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MEMORANDUM May 18, 2018 Review of Geotechnical Study Project No. 1-1089 Proposed Main Street Apartments Page 2 of 7 353 Main Street, Redwood City, California APPROACH TO REVIEW This memorandum addresses a preliminary and high-level overview of the geotechnical, hydrogeologic, and engineering geologic aspects of the project presented to the City and that are elements of the Appeal filed by Better Neighborhoods, Inc. ("BNI"). The documents reviewed include the Primary Selected References and Secondary Selected References set forth above. In general, the "MND" does not adequately address several matters that we have determined could result in significant environmental impacts from the Project if not adequately studied, addressed, and mitigated. This memorandum discusses those elements of the Project regarding geotechnical, hydrogeologic, and engineering geologic issues. As discussed in more detail below, several issues should be the subject of additional study as to (a) whether they create significant environmental impacts resulting from the Project and (b) whether feasible mitigation measures can be considered and implemented that would reduce the identified significant impacts to a status that would be a less than a significant level. ENGINEERING, GEOLOGIC, AND HYDROGEOLOGIC CONSIDERATIONS A preliminary list of primary concerns and considerations that should be given adequate study and evaluation for the Project is presented below: • Vibration from construction activities The Project is situated in close proximity to existing development. The proposed earthwork and construction of the foundation could involve equipment and methods that introduce significant ground vibration that may damage existing adjacent and nearby improvements. The significant vibration and noise of equipment operation could also create annoying or intolerable conditions that could be a significant impact on nearby residents and occupants during construction that would have to be mitigated. A detailed study of these factors that addresses the actual site conditions, characters of the surrounding properties, and the proposed construction equipment and methods should be performed — along with a monitoring and mitigation program implemented during the construction period as appropriate. • Special Setting —The Project is adjacent to Redwood Creek over approximately half of perimeter I Surface Water and Habitat Characterization and Protection — Runoff and BMP 1 Buffer It appears that the City assumed the Project is substantially surrounded by urban development. However, our review of the referenced materials and desktop observation of the site and the properties in its immediate vicinity shows a major creek adjacency, undeveloped properties and other nearby properties that may not fit within the definition of urban in -fill. The Project is not adequately isolated by urban development from the adjacent creek. The referenced geotechnical reports do not contain meaningful discussion of site elevations other than finish grade and current site elevations. Most importantly, the referenced 350 Fischer Ave. Front • Costa Mesa, CA 92626 • P: 714 668 5600 • www.G3SoilWorks.com