Extending the Life of Bunker Sandsby JAMES T. SNOWDirector, Northeastern Region, USGA Green Section

DID YOU know that sand beginsto age the moment it's placedin a bunker? If you've never

thought about the aging process of sandand its implications for the playabilityof your bunkers, then read on.

The life cycle of a bunker sandtypically begins when it is installed inthe bunker. At that time it is usually assoft and fluffy as it ever will be, and itsappearance will never be better. Withrepeated rainfall or irrigation, the sandgradually becomes more firm. Theprimary aging factor affecting bunkersands is the contamination that happensover an extended period of time, involv-ing the mixing of silt, clay, and organicmatter with the sand. As this occurs to

a greater and greater degree, the sandgoes from soft to firm to hard, and itsappearance deteriorates as well. Even-tually, when the golfers at the coursebecome upset enough, the contami-nated sand is removed and replacedwith new material, and the cycle startsagam.

The replacement of sand in thebunkers at a course is time consumingand expensive, and it is obviously nota process that anybody likes to see donemore often than absolutely necessary.By understanding the causes of sandcontamination, it is possible to imple-ment preventive measures that canprolong the life of new sand for manyyears.

Sand Selection

Extending the useful life of newbunker sand begins with proper sandselection. Depending on such factors asparticle size range, particle shape,purity (the presence or absence of con-taminants), chemical composition, andother factors, some sands are likely toprovide years more service than others.For example, a pure quartz sand witha very narrow particle size range and arounded particle shape would takemany more years to become hard andunplayable compared to a contami-nated calcareous sand with a very wideparticle size range and an angularparticle shape. On the other hand, this

Contaminated sand develops much more quickly in poorly drained bunkers.

Severe washouts (above) can be reduced or eliminated with the construction of interceptor drains (facing page) or surface swales.

quartz sand would probably be too softand would produce fried-egg lies for along time.

How can you determine the suit-ability of a sand for bunker use? Firstof all, contact the USGA Green Sectionfor guidelines concerning bunker sandselection. The guidelines include somegeneral recommendations pertaining toparticle size range, particle shape, andchemical composition. A word ofwarning, though: Some sands that fallcompletely within USGA guidelinesmay not be suitable or acceptable tosome golfers, while other sands that fallwell outside the guidelines may be con-sidered very acceptable by the golfers atthat club.

Much of this incongruity has to dowith factors such as personal prefer-ence, sand availability, cost, installationprocedures and sand depth, environ-mental factors (e.g., high winds), etc.Thus, don't let USGA guidelines be yoursole judge. Instead, use them as a means

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of eliminating the obviously unsuitablesands from your list.

After narrowing the list to one orseveral sands, it is advisable to havethem tested at a good soils laboratory,pne that is knowledgeable and ex-perienced in analyzing bunker sands.The lab, like the USGA guidelines, can'taccount for the personal tastes of thegolfers at a particular course, but it canpredict the general behavior of thesands being considered and provides abasis for making a final decision. Whensending a sand to a laboratory, alwayskeep an equal amount of material atyour office. This allows you to comparethe sand you have tested to the one thatis actually delivered.

Before spending tens of thousands ofdollars in a sand replacement program,testing sands in trial bunkers on thecourse is a common and often worth-while practice. However, be aware thatmost good sands will seem quite softand fluffy until they have had the

opportunity to settle for several weeksor months. Indeed, if a bunker sandseems "perfect" immediately after it hasbeen installed, it will probably be toofirm or hard in too short a period oftime.

Generally speaking, the best bunkersands are quartz based, angular in shapeto provide reasonable firmness, con-fined to a relatively narrow particle sizerange (a large majority between .25mmand 1.00mm), and contain no contami-nants in the form of silt, clay, andorganic debris.

Preventing Contamination

After a good-quality sand has beenselected for bunker use, the best way toextend its useful life is to prevent itscontamination with silt, clay, andorganic matter. These fine particles,which largely come from the soil on thebottom of the bunker and from the

bunker edges, gradually fill many of thepore spaces between the sand particlesand cause the sand to drain poorly andto become hard and crusted. Fortu-nately, with some forethought and ad-vanced planning, there are a number ofgood ways to reduce the rate of soil/organic buildup in bunker sands.

The earliest opportunities for con-tamination occur before the sand everreaches the bunkers. When takingdelivery of new bunker sand, inspect itto be sure that there are no telltale signsof previous loads of soil or other debris(and check to be sure it is precisely what

you ordered). Also, delivered sandshould be placed on a concrete orasphalt base so that soil contaminationdoes not occur when the sand is beingmoved from the stockpile to thebunkers.

One of the best means of preventingcontamination is to avoid bunkerwashouts caused by heavy rainfall orirrigation. When washouts occur, sandis washed down the face of the bunkerand some of the soil is eroded off theslope as well. When the washout isrepaired, the eroded soil is intermixedwith the sand and the contamination

process is begun, and with each washoutthe situation worsens. To minimize theeffects of washouts, be sure that surfacewater does not enter the top edge of asloped bunker from an adjacent slopedturf area. This can be assured by con-structing interceptor drains or surfaceswales above the bunker to carry sur-face water around its sides.

Another good way to minimize theimpact of washouts is to construct adeep vertical lip along the top edge ofthe bunker, leading to a flat, perpen-dicular plateau at the base of the lip.The cut is then packed with sand, theresult being a significant reduction inthe amount of soil eroded from the facewhen washouts occur. (For more de-tails, see "How to Rebuild ErodingBunker Faces," USGA GREEN SECTIONRECORD,May/June 1983.)

Finally, it is no secret that washoutsare much more prevalent and severe onbunkers with steeply sloped sand faces.Current architectural styles, whichemphasize grassed slopes and minimalsand flashing, greatly minimize wash-out concerns and would be worth con-sidering if bunker reconstruction isbeing contemplated.

Providing good subsurface drainageis another key to preventing sand con-tamination. When water puddles in apoorly drained bunker after a heavyrainfall, fine soil and organic particlesfloat to the surface of the puddle andthen settle on the sand surface as thewater recedes. When the sand is raked,the fine particles are mixed with thesand and contribute to the contami-nation problem. Installing subsurfacetile drainage, or clearing existing drain-age, prevents puddling in all but theworst of circumstances and thereby pre-vents contamination.

Sand is often contaminated with soilwhen riding mechanical sand rakes arecarelessly used. When the machine isrun too close to the edge of the bunker,the scarifying teeth dig into the soilbelow the sand, or the bar digs into thelip or edge of the bunker, causing amixing of sand and soil. Also, sandtends to become shifted around by themechanical rake over a period of time,leaving only a very thin layer in someparts of the bunker. When the scarifyingteeth hit these areas, soil is again mixedwith the sand. This suggests a need tokeep enough sand in the bottom of thebunker, at least four to six inches indepth, and to periodically monitor sanddepth when mechanical rakes are used.Also, keep the mechanical rake awayfrom the edges of the bunkers and off

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the slopes and faces. Hand rakingshould be done in these areas if at allpossible.

Another opportunity for sand con-tamination occurs when the bunkers areedged. Too often the edges are cut backtoo severely, allowing a significantamount of soil and other debris to fallinto the bunkers. A more modest edgingor a trimming of the long grass on thebunker edge would reduce this con-tamination and would better preservethe original contour and size of thebunkers.

Finally, care should be taken whenmowing around the perimeter of abunker to avoid blowing large volumesof clippings into the sand. If this occurs

with too much regularity, the organicmatter from the clippings can con-tribute to the aging process of the sand.

A word about geotextile liners is inorder. Yes, liners do an excellent job ofpreventing contamination from the soilbelow the sand layer. Many courseshave installed liners, but in the end alarge majority have taken them out. Itis very difficult to keep a uniform depthof sand on the liners, especially onsloped faces, and courses that use ridingmechanical rakes almost invariablysnag the liners with their rakes. Courseswith flat-bottomed bunkers and thosewho hand rake their sand have the bestopportunity for success with liners. Ifliners are used, they should be placed

under, not over, the drain tile in thebunker, as the liners occasionallybecome plugged with soil and organicdebris and can inhibit drainage.

Dealing With Existing Hard Sand

When sand approaches the end of itsuseful life, the effects of soil and organiccontamination make it crusty, hard, andunattractive. Because of the time andexpense involved, most courses arehesitant to rush out and replace all theirsand. Instead, they try to cultivate theold sand more frequently and deeply,which works for only a day or two ata time. Some try rototilling the oldsand, hoping to loosen the material to

This sand-cleaning machine allows high-quality, expensive sand to be recycled many times.The Country Club of Buffalo, Williamsville, NY.

a greater depth. Because of the silt, clay,and organic content, though, the sandquickly compacts to its original hardstate.

Most courses respond by adding acouple of inches of fresh sand on top ofthe old material. This practice works fora few months, but the new and old sandeventually become mixed, and evenmore sand must be added. Indeed, it isnot uncommon to find three or four feetof sand in old bunkers when they arefinally renovated.

Ultimately, hard, contaminated oldsand must be dug out and replaced withnew sand. This can be an extremely timeconsuming project for the grounds crew,detracting from routine maintenance

operations and other projects. Manycourses with modest-sized crews arebest advised to contract out much ofthe sand replacement work. If done in-house, then small loaders, adequatelysized dump vehicles, and extra workersmust be provided for the crew.

When old sand is removed from abunker, it is usually discarded, used forfill on some construction project, orperhaps added to leaf and clipping com-post. A more suitable use for the oldsand has been found at the CountryClub of Buffalo, where superintendentNorm Leising has for many yearswashed the contaminants out of the oldsand and put it right back in thebunkers. Their sand-washing machine

is put to good use whenever there area few extra hours in the schedule.Interested parties should contact localquarries for the names of manufacturersof stone and sand grading equipment.Where expensive, high-quality sand isused for bunkers, washing equipment ofthis type might be a good investment.

As it turns out, then, there are manyways to extend the useful life of bunkersand while guarding a large investmentin time and materials. By taking thetime to test and select the best-qualitysand, and by carefully avoiding thesources of contamination noted above,the appearance and playability ofbunker sand can be protected and main-tained for many years.

To help prevent contamination of bunker sands, keep mechanical rakesoff slopes and at least two feet away from edges. This rake is too close.

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