The challenge has been laying out the planters and walls while making sure we still have space for kitchen counters, walkways between the rooms and everything that has got to go into the bathrooms. This process has involved a lot of discussion and some arguments. Sandra and I are both still alive so I guess the arguments were not too bad.
Before laying out the planters we needed to establish a direction of water flow and planter elevation. I did not give a lot of thought to the flow of grey water through the planters when drawing the plans. I did locate the bathrooms along the south face as I felt this would simplify the grey water layout and I think that was a good decision. Our earthship has two bathrooms though, and this means we considered two options for water flow; a split system terminating in the same planter, and a shared linear system. In the split system the kitchen and common bathroom grey water would flow through two shared planters and the bathroom off the master bedroom would flow through its own planter before ending in the same planter as the kitchen and shared bathroom. The split system was my early favourite as it meant short runs from the grey water sources into the planters. I was quickly overwhelmed by the complexity of laying out this system. Not having planned for this idea from the start it was hard to fit our planter layout into a split system. We settled on a linear system that starts at the east and of the building and flows to the west end. This system means some longer runs than I had hoped for, but it is fairly easy to understand and design.
The other consideration in laying out the planters was elevation; both with respect to all the other planters in the system, and in relation to the grey water appliances that are feeding the planters. The appliances feeding the grey water system (sinks, tubs, …) must be elevated above the planters (you need about 1/4″ of elevation per 1′ of horizontal travel of the grey water pipes). In our case it means one to two steps going up into the shared bathroom so that we get sufficient elevation to get the tub water to the start of the planters. Also, each succeeding planter in the system must be slightly lower than the one before it so that water flows through the system (like an underground river instead of a stagnant pond). Again, we sloped the bottoms of the planters approximately 1/4″ per horizontal foot of travel.
The planters are linked together with pipes located about six inches off of the ‘floor’ of each planter. This means that the 1st planter is connected to the second planter by a 2″ diameter sewage pipe. The pipe leaves the first planter with the bottom of the pipe about 6″ off the floor of that planter and enters the 2nd planter again with its bottom about 6″ off of the floor. This means that the pipe also slopes 1/4″ per foot of horizontal travel to encourage the flow of grey water between the planters. The pipes are located close to the planter bottoms so that the grey water elevation is constant in the system … no one planter is a swamp or dry.
We ran these connector pipes a year ago when we did the initial excavation of our planter space. We used our backhoe to dig a trench along the front of the building. We did not give a lot of thought to the size or elevation of our planters at that time … we just did not want to be hand digging the planters a year later. Our ground is clay and rocks … making it pretty tough digging!
Because we did not set elevations or think through the size of the planters last year we have spent a lot of this week DIGGING BY HAND (I am very glad James is here). We had to re-grade the planter ‘floors’ so that they all consistently slope a 1/4″ per foot, and we had to dig up all of the pipes and set them properly as well. Most of this work is done now except for the last planter on the west side of the building.
We have also started forming the walls of the planters. Again, the work we did a year ago digging the planters was not very accurate. Most of our initial holes were wider than the intended planters. This means that we have been forming pop can/concrete walls from the bottom of the planters up to our desired planter wall height. Ideally, we would have been able to start the walls on the outside perimeters of the initial excavations, reducing the work and materials required.
Underneath the pop can walls that form bathroom walls we placed a small concrete footing (6″x6″). Underneath the pop can walls that form planter walls we excavated a small trough and filled the trough with concrete before laying cans. The footings contain engineered fibres and is a standard mix (1 part cement ; 2 parts sand ; 3 parts gravel). None of these walls are load bearing; the purpose of the footing is to create a flat, level working surface for the walls.
All in all it has been a productive week!