It is official. Water is coming from that hole in the dirt. Water flow returned this morning with a typical 1.5" to 2" of rain in about 6 hours, whereas in the past 4" of rain over 2-3 days wouldn't even bring anything into the crawlspace at all. The water flow stopped for months after I filled in the old concrete septic tank (I calculated that it could hold about 1,000 gallons) that I found about 10 feet from the back of the house. It is approximately in line with this said hole in the crawlspace dirt. Had a considerable flow of water today and the pump still triggers once every couple of hours. My previous assumptions were wrong. The photos are deceiving. This hole in the dirt behind the retaining wall is about 2 feet down at most from the top of the wall.
http://oi63.tinypic.com/2gy21aq.jpg
It appears to me that water flows in from the hole at the corner and disperses within the hollow cinderblocks of the wall all the way around, then starts coming out everywhere. That's a new problem, because it isn't at the base of the wall like I had originally thought. Containing the wall with dimple board on the inside all the way around and about 2.5 feet of grave with a 3" to 5" layer of concrete on top still wouldn't stop this source hole that would be above that point. I still have plans to flip the furnace and possibly switch the water heater to an indoor on-demand. However, I wanted to see if the water would come back. It has.
I'm quite puzzled. How is this coming from a filled old septic tank? I dug all around that area outside of the house and nothing else was found there.
Around the top of the sump hole, I noted this singular place where a stream of water about as thick as a pencil was spraying out of the concrete of the floor around the top of the makeshift hole:
http://oi64.tinypic.com/28lx46v.jpg
It wasn't hitting anything upon spraying out, but was "bending/twisting" as it flowed, as if against gravity. That must have been under some force to be curving around that much. Possible springs or just the water running from inside of the wall and under the ground finding a spot that was open in the concrete? It looks just like some of the videos of the water table shooting up out of concrete like I have seen in a lot of people's basements.
I could throw some drainage gravel behind that wall and cement over it with a thick layer of concrete on top of the gravel to keep the dirt from eroding out of the old tank and coming through that hole. That's a concern. If that is in fact where it is still coming from. I can't figure out how to "stop" the water, however. If I plugged the dirt hole, it really would just find another path around whatever I plugged it with. Plus, I can't follow it all the way to the source. At this point, however...I've pondered renting one of those inspection cameras from a home improvement store and scoping that hole to see where it leads. If it leads to the old septic tank, I would imagine that it would be open all the way to the wall where the water is flowing from. Not sure if that would be worth the money, but...this is a pretty odd problem.
I also used to think that the back wall behind the water heater was the problem. That IS where the water seems to be coming from out of the hole in the dirt. However, it apparently doesn't flow out of that back base part of the wall until much later. I now know that's a good 1 to 1.5 feet below the water hole. It was bone dry when I checked it, while the other parts of the wall had lots of water coming out of them. So that leads me to believe even more that water doesn't start coming out of the back of the wall until it builds up everywhere else around the rest of the wall and has nowhere else to go.
Thinking about one of these:
http://www6.homedepot.com/tool-truck-rental/Drain_Camera/CGPF_ECAM-ACE/index.html
Its $137 for 4 hours and $195 per day. I'm also wondering if any of the rocks in the dirt would pose a scratch hazard to the camera, as I do not want to buy a $5,000+ camera. It is obviously meant for pipes that would be easy to slide along in and be consistently smooth. Anyone know how tough they make these things to be? Will I scratch the lens on the jagged rocks pushing it through this hole?
At the end of the day, I'm thinking of just having that furnace flipped and hung from the floor, the tanked gas water heater converted to tankless indoor and mounted in the crawlspace somewhere...and just gravel the whole freaking thing to the top of the wall. Concrete over the gravel with about 5 inches of concrete across the top, install a sump basin in the gravel below the concrete and call it a day. Thoughts?