10105 1ST DR SE 2021-12-14 - Laserfiche WebLink

AE CONSTRUCTION SFR 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 a lack of native vegetation. The site consists almost entirely of residential lawn areas, which does not allow for the retention of 65% of the site in a forested or native condition. ii. Full Infiltration is infeasible due to less than 36" depth to the restrictive layer in most cases. The lack of adequate soil depth does not allow the required minimum separation of 1' between the bottom of an infiltration facility and the top of the restrictive layer. 2. Bioretention per Volume V, Chapter T i. Bioretention is infeasible due to less than 36" depth to the restrictive layer. The lack of adequate soil depth does not allow the required minimum separation of l' between the bottom of a bioretention facility and the top of the restrictive layer. 3. Downspout Dispersion Systems in accordance with BMP T5.1 OB. i. Downspout Dispersion is feasible and will be implemented for all new roof areas. The site contains adequate area for 25' vegetated flow path for a dispersion trench. See the following section of BMP sizing. 4. Perforated Stub -out Connections in accordance with BMP T5.10C. i. N/A, previous BMP selected for all roof areas. Other Hard Surfaces feasibility description: 1. Full Dispersion per BMP T5.30 i. As noted above, Full Dispersion is infeasible due to a lack of native vegetation. The site consists almost entirely of residential lawn areas, which does not allow for the retention of 65% of the site in a forested or native condition. 2. Permeable Pavement per BMP T5.15 i. Permeable Pavement is infeasible due to less than 36" depth to the restrictive layer. The lack of adequate soil depth does not allow the required minimum separation of 1' between the bottom of a permeable pavement facility and the top of the restrictive layer. 3. Biorention per Volume V, Chapter 7. i. Bioretention is infeasible due to less than 36" depth to the restrictive layer. The lack of adequate soil depth does not allow the required minimum separation of 1' between the bottom of a bioretention facility and the top of the restrictive layer. 4. Sheet Flow Dispersion in accordance with BMP T5.12 or BMP T5.11. i. Sheet Flow Dispersion is feasible and will be implemented for all new driveway areas. The site contains adequate are for the required flow path lengths for BMP T5.11 concentrated flow dispersion. WESTERN ENGINEERS, INC. 16 PROJECT: 19-1821-A