Storm water drain removal

DeltaFox

Discussion: I have a 1950s home in Boston with antiquated storm drain plumbing. I know the storm drain system was outlawed and the plumbing was "plugged". I have no idea where this plugging occured.

Context: I want to relocate my sump pump basin to where the storm water p-trap is currently located.

Question: Can I cut the storm water drain (yellow lines) and cap both ends to make room? Or is that inviting too much risk for a main sewer leak?

Intplm.

I would open the clean out plug on that trap and look to see if water is running through it first. Especially if you are not sure what the drain might be serving. If you discover that it only serves the storm water and was not combined with sanitary then a properly sized sump pit and pump should be fine.

DeltaFox

I'm 100% it only serves storm water plumbing. I'm currently adding a basement bathroom and have replaced most of the cast iron plumbing under the slab. All my sanitary plumbing ties into the far side of the 4-way (longer red line in first pic).

Jamie Hall

Oy. You need to find out — somehow — exactly what was plugged and where. The storm water must still be going somewhere, and you need to know where it is going and how it is getting there from your property. Then you also need to find out how the sanitary waste water leaves your property and how it is getting there.

"Plugged" is not a term I would expect to see. Redirected, yes. The "plug" may have been to disconnect the storm drain system on your property from the sanitary drain system on your property and redirect that storm water to a new storm sewer.

But you would do well to figure out what was done and where the water is going before you start either capping or opening pipes.

Intplm.

Then yes. Go for it. I would do all I can to get the correct size. They can get very big in volume and pricey. Some have redirected the storm water completely to the out doors so no storm water enters the building. And at times can be a better job for less $$.

Intplm.

Are you discontinuing the storm drain at the trap and replacing the storm drainage with the sump pump?

Jamie Hall

OK. Sanitary has been redirected.

Now. Figure out where the storm water is coming from, then figure out where it is going now and how it gets there, then figure out how much storm water is involved. If the storm water is going through that trap, and it is from roof leaders or yard drains (not just seeping into the basement), you may find that the peak flows you need to handle are… impressively high (the roof leaders from a 1,000 square foot house in your area will be on the order of 70 gallons per minute design flow, for instance).

DeltaFox

So,"plugged" meaning the city did something in the mid 70s such that all residential storm drains were prevented from flowing into the street storm drain system. I assume that during this time the homeowners also untied the storm drains from the residential storm water collection system (i.e. gutters), as there was no longer an exit at the other end.

Fast forward to today, I have an out of service drain system that I want to cut out and throw into the pits of hell.

What I don't know is if (1) the old rain water drain system is completely separate from my sewer main or (2) the mid century engineering pioneers tied the storm drain into my main sewer line. The sewer / storm drains are identical pipes and colocated together. I originally thought it was a 4-way. Now it looks as if it's two abutted Y's.

If 2 is true, I'd essentially be cutting into a main sewer line - not my first choice. The cast iron is covered in sediment and it's hard to tell what the f is happening from inside. On the outside it appears 1 is true, at least for the first two feet.

The storm drains are not causing the basement water. The sump project has has nothing to do with the storm water drains, other than they happen to be in the way of where I want my sump pump basin located.

Jamie Hall

First, the sanitary sewer lines in your house should be connected to the sanitary sewer in the street. Second, the storm sewer lines in your house, if there are any, should be connected to the storm sewer line in the street.

At a time — probably in the 70s — an effort was made to locate all storm sewer connections to the sanitary sewer lines in the area and disconnect them and reconnect them to new storm sewer lines, or redirect them to the street (rare).

The alterations did NOT mean that residential storm drains were prevented from feeding into the street storm drains. It DID mean that they no longer fed into the street sanitary drains which had been common practice up to that time.

Now. You say that you have an out of service storm drain system. Maybe. If that is true, I strongly advise you to determine where the storm water from your property actually goes. Believe me, it goes somewhere, and before you start cutting pipes you had better know where.

What did NOT happen was that your storm drains got cut into your sanitary drain. It was illegal when we were separating the systems and it still is illegal, and the MDC takes an exceedingly dim view of any such thing.

DeltaFox

@Jamie Hall

Any chance the water in the street storm drains is moving upstream along my drains and into my basement?

At the end of the day, I have a freakish amount of water coming into my basement relative to my neighbors. My sump pump turns on every 15-30 minutes (with the stock float and sump sitting at the bottom of a ~30 in basin). If the sump is unplugged or malfunctioning for ~8 hours, water overflows from the basin. In 12-16 hours, I have 4 inches of water. This enigma keeps me up at night (tonight, for example).

.

Jamie Hall

Very little chance. The street storm drains, in dry weather, should have very little water in them (you can go look at a catch basin to see!). In we weather, still unlikely, although there is always the odd chance of a blockage.

If your water in the basement problem is more or less constant — not related much to rainfall — you may have a problem with the foundation drains for your house (if it's related to rainfall, it may still be that — or your roof leaders). Do you have any idea where they go, or even if you have them? Foundation drains should NOT go into the storm drain system.

Intplm.

https://forum.heatinghelp.com/discussion/comment/1834607#Comment_1834607

And you could also have a high water table.