Question about concrete block bog filter

[drjay9051]

I will be building a new bog filter with dimensions of 25x6. It will be built with concrete (cinder) blocks and total height will be 24 inches. I plan on having the gravel in the bog at a depth of about 12-14 inches. Most of my information came from the following link https://nelsonwatergardens.com/gravel-bog-filter-construction/

My only real concern are the walls of the bog.

Everything I have read regarding "retaining walls" and similar structures state that you must have a pored concrete footer to assure stability.Without a poured concrete footer you risk instability and collapse, or so they say.

Now since this will only be about 2 ft high and only contain gravel and water to a height of 12 inches do I really need a footer for stability?

The last thing I need is for the whole thing to shift and fall apart down the road. Previous bogs have been made from old stock tanks so there was no issue.

Has anybody on the forum constructed a bog filter using cinder blocks and if so did you pour a concrete footer or simply build on bare earth or bed of gravel?

Appreciate the help.

 

[GBBUDD]

first question is where are you located do you get below freezing?

secondly what type of soil do you have?

third is there a lot of water in your ground table?

but yes it can and will fail with certain steps being met for the questions above. i am in 6b and i am a builder , hereis a link to my build pond and bog theres answers to your questions in the retaining wall i built in the pond . same process ass would be for a bog in my area . and then there is the bog 20x8x6 it is large keep scrolling till you see captions or pictures for what your looking for

Honored and Proud to have been chosen Aquascapes DIY pond of the year for 2023. 12,000 Gallon Koi Pond, Full Build

Large KOI pond with a Wetland filter, Negative edge and an intake bay. Start to finish, Building, Maintaining and expanding / seaming . https://www.facebook.com/watch/live/?ref=watch_permalink&v=687652723148180

www.gardenpondforum.com

 

[drjay9051]

first question is where are you located do you get below freezing?

secondly what type of soil do you have?

third is there a lot of water in your ground table?

but yes it can and will fail with certain steps being met for the questions above. i am in 6b and i am a builder , hereis a link to my build pond and bog theres answers to your questions in the retaining wall i built in the pond . same process ass would be for a bog in my area . and then there is the bog 20x8x6 it is large keep scrolling till you see captions or pictures for what your looking for

Honored and Proud to have been chosen Aquascapes DIY pond of the year for 2023. 12,000 Gallon Koi Pond, Full Build

Large KOI pond with a Wetland filter, Negative edge and an intake bay. Start to finish, Building, Maintaining and expanding / seaming . https://www.facebook.com/watch/live/?ref=watch_permalink&v=687652723148180

www.gardenpondforum.com

Appreciate your reply. I will read about your build. I am in Zone 9 so rarely do we get below freezing. Frost,yes ice,no
No standing water

So may I ask rather than pouring a footer as money is tight what are your thoughts on laying a course of square patio stones as a base?

Again appreciate your expertise.

p.s.

Just looked at your masterpiece. What are you doing next weekend.

In a word MAGNIFICENT !!

 

[GBBUDD]

Appreciate your reply. I will read about your build. I am in Zone 9 so rarely do we get below freezing. Frost,yes ice,no
No standing water

So may I ask rather than pouring a footer as money is tight what are your thoughts on laying a course of square patio stones as a base?

Again appreciate your expertise.

p.s.

Just looked at your masterpiece. What are you doing next weekend.

In a word MAGNIFICENT !!

if you want it to last .. i would never build a concrete cinderblock wall just sitting on the ground. now if you have absolute solid compact type a soils i may think about a crushed gravel base, but again for long jevity i would build a footing with two pieces of rebar in it laying horizontally the length of the pour.

pavers could be used but it's not ideal, you would want to stager the joints but again not my first or 5th choice . Maybe in arizona you'd be fine but water / rains and frost have a way of changing ground topography and concrete is very inflexible any movement and it will c rack . even with footings it's very hard not to get a crack but it's due to expansion and contraction more than footings in this case.
would i build a 20x6 bog and have a grand in aqua blocks another couple in gravel and liner would i risk it for 500 bucks in concrete footings hell no , but i build things to last i hate trying to tear down my work it's a bear.

THANKS i have enjoyed building it and tinkering with it still

 

[drjay9051]

if you want it to last .. i would never build a concrete cinderblock wall just sitting on the ground. now if you have absolute solid compact type a soils i may think about a crushed gravel base, but again for long jevity i would build a footing with two pieces of rebar in it laying horizontally the length of the pour.

pavers could be used but it's not ideal, you would want to stager the joints but again not my first or 5th choice . Maybe in arizona you'd be fine but water / rains and frost have a way of changing ground topography and concrete is very inflexible any movement and it will c rack . even with footings it's very hard not to get a crack but it's due to expansion and contraction more than footings in this case.
would i build a 20x6 bog and have a grand in aqua blocks another couple in gravel and liner would i risk it for 500 bucks in concrete footings hell no , but i build things to last i hate trying to tear down my work it's a bear.

THANKS i have enjoyed building it and tinkering with it still

Thanks again.

My soil is good old central Fl. sand.

Your opinion/expertise,if I may ask
Is the footer something I can accomplish with a wheelbarrow and muscle or too big a job?

Im wondering if a concrete guy would come out for a job this small?
The stock tanks were easy but none near the size I need.

I really value your expertise as I just want to do this once.

.lastly,would filling the voids in the CMUs with sand be of any use as opposed to a footer?
Im thinking a

More mass would lend to greater stability?


FWIW if it matters I am placing pond liner in the bog not waterproffing the block and adding water without liner.

I know you know your business but when I envision a bog maybe 2 ft high I cannot visualize a failure as it is not holding tons of water but Murphy"s
Law...

 

[GaryMoz]

First good luck with it

My bog was built with blocks, although it was 5ft deep, so was on a footing strip.

If you want a vertical wall to the bog, I would probably put a footing in for the blocks, you could always use railway sleepers on there sides instead of blocks

 

[drjay9051]

Appreciate the help.
I have decided to go with railroad ties with steel fench posts driven along the perimeter every 2 feet
Thanks again

 

[GBBUDD]

Depending on the size of your sleepers every two feet sounds extreme. Sleepers / railroad ties here in the states are 6"x8"x8' and depending on size of the bog . If only 2 feet tall you'd probably need nothing more than some good timber nails to tie it all together. Over lap everything not to speak the obvious but I have seen other wise. Corners would not need anything .
Heck my upper Main bog is conventional frame 20 feet long with a diagonal brace at 10 feet and 2x4 walls with 2 layers of 3/4 pt

 

[drjay9051]

Depending on the size of your sleepers every two feet sounds extreme. Sleepers / railroad ties here in the states are 6"x8"x8' and depending on size of the bog . If only 2 feet tall you'd probably need nothing more than some good timber nails to tie it all together. Over lap everything not to speak the obvious but I have seen other wise. Corners would not need anything .
Heck my upper Main bog is conventional frame 20 feet long with a diagonal brace at 10 feet and 2x4 walls with 2 layers of 3/4 pt

Please explain what you mean by "overlap" Do you mean stagger the joints as is done with brick or concrete block?

 

[GBBUDD]

Yes stagger the joint from one later to the next . And in your corners and joints for the 20 foot wall overlap your joints. Like a log cabin half out of the top timber and half cut to the bottom for 6 inches or so.