Best Gravity Septic System Installation in Seattle WA

I'm sure they do great work, but that was not my experience. A tech came out and poked deep holes in my yard then claimed he needs to use heavy machinery because my septic tank is 4 foot deep. I got an estimate the next day for over 2k. I called another company out and they found my septic tank within minutes using the county posted diagram that this company also had. My tank lid was 10 inches deep. They were wanting to tear up my front yard and over charge me for it. Shame on this company