Backyard flooding--city sewer the culprit?
We renovated our townhouse two years ago, including the backyard. Before the renovation, most of the yard was concrete with a dry well that never drained properly. We replaced the concrete and dry well with plantings that are graded towards the building. We installed a bluestone patio (approx. 20′ square) adjacent to the building with a french drain that connects to the sanitary line, which in turn drains into the city sewer.
Now, whenever we have heavy rainfall (>2 inches), the patio floods 3-4 inches deep. A couple hours after the rain stops it will drain. Meanwhile, the neighbor’s yard, which has the same concrete/dry well configuration we used to have, has a large puddle that takes a day or so to drain, but not the pond we get. (I’ve had our line checked several times for blockages.)
Could it be that the overflow from the city sewer is coming up through our wastepipe into the drain on the patio? Given the lack of flooding on either side of us, I am at a loss for any other explanation as to where all this water is coming from. Any ideas?
Thank you!
ixmfrteyhywobz
in General Discussion 4 years ago
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6 replies
lkrshacmzcy | 4 years ago
You would need to get more information on your Sewer and Drains. As discussed, I would hire a professional to get the sewer camera and the drain line connections better identified.
lkrshacmzcy | 4 years ago
You would need to get more information on your Sewer and Drains. As discussed, I would hire a professional to get the sewer camera and the drain line connections better identified.
randolph | 4 years ago
> @obadiahslope
> We replaced the concrete and dry well with plantings that are graded towards the building.
oops
ixmfrteyhywobz | 4 years ago
Thanks, Dork, lots of good ideas.
Yes, we are near 5th Avenue on the Slope.
The reason we pitched towards the house is because we wanted the runoff to drain into the sewer, as opposed to relying on the dry well, which was located more towards the middle of the yard and took forever to drain. (We’ve had the house for over 20 years, longer than the neighbors.)
dorkofwindsor | 4 years ago
A more likely scenario is the rain coming off the roof and down your downspout is backing up into your backyard drain as the city sewer runs full. A relatively common occurrence. There may indeed be a valid reason drywells were installed, even if inadequate. Are you located near the bottom of the Slope or Gowanus?
Having said that, a couple hours after the rain stops for your yard to drain into the city sewer is far too long. Should be 5-10 minutes max. Simulating the event by blocking the drain and flooding your patio on a nice day may help diagnose the problem. Could be some kind of venting issue for whatever reason…. or there is a serious design flaw in the plumbing from whoever developed your houses 100 years ago……OR a serious problem with the city sewer in your neighborhood. The previous owner and neighbor all went to great lengths to install dry wells.
Do you notice any sputtering or gurgling when the yard drain is draining? Venting a yard drain is not normal, but its all I can think of. Many of our houses are idiosyncratic beasts and things have been done to them that are questionable. A camera inspection from the rear of your house where the sewer / leader / yard drain connections happen could be in order.
Aside from that, I would call in a new master plumber. A top notch local MP that would know if your street sewer has issues or the houses by that developer does etc.
You have pitched everything towards the house and rely heavily on the physical trench drain, so I would solicit as many opinions as possible, including talking to your neighbors – particularly the old timers.
agdipierro
in General Discussion 4 years ago
Perhaps I misread the third sentence “pitched plantings toward building.” Always pitch away from the building.