Attached is a PDF of the presentation given Monday night at the CU meeting. I’ll try to keep this as succinct as possible.
Over the past several months, the CU Board has travelled to several locations throughout the immediate area to inspect equipment, interview operators, ask questions, and generally educate ourselves.
Mt Sterling – is in the process of building a Option 3 plant, with an accompanying Reverse Osmosis (RO) softening system.
Canal Winchester – built an Option 2 style plant in 2007ish.
London – Lime plant
Plain City – Dualator 6 style plant
Carmel, Indiana – I’m going here this Friday on my way home from work. They have had a fully functioning Option 3 style plant for the past several years.
IBI gave us 4 options after assessing our plant. They are as follows:
1.) Do Nothing. Choosing to do nothing would put us at risk of a future failure, and would not help resolve our EPA issues. This was assessed to be not an option.
2.) Install a new system consisting of a 3 separate pieces of equipment. We have been calling this the Vertical Pressure Filter (VPF) system. In the attached PDF, it’s the IBI Option 2. A fully implemented Option 2 would resolve our issues at the plant.
3.) Install a new system consisting of an integrated piece of equipment called a “Dualator.” A Dualator does the exact same work as a VPF style plant, it just is in a different configuration. A Dualator would resolve our issues at the plant.
4.) Install a utility scale “membrane” plant. A membrane style plant would take sewage and make it drinkable. It removes literally everything that isn’t water. Due to the high source quality of our ground water, we were told this option is overkill. It is also very expensive. While it would resolve our issues at the plant, we assessed this as being cost prohibitive, and therefore don’t see it as necessary.
With the four Options distilled down to two, we began to further investigate the differences between Option 2 and Option 3.
Both Option 2 and Option 3 use the same processes to remove iron from our ground water. Those processes are: Aeration, Detention, and Filtration. The only discernable difference is in Filtration.
Option 2 filters the water under 63 pounds of pressure. This generally results in media loss over time. (Think about how fast moving water tends to stir up mud, where slow moving water tends to be clearer.) Option 3 filters the water using gravity to pull it thru the filter media. Due to the slower moving water, less media loss is anticipated.
Difference 1: pressure vs gravity through the filtering media.
Option 2, because it is under pressure, uses a sealed pressure vessel to hold the media. If you wanted to look inside of a pressure filter, you would have to remove a hatch and gasket to visually lay eyes on the filter media. Gauges would have to be relied upon to determine the operating status of the filter.
Option 3, using gravity, does not require a sealed pressure vessel. Instead there are four separate chambers inside the Dualator that can be inspected using a hatch. If you wanted to know the status of a filter, you could open the hatches one at a time and visually lay eyes on the media. These chambers are discrete and not connected. If you wanted to perform maintenance on one chamber, you could still have the other 3 operating normally.
Difference 2: reliance on gauges vs visual inspection
1.) Tonka equipment is highly regarded by 100% of the operators we spoke with. We didn’t talk to only sales personnel, we talked to the people operating and maintaining this equipment on a daily basis. Tonka has also been in the same hands for 60 years, whereas their competition seems to change hands every few years. The Tonka reps have also been extremely responsive.
2.) Underdrain material is important. Underdrain material should either be concrete or PVC. Metal underdrains tend to be the part of a filter vessel where the highest amount of maintenance is required. PVC or concrete eliminates this issue. We should specify this for any future equipment.
3.) Air and Water Backflush, trade name “Simulwash” is a desirable feature. A possible cause of last years’ problem may have been the formation of a “mudball” in our filter media. Because we currently only water backflush, this “mudball” may have broken free and taken a lot of our media with it. By adding air to the backflush routine, any mudballs should be broken apart instead of getting bigger and bigger. Furthermore, a Simulwash uses only 5 gallons of water per minute per square foot of filter material of for backflush, whereas a water only backflush uses 15 gallons per minute per square foot to backwash the filter media. A Simulwash system is anticipated to save us 1.7 million gallons of water annually. (Our plant produced 75 million gallons of water last year, so this would should save us 2.2% of water wasted on backwashing every year – not a small amount.)
4.) Climate control and electricity. Our current plant facility has an extremely limited ability to control the climate in the filter room. This results in significant condensation (sweating) of the filter vessels. Furthermore, our current electrical system is not water sealed and is rather dated. We are currently determining the best way to handle these issues as well.
Our initial determination is that a fully implemented Option 2 or Option 3 would do the job for us. What we do not have a firm handle on at this time is cost. This is obviously a critical piece of information.
At the meeting on Monday night, a committee was formed to take these lessons learned and build an RFP around them. Our intent is to send an RFP out to the market to get apples to apples quotes back, with the features we’ve found to be desirable, on what it would cost to implement either one of these Options.
We fully intend to keep the community apprised of our efforts as we work through the issue this spring/summer.