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Home My WebLink AboutHMP 15-01; MARTIN RESIDENCE; GEOTECHNICAL UPDATE REPORT, PLAN REVIEW AND RESPONSE TO CITY; 2015-05-05RECORD COPY 1//j1 Initial Date VINJE & MIDDLETON E N1NERIN INC. 2450 Auto Park Way Escondido, California 92029-1229 Job #13-234-P Phone (760) 743-1214 May 5, 2015 Fax (760) 732-0343 Mr. Neil Martin 1878 Shadetree Drive Sari Marcos, CA 92078 Geotechnical Update Report and Plan Review and Response to City of Carlsbad Community and Economic Development Review for Martin Residence, Proposed Single-Family Residential Development Adams Street, Carlsbad 1. Introduction We have received and reviewed the most current project plans prepared by Sowards & Brown Engineering (9 marked up sheets, no date), and the Site Plan prepared by Howard Anderson & Associates Architects (sheet AO.1) for the above referenced residential development. Copies of the Grading Plan (sheets 4 and 5 of 9 by Sowards & Brown Engineering) are reproduced and-included as Plates 1 and 2 respectively. We are also in receipt of the City of Carlsbad 1st Review for HMP 15-01-Martin residence dated February 25, 2015. A copy of the pertinent review page is attached. Geotechnical conditions at the project property were previously studied by this office in regards to soil and geotechnical conditions. Our conclusions and recommendations forthe site development were outlined in the following technical reports: "Geotechnical Plan Review Update, Proposed Single-Family Residential Development, Adams Street, Carlsbad, (A.P.N:206-200-03)," Job #13-234-P, report dated November 7, 2013. "Preliminary Soil and Geotechnical Investigation, Parcels A, B, C, APN # 260-200- 03, 04, & 05, Adams Street, Carlsbad, California," Job #98-257-P, report dated August 10, 1998. The above-referenced reports were reviewed in connection with this letter, and are on file with our office. Copies may be obtained upon request. As part of the update and plan review, the site was visited by our project geologist on April 28, 2015. The purpose of this transmittal is to review the attached grading plans and ensure their compatibility to site indicated geotechnical conditions and current codes of standards. Also included are responses to the City of Carlsbad review letter dated February 25, 2015. Mr. Neil Martin May 5,2015 Page If. Development Plan Review Based on our review, the project Grading Plans (Plates I and 2) are in substantial compliance with the referenced Geotechnical Investigation Reports, and depict a feasible development design from a geotechnical point of view. Additionally, the attached plans are substantially unchanged from those used for our most recent Geotéchnical Plan Review Update Report (Reference A), dated November 7, 2013 The property is underlain by stable and competent Pleistocene Age sandstone terrace deposits (Qt) atop Eocene Age formational sandstone rocks with shallow surficial soils The project Grading Plan (Plate 2) depicts the construction of a multi-level, single-family residential structure in the central portion of the property. An S-shaped driveway will connect the residence to Adams Street Driveway gradients will approach 20% maximum that terminates at -a level motor court and garage Retaining and basement walls will be utilized for ground transitioning from the garage to the adjacent dwelling basement and for achieving the upper driveway profiles and lower motor court/garage pad grades Retaining walls / basement walls will approach 13 feet high maximum The residence will consist of split level construction with a lower basement type floor proposed at 33.9 feet in the east section of the dwelling, ascending to 35.0. feet in the central portion of the dwelling, and then to 37.4 feet in the west section of the dwelling Vertical cut excavations on the order of 12 feet and transition retaining all on the order of 15 feet high are proposed for establishing residence's lower basement grades and upper floor levels planned at 51 feet elevation (MSL) Associated improvements will consist of a swimming pool and spa with surrounding concrete decking proposed south Iof the dwelling at elevations ranging from near 34 feet to 38 feet (MSL) connected by stairways. The pool water level is planned at 34.1 feet. Bioretention basins are planned along the eastern and western property margins Exposed graded cut or fill embankments are not planned with all ground transitions achieved by retaining and building basement type walls Project earthworks associated with development of level building surfaces will chiefly consist of cut excavations and wall backfilling operations. Earthwork quantities shown on the plans indicate there will, be 990 yds. of cutting, 560 yds. filling, leaving 430 yds. to be exported Ill. Seismic Ground Motion Values Seismic ground motion, values were determined as part of this investigation in accordance with Chapter 16, Section 1613 of the 2013 California Building Code (CBC) and ASCE 7-10 Standard using the web-based United States Geological Survey, (USGS) ground motion VINJE & MIDDI.EToN ENGINEERING, INC. • 2450 Auto Park Way Escondido, California 92029-1229 • Phone (760) 743-1214 Mr.. Nell Martin May 5, 2015 Page calculator. Generated results including the Mapped (Se, Si), Risk-Targeted Maximum Considered Earthquake (MCER) adjusted for site Class effects (SMs, SM.1) and Design (SDS, SDI) Spectral Acceleration Parameters as well as Site Coefficients (Fa, Fv) for short periods (0.20 second) and 1-second period, Site Class, Design and. Risk-Targeted Maximum Considered Earthquake (MCER) Response Spectrums, Mapped Maximum Considered Geometric Mean (MCEG) Peak Ground Acceleration adjusted for Site Class effects (PGAM) and Seismic Design Category based on Risk Category and the severity of the design earthquake ground motion at the site are summarized in the attached. IV. Conclusions and Recommendations Physical and geotechnical conditions at the project site remain substantially unchanged from those reported in the referenced reports Landslides, geologic instability, or other majorhazards which could preclude site development are not present at the property. The attached grading plan (Plate 2) represents a feasible design for site development from a geotechnical viewpoint All conclusions and recommendations provided in the referenced reports. remain valid. The following amended and updated conclusions and recommendations are also consistent with the current plans and should also be considered where appropriate and as applicable: . . Grading operations for building pad preparation prior to construction should be completed as specified in the referenced reports. In general, vertical cuts approaching 12 feet are planned in connection with the building pad and garage pad construction. Very hard rock or unusual grading problems are not expected. Excavations to complete grading will likely be achieved with moderate efforts using medium size bulldozers or trackhoes All excavations, grading, earthworks, construction, and bearing soil preparation should be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix "J" (Grading) of the 2013 California Building Code (CBC), the Standard Specifications for Public Works Construction, City of Carlsbad Grading Ordinances, the requirements of the governing agencies and following sections, wherever appropriate and as applicable.- All fill materials, processing, placement and compaction requirements remain the same as specified. Geotechnical foundation requirements and soil design parameters will also remain unchanged. VINJE & MwDt.ETN ENGNFEIUNG, INC. 2450 Auto Patk Ww Escondido California 92029-1229 • Phone (760) 743-1214 Mr. Neil Martin May 5, 2015 Page 4. All new backfills should be appropriately keyed-in and benched into. competeAt Terrace Deposits, as directed in the field. All new fills should be compacted to a minimum 90% of the laboratory standard out to the slope face, unless otherwise specified. .. . . . All temporary construction slopes should be constructed as outlined in the referenced reports and as directed in the field. Face of temporary slopes should be protected from excessive runoff or rainfall and stockpiling the excavated materials near the top of construction embankments should be disallowed. COnstruction should be completed in a timely manner minimizing unsupported slope conditions for a prolonged period of time. All temporary construction slopes will require continuous monitoring and geotechnical inspections during the excavation operations. Additional recommendations including revised slope gradients, greater .set backs, completing excavations in limited sections and temporary shoring/trench shield support should be. given at that time as necessary. The project contractor shall also obtain appropriate permits, as needed for grading works near adjacent properties and conform ,to Cal-OSHA and local governing agencies' requirements for trenching/open excavations and safety of the workmen during construction. Hard hats shall be worn at all time. All retaining walls / basement walls .should be provided with well performing backdrain systems as shown on a Retaining Wall Drain Detail, attached as Plate 3 V. Response to City of Carlsbad 1st Review for UMP 15-01-Martin Residence The fol,loviing comments are in response to the City. of Carlsbad review letter dated February 25, 2015 under the Engineering section, issue number 6, a through d.. Factoring the grading quantities shown on the current plans (990 yds. cut, 560 yds. fill, and 430 yds. export), our soil analysis of the property remains unchanged. Revised in the previous section to the 2013 California Building Code. Typically, drainage ditches are only recommended for graded embankments. Based on the grading plan included herein as Plate 1, exposed graded embankments are not planned. Therefore, drainage ditches are currently not warranted. \1INIE & MIDDLETON ENGINEERING, INc. 2450 Auro Park Wiy Escondido, California 92029-1.22) Phone (760) 743-121.4 Mr. Neil Martin May 5, 2015 Page 5 d. Site grading and earthwork construction will not impact the adjacent properties and public right-of-way provided our recommendations are incorporated into the final designs and implemented during the construction phase. Added recommendations, however, may also be necessary and should be given by the project geotechnical consultant during site grading inspections for the protection of adjacent public and private properties and should be anticipated. Geotechnical Engineer of Record (GER) Vinje & Middleton Engineering, Inc. will be the geotechnical engineer of record (GER) for providing a specific scope of work or professional service under a contractual agreement unless it is terminated or canceled by either the client or our firm. In the event a new geotechnical consultant or soils engineering firm is hired to provide added engineering services, grading control engineering observations and compaction testing, Vinje •& Middleton Engineering, Inc. will no longer be the geotechnical engineer of the record. Project transfer should be completed in accordance with the California Geotechnical Engineering Association (CGEA) Recommended Practice for Transfer of Jobs Between Consultants. The new geotechnical consultant or soils engineering firm should review all previous geotechnical documents, conduct an independent study, and provide appropriate confirmations, revisions or design modifications to his own satisfaction The new geotechnical consultant or soils engineering firm should also notify in writing Vinje & Middleton Engineering, Inc. and submit proper notification to the City of Carlsbad for the assumption of responsibility in accordance with the applicable codes and standards (1 997 UBC Section 3317.8). Limitations This geotechnical plan review is not a "Plan Check Review" and does not relieve the responsibility of the project design consultant(s) and contractor(s) to get completely familiarized with the requirements of the project soil report(s) and fully incorporate its recommendations into the project design, plans and construction works, where appropriate, and as applicable. Our review and comments are for general geotechnical conformance of the project plans with the intent of the project soil report and design recommendations. Review of structural and civil engineering calculations, architectural intent and structural and civil engineering design modeling and basis, verification of set back requirements, easements and right-of-ways, as well as code, city and county compliance are beyond geotechnical engineering services. \JNJI: & MID)LETON ENGINEER ING, INC. 2450 Auco Park Wa0 Escondido, Cai,orna 92029-1229 Phone (760) 743-1214 Mr. Neil Martin May 5, 2015 Page 6 It is the owner's or his (her) representative's responsibility to provided copies of all pertinent soil report(s), updates, addendum letters and plan review letters to respective design consultant(s), and general contractor and his (her) subcontractor(s) for full compliance. This opportunity to be of service is sincerely appreciated. If you have any questions or need clarification, please contact the undersigned. Reference to our Job #13-234-P will help to expedite our respOnse to your inquiries. We appreciate this opportunity to be of service to you. VINJE &MIDDLETON ENGINEING, INC. GE #8 HAI oML ( Q P40-2362 Steven J. Melzer CER11FIO* ENGftEiflNQ * CEG #2362 6EOLOGIST rA \'iNjE & MIDI)iETON EN(;1NFiERNG, INC. 2450 Auto Park Way Escondido. California9202.9-1.229 Phone (760 743-121.4 / / H- a f: al 11? 1 r / i '. I, l 4 — — 1J / o t 1 1 p morm cc, l4J Ii ei-J44- I if 4 :1 .... . ......: LE(2—TE—CIJN1C,J\,L LEGEND Tcst trench (7/1/1998) (]f Road Fit] Qt Terrace Deposit TI Formational Rock I - JOB #13-234—PJ [ 1J if -- It L I I r L - - I . 1 4 I •. i?-. H . Cit A GFOTFCF1\ICAI L1-GFND L..................1- ..... .... ........................ . UrSp= Test Trench (7i1!1998 ..;.. ............. / - of Road HI I 77 I } Qi Teticc Dcpc sit .. . ,I Tv i oirnitnn ii Rook 1. I I - - - kL -.--- 0 yr /._. ............ -.i.-......-L: : 'AS BOUF 1 / PLATE 2 IV&M B#i234—Pj - Ys 4 I 4 RETAI NI NG WALL DRAI N DETAIL Typical - no scale ipg. Granular, non-expansive backfill. Compacted Waterproofing Perforated drain pipe 'I Filter Material. Crushed rock (wrapped in filter fabric) or Class 2 Permeable Material (see specifications below) PERMEABLE MArER1.: (SR-i 025) 42 I too 90100 410O : No8 183 Na3 No tc ....::3...., q.u\tt :75 CONSTRUCTION SPECIFICATIONS: Provide granular, non-expansive backfill soil in 1:1 gradient wedge behind wall. Compact backfill to minimum 90% of laboratory standard. Provide back drainage for wall to prevent build-up of hydrostatic pressures. Use drainage openings along base of wall or back drain system as outlined below. Backdrain should consist of 4 diameter PVC pipe (Schedule 40 or equivalent) with perforations down. Drain to suitabl e o u t l e t at minimum 1%. Provide % - i'/" crushed gravel filter wrapped in filter fabric (Mirafi 140N or equivalent). Delete filter fabric wrap if Caltrans Class 2 permeable material is used. Compact Class 2 material to minimum 90% of laboratory standard. Seal back of wall with waterproofing in accordance with architect's specifications. Provide positive drainage to disallow ponding of water above wall. Lined drainage ditch to minimum 2% flow away from wall is recommended. Use cuhlc foot car foot with c Mil ular backfill soil and 4 cubic foot Per foo if expansive hackflt soi is used. fl PLATE 3 13 i L'L&M JOB ,*T2 HMP 15-01 -MARTIN RESIDENCE February 25, 2015 ge5______ listed as the owners on the site plan. Also, the easement listed as delta B on sheet 2 does not appear on the report. Please verify that the easement appears on the updated report. 6. Please address the comments in the marked soils report, dated November 7, 2013. More specifically: Factor the known grading quantities into your soil analysis as the grading quantities are shown on the grading plan. On page 2 and 7, a statement is made that quantities are unknown at this time. Revise California Building Code 2010 to 2013 on page 8 and make any necessary revisions to the report to comply with the current Code. On page 11 of the 1998 report attachment, clarify if a drainage ditch should be added to the existing slope (buffer zone) and if so, specify where the drainage in the brow ditch should and should not discharge. if the drainage ditch comment is intended for manufactured slopes only, then state so. Add a statement that the grades, slopes and structures on the adjacent properties will not be impacted by the proposed development. 7. On the grading plan, please identify the points of drainage discharge from the buildable area to the existing slope to the south. Add energy dissipation at such locations. 8. The retaining walls and stairs proposed within the public easements are subject to an encroachment agreement. Please add a note to the plans stating as such. MELA (Landscape Architect): Please note that the numbers listed below have been referenced on the attached set of redlined plans for ease of locating the specific area of the comment concern. iip 1, Plans shall be prepared by a licensed landscape architect, licensed civil engineer, licensed architect, or other qualified professional licensed by the state to do this work. Please provide a valid license stamp on the landscape plans. P 2. Please add the street name. 11) 3. Please show and label all existing and proposed easements. Insure no trees are located within public utility easements. 4. The plan shall demonstrate that plants, when installed and at maturity, will be positioned to avoid obstructing motorists' views of pedestrian crossings, driveways, roadways and other vehicular travel ways. At medium to high use driveways, landscape elements over 30 inches in height (including planting measured at maturity) as measured from adjacent street grade are not permitted. The 30 inch height limitation applies at driveways 25 feet from the edge of the apron outward along the curb, then 45 degrees in toward the property. Please address, orth arrow and bar scale on the landscape pan. 5. Please provide a n . indicate positive surface dcc age (2% rrade in picntin areas) away from structures and tern nrting in an aupnoved drainage sy%em. 1CResp.me 5pectnitn f)eiçjri Reqsponw Spectrum 8.15 0.12 rj 18 --------~------i--------------a----1--- 021 0.0 108 0.28 lOs 1.20 2.02 0.0) ins 110: r1Od, 1 (vOn) Design Maps Summary Report Page 1 of I Design maps Summary Report User—Specified Input Report Title Adams Street, Carlsbad Fri May 1, 2015 14:05:54 UTC Building Code Reference Document ASCE 7-10 Standard (which utiiizes USGS hazard data available in 2008) Site Coordinates 33,1450N, 117.3268°W Site Soil Classification Site Class D "Stiff Soil" USGS—Provided Output S = 1.1359 = 1.187g S. = 0.791 g S = 0.436 g SM2 = 0.682 g S,, = 0.454 g For information on how the SS and Si values above have been calculated from probabilistic (risk-targeted) and deterministic ground motions in the direction of maximum horizontal response, please return to the application and select the "2009 NEHRP" building code reference document. For PGAM, 1,, C, and C values, please view the detailed report. 0lthouah this iniormtion is I product oft! U.S. Goicgicl Survoy, no orovidO no O1rr2flty, evprescd or inp0d, sa to th accuracy of :he Onto contained ihoroin This lord is !,CI: a sutistitlits for isdinirel subjo:t niat:sr0owldpe. I 5/1/2015 vesigri iviaps uetaneu Keport Page 1 of 6 Design Maps Detailed Report ASCE 7-10 Standard (33.1450 N, 117.3268°W) Site Class D - "Stiff Soil", Risk Category 1/11/111 Section 11.4.1 - Mapped Acceleration Parameters Note: Ground motion values provided below are for the direction of maximum horizontal spectral response acceleration. They have been converted from corresponding geometric mean ground motions computed by the USGS by applying factors of 1.1 (to obtain S) and 1.3 (to obtain S1). Maps in the 2010 ASCE-7 Standard are provided for Site Class B. Adjustments for other Site Classes are made, as needed, in Section 11.4.3. From Figure 22-1' Ss = 1.135 g From Figure 22-2 w S = 0.436 g Section 11.4.2 - Site Class The authority having jurisdiction (not the USGS), site-specific geotechnical data, and/or the default has classified the site as Site Class D, based on the site soil properties in accordance with Chapter 20. Table 20.3-1 Site classification Site Class VS Nor Nd, S,, Hard Rock >5,000 ft/s N/A N/A Rock 2,500 to 5,000 ft/s N/A N/A Very dense soil and soft rock 1,200 to 2,500 ft/s >50 >2,000 psf Stiff Soil 600 to 1,200 ft/s 15 to 50 1,000 to 2,000 psf Soft clay soil <600 ft/s <15 <1,000 psf Any profile with more than 10 ft of soil having the characteristics: a Plasticity index P1 > 20, Moisture content w ~: 40%, and Undrained shear strength S. < 500 psf F. Soils requiring site response See Section 20.3.1 analysis in accordance with Section 21.1 For SI: lft/s = 0.3048 rn/s llb/ft2 = 0.0479 kN/m2 bttp://eh1.3 -eaithcuake. wrusgs. gov!clesignnaps/us/report. hp?teipa 'nin ma.l&iathude"- ..5/ J, /2015 Design Maps Detailed Report Page 2 of 6 Section 11.4.3 - Site Coefficients and Risk-Targeted Maximum Considered Earthquake (MCE) Spectral Response Acceleration Parameters Table 11.4-1: Site coefficient F Site Class Mapped MCE Spectral Response Acceleration Parameter at Short Period S 0.25 Ss = 0.50 Ss = 0.75 S = 1.00 S? 1.25 A 0.8 0.8 0.8 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.2 1.2 1.1 1.0 1.0 D 1.6 1.4 1.2 1.1 1.0 E 2.5 1.7 1.2 0.9 0.9 F SeeSection 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of S For Site Class = D and S. = 1.135 g, F. = 1.046 Table 11.4-2: Site coefficient F. Site Class Mapped MCE Spectral Response Acceleration Parameter at 1-s Period S !~ 0.10 S = 0.20 S1 = 0.30 S = 0.40 S ~! 0.50 A 0.8 0.8 0.8 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.7 1.6 1.5 1.4 1.3 D 2.4 2.0 1.8 1.6 1.5 E 3.5 3.2 2.8 2.4 2.4 F See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of S1 For Site Class = 0 and S. = 0.436 g, F, = 1.564 httn:I/ehp3earthquake.wl.tLs;s 5/1/2015 ueslgu iviaps uetaiieu report Page 3 of 6 Equation (11.4-1): - 1.046 x 1.135 = 1.187 g Equation (11.4-2): S = F,S = 1.564 x 0.436 = 0.682 g Section 11.4.4 - Design Spectral Acceleration Parameters Equation (11.4-3): SOS = 2/3 Sms = 2/3 x 1.187 = 0.791 g Equation (11.4-4): 501 = % S 1 = % x 0.682 = 0.454 g Section 11.4.5 - Design Response Spectrum From Figure 22-l2' TL = 8 seconds Figure 11.4-1: Design Response Spectrum I f I / Tr, <ri, s=sn Ar - Por.td. T {1#e 1112015 0 0 Design Maps Detailed Report Page 4 of 6 Section 11.4.6 Risk-Targeted Maximum Considered Earthquake (MCE) Response Spectrum The MCEr, Response spectrum is determined by multiplying the design response spectrum above by 1.5. Prid, T (ct itp://ehn3-eartiiquae.wr. Cr t1e ... 5/112015 ues.tgn iVlaps iieiaiieu iteport Page 5 of 6 Section 11.8.3 - Additional Geotechnical Investigation Report Requirements for Seismic Design Categories D through F From Figure 22-7 PGA = 0.449 Equation (11.8-1): PGA I = FPGAPGA = 1.051 x 0.449 = 0.472 g Table 11.8-1: Site Coefficient F, Site Mapped MCF Geometric Mean Peak Ground Acceleration, PGA Class PGA PGA = PGA = PGA = PGA > 0.10 0.20 0.30 0.40 0.50 A 0.8 0.8 0.8 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.2 1.2 1.1 1.0 1.0 D 1.6 1.4 1.2 1.1 1.0 F 2,5 1.7 1.2 0.9 0.9 F See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of PGA For Site Class = 0 and PGA = 0.449 9, F = 1.051 Section 21.2.1.1 - Method 1 (from Chapter 21 - Site-Specific Ground Motion Procedures for Seismic Design) From Figure 2217(51 Cgs = 0.945 From Figure 2218 E61 = 0.997 http://ehp3 - .5/1/201.5 Design Maps Detailed Report Page 6 of 6 Section 11.6 - Seismic Design Category Table 11.6-1 Seismic Desiqn cateoory Based on Short Period Resoonse Acceleration Parameter VALUE OF S05 RISK CATEGORY lorll III IV SOS < 0.167g A A A 0.1679 5 S05 < 0.33g B B C 0.33g 5 S0s < 0.50g c c D 0.50gS05 D D D For Risk Category = I and S05 = 0.791 g, Seismic Design Category = D Table 11.6-2 Seismic Desicin Catecory Based on 1-S Period Resoonse Acceleration Parameter VALUE OF S01 RISK CATEGORY loril III IV S01 < 0.067g A A A 0.067g :5 S01 < 0.133g B B C 0.133g S01 < 0.209 C C D 0.209 :5 S., D D D For Risk Category = I and S,, = 0.454 g, Seismic Design Category = D Note: When S is greater than or equal to 0.75g, the Seismic Design category is E for buildings in Risk Categories I, II, and III, and F for those in Risk category Iv, irrespective of the above. Seismic Design Category "the more severe design category in accordance with Table 11.6-1 or 11.6-2" = D Note: See Section 11.6 for alternative approaches to calculating Seismic Design category. References Figure 22-1: http ://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/20 10_ASCE-7_Figu re22- 1. pdf Figure 22-2: http ://earthquake. usgs. gov/hazards/design maps/down toads/pdfs/20 1O_ASCE-7Jigu re22-2. pdf Figure 22-12: http ://earthquake.usgs.gov/hazards/desig n maps/down loads/pdfs/20 1O_ASCE-7_Figu rej2- 12.pdf Figure 22-7: http ://earthquake.usgs. gov/hazards/design maps/down loads/pdfs/20 1OASCE-7_Figu re_22-7. pdf Figure 22-17: http://eaquake.usgs.gov/hazards/designmaps/downloads/pdfs/2O1QAScE-7_Figure22- t7.pdf Figure 22-18: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/2010_ASCE-7_Figurej2- 18. pdi http://e.hp3 ..eaithquakewr. I.. 5/1/2015