The URL can be used to link to this page

Home My WebLink AboutCT 04-02; LA COSTA RIDGE NEIGHBORHOODS 2.1 & 2.2; PAVEMENT SECTION DESIGN RECOMMENDATIONS FOR CORTE ALISO, SITIO OCEANO, CORTE TAMARINDO, CORINTIA STREET; 2006-01-090 CT klu 4 Leighton and Associates, Inc. 0 A LEIGHTON GROUP COMPANY January 9, 2006 (Revised January 17, 2006) Project No. 0418 10-001 To: Pulte Homes 0 .. 5993 Avenida Encinas, Suite 101 0 Carlsbad, California 92008 Attention: Mr. Kevin Bryan .--.. Subject: Pavement. Section Design. Recommendations . for . Corte Aliso, Sitio Oceano, Corte ................Tamarindo, and a Portion of Corintia Street, La Costa Ridge Neighborhoods .2.1 0 and 2.2, Carlsbad Tract No. 04-02, Carlsbad, California References:. i. Carlsbad,. City. of, -19.96, .Standards for Design. and Construction of Public Works .............. .r . ...-Impr California, Project No.. 05332"1-2-01 - dated April 20,1993, revised December 10, 1996 .-Hunsaker & Associates, 2005a,. Private Improvement Plans. For La Costa Ridge, ........ ... '.. ,. ....'.. . . ...Corintia Street, La .Costa Ridge,, Neighborhoods 2.1 and 2.2,. Carlsbad Tract No. 0 04-02, Carlsbad, California, Drawing No. 4204B, 8 Sheets, dated October 18, 2005 & Associates, 2005b, Improvement Plans For La Costa Ridge ................................ ,Neighborhoo.ds"2.1. &. 2.2, La. .CostaRidge, Carlsbad .Tract No. .04-02, Carlsbad, ........... 'California, Drawing No 4204 18.:Sheets,. dated. October. 18, 2005 Introduction Jn accordance:.-with the: requirements of. the -City .'ofCarIsbad 'this letter presents ur paVement: ............... -. design- recommendations for a portion- of-Corintia Street. (between -Station-No. 30+3 and 64+46), ......' --::-.: Corte- Aliso, Sitio OceanQ, and Corte Jamarindo located within ..Carlsbad .Tract No. 04-02 in ................ Carlsbad,. California. Twelve representatie subade soil samples were obtained along' the-roadway. ...... . .' -- -. alignments. The samples were transported to our. laboratory-and R-value testing (in accordance with" Test. Method.30.1.). was performed.. The- test results indicated the .subade soils have R- 3934 Murphy Canyon Road, Suite B205 • San Diego, CA 92123-4425 858.292.8030 • Fax 858.292.0771 • www.leightongeo.com 041810-001 values ranging from 10 to 51. The approximate sample locations and results of the laboratory testing are presented in Appendix A. Based on our conversations with the civil engineer, and review of the project improvement plans (HUñsaker and Associates, 2005a and 2005b), we understand that the subject streets within . Carlsbad Tract No. 04-02 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 is 4 inches of Asphalt Concrete (AC) over 4 inches of Aggregate Base (AB) regardless of the R-Value. Pavement Section Utilizing Class 2 Aggregate Base Material Based on the above information, one recommended Class 2 Aggregate Base pavement section for the entire project (assuming the lowest R-Value obtained) 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) Corintia Street (Station No. 5.0 10 4.5 6.0 30+75 to 64+44), Corte Aliso, Sitio Oceano, and Corte Tamarindo Prior to placement of the street aggregate base material, the upper 12 inches of the subgrade soils in the streets (including beneath the curb and gutter) shall be scarified, moisture-conditioned (or.dned back) as necessary to at least optimum moisture content and compacted to a minimum 95 percent relative compaction based on ASTM Test Method Dl 557. 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 basematerial- shall be 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. 4 -2- Leighton 041810-001 Recommended Pavement Section Based on our experience with similar soils within the City of Carlsbad, 'we recommend that the pavement section for Corintia Street (between Station No. 49+25 and 54+00) utilize the Class 2 Aggregate Base material with no lime treatment of the subgrade. In summary, it has been our professional. experience that relatively thin lime-treated subgrade soil sections are very sensitive to moisture variations during the curing process and ultimately may be susceptible' to minor cracking. In addition, it has been our experience that, relatively thin lime-treated 'lean silty clays and- sandy clays (which are present on the La Costa Ridge project) are also susceptible to heaving conditions that can result in asphalt concrete cracking and distress. Therefore, it is our opinion 'that utilizing the Class 2 Aggregate Base material pavement design, as presented on Table 1, will result in a better performing pavement section.. 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. 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. William D. Olson, RCE 45283 Senior Project Engineer A- '' Randall K. Wagner, LIZG612 Senior Associate Geologist Attachments': Appendix A'- Laboratory Testing Procedures and Test Results Ditributioñ: (4) 'Addressee ' ' (2)' Pulte Homes, Attention: Mr. Travis Arnold • - - (2) City of Carlsbad, Public Works Department, Attention Mr Tim Fennessy 4 Leighton Mike Jensen Project Geologist Q% LTSSi D. CP 2( NoA4283 z12 ' EXP/3l&) *11 041810-001 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. The 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 R-1 Corintia Street, Brown Silty SAND 27 Station No. 61+50 R-2 Corintia Street, Station No. 56+65 Gray-Brown Silty Clayey SAND 19 R-3 Corintia Street, Brown Silty CLAY 10 Station No. 52+10 R-4 Corte Tamarindo, Brown Silty SAND 51 Station No. 14+65 R-5 Sitio Oceana, Station No. 20+60 Brown Silty SAND 32 R-6 Sitio Oceana, Station No. 16+60 Pale brown Silty SAND 29 R-7 Sitio Oceana, Station No. 12+75 Brown Silty CLAY • 15 Corintia Street,' R-8 Brown Silty SAND 28 Station No. 47+60 Corintia Street, R-9 Brown Silty SAND 37 Station No. 40+75 Corintia Street, R-10 Brown Silty Clayey SAND . 38 Station No. 36+50 Corintia Street, R-11 Brown Silty Clayey SAND 24 Station No. 32+50 Corintia Street, R-12 Brown Silty Clayey SAND 26 Station No. 43+15 A-i '