4800 DOGWOOD DR 2022-02-28 - Laserfiche WebLink

• View Ridge Comm.Church Add. Roofs feasibility description: • 1. Full Dispersion per BMP T5.30 or Downspout Full Infiltration per BMP T5.10A. i. Full Dispersion is infeasible due to insufficient flow path length and lack of native forest vegetation retention. Full Infiltration is not recommended by the geotech due to proximity of on-site steep slopes and undocumented fill areas noted near the surface per geotech report. 2. Bioretention per Volume V, Chapter 7. • i. Infeasible per Geotech. Due to proximity of on-site steep slopes and previous undocumented fill, infiltration is not recommended; therefore, bioretention facilities are infeasible. 3. Downspout Dispersion Systems in accordance with BMP T5.10B. i. Downspout Dispersion is feasible due to sufficient flow path length(i.e. • more than 25' vegetated flow paths downstream of site). Note that slopes downstream of 25' veg flow path exceed 20% slope but do not contain a vertical elevation change of more than 10' in height. Slopes 25' from edge of dispersion trench designed with<15% slope. Dispersion trench designed at 10LF of trench for every 700 sf. of contributing roof area or 42.8LF of trench for approximately 3,000 sf. of contributing roof area. • 4. Perforated Stub-out Connections in accordance with BMP T5.10C. i. Due to the use of dispersion BMPs perforated stub-out connections are not required. Other Hard Surfaces feasibility description: • 1. Full Dispersion per BMP T5.30 i. As noted above, Full Dispersion is infeasible due to insufficient flow path length and lack of native forest vegetation retention. 2. Permeable Pavement per BMP T5.15 i. Due to proximity of on-site steep slopes and undocumented fill, infiltration is not recommended; therefore,permeable pavement is not • recommended. 3. Biorention per Volume V, Chapter 7. i. Due to proximity of on-site steep slopes and undocumented fill, infiltration is not recommended; therefore,bioretention facilities are infeasible. i 4. Sheet Flow Dispersion in accordance with BMP T5.12 or BMP T5.11. i. Runoff from new parking areas, along with a small portion of existing asphalt runoff traveling across new asphalt area,has been designed to sheet flow into adjacent vegetated areas downstream of new parking areas. Vegetated flow paths have been designed at 30' in length based on a max • contributing asphalt flow path length of 60'. Note that top of downstream steep slope area is approximately 45' to 50' downstream of edge of parking area. Minimum Requirement # 6: Runoff Treatment Due to the site proposing less than 5,000 sf. of new/replaced pollution generating hard • surfaces, conversion of less than 3A acres native vegetation to lawn, and conversion of less than 2.5 acres native vegetation to pasture,runoff treatment is not required. • WESTERN ENGINEERS,INC. 12 PROJECT:17-1619-A