If you see a manhole cover jumping, move away quickly. This happens often during heavy rain or high drainage flow. Large amounts of water rushing into underground pipes push the air inside, changing pressure. The compressed air escapes toward lower pressure, causing the cover to bounce. If water volume is huge, covers in low areas may even spray water out. Most manhole covers are round because they stay securely in place, don’t need perfect alignment when replaced, and can’t fall through their o
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If you see a manhole cover jumping, move away quickly. This happens often during heavy rain or high drainage flow. Large amounts of water rushing into underground pipes push the air inside, changing pressure. The compressed air escapes toward lower pressure, causing the cover to bounce. If water volume is huge, covers in low areas may even spray water out. Most manhole covers are round because they stay securely in place, don’t need perfect alignment when replaced, and can’t fall through their o
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