The basement has a sewer clean out at 42" high and its vertical pipe section can be cut to add Y for the washing machine and sink. There is new concrete sump pit 18x18x14H - the contractor failed to make it deep enough nor flat at the bottom. I suppose to add 1/2HP sump pump (1-1/4") and a check valve to pump water to the sewer pipe(there is no other pipe in this city). My questions are:
1. shall I make use of the sump pit or use the sink to pump water from sink/washing machine to sewer pipe?
2. if I use sump pit to contain all water before pump it, will it be very dirty or odor?
3. if I connect sink to sewer, then I need two pumps and two check valve right?
4. Can I connect washing machine pipe to sewer directly?
Many thanks. I have never used sump pit.

shall I make use of the sump pit or use the sink to pump water from sink/washing machine to sewer pipe? You wish to install a open pit holding smelly water in your house? Not a good idea.

if I use sump pit to contain all water before pump it, will it be very dirty or odor? Jet's se. Smelly, dirty laundry gunk in a open pit. Will it smell? Not unless you breath in.

[ if I connect sink to sewer, then I need two pumps and two check valve right?/QUOTE] No! The washer will pump into the laundry sink. That leaves just one pump to pump the sink to the sewer.
[QUOTE]. Can I connect washing machine pipe to sewer directly? Not unless you trap and vent the washer.
Why not do the job right and install a closed pit and pump that's made for the job. Click on SANISWIFT® (http://www.saniflo.com/homeowners/sfa-product-line/saniswift-%C2%AE) to check them out. Good luck, Tom

Many thanks Tom. Of course I want to do it right, and the pit can have a cover. Looks like I have two options: let sink water goes to pit and use (single) pit pump; or use second pump to pump sink water. Which one would be right?