Turf Magazine - October, 2008

SOUTH FEATURES

Low-Impact, Lakefront Landscaping

Techniques to protect the lake and surrounding areas
By Ron Barnett

When Duke Power Co. built Lake Keowee in the foothills of the Blue Ridge Mountains in the early 1970s, its primary purpose was to serve as a source of coolant water for three nuclear reactors and to produce hydroelectric power.

The pristine shoreline, however, was a jewel waiting to be discovered by developers who saw enormous potential for upscale, lakefront subdivisions in this northwest corner of South Carolina.

Beginning with a nationally advertised retirement community called Keowee Key, 130 housing developments have sprung up along the more than 300 miles of shoreline of Lake Keowee over the past two decades.

Photos by Ron Barnett.
Lakeside homes on Lake Keowee.

All this construction has not come without some impact on the environment, however.

The Friends of Lake Keowee Society (FOLKS) has stepped in to try to minimize threats to this 18,372-acre reservoir.

An integral part of the group’s effort is promoting the use of landscaping techniques that protect the lake and the surrounding area.

With that goal in mind, FOLKS has set up a demonstration project to educate homeowners on the use of native plants that thrive with minimal use of water, fertilizers or other inputs beyond what nature provides. The project also showcases such features as pervious concrete to eliminate problems associated with stormwater runoff, and the green roof concept, where plats of plants are used to reduce energy consumption by moderating temperatures inside homes.

Photos courtesy of FOLKS.
Native plants recommended for low-impact, lakefront landscaping.

“It’s a grand experiment,” said FOLKS Executive Director Ben Turetzky.

Green roofs

The idea of growing plants on rooftops dates back at least to the famous Hanging Gardens of Babylon, built around 600 B.C.

Two graduate students from Clemson University have been working with FOLKS to prepare a demonstration of the concept on a shed on the grounds of the group’s site near Seneca, S.C.

Starting with cuttings of different varieties of plants donated by Saul’s Nursery in Atlanta, the students are growing greenery in 2-square-foot trays that will be placed on the roof. They will experiment to determine which varieties work best.

The growing medium is a form of shale heated in a kiln to high temperatures that makes it porous, which enables it to absorb lots of water. When watered to capacity, each tray weighs 90 pounds.

A rubberized membrane protects the roof and allows the green roof to do its heat exchange work. When rainwater in the tray evaporates, it sucks heat out of the room below the roof, providing cooling in summer. In the winter, the greenery acts as insulation, reducing heating costs.

Ben Turetzky, executive director of FOLKS, discusses the group's environmental efforts.
A blueprint of the FOLKS demonstration project.

The downside is that the added weight on the roof requires stronger reinforcement in the structure. That extra cost is offset somewhat, however, by the elimination of the need for shingles or other roofing material, other than a composite of rubberized sheets that are heat-sealed together.

FOLKS will set up a drip irrigation system for the green roof, but doesn’t anticipate it will be used if the area gets normal rainfall and dew, Turetzky said.

The green roof project will provide a learning experience for carpentry students from nearby Hamilton Career Center, a high school vocational program, who will develop specs and handle the construction, he said.

Pervious concrete

FOLKS is also encouraging landscapers and builders to use pervious concrete in developments along the lake. For landscape companies with the capability to install underground piping and tanks, there’s an economic, as well as environmental, opportunity.

FOLKS has set up a system in which a series of pipes collect water under a pervious parking area. The pipes run to two 1,000-gallon septic tanks, with overflow going to a 2,000-gallon bioretention cell, a large swale filled with plants that will be able to absorb hydrocarbons and other chemicals. FOLKS is working with Clemson Extension Service to choose plants that will absorb or decompose various types of organic materials and metals.

“Anything that is on this surface, whether it’s brake fluid, antifreeze, oil dripping from a car, gasoline, when the rain first hits, it’s going to wash that all off and it’s going to go into any nearby stream,” Turetzky said. “The whole idea here is to capture the water and anything that is in it.”

Photo courtesy of FOLKS.
A grass paver path at Lake Keowee.

Drought-resistant plants

The use of buffer plants between chemically treated turfgrass and landscaped areas and the lake is another key recommendation FOLKS is working to educate Keowee property owners about.

Once established, certain varieties need little watering and are well suited to keep nutrients and other additives from entering the reservoir.

FOLKS recommends plants from a list developed by Lisa Wagner, director of education at the South Carolina Botanical Garden.

Southeastern natives on the list include butterfly weed, goldenrod, false wild indigo, blue star, black-eyed Susan, blazing star, New England aster and Indian grass.

Others that aren’t native to the South­east, but that do well in the region, include purple coneflower, perennial Salvia, rosemary, white gaura, lavender, germander and lavender cotton.

The demonstration project will also include rain barrels to collect rainwater from the roof, which will be used to provide what irrigation is needed to help the plants become established.

A close-up of the plants that will go on the rooftop system.
 
Photo courtesy of FOLKS.
Example of a green roof on a mower building at a property at Lake Keowee.

Battles fought

The lakefront development has been a boon to landscape companies in this corner of South Carolina, and FOLKS has been a force in protecting Lake Keowee since it was founded 14 years ago.

The society now has 1,700 families and about 100 corporate and business members. Its mission is to preserve and protect Lake Keowee and its watershed for future generations through science, conservation, educational outreach and good governance.

“The lake is really very clean,” Turetzky said. He should know; his group has done studies of water clarity throughout the reservoir.

Among the battles FOLKS has won along the way is a recent change in state law requiring that septic tanks be at least 75 feet from a body of water. The previous limit was 50 feet.

The group also documented sewer overflows from the nearby city of Walhalla, S.C., which led to replacement of faulty pipes and brought fecal coliform down to acceptable levels.

FOLKS also persuaded Duke Power Co. to do a shoreline management plan and a recreation use and needs study.

Turetzky, a retired engineer and marketing manager for Michelin Tire Co. who lives at Keowee Key, said the group’s primary aim now, though, is the low-impact landscaping program, which FOLKS hopes will guide the continuing development of this growing lakefront area.

Ron Barnett is a freelance writer and has been a frequent contributor to Turf over the years. He resides in Easley, S.C., and is always on the lookout for new and interesting stories in the Carolinas, Georgia and east Tennessee.