Low cost septic riser material recommendations please

I’ve got some old septic tanks where the lids are significantly below grade. I intend to put in some risers myself and bring them up to grade.

I probably won’t be able to use any fixed form stuff without some way to stack them up to the right height. Any recommends on fixed or adjustable PVC or similar materials?

Is there any particular reason you can not use the manufactured concrete collar extensions intended for that purpose.

I’ve seen the round ADS plastic drainage pipes cut to length and used successfully. Like this. http://www.ads-pipe.com/en/market.asp?page=storm_water_drainage

You could buy one length and cut it to size. My only concern would be finding and installing a secure lid

@Greg, I haven’t priced it out yet. The septic designers/installers around here all use that ribbed PVC stuff more commonly. What do those concrete risers weigh?

@Coach. Thanks, I’ll check it out.

They come in 12 inch heights and weigh a couple of hundred pounds. It’s a two man job to place them but I have done it myself with a bit of leverage and ingenuity.
If it is common to use the PVC you might as well do the same. I assume they have some type of lid designed to fit the PVC .

We are on the hunt for the same thing. Went online as well as drove to several local supply stores. We also ended up getting the same advice in using the ADS plastic drain pipes and the price is quite a bit cheaper. We have concrete tanks so our biggest question was in sealing these to the top. We were told to use a roof cement or tar to create the seal. The local company we visited had Metal lids marked sewer that perfectly fit the pipe. Since this is obviously an alternative option not specifically used for this purpose, we are still shopping around but this seems like it would work.

Someone does make ADS plastic lids for these, I’ve seen them. I have no idea where to get them but they are out there.