12-31-2022, 08:30 PM
This may be the most on topic thread for me in history. I've worked on and around San Francisquito, Matadero, Barron, and Adobe Creeks and the Palo Alto Flood Basin for 36 years now. First, I sincerely wish safety for life, limb, and property and hope the next week of rain on top of wet soils does not result in a repeat of history, although I'm afraid it might.
My PE stamp is on the report/workmap that became the FEMA flood hazard maps that cover Palo Alto, Mountain View, and Los Altos. It is also on the basis of design that became the Matadero and Barron Creek improvements of the late 1990s. The person living near Barron Creek might appreciate that with a series of planned diversions into Matadero Creek, Barron Creek should have 100-year flow capacity. So should Matadero Creek. I know every inch of those systems and have walked the creeks from Foothill Expressway under El Camino in the bypass and on into the flood basin. That leaves San Francisquito Creek.
Without getting into the political reasons it may never be "fixed" completely, San Francisquito remains a problem child. Today's flow provisionally peaked at roughly 4,300 cubic feet per second (cfs) at the USGS gage at Stanford (golf course). That is equivalent to a 10-year return period based on the available record. The Pope-Chaucer Bridge is the first capacity-limiting hydraulic bottleneck and as evidenced by reports of limited overflow today, San Francisquito Creek has about a 10-year capacity. At East Bayshore, water was on the new floodwalls, and it looks like the tide was up. It is of course poor form to say "I told you so" to the people who objected to those floodwalls during their public vetting. Our pump station that sits next to Yeaman Auto Body was cranking away, only needing one of its four large capacity pumps to keep up. This storm is also the first "shake down" for two large storm water pump stations we just finished near Coyote Point, so this has been a busy week. There are some control issues at one of them we need to button down on Tuesday. Fortunately the bat signal didn't go out today. Tomorrow should be a break in the precipitation.
By contrast, February 2-3, 1998 was the flood of record on San Francisquito Creek and essentially a 100-year flow as measured at the gage. Flows leave the alluvial/perched creek channel and flow through Menlo Park, Palo Alto, and East Palo Alto never to return. The most severe flooding in 1998 was south of Colorado Avenue where water is trapped against the Matadero Creek floodwalls. That risk remains.
Every possible solution under the sun has been proposed, but none have met the public, environmental, and financial approval to move forward. Kevin Murray at the SF Creek JPA works tirelessly to get something done, so I'm sure these are anxious days for him. He does have a plan that would improve hydraulics at the Chaucer Bridge and then the next bottlenecks on the system that would then control capacity. The downstream reach is ready to handle the extra flow and additional capacity was recently added at the 101 bridge. The JPA will do what they can, but my understanding is that 100-year protection will simply remain out of reach for a host of reasons.
Stay safe everyone and remember that California is shaped by floods as much as drought.
My PE stamp is on the report/workmap that became the FEMA flood hazard maps that cover Palo Alto, Mountain View, and Los Altos. It is also on the basis of design that became the Matadero and Barron Creek improvements of the late 1990s. The person living near Barron Creek might appreciate that with a series of planned diversions into Matadero Creek, Barron Creek should have 100-year flow capacity. So should Matadero Creek. I know every inch of those systems and have walked the creeks from Foothill Expressway under El Camino in the bypass and on into the flood basin. That leaves San Francisquito Creek.
Without getting into the political reasons it may never be "fixed" completely, San Francisquito remains a problem child. Today's flow provisionally peaked at roughly 4,300 cubic feet per second (cfs) at the USGS gage at Stanford (golf course). That is equivalent to a 10-year return period based on the available record. The Pope-Chaucer Bridge is the first capacity-limiting hydraulic bottleneck and as evidenced by reports of limited overflow today, San Francisquito Creek has about a 10-year capacity. At East Bayshore, water was on the new floodwalls, and it looks like the tide was up. It is of course poor form to say "I told you so" to the people who objected to those floodwalls during their public vetting. Our pump station that sits next to Yeaman Auto Body was cranking away, only needing one of its four large capacity pumps to keep up. This storm is also the first "shake down" for two large storm water pump stations we just finished near Coyote Point, so this has been a busy week. There are some control issues at one of them we need to button down on Tuesday. Fortunately the bat signal didn't go out today. Tomorrow should be a break in the precipitation.
By contrast, February 2-3, 1998 was the flood of record on San Francisquito Creek and essentially a 100-year flow as measured at the gage. Flows leave the alluvial/perched creek channel and flow through Menlo Park, Palo Alto, and East Palo Alto never to return. The most severe flooding in 1998 was south of Colorado Avenue where water is trapped against the Matadero Creek floodwalls. That risk remains.
Every possible solution under the sun has been proposed, but none have met the public, environmental, and financial approval to move forward. Kevin Murray at the SF Creek JPA works tirelessly to get something done, so I'm sure these are anxious days for him. He does have a plan that would improve hydraulics at the Chaucer Bridge and then the next bottlenecks on the system that would then control capacity. The downstream reach is ready to handle the extra flow and additional capacity was recently added at the 101 bridge. The JPA will do what they can, but my understanding is that 100-year protection will simply remain out of reach for a host of reasons.
Stay safe everyone and remember that California is shaped by floods as much as drought.