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HomeMy WebLinkAboutMS 07-05; GEOLOGIC RECONNAISSANCE; 2008-01-15COAST GEOTECHNICAL CONSULTING ENGINEERS AND GEOLOGISTS 0 I br Cvr c\j0. January 15, 2008 Carolyn Howard-Jones 4657 Panonia Road Carlsbad, CA 92008 RECEIVED FEB 06 2008 Subject: GEOLOGIC RECONNAISSANCE ENGINEERING Proposed Lot Split DEPARTMENT APN 207-083-17 4120 Skyline Road Carlsbad, California Dear Ms. Howard-Jones: In response to your request, we have performed a geologic reconnaissance study on the subject property. No significant geologic hazards, except as disclosed, were encountered on the property which would preclude development as proposed. From a geologic viewpoint, the site is suitable for the proposed development. If you have any questions, please do not hesitate to contact us at (858) 755-8622. This opportunity to be of service is appreciated. Respectfully COAST GE AL BUR 2109 Exp. 5-31-08 * CERTIFIED ENGINEERING GEOLOGIST /1 OF CP' Mark Burwell, C.E.GN Engineering Geologist 779 ACADEMY DRIVE • SOLANA BEACH, CALIFORNIA 92075 (858) 755-8622 • FAX (858) 755-9126 Coast Geotechnical January 15,2008 W.O. R-538107 Page 2 INTRODUCTION This report presents the results of our geologic reconnaissance on the subject property. The purpose of this study is to evaluate the general geologic conditions on the site and their influence on the proposed development. SITE CONDITIONS The subject property is located at the southeast corner of Tamarack Avenue and Skyline Road, in the city of Carlsbad. The subject property includes approximately 0.76 acres of gentle sloping terrain. The site includes a single family residence situated on a level, graded pad in the central portion of the site. The western portion of the pad is bounded by a 6.0 foot high slope with a gradient approaching 2:1 (horizontal to vertical) that descends to gently sloping terrain. The property continues to descend to the west to the top of a 6.0± foot high cut slope with a variable gradient up to 2:1 (horizontal to vertical) for Skyline Road. The property is bounded along the north by a 7.0± foot high crib wall which is part of the development of Tamarack Avenue. The site is bounded along the south and east by developed residential lots. Vegetation includes grass, ice plant, shrubs and several trees. Drainage is generally by sheet flow to the west. Coast Geotechnical January 15, 2008 W.O. R-538107 Page 3 PROPOSED DEVELOPMENT Plans for the development of the site were prepared by Conway and Associates. The project includes splitting the property into two (2) separate parcels. The plans also show preliminary concept grading for each parcel to evaluate such feasibility. GEOTECHNICAL CONDITIONS The subject property is underlain at relatively shallow depths by Pleistocene terrace deposits. The sedimentary unit is composed of fine and medium-grained sand. Locally, the sedimentary rock is typically dense and moderately indurated. Bedding within the terrace deposits is poorly developed and the sedimentary unit is considered flat-lying. Dense, unweathered terrace deposits are considered suitable for the support of footings and structural fills. The terrace deposits are covered, in part, by residual soil deposits and isolated fill deposits. The fill deposits are locally derived sandy deposits and appear to be limited to a depth of approximately 4.0 feet to 5.0 feet along the western extent of the building pad. Expansive Soil Based on our experience in the area, the fill deposits, residual soil and Pleistocene sands reflect an expansion potential in the low range. Coast Geotechnical January 15, 2008 W.O. R-538107 Page 4 Groundwater The subject property is located along the top of a broad ridge. High groundwater conditions are not anticipated to be a constraint to the proposed development. Tectonic Setting The site is located within the seismically active southern California region which is generally characterized by northwest trending Quaternary-age fault zones. Several of these fault zones and fault segments are classified as active by the California Division of Mines and Geology (Alquist- Priolo Earthquake Fault Zoning Act). Based on a review of published geologic maps, no known faults transverse the site. The nearest active fault is the offshore Rose Canyon Fault Zone located approximately 2.3 miles west of the site. It should be noted that the Rose Canyon Fault is not a continuous, well-defined feature but rather a zone of right stepping en echelon faults. The complex series of faults has been referred to as the Offshore Zone of Deformation (Woodward-Clyde, 1979) and is not fully understood. Several studies suggest that the Newport-Inglewood and the Rose Canyon faults are a continuous zone of en echelon faults (Treiman, 1984). Further studies along the complex offshore zone of faulting may indicate a potentially greater seismic risk than current data suggests. Other faults which could affect the site include the Coronado Bank, Elsinore, San Jacinto and San Andreas Faults. The proximity of major faults to the site and site parameters are shown on the enclosed Seismic Design Parameters. Coast Geotechnical January 15, 2008 W.O. R-538107 Page 5 Landslides No evidence of deep-seated instability was observed on the site. No landslides have been mapped on or in the immediate vicinity of the subject property. Bedding within the terrace deposits is flat- lying and the sedimentary unit is not problematic in regards to deep-seated landsliding. Liquefaction Potential Liquefaction is a process by which a sand mass loses its shearing strength completely and flows. The temporary transformation of the material into a fluid mass is often associated with ground motion resulting from an earthquake. Owing to the medium-dense nature of the Pleistocene terrace deposits and the anticipated depth to groundwater, the potential for seismically induced liquefaction and soil instability is considered low. CONCLUSIONS The subject property is located in an area that is relatively free of potential geologic hazards such as landsliding, high groundwater conditions, liquefaction and seismically induced subsidence. The results of our geologic reconnaissance on the property suggests that no significant geologic hazards that would preclude development, as proposed, are present. Although the likelihood of ground rupture on the site is remote, the property will be exposed to moderate to high levels of ground motion resulting from the release of energy should an earthquake occur along the numerous known and unknown faults in the region. Coast Geotechnical January 15, 2008 W.O. R-538107 Page 6 The Rose Canyon Fault Zone located approximately 5.6 miles west of the property is the nearest known active fault and is considered the design earthquake for the site. A maximum probable event along the offshore segment of the Rose Canyon Fault is expected to produce a peak bedrock horizontal acceleration of 0.30g and a repeatable ground acceleration of 0.20g. A complete geotechnical investigation with subsurface exploration and laboratory testing should be conducted for actual development based on grading plans and proposed residential structures, when they are available. LIMITATIONS This report is presented with the provision that it is the responsibility of the owner or the owner's representative to bring the information and recommendations given herein to the attention of the project's architects and/or engineers so that they maybe incorporated into plans. If conditions encountered during construction appear to differ from those described in this report, our office should be notified so that we may consider whether modifications are needed. No responsibility for construction compliance with design concepts, specifications or recommendations given in this report is assumed unless on-site review is performed during the course of construction. The subsurface conditions, excavation characteristics and geologic structure described herein are based on individual exploratory excavations made on the subject property. The subsurface conditions, excavation characteristics and geologic structure discussed should in no way be construed to reflect any variations which may occur among the exploratory excavations. Coast Geotechnical January 15, 2008 W.O. R-538107 Page 7 Please note that fluctuations in the level of groundwater may occur due to variations in rainfall, temperature and other factors not evident at the time measurements were made and reported herein. Coast Geotechnical assumes no responsibility for variations which may occur across the site. The conclusions and recommendations of this report apply as of the current date. In time, however, changes can occur on a property whether caused by acts of man or nature on this or adjoining properties. Additionally, changes in professional standards may be brought about by legislation or the expansion of knowledge. Consequently, the conclusions and recommendations of this report may be rendered wholly or partially invalid by events beyond our control. This report is therefore subject to review and should not be relied upon after the passage of two years. The professional judgments presented herein are founded partly on our assessment of the technical data gathered, partly on our understanding of the proposed construction and partly on our general experience in the geotechnical field. However, in no respect do we guarantee the outcome of the project. 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: Vicinity Map Geologic Map Coast Geotechnical January 15, 2008 W.O. R-538107 Page 8 REFERENCES Hays, Walter W., 1980, Procedures for Estimating Earthquake Ground Motions, Geological Survey Professional Paper 1114, 77 pages. Petersen, Mark D. and others (DMG), Frankel, Arthur D. and others (USGS), 1996, Probabilistic Seismic Hazard Assessment for the State of California, California Division of Mines and Geology OFR 96-08, United States Geological Survey OFR 96-706. Seed, H.B., and Idriss, I.M., 1970, A Simplified Procedure for Evaluating Soil Liquefaction Potential: Earthquake Engineering Research Center. Tan, S.S., and Giffen, D.G., 1995, Landslide Hazards in the Northern Part of the San Diego Metropolitan Area, San Diego County, Plate 35A, Open-File Report 95-04, Map Scale 1:24,000. Treiman, J.A., 1984, The Rose Canyon Fault Zone, A Review and Analysis, California Division of Mines and Geology. MAPS/AERIAL PHOTOGRAPHS California Division of Mines and Geology, 1994, Fault Activity Map of California, Scale 1 "=750,000'. Conway and Associates, 2008, Tentative Parcel Map, 4120 Skyline Drive, Carlsbad, California, Scale I "= 10'. Geologic Map of the Oceanside, San Luis Rey and San Marcos 7.5' Quadrangles, 1996, DMG Open File Report 96-02. U.S.G.S., 7.5 Minute Quadrangle Topographic Map, Digitized, Scale Variable. ENCLOSURES uata ue suoject to license. © 2004 DeLorme. Topo USA® 5.0. fM4l00) www.delorme.com 1' = 466.7 ft Data Zoom 15-0 I SITE—' " 10, 5— - — —S THOS MOE P jOOOf XX TA 1. OF I MARCOS fl "OT 10 SCALE I SHEET CITY OF CARLSBAD 51(115 1 PLANNING DEPARTMENT 4 5 IslEt T11t5 I TENTATIVE PARCEL MAP I 4120 SKYLINE DRIVE City of Carlsbad Tentative Parcel Map JONES MINOR SUBDIVISION CAROLTH L HOWARD-JONES DATE BARBARA D. HOWARD-JONES DATE LEGAL OESCRIP'flON: EXISTING PED THAT PARCEL SHOWN IN CERTIFICATE OF COMPLIANCE RECORDED AUGUST 31. 1981 AS pp I4S1.MD1T NO. 61-278044 AND AS MORE PARTICULARLY DESCRIBED IN ATTACHMENT A TO DOCUMENT RECORDED NO'.DBER 16. 2006 AS DCC. NO. 2006-0815585. -- -- -- PROJECT ADORES ._-:. - ------------------- --- - 4120 SICIUFE ROAD EXISTING ID' AM EXISTING CURS. - - - - __ ASSESSORS PAR.. NUMBERS: WATER MNN / AND SBCWAI.X (TAMARACK ONLY) TAMARACK AVENUE 207-083-11 I / _— is, - -._ "-'I.- ElISTING CRIB TYPE REifr1 — .._._.. — PROJECT DESCRIPTION: DRO. NO. 206-7 SHT 3 Ac 3A OF 12 LAND SPUT ONLY — I PARCEL INTO 2 PARCELS. NO GRADING OR CONSTRUCTION IS -- 87 86 85 - —.--- - - ssoo PROPOSED AS PART OF THE PROJECT, SER'I,ING UTILITY AGENCIES - 84 s... WATER CITY OF CARLSBAD SEWOL Div OF CARLSBAD . .. —...- ..-. F CITY OF CARLSBAD . ..- - .... 5 -_._... - I SC*4ODI. CARLSBAD UNIFIED SCHOOL DISTRICT - GAS & ELECTRIC: SANDIEGO GAS & ELECTRIC PROJECT DATA. EXISTING LAND uSE... EXISTING RESIDENTIAL PROPOSED LAND USE....................... RESIDENTIAL -- — . . . . . TOTAL NUMBER OF (lISTING PARCELS ......_. SETBACK LINE , C 2 . C 2 .. . . . / TOTAL NUMBER OF PROPOSED PARCELS ...... 2 - AND DISTANCE / . , i yt / DENSITY -..-...—.-.—. 2.7 UNITS PER ACRE (3.2 UNITS/AC FROM Pt. -.TWICAJ? PARCEL 2"" ') B3 1 AJJ2LE) 1 .v' . r 5_, I_ ..-'j TOTAL LOT SI -_- ......- 33,250 OR (0.78 ACRES) 17,439 .OROSSL . .. ZONI EXISTING & NG PROPOSED .........R-1-15,000 15A57 NET .\ 'YL,4 COASTAL ZONE I "f• .s'. POSSIBLE ' -igIrw, ies'o . : I SETBADICS . . SE AND -( '. ..,. .. SHOWN ON PLAN FOR EACH PARCEL LATERAL LuAm.w,b, . . ... PARKING .. ON SHEET 2 EXISTING TREE GRADING SHOWN PROPOSED ......... _...... .... .. ......4 RENh1AL SPACES TOTAL I •_ -Qt . (TYPICAL) I TRAFFIC S 'j . - ., S — --..-.............._.... 2 UNITS X 10 ADT T - 20 ADT \ Qt . EXIS11'G HOUSE — (Co%crcd h- • GRACING .................. FEASIBLE GRADING ONLY SHOWN. THERE IS NO GRADING PROPOSED ______________________________________ *5 •' . TO BE REMOVED .... - Q) . 14 CONNECTION TH THIS PARCEl. MAP. ANY FUTURE DEVELOPMENT OF A PARCEl. % (Covered by Qs) . .) ', %s .- ,. PROPERTY UNE l CREATED BY THIS PARCEL MAP .L BE REQUIRED TO SUBMIT A GRACING PLAN AND AND 'I .. , . - S •.•. . . PARCEl. MAP OBTAIN A SEPARATE GRADING PT. THE GRADING SHOWN ON SHEET 2 QUANTITIES ARE . . . . ' . . . - 0)1-1,500 CY FILL-65 CY; EXPORT 14.15 C.Y. PROJECTED SEWER USE ......... __._.. 2 EDU'. TOTAL \4 . PROJECTED WATER USE ............... 440 GPO AVE POTABLE WATER USE S., " .5 V . PARCEL 1 . . REONS. REV. DATE By 810 .• - — - 15,811 GROSS & NET ' ., ORIGINAL 06/13/07 CONWAY & ASSOCIATES. INC. ''Ws 183'W \ \ .. REV 0 1 10/05/07 CONWAY & ASSOCIATES, INC. \ ¶ \ ?-t-- \ / SHEET INDEX - '•'- - ' EXISTING H9OSE SITIID DRI \ • .' •. - ': 1 TENTATIVE MAP COVER SHEET -.$EI"EXISTING i'V. at \\iotIstrs AT LEFT - ' . 2 PREUMINARY GRADING PLAN - FOR FEASIBILITY PURPOSES ONLY — DWTIING UTILITIES AND ESPECIALLY UNDERGROUND FACILITIES MAY BE TAKEN \• ' ' 81 ' • ' ... ' '• 3PREIJM1NARYGRADINGSECTIONS LOCATION MAP FROM RE DRAWINGS AND MUST BE FIELD W38FED EXISTING \ ;J) -. '. .'%. T ,_ . . .. . . — BY THE CONTRACTOR BEFORE ANY K WNATSO(WR IS , E0 AC \ ', \ •. , "v' ...' . GEOLOGIC MAP \5 \ — ) VICINITY MAP / EDQS11NG HOUSE O1ES SCALE (REDUCED) \ - MOST EASTERLYR CITY OF OCEANSIDE THE EXiS11Nq LOT HAS AN CXiSTTNG HOME. LEGEND " . - . - ' p" . ( - 'COST WATER LOT 37 THE E,aSilNq IME. POOL. DVE AND RELATED WLL BE p -45% . \ - ."' • - • • - . S.SERVICE OVED iNC RECOROAT1ON OF A FiNAL PARCEL • \ , .. . ... • • . - MAP AND ONCE A DEVELOPMENT PERMIT IS ISSUED CONTACT — "rr t... AT (approx.) '. 0 • • • .' ..• •. , • EITHER ONE OF THE 130 PROPOSED PARCELS. (E.G. A ("L' T ('sITr' TTF*JT'1'' '\ '.7 • • .-...\ • '' '/ - GRADING PERMIT IS ISSUED). GEOLOGIC UNITS ii • • \fl, - .5.. 81 & S , af ARTIFICIAL FILL • \ , • EXISTU ELECTRIC /G Qs RESIDUAL SOIL SSMH \'. . •, SERVICE Qt TERRACE DEPOSITS \\ . S • , \ E5ST86I COAST GEOTECHNICAL \ \\ \•.. P-538107 9ctlJ'IE ROAD TAMARACK AVENUE 60 I I 70'______________________ RIGHT OF WAY • RIGHT OF WAY MAP PREPARED 8I 30 I PROJECT T .35 ' p4' CONWAY & ASSOCIATES, INC. I 5' - IS' - 15 IS' '— F-25--25 I0 ' ' 0.ECT 4'2525 PlO PICO DRIVE CARLSBAD. CA 92008 s.s 755-1453 EXISTiNG I .- EXiSTiNG (XISTINGNG "-I H EXISTING CRIB WALL SLOPE SLOPE SLOPE .1- — — — VAR(ES - E - — — — V EXTSnNQI7 EIGHT AND 01. MICHAEL K. PAS(O. PC 41022 SIDEWALK - EXISTiNG -EXISTING CURB & EXISTING-j (XIS IINGJ 'LEXISTING EXISTING MY RCDISTRAT1ON EXPIRES 03/31/09 AC AC AC • AC £'URB & GUTTER EXISTING STREET SECTION — SKYLINE ROAD NO SCALE EXISTING STREET SECTION — TAMARACK AVENUE NO SCALE 1 EXISTING STOP SIGN TYP OF BOUNDARY DATA J SEC BRG / OQ.TA RADIUS LDIGTh J /f \ II N 59'07' 25' C - 180. 56' 12 N 2r36'04' V EXISTING - 64. 58' SSMH 83 N &-36'04' V - 64. 58' 84 587'OS'57' C - 52.48' 85 05' 36'G4' 441. 00' 43. 22' 86 N 47-04-33- V - 31. 29' '. 87 S 72' 08' 36' V - 48. 12' Be 86' 40' 30' 25. 00' 37. 82' 19 S 14'31'54' C - 6. 40' — 810 6'41'31' 170.00' 91.30' . 811 r04' 12' 770. 00' 106. 45' 4 AC 812 S 12'53' 12' V - 184. 74' WATER MAIN rIQr%.D LOT LIFE .." PER DNG 206-7 PROPERTY LIE DATA WERE DERIVED FROM RECORD SOURCES AND WALL BE CONSIDERED APPROXIMATE EXISTING ABANDONED VALUES ONLY - NOT THE RESULT OF A BOUNDARY 4 SitE.. WATER MAIN PER DWG 166-4 SEE CERTFXATE OF COMPLIANCE RECORDED AUGUST 31, 1981 AS PIS1R1N04T NO. 61-278044 O.R. -. EXISTING 8' ESVC EAENT DATA SEWER LINE /PER DWO 166-4 E 1 EASEMENT FOR ROAD PURPOSES GRANTED TO THE CITY OF CARLSBAD PER OOC NO 81-324278 REED 10/13/1981 E 2 EASEMENT FOR ROAD COB WALL PURPOSES) EXISTING ID' AC WATER LINE GRANTED TO THE CITY or CARLSBAD .. PER DWG 208-7 OOC NO 85-281749 RECORDED 06/06/1985 TOPOGRAPHY SOURCE. EXISTING 2' HWP LINE PER DWGG 166 4 THE TOPOGRAPHIC DATA SHOWN HEREON WAS GENERATED FROM RECORD SOURS AND IS FOR TENTATIVE MAP PURPOSES ONLY. DO NOT USE THE INFORMATION OR THIS PLAN FOR ANY OTHER PURPOSE. UIUIY NOTE-- -A— SHEET 1 OF 4 SHEETS MS 07-05 CDP 07-21 HDP 07- O4ER AND APPLICANT (SUBDIviDER): CAROLTh L HOWARD-JONES a BARBARA D. HOWARD-JONES 4857 PNIOMA ROAD CARLSBAD, CA 92006