Ways To Keep The Water Out

The sun is shining today after a few big storms in NYC this week, with some pockets of flooding around the city…

But it was much heavier (and deadly) slightly north of us in Connecticut…

As we all learn how to live with more water, people are sharing their flooding stories with The City Sponge. Some of these we will write-up so you can see how situations and solutions vary. Maybe one will work for you. Or maybe you have an experience to share. This way we can help each other.

Here are two stories - one from Queens, one from Brooklyn - of two homeowners who have been busy preparing for more water and potential sewer back flows in their basements.

Story 1: Queens: Make Room For Two New Valves

When the “10 year storm” began to show up every few months, Michael knew his Queens home needed a stronger approach to prevent flooding.

The solution chosen:

• An automatic “flood gate knife valve” which can cut through any debris that might get stuck in the pipe.

• It uses a bellows approach which is lifted by water pressure and does not require a person closing it, nor any electricity to operate.

• The sewer access pit was made larger (twice) to install the valve in the optimal spot, but was arduous dusty work chopping into foot-thick concrete.

How this flood gate valve works:

• On a regular day and lacking any upward force, the gate is in the open position, which allows for unrestricted flow through the opening.

• But when sewer water backs up and pushes up, that force pulls the blade up which seals the pipe and blocks the flow.

• Flood gate valve video here, and brochure on this specific model here

BUT…there was a challenge:

A design complication arose because the house used a combined storm and sewer line which was inside the basement. So he had two potential flood sources to deal with: 1) the city sewer and 2) the house stormwater/wastewater line. The two water flows were hitting each other in his basement, but closing one doesn’t solve for the other.

A few postcards from his journey…

Once the “flood gate knife valve” was in, Michael realized he needed a way to better manage the combined storm and sewer line inside the house. 

So he decided to expand the sewer pit further and make it a three part system:

1. on the city sewer connection, he added an additional “passive flapper check valve”

2. on the house sewer line, he used the “knife gate valve” which would prevent stormwater from hitting a closed city sewer connection

3. any overflow from stormwater would be routed to move up a fresh air inlet to the front yard drain where there is a sump pump

This approach isolated the city sewer connection while still having a “mostly-good” back flow solution for the house combined stormwater and sewer line. Said Michael: “I wish I had known all this from the get go, since it involved a second plumber visit and chopping out even more concrete.”

Accessories for sewer pits? Yes those exist.  

Because Michael now had an unusual shaped sewer pit close to his basement doorway and needed to walk on it, he ended up creating a custom-cut 1/4" thick steel lid, cut and delivered from RapidSteel in Queens (who he recommends).

In addition, he also wanted to know IF AND WHEN the knife gate valve was activated. For that, instead of buying a $700 accessory sold by the valve company, he was able to find and build a generic system for $100 (but he is good with tech). He actually connected it to his Ring home security system and recommends Automationdirect.com for things needed there.

Michael wrote up his journey here: https://medium.com/@MonkeyBonkey/the-journey-to-storm-overflow-proofing-my-new-york-city-brownstone-18f360287fac 

 🧽 We hope that does the trick for you, Michael! Thank you for sharing your story.

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Story 2: Brooklyn: Dry Well Stacks and New Valve

This story is about Steve - an architect - who took many years to carefully restore and rebuild his old place in Brooklyn. In this house, there was a lot of work done, a lot of attention to detail.

Now he is selling it and…it’s an amazing house. This place is so nice it has articles written about it, like the one below:

But what caught the eye of a City Sponge reader was a line about the approach to flood mitigation:

We asked Steve if we could see it and he was cool enough to say yes.

Given the investment put into the house, I expected something really fancy and high-tech. In fact, it wasn’t really expensive, but pretty simple and leveraging natural forces at the core.

The solution chosen:

• On the outside for stormwater, he stacked three smaller dry wells on top of each other creating 4 columns, and buried a stack near each corner of the house.

• These 12 dry wells can handle thousands gallons of downspout runoff, keeping it away from the sewer connection, away from the house, but more importantly - he dug them to channel the water 6-7 feet deep, far BELOW the top soil and even BELOW the layer of clay (which is less absorbent). So using gravity and permeable sediment layers.

• And inside, he installed a new “swing check valve” at the sewer connection. So the force of back flow sewer water would close the valve.

These were the 50 gallon dry-wells he stacked up.

> Here is a helpful calculator from the maker of these dry wells (NDS) to help you figure out how much drainage (dry wells) you need based on your building but ALSO the types of space for drainage: https://www.ndspro.com/tools-and-calculators/flo-well-calculator

At each corner of the house, a 6-7 foot hole was dug and the wells were set 1' below grade, with the downspouts connected to each stack.

Steve knew the depth of the clay from prior projects and after reading book written by his former neighbor called My Empire of Dirt. 

> Intro to My Empire of Dirt: “For seven months, Manny Howard—a lifelong urbanite—woke up every morning and ventured into his eight-hundred-square-foot backyard to maintain the first farm in Flatbush, Brooklyn, in generations. His goal was simple: to subsist on what he could produce on this farm, and only this farm, for at least a month.” 

Inside, Steve installed the chosen valve, which he was able to show us and easily access by removing a few carpet tiles, a bit of wood moulding and then a floor panel that fit snugly but was NOT attached nails or screws.

He chose a “swing check valve” with the door hinged at the top of the outlet in the service chamber.

He liked this type of valve because:

1. it’s a simple mechanism

2. doesn't require electrical power to operate which may not be available during a storm

3. the hinge is at the top of the waste pipe so debris is less likely to get caught on it

One suggestion he mentioned is that the swing door needs to be inspected periodically, and an owner must be careful not to let a sewer cleaning contractor try to clear the yard's sewer line from inside the house. “If the snake isn't placed in the waste line downstream from the check valve door, it will ruin the hinge,” said Steve.

Like many emergency valve systems, if and when the swing valve is closed due to sewer black flow, then any interior waste water from the house will just have to wait for the sewer blockage to dissipate and the valve to re-open…which he estimates as “usually less than an hour.”

That said, there is a 6" lateral pipe under the cellar floor can handle and store 150 gallons of waste, and it’s not under pressure like the water from a roof would be, so it’s not a problem.  But he added, any hi-volume waste water uses - like long showers, multiple toilet flushes - should be avoided if valve is closed.

And honestly, that is something we all should avoid doing during storms to help ourselves and our neighbors; we share the sewer and we share the water.

🧽  A well-designed approach. Thank you for sharing, Steve!

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