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Home My WebLink AboutCT 90-03; SHELLEY PROPERTY; PAVEMENT DESIGN RECOMMENDATIONS; 2002-06-10i; qy CITY OF CARLSBAD A&L Leighton and!AssocfqçEb MEMO ?iIH1WDHIUN AGTGCompany I G rT,HNICALCONUITANTS S /1&/ov I LV DATE June 3, 2002 (revised June 10, 2002) Project No. 851855-014 To: Continental Homes 2237 Faraday Avenue, Suite 100 Carlsbad, California 92008 Attention: Mr. Dave Lother Subject: Pavement Design Recommendations, Avenida Aragon, Avenida Secreto, Sitio Toledo, and Sitio Andalucia, Vista Unit 4, Carlsbad Tract No. 90-03, 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 Leighton. and Associates, Inc., 2001, Pavement Design Recommendations, Arroyo Vista Unit 2, Carlsbad Tract No. 90-03, Carlsbad, California, Project No. 851855-012, dated August 7, 2001, Revised August 16, 2001 Project Design Consultants, 2001, Plans for the Improvement of Shelley Property Unit No. 4, Carlsbad Tract No. 90-03, Carlsbad, California, Project No. CT 90-03, Drawing No. 380-1E, 7 Sheets, dated April 4, 2001 Introduction In accordance with the requirements of the City of Carlsbad, this letter presents our pavement design recommendations for Avenida Aragon, Avenida Secreto, Sitio Toledo, and Sitio Andalucia within Unit No. 4 of the Arroyo Vista project (Carlsbad Tract No.90-03) located in Carlsbad, California. Six representative subgrade soil samples were obtained from along the streets of the project. 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 6 to 64. The approximate sample locations and results of the laboratory testing are presented in Appendix A. Based on the project Improvement Plans (Project Design Consultants, 2001), we understand that Avenida Aragon, Avenida Secreto, Sitio Toledo, and Sitio Andalucia are considered local streets and have a traffic index (TI) of 5.0. According to the City requirements (Carlsbad, 1996), the minimum pavement section for streets having a TI of 5.0 or less is 4 inches of Asphalt Concrete (AC) over 4 inches of Aggregate Base (AB) regardless of the R-Value. R ,. ,€4Li- c I 3934 Murphy Canyon Road, #B205, San Diego, CA 92123-4425 (858) 292-8030 • FAX (858) 292-0771 • www.leightongeo.com 851855-014 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. The pavement section design calculations utilizing Caltrans design methods are presented as Appendix B. Table I Recommended Pavement Section Utilizing Class 2 Aggregate Base Traffic Design Asphalt Concrete Class 2 Aggregate Location Index R-Value Thickness Base Thickness (in inches) (in inches) Avenida Aragon (Station No. 50 6 4 8 12+50to17+00) Avenida Aragon (Station No. 1+50 to 6+50), and 5.0 9 4 Avenida Secreto Sitio Toledo 5.0 12 4 6 Avenida Aragon (Station No. 6+50 to 12+50) and 5.0 20 4 5 Sitio Andalucia Prior to placement of the Class 2 aggregate base material, the upper 12 inches of subgrade soils in the street (including beneath and a minimum of 6 inches beyond the back of the curb and gutter) should be scarified, moisture-conditioned 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 should then be placed and compacted at a minimum 95 percent relative compaction in accordance with ASTM Test Method D1557. The aggregate base material should be at least 6 inches thick below the curb and gutter and extend a minimum of 6 inches behind the back of the curb. Class 2 Aggregate Base should 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 should conform to and be placed in accordance with the "Greenbook" Standard Specifications for Public Works Construction and the City of Carlsbad requirements. 851855-014 Pavement Section Utilizing Lime-Treated Subgrade Soils A representative subgrade soil sample having a R-Value of less than 12 was retested for optimum lime content per American Standard of Testing and Materials (ASTM) Test Method C977. The optimum lime content was determined to be 5 percent quick lime. Testing of the lime treated sample resulted in an R-value of 69. The laboratory test results are presented in Appendix A. Also provided in Appendix A are results of sulfate content testing which was performed in accordance with Caltrans Test No. 417. Based on the above information, the recommended lime-treated 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 2. Table 2 Recommended Pavement Section Utilizing Lime Treated Subgrade Soils Traffic Design AC Class 2 Base Lime Treated Location Index R-Value Thickness Thickness Subgrade Layer (in inches) (in inches) (in inches) Avenida Aragon (Station No. 1+50 to 6+50 and 12+50 to 5.0 69 4 4 12 17+00), Avenida Secreto, and Sitio Toledo Prior to placement of asphalt concrete and Class 2 Aggregate Base, the upper 12 inches of subgrade soils in the street (including beneath the curb and gutter) should be scarified, moisture-conditioned to at least optimum moisture content, and thoroughly mixed with 5 percent quick lime (or equivalent percentage of hydrated lime slurry). After setting for a minimum of 24 hours, the thoroughly mixed lime-treated subgrade soils should be compacted to a minimum 95 percent relative compaction based on ASTM Test Method D1557. After the minimum compaction is achieved for the lime-treated subgrade, the lime-treated subgrade soils should be allowed to cure. After the completion of the curing period, a minimum of 4 inches of Class 2 Aggregate Base should then be placed and compacted at a minimum 95 percent relative compaction in accordance with ASTM Test Method D1557. The aggregate base material should be at least 6 inches thick below the curb and gutter and extend a minimum of 6 inches behind the back of the curb. After the placement and compaction of the Class 2 Aggregate Base, a minimum of 4 inches of asphalt concrete should be placed. Asphalt concrete and lime-treated subgrade soils should conform to and be placed in accordance with 1) the latest revision of the California Department of Transportation Standard Specifications; 2) in accordance with State of the Art Report 5, Lime Stabilization of the Transportation Research Board, National Research Council; 3) the "Greenbook" Standard Specifications for Public Works Construction (Sections 203 and/or 400); and/or 4) the City of Carlsbad requirements. Class 2 Aggregate Base should conform to and be placed -3- 85 1855-0 14 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. Pavements Adjacent to Landscape Areas If pavement is planned adjacent to landscaped areas, we recommend that appropriate measured be taken (such as keeping the amount of landscape irrigation to a minimum), installing area drains or other devices to reduce the possible adverse effects of water on the pavement subgrade. If you have any questions regarding our report, please contact this office. We appreciate this opportunity to be of service. Respectfully submitted, LEIGHTON AND ASSOCIATES, INC. VLLt W-- Randall K. Wagner, CEG 1 12 Director of Geology Attachments: Appendix A - Laboratory Testing Procedures and Test Results Appendix B - Asphalt Pavement Section Design Calculations Distribution: (4) Addressee (2) Continental Homes Attention: Mr. Jerry Sims (2) City of Carlsbad, Public Works Department Attention: Mr. Tim Fennessy -4- 851855-014 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 and Representative Location Sample Description R-Value Location Avenida Aragon Avenida Aragon (Station No. 1+50 to 6+50) Yellow olive-brown silty to Station No. 3+00 and Avenida Secreto clayey sand 10 (Station No. 6+50 to 8+75) Avenida Secreto Avenida Secreto Olive gray sandy clay 9 Station No. 4+25 (Station No. 0+40 to 6+50) Avenida Aragon Avenida Aragon Pale yellow silty sand 64 Station No. 8+50 (Station No. 6+50 to 12+50) Sitio Toledo Sitio Toledo Olive brown silty to clayey 12 Station No. 1+75 sand Avenida Aragon Avenida Aragon Olive green clay with sand 6 Station No. 14+20 (Station No. 12+50 to 17+00) Sitio Andalucia Sitio Andalucia Pale yellow silty sand 20 Station No. 2+00 Lime-Treated Avenida Aragon, Avenida Light to medium brown sandy Subgrade Secreto , and Sitio Toledo CLAY to clayey SAND with 69 5% quick lime Soluble Sulfates: The soluble sulfate contents of selected samples were determined by Caltrans Test No. 417. The test results are presented in the table below: Sample Number Sample Description Sulfate Content (%) R-7, Lime-Treated Subgrade Light to medium brown sandy CLAY to 0.18 clayey SAND I A-i 851855-014 APPENDIX B Asphalt Pavement Section Design Calculations 1) Avenida Aragon (Station No. 6+50 to 12+50) and Sitio Andalucia Utilizing Aggregate Base Material H = Thickness GE = Gravel Equivalent Design Traffic Index = 5.0 Design Subgrade R-Value = 20 Class 2 Aggregate Base R-Value = 78. (based on Caltrans Standard Specifications, Section 26) Asphalt Concrete (AC) Layer GEac = (0.0032) (5.0) (100-78) + 0.20 = 0.55 feet Gfac = 2.54 Hac = 0.55 feet x 12 in/ft = 2.6 inches 2.55 Use 4.0 inches of asphalt concrete (City of Carlsbad minimum) Actual GE of asphalt concrete layer = (4/12 feet) 2.54 = 0.85 feet Aggregate Base (AB) Layer G&0 = (0.0032) (5.0) (100-20) = 1.28 feet GE AB 1.28 feet - 0.85 = 0.43 feet GFAB = 1.1 HAB = 0.43 feet x 12 in/ft.= 4.7 inches 1.1 Use 5.0 inches of Aggregate Base material Recommended Pavement Section 4.0 inches of asphalt concrete over 5.0 inches of Class 2 Aggregate Base material (based on the City of Carlsbad Standards for Design and Construction of Public Works Improvements) 851855-014 APPENDIX B Asphalt Pavement Section Design Calculations (Continued) 2) Sitio Toledo Utilizing Aggregate Base Material H = Thickness GE =Gravel Equivalent Design Traffic Index = 5.0 Design Subgrade R-Value = 12 Class 2 Aggregate Base R-Value = 78. (based on Caltrans Standard Specifications, Section 26) Asphalt Concrete (AC) Layer GEac = (0.0032) (5.0) (100-78) + 0.20 = 0.55 feet Gfac2.54 H. = 0.55 feet x 12 in/ft = 2.6 inches 2.55 Use 4.0 inches of asphalt concrete (City of Carlsbad minimum) Actual GE of asphalt concrete layer = (4/12 feet) 2.54 = 0.85 feet Aggregate Base (AB) Layer GEtotai = (0.0032) (5.0) (10012) = 1.40 feet GE AB 1.40 feet - 0.85 = 0.55 feet GFAB = 1.1 H = 0.55 feet x 12 in/ft = 6.0 inches 1.1 Use 6.0 inches of Aggregate Base material . Recommended Pavement Section 4.0 inches of asphalt concrete over 6.0 inches of Class 2 Aggregate Base material (based on the City of Carlsbad Standards for Design and Construction of Public Works Improvements) B-2 __ noun 851855-014 APPENDIX B Asphalt Pavement Section Design Calculations (Continued) 3) Avenida Aragon (Station No. 1+50 to 6+50) and Avenida Secreto Utilizing Aggregate Base Material H = Thickness GE =Gravel Equivalent Design Traffic Index = 5.0 Design Subgrade R-Value = 9 Class 2 Aggregate Base R-Value = 78, (based on Caltrans Standard Specifications, Section 26) Asphalt Concrete (AC) Layer GEac = (0.0032) (5.0) (10078) + 0.20 = 0.55 feet Gfac = 2.54 Hac = 0.55 feet x 12 in/ft = 2.6 inches 2.55 Use 4.0 inches of asphalt concrete (City of Carlsbad minimum) Actual GE of asphalt concrete layer = (4/12 feet) 2.54 = 0.85 feet Aggregate Base (AB) Layer GEtotai = (0.0032) (5.0) (100-9) = 1.46 feet GE.n = 1.46 feet - 0.85 = 0.61 feet GFAB = 1.1 HAB = 0.61 feet x 12 in/ft = 6.7 inches 1.1 Use 7.0 inches of Aggregate Base material Recommended Pavement Section 4.0 inches of asphalt concrete over 7.0 inches of Class 2 Aggregate Base material (based on the City of Carlsbad Standards for Design and Construction of Public Works Improvements) B-3 __ 851855-014 APPENDIX B Asphalt Pavement Section Design Calculations (Continued) 4) Avenida Aragon (Station No. 12+50 to 17+00) Utilizing Aggregate Base Material H = Thickness GE =Gravel Equivalent Design Traffic Index = 5.0 Design Subgrade R-Value = 6 Class 2 Aggregate Base R-Value = 78, (based on Caltrans Standard Specifications, Section 26) Asphalt Concrete (AC) Layer GEac = (0.0032) (5.0) (100-78) + 0.20 = 0.55 feet Gfac= 2.54 Hac = 0.55 feet x 12 in/ft = 2.6 inches 2.55 Use 4.0 inches of asphalt concrete (City of Carlsbad minimum) Actual GE of asphalt concrete layer = (4/12 feet) 2.54 = 0.85 feet Aggregate Base (AB) Layer = (0.0032) (5.0) (100-6) = 1.51 feet GE AB 1.51 feet - 0.85 = 0.66 feet GFAB = 1.1 HAB = 0.66 feet x 12 in/ft = 7.2 inches 1.1 Use 8.0 inches of Aggregate Base material Recommended Pavement Section 4.0 inches of asphalt concrete over 8.0 inches of Class 2 Aggregate Base material (based on the City of Carlsbad Standards for Design and Construction of Public Works Improvements) 851855-014 APPENDIX B Asphalt Pavement Section Design Calculations (Continued) 5) Avenida Aragon (Station No. 1+50 to 6+50 and 12+50 to 17+00). Avenida Secreto. and Sitio Toledo Utilizing Lime-Treated Subgrade Soils H = Thickness GE = Gravel Equivalent Design Traffic Index = 5.0 Design Subgrade R-Value = 69 Asphalt Concrete (AC) Layer GEac = (0.0032) (5.0) (100-78) + 0.20 = 0.55 feet Gfac=2.54 Hac = 0.55 feet x 12 in/ft = 2.6 inches 2.55 Use 4.0 inches of asphalt concrete (City of Carlsbad minimum) Actual GE of asphalt concrete layer = (4/12 feet) 2.54 = 0.85 feet Aggregate Base (AB) Layer GE,. = (0.0032) (5.0) (100-69) = 0.50 feet GEM3 = 0.50 feet - 0.85 = -0.35 feet GF=1.i HAB = -0.35 feet x 12 in/ft = -3.8 inches 1.1 Use 4.0 inches of Aggregate Base material (City of Carlsbad minimum) IiL B-S __ 851855-014 APPENDIX B Asphalt Pavement Section Design Calculations (Continued) 5) Avenida Aragon (Station No. 1+50 to 6+50 and 12+50 to 17+00), Avenida Secreto. and Sitio Toledo Utilizing Lime-Treated Subgrade Soils (continued) Lime Treated Subgrade Layer (assuming 5 % quick lime or equivalent percentage of hydrated lime slurry) GEtotai = (0.0032) (5.0) (100-9) + 0.2 = 1.66 feet = 1.66 feet —0.85 = 0.81 feet Gfits = 0.9 +(400/1000)= 1.3 H1 0.81 feet 12 in/ft - 7.5 inches 1.3 Use 12.0 inches of Lime Treated Subgrade (City of Carlsbad minimum) Recommended Pavement Section 4.0 inches of asphalt concrete over 4.0 inches of Class 2 Aggregate Base material over 12.0 inches of Lime Treated Subgrade (based on the City of Carlsbad Standards for Design and Construction of Public Works Improvements). B-6 Mown __