Can I Bury Foam Core PVC

[zink88]

I will be installing a water filtration system to remove Iron from my well water. Our county code says not to route the backwash into septic or to the drain field.

I will be discharging the backwash into the woods behind my house which requires a run of ~130 feet at slope of 1/8” per foot. I was planning to use 3” PVC and possibly tie in one of my downspouts.

The 3” PVC sold by the big box stores is foam core. The bottom of the trench will start at 6” depth next to the house. Is it ok to use PVC foam core schedule 40 pipe as opposed to solid core?

The last 70 feet of the run will be in the woods.

 

[Reach4]

Yes.

3-inch seems large. I would be thinking 1 inch, or maybe 1-1/2, presuming that this is not going through an air gap.

 

[Sponsor]

 

[Breplum]

Downspout sizing is in charts found in the code books.
For Raleigh, NC, the code lists 4 inches/hr and GPM/Square Foot of .042 (100 yr 60 minute rainfall in inches)
please list your roof area served and pipe size can be calculated using UPC Table 11-1 and Table 11-2
Generally, plastic pipe should have more than 12" of earth cover to prevent physical damage. We use cast iron when so close to the surface.
At 12" Sch 40 of any plastic pipe would be fine.
I don't know when I will be back at this site, but someone can help with the tables or you may find online.

 

[Reach4]

This is for an iron filter. Iron filter backwash may be between 7 gpm and 12 gpm typically. This comes out under pressure, but maybe there is an air gap at some point. If the air gap is at the far end (such as discharges above ground), you would not need big pipe. If there is an air gap, I still think 2 inch like used for a washing machine standpipe should be sufficient-- I would think.

 

[zink88]

The roof handled by the downspout that I might tie into the drain pipe is 276 square feet (23’ x 12’). I didn’t find a UPC table 11-1 or 11-2. I did find a table 1106.3 which I believe indicates a 3” horizontal pipe at 1% slope (1/8” drop per foot) can handle 6” of rain per hour from a roof area of 548 square feet. Am I reading that correctly?

The table doesn’t provide information on any pipe less than 3” in diameter.

The plan is to have the pipe discharge on the surface in the woods behind the house which would be considered an air gap, correct? I could also have an air gap at the entrance to the pipe above ground at the back of the garage by having a smaller vertical pipe feed into the open end of a larger drain pipe with no reducer to connect the two. The filter will be in my garage and the discharge line will be routed horizontally out the back wall and then straight down to the buried drain line.

I was planning to only bury the line so the bottom of the pipe is 6” below ground where it starts at the back of the garage so the end of the pipe ends up above ground 130’ behind the house at 1/8” slope per foot. If I start the pipe with the top 12” under ground I don’t think I can end up above ground before reaching the end of my property at 1% slope.