Wilson and Company engineer Glenn Selover gave his analysis of Cantrell Dam and why the least costly and safest thing to do is “breach” the dam instead of repairing it, but City Commissioner Merry Jo Fahl insisted the people would not “understand” such a move and it would “scare” them.
Selover gave his presentation on Cantrell Dam at the Dec. 14 city commission meeting. He was put on the agenda by Fahl. At the last meeting Fahl said she wanted an explanation why Wilson & Co. was recommending breaching the dam.
Only a few minutes had been given to the dam capital project during the October report given by Wilson & Co.’s T or C spokesman, Alfonse Holguin.
Evidently Fahl’s mild request to learn more about Selover’s recommendation to breach the dam moved someone on city staff to rehire or extend Wilson & Co.’s contract to do more study. Instead of simply explaining his September recommendation, Selover presented the alternative of fixing the dam. Dam improvements, Selover said, would cost $3 million to $5 million.
Selover pointed out the difference between a functioning dam and a breached dam in a storm event would only be “200 to 300 cfs,” or cubic feet per second.
Imagine a 10-foot-square room filled to three feet with water. That’s the reduction of water that would flow second by second through the dam’s spillway, making it understandable Selover did not recommend the city pay up to $5 million for so little extra safety. This cost estimate also does not include future maintenance costs of the dam.
The dam, even if it had been functioning, would not have been able to handle the five inches of rain that fell within seven hours on July 26, 2020, Selover said. It held up the water until it “failed,” causing “a wall of water” to flow hard and fast, causing more damage than if the dam had not been there. Selover said, “The dam either needs to be functioning or breached.”
Selover explained how projects downstream from the dam offer property protections to Village of Williamsburg, T or C and Sierra County structures. Since the flood a berm was built but needs to be reinforced to divert water into a channel, the channel capacity needs to be increased and a box culvert installed. These would cost about $1.7 million, and would prevent flooding if more than three inches of rain falls quickly.
After Selover’s presentation, Fahl decried the fact only one option—breaching the dam—was offered in September. “People don’t understand what breaching means and it would scare the people,” she said. When she read that recommendation, Fahl said she found it “alarming.”
Fahl was employed as district manager of the Sierra Soil and Water Conservation District for many years, which included duties concerning the nearly 20 dams and their functioning within her district.
Fahl invited officials impacted by Cantrell Dam’s failure during the flood occurring on July 26, 2020. Sierra County officials included Flood Commissioner Sandy Jones, Emergency Services Administrator Ryan Williams and County Commissioner Jim Paxon. The Village of Williamsburg was represented by Mayor Deborah Stubblefield and Mayor Pro Tem Majorie Powey.
Consensus among T or C, county and the village officials determined they will work together to prevent a similar flood event and that “communication is key.”
Mayor Amanda Forrister elicited promises that mutual cooperation on the project also means financial support as well.
Jones said fixing the flooding issue will require federal and state funds, which are more likely to be awarded if the entities cooperate. In fact, Jones said an agreement among the entities should be negotiated first and then grant money sought.
For more information on the July 26, 2020 rain event and Cantrell Dam, see the Sierra County Sun article:
https://sierracountysun.org/feature/july-26-torrential-downpour-cantrell-dams-malfunction-part-2/
It appears that the $1.7 million suggestion is the most logical, not only from a money savings, but from a practical, mathematically proven solution… that solution is what we in Cuchillo proved to the people of the County and the US Army Corps of Engineers when we fought the Cuchillo Flood Control Dam, aka White Elephant Dam… Channel design is the answer… I still am amused when I see and hear of flood control efforts in the County, which are done without the use of mathematics and physics!!! But, we tend to take the bottom of the barrel when choosing some of our local leaders and administrators, and they don’t want to hear from some of us with real world experience!!!