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HomeMy WebLinkAbout20288483 269 Broadway New Mixed-Use Public Comment ForthePlanningBoard RE : Proposed 269 Broadway January 3, 2022 In reading the two Reviews provided by CHA on the project, we notice there are still several outstanding questions to be resolved from the CHA reviews and suggest another review is required. In addition, several issues should be addressed based upon the geotechnical report. 1. The developers have presented a Sept 5, 2019, report by Terracon for planning approval. However,that report was prepared for Roohan Realty and does not represent the building that is being proposed. The geotechnical report states: "As we understand it, the project entails construction of a new five-story mixed use building with basement level parking and plan dimensions of about 65 x 240 feet. Preliminary plans envision the first floor at an elevation of approximately 307 feet (about five feet above Broadway), with the basement level parking at about elevation 295 (orjust above Hamilton Street)." The building being proposed is six stories, not five. In addition,the proposed building has parking down to an elevation of 275 or twenty feet below what was assumed in the geotechnical report. This is a notable change to the proposed work required. The added depth greatly undermines both Broadway and Hamilton Streets and their sidewalks and buried utilities, as well as the bank building to the north. 2. The geotechnical report indicates the groundwater level is expected at an elevation of between 289 to 292. Thus, the lowest level of parking (Elevation 275) will be 14 to 17 feet below ground water level. However,the SEQR application stated the building needs no dewatering.This should require a reopening of the SEQR application to address the water issue. 3. The proposed building is being described as a zero-lot-line building. However, the geotechnical report requires a drainage system on the below-grade exterior walls. It states: "Subsurface Drainage for Below-Grade Walls Retaining structures should be provided with a foundation level drain which may consist of a nominal 4-inch diameter perforated PVC pipe embedded at the base of a minimum 12-inch wide column of clean crushed stone(e.g., no. 1 and no. 2 size aggregate or ASTM Blend 57 stone).The stone should be wrapped in a filter fabric(Mirafi 140N or equivalent)to inhibit siltation. Backfill soils behind the crushed stone drainage layer should consist of Structural Fill. The drain line should be sloped to provide positive gravity drainage to daylight, stormwater system, or to a sump pit and pump." The drainage system recommendation requires a minimum setback of 1 foot from the property line. In addition, there needs to be an allowance for construction access and future maintenance of the drainage system. 4. Even without knowledge of the proposed deep parking levels, the geotechnical report recommends pre-construction surveys and monitoring if piles are used. It states: "Site Preparation Site preparation should begin with clearing and stripping of asphalt, topsoil and surficial organic matter from the building pad. A pre-construction survey of adjoining properties should be completed to define pre-existing cracks or deflections within the adjacent structures if H pile foundations are selected. In addition, vibration monitoring at the site limits and at nearby structures should be performed to verify whether the pile driving contractor's means and methods are acceptable or require modification." If piles are used, the pre-construction survey and vibration monitoring should be made mandatory. The geotechnical report should be amended, and similar pre-construction surveying and monitoring be considered due to the deep excavations required. 5. The geotechnical report recommends "Geotechnical Observations and Testing" during construction. This was recommended even without knowledge of the proposed deep parking areas.The report should be updated, and the recommended observations and testing be made a mandatory condition. Summary: 1. CHA should complete its review of outstanding issues and the items listed below. 2. The geotechnical report was written without knowled�e of the proposed building. 3. The SEQR report incorrectly stated no dewatering was required and should be revisited. 4. The geotechnical report should be updated to address the actual proposed building: a. The actual proposed height. b. The proposed deep parking levels and their impact on the groundwater level, the adjacent building, Hamilton St. and Broadway, and the buried public utilities. c. The proposed building drawings and floor elevations should be provided to the geotechnical engineer to assist in the preparation of a revised report.