Key Points
Sand bunkers come in all shapes and sizes, limited only by the imagination of the golf course architect and the client’s construction and maintenance budgets. Regardless of the form, all sand bunkers should be designed and built to encourage rapid drainage, to minimize contamination of the bunker sand by silt and soil, and to reduce the movement of bunker sand from the face of the bunker toward the bunker bottom. This will minimize the cost of upkeep as well as maximizing the function and effective life of the bunkers.
In the interest of accessibility and inclusion, the golf course architect should give thought to how golfers of all physical abilities can safely walk in and out of the bunkers.
A final important design consideration is how the bunkers will be maintained. Will the bunker be large and accessible enough so that it can be raked mechanically (by e.g. Sand Pros, bunker rakes) or will the sand need to be raked by hand? How about the grass on the bunker faces and surrounding mounds and hollows – can a triplex mower manage the terrain or will the job require smaller machinery such as a fly mower? How often does this grass need to be mowed to maintain playability? The number of man-hours needed to maintain sand bunkers is a big piece of the typical golf course's annual maintenance budget so efficiency should at least be considered.
Sand bunker upkeep often demands a large percentage of the maintenance budget. It may be wise to examine whether expectations for perfect consistency are realistic and if limited maintenance resources might be better used on areas that receive more play.
Where budget is a concern, the golf course architect can have a positive impact on the long-term economic sustainability of a golf course by minimizing the size and number of sand bunkers and by sourcing sand locally. Grass bunkers, hollows, mounds, swales, and waste bunkers (which are less formal, are built with less expensive materials, and are less maintenance intensive than formal sand bunkers) can all be good substitutes without sacrificing strategy or aesthetics.
Sand bunker construction is a multi-step process that needs to be coordinated with drainage and irrigation installation, in addition to grassing. There are differing opinions on the best time to install perforated subsurface drainage pipe within the bunker (if it’s deemed necessary) but care must be taken to avoid clogging the pipe with silt from adjacent construction activity before grass has established.
Variety in bunker forms.
There is seemingly infinite variety in the form of bunkers – sand bottomed or grassy hollows; high sand flash, grass face, or stacked-sod revetted face; formal or naturalized edges; gentle and shallow or severe and deep. Some forms (e.g. bunkers with high and steep sand faces; bunkers that require extensive hand maintenance) are much more expensive to maintain. Other bunkers (e.g. revetted sod) will have a shorter lifespan and require more frequent repair and replacement. That’s why it’s always a good idea for the golf course architect to discuss budget and expectations with the client and golf course superintendent prior to finalizing the design. Once the construction budget and ongoing maintenance expectations have been discussed with the client, the style, quantity, and form of the bunkers on a golf course is limited only by the imagination of the golf course architect and the ability of the golf course builder and/or shaper to physically manifest that imagination.
There are, however, some typical construction practices that will help to ensure that a bunker of any form or style will function properly and enjoy a longer lifespan (drain quickly, minimize contamination of the bunker sand with silt or soil, reduce movement of sand from the bunker face toward the bunker bottom). Furthermore, there is an obvious connection between how well the bunkers are functioning and how costly and time consuming they are to maintain, which plays a big role in the maintenance budget and, ultimately, the long-term economic sustainability of the golf course.
The following steps illustrate how bunkers move from a concept to reality:
Differences in Design Detail
As discussed in Step 2 – The Various Modus Operandi of Golf Course Architects, there are different philosophies for how detailed the bunker design should be during the design of the golf course. Some golf course architects work out most of the details during the design phase, provide extremely detailed grading and drainage plans to the golf course builder, and make only small modifications in the field as required. Other golf course architects start construction only with a budget for the total bunker area but retain full license to determine exactly where and how large each of the individual bunkers will be as construction progresses. The ease of the site for construction and the golf course architect’s relationship with the client and the people building the bunkers will ultimately determine the level of detail in the design documents that makes the most sense.
Approval in Subgrade
Mass grading operations will raise or lower the disturbed areas on the site to within 2 or 3 feet (1 meter) of design finished elevation. At this point the golf course architect should have a good idea where the bunkers are going to be located. Rough and fine shaping operations will then progress from hole to hole and will shape the bunkers to subgrade levels (not including sand cap or topsoil) in the locations, sizes, and forms that the golf course architect has specified or agreed to.
The golf course architect should be working with the shapers throughout this process to inspect, tweak, and approve each of the bunkers at their subgrade levels. This approval gives the “bunker crew” (whether under the direction of the golf course builder or a shaper) license to proceed to the finishing steps.
Finishing the Bunkers
“Finishing” the bunker includes placing topsoil or a sandcap to bring the area surrounding the bunker up to finished grade and using small machinery and hand labor to get all of the bunker surrounds and the bunker floor (or bowl) finalized, compacted, and stabilized. Depending upon the steepness of the proposed bunker face and the severity of the climate, a stabilization product (fabric, blanket, spray, impermeable or permeable layer, etc.) that is designed to quickly infiltrate water while holding the bunker sand in place may need to be applied/installed at this time. If the bunker is to be revetted, the stacked sod (or artificial turf) wall will be built during this step (see detail below). Installation of nearby irrigation and drainage may also be happening simultaneously.
Briefly, on bunker stabilization products – there are now a wide variety of products that are designed to be permeable, hold bunker sand in place, and minimize soil and silt contamination of the bunker sand. In some cases, the climate makes these products very helpful (e.g. frequent, heavy rains causing regular wash-outs or near constant high-wind conditions making it difficult to keep the sand in place). In other cases, the design concept (e.g. very steep sand faces) will be the main reason why these products are called for. When budget is a concern, a design solution can usually be found, even in difficult climates, to make the sand bunkers functional and visible without additional stabilization measures.
Adding Drainage to the Bunkers
Since a bunker is often lower than its immediate surroundings, the rapid conveyance of rainfall and irrigation water out of the bunker should be a primary concern in its design and construction. First, the adjacent ground will ideally be contoured with mounds and swales to divert the majority of overland flow away from the bunker. Second, the irrigation water and rainfall that does find its way into the bunker must have an avenue to exit quickly. Golf courses that are built upon free-draining sand can often rely upon the rapid infiltration rates of the native soils and forego subsurface bunker drainage. Most golf courses are not built upon free draining sand, however, and would therefore benefit from at least some subsurface pipe at the low point(s) of the bunker (whether grass or sand) to rapidly remove the nuisance water that will otherwise collect.
The subsurface drainage pipe within the bunker bowl will often be perforated and within a gravel trench and will connect to a solid exit drainage pipe that is outside of the bunker. The solid pipe will bring the water to either a nearby drainage sump, into the larger subsurface storm drainage network, or will daylight to a SuDS conveyance feature. A “clean-out” pipe riser is also often added on the high side of the bunker, which will allow the maintenance staff to blow-out the perforated pipe and gravel trenches with water or air should it become clogged with silt and stop draining as quickly.
There are different theories about the best time in the construction process to install the interior, perforated pipe but it is common practice to install the exterior, solid exit drainage pipe while the bunker is being finished. One common practice in climates with more intense precipitation is to wait to install the interior, perforated drainage pipe and gravel tranches until after grass has established around the bunker and just before placing the sand. This is due to the possibility that, without grass to catch it, silt and soil kicked up by adjacent construction activities can wash into the bunker and clog the perforated pipe and gravel trenches, causing them to function less than optimally.
See the following construction details for a common method of bunker drainage:
Grassing
Once a bunker has been finished and stabilized to the satisfaction of the golf course architect, and the disruptive activity of nearby irrigation and drainage pipe installation is complete, the next step is to establish grass around the edge of the bunker, which will help to prevent soil and silt from washing into the bunker bowl. For grass bunkers and hollows, grass is established within the bowl too. Sod is typically used because it establishes significantly faster than seed (and helps to avoid the issue of erosion), even though it is more expensive initially.
Below is a typical construction detail for sodding around a sand bunker:
Edging, Perforated Drainage, and Sand Placement (for Sand Bunkers)
Once grass has established around the perimeter of the sand bunker bowl, the final details can be completed by the bunker crew.
Edges can be cut to match the look desired by the golf course architect. Both formal and more “natural” bunker edges will be perfected by hand labor.
The interior perforated drainage pipe will be installed (if it hasn’t been already) and connected to the exterior solid exit drainage pipe.
Bunker sand is typically selected and sourced during the early phases of construction based on physical and aesthetic characteristics, availability, and cost. The consulting agronomist and golf course architect will make recommendations and the golf course builder will source samples for approval by the client.
The bunker sand is spread and compacted to the desired depth (typically 4-6" (10-15 cm) on the bunker floor and 2-3" (5-7.5 cm) on the flashed face. Space may be left between the edges of the bunker bowl and the sand during grassing and grow-in to collect any silt or debris that may still wash into the bunker before full establishment of the grass.
Final detailing and clean-up can happen by hand after the turf has adequately established.
Sustainability and Accessibility in the Design and Construction of Bunkers
There is widespread discussion in the golf industry about the constant “state of perfection” and consistency that is now expected by golfers of sand bunkers (see Rethinking Bunker Maintenance, George Waters, USGA Green Section, as one example). As the result of countless hours spent by the maintenance staff to meet the heightened expectations of today’s golfer, what was once meant to serve as a penalty is now often much less than that for the better players (while still penalizing high handicap golfers). In extreme cases, bunker upkeep and maintenance accounts for as much or more labor expense as putting greens, where significantly more play takes place! Whether or not this is a good use of limited resources is a discussion for another time and place.
Outside of the maintenance practices that happen once the golf course has opened, the golf course architect can have a big impact on the long-term economic viability of a golf course by the careful consideration of the actual purpose (and need) for each bunker as well as the selection and sourcing of bunker sand. At most golf courses the maintenance budget won’t be unlimited so what follows are some common-sense questions that should be asked by the golf course architect during the design phase:
How many bunkers does the golf course need and how large do they need to be for the intended strategy to work?
How steep and complex do the bunker faces need to be for good visibility and to administer the intended penalty? If they’re steep enough (or the climate harsh enough) to necessitate a bunker stability product (fabric, blanket, spray, etc.), what’s the most cost-effective and maintenance reducing product over the short-term and the long-term given an individual bunker’s size, location, and orientation? Is there a way to reconsider the design or placement of the bunkers so they can still function without that stability product?
How will the bunkers be maintained? Small and intricately shaped bunkers with steep banks on all sides may be impossible to access by even small maintenance equipment (like a Sand Pro or bunker rake). These will require hand raking, which can be very costly over the long-term. Much like tees, multiple access points for golfers and maintenance staff should be provided to reduce compaction and wear of the surrounding turf.
Grass bunkers (which are shaped similarly to sand bunkers but have grass in the bowls and may be shaped to encourage overland drainage (see examples at Bandon Sheep Ranch - picture below)), swales, "chocolate drops", and mounds are golf hazards that are significantly easier and less expensive to build and maintain than sand bunkers. Are there places on the golf course where these features can be used instead of sand bunkers to save the cost of sand and maintenance without compromising visibility, strategy, or intended difficulty of recovery? (see https://golf.com/travel/ways-architects-use-grass-hazards/ for more insight).
Can sand with acceptable physical characteristics (particle size, particle shape, hardness, color) be quarried on-site or locally to reduce material costs and transportation costs, and to benefit the local economy?
When building revetted bunkers, does it make sense to use stacked recycled artificial turf rather than sod? This is a newer technique and, despite likely higher upfront cost, the artificial turf has been shown to last longer with lower ongoing maintenance costs.
Are there instances where “waste bunkers” can be used instead of sand bunkers? Waste bunkers are different from sand bunkers in that they are not considered “specially prepared areas of sand” under the rules of golf, giving the golfer more leeway in how he or she plays from within them. For practical purposes, waste bunkers are more informal hazards that have elements of a sand bunker – sand, crushed shells, loose soil, vegetation – but don’t have the same specially sourced sand and aren’t maintained as intensively. These areas are therefore significantly less expensive than sand bunkers to build and maintain while still reinforcing the intended strategy. (As an aside, waste bunkers are also often more impactful as hazards for low handicap players than formal bunkers simply because they aren’t as perfectly maintained and predictable.)
Finally, accessibility to the bunkers by all golfers should be considered. Will golfers with physical limitations be able to safely walk into and out of the bunkers? Multiple access points for golfers with physical limitations will make the playing experience more inclusive and will also help to distribute wear and compaction on the surrounding turf.
The answers to all of these questions will meaningfully impact the golf course’s construction budget and ongoing maintenance budgets, so clear communication and understanding of the client’s expectations and budget is a must.
A purpose-built grass bunker at Bandon Sheep Ranch
Waste bunkers alongside formal sand bunkers at Sand Valley Golf Resort
Contact Sustain Golf for More Information!
We would be happy to make recommendations or answer any questions that you might have about sustainable and accessible golf course design, construction, or maintenance. Visit www.SustainGolf.com or contact us at the following address for more information: Contact@SustainGolf.com.
The European Institute of Golf Course Architects (EIGCA), in partnership with the GEO Foundation, has developed a continuing professional development program for its members called Raising the Standard of Sustainable Golf Course Development, or RSSGCD. This is the industry’s only structured program in the world to specifically train golf course architects in sustainable golf course design, construction, and maintenance best practices. A Sustain Golf team member has attained Stage 3 of this rigorous program.
A Sustain Golf team member is also currently serving on the EIGCA’s Sustainability Committee and is a GEO Certified Accredited Sustainability Verifier.
We firmly believe that common sense sustainable design, construction, and maintenance practices are the keys to the long-term survival of the game of golf. We aspire to be on the leading edge of applying sustainability concepts to golf course design, construction, and maintenance.
We will spend every day for the duration of the project on-site and/or coordinating with all contractors, subcontractors and professional consultants to be sure that no opportunities are lost and that the best golf course for your property is realized.
Up Next:
Step 13 – Feature Construction Spotlight: Putting Greens
Sustain Golf is a collaborative group of like-minded qualified golf course architects. We are also qualified and experienced as civil engineers, vertical architects, and project managers. We have the breadth and diversity of experience and knowledge to offer a full suite of golf course design and construction services, from first concept to opening day on your new or remodeled golf course.
References:
Hurdzan, Dr. Michael J. Golf Course Architecture: Design, Construction & Restoration. Chelsea, MI: Sleeping Bear Press, 1996.
Isaacson, Desi. 2 Ways Architects Use Grass as Hazards (Other Than Growing Up the Rough). Retrieved from https://golf.com/travel/ways-architects-use-grass-hazards/Richardson,
Forrest L. & Fine, Mark K. Bunkers, Pits & Other Hazards. Hoboken, NJ: John Wiley & Sons, Inc., 2006
Waters, George. Rethinking Bunker Maintenance. Retrieved from https://www.usga.org/content/usga/home-page/articles/2018/06/rethinking-bunker-maintenance--embracing-the-imperfections.html
Photo Credits:
Photo collage - Mark Alexander, Matthew Schiffer
Sand Valley Golf Resort – Minneapolis Star Tribune (retrieved from https://www.startribune.com/sand-valley-golf-course-in-wisconsin-is-product-of-big-dreams/421692173/)
Bandon Sheet Ranch - The Fried Egg (retrieved from https://thefriedegg.com/just-the-yolk-bunker-maintenance/)
Peer Review:
Dr. Keith Duff, former UK government wildlife agency Chief Scientist, current Golf Environment Consultant
Brett Hochstein, Golf Course Architect, Hochstein Design, LLC
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