1502 SE EVERETT MALL WAY FLOOR AND DECOR 2019-06-24

Everett Floor& Decor Storm Drainage Report Everett,Washington Section 6 - On-Site Stormwater Management Site Areas The proposed work involved a combination of pavement replacement, new pavement, removal of existing pavement for installation of landscaped islands, and overlay &grind/overlay of existing pavement. Stormwater requirements in the SWMMWW are based on the total amount of new and replaced impervious areas, which exclude those areas of overlay &grind/overlay. The site areas are provided in Table 3 below. Table 3 Impervious Areas Activity Description Area (SF) New/Replaced Concrete Pavement 4,128 New Asphalt Pavement 821 Grind/Overlay (Non-Disturbed) 6,282 Landscaped Area 890 Total Pervious + Non-Disturbed Area 7,172 Total New + Replaced Impervious Area 4,949 Best Management Practices List#1 BMP Evaluation Lawn and Landscaped Areas j1. Post-Construction Soil Quality and Depth shall be provided in accordance with BMP T5.13 "Post-Construction Soil Quality and Depth"for all new landscaped islands. Roofs 1. No roof areas are included in the project. BMPs are not required to be evaluated. Other Hard Surfaces 1. Full Dispersion a. The pr posed project is located in an existing parking lot. No pervious flow path exists t provide full dispen meeting the requttiremof SWMMWW BMP T5.30.JfJfM4&)7aSth9J?fi 81� /ids SlOrc V . 13, - 2. Permeable Pavement/Rain Gardens/Bioretention 14-- is i & a. Per the information obtained from the NRCS Web Soil Survey, on-site soils do not appear to be appropriate for BMPs utilizing infiltration to manage stormwater.The capacity of the most limiting soil layer is classified as "very low to moderately low",which corresponds to infiltration rates between 0.00 and 0.06 inches per hour,which are less than the 0.30 inches per hour identified in SWMMWW as the minimum rate required to support these BMPs. Furthermore, the water table is identified as being between 18 and 36 inches deep, which do PACLAND Project#10-635-004