The URL can be used to link to this page

Home My WebLink AboutCT 79-14; Birtcher Business Center; Soils Report; 1980-10-09- ROBERT PRATER ASSOCIATES Coosultiog Soil, Foundotion B Geological Eogineerr -. - - - - - .- - - - October 9. 196L 304-lA, 3605 Birtcher Pacific 27611 La Paz Road Laguna Niguel, California 92677 Attention: Messrs. Andy Youngquist and Charles Gore Gentlemen: In accordance with your request we are providing earthwork observation and testing services for the subject project. A geotechnical investigation for the entire Unit 1 portion of the business park was performed by our predecessor firm the results of which were presented in a report dated February 26, 1974. In addition, soil and foundation engineering recommendations for the subject site were presented in our report dated August 23, 1979. Pavement design recommendations were presented in our report dated September 2, 1980. Commencing on July 8, 1980, our representatives have been present at the site to observe the earthwork operations and to provide field density testing services as required. The results of our field density and laboratory compaction tests performed in connection with the mass grading operations are presented in the attached Tables A and B, respectively. The approximate locations of the field density tests are in- dicated on the attached Site Plans, Figures 1 and 2. Based on our observations and the attached test results, it is our opinion that the fill soils placed and compacted in connection with the mass grading operations for building pads A through K on Lot 10 (see Figures 1 and 2) and the rough grading for Lots 1 through 9 and 11 (except for the southwest corner of Lot 1 in the vicinity of the construction trailer where an area measuring approximately 20 by 40 feet in plan dimensions was not filled) were compacted to a minimum degree of compaction of 90 percent as determined SlOlO .13.31 Ll - - October 9, 1980 304-lA, 3605 Page 2 - - - - .- by ASTM test designation D 1557-78. The site preparation work included the removal and recompaction of a wet area in the vicinity of Building Pad D on Lot 10. Based on our observations and the results of laboratory expansion tests presented in the attached Table C, the soils exposed at the finish subgrade level on the building pads constructed in Lot 10 possess a high potential for expansion; the pads were not capped with non-expansive fill soil as recommended in our report dated August 23, 1979. In lieu of providing a 24-inch minimum thickness of compacted non-expansive fill beneoth slabs-on-grade, the effects of the expansive soil condition may be mitigated by moisture conditioning and recompacting the potentially expansive soil at the sub- grade surface and reinforcing the slabs. We recommend that the potentially expansive soil be 1) scarified to a depth of 18 inches below the finished subgrade surface, 2) moisture conditioned to a minimum of 3 percent above the laboratory optimum water content, and 3) compacted to a minimum of 85 percent of the laboratory maximum dry density (ASTM D 1557-78) just prior to placement of the visqueen vapor barrier. If a visqueen vapor barrier is not utilized the water content of the moisture conditioned soil layer should be maintained by some other-method, such as frequent sprinkling, until the floor slabs are poured. In addition, the slabs should be reinforced with 6x6-6/6 welded wire fabric placed at the midheight of the slab. Because of the expansive soil conditions, footings for the proposed buildings should be founded at least 24 inches below the lowest adjacent finished grade. All continuous footings should be reinforced with two No. 4 reinforcing bars both top and bottom. Work remaining at the site which will require additional earthwork inspection and testing services includes 1) moisture conditioning of the potentially expansive soils present on the building pads in Lot 10, 2) the placement and compaction of utility and storm drain trench backfills which are underway at this time, 3) the placement and compaction of retaining wall backfills, 4) the preparation and compaction of the pavement subgrade soils to 95 percent relative compaction, and 5) the placement and compaction of the pavement base rock layer. In addition, the completion of the mass grading for Lot 1 (as mentioned previously) and any future finish grading operations on Lots 1 through 9 and Lot 11 will require earthwork inspection and testing services. - Our services consist of professional opinions and recommendations made in accordance with generally accepted soil and foundation engineering principles and practices. This warranty is in lieu of all other warranties, either express or implied. - If you have any questions, please call. Very truly yours, - - JLB:cn Attachments - Copies: Addressee (3) Henry Worley Associates, Attn: Mr. Henry Worley (1) City of Carlsbad, Attn: Mr. Emile Plude (1) I I I I I I I I I I I I I I I 1 I I 304-1A TABLE A - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556-64 and/or ASTM D2922-78, ASTM D3017-78) Test No. Date of Test 1 7/!30/80 2 7/30/80 3 7/‘30/80 4 7/31/80 5 7/31/80 6 7/31/80 7 7/31/80 8 7/31/80 .9 8/01/80 10 8/O l/80 11 8/01/80 12 8/01/80 13 8/01/80 14 8/01/80 15 8/01/80 16 8/01/80 17 8/04/80 18 8/04/80 19 8/04/80 20 8/04/80 Test Location Lot 7 Lot 7 Lot 7 Lot 7 Lot 7 Lot 7 Lot 8 Lot 8 Lot 9 Lot 7 Lot 7 Lot 8 Lot 9 Lot 8 Lot 9 Lot 9 Lot 9 Lot 10 Lot 7 Lot 9 Approximote Elevation (Feet) 224 225 227 229 231 233 237 239 241 231 235 241 241 243 241 243 245 239 237 247 Water Content 13 11 16 26 23 21 19 22 21 18 22 21 18 17 23 24 21 21 20 25 b Density (pcf) 98.9 102.0 96.3 99.5 98.0 101.1 97.1 101.1 95.4 100.3 99.1 100.0 97.1 99.7 100.1 101.7 94.8 98.0 99.1 100.0 Degree of Compaction 90 92 94 90 89 91 94 91 84 91 90 90 88 90 90 92 92 94 90 90 Compaction Curve No. Remarks 1 1 2 1 1 Test failed, see #lo 1 2 1 1 Test failed, see #15 1 Retest of #5 1 1 1 Test failed, see if15 1 1 Retest of #9 and #13 1 2 4 1 1 Notes: 1) “Compaction Curve No. ” refers to Table B. 2) Unless otherwise noted elevations shown are to nearest foot. I I I I I I 1 I I I I / I I I I ) I I 304-1A TABLE A - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556-64 and/or ASTM D2922-78, ASTM D3017-78) Test No. Date of Test 21 8/04/80 22 S/05/80 23 8/05/80 24 8/05/80 25 S/OS/SO 26 8/05/80 27 8/05/80 28 8/05/80 29 8/06/80 30 8/06/80 31 8/06/80 32 8/06/80 33 8/06/801 34 8/06/80 35 8/06/80 36 8/07/80 37 8/07/80 38 8/07/80 39 8/07/80 40 8/07/80 Test Location Lot 10 Lot 9 Lot 9 Lot 1 Lot 6 Lot 1 Lot 6 Lot 1 Lot 2 Lot 2 Lot 2 Lot 2 Lot 2 Lot 3 Lot 2 Lot 3 Lot 2 Lot 3 Lot 3 Lot 10 Approximate Woter DV Degree of Elevation Content Density Compaction (Feet) (“4 (pcf) (%I 241 22 94.2 91 249 24 94.4 91 251 19 98.6 90 237 17 96.6 93 237 16 93.2 90 239 17 93.3 90 240 18 95.4 92 242 24 100.5 91 252 17 93.1 90 254 17 100.3 91 256 19 96.9 88 256 18 99.5 90 258 20 99.8 90 264 17 103.1 93 260 20 94.7 91 266 19 99.1 90 262 18 103.4 93 268 27 99.6 90 270 23 101.9 92 243 20 96.9 93 Compaction Curve No. Remarks 4 4 1 4 4 4 4 1 4 1 1 Test failed, see #32 1 Retest of x31 1 1 4 1 1 1 ! .4 dotes: I) “Compaction Curve No.” refers to Table B. 2) Unless otherwise noted elevations shown are to nearest foot. I I I I I I I I I I I I I I 304-llA I I I TABLE A - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556-64 and/or ASTM D2922-78, ASTM D3017-78) Test No. Date of Test 41 8/08/80 42 8/l l/80 43 8/l l/80 44 8/l l/80 45 8/l l/80 46 8/l 2/80 47 8/l 2/80 48 8/l 2/80 49 8/l 2/80 50 8/l 3/80 51 8/l 3/80 52 8/l 3/80 53 8/l 3/80 54 8/l 3/80 55 8/l 3/80 56 8/l 3/80 57 8/l 3/80 58 8/l 3/80 59 8/l 3/80 60 8/l 3/80 Test Location Lot 10 Lot 10 - Pad K Lot 10 - Pad E LotlO-PadK Electrical Trench Backfill - Corte Del Cedro Lot 11 Lot 11 Lot 11 Lot 11 Lot 11 Lot 11 Lot 9 Lot 9 Lot 9 Lot 8 Lot 8 Lot 7 Lot 7 Lot 2 Lot 2 Approximate Water DV Elevation Content Density (Feet) (“4 & 245 23 95.2 247 17 98.3 245 19 95.7 249 18 92.7 220 23 92.6 257 20 96.5 93 4 259 22 95.5 92 4 261 17 109.0 95 6 262 19 103.1 93 1 264 24 94.7 91 4 262 19 93.8 90 4 253 (FSG) 21 96.0 92 5 251 (FSG) 23 96.6 93 5 250 (FSG) 17 98.6 90 9 243 (FSG) 21 99.0 90 9 243 (FSG) 16 96.0 92 5 237 (FSG) 16 103.2 94 9 236 (FSG) 18 93.8 90 5 260 (FSG) 16 98.4 90 9 263 (FSG) 21 98.0 94 5 Degree of Compaction (%, 92 95 92 90 90 Compaction Curve No. 4 4 4 2 2 Remarks \lotes: 1) “Compaction Curve No.” refers to Table 8. 2) Unless otherwise noted elevations shown are to nearest foot. 3) “FSG” denotes finish subgrade elevation. I I I I 1 I 1 / I I I I I ’ ;&A I I I TABLE A - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556-64 and/or ASTM D2922-78, ASTM D3017-78) Approximate Water Test Elevotion Content No. Date of Test Test Location (Feet) (“W 61 8/l 3/80 Lot 3 270 (FSG) 17 62 8/l 3/80 Lot 3 273 (FSG) 22 63 8/l 4/80 Electrical Trench Backfill - 222 19 Corte Del Cedro 64 S/15/80 Lot 10 242 22 65 8/l 5/80 Lot lo-PadD 244 20 66 8/l 5/80 Lot lo-PadD 246 20 67 8/l 8/80 Lot 10 - Pad D 247 20 68 8/l 8/80 Lot 10 248 20 69 8/2 l/80 Lot 6 245 (FSG) 18 70 8/21/80 Lot 6 243 (FSG) 20 71 8fJ l/e0 Lot 1 245 (FSG) 16 72 8/2 l/80 Lot 1 246 (FSG) 17 73 8/25/80 Lot lo-PadJ 252 (FSG) 19 74 8/‘25/80 Lot IO-Pad J 252 (FSG) 13 75 S/2 5/80 Lot IO-Pad K 251 (FSG)’ 15 76 8/‘.25/80 Lot 10 -Pad K 251 (FSG) 13 77 8/‘25/80 Lot 10 - Pad I 250 (FSG) 12 78 8/25/80 Lot IO-Pad1 250 (FSG) 10 79 8/2 5/80 Lot lo-PadF 248 (FSG) 13 80 8/2 5/80 Lot lo-PodG 248 (FSG) 15 \lotes: 1) “Compaction Curve No.” refers to Table B. 2) Unless otherwise noted elevations shown are to nearest foot. 3) “FSG” denotes finish subgrade elevation. DV Degree of Density Compaction (pcf) (W 95.8’ 92 98.7 90 98.3 96 Compaction Curve No. 5 9 2 98.9 90 9 99.3 91 9 97.3 93 5 94.2 90 5 94.3 90 5 100. T 91 9 97.8 94 5 102.3 93 9 103.6 95 9 99.9 91 9 102.1 93 9 102.1 93 9 107.4 97 1 102.3 93 9 99.3 91 9 97.4 93 5 99.2 91 9 Remorks Test No. 81 82 83 84 85 86 87 88 / I I I I I I I I I I I I I I I I I I 304-1A TABLE A - SUMMARY OF FIELD DENSITY TEST RESULTS (ASTM D1556-64 and/or ASTM D2922-78, ASTM D3017-78) Approximate Water Dry Degree of Elevation Content Density Compaction Compaction Date of Test Test Location (Feet) (“N (pcf) &I Curve No. Remarks 8b5/80 LotlO-PadG 248.(FSG) 13 105.9 96 1 8/?5/80 Lot 10 - Pad G 248 (FSG) 15 103.1 93 1 8/2 5/80 Lot 10 - Pad E 248 (FSG) 15 103.7 94 1 8/25/80 Lot 10 - Pad E 248 (FSG) 15 102.0 92 1 8/2 8/80 LotlO-PadC 250 (FSG) 16 94.9 91 5 8/28/80 Lot lo-PadC 250 (FSG) 18 95.5 92 5 8/z 8/80 Lot 11 266 (FSG) 16 96.4 93 5 8/28/80 Lot 11 266 (FSG) 17 95.0 91 5 \lotes: 1) “Compaction Curve No. ” refers to Table B. 2) Unless otherwise noted elevations shown ore to nearest foot. 3) “FSG” denotes finish subgrade elevation. - - - - - - - - - - - - - - - - 304-1A TABLE B LABORATORY COMPACTION TEST RESULTS (ASTM 01557-78) Compaction Test Description of (Curve)No. Material 1 2 3 4 5 6 7 8 9 SANDY CLAY (SC), greenish yellow CLAYEY and SANDY SILT (MH), tan SANDY CLAY (SC), brown CLAYEY SILT VW, grey CLAYEY and SANDY SILT (MH), brown SILTY SAND (SM), brown SILTY SAND WV, way SILTY SAND (SW, way CLAYEY SILT (ML), cm source of Material On-site Maximum Optimum Dry Density Water Content (pcf) (%I 110.5 17.3 On-site 102.7 15.5 On-site On-site On-site 116.0 12.5 103.7 104.2 18.6 20.7 On-site Import Import On-site 115.0 108.0 112.0 109.5 14.0 13.0 13.5 17.3 - _ 304-1A TABLE C RESULTS OF -SWELL TESTS Water Water Content Content Sample Initial Before After Surcharge Elevation Dry Density Sob&an Saturation Pressure Swell Lot No. (FSG) (PCf) (W ra . (Pd) w 2 109.3 1.9 27.9 144 15.5 10 - Pad A 97.5 3.5 30.5 144 11.6 10 - Pad C 101.9 8.5 30.7 144 8.1 10 - Pad F 99.4 7.5 33.9 144 15.5 - - - - - - - - - - - -