Although you can have a system designed using that paperwork, you should definitely have that looked at again. We will do a FREE in office review of the paperwork and our files to see if it looks like there are other potential alternatives available or wheter it would be worthwhile to reevaluate the lot. When we do a preliminary evaluation for subdivision lots there are alot of unknowns and contraints that sometimes lead to overkill in the recommendations we make at that stage. It's only after the lots are finalized and house sites identified that a comprehensive evaluation specific to your plans can be performed. This is especially true on large lots with multiple potential house sites or sites in remote locations.
I'll give you an example. A develpor puts a contract on a large undivided tract of land to develop into a large lot subdivision. He (or she) is signing up to spend a lot of money on surveys, roadbuilding, marketing, etc. But first they usually have to obtain local government approval, part of which is showing that all the proposed tracts in the subdivision will support some kind of septic system. The tract is wooded and remote with limited access to established roads and the subdivision roads won't even get built until all the approvals are in place. So the developer hires SETEC to make sure all the proposed lots have a specific place where a septic system can be approved. (Usually, the developer has already had us go out and do a soils map of the property to make sure there are enough suitable soils to even consider the development.)
So here we go, hand auger in hand, to evaluate lots that often aren't even flagged in the field yet. The lots are large and there are plenty of nice places to build a house once people can get back in there but the soils on a particular lot (or several) are stony and we can only auger a couple of feet deep. Although it's a place where we could maybe get a conventional drainfield (if we could bring in more appropriate equipment) , we have to identify a site so the developer can move forward, so we recommend a system that will work for the level of evaluation were able to accomplish, a drip system.
A couple of years later, there are roads into the property, the lot lines are flagged, and a potential homebuilder has picked a site different than that we originally picked. You can see how that original evaluation, although still valid, may not be the best solution for your particular situation.
Now is the time for a comprehensive evaluation to tailor a solution that will work specifically for you. Often all it takes is using a backhoe to dig the holes to go from a $20,000 dollar system to a $5,000 conventional one. I can't promise you still won't need that drip system, but you won't go away wondering either.