About 2 exits east of the Junction City, KS exit on I-70 is highway 177. Go south on 177 about 25 miles to the Council Grove, KS ACOE Campgrounds. There are 3 entrances off 177; Richey Cove, Kit Carson Cove Park and Kansa View Park.
Have lunch or dinner at Hays House, downtown Council Grove. As best I know, there are over 20 historic landmarks in that little town. Very quaint and we liked it a lot.
You'd be smart to Google better directions.
Enjoy your adventure and be safe (there are a lot of crazies on the roads).