Had a wierd issue happen today. Last fall I replaced all my drain pvc off with new 1 1/2". Installed a check valve in the line and ran it out of the house as it was previously. From the outside I ran a down spout that was 10' east of it to a T with the sump pump. The side that pitches down towards our ditch (65' to the west) off the sump pump is a 45 degree turn. The down spout then runs straight through the T. All pipe up to 25' off the house towards our ditch is 2" where from there I adapted to 3" until the final 20' where I adapted up to a 4" pipe for a 4" opening at the end.
All fall, spring and up to today we've had no troubles. All runs straight out no issues. We had a serious rainfall today and here's what I'm having troubles with:
The downspout that's 10' east of the sump pump outside has a plastic adapter that fits the pvc and the down spout metal. I pulled this back because I heard some "glugging" sounds. When the pump kicks in about 5 seconds later a rush of water comes back up into the down spout spilling onto the landscape. I checked the end in the ditch and a steady stream of water still spills out. I have a backup pump that I used to allow my installed drain line a break to dry out. When I plug back in the original sump pump the first push out causes the water to rush back up the pitch to the down spout away from the ditch.
My thoughts are:
1) A rodent got in and is partially clogging the system causing the pressue to release up the pitch to the down spout.
2) Because it was a LOT of rain the pitch from the down spout shifted and now it's level causing the rush to partially run up the wrong way.
3) I should've used bigger than 2" off the house.
Any suggestions or ideas would be greatly helpful. All spring we had solid rain but never saw this before until today.