backflow valve but still flooding

[s1156780]

I live in Cicero. We had a double check backflow valve that has a manual option as well installed in spring of 2010; however, that has not quit the flooding of the basement. We have a catch basin in the rear of the home and it appears that the catch basin fills up and causes water to come in through the floor drains. What kind of options do we have outside of installing an overhead system that will prevent the basement from getting water?

 

[Jadnashua]

You could put in a a basin and a pump. Make sure that the pumped outlet goes high enough so that when the sewer backs up that is higher than the next higher outlet. Pumps are not without their own problems, though (like maintenance, and they don't work in a power outage), not counting the cost to install and the energy consumption when they do need to run. It's not uncommon for a check valve to not seal perfectly every time. Gravity, though should work every time. Depending on where you live, your loop might have to be so high, that won't work.

If your city has not separated their storm and waste sewers, a bad rainstorm can often overwhelm them. The results can be really messy.

 

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[hj]

It makes no difference how high the pump discharge is, as long is it has the required check valve in the discharge line. If the grease interceptor/catch basin is connected to the floor drains and is also connected to the sewer outside the basement, then it is bypassing the backwater valve making it completely ineffective. I would have to see your installation to determine how difficult it would be to convert the system to an overhead sewer, which is the ONLY positive way to prevent flooding, since either a slide valve or backwater valve can fail.

 

[Jadnashua]

A backwater valve like a check valve can fail to seal...if the outlet of the pumped system goes high enough before going down to the sewer, even with a failed or stuck valve, it shouldn't back up into the house - it will overflow somewhere else that is lower. A checkvalve on a pumped system gets exercised frequently, and may not fail as often as a backwater valve, but it can still happen.

 

[hj]

If the pump is working, it will eject any "backflow" even if the check valve is defective. If the power is off, then the basement is "doomed" regardless of how the water gets in.

 

[s1156780]

It makes no difference how high the pump discharge is, as long is it has the required check valve in the discharge line. If the grease interceptor/catch basin is connected to the floor drains and is also connected to the sewer outside the basement, then it is bypassing the backwater valve making it completely ineffective. I would have to see your installation to determine how difficult it would be to convert the system to an overhead sewer, which is the ONLY positive way to prevent flooding, since either a slide valve or backwater valve can fail.

thank you for your help although it is disappointing to hear there is not much that can b done outside of an overhead system, but could you explain how it is bypassing the check valve; although that is what we thought may be happening.

 

[hj]

Baackwater valves, except when new, seldom have a good seal. In fact, once they get older, they can cause more backups than they prevent. 50 years ago, there was a company in Chicago that made an excellent combination backwater/pump system that overcame all the issues of pumps and leaking backwater valves. It installed in the sewer in place of the conventional backwater valve. I used to go there and get them, but cannot remember the name or if they are still in business.