GSD Upgrades Seismic Plans for Contact Chamber
The GSD board meeting began with a closed session for the personnel evaluation of the General Manager. The report out from the closed session by Board President was “the General Manager received a very positive evaluation.”
Julie Lyon of the Summer Games and the Southern Humboldt Unified School District attended the meeting. Lyon is expressing an interest in joining the GSD Board, but no public discussion occurred during this meeting. Lyon said, in a conversation after the meeting, she has served on the SHUSD Board and has time in her life to serve the GSD District.
The Need for the Contact Chamber
The District is moving forward with its purchase of the contact chamber. Emerson explained the District’s need for the contact chamber saying,
The reason we are replacing the tank is because we are required to replace the tank per building the treatment facility in the first place.
It was part of the design, so we are putting something back in place that was already there…. If we don’t have the contact chamber in place, then the state can tell us how much chlorine to add and what the residual has to be at different points.
It becomes a real difficulty for the Operators. And also, if we increase the gallons per minute, there is the possibility we are not going to meet our disinfection requirements for the State.
It’s up to the State. They are going to tell us what to do.
And if that’s the case, we issue a boil water order. So the entire town, we will recommend they don’t drink the water.
I don’t think anyone wants that to happen, but that is the scenario, the real scenario that may take place if we can’t get a contact chamber installed before the high water demands hit the district and we can’t meet it.”
The above ground contact chamber is a baffled 1,000 gallon tank shaped like a traditional propane tank, long and low. Water weighs 8.35 lbs per gallon, so the tank will weigh just over four tons. Thousand gallon water tanks are plentiful in the hills of Southern Humboldt, but nonetheless, above ground water tanks can represent a physics challenge during high magnitude seismic events. Velocity times mass indicates the sloshing momentum that will work on the tank, its foundation and the straps and anchors that hold the tank down during earthquakes.
Board Member Thompson and retired Caltrans Engineer asked, “What have we learned about the earthquake design for the foundation?”
…they wanted additional monies, to do the testing [with] their engineer back east, and we felt it was more advantageous for us to have a California engineer approve that for California. And the dollar amount that they were going to require, our engineer, Andy Sundquist, [of Candor Rock LLP] says he has somebody who can do it for less. And he is confident it will pass. So we are going to have the seismic [calculations] done by the California engineer who works with our engineer before the tank arrives, before it is completed.
We are also looking at putting in additional support in the middle, as you had mentioned previously. Spreading out the weight over a larger area, but also having the support in the middle that will go down to something hard. Our engineers are working on a design that would have something going below the saddles down deeper into the soil so there’s something harder that its resting against
…[P]art of our design for the slab that will be under the contact chamber [is] having an additional wall or saddle built underneath it to where we have three supports on the tank instead of just two. It’s easier for us to do that than to have the delays with the tank company.
A neighbor of the district, Christine Vogel, asked a long list of questions. One was if a reason for the contact chamber’s failure had yet been determined. Emerson said it had not.
Vogel also asked how this tank came to be chosen over the options that have already been approved by the State of California.
Some of it had to do with cost. We wanted something above ground, I didn’t want anything underground again because we cant maintain it. So those were the factors we looked at. Our engineers felt, after researching this company, that this was something they have great success with back east, so we felt that with the cost for the maintenance,….it was felt that this was the best option for our needs.
The Board voted unanimously to move forward with this project.
GSD Property Faces East
Back in December, Greenwired Renewable Energy Solutions presented information about the possibilities of GSD building a solar array that could offset half the District’s $57,000 annual power bill. It seemed the project might pay for itself via the energy cost savings.
While no decision has ever been made in public, the District seems to have moved away from that idea. In April, Emerson reported Redwood Coast Energy Authority is looking to lease land for solar energy production. Emerson said the District has submitted paperwork for that program. However, staff noted the District’s available land is primarily east facing.