Initially I designed the horizontal ground loop as a 56" slinky at 6' depth, 4 trenches for a 3 ton system, spaced 10' apart at 130' length. EWTmax 88.1 F. I've priced a local excavating company and received a quote of $5k. Just for digging, which seems a bit high. Digging conditions are level, no roots, no rocks, sandy loam to sandy clay loam(very easy). This job would be trivialized with a large trackhoe, I believe. However, what is readily available for rental are Bobcat E42's. I can have something larger shipped in, but the cost becomes quite high. The Bobcat E42 can be equipped with 12" -36" buckets. I guess my first question is, does 5k sound outlandish for trenching? ~346 Cu Yds. and putting the soil back in the hole. If I go the DIY route, is the bobcat e42 enough machine to reasonable trench 3' x 6' x 130' x 4 trenches? (say in 3-4 days by a beginner) I've redesigned the loop several different ways, including standing slinkies. Initially I was trying to get the most out of 600' of pipe per loop and a 50' x 170' area. I also maintained a less than 90 degree EWTmaxx(Eastern NC). I can't find a chain trencher locally that will go to 5-7', but it seems like, in software, the standing slinky performs reasonably well, and increasing the loops to 1000' of pipe would cut down greatly on the amount of soil movement. A 12" x 6' deep, 130' long, x 4 loop field comes up to about 115 yards of dirt. Here I guess my question is, does this logic stand to reason with anyone's experience? I may be relying too much on software, but for reverence this is what I've been using. https://looplinkrlc.com
I would get more quotes for digging. Maybe work it out where you fill it back in. They can be cheaper if they dig and leave. Find someone that digs on the side. I found a guy that had the biggest mini track hoe they sell and he digs on his day job. He owns his own track hoe and dug my two 300’ foot 3’ wide trenches. It took ½ Sunday and to evenings after work to finish.