Most septic lids are buried and need to be excavated or uncovered prior to pumping. Usually they are less then three feet deep, however if you have a basement in your home they can be much deeper. There are companies out there that can locate your septic lid for you and even excavate it, but they do charge. The cost can vary depending on what exactly you need from a couple hundred dollars to a couple thousand. Luckily there is a free resource that can help you locate your own septic tank and septic lid. Your local county health department should have record of where your septic system is and can provide that information to you with quick phone call.
Salt Lake County https://slco.org/health/ 801-468-4100
Utah County http://www.utahcountyonline.org/Dept2/Health/index.asp 801-851-7525
Weber-Morgan County http://www.webermorganhealth.org/ 801-399-7160
Summit County https://summitcountyhealth.org/ 435-333-1511
Wasatch County http://www.wasatchcountyhd.org/ 435-654-2700
Davis County http://www.daviscountyutah.gov/health/health-department 801-525-5100
Tooele County http://tooelehealth.org/ 435-277-2300
You can also verify with the county health departments that whatever pumper you decide to higher is licensed in that county. That way you know you are dealing with a professional.