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  1. OneManWolfpack

    Containment for Sodium Hydroxide - Tight-Wrap Double Walled Tank

    I'm looking for guidance on containment for a 15,000 gallon steel tank to store 25% sodium hydroxide. I have specified a double-wall tank in lieu of a containment bund. I received an inquiry from the tank supplier asking if a "tight-wrapped double walled containment" is acceptable in lieu of...
  2. OneManWolfpack

    NaOH (Caustic) dilution system

    Another idea that's been suggested is to pre-fill the tank with enough water so that when the truck pumps 50% into the tank, the resulting solution in the tank is 25%. This seems simple, but I know you have to make sure the solution is constantly mixed or it will blow up and kill everybody or...
  3. OneManWolfpack

    NaOH (Caustic) dilution system

    I'm designing bulk caustic storage facilities for an existing 2 MGD water treatment plant. The plant currently receives bulk caustic shipments in 50 gallon drums and dilutes it to 25% in a day tank prior to feeding. Client would like to switch to tank truck delivery, so the obvious solution is...
  4. OneManWolfpack

    Single- or Double-Acting Altitude Valve for Elevated Tank

    I'm designing a new 0.5 MG elevated tank, which will be filled from an existing distribution system by a 10-inch line. I need an altitude valve to prevent the tank from overflowing. I've seen two different arrangements: 1. A single-acting (one-way flow) altitude valve with a bypass check...
  5. OneManWolfpack

    Cost Estimating Guidelines

    Construction cost estimating is not my forte. My go-to methods are RS Means and emailing reps. My firm attempts to compile bid price records from previous projects, which is extremely helpful when I find relevant items; however, I often find this resource lacking. Most of the estimating I do...
  6. OneManWolfpack

    Algae Growth in WWTP Clarifiers

    I had an operator claim that covers require a lot of maintenance and therefore don't really result in a net benefit over periodic manual cleanings. What maintenance could there be for a cover?
  7. OneManWolfpack

    Algae Growth in WWTP Clarifiers

    What are your opinions on algae control in secondary clarifiers? Some of the alternatives I know/have heard of are: 1. Install a cover over the entire clarifier 2. Install sun shades for the effluent troughs only 3. Install an automatic brush/cleaning system 4. Increase manual cleaning frequency
  8. OneManWolfpack

    Zinc Primer for Potable Water Tank - Will Zinc Become the "New Lead"?

    It is a repainting, but the interior is to be blasted to SSPC SP-10. Should this be treated differently than a new tank?
  9. OneManWolfpack

    Zinc Primer for Potable Water Tank - Will Zinc Become the "New Lead"?

    OK. Just heard back from the sales rep. She misunderstood (or maybe I did) the company's reason for not providing zinc primers for immersion environments. It actually has nothing to do with health risks. She sent me a copy of a technical bulletin explaining their stance. Basically, they...
  10. OneManWolfpack

    Zinc Primer for Potable Water Tank - Will Zinc Become the "New Lead"?

    I'm specifying an elevated tank repainting. Right now, I'm going with AWWA Interior Coating System #5 (ICS-5) for the interior wet area of the tank. ICS-5 consists of a zinc-rich primer and epoxy intermediate and finish coats. All paints must be ANSI/NSF Standard 61 approved for immersion in...
  11. OneManWolfpack

    Filter backwash from elevated tank

    "If your line pressure reads 5 psi after the valve, the total energy in the fluid is actually higher, so you will not taking 75 psi across the valve." I'm not following you here. If the pressure is 80 psi before the valve and 5 psi after the valve, then there is a 75 psi pressure drop across...
  12. OneManWolfpack

    Filter backwash from elevated tank

    I'm not concerned about the pressure on the discharge side of the valve; rather, I'm concerned about the pressure gradient across the valve. Based on my analysis, the valve will have to impart a 75 psi pressure drop. To do this, it will be barely opened and thus susceptible to cavitation...
  13. OneManWolfpack

    Filter backwash from elevated tank

    The filters are gravity sand filters. The backwash water flows up through the filters (opposite of normal flow), and exits through backwash troughs. I estimated the head loss through the filter to be around 5 ft (2.2 psi) based off the attached chart. I'm assuming that backwash flow will...
  14. OneManWolfpack

    Filter backwash from elevated tank

    I'm working on a small surface WTP design. Instead of providing a pumped filter backwash system, we're looking at running a line from an on-site elevated tank and installing a flow control valve. One concern I have is the flow control valve wearing out. It will have to provide a significant...
  15. OneManWolfpack

    Wash water system to breakdown floating sludge build up

    A client of ours is having a pretty bad FOG problem at its WWTP, which is causing a number of headaches. One such headache is the build up of a floating sludge layer that shows up in the anaerobic selector tanks (see attached picture...
  16. OneManWolfpack

    Forcemain Tie in

    You could line the excavation and use a vac truck to pump it out.
  17. OneManWolfpack

    Wastewater lift station/forcemain problem

    bimr: Scratched my head over this one for a long time. I have no idea what would be causing the pumps to see less than half of the head they should be seeing other than they're pumping into half (or less) of the forcemain. If you have any other hypotheses, please let me know. Closing the...
  18. OneManWolfpack

    Wastewater lift station/forcemain problem

    Also important to note, the original 1975 plans for the forcemain show air release valves (no vacuum function). The owner replaced these several years ago with combination air-vacuum valves. I don't believe an 8-ft elevation drop is enough to collapse a 14-inch DIP pipe, so I'm pretty sure the...
  19. OneManWolfpack

    Wastewater lift station/forcemain problem

    The intent of both the gooseneck option and the backpressure sustaining valve option is to keep the line full. When the line is full, the pumps will see the friction head from the entire forcemain when they start. The gooseneck would have to be 8 ft above grade to match the elevation of the...
  20. OneManWolfpack

    Wastewater lift station/forcemain problem

    Thanks bimr. I got a quote for a 14-inch backpressure sustaining valve from Ross. It looks like a good valve and a good solution here. The problem is, that the thing is 6.5 ft tall and costs around $30k just for the valve. What are your thoughts about option 3? I've got this estimated...

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