Help - Lilly Miller Noxall seeped into lawn

I applied Lilly Miller Noxall in a rock bed and an area that we don't want any vegetation growing... However we have had lots of rain and the noxall has seeped into the lawn... Of course now it is killing the grass.
I called Lilly Miller customer service and they said I will not have vegetation for a full year.. even if I dig out the soil...

Q: how can I remedy this? I find it hard to believe that I can't dig out the soil in the affected area and re-seed / sod... Will you please...

Help - Lilly Miller Noxall seeped into lawn