03/10/2004 ZONING BOARD OF APPEALS Minutes

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• Grading has been revised in this area: c,. Provide culverts beneath driveways. The applicant was planning on providing culverts beneath driveways to connect swale sections. These culverts are now shown on the Plan, where open section drainage is proposed. d. How will swale grades be reconciled with the grades of the intersecting pavements? See Plans. e. The parking area located within Lot 9 has uncontrolled sheet drainage at a grade of 10%. The grading of this parking area has been revised to direct the runoff to either a grass drainage Swale equipped with rip rap stabilization to the south or a paved gutter to the north. Both conveyance facilities discharge to the grass channel that is located adjacent to Lettie Lane, which has a slope of less than 3% and eventually discharges to the bioretention area located within the entrance round-about. f. Much of the surface runoff from the commercial parking will not be intercepted and controlled by swales. Grading suggests it will be carried out the entrance to Route 130: There should be catchbasins.at the entrance at Route 130 to collect runoff from entering the public way. All surface runofffrom the commercial parking lots will be collected and either infiltrated or discharged in a controlled manner, as to ensure public safety. Ruinoffwill be collected by paved gutters and discharged to bioretention areas through-rip rapped stabilized inflow channels. Due to the Site being broken up into small drainage areas, bioretention facilities are sized to store and infiltratestormsup to the 25-year, 24-hour storm during f-ozen ground conditions. EXtreme storm events(i.e. 100-year storm) during non-frozen conditions will be controlled by emergency overflow structures, which discharge at a rate below the pre-development conditions. We have included two additional deep-sunup catchbasins,at the entrance to Route 130, to collect any runoff not collected by the bioretention facility proposed in the entrance cul-de-sac. These additional catchbasins will direct runoff to a proposed recharge basin, as shown on the Plans. g'. Two bioretention areas adjacent to the wastewater subsurface absorption areas (SAS). All bioretention areas rnointaina 10-foot setback to the SAS systems, in accordance with Title 5. One bioretention area has-been eliminated. Also, the bioretention system close to the SAS systems is equipped with an underdrain that will collect runoff and direct it to large infiltration basin or the southern portion of Site. h. Spot grades in commercial parking lots. Response Letter - - Horsley Witten Group _ -' Main Street Village(Lettie Lane)Mashpee,MA : 6 March,5,2004 -- Horsley WiTten Group F