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No. 3—Closed Detention Systems (Tan ksNaults) <br /> Maintenance Defect Conditions When Maintenance is Needed Results Expected <br /> Component When Maintenance is <br /> Performed <br /> Storage Area Plugged Air Vents One-half of the cross section of a vent is Vents open and <br /> blocked at any point or the vent is damaged. functioning. <br /> Debris and Sediment Accumulated sediment depth exceeds 10% All sediment and <br /> of the diameter of the storage area for 1/2 debris removed from <br /> length of storage vault or any point depth storage area. <br /> exceeds 15%of diameter. <br /> (Example: 72-inch storage tank would <br /> require cleaning when sediment reaches <br /> depth of 7 inches for more than 1/2 length of <br /> tank.) <br /> Joints Between Any openings or voids allowing material to All joint between <br /> Tank/Pipe Section be transported into facility. tank/pipe sections <br /> (Will require engineering analysis to are sealed. <br /> determine structural stability). <br /> Tank Pipe Bent Out Any part of tank/pipe is bent out of shape Tank/pipe repaired or <br /> of Shape more than 10%of its design shape. (Review replaced to design. <br /> required by engineer to determine structural <br /> stability). <br /> Vault Structure Cracks wider than 1/2-inch and any Vault replaced or <br /> Includes Cracks in evidence of soil particles entering the repaired to design <br /> Wall, Bottom, structure through the cracks, or specifications and is <br /> Damage to Frame maintenance/inspection personnel structurally sound. <br /> and/or Top Slab determines that the vault is not structurally <br /> sound. <br /> Cracks wider than 1/2-inch at the joint of any No cracks more than <br /> inlet/outlet pipe or any evidence of soil 1/4-inch wide at the <br /> particles entering the vault through the walls. joint of the inlet/outlet <br /> pipe. <br /> Manhole Cover Not in Place Cover is missing or only partially in place. Manhole is closed. <br /> Any open manhole requires maintenance. <br /> Locking Mechanism Mechanism cannot be opened by one Mechanism opens <br /> Not Working maintenance person with proper tools. Bolts with proper tools. <br /> into frame have less than 1/2 inch of thread <br /> (may not apply to self-locking lids). <br /> Cover Difficult to One maintenance person cannot remove lid Cover can be <br /> Remove after applying normal lifting pressure. Intent removed and <br /> is to keep cover from sealing off access to reinstalled by one <br /> maintenance. maintenance person. <br /> Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, Ladder meets design <br /> misalignment, not securely attached to standards.Allows <br /> structure wall, rust, or cracks. maintenance person <br /> safe access. <br /> Catch Basins See"Catch Basins" See"Catch Basins" (No. 5). See"Catch Basins" <br /> (No. 5) (No. 5). <br /> Volume V—Runoff Treatment BMPs—December 2014 <br /> 4-36 <br />