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Home My WebLink AboutCT 81-46; AIRPORT BUSINESS CENTER; REPORT OF GEOTECHNICAL SERVICES; 1988-02-03Cl- '1-4(' AA MOORE & TA B E R GEOTECHNICAL ENGINEERS AND GEOLOGISTS 4530 EAST LA PALMA AVENUE ANAHEIM, CALIFORNIA 92807 (714) 779-2591 ADDITIONAL OFFICES SAN DIEGO BAI<ERSFIELD REPORT OF GEOTECHNICAL SERVICES Office Building Carlsbad Airport Business Center Lot 13 & 14, Tract 81-46 Corner of Palomar Airport Road and Palomar Oaks Way Carlsbad, California CLIENT Opus Southwest Corporation M 0 0 R E & TA B E R GEOTECHNICAL ENGINEERS AND GEOLOGISTS REPORT OF GEOTECHNICAL SERVICES Introduction This report presents the results of our field observations and tests performed during recent grading operations within Lots 13 and 14 of the Carlsbad Airport Business Center (Carlsbad Tract 81-46). This grading was performed in order to create a building pad for the proposed office building and bring the parking and drive areas to rough subgrade elevation. These soils engineering services were conducted in compliance with a request by Mr. Gary Moss representing Opus Southwest Corporation. Initial grading of Lots 13 and 14 was performed in conjunc- tion with mass grading of Carlsbad Tract No. 81-46 - Airport Business Center, Unit I as described .in our Report of Geotechnical Services dated February 25, 1987. A site specific geotechnical review of Lots 13 and 14 regarding the proposed Office Building was presented in our Geotechnical Investigations, Carlsbad Airport Business Center, Carlsbad Tract 81-46, Unit No. I, Lots 13 and 14, dated October 16, 1986 (Job No. 186-118). Grading Procedures The recent grading was performed during January 1988. Earthwork consisted of minor cut and fill placement operations within the previously graded lot in order to create a building pad for the proposed office building, and to obtain rough grade elevations within the proposed parking and driveways. Site preparation included the removal of. vegetation and unsuitable materials. No other surface or subsurface obstructions were encountered. I Subsequent to observation of site preparation by a geotechni- cal representative of this firm, the exposed ground surface, in areas to receive fill, was scarified, moisture conditioned and compacted to a depth of at least eight (8) inches. Soils used as I fills were obtained on the site and were essentially free of organic matter or objectionable debris. Fill materials were spread in thin lifts, moisture conditioned and compacted by I sheepsfoot rolling. The maximum depth of newly placed compacted fill is in the entry drive at the northwest portion of Lot 13 and is about four and a half (4.5) feet. The office building pad is located in cut and was brought to design elevation by excavation into bedrock. Surficial materials exposed at pad grade were moisture conditioned and compacted. Job No. 688-203 - February 3., 1988 -2- I M 0 0 R E & TA B E R GEOTECHNICAL ENGINEERS AND GEOLOGISTS The approximate location and elevation of the filled ground are shown on. the attached plan. The drawing is a modification -of grading plan prepared by The McIntire Group, dated November 24, 1987. S Testing Maximum dry density and optimum moisture content of the representative soils used to construct the fills were determined in the laboratory by ASTM Test Method D1557. The results of the compaction curves were: Maximum Optimum Type Description Dry Density Moisture Content (pcf) (percent) A Tan Fine to 110.5 13.0 medium SILTY SAND B Tan SILTY SAND 116.5 13.0 A total of seven (7) field moisture-density tests were taken on the site during fill placement operations to determine relative compaction. Fill soils were tested using the nuclear gauge method, as described in ASTM publications. Results Of the relative compaction tests are presented below and test locations are shown on the attached drawing. Test Test Test Maximum Moisture Dry Relative Number Date Elev. Density Content Density Compaction (ft) (pcf) (%) (pcf) (%) .1 1-28-88 159 110.5 18.4 103.0 93 2 1-28-88 159 110.5 15.5 103.0 93 3 1-29-88 161 110.5 13.7 103.8 94 4 1-29-88 163 116.5 16.0 107.3 92 5 2-01-88 156 116.5 13.8 . 105.0 90 6 2-01-88 156 116.5 15.5 104.8 90 7 2-01-88 163 116.5 14.6 106.0 91 Job No. '688-203 - February 3, 1988 -3- M 0 0 R E & TA B E R GEOTECHNICAL ENGINEERS AND GEOLOGISTS An expansion test was performed on a typical sample of surf icial slab subgrade soil in accordance with the standard procedure for Expansion Index Test (UBC Standard 29-2). The results are shown below: Initial Test No. Dry Density (pcf) E-1 105.1 Initial Moisture Content Expansion (%) (%) Index 11.1 0.4 4 CONCLUSIONS AND RECOMMENDATIONS Grading Accepted construction practice and testing procedures were followed during the grading operations. It is our opinion that the fill was placed and compacted in conformance with the project. plans and specifications, the City of Carlsbad Grading ordinance, and the recommendations contained in our previously referenced geotechnical report. The site soil and bedrock conditions were found to be in general conformance with those assumed in our previous reports. Based on our observations and tests, it is concluded that the existing ground was properly prepared as required. Representative, field tests indicate the fill materials were compacted to a minimum of 90 percent relative compaction at the locations shown on the attached drawing. This report describes geotechnical services provided during rough grading of the subject lot. Additional construction involving earthwork, such as utility trench backfill, pavement subgrade, etc., may require geotechnical observation and testing. Notification should be given to the soils engineer prior to commencement of this work in order to schedule these geotechnical services. Expansive Soils Based on our field observations and the results of the Expansion Index Test performed ona typical sample of the on-site soil, it is concluded that the on-site soils are essentially non- expansive, therefore, special recommendations for expansive soil conditions are not considered necessary. Job No. 688-203 - February 3, 1988 -4- I MOORE & TAB ER GEOTECHNICAL ENGINEERS AND GEOLOGISTS Foundations All continuous footings should be reinforced with the equiva- lent of two No. 4 bars, one placed near 'the top and one near the bottom. All footings should be placed a minimum of two feet into bedrock. Footings located within ten feet of the top of slope, should be deepened one foot for every three feet of encroachment toward the top of the slope or be imbedded a minimum of two feet into bedrock, whichever is greater. Footing excavations should be observed and approved by a geotechnical representative of this firm prior to placing reinforcement. Providing the above recommendations are followed, footings 'placed on undisturbed bedrock may be design for a maximum allow- able static bearing pressure of 6500 psf.' Slabs The on-site soils are essentially non-expansive and therefore reinforcement of concrete slabs-on-grade for expansive soil conditions in not necessary, however, reinforcement of slabs for other factors, as determined by the Structural 'Engineer may be required. Where interior fixtures, such as carpet or floor tile, may be adversely affected by moisture, it is recommended that"a moisture barrier be placed below the slab. Drainage Positive 'drainage of surface water away from the structures and to the parking and drive areas is very important. No water should be allowed to pond at any location. Where slabs or pavement are not feasible adjacent tothe buildings, the ground surface should be provided with a minimum gradient of three percent to a distance of five feet away from the structure. Water should be transported off the site in approved drainage devices or unobstructed swales with a gradient of at least one percent. Job No. 688-203 - February 3, 1988 -5- MOORE & TAB ER GEOTECHNICAL ENGINEERS AND GEOLOGISTS General Conditions 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 in it. The report is based on the project as described and the data obtained in the field or from referenced documents. This report has not been prepared for use by parties or projects other than those named or described above. ....... c.,. , - r9" Reviewed by Dugald R. Campbel]( ic Registered Civil Engineer 1812i . (Expires 6-30-89) Locations of Field Tests plan C................ Distribution (4) Client - (2) City of Carlsbad . (2) Field Office - Opus Southwest Corp. Job No. 688-203 - February 3, 1988 I I MOORE & TABER Walter M. Christian WMC/ DRC/ lb Attachments: I I I . I I 1 I 1 I I, I I I I I. I . I ---- SCALE cr cr cc cr PROPOSED OFFICE BUILDING if LOT 13, TRACT 81-46 CARLSBAD AIRPORT BUSINESS PARK J CARLSBAD, CALIFORNIA LOCATION OF FIELD TESTS / MOO RE a TA B E R Engineers - Geologists / DRAFT. APPROV. DATE JOB N9 LMB 2-2-88 688-203 PLATE I