2016-01-11-CONCOM-min - Laserfiche WebLink

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Mrs. Dohan recused herself from this hearing. Motion to close the hearing made by Mr. Wolk and seconded by Mr. Beuttell. Vote: 4-0 in favor. Motion to issue the Order of Conditions made by Mr. Wolk and seconded by Mr. Beuttell. Vote: 4-0 in favor. New Hearings 6:53pm DEP File No. 201-1013, BL 970 NOI, 99 Hancock Street, Diamond School Owner/Applicant: Town of Lexington, Facilities Department Project: School addition and associated site appurtenances Ken DiNisco- Architect, Fred King- Wetlands Scientist Documents: NOI package 12/22/2015, Building Plans 12/22/2015, Stormwater Management 12/22/2015, Presentation 1/11/2016, Engineering report 1/11/2016 Mr. DiNisco began by giving a small overview of the project at the Diamond School. He explained that an alternatives analysis was done and was available in the packets to be reviewed. HE told the commissioners that work was expected to begin in May 2016 with an initial finish date of August 2017. Mr. King gave an overview of the resource areas in the region. He told the commission that there are many wetlands surrounding the project on almost all sides and that several pieces of the project come close to the wetland. The first is the proposed driveway turn around. The second is the redesign of the parking facility. The third feature is the extension of the driveway to connect both parking lots. The driveway in that area would be extended 22 feet and would run alongside the existing fence. Additionally, along Sedge Road parking spots will be added along with a wider sidewalk for walking and biking. This portion of the project will actually be pulled away from the wetland. Mr. King went on to explain the existing stormwater management system, much of which was installed in the last renovation in 2000 and will be repurposed for this project. The new proposed system would include a bio-retention system for pretreatment to meet the 44% TSS removal as well as handle infiltration and peak flow. The new driveway area will have new deep sump catch basins and a deep sump manhole. There will also be one more feature used here that will be determined. The new road area will mostly rely on the existing system. A sub drain will go between the sidewalk and walkway. The catch basin will also be relocated to keep the wetland from overflowing into the road. Overall, the Sedge road system should match the existing peak flows and there would be a slight increase in volumes, but well within the capacity of the drainage system. The overflow system to the wetland will see similar results.