30" is the prescribed depth for water lines by City Building Department. However, with all things engineering, this is not an absolute answer. This depth is most likely based on a 50 year probability of reoccurance. So frost may go lower but it does not happen often and it probably would not be much lower than 30".
The missouri river averages 75 ft deep, and its deepest point is only 100 ft deep.35 ft deep
Deep River - 2009 was released on: USA: 1 May 2009 (Kansas City, Missouri)
32"
The last question on the attached link. http://extension.missouri.edu/xplor/qa/agriculturalengineering0001.htm
no Frost
The frost line in the city of Chicago is thought to be 36 inches. The average Chicago winter does not exceed the 36 inch frost line, but extremely cold winters can.
In the City of Pittsburgh, PA, the frost line typically ranges from 36-42 inches deep. This depth is the point where the ground is expected to freeze in the winter months. Understanding the frost line is important for construction projects to prevent damage to structures.
no Frost
The frost line in Salt lake city is 30 in. I would assume that that is average for most of the state.
3ft
The major bodies of water in Kansas include:Major Rivers - Kansas River, Republican River, Smoky Hill River, Arkansas River, Missouri River.Major Lakes - Tuttle Creek Reservoir, Cheney Reservoir, Waconda Lake.
i dont know whho cares Most concrete foundations are buried 4' to get below the frost line which is around 3'.