Ask the PAC: The unseen impacts of the Highway 101 widening project in the North Bay

“The bridge design had one of the bridge footings in the location of the existing sewer force main,” said Brad Sherwood, assistant general manager of Sonoma Water.|

Ask the PAC

This weekly feature aims to get to the bottom of Petalumans’ burning questions and provide insight into vexing daily curiosities.

If you would like your question featured in Ask the PAC, simply email askpac@arguscourier.com

While Petaluma continues to be a thoroughfare for a network of water pipelines, it also serves as the treatment area for the Penngrove Sanitation Zone, which comprises roughly 546 single-family homes spanning 475 acres. According to Sonoma Water, collected sewage from the Penngrove Sanitation Zone is routed through the zone’s lift station to be treated at the city of Petaluma's Ellis Creek Water Recycling Facility on Cypress Drive, located off of Highway 116.

But one of the Penngrove area’s sewer force main falls in line with an area affected by a years-long Highway 101 expansion project, also known as the Marin-Sonoma Narrows project, which has left some residents wondering how the highway infrastructure and the water system are influencing or impacting each other.

Question: Is it true that the new Highway 101 overpass was raised to accommodate a county sewer connector that needed to be replaced?

Answer: Right now, work is in progress to revise the Highway 101 vertical alignment in order to raise the portion of the highway over Sonoma-Marin Area Rail Transit train tracks while maintaining standard clearance height above the railroad corridor. This is to accommodate standard stopping site distance and design speed. The project does require for the Penngrove Sanitation Zone’s 6-inch sewer force main to be relocated, said Brad Sherwood, assistant general manager of Sonoma Water.

“The bridge design had one of the bridge footings in the location of the existing sewer force main,” Sherwood said in a recent email. “The relocation of the force main was to accommodate the new bridge.”

Officials with Sonoma Water did not say service to the area would be affected by the main’s relocation. It is also unclear when the relocation would occur.

While the Marin-Sonoma Narrows project was divided into 13 phases, the replacement of the Petaluma Bridge falls under “MSN C2,” which also included the construction of northbound and southbound HOV lanes along Highway 101 through Petaluma, as well as sound walls around the affected area.

The project comes after Sonoma Water and Ghillotti Construction in 2020 relocated 600 feet of the Petaluma Aqueduct, which transports water to about 309,000 people in Petaluma and parts of Marin County.

Amelia Parreira is a staff writer for the Argus-Courier. She can be reached at amelia.parreira@arguscourier.com or 707-521-5208.

Ask the PAC

This weekly feature aims to get to the bottom of Petalumans’ burning questions and provide insight into vexing daily curiosities.

If you would like your question featured in Ask the PAC, simply email askpac@arguscourier.com

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