CA - Domestic Waste line minimum depth advice

[sferber]

Hi Everyone,

I wanted to see someone with more experience could offer advice in our situation. We are struggling with a remodel design because of distances (nearly 100ft) involved in the plan. Is the minimum depth for the sewer pipe below grade at 1 ft or 2ft? What is the minimum depth for the outlet of the waste piping at the edge of the house? And finally what is the minimum depth for the sewer lines outside of the building?

The City has said that they will allow a slope of 1% provided we use a 4" pipe. But because of the distance involved, I am not sure we can make it work with the existing grades.

I looked up the following code reference from the 2010 CALIFORNIA PLUMBING CODE.

Thanks in advance for any advice you may have.


"718.3 No building sewer or other drainage piping or part thereof, which is constructed of materials other than those approved for use under or within a building, shall be installed under or within two (2) feet (610 mm) of any building or structure, or part thereof, nor less than one (1) foot (305 mm) below the surface of the ground. The provisions of this subsection include structures such as porches and steps, whether covered or uncovered; breezeways; roofed porte cocheres; roofed patios; carports; covered walks; covered driveways; and similar structures or appurtenances."

[hj]

I have installed it 4" UNDER the ground, as long as you use the same material as inside the house, which would be the normal situation these days. The plumber has to be well versed and able to visualize a different drain system than normal to get the pipe to that shallow elevation, but it can be done.

[sferber]

Thanks HJ. How much distance do you have between your furthest drain and the exit point of the line to be at 4"? I have talked to a few plumbers so far and no one has said they could install anywhere near 4". I was told that we are to use a ABS Schedule 40 pipe throughout.

[hj]

The closer the plumbing fixtures are to the exit point from the wall, the higher the pipe can be in the ground. In the situation I was describing, they were next to the exterior wall. You establish your "starting point" as high as possible, such as just below the floor slab, then go downhill from there. Creating a "high starting point" is something that usually separates the "plumbers" from the "installers".

[ballvalve]

freezing is not an issue, so pretty much anything goes. If you are on a slab/ septic, you might be lucky to get 2" of cover for the starting point. dont drive on it.

[sferber]

freezing is not an issue, so pretty much anything goes. If you are on a slab/ septic, you might be lucky to get 2" of cover for the starting point. dont drive on it.

Thank You Ballvalve. We will have slab foundation going to a septic system. The County requirements are very difficult to meet here because of high seasonal water tables that are due to agricultural seepage. The irony is that they consider this clean water even though it is wastewater that contains pesticides and fertilizer.

I was told that we would not be able to drive in that area and should not plant anything near the lines.