This article from last Sunday’s Bee describes Sacramento’s increased drainage storage and how it helped during the recent floods, but still notes that the improvements have not helped stop the type of sewage backup that occurred in downtown Sacramento in 2004 and can again. Yuk!!
Excerpts below:
“The heavy rains of last weekend caused sewer pipes to back up, streets to flood, and an unexpected flow of partially treated wastewater into the Sacramento River.
“But however wet and messy it was, the men and women who manage the Sacramento area's sewer and storm drainage systems were grateful things weren't worse.
“That's because the various underground systems are designed to handle up to a 10-year storm event, while the series of storms that dumped five inches or more on the region last weekend were considered a 25-to 50-year event, depending on the location, according to Michael Peterson, principal civil engineer with the Sacramento County Department of Water Resources.
“A 10-year event has a 10 percent chance of happening every year, while a much larger 50-year event has a one in 50 chance of occurring in a given year.
…. “During the past 10 years, the city has spent about $107 million to upgrade the system, which had become notorious for backups during storms. The fixes included vastly increasing the capacity of two large pumping stations, expanding a city treatment plant's capacity to disinfect wastewater and discharge directly into the river during heavy rain events, and installing below-ground storage basins for times of excess rain, Sacramento Utilities Director Gary Reents said.
“During last weekend's storms, the system was effective: The city had just two spots where a small amount of sewage backed up into streets.
“Reents said that if Sacramento received the kind of record-setting rain it got in September 2004, even the latest improvements to the city's sewer and drainage systems could not accommodate the quick rush of water. In the 2004 event, two inches of rain fell in an hour in the downtown area, causing sewage backups that infuriated residents.
"Even with the improvements, there will be storms that are larger than we can accommodate," Reents said.”
