Post date: Dec 13, 2014 5:19:39 AM
We knew that the sewer connection was not very deep, but were not sure whether it would be a problem. Now we know, and the house will not be high enough to drain into the sewer. Shallow sewers seems to be a problem all across the subdivision.
How do we deal with this problem? I see these methods:
My immediate neighbor raised his house so that there is sufficient drop (1/4” per foot) in the sewer line. However we have a height limit in the property deed of 17 feet. With a single story Pueblo style house this should not be a problem, but my neighbor looks like he is up on a pedestal and has a pitched roof. Even after modifying the roof structure (after it was framed - tore part of it down and started over), he is over the limit.
I have a flat roof and my little mechanical room is set back from the parapet walls so it doesn't appear to be high. Also, we will have plenty of dirt from the excavation (120 cubic yards, I believe) so we can build up the soil around the foundations to make it look more nearly natural.
Another other neighbor’s plumber apparently installed the sewer line with less slope. However they have had to pump out the drain line every year. Clearly not the answer.
I am familiar with sewage pumps because we had to use them on the houseboat. Sewage is collected in a plastic tank (called a ‘basin’). A submersible pump specially designed to handle 2” diameter solids pumps the sewage up into the sewer main. This is often used for basement bathrooms, so is a common application. In my case the pump would be buried 10 feet away from the house in the garden. The cover must be accessible for replacing the pump.
To quote from one manufacturer “Installation is normally done by digging a hole at least 24" larger in diameter than the basin diameter to allow for a 12" backfill all around it. The backfill material should be 1/8" -3/4" pea gravel or 1/8" -1/2" crushed stone. The hole should be dug deep enough to allow for 12" of compacted backfill or 6" deep if a concrete pad will be required. Do not backfill until the inlet and discharge plumbing lines have been installed into the basin. The hole should be at least 10 feet from adjacent structures. The top of the basin should be flush with the top of the surface of the ground for access to the pump and basin. When located below grade a riser extension is recommended to bring the lid up to ground surface for easy access to the pump and interior of the basin. The installer will need to dig a trench and plumb the fixtures to drain into the 4" basin inlet which can be bushed down to 3" if needed. A trench will also need to be dug for the discharge pipe and for the electrical conduit. The sewage discharge exits from the side of the basin to be plumbed horizontally underground and tied into the main drain….” My guess is a $1,000 jump in the budget - mostly for extra labor.
Liberty Pumps and Zoeller both make fine pumps and basins. The pump will cost about $300, a basin adds, then we need a back-check valve and, of course, installation costs - more digging, more gravel.
I had originally planned to separate the greywater (laundry and shower) from blackwater (toilet and dishwashing). My plan was to re-join them outside the house until I was ready to deal with using the greywater for irrigation. I’m not planning on buying a laundry washer yet, so the amount of shower water will be very small - maybe 25 gallons a week. This is probably not enough to set up an irrigation zone, so we’ll just run it into the sewer for now. (Collected rainwater may be 250 gallons per week.)