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Ground Work

Bangor Daily News Op Ed 2/9/06
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Drilling 12 - 1 inch holes in basement wall below frost line


I opted to have all joints in the basement since joints are the weakest points. If one of the 6 branches developed a leak, it could be isolated in the basement even in the middle of winter and the system would still continue to function. Holes were drilled from the inside the basement before the trench was dug. (Note the water shown in the picture below is from ground water leaking into my basement due to high amounts of rain we’ve had this year.)


Digging Trenches


The most difficult and stressful day involved digging the trenches, laying the pipe and backfilling. The first step was to contact DigSafe two weeks earlier to make sure there were no hidden pipes or cables where the trench was suppose to go. The excavator dug the trenches in one morning while I prepared the pipes. Since the trench was fairly deep, I laid 6 pipes in the trench as soon as possible just in case trench walls might collapse. For safety reasons this must be done from the side of the trench without going into the trench. At first unrolling 6 rolls of 300 foot pipe is hard demanding work. Fortunately the job gets easier as the rolls get smaller. In one place the walls did start to collapse a few hours after the pipe was laid.


The next step was to stick the pipes in the basement wall. I inserted the ” pipes in 4 foot lengths of 1 inch plastic pipe where they go through the basement wall. This protected the pipe from scraping against the concrete wall as it thermally expanded and contracted. Furthermore it provided a little extra insulation around the pipes which would minimize any frost damage to the basement walls resulting from the cold pipes. I used a lot of sealant around the pipes but I missed a couple spots and I did get some leakage with all the heavy rains we’ve had this year. I’ll have to fix that this summer. Finally I had a chance to rest as the excavator backfilled the trenches.


Finally I could relax and begin to wonder if everything was done right. When the excavation began I didn’t know what kind of soil the excavator would find. Would he hit ledge or immoveable boulders? Would he get below the water line? Drenched soils are good but would there be too much water? Will the walls collapse before I had a chance to lay the pipe? Any of these things could have brought the Geothermal Heat Pump project to a halt.


The backfill in the trenches settled over time and the ground will need to be leveled again in summer.


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