Pond Construction

Construction Technique #1 : Getting Off to the Right Start

To get off to the right start and avoid surprises later on. there are a couple of things to do before construction starts:

1. Assess the property where the pond will be located and take note of all existing structures and utilities.
2. Using a site or laser level, determine the high and low areas where the pond will most likely be constructed.

Site Assessment
Go around the pond perimeter to determine the high and low areas in relation to the main viewing area. Most of our ponds are located next to a patio, so the patio would be a starting point. We like the water to come right up to the viewing area, so we typically set the water 2" to 3" below the level of the patio. Once the water level is established, we construct the entire pond perimeter a minimum of 2" above the water level.

At the back edge of the pond, where the waterfall is located, the level would be much higher, depending on the waterfall height. All measurements taken from this point forward will be in direct relationship to the water level!
 

Pond Excavation

Technique #2 : Constructing Ledges

Purpose of Constructing Ledges
Safety - If someone were to accidentally or purposely walk into one of our ponds, it would be like walking down a gradual staircase, not a steep, slippery, dangerous drop off.
Strength and Stability - Terracing is much more stable and less likely to collapse than a steep, tall wall.
Aesthetics - Our ponds are very clear, and you will see the bottom contours, adding interest to the pond's interior.
Aquatic Plants - The different ledge depths are perfect for planting the many different species that are available.

Stone Usage
Using our formulas an 11' x 16' is 176 square feet divided by 65 = 2.7 tons of rock. We always round up, so the new number is 3 tons of boulders. This is an average, and if we want some character stones, we would add in another half ton bringing it to 3 1/2 tons.

The top ledge of an 11' x 16' pond has the greatest perimeter. It's approximately 45' long. Using a mix of stones, we would need 1 1/2 to 2 tons. The middle and lower shelf combined are approximately 45' long. We would need another 1 1/2 to 2 tons. Our estimated amount of stone was 3 1/2 tons and it should be fairly accurate. If the pond were excavated without shelves, not only would we need an extra 1 1/2 to 2 tons of stone to cover the steep walls, it would also take several more hours to excavate.

Constructing the First Ledge
Now you're ready to dig the first ledge! It's typically 6" to 10" deep and dug around the perimeter of the entire pond. Remember this ledge should be covered with gravel, so a ledge that is 6" deep will become 4" deep after it is constructed.

Ledges can vary according to their usage, but they do not have to be perfect. Remember, our goal is to copy nature, and natural ponds don't have perfectly level or symmetrical ledges graduating toward the bottom of the pond. When the first ledge is completed, mark out the next area to be excavated.

Technique #3 : Berm Construction

During the excavation phase, the filters and piping are laid as well. The BIOFALLS is always set first, and the flexible piping follows. This is important for peak efficiencies of the crew. The excavated soil is used to construct the berm around the BIOFALLS and its size should be equivalent to the size of the pond. In other words, if the pond is 11' x 16' and 2' deep, the berm should be 11' x 16' and 2' high. If the BIOFALLS is set higher, more soil will be needed to disguise the waterfall, and may seem out of place. If it's set lower, the berm will need to be more spread out in order to use the soil. Each construction site is evaluated by the salesperson as to how high or low the waterfall should be.

Soil usage is often an overlooked part of the construction process. Our crews rarely remove soil from a construction site and if the quality of the soil is poor, organic topsoil is brought in to be used for future plantings. The larger and broader the berm is constructed, the easier it will be to naturally incorporate plantings to help a water feature reach it's potential.

Large Construction Projects
On larger constructions of 600 square feet or more, we bring large equipment in to help with the excavation, larger boulder placement, and material handling. Skid-steers and backhoes are the two most common pieces of equipment, but cranes and loaders can be used as well. A skid steer can be effective in excavating the top shelves of the pond, but the bottom and final shaping should still be done with hand tools. A good backhoe operator can maneuver around enough to do quite a bit of digging, but some handiwork is always necessary to clean things up.

Check Valve
This plumbing component is used to prevent water from draining out of the BIOFALLS and flowing back into the pond when the power to your pond is cut. If the electricity goes out, or the user simply unplugs the pump, gravity will naturally pull the water from the return line back into the pond, emptying the BIOFALLS.

Without the water, the bacteria that has seeded within the media in the BIOFALLS will most certainly die. Depending on the length of the pipe run and the amount of pond surface area, the water may rise enough to exit the skimmer overflow. This will force the user to compensate for the water loss by "topping off" the pond once it's restarted. A properly constructed check valve will solve these problems by trapping the water in the pipe and BIOFALLS, with a one-way flap gasket contained within the check valve.

The Manifold
The manifold is mainly used to split one line into two while creating less friction than a standard tee. The manifold takes a curved path instead of dead ending and shooting left or right. We suggest using a manifold for several construction applications. The most common use is to split the flow of one large pump into two mini or standard BIOFALLS. Aquascape Designs offers a 3" x 3" manifold assembly with elbows and 2" reducer bushings to accommodate several different pipe configurations. Manifold installation requires glue and primer only.

Ball Valve
A ball valve is used to restrict or divert the flow of water through a pipe. A 1 1/2" and 2" ball valve are available from Aquascape Designs. turning the red handle moves the ball inside and allows the user to evenly distribute the flow rate of one pump through two or more BIOFALLS. Ball valves can also be used in pond construction to slightly reduce the flow of a waterfall, or as an alternate check valve by fully turning the handle and preventing water backflow from the pipe and BIOFALLS.

Conversion Kits
There are two conversion kits available from Aquascape Designs. The first one is a 2" to 3" to be used with pumps that are capable of producing greater water flow than a 2" pipe can handle (apx. 4,800 gph).

• Conversion kits should be run directly through the discharge hole in the back of the skimmer and connected to the 2" check valve assembly.
• The other end is converted and will adapt to one 3" line.
• This will alleviate head pressure from the pump, and allow it to achieve maximum water flow.

Be Prepared for Other "Plumbing"!
From time to time during pond construction, you may come across irrigation systems, as we often do. To save yourself delays and confusion, familiarize yourself with the plumbing and tools needed to work with these types of systems. You may want to carry a set of the necessary tools with you so you can divert the lines to accommodate your pond construction.

Pressure Relief Valve
A pressure relief valve (PRV) was designed to counter the effects of hydrostatic pressure in larger constructed ponds with a minimum depth of five feet. Hydrostatic pressure builds up beneath the liner, usually due to a high water table, and forms air bubbles. The pressure can be so powerful that it actually stretches the liner and forms liner bubbles that can be seen above the water level, regardless of the heavy rocks holding it down.

The PRV is a spring loaded device (rated at 90 PSI) that opens when enough hydrostatic pressure is present, allowing the ground water to enter the system. Once the pressure is released, the valve will close on its own, and the spring gasket will re-seal the system. A minimum depth of five feet is recommended to create enough pressure on top of the liner to counter the PSI rating for the valve, and allow the device to pop open. For example, a PRV will not work on a pond that is 50' x 50' x 3' deep, but will work on an 11' x 16' x 5' deep pond construction.

Note: Alternative methods of pressure relief involve running a small diameter pipe underneath the pond liner, allowing gases and groundwater to escape.

Automatic Water Fill Valve
An automatic water fill valve is a device installed in the back corner of a skimmer to help counter the effects of pond water evaporation or a slow leak, by adding small amounts of water, and maintaining a consistent water level.

Regardless of which approach you take for installation, WFV lines must be blown out in the winter to prevent freezing and cracking.

Overflow Construction
An overflow design is built into the back of each Aquascape Designs skimmer. The overflow will be the lowest predrilled hole in the back of the skimmer mold.

• There is a bulkhead fitting and MPT slip provided for the installation of the skimmer overflow. Install the bulkhead fitting and MPT slip.
• Connect a minimum 5' of flex pipe to the overflow MPT slip with primer and glue.
• Simply run your overflow pipe to a low retention area of the site.

Fittings

Bulkhead Fitting
A bulkhead fitting is a water tight gasket seal used in conjunction with an MPT slip to connect a pipe to the back of the BIOFALLS and skimmer molds. It is also used for the installation of a pressure release valve.

• Installing a bulkhead fitting will require the use of channel locks.
• Remove the nut and place the bulkhead with the rubber gasket on the inside (water side) of the mold's pre-drilled hole, exposing the threads of the fitting on the outside of the unit.
• Fasten down the plastic nut and washer, turn counterclockwise one to two turns past hand tight.
• Note: 3" Bulkhead fitting does not include a plastic washer.

MPT Slip
An MPT slip (male pipe thread) is a fitting that threads into a bulkhead to connect a pipe into the BIOFALLS and skimmer molds. It is also used in the check valve assembly to adapt the valve to the discharge of the pump. Wrapping silicone or Teflon tape or a bead of silicone around the threads of the fitting is suggested to maintain a water tight seal.

Construction Tip #5 : Installation Sealants

Glue and Primer
The glue and primer used with Aquascape Design's ProPond Kits are included with the installation package. The glue and primer are specifically designed to prepare and adhere sections of flexible PVC pipe to various fittings and components. You can use any glue and primer on the market as long as it's rated for use with flexible PVC pipe. Standard schedule 40 glue and primers simply don't have the right bonding strength and temperature to work with flex pipe.

Silicone Sealant
The silicone sealant used by Aquascape Designs is included in the installation package of the ProPond Kits. Any silicone on the market will work, as long as the silicone is labeled as "fish safe" or "food safe." Black silicone is much easier to disguise, but clear silicone will work just as well.

Teflon Tape
Using Teflon tape on the threads of certain plumbing fittings is a technique that the Aquascape construction crew used religiously before the days of silicone sealant. It's a common technique used in the plumbing industry and has proven to be very effective in forming water-tight seals on threaded plumbing fittings. Since our silicone sealant is included in our ProPond kits, we suggest using it in place of Teflon tape, but either one works fine. Simply apply one or two layers of tape on the threads of an MPT slip or PRV, and fasten down the bulkhead fitting.

The 18 Steps of Pond Construction from Start to Finish:

Certified Aquascape Contractors (CAC's) are the most qualified and informed  installers in the pond construction  industry. All CAC's are required to attend continual training and education seminars and maintain a proven record of outstanding work and dedicated customer service and support.