Nearly 50,000 Gallons of Raw Sewage Flood Redwood City. Is That A Lot?

There's 50,000 gallons more where that came from, kid...

​Stories about just shy of 50,000 gallons of raw sewage bubbling into half a dozen prim Redwood City homes and inundating the community's lagoon touched off a round of schadenfreude here in the city. There's just something that much funnier about your standard feces-and-urine-coming-back-up-the-toilet story when it occurs in a neat and well-run suburb alongside a man-made lagoon.

Two questions remained unanswered by coverage thus far, however. How big is this lagoon? And, is 50,000 gallons of raw sewage a lot? We contacted officials in Redwood City and a sewage expert. And we've got answers.

If you came home and found 50,000 gallons of sewage waiting for you -- it'd ruin your day. But how significant is it when it's dumped into a 140-acre lagoon system like Redwood City's? Still pretty big, according to Peter Petrovsky, an engineer and expert on sewage spills. "That's a lot of sewage no matter how you slice it," he says.

Yes, it's possible to estimate how much water there is in a 140-acre lagoon. But let's keep this simple. An acre is about the size of a pro football field. And 50,000 gallons, Petrovsky notes, is about the size of a large residential swimming pool. So imagine a pool full of untreated human waste -- and anything else locals deigned to flush down the toilet -- being dumped into a body of water the size of 140-odd football fields.

Ah, crap

​Malcolm Smith, a Redwood City spokesman, explained that the amount of sewage flushed into the lagoon was 10 times higher than initially estimated on Friday because, in part, the flushing lasted longer than people thought it would. Initially, city workers figured 300 gallons of sewage was seeping into the lagoon for half an hour. Now, it turns out, "the discharge continued beyond the initial expected stop time."

That's because the problem wasn't with a failed valve as initially diagnosed, but a ruptured pipe. And those take longer to fix -- especially when they're gushing five gallons of sewage every second.

Smith adds the city is weighing "options to improve lagoon water quality in an environmentally friendly manner." Petrovsky notes, however, that this amount of sewage will likely decompose on its own within the year -- and can be treated sooner, especially if it's concentrated in one section of the lagoon. Still, "the water probably wouldn't be safe to go into for a couple of months." So cancel that lagoon party, stat.

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