535 VIEW RIDGE DR 2025-03-31 - Laserfiche WebLink

3. Bioretention BMPs (See Chapter D5 of this manual and Chapter 7, Volume V of the DOE Manual) that have a minimum horizontally projected surface area below the overflow which is at least 5% of the total surface area draining to it. Not feasible due to slope of site and soils. 4. Sheet Flow Dispersion in accordance with BMP T5.12: Sheet Flow Dispersion, or Concentrated Flow Dispersion in accordance with BMP T5.11: Proposed 24" -gravel dispersion berm for driveway drainage to veaetated strip having compost amended soils Minimum Requirement #6: Runoff Treatment: Design of the storm water treatment facilities is not required due to new/redeveloped pollution generating surfaces (4,215 SF) not exceeding the threshold of 5,000 SF of PGIS, stormwater treatment is not required. Note that the driveway surface area is to be sheet flow dispersed across a gravel berm to lawn area with compost amended soils. (See table below for breakdown of Impervious areas) Minimum Requirement #7: Flow Control:. Under the guidelines and specifications in Volume III of the 2019 DOE SWDM no flow control required. The roof area (3,487 SF)will be collected and tied into the ROW drainage system that is located along the west side of the site and connects to Olympic Blvd . Due to the project having low permeable soils, shallow water table as well as being under the stormwater mitigation thresholds of: • 10,000 SF of new or replaced impervious area on-site, (7,742 SF) • s% acre converted from natural vegetation to lawn and (0.378 Ac) • below the net increase in 100-year storm runoff being below 0.15 cfs for 15-minute time steps in the 100-year flow frequency from our threshold discharge area (0.06 CFS) No Flow Control required nor proposed. (See table below for breakdown of site surface areas). Minimum Requirement #8: Wetlands Protection: There are no streams anywhere near any portion of the site or immediately downstream of the development. The Project discharges to a roadside ditch before entering the culvert that discharges to Pigeon Creek No 2 therefore #8 does not apply to this project. Minimum Requirement#9: Operation and Maintenance: The Operation and Maintenance report is in appendix D of this report. PROJECT SITE AREA TABLE Project Area= 23,112 SF (Site) Impervious Areas= 3,487 SF(Roof) +4,215 SF(Dwy) +40 SF(walk) = 7,442 SF (33.5 %of Site) 3