No worms in the tank, they need to breath, worms are only useful to aerate the soil.
The tank still needs to be pumped out every 5 years or so depending on your family size. Pump the tank when the sludge level gets too high. Another reason you need risers on your tank. http://www.septicsolutions.net/store/risers_lids.htm
Is you land flat or on a slope? If it is flat, then you have only one D-Box that you can dig up and add a riser to. Then you can rent a pressure pump and jet your own laterals. If your land is on a slope, then you have multiple D-Boxes, at each lateral.
If they force you into a new system, make sure it has risers at every D-Box & for the tank. It must be serviceable.