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Home My WebLink AboutCT 02-24; VILLAGES OF LA COSTA GREENS 1.11, 1.13, 1.14; PAVEMENT RECOMMENDATIONS GALENA AVE, COPAL PLACE, GOLDSTONE ROAD, CARNELIAN COURT; 2004-12-06CT 02-24 GEOCON I N C 0 R P 0 R A T E D Project No. 06403-52-16B December 6, 2004 GEOTECI-INICAL CONSULTANTS (low) John Laing Homes 6183 Paseo Del Norte, Suite 160 Carlsbad, California 92009 Attention: Ms. Liz Albano irer3ve GLl'fltqcL Subject: VILLAGES OF LA COSTA - THE GREENS NEIGHBORHOOD 1.14 GALENA AVENUE STATION 10+00 TO 17+00 COPAL PLACE STATION 10+00 TO 11+65 GOLDSTONE ROAD STATION 13+00 TO 19+00 CARNELIAN COURT STATION 10+00 TO 13+40 CARLSBAD, CALIFORNIA PAVEMENT RECOMMENDATIONS Dear Ms. Albano: In accordance with your request, we have performed supplemental geotechnical services for the subject roadway alignments within Villages of La Costa - The Greens 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 for: La Costa Greens - Neighborhood 1. 11, 1. 13, 1.14, prepared by Hunsaker and Associates (Drawing No. 406-3), City of Carlsbad approval dated May 6, 2004, and our report entitled Update Geotechnical Report, Villages of La Costa - The Greens, Neighborhoods 1.11, 1.13, and 1.14, Carlsbad, California, dated July 28, 2004 (Project No. 06403-52-16). Subgrade soils in the area are predominately sandy clays and silty sand, and typically exhibit relatively low R-Value characteristics. Based on field observations and previous laboratory tests, subgrade materials possess an "Mdiuri-" (Expansion Index of 90 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(!TtI)f4MO1has been assigned to the subject roadway alignments. Based on the above information and laboratory testing, we recommend the pavement sections indicated on Table II. 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. As indicated on Table I, the R-Value laboratory test results for Sample Nos. 1,.PR-4,—and R6" Wèls thaYff It is our understanding that the City of Carlsbad requires testing for lime treatment of subgrade soils when the R-Value is less than 12. Therefore, additional laboratory testing was performed to assess the actual amount of lime required to effectively treat the subgrade soils. We selected sample R-4 for the laboratory testing. As indicated on Table I, the R-Value test result for this sample was 5. 6960 Flanders Drive 0 San Diego, California 92121-2974 U Telephone (858) 558-6900 0 Fax (858) 558-6159 The labôratoiy test meth6d was-based on Texas Method, which consists of performThg a series of Plastiêity Index (P1) tests at diffefent lime contents until the P1 stabilizes. Table III sho4s the result of the P1 tests versus lime content. It is our opinion that 3.5 percent Quick Lime by dry weight (or 4.5 percent hydrated lime) is required to stabilize clayey subgrade. Supplemental R-Value( testing of the lime treated materials shows that the R-Value increased to 70. Table IV prpvides alternative recommended pavement sections that incorporate a lime-treated subgrade. The minimum thickness of lime-treated subgrade is estimated to be 6 inches. It has been our experience that lime treatment is most effective when used in situations where clays' of "high" expansion potential (Expansion Index of 90 or higher) are present. Due to the presence of silty sands and clays with 'low to medium expansion potential - _._: - -.,-----------.----.-.- - geotechnica1standpointthatthe constructionofaconventionaL.t,avement sectiona1on the ti Iii ect Prior to placing base material for roadways as well as curb and gutter, we recommend the upper 12 inches ofsubgrade 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 optirum moisture content in accordance with ASTM D 1557-02. 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 concrei'e should be compacted to a density,. of at least 95 percent of the laboratory Hveem density in accordance with ASTM D 2726-00. The upper 12'inches of subgrade beneath areas to receive concrete'. sidewalks should 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 base lift thickness should not exceed. 6 inches. Class 2 aggregate base and asphalt concrete should conform to the City. of CarIs8ad specifications. The performance of a5pha1t concrete pavement is highly dependent on providing'. poitive surface drainage away from the edge of.the pavement. Pondiig of water on or adjacent to the avement will likely result in pavement distress nd ubgade'failure Toreduce the occurrence for such situations we recommend that a minimtim drain iTe gradient of 1percent be maintained for pavement surfaces Drainage form landscaped area's 'should be difected iTocontrolled drainage structures. i - ..,f i/ ..•"•"' :4 4 Should you have , any quetions regarding this. conesp.ondence - or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON INCORPORATED Michael C. Ertwine Staff Geologist RCE 6 oF ESS,0 (.ROO ( No. 63291 Exp.6/3O/O6 ) MCE:SR:dmc (2) Addrssee. (1) Hunsaker and Associates Attention: Mr. David Blalock (3/del) John Laing Homes Cf0 Devenco;'La Costa' Gieens Job Site Attention: Mr. Will Bigler Project No. 06403-52-16B -2- Dcember 6, 2004 TABLE I SUMMARY OF R-VALUE TEST RESULTS ASTM D 2844-01 (CALIFORNIA TEST METHOD NO. 301) Sample No. Location R-Value R-1 Galena Avenue Station 13+50 to 17+00 10 R-2 Galena Avenue Station 10+00 to 13+50 21 R-3 Copal Place Station 10+50 to 11+65 6 R-4 Goldstone Road Station 16+00 to 19+00 5 R-5 Goldstone Road Station 13+00 to 16+00 15 R-6 Carnelian Court Station 10+00 to 13+40 10 TABLE II PAVEMENT SECTION RECOMMENDATIONS - CONVENTIONAL • Location • Traffic Index (TI) Asphalt Concrete (inches) C1as 2 Aggregate Base (inches) Galena Avenue Station 13+50 to 17+00 5.0 4 Galena Avenue StatiOn 10+00 to 13+50 5.0 4 Copal Place Station 10+50 to 11+65 5.0 4 1 8 Goldstone Road Station 16+00 to 19+00 5.0 4 V 8 Goldstone Road Station 13+00 to 16+00 5.0 4 Carnelian Court Station 10+00 to 13+40 5.0 4 1 7 1 TABLE III SUMMARY OF PLASTICITY INDEX VS. LIME CONTENT SAMPLE NO. R-4 - GOLDSTONE ROAD Plasticity Index (P1) Percent Lime 29 0 22 3 19 5 4 18 5 16 6 Project No. 06403-52-16B December 6, 2004 TABLE IV At(ERNATIVE PAVEMENT SECTION RE LIME-TREATED SUBGR ENDATIONS Traffi c Asphalt Class 2 Minimum Location Ind 7' Concrete Aggregate Lime-Treated /EFt (inches) Base Subgrade (inches) (inches) Galena Avenue Station 13+50 to 17+00 / N 5.0 4 • 4 6 Copal Place Station 10+50 to 11+65 4 4 6 Goldstone Road Station 16+00 to,1400 5.0 4 4 6 Carnelian Court Station 10+2p4 13+40 5.0 4 6 I. • I Project No. 06403-52-16B December 6, 2004 FIGURE 1 PAVEMENT SECTION CALCULATIONS VILLAGES OF LA COSTA - THE GREENS Galena Avenue Station 13+50 to 17+00 S Use subgrade R-Value = 10.0 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 = (0M032)( 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 ofAC=.83 feet GE for base = (0.0032)( 5.0)(100-10.0) -:83 .61 feet from Table 608.4B Highway D6sign'M'an'ual4 ith GF for Class-2 base = 1.1 Base thickness = 6.62 inches . 5; . . Use base thickness = 7.0indies . Design Street Structural Section *** Asphalt Concrete Thickness = 4.0 inches. Class 2 Aggregate Base Thickness .= 7.0 inches. Galena Avenue Station 10+00 to 13+50 Use subgrade R-Value = 21.0 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)(100-21:0) -.83 = .43 feet from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1 Base thickness = 4.70 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. Project No. 06403-52-16B S . December 6, 2004 FIGURE 1 (Continued) PAVEMENT SECTION CALCULATIONS 'VILLAGES OF LA COSTA - THE GREENS Copal Place- Station 10+50 to 11+65 Use subgrade R-Value = 6.0 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)( 50)(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- 6.0) -.83 = .67 feet from Table 608.413 Highway Design Manual with GF for Class 2 base =1. I Base thickness = 7.32 inches Use base thickness = 8.0'inches Design Street Structural Section Asphalt Concrete Thickness = 4.0 inches. Class 2 Aggregate Base Thickness = 8.0 inches. Goldstone Road - Station 16+00 to 19+00 Use subgrade R-Value =5.0 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)(100778.0)+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- 5.0) - .83 = .69 feet from Table 608.4B Highway Design Manual with GF for Class 2 base = 1.1 Base thickness = 7.49 inches Use base thickness = 8.0 inches Design 'Street Structural Section K* Asphalt Concrete Thickness = 4.0 inches. Class 2 Aggregate 'Base Thickness = 8.0. inches. ,Project No. 06403-52-6B ' ' ' December 6, 2004 FIGURE 1 (Continued) PAVEMENT SECTION CALCULATIONS VILLAGES OF LA COSTA - THE GREENS Goldstone Road - Station 13+00 to 16+00 Use subgrade R-Value = 15.0 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 GEfor 4.0 inches of AC = .83 feet GE for base = (0.0032)( 5-0)(100-15.0),-.83 =.53 feet from Table 608.413 Highway Design Manual with GF for Class 2 base = 1.1 Base thickness = 5.75 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. Carnelian Court - Station 10+00 to 13+40 Use subgrade R-Value = 10.0 Traffic Index (TI) = 5.0 Methodology = Caltrans Highway Design Manual Section 608.4 Safety Factor = 0.2 - Applied to Asphalt Concete (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)(100-10.0) -.83 = .61 feet from Table 608.4B Highway Design Manual with GF for Class 2 base = 1 Base thickness = 6.62 inches Use base thickness = 7.0 inches. Design Street Structural Section ***. Asphalt Concrete Thickness = 4.0 inches. Class 2 Aggregate Base Thickness = 7.0 inches. Project No. 06403-52-16B December 6, 2004