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Home My WebLink About; Proposed Western Structure Ocean Point/Harbor Dr; As-Graded Geotechnical Report; 2000-10-06PHONE (619) 280-4321 TOLL FREE (877) 215-4321 F A X (619) 280-4717 P.O. Box 600627 San Diego, CA 92160-0627 6280 Riverdale Street San Diego, CA 92120 www.scst.com AS-GRADED GEOTECHNICAL REPORT PROPOSED WESTERN STRUCTURE OCEAN POINTE HARBOR DRIVE CARLSBAD, CALIFORNIA PREPARED FOR: REGIS HOMES. L.P. 18825 BARDEEN AVENUE IRVINE, CALIFORNIA 92612-1520 PREPARED BY: SOUTHERN CALIFORNIA SOIL AND TESTING, INC. 6280 RIVERDALE STREET SAN DIEGO, CALIFORNIA 92120 Providing Professional Engineering Services Since 1959 PHONE (619) 280-4321 TOLL FREE (877) 215-4321 FAX (619) 280-4717 P.O. Box 600627 San Diego, CA 92160-0627 6280 Riverdale Street San Diego, CA 92120 www.scst.com October 6, 2000 SCS&T 9911144-9 Regis Homes, L.P. 18825 Bardeen Avenue Irvine, California 92612-1520 Subject: AS GRADED GEOTECHNICAL REPORT PROPOSED WESTERN STRUCTURE OCEAN POINTE HARBOR DRIVE, CARLSBAD, CALIFORNIA Reference: 1) "Update Report, Proposed Ocean Pointe Harbor Drive, Carlsbad, California;" (SCS&T 9911144, Report No. 8R) - 2) "Basement Subdrain and Moisture Barrier Recommendafions, Exisfing Structure Ocean Pointe, Harbor Dri\e, Carlsbad, California;" {SCS&f 9911144, Report No. 7R) 3) "Report of Geotechnical Investigation, Windsong Shores;" Southem California Soil and Tesfing, Inc.; March 15,1988 (SCS&T 8821027, Report No. 1). Dear Ladies and Gentlemen: In accordance with your request, this report has been prepared to present the results of field ' observafions and tesfing performed in conjuncfion with the earthwork construction at the subject site. Our services were performed between September 20 and September 27, 2000. The earthwork construction was performed by McGrath Grading of San Diego, California. The site was cut to elevafions as indicated on the grading plans by Crosby Mead Benton & Associates, dated September 27, 1989. SITE DESCRIPTION AND PROPOSED DEVELOPMENT The project site is a rectangular shaped parcel surrounded by the railroad tracks to the west, Agua Hedionda Lagoon to the south. Harbor Drive to the east and Maya Street to the north. Grading was performed to^provide a building pad forthe basement parking garage portion ofthe proposed structure. Ocean Pointe October 6, 2000 SCS&T No. 9911144-9 Page 2 SITE PREPARATION PRIMARY EQUIPMENT: The primary equipment employed for the site mass grading operafion included: 1 - Caterpillar 950 Loader 1 - Water truck 1 - Caterpillar 150 Motor grader 1 -Caterpillar D8 Dozer CLEARING AND GRUBBING: Site preparafion began with the clearing and grubbing of the existing vegetation and matter detrimental to the proposed development froni the areas to be graded. The detrimental material generated from the operafions was exported from the site. GRADING: Grading for the proposed structure consisted mainly of creating a subterranean excavation to accommodate the proposed basement garage. The removed soils were exported from the site. Soils exposed in the basement excavation consisted primarily of natural terrace deposits. Portions of the cut pad were disturbed during grading and relatively minor fill was placed in some areas due to undercutfing, which occurred during grading (depths ranging from three to 18 inches). These materials were moisture condifioned and compacted, with field density tests indicating a minimum of 90 percent relafive compaction, determined in accordance with ASTM D 1557-91. Compaction was achieved by means of a Caterpillar 950 rubber tire loader or other heavy construcfion equipment. TEMPORARY CUT SLOPE: Temporary cut slopes exposed terrace deposits and were cut back at a 1.5:1 (horizontal to vertical) rafio. Each slope vras evaluated by our engineering geologist and indications of instability were observed. Temporary cut slopes were constructed along the west and south sides of the basement excavation. A shoring system consisting of "H" beams and wooden lagging was utilized along the northern and eastern sides ofthe excavation due to space limitafions. SUBDRAINS: As indicated in the referenced report 9911144-8R, it is recommended that a subdrain system be installed within the basement of the subject building to reduce the potenfial for the ponding of water beneath the structure, and possible resultant moisture intrusion problems. However, due to the fact that the basement subgrade surface did not intercept the contact between the terrace deposits and the underlying Santiago Formation, as previously anticipated, it appears that the subdrain system required may be less extensive than that recommended for the existing eastern building (see Reference 2). Design recommendations for the subdrain for the western building should be provided after thefooting excavations have been observed and a better understanding of the configuration of the terrace deposits/Santiago Formation contact is obtained. Ocean Pointe October 6, 2000 SCS&T No. 9911144-9 _^ Page 3 FIELD OBSERVATION AND TESTING Field observation and density tests were performed by a representative of Southern California Soil and Tesfing, Inc., during the mass grading operafions. The density tests were taken according to ASTM D 2922-91 (nuclear gauge). The results of those tests are shown on the attached plates. The accuracy of the in-situ density test locations and elevations is a function of the accuracy of the survey control provided by other than Southern California Soil and Tesfing, Inc. representafives. Unless othenwise noted, their locations and elevafions were detennined by pacing and hand level methods and should be considered accurate only to the degree implied by the method used. As used herein, the term "observation" implies only that we observed the progress of work we were involved with, and performed field density tests, which in conjunction with our observation was the basis for our opinion as to whether the work was performed in substantial conformance with the geotechnical recommendafions and the requirements ofthe applicable agencies. LABORATORY TESTS Maximum dry density determinafions were performed on representafive samples ofthe soils used in the compacted fills according to ASTM D1557-91, Procedure A and C. Procedure A is used when the soil contains 20% or less by weight of material retained on the #4 sieve. This procedure specifies that a four (4) inch diameter cylindrical mold of 1/30 cubic foot volume be used and that the soil tested be placed in five (5) equal layers with each layer compacted by twenty-five (25) blows ufilizing a 10-pound hammer with an 18-inch drop. Procedure C is used when the soil contains more than 20% by weight of material is retained on the 3/8" sieve and less than 30% by weight is retained on the 3/4" sieve. This procedure specifies that a six (6) inch diameter cylindrical mold of-1/13 cubic foot volume be used and thatthe soil tested be placed in five (5) equal layers with each layer compacted by fifty-six (56) blows utilizing a 10-pound hammer with an 18-inch drop. The results of these tests, as presented on Plate Number 2, were used in conjuncfion with the field density tests to determine the degree of relative compaction of the compacted fill. AS-BUILT GEOLOGY Based on the results of on-site geological observation, the following conclusions are presented: 1) The geological condifions exposed at the site were generally found to be similar to thoise described in the referenced geotechnical reports, although the elevafion of the terrace deposits/Santiago Formation contact is somewhat lower than expected in some areas. Ocean Pointe October 6, 2000 SCS&T No. 9911144-9 Page 4 2) The grading recommendations presented in the referenced report and those recommended during the grading appear to ha\e been followed. . 3) All temporary cut slopes were observed and no adverse geological conditions were observed. 4) In our professional opinion and to the best of our knowledge, all known adverse geologic conditions have been sufficiently mitigated and the site appears to be geologically suitable for the proposed construction. REMAINING WORK The following operations remain to be completed. It is recommended that field observafions and relative compaction tests be perfomied during these operafions to verify that these operafions are performed in accordance witbjob requirements and local grading ordinances. . The backfilling ofthe basement retaining vralls; . The backfilling ofthe underground utilities trenches. •, A subdrain system to be constructed in the basement subgrade soils CONCLUSIONS Based on our field observafions and the in-place density test results, it is the opinion of Southern California Soil and Testing, Inc. that the grading work was performed substanfially in accordance with the recommendations contained in the referenced geotechnical reports, the City of Carisbad grading ordinance, the Phase I grading plan, and the Uniform Building Code. Minimum recommendations for the design of the foundations, as presented in the referenced report, remain applicable. For jour convenience these recommendations are presented below. FOUNDATIONS GENERAL: Shallow foundations may be utilized for the support of the proposed structure. The footings should have a minimum depth of 24 inches below the lowest adjacent finish pad grade. A minimum width of 12 inches and 24 inches is recommended for confinuous and isolated footings, respectively. A bearing capacity of 4000 pounds per square foot (psf) maybe assumed for said foofings. This bearing capacity may be increased by one-third when considering wind and/or seismic forces. Foofings located adjacent to or within slopes should be extended to a depth such that a minimum distance of seven feet exists between the bottom of the footing and the face of the slope. Retaining walls in similar condifions should be extended to a depth such that a minimum distance often feet exists between the bottom ofthe footing and the face of the slope. la i^8^ Ocean Pointe October 6, 2000 SCS&T No. 9911144-9 ^ Page 5 REINFORCEMENT: Both exterior and interior continuous foofings should be reinforced with at least two No. 4 bars positioned near the bottom of the footing and at least two No. 4 bars posifioned near the top of the foofing. This reinforcement is based on soil characterisfics and is not intended to be in lieu of reinforcement necessary to safisfy structural considerafions. FOUNDATION EXCAVATION OBSERVATIONS: All foofing excavafions should be observed by a member of our engineering/geology staff to verify that the foundation excavafions ^end into a suitable bearing stratum. EXPANSIVE CHARACTERISTICS: The prevailing foundation soils were found to be non- detrimentally expansive. The recommendations contained in this report are applicable to this condition. ON-GRADE-SLABS INTERIOR CONCRETE SLAB-ON-GRADE: Concrete slabs-on-grade should have a thickness of at least four inches and be reinforced with at least No. 3 reinforcing bars placed at 18 inches on center each way. Slab reinforcement should be placed approximately at mid-height ofthe slab and extend at least six inches down into the footings. Due to the sandy nature of the basement subgrade soils, no sub-slab sand layer is required. Due to the fact that moisture-sensitive flooring will not be placed on the parking garage floor slab, a moisture banier membrane, such as visqueen, is also not required. However, the client should be aware that the garage floor slab may be more susceptible to moisture-related effects, such as efflorescence, if visqueen is not utilized SETTLEMENT CHARACTERISTICS: The anticipated total and/or differenfial settlements for the proposed structure may be considered to be within tolerable limits, provided the recommendations presented in this report are followed. It should be recognized that minor cracks normally occur In concrete slabs and foundafions dUe to shrinkage during curing or redistribution of stresses and some cracks may be anficlpated. Such cracks are not necessarily an indicafion of excessive movement. LIMITATIONS This report covers only the services performed between September 20 and September 27,2000. Our opinions presented herein is based on our observations and the relafive compaction test results and is limited by the scope of the services which we agreed to perform. Our services were performed in accordance with the currently accepted standard of practice and in such a manner as to provide a reasonable measure ofthe compliance ofthe grading operations with the job requirements. No warranty, express or implied, is given or intended with respect to the Ocean Pointe SCS&T No. 9911144-9 October 6, 2000 Page 6 services which we have performed, and neither the performance of those services nor the submittal of this report should be construed as relieving the contractor of his responsibility to conform with the job requirements. If you should have any questions regarding this report, please do not hesitate to contact this office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, SOUTHERN CALIFORNIA SOIL Reviewed by: Mike P. Farr, C. E. G. #1938 Certified Engineering Geologist MPF:DBA:sd (5 )Submitted (1) Cityof Carlsbad OTNG.INC. 1^ ENGt'^ti:- •' / spanielB. Adfler, R.^ GB KU^'^'/^/Vice presicfept, Principal JOB NAME: Ocean Pointe JOB NUMBER: 9911144 IN-PLACE DENSITY TESTS TEST ELEVATION MOISTURE DRY DENSITY SOIL REL.COMP. NO. DATE LOCATION (feet,MSL) (percent) (p.cf.) TYPE (percent) #VALUE! 1 9/27/00 NE Comer, Upper Pad 39.5 5.6 122.8 2 97.8 2 9/27/00 SW Comer, Upper Pad 39.0 5.6 113.1 2 90.1 3 9/27/00 NE Corner, Lower Pad 38.0 9.8 105.8 3 88.2 4 9/27/00 Mid-South, Lower Pad 34.5 6.0 123.4 2 98.3 5 9/27/00 Middle, Lower Pad 34.5 7.1 119.9 2 95.5 6 9/27/00 NW Corner, Lower Pad 34.5 9.2 123.6 2 98.5 7 9/27/00 RETEST OF 3 38.0 9.4 110.7 3 92.3 MAXIMUM DENSITY AND OPTIMUM MOISTURE SUMMARY (ASTM D1557) Soil Type 1 2 3 Soil Description Tan to Red, Slightly Silty Sand Red-Brow^n, Silty Sand Tan, Slightly Silty Sand Maximum Densitv. pcf 104.9 125.5 120.0 Optimum Moisture. % 9.4 8.5 12.3 PLATE NO. 2