Building a Pond, Part 2 Waterproofing

I’m taking today off from the yard. Yesterday I poured concrete for our sidewalk since the weatherman assured me there were going to be several at least semi-dry days in a row. I didn’t want to quit until all the concrete I’d purchased was used and I couldn’t be bothered to stop what I was doing long enough to go inside and put some sunscreen on. Now, I’m sorry to say, I have a very nasty sunburn that is keeping me from the yard. So lemonade from lemons and all that, I thought this would be an excellent opportunity to work on my next post about the pond project.

So where were we… oh yes, mud. Lots of mud.

Luckily, I had leveled the edges of the excavation prior to the rain turning the entire pond area into Mudville. I opted for a very simplistic method of accomplishing this: I moved dirt from the higher side of the pond to the lower side until it was mostly level all the way around.
As long as it reaches from one side of the pond to the other, you can use any straight board with a level sitting on top to check level. This works for ponds this size or slightly larger; if you’re doing a much larger pond, leveling will be more technically involved.

Leveling the sides of an organic, freestyle bordered pond is forgiving compared to a formal pond in an exact shape. You still need to level well enough that water doesn’t run out the low side, but minor imperfections can be hidden with rock or plantings.

Perfectly round or square ponds will be noticeably lopsided if the water level is higher on one side than the other. Water will run over the low side and liner will show above the water level on the high side; which makes your pond look silly. Not to mention it can waste a lot of work and expensive materials if you realize that it sucks after the fact and you can’t live with lopsided.

Check for level from every angle, and then check it again before you start moving heavy rocks or mortaring things in place.
Formal ponds may benefit from a brick or concrete block ring set in a light mortar bed around the perimeter of the pond to help it maintain a precise shape and make sure the edge is perfectly level.

Ok, so sides are now level and if you’re me, you’re about ankle deep in mud and not sure whether it feels nice between your toes or just really slimy and gross. It makes a nice SSSSSTHOCK sound when you pull your foot out, which is giggle-inducing to all preschoolers within ear shot. Doubly funny if you lose your sandal to the mud sucking if off your feet. Brownie points if you lose BOTH sandals and nearly get a mud facial trying to rescue them from the bottom of the pond.

I cut my underlayment in half and covered the entire area around the pond and the waterfall, overlapping the underlayment in the middle. An underlayment of some kind under your pond liner is an absolute necessity if you don’t want rocks or sharp roots poking through and destroying all your hard work when you add water.

Water is HEAVY and will cause anything pressing on your liner from underneath to push on it exponentially harder. In the winter, if you leave your pond in place with water in it, this is even more so as the ice pushes up against the walls of the pond as it expands. You need a nice, soft cushion over that hard, unforgiving ground to protect the liner. The clay-type liners are more forgiving in this area, since the clay itself can act as a natural sealant against small punctures. However, a large rip could still destroy even a clay liner, so it’s best to do your prep work regardless of the liner material you choose.
My liner is PVC, because this was cheapest option. EVDM liners are a better choice if you can spend a few extra $; they are stronger (made out of a material similar to car tires) and can tolerate UV rays from the sun better than a PVC liner can.
If you don’t want to fork over the $20 or more for underlayment, a layer of sand and newspaper or cardboard will work instead. Just make sure it’s durable enough that the sharp bits are not going to come through and trash your liner.

After the underlayment is in place, spread your liner out a bit and let the sun warm it up to make it easier to smooth out the wrinkles. A couple of flat rocks on either side of the pond will help hold it in place when you start to add water and can be moved to allow slippage as it fills.

I actually bought two liners for this project, one for the pond and another smaller liner for the waterfall.
The pond liner goes in first, the waterfall liner should overlap it. I had enough for the pond  to run up the waterfall with a bit of slack so that it didn’t stretch too much when I added the large rocks for the waterfall base and then water. Leave plenty of slack at the base of the waterfall liner and let it hang down into the pond. If you’re not doing a waterfall, ignore this entire paragraph. (I probably should have mentioned that BEFORE you read it.)

Liners in place, I filled the pond about ¾ of the way with water, adjusting for slippage as it filled. “Adjust for slippage” is fancy landscaper speak for smoothing out the wrinkles enough that it isn’t tight, but doesn’t look the skin on a Shar-pei puppy either.

The spot where my daughter is sitting in the photo has been dug out to slightly below the rest of the sides in order to build a beach area there later. I put some cement blocks underneath for the time being, just to give us a stable place to climb in and out of the pond and keep the water from spilling out of that area.

You can trim off major excess of liner now if you wish, but don’t trim too close to the edge; you’ll want to leave enough to wrap up around the coping stones (your rocks that border the pond) or tuck under the grass if you prefer the natural look. I saved the really large pieces of leftover liner to put under my big stones and small boulders to guard against tears and punctures.

I can’t stress enough how you should buy a MUCH bigger liner than you need for your project. This will ensure that A) You don’t have a nasty “My liner is too freaking small for this hole” surprise and B) That there is plenty to wrap and use for padding.

At this point, the pond is basically in place, but there is still a lot of ugly black liner showing and a PVC covered pyramid for a waterfall. I’m using a basic drop-in pump with an attached UV filter to move the water. If you’re doing a bio-falls and skimmer, you’ll need to watch their little video or call a plumber, etc. to get that thing installed. The drop in pump was cost effective. Previous years, I actually used one of those fish tank waterfalls disguised under rocks to run my small pond. It worked pretty well and was under $30. The drop-in pump in and filter will run you closer to $100, but it can also handle filtering a much larger pond.

Next, it’s time to do a jigsaw puzzle with a big pile of rock…

Building a Pond: Part 1, Hardscape

Our little pond project went better this time, (I hope) only a few hiccups along the way and a little flooding problem I’ll have to be addressing before it is complete. I’m going to be doing this in a series of posts, since it’s a rather lengthy process with lots of pictures. And just a side-note: Water-containing things… still not my favorite element to work with.

Since this was my first attempt at a pond that I didn’t just dig a hole and toss the hard plastic liner in the ground, I did some reading online and even checked out a couple library books on pond construction before I started. I ordered a PVC liner, some underlayment and landscaping foam from I also hauled buckets and buckets of rock from our woods and surrounding yard to the pond site. I didn’t want to have to buy large amounts of stone; I was hoping to keep the budget for this project under $200.  At this point, I was in $49 for the liner, $20 for underlayment, $50 for a pump and $20 for landscaping foam; so right on target after buying a couple bags of river rock and some mulch to finish it off.

The first two days of this project were all about hardscape. I hauled rocks out of our woods, sometimes by the bucketful or one at a time depending on the size. Some of the really big ones I had to just roll out of the woods, since we don’t have a four-wheeler or other mechanical option to get them to the yard. My daughter helped by picking up smaller rocks and pushing a few of the larger ones back down the hill for me. >.<

I thought that I had more than enough rock when I’d finished, judging by the size of the pile I wound up with. It turned out that this was only about HALF of what I actually needed to do the job, so I spent another day during the pond construction rock searching and hauling. We are lucky cost wise that we have such a huge resource of rock available on our site. If you don’t have this kind of rock readily available, be prepared to shell out a couple hundred dollars to have stones of this size and in this quantity delivered to you.

Third day or so was spent digging. I used an old piece of hose laid on the ground to get a general outline of where I wanted the pond to be. I then stuck my shovel in just deep enough to leave a line in the ground around the hose so I had a rough outline of the pond. Since the back of the waterfall was going to butt right up against our sidewalk, I decided to work on that next. I figured the best way to make it stable would be to build it like a raised flower bed. You lay your first course of rock (in this case, cement pavers I had lying around from a previous project) at least halfway buried in earth. 

The ground slopes from left to right in this area, so I dug a shallow trench deeper on one side than the other to level the first three blocks in. For flower beds, I would usually just eyeball the level. For this project, I went inside and actually got a level and checked each block for level and then all three of the first course for level against each other. I can’t stress how very important it is that this first course be as level as you can get it. For every little bit the first course is off, the blocks you stack on top of it will be exponentially off level which can lead to a very unstable structure. 

I wanted the waterfall to come to the top of the sidewalk, so I stacked blocks 3 high in a pyramid, leaving a few inches for the decorative rock I’d be putting on top. Once I was happy with these later and sure I didn’t want to re-arrange them again, I glued them together with a little landscaping foam.

Now that I had the waterfall base in place, I started digging the pond. This is where I should have done a bit more research, because I made a mistake that is probably going to prove to be a real pain in my butt sometime in the future. I dug out the hole and then went back and built up shelves out of leftover dirt. Our soil is mostly clay, which sticks together and packs nicely, so this was very easy to do.

The CORRECT way to do this is dig a shallow hole for your first layer. Then re-mark the outline of the pond a few inches or so from the perimeter and dig a bit deeper to create a ledge out of undisturbed soil. Then mark a perimeter again a few inches in to create a second ledge of undisturbed soil. Finally, mark your last perimeter and dig even deeper. This is the center and deepest part of the pond where your pump would go.

When you finish it should look like this nice professional picture of the man with his level, which you will note, doesn’t look much at all like the sloppy hole I dug myself. I only put shelves in where I thought plants might sit later. Also, I had this issue with small children in my excavation. If you have a small child in your dig, I recommend you get them out, especially before installation of the rock or liner.
Those first and second layers of shelving in the example pond are not only for plants, but you need them to hold rocks in place that will hide the sides of the liner later. The website I took this picture from is a good example of how to do it right. My dig is an excellent example of what to do if you want to be standing in a pond half full of water later, saying to yourself, “How the hell am I supposed to get these rocks to stay on the sloped sides of this pond?” This was my first major mistake.

The depth of your pond will depend on it’s purpose. If you are only going to put a few water plants in, it only needs to be around 1.5-2ft deep. I kept mine fairly shallow so that my 3-year-old daughter was able to sit on the bottom without the water level being over her head. Had I installed this a year or two ago, I probably would have opted for a pond-less feature with a recirculating fountain.  The current pond is outside the fenced play area of our yard; in other words, it’s in a place where she should never be around it unsupervised. I built our pond with her in mind. It will home to frogs and a few water lilies, but no fish.
If you are building your pond for fish, it will need to be deeper- at least 3 to 4 feet for koi, slightly less for goldfish. Basically, the fish need a place below the frost line where they can hibernate without the whole pond freezing solid. Having fish in your pond may also involve installation of a heater and a pump to keep oxygen circulation going.

I didn’t finish the pond the day I dug my hole. I ran out of steam and time, so I let it set and planned to pick up where I’d left off the next day. Then it rained. A lot.  And I wound up with a big, muddy hole, ¾ full of water. Did I mention that clay is an excellent medium for holding water? In fact, they make natural pond liners out of clay and a bonding material that you can use to line your pond if you prefer not to use PVC or EPDM liners. It’s more expensive, but can be self-sealing and it’s a natural alternative to plastic or rubber. Large scale farm ponds around here often utilize clay as a pond base to hold the water in.
SO… after it finally quit raining, I went out and pumped and bucket-scooped the water out of the hole so that I could replace the muddy, mucky mess with my nice, clean PVC liner. The fact that the pond held water so well without any liner at all should have told me this would be a problem later. I was oblivious however and continued on, unhindered by mud or knowledge of hydrostatic pressure and ground water tables.
…to be continued…