Yay for grey!

A covered box needed to be constructed around the sump pump so the area could be buried but we would still have access to the sump pump for servicing, and the diverter valve should we ever need to bypass the wetlands and start dumping the grey water back into the main sewer (note the outflow pipe leading off in the direction of the wetlands)

During rough grading, our guys excavated a 15’x25’x2′ deep “wetland” area in the middle yard which was to be filled with gravel for treatment of the grey water

Three trenches were then dug in the far back yard, lined with drain rock, and then perforated drain pipe. Check valves in line with the drains prevent siphoning of water back up into the wetlands. These pipes were then covered with a layer of drain rock, and reburied under the soil

The grey water pit was then lined with a protective liner to help keep the EPDM membrane (the water proof liner) from getting punctured. You can buy special material for this commercially, but we reused the spongey plastic separators that came in between the huge paving stones. Rather than throwing it away, it found a second use as our protective liner

An enormous (and astonishingly heavy) pond liner was then rolled out to fill the pit. We are using 40 mil EPDM which is available at specialty pond supply stores or by mail order on-line. It is more durable than the lighter weight PVC pond liner you can buy at Home Depot or Lowes

We partly filled the liner with water to help settle the bottom and smooth it out. Then landscape fabric “socks” were wrapped around perforated pipe which was plumbed to an overflow that passed through the EPDM membrane to flow into the now buried leach field. The pipe coming in from the left with an in-line check valve is the overflow from our rainwater cachement tank, so in a year of very heavy rainfall, our excess rainwater also gets dumped into the greywater leach field

This liner was then filled with (two and a half truck loads!) of  3/8″ pea gravel, and Catherine discovered her little measurement error… the water would overflow the edge of the liner before flowing out of the pipe… the pass through, however, was a nice use of two toilet flanges that bolted face to face through the liner (with a 3″ hole cut in it) making a water tight seal … the guys at our local plumbing supply store know it is usually going to be something weird when Catherine walks in.

The pea gravel was then covered with landscape fabric and a little sand to keep it in place in anticipation of being buried… but things were on hold for yet another trip to the plumbing supply store in search of a solution for that pesky outflow issue…

A little plumbing ingenuity was all it took to bring the outflow pipe down to the right level, have an access point for draining the wetlands (should that ever be necessary), and still keep the grey water from flowing into the rainwater cachement tank…

Now when the water is filled up to the level of the top of the gravel, (but still a couple of inches below the liner top all around!) water starts to flow out of the outlet to the leach field. It is a beautiful thing. Grey water in one end of the wetlands, and cleaned water out the other end off to irrigate the yet-to-be-planted fruit trees

Then all that work is buried under a layer of mulch, and a bit of top soil with only the access drain peeking out.