6009 FLEMING ST 2021-06-09 - Laserfiche WebLink

• Popach Short Plat—2 Lots Refer to feasibility list below for appropriate BMP selection or infeasibility • description: Lawn and landscaped areas: • Post-Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V. • 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. Full Infiltration is infeasible • due to less than 36" depth permeable soils on site. 2. Bioretention per Volume V, Chapter 7. i. At or below grade bioretention facilities area infeasible due to less than 36" depth petiiieable soils on-site. Above grade bioretention planter boxes have been proposed for development for all new roof areas. • 3. Downspout Dispersion Systems in accordance with BMP T5.10B. i. N/A. Project designed with above grade bioretention planter boxes. 4. Perforated Stub-out Connections in accordance with BMP T5.10C. i. N/A. Project designed with above grade bioretention planter boxes. 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. 2. Permeable Pavement per BMP T5.15 i. Permeable paving proposed for all new driving surfaces. 3. Biorention per Volume V, Chapter 7. i. N/A. Permeable paving proposed for all new driving surfaces. 4. Sheet Flow Dispersion in accordance with BMP T5.12 or BMP T5.11. i. N/A. Permeable paving proposed for all new driving surfaces. Stormwater BMP design discussion: Due to lack of available drainage systems in the area, along with concerns of drainage impacts to a basement area located in the adjacent property to the north, the site has been designed to implement minimal infiltration type stormwater BMP's and concentrate them in the central and southerly portions of the site. This infiltration type BMP's include new permeable driving surfaces per BMP T5.15 located in the southern portion of the site along with above ground bio-retention planters located adjacent to future roof areas per BMP T5.14B and T7.30. Though the site in general doesn't contain at least 36"depth of soil to restrictive layers,minor infiltration type BMP's still appear feasible. Existing soils surrounding the new permeable driveway area are estimated to contairi approximately 24"-32" of permeable soils prior to reaching restrictive layers (i.e. glacial till). Note that this property lines on a small ridge/high point for the general WESTERN ENGINEERS,INC. 12 PROJECT:15-1463-A