What is this big pipe and big concrete block?

[Ax01]

hi i'm new (see intro: https://www.gardenpondforum.com/threads/hey-hey-hey.27655) and this is a long post. anyways i found some interesting stuff during my dig today. i'm not sure if they are of concern but i didn't expect to find them and they are in my way!

Preface: I called 811 like a month ago before my dig (just as i started buying and collecting pond materials). i actually filled out a form online. some utility companies came out and marked my front yard. the only company that knocked on my door was the sewer company, so they can mark my back yard sewer line. here are pix:

https://imgur.com/a/vGkCzhM

the line is 3 feet from the foundation and angles out to like 6 feet before making its way into the alley to join a main line beyond my fence. the sewer guy used a map and grid to determine the location and left me a copy. the sewer pipe was the only obstruction i was aware of in my backyard and i was careful to be plan and dig far away from it.

so i was digging today when i noticed i reached gravel like 12 inches down. i thought whatever and soon i found a big pipe! i thought 'Omg i hope the sewer guy didn't get it wrong and this is my sewer piper!' i thought it was metal at first, but i think it is a concrete pipe and seems to be wrapped/connected by black vinyl tape that's in 1 foot sections? see:

is it an electrical conduit? a drainage pipe for my gutter? whattabummer! i really wanted to dig deeper than that in this section and really hope i do not have to cover up this whole part.

nearby and a couple inches lower, i struck more hard stuff underground. i seems to be a large concrete circle/cylinder! and i uncovered like maybe 25% of it. see:

and what is this?! the sewer guy didn't mention this? was this an old septic tank (before the house got connected to the sewer)? is it part of the house's foundation? what the heck?!

anyways i'm calling the sewer company in the morning? we are not near the lines that had been marked:

any other thoughts and feedback would be appreciated. thanks yall!

 

[addy1]

That looks like a septic system. Hope not for your sake that tank would be horrible to get out. IE a huge backhoe!

I found mine while digging the pond, found the tank and the lines to the other two tanks. Glad I stopped to see what I was trying to break up (thought it was a huge rock)

 

[texastkc]

We found a collapsed clay pipeline. At first, we thought it ran to an extinct septic tank but it turns out it ran to an old drywell. It was used for runoff from the water cistern they used to use here. However, in your case, I'm betting septic tank.

 

[j.w]

Yep that looks like the old septic tank and pipe running from your house. They usually fill them in but who knows if they did. I think you are gonna have to work around it to build your pond as not sure how much that would cost to remove. It could also be the runoff tank for washing machine etc. water as the neighbors at our old house in Everett had one in the back yard.

 

[Crimedog]

looks like a Bog area behind the pipe - and a plant shelf (concrete circle) and a good excuse to double the size of your pond

 

[Ax01]

thanks all. i'm a second year homeowner and this house was built in the 60's but was updated before we bought it. last year we re-did the fence and i'm building the pond this year.

That looks like a septic system. Shope not for your sake that tank would be horrible to get out. IE a huge backhoe!

I found mine while digging the pond, found the tank and the lines to the other two tanks. Glad I stopped to see what I was trying to break up (thought it was a huge rock)

yeah, i'm not digging it up or moving it. it's just more time and money. how did the discovery of the tank and lines affect your pond build? did u incorporate it? did u move it or change your plans/layout?

We found a collapsed clay pipeline. At first, we thought it ran to an extinct septic tank but it turns out it ran to an old drywell. It was used for runoff from the water cistern they used to use here. However, in your case, I'm betting septic tank.

what did u do with the collapsed pipeline? removed it and continued your build as planned?

Yep that looks like the old septic tank and pipe running from your house. They usually fill them in but who knows if they did. I think you are gonna have to work around it to build your pond as not sure how much that would cost to remove. It could also be the runoff tank for washing machine etc. water as the neighbors at our old house in Everett had one in the back yard.

that pipe will seriously limit my depth at that section of the pond, which will be like 1/4 to 1/3 of the pond. it will be like 12 inches, shallow. if i wanted to continue to build there, should i lay down pea gravel over the pipe and some dirt before underlayment and liner?

looks like a Bog area behind the pipe - and a plant shelf (concrete circle) and a good excuse to double the size of your pond

yes very tempting to build a bog/wetland. i would have to push my pond to the right and have 3 feet before the yard begins to slope. i think i will build it as is w/ a very shallow end tho.

 

[texastkc]

what did u do with the collapsed pipeline? removed it and continued your build as planned?

We dug out the clay pipe pieces that were in our way. The drywell we turned into a place to house a trashcan filter we built that also works as a skimmer.

 

[addy1]

how did the discovery of the tank and lines affect your pond build? did u incorporate it? did u move it or change your plans/layout?

I had to move the dig over a bit and make sure I did not chop the pipe. We only have septic out here. So just a bit of readjusting. We did not have a inspection done on the house so had no idea where it was.

 

[Crimedog]

You cann dig below the pipe on each side - no rule says you can't have a ridge in the middle of the pond

 

[Mmathis]

Interesting!

 

[j.w]

I had my first pond built over the septic pipe to our septic tank that was still working. Just had a ridge on the bottom of my pond like @Crimedog posted. I kept it like that for a few years and then I wanted a bigger pond so I filled it all in. No issues w/that pond over the septic pipe and it was a big pipe!

 

[clark kent]

If you can be absolutely sure it's abandoned and not in use, you could turn that to your advantage. You can clearly see the curvature of the tank. From that you can estimate its diameter. A little further digging should reveal the opposite edges and any field lines. You don't have to remove it. Rent an electric jackhammer and break up the top. (Yeah, don't stand on it when you're doing this.) Just let the broken concrete fall into the bottom of the tank. You can break up the upper sides of it as deep as you need to with a sledge hammer and throw them in too. Then cover it to your desired depth with some fill dirt.

 

[Ax01]

You cann dig below the pipe on each side - no rule says you can't have a ridge in the middle of the pond

I had my first pond built over the septic pipe to our septic tank that was still working. Just had a ridge on the bottom of my pond like @Crimedog posted. I kept it like that for a few years and then I wanted a bigger pond so I filled it all in. No issues w/that pond over the septic pipe and it was a big pipe!

i was gonna have a formal edge using retaining wall block on the long side of the pond where u walk up to it from the house. the idea was to have this part the the deepest, most uniterrupted part of the pool. now that ol' septic tank disrupts things by taking up almost half this area up w/ a shelf.

if i keep the pipe there, i think i might make that other side of the pipe the formal edge for toe dipping if i keep it shallow. but i might dig in an oval another foot or so down on that side.

If you can be absolutely sure it's abandoned and not in use, you could turn that to your advantage. You can clearly see the curvature of the tank. From that you can estimate its diameter. A little further digging should reveal the opposite edges and any field lines. You don't have to remove it. Rent an electric jackhammer and break up the top. (Yeah, don't stand on it when you're doing this.) Just let the broken concrete fall into the bottom of the tank. You can break up the upper sides of it as deep as you need to with a sledge hammer and throw them in too. Then cover it to your desired depth with some fill dirt.

i'm waiting for the sewer company to get back to me or send someone out. so i'm 99% pretty sure it's abandoned. it wasnt mentioned when i bought the house as something to upkeep/service and have lived here 2 years. jackhammering the tank is a good idea but i think i'm just gonna use it as a pond/plant shelf. i would like to remove the pipe if possible tho.

 

[addy1]

Get the top off and you have a instant fish pond! Might want to throw in a liner!

 

[Ax01]

ok, this shoulda been obvious butt i learned today that if u dig too close to a pipe that had been laid in gravel, the soil wall will lose it's rigidity, collapse and the gravel will spill. well i guess i will have to reinforce that section w/ bricks or something.

Get the top off and you have a instant fish pond! Might want to throw in a liner!

it can be a pond in a pond!