Pumped Effluent Hight / Distance Limits

[gborg]

Rural Septic system contractor is concerned about pumping effluent from septic tank/pump chamber to drain field D box that is 75 feet distant with a total rise of approximately 5.5 feet. There are no intermediate obstacles and the rise is pretty constant over the 75 feet. This doesn't seem like it should be a problem given use of check valve(s), hose, and appropriate pump sizing. My suggestion is to use 2" or 3" flex plastic pipe from pump with 2 check valves in line, emptying into a distribution box feeding gavity absorption field. Too simple?

 

[Maury]

Not enough information. Why use two check valves? You need to have the pump curve to evaluate the hydraulic requirements of the discharge line and I have doubts about using a 2" line because of possible clogging unless you use a grinder pump. Will you be cycling between two pumps so there is a backup or will you be relying on one? Don't forget backup power (battery or generator).

 

[mmenarry]

I'd use a macerator (shredding) pump for that sort of work. A few years ago I had an almost identical situation (although a much longer pipe approx 180m), and we were pumping treated effluent. Even though it was only a domestic dwelling, it took a significant amount of "oomph" to get it to go the distance at a decent flow speed.

Do you really need 2" or 3" pipe? What sort of volumes are you expecting per day? True, you'll have less chance of clogging on a larger line, but you run the risk of a buildup (especially with poorly treated septic tank liquor) if you don't have a decent flow speed through the pipe itself.

M.

 

[gravel]

If you are pumping clear effluent into a D box, the 2" line is more than sufficient for the 75' distance... the pump can be rather smallish even, as you don't want it squirting hard into the D box... all you are doing is lifting the flow to a higher elevation (5'+ donsing tank depth= 9' maybe)...better to set the pump on/off floats so the pump cycles more frequently with mini loadings to load the absorption field somewhat uniformily over the 24 hr period, than trying to take on superloads. Probably wouldn't want to pump more volume than the absorption bed later pipe volumes are in one dose cycle...I don't see the need for a check valve on the forcemain.. just let the line drain back into the dosing tank (pump box)... a check valve just introduces a clogging area and a line freezing potential in north areas.

 

[gborg]

Thank you all for the input.This is a 2 bedroom moslty weekend use dwelling. Yes I am routing clear effluent to a D box 75' distant. I guess I was looking for a confirmation that my initial plan was at least sound from a design standpoint. Good point about the check valve, this is in Michigan so it can get pretty cold. Thanks again for the comments. GB