Building raised Patio over Septic Line

ChrisDIY · 07-08-2010, 03:32 PM

Hello!

I would like to build a raised patio next to the house. There are two boxes for the septic line in the yard that have access panels. Neither will be involved however the line that runs to them will be under the planned patio. I will need to raise the level up almost 6 feet at the front edge (closest to boxes) and about 3-4 feet next to the house. My original plan was to do a deck but I like idea of doing a firepit on edge of patio instead.

Should there be any reason under normal circumstances you would have to dig up this line in the lifetime of this home?
Is the PVC pipe rated such that it should withstand the additional weight of the soil above?
The finger system is far away from the planned location.

LateralConcepts · 07-08-2010, 03:54 PM

How deep is the line currently?

Your question is a matter of speculation really. If you plan to run heavy equipment over the septic line it could cause damage depending on how deep it is. Either way, the line needs to be serviceable in case there's ever a blockage. Is there an existing cleanout for the septic line from the house to the tank?

PVC is common in new construction. Around here, homes connected to city sewer typically have 30/34 grade PVC lines that are buried 6'-12' deep. They withstand the weight of all that soil on top. If not properly bedded prior to back-fill however, can become bellied and sometimes break.

Additionally, running heavy equipment over a drainfield can cause problems by compacting the soil.

I always suggest people consider the long term prior to any landscaping, patio, decking, project. If down the road there happens to be a problem, your beautiful patio and fire pit may have to go. On the other hand, it may give you years of enjoyment without a problem.

When was the septic system installed or how old is the home? Have you ever had a history of problems, i.e. slow drainage, back-ups, sludge buildup, etc.?

ChrisDIY · 07-08-2010, 04:17 PM

Quote:

Originally Posted by LateralConcepts

How deep is the line currently?

Your question is a matter of speculation really. If you plan to run heavy equipment over the septic line it could cause damage depending on how deep it is. Either way, the line needs to be serviceable in case there's ever a blockage. Is there an existing cleanout for the septic line from the house to the tank?

PVC is common in new construction. Around here, homes connected to city sewer typically have 30/34 grade PVC lines that are buried 6'-12' deep. They withstand the weight of all that soil on top. If not properly bedded prior to back-fill however, can become bellied and sometimes break.

Additionally, running heavy equipment over a drainfield can cause problems by compacting the soil.

I always suggest people consider the long term prior to any landscaping, patio, decking, project. If down the road there happens to be a problem, your beautiful patio and fire pit may have to go. On the other hand, it may give you years of enjoyment without a problem.

When was the septic system installed or how old is the home? Have you ever had a history of problems, i.e. slow drainage, back-ups, sludge buildup, etc.?

There is a clean out at the house before it goes under the current deck. I have the actual depth in a pdf file but my old computer crashed so don't have access to it at the moment. It's greater than 3 feet. I would be driving nothing heavier than my current tractor over it, which I do every time I cut the grass. Will build using retaining wall blocks, pavers and elbow grease. It would be in front of the deck in the very left of first picture in link below. House built in 2005-2006. No drain issues yet. Needs to be serviced since I haven't done that after a year of ownership.

Images here: House Project.

LateralConcepts · 07-08-2010, 04:50 PM

I think you'll be fine as long as you don't cover up any access for servicing. (inlet baffle, outlet baffle, center lid, or cleanout)

At least with pavers if you ever had a problem you would be able to pull them up instead of jackhammering or sawing through concrete and rebar.

As far as servicing goes, every year is good practice, but probably not necessary. If it's a 1000 gallon tank and a typical single family residence (3-5 people that don't abuse it) Every 3 -5 years is ok.

Daniel Holzman · 07-08-2010, 06:35 PM

I assume you have a permit from the Town for the existing septic system. Similarly, you are likely going to need a permit to build the raised patio. At the time you pull the permit for the raised patio, the building department should communicate with the Board of Health to determine if the Board of Health feels there are any issues associated with raising grade over your pipe, and possibly impacting the septic field if you are anywhere near it. In the end, the building department and the Board of Health most probably have the final say on your project.

ChrisDIY · 07-09-2010, 12:44 AM

I guess I may have to "fake it?" Use conventional footers for a wood framing deck. Build the firepit/fireplace with apron. Wood framing and firepit/fireplace will not be connected. Apply decking up to the apron but do not attach. Build retaining wall around wood deck so it would look like a patio. Something like that. Would need to get plan approved at least this would only require removing decking in the event access is needed. I'll be forced to go all the way around to the rear with retaining wall otherwise I am sure I'll have all kinds of woodland creatures living under deck.

I will have to figure out how to build a slab for firepit/fireplace on top of footers.