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HomeMy WebLinkAboutCT 03-01; LA COSTA RESORT; GEOTECHNICAL UPDATE; 2005-05-19'e--'-"""-; '~',~v",:,'>l .,.." M -. . ,,-.. ,-................ ,,"'-.... Siadden Engineering 6782 Stanton Avenue, Suite A, Buena Park, CA 90621 (714) 523-0952 Fax (714) 523-1369 114 South California Avenue, Beaumont, CA 92223 (951) 845-7743 Fax (951) 951-845-8803 39-725 Garand Lane., Suite G, Palm Desert, CA 92211 (760) 772-3893 Fax (760) 772-3895 May19,2005 (Revised 7-15-05) La Costa Resort and Spa c/o KSL Development Corporation 2100 Costa Del Mar Road Carlsbad, California 92009 ' Subject: Project: Geotechnical Update Proposed Driving Range Renovation La Costa Resort & Spa Costa Del Mar Road Carlsbad, California Project No. 544-2063 ! 05-05-116 I Ref: Geotechnical Investigation Report prepared by Sladden Engineering dated June 7,: 2002, Project No. 544-2063, Report No. 02-06-343. ' As requested, we have reviewed the referenced Geotechnical Investigation report as it relates to, the proposed driving range renovation project. The project site is located on the northeast corner: of El Camino Real and Costa Del Mar Road in the City of Carlsbad, California. The driving range: is located adjacent to the La Costa Resort Hotel. - The referenced,Geotechnical Investigation report includes recommendations for the design and, construction of the various resort improvements that should be applicable to the proposed' driving ,range renovation. Based upon our review of the referenced report and our previous site! observations, it is our opinion that the recommendations included ill the above referenced report; remain applicable for the proposed driving range. i The foundation design recommendations should be applicable to any miscellaneous structures: included within the driving range. Footings should extend at least 18 inches beneath lowest: adjacent grade. Isolated square or rectangular footings at least 2 feet square may be designed' I using an allowable bearing value of 2500 pounds per square foot. Continuous footings at least 12, inches wide may be designed using an allowable bearing value of 2000 pounds per square foot.i Allowable increases of 200 psf for each additional 1 foot of width and 250 psf for each additional~ 6 inches of depth may be utilized if desired. The maximum allowable bearing pressure should be: 3000 psf. The allowable bearing pressures are for dead and frequently applied live loads and; may be increased by 1/3 to resist wind, seismic or other transient loading. : CID~-ol Fi [e#fq ~ r ! d z, ~ o UJ :J: o Z « ...I c. , i~ ; May 19, 2005 (Revised 7-15-05) -2- • Project No. 544-2063 i 05-05-116 ; The recommendations made in the preceding paragraph are based on the assumption that all : footings will be supported by properly compacted soils. Prior to the placement of the reinforcing: steel and concrete, we recommend that the footing excavations be inspected in order to verify: that they extend into the firm compacted soils and are free of loose and disturbed materials. Settlements may result from the anticipated foundation loads. These estimated ultimate, settlements are calculated to be a maximum of 1 inch when using the recommended bearing values. As a practical matter, differential settlements between footings can be assumed as one-· half of the total settlement. These elastic settlements are expected to occur during construction. Resistance to lateral loads may be provided by a combination of friction acting at the base of the , slabs or foundations and passive earth pressure along the sides of the foundations. A coefficient, of friction of 0.40 between soil and concrete may be used for dead load forces only. A passive' earth pressure of 250 pounds per square foot, per foot of depth, may be used along the sides of: footings which are poured against properly compacted native or approved import soils. Retaining walls may be required to accomplish the proposed construction. Cantilever retaining' walls may be designed using "active" pressures. Active pressures may be estimated using an; equivalent fluid weight of 40 pcf for native backfill soils with level free-draining backfill: conditions. For walls that are restrained, "at rest" pressures should be utilized in design. At rest! pressures may be estimated using an eqUivalent fluid weight of 60 pcf. Walls should be provided; with adequate drainage. It is our opinion that the remedial grading recommended in the referenced report remains' appropriate for any structural areas. Because the majority of the driving range grading will be ' non-structural areas remedial grading should not be necessary. The' remedial grading: recommended in the referenced report including overexcavation of the surface soils should be; limited to structural areas. . : The structural fill areas should be cleared of any surface vegetation prior to grading. In order to! provide for firm and uniform foundation support, we recommend overexcavation and: recompaction. The building areas should be overexcavated to a depth of at least 3 feet below; existing grade or 3 feet below pad grade, whichever is deeper. The exposed surface should then! be scarified, moisture conditioned and compacted to a minimum of 90 percent relative; compaction. The previously removed soils and fill material may then be placed in thin lifts and' compacted to at least 90 percent relative compaction. It should be noted that the site is located within a seismically active ·area of Southern California and it is likely that the proposed structures will experience strong ground shaking as a result of an earthquake event along one of the faults in the region during the expected life of the; development. As a minimum, structures should be designed based upon Seismic Zone 4 design; criteria included in the Uniform Building Code (UBC). The pot,ential for liquefaction or other' geologic/seismic hazards occurring at the site is considered to be negligible. Sladden Engineering i May 19,2005 (Revised 7-15-05) -3-Project No. 544-2063 05-05-116 We appreciate the opportunity to provide service to you on this project, if you have any questions regarding this letter or the referenced reports please contact the undersigned. Respectfully submitted, SLADDEN ENGINEERING Principal Engineer SER/lb Copies: 4/La Costa Resort & Spa Sladden Engineering May 19, 2005 (Revised 7-15-05) -4-Project No. 544-2063 05-05-116 1997 UNIFORM BUILDING CODE INFORMATION The International Conference of Building Officials 1997 Uniform Building Code contains substantial revisions and additions to the earthquake engineering section in Chapter 16. Concepts contained in the updated code that will be relevant to construction of the proposed structures are summarized below. Ground shaking is expected to be the primary hazard most likely to affect the site, based upon proximity to significant faults capable of generating large earthquakes. Major fault zones considered to be most likely to create strong ground shaking at the site are listed below. Approximate Distance Fault Type Fault Zone From Site (1997UBC) Newport -Inglewood 16.8 kID B Rose Canyon Fault 8.8km B Based on our field observations and understanding of local geologic conditions, the soil profile type judged applicable to this site is So, generally described as stiff or' dense soil. The site is located within UBC Seismic Zone 4. The following table presents additional coefficients and factors relevant to seismic mitigation for new construction upon adoption of the 1997 code. Near-Source Near-Source Seismic Seismic Seismic Acceleration Velocity Coefficient Coefficient Source Factor, Na Factor, Nv Ca Cv Newport Inglewood 1.0 1.0 0.44 Na 0.64Nv Rose Canyon Fault 1.0 1.05 0.44Na O.64Nv Sladden Engineering RECEIVED JUl 20 2005 ENGINEERING DEPARTMD~·r -114/2005 15: 31 FAX 760 929 6313 LA COSTA RESORT & SPA ~ e Siadden Engineering 6782 Stanton Avenue. Sl,Iite A, Buena Pari<, CA 90621 (714) 523-0952 Fax (714) 523-1369 114 South California Avenue, Beaumont. CA e~ (951) 845-7743 Fax (951) 951,:645-8803 39-725 Ganlnd Lane" SuIte G. Palm D~rt. CA g2~11 (760) 772-3003 Fax (760) 172-3895 June9~ 2005 La Costa Resort and Spa do l<SL Development Corporation 2100 Costa Del Mar Road CarlsbacL California 92009 Subject: Geotechnical Update Proposed Entrance Monument I,.a Costa Resort &: Spa. Costa Del Mar Road Carlsbad, California .Prgject No. 444-3161 05-D6-130 Ref: Geotechnical Investigation Ra!port prepared by SIadden Engineering datttd November 11, 2004, Project No.4.44-316tl Report No. 03-10-183. As requested~ we have reviewed the referenced Geotechnical Investigation report as it reiates I:() the design and construction of the pro~ entrance Inonumcmt. 'The ptoJ~ site is located on the northeast corner of El Camino Real and Costa Del MaT Road in the City oC Carlsbad, California. The referenced Ccotechnical InvlI!!stigation. report Includes recommendations for the dC$ign and construction of the resort residential units that should be applicnblc fot sound wall design. 'Based upon our review of the -referenced report and our ongoing site observations, it is our opinion that the :t~mmel\dations included in the above refe .. en~ Teport remain applicable for the proposed SO\lnd wall. Footings should extend at least 18 inches beneath lowest adjacent grD.de. fsoiated square or rectangular footings at least 2 feet square may be designed uSing an allowable bearing value of 2500 pounds-pel:' square foot. Continuous footings at leattt 12 inches wide may be designe~ using an allowable bearing value of 2000 pounds per square foot. Allowable lncreases of 200 psf fot each ad ditionall foot of width and 250 p$f fOT each additional 6 inches of depth may be utilized if desired. The maximum allowable hearing pressure! should ~ 3000 psf. The Oll1owable bearing pressures are for dead ~nd frequently applied live loads and may be increased. by 1/3 to resist Wind seismic Or other transient loading. ~ d ZVLOLLlOB9 'oN/SO: Ll 'lS/90: H SOOl £ L Nnr(NOW) 141002 L ..... ·' 14/2005 15: 31 FAX 760 929 6313 June 9, 2005 LA COSTA RESORT & SPA -2-Project No. 444-3161 05-06-130 Thll tlOlCommendations made in the preceding paragraph are based on the assumption that all footings will be supported by pTOpedy compacted eoila. Prior to the pt<l<x:ment of th~ reinforcing steel .,nd c:on~arte, we recommend that the footing excavations be inspocted in order to verify that they extend into the firm compacted soils and are free of loose and disturbed materials. Settlement:! may result from the antldpated foundation loads. These estimated ultimate settlements are calculated to be a maximum of 1 inch when using the recoMmended bearing valu~. M a practical matter, differential settlements between footings can be assumed as one- hililf of the total settlcrnc:nt. These elastic settlements Jlre expected to occur during construction. Resistance to lateral loads may be proYided by a combination of friction acting :Jt the base of the slabs or foundation~ and pa!;sivc earth pressure along the sides of the foundations. A coefficient of friction of 0.40 between soil and c:oncrete may I;>e used for dead load torC!e!S only. A passjve earth pressure ot 200 pounds per square toot., per foot of depth, may be used along the sides of footings which are poured against properly ~mpacted native Of appro,,"ed import soils. Retaining waHs may be required to aQ:Omplish the proposed conSttuction. Cantilever retaining walls may l>e designed using "active" pNSSUTeS. Active pressures may ~ estimated using ,m equivalent fJ\lid weight of 40 pef I(,r nativ~ bac:kfill soils with level free-draining backfill conditjons. For walls that are restrained, "at rest" pressures should be utiliud in design. At rest p~"SUres may be estimated using an equivalent fluid weight of 60 pef. Walls should be provided with adequate drainage. , It is our opinion that the remedial grading tccommend«l in the telerc:nc;ed report remains approprillte. The rem~diaJ grading necessary at this time should Jnc:lude overeXJ;avation of the smfac:e soils within tha proposed cntranee monument area. The foundation areas should be cleared of any surface vegetation prior to gl'ading. In order to provide [or firm and uniform foundation supPOrt. we recommend overexcavation and rccompQct1on. The foundation aTeas should be ovcrexcavated to a depth of .,t least 3 feet below qxisting grLlde or 2 £eet below tho bottom of the f.ootlngsr, whichever Is oecpeT. ·rhe exposed surface should then be scarlficd, moi~ .. iure cond1Uoned and compacted to ~ minimum of 90 perc:ent relative compaction. The previously removed soUs ~nd fill material may tnen be placed in thin lifts and compacted to at least 90 percent relatiye compaction. It should be noted that the site is located within a l>eismicaUy ;,dive area ol Southern California and it is likely that ·the proposed structures will experience strong gI'O,md shaking as a t'eSult of an earthquake f!",ent along one of the faults h'l the region during the expected life 'of the development. As a mirWnunl, SLructuTCS should be designed hr£sed upon Seismic Zone 4. d~ign criteria included in the Uniform Building Code (USC). The potential for liquefaction or other geologic/seismic hazards occurring at the site is (on~dered to be negligible. SJaddelt Ellgilleering ~003 Z d 2:vLOLLcOS9 'ON/SO:Ll 'lS/90:Ll SOO~ Sl N11r(N{)W) IH3S3G W1Vd N30aV1S WOHd "14/2005 15: 31 FAX 760 929 6313 e June 9,2005 LA COSTA RESORT & SPA Ptoject No. 444-3161 05~06-130 We appl'~ate the opportunity to pto\1ide service to you on this project if you have any questions rcga-.:ding this letter or the reteren~ r~ports please contact the undersigned. Respectfully submitted, SUDDEN ENCINEERING SER/lb Copies: -. •. _---- Sladdt'!1f E'fgine.el'iJIg l4J 004 S d lVLOLLG089 'oN/SQ:Ll 'lS/SO:U SOOZ 8L NOr<NOW) 1~3Sja W1Vd N30aV1S ~OBj 0/14/2005 15:31 FAX 760 929 6313 tit June 9, 2005 LA COSTA RESORT & SPA -4- • Project No. 44+3161 05-06-130 19!17 UNIfORM BUILDING COOl! INFORMATION The International Conference of Building Officials 1991' Uniform Bullding Code contains subst&lntial r¢visions and additions to the earthquake engineering section hl Chapter 16. Con~pts contnincd in the updated code that wiU be relevant to constnlction of the t'ro~sed structures ate summ"rized bt::low. Gtound shaking ;s expected to be the primary hazard most likely to affect the site, bas(!d upon proximity to ~i~~ant faults COlp<lblc of generating largca e~Tthquake9. Major faull: 7.0n(,s consider~ to be most likely to create strong ground shaking at the site are listed below. .. , " Appl'Qximate DJatance Fault Type FauItZone FmmSite (1997UBC) Newport .... Inglewood 16.8km B Rose CaI!}'on Fault 8.8km D Based on our field observations and understanding of local geologic conditions, the soil profile type judged applicable to this site is $v, ~all)" descrJbQd as stifi OJ: de'\Se soil. The site I, located within USC Seismic Zone 4. The foUowing table presents additional coefficients and factors .televant to soil9TJ1ic mitigation Cor new construction upon. adoption of the 1997 o:ld~. Near-Source Ne31'-Source Seiamj(: Seistnic Sei:sm1c Acederation Velocity Coefficient Coefficient Source Factor,Na P .. ctOT; Ny Ca . C .. Newport Il'lglewood. 1.0 1.0 0.44 N. 0.64 N" Rose Canyon Fault 1.0 1.05 O.4.4N. O.64Nv SJatlJ~1l EJtgineering 141 005 \7 d cHOLLG099 'oN/90:LL 'ls/90:LL 900l SL NOr(NOW) 1~3S3a W1Vd N300V1S WOHJ • ~C£f'[BD J \) ~ 1. 3 1\\\\~ ~~G\N~E.R\N? ~? p..F..1~N2.N \ , .