Drinking Water Well Pump Control Strategy

[djcbgn]

Hi,

I am working on a very large development project (2000 homes at buildout), for which the city is requiring the developer to install wells to provide water supply. The developer does not want an elevated tank on the site and there is a connection to the county system for emergency water demands. I am asking for input on controlling the well pumps by system pressure or another option other than tank level. They are performing test wells now so I dont know the production capacity of each well yet but I expect each well to produce around 150-200 gpm and there will be several.

I dont have experience with hydropnuematic tanks so I was looking for some guidance here for sizing.

Thanks for your help.

 

[bimr]

The proposed water supply scenario is too large for a hydropneumatic tank system.

Could you explain how the county system will supply emergency water demands?

 

[jhnblgr]

A system of this size should be required to have storage tank just to meet fire flow and pressure requirements. Hydro pneumatic tanks are a poor idea in general. Ideally the development should provide a backup water supply to the municipality and become part of the district. Utilizing the existing system for storage. But likely this isn’t an option. The system needs to be designed to the municipal system pressure or have a pressure regulator installed and flow meter. You will need a whole treatment system for the water based on local regulations. The only other option is a booster pump system to pressurize the system but that is a really bad idea. The developer is always going to take the cheapest route and likely the shortest lifespan and with years of fixing systems like this because they end up in disrepair and burned out leaving the home owners with the bill and hating engineers.

 

[LittleInch]

Well first you need to work out your max and min demand and what you think the cycles are. but your demand is likely to be 10 or even 20:1 turndown.

For 2000 homes the flow is unlikely to ever be zero so you will need at least one or two wells running at all times. then for a network you will need to work out where the inputs are from the wells and where the lowest pressure will be in the network.

Forget any sort of micro hydropnematic tank. That's for single dwellings each with their own water pump. You're in a completely different league with 2000 houses.

Then you can figure out a cascading start for the wells so as pressure falls more wells start up. You probably need to program in a sequence of which wells operate all the time so its not the same one each time.

but this will cost money and effort to do so is normally why a simple elevated tank with level control provides some spare capacity of those peak 15minute periods in the day when everyone turns the shower on and flushes toilets etc or decides to water the grass all at the same time. It also give a very consistent pressure.

Basically users just want potable water at a decent pressure available 24hrs day/ 365. And water that doesn't make you ill. Fail any of those and the wrath of the homeowner descends on you with a vengeance....

 

[EdStainless]

Why are towers and standpipes so ubiquitous?
Because they are the best solution for this application.