The create a new Section Flood Resilience Standards

22.80 FLOOD RESILIENCE STANDARDS 22.81 Statement of Purpose. The purpose of this Section is to promote building designs that are resilient to the impacts of flood events that are likely to become more frequent and intense due to the effects of climate change. These standards are informed by future projections, based on up-to-date scientific research, rather than historical occurrences of flooding.

These standards are intended to account for the differing needs of buildings and sites and provide flexibility to use different measures to promote resilience. They are also intended to work in tandem with environmental standards promulgated by the Department of Public Works (DPW). 22.82 Applicability. This Section shall apply to development subject to Section 22.20 Green Building Requirements, and to other development as set forth elsewhere in this Zoning Ordinance. 22.83 Flood Elevation Standards.

22.83.1 Promulgation. (a) The City Engineer shall promulgate, and shall revise from time to time, the projected elevations of future flood risk due to certain types and probabilities of flood events for every lot in the City of Cambridge. The resulting projected elevations are referred to herein as Long-Term Flood Elevations (“LTFEs”).

(b) LTFEs shall be determined for flood risk due to precipitation based on piped infrastructure using the City’s hydraulic model, and for flood risk due to sea level rise and storm surge based on climate modeling performed by or endorsed by the Commonwealth of Massachusetts’s agencies and determined by the City Engineer to represent the most reliable and up-to-date scientific analysis of future climate conditions.

Whenever promulgating new LTFEs, the City Engineer shall document the source data used to determine the LTFEs and shall provide an explanation of why such data was selected. (c) LTFEs shall be based on an approximately 50-year projection from the time of promulgation. For example, LTFEs promulgated in or around the year 2020 shall anticipate flood risks in or around the year 2070. The City Engineer shall identify the projected timeframe when promulgating LTFEs.

(d) LTFEs shall be represented in vertical feet relative to the Cambridge City Base (CCB) datum.

(e) LTFEs shall be presented in the form of data tables that provide the numerical LTFEs for each parcel identified on the Cambridge Assessing Map and may also be presented in the form of a physical or digital map (for example, the Cambridge “FloodViewer” or any successor map) illustrating the LTFEs for different probabilities of flood risk for different types of flooding (i.e., precipitation, sea level rise, and storm surge) across the City.

Such a map may be presented and/or illustrated in relation to ground elevation data collected by the City of Cambridge through light detection and ranging (LIDAR) or other technology; however, if a property owner provides a property survey performed by a licensed surveyor, such survey shall be considered more accurate than ground elevation data collected by the

Page 2 of 38 City of Cambridge. Property surveys shall not alter the LTFEs but may affect the relative difference between the LTFE and the Grade on a given parcel. (f) New or revised LTFEs shall be made available to the public for comment no less than 90 days prior to final promulgation. 22.83.2 Application in Zoning. (a) For the purpose of this Section, the following LTFE standards promulgated by the City Engineer as set forth above shall be applicable to development on a lot or development parcel: (1)The 1%-Probability Long-Term Flood Elevation standard, or “1%-LTFE standard,” shall refer to the projected elevation of floodwater that has a one percent annual chance of occurrence due to either sea level rise and storm surge or due to precipitation, whichever is higher. (2) The 10%-Probability Long-Term Flood Elevation standard, or “10%-LTFE standard,” shall refer to the projected elevation of floodwater that has a ten percent annual chance of occurrence due to either sea level rise and storm surge or due to precipitation, whichever is higher. (b) For the purpose of this Section, then current LTFE standards shall be applicable to a lot or development parcel beginning on the date of final promulgation. However, a development proposal that has already submitted a LTFE plan that has been approved in writing by DPW, in accordance with Section 22.85 below, shall not be subject to LTFE standards promulgated after the date of such written approval, provided that the proposal receives all necessary permits including but not limited to a building or special permit and proceeds thereafter continuously and expeditiously to completion. 22.84 Development Standards. 22.84.1 Protection. A Story Above Grade or portion thereof shall be considered protected from flooding to a specified LTFE standard if its finished floor is higher in elevation than the LTFE standard, or if its finished floor is lower than the LTFE standard, there are permanent or passively deployable barriers in place at the height of the LTFE standard adequate to fully prevent the entry of floodwater into the building’s interior. A Story Below Grade or any portion thereof shall be considered a finished floor protected from flooding to a specified LTFE standard if the LTFE standard is below the Grade adjoining the building, or if the LTFE standard is above the Grade adjoining the building, there are permanent or passively deployable barriers in place at the height of the LTFE standard adequate to fully prevent the entry of floodwater into the interior of the Story Below Grade. The following standards shall apply: (a) All occupiable spaces within the building, as defined in the State Building Code, shall be protected to the 10%-LTFE standard, except that small entryways, vestibules, or lobbies with a finished floor below the 10%-LTFE standard are allowed to not be protected if they contain stairs, ramps, or lifts that allow occupants to travel to portions of the building that are protected, and if they meet the standards for “Recovery” set forth in Section 22.84.2 below.