz UJ 6
m w OO S wH D Ow ≥ woo
ce
w y a w ¢O ¢ - oft N¢ODO
O Approx. Surface Elev.: 4970 ft 0 S' z o: m 3 O X D m ae o o m
CLAYEY SAND, fine to medium grained,
trace to with organics, dark brown to black,
% moist
4 - 4966 SILTY SAND, fine to medium grained, tan
to grey, moist to wet - s-
•
.- 10-
15-
16 4954
^ CLAYSTONE, grey to olive brown, iron -
staining, moist
20 4950 20
Stopped boring at 20 feet
—
z
- 8
w
— The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
- WL 4 5 WD = 4 2/10/01 irerracon BORING COMPLETED 2-7-01
d WL Q RIG CME55 FOREMAN SF
03 WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 5 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m > z scc
Y K W wn Z f- W O
Q H Z gm
0 CO W O 5 LC 7 Ow worm
a W N 7 d O Qp �� Z� y=op°
o Approx. Surface Elev.: 4970 ft o 7 z ¢ m 3 o o a. Du) s o co
CLAYSTONE, olive brown to yellow brown, —
iron staining, moist
5-
10-
15
.20 4950 20
Stopped boring at 20 feet
5
O
O
8
W
H
- 23 The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
NONE WD 10 2/10/01 [err aconBO RGRING COMPLETE 2-7-01
WL CME55 FOREMAN SF
m WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 6 page 1 of 1
CLIENT
Fort Lupton North, LLC •
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
^ ° J
DESCRIPTION m >:c Wtit
-
w= O CC_ O C >- r W C Z $ Lilo J Th
m
D W O
F co � KW O2
W N it ccea
a W -OJ ¢O cer Z� NreOD0(7 Approx. Surface Elev.: 4964 ft o Z) z o: m 5O O I£ Do ae o O co J
SILTY SAND, fine to medium grained, —
medium brown, dry to moist
- 3.5 4960.5
CLAYSTONE, orange brown to olive brown,i —
moist —
5-
10-
15—
^ 20 4944
20
Stopped boring at 20 feet
0-0
2
0
U
c°� The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
^ WL ? NONE WD ? 4 2/10/01 1racon err BORING COMPLETED 2-7-01
w WL $ s RIG CME55 FOREMAN SF
m WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 7 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m y aceo=te o
_ = C CO W W C Z Z W 0 -w O Q
a a CO w O Wz D Ow 5 000
Lai
o. 0 2, ¢p �� z� N¢8A2
O Approx. Surface Elev.: 4963 ft 0 z r. m 3 0 0 a Do) ae o o co
SILTY SAND, fine to medium grained, light =to medium brown, moist to wet —
5
4 _
�— 10-
15
20 4943 20
Stopped boring at 20 feet
O
0
_ zz— d
u:
w
r
0 The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradual.
WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
WL 2 6 WD 1 2/10/01 % BOrr acon R GRING COCME55 FOREMAN MPLETE 2-7-01
SF
111
_ m WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 8 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton,Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m > ae w W
g re
2= 0
Z ♦2 La- Lu CQ
N W 2 2
a I- Lu U o
ce W y a o OJ a0 >- re U� NZODOO
Approx. Surface Elev.: 4965 ft o Lg 2 rr m 3 0 0 $ D m ae o o m
SILTY SAND, flne to medium grained, tan t —
brown to light brown, moist to wet
5
V
10-
15
20 4945
20
Stopped boring at 20 feet
_
8
— s: The stratification lines represent the approximate boundary lines
between soil and rock types: in-situ,the transition may be gradua
WATER LEVEL OBSERVATIONS, ftBORING STARTED 2-7-01
WL 2 6 WD 0.5 2/10/01 ir BOe rr acon R GRING COMPLETED
FOREMAN 2-7-01
7 SF
m WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 9 Page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m } ae W=
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CLAYEY SAND, fine grained, with organics,- —
dark brown, moist
2.5 4964.5 —
SILTY SAND, fine to medium grained, grey to medium brown, moist to wet
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u The stratification lines represent the approximate boundary lines
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3yT{ WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
$ WL ? 5 WD - 0.5 2/10/01 ir erracon BORING COMPLETED 2-7-01
WL 4 Y RIG CME55 FOREMAN SF
2 WL APPROVED MEA JOB# 25005427
LOG OF BORING NO. P 10 page 1 of 1
CLIENT
Fort Lupton North, LLC
SITE PROJECT
Fort Lupton, Colorado Fort Lupton North
SAMPLES TESTS
DESCRIPTION m } a2 w
re s 2=
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The stratification lines represent the approximate boundary lines
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WATER LEVEL OBSERVATIONS, ft BORING STARTED 2-7-01
- WL 4 5 WD ? 0.5 2/10/01 ir acon BORING COMPLETED 2-7-01
WL Y RIG CME55 FOREMAN SF
WL APPROVED MEA JOB# 25005427
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h_ Project: Fort Lupton North
i ie rr actin I Site: Fort Lupton, Colorado
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—
Date: 1-25-01
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er
1 Derr acon Site. Fort Lupton North
ocn ' Site: Fort Lupton, Colorado
o I Job#: 25005427
Date: 2-9-01
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z11 �L�«a`On S Fort Lupton No th
o Site: Fort Lupton, Colorado
g Job#: 25005427
— O Date: 1-26-01
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Project: Fort Lupton North
1 ierracon Site Fort Lupton, Colorado
— o Job#: 25005427
u Date: 1-25-01
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cr
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— I-- Date: 1-25-01
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1 ie rr acon 1 Project: Fort Lupton North
o ' Site: Fort Lupton, Colorado
o Job#: 25005427
O Date: 2-9-01
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,- Project: Fort Lupton North
1 rerracon Site: Fort Lupton, Colorado
o Job#: 25005427
2 Date: 1-25-01
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CONSOLIDATION TEST
1 to rr acon I Project Fort Lupton North
Site: Fort Lupton, Colorado
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u i Date: 1-25-01
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- CONSOLIDATION TEST
Project: Fort Lupton North
o i ie«acon 1 Site: Fort Lupton, Colorado
o Job#: 25005427
O Date: 1-25-01
U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS I HYDROMETER
4 2 1 1/2 3 6 10 16 30 50 100 200
6 3 1.5 3/4 3/8 4 8. 14 20 40 60 140
100 11 : HI ! 1 II : ' l
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GRAIN SIZE IN MILLIMETERS
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Specimen Identification t Classification LL I PL PI I Cc Cu
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- - GRAIN SIZE DISTRIBUTION
Lu Project: Fort Lupton North
Q l ierr aron Site: Fort Lupton, Colorado
I Job#: 25005427
o Date: 2-9-01
U.S.SIEVE OPENING IN INCHES I US.SIEVE NUMBERS I HYDROMETER
6 4 3 2 1.5 1 3/4 1/23/8 3 4 6 810 1416 20 30 40 50 60 100140200
... 100 ' I I ! I IF III I I •iT I 11 !
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medium fine
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N Project: Fort Lupton North
1 ierracon site:
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Job#: 25005427
O Date: 2-9-01
..-
U.S.SIEVE OPENING IN INCHES I U S.SIEVE NUMBERS I HYDROMETER
4 2 1 1/2 3 6 10 16 30 50 100 200
6 3 1 5 3/4 3/8 4 8 14 20 40 60 140
.-. 100 I I I I ' rill I I I Y•..I III� I I I I
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n 1 ierracon Project: Fort Lupton North
z I Site: Fort Lupton, Colorado
u ' Job#: 25005427
— ° I Date: 2-9-01
U.S.SIEVE OPENING IN INCHES ! U.S.SIEVE NUMBERS I HYDROMETER
4 2 1 1/2 3 6 10 16 30 50 100 200
6 3 1.5 le 3/8 4 8 14 20 40 60 140
�.. 100 I 1 r-- •- 1•. I I , 1 I I f I I
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GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND
SILT OR CLAY
coarse fine coarse medium 1 fine
Specimen Identification Classification LL PL PI Cc Cu
• 5 9.0ft SILTY SAND(SM) NP NP NP
.-
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a •5 9.0ft I 19 0.182 ' 1.0 I 60.3 I 38.6
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s I—_ GRAIN SIZE DISTRIBUTION
Project: Fort Lupton North
1 ierr aeon Site: Fort Lupton, Colorado
w Job#: 25005427
O Date: 1-25-01
U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER
4 2 1 12 3 6 10 16 30 50 100 200
6 3 1.5 3/4 3/8 i 8 14 20 40 60 140
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GRAIN SIZE IN MILLIMETERS
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.I _.coarse fine coarse medium I fine
Specimen Identification Classification [ LL ' PL 1 PI I Cc I Cu
-
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Ir
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4.75 0.277 . . .9 I 13.1
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cc
GRAIN SIZE DISTRIBUTION
W Project: Fort Lupton North
1 rerracon Site: Fort Lupton, Colorado
Job#: 25005427
ri p I Date: 2-9-01
U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER
4 2 1 1/2 3 6 10 16 30 50 100 200
6 3 1.5 3/4 3/8 4 8 14 20 60 140
- 100 r 11 I I 1' I 1 1 1
95
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lit
GRAIN SIZE IN MILLIMETERS
' COBBLES GRAVEL SAND SILT OR CLAY
- coarse fine coarse medium , fine ;fine ;
Specimen Identification Classification LL PL PI Cc ! Cu
• 8 2.0ft CLAYEY SAND(SC) 1 29 14 15
I.
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0 •1'I 8 2.0ft 0.425 I 0.108 0.0 50.5 49.5
cc
cr
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a GRAIN SIZE DISTRIBUTION
1 ierr acon Project: Fort Lupton North
z Site:: Fort Lupton, Colorado
w
Job#: 25005427
o Date: 1-25-01
U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER
6 4 3 2 1.5 1 3/4 1/23/8 3 6 810 1416 20 30 40 50 60 100140200
,,. 100 i I II I I IF -IS ,, III 1 I I I I I I
95 I .
90 ,
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80 . 1 [ I
75 I
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GRAIN SIZE IN MILLIMETERS
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COBBLES ' - SILT OR CLAY
coarse fine coarse medium Ifine j
Specimen Identification Classification ' LL PL PI Cc 1 Cu
•i 10 2.0ft SILTYSAND(SM) NP NP NP
e I —
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o • 10 2.0ft 4.75 0.192 , 0.0 i 66.3 33.7
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"s GRAIN SIZE DISTRIBUTION
Project: Fort Lupton North
1 terracon Site: Fort Lupton, Colorado
Job#: 25005427
f.
Date: 1-25-01
U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER
6 4 3 2 1.5 1 3/4 1/23/8 3 4 6 8 1014 16 20 30 40 5060 100140200
100 ! IF II III • Ij I I !I !
95 _
90 I Y�pp�pp.''' II
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80 � ,� � I 111 -
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100 10 1 0.1 1 0.01 0.001
GRAIN SIZE IN MILLIMETERS
COBBLES ' GRAVEL SAND SILT OR CLAY
,., coarse fine I coarse medium fine
Specimen Identification Classification LL PL PI Cc Cu
• 11 2.0ft SILTY SAND(SM) NP NP NP 1 I
--- __ _ -
-
Specimen Identification D100 _ D60 D30 D10 %Gravel I %Sand %Silt %Clay
— C • 11 2.0ft 2 0.251 0.108 0.0 83.0 17.0
0
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W _ _ __
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, __ __ __
GRAIN SIZE DISTRIBUTION
^. w Project: Fort Lupton North
1 ierracon Site: Fort Lupton, Colorado
Job#: 25005427
o Date: 1-25-01
-
I I I I I I I I I I I I I I I I I I
PHYSICAL PROPERTIES
PROPOSED WELD COUNTY NORTH MIXED-USE DEVELOPMENT
TERRACON PROJECT NO. 25005427
Boring Depth Soil Classification Particle Size Distribution,V. Atterberg Moisture-Density Relationship Specific Permeability Remarks
No. (ft) Passing by Weight Limits Gravity Corrected
3" #4 #10 #40 #200 LL PI Dry Optimum Method Dry K R-Value
Density Moisture Density Cm/Sec
(Pct) (%) (Pc1)
1 2 A-2-4(0)SM - - - 84 21 NV NP 2
2 4 A-3(0)SP-SM - - - 68 57 NV NP 2
3 0-25 A-4(0)SM - - - 85 37 NV NP 2
4 2 A-6(9)CL - - - - 66 33 18 3
4 9 A-6(11)CL - - - - 69 35 20 3
5 9 A-4(0)SM - 99 99 81 39 NV NP 2
6 2 A-2-4(0)SM - - - 75 13 NV NP 2
6 9 A-4(1)CL-ML - - - - 61 26 5 3
7 2 A-6(15)CL - - - - 74 39 23 3
6 2 A-6(4)SC - - - - 50 29 15 3
9 4 A-7-6(33)CL - - - - 98 49 31 3
10 2 A-2-4(0)SM - - - 82 34 NV NP 2
11 2 A-2-4(0)SM — — — 79 17 NV NP 2
REMARKS:
Classification/Particle Size Moisture-Density Relationship Specific Gravity Permeability R-Value
1. Visual 4. Tested ASTM D698/AASHTO T99 6. Minus#4 8. Constant Head 10. Expansion Pressure psf
2. Laboratory Tested 5. Tested ASTM D1577/AASHTO T180 7. Plus#4 9. Falling Head 11. Exudation Pressure 300 psi
3. Minus#200 Only
Note: NV= no value
NP= non-plastic
lierracon
I I I I I I I I I 1 1 I I I I I I I I
SOIL PROPERTIES
PROPOSED WELD COUNTY NORTH MIXED-USE DEVELOPMENT
TERRACON PROJECT NO. 25005427
Atterberg Water Soluble
Soil Property Expansion Unconfined Shear
Limits Matter, (mg/l)
Boring Depth Soil Compressive Strength Corrected
No. (ft) Classification Initial Dry initial Water Surcharge Expansion Strength C R-Value Remarks
Density Content(%) LL PI (ksf) (%) (psf) Deg. Salts Sulfates
(Pci)
1 2 SM 104 8 0.5 -0.2 3,4,5
2 2 SM 97 4 4,5
2 4 SM 102 3 0.5 -0.9 3, 4,5
3 0-25 SM - 25 4, 5
4 2 CL 94 26 4, 5
4 4 CL 103 21 - 800 4,5
4 9 CL 110 18 0.5 +0.3 3, 4,5
5 2 SM 112 9 4,5
5 9 101 17 0.5 +0.2 3,4
6 4 114 14 0.5 +0.1 3,4
6 9 113 17 4
7 2 CL 105 9 0.5 +3.6 3,4,5
Partially disturbed sample
-=Compression/settlement
Note: Initial Dry Density and Initial Water Content are in-situ values unless otherwise Noted.
Legend REMARKS
Shear Strength Test Method 1. Compacted density(approximately 95%of ASTM D698 maximum density at moisture content slightly below optimum).
DS-Direct Shear 2. Compacted density(approximately 95%of ASTM D1557 maximum density at moisture content slightly below optimum).
DS-Direct Shear(Saturated) 3. Submerged to approximate saturation.
UC-Unconfined Compression 4. Dry density and/or moisture content determined from one ring of a multi-ring sample.
UU-Unconsolidated Undrained 5. Visual Classification.
CU-Consolidated Undrained w/pore pressure
CU-Consolidated Undrained
CD-Consolidated Drained
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i
I 1 1 1 1 1 1 ) I 1 1 1 1 1 1 1 1 1 1
SOIL PROPERTIES
PROPOSED WELD COUNTY NORTH MIXED-USE DEVELOPMENT
TERRACON PROJECT NO. 25005427
Atterberg Water Soluble
Soil Property Expansion Unconfined Shear
Boring Depth Soil Limits Compressive Strength Corrected Matter,(mg/I)
No. (ft) Classification Initial Dry Initial Water Surcharge Expansion Strength C R-Value Remarks
Density a LL PI Salts Sulfates
(Pc
Content(/.) (ksf) (%) (psf) Deg.
7 4 SM 120 6 25 4, 5
8 2 SC 107 7 4,5
8 4 115 11 0.5 +4.9 3,4
8 9 100 3 4
9 2 104 21 0.5 +3.1 3,4
9 4 103 22 4
9 9 101 23 0.5 +3.0 3,4
10 2 SM 107 4 0.5 -1.3 3,4,5
11 2 SM 116 8 0.5 -0.5 3,4, 5
*=Partially disturbed sample
-=Compression/settlement
Note: Initial Dry Density and Initial Water Content are in-situ values unless otherwise Noted.
Legend REMARKS
Shear Strength Test Method 1. Compacted density(approximately 95%of ASTM D698 maximum density at moisture content slightly below optimum).
DS-Direct Shear 2. Compacted density(approximately 95% of ASTM D1557 maximum density at moisture content slightly below optimum).
DS-Direct Shear(Saturated) 3. Submerged to approximate saturation.
UC-Unconfined Compression 4. Dry density and/or moisture content determined from one ring of a multi-ring sample.
UU-Unconsolidated Undrained 5. Visual Classification.
CU-Consolidated Undrained w/pore pressure
CU-Consolidated Undrained
CD-Consolidated Drained
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GENERAL NOTES
DRILLING&SAMPLING SYMBOLS:
SS: Split Spoon - 1-3/8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger
ST: Thin-Walled Tube-2"O.D., unless otherwise noted PA: Power Auger
RS: Ring Sampler-2.42" I.D., 3"O.D., unless otherwise noted HA: Hand Auger
—
DB: Diamond Bit Coring-4", N, B RB: Rock Bit
BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary
—
The number of blows required to advance a standard 2-inch O.D. split-spoon sampler(SS)the last 12 inches of the total 18-
inch penetration with a 140-pound hammer falling 30 inches is considered the "Standard Penetration" or "N-value". For 3"
O.D. ring samplers (RS)the penetration value is reported as the number of blows required to advance the sampler 12 inches
using a 140-pound hammer falling 30 inches, reported as"blows per foot," and is not considered equivalent to the "Standard
Penetration" or"N-value".
WATER LEVEL MEASUREMENT SYMBOLS:
WL: Water Level WS: While Sampling
WCI: Wet Cave in WD: While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB: After Boring ACR: After Casing Removal
— Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at
other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of
groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-
term observations.
re
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained
Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles,
r. gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally
described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents.may be added as
modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to
gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of
_ their consistency.
•
FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK
Mal 1551 MI MI Relative LRS1 fial
Blows/Ft. Blows/Ft. Consistency Blows/Ft. Blows/Ft. Density Blows/Ft. Blows/Ft. Consistency
<3 <2 Very Soft 0-6 <3 Very Loose <30 <20 Weathered
3-4 2-3 Soft 7-18 4-9 Loose 30-49 20-29 Firm
5-9 4-6 Medium Stiff 19-58 10-29 Medium Dense 50-89 30-49 Medium Hard
—
10-18 7-12 Stiff 59-98 30-49 Dense 90-119 50-79 Hard
19-42 13-26 Very Stiff > 98 >49 Very Dense > 119 > 79 Very Hard
>42 >26 Hard
RELATIVE PROPORTIONS OF SAND AND GRAIN SIZE TERMINOLOGY
GRAVEL
Descriptive Terms of Percent of Major Component
— Other Constituents Dry Weight of Sample Particle Size
Trace < 15 Boulders Over 12 in. (300mm)
With 15—29 Cobbles 12 in. to 3 in. (300mm to 75 mm)
"— Modifier > 30 Gravel 3 in. to#4 sieve(75mm to 4.75 mm)
Sand #4 to#200 sieve(4.75mm to 0.075mm)
Silt or Clay Passing #200 Sieve(0.075mm)
RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION
—
Descriptive Terms of Percent of
Other Constituents Dry Weight Term Plasticity Index
Trace <5 Non-plastic 0
With 5-12 Low 1-10
Modifiers > 12 Medium 11-30
High 30+
— lierracan
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests^ Soil Classification
Group
Symbol Group Names
Coarse Grained Soils Gravels Clean Gravels Cu z 4 and 1 z Cc z 3E GW Well graded gravelF
More than 50%retained More than 50%of coarse Less than 5%finest fraction retained on Cu<4 and/or 1 >Cc>3E GP Poorly graded gravelF
on No.200 sieve No.4 sieve Gravels with Fines More Fines classify as ML or MH GM Silty gravelF.°•H
•—• than 12%fines°
Fines classify as CL or CH GC Clayey gravelF."
Sands Clean Sands Cu≥6 and 1 s Cc z 3E SW Well graded sand'
50%or more of coarse Less than 5%fines°
fraction passes Cu<6 and/or 1 >Cc>3E SP Poorly graded sand
No.4 sieve Sands with Fines Fines classify as ML or MH SM Silty sand°H'
More than 12%fines° Fines classify as CL or CH ani
SC Clayey sand
Fine-Grained Soils Silts and Clays inorganic PI>7 and plots on or above"A"lined CL Lean clayK.M
50%or more passes the Liquid limit less than 50
No.200 sieve PI<4 or plots below"A"lines ML SiltK4'"
organic Liquid limit-oven Organic clayK"
<0.75 OL
"'dried
Liquid limit-not Organic siltK4'A°
dried
Silts and Clays Inorganic PI plots on or above"A"line CH Fat clayKuM
Liquid limit 50 or more
,,... PI plots below"A"line MH Elastic silt"M
organic Liquid limit-oven dried Organic clay'""t°
<0.75 OH
Liquid limit-not dried Organic siltK"1AO
Highly organic soils Primarily organic matter,dark in color,and organic odor PT Peat
A Based on the material passing the 3-in.(75-mm)sieve "If fines are organic,add"with organic fines"to group name.
— a If field sample contained cobbles or boulders,or both,add"with cobbles or I If soil contains≥15%gravel,add'with gravel"to group name.
°boulders,or both"to group name. 'If Atterberg limits plot in shaded area,soil is a CL-ML,silty clay.
Gravels with 5 to 12%fines require dual symbols: GW-GM well graded K If soil contains 15 to 29%plus No.200,add"with sand"or"with
gravel with silt,GW-GC well graded gravel with clay,GP-GM poorly graded gravel,"whichever is predominant.
— gravel with silt,GP-GC poorly graded gravel with clay.
L°Sands with 5 to 12%fines require dual symbols: SW-SM well graded sand If soil contains≥30%plus No.200 predominantly sand,add"sandy"
with silt,SW-SC wellgraded sand with clay,SP-SM poorly to group name.
Y graded sand with MIf soil contains≥30%silt, SP-SC poorly graded sand with clay plus No.200,predominantly gravel,add
"gravelly"to group name.
ECu=Dee/Die Cc= (D'°) "PI≥4 and plots on or above"A"line.
2
010 x Del °PI<4 or plots below"A"line.
F If soil contains≥15%sand,add with sand"to group name. "PI plots on or above"A"line.
°If fines classify as CL-ML,use dual symbol GC-GM,or SC-SM. °PI plots below"A"line.
so I I
.„ For classification of fine-grained
soils and fine-grained fraction
50 —of coarse-grained soils Ica "' e
Equation of"A"-line / "p;�'�
d Horizontal at PI=4 to LL=25.5.
W 40 — then PI=0.73(LL-20) 0+
O Equation of"U"-line °t
Z Vertical at LL=16 to PI=7, G�
>-
30 "" then PI=0.9(LL-8) e
—
... U ON'
of 20 Cie
MHorOH
•.• 10
7
4 - -7. ML or OL
0 I
,.., 0 10 16 20 30 40 50 60 70 80 90 100 110
LIQUID LIMIT(LL) ierracon _
ROCK CLASSIFICATION
(Based on ASTM C-294)
Sedimentary Rocks
Sedimentary rocks are stratified materials laid down by water or wind. The sediments may be
composed of particles or pre-existing rocks derived by mechanical weathering, evaporation or by
chemical or organic origin. The sediments are usually indurated by cementation or compaction.
Chert Very fine-grained siliceous rock composed of micro-crystalline or cyrptocrystalline
quartz, chalcedony or opal. Chert is various colored, porous to dense, hard and
has a conchoidal to splintery fracture.
Claystone Fine-grained rock composed of or derived by erosion of silts and clays or any
rock containing clay. Soft massive and may contain carbonate minerals.
Conglomerate Rock consisting of a considerable amount of rounded gravel, sand and cobbles
with or without interstitial or cementing material. The cementing or interstitial
material may be quartz, opal, calcite, dolomite, clay, iron oxides or other
materials.
Dolomite A fine-grained carbonate rock consisting of the mineral dolomite [CaMg(CO3)2].
May contain noncarbonate impurities such as quartz, chert, clay minerals,
organic matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL).
Limestone A fine-grained carbonate rock consisting of the mineral calcite (CaCO3). May
contain noncarbonate impurities such as quartz, chert, clay minerals, organic
matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL).
Sandstone Rock consisting of particles of sand with or without interstitial and cementing
materials. The cementing or interstitial material may be quartz, opal, calcite,
dolomite, clay, iron oxides or other material.
Shale Fine-grained rock composed of-or derived by erosion of silts and clays or any
rock containing clay. Shale is hard, platy, of fissile may be gray, black, reddish
or green and may contain some carbonate minerals (calcareous shale).
Siltstone Fine grained rock composed of or derived by erosion of silts or rock containing
silt. Siltstones consist predominantly of silt sized particles (0.0625 to 0.002 mm
in diameter) and are intermediate rocks between claystones and sandstones and
may contain carbonate minerals.
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ROCK CLASSIFICATION
(Based on ASTM C-294)
Metamorphic Rocks
Metamorphic rocks form from igneous, sedimentary, or pre-existing metamorphic rocks in response to
changes in chemical and physical conditions occurring within the earth's crust after formation of the
original rock. The changes may be textural, structural, or mineralogic and may be accompanied by
^ changes in chemical composition. The rocks are dense and may be massive but are more frequently
foliated (laminated or layered) and tend to break into platy particles. The mineral composition is very
variable depending in part on the degree of metamorphism and in part on the composition of the
original rock.
Marble A recrystallized medium- to coarse-grained carbonate rock composed of calcite
or dolomite, or calcite and dolomite. The original impurities are present in the
form of new minerals, such as micas, amphiboles, pyroxenes, and graphite.
Metaquartzite A granular rock consisting essentially of recrystallized quartz. Its strength and
.. resistance to weathering derive from the interlocking of the quartz grains.
Slate A fine-grained metamorphic rock that is distinctly laminated and tends to split into
thin parallel layers. The mineral composition usually cannot be determined with
the unaided eye.
Schist A highly layered rock tending to split into nearly parallel planes (schistose) in
which the grain is coarse enough to permit identification of the principal minerals.
Schists are subdivided into varieties on the basis of the most prominent mineral
present in addition to quartz or to quartz and feldspars; for instance, mica schist.
Greenschist is a green schistose rock whose color is due to abundance of one or
more of the green minerals, chlorite or amphibole, and is commonly derived from
altered volcanic rock.
Gneiss One of the most common metamorphic rocks, usually formed from igneous or
sedimentary rocks by a higher degree of metamorphism than the schists. It is
characterized by a layered or foliated structure resulting from approximately
parallel lenses and bands of platy minerals, usually micas or prisms, usually
amphiboles, and of granular minerals, usually quartz and feldspars. All
intermediate varieties between gneiss and schist and between gneiss and
granite are often found in the same areas in which well-defined gneisses occur.
soma
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ROCK CLASSIFICATION
(Based on ASTM C-294)
^
Igneous Rocks
Igneous rocks are formed by cooling from a molten rock mass (magma). Igneous rocks are divided
into two classes (1) plutonic, or intrusive, that have cooled slowly within the earth; and (2) volcanic, or
extrusive, that formed from quickly cooled lavas. Plutonic rocks have grain sizes greater than
approximately 1 mm, and are classified as coarse- or medium-grained. Volcanic rocks have grain
sizes less than approximately 1 mm, and are classified as fine-grained. Volcanic rocks frequently
contain glass. Both plutonic and volcanic rocks may consist of porphyries that are characterized by the
presence of large mineral grains in a fine-grained or glassy groundmass. This is the result of sharp
changes in rate of cooling or other physico-chemical conditions during solidification of the melt.
Granite Granite is a medium- to coarse-grained light-colored rock characterized by the
presence of potassium feldspar with lesser amounts of plagioclase feldspars and
quartz. The characteristic potassium feldspars are othoclase or microcline, or
both; the common plagioclase feldspars are albite and oligoclase. Feldspars are
more abundant than quartz. Dark-colored mica (biotite) is usually present, and
light-colored mica (muscovite) is frequently present. Other dark-colored
ferromagnesian minerals, especially honblende, may be present in amounts less
than those of the light-colored constituents.
.— Quartz-Monzonite Rocks similar to granite but contain more plagioclase feldspar than potassium
and Grano-Diorite feldspar.
Basalt Fine-grained extrusive equivalent of gabbro and diabase. When basalt contains
natural glass, the glass is generally lower in silica content than that of the lighter-
colored extrusive rocks.
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LABORATORY TEST
SIGNIFICANCE AND PURPOSE
TEST SIGNIFICANCE PURPOSE
California Bearing Used to evaluate the potential strength of subgrade soil, Pavement Thickness
Ratio subbase, and base course material, including recycled Design
materials for use in road and airfield pavements.
Consolidation Used to develop an estimate of both the rate and amount Foundation Design
of both differential and total settlement of a structure.
Direct Shear Used to determine the consolidated drained shear strength Bearing Capacity,
of soil or rock. Foundation Design,
and Slope Stability
Dry Density Used to determine the in-place density of natural, Index Property Soil
inorganic, fine-grained soils. Behavior
Expansion Used to measure the expansive potential of fine-grained Foundation and Slab
soil and to provide a basis for swell potential classification. Design
Gradation Used for the quantitative determination of the distribution Soil Classification
of particle sizes in soil.
Liquid& Plastic Limit, Used as an integral part of engineering classification Soil Classification
Plasticity Index systems to characterize the fine-grained fraction of soils,
and to specify the fine-grained fraction of construction
materials.
Permeability Used to determine the capacity of soil or rock to conduct a Groundwater Flow
liquid or gas. Analysis
pH Used to determine the degree of acidity or alkalinity of a Corrosion Potential
soil.
Resistivity Used to indicate the relative ability of a soil medium to Corrosion Potential
carry electrical currents.
R-Value Used to evaluate the potential strength of subgrade soil, Pavement Thickness
subbase, and base course material, including recycled Design
materials for use in road and airfield pavements.
Soluble Sulphate Used to determine the quantitative amount of soluble Corrosion Potential
sulfates within a soil mass.
Unconfined To obtain the approximate compressive strength of soils Bearing Capacity
Compression that possess sufficient cohesion to permit testing in the Analysis for
unconfined state. Foundations
Water Content Used to determine the quantitative amount of water in a Index Property Soil
soil mass. Behavior
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REPORT TERMINOLOGY
(Based on ASTM D653)
Allowable Soil The recommended maximum contact stress developed at the interface of the foundation
Bearing Capacity element and the supporting material.
Alluvium Soil, the constituents of which have been transported in suspension by flowing water and
subsequently deposited by sedimentation.
.. Aggregate Base A layer of specified material placed on a subgrade or subbase usually beneath slabs or
Course pavements.
Backfill A specified material placed and compacted in a confined area.
Bedrock A natural aggregate of mineral grains connected by strong and permanent cohesive forces.
Usually requires drilling, wedging, blasting or other methods of extraordinary force for
excavation.
Bench A horizontal surface in a sloped deposit.
Caisson (Drilled A concrete foundation element cast in a circular excavation which may have an enlarged
Pier or Shaft) base. Sometimes referred to as a cast-in-place pier or drilled shaft.
Coefficient of A constant proportionality factor relating normal stress and the corresponding shear stress
Friction at which sliding starts between the two surfaces.
Colluvium Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of
a slope or cliff.
Compaction The densification of a soil by means of mechanical manipulation
Concrete Slab-on- A concrete surface layer cast directly upon a base, subbase or subgrade, and typically used
Grade as a floor system.
r- Differential Unequal settlement or heave between, or within foundation elements of structure.
Movement
Earth Pressure The pressure exerted by soil on any boundary such as a foundation wall.
ESAL Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000
pound axle loads).
Engineered Fill Specified material placed and compacted to specified density and/or moisture conditions
under observations of a representative of a geotechnical engineer.
Equivalent Fluid A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral
support presumed to be equivalent to that produced by the actual soil. This simplified
approach is valid only when deformation conditions are such that the pressure increases
linearly with depth and the wall friction is neglected.
Existing Fill(or Materials deposited throughout the action of man prior to exploration of the site.
Man-Made Fill)
Existing Grade The ground surface at the time of field exploration.
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REPORT TERMINOLOGY
(Based on ASTM D653)
Expansive The potential of a soil to expand (increase in volume) due to absorption of moisture.
Potential
Finished Grade The final grade created as a part of the project.
Footing A portion of the foundation of a structure that transmits loads directly to the soil.
Foundation The lower part of a structure that transmits the loads to the soil or bedrock.
Frost Depth The depth at which the ground becomes frozen during the winter season.
Grade Beam A foundation element or wall, typically constructed of reinforced concrete, used to span
between other foundation elements such as drilled piers.
Groundwater Subsurface water found in the zone of saturation of soils or within fractures in bedrock.
Heave Upward movement.
Lithologic The characteristics which describe the composition and texture of soil and rock by
observation.
Native Grade The naturally occurring ground surface.
Native Soil Naturally occurring on-site soil, sometimes referred to as natural soil.
Optimum Moisture The water content at which a soil can be compacted to a maximum dry unit weight by a
Content given compactive effort.
Perched Water Groundwater, usually of limited area maintained above a normal water elevation by the
presence of an intervening relatively impervious continuous stratum.
Scarify To mechanically loosen soil or break down existing soil structure.
Settlement Downward movement.
Skin Friction (Side The frictional resistance developed between soil and an element of the structure such as a
Shear) drilled pier.
Soil(Earth) Sediments or other unconsolidated accumulations of solid particles produced by the
physical and chemical disintegration of rocks, and which may or may not contain organic
matter.
Strain The change in length per unit of length in a given direction.
Stress The force per unit area acting within a soil mass.
Strip To remove from present location.
Subbase A layer of specified material in a pavement system between the subgrade and base course.
Subgrade The soil prepared and compacted to support a structure, slab or pavement system.
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LARGE MAPS AVAILABLE
FOR
VIEWING
AT THE CLERK TO THE BOARD'S
OFFICE, IN THE PUBLIC REVIEW FILE.
Hello