Urban Survivalists

Last week, we started the construction of our new rain water harvesting system by taking off our old gutter, adding a new one, and starting the creation of a roof washer. This week, we are going to continue installing the gutter and finish the roof washer and run some tests on it.

Roof Washer

Construction

There are four layers to our roof washer. The first item below is at the bottom of the roof washer while the last is at the top:

1. Trench wrap filter cloth (4 layers): to prevent sand and gravel passage into the outflow
2. Pea gravel 2-3″ thick: to cover the outlet pipes and allow easier water flow directly to the pipe
3. Filter cloth (4 layers): to keep the sand and gravel from mixing
4. Medium grade quarts sand: to filter out particles from the water inflow coming from the first flush system

A filter media, like the trench wrap we are using, must be used when adding sand to the filter because we don’t want to allow the passage of sand from the filter to the rain barrels. We have added a trench filter media in multiple layers between the aggregates and the outlet pipes. The finer filter media should prevent most sand from passing through into the clean water supply. The filter cloth was purchased from Home Depot and came in a 3′ long roll and contained  150′ of cloth. This is more than enough for something like 100 roof washers. We don’t really know what to do with the rest except maybe something to do with the aeroponics system we want to construct later.

Testing the sand filter:

We would like to know how long it is going to take our sand filter to drain if we are experiencing a heavy storm. At fist, we were going to plug the outlet pipes and fill the filter completely up with water and then time the drain time from that state. However, it occurred to us that this isn’t how a rain event actually happens. The filter starts off from a dry or mostly dry state and is expected to function from that moment to the end of the rain event. In light of this, we decided to simply start the filter dry and dump 12 gallons of water through it as fast as it could take it and measure the drain time.

Test time = 12min 50sec

Test volume = 12gallons

It should be noted that a full two and a half minutes were spent letting the last dregs dribble out of the system before we called it good and stopped the timer. From these numbers, it appears that our roof washer can drain at about a gallon a minute. This is not a bad flow for our test system but it is probably not fast enough for a full scale system implementation.

We can do a few things on our next iteration to increase the flow capacity. First, we will be using a larger drain for the system so that the pipes coming out of the roof washer are not limiting the flow. As it is, we feel that this may be one source of flow restriction though we have no empirical data to prove this. Second, we will not be using four layers of filter cloth on the bottom and four layers between the sand and the gravel. The filter cloth, at this thickness, may be inhibiting the water flow more than the sand in which case it would slow down our throughput. We also recommend washing your sand and gravel prior to placing them into the filter and testing. Our water as seen in the jar below, was dirty because we did not wash the sand and gravel.

These are just thoughts for our permanent system and for any systems you choose to build. Keep these things in mind.

Gutter Installation (continued)

Last week, we had finished attaching the actual gutter to the eaves but had not put in our leaf guards nor attached the downspout. The downspout is going to wait for next week–sorry, we know how much you wanted to read about that!–as there are some connection and measurement issues we have to resolve.

The leaf guard went over very nicely. We had acquired some vinyl mesh from Ace Hardware and had opted not to buy the brackets for installation as they were sort of spendy (around $1 to $1.50 each with a need for at least 15). Instead we made use of some 8 gauge fencing wire we had on hand and made some nifty little brackets ourselves in about 45 minutes at no cost.

You’ll notice we have the construction of the brackets outlined in nice, easy, graphical steps below so you can make your own. We encourage you to find cheaper solutions to problems like this yourself. In general, people often buy a solution to a problem that they have the equipment on hand to solve at no charge. Part of being sustainable is being able to solve your own problems, in our opinion it is good to get ourselves in this frame of mind and habit of thought as soon as possible.

Bracket construction:

Gutter guard construction:

You’ll notice in the pictures below that there was no use of ties on the vinyl mesh to hold it in the gutter. We feel that this is an okay solution as the vinyl mesh has some spring to it and it will likely not encounter any situation that causes it to come undone. Time will tell, however, and we’ll keep you posted of any failures of this system.

Overall, the effect of our home-made brackets was very nice. They are not visible at all from the ground and worked very well at both providing a resting place for the vinyl mesh and holding the gutter open at a constant width along the length of the roof. We highly recommend you make your own brackets too.

Future Plans, Next Week and Thanks to Larry

For our next phase of this project, we will be making our first flush system and endeavoring to find a good method of attachment for the downspout. We have been working on this problem for awhile. The issue is the square outlet from the gutter. We need a method of running this into a round pipe without a huge amount of leakage which would waste our precious water. We have kicked around ideas involving bolts and caulking but this just didn’t seem like a satisfying solution nor one that we can ask you to want to replicate. We want a clean, cheap, effective connection that (ideally) could be detached easily for moving or repairs. We know it’s not the easiest of designs, but are still searching for a good solution. If you have any ideas or have seen any successful implementations, let us know!

The rain water collection portion of our quest for urban sustainability is quickly coming to a close. This means we need to move into another data collecting mode and start designing and building another project. Since we have collected the water, we want to make it usable for a variety of applications not least of which is our growing school of Discus. To this end, we will soon be starting our filtration unit. This project looks to be much more modular than our rainwater harvesting system could ever be and as such, should be a lot of fun to build and document.

Let us know what you think and if you have any ideas for us. A couple weeks ago Larry Pfaffer noted that we had completely left out electronics tools in our rundown of essential tools for sustainability. He was completely correct. We would like to thank Larry for his spot-on assessment and add to our tool list a soldering iron and a digital multimeter capable of testing both AC and DC. We completely slipped the electronics aspect in our fervor over machine tools. Thanks Larry!

That’s it for this week. Be safe and sustainable.

P&S

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