need advice: sump pump install and connection

[mele63]

As discussed my my recent post, we had a flooded basement despite the sump pump running on a constant basis for six hours. After the dust has settled, I set out to check a few things, including the discharge line. Well, it turns out the pump worked great, at pumping 30 gpm right back into the basement. It's really a sight to see; the pump cyles and the water pours right back into the pit. Someday I'll do some digging outside to see how stupid the guy who installed the discharge line really was.







For now my plan is as follows:

1) re-route the discharge line up and out, the routing the water into the downspout drain pipe (4" corrugated)

2) while I'm at it, install a second back-up pump in the pit, at a higher level using a "brick" to add two inches to the float height. The new pump is the same as the existing, Liberty 1/3 h.p.

QUESTIONS:

1) any advice on routing? I am a little stumped as to the best way of attaching to 1 and 1/2" pvc pipes to the 4" corrugated drain pipe. Should I tie the two 1 and 1/2 pipes to together inside the house, or run two ouside in tandom? Higher or lower? Is there a connector made for this?

2) are there any fatal flaws in my plan? LazyPup posted some advice on sizing pumps, but I'm afraid the conditions are too variable; esp. the rate of flow into the pit.

Thanks in advance.

[mele63]

Here's another photo, showing the grade of the lot:

[LazyPup]

I have attached an illustration that will show a fairly simple way to combine both pumps into one line. As you can see the riser from the pumps will be basically the same as you have now except you would also add a manually operated gate valve on each riser. With the gate valve you can isolate one line in the event it is necessary to service the pump or gate valve, while still keeping the opposite line in full operation.

On the top of the riser you then install a Wye & 1/8 bend or combo with the side opening on the riser and connect the horizontal line straight through the combo. You would then also have a cleanout on the end of the horizontal line.

The problem now is to determine the proper size of the lines. The risers are simple, we just use the size of the pump discharge, which in this case is 1-1/2" however when combining two pumps on the horizontal line, the horizontal line must then be capable of handling twice the volume.

There is a common rule of thumb which states that when we increase the diameter of a line by one nominal trade size we roughly double the capacity of the line. The next nominal trade size from 1-1/2" is 2".

The formula for comparing the volume of two dissimilar lines is
Large Diameter Squared divided by small diameter squared.

Comparing 2" to 1-1/2" we get:

(2 x 2) / (1.5 x 1.5) =
4 / 2.25 = 1.77

Each pump is rated to pump 30gal/min which would be a combined volume of 60gal/min. however the 2" line will only handle 1.77 x 30gpm = 53.1gal/min.

The trade off here that there would be a slight loss in total capacity but understanding that there is no 2 1/5" drainage pipe if we opt for 100% capacity it would require increasing to 3".

Now consider the next problem we would encounter. If we elect to use the 2" with the slight loss in total capacity we may be able to get the 2" pipe through the existing hole in the concrete wall whereas if we insist on keeping 100% capacity it would require enlarging the hole in the concrete to permit a 3" line.

To connect the horizontal line to your 4" corrugated you would first use the appropriate reducer bushing to enlarge the end of your horizontal pipe to 4" PVC. The make a PVC x corrugated transition fitting that screws into the corrugations and makes a 4" female hub that is then slipped on the end of the 4" PVC.

[mele63]

LP that is awsome; like having a plumber for a neighbor. Thank you.

One problem. The existing pipe through the foundation is cracked. There was a 90 degree elbow going downward on the other side. It cracked under three feet of soil. (I saw it with a flashlight this afternooon). This, together with 11" of rain, caused my basement to flood.

To be honest, I haven't a clue as to where the pipe through the wall goes. They may have run it out to the storm sewer but I doubt it. I think that pipe is below the level of the storm sewer.

In the future I want to be able to SEE the water coming out of the pumps/pipes. That's why I wanted to tie into the downspout line.

I can't go to daylight because there's a house below me to the left. I put the downspout pipes in because water was going into their sideyard. The downspouts go to daylight at the curb via one 4" line.

Now I know we can never measure to volume from the downspouts. I may have to wing it on this one; I don't want to dig up the front yard again to put in another 4" drain pipe.

I figured I'd run the two pipes up the wall inside and out through the wooden sill where a lot of the other utilities come/go. Do you think this is ok? I'm really not comfortable with drilling one or two more holes through the foundation.

[LazyPup]

In one of your other posts you show a picture of the discharge line where it connects to the pump and you stated that the pump discharge was 1-1/4" but the installers had installed and 1-1/2pvc x 1-1/4MIP adapter thus increasing the line size from 1-1/4" to 1-1/2". That is fine, in fact if you examine the discharge tables in the pump instruction book it will show where they recommend increasing the line size if when using a longer discharge line to compensate for line friction. Actually a bathroom lavatory is the only fixture in a house that is permitted an 1-1/4" drain line and the code allows us to increase both the line and trap one nominal trade size so we often increase 1-1/4" to 1-1/2" to avoid the hassle of maintaining an entire inventory of 1-1/4 pipe and fittings for limited use.

The good news is that the pump is rated for 1-1/4" therefore a 2" horizontal will be more than adequate.

(2 x 2) / (1.25 x 1.25) =
4 / 1.56 = 2.56

A 2" horizontal line will have 2.56 times the capacity of one pump thus even with both pumps running the 2" line will have more than adequate capacity.

Rather than running two pipes up and out through the sill you could still combine both lines into a 2" line in the manner i detailed, then run the one 2" line through the sill as you describe.

[mele63]

Thanks again LP

Is there any device (akin to a pressure-relief valve) that would divert the water from the sump pump to the ground, in the event the underground drain pipes freeze shut?

[mele63]

picture of work in progress - dual sump pumps

Here are some pictures of the project.....special thanks to LazyPup for all his help so far.