7800 EVERGREEN WAY HYUNDAI Drainage Report 2025-04-28

Table V-A.2: Maintenance Standards - Infiltration (continued) Maintenance Component Defect Conditions When Maintenance Is Needed Results Expected When Maintenance Is Per- formed (A percolation test pit or test of facility indicates facility is only working at 90%of its designed capabilities. Test every 2 to 5 years. If two inches or more sediment is present, remove). Filter Bags(if applicable) Filled with Sediment and Sediment and debris fill bagmore than 1/2 full. Filter bagis replaced or system is redesigned. gpp ) Debris p y g Rock Filters Sediment and Debris By visual inspection, little or no water flows through filter during heavy rain storms. Gravel in rock filter is replaced. Side Slopes of Pond Erosion See Table V-A.1: Maintenance Standards-Detention Ponds See Table V A.1: Maintenance Standards Deten tion Ponds Tree Growth See Table V-A.1: Maintenance Standards-Detention Ponds See Table V A.1: Maintenance Standards Deten Emergency Overflow Spillway tion Ponds and Berms over 4 feet in height. See Table V-A.1: Maintenance Standards-Deten- Piping See Table V-A.1: Maintenance Standards-Detention Ponds tion Ponds Rock Missing See Table V-A.1: Maintenance Standards-Detention Ponds See Table V A.1: Maintenance Standards Deten tion Ponds Emergency Overflow Spillway Erosion See Table V-A.1: Maintenance Standards-Detention Ponds See Table V A.1: Maintenance Standards Deten tion Ponds Facility or sump filled Pre-settling Ponds and Vaults with Sediment and/or 6"or designed sediment trap depth of sediment. Sediment is removed. debris Table V-A.3: Maintenance Standards - Closed Detention Systems (Tanks/Vaults) Maintenance Per- Defect Conditions When Maintenance is Needed Results Expected When Maintenance is Component formed Plugged Air Vents One-half of the cross section of a vent is blocked at any point or the vent is damaged. Vents open and functioning. Accumulated sediment depth exceeds 10%of the diameter of the storage area for 1/2 length of storage vault or any point depth exceeds 15%of diameter. All sediment and debris removed from storage Debris and Sediment (Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than 1/2 length of area. Storage Area tank.) Any openings or voids allowing material to be transported into facility. Joints Between Tank/Pipe Section All joint between tank/pipe sections are sealed. (Will require engineering analysis to determine structural stability). Tank Pipe Bent Out of Shape Any part of tank/pipe is bent out of shape more than 10%of its design shape. (Review required by engineer to determine Tank/pipe repaired or replaced to design. structural stability). Cracks wider than 1/2-inch and any evidence of soil particles entering the structure through the cracks, or main- Vault replaced or repaired to design spe- Vault Structure Includes Cracks in Wall, Bottom, tenance/inspection personnel determines that the vault is not structurally sound. cifications and is structurally sound. Damage to Frame and/or Top Slab Cracks wider than 1/2-inch at the joint of any inlet/outlet pipe or any evidence of soil particles entering the vault through the No cracks more than 1/4-inch wide at the joint of walls. the inlet/outlet pipe. 2019 Stormwater Management Manual for Western Washington Volume V-Appendix A-Page 1007