SANTA ROSA, Calif. (KGO) -- A sinkhole 7-feet deep and 4-feet wide was recently discovered at the foot of Newberry Court in Santa Rosa's Fountaingrove neighborhood.
City officials say it was caused by 300-feet of plastic storm drain pipe, which melted during the firestorm last month.
"The pipes caught fire and were destroyed," said Santa Rosa Water Director Bennett Horenstein.
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The sinkhole has been filled and replaced with new pipes, but the problem is now larger than first thought.
"So far we've discovered eight sites where pipe has been lost and 20 suspected areas under investigation," said Horenstein.
RELATED: Residents find very little after returning to fire-ravaged Fountaingrove
The loss of drain pipe has greatly increased the threat of more sinkholes, mudslides, flooding and possible evacuations if future storms bring heavy rain.
"It's hard to tell people who just got back into their homes they need to be ready to leave again if things turn sour," said Santa Rosa Mayor Chris Coursey.
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On Sunday night, officials closed Cross Creek Road after a fire damaged pipe was discovered, which runs underneath the road. The fire department says the road could be compromised.
Santa Rosa city officials are monitoring the weather and telling residents in Fountaingrove to be ready to leave if necessary.
Click here for more stories about the North Bay fires.
Santa Rosa officials issue flood warning after North Bay fires melted storm drain pipes
NORTH BAY FIRES