Sorry I was not around for start up. The cores would let you know what your foundation and catchment are laying upon. But they might run right into a rock. Also you could fine tune your compaction practices. It is well advised to drain it back and give it a very close inspection. That limestone and verticle water movement combination concerns me. You know when you drain it you can also do some cores. It is not too late. Maybe pay some unemployed geologist to take a look. It could answer a lot of questions.
