1) (25pts) Irrigation Pipes Freezing in the Ground Jackie is the Park Planner for the City. She builds and designs parks and installs a lot of irrigation systems. They install pipes

at 2 ft. below the surface. When it was so cold in Week#2 ("ice week") she asked how long it would take for the pipes to freeze if it stayed cold. Assume that the earth is generally at 45°F. and the surface temperature suddenly drops to 0°F. The ground temperature at 2 ft must be at 30°F for 24hrs before the pipes freeze. How long does Jackie have before she needs to worry about the pipes? Ground Properties: k = 0.8 BTU/hr-ft-°F, a = 0.02 ft²/hr Sketch and Label Problem. Clearly state assumptions and show calculations, including units.