SCEngr1
Thanks for the clarification.
1.5"-2" of ACP on "clay" is not a good construction practice for starters. Depending on the P.I. (plasticity index) of the clay (how suseptable to expansion and contraction) would have a bearing on the best way to remedy the situation. We would not want to overlay with neither conc. or new ACP if the subgrade is ca-ca.
We have tried the "roto mill" option in a parking lot with not so good results, we used some "rejuvinator" as well. Our loads were probably more than yours, but it sounds like we had better subgrade.
I am guessing the "TOP SEAL" is a chip seal or Seal Coat?
A seal coat (hot liquid asphalt sprayed at 300+ degrees with aggregate sprinkled and rolled behind the distributor) is good in that it "seals out moisture and provides (in some cases) good skid qualities. However, in a parking lot with lots of turning movements.....I would not recommend it. (just my opinion) Lots of variability in this type of operation. Very weather, materials, equipment and skill dependant. It could get gooey for people afoot if it is not done correctly.
So you are tied elavation-wise.
OPTION 1----cheap--------
You could saw out the chuckholes to neat lines, patch with 3-4 inches of ACP (dense-graded hotmix), and overlay the entire mat with 2-3 inches with the same ACP...at the grade tie-ins (C&G?) could you can taper down to tie in?
OPTION 2----not so cheap
1. Rotomill or "mix" the existing ACP with the subgrade to a depth of 8-10 inches.
2. Depending on your clay P.I., calculate 3-5% @ 8-10 inches deep of LIME (I like quicklime, but you could use slurry or powder)re-mix the subgrade ( ACP, clay, and lime) adding the required moisture content (enough to activate the lime) mix until you have an acceptable gradation, then compact (with a compactor) and finish to drain.
3. Place 2" of dense graded ACP.
I know this sounds like lots of $$$$, but if it is done correctly it is cheaper than adding a good aggregate sub-base.
If water stands on the parking lot now (minus the chuck holes) you need to re-construct/grade it to drain. Water standing on ACP is not good, especially in high traffic areas.
Hope this helps.