When it rains, it pours - Checkvalve Maintance

Got flooded during Irene, had checkvalve installed.
Got flooded during Sandy - post recuperation, I opened up the access door to find that a piece of turd had kept the door from properly closing..
The turd was literally stuck to the door edge...
(I believe part of the issue is design. The door is a cast iron flapper. I suspect running water constant after turd flushes might have prevented this problem). As a maintenance post sandy, I have occasionally filled up both tubs, and all sinks and drain them all at it - sorta like a turbulence of water to free up anything if it was stuck to the checkvalve door

Fast forward today. Heavy rains. Flash flooding alerts off go off on the iPhone....
And lo and behold, I get some backup coming through.

I've yet to get to the access door and see what's going in.
We'll let the rain simmer for now


Just short of opening up the check valve access door 1X a month, what do you guys suggest as a next step.
A Ball Valve right behind the check valve that will allow me to manually close the pipe .

You can check the valve once a month, but there is nothing to stop a toothpick, or anything else, from lodging on the seat IMMEDIATELY after you close it up again. That is the "deficiency" of a back water valve. All you can hope for is that it slows the flooding down until the city sewer can operate normally again. A 4" ball valve" can be very difficult to operate after a couple of years. A "shear gate valve", (many are combination in with a back water valve), designed for a sewer system is a better option, assuming you are home when the flooding occurs.