Geosynthetics on the Links

Geosynthetics and erosion control blankets (ECBs) have made a steady inroad into the many ways soil and sediment can be controlled. Their acceptance has come more easily as the success stories continue to reinforce what many in the EC industry have been saying for a long time: These items provide great solutions for some of nature’s most vexing problems. One application that puts geosynthetics and ECBs to the test in a variety of ways is the golf course. Although many new golf courses look like they are part of the topography and have been there for many years, we in the construction industry know that a lot of hard work, planning, and careful execution go into making a golf course look great. Soil stabilization on golf course terrain is challenging, especially before a good stand of grass is established. The terrain is sculpted to look like a natural part of the landscape and to make the course challenging to play. While the final result is a beautiful golf course, the topography is often severe and prone to erosion during construction. The time and money needed to repair and regrade an eroded area add to the overall cost of construction. Although planning for erosion control was not always a high priority in the past, today golf course developers protect their investment and the environment by taking a proactive stance. Erosion control planning is state-of-the-practice in golf course design. Although geosynthetics and ECBs have been used successfully to stabilize soils in numerous other applications, only recently has their use gained widespread acceptance by professional golf course architects and designers. As the demand for new and challenging golf courses increases, many golf course architects recognize the advantages that geosynthetics offer in erosion control, sediment control, and slope stabilization.Consistency Counts

North American Green DS75 and Amoco SuperGro at Stone Ridge Golf Course.Geosynthetics and ECBs bring an element of predictability to extreme variations in terrain. Because they are manufactured products, they can be produced under stringent material-quality-control standards. They are subjected to rigorous quality-assurance processes, and the variation in material quality can be controlled.Accessibility of the products provides golf course architects with flexibility for design modifications, as these types of products are easily obtained and shipped as needed for construction. Generally, geosynthetics cost less to purchase, transport, and install than do soil and aggregates. Many different types of geosynthetics and blankets are available. These are some of the most popular, especially for golf course applications:Turf reinforcement mats (TRMs) are flexible, synthetic, three-dimensional mats designed for use in conjunction with topsoil and seed or turf to create strong, durable, and continuous soil-root-mat matrices that can provide nearly twice the erosion protection of plain grass alone. Erosion control blankets are temporary, degradable rolled erosion control products composed of processed natural or polymer fibers. The fibers are mechanically, structurally, or chemically bound together to form a continuous matrix that covers the surface and promotes and enhances the growth of vegetation. Open-weave geotextile is a temporary, degradable rolled erosion control product composed of processed natural or polymer fibers woven into a matrix and used to provide erosion control and facilitate vegetation establishment.Erosion control revegetation matrix comprises several layers of geogrids stitched together to form a three-dimensional geomat. Geocellular confinement system is a three-dimensional honeycomb web that covers the surface and is backfilled with soil or aggregate.Staying on CourseFour golf courses recently built in Minnesota’s Minneapolis-St. Paul Metro area have employed a variety of erosion control methods using geosynthetics and ECBs. The materials were selected to reduce the amount of sod needed to keep the topography in place or eliminate the use of sod altogether. A geosynthetic or an ECB placed on the soil surface provides surface stabilization by restricting movement and preventing dispersion of surface soil particles subjected to erosion actions (rain and wind). ECBs can also offer a hospitable environment for seed and assist in revegetation. As Tim Johnson, project manager and superintendent with Spring Hill Golf Club in Wayzata, MN, notes, “Anytime you can seed, you get a healthier stand of grass.”

Amoco SuperGro at Spring Hill Golf ClubGolf Course Superintendent Jim Kassera of The Legends Club credits straw ECBs and a fiber-and-netting composite for their significant role in establishing grass during the short Minnesota growing season. These materials were used to frame the tees, greens, and bunkers. “The sand in these areas did not wash out into the outside areas despite three rainfalls,” reports Kassera. “We did not have to use any sod on the entire project.”By using ECBs and geosynthetics rather than sod, the golf course designer can work with either native soil or preselected soil, preventing the introduction of foreign substances into the soil. Golf course designers seek to create original and challenging courses by planting different kinds of grass to create different playing conditions. By opting for an ECB or a geosynthetic, a designer can customize the grass mixture to get the exact type of grass he wants. The designer who chooses sod is limited to the type of sod available. Larsen cites the Stone Ridge Golf Course in Stillwater to illustrate how the ECB and seed combination gives the golf course architect greater flexibility and control of the grassing plan. Golf course architect Bobby Weed of Ponte Vedra Beach, FL, wanted precise control of the seed mixture to create the look he was after. “He wanted to create a unique course similar to heathland layouts overseas,” describes Larsen. “He avoided the hard edge between grass lines that sod creates by overlapping the seed between the fairway and the primary rough to create an undefined edge. The use of a straw erosion control blanket also helped keep construction on schedule, because large areas could be prepped, seeded, and matted simultaneously.” Tim Johnson favors the ease of maintenance geosynthetics and blankets offer. The Spring Hill Golf Club was designed to take advantage of the hilly terrain native to the area. As a result, most of the fairways are either sloping or adjacent to steep slopes. Johnson notes that a synthetic fibrous matrix made of rapidly degradable netting was needed to retain soil and promote rapid vegetation in the short Minnesota growing season. According to Mark Marienfeld of BP Amoco, the erosion control composite was installed at Spring Hill between late May and October 1998. Because the initial opening of the golf course was scheduled for midsummer 1999, it was vital that the maximum possible ground cover be established in the 1998 growing season. The newly seeded areas covered with the synthetic fibrous matrix quickly began to sprout and established a good base growth before the beginning of winter.As is common practice, seed was added to some areas to thicken growth. Denser grass growth in these areas was accomplished by simply aerating right through the synthetic fibrous matrix and reseeding on top. These newly seeded areas grew in quickly and were successfully established well before the scheduled opening. Areas seeded with fescue and covered with the synthetic fibrous matrix grew in as thick as the Kentucky bluegrass sod used in the rough. Johnson says the synthetic fibrous matrix did not interfere with maintenance or play. “When it’s installed smoothly, the area can be mowed without worry about catching it with a six-tenths-of-an-inch mower.” The same slopes that are desirable to golfers are challenging to the establishment of a good stand of grass. Such topography is subject to soil loss, which impedes the germination and establishment of vegetation. Because most fairways were either sloping or adjacent to steep slopes, an erosion control system was needed that would retain soil, promote rapid vegetation, and not hinder future golfers. Spring Hill employed geosynthetics on steep slopes to keep the soil in place.According to Marienfeld, a bonus feature was a two-person crew’s ability to roll out and pin an entire fairway in an hour, thereby saving time and labor cost over the use of sod in the same area.One final benefit of an ECB is its ability to retain moisture. When sod is laid, it is imperative that it be watered immediately, and the contractor or course superintendent depends on the irrigation system being up and running. If the system is not running, water must be trucked in to avoid the risk of the sod dying before it can get established. With a geosynthetic or an ECB, even if it is not immediately watered, the seed will still germinate. Additionally, the blanket or geosynthetic prevents evaporation. This is especially beneficial when there are dry conditions or drought during construction. Water features such as streams and ponds are an important element of a golf course, but they’re also likely places for erosion to occur. Runoff generally flows to the nearest body of water or low spot and collects. The aesthetic appeal is degraded when sediment runoff ends up in an undesirable location. When the topsoil collects in a low spot, it creates an unsightly area on the course. A composite TRM can be used in and around bodies of water to prevent shoreline erosion. Because geosynthetics allow versatility, shorelines can be seeded with a mixture of wetland plants rather than reinforced with hard armor or riprap. The challenge for any golf course under development is to get the course in playing condition as quickly as possible. That challenge is intensified in climates such as Minnesota’s, where a short growing season is unforgiving if a hardy stand of vegetation is not well established. Spring snowmelt can be detrimental to bare or poorly vegetated topography. Snowmelt also softens the ground so that getting equipment onto the site might not be possible. Therefore, eroded slopes cannot be repaired until the ground is firm enough to withstand maintenance or construction equipment. What’s Ahead, Where to LookMany industry groups are working to advance the science behind the use of these materials. The rolled erosion control materials industry and the geosynthetics industry are active in promoting standards, developing index testing, and educating users on the proper installation and maintenance of these products. There are several industry organizations whose goal is the dissemination of information through conferences, educational materials, seminars, and workshops. Individuals seeking assistance or additional resources on geosynthetics and erosion control materials are encouraged to contact the following organizations. The Erosion Control Technology Council (www.ectc.org) is a nonprofit organization whose mission is to develop performance standards, uniform testing procedures, and guidance on the application and installation of rolled erosion control products.The Geosynthetic Materials Association (www.gmanow.com) serves as the central resource for information regarding geosynthetics and provides a forum for consistent and accurate information to increase the acceptance and promote the correct use of geosynthetics.The American Society of Testing and Materials (www.astm.org) develops voluntary consensus standards, related technical information, and services.The International Erosion Control Association (www.ieca.org) provides education, resource information, and business opportunities for professionals in the erosion and sediment control industry.