I live on a long steep hill and my yard is prone to flooding. Technically it’s not wetlands but during the spring and heavy summer rain, it becomes incredibly wet out back. I’ve done some research and decided to put in a French drain system to divert the excess water into the woods below. Conceptually it doesn’t sound too hard to do. Making sure to have the pitch correct, the right size stone, and landscape fabric to keep the holes in the perforated pipe from getting plugged. I can handle all that. The hardest part is digging the trenches. I did a test with a pick axe and a shovel just to see how labor intensive it was. Being in New England where the soil is 50% large stones, I can’t see myself digging the whole thing by hand. Enter renting a trenching machine. Who here has used one, and did you have to battle a lot of rocks? How’d it do? Also any tips on the drainage system are welcome. Thanks in advance.
How big are the "large stones"? I've used some small trenchers and small rocks (3-4" and down) only slow you down (sometimes quite a bit) but get much bigger than that and they seem to cause rapidly increasing problems with each inch of diameter gained. Get much over 6" and it becomes a real PITA (usually have to dig out by hand) unless you have a pretty large machine (bigger than what most homeowners can get their hands on)
Mini excavator with a little bucket would be my choice. Either way the rocks in the way gotta go. A small rental trencher isn't going to do well.
I’ll be dealing with stones averaging the size of a large potato. I know there will be some bigger ones I’ll have to hand dig. From the excavating I’ve done in my yard so far I know there are rocks underground that I’d need heavy equipment to move.
A large potato that is in the path of a trencher by say a french fry has to either be uprooted or hash browned. Definitely not a piece of potato pancake for the machine.
Can you create swales and divert surface water around areas of concern? Or is the goal to move standing water in the ground itself?
I think the best approach is to divert as much of the groundwater itself. My most immediate concern was the run for my chicken coop, which was flooding pretty badly. Last night I dug a 20' ditch about a foot down just to prevent some of the water from getting in there. I noticed when I did that, water was just seeping into the ditch from the higher ground above me. It's almost like an underground river going through there at times.
I just had 130' of 30" deep ditch dug with the smallest compact excavator Kubota makes using an 8" bucket. I think it was an 008. Lots of rocks in the entire ditch and some the Kubota couldn't pick up with the thumb. Digger Dan has been doin this for 60 years and has diabetes. He apologized it took 4 hours. A good operator can make it look easy.
Terminology: in my mind a drain tile drains supersaturated soils, and a French drain directs surface flow down to a drain tile. The French drain provides a much greater infiltration rate than the native soil; it generally implies backfilling the trench to the surface with a material you bring in (coarse sand, for example). If you are dealing with overland flow, the French drain can help. If you are dealing with perched groundwater, you might simply need a tile drain. edit: another option is a catch basin. They make some cute 6” ones these days for landscaping. That gives you maximum infiltration rate.
Well, considering I might be getting 6 inches of rain this weekend, I guess all the manual labor will be worth it. I figure I’m 2/3 of the way there on the depth of it. This will be one of 3 trenches I dig.
Do it when it's pouring out, seriously. Once it's flowing the solvent action of the water helps a lot. Scrape away with a mattock a bit at a time.
An adz has a single blade, as I recall. A sharp edge for carving/hacking into a log, removing wood. Not intended for ground work. Good word for Scrabble. It always get questioned as being a real word.
