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Home My WebLink AboutCT 81-46; Camino Via Roble Unit 1 Lot 6; Soils Report; 1990-04-020 3’2. CT g/-46 - .- - - - - - - - - - - - - - -~ MOORE & TABER GEOTECHNICAL ENGINEERS AND GEOLOGlSTS 16760 WEST BERNARD0 DRIVE SAN DIEGO. CALIFORN,* 92127 TELEPHONE (619, 487.2113 FAX : (6191 487.2357 *Do,TIONAL OFFICES ANAHEIM BAKERSFIELD The Fox/Croft Partnership 404 Camino De1 Rio South, Suite 106 San Dieao. California 92108 CARLSBAD, April 2, 1990 Job NO. 689-215 ! ij 4”” !“’ I ENGINEERING DEPT. LIBE; City of Carlsbad 2075 Las Palmas Drive CarisbaQ CA 92009.48,5::,. Introduction \w This letter przs the results of qeotechnical tests and observations performed during recent grading operations on the subject lot, and presents the results of tests and observations performed during the backfilling of several utility trenches within the subject lot. This letter supplements our report of October 15, 1989 (Job No. 689-215). Site Gradins Additional fill placement was required within the parking lot area. The materials exposed at grade consisted of fill soils which were placed and compacted during initial site grading, which was described in our Report of Geotechnical Services for Carlsbad Tract 81-46 Unit No.1, dated February 25, 1988 (Job No. 285-256). Materials excavated from the southerly one-third of the parking lot were placed and compacted in the remaining parking area. Prior to fill placement, all areas to receive fill were stripped of unsuitable materials. The exposed ground surface was moisture conditioned and compacted to a depth of at least 8-inches. Fills were spread in thin lifts, moisture conditioned and compacted by rolling with heavy pneumatic wheeled equipment. Fill placement brought the parking and drive areas to rough grade. The maximum depth of fill placed at this time was approximately one foot in the center one-third of the parking lot. - Page 2 MOORE & TABER GEOTECHNICAL ENGINEERS AND GEOLOGISTS - The Fox/Croft Partnership - Utility Trench Backfills - Buildins Pad Area - Geotechnical tests and observations were performed during backfilling of the storm drain, sewer and water line trenches. The trenches were backfilled with on-site soils which were placed - in lifts, moisture conditioned and compacted by rolling with a sheepsfoot-roller attached to a large backhoe and/or rolling with heavy, pneumatic-wheeled equipment. The maximum depth of trench backfill is about five feet in the sewer line. - Testinq The maximum dry density and optimum moisture content of the representative soils were determined in the laboratory by ASTM Test Method D1557-70. The results of the compaction curves were: - Soil TY.E!s Descriwtion Maximum Drv Density (pcf) Optimum Moisture Content (percent) - A - B - C D - E - F - G Mottled gray-green SANDY SILT Light tan fine to medium SILTY SAND Mottled qray-brown CLAYEY SILT with SAND Gray-brown fine to medium CLAYEY SAND Light brown and qray CLAYEY SILT with SILTSTONE Gray-tan BASEROCK Mottled tan CLAYEY SILT with SAND 106.0 110.5 112.5 14.0 117.5 104.0 18.5 140.0 6.2 114.5 17.0 13.0 12.0 12.0 - Fifty-six (56) relative compaction tests were taken at random depths and locations within the trench backfills and the fill placed within the parking area. The test samples were obtained by the drive cylinder, sand volume and nuclear gauge methods (UBC Standard 70-4, 70-2 and 70-5). Testing of utility trenches was supplemented by probing those areas not tested to determine similarity in compaction. Results of the tests are given in Table I, and their locations are shown on the attached drawing. Job No. 689-215 - April 2, 1990 - - - - - - - - - - - - -. - - The Fox/Croft Partnership Page 3 CONCLUSIONS AND RECOMMENDATIONS Gradinq Based on our tests and observations, we conclude that the fill placed in the parking lot area has been compacted to a minimum of 90 percent of maximum density where shown on the attached drawing. Materials exposed at sub-grade throughout the parking lot area were found to be in substantial conformance with those assumed from previous reports and therefore, all recommendations presented in our Geotechnical update letter report for Lot 6 - Carlsbad Tract, 81-46 dated May 15, 1989 (Job No. 689-215) are still considered to be valid. Based on our tests and observations we conclude that the baserock placed in the parking lots and driveway areas was compacted to a minimum of 95 percent of maximum density where shown on the attached drawing. Where tests indicated compaction below the required 95 percent, the area was reworked, recompacted and checked by additional testing. Utility Trench Backfills Based on our tests and observations, we conclude that the storm drain, sewer and water line trench backfills tested have been compacted to a minimum of 90 percent of maximum density where shown on the attached drawing. Closure This report has been prepared in accordance with generally accepted geotechnical practices and makes no other warranties, either express or implied, as to the professional advice or data included. Moore & Taber izJza.&kti David J. Gaddie DJG/SfWj 4 Stanley H. Madsen Registered Civil Engineer 16569 (expires 6-30-93) Attachments: Plan Table I Disbursement: (2) Addressee (2) City of Carlsbad Job No. 689-215 - April 2, 1990 - MOORE & TABER GECITECHNICAL ENGiNEERS AND GEOLOtilSiS .- - - ,- - - - - - - - - - -. Test Test Number Date -_---_ _---_-__ 17A 10-06-89 18A 10-06-89 19A 10-09-89 20A 10-09-89 21A 10-09-89 22A 10-09-89 23A 10-25-89 24A 10-25-89 25A 10-25-89 26A 10-25-89 27A 10-26-89 28A 10-27-89 29A 10-27-89 30A 10-27-89 31A 10-27-89 32A nu 03-02-90 33A nu 03-02-90 34A nu 03-02-90 35A nu 03-02-90 36A nu 03-02-90 37A nu 03-02-90 38A nu 03-02-90 39A nu 03-19-90 40A nu 03-19-90 41A nu 03-19-90 42A nu 03-19-90 43A nu 03-19-90 44A nu 03-19-90 45A nu 03-19-90 46A nu 03-19-90 47A nu 03-19-90 48A nu 03-20-90 49A sv 03-20-90 50A nu 03-20-90 Test Depth (ft) ----- 1.5 1.5 1.0 1.0 1.0 1.0 4.0 4.0 4.0 4.0 2.0 3.0 2.0 2.0 2.0 1.0 1.0 0.5 1.0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Table I Maximum Moisture Dry Density Content Density (PCf) (%) (PCf) -----__ _------- __----- 117.5 15.6 107.4 117.5 14.9 107.4 110.5 15.6 103.5 110.5 16.6 101.7 110.5 18.3 103.6 106.0 18.0 98.0 112.5 14.0 104.4 112.5 14.2 105.1 112.5 14.9 106.2 112.5 14.2 102.1 112.5 14.6 105.0 112.5 14.4 104.1 104.0 16.5 98.4 112.0 14.9 105.8 112.5 14.5 103.8 112.5 17.9 107.3 112.5 15.5 106.5 112.5 19.2 103.6 112.5 16.4 105.7 112.5 15.9 100.9 112.5 16.1 101.5 112.5 16.2 103.7 117.5 11.1 116.8 117.5 14.0 110.4 117.5 13.9 110.2 117.5 14.3 109.6 117.5 11.5 117.0 117.5 14.1 111.1 117.5 11.9 109.0 117.5 11.5 116.4 112.5 15.4 107.1 112.5 18.1 103.7 112.5 19.7 111.5 117.5 15.9 108.7 Relative Compaction (%) ----__---- 91 91 94 92 94 92 93 93 94 91 93 93 95 94 32 95 95 92 94 90 90 92 99 94 94 93 100 95 93 99 95 92 99 93 Job No. 689-215 - April 2, 1990 A-l - - -. - - - - - -- - MOORE & TABER GEOTECHNICAL ENGINEERS AN0 GEOLOGiSTS Test Test Number Date ------ -------- 51A nu 03-20-90 0.5 117.5 17.1 107.2 91 52A nu 03-20-90 0.5 117.5 15.9 110.0 94 53A nu 03-20-90 0.5 117.5 16.0 106.5 91 54A nu 03-20-90 0.5 117.5 14.0 110.5 94 55A nu 03-20-90 0.5 117.5 15.6 107.7 92 56A nu 03-21-90 0.0 140.0 3.3 137.8 98 57A nu 03-21-90 0.0 140.0 3.2 136.2 97 58A nu 03-21-90 0.0 140.0 3.0 134.3 96 59A nu 03-21-90 0.0 140.0 3.9 137.0 98 60A nu 03-21-90 0.0 140.0 3.1 135.8 97 61A nu 03-21-90 0.0 140.0 3.4 133.8 96 62A nu 03-21-90 0.0 140.0 4.1 135.5 97 63A nu 03-21-90 0.0 140.0 4.4 133.6 95 64A nu 03-21-90 0.0 140.0 4.7 134.2 96 65A nu 03-21-90 0.0 140.0 3.5 136.8 98 66A nu 03-21-90 0.0 140.0 4.2 135.3 97 67A nu 03-27-90 1.4 114.5 13.9 104.5 91 68A nu 03-27-90 1.4 114.5 13.4 105.8 92 69A nu 03-30-90 8.0 140.0 7.1 130.0 93ckby#70A 70A nu 03-30-90 8.0 140.0 6.4 132.5 95 71A nu 03-30-90 8.0 140.0 7.3 130.2 93ckby#72A 72A sv 03-30-90 8.0 140.0 6.7 137.8 98 Test Depth (ft) ----- Table I (contld.) Maximum Moisture DrY Density Content Density (PCf) (%I (PCf) ------- -------- ------- Relative Compaction (%) -__------- (ck by 12) - signifies that this failing test area was reworked, .~ recompacted, and retested by test number 12 nu - indicates that this test is a nuclear test sv - indicates that this test is a sand volume test ..~. - Job No. 689-215 - April 2, 1990 A-2