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HomeMy WebLinkAboutPA2022-002_20220215_GeoSoils responseGeotechnical C Geologic C Coastal C Environmental 5741 Palmer Way C Carlsbad, California 92010 C (760) 438-3155 C FAX (760) 931-0915 C www.geosoilsinc.com February 15, 2022 Helle McIain 8 Strands, 913 Balmoral 2 Praed Street London, UK W21JN SUBJECT: Response to City of Newport Beach Plan Check Comment, PA2022-002, for 2172 E Ocean Front, Newport Beach, California. REFERENCE: Coastal Hazard and Wave Runup Study, 2172 East Oceanfront, Newport Beach, California, by GeoSoils Inc., dated November 8, 2021. Dear Helle Mclain: At your request, we are pleased to respond to Plan Check (PA2022-02) Comment #1. For ease of review the comment is provided below in italics followed by our response. Unless specifically superceded herein, the conclusions and recommendations of the above referenced Coastal Hazard and Wave Runup Study remain valid and pertinent. 1. Coastal hazards report: Coastal Hazards report should interpolate sea level rise data to the year 2100. Waterproofing of the residence will be required to 14.4 feet NAVD88. The referenced coastal hazard study uses the California Coastal Commission Sea Level Rise Guidance (CCCSLRG) document to determine the potential range of sea level rise expected over the life of the development. The life of the development is 75 years, which at the date of the report, would be the year 2096. In addition, the CCCSLRG requires the use of the “best available science” to determine the SLR range over the life of the development. The CCCSLRG tables are based upon science that is now over 10 years old, and that science does not reflect what is currently known about the rate of SLR. The referenced GeoSoils Inc. report provides the best available science at this time based upon currently measured SLR and more updated NOAA SLR models. However, based upon the plan check comment the City of Newport Beach is requiring the use of the possible, but not probable 0.5%, high emissions, SLR estimate for the year 2100 of 6.7 feet. If 6.7 feet of SLR is added to the 100-year design water elevation of 7.7 feet NAVD88, the future design water elevation is +14.4 feet NAVD88. In order to mitigate this potential flood hazard at the end of the life of the development, the proposed development should be waterproofed (by design) to a minimum elevation of +14.4 feet NAVD88. 2 CLOSING The proposed project minimizes risks from flooding. GSI certifies* that coastal hazards will not impact the property over the next 75 years and that there is no anticipated need for a shore protection device over the life of the proposed development. There are no recommendations necessary for avoidance or minimization of coastal hazards. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to contact our of fice. Respectfully Submitted, _______________________ GeoSoils, Inc. David W. Skelly, MS RCE #47857 *The term "certify" is used herein as defined in Division 3, Chapter 7, Article 3, § 6735.5. of the California Business and Professions Code (2007).