Pond catch basin

[cosmaar1]

This is a question for all you guys who have built a pond before, more specifically the ones who have installed a catch basin type drainage system.

I’ve got a plan on how I’m going to do this, but doesn’t hurt to ask for other opinions as I have never done this before.

I’ve purchased a 2’x2’ precast concrete catch basin that I will have to knockout the side wall to accept my 15” double wall pipe.

Obviously I’m not going to be able to make a watertight hole between the concrete and pipe, so what do you all recommend for sealing the connection point?

In the research I’ve done, people use grout, hydraulic cement, etc., but I’m wondering which option is better or if I need to go a different way.

 

[CM1995]

This one is right up my alley.

First of all will a 15" dual wall HDPE fit in the side of a 2x2 knockout box? We don't use KO's that small, all the ones we use are 4x4.

For the connection I would suggest a 1:2 mixture of portland cement and sand. 1 shovel cement to 2 shovels sand. We also use Quickcrete stone veneer mix which you can buy at HD and only requires water. The veneer mix has admixtures that helps it stay put vertically and has some water proofing characteristics.

You will want a dry but workable mixture. It might take a couple of batches to get the right consistency. Start at the bottom of pipe and bring each side up at the same time. If the gap between the box and pipe is wide then small pieces of brick or busted concrete from the knock out side can be used to fill the void but don't let the pieces stick past the mortar as it can cause a leak.

Next step is to pour your concrete invert and make sure the concrete gets under the pipe to seal the bottom up. We like to bring the concrete up 2-3" around the sides of a 15" sized pipe in a 4x4 box not sure you'll have enough room in a 2x2.

Once the pipe is mudded inside and outside the box and the invert poured, I would suggest wiping it with water plug other wise known as hydraulic cement.

Safety Note: Hydraulic cement will burn your skin much more than regular concrete or mortar so you will need a set of heavy duty rubber gloves to handle it.

Hydro cement sets up quickly so you will have to work in small batches. Mix a small portion and wipe the inside of the mortar collar around the pipe. It'll take some time but this will help seal up the inside of the pipe.

If you really want a belt and suspenders approach then you could pour a concrete collar around the pipe where it enters the box on the outside. Throw some wood forms on either side and make sure the concrete can get under the pipe. It doesn't have to pretty just seal it up.

 

[StevenG]

I would add in to pour an anti-float block around the catch basin out of concrete so it is anchored and doesn't float. I've always used hydraulic cement for connections. I've also never used knock out boxes for ponds. Could you pour an inti float and then block it up instead?

 

[Steve Favia]

This is a question for all you guys who have built a pond before, more specifically the ones who have installed a catch basin type drainage system.

I’ve got a plan on how I’m going to do this, but doesn’t hurt to ask for other opinions as I have never done this before.

I’ve purchased a 2’x2’ precast concrete catch basin that I will have to knockout the side wall to accept my 15” double wall pipe.

Obviously I’m not going to be able to make a watertight hole between the concrete and pipe, so what do you all recommend for sealing the connection point?

In the research I’ve done, people use grout, hydraulic cement, etc., but I’m wondering which option is better or if I need to go a different way.

Around the Chicagoland area we would core a hole and use a boot with with a stainless steel expansion ring on the inside that use’s a boot tool for a water tight connection.

 

[Steve Favia]

Around the Chicagoland area we would core a hole and use a boot with with a stainless steel expansion ring on the inside that use’s a boot tool for a water tight connection.

Pretty much all the sanitary manholes come from the precast suppliers with the boots already installed around here

 

[StevenG]

 

[StevenG]

 

[CM1995]

I would add in to pour an anti-float block around the catch basin out of concrete so it is anchored and doesn't float. I've always used hydraulic cement for connections. I've also never used knock out boxes for ponds. Could you pour an inti float and then block it up instead?

I've never used a 2x2 knockout but we've put in too many 4x4's to remember with some in ponds. The 4x4's didn't need an anti-float due to our soil/water table conditions as the bases are 6-8" thick. Don't know about OP's 2x2 box but not a bad idea depending on his ground/water table conditions.

For us blocking or bricking an inlet is so labor intensive it's much cheaper to buy a pre-cast unit. If you are doing the work yourself then it could be a different story.

Around the Chicagoland area we would core a hole and use a boot with with a stainless steel expansion ring on the inside that use’s a boot tool for a water tight connection.

A 15" rubber boot and SS ring is over kill for a regular pond overflow. I can't imagine what a boot big enough to fit a 15" ADS N12 or equivalent pipe would cost.

 

[hvy 1ton]

First of all will a 15" dual wall HDPE fit in the side of a 2x2 knockout box? We don't use KO's that small, all the ones we use are 4x4.

15" N12 is 18" on the OD. If the KO has 4" walls, it won't fit. Local precast guy builds most boxes with 5" walls.

 

[CM1995]

15" N12 is 18" on the OD. If the KO has 4" walls, it won't fit. Local precast guy builds most boxes with 5" walls.

That's why I asked if it would fit. Not familiar with the box he's using.

Cosmar post a pic of your 2x2 box and some dimensions.

 

[cosmaar1]

That's why I asked if it would fit. Not familiar with the box he's using.

Cosmar post a pic of your 2x2 box and some dimensions.

I don’t have the basin near me, but OD it measured 36”. So that would make the walls 6”. I’m assuming the knockout portion is only an inch or two thick, but I won’t know until I put a hole in it to fit my pipe.

 

[cosmaar1]

Appreciate everyone’s replies. I wasn’t around a computer much the last 2 days so I will try to answer everyone’s comments to follow up.

According to the precast people, these boxes are typical around here. The guy at the shop told me they use a core saw to cut the hole and I wish I would have known that prior to buying the stupid thing. I would have asked they do it for me.

Regardless I appreciate the comments CM had regarding mixture. This is helpful as I was thinking about using grout.

In terms of a anti-seap collar, check this pic out. I had one precast to fit my pipe. Getting concrete back to my pond is almost impossible so this will have to do. I’m going to mix up a few bags of sackcrete for the base, but it should work good.

The picture with the pipe in the middle I borrowed from their website.

 

[CM1995]

That's a nice looking box. I am assuming the knock out portion is +/-24" so there is more than enough room to fit the pipe in.

We turn the boxes over on their side and cut a square hole in the KO, it's easier to stand on top of the box with a saw instead of trying to cut the hole vertically. Our round pre-cast comes with cast in holes but all the KO boxes come with no holes. Here knock out boxes are several $100 more per structure than custom 48" round structures.

Interesting pre-cast collar, we've always poured them in place. You can also dig a 2-3' wide (min) by 1' deep trench and fill it with a fine crushed stone or sand as a base in lieu of bag concrete mix. Don't use any clean type stone that water drains through it. I would also grout both sides of the pipe in addition to packing a good clay mixture around it.

 

[cosmaar1]

That's a nice looking box. I am assuming the knock out portion is +/-24" so there is more than enough room to fit the pipe in.

We turn the boxes over on their side and cut a square hole in the KO, it's easier to stand on top of the box with a saw instead of trying to cut the hole vertically. Our round pre-cast comes with cast in holes but all the KO boxes come with no holes. Here knock out boxes are several $100 more per structure than custom 48" round structures.

Interesting pre-cast collar, we've always poured them in place. You can also dig a 2-3' wide (min) by 1' deep trench and fill it with a fine crushed stone or sand as a base in lieu of bag concrete mix. Don't use any clean type stone that water drains through it. I would also grout both sides of the pipe in addition to packing a good clay mixture around it.

Very good tips and I like your idea with turning the box on the side. That will make things a lot easier.

 

[CM1995]

Also helps with the dust if you are not cutting with water.