2801 35TH AVE NE 2025-04-07 - Laserfiche WebLink

STORMWATER SITE PLAN 8/22/2023 SOUTHWEST STORAGE YARD 3 Flow from the site exits the site in two directions that do not connect within % miles, making for two threshold basins. Flow to the east crosses 351h at the intersection and discharges into a large ditch along the north side of 281h Place.A 24" ADS culvert conveys the flow past the existing access and a shed near the southeast corner of the site and the flow continues east approximately 40 foot before being joined by a 72" culvert to the south. From there the ditch opens into a large conveyance that directs flow to the north 1,500 feet to the 36" tide gate and the outlet to the Snohomish River system. The system has operated for years with no significant issues. With mitigations herein proposed,there should be no impact from the development. Flow to the west enters a low area between 351h and SR 529 that descends to the north following the highway that continues north to the dike (see the elevations of the LiDAR map). Upon reaching the dike,the flow enters a ditch line at the toe of the structure that conveys water to the east, southeast, and then south.This ditch ultimately connects into the large conveyance channel that runs north to the dike near the northeast corner of the adjacent Mina Properties storage site. It is at this point that the flow joins with the eastern drainage path. MR 2: SWPPP NARRATIVE As the site has less than 1 acre of disturbance, so a DOE Construction Permit will not be required. A SWPPP based on the Department of Ecology template and is provided under separate cover. MR 3: WATER POLLUTION SOURCE CONTROL Permanent Source Control will be as follows: • S407: BMPs for Dust Control at Disturbed Land Areas and Unpaved Roadways and Parking lots; • S454: Preventative Maintenance; • S455: Spill Control; • S456: Employee Training.; • S457: Inspections; • S458: Record Keeping; • S417: Maintenance of Stormwater&Treatment Systems; • S411: Landscaping and Lawn/Vegetation Management; • S450: Irrigation • S412 Loading and Unloading Areas for Liquid or Solid Material • S442: Labeling Storm Drain Inlets on your property. At present, no structural BMP's are proposed. Additional controls might be required through a Department of Ecology Industrial Permit. MR 4: PRESERVATION OF NATURAL DRAINAGE The natural drainage system has been amended in times past to provide for flood control. Diking District#5 has control of the local area and maintains a dike to the north and east of the site.The surrounding ditches provide access east and P:\Work\Projects\2021\21-162 Sea Con\CE\DOCS\STORMWATER SITE PLAN.SMALL.docx