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HomeMy WebLinkAboutCT 81-46; Carlsbad Airport Center Unit 2 Lot 37; Soils Report; 1990-12-11EWGINEERI#8 GEOTECHNICAL EVALUATION AND COMPACTION TESTING, SITE REGRADING CARISBAD AIRPORT CENTER, UNIT 2, LOT 37 CARLSBAD, CALIFORNIA FOR 1921 PAIDMAR OAKS WAY, SUITE 310 HONOUR CONSTRUCTION CARLSBAD, CALIFORNIA 92008 W.O. 1261-SD DECEMBER 11, 1990 GeoSofls, Inc. 7- f -W9l - - Geotechnical Engineering Engineering Geology - 5741 Palmer Way * Carlsbad, California 92008 (619) 438-3155 SFAX 1619) 931-0915 W.O. 1261-SD December 11, 1990 HONOUR CONSTRUCTION Carlsbad, California 92008 1921 Palomar Oaks Way, Suite 310 Attention: Mr. J. H. Honour, Jr. Subject : Geotechnical Evaluation and Compaction Testing, Site Regrading Carlsbad Airport Center, Unit 2, Lot 37 Carlsbad, California Reference: "Foundation Investigation Carlsbad Airport Center Unit 2, Lot 37 Carlsbad", dated August 6, 1990, by ICG Incorporated Gentlemen: This report presents a summary of ~ our evaluation. of the previously placed fill and the results of the observation and testing services provided by GeoSoils, Inc. during regrading of Lot 37, in Unit 2 of the Carlsbad Airport Center, Carlsbad, California. The purpose of regrading was to construct a level building pad at the desired elevation for the proposed commercial/industrial concrete tilt-up structure and associated loading docks, traffic lanes and parking areas. HONOUR CONSTRUCTION W.0. 1261-SD DECEMBER 11, 1990 PAGE 2 Site DescriDtion The subject site is a roughly rectangular shaped lot and is free of vegetation. Lot 37 is bounded on the south by Kellogg Avenue, on the north by Palomar Airport and on the east and west by similar vacant parcels. The previous phase of earthwork construction was completed in February of 1990, under the observation and testing services of ICG, Incorporated. SOIL ENGINEERING On Lot 37, the scope of the services provided by GeoSoils, Inc. were two fold evaluate the previous fill and observation and compaction testing for the import materials. As such, each is discussed separately. Fill Evaluation Subsurface conditions were explored by excavating four backhoe test pits to depths of between 1.5 and 10 feet. Field exploration was performed on December 3, 1990 by one of our staff geologists, who logged the test pits, performed in place density and moisture tests and obtained samples of representative fill materials for laboratory testing. The approximate location of the exploratory test pits are indicated on the enclosed Geotechnical Map (Plate 1) which utilizes the l1I=3O1 site plan prepared by Bodas Engineering Inc. as a base. CeoSoils, Znc. HONOUR CONSTRUCTION W.O. 1261-SD DECEWBER 11, 1990 PAGE 3 As the test pits were excavated, field density tests were performed at approximately 2 foot vertical intervals. These test methods were utilized to evaluate in-situ moisture and density of the fill material. Field density tests were performed using the sand cone method (ASTM D-1556-82) or nuclear density method (ASTM D-2922-81 and ASTM D-3017-78). The test results were compared to the laboratory maximum dry density and optimum moisture content of representative soil types to determine in place relative compaction of the materials tested. Visual classification of the soils in the field or direct correlation were the basis for determining which optimum moisture content and maximum dry density values to use for a given density test. The test results are presented in Table 1 at the end of this report. ~~ Based on our exploratory test pits, field and laboratory testing, review of ICG, Incorporated daily field testing reports and review of the referenced report dated August 6, 1990 by ICG, Incorporated the following discussion is presented. Observation of the exploratory test pits indicated that adequate removals were made and proper benching was performed as the contact between bedrock and fill materials were relatively flat lying and distinct. Field testing results indicated that all but one test met or exceeded the minimum 90 percent relative compaction standard. A test in TP-1 at a depth of one foot indicated a 89 percent relative compaction. This is likely due to GeoSoils, Inc. HONOUR CONSTRUCTION W.O. 1261-SD DECEMBER 11, 1990 PAGE 4 the affects of surface weathering, expansion and desiccation. Prior to additional fill being placed on-site, this area was reprocessed and recompacted to the minimum relative compaction standard. Both cut and fill slopes have performed satisfactorily to date. However, these slopes are being heavily irrigated. Consideration should given to providing only the amount of water necessary to maintain plant life. Irrigation should be minimized and overwatering avoided. ICG, Inc. states in their August 6, 1990 report that; "Based on our previous work and the present investigation, the fill is considered suitable for support of structural loads, although, it is highly expansive." ~~ Based upon our evaluation and review of the other available data, it is our opinion that the previously placed fill was compacted in general accordance with the typical standards of practice utilized in the industry today. Site Resradinq Preparation of Existing Ground and Fill Placement 1. The surface soils were scarified, moisture conditioned as necessary to achieve adequate moisture content, and recompacted. GeoSoils, Inc. HONOUR CONSTRUCTION W.O. 1261-SD DECEMBER 11, 1990 PAGE 5 2. To facilitate excavation in the back stairway and loading dock area (see Plate 1 for location) the below grade volcanics were blasted to an approximate depth of 10f feet. Subsequently, this area was cut to finish grade: no overexcavation of the shot rock was made. During excavation for the back stairway and loading dock, all loose below grade material should be excavated to competent material. Fill should be placed and compacted to proposed grade in accordance with the project geotechnical engineers recommendations. 3. Fill placed under the purview of this report consisted of the reprocessed existing fill and imported soils which were placed in thin lifts, moisture conditioned as necessary to -achieve adequate"moisture-~ content and " compacted. Field Testing 1. Field density tests were performed using the sand cone method (ASTM D-1556-82) and the nuclear density method (ASTM D-2922-81 and ASTM D-3017-78). The test results are shown in Table 11. The estimated locations of the field density tests are shown on Geotechnical Map, Plate 1, which uses the lt1=30' scale site plan prepared by Bodas Engineering Inc., as a base map. Based on our observations, the test results are considered representative of the compacted fill. GeoSoils, Inc. HONOUR CONSTRUCTION W.O. 1261-SD DECEMBER 11, 1990 PAGE 6 2. Field density tests were taken at maximum vertical intervals of two feet. 3. Visual classification of the soils in the field was the basis for determining which maximum density value to use for a given density test. LABORATORY TESTING The laboratory maximum dry density and optimum moisture content for each of the major soil types was determined according to test method ASTM D-1557-78. The following table presents the test results: Maximum Dry Optimum Moisture Soil "me Densitv. Dcf Content % A-Yellow fine to medium sand 122.0 B-Yellow gray silty fine sand 118.5 C-Yellow gray silty fine sand 113.0 E-Yellow brown silty sand D-Yellow gray silty fine sand 117.0 117.0 11.5 14.5 17.0 15.5 14.5 DISCUSSION Based upon our evaluation of the previously placed fill materials review of work performed by others and the observation and testing services provided by GeoSoils, Inc. during site regrading, it is our opinion that the proposed development of Lot CeoSoils, fnc. HONOUR CONSTRUCTION W.O. 1261-SD DECEMBER 11, 1990 PAGE 7 37 in Unit 2 of the Carlsbad Airport Center is feasible from a geotechnical standpoint. Two primary items that need to be considered during site development are; the on-site expansive soils and the need to remove loose, blasted material in the areas of back stairway and the loading docks. The limits and depth of this material should be ascertained during construction. If desired, specific recommendations concerning the geotechnical aspects of design and construction could be provided upon request. Drainase Positive site drainage should be maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. Pad drainage should be directed toward the street or other approved area. Due to the nature of on site soils, combined with the hardness and permeability of the bedrock, local areas of seepage may develop due to irrigation or heavy rainfall. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this could be provided upon request. CeoSofls, Znc. HONOUR CONSTRUCTION W.O. 1261-SD DECEMBER 11, 1990 PAGE 8 LandscaDe Maintenance Water is known to weaken the inherent strength of all earth materials and cause soil expansion. Only the amount of irrigation necessary to sustain plant life should be provided. Over watering the landscape areas could adversely affect proposed site improvements. REGULATORY COMPLIANCE AND LIMITATIONS The materials encountered on the project site and utilized in our laboratory study are believed representative of the area: however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. -~ ... . ". ~ . .. . ~- .~ ~. ~. ~~ . . ~. .~ .~ . . ~~ ~~ Since our study is based upon the site materials observed, selective laboratory testing and engineering analysis, the conclusion are professional opinions. Cuts, fills, and processing of original grade under the purview of this report have been completed under the observation of, and with selective testing by GeoSoils, Inc. are found to be in compliance with our recommendations, as required by the City of Carlsbad. Our findings were made in conformance with generally accepted professional engineering practices and no further GeoSofZs, Znc. HONOUR CONSTRUCTION W.O. 1261-SD DECEMBER 11, 1990 PAGE 9 warranty is implied nor made. This report is subject to review by the controlling authorities for this project. This opportunity to be of service is sincerely appreciated. If you should have any questions regarding this report, or if we may be of further service, please do not hesitate to call. Very truly yours, GeoSoils, Inc. aff Engineer Geotechnical Engineer RCS/VS/mc Enclosures: Table I, Field Density Test Results for the previously placed fill Table 11, Field Density Test Results Plate 1, Compaction Test Location Map for fill tested by GeoSoils, Inc. cc: (4) Addressee GeoSoiZs, Inc. PROJECT MAHE: CARLSBAD AIRPORT CENTER, UMIT 2. LOT 37 CLIENT: HOMOUR COYSTRUCTIOM TABLE I FIELD DEMSITY TEST RESULTS U.O. 1261.913 DATE: 12/90 Dry Relative Date of Moisture Density Compaction Test Soil Test Test Location Elevation (X) (DCf) (X) TYDe TYDe 12-03-90 MOTE: TP-1 TP-2 TP-3 TP-3 TP-3 TP-3 TP-4 TP-4 TP-4 -1.0' -1.0' -2.0' -4.0' -6.0' -8.0' -7.0' -4.0' -6.01 15.0 15.3 17.7 20.5 17.0 17.7 14.9 18.4 18.7 105.7 107.9 103.9 101.5 105.2 107.3 108.7 107.4 107.3 FIELD DEMSITY TEST TAKEN IM THE PREVIOUSLY PLACED FILL. SC= SAM0 COME TEST MD= MUCLEAR DEMSITY GAUGE TEST GeoSoils, Inc. a9 91 ND ND 8 92 8 ND 92 C 93 ND C NO 95 C sc C 93 ND 92 sc D 92 ND D D PROJECT NAME: CARLSBAD AIRPORT CENTER. UNIT 2. LOT 37 CLIENT: HONOUR CDYSTRUCTIOY TABLE 11 FIELD DENSITY TEST RESULTS Y.D. 1261-50 DATE: 12/90 Dry Relative Date of Test moisture Density Compaction Test Soil Test NO Test Location Elevation (2) (Ref) f 2) TyDe TYDe 12-05-90 1 SE CORNER PAD 310.0' 11.9 114.8 94 2 S PAD 310.0' 14.7 107.9 92 3 W PA0 311.0' 14.8 107.1 91 4 MID PA0 311.0' 15.3 107.3 92 12-07-90 5FG S PAD 6FG N PA0 7FG MID PA0 FG 12.8 108.1 92 FG 11.9 115.6 95 FG 12.4 108.2 92 NOTE: SC= SAND CONE TEST FIELD DENSITY TESTS TAKEN IY THE IMPORTED FILL MATERIALS. YD= NUCLEAR DENSITT GAUGE TEST ND A ND E NO E SC E ND E NO A SC E CeoSoiIs, Znc.