At what depth is the Ground Temperature constant in Salem Oregon and what is that temp?

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Lynhart Ranch (2074) - Site Information and Reports (http://www.wcc.nrcs.usda.gov/nwcc/site?sitenum=2074&state=or)

Pretty much around the world,except for around the poles permafrost ground,and you may have to go 1 or 2 feet deeper in a sand desert. But the depth would be 3 feet and the constant temp would be 58-62 degrees.it's a good place to run a series of water lines to use for cooling,and also in cold climates they would be your heating. 60 degrees might be a little chilly for some but it's a lot better than 37 degrees or 97 degrees. Rate answer please:)