Friday, August 5, 2016

Taking aim at stormwater pollution

At eight locations in Ventura County along US Highway 101, Austin Vault Sand Filters will be built, similar to
this one (at right) shown under construction along I-5 near Carmenita Road in Los Angeles County.

A completed Austin Vault Sand Filter in the Caltrans I-5 project at Alondra Boulevard in Los Angeles County.

Some of Caltrans’ latest efforts for stormwater pollution control are beginning to take shape in Ventura County along US Highway 101 and State Route 33.

Using recognized Best Management Practices (BMPs) for curtailing pollution in runoff from the state highway system, Caltrans District 7 is working at more than two dozen locations in Ventura County, from the city of Ventura on the west to Thousand Oaks on the east, including the cities of Camarillo and Oxnard.

The projects aim to achieve measurable reductions in trash, heavy metals and other pollutants affecting the Ventura River Watershed in western Ventura County and the Calleguas Creek Watershed in the eastern area of the county.

At eight locations along US Highway 101, Caltrans is constructing Austin Vault Sand Filters, which remove fine sediment and particulate pollutants through two concrete-lined chambers – the first is a sedimentation vault, and the second is a filtering vault. The sand filter limits runoff material including oil and grease, heavy metals and bacteria.

Also along US 101, Caltrans plans to create 21 vegetated areas for pollution control, known as biofiltration strips and biofiltration swales.

Biofiltration strips use grasses, ground cover and other plantings to capture and biologically degrade pollutants carried by stormwater. They also reduce the velocity and volume of stormwater runoff.

Biofiltration swales receive and direct the flow of stormwater while helping to degrade pollutants in the runoff.

Meanwhile, at seven locations along State Route 33 in and near Ventura, Caltrans is working to install Gross Solids Removal Devices and drainage modifications. GSRDs capture trash and larger debris in stormwater.

All of these facilities are being constructed under two Caltrans projects that have a total dollar value of $9.6 million, from state and federal funds.

Beginning in June, contractors placed concrete barriers at work zones along Highway 33 and US 101, prompting inquiries from local news reporters and members of the public alike.

The temporary barriers are expected to remain in place approximately until the end of 2016. Construction of the two projects is estimated to be completed in spring or summer 2017.