Inspiring Rock

Formations Build Beauty

By: Ron Derven

            Editor’s Note: William Renter, owner, Deck and Patio Company, Huntington Station, New York, has won numerous awards in NESPA and APSP design competitions for his outstanding pools, spas and water features. A signature theme of many of these projects has been beautiful rock formations mixed with vegetation and water. Recently, we asked Bill about his use of rock and how he goes about designing these formations into his projects.

            The Edge: Where do you get your inspiration for your rock formations?

            Renter: I get my inspiration from nature. I have a ski house in the Catskill Mountains and on days when its pouring rain, I love to hike up to the waterfalls that are near my place and watch the streams, and waterfalls and the way that water flows over rocks. There is one waterfall near me named Kaaterskill Falls, which is a spectacular two-drop waterfall that cascades a total of 260 feet, making it one of the highest waterfalls in New York State and on the East Coast.

            The Edge: How do you apply what you find in nature?

            Renter: I like to make rock formations look like they do in a natural setting. On Long Island where I live, we do not have a great deal of rock formations because it is an island that was created mainly out of sand. We do not have rocky ledges like they do in New Jersey, New York or Connecticut, so we have to bring in stone that looks like it comes out of the forest. Our materials are from Pennsylvania. We try to make our rock formations look like rock outcroppings. We do not want to make the formation look like a necklace of boulders; it is about making the rock formation look natural.

            That can be achieved by grouping boulders together and doing plantings around them. The key is grouping you boulders together to make them look like a big piece of stone. You can do this when you group smaller pieces of stone together tightly. Avoid making it look like a retaining wall–that is, similar sized boulders all in a row. That is a key. We have done this successfully.

            The Edge: You don’t like retaining walls?

            Renter: I have made a career out of avoiding retaining walls. I use natural elements such as plants and boulders to hold back soil and to hold back the grade. We use boulders on the edge of pools that overhang a little.

            The Edge: What about using rocks to create waterfalls?

            Renter: To create a beautiful waterfall, you need to use support boulders – boulders that are not part of the waterfall itself, but rather part of the landscaping, so that the project does not look like the waterfall just fell into place and there is nothing else around it that makes sense. The support boulders, or “accent boulders,” as we call them, are as important as the waterfall itself.

            The Edge: What else doe you try to achieve in you waterfalls?

            Renter: I want water to change direction in my waterfalls, not simply flow forward. On some of our jobs, the water does flow forward, but then it hits a rock and bounces off. When you think about a stream in nature, the water does not go straight down like a set of stairs, which is typically what we see on waterfalls that do not work well. The tricky and complicated part is when you start to build it, you must begin at the bottom and work you way up. You must identify all of the placers where the water will hit the rocks. Don’t let water simply spill forward like a set of steps.

            The Edge: Besides the rocks in a waterfall, you add plants. Why?

            Renter: We find that when many people build waterfalls, they do not think about the plants and the water – two critical design elements. We leave pockets for plants where we have plants almost touching the water. Planting in the rock will soften the rock, which sometimes can become overwhelming.

            The Edge: What about leaks in waterfalls and water features? This is an ongoing problem in many projects, is it not?

            Renter: When you put water on rocks, leaks develop. To create a leak-proof waterfall, we start with a 45 mil EPDM flexible rubber pond liner. That liner is placed on top of the wall of the pool and actually overhangs the pool by an inch. Any water that makes its way through the waterfall, the rock or the cement will hilt the liner, which is overlapped over the beam of the pool, and it returns the water back into the swimming pool or water feature. Some clients complain that they do not want to have the liner showing and we doe our best to hide it, but it does have to overhang. If you were to cute the liner flush with the edge of the pool, the water tends to cling to the liner, goes under the liner and behind the pool, which creates other problems. So letting it overhang by and inch creates a kind of drip edge where the water will roll off and into the pool, not cling to the liner.

            The Edge: How do you keep your waterfalls from flowing like a water main break?

            Renter: What we like to do is use something from a company called Aquascapes, our equipment supplier. The product is called Biofalls. This is almost a settling tank. It is roughly a 20-gallon container where the water from the pump goes into it and slows down. We want a heavy flow of water, but we want the velocity to slow down.

            The Edge: You are an expert on rock formations, but how do you communicate it all to the client who may not know that much about them?

            Renter: I take a lot of pictures of streams and waterfalls. I have thousands of pictures. I am not artistic when it comes to drawing and perspective, but I am creative when it comes to shapes and landscape design. I do a lot of my own landscape design. People hire me because I show them what I like, and hopefully they will like what I like.

            I also suggest they go to our website, www.deckandpatio.com, and watch our video titled “It starts with a plan.” That is our theme when we meet with a client. We draw plans on auto CAD to show the shapes and sizes of spaces and where things will go and the viewing angles. The last thing we use to blow clients away is design software called Pool Studio. But we charge for this service. Our people will spend up to 25 hours working with this program to create a design.

            The Edge: What about the hydraulics of waterfalls?

            Renter: You need to understand the basics of hydraulics. The greatest failures in waterfalls and rock formations are when you are all done and you have a pile of wet rocks because the builder did not supply enough water to the waterfall.

            The Edge: Where can one go to learn and understand the complexities of hydraulics?

Renter: You need to create a “weir,” a small overflow. When you have a rock and you want the water to release and spill off the rock, that is a weir. Further, you need to have thicker water run over your weir when using natural stone and boulders. The diameter of the pipe and the size of the pump or pumps need to be carefully calculated. On critical thing I have learned in this business is that big pipe is good. A builder can always change a pump if the waterfall needs more water, but if the pipe is not large enough, no matter how big a pump it its, it simply won’t work.

            The Edge: How important is rock selection to the overall design success of a project?

            Renter: Sometimes customers will say “Our patio is a reddish stone so why don’t we make the waterfall reddish stone?” I will suggest to them that it does not look quite natural. We found two types of stones that we typically use. One is called Long Island Boulder, a rounded stone without a lot of cragginess to it. Theses stones look like a big round bowling balls or dinosaur eggs. We do not use them all that often. We specify the shape and size of the boulders we want, and we use very simple terms to order them, such as “I want rocks that look like basketballs” or “I want rocks that look like a box that is three feet by two feet by three feet.” We also use beautiful moss rock that comes out of wooded areas in Pennsylvania. It is craggy and very interesting material. We do not go so much on color. We want rocks that came out of the woods or a stream.

            The Edge: It must be quite difficult handling large boulders and placing them where they need to be on a job.

            Renter: We tried a couple of different handling methods. We now use slings to lift the boulders. We can pick them up and turn them around and twist them and get them just right. We recently purchased a mini excavator that has the ability to pick up a 2,000-pound rock. When we put a sling on it, the excavator has such a good reach that we can do our work safely and correctly. You have to pay attention when positioning rocks. On small waterfalls, we pick the rocks up by hand and place them.

            The Edge: How big is a 2,000 pound rock?

            Renter: A 2,000 pound rock is about three feet by four feet by eighteen inches to two feet deep. We get twenty-five tons of rock in a 20-yard dumpster container and use about three containers a week on our jobs.