Seepage Pit Issue; Back out or not?

[Jerome Morelos]

I'm in a “sticky” situation where I could potentially lose my earnest money (5k) due to me potentially backing out of the deal.

I’m in contract on my first owner-occupied property that was listed as “public sewer” but we come to find out it was on “septic”,  which the sellers were able to get inspected right before the 10 day inspection contingency expired. We requested the inspection report but the seller’s agent dragged their feet and took a while to send it. With the inspection contingency expiring, we finally received it and come to find out it also has a "seepage pit" that's 90% full and needed replacement. This was not disclosed at all by the seller.  

A Septic company quoted me 8k to replace the seepage pit. I'm not sure if they're just trying to make money off me. I'm looking to get a second opinion, pay out of pocket again for another inspection, and hopefully it's not a big problem to where it needs replacement. The septic tank, however, did not need any repairs.

What's keeping me in the deal is that it's in a great location with high rental demand. It also appraised for $34k higher than my purchase price.

 Anyone have any experience with "seepage pits?"