After clearing all the weed around the lids I have following findings..
1. There are 4 lids/chambers for this septic tank system (not 3!)
2. First lid seems to be an inspection chamber sort as shown in
first Image below. Water just flows via this.I can't see any difficulty in water flow, I suppose thats a good sign..?
3. Between chamber 2 above and actual septic tank there is small round hole may be 15cm diameter. see
2nd Image below. This is made of red brick (clay) material. I measured depth using stick into this only. I can say no smell I could get when I opened this chamber and can see some water down.
4. 3 & 4 lids covers side by side equal sized chambers paved with bricks. chamber 3 got solid waste and still didn't smell anything!! I didn't had courage to put a stick in this
5. Chamber 4 is same size as 3 but this got cloudy water in it, no solid waste
6. Both above chambers are 60% filled I think
7. when emptying waste is that done on solid chamber waste only..? or liquid chamber as well?
8. Solid chamber volume seems to be as shown in last image, but its not in 1000's of gallon as the companies were asking me..? Is this volume calculation wrong?