liner install over retainer wall blocks?

[gcann]

Help please,

I'm working on a new pond and have a question, I had a hole dug but decided to shorten it and I used retainer wall block to cut the size by about 40%. The reason for the size change is because personally I didn't like the rectangular shape (18x11) and now have it at 11x11 with average depth of 30" and with a curved front and for me it seems like a reasonable size to enjoy and maintain.
The shelf at the top of the block is for a ledge of rocks which will be about 3 inches below the water line and the liner will go over the ledge, up the cinder block face and end under the 2" cap blocks on this back wall

Anyway my question is can I use 45 mil EPDM liner with 2 layers of 6 oz geotextile non-woven underlayment directly over the block wall or should I use some form of insulation board as a backer as well? The Vendor did say the double underlayment will protect the liner from cuts and the EPDM liner will form to the wall block under the water pressure....... which is what I had hoped.....just wanted to get a second opinion

thanks in advance for any suggestions
Greg

 

[combatwombat]

I had a hole dug but decided to shorten it

You know your plans and desires more than we do, but most of us would call that a "mistake."

can I use 45 mil EPDM liner with 2 layers of 6 oz geotextile non-woven underlayment directly over the block wall

Yes, two layers of underlayment under the liner should work fine. Even better would be some old carpet (check for pins/needles!). Better padding and free for the taking.

Enjoy the build and be sure to post lots of pictures as you go!

 

[poconojoe]

Great job you are doing.
I'm going to follow, so keep posting!

What do you intend on using for filtration?
A lot of us filter exclusively with wetland upflow bogs. No commercial filters.


What kind of fish, if any, do you plan on introducing?
I don't know how many gallons your pond will hold, but keep in mind that if you plan on koi, they do require a lot of space and a lot of filtration.
The general rule is 1,000 gallons for your first koi and 250-500 for each additional.

I use a digital water meter that screws onto my garden hose. It was about $20 on Amazon.
If you use something like that when you initially fill the pond, it would be helpful later.

 

[Mmathis]

When I used cinderblocks for part of my pond, I used an angle grinder to very aggressively smooth out any sharp or particularly troublesome places. Then I very aggressively covered those places with extra underlayment. BUT, this wasn’t the entire surface of the pond.

 

[gcann]

combatwombat - Funny you mention that, I had a pond at a previous home and enlarged it twice but I do believe this size will suit me at this point in my life and sometimes energy level. Thank you for your input on the liner.

poconojoe - I plan to have various kinds of goldfish, filtration is the biofalls pictured paired with an Atlantic skimmer. Based on size and depth it's going to be about 2200 gallons, I did order a water meter off Amazon last week so will be here in time for the initial fill.

mmathis - I did buy a grinding wheel for the cinder block shelves, haven't gotten to it yet

I joined months ago and have picked up great tips since joining......thanks for responding

 

[j.w]

@gcann

 

[poconojoe]

combatwombat - Funny you mention that, I had a pond at a previous home and enlarged it twice but I do believe this size will suit me at this point in my life and sometimes energy level. Thank you for your input on the liner.

poconojoe - I plan to have various kinds of goldfish, filtration is the biofalls pictured paired with an Atlantic skimmer. Based on size and depth it's going to be about 2200 gallons, I did order a water meter off Amazon last week so will be here in time for the initial fill.

mmathis - I did buy a grinding wheel for the cinder block shelves, haven't gotten to it yet

I joined months ago and have picked up great tips since joining......thanks for responding

Awesome!

Sounds like you have it all under control!

If you aren't familiar with shubunkin, check them out. They are in the goldfish family.
They are a nice fancy colorful fish with long flowing fins and they don't grow too large.

 

[GBBUDD]

Coming along nicely.......... y but as your asking a couple tweeks would make things more re assuring for long term

Yes epdm will easily stretch around the block HOWEVER you never want to stretch your liner . If anything you want to leave slack behind so if something should settle or shift there is extra material left behind instead of making the rubber stretch .

As mentioned those corners on the both sides at the bottom should be eased with a grinder.

6 OZ Non woven is respectful stuff but still a little light for what i would want to use. My go to is 8 oz and there is a couple other options you could do you can cover the wall in sand before you apply the fabric making it work far less. also there is a material its a roofing protection board it's fiberglass and a petroleum coating . not to be used inside the pond but under the liner it comes in a 1/8" 4x8' sheet and i would use one layer of fabric the 1/8" sheet and then the second layer that should be a comfortable piece of mind . https://www.iko.com/comm/wp-content...021-023-034-036-037-PDS-Protectoboard-3mm.pdf

The other observation i can see is your inverted corner on both side i would close those in 1. its a place for debris to build up

Water current can get in there effectively

Trying to catch fish will be a nightmare or it may help but i vote toward a nightmare..

Your bottom looks flat a bowl would help for debris to end up in one area . making it easier to clean.

The bottom of your 8 x16 cinder blocks have a shelf there as well that will need to have the edges eased as well. This spot creates questions with the protection board though as your have the blocks rounding in but the protection board and fabric will not be on that row alone i believe i would fill it in with some concrete. maybe take a strip of ply wood secure it to the block and fill all the round ins so you have a flat per say and level area to terminate the protection board let the fabrics and rubber step back in the shelf AGAIN LEAVING SLACK Just like is recommended for skimmers,

These are suggestions as i have never had your circumstances before if you place the underlayment over this area and it seems decent and you try your second layer and its feels strong as a bull maybe it will work my money would want more in my 40 years of construction

 

[gcann]

GBBUDD - thanks for the input and suggestion ........ sorry but can you explain this part please I'm not 100% clear, I also included a full pic of the pond

The bottom of your 8 x16 cinder blocks have a shelf there as well that will need to have the edges eased as well. This spot creates questions with the protection board though as your have the blocks rounding in but the protection board and fabric will not be on that row alone i believe i would fill it in with some concrete. maybe take a strip of ply wood secure it to the block and fill all the round ins so you have a flat per say and level area to terminate the protection board let the fabrics and rubber step back in the shelf AGAIN LEAVING SLACK Just like is recommended for skimmers,

 

[brokensword]

GBBUDD - thanks for the input and suggestion ........ sorry but can you explain this part please I'm not 100% clear, I also included a full pic of the pond



View attachment 140824

I'm not at all sure your retaining blocks aren't going to move on filling; usually, it's either back filled or the blocks are bound by poured concrete (not these blocks but rather, cinder blocks) + rebar. Just a thought.

 

[combatwombat]

I'm not at all sure your retaining blocks aren't going to move on filling; usually, it's either back filled or the blocks are bound by poured concrete (not these blocks but rather, cinder blocks) + rebar. Just a thought.

Looks like the pond is the backfill in this scenario (face of blocks are facing camera). Also, those blocks are confusing the heck out of me. They look like the solid type you'd find at a garden center w/ a lip on the back for alignment/setback, but then it looks like @gcann has rebar running through them and they're grouted like a standard cinder block.

 

[poconojoe]

Looks like the pond is the backfill in this scenario (face of blocks are facing camera). Also, those blocks are confusing the heck out of me. They look like the solid type you'd find at a garden center w/ a lip on the back for alignment/setback, but then it looks like @gcann has rebar running through them and they're grouted like a standard cinder block.

If you are referring to the wall in the foreground of the last picture, they seem to be concrete blocks with a nice finish on their face. They look nice.

I see he used rebar and the voids are filled with concrete.

The whole project is progressing nicely!

 

[Jagsfan]

@gcann I'll leave the more experienced people to give you advice, but i had a question on where you live? NE Alabama, where exactly? i grew up in Boaz, Albertville, Crossville area.

 

[gcann]

the decorative blocks along the front facing wall and the cinder blocks on the other 3 sides have rebar about 2' in the ground in each cell, poured concrete in each cell, and the front wall also has landscape block adhesive between each as well as horizontal rebar across the top to tie it all together. The left front side that is over 3 blocks high also has a wing wall to help support the end where the skimmer is set. The cinder blocks are against the ground on the other 3 sides. The front exposed blocks are 6" each and the water level is going to be about 14" up the block, meaning the water will average just over 2 blocks high. THis is my first pond with a wall above grade and has worried me but I feel I've taken steps to prevent any type of failure

Jagsfan - I'm closer to Crossville

 

[combatwombat]

You’ll be good to go. Soil puts a lot more pressure in a wall than water does.