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Home My WebLink AboutCDP 00-62; Hamilton Residence; Soils Report; 2001-05-22Eni/nieerinf^NC. CIVIL GEOTECHNICAL i QUALITY ENGINEERING FOUNDATION DESIGN • LAND SURVEYING • SOIL TESTING CONSTRUCTION MANAGEMENT i INSPECTION CLIENT: HAMILTON PROJECT: HAM 501 U DATE: 22 MAY 2001 JOHN & BARBARA HAMILTON 2335 Pio Pico Drive Carlsbad, CA. 92008 Attention: Mr. John Hamilton Mr. Sam Wright Subject: Soil Update Report for the Proposed Construction for the Residence located at 2335 Pio Pico Drive, Oceanside, CA. (APN: 156-350-11) Reference (a): Preliminary Geotechnical Soils Investigation Report by B & B Engineering, Inc. dated 27 June 1998. (b): Results of Compaction Testing Report by B & B Engineering, Inc. dated 14 October 1998. Gentlemen: Pursuant to your request, we have completed our site inspection in regard to the existing soil conditions for the subject site. On May 22, 2001, a representative from our firm visited the site in order to evaluate the existing surface soil conditions relative to the proposed construction. According to Reference (b), this lot was graded and tested under engineering supervision between August 27 and September 4, 1998. The grading was performed in accordance with Reference (a) and the City ofCarlsbad Grading Ordinance. Reference (b) report indicated sufficient testing that showed over 90% relative compaction in the fill portion of the lot. No geotechnical conditions were encountered which would preclude the development ofthe site. Based on our visual inspections and observations in the field and our review ofthe Geotechnical Reports, References (a) & (b), the following conclusions were derived: The general overall surface soil conditions do not appear to have changed 1 1611-ASO. MELROSE DRIVE 11285, VISTA. CA 92083-5497 • 760-945-3150 • FAX: 760-945-4221 K^iS Eufiiueerin^hw. CIVIL GEOTECHNICAL i QUALITY ENGINEERING FOUNDATION DESIGN • LAND SURVEYING • SOIL TESTING CONSTRUCTION MANAGEMENT S INSPECTION significantly since the rough grading operation. It is our opinion that the cut/fill pad may support the proposed structure. Foundations shall be sized and constructed in accordance with the recommendations found in Reference (b). For foundation design purposes, an allowable bearing strength of 1450 psf may be utilized for all continuous or spread footings founded in dense or imported native soils compacted to 90% relative compaction per ASTM D 1557-91. This design bearing value is in accordance with the Uniform Building Code. It is our opinion that the soils underlying the subject lot may support the proposed residential construction. However, the conclusions and recommendations found in the latter part of this report shall be incorporated in the design plans. GEOLOGIC HAZARDS According to published information, there are no known active or potentially active faults on or in the immediate vicinity of the subject site. Therefore, the potential for ground rupture at this site is considered low. There are, however, several faults located within a close proximity to this site that the movement associated with them could cause significant ground motion. The following table presents the distance of major faults from the site, the assumed maximum credible earthquake magnitudes and estimated peak accelerations anticipated at the site. The probability of such an earthquake occurring during the lifetime of this project is considered low. The severity of ground motion is not anticipated to be any greater at this site than in other areas of San Diego County. SEISMICITY OF MAJOR FAULTS MAXIMUM CREDIBLE ESTIMATED FAULT DISTANCE MAGNITUDE(RICHTER) ACCELERATION(g) Rose Canyon 5 mi. 7.0 0.25 Elsinore 29 mi. 7.5 0.35 San Jacinto 52 mi. 7.8 0.17 San Andreas 78 mi. 8.3 0.12 The following information is presented relative to the subject site and Seismic Zone 4 per the U.B.C: 2 1611-ASO. MELROSE DRIVE #285. VISTA. CA 92083-5497 • 760-945-3150 • FAX: 760-945-4221 K^K Ihifiineeiin^lnCa CIVIL GEOTECHNICAL i QUALITY ENGINEERING FOUNDATION DESIGN • UND SURVEYING • SOIL TESTING CONSTRUCTION MANAGEMENT i INSPECTION (z) Seismic zone factor = 0.4 (Na) Near-source factor = 1.2 (A) Seismic source type = A (Sd) Soil profile type = Sd (Ca) Seismic coefficient = 0.44 Na (Cv) Seismic coefficient = 0.64 Nv (Nv) Near-source factor = 1.2 LIQUEFACTION POTENTIAL Liquefaction analysis of the soils underlying the site was based on the consideration of various factors which include the water level, soil type gradation, relative density, intensity of ground shaking and duration of shaking. Liquefaction potential has been found to be the greatest where the ground water level is shallow and loose fine sands occur within a depth of 50 feet or less. These conditions are not present within the site area and, therefore, the potential for generalized liquefaction in the event of a strong to moderate earthquake on nearby faults is considered to be low. STABILITY The relatively dense nature of the slopes within the site and the nature ofthe material underlying the site generally preclude the occurrence of major landslide conditions. The area surrounding the site is not known to be within an area of ground subsidence. The potential for deep seated slope failure at the subject site is considered low. The site surface materials consist of silty sands that are relatively dense in their dry state. These materials are susceptible to erosion. Drainage control is essential to maintain the stability of any planned slopes or slope areas. FOUNDATIONS For foundation design purposes, the following earth pressures were calculated based on our Shear Test Results of the nafive soils per Reference (a) and based on a foundation depth and width of 12 inches: 3 1611-A SO. MELROSE DRIVE 11285. VISTA, CA 92083-5497 • 760-945-3150 • FAX: 760-945-4221 IS^I{ Eniiineerin^luc. CIVIL GEOTECHNICAL 4 QUALITY ENGINEERINQ FOUNDATION DESIGN • UND SURVEYING • SOIL TESTING CONSTRUCTION MANAGEMENT i INSPECTION Shear Test: Cohesion = 600 psf; Angle of Fricfion =16° Allowable Bearing Value = 1450 psf Equivalent Fluid Pressure = 76 psf Passive Lateral Resistance = 235 psf Active Pressure = 76 psf Coefficient of Fricfion = 0.35 Expansion Index = 68 (MODERATE) These values are for dead plus live loads and may be increased by one-third (1/3) for seismic and wind loads where allowed by code. These design bearing values are in accordance with the Uniform Building Code and were calculated based on Terzaghis' Formula. It is recommended that the continuous perimeter foundafions and concrete slabs for a light weight wood-framed structure shall be reinforced in accordance with the following minimum designs: a. Foundafion dimensions: it is recommended that the continuous perimeter foundations for a single story structure shall extend a minimum depth of 18 inches and a minimum width of 12 inches into firm nafive soils with a relative compacfion exceeding 90%). A minimum of 24 inches deep by 15 inches wide shall be used for a two story structure. b. All foundations shall be reinforced with at least four No.4 steel bars, two bars shall be placed 3 inches from the top of the foundation and the other bars shall be placed 3 inches from the bottom. As an altemative to the four No. 4 steel rebars, one No. 5 steel rebar top and bottom may be used. c. All interior concrete slabs shall be a minimum of four inches in thickness and reinforced with a minimum of No. 3 rebar at 18 inches on center both ways placed in the center of the slab. The slab steel reinforcement shall be bent downward into the perimeter footings and connected to the foundation steel at 18 inches on center. In order to minimize vapor transmission, an impermeable membrane (ie: 6 mil visqueen) shall be placed over 2 inches of clean, poorly graded, coarse sand, decomposed granite, or crushed rock. The membrane shall be covered with 2 inches of sand to protect it during construction and the sand should be lightly moistened just prior to placing concrete. All concrete used on this project 4 1611-A SO. MELROSE DRIVE #285. VISTA, CA 92083-5497 • 760-945-3150 • FAX: 760-945-4221 K^IS Euifineevm^lnc. CIVIL GEOTECHNICAL t QUALITY ENGINEERING FOUNDATION DESIGN • UND SURVEYING • SOIL TESTING CONSTRUCTION MANAGEMENTS INSPECTION shall have a minimum compressive strength of 2500 psi unless otherwise stated on the Building Plans. If imported soil materials are used during grading to bring the building pad to the design elevations, or if variations of soils or building locations are encountered, foundation and slab designs shall be reevaluated by our firm upon the complefion of the rough grading operation and the foundation excavations. Footings located on or adjacent to the top of slopes shall be extended to a sufficient depth to provide a minimum horizontal distance of 7 feet between the bottom edge of the footing and the face of the slope. These foundation recommendations are minimum design requirements for the soils encountered during this investigafion; however, actual foundations shall be designed by the Structural Engineer for the expected live and dead loads, and for wind and seismic loads. Findings of this Report are valid as of this date; however, changes in conditions of a property can occur with passage of time, whether they be due to natural process or works of man on this or adjacent properties. In addition, changes in applicable or appropriate standards occur whether they result from legislation or broadening of knowledge. Accordingly, findings of this Report may be invalidated wholly or partially by changes outside our control. Therefore, this Report is subject to review and should not be relied upon after a period of one year. In the event that any changes in the nature, design, or location of buildings are planned, the conclusions and recommendations contained in this Report shall not be considered valid unless the changes are reviewed and the conclusions of this Report are modified or verified in writing. This Report is issued with the understanding that it is the responsibility of the owner or of his representative to ensure that the information and recommendafions contained herein are called to the attention of the project Architect and Engineer and are incorporated into the plans. Further, the necessary steps shall be taken to ensure that the contractor and subcontractors carry out such recommendations in the field. 1611-ASO. MELROSE DRIVE #285, VISTA, CA 92083-5497 • 760-945-3150 • FAX: 760-945-4221 Eufiiueeriufi, fnc. CIVIL GEOTECHNICAL t QUALITY ENGINEERING FOUNDATION DESIGN • UNO SURVEYING • SOIL TESTING CONSTRUCTION MANAGEMENTS INSPECTION It is recommended that the Soil Engineer be provided the opportunity for a general review of the final design plans and specificafions for this project in order that the recommendations of this report may be properly interpreted and implemented in the design. It is also recommended that the Soil Engineer be provided the opportunity to verify the foundafion and slab construcfion in the field prior to placing concrete. (If the Soil Engineer is not accorded the privilege of making these reviews, he can assume no responsibility for misinterpretafion of his recommendafions). The Soil Engineer has prepared this Report for the exclusive use of the client and authorized agents. This Report has been prepared in accordance with generally accepted soil and foundation engineering pracfices. No other warranties, either expressed or implied, are made as to the professional advice provided under the terms of this agreement, and included in the Report. B&B Engineering Inc. and Associates appreciate this opportunity to be of service. Should you have any questions regarding this project, please do not hesitate to contact us. Sincerely, frthur C. Beard RCE RQE RGE Chief Engineer 1611-ASO. MELROSE DRIVE #285, VISTA. CA 92083-5497 • 760-945-3150 • FAX: 760-945-4221