2026 05 Storm Water Management Report rcd 5 6 2026

Point of Analysis #3 Study Area 3: This area consists of 0.103 acres which includes sidewalks and lawn area that sheet flows to the northeast corner of the site and is not collected by the onsite stormwater conveyance system. Existing Conditions Input Summary Table Drainage Area Name Drainage Area Time of Curve Number (acres) Concentration (CN) (minutes) EDA 3 - Impervious 0.019 Ac 8.1 98 EDA 3 - Pervious 0.084 Ac 8.6 61 Existing Conditions Flow Summary Table Drainage Current Adjusted Rainfall Projected Adjusted Rainfall Area Conditions Conditions Name Q2 (CFS) Q10 (CFS) Q100 (CFS) Q2 (CFS) Q10 (CFS) Q100 (CFS) POI #3 0.09 0.22 0.53 0.13 0.30 0.76 4. Proposed Drainage Conditions The proposed development has been designed to generally maintain similar drainage patterns as the existing condition. As shown on the Proposed Drainage Area Map in the Appendix of this report, the majority of the stormwater runoff for the proposed development will be captured by the proposed inlets and yard drains and conveyed to the same offsite region as in the existing condition. Moreover, the proposed development will incorporate a small bio-retention basin to the west of the proposed building along the site frontage, and an underground pipe storage detention basin to the north of the proposed building along the northern property line for stormwater management. The basins are designed to detain stormwater runoff generated by the development to meet the stormwater management requirements. The proposed site conditions have been evaluated using the following drainage sub-watershed areas as depicted on the Proposed Drainage Area Map included in the Appendix of this report. Point of Analysis #1 To On-Site Conveyance System: This area consists of 0.275 acres and includes motor vehicle surfaces, impervious and grass areas throughout the site. Under proposed conditions runoff generated by this area sheet flows into the proposed storm conveyance system and

s and includes motor vehicle surfaces, impervious and grass areas throughout the site. Under proposed conditions runoff generated by this area sheet flows into the proposed storm conveyance system and discharges in the same location under existing conditions. Study Area Roof: This area consists of the entire 0.142 acres of roof area for the proposed building. Under proposed conditions the runoff generated by this area flows into a roof leader manifold and is discharged into the proposed 48” HDPE Underground Detention Basin to the north of the proposed building. The underground pipe storage provides detention for the runoff, slowing the rate of flow to the POI #1, the ultimate discharge point. Mavis Tire Supply, LLC July 2025 DEC# 1956-24-04187 4 Last revised May 2026