Feature Interview with Bob Randquist, CGCS
Part II
December, 2004

Bob Randquist has been the golf course superintendent at Boca Rio Golf Club in Boca Raton, Fla., since 1998. Previously he was the golf course superintendent for 19 years at Southern Hills Country Club in Tulsa, Okla., and for 2 years at Quail Creek Golf and Country Club in Oklahoma City. He has also served on the USGA Green Section Committee for the past 15 years.

During his tenure as superintendent at Southern Hills Country Club, he hosted the 1982 and 1994 PGA Championships, the inaugural 1987 USGA Womens’s Mid-Amateur Championship, and the 1995 and 1996 PGA Tour Championships. Bob is currently teaching a seminar for the Golf Course Superintendents Association of America titled ‘Hazardous Duty……Basic Bunker Maintenance’, and was recently elected to serve a 2 year term on the Board of Directors for the GCSAA.

A native of Anadarko, Oklahoma, Randquist graduated from the University of Oklahoma in 1972 with a bachelor’s degree in metallurgical engineering.

The purpose of his seminar ‘Hazardous Duty…Basic Maintenance’, much of which he has graciously allowed GolfClubAtlas.com to reproduce in this three part Feature Interview, is to help those attending gain knowledge on bunkers, in part by:

  • Understanding the design strategy that bunkers provide for the game of golf.
  • Understanding factors that golfers use to form opinions regarding bunker playability.
  • Learning how bunker design and construction impact bunker maintenance.
  • Identifying how sand selection and depth impact bunker maintenance and playability.
  • Identifying how surface related bunker maintenance practices affect playability.
  • Identifying methods for solving problems associated with poorly designed or constructed bunkers.

PartII of this Feature Interview centers on the methods and costs for maintaining bunkers.

What factors influence the implementation of a bunker maintenance program?

The primary factors that influence golf course superintendent’s decisions regarding the development and implementation of bunker maintenance programs are:

  1. type of sand in bunkers
  2. depth of sand in bunkers
  3. raking and grooming methods
  4. edging methods
  5. bunker maintenance costs

Golfer’s perceptions and expectations, and the degree of difficulty for bunker playing conditions are significantly impacted by the decisions made regarding these factors. They are all closely related to each other and every decision made regarding one of these factors has an impact on decisions regarding each of the other factors.

Whatare the factors that make up the differenttypes of sand?

In an article titled ‘How to Select the Best Sand for Your Bunkers’ in the January/February 1998 issue of the ‘USGA Green Section Record’, Jim Moore, Director of Construction Education Programs for the USGA, lists seven criteria that should be considered when selecting bunker sand. These criteria also play a very important role in our decisions regarding the best methods for maintaining bunker sand.

  1. Particle size…….Generally, sand used in bunkers should be composed of particles with a large majority in the size range of 0.25-1.0 mm. Silt and clay (particles below 0.05 mm) should be minimal, since they are associated with surface crusting. Sands with a higher percentage of coarser particle sizes tend to be resistant to packing and often provide playing conditions for bunkers that are too soft. The result may be too many buried lies and a degree of difficulty that is too severe. Sands with a higher percentage of finer particle sizes tend to pack too tightly and provide playing conditions for bunkers that are too firm. The result may be an absence of any buried lies and a degree of difficulty which is too easy, drainage problems which arise due to poor infiltration rates, or a golfer’s perception that there is not an adequate depth of sand in the bunker because a golf club will not easily penetrate the sand surface. Selecting sands with particle sizes in the proper range is a critically important decision, but we cannot assume that adherence to proper guidelines for this factor alone will identify the best sand for bunker use. Other factors must also be considered.
  2. Particle shape and penetrometer value…….The shape of the sand particles also has a strong influence on bunker playing conditions. Sand particles that are spherical (round, smooth surfaces) in shape are very resistant to packing and tend to result in bunker playing conditions that are too soft and increase the possibility of fried-egg lies. Sand particles that are angular (many sharp, well-defined edges) in shape tend to provide firmer bunker playing conditions and tend to eliminate the possibility of fried-egg lies. Soil testing laboratories can perform a penetrometer test to measure sand’s resistance to compression. The value from this test is used to predict the sand’s potential for fried-egg lies. The USGA offers these guidelines based on penetrometer testing:
  3. Potential for Fried-Egg Lies
    (Thomas Turf Services)
    Penetrometer ReadingFried-Egg Potential
    Greater than 2.4 kg/sq. cm.Very low tendency to bury
    2.2 to 2.4 kg/sq. cm.Slight tendency to bury
    1.8 to 2.2 kg/sq. cm.Moderate tendency to bury
    Less than 1.8 kg/sq. cm.High tendency to bury
    Greater than 2.4 kg/sq. cm.Very low tendency to bury

    The relative angular or spherical characteristic of sand particles has a major influence on bunker playing conditions, and also on the selection of bunker raking and grooming methods required to produce the desired degree of difficulty for bunker shots. Golfers often express a preference for either a firm or a soft ‘feel’ as the golf club enters the sand surface during the execution of their bunker shot. Some prefer the ‘bounce’ provided by more tightly packed angular sand particles, while others prefer the ‘soft feel’ provided by more spherical sand particles. Raking and cultivation methods necessary to produce these desired results can be significantly different depending on the dominant shape characteristic of the sand particles in a bunker sand.

  4. Crusting potential…….Crusting is the formation of a layer (1/8′ to ¼’ thick) of dried, stiff sand on the surface of the bunker. This crust layer tends to cause a golf club to excessively bounce off the sand surface when a bunker shot is played, and severely hampers the player’s ability to hit through the sand and have a desirable cushion of sand between the clubface and the golf ball. Bunker shots from crusty lies are very unpredictable and difficult. Crusting is directly related to the percentage of silt and clay in the sand. Soil testing laboratories can perform a test that indicates the relative tendency for crusting to form on a bunker sand surface. The crusting potential is usually rated and reported as none, light, moderate or severe. If the crusting potential is moderate or severe, more frequent raking and cultivation are required to maintain the desired bunker playing conditions. Crusting potential for a golf course’s bunkers usually increases as the bunker sand ages. Silt and other fine particle contamination of the sand occurs due to bunker slope washouts during heavy rainfall events, dust blown in by high winds, silt contaminated irrigation water and grass clippings and other organic debris becoming mixed in the sand. As a result, bunker maintenance methods used for a golf courses’ bunkers may have to be modified at some point in time to accommodate for an increase in crusting potential of the bunker sand.
  5. Chemical reaction and hardness……Some laboratories also test the sand for its chemical reaction (pH). Sands with an extremely high pH (>8) are likely to be strongly calcareous and subject to physical and chemical weathering. This weathering can result in changes to the sand’s particle shape and size characteristics over a period of time, causing the sand to pack more tightly than when it was originally installed in the bunkers. Laboratory tests can give an accurate indication as to whether or not this is a potential problem for bunker sand.
  6. Infiltration rate…….Infiltration rate indicates the sand’s ability to drain properly and is usually referred to by laboratories as saturated hydraulic conductivity. It is critical that bunkers drain well after rain or irrigation events. If the sand retains excessive moisture or pools of water for extended periods of time, the desired playing conditions for bunkers will not be attainable. To allow for adequate bunker drainage, infiltration rates should be at least 20 inches per hour. Like crusting potential, infiltration rates usually change as bunker sands age. Silt and fine particle contamination result in reduced infiltration rates that may necessitate modifications of bunker maintenance methods. In worst case scenarios where poor infiltration rates prevent water from reaching the bunker drainage system, a portion or all of the bunker and may have to be removed and replaced with new sand. The moisture content of the sand also has a direct influence on the firmness of the bunker’s playing surface. If infiltration rates are too high the bunker sand dries too quickly and may not have any significant moisture retention capacity. The sand surface will have a tendency to be too loose and no effort at compacting the sand will properly firm the sand surface and provide the desired bunker playing conditions. Moderate infiltration rates between 20 to 40′ per hour usually provide the most workable conditions for the bunker maintenance methods necessary to provide the desired bunker playing conditions.
  7. Color…….Although sand color is important to many golfers, it should not be the primary factor considered for selecting a bunker sand. Golfers usually prefer lighter tan or white colored sands due to the contrast they provide with the green grass. Some bunker sands are so white that golfers complain that the reflective glare from the sand surface is blinding or impairing their vision when they are playing a bunker shot. Availability and/or cost of the bunker sand often present a major challenge to providing a mandated color of bunker sand. The best solution is to select the sand that provides the best bunker playing conditions and desired degree of difficulty, regardless of the sand color.
  8. Overall playing quality…….Every golfer has their own opinion regarding the overall playing quality of any particular bunker sand. Their opinion is based on their personal preference and perception of how difficult or easy bunker shots should be. It is also influenced by their opinion of how the sand in the bunkers should look and feel. Their opinion may even change from day to day depending on the number and quality of their bunker shots. Whether you agree or disagree with the concept, the most commonly expressed golfer’s desire is that bunkers offer uniform playing conditions in all the bunkers, and that the bunkers offer those playing conditions on a daily basis. The first step toward meeting that goal is having sand in the bunkers that conforms to the previously mentioned standards for particle size, particle shape and penetrometer value, crusting potential, chemical reaction and hardness, infiltration rate and desired color. If the bunker sand does not conform to these standards, the ability to provide consistent playing conditions is much more challenging to the golf course superintendent. Because of the complex relationship of these six factors and their effect on each other, golf course superintendents must develop a thorough understanding of how each piece of the bunker sand puzzle affects the overall bunker maintenance program. A sense of the overall playing quality of a bunker sand can only be obtained by soliciting, listening to, and carefully analyzing the opinions of the golfers playing our golf courses.
    1. During the past ten years golf course equipment manufacturers have steadily improved the types and configurations of rake attachments available for mechanical bunker rakes. Rake attachments are available with differing lengths of ‘teeth’ on a set of flat rake blades that will leave furrows from 1/8′ to 1′ deep in the sand surface. Some rake attachments have one set of rake blades with 1/2-1′ deep teeth, used for smoothing deeper irregularities in the sand surface, trailed by a second set of rake blades with 1/8-1/4′ deep teeth to leave a less furrowed sand surface. Some rake attachments utilize leaf rake heads (either right side up or upside down) or bristle broom heads to produce a smoother finished sand surface with no distinguishable furrowing pattern. If a high degree of difficulty is the desired standard, a rake attachment that produces a deep furrow pattern should be used. The deep furrows will allow the ball to be more ‘buried’ in the sand on a regular basis. The deep furrows also tend to hold shots more up on the slopes of bunker faces, presenting golfers with more challenging uphill, side hill, and downhill lies. If a lower degree of difficulty is the desired standard, a rake attachment that produces no distinguishable furrow pattern should be selected. Fewer buried lies will result because the smooth sand surface tends to cause the incoming golf ball to bounce from the spot where it initially strikes the sand and come to rest on a smooth sand surface. Also, fewer uphill, side hill, and downhill lies will occur because the smooth surface on the bunker slope will tend to repel or allow a ball to roll down onto a level lie on the bunker floor. The type of sand and moisture content of the sand will also have an effect on the performance of a rake attachment. When sand is extremely wet, dry, hard packed, or soft, the desired furrow pattern and sand surface finish may be difficult to produce. No rake attachment will produce the same pattern every time that bunkers are raked. Once a desired degree of difficulty and a standard for bunker playing conditions has been established, golf course superintendents should conduct one to two month long trial studies using different mechanical bunker rake attachments. This testing best determines what type of rake attachment most consistently produces the desired sand surface finish for their golf course’s bunkers.
    2. The type of cultivation system used in conjunction with the rake attachment also has a strong effect on bunker playing conditions. Most mechanical bunker rakes have some type of cultivation attachment included as a part of the rake attachment. These cultivators allow the sand to be loosened to a depth of ½ to 3′ deep. This cultivation process allows the rake attachment to do a better job of smoothing the sand surface, helps to prevent and eliminate sand crusting problems, and helps control weed invasion. There are three basic types of cultivation attachments available: 1) flat, solid slicing or cutting bars ½ – 1′ wide, approximately 1/8′ thick, which match the width of each rake blade. These bars slice through the sand just in front of the rake blades and can usually be adjusted to cultivate the sand at different depths; 2) a solid cultivator bar with small ‘flat bottom plow’ blades attached to the bar. This attachment is usually positioned on the underbelly of a mechanical bunker rake and can be adjusted up and down to cultivate the sand to a desired depth, or raised to a position so that no cultivation takes place. This attachment can be controlled and operated separately from the rake attachment; and 3) a bar with a set of vertical spikes which are pulled through the sand at depths of ½ – 2′. This spike bar usually matches the width of each rake blade and is mounted just in front of the rake blade. The cutter bar and flat bottom plow cultivators provide better loosening of tightly packed sands, better breakup of crusted sands, and better control of weed invasion. The vertical spike cultivator is not as effective in bunker sands that are tightly packed, crusted, or prone to weed invasion. Conversely, when bunker sand is composed of predominantly spherical sand particles and is difficult to pack tightly, regular use of cutter bar and flat bottom plow cultivators may make it impossible to create the desired sand surface firmness. The vertical spike cultivator works much better in these looser types of bunker sands. Factors which must be considered when selecting the best combination of rake and cultivation attachments for mechanical bunker rakes are sand type, depth of sand, sand crusting potential, desired degree of difficulty, whether bunker liners are used in the bunkers, and potential for weed invasion. When using mechanical bunker rakes, the selection of a proper combination of rake and cultivation attachments is critical to producing the desired bunker playing conditions.
      3) Providing a perfectly smooth sand surface with no rake or furrow pattern. When the sand surface is perfectly smooth the sand grains tend to remain more tightly packed and cause a golf ball to bounce from its initial impact point where it strikes the sand surface. In addition, a smooth sand surface allows balls that land on or roll up bunker slopes to easily roll down to the flatter areas of the bunker. A smooth sand surface can also be achieved by dragging soft bristle brush or carpet mats behind a mechanical rake attachment. Most mechanical rake manufacturers offer a brush attachment that easily connects to their rake attachment. When hand raking bunkers, the raking process can be followed by dragging a 3/4′ or 1′ flexible water hose filled with sand over the bunker sand surface while walking around the bunker perimeter, dragging the sand surface with carpet or drag mats attached to long handles, or dragging a steel chain of the right size and weight over the sand surface. These methods work best when the sand is slightly dry. Trying different methods is the best way to determine what will work best on a particular bunker sand surface. Though these methods tend to produce a sand surface that makes bunker shots very easy for highly skilled golfers, some golfers may object to the ‘tight lie’ look that a very smooth bunker surface provides.
      1) Bunker edges that are sharply defined and have soil visible as a part of the bunker edge create a very formal, highly maintained appearance for the golf course’s bunkers. Though some golf purists would argue that bunker edges were never intended to be maintained in this ‘un-natural’ fashion, many golfers prefer the tidy, neat appearance this style of bunker edging presents. The degree of difficulty associated with this style of edging varies according to the height of the soil lip above the bunker surface. If the sand is pulled almost to the top of the soil lip the degree of difficulty is very low and some golfers may even elect to putt out of greenside bunkers. If the soil lip is several inches above the sand surface the degree of difficulty becomes much higher. Because this style of edging provides strong visual contrast with the surrounding turf areas, golfers tend to have better depth and dimensional perception of the target area on the green or in the fairway. The disadvantages of this type of bunker edge are the frequency of edging required to maintain a sharp edge, potential soil contamination as the exposed soil washes into the bunker, and the high potential for collapse of the edge caused by golfers or maintenance equipment. This bunker edging style works well when the golf course architect intends for the bunkers to be highly visible and prominently displayed as a part of the golf course landscape.2) Bunker edges that are well defined with grass growing vertically on the bunker lip provide a less formal, softer aesthetic appearance to bunkers. Cool-season grasses used on bunker lips can generally be grown longer and require less frequent edging while warm season grasses must be maintained at shorter lengths and edged more frequently. The degree of difficulty varies according to the height of the bunker lip and the length the grass is allowed to grow laterally and overhang the bunker sand surface. This type of bunker edge provides a relatively formal appearance without the disadvantages associated with sharp bunker edges with soil showing on the bunker lip. The grass on the lip helps stabilize the soil on the bunker edge. This greatly reduces the potential for soil from the bunker edge contaminating the bunker sand, and the potential for golfers or maintenance equipment collapsing the bunker edge. The disadvantages of this type of bunker edge are the moderate frequency of edging required, the bunker technician skills and judgment necessary to correctly maintain the grass bunker lip, and the tendency for golf balls to get caught up under the overhanging grass growing from the bunker lip. If a severe degree of difficulty for playing bunker shots is preferred, this type of bunker edging can be done in a fashion that provides a very intimidating appearing bunker lip that will challenge golfers of any skill level. This style of bunker edge works well in situations where a more natural, but somewhat formal appearance is the established standard for bunker maintenance.

      3) Bunker edges where grass is allowed to encroach 2 – 6′ onto the sand surface before any edging is done provide a more natural appearance for a golf course’s bunkers. Because growing conditions vary around the perimeter of most bunkers, an irregular edge without formal shape or straight lines evolves when this bunker edge style is selected. Some golfers find this type of natural appearing bunker edge very attractive, while others may feel it is unacceptable due to the unkempt appearance bunkers with this type of edge exhibit. The degree of difficulty associated with this style of bunker edge can be very high. Due to the unpredictability of the firmness of the lie, it can be very difficult to play a bunker shot from a bunker area that is a combination of grass and sand. Also, the low frequency of bunker edging associated with this style of bunker edge may cause the original bunker perimeters to disappear over time, and the shape and size of the bunkers may significantly change from the golf course architect’s original design parameters. This style of bunker edge fits well on golf courses where low maintenance of the rough areas is the established standard and native vegetation and grasses dominate the golf course landscape, and the golf course architect intends for the bunkers to be in harmony with the native landscape.

  9. Is there a proper depth of sand for bunkers?

    There are no strict established rules for the depth of sand which should be maintained in bunkers nor are there regulations which require the sand to be of uniform depth throughout the entire bunker. Sand depths from 2 to 8′ deep have been most commonly used in golf course bunkers for the past several years, with a 4 to 6′ sand depth being the recommendation accepted by most golf course superintendents, architects, and consulting agronomists. Some older bunkers where fresh sand has been repeatedly added for several years may have sand depths of 10 to 24′. Many PGA Tour Professionals have advocated that sand depths be no more than 1 ½’ on bunker faces and 2′ on bunker floors so that the tendency for golf balls to bury in the sand will be very low. Although there is no perfect sand depth for bunkers, we can note some general observations concerning the advantages and disadvantages of specific sand depth ranges used in bunkers:

    SAND

    DepthAdvantagesDisadvantages
    1- 3′

    Sand can usually be packed tightly;

    Provides firm stance;

    extremely low potential for buried lies;

    tends to repel balls off bunker slopes and onto more level lies on bunker floor;

    reduced costs for bunker sand.

    Depth very difficult and expensive to consistently maintain; sand prone to severe washouts on slopes; ‘ no sand in bunker’ comments when club face hits bunker floor below sand; provides extremely low degree of difficulty for highly skilled golfers; use of mechanical bunker rakes not advisable; use of liners not advisable; sand is easily contaminated by underlying soil and stones.
    3 – 4′Very good packing and firmness with angular sand particles; moderate potential for buried lies; moderate tendency to repel balls off bunker slopes and onto more reliable lies on bunker floor; use of mechanical rakes ok; use of liners ok in most cases; golf club rarely strikes soil beneath sand; moderate resistance to washouts on bunker slopes; moderate degree of difficulty possible with proper raking and grooming methods.Poor packing and firmness with rounded sand particles; buried potential high with rounded sand particles; severe washouts still possible on severe slopes; ball occasionally comes to rest under or against bunker lip; moderate risk of sand being contaminated by underlying soil and stones; degree of difficulty may be too high with rounded sand particles.
    4 – 6′Good packing and firmness is possible with angular sand particles; use of mechanical rakes ok; use of liners ok; golf club rarely strikes soil beneath sand; good resistance to washouts on bunker slopes; good resistance to contamination by underlying soil and stones; moderate degree of difficulty possible with proper raking and grooming methods.Very poor packing and firmness with rounded sand particles; buried lie potential very high; ball often comes to rest under or against bunker lip; very high degree of difficulty; sand may be prone to shifting under foot during golf swing; smooth sand surface may be difficult to achieve.
    > 6′Use of mechanical rake ok; use of liners ok; golf club never strikes soil beneath sand; good resistance to washouts on bunker slopes; excellent resistance to contamination by underlying soil and stones.Very difficult to pack sand tightly; good stance very difficult; playing surface usually too soft; buried lie potential extremely high; smooth sand surface difficult to achieve; degree of difficulty may be extremely challenging.

    What is the ideal sand depth in bunkers? The primary factors that must be considered to correctly answer this question are 1) sand type (size and relative angularity or sphericity of the sand particles), 2) desired degree of difficulty, 3) whether bunkers will be hand raked or machine raked, 4) whether bunker liners will be used in the bunkers, and 5) design characteristics and slopes of the bunkers. The complexity involved in answering this seemingly simple question regarding bunker sand depth is a clear indication of the importance that depth of sand plays when choosing raking and grooming methods to provide the desired playing characteristics for a golf course’s bunkers.

    Please explain the various raking and grooming methods.

    ‘The Golf Course’, by Geoffrey Cornish and Ronald Whitten, provides this description of how bunkers were raked at Oakmont Country Club for a number of years: ‘ Since the heavy clay base upon which the course was built prevented the digging of all but a few deep bunkers, Fownes (Oakmont’s builder) and Loeffler (long-time Oakmont greenkeeper) concocted a device to add to the difficulty of the otherwise flat, shallow bunkers. It was a special rake that, when dragged through the thick, brown river sand in Oakmont’s bunkers, left deep grooves or furrows. Many felt it took two special talents to extract a ball from an Oakmont bunker-one if the ball sat on a ridge in the sand, another if it settled in a trough. Others believed that since a ball seldom stayed on the ridges in the sand, Oakmont’s bunkers were easier to recover from than those raked in the conventional manner. Indeed, several neighboring courses adopted Oakmont’s furrowed rake. In the 1960s, the river sand was replaced, the furrows eliminated and almost a quarter of the bunkers filled in.’

    Following the example of Emil ‘Dutch’ Loeffler, golf course superintendents have usually been the innovators in the development of tools and methods used to maintain bunkers. As a result, modern day golf course superintendents can choose from several methods and tools to produce bunker sand playing surfaces with the desired bunker playing conditions. Bunker maintenance methods can be roughly divided into four categories: 1) raking and cultivation methods; 2) packing and surface smoothing methods; 3) control of sand moisture content; and 4) addition of amendments. As a rule, the intensity and cost of a bunker maintenance program increases progressively as methods from categories 2 – 4 are made a part of a golf course’s bunker maintenance program, and the degree of difficulty for playing bunker shots decreases as methods from each of these categories are implemented.

    Please explain the different raking and cultivation methods.

    Bunker sand can be raked and cultivated by mechanical bunker raking, hand raking, or a combination of both. Each method has advantages and disadvantages that need to be considered when developing a golf course’s bunker maintenance program.

    Mechanical bunker rakes first began to appear on golf courses in the 1960s. In ‘Keepers of the Green’ Bob Labbance and Gordon Witteveen give this account of the advent and acceptance of mechanical bunker rakes: ‘….one was the power sand rake, first marketed in 1971. Although several innovative superintendents had attached rakes to tractors in the past, the first real power sand bunker rake was invented by Stanley Clarke of LaGorce CC in Miami, Florida. USGA Agronomist William Buchanan observed his first exposure to the machine in a September 1971 article for the USGA Green Section Record: ‘Bunkers on many courses are costly to maintain, and until recently all the work was done by hand. Recently, power rakes have been developed that offer a tremendous saving in man-hours. While visiting one course this summer, we observed a power rake in use. The operation was timed in five minutes; according to the superintendent, it took one man 30 minutes to do the job manually. Therefore he saves 25 minutes in labor on that one bunker every time it is raked.’ There is no doubt that the usage of mechanical bunker rakes has made it possible for golf courses to intensely maintain large expanses of bunker sand surface for a reasonable cost.

    What factors need to be considered when selecting mechanical bunker raking?

    There are three primary factors that must be considered when selecting a mechanical bunker rake as the preferred method for raking bunkers: 1) the type of rake attachment necessary to produce the desired bunker playing conditions; 2) the type of cultivation system used in conjunction with the rake attachment; and 3) limitations of the mechanical bunker rake and resulting negative effects when mechanical bunker rakes are used improperly.

    Please expand on the limitations of mechanical bunker raking of which clubs should be aware.

    Golf course superintendents must recognize, acknowledge and address the limitations of mechanical bunker rakes and the resulting negative effects when mechanical bunker rakes are used improperly. In an article titled ‘A Revival of Hand Raking?’ in the May/June 1988 issue of the ‘USGA Green Section Record’, James Snow, USGA Green Section National Director, provides a thorough explanation of the potential problems which can result from mechanical bunker raking: ‘Many of the negatives concerning the mechanical rake are inherent in its use, while others can best be attributed to its misuse. The rake does an excellent job of grooming hard sand to keep it in good playing condition, but on the other hand, it can actually keep new sand too soft, and encourage fried-egg lies. Complaints from golfers are especially common after a course has just replaced its old contaminated sand with new material. One course of action in this instance is to keep the mechanical rake out of the bunkers as much as possible, or at least remove its scarifying teeth to prevent deep cultivation. This helps to improve playability while the sand has an opportunity to settle in the months ahead.

    The mechanical rake has other drawbacks in new or soft sand. It creates ridges of sand as it makes its turns. A golfer unfortunate enough to find his ball on the wrong side of one of these ridges may have a tricky shot, to say the least. The problem is most severe when the operator is going too fast, but even a good operator will have difficulty avoiding ridges when the sand is quite soft. The only way to deal with this problem is to slow down the operator and have him touch up the ridges with a hand rake.

    By the nature of the turning action of mechanical rakes in sand bunkers, sand is constantly being moved around. As the machine makes its turns, a lateral, downward force is exerted, which pushes the sand outward-a process that occurs more quickly with operators who go too fast.

    Over a period of weeks and months, a bunker that may have started out with a uniform 6′ layer of sand may be found to have pockets with only a 2′ layer, and other areas with from 8 – 10’. When the machine passes through the shallow areas, the scarifying teeth or blades often dig into the sub-base and contaminate the sand with soil and stones. In bunkers where plastic or geotextile liners are used, the teeth sometimes catch and rip the liner, often leading to its removal. Though it is a time-consuming solution, some clubs combat this problem by routinely monitoring the depth of sand in various locations within their bunkers, and sending out crews to reestablish a uniform sand depth. Nevertheless, inconsistent playing conditions and an increased rate of sand contamination is almost assured.

    Human nature being what it is, most would agree that if a person had a choice of riding a machine or doing the work by hand, he would choose to ride. Therein lies the biggest problem with the mechanical sand rake; many operators spend too much time on it, and try to do too much with it. For example, trying to rake the sand on a steep slope or face with the machine leads to nothing but problems. Sand is pulled down the slope, leaving a very thin layer on the face, and the machine ultimately digs into the sub-base and hastens the contamination of the bunker with soil and stones.

    Also, operators often rake too close to the edge of the bunker trying to avoid having to touch up the perimeter by hand. In the process, contamination occurs as the machine catches the lip, and excess sand is pushed closer and closer to the edge, until the lip is lost in a wash of sand. At this point, when good bunker definition is lost, the appearance and playing qualities of the bunker are greatly diminished. Many clubs try to compensate for the deterioration of the lips by edging the bunkers more often, but this only results in the loss of their original size and shape.

    One of the most blatant attacks on the integrity of sand bunkers is in the areas where the mechanical rake enters and exits. Due to habit or sometimes to design considerations, many operators always enter and leave a bunker at the same location, causing a gradual deterioration and loss of definition of the lip in that area. Worse still, due to haste and a loathing for getting off the machine, operators tend to drag some sand out over the edge of the lip as they leave. Over a period of weeks and months, many bunkers grow appendages that ultimately become integral parts of the hazard. It is not surprising, then, that mechanical sand rakes are the bane of golf course architects, who take pride in the bunkers they create.

    Thus, it is apparent how the long-term costs of relying completely on the mechanical sand rake can add up. Soil and stone contamination can occur significantly faster with a mechanical rake than with hand rakes. All things being equal, the sand will have to be replaced more frequently. An alternative is to place several inches more sand in the bunkers to reduce the chances that the mechanical rake’s scarifying teeth will dig into the soil. Regular sand depth monitoring and sand redistribution work is another possibility. The use of geotextile liner to minimize contamination is a calculated risk, and more often than not is unsuccessful. All of these accommodations of the mechanical rake are costly. Bunker lip deterioration occurs much more quickly with the use of the mechanical rake, requiring more frequent edging to maintain good definition. The design of the bunker is then compromised, calling for the redesign and rebuilding of the bunker lips. Much of the extensive bunker renovation work going on at hundreds of golf courses now and in recent years is in good part due to the effects of the mechanical rake.

    So what’s the solution?

    Some would argue that the mechanical rake should be abandoned and that hand raking should be re-instituted. Certain courses, such as those with small bunkers and limited numbers of bunkers, would be wise to consider such a move. Courses with many large bunkers, however, would be hard pressed to give up the time saving, weed control, and grooming benefits of the mechanical rake.

    Perhaps the best way to enjoy the advantages of the mechanical rake while minimizing its long-term negative impact is to develop a strong program of training the operators to use the machine properly. Unless the design of the bunker limits its accessibility, operators should be directed to alter their entrance and exit points regularly to avoid excessive wear on the lips in any single location. The speed of the machine should be kept at a reasonably slow pace while raking the sand and should be allowed to move no closer than 12 to 18′ from the bunker lip. The rake should be limited to the flat or mildly sloping ground within the bunker, avoiding the faces at all costs. To prevent sand from being dragged over the lip when leaving the bunker, the scarifying bar should be raised well ahead of time, preferably 12 to 18′ before reaching the lip. Finally, the inside perimeter of the bunker and any un-raked faces should be touched up with a hand rake, and weeds in this perimeter area should be pulled by hand and or periodically treated with a non-selective herbicide.’

    By carefully selecting mechanical bunker rake attachments and properly training golf course equipment operators to use mechanical bunker rakes, a bunker maintenance program that consistently provides the desired bunker playing conditions can, in most cases, be implemented.

    When is hand raking clearly required?

    There are several situations which may require that bunker surfaces be maintained by hand raking rather than machine raking: 1) bunkers too small for turning and maneuvering mechanical rakes; 2) bunkers with large surface area severe slopes; 3) pot bunkers with vertical walls, or bunkers with very high lips allowing no access for mechanical rakes into the bunker; 4) soft or loose sand conditions which require minimum cultivation and surface disturbance to produce the desired firmness of the sand playing surface; 5) golfer’s mandating that the sand furrow pattern be parallel or perpendicular to the direction of play, rather than the circular pattern produced by a mechanical rake; 6) bunkers with severely irregular shaped perimeters, numerous capes, narrow bays or other severe design features; and 7) golfer’s perception that hand raking produces better bunker playing surfaces.

    Though cost and convenience are limiting factors that must be considered, the age old practice of hand raking bunkers may be the best method for providing the desired playing conditions in these situations. Golf course superintendents must carefully analyze all the factors that affect bunker playing conditions and golfer’s perceptions before choosing the ‘right method’ of bunker raking. Every set of golf course bunkers is different. The method that works well for one bunker or set of bunkers may be the wrong method for a different bunker or set of bunkers.

    What are the different types of rakes?

    A variety of rake types are commonly used for hand raking bunkers: 1) 12 – 36′ wide leaf rakes; 2) 12 – 36′ wide metal bunker rakes with teeth from ½ – 2′ long; 3) hard plastic bunker rakes with rounded heads and ½ – ¾’ long teeth; 4) 12 – 24′ wide garden rakes with narrower, more widely spaced 2 – 4′ long teeth; and 5) hard plastic bunker rakes with straight heads and ½ – 2′ long teeth. Some hand rakes have extra long (4 – 8′) handles so that steep bunker slopes may be easily reached and raked without creating deep depressions caused by footsteps. Rakes with short, closely spaced teeth and leaf rakes work well for dry, loose sand, or for situations where golfers desire a smooth sand surface with very shallow furrows. Rakes with longer, more widely spaced teeth work well for tightly packed sands, sands with a high crusting potential, bunkers susceptible to weed invasion or for situations where a deep furrowing pattern is the desired result. Factors that must be considered when selecting the correct rake for hand raking are sand type, depth of sand, sand crusting potential, desired degree of difficulty, potential for weed invasion and efficiency and ease of operation for laborers doing the bunker raking. The selection of the proper type of hand rake is critical to producing the desired bunker playing conditions.

    What is required for hand raking to be successful?

    Hand raking bunkers is a task that requires diligent, patient, and careful effort by the golf course maintenance employees responsible for raking bunkers.

    In the USGA ‘Turf Management For Golf Courses’, pg. 329, Dr. James Beard gives the proper technique for hand raking bunkers: ‘ Manual raking involves a forward-and-back movement of a rigid-toothed rake as the green staff member moves laterally to the left of right. Care should be exercised so ridges of sand are not left at the termination of either the forward or backward stroke. The bunker may be raked (a) from one side to the other, (b) from end-to-end, or (c) in a circular pattern. Manual raking should be done carefully, since rapid movements tend to leave vertical waves in the sand surface.

    Special care is needed in raking the perimeter of bunkers to ensure a well-defined edge.

    Sand must be pushed or pulled toward the edge of the bunker in proportion to the amount moved toward the center. The proper raking procedure for the bunker face involves working along the edge of the bunker, either pulling sand up the face if the individual is above, or pushing it up if the individual is in the bunker. Continual raking down the face causes a downward movement of sand that eventually results in a thin face and excess sand in the base of the bunker. Care should be taken to not pull excess sand up and over the turfed lip. In contrast, the raking procedure on the backside of a bunker should ensure that the sand surface is nearly level with the nearby turf-soil interface to avoid difficult ball lies.’

    Hand raking does allow for the furrow pattern to be aligned in a particular direction relative to the direction of play. Most golfers and tournament officials request that the sand furrows be aligned in the direction of the shot to be played.

    Apart from the time and expense,are there any otherdownsides to hand raking?

    One of the negative effects associated with hand raking is the lack of cultivation of the bunker sand. This lack of cultivation usually leads to increased weed invasion, sand surfaces that become too tightly packed and firm, and increased crusting on the sand surface. Weed invasion in the bunkers can be controlled by non-selective herbicide applications, manual removal of the weeds, or occasional use of mechanical sand rake cultivator attachments. The occasional use of mechanical sand rake cultivator attachments can also effectively alleviate problems associated with tightly packed or crusty sand surfaces. This occasional mechanical cultivation can be a perfect, low-cost method to complement a bunker maintenance program built upon hand raking of bunkers. With adequate employee training, motivation, and supervision, a bunker maintenance program that utilizes hand raking of bunkers can produce the desired bunker playing conditions on a very consistent basis.

    How do golf course superintendents utilize a combination of mechanical and hand bunker raking?

    Mechanical bunker rakes are used in the flatter portions of the bunkers and hand raking is done around bunker edges, on severe bunker slopes, and in the few golf course bunkers which may be too small to accommodate the mechanical bunker rake. Training golf course maintenance employees to know the proper combination of raking methods that should be used in each golf course bunker is critical to the success of this approach to bunker raking. Given the right conditions, the proper combination of these two raking methods can be fine tuned to provide the desired bunker playing conditions for a very reasonable cost.

    Please explain the different packing and surface smoothing methods.

    When a low degree of difficulty for bunker shots is the established bunker maintenance standard, additional cultural practices may need to be added to the bunker maintenance program in order to produce the desired bunker playing conditions. Relying only on proper raking and cultivation techniques may not adequately prevent problems with buried lies, balls resting on severe bunker slopes, or soft lies that are undesirable to most golfers. These problems are especially common when bunker sand has been completely replaced or new sand has been added to ‘freshen up’ the sand surface of the bunkers, and the sand has not had time to settle and pack completely. Bunkers with severe slopes that are prone to frequent washing or slipping of the sand from the slopes present an ongoing challenge since sand must be regularly pushed back up the slopes to maintain a consistent sand depth. The sand that is continually returned to bunker slopes often demonstrates characteristics similar to newly added sand and must be repacked to provide the desired playing conditions. Temporarily suspending or eliminating cultivation practices, and/or reducing sand depth are usually the first two steps that are tried in an attempt to pack bunker sands more tightly and provide firmer playing conditions. When these efforts fail to produce the desired playing conditions, other bunker maintenance methods that may sufficiently firm the sand surface are:

    1) Packing the sand by driving a small vehicle with wide tires back and forth several times over the bunker surface. Since most mechanical bunker rakes have a very low center of gravity, wide tires, and are designed to operate well on sandy surfaces, they are ideal tools for packing sand in bunkers. When the raking and cultivation attachments are either removed or raised to a non-operating position, the mechanical rake is maneuverable enough to pack sand on the bunker floor and on bunker slopes. On severe slopes the mechanical rake should be driven straight up and down the slope and not across the slope. This ensures safe operation of the mechanical rake and also tends to reduce the tendency for the sand to slip down the slope during the packing operation.

    2) Packing the sand with a vibratory tamp (a flat steel plate with an engine mounted on top of the plate that produces a compacting effect by vibrating horizontally, with a handle attached to the plate for ease of maneuverability). Although more labor intensive and slower to operate, the vibratory tamp does an excellent job of packing most sands tightly. On bunker slopes two workers are usually required to keep the tamp going on a straight line across the slope.

    Both of these packing methods work better when the sand has adequate moisture content, and watering the sand just prior to the packing procedure is usually advisable.

    How does a golf course superintendent control the sand moisture content?

    Many bunker sands may be adequately firm when damp after nighttime irrigation, but may become very soft and prone to shifting as they dry out rapidly through the daytime. Bunker playing conditions that were perfect at the start of the days play may become objectionable as the day progresses. Some bunker sands with very low silt or fine particle concentrations have very low field water retention capacities and may dry much too quickly to provide consistent bunker playing conditions. Tightly packing these types of sands by using the previously described methods may not yield the desired results. There are two commonly used methods that help in this situation:

    1) Apply a wetting agent at 6 to 8 oz. per 1,000 sq. ft. every 10 to 14 days. The simplest method for applying these materials uniformly to the bunker sand is to use a hose proportioner attached to a standard water hose and quick coupler system. Though this process is very labor intensive it usually provides much more consistent moisture content in the bunker sand profile. As a result, bunker sand can be packed more tightly and remain firmer for longer periods of time. This practice works especially well as a short-term solution for bunker sands that have not had time to completely settle, and for providing the short term playing conditions for bunkers required for an important golf tournament or event.

    2) Installing sprinklers around the bunker perimeter that irrigate only the bunker sand surface and not the surrounding turf areas. When dry, firm turf conditions are desired, this may be the only solution for maintaining adequate moisture content in the bunker sand. Though this method may seem excessive in trying to solve a hazard maintenance problem, it does allow the golf course superintendent to effectively control moisture content in bunker sand and provides a very long-term solution to the problem. In many cases only a few of the bunkers on a golf course may need this type of installation to provide the desired bunker playing conditions.

    What about the addition of amendments?

    When a combination of raking, cultivation, packing, surface smoothing and moisture content control methods fail to produce the desired playing conditions for a bunker sand, one other method is worth considering before recommending complete removal and replacement of the bunker sand. Loose, packing resistant bunker sands can often be made firmer by incorporating finer particle size sand (or a crushed granite dust normally used for clay tennis courts) into the top part of the sand layer of the bunker. These materials are spread uniformly onto the sand surface and lightly cultivated into the top part of the sand layer by using a disc spiker or by raking with hand rakes. The bunker sand is then packed tightly using one of the previously discussed methods. If the right amendment and installation technique is used the desired firmer bunker playing conditions can usually be attained. This method works surprisingly well in many cases. However, over a period of time the amending material becomes more dispersed into the sand profile due to rain events, routine bunker maintenance practices, and golfer foot traffic and bunker shots. The initial firming of the sand surface gradually dissipates and the amending material must be added again to maintain the desired playing conditions. In most situations these materials will need to be added three or four times a year to produce the desired results. Continued long-term usage of these materials can also have a negative impact on the drainage properties of the bunker sand profile. Infiltration rates should be routinely monitored to ensure that amendments are not significantly affecting the bunker sand’s drainage properties.

    What is the significance of bunker edging?

    The style in which bunker edges are maintained has a significant impact on the golfer’s degree of difficulty for playing bunker shots and their strategy for playing a golf hole. Also, the aesthetic appearance and architectural intent of bunkers is strongly influenced by the style in which bunker edges are maintained. Many golfers have very strong personal preferences regarding the aesthetic appearance that bunker edges present, and are more than willing to voice those opinions to the golf course superintendent. At some point in time, encroaching grass from turf surrounding the bunker must be edged, either by mechanical or chemical means, in order to maintain the architectural intent of bunker. Bunker edging styles can be roughly divided into four types: 1) bunker edges sharply defined with soil showing on the bunker edge; 2) bunker edges sharply defined with grass showing on the bunker edge; 3) bunker edges with grass encroaching 2 – 6′ into the bunker, providing a somewhat irregular edge; and 4) grass encroaching more than 6′ into the bunker providing a severely irregular edge. Golf course superintendents should carefully consider the effects bunker edging styles have before selecting an edging style which best fits the overall bunker maintenance program.

    4) Some bunkers that are adjacent to native vegetation areas may not be designed to have a defined edge, especially on the side of the bunker farthest away from the green or fairway. The bunker’s definition ‘washes out’ as it transitions into the native vegetation area. Native grasses with clump-like growth habits often extend into the bunker sand more that 6′ from the edge of the sand and provide an extremely natural appearance for the bunker. These types of bunker edges usually require only minimal maintenance. Due to possible interference to the golf club swing path that these native materials provide, and the increased possibility of a lost ball, a very high degree of difficulty may be associated with this type of bunker edge. Factors that golf course superintendents should consider when selecting the correct bunker edge style for the golf course’s bunkers are desired degree of difficulty, growth habit of the grasses surrounding the bunkers, golfer’s attitudes and perceptions regarding highly maintained versus natural aesthetic appearance, and architectural design style of the golf course. Once a standard for the style of bunker edges has been clearly established, maintenance procedures can be developed which produce the desired result.

    Bunker edging frequencies may vary from bi-weekly to yearly depending on the grass type and the desired style of bunker edge and lip. String trimmers, engine powered edgers, weedeaters with reciprocating blade attachments, sod knives, machetes and flat bladed shovels can be successfully used to trim bunker edges or the grass lip of a bunker edge. Experimenting with several different tools used for edging bunkers is the simplest way to determine which edging tool and method produces the desired results most efficiently. Training, motivating, and supervising golf course employees to properly edge bunkers is the most important key to consistently having bunker edges that conform to established bunker maintenance standards.

    What factors determine the cost of bunker maintenance?

    The cost for maintaining a golf course’s bunkers is dependent on several primary factors: 1) number of bunkers; 2) size of bunkers; 3) frequency of bunker raking; 4) length of golf season and other climatological influences; 5) whether bunkers are hand raked or machine raked; 6) style and frequency of bunker edging; 7) desired degree of difficulty; 8) average hourly labor cost; 9) desired uniformity and depth of bunker sand; 10) architectural design of bunkers; 11) type of sand; 12) weed invasion pressure; and 13) amount of debris, leaf, and stone removal required.

    Because there are such a large number of factors that influence the cost for bunker maintenance, the cost for maintaining bunkers varies widely from one golf course to another. Some golf facilities may commit as much as 15 – 25% of their golf course labor hours to bunker maintenance, while others may commit as little as 5 – 10% of their golf course labor hours to bunker maintenance. In preparation for golf Championships, it is not uncommon to have a bunker maintenance crew of 10 to 20 people working full time on bunkers for 2 to 3 weeks prior to and during the event. Bunker maintenance practices associated with Tournament preparation often include hand raking, packing, adjusting sand depths, removing debris and stones, controlling moisture content, adding amendments, and surface smoothing, cultural practices that are all very labor intensive.

    If golf course superintendents and their supervisors set a bunker maintenance standard of providing ‘Championship’ conditions every day, labor costs for bunker maintenance for an 18-hole golf course can easily be $300,000 to $350,000 per year. Though a few golf facilities may be willing to spend that much money for bunker maintenance, the vast majority of 18-hole golf facilities choose to spend a more reasonable amount for bunker maintenance labor, somewhere in the range of $50,000 to $125,000 per year.

    Conversely, some golf facilities establish a policy that only minimal bunker maintenance is necessary and that bunkers should be truly hazardous. Bunkers are raked maybe once weekly, only edged two or three times per year, and sand depths are rarely adjusted. Bunker maintenance labor costs can be as little as $5,000 to $15,000 per year in these situations. Some golf course officials choose to label bunkers that are infrequently maintained as ‘waste bunkers’ or ‘waste areas’, and instruct players that they may ground their golf club when addressing their golf ball before playing a shot, a practice not permitted by the USGA ‘The Rules of Golf’ when playing a bunker shot. Though this practice does allow for significantly reduced bunker maintenance costs, there is no definition in ‘The Rules of Golf’ for ‘waste bunker’ or ‘waste area’, and golf course superintendents and golf course officials should be cautious regarding how these hazardous areas are identified/designated as being bunkers or not being bunkers.

    Since there can be such a wide variance in cost for differing bunker maintenance programs, golf course superintendents need to carefully examine, analyze, and project the costs associated with each bunker maintenance procedure before adding that procedure to their bunker maintenance plans. By consistently maintaining and analyzing records of the labor hours required for bunker maintenance tasks, golf course superintendents can easily calculate and report the costs associated with different bunker maintenance procedures. Governing parties responsible for approving golf course budgets and expenditures can then be accurately informed regarding the expense required to maintain bunkers that provide playing conditions that meet a golf course’s established standards. Many golfers are very surprised to learn that as much as 10 – 25% of the golf course maintenance staff’s time is spent on maintaining bunkers, and golfer’s expectations regarding bunker playing conditions are often modified when they are made aware of the financial commitment required to provide a perfect lie for every bunker shot. Golf course superintendents need to consistently inform and educate their golfers about the hazardous challenge that bunkers are intended to present to them as they play golf, and about the considerable expense required to reduce or remove the hazardous nature of a bunker. When this educational effort is conducted in a professional, non-confrontational manner, golf course superintendents will often find that basic bunker maintenance becomes a much less stressful Hazardous Duty.

    Howhas all this time and thought and effort regarding bunker maintenance effected the original historical intent of a bunker as a hazard?

    Many golf course superintendents would agree that these bunker maintenance programs that produce playing conditions that provide a very low degree of difficulty are completely at odds with the definition of a golf course bunker as a hazard. Whether we agree or not, for the past several years the perception and expectations that golfers have developed regarding bunkers has steadily shifted toward an attitude that bunkers should be much less hazardous, and that golf is a game that should always provide fair treatment for every golfer, with ‘bad luck’ never being a part of the game. As long as this thought trend continues and golfers are willing to provide the necessary financial resources, golf course superintendents will continue to strive to develop bunker maintenance programs that provide golfers with the bunker playing conditions they desire on a daily basis. Hopefully, in the future the bunker maintenance pendulum will swing back the other direction and golf course bunkers will become more hazardous again. Until it does, golf course bunker maintenance will remain hazardous duty for the golf course superintendent.

The End