Monday, November 26, 2012

Ready for the Rain

The rainy season is here! While we welcome the rain we also have to prepare for it.  Why? If left unchecked, rain water will travel through constructions sites (that uncover large amounts of dirt for their work) and pickup dirt and small rocks and anything else that is on the ground surface along the way.  The runoff then goes into storm drains and flows into the local water system causing harm to the Bay.

At the New Irvington Tunnel Project, the San Francisco Public Utilities Commission uses a series of Best Management Practices (BMPs) to minimize the effects of storm water runoff.  Our prevention methods include:

Erosion Control: Planting vegetation is an effective way to stabilize the soil by reducing exposure to erosion.  Stabilization prevents soil particles from detaching and becoming transported in storm water runoff. 

 Erosion control measures in place at the Vargas Shaft

Earth Dikes & Drainage Swales:  Earth dikes are temporary berms of compacted soil and drainage swales with shallow slopped channels. These easily installed measures divert storm water runoff away from soil that is prone to erosion and into controlled areas.

This drainage swale channels storm water away from erosion sensitive areas

Sediment Basins: Control areas such as gravel basins trap and collect sediment from storm water runoff before it enters our local water systems.

A gravel basin at the Irvington Portal

The SFPUC and our contractor, Southland Tutor Perini Joint Venture, work together to make sure stormwater runoff does not make its way into the local water system.  As a team we keep a constant eye to ensure the appropriate measures are in place and are effective. 

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