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Home My WebLink AboutCT 05-01; CRESCENT DEL SOL ESTATES; FINAL GEOTECHNICAL REPORT; 2009-12-16I COAST GEOTECHNICAL CONSULTING ENGINEERS AND GEOLOGISTS December 16, 2009 Crescent Del So!, LLC. Wayne Blass President 7237 Sanderling Ct. Carlsbad, CA 92011 Subject: FINAL GEOTECHNICAL REPORT Crescent Del Sol Estates 234/236 Date Avenue - Carlsbad, California References: Please refer to page 8 Dear Mr. Blass: This report has been prepared at your request and presents the results of our observations and testing during the rough grading and construction phases on the above referenced property. The geotechnical conditions encountered during grading and footing excavations for residential development are in substantial conformance with those conditions anticipated in the Preliminary Geotechnical Investigation. Grading and construction aspects, where documented, are in substantial conformance with the recommendations of the Preliminary Geotechnical Investigation and supplemental reports. Based on the results of selective testing, the fill deposits in the subterranean parking area, driveway, utility line backfill and portions of retaining wall backfill were adequately placed and compacted to a minimum of 90 percent of the laboratory maximum dry density. The control of drainage and irrigation is essential to the future performance of the structures. If you have any questions, please do not hesitate to contact us at (858) 755-8622 This opportunity to be of service is greatly appreciated. - I I I Respectfully submitted, COAST GEOTECHNJJ ell, 2109 (II 'V- Exp. Rdd 5/31/10 CERTIFIED ) ) 1kt &J! GEOLOGIST ENGINEERINGMark B * Vithaya Singhant, PJ" *41 Engineerin Geologist Id Geotechnical Engineer FC 779 ACADEMY DRIVE • SOLANA BEACH, CALIFORNIA 92075 (858) 755-8622 • FAX (858) 755-9126 SIN - 782 Exp. 12-31-09 FINAL GEOTECHNICAL REPORT Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared for: Crescent Del Sol, LLC. Wayne Blass President 7237 Sanderling Ct. Carlsbad, CA 92011 December 16, 2009 W.O. G-400123 Prepared by: COAST GEOTECHNICAL 779 Academy Drive Solana Beach, California 92075 Coast Geotechnical December 16, 2009 W.O. G-400123 -I Page 3 INTRODUCTION This report presents a summary of geotechnical observations and testing conducted on the site during the rough grading and construction phases. The general contractor for the project was Diversified Construction and the grading contractor was Burt Simms Grading. Geotechnical observation and testing was conducted on an on-call basis for documented aspects of the project from July 18, 2007 through March 23, 2009. GEOTECHNICAL CONDITIONS The property is underlain at relatively shallow depths by poorly consolidated Pleistocene terrace deposits that are correlated with the Bay Point formation on published geologic maps. The terrace deposits are underlain at depth by Eocene-age sedimentary rocks which have commonly been designated as the Santiago Formation on published geologic maps. The terrace deposits are covered by thin residual soil and minor fill deposits. These surficial deposits were removed or recompacted during the grading and construction phases on most of the site PROJECT SUMMARY The project included excavation of a subterranean garage up to 13.5 feet bçlow existing grade. Temporary slopes were constructed at a gradient of 3/4:1 (horizontal to vertical) or less, as discussed in the referenced reports. Survey points were established on the existing property line retaining wall by BHA, project civil engineering firm, in the northeastern portion of the site. Subsequent surveying Coast Geotechnical December 16, 2009 W.O. G-400123 Page 4 of the points by BHA indicates that no movement occurred along the wall due to excavation of the temporary slopes. The upper 2.0 feet to 3.0 feet of the Pleistocene terrace deposits'. exposed along the garage subgrade were removed and replaced as compacted fill. Density test results, as well as a general discussion of the grading operations are addressed in the referenced Rough Grading Report, dated August 23, 2007. The storm drain system was subsequently constructed along the garage subgrade. The excavated granular deposits were used as trench backfill above the 3/4 inch rock bedding. The backfill was placed in 8.0 inch lifts, moistened as required to near optimum moisture content, and compacted with a sheepsfoot attached to a tractor-mounted backhoe and hand operated compaction equipment. Selective testing suggests the backfill deposits were compacted to a minimum of 90 percent of the laboratory maximum dry density. The results of the laboratory testing and field density tests are plotted on the enclosed grading plan, prepared by BHA, Land Planning and Civil Engineering. Upon completion of storm drain trench backfill, the footings for the proposed garage walls and column pads were excavated in the lower garage pad. The footing excavations along the lower garage pad were observed by this firm, as documented in the various footing excavation observation reports referenced in this report. I Coast Geotechnical December 16, 2009 W.O. G-400123 Page 5 A limited amount, approximately 2.0 feet, of garage wall backfill was placed prior to construction of the first floor post-tensioned slab, as per suggestions of Collons+Smith, project structural engineers. Upon completion of the post-tensioned slab, the wall backfill was continued. Backfill was placed in loose lifts of approximately 8.0 inches, moistened to near optimum moisture and compacted. Compaction was accomplished with a Bobcat and hand operated compaction equipment. The lower 10± feet of wall backfill was tested by this firm, however, the upper 3.0 feet of wall backfill was not tested per the request of the owner. The completion of a wall backfill report by this office was declined by the owner. Density testing along the lower wall backfill deposits suggests the backfill was compacted to a minimum of 90 percent of the laboratory maximum. Additional utility line backfill testing was conducted along Date Street, per the request of the city of Carlsbad. Testing included the sewer, line, storm drain, water line and gas/electric line connections along Date Street. It should be noted that some of the utility line backfill testing was limited to subgrades only, as requested by the city of Carlsbad. The results of the majority of our field density tests are shown on Table II. The approximate location of the tests are shown on the enclosed Grading Plan. The driveway subgrade deposits, as well as the adjacent geogrid Keystone wall backfill were tested by this firm (see referenced report dated March 10, 2009). The driveway subgrade deposits were scarified, moistened as required and compacted to a minimum of 95 percent of the laboratory maximum dry density. The 5.0 inch thick driveway slab was cast directly on the densified subgrade deposits, as recommended. Coast Geotechnical December 16, 2009 W.O. G-400123 Page 6 CONCLUSIONS AND RECOMMENDATIONS The geotechnical conditions encountered during the grading and construction phases are in substantial conformance with those conditions anticipated in the Preliminary Geotechnical Investigation. Observation and selective testing of fill deposits suggests that the areas observed and documented during grading were compacted to a minimum of 90 percent of the laboratory maximum dry density. Selective testing suggests that utility line backfill, where observed and tested, was adequately compacted. Drainage systems were not designed by this firm. However, it is suggested that all drainage devices be cleaned and maintained prior to winter rains to ensure they are functioning properly. Irrigation should be limited to that amount necessary to sustain plant life. Slabs on grade should be protected from water migrating under concrete flatwork. Enclosures: Laboratory Test Data Field Density-Test Results Grading Plan (Garage Level)' Coast Geotechnical December 16, 2009 W.O. G-400123 Page 7 LIMITATIONS Although the major aspects of construction were conducted in general conformance with the recommendations of the Preliminary Geotechnical Report and supplemental reports, several areas of the project were not observed or tested by this firm. These areas include but are not limited to the upper 3.0 feet of garage wall backfill, subgrades for concrete flatwork (except as documented), exterior improvements, site walls, property line walls, as well as finished grading. Coast Geotechnical and its engineers and geologists cannot be responsible for any fill areas, as well as subsequent construction not observed and/or tested and specifically approved by this office. It should also be noted that some degree of concrete cracking occurs as a result of shrinkage in slabs on grade. These shrinkage cracks are considered normal and should be expected as concrete cures. This offiëe assumes no responsibility for any alterations made without our knowledge and written approval, subsequent to the issuance of this report. All areas of disturbance which require the placement of compacted fill to restore them to the original condition, will not be reviewed unless such backfihling operations are performed under our observation and tested for required compaction. This study has been provided solely for the benefit of the client and is in no way intended to benefit or extend any, right or interest to any third party. This study is not to be used on other projects or extensions to this project except by agreement in writing with Coast Geotechnical. Coast Geotechnical December 16, 2009 W.O. G-400123 Page 8 REFERENCES PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Eleven (11) Unit Condominium 236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated February 4, 2004 GEOTECHNICAL REVIEW OF PROPOSED DEVELOPMENT Eight (8) Single Family Residences 236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated April 4, 2005 SUPPLEMENTAL GEOTECHNICAL INVESTIGATION Proposed Eleven (11) Unit Condominium 236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated September 28, 2005 REVISED FOUNDATION DESIGN PARAMETERS Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated January 11, 2006 FOUNDATION PLAN REVIEW PLAN CHECK NO. 06-0163 Crescent Del Sol Estates 234/236 Date .Avenue Carlsbad, California Prepared by Coast Geotechnical Dated February 16'2006 Coast Geotechnical December 16, 2009 - W.O. G-400123 Page 9 GEOTECHNICAL UPDATE LETTER - PLAN CHECK NO. 06-0163 Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated February 16, 2006 GRADING PLAN REVIEW Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated February.27, 2006 UPDATED FOUNDATION PLAN REVIEW - PLAN CHECK NO. 06-0163 Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated November 22, 2006 REVISION NO. 2 UPDATED FOUNDATION PLAN REVIEW PLAN CHECK NO. 06-0163 Crescent Del Sol Estates 234/236 Date Avenue • Carlsbad, California Prepared by Coast Geotechnical Dated May 31, 2007 GEOTECHNICAL CONSTRUCTION ISSUES Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated July 2, 2007 Coast Geotechnical December 16, 2009 W.O. G-400123 Page 10 FOUNDATION REDESIGN Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated July 27, 2007 REVISED FOUNDATION PLAN REVIEW PLAN CHECK NO. 06-0163 Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated August 21, 2007 TEMPORARY SLOPES Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Pàted August 22, 2007 ROUGH GRADING REPORT PLAN CHECK NO. 06-0163 Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated August 23, 2007 NOTICE OF FOOTING EXCAVATION OBSERVATION Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated September 12, 2007 Coast Geotechnical December 16, 2009 W.O. G-400123 Page!! TEMPORARY SLOPES Stairway Wall Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated October 9, 2007 NOTICE OF FOOTING EXCAVATION OBSERVATION Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated October 30, 2007 FIELD MEMO Sand Blanket Garage Slab Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated October 31, 2007 REVISED TEMPORARY SLOPES Stairway Wall Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated November 1, 2007 NOTICE OF FOOTING EXCAVATION OBSERVATION Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated November 6, 2007 Coast Geotechnical December 16, 2009 W.O. G-400123 Page 12 FIELD MEMO Sand Equivalent Test Sand Blanket Garage Slab Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated November 6, 2007 UTILITY TRENCH BACKFILL OBSERVATION Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated November 19, 2007 NOTICE OF FOOTING EXCAVATION OBSERVATION Western Staircase Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated April 3, 2008- FIELD MEMO Backfill Under Slab Extensions Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated July 7, 2008 NOTICE OF FOOTING EXCAVATION OBSERVATION Western Driveway Wall Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated November 12, 2008 Coast Geotechnical December 16, 2009 W.O. G-400123 Page 13 NOTICE OF FOOTING EXCAVATION OBSERVATION Eastern Driveway Wall Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated January 7, 2009 DRIVEWAY SUBGRADE TESTING AND GEOGRID REINFORCED WALLS Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated March 10, 2009 GEOTECHNICAL SERVICES Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated June 18, 2009 NC O-S I LABORATORY AND FIELD TEST RESULTS The laboratory standard for determining the maximum dry density was performed accordance with ASTM D 1557-91. Field density tests were performed in I in accordance with ASTM D 1556. TABLE I Maximum I . Dry Density. Optimum Description (p.c.f.) Moisture(%) Soil Type 1 Tan to brown fine and 127.0 10.5 A medium-grained sand . Whitish tan fine and medium-grained . I sand 112.0 11.0 B Import - Brown fine I . and medium-grained sand, slightly silty 129.0 11.0 C I . TABLE II .I Field Dry Density and Moisture Content Approx. moisture • Dry Relative Test Test Height Content Density % Soil I Date No. Location Of Fill (pc f) Compaction Type I 8/28/07 lsd See Map 2.0' 10.9 120.2 95 A 8/29/07 2sd See Map 2.5' 9.8 119.5. 94 A I ; 8/29/07 3sd See Map 2.0' 9.3 121.6 96 A I 8/29/07 4sd See Map 2.0' 10.7 119.5 94 A (Page lof 2) I I . I TABLE II (Continued) Field Dry Density and Moisture Content I Approx. Moisture Dry Relative Test Test Height Content Density % Soil Date No. Location Of Fill % (pc f) Compaction Type 8/31/07 5sd See Map S.G. 8.3 110.0 98 B 8/31/07 6sd See Map S.G. 9.2 110.8 99 B 8/31/07 7sd See Map S.G. 9.1 119.3 94 A I 3/06/08 8sd See Map 2.0' 9.8 126.5 98 C I 3/17/08 9w1 See Map 2.5' 9.1 118.2 93 A 12/11/08 lOs See Map S.G. 10.9 122.1 96 A I 12/13/08 us See Map 20' 12.7 120.4 95 A 12 /13/08 12s See Map S.G. 11.9 122.8 97 A :1 I Note: sd = storm drain wi = water line S = sewer line I I I (Page 2 of 2) I .1 \ ,i V APN 206-080#3 206-080-14, \\ /2fëbj8O1 \ 2O6o9O46 APN 206O8O39 20 10 0 I — 20 440 60 PEG 7 jr 14 % 'tJ .\ \ \ ?t .'• /' r _-Ar - 6 p r \ 6 Ail S cJ FN O8-8O\_., - f's \ '— ; GRADING PLAN I s .APN 2OS- GARAGE LEVEL N SCALE 1"=40' (reduced) V 5S_S S ol DENSITY TEST (approx.) I 6 APN-2OO8O31 f - - - SEE TAU 7W 5 A. \ 1; im /2APN 206OD08 rG 06sd - APN 20608099\ - V \ \ \ L (OH) 5+00 - 55 ) 5' 5 (QH) () S rAs \u\ 44.0 GA As - GRASSY- FIL TER PR DETAIL iEET2. - s' (S) - \ - - Cs) (5) \ '•' •S - S S I S. S 206-091-12 ARN 06 APN A 208 17 -091-01 S S COAST GEOTECHNICAI G-400123