HomeMy WebLinkAboutCT 00-06; BRESSI RANCH; PAVEMENT SECTION DESIGN RECOMMENDATIONS; 2004-04-08croO- 0c9
Leighton and Associates, Inc.
A LEIGHTON GROUP COMPANY
April 8, 2004
Project No. 971009-011
To: Lennar Communities
1525 Faraday Avenue, Suite 300
Carlsbad, California 92008
Attention: Ms. Kristine Zortman
X2JL 4//2/o1-
Subject: Pavement Section Design Recommendations for El Fuerte Street (Bressi Ranch
Way to the North End of PA-13), Station No. 21+50 to 34+00, Bressi Ranch,
Carlsbad, California
References: Carlsbad, City of, 1996, Standards for Design and Construction of Public Works
Improvements in the City of Carlsbad, California, Project No. 05332-12-01, dated
April 20, 1993, revised December 10, 1996
Project Design Consultants (PDC), 2003, Plans for the Improvement of El Fuerte
Street, Carlsbad, California, Project No. CT-00-06, Drawing No. 400-8E, 23 Sheets,
dated February 21, 2003
Introduction
This letter presents our preliminary pavement design recommendations for El Fuerte Street (form
Bressi Ranch Way to the north end of PA-13) between Station No. 21+50 and 34+00 within the
Bressi Ranch project, located in Carlsbad, California. Three representative subgrade soil samples
were obtained along the roadway alignment. The samples were transported to our laboratory and R-
value testing (in accordance with Caltrans Test Method 301) was performed. The test results
indicated the subgrade soils have R-values ranging from 12 to 13. The approximate sample
locations and results of the laboratory testing are presented in Appendix A.
Based on the project Improvement Plans (PDC, 2003), we understand that Poinsettia Lane has a
traffic index (TI) of 8.0. According to the City of Carlsbad requirements (Carlsbad, 1996), the
minimum pavement section for streets having a TI of 8.0 is 5.0 inches of Asphalt Concrete (AC)
over 6.0 inches of Aggregate Base (AB) regardless of the R-Value.
3934 Murphy Canyon Road, Suite B205 • San Diego, CA 92123-4425
858.292.8030 • Fax 858.292.0771 • www.leightongeo.com
971009-011
Pavement Section Utilizing Class 2 Aggregate Base Material
Based on the above information, the recommended Class 2 Aggregate Base pavement section
was calculated using the Caltrans Highway Design Manual Method and compared with the City
of Carlsbad's minimum section thickness requirements. The recommended pavement section is
presented on Table 1.
Table 1
Recommended Pavement Section Utilizing Class 2 Aggregate Base
Asphalt Class 2
Location Traffic Design Concrete Aggregate Base
Index R-Value Thickness Thickness
(in inches) (in inches)
El Fuerte Street, Station No. 8.0 12 5.0 16.0 21+50 to 34+00
Prior to placement of the street aggregate base material, the upper 12 inches of subgrade soils in the
street (including beneath the curb and gutter) shall be scarified, moisture-conditioned (or dried
back) as necessary to at least optimum moisture content and compacted to a minimum 95 percent
relative compaction based on American Standard of Testing and Materials (ASTM) Test Method
D1557.
Class 2 Aggregate Base shall then be placed and compacted at a minimum 95 percent relative
compaction in accordance with ASTM Test Method D1557. The aggregate base material shall be a
maximum of 6 inches thick below the curb and gutter and extend a minimum of 6 inches behind the
back of the curb. The Class 2 Aggregate Base shall conform to and be placed in accordance with
the latest revision of the California Department of Transportation Standard Specifications (Section
26), the Greenbook specifications, and/or the City of Carlsbad requirements. Asphalt Concrete shall
conform to and be placed in accordance with the "Greenbook" Standard Specifications for Public
Works Construction and the City of Carlsbad requirements.
If pavement is planned adjacent to landscaped areas, we recommend that appropriate measures be
taken (such as keeping the amount of landscape irrigation to a minimum, installing area drains or
other devices, etc.) to reduce the possible adverse effects of water on the pavement subgrade.
4
Leighton
971009-011
If you have any questions regarding our letter, please contact this office. We appreciate this
opportunity to be of service.
Respectfully submitted,
LEIGHTON AND ASSOCIATES, INC.
No. 45283 rn
CM rn William D. Olson, RCE 45283
Senior Project Engineer
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Randall K. Wagner, LEG 1612 fKQ
Senior Associate
if No. 164-2
* CERTIFIED *
Vi \ ENGINEERING / Attachments: Appendix A - Laboratory Testing Procedures and Test Results
OF CAL
Distribution: (2) Addressee 13
Lennar Communities, Attention: Mr. Jim Urbina
City of Carlsbad, Public Works Department, Attention: Mr. Casey Arndt
(2) J. T. Kruer, Attention: Mr. Chuck Knight
(1) Hazard Construction Company, Attention: Mr. Lino Cruz
-3-
Leighton
971009-011
APPENDIX A
Laboratory Testing Procedures and Test Results
"R"-Value: The resistance "R"-value was determined by the California Materials Method No. 301
for subgrade soils. Three samples were prepared and exudation pressure and 'R"-value determined
on each one. The graphically determined "R"-value exudation pressure of 300 psi is summarized in
the table below:
Sample Number Sample Location Sample Description R-Value
El Fuerte Street, Station
R-25 Light brown clayey SILT 13
No. 32+50
El Fuerte Street, Station
R-26 Light brown clayey SILT 13
No. 29+30
El Fuerte Street, Station
R-27 Light brown clayey SILT 12
No. 25+10
A-i
Leighton