Shop Grey Water

Before I get after today's post, I would like to wish my US readers a happy belated Labor Day. I recognize the value our labor unions and those who fought for worker rights have provided those of us who came after. Ironically, I spent Labor Day and the days before shoveling dirt, but that's what today's post is all about. One last thing: Thursday is my son Cedar's 25th birthday. While most folks are looking at Friday to consider the implications of 9/11, 25 years ago, I will be considering the implications of his arrival just a few hours prior (1130PM on 9/10). Happy Birthday, C. 

 

Some History 

ready for the rains

Back when I started my concepts for this shop, I did not have much of a plan other than a spot to put and work on cars. During the initial permitting process (See Building a Shop - Permits), I did not have a plan for water use or even a plan to make a plan for water use like a bathroom or whatever. After the plans got started, and the metal building ordered, I thought about how nice it would be to wash my hands before crossing the yard into the house. And then I thought about how nice it would be to take a leak without tracking whatever was on my boots and then whatever my boots picked up in the yard into the house. I started first with looking at what was possible in terms of tying into existing sewer systems.

 

The shop is a good 35 meters from the back of the house. So, if the main sewer pipe under the house is less than a foot below ground in the crawlspace and the crawlspace is barely below grade overall, I only have less than 50 feet before I run out of elevation. I determine this using the basic formula for waste water management: a pipe must have a pitch of at least 1/4" drop per foot, or 1 inch per 4 feet. If we extrapolate that out to one foot of descent, that's 48 feet before the waste pipe is lying on the ground or being suspended above ground. So, that doesn't work.

 

2 foot deep 2 foot wide channel

Next, I looked at connecting to the sewer running along the adjacent street on the other side of my neighbors. While it is downhill, it would still be a couple hundred feet, and either through one of their yards or right on the property line. Either way, that would require an easement that one or both of them would need to approve and it would tie into the city waste system while my property is not. After all that, I was unable to determine how far underground the city sewer is. I decided it was all just too legally perilous and dropped the while thing.

 

Since these musings were taking place while the permits were getting finalized, I drew in a 2 meter square in the southwest corner where we would not put concrete, and just leave gravel. My thought was we would have a wet room or something if I could figure out the waste management side.

 

Storm Outflow to Bio Swale

trenching

As part of the excavation work for the foundation, I had the Clean Water Services -required storm outflow and a channel from the rear of the building to the outflow dug out. This cost me a few extra hundred bucks and a cherry tree. I then located and had delivered large rocks of the specified size (the finding was NOT easy). This cost me another $1000US. Ultimately, this shop cannot support rain gutters, so I spent multiple weekends last summer digging out and installing French drains to manage the rain water. That system has been working really well, by the way. Anyway, a year later, the permit has been long closed, and I still had a 2 foot deep 2 foot wide channel from the rear of the building to the hole with rocks in it. It can be seen in the foreground of the second picture from the top. When I had the trencher, I took a stab at putting a more direct trench from the hole to the backside of the building where the wet room square was located. This trench was only 4 inches wide, mostly 2 feet deep, but it did not go the full distance due to soft soil gumming up the wheels. The new plan was to put in a floor drain in the "wet room" and run that grey water into the storm outflow, and maybe, eventually, purposefully add plants designed to thrive in a bio swale.

 

More Trenching

bored through

All of this backstory leads me to the antics of this past weekend. I started with a shovel and soon had small hand tools, a post-hole digger and a hoe to work the trench. Unlike the major trench I did for the electrical feed, this 25 foot trench encountered a half dozen large roots. I was able to hand-dig around either side but to get underneath, I used a framing hammer and a steel rod to bore a hole and then used a hand digger to clear it out.

 

I knew that the foundation for the steel building included a 1-foot by 1-foot curb. The rest of the floor was reinforced 4" concrete. The 1-foot, however, set the high-point for the top of the grey water pipe at the edge of the building. Every 4 feet closer to the hole I got, the trench needed to be another inch deeper until at the end, I was 18 inches below level. To determine a consistent relative point from which to measure progress, I laid out a stretch of pipe and used a level, propping up the hole-end to get level. Then, I measured distance and depth from the pipe. It took me a day and a half, but I got the trench dug out, with large openings under the roots through which I could pass a 2" pipe.

 

Surge Tank

surge tank

With the trench set, I wanted to complete the outside steps. I figured I could leave most of the indoors work until after the rains start. Even with a system as tiny as this with such low input (a rarely-used floor drain and maybe a couple of dry sinks), it is advisable to include a surge tank. This is so when a large wave of water enters the system it does not instantly propagate down to the bio swale. This also serves as a place to clean out stuff that made it's way into the drain that you may not want further downstream. I used a 5 gallon bucket for my "tank". Oh, by "dry sink" I mean a sink that does not have any water fed to it. We do not have a county-supplied water source out there, and no plan for one. We could harvest rainwater, but anything like that would not be pressurized water, it would be pure gravity feed, so a "trickle" of water. Alternatively, we could do something with 5 gallon buckets, but, again, it would be a gravity feed trickle.

 

layin pipe

Immediately outside the foundation, I dug a hole large enough to fit the 5 gallon bucket and then realized that I can't just stop there. The pipe that feeds from the shop side needs to be in place too. So, I measured to find the spot where the pipe needed to pass and dug about 18 inches down, and about a foot across inside the shop gravel at the spot I had measured. Then, I tunneled under the foundation with the hand digger. Once I was able to pass a short stretch (about a meter) of 2" pipe between the holes, I located and drilled holes in the bucket for the 2" pipe to enter/exit the bucket. At some point, I figured I would put a bucket on the shop side similar to the surge tank, but this bucket would be intended dry. Inside, would be where I would add a pee-trap, but I'm not sure if this little system would necessarily need one. Something to think about while it's raining.

Piping and Filling

I hit the local home improvement store for a collection of 2" pipe bits, but only really needed another 10' of pipe, a butt joint, something to put on the pipe ends to fill the space between the pipe and the bucket and some pipe cement. With the goodies in hand, I joined together the pipes with cement and after they set (10 minutes), I sent the completed 25' of pipe from the hole up the trench to the bucket outside the shop. I added a collar to that pipe, with cement, and then fit it into the hole in the bucket. To test the system, I poured a gallon of water into the pipe at the bucket and quickly walked down to the other end. Most of the water had already left the pipe by the time I got there, so I took that as success.

 

draining

The rest of Sunday, and part of Monday was spent shoveling dirt from the mound at the foot of the black walnut tree into the grey water trench and the 2 foot deep 2 foot wide channel. With the trenches filled in, the rains can begin and we can feel comfortable that neither we, nor our friends nor our pets will trip and fall into one of the open trenches. We still don't know what we are going to do back there. Maybe we'll let it get overtaken by wild flowers or we'll seed it for grass or we'll put a food producing garden back there or it will just get wood chips. At this point, since it is space we have never used before, we haven't a preconceived notion.

Wrap Up 

As you can see from the image at the top, as compared to some of the others, what was once a hazardous place to walk around has become relatively flat and hazard-free. As I figure out how to make something work inside the shop in terms of a floor drain or a dry sink, I'll post on it. Long term, it would be really nice to have, like, a composting toilet and some low pressure water for washing hands out there. Even that would be pure luxury.

 

That's it for now. Thanks, as always, for following along-