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HomeMy WebLinkAboutCT 05-01; CRESCENT DEL SOL ESTATES; ROUGH GRADING REPORT; 2007-08-23COAST GEOTECHNICAL CONSULTING ENGINEERS AND GEOLOGISTS August 23, 2007 Crescent del So!, LLC. Wayne Blass President 7237 Sanderling Ct. Carlsbad, CA 92011 Subject: ROUGH GRADING REPORT PLAN CHECK NO. 06-0163 Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California Reference: Please see page 9 Dear Mr. Blass: In response to your request, we have performed field observations and testing during the rough grading phase on the above referenced property. The results of our density tests and laboratory testing are presented in this report. The geotechnical conditions observed in the subterranean garage excavation are in substantial conformance with those conditions anticipated in the Preliminary Geotechnical Report. Based on the results of our testing, it is our opinion that the fill was placed in an adequate manner and compacted to a minimum of 90 percent of the laboratory maximum dry density. 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. NAL Respectfully submitte BU& 0 FES / Io* NSIN COAST rt,sJ4, 4Jt ExP12-31O7) IL (1 782 . I I\ CERTIFIED 1*11 ENGINEERING 1 11 Mark Burwell, C.E.C\GEOLOGS2' Vithaya Sin et, Engineering Geologist Geotechnical ngin 4QFC 779 ACADEMY DRWE • SOLANA BEACH, CALIFORNIA 92075 (858) 755-8622 • FAX (858) 755-9126 - I. ROUGH GRADING REPORT I I Plan Check No. 06-0163 Crescent Del Sol Estates 234/236 Date Avenue I Carlsbad, California I I - - Prepared for: Crescent del Sol, LLC. Wayne Blass I President 7231 SanderlingCt. Carlsbad, CA 92011 I I I I I. I I I August 23, 2007 W.O. G-400123 Prepared by: COAST GEOTECHNICAL 779 Academy Drive Solana Beach, California 92075 Coast Geotechnical August 23, 2007 W.O. G-400123 Page 3 INTRODUCTION This report presents the results of our observations and field density, testing on the subject property during rough grading. The project included the excavation of the subterranean garage and the densification of the upper 2.0 to 3.0 feet of the Pleistocene terrace deposits exposed at the garage pad elevation. Temporary slopes up to 13.5 feet high were constructed at a gradient of 3/4 :1 (horizontal to vertical) or less. The approximate lOcations of field density tests are shown on the enclosed Grading Plan, prepared by bha, Land Planning and Civil Engineering. LABORATORY TEST DATA The laboratory standard for determining the maximum dry density was performed in accordance with ASTM D 1557-91. Field density tests were performed in accordance with ASTM D 1556. The results of the laboratory maximum dry density, for the soil type used as compacted fill on the site, is summarized below: Maximum Dry Density Optimum Description (p.c.f.) Moisture (%) Soil Type Tan to brown fine and 127.0 10.5 A medium-grained sand Whitish tan fine and medium-grained sand 112.0 11.0 B Coast Geotechnical August 23, 2007 W.O. G-400123 Page 4 GEOTECHNICAL CONDITIONS The property is underlain at relatively shallow depths by poorly consolidated Pleistocene terrace deposits. The terrace deposits are underlain at depth by Eocene-age sedimentary rocks which have commonly been designated as Santiago Formation on published geologic maps. The terrace deposits are covered by thin residual soil and minor fill deposits. DISCUSSION The grading contractor on this project was Bert Sims Grading. The following is a discussion of the general grading operations as they were performed on the project. The existing structures were demolished and disposed of offsite. The subterranean garage was excavated to a revised subgrade elevation of approximately 34.3 feet. The upper 2.0 to 3.0 feet of the garage subgrade deposits were removed and replaced as compacted fill. Removals were completed in sections and stockpiled. Stockpiled soils were generally mixed and placed in loose lifts of approximately 6.0 inches, moistened to near or above optimum moisture content and compacted. Compaction was Coast Geotechnical August 23, 2007 W.O. G-400123 Page 5 accomplished by track rolling with a Catapillar dozer and wheel rolling with a rubber tired loader. - Based on visual classification and previous laboratory testing, the fill deposits have a potential expansion in the low range. No evidence of significant adverse geologic structures was observed along the temporary cut slopes. Minor steeply dipping discontinuous fractures were observed. The limited planar fractures dip from 70 to 78 degrees out of slope. CONCLUSIONS AND RECOMMENDATIONS Based on selective testing, the fill was placed to a minimum of90 percent of the laboratory maximum dry density as suggested by our test results. Stability analyses suggests that temporary slopes constructed at an inclination of ~ :1 (horizontal to vertical) or less have a minimum static factor of safety of 1.25 for gross stability.. Although considered grossly stable, the Pleistocene sands are friable and subject to sloughing along the slope face. As previously-indicated, any structure within a horizontal distance equal to one half the height of the slope, measured from the top of the temporary slope, is subject to failure. . - I I Coast Geotechnical August 23, 2007 W.O. G-400123 Page 6 I 3) Due to the friable characteristics of the terrace deposits, the garage walls should be backfihled as soon as possible. In order to expedite this process, 3/4 inch crushed rock should be used to the maximum height possible. The gravel should be covered with filter fabric, Mirafi I 140N or equivalent. However, where concrete slabs or footings are proposed, they should be underlain by a minimum of 2.0 feet of compacted approved fill. The base of footings should be underlain by a minimum of 2.0 feet of compacted fill. The soil parameters recommended in the referenced Preliminary Geotechnical Investigation, Reference No. 1, and Revised Foundation Parameters, Reference No. 4, for foundations and retaining wall design remain valid. I The following pavement section is recommended for the proposed driveway: 5.0 inches of concrete on I 12 inches of compacted native soils I Subgrade soils should be compacted to the thickness indicated in the structural section and left in a condition to receive slabs on grade. Subgrade soils should be compacted to a ii minimum of 95 percent of their laboratory maximum dry density. The pavement section should be protected from water sources. Migration of water into subgrade deposits could result in pavement failure. Slabs on grade should be reinforced with No. 3 bars placed 16 inches on center in both directions. Slabs should be provided with saw cuts/expansionjoints, I as recommended by the project structural engineer. I Coast Geotechnical August 23, 2007 W.O. G-400123 Page 7 6) We recommend that all utilities be bedded in clean sand to at least one foot above the top of the conduit. The bedding should be flooded in place to fill all the voids around the conduit. Imported or on-site granular nonexpansive material compacted to at least 90 percent relative compaction may be utilized for backfill above the bedding. The invert of subsurface utility - excavations paralleling footings should be located above the zone of influence of these adjacent footings. This zone of influence is defined as the area below a 45 degree plane projected down from the nearest bottom edge of an adjacent footing. This can be accomplished by either deepening the footing, raising the invert elevation of the utility, or moving the utility or the footing away, from one another. Positive site drainage should be maintained at all times. Water should be directed away from foundations and not allowed to pond or seep into the ground or migrate under concrete flatwork or pavement sections. All the recommendations in the referenced Preliminary Geotechnical Investigation which are not superseded by this report remain valid and should be implemented during the construction phase. Coast Geotechnical I August 23, 2007 W.O. G-400123 Page 8 LIMITATIONS I ,. I Th ap pla 1 suc Its I Th I is office assumes no responsibility for any alterations made without our knowledge and written rova1, subsequent to the issuance of this report. All areas of disturbance which require the cement of compacted fill to restore them to the original condition, will not be reviewed unless h backfi!ling operations are performed.under our observation and tested for required compaction. hould be noted that density (compaction) testing is conducted on a very small volume of the fill. e intent is to provide an opinion, based on selective testing and observation during fill placement. 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. Enclosures: Table I Grading Plan Coast Geotechnical August 23, 2007 W.O. G-400123 Page 9 REFERENCES PRELIMINARY GEOTECHNICAL INVESTIGATION Proposed Eleven (11) Unit Condominium I 236 Date Avenue. Carlsbad, California Prepared by Coast Geotechnical I Dated February 4, 2004 I .. GEOTECHNICAL REVIEW OF PROPOSED DEVELOPMENT Eight (8) Single Family Residences 236 Date Avenue I Carlsbad, California Prepared by Coast Geotechnical Dated April 4, 2005 I SUPPLEMENTAL GEOTECHNICAL INVESTIGATION Proposed Eleven (11) Unit Condominium I 236 Date Avenue Carlsbad, California I Dated Prepared by Coast Geotechnical September 28, 2005 .4) REVISED FOUNDATION DESIGN PARAMETERS I Crescent Del Sol Estates 234/236 Date Avenue Carlsbad, California I Prepared by Coast Geotechnical Dated January 11, 2006 I 5) FOUNDATION PLAN REVIEW - PLAN CHECK NO. 06-0163 Crescent Del Sol Estates I . .234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical I Dated February 16, 2006 Coast Geotechnical August 23, 2007 W.O. G-400123 Page 10 GEOTECI{NICAL UPDATE LETTER - PLAN CHECK NO. 06-0163 Crescent Del So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechnical Dated February 16, 2006 GRADING PLAN REVIEW Crescent Del So! 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 So! Estates 234/236 Date Avenue Carlsbad, California Prepared by Coast Geotechniôa! Dated November 22, 2006 /7 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 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 Coast Geotechnical August 23, 2007 W.O. G-400123 I - Page!! I 11) TEMPORARY SLOPES - Crescent Del Sol Estates 234/236 Date Avenue I Carlsbad, California - Prepared by Coast Geotechnical - Dated August 22, 2007 I FIELD TEST RESULTS I H TABLE I Field Dry Density and Moisture Content Moisture Dry Relative I Test Test Approx. Content Density Soil Date No. Location Elevation % (pcf) Compaction Type 8/03/07 1 See Map 33.2' 13.0' 110.1 96 B I 8/03/07 2 See Map 33.2' 12.7' 108.3 94 B 8/03/07 3 See Map 33.2' 11.2 109.1 95 B I 8/08/07 4 See Map 33.2' 10.3 118.3 93 A I 8/08/07 5 See Map 33.2' 9.7 121.1 95 A 8/08/07 6 See Map 33.2' 9.9 116.8 92 A I 8 /13/07 7 See Map 33.2' 10.6 116.1 91 A I 8/13/07 8 See Map 33.2' 10.9 119.3 94 A 9 See Map 31.0' 8.4 104.1 Native I 8/13/07 - 8/13/07 10 See Map 31.0' 9.0 104.1 - Native I 8/16/07 11 See Map 34.2' 10.9 118.5 93 A 8/16/07 12 See Map 34.2' 9.8 116.5 92 A 1 8/16/07 13 See Map 34.2' 9.3 115.9 91 A I 8 /16/07 14 See Map 34.2' 8.5 118.3 93 A 8 /16/07 15 See Map 34.2' 9.8 118.9 94 A G-400123 I (TO REMAIN) rw d7.8 46. .46. rW 4Z9 WALL BY SEPARATE rG 46.5 - - PN 2 ___ EXISTING RETAIl/INC WALL JT -frLOING LlN1h / (TO REMAIN) (TN 53.4) S - / /FFELEV.- 70 / 7G46.2 (PG 47.7 ---- / BUILDING / \ 'f 440 HOA EASEMENT ' rd DRAIN/ 455 LIMITS ABOVE SEEARcIL MWALL BY SEPARA TE ASONRY RETAINING RA p45 6T / BUILDING LIMITS—N 11 0 PLANS UNIT6-A 0 \ 0 / ØZFFELEV=47.0 UNIT / t . - 46.5AP/\J 206-08O 24 /UNIT 68 PP ELEV=47 BU'LDIN LIMIT - PG 45.3 TG 452 /FP ELEV.=470 - densified) UNIT INSTALLI8XIS B OS 12 LIGH TRAFFIC Y 'N/ / r E.Ev.-4 .0 9 IN BROOKS BOX • TG 45.0 / PRO I & FLOW I.E. OUT 30.4 - I . 42.05 LIMIT Of7 .GUA FILTER . I.E. OUT HANG / \ - -13 46.51 /0 1 4 9 3D I\ G453 \ \ I 2 Ayy I OR S I L~NE - ?c s-; o6 I ITW 465 45.3 SI4T 5 I_31 - I - Tr '' So INL T W/GRATE R KS TG 4.4' 6.2 UNFT/2 / -- TW 45.5 I - . - . L it IN 43.4 I FF ELE A47O . I . PG 35 0 - P 5 \ /' °ç- BUILDING 741T I I IE43 7 \ TW45....-FL44 i5FG465.\ .\FG4J.5 PRIVATE 12 STORM TW 45 ' I\V 1 Qt- -- - I - - PROTECT<\ il •- . . \ (densified) Ti- 8 \ API'] 206 0 EXISTING WALL 4 jj!~ ff TG 46.21 ABOVE GARAGE FL 452 FO~ DRAINAGE Zr L GAPA L,\ ARCHITECTURAL °'WMI T .1'74.67 RWY- 4 4 R "- -c S 0 TIP 45 p _-7L 44 2 / UNØ 1Q4 SIDE WAL/( UNDER A/N - I 46 J PP çtEV470 I 45 PER 0-2> FL 398 -FG-7 pST/- E4-FILTER I FLUSH DECOR CONCRETE S \/. \_S /S437 ' 40 RASSYSWALc__ I PER ARCHITECT PLANS \\%I' \S FG 465 p DETAIL $ r 2 AP'\J 206-080-09 TIV'45 . \IQS H° GETA - :-- IFC 4.5 MASONRY RETAINING A - WALL BY, SEPA RA TE-- W 485 PERMIT '/4/l 1, OVERHEAD A- - - INSTALL TYP' ' CS rQt \ 9' - - - ' -- JG 45.5 PERO 5 0 (2' COR I.E. 4a92 cO INE VeEC. . .. 485 13Y -. H. IOUT 4059 —?4 - \ T 0 IL \ISTING PG 456 - - \ I C IC ipa IT/LE 00 I A- B—RS (10) - --iT --- , WATER ME rL (i 922) - - ) ImPRO MEN T PLANS SEE~ OVE CT r 47.47 NG ExIS1 5 Exis~;Nl' CURE: 0'T TER ''STIHGNO r0GE OF 2, 206-09-09. AC P"VrMENT 0,72 00 y XI$TIHG EXISTING CROSS APj\1 205-oqJ- API'] 20 10 0 40 60 GRADING PLAN SCALE: 1"=40' (reduced) LEGEND 01 DENSITY TEST (approx.) 73 LIMIT OF FILL (approx.) GEOLOGIC UNITS - . af ARTIFICIAL FILL Qs RESIDUAL SOIL Qt TERRACE DEPOSITS COAST GEOTECHNICAL G-400123