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HomeMy WebLinkAboutCT 74-21; CARLSBAD OAKS BUSINESS PARK; TESTING AND OBSERVATION REPORT; 1992-11-24GEOCON *RECEIVED 11011301992 I NCO RPORATED ul Geotechnical Engineers and Engineering Geologists -OD Project No. 04950-52-01 Tech Construction Corporation Post Office Box 80036 San Diego, California 92138 Attention: Mr. Ted Tchang Subject: CARLSBAD OAKS EAST NORTH OF EL FUERTE STREET CARLSBAD, CALIFORNIA REPORT OF TESTING AND OBSERVATION SERVICES DURING DRAINAGE CHANNEL RE-GRADING Gentlemen: In accordance with your request and our proposal dated October 29, 1992, we have provided compaction testing and observation services during the re-grading of a drainage channel north of El Fuerte Street on the subject project. Our services were performed during the period of November 6, 1992 through November 17, 1992. The scope of our services included the following: Observing the re-grading operation, including the removal and/or processing of loose soils prior to fill placement. Performing in-place density tests in fill placed and compacted at the site. Preparing a map indicating the location of in-place density tests. Preparing this report of re-grading operations. GENERAL In 1987, a concrete-lined drainage channel was constructed north of the terminus of El Fuerte Street to transport runoff from El Fuerte Street and adjacent developed areas to a desilting basin. As a result of heavy rains in the area last winter, an erosional feature was created beneath and adjacent to the drainage channel below approximately Station 2+50. 6960 Flanders Drive San Diego, CA 92121-2974 619 558-6900 - FAX 619 558-6159 -S.'. -. - ".5 --.'..--.5•-.655_ - 0 Project No. 04950-52-01 November 24, 1992 Page 2 The gully created by the erosion possessed a maximum width of approximately 40 feet and a maximum depth of approximately 20 feet with vertical side slopes. The grading contractor for the re-grade was T.C. Construction Company. The plan supplied for our use was prepared by Rick Engineering Company and is entitled Improvement Plan For: Drainage Channel in Carlsbad Airport Business Park, Sheet Number 26, "As-Built" date of October 8, 1987. References to elevations and locations herein were based on surveyor's or grade checker's stakes in the field and/or interpolation from the referenced Improvement Plan. Geocon Incorporated did not provide surveying services and, therefore, has no opinion regarding the accuracy of the as-graded elevations or surface geometry with respect to the approved grading plans or proper surface drainage. GRADING Grading began with the removal of brush, vegetation, and concrete debris from the area to be re-graded. Loose soils deposited subsequent to the erosion were removed until firm, previously placed fill soils were encountered. Prior to placing fill, the exposed ground surface was scarified, moisture conditioned and compacted. Fill soils derived from on-site excavations were then placed and compacted in layers until the desired elevations were attained. In general, the on-site fill materials consist of sandy clay soils derived from excavations in adjacent hillsides. - During the re-grading operation, compaction procedures were observed and in-place density tests were performed to evaluate the relative compaction of the fill material. The in-place density tests were performed in general conformance with ASTM Test Method D-2922-81 (Nuclear Test Method). The results of the in-place dry density and moisture content tests are summarized on Table I. Percent relative compaction was calculated using laboratory test results for optimum moisture content and maximum dry density from a report entitled As- Graded Geotechnical Report, Final Report of Mass Grading, Carlsbad Oaks Business Center, Carlsbad Tract 74-21, Carlsbad, California, prepared by San Diego Geotechnical Consultants, Inc., dated February 19, 1987. The results of the laboratory tests are summarized in- Table II. In general, the in-place density test results indicate that the fill soil has a relative compaction of at least 90 percent at the locations tested. The approximate locations of the in-place density-tests are.shown on Figure 1. Project No. 04950-52-01 November 24, 1992 Page RECOMMENDATIONS Any additional grading performed in the vicinity of the drainage channel should be accomplished in conjunction with our observation and compaction testing services. Grading plans for any future grading should be reviewed by Geocon Incorporated prior to finalizing. All trench backfill in excess of one foot thick should be compacted to at least 90 percent relative compaction. This office should be notified at least 48 hours prior to commencing additional grading or backfill operations. Adequate drainage provisions are imperative. Drainage water should be directed away from foundations, pavements, concrete slabs, and slope tops to controlled drainage devices. Experience has shown that even with these provisions, a shallow groundwater or subsurface water condition can and may develop in areas where no such water conditions existed prior to site development; this is particularly true where a substantial increase in surface water infiltration results from an increase in landscape irrigation. LIMITATIONS The information contained herein applies only to our work with respect to the re-grading operation, and represents conditions at the date of our final observation, November 17, 1992. Changes in the conditions of a property can occur with the passage of time due to natural processes or the works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards may occur, resulting from legislation or the broadening of knowledge in the fields of geotechnical engineering or geology. Accordingly, the findings of this report may be invalidated wholly or partially by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period of three years. Any subsequent grading should be done in conjunction with our observation and testing services. As used herein, the term "observation" implies only that we observed the progress of the work with which we agreed to be involved. Our services did not -include the evalu- ation or identification of the potential presence of hazardous materials. Our conclusions and opinions as to whether the work essentially complies with the job specifications are- based on our observations, experience and test results. Due to the inaccuracies inherent in most field and laboratory soil tests, and the necessary assumption that the relatively small soil sample tested is representative of a significantly larger volume of soil, future tests of the same soil location or condition should not be expected to duplicate specific individual test results of this report. Subsurface conditions, and the accuracy of tests used to measure such conditions, can vary greatly at any time. We make no warranty, expressed or implied, except that our services were performed in accordance with engineering principles generally accepted at this time and location. - - - - Project No. 04950-52-01 November 24, 1992 Page 4 We will accept no responsibility for any subsequent changes made to the site by others, by the uncontrolled action of water, or by the failure of others to properly repair damages caused by the uncontrolled action of water. Recommendations which pertain to the future maintenance and care for the property should be brought to the attention of future owners of the property or portions thereof. If you have any questions regarding this report, or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON INCORPORATED GfESSi co i5E 1524 Z3 cc a) M Cr ENGINEERING rian W. Jr. LJ cO No 46236 :0 John Hoobs GEOLOGI CE 462~3 Exp. 12-31-94 CEG 1524 6.30- CNII "We Or CA *0q6 (6) Addressee MaIF Nal = == = == = Off sm ig OWN VNIVEL ___ ___ ___ _____ • SEE DETAIL . . 3CALE 1'. OR ____ ___ • \ \ 4/ F i2&lN L (SPL49h1 pj0N%wNEL PC LL - - .,:'•. •- • . 47 FVTUKE RIM '::~SpL49N WALL 7t M S Comm- it- For ro SCALE 0 N THICK- PER 9-56 15 So fe ;, / : _Lff e TOM. RIP RAP ILANKT .- . _.- / / \••. I\ .IT WI DCC. SILL AND FILTER C-LOOO CLASSCONCRETE sjAp/çT7 s(EoETnL QETAIL'_SILLWI_ FILTER BLANKETS - \ '4' ENGINEER OF WORK MIS BENCHMARK --- . t'.I . . I" BARRY C.1BENDER R.C.E. 28448 . - DATE E5CRIPrIoP COlIC. MONUMENT wifrAwoAso 015C \ _-- \ \\.L_ FOR STOAA DRAIN 5)TEM E . -. . RICK ENGINEERING COMPANY • TAMPED ER. (9 • '- _.—:7 - ' \ \ 5(E SUE(T NO. tI • - Ow PL4/fOS- CIVIL £NGINES-LAV SPN)DRS XAI(f2& 900' SOUTH OF INTERSECTION OF a CAMIW \ \ \\ . 3088 P10 piro A.C4RL8840, CALJE 98008 fli 789-4997 SEAL r PALOMAR AIRPORT RD EAST 5101 OF EL MM - -' - - - 5,011 ° INCORPORATED Prn47r GVW7ACT LLOAv1 FEf(CELINE. PRECISE SURVEY LEVELS. \\ PROJ. NO. 04950-52-01 ST1CITY OFCARLSBAD FIG. I 2&!M U.S-C 10.5 -- — J?.f 1606 - .— ---- \ \\\\ -'".' - DATE 11-24-1992 IMPROVEMENT PLAN FOR, N11?7 (5 CMNGECNMNILN5TORN&AIN DRAINAGE CHANNEL PHASE AS BUILT 11 _- LEGEND PHASE Af 5bILT PWVJECT S_PHASE_1 ?'l CARLSBAD AIRPORT BUSINESS CENTER -" •..........APPROX. LOCATION OF IN-PLACE FE-4.77-St DENSITY TEST CfrV 18ENMR E_28448 DATE --'\\ IFM DENSITY TEST LOCATION MAP L ____________ __ c ________ • - _-•- •-- _________ er _PEoNs In CHANNEL DATA i4 XL TA a? Bfl RADIUS WWJ7W RENA KS J. 600 1(3.51' , B,y 1Ot__ - QOO&O6' ________200' P(AClf _4O!4P$ 82.00 WCH 2o'- 400' 5ö 00 REACU _3 Project No. 04950-52-01 TABLE I FIELD DENSITY TEST RESULTS Elev. Plus Max. Opt. Field Field Field Req'd or 3/4" Dry Moist. Dry Moist. Rel. Rel. Test Depth Curve Rock Dens. Cont. Dens. Cont. Comp. Comp. Test No. Date Test Location (ft) No. (%) (pcf) (%) (pcf) (%) (%) (%) Type 1 11/09/92 DRAIN. CHANNEL 3+25 314 7 0 119.5 12.0 110.0 15.1 92 90 NU 2 11/09/92 DRAIN. CHANNEL 3+35 317 7 0 119.5 12.0 108.1 16.5 91 90 3 11/10/92 DRAIN. CHANNEL 2+85 315 8 0 114.0 15.5 102.8 19.7 90 90 4 11/10/92 DRAIN. CHANNEL 3+90 306 7 0 119.5 12.0 108.8 16.3 91 90 NU 5 11/10/92 DRAIN. CHANNEL 3+05 318 8 0 114.0 15.5 103.9 17.5 91 90 NU 6 11/10/92 DRAIN. CHANNEL 4+35 309 8 0 114.0 15.5 98.7 17.4 87 90 NU 6A 11/10/92 DRAIN. CHANNEL 4+35 309 8 0 114.0 15.5 103.3 17.6 91 90 NU 7 11/10/92 DRAIN. CHANNEL 3+45 317 7 0 119.5 12.0 109.5 17.3 92 90 NU 8 11/10/92 DRAIN. CHANNEL 4+65 302 7 0 119.5 12.0 109.2 16.1 91 90 NU 9 11/11/92 DRAIN. CHANNEL 5+10 294 8 0 114.0 15.5 103.0 18.1 90 90 NU 10 11/11/92 DRAIN. CHANNEL 5+85 281 9 0 112.8 15.8 101.7 20.6 90 90 NU 11 11/11/92 DRAIN. CHANNEL 2+60 336 8 0 114.0 15.5 103.4 17.7 91 90 NU 12 11/16/92 DRAIN. CHANNEL 5+90 283. 7 0 119.5 12.0 107.9 17.6 90 90 NU 13 11/17/92 DRAIN. CHANNEL 4+90 297 7 0 119.5 12.0 111.0 14.1 93 90 NU 14 11/17/92 DRAIN. CHANNEL 2+80 332 8 0 114.0 15.5 103.1 16.8 90 90 NU 15 11/17/92 DRAIN. CHANNEL 3+70 314 8 0 114.0 15.5 104.9 17.3 92 90 Note: See last page of table for explanation of coded terms Project No. 04950-52-01 EXPLANATION OF CODED TERMS - TEST SUFFIX A, B, C .....Retest of previous density test failure, following moisture conditioning and/or recompaction. R: Fill in area of density test failure was removed and replaced with properly compacted fill soil. - PREFIX CODE DESIGNATION FOR TEST NUMBERS AD - Area Drain JT - Joint Trench ST - Slope Test B - Base Test MT - Moisture Test SW - Sidewalk CG - Curb & Gutter RW - Retaining Wall SZ - Slope Zone CW - Crib Wall SD - Storm Drain UT - Utility Trench DW - Driveway SC - Subgrade WB - Wall Backfill FG - Finish Grade SL - Sewer Lateral WL - Water Lateral IT - Irrigation Trench SM - Sewer Main WM - Water Main - CURVE NO. Corresponds to curve numbers listed in Table II, representing the laboratory maximum dry density/optimum moisture content data for selected fill soil samples encountered during testing and observation. - ROCK CORRECTION For density tests with rock percentage greater than zero, laboratory maximum dry density and optimum moisture content were adjusted for rock content. For tests with rock content equal to zero, laboratory maximum dry density and optimum moisture content values listed are then unadjusted values. - TYPE OF TEST SC: Sand Cone Test NU: Nuclear Density Test DC: Drive Cylinder Test - ELEVATION/DEPTH Test elevations/depths have been rounded to the nearest whole foot. Project No. 04950-52-01 November 24, 1992 TABLE II Summary of Laboratory Comnaction Test Results Optimum Maximum Moisture Dry Density Content Sample No. Description (pcfl (% Dry Wt.) 7* Tan sandy CLAY 119.5 12.0 8* Light orange-brown sandy CLAY 114.0 15.5 9* Light green-brown sandy CLAY 112.8 15.8 * Laboratory test results from As-Graded Geotechnical Report, Final Report of Mass Grading, Carlsbad Oaks Business Center, Carlsbad Tract 74-21, Carlsbad, California, prepared by San Diego Geotechnical Consultants, Inc., dated February 19, 1987.