HomeMy WebLinkAboutCT 04-03; LA COSTA RIDGE NEIGHBORHOODS 2.3 & 2.4; PAVEMENT RECOMMENDATIONS CORTE LONGOSTA, SITIO SENDERO; 2005-12-14GEQTECHNICAL CONSULTANTS
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GEOCON
INCORPORATED
Project No. 07290-52-05
December 14, 2005
Shea Homes
9990 Mesa Rim Road
San Diego, California 92121
Attention: Mr. Greg Ponce
Subject: VILLAGES OF LA COSTA - THE RIDGE
NEIGHBORHOODS 2.3 AND 2.4 (NORTH)
CORTE LANGOSTA - STATIONS 9+70 TO 24+65
SITIO SENDERO - STATIONS 30+00 TO 37+60
CARLSBAD, CALIFORNIA
PAVEMENT RECOMMENDATIONS
Gentlemen:
In accordance with your request, we have performed supplemental geotechnical services for the
subject roadways within Villages of La Costa - The Ridge development. The scope of our services
included obtaining representative subgrade soil samples within the street areas and performing
Resistance Value (R-Value) tests. The purpose of our work was to provide pavement design
recommendations. To aid in preparing this letter, we have reviewed the improvement plans entitled
Improvement Plans and Utility Plans for: La Costa Ridge - Neighborhoods 2.3 and 2.4 (North),
prepared by Hunsaker and Associates (Drawing No. 420-5), City of Carlsbad approval dated
August 23, 2005, and our report entitled Update Geotechnical Investigation, Villages of La Costa -
The Ridge, Carlsbad, California, dated August 27, 2001 (Project No. 06105-12-05).
Subgrade soils in the area are predominately clayey fine sands and sandy to clayey gravels and
exhibit relatively low to moderate R-Value characteristics. Based on field observations and previous
laboratory tests, subgrade materials possess an expansion potential of "very low" to "low"
(Expansion Index of 50 or less) as defined by Uniform Building Code (UBC) Table 18-I-B. R-Value
laboratory tests were performed in accordance with ASTM D 2844-01 (California Test Method
No. 301) and the laboratory test results are presented on Table I.
Based on conversations with Hunsaker and Associates, the project civil engineer, we understand that
a Traffic Index (TI) of 5.0 has been assigned to the subject roadways. Based on the above information
and laboratory testing, we recommend the pavement sections indicated on Table H. Pavement section
calculations were performed in accordance with California Department of Transportation Highway
Design Manual; Section 608.4 and the City of Carlsbad Minimum Structural Standard GS-17.
Pavement section calculations are presented on Figure 1. These recommended sections should be
considered preliminary with final sections to be determined and approved by the City of Carlsbad.
Prior to placing base material for roadways as well as curb and gutter, we_ie the upper
12 inches of subgrade be scarified, moisture conditioned as necessary, and compacted to a dry density
of at least 95 percent of the laboratory maximum dry density near to slightly above optimum moisture
6960 Flanders Drive 0 San Diego, California 92121-2974 0 Telephone (858) 558-6900 0 Fax (858) 558-6159
content in accordance with ASTM D 1557-02. In addition, the Class 2 aggregate base shall be
compacted to a dry density of at least 95 percent of the laboratory maximum dry density near to
slightly above optimum moisture content.
Asphalt concrete shall be compacted to a density of at least 95 percent of the laboratory Hveem
density in accordance with ASTM D 2726-04. The upper 12 inches of subgrade beneath areas to
receive concrete sidewalks shall be compacted to a dry density of 90 percent of the laboratory
maximum dry density near to slightly above optimum moisture content. Fill soil and aggregate base
lift thicknesses should not exceed 6 inches. Class 2 aggregate base and asphalt concrete shall conform
to the City of Carlsbad specifications.
The performance of asphalt concrete pavement is highly dependent on providing positive surface
drainage away from the edge of the pavement. Ponding of water on or adjacent to the pavement will
likely result in pavement distress and subgrade failure. To reduce the occurrence for such situations,
we recommend that a minimum drainage gradient of 1 percent be maintained for pavement surfaces.
Drainage from landscaped areas should be directed to controlled drainage structures.
Should you have any questions regarding this correspondence, or if we may be of further service,
please contact the undersigned at your convenience.
Very truly yours,
GEOCON INCORPORATED
63291 '' 2 Shane Rodacker
Addressee
RCE 63291 W
.
SRdmc
(3/del) Shea Homes, Jobsite Trailer
Attention: Mr. Matt Rottnek
(1) Hunsaker and Associates
Attention: Mr. David Blalock
Project No. 07290-52-05 - 2 - December 14, 2005
TABLE I
SUMMARY OF R-VALUE TEST RESULTS
ASTM D 2844-01
(CALIFORNIA TEST METHOD NO. 301)
Sample Number Location R-Value
R-1 Sitio Sendero - Stations 30+00 to 33+00 35
R-2 Sitio Sendero - Stations 33+00 to 36+00 16
R-3 Sitio Sendero - Stations 36+00 to 37+60 19
R-4 Corte Langosta - Stations 9+70 to 12+70 32
R-5 Corte Langosta - Stations 12+70 to 15+70 32
R-6 Corte Langosta - Stations 15+70 to 18+70 34
R-7 Corte Langosta - Stations 18+70 to 21+70 26
R-8 Corte Langosta - Stations 21+70 to 24+65 17
TABLE ID
PAVEMENT SECTION RECOMMENDATIONS
Location Traffic Index
(TI)
Asphalt
Concrete
(inches)
Class 2
Aggregate Base
(inches)
Sitio Sendero - Stations 30+00 to 33+00 5.0 4 4
Sitio Sendero - Stations 33+00 to 36+00 5.0 4 6
Sitio Sendero - Stations 36+00 to 37+60 5.0 4 5
Corte Langosta - Stations 9+70 to 12+70 5.0 4 4
Corte Langosta - Stations 12+70 to 15+70 5.0 4 4
Corte Langosta - Stations 15+70 to 18+70 5.0 4 4
Corte Langosta - Stations 18+70 to 21+70 5.0 4 4
Corte Langosta - Stations 21+70 to 24+65 5.0 4 6
Project No. 07290-52-05 December 14, 2005
FIGURE 1
PAVEMENT SECTION CALCULATIONS
VILLAGES OF LA COSTA - THE RIDGE
Sitio Sendero - Stations 30+00 to 33+00
Use subgrade R-Value = 35.0
Traffic Index (TI) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)( 5.0)(100-78.0)+0.2 =.55 feet
from Table 608.4B Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC = .83 feet
GE for base = (0.0032)(5.0)(100-35.0) -.83 .21 feet
from Table 608.413 Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 2.25 inches
Use base thickness = 4.0 inches, City of Carlsbad minimum
*** Design Street Structural Section
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 4.0 inches.
Sitio Sendero - Stations 33+00 to 36+00
Use subgrade R-Value = 16.0
Traffic Index (TI) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)(5.0)(100-78.0)+0.2 = .55 feet
from Table 608.4B Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC =.83 feet
GE for base = (0.0032)(5.0)(100-16.0) -.83 = .51 feet
from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 5.57 inches
Use base thickness = 6.0 inches
*** Design Street Structural Section ***
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 6.0 inches.
Project No. 07290-52-05 December 14, 2005
FIGURE 1 (Continued)
PAVEMENT SECTION CALCULATIONS
VILLAGES OF LA COSTA - THE RIDGE
Sitio Sendero - Stations 36+00 to 37+60
Use subgrade R-Value = 19.0
Traffic Index (TI) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)(5.0)(100-78.0)+0.2 = .55 feet
from Table 608.4B Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC = .83 feet
GE for base = (0.0032)(5.0)(100-19.0) -.83 =.46 feet
from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 5.05 inches
Use base thickness = 5.0 inches
*** Design Street Structural Section ***
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 5.0 inches.
Corte Langosta - Stations 9+70 to 12+70
Use subgrade R-Value = 32.0
Traffic Index (TI) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)(5.0)(100-78.0)+0.2 = .55 feet
from Table 608.4B Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC = .83 feet
GE for base = (0.0032)(5.0)(100-32,0) -.83 = .25 feet
from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 2.78 inches
Use base thickness = 4.0 inches, City of Carlsbad minimum
Design Street Structural Section ***
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 4.0 inches.
Project No. 07290-52-05 December 14, 2005
FIGURE 1 (Continued)
PAVEMENT SECTION CALCULATIONS
VILLAGES OF LA COSTA-THE RIDGE
Corte Langosta - 12+70 to 15+70
Use subgrade R-Value = 32.0
Traffic Index (TI) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)(5.0)(100-78.0)+0.2 =.55 feet
from Table 608.413 Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC = .83 feet
GE for base = (0.0032)(5.0)(100-32.0) -.83 = .25 feet
from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 2.78 inches
Use base thickness = 4.0 inches, City of Carlsbad minimum
Design Street Structural Section
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 4.0 inches.
Corte Langosta - Stations 15+70 to 18+70
Use subgrade R-Value = 34.0
Traffic Index (TI) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)(5.0)(100-78.0)+0.2 =.55 feet
from Table 608.4B Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC =.83 feet
GE for base = (0.0032)(5.0)(100-34.0) -.83 = .22 feet
from Table 608.413 Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 2.43 inches
Use base thickness = 4.0 inches, City of Carlsbad minimum
Design Street Structural Section
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 4.0 inches.
Project No. 07290-52-05 December 14, 2005
FIGURE 1 (Continued)
PAVEMENT SECTION CALCULATIONS
VILLAGES OF LA COSTA - THERIDGE
Corte Langosta - Stations 18+70 to 21+70
Use subgrade R-Value = 26.0
Traffic Index (TI) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
-Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)(5.0)(100-78.0)+0.2 = .55 feet
from Table 608.4B Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC = .83 feet
GE for base = (0.0032)(5.0)(100-26.0) -.83 = .35 feet
from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 3.83 inches
Use base thickness = 4.0 inches
*** Design Street Structural Section ***
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 4.0 inches.
Corte Langosta - Stations 21+70 to 24+65
Use subgrade R-Value = 17.0
Traffic Index (Ti) = 5.0
Methodology = Caltrans Highway Design Manual Section 608.4
Safety Factor = 0.2 - Applied to Asphalt Concrete (AC)
GE for AC = (0.0032)(5.0)(100-78.0)+0.2 =.55 feet
from Table 608.4B Highway Design Manual
GE = .55 feet for AC yields actual thickness = 2.65 inches
Use 4.0 inches of AC - City Minimum
GE for 4.0 inches of AC = .83 feet
GE for base = (0.0032)(5.0)(100-17.0) -.83 = .49 feet
from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1
Base thickness = 5.40 inches
Use base thickness = 6.0 inches
Design Street Structural Section ***
Asphalt Concrete Thickness = 4.0 inches.
Class 2 Aggregate Base Thickness = 6.0 inches.
Project No. 07290-52-05 December 14, 2005