Unit Process Screening
Screening Area Equipment Five (5) Influent Sluice Gates; Five (5) Mechanical Bar Screens; One (1) Collecting Belt Conveyor; One (1) Reversing Belt Conveyor; Ten (10) 1–CY Self–Dumping Containers; Two (2) 30–CY Roll–off Containers; Influent level and flow measuring devices; Gas Detection Equipment; Four (4) Influent Channel Sluice Gates
Before Wet Weather Event 1.
Dry weather flows (infiltration and inflow) are not expected to be great enough to initiate the operation of the screens when they are in the automatic operating sequence. However, the removal of solids and debris that may build up on the screens as a result of dry weather flow may be necessary. Therefore, a control strategy shall be provided to allow the periodic EXERCISE operation of the screens during dry weather.
2.
This feature will ensure that the mechanical bar screens remain well lubricated and do not "freeze up" after extended periods of dry weather and inactivity. The control strategy for the bar screens shall initiate the EXERCISE routine based on the "elapsed off-timer." The "elapsed off–timer" will start whenever a bar screen is in the automatic operation sequence and the water surface elevation in the Influent Channel is insufficient to initiate operation of the screens.
3.
The "elapsed off–timer" will start the bar screens at a set interval and run them for a set duration. The time interval shall be soft-programmed and therefore be operator selectable. The time interval and run duration will be set based on operating experience and judgment. The "elapsed off–timer" shall reset to zero when a bar screen starts. When set up in this fashion, the screen shall not operate unnecessarily. The EXERCISE feature will operate in either the "TIMER" or "CONTINUOUS" sequence of the automatic operation setting. The exercise program will automatically start cross conveyor 1812–00 which will start
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