D. I'd like to think the reason nobody is helping you is because there is no good answer. I would expect you need many test holes, and your question as posed in the last sentence mentions only one test hole. It could be consistant or it could be the only one like it.

The more test holes the better. Also, the neighbors poorly built pond that works could be a good sign.

Good luck.

Robinson, PI (Politically Incorrect, of Course)