I am late as usual
...anyway you are way north of me so, basically I can't help you.
However, I was at my parents house when their toilet overflowed as well as the sinks and bathtubs. I just opened the yellow pages and picked a company that would come out that night and give a free estimate.
It worked out real good. I had the as built and already knew where the tanks were. So, I did use that company the following day. The septic guys tried to tell me that there was a filter and I said ....no there isn't. They said "yes, there is" and I said wanna bet? So, we betted an hours time of digging at $80.00 per hour. There was no filter, so they subtracted that charge from the bill.