I spent some time at the end of 2015 locating benchmarks to qualify for several challenges on Galveston Island. Benchmarks are like virtuals -- no containers to find, no logs to sign -- but with the added challenge of coordinates taken with less accurate measuring tools, or based on older geospatial reference systems. Like caches, they can become obscured, or removed over time. Many of the benchmarks are brass disks attached to concrete in the ground, or to bridge overpasses, or even to public buildings like courthouses. geocaching.com has a database of benchmarks placed around the country.
I've come across other similar benchmark disks, but not all of them are in the geocaching database. Some are too new to have been included, while others may have been put out by municipalities.
The City of Cedar Park also has benchmarks placed around the city. This cache takes you to one of them, located at the posted coordinates. To find the cache container, take the number that is stamped on the disk, and multiply that number by 28.54829 to obtain the distance in meters. Also multiply that same number by 6.23195 to obtain the bearing. Then, using those values, project from the posted coordinates to locate the cache container.
Be prepared and bring a writing utensil. Also, it should go without saying that one should not post a picture of the actual benchmark disk. Doing so will cause the log to be deleted.
You can validate your puzzle solution with certitude.