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EXCELLENT EXPANSIONS
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utting green expansions are an important part of many golf course renovation projects. In some cases, the goal is restoring putting green perimeters back to their original size. Other times, the goal may be to enlarge greens beyond their original dimensions to add architectural interest or simply to spread traffic over a wider area. Whatever the motivation may be, expanding putting greens can be a very complex endeavor. Early in the planning, it is important to gather soil samples from the proposed expansion areas and the existing putting greens to develop a complete understanding of the appropriate construction process and materials that will be required. Depending on how the existing putting greens were built, and the nature of the surrounding soils, the construction method can vary significantly from project to project – and even from green to green on a given course. When expanding a sand-based putting green, the entire expansion area should be excavated and built to the same specifications as the existing putting green. The expansion cavity should have the same depth as the original, and additional drainage should be installed and connected to the existing putting green drainage system. Perimeter drains should also be added in any expansion areas that may accumulate water along their edges. If there is a vapor barrier around the existing green, it must be cut to accommodate the expansion. Extending the barrier around the new putting green perimeter may be optional depending on site conditions. It is important to ensure that both the gravel and rootzone mixture match as closely as possible with the materials in the existing green. Otherwise, the expansion areas could perform differently than the majority of the putting surface. This complicates future management and may lead to playability issues and turf failure down the road.
16 GCBAA Earth Shaping News | 1st Quarter 2019
When expanding a soil-based putting green, the process is less straightforward. Ideally, soil in the expansion areas matches closely with the soil under the putting surface. If the soils are in fact similar, it may be possible to simply remove the turf and any undesirable organic matter and prepare the existing soil for planting. However, it is important to maintain the same depth of rootzone material in the expansion areas as is found under the green. If recontouring in the expansion areas is desired, or if the topsoil depth is not consistent, it may be necessary to remove the existing sandy rootzone material and shape the expansions in a cavity. Then topsoil would then be replaced at a consistent depth. If the soils are very different in the expansion areas, they must be cored, shaped and filled with a purchased rootzone material that matches the characteristics of the putting green soils. The depth of this mixture should match the depth of
the topdressing layer on the existing green. A soil testing laboratory should be involved in selecting an appropriate material and in quality control throughout the project. Unless the native soil is extremely sandy, it is not recommended to install sand-based rootzone material in the expansion areas of a native soil green. This can lead to disastrous outcomes. Many golfers and decision-makers at golf facilities mistakenly believe that expanding putting greens will be a relatively simple process. The reality is that expansion projects require the same amount of care as a full putting green construction. In fact, extra care is warranted because expansion areas have a strong tendency to fail during stressful conditions. Thin or dead expansion areas next to healthy putting green turf is not something any golfer, superintendent or builder wants to see.
Putting green expansions require thorough planning and careful execution to deliver long-term success. (Image Courtesy of Brett Nagy)