Has anyone had a clogged parking lot drain?

[Jonathan Stone]

Hey BP,

I'm hoping someone has experience in fixing clogged parking lot drains.  I bought 2 4 unit properties that share a parking lot and at the time I bought it I didn't realize that the drain was clogged.  Apparently this is something the seller didn't mention and I did not know to check for it.  

My PM sent a plumber down to evaluate it and they estimated the job would cost a minimum of $650 but didn't give me a price ceiling.  So I asked the PM to send one of their guys down to dig out he drain at a rate of $45 per hour. He spent about an hour digging and uncovered all types of trash and debris but after 6-8 inches he wasnt able to dig any further.  Whatever is down there appears to have compacted so tightly that it felt like he was digging rock.

I am hoping that someone on BP has had this problem before and can share what they did and how much they spent to rectify the problem.  My tenants are tired of walking through a lake to get to their cars everytime it rains and I want to explore options for fixing this before going with the plumber and literally throwing money down the drain. 

Thanks in advance for your help!