General bog questions and build ideas

[Mr. Green Frog]

At some point (probably next spring) I'll be renting a mini excavator and extending a 4' wide catch basin trench that's currently about 40' long, to 65' and as deep as possible (10' to 12' deep) in that last 25', then backfilling with washed 3/4", to act like a dry well vs. a sump pit, so as to be overkill for the now common 1-3"+ downpours that basically flood out the yard. And I could snake a horizontal overflow drain from the pond to the dry well surface (I think) though have to devise an plan to keep water from running back to pond in event of sustained torrential rains managed to overflow trench and outpace current sump pit.

Anyhow, with all that going on, I think I have enough room to do a 20' x 12' bog that'd be semi oval in shape and follow rear contour of pond bank. Overflow drain pipe mentioned above would run right through the bog to the trench. Filled-in bog would be several feet above water level, and think I could do a waterfall feature off it's edge and over or through the bank back to the pond. I believe it could go as deep as the trench addition, though it'll be expensive to back fill 20' x 12' at a 10' depth = 125 tons of no.8's and would be at least 6 or 7 dump truck loads.

1. Assuming the pond is 20k gallons when at it's upper limit, how deep should the bog be if I go with a 20'L x 12'W bog perimeter?

2. Cleaning that large of a bog out would be incredibly demanding (even if it it was only once every 10 to 15 years). Was thinking of getting a smaller HF sewage ejector pump, and placing that in a vertical corrugated drain tile pipe or similar DIY pipe with holes and capping it and placing gravel over the cap. That way if all the waste is at the bottom, I could hopefully just pump it out occasionally and never have to worry about the gravel being moved?

3. I love the idea of bamboo and really want it in the yard, but understand it's incredibly invasive and difficult to remove w/o heavy machinery once mature, and needs it's root system contained or restrained. Was thinking about lining the bog pit with liner and planting some bamboo in it? OR if it'd get too densely packed and overpower the bog's capacity eventually, I could maybe place vertical pvc pipes into the no.8's, just below or at the surface, about 36" deep, fill them with no.8's, and use those like planters? Or conversely, place a bunch of vertical corrugated pvc sections into the bog (think of a honeycomb pattern), fill them in with no.8's and plant the bamboo around those instead of IN them? That would allow the gravel inside of those corrugated sections to remain clear of the roots (I think) and force the bamboo to grow around them instead and leave gaps in the bog where the pipes are (honeycomb pattern). I think that would help limit density assuming it's something that needs to be accounted for?

3a. If bamboo for some reason isn't a good choice or is toxic, etc., how about cat tails?

4. If water gets pumped to the bog, where should the water enter in at? Say I do a 5' deep hole. At what depth should the water from the pump enter that hole from the side? Or should it enter up high and hit a 90 degree turn down? If so, how close to the bottom of the hole should that turn down get?

4a. Should I use a submerged spray bar with downward holes? Or just let it flow in straight from the pipe?

5. The return line, I put a downward facing 90 near top of bog then run horizontal section out? So it fills low and rises?

5a. If doing a waterfall, suppose I could place some concrete patio pavers, in a horizontal line on pond bank at bog edge, set a few blocks vertically at either end, creating a " []__ __ __ __ __ __[] " channel. Water from bog would have to rise high enough to flow "through" the channel. I kind of have an infinity pool edge in mind. So only top surface water would leave the bog. That'd work?

6. Just to be clear, you have to have plants growing in the bog area correct? Is the bog not effective until they are fully grown?

7. Washed no. 8's or no. 9's are what you guys use? So entire hole gets filled with them? So a hole, filled with the gravel, a feed line from the pump, then a return line back?

8. Last one. My pump is presently in a 4' x 4' sump pocket in exposed clay (rest of pond floor is 601d and 601b rip rap) near center of pond. Pump needs to be below frost line but I see some of you use skimmer boxes? Does 6" of pond ice or freezing damage the boxes? And your pump is at the bottom of your pond too?

8a. If I keep the pump where it is, but did some type of skimmer box then plumbed it down to the pump, any issues to be aware of, other than complexity of pipe layout and preventing starvation to the pump?

 

[addy1]

Cleaning that large of a bog out would be incredibly demanding (even if it it was only once every 10 to 15 years)

I have never cleaned mine, built and running 2010, draw water from about a foot from the bottom of the pond, keeps big debris out of the bog.

I love the idea of bamboo and really want it in the yard, but understand it's incredibly invasive

They sale clump bamboo, it tends to not spread like the bamboo that spreads by runners. I think I have read the roots of the bamboo can go through your liner so be careful.

If water gets pumped to the bog, where should the water enter in at?

It can enter high or enter at the bottom. Mine is plumbed through the liner into the bottom of the bog. I could have entered high and just plumbed it to the bottom of the bog .

Should I use a submerged spray bar with downward holes? Or just let it flow in straight from the pipe?

Mine are 26 foot long pvc pipes with slits cut into them facing down for the out flow of the water.

creating a " []__ __ __ __ __ __[] " channel. Water from bog would have to rise high enough to flow "through" the channel. I kind of have an infinity pool edge in mind. So only top surface water would leave the bog. That'd work?

yes

Just to be clear, you have to have plants growing in the bog area correct? Is the bog not effective until they are fully grown?

no the bog starts working as the water flows through it, better as the plants grow.

Washed no. 8's or no. 9's are what you guys use? So entire hole gets filled with them? So a hole, filled with the gravel, a feed line from the pump, then a return line back?

We did not wash ours. Too much to wash and it was a dry year on a well.
the return is the water fall back into the pond.

 

[Jhn]

Just to add, do not use just traditional no.8’s in the construction sense, as that stone is angular and will pack together you want to use pea gravel ranging from 3/8” to 3/4”.

Also just burying a pipe/snorkel in the bog for a pump out point won’t work, if you fill it with all pea gravel. You need ideally a void space at the bottom of the bog created either with aqua block, milk crates or large rocks starting at 12-18” or so, then graduate up to the top of the bog getting smaller as you go, ending with a foot or two of pea gravel. The bottom of the bog should be dug out so everything slopes to the snorkel, which is the low point of the bog. If going this route it matters not how you plumb into the bog, but when it gets to the bottom you want the feed pipe go8ng into a large horizontal tube at least 12” in diameter that connects over to the snorkel/clean out pipe. This will allow any solids/fines getting pumped into the bog to settle out as the flow slows down in the larger space, then it eventually will work its way towards the vertical clean out pipe. Then as the water rises up through the gravel it speeds back up, and your return to the pond can be just about anything a waterfall, a stream etc..
Purpose of the bog is two or even three fold, the gravel provides a lot of SSA for nitrifying bacteria to colonize, and also a media for plants to root into, which will also use up ammonia/nitrates to grow, and bogs with void space ie a settling chamber can help keep the pond proper clear of floating fines, then can be pumped out occasionally as needed.

Also, would skip the traditional bamboo and cattails in the bog, way to invasive and have massive tough root systems that will jam up the bog eventually. Traditional bamboo growing by runners, will jump over most things ie a pipe that you try to contain it with unless the pipe is left well above gravel level, even then have seen it jump up and over edging that is a foot above ground level.

Pump does not need to be below frost line, unless you turn it off. My pumps run year round, have some in skimmer boxes and sone Currently in a intake bay. Have never had an issue with a skimmer box cracking due to ice, in the 25 years or so I have had them.

You want your pump elevated off the bottom of the pond, unless as you suggested you leave it down there but plumb the intake into a skimmer box. The idea is to pump nutrient rich pond water into the bog, but not any solids that slowly can accumulate on the pond bottom.

 

[GBBUDD]

At some point (probably next spring) I'll be renting a mini excavator and extending a 4' wide catch basin trench that's currently about 40' long, to 65' and as deep as possible (10' to 12' deep) in that last 25', then backfilling with washed 3/4", to act like a dry well vs. a sump pit, so as to be overkill for the now common 1-3"+ downpours that basically flood out the yard. And I could snake a horizontal overflow drain from the pond to the dry well surface (I think) though have to devise an plan to keep water from running back to pond in event of sustained torrential rains managed to overflow trench and outpace current sump pit.

Anyhow, with all that going on, I think I have enough room to do a 20' x 12' bog that'd be semi oval in shape and follow rear contour of pond bank. Overflow drain pipe mentioned above would run right through the bog to the trench. Filled-in bog would be several feet above water level, and think I could do a waterfall feature off it's edge and over or through the bank back to the pond. I believe it could go as deep as the trench addition, though it'll be expensive to back fill 20' x 12' at a 10' depth = 125 tons of no.8's and would be at least 6 or 7 dump truck loads.

1. Assuming the pond is 20k gallons when at it's upper limit, how deep should the bog be if I go with a 20'L x 12'W bog perimeter?

2. Cleaning that large of a bog out would be incredibly demanding (even if it it was only once every 10 to 15 years). Was thinking of getting a smaller HF sewage ejector pump, and placing that in a vertical corrugated drain tile pipe or similar DIY pipe with holes and capping it and placing gravel over the cap. That way if all the waste is at the bottom, I could hopefully just pump it out occasionally and never have to worry about the gravel being moved?

3. I love the idea of bamboo and really want it in the yard, but understand it's incredibly invasive and difficult to remove w/o heavy machinery once mature, and needs it's root system contained or restrained. Was thinking about lining the bog pit with liner and planting some bamboo in it? OR if it'd get too densely packed and overpower the bog's capacity eventually, I could maybe place vertical pvc pipes into the no.8's, just below or at the surface, about 36" deep, fill them with no.8's, and use those like planters? Or conversely, place a bunch of vertical corrugated pvc sections into the bog (think of a honeycomb pattern), fill them in with no.8's and plant the bamboo around those instead of IN them? That would allow the gravel inside of those corrugated sections to remain clear of the roots (I think) and force the bamboo to grow around them instead and leave gaps in the bog where the pipes are (honeycomb pattern). I think that would help limit density assuming it's something that needs to be accounted for?

3a. If bamboo for some reason isn't a good choice or is toxic, etc., how about cat tails?

4. If water gets pumped to the bog, where should the water enter in at? Say I do a 5' deep hole. At what depth should the water from the pump enter that hole from the side? Or should it enter up high and hit a 90 degree turn down? If so, how close to the bottom of the hole should that turn down get?

4a. Should I use a submerged spray bar with downward holes? Or just let it flow in straight from the pipe?

5. The return line, I put a downward facing 90 near top of bog then run horizontal section out? So it fills low and rises?

5a. If doing a waterfall, suppose I could place some concrete patio pavers, in a horizontal line on pond bank at bog edge, set a few blocks vertically at either end, creating a " []__ __ __ __ __ __[] " channel. Water from bog would have to rise high enough to flow "through" the channel. I kind of have an infinity pool edge in mind. So only top surface water would leave the bog. That'd work?

6. Just to be clear, you have to have plants growing in the bog area correct? Is the bog not effective until they are fully grown?

7. Washed no. 8's or no. 9's are what you guys use? So entire hole gets filled with them? So a hole, filled with the gravel, a feed line from the pump, then a return line back?

8. Last one. My pump is presently in a 4' x 4' sump pocket in exposed clay (rest of pond floor is 601d and 601b rip rap) near center of pond. Pump needs to be below frost line but I see some of you use skimmer boxes? Does 6" of pond ice or freezing damage the boxes? And your pump is at the bottom of your pond too?

8a. If I keep the pump where it is, but did some type of skimmer box then plumbed it down to the pump, any issues to be aware of, other than complexity of pipe layout and preventing starvation to the pump?

1. A 10 foot deep hole is a challange both in actually digging it as you only get one shot most excavators can only dig to 12 feet and that's only very close to the machine.
The soils that you have better be a solid b or shorring or benching will be needed at now your talking a big hole.

2. After 4 years next to nothing has developed in my bog and I have 24 inch corrugated pipe down there and a foot deeper snorkel bottom for sediments to land and get trapped 4 years latter nothing to speak of in the trap. I would place the snorkel on as much of a pitch as you can so any sediment does go to one end.
3 I believe black bamboo is not to invasive but it may depend on clim
4. A pvc disbursing pipe at the bottom may be beneficial to force any build up to the snorkel trap.
5. No comment not my cup of tea
6.not necessarily but you would need to have great water to start with and don't overstock the pond . Plants are more then a big part of completing the cycle. They thrive on phosphates something bacteria is not big on absorbing.
6. If your talking the depths that you are for your bog I would hands down use aquablocks " there are many makers out there today but from what I have seen and used aquablocks are the strongest. It's like creating a hotel with an open buffet for bacteria and microbes and water creatures a place to move and forage.
7. I used 3/4 river rock for my main staple mixed more with 3/8 pea stone at the top. Just pumped to the bottom to one end of a centipede then just let the water flow up and trough the layers of gravel on its own that's the filter. Now if no aquablocks are used the simply lay a series of pipe making even displacement across the bottom. I don't like having more then a 16 space between the pipes so the water only has to travel 8 inches so there are no dead spots
8. It sounds like you have a earthen pond? The pump should never lay on the clay

 

[combatwombat]

Alright. Let's get started!

Overflow drain pipe mentioned above would run right through the bog to the trench.

Let's clarify this first. Are you saying this overflow pipe is taking runoff from your landscape to the trench? And the pipe is bisecting the bog somehow? Penetrating the liner to go through it? Going over top of it? Landscape runoff is on one side of bog and is being directed to drywell trench on other side of bog? Can you make a quick diagram to help us visualize?

I believe it could go as deep as the trench addition, though it'll be expensive to back fill 20' x 12' at a 10' depth

Way too deep. Would be challenging even to dig. When we talk about deep bogs, we're mostly talking about bogs that are deeper than the 12" pea gravel style bog. Once you have more than about 3-4' of gravel, you're going to start running into issues with depleted oxygen in the bog, which will invite anaerobic bacteria, which you don't want. Can probably be addressed by adding lots of oxygen throughout the bog, but an unnecessary complication.

The 5' deep bogs we talk about here still only have about 2-3' of gravel medium in them. The rest of the depth is comprised of a centipede trench, snorkel pit, standing water, and liner clearance above water.

Also, I think after you get to more than about 3' of gravel, you're going to run into issues backflusing the bog no matter how you design it.

And like @Jhn said, don't use angular gravel.

1. Assuming the pond is 20k gallons when at it's upper limit, how deep should the bog be if I go with a 20'L x 12'W bog perimeter?

Good question, but probably doesn't matter that much. I wouldn't go deeper than about 5-6' max with 2-3' of gravel medium. Turnover is important, but when sizing a bog, ratio of surface area to pond is more important. Bog surface area = 10% of pond surface area is probably good enough for a really big pond with very light fish load. Bigger surface area is better. Dedicated koi ponds like to see 50%.

2. Cleaning that large of a bog out would be incredibly demanding (even if it it was only once every 10 to 15 years). Was thinking of getting a smaller HF sewage ejector pump, and placing that in a vertical corrugated drain tile pipe or similar DIY pipe with holes and capping it and placing gravel over the cap. That way if all the waste is at the bottom, I could hopefully just pump it out occasionally and never have to worry about the gravel being moved?

Good thought, but is not going to work without a void space at the bottom that you can backflush trapped waste into so that it can migrate to this vertical pipe. @Jhn and @GBBUDD both mentioned the importance of this void space in deeper bogs. I am in the middle of building mine right now. Follow link in my signature to see progress. I am using reinforced milk crates below gravel.

I love the idea of bamboo and really want it in the yard, but understand it's incredibly invasive and difficult to remove w/o heavy machinery once mature

Really depends on what kind you get. There is running and clumping bamboo. Running does what it says... runs. Clumping behaves itself. Within those categories, there are fast runners and slow runners. There are tight clumpers and loose clumpers. All said, tight clumpers will be the easiest to manage. They do not require containment. Runners will spread to path of least resistance, thus the containment barrier. Clumpers are going to go where they want to go (but they don't go far), and you're probably not going to stop from going there short of a rhizome pruning. They can exert pressure like a tree would as a root gets larger and buckles a sidewalk. So choose a tight clumper, learn its mature diameter, and plant accordingly.

Was thinking about lining the bog pit with liner and planting some bamboo in it?

I don' think it will work. Bamboo doesn't like wet feet. It wants well drained soil. At least all the ones I know of. But there are thousands of varieties, so maybe there are some that will work. Believe there are only two families of clumpers that will thrive in most US climates. Fargesias do well in the north, won't like it in the south. Bambusas do great in the south, but aren't very hardy in the north.

4. If water gets pumped to the bog, where should the water enter in at?

Bottom. Doesn't matter too much how you get it to the bottom, but that's where you want it to enter. Piping over the liner and down, or bulkhead just below surface of gravel would be my choice. I would not want a bulkhead buried 10' deep. Asking for a nightmare.

4a. Should I use a submerged spray bar with downward holes? Or just let it flow in straight from the pipe?

Just let it flow in. Flow it into a big pipe/settling chamber. You want the velocity of water as slow as possible when it enters the bog.

5. The return line, I put a downward facing 90 near top of bog then run horizontal section out? So it fills low and rises?

I don't understand this question.

I kind of have an infinity pool edge in mind. So only top surface water would leave the bog. That'd work?

That's the idea. Water needs to work its way up through gravel and plant roots before exiting back to pond.

Just to be clear, you have to have plants growing in the bog area correct? Is the bog not effective until they are fully grown?

You don't have to. It will work much better planted, though. Looks better, too.

7. Washed no. 8's or no. 9's are what you guys use? So entire hole gets filled with them? So a hole, filled with the gravel, a feed line from the pump, then a return line back?

Deep bogs meant to be backflushed should use graduated gravel sizes and no bog should use angular gravel. I have 3 grades of gravel going into my bog. Bottom is 4-8" river cobble. Middle section is 1-2" drain rock. Top is pea gravel.

 

[brokensword]

Alright. Let's get started!


Let's clarify this first. Are you saying this overflow pipe is taking runoff from your landscape to the trench? And the pipe is bisecting the bog somehow? Penetrating the liner to go through it? Going over top of it? Landscape runoff is on one side of bog and is being directed to drywell trench on other side of bog? Can you make a quick diagram to help us visualize?


Way too deep. Would be challenging even to dig. When we talk about deep bogs, we're mostly talking about bogs that are deeper than the 12" pea gravel style bog. Once you have more than about 3-4' of gravel, you're going to start running into issues with depleted oxygen in the bog, which will invite anaerobic bacteria, which you don't want. Can probably be addressed by adding lots of oxygen throughout the bog, but an unnecessary complication.

The 5' deep bogs we talk about here still only have about 2-3' of gravel medium in them. The rest of the depth is comprised of a centipede trench, snorkel pit, standing water, and liner clearance above water.

Also, I think after you get to more than about 3' of gravel, you're going to run into issues backflusing the bog no matter how you design it.

And like @Jhn said, don't use angular gravel.


Good question, but probably doesn't matter that much. I wouldn't go deeper than about 5-6' max with 2-3' of gravel medium. Turnover is important, but when sizing a bog, ratio of surface area to pond is more important. Bog surface area = 10% of pond surface area is probably good enough for a really big pond with very light fish load. Bigger surface area is better. Dedicated koi ponds like to see 50%.


Good thought, but is not going to work without a void space at the bottom that you can backflush trapped waste into so that it can migrate to this vertical pipe. @Jhn and @GBBUDD both mentioned the importance of this void space in deeper bogs. I am in the middle of building mine right now. Follow link in my signature to see progress. I am using reinforced milk crates below gravel.


Really depends on what kind you get. There is running and clumping bamboo. Running does what it says... runs. Clumping behaves itself. Within those categories, there are fast runners and slow runners. There are tight clumpers and loose clumpers. All said, tight clumpers will be the easiest to manage. They do not require containment. Runners will spread to path of least resistance, thus the containment barrier. Clumpers are going to go where they want to go (but they don't go far), and you're probably not going to stop from going there short of a rhizome pruning. They can exert pressure like a tree would as a root gets larger and buckles a sidewalk. So choose a tight clumper, learn its mature diameter, and plant accordingly.


I don' think it will work. Bamboo doesn't like wet feet. It wants well drained soil. At least all the ones I know of. But there are thousands of varieties, so maybe there are some that will work. Believe there are only two families of clumpers that will thrive in most US climates. Fargesias do well in the north, won't like it in the south. Bambusas do great in the south, but aren't very hardy in the north.


Bottom. Doesn't matter too much how you get it to the bottom, but that's where you want it to enter. Piping over the liner and down, or bulkhead just below surface of gravel would be my choice. I would not want a bulkhead buried 10' deep. Asking for a nightmare.


Just let it flow in. Flow it into a big pipe/settling chamber. You want the velocity of water as slow as possible when it enters the bog.


I don't understand this question.


That's the idea. Water needs to work its way up through gravel and plant roots before exiting back to pond.


You don't have to. It will work much better planted, though. Looks better, too.



Deep bogs meant to be backflushed should use graduated gravel sizes and no bog should use angular gravel. I have 3 grades of gravel going into my bog. Bottom is 4-8" river cobble. Middle section is 1-2" drain rock. Top is pea gravel.

very well said, CW.

 

[Mr. Green Frog]

Thank you guys for the excellent replies! I'll add pics later and hopefully give a better idea and maybe do a crude top-down illustration if I have time and upload as a pic.

I have room to work in the yard to a degree, and want to knock everything out in one go. Will also need to trench electrical conduit in other area of yard, so trying to plan as much now in my head as possible.

Ground is tan colored clay and soil is maybe top 6", though yard has been messed with at different stages in it's life from what I can tell. After a couple feet, it's mostly gray clay. So very solid area.

Milk crates could essentially line the bottom, side by side in a grid fashion then (guessing some cut vertical pipe under each in center would reinforce) to create the cavity at the bottom? Then stack rocks on them, working up in size? If crates are roughly 12" tall, then a 4' depth would be suitable to maintain a 3' bog above them?

@combatwombat 90 degree down-facing elbow with pipe running horizontal off other end. Water rises to the elbow and flows out horizontal, was what I meant. I like the idea of the " []__ __ __ __[] " channel instead. Actually need to pull up some 6" slabs that are above grade near house and messing with water flowing through yard during down pours, so might be able to repurpose some of it for water to flow over vs. using pavers.

Will research more into clumping bamboo.

What about tall ornamental grasses? Some of the wheat-looking stuff at sides of the highways get over 10' and I've seen them growing in swampy areas.

 

[Mr. Green Frog]

Mud pics were beginning of spring. Grass pics are current. Still a work in process, with trench being an experiment and not finished as it needs reworked. Shed in back was rebuilt from the posts up, and looks different now, but is same yard at different angles.

First pic, pond banks are on upper right, oak tree in middle of back yard is reference point in trench pics. I'm at left rear corner of house facing North.

Trench after initially digging it and still building hill on right, shed would be on my right at that angle. Small pine is reference. Facing N/W:

Another shot, further away. Lower left where gravel was is near pond slope and where bog will most likely go. N/W

Same shot but more recent. Trench is in middle, I'm standing about where new addition of deeper trench will go if just lengthened an extra 25'; left is where bog would go:

Opposite end of trench, facing East. Oak is upper right, bog would be further upper right:

Close up, bog would be in front of smaller maple tree upper right (left standing water in trench for the new baby frogs that seem to prefer it over pond; sump pit was a proof of concept basically and not finalized):

Standing on pond shore and looking north again. Rebuilt pole shed in rear left/center. Waterfall would be about where clay dirt is at very bottom near feet. The small weeping cherry tree will probably be relocated, but left black plastic to right rip rap (small maple in earlier east facing shot is right there) is about 20' and then front to back would be 12'. The rip rap rocks and black plastic near center is at least 12' back from mud mound (camera seems to have hidden glamor filters, which makes scale and depth seem smaller as the yard is insecure). Mound is actually about 12" above the weeping cheery tree grade. Thinking of 6" x 6" x 10' post, laying side by side by side as a bridge to cross gap of extended trench, which would run east to west in pic and bridge would be north/south.

Different angle which appears smaller than actual or slight fish eye effect; 55 gallon is at least 3' tall, and mud bank mound is almost same height. If new trench goes about 8' to 10' at deepest point (10' depth measured from a slightly elevated starting position vs. weeping cherry tree grade), it would probably be around 5 to 7' feet below bottom area of 55 gal. current location. I want to run horizontal 4" pvc overflow pipe from a later to be determined pond crest point so it'll drain to trench if needed. Guessing trench needs it's own over flow running to yard in event it gets too high or power goes out.

I'm tired and it's crude (I don't do any of these things for a living, just a necessity and hobby at this point), but basic diagram from a top down perspective. Very rear of the yard is higher and slopes south towards house and pond. Trench currently interrupts a huge chunk of that and shed area was graded away towards the north, for what it's worth. But trench needs to be more robust and extra plus taking possible overflow from pond.