07/30/2003 ZONING BOARD OF APPEALS Decisions

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Meetinghouse Hill Plan Review Page two . Sheet 3 of 6 The site grading on this sheet is similar to the former concept except for the southerly half of Lot 1. This area is now reserved as part of the overall site drainage and provides an uninterrupted path for storm water flow. The drainage system consists of deep sump catch basins, an in-line sediment trap, a sediment forebay, detention area and a release point with a leaching pit for infiltration. The bottom of the detention area is set at elevation 100 (plan datum). The high ground water was determined by soil evaluation to be at 93.6 plan datum. A report from soil scientist Peter Fletcher suggests that mottling in the soil profile establishes the depth below the ground surface where the high ground water might be anticipated. This sheet of plans indicates where and how the surface water would be collected from the proposed construction. The storm drainage design incorporates several features that are typical to systems that are recommended in the Department of Environmental Protection Storm Water Management Policy. Some of the design details are similar to those found in the Urban Storm Water Handbook that is used along with TR-20 and TR-55, both of which are technical documents and provide procedures for determining storm water flows. Sheet 4 of 6 The boxed note in the middle of the sheet indicates that the final design of the storm water system at Meetinghouse Road will be done after soil testing has been completed. It is recommended that this be done as soon as possible since the results may affect the size of the drainage easement that should be shown on the plan to be recorded in the Barnstable Registry of Deeds. The catch basin detail for CB-1 and CB-2 should be revised as follows: 1. Extend the gas/oil separator so that the bottom is 12" below the flow line • of the horizontal discharge pipe, 2. The sump in the structure can be reduced to 4' below the invert if desired. Sheet 5 of 6 The detail for the Extended Detention Basin Spillway should be revised as follows: 1. Label the amount of stone around the leaching pit structure, 2. Identify the bottom elevation of the proposed leaching pit, 3. Label the 1/8" to ''/" peastone cover It is recommended that a detailed cross-section of the forebay and detention basin be included on the plans. Haybales should be provided around the leaching pit grate during the construction phase to prevent siltation of the stone. Sheet 6 of 6 The Mashpee Water District should review the size and location of the proposed water line and the Mashpee Fire/Rescue Department should review the location of the proposed fire hydrants. Drainage Calculations A site visit was made along with the applicant's engineer to review the drainage patterns and general physical features of the site. This on-site inspection was made at the end of June. Two off site features impact the site; 1. The access road and crossing culverts on the south of the subject property that leads to the new water tank, 2. The water tank site and the general storm drainage patterns that evolve • from that location. The site itself was dry at the time of the site visit. No standing water was observed in the section of the site that was previously excavated out and is now an abandoned pit.