Guys, my basement and perimeter drain runs 960' west to an open ditch. I have 2'-10" of fall in that distance. Normal summer, and fall, no problem. But winter and spring rains can quickly overwhelm the ditch, and then the water comes UP the basement drain and works the dog$hit out of the sump pump. The ditch comes up quick, flows fast, and then slowly goes down. Now, I understand the venturi effect in a carb, but I also know you are dealing with different pressures as the air flows thru. Speed increases, pressure drops. Because of the non compressability of fluids, is there any thing I can add or do to my outlet to allow the ditch flow to help suck the water out of the outlet pipe? I can't grasp how building a pipe venturi would help, the water pressure will remain the same, right? Or wrong? Chuck
Just a logical approach... You have 2'10" of fall ... Let's say the ditch fills up 10" so now your fall is only 2' or 24 inches over 960 feet. That is only .025 inch per foot. plumbing drains look for 0.125 per foot. You don't have enough flow capacity at present. And the same rain that overflows the ditch increases the water flow at the house. If you pull a negative pressure at the stream, I doubt it will solve your problem unless the pipe and venturi has no leaks. Any air space will negate the suction at the drain. Plus the venturi is a clog waiting to happen. I would build an overflow pit at the house. and pump the excess water to the ditch (as your sump pump is now doing)
If I understand your post correctly, it sounds like you need a one way valve on the end of your drain so ditch water can't back into your drain.
A sewage ejector pump may help your situation. They usually pump a higher volume with more pressure than an ordinary sump pump. I think you need pressure to overcome the resistance the ditch water is creating against your outflow. IMHO An industrial sump pump is another option. We used them in trenches that around borrow pits for dewatering in really wet soils. They were 6" pumps. A check is must have addition to your drain line. Most big box stores sell them up to 6". I have installed them in 3 different drain lines where I live. They are very effective.
You don't have enough speed in the ditch to make more than an inch or two difference. The backwater check valve is what you need if the water is coming back from the ditch. If it's just not draining fast enough, you need to figure out if the water level is rising too high, or you're getting too much rainwater into the drain, or what's going on.
How deep is the ditch below the ground surface ? It might be that the ground is freezing and limiting the capacity to drain. I also agree that the pitch is insufficient.
Although the pitch could be better, the proper pump and check valve will create a force line. Similar to a sewage force main. A tee in the line with a vertical pipe open at the surface may even help. I did that on one of my drains but after several years it was never needed. The opening of the riser would need to above the maximum height of the ditch water's highest level.
Yeah if it was me I'd put in a decent sized wet well and pumps and discharge to the ditch above the high water line so you take ditch level out of the equation.
So is the water in you basement only from the back flow of the drain, or other sources? A back flow preventer valve as shown above will stop the back flow as it's name suggests. It always seems to me that homes are never built high enough. A buddy of mine built a home years ago, and asked me for advice. I said tell the excavation company when they do your basement that you never want water problems. They didn't dig for his footing, the leveled the existing ground and poured his basement footing higher than the road, an well above the ditch. Took a lot of fill, but he has never had a drop of water, unlike his neighbors. My sump pump hole is in the same hole as the outlet for my sewer, I am on city sewer. At one time this sub division got water every spring, and everyone had at least 2 sump pumps. When the company I work for did the sewer in the neighborhood, there was a hard ledge at one point. Once they broke through, the water problems stopped. I assume the water started running out through the stone bedding around the pipe. I do get water in the sump hole for 2 or 3 days in the spring, but I just crack the cleanout on my sewer ( don't tell the city) and it takes it away. Back flow preventer.