Concrete integrity? My church asked me to take a look at the vault for...

My church asked me to take a look at the vault for them because it was flooding. I temporarily took comfort of the flooding problem by extending the gutter further from the building, but I became more concerned near something I found in the subterranean vault. There is a crack in the concrete foundation, and I did a tack hammer tap trial on it, and there be a clear difference indicating a void around the crack (more than imagined, the water be coming from here). I am concerned for the structural integrity of the concrete. There was a discouraging sinkhole not far from this crack about 10 years ago, and the church have a very big ceiling with a slate roof, and because of this, the wall on the side where on earth the crack is bows out. The crack is lateral, is fairly long (about 2.5 feet), nearly 1/2 an inch thick, and it is surrounded by a spot where the wall juts out, and it go around the corner, but the corner is blocked off, and I cannot see how it looks on the other side. The church is intensely old (built around 1900).
How do i bring back it out of...
Answers:    contact me directly via email and let discuss. I'll try to help.
I enjoy a john Lewis ceiling table lamp...
you may want to look into it further. if it isn't a problem next you will just be down a few bucks to hire an inspector, compared to the cost if something happen.