This is the Bonus cache for the "Walnut Creek Ranches and Homesteads" Adventure Lab. The final is located at one of the lab stages.
After completely the 5 stages of the "Walnut Creek Ranches and Homesteads" adventure lab, note the codes found in the 5 journal entries, Enter in the codes to solve for:
N37 54. AB W122 02.CDE
Enter the full coordinates into the Checker.