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HomeMy WebLinkAboutRP 15-16; 4 + 1 LUXURY LIVING; SITE INSPECTION RESPONSE TO THIRD PARTY GEOTECHNICAL REVIEW - PROPOSED COMMERCIAL BUILDING SITE 3050 MADISON STREET CITY OF CARLSBAD; 2021-01-29January 29, 2021 City of Carlsbad Land Development Engineering 1635 Faraday Avenue Carlsbad, California 92008 Attention: Mr. David Rick SUBJECT: File No. 1106E5A-16 SITE INSPECTION Dear Mr. Rick: Response to Third Party Geotechnical Review Proposed Commercial Building Site 3050 Madison Street City of Carlsbad Project ID:GR2017-0042/RP15-16/CDP15-37 P.O. Box 1195 Lakeside, California 92040 (619) 443-0060 In response to the third party review by Hetherington Engineering, dated November 11, 2020. 1. The consultant should review the project grading and foundation plans, provide any additional geotechnical recommendations considered necessary, and confirm that the plans have been prepared in accordance with the geotechnical recommendations. Please see our attached Foundation Plan Review for the proposed development. 2. The consultant should provide a description of the proposed development including grading, structures/improvements, drainage, use, foundation type, estimated structural loads, etc. In addition, to our updated soil report dated July 02, 2020, we are adding the following items for the proposed development: Drainage at the site should be directed away from foundations, collected and tight lined to appropriate discharge points. Consideration may be given to collecting roof drainage 1 City of Carlsbad File No. l 106E5A-16 January 29, 2021 by eave gutters and directing it away from foundations via non-erosive devices. Water, either natural or from irrigation, should not be permitted to pond, saturate the surface soils or flow towards the foundation. The site should be graded and maintained such that surface drainage is directed away from structures in accordance with 2019, CBC 1803.3, or other applicable standards. Underground utilities should be leak free. Utilities and irrigation lines should be checked periodically for leaks and detected leaks should be repaired promptly. Detrimental soil movement could occur if water is allowed to infiltrate the soil for prolonged periods of time. Landscaping requiring a heavy irrigation schedule should not be planted adjacent to foundations or paved areas. The type of drainage issues found within the project and materials specified and used should be determined by the Engineer of Record. Soil Testers does not practice in the field of corrosion engineering. If after grading the soils seems susceptible to corrosion than Soil Testers can collect a sample to be tested and evaluate the corrosion potential to any subsurface metal structures and be included in the compaction report. Any further evaluation should be done by a corrosion engineer to provide recommendations. Estimated structural loads should be provided by the structural engineer of record. 3. The consultant reports an expansion index of 24 (Low Expansion Potential) and indicates these soils are "non-detrimentally expansive". This description is not consistent with the 2019 California Building Code or the Expansion Index test ASTM: D4829. The Consultant should provide a statement as to weather the foundation and slab recommendations are consistent with the requirements of section 1808.6 ( expansion soils) of the 2019 California Building Code. In our professional opinion the foundation and slab recommendations are still consistent with Low Expansion Potential or non-detrimentally expansive soils to the project development. Therefore, our recommendations are consistent with the requirements of section 1808.6, 2019 California Building Code. 2 City of Carlsbad File No. 1106E5A-16 January 29, 2021 TABLE 1 Classification of Potential Expansion of Soils Using El Expansion Index El Po ential Expansion 0-20 Very Lo 21-50 Lo 51-90 edium 91-130 High >130 Very High 4. The consultant has provided seismic design parameters that are based on ASCE 7-10 criteria. The Consultant should update seismic design recommendations based on requirements of ASCE 7-16 and the 2019 California Building Code. Please see attached Plate I and II. 5. The consultant should provide a list of recommended geotechnical observations and testing during and construction. A pre-construction meeting or conference with the developer, contractor, civil engineer, soil engineer, and the agency inspector in attendance should be held at the site prior to the beginning of the grading operations. Special soil handling requirements can be discussed at that time. Grading of the site should commence with the removal of all vegetation and existing improvements from the area to be graded. Deleterious material and debris such as broken asphalt and concrete, underground pipe materials, wires, trash, etc. if encountered, should be exported from the site and should not be mixed with the fill soils. Abandoned foundations and buried septic tanks or cisterns (if encountered) should be removed and the subsequent depressions and /or trenches should be filled with properly compacted materials as part of the remedial grading. All fill and backfill soils should be placed in horizontal loose layers approximately 8 inches thick, moisture conditioned to a water content of one to three percent above optimum moisture content, and compacted to at least 90 percent relative compaction, as determined by ASTM Test Method D 1557-00. The excavation bottom should then be scarified to a depth of approximately 6 to 8 inches, moisture-conditioned to 1 to 3 percent above optimum moisture content, and re-compacted 3 City of Carlsbad File No. 1106E5A-16 January 29, 2021 to a minimum relative compaction of 90 percent in accordance with ASTM D 1557-00. Excavated sandy or clayey soils should then be uniformly moisture conditioned at above optimum moisture content, placed in 8-inch-thick loose layers and compacted to a relative compaction of at least 90 percent. Import fill soil, if required, should consist of granular materials with low expansion potential (El less than 30 or stated by the soil engineer) and should be compacted as indicated herein. Soil Testers should be notified of the import source and should perform laboratory testing of the soil prior to its arrival at the site to determine its suitability as fill material. Deviations from the recommendations of the Soil Report, from the plans, or from these Specifications must be approved in writing by the owner and the contractor and endorsed by the engineer. If we can be of any further assistance, please do not hesitate to contact our office. This opportunity to be of service is sincerely appreciated. Reference sheet and Plate I and II are part of this report. Respectfully submitted, Chin C. Chen, RPE C34442 CCC/mlj 4 City of Carlsbad File No. 1106E5A-16 January 29, 2021 REFERENCES I. "File No. 1106E5A-16, Site Inspection, Proposed Commercial Building Site, 3050 Madison Street, City of Carlsbad", by Soil Testers, dated July 7, 2016. 2. "Grading Plans For: 4 + 1 Luxury Living" by Landmark Engineering Corporation, dated revised February 15, 2017 (Sheets 1 through 3 of 5). 3. "Third-Party Geotechnical Review (First), Proposed Commercial Building Site, 4 + I Luxury Living, 3050 Madison Street, Carlsbad, California, Project 10: GR2017- 0042/RP15-16/CDPI 5-37", by Hetherington Engineering, Inc., dated May 18, 2020. 4. "File No. 1106E5A-16, Site Inspection, Response to Third Party Geotechnical Review, Proposed Commercial Building Site, 3050 Madison Street, City of Carlsbad", by Soil Testers, dated June 11, 2020. 5. "File No. 1106E5A-16, Site Inspection -Updated, Original Commercial Building Site, 3050 Madison Street, City of Carlsbad", by Soil Testers, dated July 2, 2020. 6. "Grading Plans For: 4 + 1 Luxury Living, 3050 Madison Street", by Landmark Engineering Corporation, dated revised February 15, 2017 (Sheets I through 7). 5 Seismic Ground Motion Values -ASCE 7-16 11.4 3050 Madison Avenue, Carlsbad Site Latitude= 33.1603 Site Longitude= -117.3460 Plate I 11.4.2 Mapped Spectral Accelerations (Site Class B, 2% exceedance in 50 years) Ss Mapped Spectral Response at 0.2 sec. Figure 22-1 S1 = Mapped Spectral Response at 1.0 sec. Figure 22-2 11.4.2 Mapped Spectral Accelerations (Site Class B, 2% exceedance in 50 years) Fa= Site Coefficient for Mapped Spectral Response at 0.2 sec. Table 11.4-1 F v = Site Coefficient for Mapped Spectral Response at 1.0 sec. 11.4.4 Maximum Considered Earthquake (MCE) Spectral Response SMs = MCE Spectral Response at 0.2 sec. = (S5)(Fa) SM1 = MCE Spectral Response at 1.0 sec. = (S1)(Fv) 11.4.5 Design Spectral Response SDs = Design Spectral Response at 0.2 sec. = 2/3(SMs) SD1 = Design Spectral Response at 1.0 sec. = 2/3(SM1) 11.8.3 Design Peak Ground Acceleration (PGAM) 11.4.6 Code Design Response Spectrum T Sa 0 0.344 0.115 0.859 0.577 0.859 Ts= SDl/SDs Sa= SD1/T Table 11.4-2 Equation 11.4-1 Equation 11.4-2 Equation 11.4-3 Equation 11.4-4 Soil Site Class = D Ss = 1.074 S1 = 0.389 Fa= 1.200 = 1.911 SMs = 1.289 SM1 = 0.743 SDs = 0.859 SDl = 0.496 PGAM = 0.568 1.000 1.250 1.500 0.496 0.396 0.330 ASCE 7-1611.4 Design Response Spectrum 1.750 0.283 2.000 0.248 1.000 :§ 0.900 «I (/'J c 0.800 0 i 0.700 G) 0.600 a> (,) ~ 0.500 Cl) "' 0.400 C: 0 C. 0.300 "' Cl) a: 0.200 'i :.. 0.100 ti Cl) C. 0.000 (/'J 0 0.5 1.5 2 2.5 Period, T (sec) Plate II MNI, THITHRI January 26, 2021 Dr. Bruce Sahba First BMS Properties, LLC 1010 Pearl Street #12 La Jolla, California 9203 7 SUBJECT: File No. 1106E5A-16 Dear Dr. Sahba: Grading Plan & Foundation Plan Set Review Proposed Mixed Use Building Site 3050 Madison Street City of Carlsbad P.O. Box 1195 Lakeside, California 92040 (619) 443-0060 We have reviewed the grading plans prepared by Landmark Engineering, Drawing No. 505- 8A and the structural plan set prepared by ARCE Architectural Engineering Services dated August 11, 2020, Project Number l 7.010.03D for the proposed mixed use building site and find that from a geotechnical perspective; the foundation plan conforms to the required minimum specifications in our Update to Site Inspection dated May 18, 2020 based on the onsite soils encountered. A representative of this company must inspect the foundation excavations prior to placement of forms and reinforcing steel to ensure that adequate depth has been achieved. Our recommendations are based upon on the soil type encountered and do not take into consideration the proposed bearing load. If we can be of any further assistance, please do not hesitate to contact our office. This opportunity to be of service is sincerely appreciated. Respectfully submitted, {?~{:e7L Chin C. Chen RPE C34442 CCC/mlj o. C 0344 .9<Jo ..