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Home My WebLink About3557; Carlsbad Blvd Bridge Retrofit; Carlsbad Blvd Bridge Retrofit; 2008-07-03Geotechnical and Environmental Sciences Consultants July 3, 2008 ProjectNo. 106214001 Ms. Eva Plajzer City of Carlsbad Public Works Engineering , 1635 Faraday Avenue Carlsbad, Califomia 92008 M:CEIVED JUL 23 2008 DEPARTMENT Subject: Summary of Fieldwork Observations and Testing During Subsurface Exploration Performed by Group Delta Consultants Carlsbad Boulevard Railroad Bridge Overcrossing Slope Distress Project Carlsbad, Califomia Reference: Ninyo & Moore, 2007, Geotechnical Evaluation, Carlsbad Boulevard Railroad Bridge Overcrossing Slope, Carlsbad, California: dated December 4. Dear Ms. Platzjer: In accordance with your request and authorization, we performed field observations and testing at the site during subsurface exploration by Group Delta Consultants. As referenced above, our offices per- formed a geotechnical evaluation of observed distress at the slope and adjacent wing walls at this site in 2007. One ofthe conclusions of that evaluation was that loose soils were present below the foundations ofthe wing walls and settlement of these soils had contributed to the observed distress. FIELD EXPLORATION AND TESTING On March 20, 2008 representatives from our firm observed the subsurface exploration performed by Group Delta Consultants. Their exploration consisted of the manual excavation of two exploratory test pits and three borings. In addition they performed Dynamic Cone Penetration Tests using a Wildcat Dynamic Cone. During the exploration our field geologist observed that the encountered fill soils as generally consisted of brown, moist, loose, silty sand; a finding consistent with those made during our referenced evaluation. Our geologist was provided the opportunity to perform in-place field density testing and to collect represen- tative soil samples from the test pits excavated by Group Delta. Two field density tests were performed in accordance with American Society for Testing and Materials (ASTM) D 6938 (Nuclear Gauge Method). One field density test was performed within exploratory test pit TP-1, located in front of the eastem wing- wall. The other field density test was performed within test pit TP-2, located in front of the westem wingwall. The field density tests were performed at the approximate elevation of the bottom of footings for 5710 Ruffin Road » San Diego, California 92123 • Phone (858) 576-1000 • Fax (858) 576-9600 San Diego • Irvine » Ontario » Los Angeles • Oal<land • Las Vegas Carson City " Phoenix • Denver Carlsbad Boulevard Railroad Bridge Overcrossing Slope July 3, 2008 Carlsbad, Califomia Project No. 106214001 the wingwalls. The results and approximate elevations of these tests are presented in the attached Table 1. Subsequent to the in-place field density testing within each of the two test pits, representative bulk samples ofthe encountered soils were collected and retumed to our in-house geotechnical laboratory for testing. LABORATORY TESTING Geotechnical laboratory testing was performed on the collected samples to evaluate in-place moisture content as well as modified Proctor dry density and optimum moisture content. The moisture content test- ing was performed in accordance with ASTM D2216, and the results are presented in the attached Table 1. The modified Proctor dry density and optimum moisture content were evaluated in general ac- cordance with ASTM D 1557, and the results are presented on Figures 1 and 2. DISCUSSION AND CONCLUSIONS As noted, one of the conclusions of our reference report was that loose soils beneath the wing walls had set- tled and that this had contributed to the observed disfress. Laboratory testing of soils collected during our earlier evaluafion had yielded dry densifies of 103.5 and 105.9 pounds per cubic foot (pcf). Dry densifies of 101.3 and 113.8 pcf were obtained from in-place field testing of soils during our most recent evaluation. It is our opinion that the results of our most recent field and geotechnical laboratory testing are consistent with the conclusion presented in the referenced report that settlement of loose fill soils contributed to the observed distress. Accordingly, we feel that the repair recommendations presented in the report are still valid and applicable. Respectfully submitted, NINYO & MOORE Jeffrey T. Kent, RE. vy^tx?-. " JB±jj Jbnathan Goodmacher, C.E.G 2136 Senior Project Engineer V \^CAAV-^i!^yy Alanager/Principal Geologist Attachments: Table 1 - Summary of Field Density Tests \J )<s|t llrya ^ Figures 1 and 2 - Proctor Density Test Results "^iiS S'i F^T FIED , :"NC5!NEERI,NG Distribution: (3) Addressee ^ ^VOGIST/ , 1062M001LObs,<ioc 2 MintgOS^^^ TABLE 1 SUMMARY OF FIELD DENSITY TESTS. PROJECTNO. 106214001 TEST OF: COMPACTED FILL Field Laboratory . Test No. Date Test of Test Location Elevation (ft) Soil Type No. Dry Density (pcf) In-Place Moisture Content (%) Proctor Density (pcf) Optimum Moisture Content - (%) Relative Compaction (%) Remarks 1 # 3/20/08 CF In Front of Eastem Wingwall 27.5 I 101.3 11.9 126.0 10.0 80 •2 # 3/20/08 CF In Front of Westem Wingwall 26.5 2 113.8 10.9 129.0 10.0 88 Notes: Test No.;: (#) Test of: WB Nuclear Gauge Test Method; (*) - Sand Cone Test Method; (-I-) - 12-inch Sand Cone Method; C) - Drive-Cylinder Method Wall Backfill I0621400I FDT-xIs 1 of 1 140.0 130.0 120,0 O H W 110.0 LJJ Q > DC a 100.0 90.0 - 80.0 \ 1 i i II 1 \ Zero Air Void Line \ • 1 (Specific Gravity = 2.70) \ / / i Zero Air Void Line J. -(Specific Gravity = = 2.60) / Zero Air Void Line / (Specific Gravity = = 2.50) 1 \ — \ ^\ 10 15 20 25 MOISTURE CONTENT (%) 30 35 40 Sample Location Depth (ft) Soil Description Maximum Dry Density (pcf) Optimum Moisture Content (%) TP-1 3.0-3.5 Silty SAND (SM) 126.0 10.0 Dry Density and Moisture Content Values Corrected for Oversize (ASTM D 4718-87) N/A N/A PERFORMED IN GENERAL ACCORDANCE WITH 0 ASTM D 1557-02 • ASTM D 698-OOa METHOD0A Dsnc PROCTOR DENSITY TEST RESULTS FIGURE 1 PROJECT NO. DATE CARLSBAD BOULEVARD BRIDGE OVERCROSSING SLOPE CARLSBAD, CALIFORNIA FIGURE 1 106214001 7/08 CARLSBAD BOULEVARD BRIDGE OVERCROSSING SLOPE CARLSBAD, CALIFORNIA FIGURE 1 106214001 PROCTOR TP-1 @ 3,0-3 6,xls 140.0 OU.U -1—'—^ 0 ———1—1—i—1 1 \ 1—^—I—I—\—1—1—1—1—1—I— 5 10 15 20 2£ MOISTURE CONTENT ("A 1 1 1 > 30 35 40 Sample Location Depth (ft) Soil Description Maximum Dry Density (pcO Optimum Moisture Content (%) TP-2 5.0-6.0 Silty SAND (SM) 129.0 10.0 Dry Density and Moisture Content Values Corrected for Oversize (ASTM D 4718-87) N/A N/A PERFORMED IN GENERAL ACCORDANCE WITH [7| ASTM D 1557-02 • ASTM D 698-OOa METHOD0A DBQC PROCTOR DENSITY TEST RESULTS FIGURE 2 PROJECT NO. DATE CARLSBAD BOULEVARD BRIDGE OVERCROSSING SLOPE CARLSBAD, CALIFORNIA FIGURE 2 106214001 7/08 CARLSBAD BOULEVARD BRIDGE OVERCROSSING SLOPE CARLSBAD, CALIFORNIA FIGURE 2 106214001 PROCTOR TP-2 @ 5,0-6.0.xls