Septic tank risers

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Old 07-03-14, 09:09 AM
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Septic tank risers

Bought my house about three years ago and want to get the septic tank pumped. My tank is 2 feet underground and I had a heck of a time finding it! There are no risers on it, so I don't want to go through all this again.

I called around and the septic companies will install risers but several of them said they don't seal the adapter ring to the concrete tank. The backfilled soil holds it on and the weight of the cement lid makes it seal. That doesn't seem like the best way to do it. From the research I've done online, all the adapter rings for sale talk about bolting them down or using a adhesive.

For the adhesive I see mention of a "foam sealant", like on this page:
Manufactures - Seal-R Products Tank Cover, Service Lid, Septic Tank Lid, Septic Cover, Seal-r Ring, Seal-r Lids, Safety Lids, Riser Pipe, Precast, Maintenance Pipe, Cast In Place Ring, Adaptor Rings

What is this and can I use this and not have to bolt it down? Or do you use both? My tank is 10 years old. Anyone have experience installing these risers?
 
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Old 07-03-14, 09:37 AM
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My local septic tank manufacturer makes risers specifically for retrofitting. They take a standard plastic riser section and cast a square concrete pad around it. The pad provides a broad flange to apply sealant and the weight holds it in place. Extra plastic riser extensions are then added on top as needed.

I excavate the top of the tank and clean the area where the riser will be installed. Then a rubbery, tar/butyl sealant is laid in a circle around the tank opening. The sealant is a rope about an inch in diameter and quite soft and sticky. Then the riser is set down on top with it's weight squishing the sealant and hopefully making a watertight seal.

 
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Old 07-03-14, 09:55 AM
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Pilot Dane,
Thanks for the info and the picture. I'm trying to go the route that doesn't involve casting concrete. I know it's an option but I don't have mine as dug up as the picture you show. My lids are dig up, and a little around them (although I will probably have to dig up more around the edges of the lid)

As far as using sealant rope, are you talking about when you attach the riser to the concrete pad? There is no bolting? Or did you cast the riser in to the concrete pad?

Trying to figure out if I need to bolt the adapter to my tank or if I can just use the correct sealant foam/tape. The adapter kits come with the tape you mentioned:
Septic Tank Risers & Lids - Polylok Septic Tank Risers

But I have seem some installations just using a foam sealant/adhesive. I'm not sure what type they are talking about though.
 
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Old 07-03-14, 01:13 PM
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Use the Poly-Lok adapter & Butyl Rubber to seal it to the tank.
I use tapcons instead of kwik bolts to hold down the adapter ring.
Then add risers until you are 4 - 6 inches above grade.
Then put the lid on.
There are other ways to do it, but this is the easiest.
We do this all the time & we have one inspector that likes to make us fill the tank & risers up with water to do a water tightness test & we always pass.
There is no foam that will seal the adapter ring.
 
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Old 07-03-14, 03:09 PM
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make us fill the tank & risers up with water to do a water tightness test
Never heard of this. Your tank will, under normal conditions never reach the level of the risers, much less exceed it. You would have to seal the exit to the drain field in order to run such a test. The original cast lid was less waterproof than the risers properly sealed and installed. The riser is not part of the water holding part of the tank, only an access point for inspection and pumping. You DO want it sealed to keep external water from filling in the tank, so the butyl rubber rope is a good thing to use. I used expanding drive pins on mine.

I can't believe the cost of the riser system you quoted in post 3. I have about $69 in each riser, including the bottom locking flange plate, two risers and the cap.

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Old 07-04-14, 07:50 AM
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The reason the inspector has us fill the risers up with water is to prove that they are watertight.
If no water can leak out no ground water can leak in.
It is only one inspector that makes us do that.
And yes the way septic tanks are made with just a concrete plug in a hole is not watertight.
 
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Old 07-04-14, 08:33 AM
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I would think flooding the outside of the riser prior to backfilling would indicate a good seal or not. I know it would save a bunch of water needlessly going down the field when released, and not as big a PITA.
 
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Old 07-04-14, 12:00 PM
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I would mechanically fasten your riser to the tank somehow. The cast concrete base makes installation easy if you have the equipment to handle them. I just use the excavator to set them in place. Poop I'm done. Without the machinery or manpower to lift a couple hundred pounds into place hammer drilling into your tank is probably the only option.

In my county there is no test for waterproofness of retrofitted risers. Obviously you want them sealed as best possible but in a retrofit application they are usually going onto tanks that had unsealed concrete plugs so the riser is an improvement even if it leaks some. The biggest benefit of sealing the riser for me is that dirt does not get washed in so when it's time to access the tank it's a simple matter of pulling the cap.
 
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Old 07-04-14, 05:39 PM
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Great info here. One guy I called recommended using roofing tar and just "sticking" the riser on to the concrete tank. Others use quick drying cement? I am trying to avoid bolting it because the position of the tank is 2 feet underground and getting a hammer drill down there would be cumbersome, but possible. Is there any danger in breaking the concrete when using the hammer drill and concrete wedge bolts? I would hate to make things worse.
 
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Old 07-05-14, 04:52 AM
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Yes, there is a risk of damaging the tank. It's one reason I prefer to let the mass of the riser w/ concrete hold it in place.

You could try a belt and suspenders approach. Use a heavy bead of tar or butyl to seal the riser to the top of the tank. Since it sounds like your hole is not over dug much larger than the riser size you could pour some concrete around the riser. It would help seal and stick it to the tank and the concrete's mass would help hold it down.
 
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Old 07-05-14, 08:39 AM
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Pilot Dane,
Thanks again for the info. I think this is the type of approach I will use. What type of concrete do you suggest? Also if I go the tar approach, what should I look for at the store? Thanks again!
 
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Old 07-05-14, 11:09 AM
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I'd either get a gallon bucket of roofing tar or the same stuff in a caulk tube. I like the red can/tube of rubberized tar but other brands would work as well.



Clean the top of the tank as best possible. You want the tar to stick to concrete and if you clean it well the rubberized tar can form a surprisingly strong bond to the concrete. I'd set the riser in place and trace around the inside and outside. Remove the riser and put down a really heavy bead of tar within the lines and push your riser down into the tar so it squishes out.

I don't know if one cement would be better than another so I'd just get a bag or two of regular concrete mix. Maybe mix it slightly wet so it can more easily flow into the ridges of your riser to further help lock it in place. Then when it's cured you've got the tar glueing the riser in place and the cement's weight and it's bonding to the tank. Put dirt on top and you've got that extra mass further holding it in place to withstand bumps from a lawnmower.

---
Now that you'll have easy access to the tank make sure you re-install the cement tank lid and screw the riser cap on with "funny" screws like torx or square drive. You don't want anyone (children) to fall into or explore the tank. The sewer gases are toxic and it's an anaerobic (no oxygen) environment so it's easy to die if anyone goes into the tank.
 
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Old 07-05-14, 12:21 PM
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Pilot dane,
Thanks again for the help. I think this is the route I am going. I'm not sure if my tank is completely level though, so I might have to put a couple shims in with the tar if I want a level riser. Or maybe I could just use that Butyl Rubber rope on one half to level it out, then go with the roofing tar.

With regards to the last part of your post... you talk about re-installing the cement tank lid. I was under the impression that you wouldn't need that lid anymore. In fact when I talked to the septic guy who is going to pump out my tank, he said don't install risers with the cement lid on because they are impossible to get out. My plan was just to get the lid for the cap of the riser which I believe is a water/airtight seal.

Also I'm not too worried about safety issues, the lid is going to be under grass by about 4-5 inches. So kids falling in or trying to explore it won't be an issue. But it's a good point. We had a kid a few years ago messing around with one and fell in and drown.
 
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Old 07-05-14, 04:06 PM
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I would not worry about trying to level the riser. Get it good enough and stick it in place.

Being only 2' down I'd try to save the concrete lid if possible especially if it's round. If it is square the odds are good that some day it will end up dropped into the tank. I don't have concrete lids on my tanks. They are too deep. It's sorta back to the belt and suspenders. If you can use your existing concrete caps why not use them? If the lifting wire breaks and you loose it into the tank then you go without but until then it's free protection.

If you are installing risers leave them above grade. That's a major reason for risers. And, 4-5" below grade is not enough to allow grass to reliably grow above so you're going to have a dead spot so you might as well leave them above grade and hit them with the mower.
 
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Old 07-05-14, 05:20 PM
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All this discussion about the "risers" has me feeling somewhat deprived. I installed a new concrete tank here in 1987, and never thought once about a riser . . . . until it came time to consider pumping the thing 10 years later; and the pumping contractor volunteered that we'd save $50 if we could expose the clean-out.

Even though we had been present when that tank was set, we couldn't find the clean-out to save our lives; pushed steel probes into the ground hundreds of times, and dug multiple false holes A day before the pumping was scheduled, we met with success; and said "never again" !

We arranged to get a 2 foot length of heavy 24" corrugated EDPM culvert cut and we simply sat it vertically onto of the tank, surrounding the concrete clean-out, and then placed one of those 24"green circular covers on top . . . . never thought about keeping surface water from attempting the tank from above. There's no seal around the base of that 24" culvert, and I see no evidence that any water collects in there or even travels through that area (a snake once molted and shed his old skin there) but that's all we've seen in 17 years of living with an un-sealed riser !

I'll be having a new baffle installed later this summer, and will ask my septic guy how I could have survived this long without that precaution . . . . no tar or caulk or anything like that; just gravity. All I can say is that the heat from the tank does ten to melt much of the snow off that cover, and we can now at least find the tank within seconds . . . . even in the winter if need be.
 
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Old 07-06-14, 04:15 PM
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What type of concrete to use? I'm guessing something that sets pretty quickly?
 
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Old 07-11-14, 02:01 PM
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My risers are leaking ground water into the tanks every time it rains. It's pouring in gallons per minute through the gap between the existing risers and the tanks, the level increases 1" every 20 minutes.

One of the companies I talked to said they would replace my existing risers using the Seal-R system posted above. I have 2 problems with this:
  • The instructions say to use expanding foam to seal the riser to the ring. They use Great Stuff. I called Dow Chemical and asked if that was an appropriate use for the foam, and they told me absolutely not. They said it would deteriorate underground like that and it's not meant for that purpose.
  • The riser itself has ridges. When the ground freezes and heaves or expands, it will pull the riser away from the tank. This will potentially cause your seal to fail.

Now, to be fair, the company that makes Seal-R says that they've been installing them this way with no problems since 1998. And they are in MN, where the ground freezes pretty solid.

However, I'm still concerned. My tank has filled completely 5 times so far this year, and I don't want to have to deal with this again. One of my thoughts was to still use the foam, but then put hydraulic cement over it to give it a little protection, or even some rubberized tar first, and then some concrete. Then I'd have 3 barriers that would have to fail before water could infiltrate. But, it's still ribbed, and I don't like that since I'm in an area that will freeze.

The Polylok stuff looks great. The sides of the risers are smooth. But, the risers require you to put them together in sections, which is just more joints to fail IMO.

No idea what I have now on there, but they are clearly not working.

Any other suggestions?
 
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Old 07-11-14, 02:30 PM
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The joints are sealed and locked tight. They won't leak. Your leak is at the bottom on the irregular surface. I agree to use a non hardening elastomeric type sealant under the riser flange.. It will require digging, but it's just gotta be done to stop the leaking, I guess.
 
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Old 07-11-14, 07:14 PM
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So, that Polylok stuff looked good, but I spoke with an excavating company today and they said those things are a huge PITA to keep them from leaking.

It was recommended to me to use tar strips to seal it to the tank (heated so they flow well). And, if I want to, I can add additional tar around the outside of the joint and cover that with hydraulic cement.
 
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Old 07-12-14, 03:45 AM
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We use Poly-Lok risers everyday & have no problem keeping them watertight.
They are a PITA when it gets cold, because they are harder to put together.
But then all you have to do it use a couple of pry bars.
I would not cover butyl rubber with hydraulic cement it will not last.
Hydraulic cement needs a clean oil free surface to adhere too.
 
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Old 07-14-14, 08:45 AM
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Why doesn't anyone use epoxy, or a foaming epoxy to adhere the risers to the tank? Seems like it would have much less chance of failure.
 
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Old 07-14-14, 01:17 PM
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To add, hydraulic cement isn't meant to adhere to anything. It is meant as an expansion agent to fill holes and cracks. I wouldn't use it in this instance. Why use epoxy? You have to mix it in large quantities and lay it in. Elastomeric compounds can be troweled on from the container or squeezed from a tube. Epoxy will harden. Elastomerics won't. Not sure what "foaming epoxy" is. If it foams, it will have air pockets in it that can leak.
 
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Old 07-21-14, 09:07 PM
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Wanted to check in again because I have since worked on this project. I am going to post some more info when its completely done but I have the risers on. I used roofing tar to try to seal the riser to the cement, it worked OK. I then used this cement:
Rapid Set 60 lb. Concrete Mix-03010060 at The Home Depot

and poured it around the edge. It seems to be doing OK. This cement is basically a hydraulic cement, is that correct? Also, is it acceptable to just dump the bag around the edge of the riser and spray some water on it? Or do I need to mix it properly before pouring it in?
 
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Old 07-22-14, 04:11 AM
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Your waterproofing will be the roofer's tar. The concrete will add stability to the joint. It is not hydraulic cement. Hydraulic cement expands as it chemically heats up to fill cracks and holes in concrete walls, etc. What you used is fine. Your method is ok as long as the wetting process was evenly done, not too wet, not too dry.
 
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Old 07-22-14, 09:11 PM
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Chandler,
Thanks for the reply and the info.

The other issue I have is, and I didn't realize this until I got it pumped out, I have a third lid... an inspection port for the filter. So I have to build a riser for this. It's only I believe a 6 or 8 inch cement lid. Any experience with this? I was talking to the guy who pumped my tank and he said get some PVC tubing with a cap.
 
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Old 07-23-14, 03:01 AM
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Not sure of your design, but my outlet riser is over the area where a filter can be placed in the tank, so placing a filter in the baffle is done through that riser.
 
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Old 07-23-14, 07:42 AM
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It's a separate lid on the top of my tank for the filter. Guess I will have to try to rig something using pvc
 
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Old 08-16-14, 10:34 PM
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Would a 10" diameter PVC pipe work? The lid for the filter is 7" wide so that should be enough to pull it up and then pull the filter out. Just wondering what to put on top of the 10" wide PVC tube. A simple end cap would probably be good and then maybe just tape it on? Don't want to spend $200 on a clean out lid
 
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Old 08-17-14, 05:46 AM
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Just like in the other thread you need to make sure you can remove the cap and remove & re-install the filter through that smaller diameter riser. A 10" diameter means you'll have to do everything with one hand or you'll have to make tools to work down in the riser. The filter will be 6" to a foot deeper than the lid so at best you might be lying flat on the ground to get your arm in far enough to reach it if you can reach it at all (you mentioned in the other thread that the lid is 24" below grade). And of course you won't be able to see what you are doing. It will all be by feel.
 
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Old 08-17-14, 06:24 AM
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Originally Posted by Pilot Dane
". . . And of course you won't be able to see what you are doing. It will all be by feel . . ."
Then it won't be much of an Outlet "Inspection" Port anymore at that stage, will it ?
 
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Old 08-17-14, 06:54 AM
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The riser for the inspection lid will only be a foot deep by 10" wide. The 7" lid should come right out with no problem. It might be a little bit harder to pull the filter out with this setup, but I saw the tool the septic guys used and it's probably about 4 feet long with a little grabber on the end. I don't think it will be a problem. The guy said the filter should be pulled out and inspected and cleaned every couple of years. Does anyone do this?!
 
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