MIL-HDBK-1138
Table 8
Winter Problems with Clarifiers
Problem
Solution
Scum line freezes
Flush out with hot water. Use
sewer bag to free blockages.
Install automatic flushing
mechanism.
Scum trough freezes
Cover exterior trough.
Break ice into pieces and
remove by hand.
Install automatic flushing
mechanism.
Scum freezes on beaching plate
Flush off with hot water.
Discontinue scum removal in
winter.
Shovel and hose down by hand.
If adjustable, decrease
exposed plate area.
Ice on beaching plate hangs up
Remove skimmer during winter.
collector arm and damages
Remove ice by hand.
mechanism
Scum freezes on outside ring
Cover clarifier.
of peripheral feed clarifier
Scum solidifies, won't flow
Use warm water to flush.
Scum freezes at center feed
Install a warm water sprayer
to keep scum moving toward
skimmer.
Surface icing
Remove secondary arms to
prevent damage.
Keep clarifiers on 24 hours/
day.
Remove thick ice with long-
armed backhoe.
Shorten detention times.
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