Filtering Runoff

Thanks to a reader for passing along this interesting story that ran late last month in the Orange County Register.

Officials there are coping with the effects of urban runoff – a familiar story here in San Diego, where sewage-tainted runoff from Tijuana has closed some three miles of coastline, from the border north to Imperial Beach.

In Orange County, the city of Newport Beach is spending $300,000 to curb polluting runoff near the city’s harbor. Register reporter Jeff Overley says:

There’s a bright blue, cloudless sky, but on the side of Newport Boulevard, water is coming down in buckets.

It’s here, in a wedge of land the size of a football field, that water hosed onto walkways and thirsty lawns comes together, hits a storm drain and makes a beeline for Newport Harbor.

“It hasn’t rained in 150 days, but we’ve got 30,000 gallons of water washing down” every day, said John Kappeler, a Newport Beach water quality specialist.

If it were just the water, no problem. But every drop carries a laundry list of pesticides and fertilizers, grime that can feed bacterial growth once it hits the harbor.

So, at the behest of state environmental officials, the city is building a “bioswale,” a natural filtration system composed of sand and gravel that absorbs pollutants and filter debris.

We’ve written about a similar project that is being constructed in Tijuana. There, pervious pavers are replacing asphalt in one neighborhood. Pervious pavers – unlike impervious asphalt – allow storm runoff to soak in the ground and can help replenish groundwater aquifers. Some background on that is here.

– ROB DAVIS