Ann, if the leak is on one corner, I would want to know why it leaks just there. Do you have a ponding situation there? Do you need gutters or do you have a down spout there?
It leaks, of course, because of some reason the water is hanging on in that spot, you need to move it away.
In answer to your question, it seems to be a combination of several professions. I would start with a Irrigation Service that deals with drains and speciality situations like yours.
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