10617 ROSEWOOD AVE 2022-01-25 - Laserfiche WebLink

• KUKHOTSKIY DUPLEX 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 feasible in the south west portion of the site and will be used for approximately 457 square feet of the duplex roof area. Infiltration is not feasible in the remaining areas of the site due to inadequate soil • conditions as the depth to glacial till does not provide the minimum 36" needed and potential infiltration areas south of new driveway area already consisting of driveway dispersion BMP area. 2. Bioretention per Volume V, Chapter 7. i. Bioretention is feasible in the northwest portion of the site however, Full infiltration is proposed to be installed in that location. Therefore; • Bioretention cannot be used. 3. Downspout Dispersion Systems in accordance with BMP T5.10B. i. Downspout Dispersion is feasible, and 5 splash blocks will be implemented for approximately 3,238 square feet of the proposed roof area. The site contains adequate area for 50' vegetated flow path for all • splash blocks. See the following section of BMP sizing. 4. Perforated Stub-out Connections in accordance with BMP T5.10C. i. Not needed as roof area runoff already being conveyed to options above 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 not feasible due to the need to fill in areas for new driveways to meet grading/building height design needs. 3. Bioretention per Volume V, Chapter 7. i. Bioretention is infeasible due to less than 36" depth to the restrictive layer in the location directly downstream of the proposed driveway. 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. • WESTERN ENGINEERS,INC. 16 PROJECT:19-1825-A