I have a boulder/rock that is about 2 feet long and 1.5 feet in diameter. It is too heavy to lift and I would like to break it into smaller pieces. Without power tools, are there any good methods besides going at it with a sledgehammer?
How to break up a small boulder without power tools
landscapingremovalrocktechnique
Related Solutions
How old is the house? If it's fairly recent, do you have any idea of what the property was like before being built on? It's possible that the builder put down a lot of fill, and there was a large amount of organic material in that fill, or that he just dumped fill on top of what was there - stumps, trees, etc. Depending on the composition of the fill used, you might be able to get away with just dumping earth or sand into the hole, but it sounds like a large area - which means that digging it up, removing the rotting organic material, and replacing it with fresh fill is really the only way to permanently fix it.
You might want to get a local plumber to come out and "scope" the hole to see if you can tell whether or not this really is your problem.
Option #1:
Find a few objects (house, trees, etc.) that, together, allow at least one of them to be level line-of sight from anywhere in the yard.
Tape a laser pointer on the end of a level (taped so you can use the level as a sort of monopod resting on the ground).
Move around the yard, hold the level level, and point the laser at one of the objects. 3a. Have someone at the object use a measuring tape to record the measurement. 3b. Subtract the length of your level.
Once you have all of your measurements, figure out the elevation offsets of the objects in relation to one another and offset measurements against them accordingly.
For example, in this diagram from Practical Engineering's YouTube on land-surveying, the human can be replaced with a level with a laser-pointer on the top. Then "measured height" is the measurement at your object (step 3a); the "eye line height" is the height of your spirit-level (step 3b); subtract the spirit-level from your measured height to get the the "relative height" (step 4)
Option #2:
Use a photogrammetry program like PhotoModeler (http://www.photomodeler.com/) to combine photographs taken using a tripod and a digital camera from different vantage points. Of course, these apps are incredibly expensive, probably cost more than the gadgets you mentioned. Unless you happen to already own a license to one of the AutoCAD products that gives you access to AutoDesk's photogrammetry app, ImageModeler 2009 (http://usa.autodesk.com/adsk/servlet/pc/index?id=11390028&siteID=123112).
Best Answer
You can go at it with a sledgehammer (or a smaller hand sledge) and a star drill, and then drive wedges into the holes (or if you are patient, fill the holes with water and let them freeze in the winter.) There are special wedges designed for use in round holes for splitting rock (feathers and wedges seems to find them). https://en.wikipedia.org/wiki/Plug_and_feather
Remember to use ear and eye protection.
Another approach from our practical forebears if you just need it out of the way would be to dig a hole 2-1/2 feet long, 2 feet wide and 3 feet deep next to it, then roll it in and bury it.
You could also build a bonfire on or around it, but that has some potential to become more exciting than planned for if the stone has trapped water in it.