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Home My WebLink AboutPD 2019-0009; 2700 ARGONAUTA RESIDENCE; ADDENDUM NO. 1; 2019-06-10ENGINEERING L DESIGN GROUP wwwdesigngroupca .com 2121 Montiel Road, San Marcos, CA 92069 760.839.7302 RECORD COPY Date: June 10th, 2019 Initial Date To: Keith Webster 1460 Orpheus Avenue Encinitas, CA 92024 Re: Proposed new residence to be located at Argonauta Street (APN: 215-460-05), Carlsbad, California Subject: Addendum No. 1 PD 2019-0009 GR 2019-0014 DWG 517-6A Ref: "Preliminary Geotechnical Investigation and Foundation Recommendations Proposed New Residence to be Located at (APN: 215-460-05) Argonauta Street, Carlsbad, California", prepared by Engineering Design Group, Project No. 175864-1, dated January 4th, 2019. "Grading Plans for Webster Residence" by Engineering Design Group, DWG 517-6A. Hetherington Engineering Inc., Third-Party Geotechnical Review (First Review) - Proposed New Residence - Argonauta Street (APN:215-460-05), dated May 2, 2019. PURPOSE We have prepared the following addendum to our original report (Reference No. 1) to address city/third- party comments referenced above (Reference No. 3) for the proposed new residence to be located at Argonauta Street (APN: 215-460-05) in the City of Carlsbad (Reference No. 2). As we understand the proposed development is consistent with that described in our original report, to consist of the construction of a new, multi-level, single-family residence and typical hardscape/landscape improvements. Our responses to review comments are incorporated into this addendum report. SITE DESCRIPTION The subject property is located at Argonauta Street (APN: 215-460-05), in the City of Carlsbad. As EDG Project No. 186021-1 RECEIVED JUL 02 2019 LAND DEVELOPMENT ENGINEERING ENGINEERING DESIGN GROUP GEOTECHNWA4 Civil. STRUCTURAL CONSULTANTS described in the original report, the general topography of the site area consists of foothill terrain. The site generally descends from south to north. Based upon review of site topography, the overall elevation change is approximately 40 feet, with an approximate overall gradient of 15%. As stated in our original report, the site is currently undeveloped. The subject site is covered with limited vegetative cover, a few trees and isolated localized rock outcroppings. PROPOSED DEVELOPMENT The proposed development will consist of the construction of a new, multi-level, single-family residence with basement elements, attached garage, driveway, retaining walls, hardscape/Iandscape areas and a detention basin. We understand the residence will be founded with shallow, continuous-type foundations. The proposed grading work will include new cut and fill slopes, including grading for proposed driveway, excavations for basement pad, construction of new retaining walls, private storm drain system and stormwater detention facilities. In the developed condition, runoff is anticipated to be captured by a private storm drain system and directed to the stormwater detention basin constructed at the northwest portion of the site. Structural loads are anticipated to be commensurate with standard single-family residential construction with basement elements. SUBSURFACE CONDITIONS Please see attached Geotechnical Map and Geologic Cross-Sections of the attachments herein, Figure A and Figure B respectively. S. GEOLOGIC SETTING San Diego lies within the Peninsular Ranges of California. The Peninsular Ranges province varies in width from approximately 30 to 100 miles and is characterized by northwest-trending mountain range blocks separated by similarly trending northwest-trending faults (Norris and Webb, 1990). Based upon the findings of our subsurface investigation and review of readily available pertinent geologic and geotechnical literature the site is underlain by Jurassic-aged metamorphosed and unmetamorphosed volcanic and sedimentary rocks (Mzu, previously Kisp - Kennedy 2008). A general description of each material type was presented in our original report. The general distribution of these materials across the site is presented in figures A to C of this addendum. As stated in our original geotechnical report, the site is not located within a currently established Alquist-Priolo Earthquake Fault Zone. No active or potentially active faults with the potential for surface rupture are known to pass directly beneath the site.. Therefore, the potential for surface rupture due to faulting occurring beneath the site during the design life of the proposed residence EDG Project No. 186021-1 ENGINEERING DESIGN GROUP G(OTSCHNICAL CIViL. STRUCTURAL CONSULTANTS is considered low. The site however, is in the seismically active southern California region, and could be subjected to moderate to strong ground shaking in the event of an earthquake on one of the many southern California faults as stated in out original report. The proposed development's occupancy category is II. The 2016 CBC Seismic Design Parameters provided in our original report still apply, additionally, Ss = 1.032 and Si = 0.4. As described in the original report, foundations shall extend into competent material, as determined in the field, to consist of competent rock material or recompacted fill. SLOPES We have reviewed the project's current preliminary grading plans (Reference No. 2); the proposed improvements have been prepared in general accordance with our geotechnical recommendations. As stated in our original report, the subject site gently slopes from south (front) to north (rear). The site does not generally present any steep exposures or vertical geologic features. The average gradient of the ungraded slopes is approximately 15 percent. Based upon our review of the proposed improvements, including related grading and the subject site's geologic structure, are favorable in respect to slope stability. The development of the subject site and proposed site improvements as identified on the referenced plans and indicated on our cross sections, will not destabilize or negatively impact the natural slopes that will remain. SETTLEMENT The maximum expected total static settlement for the proposed structure supported on.a conventional foundation system utilizing a maximum allowable soil bearing pressure of 2,500 psf (deriving support in competent re-compacted fill material) or up to 3,500 psf (in competent meta-volcanic material, per our original report) is estimated to be on the order of 1 inch. Differential settlement if not expected to exceed /2 inch over a distance of twenty (20) feet. All design parameters and values provided in our original report (Reference No.1) remain applicable. If you have any questions regarding this report, please do not hesitate to contact our office. Sincerely, ENGINEERING DESIGN GROUP EDG Project No. 186021-1 ENGINEERING DESIGN GROUP GEOTECHNICAL. CiVil, STRUCTURAL CONSULTANTS SIok E. C 65122 C1 I (\OHALG (. (STEVEN BRYN4TNOIS\ NG2263 CERTIFIED J• V ENGINEERING / Steve Norris Geotechnical Engineer GE 2590 Certified Engineering Geologist EG 2263 Erin Rist Licensed Civil Engineer C 65122 Attachments: Figure A - Geologic Map Figure B - Geologic Cross-Section A-A' Figure C - Geologic Cross-Section. B-B' EDG Project No. 186021-1 ENGINEERING DESIGN GROUP G(OTECHNICAI, CIVIL. STRUCTURAL CONSULTANTS REFERENCES California Geological Survey, Probabilistic Seismic Hazards Mapping Ground Motion Page. California Department of Conservation, Division of Mines and Geology, Fault Rupture Zones in California, Special Publication 42, Revised 1990. California Department of Conservation, Division of Mines and Geology, DMG Open-File Report 95-04, Landslide Hazards in the Northern Part of the San Diego County Metropolitan Area, San Diego County, California - Landslide Hazard Identification Map No. 35- Encinitas Quadrangle (Plate D), dated 1995. County of San Diego, Planning and Development Services Archive, Various Aerial Photographs, Various Dates. Day, Robert W. 1999. Geotechnical and Foundation Engineering Design and Construction. McGraw Hill. 6. DZN Partners, Plans for Argonauta Project, Dated 01-04-2018. Greensfelder, R.W., 1974 Maximum Credible Rock Acceleration from Earthquakes in California Division of Mines and Geology, Map Sheet 23. Kennedy, Michael P. and Tan Siang S., Geologic Map of the Oceanside 30'x60' Quadrangle, San Diego County California. Dated 2002. Lee, L.J., 1977, Potential foundation problems associated with earthquakes in San Diego, in Abbott, P.L. and Victoria, J.K., eds. Geologic Hazards in San Diego, Earthquakes, Landslides, and Floods: San Diego Society of Natural History John Porter Dexter Memorial Publication. Norris, Robert M. and Webb, Robert W., Geology of California, 2nd edition, 1990. Ploessel, M.R. and Slossan, i.E., 1974 Repeatable High Ground Acceleration from Earthquakes: California Geology, Vol. 27, No. 9, P. 195-199. State of California, Fault Map of California, Map No. 1, Dated 1975. State of California, Geologic Map of California, Map No. 1, Dated 1977. Structural Engineers Association of Southern California (SEAOSC) Seismology Committee, Macroseminar Presentation on Seismically Induced Earth Pressure, June 8, 2006. is. Tan, Siang S. and Kennedy, Michael P., Geologic Maps of the Northwestern Part of San Diego County, California. Plate 2. Geologic Map of the Encinitas and Rancho Santa Fe 7.5' Quadrangles, San Diego County, California. Dated 1996. U.S. Army Corps of Engineers, 1985, Coast of California Storm and Tidal Waves Study, Shoreline Movement Data Report, Portuguese Point to Mexican Border, dated December U.S. Army Corps of Engineers, 1985, Coast of California Storm and Tidal Waves Study, Coastal Cliff Sediments, San Diego Region (CCSTWS 87-2), dated June. Van Dorn, W.G., 1979 Theoretical aspects of tsunamis along the San Diego coastline, in Abbott, P.L. and Elliott, W.J., Earthquakes and Other Perils: Geological Society of America field trip guidebook. Various Aerial Photographs. LEGEND Artificial Fill (buried units shown in parentheses) Metamorphosed and unmetamorphosed volcanic and sedimentary rocks, undivided (Mesozoic) T-2 Exploratory Trench Geologic Contact A1 A' Geologic Cross—Section - - - Property Boundary - - - - Setbacks (562)_---....A562) Existing Contours Proposed Contours ' '- ENGINEERING' 2121 Montiel Road, San Marcos, CA 92069 DESIGN GROUP 760.839.7302 www.designgroupca.com A JOB NAME: JOB ADDRESS: JOB NO.: DATE: WEBSTER RESIDENCE Argonauta Street (APN:215-460-05) Carlsbad, California 92009 175864-1 6-3-2019 FIGURE: A 0+00.00 540. 00 - 530.00 - 520.00 - 510.00 - 500.00 - 490.00 - 480.00 - --•----•- -_.--__-4PR0P0SED-3STt Y__.-_._-.--4--.-__-_...- ......F----- :::L:=: hT1L: - P)0JECTI0N-0Fz __ PROPOSED-IWALL-/—STAIRS--- I - E= 7. 1STFLOOR - - -' - APPR0X—LIM1TS- i)FCE0r0CIC - BASEMENT- _____•_... S()_(4) -- =7 ------ -CONTACT----- 0+00.00 0+25.00 1+00.00 1+70.00 I I I I I - cjlnn 0+50.00 0+75.00 1+00.00 1+25.00 1+50.00 .J,J.(Jv 530.00 520.00 510.00 500.00 - 490.00 - 480.00 - 475.00 1+70.00 SECTONA - A' SCALE: 1" = 20'— 0" IN ENGINEERING 2121 Montiel Road, San Marcos, CA 92069 DESIGN GROUP 760.839.7302 www.designgroupca.com JOB NAME: JOB ADDRESS: JOB NO.: DATE: WEBSTER RESIDENCE Argonauta Street (APN:21 5-460-05) Carlsbad, California 92009 175864-1 6-3-2019 FIGURE: B 1510.00- 500.00- 520.00 - 0+00.00 493.00 - 0+00.00 1,1101.141 'y - :1I'13.LW .. VV p —M19 "! . Y "WGRADE ________________-_________ ithered -A Wo- l ' PROX LIMITS OF GEOLOGIC L - ... . .. ....- . 0+25.00 0+50.00 0+75.00 SECTION B - B SCALE: 1" = 10-0" 1+00.00 pppcç _TI9V 1+00.00 1+25.00 - 493.00 1+40.00 1+40.00 - 520.00 W1101010 - 500.00 I ENGINEERING Roii p 2121 Montiel Road, San Marcos, CA 92069 P1 DESIGN 760.839.7302 www.designgroupca.com JOB NAME: JOB ADDRESS: JOB NO.: DATE: WEBSTER RESIDENCE Argonauta Street (APN:21 5-460-05) Carlsbad, California 92009 175864-1 6-3-2019 FIGURE: C