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Home My WebLink AboutCT 02-05; LA COSTA OAKS SOUTH NEIGHBORHOOD 3.15; PAVEMENT RECOMMENDATIONS CIRCULO SEQUOIA; 2004-01-13GEOCON INCORPORATED Project No. 06105-52-17 January 13, 2004 . . . . cTO2ot5 GEOTECHNICAL CONSULTANTS CiTY OF 0AFL5LJAD APPROVED O WITH ADD iT(NS ' /17/oq - 6 D.TE Davidson Communities 1302 Camino Del Mar Del Mar, California 92014 Attention: Ms. Paula Lombardi Subject: VILLAGES OF LA COSTA - THE OAKS SOUTH NEIGHBORHOOD 3.15. CIRCULO SEQUOIA STATION 37+00 TO 51+30 CARLSBAD, CALIFORNIA PAVEMENT RECOMMENDATIONS Dear Ms. Lombardi: In accordance with ybur request, we have performed supplemental geotechnical services for the subject street within Villages of La Costa TheOaks South 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 and Utility Plans for Villages of La Costa - Neighborhood 3.15, prepared by Hunsaker & Associates, City of Carlsbad approval dated May 27, 2003 and our report entitled Update Geotechnical Report, Villages of La Costa-The Oaks South, Neighborhood 3.15, Carlsbad, California, dated January 6, 2004 (Project No. 06105-52-17). Subgrade soils in the area are predominately sandy to clayey gravels and typically ekhibit relatively low to medium R-Value characteristics. Based on field observations and previous laboratory tests, subgrade materials possess an expansion potential of "low" to "medium" (Expansion Index of 90 or less) as defined .by Uniform Building Code (UBC) Table 184-B. R-Value laboratorytests were. performed in accordance with ASTM D2844-99 (California Test Method 301) and the laboratory test results are presented on Table I. It is our understanding that a Traffic' Index (TI) of 5.0 has been assigned to the subject street. 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 recommend 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 6960 Flanders Drive 0 San Diego, California 92121-2974 • Telephone (858) 5586900 • Fax (858) 558-6159 .: :.. 0.... - moisture content in accordance with ASTM D 1557 00 In addition, the Class 2 aggregate base should 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 should be compacted to a density of at least 95 percent of the laboratory. Hveem density in accordance with ASTM D 2726-96a The upper 12 inches of subgrade soils beneath areas to receive concrete sidewalks should be compacted to a dry density of at least 90 percent of the laboratory maximum dry density near to slightly above optimum moisture content. Fill soil and base lift thickness should not exceed 6 inches. Class 2 aggregate base and asphalt concrete should 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 : - - 0 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 yow have any questions regarding this correspondence, or if we may be. of further service, - please contact the undersigned at your. convenience. - • Very truly yours, 0 -- . • 0 RO Shane odacker OFC (2) . Addressee 0 0 • • 0 (3/del) Davidson Communities (Jobsite) 0 - • . 0 Attention: Mr. George Sturgeon (1) Hunsalcer & Associates 0 • 0 0, 0 Attention: 'Mr. David Blalock 0 0 • 0 • ' 0 / -. TABLE 1, SUMMARYsOF R-yALuE TEST RESULTS i ASTMD2844-99 (CALIFORNIA TEST METHOD 301) 1, Sample No. . Location R-Value R-1 Circulo Sequoia Station 48+50 to 51+30 44 R-2 Circulo Sequoia Station 45+50 to 48+50 42 R-3 Circulo Sequoia Station 43+00 to 45+50 50 R-4 '.. Circulo Sequoia Station 40+00 to 43+00 : 18 R-5 . Circulo Sequoia Station 37+00 to 40+00 32 4. -i Location Traffic Index Asphalt Concrete - Class 2 Aggregate Base - . " ' '(inches) (inches) Circulo Sequoia Station4.8±50 to 51+30 5.0 .4 . . 4 Circulo Sequoia Station 45+50 to 48+50 5.0 4' . . 4 Circulo Sequoia Station 43+00 to 45+50- 5.0 4 . 4 Circulo Sequoia Station 40+00 to 43+00 5.0 4 6 Circulo Sequoia Station 37+00 to 40+00 . 5.0 - 4 4 FIGURE 1 PAVEMENT SECTION CALCULATIONS . VILLAGES OF LA COSTA -THE OAKS SOUTH . Circulo Sequoia - Station 48+50 to 51+30 . Use subgradeR-Value = 44.0 Traffic Index (TI) = 5.0 Methodology =CALTRANS Highivay Design Manual Section, 608.4 -' Safety Factor = 0.2 Applied to Asphalt Concrete'(AC) GE for AC (0.0032)( 5.0)100-7,8.0)+0.2' .55,fet from Table. 608.413 Highviay Design Manual . . . '. . . GE = 55 feet for AC yields actual thickness = 2 65 mches -Use 4.0 inches of AC - City Minimum GE for 4.0 inches of AC = .83 feet. . S GE for base .= (0.0032)( 5.0)(100-44.0) - .83 = .06 feet from Table 608.413 Highway Design Manual with GF for Class 2 base= 1.1 . Base thickness = '.68 inches . ,. . .. Use base thickness = 4.0 inches *** Design Street Structural Section .. . . . . Asphalt Conérete Thickness = 4.0 inches Class 2. Aggregate Base Thickness = 4.0 inches. .. Circulo Sequoia- Station 45+50 to 48+50 . . . . Use subgrade R-Value = 42.0 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 - S from Table 608.4B Highway Design Manual GE = .55 feet-for AC yields actual thickness = 265 inches' , ' Use 4.0 ipches of AC - City Minimum , 5 .5 • S GE for 4.0 inches of AC = .83 feet GE for base = (00032)( 5.0)(100-42.0) - .83 = .09 feet- from Table 608.4B Highway Design Manual with G1 for Class 2 base'-1. 1 Base thickness = 1.03 inches Use base thickness = 4.0 inches Design Street Structural Section S S Asphalt Concrete Thickness = 4.0 inches. . - - Class 2-Aggregate Base Thickness 4.0 inches. ProjectNó. 06105-52-17 - .' S ' '- • : . . January 13, 2004 ( ' FIGURE 1 (Continued) '. PAVEMENT SECTION CALCULATIONS - VILLAGES OF LA COSTA -THE OAKS SOUTH Circulo'Sequoia - Station 43+00 to 45+50 Use subg'rade R-Value = 50.0 . Traffic Index (TI) 5.0 '' •• •- 'Methodology =CALTRANS Highway Design Manual Section 608:4 Safety Factor = 0.2 -- Applied to Asphalt Concrete (XC) . 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 =,(0.0632)(5.0)(100-50!0)- .83 = -.03 feet . from Table 608 4B Highway Design Manual with GF for Class 2 base = 1.1 Base thickness = -.36 inches Use base thickness = 4.0 'inches 'I Design Street, Structural. Section Asphalt Concrete Thickness = 4.0 inches. Class .2 Aggregate Base Thickness 4.0 inches. Circitlo Sequoia -Station 40+00 to 43+00 Use subgrade R-Valu"e = 18.0 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 GE for 4.0 inches of AC= .83 feet. . ' • E for base = (0.0032)( 5.0)(10048.0),,-..;83 = .48 feet; , - •., • • , from Table 608.4B Highway Design 'Manual with GF for Class 2 base = 1.1 ,• ' ' : '' • '. • Base thickness = '5.22 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. 06105-52-17 • ' . ' . ' • ' January 13, 2004.