Lake Case Study

By Steve Blackshire, Southeast Regional Sales Manager, Otterbine Barebo, Inc.

The Sprinkler House in Peabody, Mass. installed this water feature in Lafayette Park. This was a retrofit replacing three other fountains in a concrete lined body of water. Due to its size it cannot be cleaned to the bottom as you would a swimming pool, and since this is a residential neighborhood, the unit had to be fairly quiet as well to appease the homeowners along one side of the park.

Considerations When Installing A Water Feature

The purpose of a lake is a great determining factor when choosing the best aeration system. If the pond or lake is used for recreation: fishing, swimming or boating, then the best choice for maximum aeration would be a diffused air system. These types of systems have a shore-mounted compressor that pumps air through weighted tubing to some type of diffuser that lies on the bottom of the lake.

Irrigation lakes need strong surface spray aerators to combat the nutrient load in the water. Many irrigation ponds and lakes are pulling double duty these days as they are also used for an aesthetic feature and asset for the property. When considering water features for these types of lakes keep in mind that multiple smaller units will achieve better results than one large unit. This is said because sometimes the best aeration system is not always the prettiest, so a decorative element can be added to a sound surface spray aeration package to give the aesthetic punch if desired.

This 1/2 acre water feature exists in an estate property in West Chester, Pa. The feature itself is very shallow, only about 5-6 feet deep, which set the stage for frequent algae blooms. There were also game fish in the pond, which required cooler water temperatures, thus a 1HP Sunburst was selected to manage the water long term and during severe winter weather.

Surface spray aerators are best in water 15 feet or less. They are good at breaking down the thermal stratification or temperature layering of the water as well as mixing the oxygenated water that they help produce throughout the pond or lake. Surface spray is the best choice for shallow applications and gives the best boost to Nature?EUR??,,????'???s way of aerating though wave, wind and rain. In the case of irrigation lakes, a properly sized aeration system is needed for oxidizing nutrients as the positive charged oxygen molecule added, attracts the negatively charged molecules of phosphorous, nitrogen, iron, etc. Once coagulated they precipitate or fall out of suspension and bond in the biomass or sludge layer at the bottom. The diffused oxygen added by the aerator also supports the aerobic bacteria colonies, which are the piranhas of a lake. These aerobic bacteria flourish and reproduce in high oxygenated waters and attack the biomass in the sludge layer as well as the load of nutrients from dead fish, runoff etc. By keeping this nutrient load in check through aerobic digestion, the algae and aquatic weeds have fewer nutrients available to them for their proliferation. As you can see it is a cycle that aeration can keep in check and slowly impact if sized properly.

The aeration in a water feature helps to improve water quality and reduce odors and algae blooms from stagnating water. However, it is important when constructing a water feature to choose the location carefully so that obtaining access and getting power to the location will not be a problem.

If you have a lake that is in need of aeration but a pattern of any type is not wanted, then the first product to consider would be a horizontal mixer or aspirator. These systems can influence huge amounts of water, some as much as 1.4 million gallons per minute. If you can influence that amount of water every minute then the results are soon to follow. Horizontal mixers and aspirators are good when a pattern is not wanted, in long, narrow, canal type bodies of water or when you need to keep a cove or windward side of lake or pond cleaned out. They can both be anchored to the bottom and pitched to blow towards the surface or float just under the surface. which make them a good choice to use in stagnant water situations because they can create an artificial current.

The azaleas are in bloom at the Wellspring Apartment complex in Irmo, S.C. where the interest was in the aeration and aesthetics of this water feature. The pond receives storm drainage with a fair amount of runoff pollution as well as serving as a home for several ducks. The fountain is a 5HP with 4, 65-watt lights.

The Littoral Shelf Or Buffer Zone

Littoral shelves, the shallow edge around a lake or pond can be a friend or foe. This shelf is designed primarily in lakes built today as a safety ?EUR??,,????'??net?EUR??,,????'??. They are usually built to be inches up to a couple feet in depth, so that if someone or something was to fall in they are not in danger of deep water and can pretty much save themselves. These ?EUR??,,????'??shelves?EUR??,,????'?? can also be used as planting zones for both aesthetic and environmental stewardship. If planted correctly and with the right types of aquatic plants these shelves can literally filter the nutrients that run off into the water, a sponge of sorts keeping the more troublesome nutrients like phosphorous in check before it reeks too much havoc. If left unattended and not maintained these shallow areas become the problem child that left to run wild is hard to tame.

This before picture is of the Toohey Park water feature located in Wheaton Park District, Ill. The feature itself, is very shallow, about 4-6 feet (1.2-1.8m) at most. One of most apparent sore spots was a stagnant water spot around an island, which had a history of duckweed. The water is easily visible, so an aesthetically pleasing solution that would deter algae growth and stench, and restore the water clarity back to a clean and clear state was necessary.

Since the installation of aerators, the after picture clearly demonstrates the effects of increased oxygen in the water, which ensures the health of the aerobic bacteria, that has helped water clarity, stench, algae, and the overall aesthetics of the water feature. The increased circulation has also diminished the duck-weed, algae and insect breeding.

Electrical Needs

When considering a water feature of any kind, shape or form, you will always need to be aware of what power sources you have available. House current of 110/115 volts is good for smaller ?EUR??,,????'??fractional?EUR??,,????'?? type systems that don?EUR??,,????'???t pull a lot of amps and will be located in smaller ponds. For just about everything else you will need a strong 230-volt source relatively close to where you want to install the water feature. The electrical portion of any installation can be the Achilles heel if proper planning and preparation is not done. Cable runs, the control panel distance from the electrical source, high water mark at flood stage and what is also on the same circuit are but a few things to consider. Properly grounded circuits including a neutral leg, is it single phase or three, are all questions that need to be asked and answered without a doubt. When it comes to electricity you can never be too safe. Always contract a license-QUALIFIED electrician to make all your connections and start up tests.

In the reflecting pond at the Bethany World Prayer Center in Baton Rouge, La. are 12 Otterbine 2HP High Volume (HV) Aerators. The aerators are part of the landscape architect's plan to accentuate the crosses. They were placed in a semi-circle and linked together by 35ft (10.7m) of cable between each one to maintain the symmetry that was part of the plan.

Serviceability For The Water Feature

There is no one silver bullet to managing a lake. However, there are things that we must do as stewards of the environment. Being that most lakes of today are man made, not put there by nature, we have a very big challenge to make sure we can help the lakes age very slowly. Natural lakes, seas and oceans have been around for millions of years because they have been able to circulate and oxygenate themselves from their sheer mass and foot print, allowing them to utilize and harness any type of weather (wind and rain) as a means of maintaining a healthy ecosystem. Not so with the lakes we build today. We must give nature a boost with maintaining a healthy ecosystem by doing our part with pollution and run off, properly stocking the right kinds of fish and recommending a sound aeration system to help proliferate water quality.

There is a special element to this project in Baton Rouge, La., the power is 3 phase (PH) but the pattern needed to be only the dimensions of the 2HP HV. The actual motor on the units are 3HP 230V 3HP motors with 2HP impellers. Smart design on both the electrical engineering and landscape architecture parts, 3PH power over the long haul should equate to about 30% power savings.

Water Facts

1885: Approximate year of the discovery of ozone. This product has been used to purify drinking water since the early 1900s.

14: When generated and injected into the bottom of a lake, ozone becomes 14 times more soluble than oxygen. Source: California Fairways