HomeMy WebLinkAboutRIGDEN FARM, 5TH FILING, TRACT I, SETTLERS GREEN - PDP - 56-98J - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTEarth Engineering Cornutrants, Inc.
EEC Project No. 1994119
July 7, 2000
Page 4
project owner has expressed a desire to use the lower R-value and construct more conservative
pavement sections. On that basis, we recommend design pavement sections as follows:
Des Moines Drive
Roadway
Custer Drive
Rigden Drive
Canby Way
Chase Drive
Design EDLA
110
35
20
Composite Section
Asphalt Surface
6"
5"
4'/2 "
Aggregate Base
14"
12"
9"
The asphalt surface should consist of grading C or CX hot bituminous pavement consistent with
City of Fort Collins criteria. The aggregate base should consist of Class 5 or Class 6 aggregate
base.
GENERAL COMMENTS
The preliminary analysis and recommendations presented in this report are based upon the data
obtained from the soil borings performed at the indicated locations and from any other information
discussed in this report. This report does not reflect any variations which may occur between
borings or across the site. The nature and extent of such variations may not become evident until
further exploration or construction. If variations appear evident, it will be necessary to re-evaluate
the recommendations of this report.
This report has been prepared for the exclusive use of Wheeler Construction Services, LLC for
specific application to the project discussed and has been prepared in accordance with generally
accepted geotechnical engineering practices. No warranty, express or implied, is made. In the
event that any 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 the changes are reviewed and the conclusions of this report modified or verified in
writing by the geotechnical engineer.
Earth Eupnwmg Consultants, ins.
EEC Project No. 1994119
July 7, 2000
Page 3
At boring locations B-12 and B-13, silty, sandy gravel was encountered in the test borings. At
boring locations B-14, B-16 and B-17, claystone/siltstone bedrock was encountered below depths
of 4 feet. During utility installation, all shallow bedrock was removed for the street areas and
replaced with low volume change fill.
The stratification boundaries indicated on the boring logs represent the approximate locations of
changes in soil types; in -situ, the transition of materials may be gradual and indistinct.
Observations were made while drilling and after completion of the borings to detect the presence
and depth to free water. Free water was observed only in borings B-12 and B-15 at a depth of
approximately 7 and 8 1/2 feet, respectively, at the time of drilling. Fluctuations in groundwater
levels can occur over time depending on variations in hydrologic conditions and other conditions
not apparent at the time of this report.
ANALYSIS AND RECOMMENDATIONS
The subgrades for the roadways have been -prepared in general accordance with City of Fort
Collins criteria. In addition, any bedrock encountered within 4 feet of the top-of-subgrade has
been removed and replaced with low volume change material. Utilities have also been installed
within the roadway right-of-way in accordance with City requirements. Field density tests have
been completed on the utility backfill materials within the roadway areas. The test results indicate
the site fill and backfill materials were compacted to at least 95% of standard Proctor maximum
dry density.
The subgrade soils in the pavement areas consist of sandy lean clay or pit -run gravel with low
swell potential. It is our opinion those subgrades could be used for direct support of composite
or full -depth asphalt concrete pavement sections. A Hveem R-value of 10 was determined in
laboratory testing of the cohesive subgrade soils.
Pavement designs based on an assumed R-value of 5 have been pre -designed for this development.
Although a higher R-value has been determined in the laboratory for the in -place subgrades, the
Earth FEng K•ing Consultants, Inc.
EEC Project No. 1994119
July 7, 2000
Page 2
barrel sampling procedures and from the auger cuttings. Field density testing has previously been
completed in the overlot fill and utility backfill areas.
Moisture content tests were completed in the laboratory on each of the recovered samples. In
addition, washed sieve analysis and Atterberg limits tests were performed on samples representing
the different subgrade soil groups encountered. Swell/consolidation tests were performed on
selected California barrel samples. One Hveem stabilometer R-value test was completed on a
composite sample of near surface subgrade materials. Results of the outlined tests are shown on
the attached boring logs and summary sheets.
As a part of the testing program, all samples were examined in the laboratory by an engineer and
classified in accordance with the attached General Notes and the Unified Soil Classification
System, based on the soil's texture and plasticity. The estimated group symbol for the Unified
Soil Classification System is shown on the boring logs and a brief description of that classification
system is included with this report.
SITE AND SUBSURFACE CONDITIONS
The Rigden Farm development'is located south of Drake Road and east of Lemay Avenue. The
approximate roadway configuration within the First Filing of the development is indicated on the
attached boring location diagram. At this time, overlot grading and utility installations have been
completed in the roadway areas identified as a part of this report. The boring location diagram
indicates the present paving phase and previously completed pavement areas. Field density tests
have been completed on the overlot fill and utility backfill.
Based on results of the subsurface exploration, subsurface conditions can be generalized as
follows. Subsurface soils encountered in the test borings consisted predominately of sandy lean
clay with occasional gravel. A portion of material encountered in the test borings was overlot fill
material or utility backfill. The site materials are slightly plastic as indicated from the Atterberg
limits tests. The lean clay shows low swell potential in in -situ moisture and density conditions.
The subsurface soils have low to moderate remolded strength.
SUBSURFACE EXPLORATION REPORT/PAVEMENT DESIGN
RIGDEN FARM PAVEMENTS
FORT COLLINS, COLORADO
EEC PROJECT NO. 1994119
July 7, 2000
INTRODUCTION
The subsurface exploration for selected roadway subgrades in Rigden Farm in Fort Collins,
Colorado has been completed. Twenty (20) soil borings were advanced in the right-of-ways of
the new streets to develop information on existing subsurface conditions. At the time of our
exploration, the sanitary sewer and water had been installed in the roadway right-of-ways.
Individual boring logs and a diagram indicating the approximate boring locations are included with
this report.
The Rigden Farm development is located south of Drake Road and east of Lemay Avenue in Fort
Collins. At the time of our exploration, the street subgrades were at approximate final grade and
the underground utilities had been installed in the street right-of-ways. The purpose of our
exploration was to define the existing subsurface conditions in the street areas and provide
remolded subgrade strength characteristics of the subgrade soils for use in the pavement structure
design. Pavement structure designs based partially on traffic load data previously provided by
City of Fort Collins Engineering are also included with this report.
IEXPLORATION AND TESTING PROCEDURES
The boring locations were selected and established in the field by Earth Engineering Consultants,
Inc. (EEC) personnel. The field locations were established by approximating locations relative
to identifiable site features. The locations of the field borings should be considered accurate only
to the degree implied by the methods used to make the field measurements.
The borings were performed with a CME 45 drill rig using 4-inch nominal diameter continuous
flight augers. Samples of the subgrade materials were obtained using split -barrel and California
July 7, 2000
Wheeler Construction Services, LLC
1027 West Horsetooth Road, Suite 200
Fort Collins, Colorado 80526
Attn: Mr. Ken Snee
Re: Subsurface Exploration Report/Pavement Design
Rigden Farm Pavements
Fort Collins, Colorado
EEC Project No. 1994119
Mr. Snee:
6 :
E
EARTH ENGINEERING
CONSULTANTS, INC.
Enclosed, herewith, are the results of the geotechnical subsurface exploration completed by Earth
Engineering Consultants, Inc. personnel for selected roadways in the Rigden Farm development in Fort
Collins. The roadways included in this evaluation are:
- Custer Drive from Timberline to east of Chase Drive
- Rigden Parkway from Des Moines Drive to south of Custer Drive
- Canby Way from Topeka Lane to Des Moines Drive
- Chase Drive from Topeka Lane to Des Moines Drive
- Des Moines Drive from Topeka Lane to east of Chase Drive.
The structural pavement design for roadways based on previously provided traffic data are also included with
this report.
We appreciate the opportunity to be of service to you on this project. If you have any questions concerning
the enclosed report, or if we can be of further service to you in any other way, please do not hesitate to
contact us.
Principal Engineer
cc: Rick Richter - City of Fort Collins (4)
CENTRE FOR ADVANCED TECHNOLOGY
2301 RESEARCH BOULEVARD, SUITE 1 04
FORT COLLINS, COLORADO80526
(970) 224- 1 522 (FAx) 224-4564
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