Preventing freezing of an exposed section of sewage ejector discharge line...

[Foxwaves]

I have to run a discharge line from a sewage ejector to a septic tank. About 20' of this is vertically up a stone bluff and I'm looking for freeze-prevention ideas? And advice? I'm hoping to avoid building an insulated box, but not sure what would be best. I don't think heat tape or that sort of thing is practical. Any plumbers out there that work on bluff-side homes? Thanks!

 

[hj]

Must be a hefty ejector pump, since few would handle that head and still deliver good volume. NOTHING other than "adding heat to the pipe" will "prevent" freezing. You either use heat tape or drain the water out of the pipe after every use.

 

[Sponsor]

 

[CountryBumkin]

Are you thinking that there will be liquid in the pipe when it's not in use (not pumping)?

 

[Foxwaves]

Must be a hefty ejector pump, since few would handle that head and still deliver good volume. NOTHING other than "adding heat to the pipe" will "prevent" freezing. You either use heat tape or drain the water out of the pipe after every use.

Thanks for your reply. I made a mistake in my first post: the exposed vertical part up the bluff is going to be just a few feet...maybe 5' or so. The rest of the way to the septic tank is about 11' more of rise, so about 16' of head. The pump is a typical 1/2 hp. What do you think of the one I'm considering:? http://www.sumppumpsdirect.com/Zoeller-915-0005-Sewage-Pump/p61880.html

A bit more research seems to have a method that solves the problem simply: omit the check valve. After the pump shuts off, less than 5 gallons will flow back into the grinder-pump basin, leaving the discharge line empty. An apparent added benefit is backwashing the pump impeller. Sound reasonable to you? I want a happy customer.

 

[Foxwaves]

Are you thinking that there will be liquid in the pipe when it's not in use (not pumping)?

Well, with the usual installation, the check valve would leave the line loaded to the septic tank all of the time. But I'm thinking of just omitting the check valve and letting whatever doesn't make it into the tank just fall back into the basin, leaving the line empty. Thanks for your reply.

 

[Jadnashua]

That could also get expensive, since you'd be essentially pumping the waste sometimes, more than once? If it say held 10g before the float switch opened...you added a quart, it would pump, having to refill the line, at least half of that would then fall back into the basin without a check valve for you to pump again the next time, making the potential for it to have to run much more frequently, wearing things out much quicker.

How big is the basin?

I take it that they do not want to deal with burying things below the frost line.

 

[hj]

IF the discharge covers the end of the pipe it will ALL be "sucked" back into the pit. A check valve after the rise with a vacuum relief valve ahead of it will just drain the water out of the riser back to the pit and whatever is in the horizontal pipe will flow to the outlet.

 

[Foxwaves]

That could also get expensive, since you'd be essentially pumping the waste sometimes, more than once? If it say held 10g before the float switch opened...you added a quart, it would pump, having to refill the line, at least half of that would then fall back into the basin without a check valve for you to pump again the next time, making the potential for it to have to run much more frequently, wearing things out much quicker.

How big is the basin?

I take it that they do not want to deal with burying things below the frost line.

Hello jadnashua...There would be re-pumping of material, and I agree that's not ideal. The basin is 18"x30" which probably is 33 gallon capacity, but I'll have to check on that before ordering. With a grinder pump I'll run a smaller 1-1/4" pipe (maybe 1-1/2") which holds .064 gallons per foot, or 4.8 gallons in a 75' line. That would be dumping about 1/5 of the apx. total basin capacity back into the basin.

The available location for the basin in on a rocky mountainside, and to bury it would mean going down into solid rock. The same is true for a portion of the discharge line. The homeowner understandably is concerned about expenses, and I'm concerned about getting a good job in a difficult situation. Thanks for replying.

 

[Foxwaves]

IF the discharge covers the end of the pipe it will ALL be "sucked" back into the pit. A check valve after the rise with a vacuum relief valve ahead of it will just drain the water out of the riser back to the pit and whatever is in the horizontal pipe will flow to the outlet.

Hello hj...The discharge pipe will be emptying at the top of a concrete septic tank, probably 750 or 100 gallons, so it should freely drop in as long as the field line is doing its job. I'll most likely not install any kind of valve on the discharge. Thanks for your help.