The origin of bunkers and what they are used for
If you play golf, then we are pretty sure you’ll already know what a bunker is, but for those who don’t, they are shallow pits that are filled with sand. Also known as sand traps, bunkers are a common feature on golf courses across the world. Bunkers often incorporate a raised lip or barrier along the edge and a more difficult to play out from than that of a grassed area.
It is said the bunkers were created in the early adaptations of golf and were developed on links courses. These courses were located near shorelines where sand w. This sand would create ‘burns’ that ran into the sea and were eventually shaped into the bunkers that we know today.
The modern-day bunker is now an integrated part of any golf course. They are positioned to provide challenges to golfers or to ensure balls are caught rather than being hit out of bounds. There are now a variety of different bunkers to ensure the game of golfs keeps moving forward and skills are truly tested.
but how are these sandy hazards created?
Bunker design process and creation
Design
As mentioned, modern golf now looks to incorporate bunkers into the golf course design process because of how essential they are to the game. Firstly they are incorporated into any new golf course designs that a golf course architect has created. There are a variety of different bunker styles that an architect has at their disposal, each with variables such as size, shape, lips, and barriers. Bunker styles include:
- Traditional Bunker – Clean line and edges.
- Revetted Bunker – Layered edges, usually creating a large lip.
- Waste Bunker – Large sandy area that incorporates the landscape. These are usually seen in hotter climates.
- Amoeba Bunker – Low-lying and flat with an organic shape. Similar to the cell that is it named after.
Location
The position of a bunker is important because it will dictate the role that it will play on the golf course. When designing a course, architects will look to position bunkers in specific areas to enhance enjoyment whilst still providing challenges. Bunker roles include:
- Carry Bunkers – Placed just short of the tee shot target zone, alongside the favorable side of a fairway that an approach shot is likely to be played.
- Target Bunkers – Play a similar role to the carry bunker, however, they are placed beyond the tee shot target zone where the best angle for the next approach shot is likely to be.
- Catch Bunkers – They look to catch golf balls between safe grass areas and unsafe areas such as tree lines.
- Approach Bunkers – Placed between 50-100 yards from the green and usually feature on par 5’s or long par 4’s. It also helps to indicate the position of the green.
- Greenside Bunkers – As the name suggests, they are placed alongside the green and are usually the deepest bunkers because the ball doesn’t have to travel far to reach the hole.
Topsoil strip
Once the design and location of a bunker have been finalised, the construction process can begin. This starts with a topsoil strip where the turf will be removed and stored if it is in good enough condition to be reused. Once the turf has been removed the topsoil below can be stripped away using the appropriate machinery and then stockpiled for reuse.
If there is an existing bunker, then you’ll need to locate the existing drainage pipes and remove them with any material.
Shaping and subgrade
Once the area has been stripped it can now be shaped to the agreed design. Graded stakes will be placed along the area to ensure the final bunker reaches the desired depth and shape. Materials such as aggregates will be imported and placed within the stripped area and spread to ensure there is a consistent depth, and the correct shape is achieved. This material will then be compacted using appropriate machines to provide a stable subgrade.
It’s important that the bunker floor is cleaned out and graded to a smooth finish. This allows for an increased flow of water, helping with drainage properties.
Drainage
There is nothing more annoying than a badly drained bunker. If a bunker doesn’t drainage effectively it will cause the sand to erode, revealing the subgrade below. A badly built bunker can also become a very expensive feature for golf courses to maintain.
Upon completion of the subgrade placement, drainage trenches and a soakaway will be dug out so that perforated drainage pipes can be placed underneath the bunker. These pipes will then be surrounded by coarse aggregate material such as pea gravel or pipe bedding to allow water to pass through.
A geotextile layer may be placed above to ensure that the aggregates and bunker sands don’t mix.
Edges
The edge of the bunker can now be formed by placing the topsoil around the edge of the green. Turf can then be placed alongside the bunker to form the edge.
If you are looking to create a revetted bunker, you’ll now place turf sods in layers starting from the bunker base. Each sod should be laid one on top of the other and offset like brickwork until the desired height is reached. The general rule is for the angle of the lip to be 135°, which is achieved by placing each layer 40mm further back, however, this can be dependent on the thickness of the turf sods.
Sand selection & placement
The selection of appropriate sand is important to ensure proper drainage of rainwater or irrigation water. You should look to choose sand based on accredited laboratory testing that meets the following criteria.
- Drains well (more than 20 inches per hour).
- Angular Particles (Better for compaction).
- Doesn’t contain gravel or fine particles.
- Has an angle of repose steeper than that of the bunker face. This means the sand won’t move when placed on a steep slope.
- Has a high penetrometer rating.
- Desired colour.
- Use uncontaminated sand.
Once the correct sand has been selected it should be spread evenly across the bunker floor to a depth of 100mm. It then needs to be compacted to create an even surface that the golf balls can enter, this also prevents sand from blowing away in windy conditions.
Sources
How to construct a revetted bunker | European Golf Design (egd.com)
NCG’s Golf Glossary: What is a bunker? (nationalclubgolfer.com)
Renovating golf course bunkers: 7 key considerations – GCMOnline.com
