I would go do a 2' X 2' test area. See how long it takes you. Then I would measure the total square footage. 2 (10,480 ft approx.) miles X 12' wide = 125,760 sq ft. Say it takes you 10 minutes to clean (hopefully it doesn't take you that long) the 2' X 2' section = 4 square feet. 125760 divided by 4 = 31460 of the 2' X 2' sections. 31460 minutes total 524 total hours X $95 per hour = $49,780.
Now if you were in Southern California then there would be the lowballing hack that would come in with a price of $10,000 to do the job.
I normally don't bid on city, state or county jobs for the simple fact that I'm usually in the middle of 1 of the highest.