Laying a new sump line for basement sump this weekend. Old line is 1 1/2" black poly with freezing problems in winter due to undulations and water collecting. Sump handles water softener backflush, water from condensor/AC, and whole-house humidifier if I hook it up this winter, with no or very minimal ground water; presumably this is low flow, though I don't know water use for the humidifier. Current system also is discharge for inground pool filter, connected with a "Y" with bronze check-valve in the leg from sump to the "Y" to prevent flow into the house (additional typical check valve 3 ft from pump discharge). Freezing conditions as I live in Michigan. Original is not below frost line and that is not an option for new line.

Distance from exterior wall to discharge is about 120 LF. Based on friend and another post here I plan on using 4" diam schedule 40 pipe for the main line. Interior line will be 1.5" PVC from pump, through check valve, through about 18 feet in basement, through the wall and likely into a "freeze stop" or similar device to provide extra protection in case of freezing. Discharge end will have grated cap.

My questions are:

1. What slope do I need?

2. What is minimal depth below surface? The early section of 4" line near the house will be the shallowest because of other piping (pool) that I would rather cross over rather than under. Might be 3 inches below the surface in an area that will only see foot traffic. After 20 LF I have to plan on heavier traffic, but only from lawn crew, nothing heavier.

3. Debating whether to tie pool discharge into this or not. Could use current line though it may interfere with laying this one since I'm going to follow same trajectory for first 80 feet. Since current line is sufficient in the summer I could have two separate lines. If I do join them then how do I avoid using a 4 inch check valve upstream of the "Y"? There's going to be the rubber flapper/check vavle in the basement, but that is insufficient for protection from the pool pump, so I know I need another one, but where should it go? Should I simply run 1.5" PVC into the ground, put a check valve in a 1.5" horizontal piece, and then transition to the 4" PVC? Problem is, kind of defeats the purpose of the 4" line, doesn't it? Any thoughts would be appreciated.

4. What's the pea gravel for? Having a solid base under the 4" line to prevent undulations or to distribute load from above? Can I avoid using pea gravel and just bury it in the ground?

5. I've never used SDR pipe. Any advantages cost-wise or other?

Thanks, I think that's it. Never one for short questions or posts:)

You say "Original is not below frost line and that is not an option for new line.
" so you must be below the frost line, right? The frostline varies a great deal in Michigan from 42 to nearly 50 inches, where do you live, UP? This may help you http://www.summittwp.com/zoning/MICHRESCODE.pdf Your slope in the pipe must be 1/4" per foot but Michigan code also reqyuires your foundation grading to slope 6" in the first 10'. I'd use cloth covered balck poly pipe buried abelow the frost line with gravel above and below by 6". I would also rethink about back flushing the water softner into this pit, that's a lot of sodium.

Thanks for your response.

Not means not.. . Not sure why my words are confusing. I'm in SE Michigan, everyone talks of 42" frost line but this line will be in the frozen zone if you will, not doubt about it. That's the purpose of going to 4 inch and making sure I have continuous slope.

Won't be going into a pit, and no other options for it unless I go to a dry well. Don't want to and probably can't go into septic.

B ump

Top 12" above pipe in 6" layers sloped 1/8" per foot.

The gravel does help distribute the weight, but probably more importantly it allows the soil pipe to move with expansion and contraction.

Top 12" above pipe in 6" layers sloped 1/8" per foot.

The gravel does help distribute the weight, but probably more importantly it allows the soil pipe to move with expansion and contraction.

Thanks KISS, but you need to throw in a few more words for me. Top with pea gravel 12" above?? seems like a lot if that is what you are saying. 6"layers? Of what? If you are talking pea gravel, what's the diff between one 12 inch layer and 2 6 inch layers? Got you on the 1/8"slope though.

Please clarify. Thanks.

The dirt on the top of the pipe is packed (tamped) in 6" layers.

Gravel is only necessary to the centerline of the pipe to the width of the trench.

This URL explains it much better:

http://www.pweagleinc.com/literature/tb/tb-i1.pdf

And a whole bunch more stuff here: http://www.pweagleinc.com/support/

Other useful info:

18" minimum width of the trench.

Geotextile fabric can/should be used to prevent migration of the layers of say dirt and stone.

The requirements are different for corrogated pipe.