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HomeMy WebLinkAboutSDP 09-04A; PLAZA CAMINO REAL SHOPPING CENTER; GEOTECHNICAL RECONNAISSANCE REPORT APPENDIX C; 2010-01-28Appendix C GEOTECHNICAL RECONNAISSANCE REPORT RECEIVED AUG 292016 LAND DEVELOPMENT ENGINEERING oq- 'qA GEOTECHNICAL RECONNAISSANCE REPORT PLAZA CAMINO REAL SHOPPING CENTER REVITALIZATION CARLSBAD, CALIFORNIA PREPARED FOR HELIX ENVIRONMENTAL PLANNING, INC. LA MESA, CALIFORNIA JANUARY 28, 2010 PROJECT NO. G1180-32-01 GEOCON IN CO H PO It ATE n GEOTECNICA1 CONSULTANTS Project No. G1180-32-01 January 28, 2010 Helix Environmental Planning, Inc. 7578 El Cajon Boulevard, Suite 200 La Mesa, California 91942 Attention: Ms. Kim Baranek Subject: PLAZA CAMJNO REAL SHOPPING CENTER REVITALIZATION CARLSBAD, CALIFORNIA GEOTECHNICAL RECONNAISSANCE REPORT Dear Ms. Baranek: In accordance with your authorization of our Proposal (LG-09249 dated October 15, 2009), we have prepared this geotechnical reconnaissance for the Plaza Camino Real Shopping Center revitalization project in Carlsbad, California. The accompanying report describes the site soil and geologic conditions, discusses potential geotechnical constraints and geologic hazards, and provides recommendations for a future geotechnical investigation. Should you have questions regarding this report, or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON INCORPORATED - <11fu-i-xX Trevor E. Myers RCE 63773 TEM:DBE:dmc VA ( No. RCE63773 (6) Addressee ' xp.oWlO avid B. Evans CEG 1860 ONAL DAVID a 4: EVANS CEFMFIED -4 ENGINEERING :A GEOLOGIST 6960 Flanders Drive .0 Son Diego, Coulomb 92121-2974 0 Telephone (858) 558.6900 a Fox (858) 558-6159 TABLE OF CONTENTS PURPOSE AND SCOPE ................................................................................................................. 1 SITE AND PROJECT DESCRIPTION ........................................................................................... 1 SOIL AND GEOLOGIC CONDITIONS ........................................................................................2 3.1 Compacted Fill ......................................................................................................................2 3.2 Alluvium................................................................................................................................2 3.3 Santiago Formation................................................................................................................3 GROUNDWATER..........................................................................................................................3 GEOLOGIC HAZARDS .................................................................................................................3 5.1 Landslides..............................................................................................................................3 5.2 Regional Faulting and Seismicity..........................................................................................3 5.3 Soil Liquefaction and Lateral Spread Potential.....................................................................4 5.4 Tsunamis and Seiches............................................................................................................5 5.5 Mineral Resources.................................................................................................................6 5.6 Slope Stability........................................................................................................................6 5.7 Remedial Grading..................................................................................................................6 FUTURE GEOTECHNICAL INVESTIGATION...........................................................................6 MAPS AND ILLUSTRATIONS Figure 1, Vicinity Map Figure 2, Site Plan Figure 3, Regional Geologic Map GEOTECHNICAL RECONNAISSANCE REPORT 1. PURPOSE AND SCOPE This report presents the results of a geotechnical reconnaissance for the proposed Plaza Camino Real shopping center revitalization and expansion project in Carlsbad, California (see Vicinity Map, Figure 1). The purpose of this study is to provide preliminary soil and geologic information for the property, identify known geologic hazards that may adversely impact the proposed development and assist in planning and development studies. The scope of our study included a review of readily available published geologic literature and geotechnical reports relative to this property and the vicinity, and performing a site reconnaissance and preliminary geologic mapping where possible. 2. SITE AND PROJECT DESCRIPTION Plaza Camino Real is an existing regional shopping center located on an approximately 93-acre site bounded by El Camino Real to the east, State Route 78 and Buena Vista Creek to the north, Marron Road to the south, and Monroe Street to the west in Carlsbad, California. The site was originally developed in the late 1960's and subsequently expanded several times to its current configuration. The two to three story shopping center buildings are situated in the central portion of the site with a significant grade break traversing in an east-west direction dividing the upper southerly one-third of the site from the lower northerly two-thirds of the site. Peripheral parking consisting of approximately 6,400 parking stalls surrounds the central mall stores. Five existing outparcel buildings occupy portions of the parking lot area. We understand that re-development consists of demolition, reconfiguration and/or reconstruction of approximately 179,600 square feet of existing area and the construction of up to approximately 35,400 square feet of new gross leasable place. It appears that the improvement will be accomplished by expanding several of the existing buildings and construction of four new structures in the southeast portion of the property. The new structures will provide retail space, restaurant pads, a theater and grocery/market or other retail/lifestyle/entertainment commercial uses. From a geologic standpoint, the subject site is situated on reclaimed marshland in the Buena Vista lagoon area approximately 1 mile from the Pacific Ocean. The site is located relatively close to the southern boundary of the lagoon, where relatively steep slopes ascend from the lagoon to an elevated terrace several hundred feet above the shopping mall. Santiago Formation has been mapped along the southern flanks of the property. The elevation of the lagoon prior to site development ranged from approximately 5 to 10 feet (MSL). Grading for the mall resulted in placing compacted fill across the Project No. 01180-32-01 -1- January 28, 2010 lagoon aria to achieve pad grade elevations ranging between approximately 26 and 38 feet (MSL). The topographic relief across the property ranges from approximately 10 feet along the northwestern edge of the parking lot to approximately 44 feet along the southeastern edge. The Site Plan (Figure 2), which utilized a Google Earth image as the base map, depicts the current configuration of the subject property and existing improvements. We added the approximate overall project limits and locations of proposed improvements. 3. SOIL AND GEOLOGIC CONDITIONS Based on our literature review and site reconnaissance, the site is generally underlain by either compacted fill over alluvium or Santiago Formation. The thickness of the alluvium is expected to be nominal to the south where the formational materials are expected. The geologic units are described in detail below. 3.1 Compacted Fill Compacted fill soils have been placed across portions of the property during the original site grading in the late 1960's/early 1970's to achieve the current grades (Reference No. 9). The fill soils range in thickness from 0 feet in the southeastern portion of the site to approximately 35 feet in the western and northwestern portions of the property. The fill soils generally consist of clayey sands, silty sands, silty clays and sandy clays and typically exhibit a "low to medium" expansion potential. The fill materials were most likely placed to raise the existing grades out of the lagoon /floodplain zone. 3.2 Alluvium Alluvial soils underlie the fill materials across portions of the site. These bay-estuary deposits generally consist of loose to medium dense, silty fine sands and clayey sands, and soft to firm clayey silts and silty and sandy clays. The alluvial deposits are considered potentially compressible and subject to consolidation under increased loading. The estimated alluvial thickness ranges from 0 feet in the southeastern portion of the property to greater than 100 feet in the northwestern portion of the site (Reference No. 9). The settlement potential of the alluvial materials should be evaluated during future geotechnical studies. In addition, there are layers of potentially liquefiable soil below the groundwater level based on Reference No. 9. Evaluation of the soil liquefaction potential will be required during future geotechnical studies. Project No. GI 180-32-01 1 - 2 - January 28, 2010 — 3.3 Santiago Formation The Eocene-age Santiago Formation was mapped along the southern flanks of the property and is expected to be encountered along the southern and southeastern portions of the property. The Santiago Formation generally consists of relatively flat-lying claystone, siltstone, and sandstone units. Weak, waxy claystone and thinly laminated siltstone/claystone and sandstone are typically present within this unit. With the exception of the sandier portions of the Santiago Formation, materials derived from this unit typically posses a medium to high expansion potential with a moderate to low shear strength. The Santiago Formation typically has a high to moderate potential to transmit seepage along impervious layers within the formation. The Santiago Formation often exhibits highly cemented zones that may result in excavation difficulty during grading and construction of site improvements (e.g., underground utility lines and building foundations). Moderate to heavy ripping may be necessary in portions of this formation to facilitate excavation. Generation of oversize materials requiring special handling and placement techniques often occurs when excavating in this formation. 4. GROUNDWATER Based on Reference No. 9, the depth to groundwater is estimated to be approximately 13 to 15 feet below ground surface. Groundwater could have a significant influence on construction depending on the location of proposed underground utilities and excavation depths. Stabilization and/or dewatering techniques will likely be necessary for excavations greater than approximately 13 below existing grades, especially along the northern and northwestern portions of the property where the compacted fill and alluvial materials are present. Groundwater elevations may vary seasonally and may also be influenced by the presence of water in the Buena Vista channel located along the northern boundary of the site. Proper surface drainage of irrigation and rainwater will be critical to the future performance of the project. 5. GEOLOGIC HAZARDS 5.1 Landslides No evidence of landsliding was noted during the reconnaissance or previous investigation, and no landslides are known to exist on the property or at a location that would impact the proposed development. 5.2 Regional Faulting and Seismicity Based on review of aerial photographs and published geologic maps, the site is not located on any active or potentially active fault trace, as defined by the California Division of Mines and Geology. In order to determine the distance of known faults to the property, the computer program EQFA ULT Project No. Gil 80-32-01 -3 - January 28, 2010 (Blake, 2000) was utilized. In addition to fault location, EQFA ULT was used to estimate ground accelerations at the site for the maximum anticipated seismic event. Regional geologic information (Reference No. 5) is presented in Figure 3. The results of the deterministic analysis indicate that the Newport-Inglewood (off-shore segment) and Rose Canyon Faults are the dominant sources of potential ground shaking at the site. The Newport- Inglewood and Rose Canyon Faults are estimated to have the capability to generate a maximum earthquake event of Magnitude 7.1 and 7.2, respectively. The estimated maximum peak site acceleration was calculated to be 0.34g. Presented on Table 5.2 are the earthquake events and calculated peak site accelerations for the faults most likely to subject the site to significant ground shaking. Peak ground acceleration was estimated using the attenuation relationships of Sadigh (1997). TABLE 5.2 DETERMINISTIC SITE PARAMETERS FOR SELECTED ACTIVE FAULTS Fault Name Distance From Site (miles) Maximum Magnitude Event Magnitude pea k Site Acceleration (g) Newport-Inglewood (Offshore) 5.8 7.1 0.34 Rose Canyon 6.2 7.2 0.34 Coronado Bank 22.4 7.6 0.17 Elsinore (Temecula) 22.7 6.8 0.11 Elsinore (Julian) 23.1 7.1 0.12 Elsinore (Glen Ivy) 32.1 6.8 0.07 San Joaquin Hills 34.5 6.6 0.07 Palos Verdes 35.8 7.3 0.09 It is our opinion that the site could be subjected to moderate to severe ground shaking in the event of an earthquake along any of the faults listed on Table 5.2 or other faults in the southern California/ northern Baja California region. However, the site does not possess any greater seismic risk than that of the surrounding developments. 5.3 Soil Liquefaction and Lateral Spread Potential Liquefaction typically occurs when a site is located in a zone with seismic activity, on-site soils are cohesionless, groundwater is encountered within 50 feet of the surface, and soil relative densities are less than about 70 percent. If the four previous criteria are met, a seismic event could result in a rapid pore-water pressure increase from the earthquake-generated ground accelerations. Seismically induced settlement is settlement that occurs as a result of liquefaction, or as a result of partial re-arrangement in loose dry sands located above the groundwater table. Project No. Gl 180-32-01 -4- January 28, 2010 The County of San Diego Hazard Mitigation Plan maps identify zones of high risk for liquefaction in areas throughout the county. The northern portion of the subject property is included in a high-risk hazard area based on their mapping. The potential for liquefaction and seismically induced settlement occurring within the site will be a primary focus of future studies. Surface manifestation .of liquefaction will vary depending on the thickness of liquefiable layers, the thickness of a non-liquefiable cap, and other factors. Surface manifestation could consist of surface settlements, sand boils, and ground fissures. Based on our preliminary evaluation using Reference No. 9, the risk for seismically induced liquefaction along the southern portions of the property may be lower since this part of the site is underlain by formational materials at a shallow depth. In addition, it is estimated that the thickness of potentially liquefiable alluvium beneath the compacted fill in this area would relatively limited. It should be noted, however, that there still may be a potential for differential settlement if liquefaction occurs. If future studies identify liquefiable soils, mitigation will be necessary for settlement-sensitive structures. Typically, structural mitigation would consist of deep foundations extending through the liquefiable layers into deep, non-liquefiable soils at depth. It may also be possible to design the proposed structures and improvements to accommodate the estimated settlement. As an alternative, ground improvement can be used to densify existing soils. Typical ground improvement techniques for liquefaction include stone columns, vibrocompaction, compaction grouting, and deep dynamic compaction. The potential for lateral spreading due to liquefaction at the site is considered relatively low and would be confined to soil adjacent to the drainage channel and highway embankment. 5.4 Tsunamis and Seiches A tsunami is a series of long-period waves generated in the ocean by a sudden displacement of large volumes of water. Causes of tsunamis include underwater earthquakes, volcanic eruptions, or offshore slope failures. The first order driving force for locally generated tsunamis offshore of southern California is expected to be tectonic deformation from large earthquakes (Legg, et al., 2002). The largest tsunami effect recorded in San Diego since 1950 was May 22, 1960, which had a maximum run-up amplitude of 2.1 feet (0.7 meters) [URS, 2004]. Wave heights and run-up elevations from tsunami along the San Diego Coast have historically fallen within the normal range of the tides. The County of San Diego Hazard Mitigation Plan maps zones of high risk for tsunami run-up for coastal areas throughout the county. The site is not included in the high risk hazard area. Due to the relative elevation of the site compared to sea level and distance to the Pacific Ocean, the potential for tsunamis impacting the site is low. Project No. G1180-3 2-01 - 5 - January 28, 2010 Seiches are caused by the movement of an inland body of water due to the movement from seismic forces. The County of San Diego Hazard Mitigation Plan maps zones of high risk for dam inundation areas throughout the county. The site is not included in the high risk hazard area. The potential of seiches to occur is considered to be very low due to the absence of a nearby inland body of water. 5.5 Mineral Resources The subject property is currently developed to support an active regional shopping center with the anchor stores and mall complex located in the central portion of the site with surface parking lots surrounding the mall. The proposed improvements are planned within the existing shopping center property boundaries and generally within the existing parking lots. From a geologic standpoint, the site is underlain by either Santiago Formation or compacted fill over alluvium. The site was originally marshland terrain that was reclaimed in the late 1960's for the shopping center construction. As part of our evaluation, we reviewed the report entitled Mines and Mineral Resources of San Diego County, California (County Report 3), published in 1963 by the California Division of Mines and Geology. The report indicates that a salt producing operation was present near or beneath the current shopping center in 1901 through 1902. The mining process consisted of drilling 30 to 50 foot deep wells into the lagoon and pumping the salt brine into evaporating ponds. Since the site has already been developed to support the existing improvements, and future improvements are relatively minor, it is our opinion that loss of availability of a locally important mineral resource is relatively low. 5.6 Slope Stability No major cut or fill slopes are planned. Based on our visual observations and experience with similar soil and geologic conditions, the existing slopes should be grossly and surficially stable with respect to deep-seated instability and shallow sloughing conditions. 5.7 Remedial Grading Remedial grading recommendations will be developed as part of the future geotechnical investigation and will be dependent on the results of the liquefaction analysis, mitigation method, and foundation system used. Typical remedial grading measures may consist of removing and replacing the upper approximately 3 feet of finish grade soils with properly placed compacted fill. 6. FUTURE GEOTECHNICAL INVESTIGATION A geotechnical investigation will be necessary to evaluate the subsurface conditions at the site and to provide recommendations for design and construction of the proposed improvements. The scope of the geotechnical investigation should include performing a subsurface investigation, laboratory testing, and engineering analyses and include an evaluation of the subsurface geologic conditions, the Project No. G1180-32-01 -6- January 28, 2010 - presence of geologic hazards, including liquefaction and seismically-induced settlement potential, and the geotechnical aspects of developing the property. The report should include recommendations regarding remedial grading, earthwork grading considerations, ground improvement options, foundation options, concrete slabs and flatwork, preliminary pavement design, retaining walls, and site drainage. Project No. GI 180-32-01 - 7 - January 28, 2010 SOURCE: 2007 THOMAS BROTHERS MAP SAN DIEGO COUNTY, CALIFORNIA "Map © Rand McNally, R L 08-S-lOU, reproduced with permission It is unlawful to copy NO SCALE or reproduce, whether for personal use or resale, without perm ssion" GEOCON I N C 0 H P0 H AT S D 401W GEOTECHNICAL CONSULTANTS 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121 - 2974 PHONE 858 558-6900 - FAX 858 558-6159 TM I RS DSK/GTYPD G1180 32 01 TM Vo,r, 'A Mop FIG1 VICINITY MAP PLAZA CAMINO REAL SHOPPING CENTER REVITALIZATION CARLSBAD, CALIFORNIA DATE 01-28-2010 PROJECTNO. G1180-32-01 1 FIG.1 Y \RI4TEMP\1 GE01E011 GEOTECH RUBENIGEOCON 2010\G1100-32 01 PLAZA CAMINO REAL SHOPPING CENTER\G1 1803201 VICINITY MAP _TM_FIG1 dwg irt? y * '. !z•' I' -' Ye ;tW - I1w PLAZA CAMINO REAL SHOPPING CENTER REVITALIZATION CARLSBAD, CALIFORNIA ZTh.; : raw - — . - -'-- — .- -.,. .- ., -- •_ JIJW _. - - .. - • a fr -1 .-- - - • SITE BOUNDARY-"' ML 1 01 Its:-. 4 1 eA . p p '--'- 0. 101 a, '•.*.Ito , , ,,i : s - I r - ,'! j 'r"- .r ' r 0000 J A NO SCALE GEOCON Aft INCORPORATED THE GEOGRAPHICAL INFORMATION MADE AVAILABLE FOR DISPLAY WAS PROVIDED BY GOOGLE EARTH, SUBJECT TO A LICENSING AGREEMENT. THE INFORMATION IS FOR ILLUSTRATIVE PURPOSES ONLY; IT IS NOT INTENDED FOR CLIENTS USE OR RELIANCE AND SHALL NOT BE REPRODUCED BY CLIENT. CLIENT SHALL INDEMNIFY, DEFEND AND HOLD HARMLESS GEOCON FROM ANY LIABILITY INCURRED AS A RESULT OF SUCH USE OR RELIANCE BY CLIENT. LEGEND .......APPROX. LOCATION OF PROPOSED IMPROVEMENTS GEOTEaINICAL CONSULTANTS 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 92121- 2974 PHONE 858 558-6900 - FAX 858 558-6159 PROJECT NO. G1180-32-01 FIGURE 2 SITE PLAN DATE 01 -28 -2010 S.- ?\\\\ 2,1 t\ ) Qo 20 10 6/ SOURCE: Kennedy, MP and S.S. Tan, 2005 Geologic Map of the Oceanside 30'x60' Quadrangle, California /L/ Qa 15 ~~7,Qa 11111~_ 1-1 Tsa "' 77 61s, 1-50 \ ' \ \ 0 \, A it / \ ()r PLAZA CAMINO REAL SHOPPING CENTER REVITALIZATION CARLSBAD, CALIFORNIA LEGEND - IT IJ uf,. 'w-0 lwwd ibh.'i1 h&'ST zçpnmrinztl.T!. Acd U'i,'hr,"r' isr,.. I.! -. sir,L ,i.p .Ikuial flood plain d.posii', fIik' lliii.il ,Ijists Ii,: ,',.i Ii ',.i'. I t iITLoTi-,,TIij.itc,l s,rif ili ' 1','rm ,IliiL ii I)...- I1LIi,IL illjiI'll I in kT'STN ii IinI LidS ''I I .nd'.iide thI1isifs undis ided (iiio&'cni and I old', 'F,IL'iTT_'iICTI to .iuL_k 'li_roil iii,'!,_'i.itl', i'' it:,: \loi_i tl.,llii'L'tl i LlSITI,_', L'iuiatii .LTI ,ii_'i IL'. Iii 10111c ,111'j, '.L,ii i IS 'diL'.L ii '.s';'.ir,lL'l tl,iii, II: ,Iiicctti. ..,_' Ijiijslidss Ii Li: I III tt.'d Iii pill TI :ni FL'l\ Inrn: lit: I II T&':ne \l,'., ill die Iinil'.Iidi_''. in I ini_l hi',: ,'iiurroil i Ohio tho ( Ipl'.tr.IlT I iiilfl.itIT'iL li,'.',i_'\.-r. thor: .r: it.l\ o 11,-n Ii: \I1I11LTL\ Oh1 i-,.i iii:',' III.iIi Ill )S 1", ii 01 t ' Santiago hirmalion (middle F iovno) \.i,ii:d h 'A LIII IiiTT_i)hbc f I '12, 1 *i'r I I), ti, i,j,,isjti_ of noitliii:'.t,'ri, S;ij \n,i N,Iiioiii,iin.. I lion: .: llroc ili'.linctiic pill'. T011 111LilibLI tin_il ,.i'ii,L',ts iii h ILL fl ,oiil hiii','tlI'.h-iTI,i\ i:jTn,.iI loin ',iio:il at ko,ic '.aiid'.t,,nc LIIL,hiiT.L,Ttc '.ITti_ISILIiO odd alli_ iii: Ii;i'.,i( 1Ii_lfll'di I', iTS 01 Lou b :1' In_I lii*i Ii'.11-OlL\ i 'alt and popporl coninal no :nihct i liii on'. '.1'. of ',ott. Ii1(.t:r,htei\ ',s i_'lI-'.,'Iloil ,irkosii_ s.iisiiii, \i 'Ippi_'r Ii)L'n)h,'r i_iin'.i,.t'. nil ora', c,crSc-l!rTI1T.ii il'. slut: mid .r0 I Iiniuiglout I (IL' I,'rn,il ii'ii. holh s i_ri IL.T I Iiiti_'ljII'. lblL'Id ,.\i',IS IIILi, silissiull.' Otls'ii Rissil' Ici ins',, L I,', .tTIIO ,in_iI '.lIt'.tS'IIi_' 'I IIc ill iii: ,TTiTiIiiI,il iiitL'TlliiitL'iS o iii tlii_' l)i_'Ii i I 'i 01.11 ,0 II TI I ii tbio I ii,'IT' It'. 1I:Ilr:n (1 I CC C lN(b)Rl'Olt.-TLt) GEOTECHNICAL CONSULTANTS 6960 FLANDERS DRIVE - SAN DIEGO, CALIFORNIA 921212974 PHONE 858 558-6900 - FAX 858 5586159 PROJECT NO. G1180-32-01 FIGURE REGIONAL _GEOLOGIC _MAP 13-282o1o_________ 5 Tsa Qaç JiL V~~ fl1001701 J.T'P ...,:T-L.. -.,..' .. LIST OF REFERENCES Aerial Photographs (AXN 14M-20, and AXN 14M-21, dated May 2, 1953). Blake, EQFA ULT, A Computer Program for the Deterministic Prediction of Peak Horizontal Acceleration from Digitized California Faults, User's Manual, 1989a, p. 79. County of San Diego, Office of Emergency Services, Multi-Jurisdictional Hazard Mitigation Plan, 2010 (Draft), www.sdcoun1y.ca.gov/emerency_mangement/oesjl_mitplan.html. Jennings, C. W., 1994, California Division of Mines and Geology, Fault Activity Map of California and Adjacent Areas, California Geologic Data Map Series Map No. 6. Kennedy, M. P. and S. S. Tan, 2005, Geologic Map of the Oceanside 30 'x60' Quadrangle, California, USGS Regional Map Series Map No. 3, Scale 1:100,000. Landslide Hazards In The Northern Part of the San Diego Metropolitan Area, San Diego County, California, California Division Of Mines And Geology, Open File Report 95-04 (1995). 1953 stereoscopic aerial photographs of the site and surrounding areas. United States Geological Survey, 7.5 Minute Quadrangle Series San Luis Rey Quadrangle, 1968, photo revised 1975. Unpublished reports and maps on file with Geocon Incorporated. Woodward-Clyde Consultants, Geotechnical Investigation, Plaza Camino Real Expansion, Carlsbad, California, dated September 17, 1975 (Project No. 75-173). Project No. GI 180-32-01 January 28, 2010 GEOCON 0 I N C 0 K p o It A T K fl GEOTECHNICAL CONSULTANTS Project No. G1180-32-01 April 27, 2010 Helix Environmental Planning, Inc. 7578 El Cajon Boulevard, Suite 200 La Mesa, California 91942 Attention: Ms. Kim Baranek Subject: PLAZA CAMINO REAL SHOPPING CENTER REVITALIZATION CARLSBAD, CALIFORNIA ADDENDUM TO GEOTECHNICAL RECONNAISSANCE REPORT Dear Ms. Baranek: In accordance with your request, we have prepared this addendum to our report entitled Geotechnical Reconnaissance Report, Plaza Camino Real Shopping Center Revitalization, Carlsbad, California, dated January 28, 2010. The addendum, Figure 4 attached, is a site plan presenting the estimated project location on an enlarged version of the map entitled County of San Diego, Office of Emergency Services, Multi-Jurisdictional Hazard Mitigation Plan, 2010 (Draft). Should you have questions regarding this addendum, or if we may be of further service, please contact the undersigned at your convenience. Very truly yours, GEOCON INCORPORATED Trevor E. Myers RCE 63773 TEM:DBE:dmc Attachment: Figure 4— Liquefaction (4) Addressee "a No. RCE63773 rl Exp.O9P3W1OjZt Map 6960 Flanders Drive • Son Diego, California 92121.2974 U Telephone (858) 558.6900 ON Fox 18581558-6159