Soil Movement and Erosion Control Plandocx rcd 5 7 2026

Part D: Roof Leader Plan and Discharge (Comments 5.5 and 5.7) Existing roof drainage system The existing dwelling is served by an underground roof drain system constructed of approximately 3" PVC pipe. The system collects roof runoff from the existing downspouts and conveys it underground along the southeast side of the house (along the property boundary between 15 Alan and 13 Alan), running approximately the full 120' length of the property to a discharge point at the curb in the public right-of-way at the front of the property. (The 120' length includes approximately 5'–6' of municipally-owned sidewalk and grass strip between the front property line and the street.) The system has functioned without backup, surfacing, or basement infiltration throughout the current ownership of the property. The existing system was not installed under permit in the current owner's tenure and as-built drawings are not available. Pipe size, depth, slope, and exact alignment have not been field-verified beyond what is visible at the downspout connections and the curb discharge. The system has performed reliably for many years, which is the basis for the Applicant's intent to tie the new rear leader into the existing line. Proposed roof leaders for new garage addition The proposed addition will have two roof leaders, one at the front (south) and one at the rear (north) of the new structure, in the same configuration and locations as the existing leaders on the existing garage. Rear (north) roof leader: The new downspout will tie into the existing underground 3" PVC roof drain system at grade via a standard downspout-to-pipe adapter, matching the existing detail. The roof area added by the new structure is modest relative to the total existing roof area served by the system, and the existing 3" PVC main is expected to have adequate capacity to accept the additional flow. If, during construction, the existing system is determined to be inadequate or in poor condition, a separate dedicated 3" PVC line will be installed parallel to the existing line. Final discharge in either case will be at the existing curb outlet at the street. Front (south) roof leader: The new downspout will be installed in the same location and connected in the same manner as the existing rear roof leader on the existing garage. Discharge will be at grade onto the existing asphalt driveway via a splash

l be installed in the same location and connected in the same manner as the existing rear roof leader on the existing garage. Discharge will be at grade onto the existing asphalt driveway via a splash block, matching the existing condition. The driveway falls generally toward the lawn to the east and south toward the curb at the street. Sheet flow from the rear leader follows this existing drainage pattern, with the majority of the discharge infiltrating into the adjoining lawn and the remainder continuing south along the driveway to the curb. No underground piping is proposed for the front leader. Effect on adjoining property owners (Comment 5.7) The rear leader discharges to the public right-of-way via the existing curb outlet. This is the same point of discharge currently used by the dwelling and represents no new or relocated point of discharge. There is no flow path from the front leader toward any adjoining property. The front leader discharges at grade onto the existing asphalt driveway in the same location and manner as the existing rear leader on the existing garage. The driveway falls toward the lawn