Leaking underground

if your moving your boiler like Rob suggested , dont worry about it . If your leaving alone then you need to dig the thing up , This time make sure there is a place for water to drain from the ditch. It kinda looks like there is a little bit of grade to the side of the trench, dig a few laterals off the ditch to daylight . Next figure out what you want for pipe and insulation . Finally , fill the trench to 6" over the pipe with #2 washed stone(round golfball size) not sand or dirt. the stone will have air pockets which will keep the ground from stealing your heat. Wet sand or earth around your pipe is'nt any better than water. no water, no worries
Im shure it hurts but, you'll just have to burn coal a little longer to offset the cost. And if your gonna use a conduit it needs to be watertight till your above grade and Id still use the stone for fill.

waldo

Just looked at your picture. You said you went pretty deep with your pipe so you have a lot of heat loss to melt the snow like that. It is expensive, but I used 1 1/4 inch thermapex for my line. Ran about 100 feet between the barn and the house. Sandy soil (like masonry sand) and only about 30 inches down in some spots. Absolutely no snow melt. My IR gun is a cheapo but shows little or no loss at the transition to copper when measured at house entry and barn exit points. I also have heat pumps at the house to use when I'm not home or in Spring and Fall. Harman boiler and electric water heater. If I had the option to locate in the house I would consider either one of the Harman (or other brand) furnaces and electric hot water heater or the boiler with DHW coil and air duct heat exchanger. The new, high efficiency hot water heaters are pretty thrifty and I don't have to worry about keeping a fire going during the summer when I'd rather be fishing and we have to deal with power outages caused by thunderstorms.