1517 132ND ST SE 2024-12-09 - Laserfiche WebLink

Implemented BMPs Because the project triggers minimum requirement #1-5 the project must consider BMPs in List #1 of the SWMM to mitigate stormwater runoff from lawn and landscaped areas, roofs, and other hard surfaces. This project proposes to meet the LID performance standard by collecting and conveying stormwater to existing stormwater facilities offsite. Lawn and Landscaped Areas: 1. BMP T5.13: Post-Construction Soil and Depth Soil quality will be met onsite by amending all soils onsite and importing new soil. Roof Areas: 1. BMP T5.30: Full Dispersion There is no native vegetation onsite to make full dispersion possible. 2. BMP T5.10A: Downspout Full Infiltration As described in the geotechnical report in Appendix B, the soil does not have the capacity for any infiltration type systems. 3. BMP T5.14A: Rain Gardens &BMP T7.30: Bioretention Cells, Swales, and Planter Boxes As most of the site is already covered in pavement and will remain paved, there is no space onsite suitable for any of these BMPs. 4. BMP 5.10B: Downspout Dispersion System. The site does not have enough room for a dispersion flow path. 5. BMP T5.10C: Perforated Stub-out Connections. The design criteria for perforated stub-out connections cannot be met. An adequate amount of pipe will not fit with the minimum setbacks for this BMP. Other Hard Surface Areas: 1. BMP T5.30: Full Dispersion There is no native vegetation onsite to make full dispersion possible. 2. BMP T5.15: Permeable Pavements, BMP T5.14A: Rain Gardens, and BMP T7.30: Bioretention Cells, Swales, and Planter Boxes As most of the site is already covered in pavement and will remain paved, there is no space onsite suitable for any of these BMPs. 3. BMP T5.12: Sheet Flow Dispersion and BMPT5.11: Concentrated Flow Dispersion There is not enough room onsite for a dispersion flow path.