If your property lies within an area designated as the Casper Aquifer Protection Zone (CAPZ), any septic field that is to be installed in that area will have to be designed by a Professional Engineer or a Professional Geologist, licensed to practice in Wyoming and qualified to do such work. An electrical engineer, for example, may not have the requisite skills for this undertaking.  The engineer/geologist should contact the County Water and Wastewater Engineer for guidance regarding what will be expected.