Seeking comments - first pond design

[AussieGardener]

Hello everyone,

I'm a little nervous about the size of the following undertaking, but excited at the same time.

Here are the points, followed by my questions and request for comments :

Climate zone C - Moist Subtropical Mid-Latitude Climate - Maryland, close to Washington DC. Clay soil. Partial shade from some large overhead trees, but plenty of sun also.
Large area with which to work, with steep up flow slope - at least 50 feet, aprox 25% grade. There's even more land available beyond the flat area at left of drawing.
Existing concrete pond/pool (not sure of original design intention - maybe a kiddie pool back in the 60's?) - weird, unnatural shape, but loved by our local frogs and plants. Constructed with some sort of brass drain fitting, also plumbed with copper line for refilling.

Proposed - transfer our frogs into a temporary holding, while I excavate new pond upslope, along with bog, and demo entire concrete patio area/concrete pond
Rebuilt patio to have a natural-shaped pond, grassed/pavers surrounds. Water fall coming over the old retaining wall and landing in this lower pond

Questions/seeking comments
Existing hollow upslope - best used for pond, or bog?
These ponds - any reason to locate drains in their base? (I don't understand what the benefit would be)
Pump and filtration, or just pump? (thinking that an installed bog may obviate the need for filtration. The frogs seem to thrive in the existing, non-flowing water, loaded with plant materials, and with soil migrating down into it from back yard). They're VERY entertaining!
I would have loved to retain some of the existing concrete pond, by doing a cutdown/re-shape. But I am guessing that there is no way to reliably add concrete to existing concrete after doing a partial 'slice and demo' - it would always be prone to leaking where the new met the old.

I am looking forward to hearing from others, and want to thank everyone for the great information already available here. It's fantastic to be able to share so much knowledge.

 

[TheFishGuy]

What a strange little basin! I like your plan, plus the slope will provide for a wonderful waterfall when it is all finished.

 

[bagsmom]

Very cool!!!! This will be a fun project to watch!
I know our other more experienced pond-builders will have good advice. The big thing I see that could be a potential problem is if too much runoff goes down the hill into the pond. Does that happen now? Like with heavy rains?
People build waterfalls on hills all the time, though -- it will just require some thoughtful and strategic planning to avoid that problem. I can't wait to see your build - and I love all the frogs!

 

[GBBUDD]

Climate zone C - Moist Subtropical Mid-Latitude Climate - Maryland, close to Washington DC. Clay soil. Partial shade from some large overhead trees, but plenty of sun also.

our in zone 6b or 7a
Y

Very cool!!!! This will be a fun project to watch!
I know our other more experienced pond-builders will have good advice. The big thing I see that could be a potential problem is if too much runoff goes down the hill into the pond. Does that happen now? Like with heavy rains?
People build waterfalls on hills all the time, though -- it will just require some thoughtful and strategic planning to avoid that problem. I can't wait to see your build - and I love all the frogs!

YOUR NOW ONE OF THEM

Proposed - transfer our frogs into a temporary holding, while I excavate new pond upslope, along with bog, and demo entire concrete patio area/concrete pond

WHY DEMO CONCRETE POND IS IT LEAKING? OR DO YOU WANT A DEEPER POND ?

 

[GBBUDD]

I can not see the condition of the patio but unless it is in realy bad shape i wouldn't be so quick to demo it.
The pictures appear that the deck has a good pitch so that the water is shedding away from the house.
Why not use the existing as a base layer for concrete pavers. any loose flag stone remove or reset in mortar, if it's only a couple. then apply a thin layer of sand like an inch or two and then place pavers on the sand as the patio ages in time you pull up a bad block and put a new one in. a heck of a lot cheaper then rip and tear out everything.

I would make the pond are deeper and larger but i like a bigger pond area . that's just me . i'd bring it right up to the retaining wall i'd make a shallow bog are off to each side but not balanced. and have the main falls cut into the retaining wall and boulders make the character stones and water fall. having a static bog to each side will catch the splash. then if you want the real deal you can make the stream coming down the slope and a bog sitting up on the hill.

 

[addy1]

Welcome to the forum!

This will be one neat project to follow along and it will be beautiful when done.

 

[AussieGardener]

Hello everyone, and thanks for the excellent input. I could have sworn I posted quite a while back, but whatever I wrote did not stick for some reason.

After much delay, and weather to deal with, the entire concrete patio has been demolished and removed. Probably 25 tons worth, and the concrete pond in particular was very heavily constructed.

The area is now under sod, with the exception of the original cut-out of the concrete pond. I'm running into some issues prepping it for a protection and then liner layer. I have enlarged, and reshaped compared to the original. It's almost large enough to take full advantage of a 20' x 25' 45 mil pond liner.

Here are the issues at this stage of the project :

1. The weather! This is clay soil. I have siphoned out the pond multiple times, only to have it refill with heavy rainfall and wild storms. Each time, a proportion of the frogs come right back from their temporary accommodations (kiddie pool). They've just go so much personality! It takes about a week of drying before the emptied pond has a workable consistency.

2. Issue - construction of cut-in 'shelving', 12"-14" in depth, to support perimeter plants and rocks - hard to do when the hole is already cut out. I have not quite figured this out. It's almost as if I need to make wooden forms, wet the soil to a pliable consistency, and then pour it into place (and there's that weather issue again, haunting me).

3. Leveling off the edges. See photos. There's currently about a 6" height difference between the back edge of the new pond (the one adjacent the old stone retaining wall) and the 'front' edge - the one closest to the house. Excavating further down along the back brings me to a submerged drainage pipe - can't say if it's important & functional, as it was put in by prior owners. Alternatively, bringing up the other 3 'sides' would mean that these margins of the pond would be above the level of the new sod that is adjacent to each of them. Does anyone here have an inkling about how to deal with this?

One of the factors that might be worth mentioning is that the waterfall will be coming down over at least ¼ of the width of the rear area - this will be the zone that is therefore not going to show the pond liner. But the rest of the rear edge could be a problem - plants and rocks most likely will not be able to completely conceal the black rubber pond liner, owing to it's exposed height above the waterline. What to do?

 

[GBBUDD]

there's that weather issue again, haunting me).

Cover the area with a cheap tarp or plastic and p I mp out the water keeping the soil dry. T

Excavating further down along the back brings me to a submerged drainage pipe - can't say if it's important & functional, as it

Always assume it's live if you do and assume it's live and repair it and it's not connected your out a couple bucks.

Ignore it and it is live and you bury the broken pipe think what a nightmare it is it you have to rip everything apart when it's done and looking good.

You don't want the edge of the pond lower than the sod. You need to keep water run off from getting in the pond . Even as it drops over the retaining wall keep it out of the pond.

As far as the water being higher than grade build a cinderblock wall . I did the same with my pond the build is detailed in the showcase link below.

 

[YShahar]

Here are the issues at this stage of the project :

1. The weather! This is clay soil. I have siphoned out the pond multiple times, only to have it refill with heavy rainfall and wild storms. Each time, a proportion of the frogs come right back from their temporary accommodations (kiddie pool). They've just go so much personality! It takes about a week of drying before the emptied pond has a workable consistency.

I'm thinking you might need to set up a series of French drains around your pond and extending around your waterfall and stream. Or maybe even under the stream itself. Otherwise you're likely to have all kinds of guck flowing into the pond every time it rains. There's are a couple of good Aquascape videos out there on providing drainage to guide rain water away from your pond.

2. Issue - construction of cut-in 'shelving', 12"-14" in depth, to support perimeter plants and rocks - hard to do when the hole is already cut out. I have not quite figured this out. It's almost as if I need to make wooden forms, wet the soil to a pliable consistency, and then pour it into place (and there's that weather issue again, haunting me).

I had a similar issue, except that in my case, I was dealing with "soil" that was more gravel and rock than actual soil. The stuff kept collapsing whenever I'd pull out a sharp rock. My solution was to add old construction pavers in the hole to hold the soil and keep the sharp bits away from the liner.

For the shelves higher up, I carved out the shelves as well as I could, fairly roughly. Then, as I was laying in the liner, I'd fold it back in towards the pond and use the liner itself to hold up the soil. This meant quit literally digging with a hand trowel and small pickaxe, so it took hours. But it worked!

Another solution is to over-excavate and not worry about the shelves. Then, once the liner is in place, use your larger rocks to build the shelves: set a row of them, fill the space behind (toward the pond wall) with gravel, and then move on to the next higher shelf, laying the rocks on the gravel below.

3. Leveling off the edges. See photos. There's currently about a 6" height difference between the back edge of the new pond (the one adjacent the old stone retaining wall) and the 'front' edge - the one closest to the house. Excavating further down along the back brings me to a submerged drainage pipe - can't say if it's important & functional, as it was put in by prior owners. Alternatively, bringing up the other 3 'sides' would mean that these margins of the pond would be above the level of the new sod that is adjacent to each of them. Does anyone here have an inkling about how to deal with this?

This might actually be a good thing, in that the level of the pond should be above the level of the sod, in order to keep runoff out of the pond. You could make a virtue of necessity and simply extend the pond back a bit and put a series of stepped back rocks on that higher edge.

One of the factors that might be worth mentioning is that the waterfall will be coming down over at least ¼ of the width of the rear area - this will be the zone that is therefore not going to show the pond liner. But the rest of the rear edge could be a problem - plants and rocks most likely will not be able to completely conceal the black rubber pond liner, owing to it's exposed height above the waterline. What to do?

Check out some of the great videos by Aquascape and Atlantis Water Gardens on hiding edges. The short answer is to give yourself a shelf about 6-15 cm below the top edge and lay rocks on that, making sure to use a mix of sizes, to avoid the "string of pearls" look. Then you continue adding rocks behind those rocks, to make the edge look more natural.

One point to watch out with edging is something I learned the hard way: make sure any interior folds in the liner that meet the edge at an angle are folded over such that they don't siphon water out of the pond. This may mean making your edge folds inward, rather than outward (as encouraged by the pond experts).

Enjoy!

 

[AussieGardener]

Hello everyone. It's, what' a year later? FINALLY some progress to report!

Pond 1 is 'roughed in'. I am throwing in a fairly random set of pics. The materials laid in atop the liner are comprised of 1 pallet load of irregular stones, quite a mix of sizes. There's also some pink-ish quartz-derivative rocks from around the yard - 'yoink' - in they go! The smaller river stones came in aprox size ranges 3"-5", 1"-3", and ½"-¾". I ordered 1,000 lbs of each of these, having the supplier put the smallest stones on bottom of the 'tote', then next size on top of that, and finally the largest on top (thinking of the practicality of laying out the various sizes by wheelbarrow, and wanting access to the 'dressing' (smallest) stones last. It went well.

I will need to come back and tweak the position of the overflow pipe, but for now, we're loaded with water, and a few frogs and tadpoles that sat out the entire summer in a kiddie pool (with a tarp draped from that and into our green swimming pool). As I had guessed, the frogs love the expanded area with both in/out of water access. Plants were also held in the kids pool, and I am guessing that they will be viable for next summer.

Up next - upper pond, and then a waterfall to connect them together. I have been daydreaming about constructing the overfall area (crossing retaining wall) from scrap steel, and then covering it with pond liner and placed stones. I will search for local supplies and see how practical this might be. It gives me an excuse to wake up my unused MIG welder.

Back to it. I am heading to suppliers to build a ½" PVC pipe-based 'tent' - we have heavy leaf fall, and it will probably get underway this week. Thanks again everyone for the great ideas. At some level, everyone's input made it into the end result. Grateful!

Grant.

 

[YShahar]

Looking good! It's going to look great with such a lovely wooded backdrop. Looks like your little furry helper is getting excited about the project!

 

[addy1]

Very nice! Like the helper!