05/22/2019 ZONING BOARD OF APPEALS ZBA Decision

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Re: Habitat for Humanity 341 Great Neck Road North Page three 9. Driveway width should be reviewed by Mashpee Fire and Rescue to be suitable for their needs. Curb radius should be noted as 20 ft. 10.The stormwater portion of the project consists of a single catch basin inlet, connecting pipe, a grass swale and a stand-alone leaching catch basin. The following comments relate to the system as a whole: a. A check of the information found on line for a Shorey DB-9 curb inlet suggests it is a structure commonly used for septic systems. It is not H-20 designed. A catalog cut is necessary to show that it is something other than this. b. A standard catch basin, however, is preferable to a shallow curb inlet in order to trap sediment from the driveway surface. The driveway grade is approximately 6% meaning that it would most likely need sanding during winter months. The sand will be carried to the catch basin and in a short period of time will fill the shallow inlet. Sediment should not be allowed to travel out of the curb inlet toward the leaching pit. Both structures should be H-20 design. Iron castings should also be H-20 design. c. Castings should be set in place with a ring of cement concrete 12" wide and 12" deep brought level to the top of the binder course of pavement to seal the casting to the structure. d. It is recommended that the standard catch basin be fitted with the 12- inch pipe directly into the leaching pit. The catch basin should have a 4-foot sump below the pipe and the pipe should be fitted inside the basin with either a tee or 90- degree elbow of the same size as the pipe to act as a gas/oil trap. If an elbow is used it should have a 2" diameter hole cut into the top surface as an anti-siphon device. Doing the drainage in this way eliminates the need for the rip rap stone. The leaching basin casting could be fitted with a solid cover instead of a grate. Pipe should be mortared in place inside and outside of structures. e. The plan shows that the electric service and water services run very close to the drop inlet. If the catch basin is located so that the edge of the casting is at the gutter line of the pavement, there will be room in the adjacent shoulder to run both utilities without interference with the structure. f. The water line will have to meet the requirements of the water department but in general is set with at least 5 feet of cover over the pipe. g. No storm drainage calculations were provided. It is assumed that the leaching pit capacity has been appropriately sized for the runoff from the proposed paved surfaces. Please feel free to contact me if you have any questions. Very truly yours, C4awees L, /eowl�� Charles L. Rowley, PE, PLS Cc Mashpee Zoning Board of Appeals Cl