CW's Back Yard Water Garden Begins!

[GBBUDD]

I was not home for the entire month of September hot water was still running basic lights . And the 12000 gph the 500 gph a air pump 600 and some leds to light the pond welcome to the hive mind much like your area and as insane as Seattle has gone you still have a long way to catch up.

 

[combatwombat]

Excavator is coming back this morning to do the big dig. Exciting! Shot this video yesterday explaining the design of the intake bay:

And here are my notes from a conversation with Trevor in the tech dept. @ Aquascape about designing an intake bay, in case it's helpful to others:

Intake bay should be sized based on volume of water drawn at pump. Do not include head pressure in calculation. First, convert GPH to GPM.

Example: 5000 gph = 83.33 gpm

Then, look to get that volume in aquablox. Example: 83.3 = 4.9 small Aquablox. Even number = easier design, so use 6 in this example. You can use large or small. Need to consider winter needs. Need to use large aquablox if running pump in winter to account for adequate flow to pump when surface ice is present.

Aquablox layout should be rectalinear so that you can place vault in the center for max flow to pump. Try not to place vault at a corner as it weakens design. Square is better than long rectangle.

In general, looking for 8-12" water depth above gravel over intake bay.

Weir sizing should be 1' per 8000 GPH of flow and 6-8" depth. Can also be expressed as 1" per 667 GPH

If you excavate bay/weir to max dimensions, you can always adjust smaller with rock later on to dial in performance. If you undersize, you'll have to pull liner and excavate.

I have some more design info written out in the description of the youtube video posted above. Think I'll make a more comprehensive thread about this in the future once I've actually built mine and can speak more competently about it.

 

[bagsmom]

Oh lord - that math intimidates me!

 

[combatwombat]

Oh lord - that math intimidates me!

Ha. I think you'd find it quite simple if you were standing in front of your pond and applying it directly like I was. Much easier to understand when it's directly applicable.

If you're actually wanting to design an intake bay for your pond, I'd be happy to run the numbers and help you design it.

 

[bagsmom]

Thank you! I have the excavation all complete and all my stuff purchased. I actually did the math just now and WONDER OF WONDERS - by some miracle - I have the right size on everything! I don't know what planets aligned to make that happen... Now I need to save up $1200.00 for all my rocks. (I was almost there, then our deep freezer bit the dust, so we had to use it for that. Back to the beginning!)

 

[combatwombat]

@bagsmom: Nice! And I think there is quite a lot of wiggle room in the design process. Doing all the calcs should guarantee it works right, but just like it seems with bog filters, just about anything you build ought to work fine. To hell with the calcs! Good luck with the freezer. Seems like finding one of those is like trying to find toilet paper back in April.

 

[combatwombat]

Most of a very large hole is now in the ground. Still need to dig the bottom shelf to final depth of 48". Excavator doesn't have a long enough reach to dig very cleanly on the final shelf, so we'll be hand shoveling it into the bucket. Very sandy soil down there. For a brief moment, I considered abandoning the intake bay (background) and recessing a hot tub into that hole instead.

Ended up with a lot of soil—15" in some spots—above water level as the yard is on a gradual slope. I thought it was more gradual than that! Gonna have to come up with some creative landscaping ideas to make it all look the way I want it. Part of the problem was that we were trying to pull a lot of the soil to the high side of the yard, and the edge of the pond on the side that was already going to be high got built up even more.

Maybe I can have a bit more of an impressive waterfall than I first thought!

 

[addy1]

Nice!

 

[combatwombat]

Put together a video of the excavation and some of the details that will still have to go into getting things just how I want them.

Final excavated dimensions: 43x25. Final depth will be 4'.

Ordered a 40x70 HDRPE liner just now from American Tilapia. 2800 sf (same as the house!) for about $1200. At $0.43/sf, it's about half the cost of EPDM. Less, actually, as you don't typically require an underlayment because it's a lot more puncture resistant. I definitely don't need an underlayment as our soil turned out to be very sandy loam.

It's a fraction of the weight, too. 150 lbs vs. almost 900 for a liner this size. I should be able to place it myself or with one friend and no equipment necessary to move it around.

Will be interested to see how it goes in. I'm expecting it to be a bit tougher to work with and form to the curves/shelves than epdm, but I think this pond is big enough with no tight corners, so hopefully not too bad.

 

[combatwombat]

Finished digging the final shelf yesterday and grading the excavated dirt around the property. Happy to be done with that, but I think I see some problems that need to be fixed before the liner goes in. And not quite sure the best route. Any help is appreciated.

Here's what's up:

I wanted a final depth of 48" without any one shelf being too tall (so that building the rock walls around the shelves would be easier). That led me to set the shelves at 14" (12" after gravel covers liner), 14", and 20". But I did not choose the water level carefully enough. We marked a spot for water level and dug 14" down from that spot for the first shelf.

Well, that left me with 6" of freeboard for overflow. But there is also a 4" grade change across the length of the pond. That means the actual excavation depth for the first shelf ended up being 20" at one end and 24" at the other. And it will leave the water about 8" below grade from the primary viewing point. I think I'd prefer more like 3".

So how to solve this? I can simply raise the water level 4"—I have room for it. That would leave me 2" before overflow. But then my 1st shelf would be 16" deep for planting. I have not really done my research on aquatic plants yet, but I think that's too deep for pretty much all of them? I could solve that problem by planting in pots, but my preference would be to plant directly in the gravel as I believe potted plants are a fussier.

Simply raising water level will also still leave me with a 24" high wall to rock around the edge of the pond. Not the end of the world, but not ideal as it will mean having to set some BIG ROCKS (small rocks if you have a machine, I guess...) to make it safe and sturdy.

I can also cut down the grade around the high sides (to an extent), but am limited there by a few set elevations and it would mean moving EVEN MORE DIRT than I already have. Another "not a big deal" but I am sort of running out places to lose it all. Might have to make some raised beds for the wife!

I guess I could also start filling the top shelf back in with dirt. That would be a bit of a demoralizing task, but if it has to be done...

Oh, one other option might be to make the pond EVEN BIGGER and dig a shallower shelf around the perimeter. But I'm limited on space and my liner is already shipped (should be big enough for some expansion, though).

Probably some combination of all of these options will get us there. I thought we were done digging, but perhaps we've only just begun!

 

[addy1]

If my dig I would dig a shallow shelf around the pond, make it 4-6 inches. Have your liner lay on that shelf and come up and out of the pond. On that shelf lay rocks that will totally hide the liner and hide the fact there is a water level issue.

 

[Jhn]

Addy’s suggestion is how portions of my pond are done. The other option is turning that planting area that is now 16” deep to the top of the gravel into a planting bed for lilies or a lotus.

 

[combatwombat]

Addy’s suggestion is how portions of my pond are done. The other option is turning that planting area that is now 16” deep to the top of the gravel into a planting bed for lilies or a lotus.

Good call. That makes me think of another option. Parts of my top shelf are wide enough that I can probably arrange the boulders so that there is space behind them. but inside the liner, that I can fill with gravel and use for planting. And then just plant the heck out of the edge with terrestrial plants and things that will grow over the edge of the rocks to soften it up and give it some more life.

Using the top shelf as the lilly shelf would also keep the center area more open as it wouldn't need to support much plant life. Great idea. Thanks for this.

Also, you work with rock a lot in your job right? I am so intimidated right now by the rocking process. My soil got sandier as we went deeper, so that bottom shelf is not too sturdy. Thinking I need to go big with rocks down there and treat it as a legit retaining wall.

My excavator was using a JD 35g, and we actually had to dig that bottom shelf by hand because he couldn't reach his bucket down there well enough to get clean scoops at it.

The idea of getting big rocks down there when his machine couldn't reach makes me think they either have to go by hand or I have to get a huge machine in here to place them. Have casually considered using engineered wall blocks, like Allen Block, or something to provide really good stability in manageable sized blocks. Would look pretty out of place, though. Wall only needs to be 22" high.

 

[GBBUDD]

Parts of my top shelf are wide enough that I can probably arrange the boulders so that there is space behind them.

I have that in a couple places it really makes everything look like it was always there.

You have some areas that still have spray paint that would make the shelves all the same width it looks a lot better to me when they vary and have odd lines and shapes.

i also would dig out one shelf toward the bottom just wide enough for a wide piece of flag stone or similar so you can have the liner fall into this area and place a stone over the top which would give you a built in fish cave.

I have mentioned what addy has drawn out to you as well on your other posts it is ponding 101 it makes finishing the edges a breaze and looks great

 

[combatwombat]

@GBBUDD:

I have that in a couple places it really makes everything look like it was always there.

Your pond looks amazing, so it's good to know I'm on the right track with that idea.

You have some areas that still have spray paint that would make the shelves all the same width it looks a lot better to me when they vary and have odd lines and shapes.

It's all dug out now. There's quite a bit of variability to the width/shapes of the shelves. I don't think the pictures quite do it justice. But I know what you mean and you're right. The shelves all go all the way around. I could cut some parts out, I just got intimidated by the size of rocks I felt like I would need to accomplish that. I will certainly dig out some fish caves before I set the liner.

I have mentioned what addy has drawn out to you as well on your other posts it is ponding 101 it makes finishing the edges a breaze and looks great

You know, I don't know how I missed this. I've watched just about every single pond building video on the internet and don't think I ever ran into this technique. And when I finally did, I wrote it off as, "Oh that's what people who use flagstone around their edge do" and I wasn't going for that look, so I just ignored it. I think that was a mistake. The more I think about it, the more that approach makes sense to me for any type of edge treatment you want. Still a bit tough when your dig is on a slope, but certainly better than what I've got.

Oh well. Can't go back now. I ordered my liner large, so I'll see what I can make work when it shows up. Maybe if I'll buy another strip of liner and try to pull off a massive seam. Yikes!