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Natural and reinforced grassFootball pitches
---- Quality assessment----
Experiences learned and shared
by
Sportfloor TechnologieS
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INTRODUCTION
What exactly is a natural grass pitch? _____________________________________ 3
STADIA GRASS PITCH QUALITIES
Some questions and answers concerning natural grass football pitches___________ 3
Natural grass types and qualities_________________________________________ 4Footballistic and technical qualities differences______________________________ 9
Natural grass grown outside of a stadium
• harvested in turf farms _____________________________________________ 10
• grown in box systems______________________________________________ 13
Reinforced natural grass
• reinforced with organic or artificial fibres within the grass roots_______________ 15
• reinforced with implanted fibres_______________________________________ 17
• reinforced with artificial fibres of a turf carpet____________________________ 19
Typical pitch constructions_______________________________________________ 24
Line markings_________________________________________________________ 28
ADDITIONAL PITCH INSTALLATIONS
Water sprinkler _______________________________________________________ 29
Soil heating __________________________________________________________ 31
Artificial lightening_____________________________________________________ 33
Artificial aeration below the root zone______________________________________ 34
MAINTENANCE __________________________________________________ 36
Cost comparison between the three mayor turf systems________________________ 37
Example of detailed yearly maintenance cost________________________________ 38
APPENDIX
Competition regulations_________________________________________________ 41
Extracts of studies and publications of reinforced grass_______________________ 42
Detailed footballistic test results__________________________________________ 46
Test template for natural and reinforced grass pitches_________________________ 47
Author Rolf HedigerExpert in sport surfaces / floorings; 30 years of experiencesDirector of a sport surface installation company; 1980 - 1997Sport expert, Sportfloor TechnologieS, since 1997Consultant of UEFA, Fifa, the Italian Football Federation (LND) and EFTGInitiator of the UEFA test manual and test criteria (2003); today’s FIFA Football Turf 2Star criteriaUEFA study comparing natural grass and Football Turf (footballistic qualities compared to injuries)in European stadia used by professional teams in the Champions League 2006-2008 und during the Euro08
Address 28, CorgeonCH-1095 [email protected] www.sportfloor.ch
Documentation Publication from the industry, Football Associations and communities
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INTRODUCTION
What exactly is a natural grass pitch?
Natural grass is something so common in our l ives that we take its very existence, and rampant use, for granted. Butwhat is grass and why do we spend so much time obsessing over it? Grass is the familiar name given to the family ofplants known as the graminae. The graminae family consists of over 6,000 species, making it one of the largest in life.
Grass, as a family, isn't limited to being something to just play football on. Bamboo rice, corn and oats are part of thegrass plant family and so are the plants that make sugar, liquor, bread, and many other staples of the average kitchentable. Though it may not seem obvious, even lawn grass contains the building blocks of all plant l ife: stems, roots,leaves, and yes, flowers. The flowers are quite obvious in grass plants like corn or even wheat. But in garden grass, youhave to get on your hands and knees to see how the grass functions and reproduces. The secret to grass, if there is one,is the fact that it all its growing takes place from what is known as the crown: a part of the stem that is at or near thesurface of the ground. Grass is adaptable and relatively easy to garden. You can mow a lawn and as long as the crownlevel isn't affected, the grass grows back. Likewise, if you grow grass and slice it from the ground as turf, as long as thecrown remains intact, the roots underneath can be sliced through below their tips. Grass reproduces by the seedingprocess, but also by stems that emanate from the crown. Stems that grow above the surface are called stolons. Stemsbelow the surface are called rhizomes.
STADIA PITCH QUALITIES Some questions and answers concerning natural grass football pi tches
What do the Football Associations require concerning the different types and qualities of grass used in itscompetitions?
• There are no regulation and recommendations whatsoever concerning the grass types and qualities used forfootball and so far no studies have been published by Football Federations.
What does the football player wish / request of a grass pi tch?
• A soft, not too deep surface.
• A full / dense and humid grass cover.
• An optical nice looking green surface.
What does the spectators like?
• An optically nice looking green pitch cover.
How many hours of play a natural grass pitch can be used?
• A natural grass pitch can, under normal circumstances, be used only a few hours per week, calculated over afull year between 400 to max. 700 hours, in order to keep a pitch in perfect condition.
What about stadium pit ches used for European Championship matches?In modern stadium, the surfaces can very often not be used as they are covered with:
• Artificial lighting to make the grass growing especially in the shades of the arena roofs.
• Covers over the entire pitch in order to blow warm air onto the pitch in order to grow the grass during the wintermonths.
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Natural grass quality
Pitches used for UEFA championship matches dur ing the season 2005 / 2006
Extremes overused pitches…
… and pitches covered with sicknesses
An average stadia grass density…. …… compared to an ideal grass density
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Perfect root density without too much thatch
Some renowned Greenkeeper of mayor stadium in Europe do think that the ideal compositionof a 100% natural grass pitch should be composed of:
• 70 – 90% Lolium Perenne
• 30 – 10% Poa pratensis
During the FIFA World Cup 2006 in Germany, two grass solutions have been adopted for all stadia pitches Type A
70% Festuca arundinacea 10% Lolium perenne
20% Poa protensis
Type A 80% Festuca arundinacea 20% Poa pratensis
• Poa pratensis= Kentucky blue grass = Common Meadow Grass = = Smooth stork meadow grass = Pâturindes prés = Wiesenrispe
• Lolium perenne = Ray-grass (english) = Perennial Ryegrass = Weidelgrass
• Festuca arundinacea = Fétuque élevée = Tall fescue = Rohr-Schwingel
Characteristics
Lolium Perenne Poa pratensisFine leaves Less playing resistance
Good playing resistance Need more maintenance and fertilisation
Good resistance against sicknesses Good resistance for a low cut, around 20mm
Fast growing Slow growing
Note: it seems that poa potencies can cause problemsbecause of its very strong roots which can lead to hightraction values = possible injuries.
Lolium Perenne Poa pratensis
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This graph show the type and composition of grass used in some of the mayor stadiumsand if any reinforcement is used, which type of reinforcement
0
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A B E Ma MI MO P B1 B2 B G Z I K S V
Lolium perenne Poa pratensisPoa supina Kentucky BlueLolium & Poa in unknown proportion Limonta SportDD GrassMaster Fibreturf
It is estimated that an excellent football pitch has about 25’000 to 40’000 grass leafs per m2,which means an average of 300 Million grasses leafs per football pitch! A comparison: Golf Greens contain about 100’000 to 200’000 leafs par m2
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Maybe some stupid questionsMany football pitches in mayor stadium are reinforced with all types of artificial fibres systems or grow natural grasswithin artificial turfs.
• Are Football pitches with implanted artificial fibres or similar systems assimilated to natural grass?
• At which moment a football pitch is no longer considered natural?
• Is it when the numbers of artificial fibres per m2 are 10%, 20% or above 50% of a pitch?
Mix of natural grass and artificial fibres (National Stadium, San Marino)
Answer At the moment, 2010, the Football Associations (FIFA and UEFA) do not take this evolution into account.They are considering that a pitch which has any kind and number of natural grass within the playing surface is to beconsidered as natural grass. No any kinds of approvals or tests are required as with artificial pitches.
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Ar ti ficial help to reinforce and grow the natural grass
To strengthen the natural grass, in some stadia grass pitches, the grass root zone is reinforced with artificial ororganic fibres. Additional equipment is also installed in order to keep the grass growth as soil heating and aerationsystems below the root zone and above the turf as well as artificial lighting.
Implanted artificial fi bres and artificial light ing (London, Emirate Stadium)
Arti ficial aeration below and above the pitch
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Footballistic and technical quality differences
Footballistic and technical tests have been by UEFA made on European stadia with natural andreinforced grass pitches used for UEFA championship matches during the seasons 2006 to 2008 aswell as during the EURO08.The stadia pitches have been tested by 5 different FIFA accredited test laboratories and the testedpitches are
• 97 Football Turf
• 29 natural grass• 6 reinforced natural grass
During the same period the number and type of injuries where recorded by Prof. Ekstrand, a memberof the UEFA Medical committee, and a correlation between the footballistic pitch results and the injury studydata has been made.
Some test apparatus
Ball roll, Rotational resistance and Shock absorption / Energy restitution / V-deformation
ResultsUntil today, UEFA has not published the test report, therefore no detailed comments can bemade.In general, the pitch results show significant technical and footballistic quality differences between thetested pitches. Due to the technical and footballistic characteristics, the natural grass pitches have tobe divided into two groups; on one hand pitches with natural grass (pure top soil) and on the otherhand natural grass including different systems of root reinforcements.
Ball roll distanceTest results on different football pitches in mayor European stadia
Lenth of the ball roll in m compared to the grass height in mm
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Ars enal april Arsenal
september
Barcelona Eindhoven
february
Eindhoven
september
Malta Moscow
Locomotif
Milan Porto
mm minimum maximum
A B C D E F G H IContrary to general belief (coaches and ground keepers), the grass density(grass cover) defines the ball speed and not the height of the grass!
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NATURAL GRASS GROWN OUTSIDE OF STADIA
Natural grass harvested in turf farms
Harvesting in rolls from 0.30m to 2.20m width and 15 to 35mm thickness
Installation during the EURO08 in Basel
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Installation for the European Champions final in Moscow (Luzhniki) 2008
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Covering the artificial turf wi th a natural grass pitch for the EURO08
Experiences dur ing the EURO08 in Bern Wankdorf (Swi tzerland) and Salzburg (Austria)
Af ter the EURO08, removal of the natural grass
Construction scheme for the EURO 08 in Bern and Salzburg
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Natural grass grown in box systems
Preparation and fi lling the modules with sand
Levelling the height ready to plant the grass
The modules are ready for the installation in the stadium
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The installation in the stadium
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REINFORCED NATURAL GRASS
Grass reinforced with organic or artific ial fibres within the grass roots
The marked overall improvement in football pitches probably really started in the late 70’s and early 80’s, with theintroduction of sand - dominant root zones.However as an infrastructure with 100% sand is unstable, various fibre reinforcement techniques in sand-dominant root zones represented a significant step forward in tackling the basic lack of stability inherent in suchroot zones.Two such techniques firstly, the Fibreturf system of random fibre orientation developed in the USA in order to usea stadium for concerts and other non sportive events and secondly, the DESSO GrassMaster system of ‘stitchedfibre’.This type of pitches are now relatively commonplace and are to be found in many top-class pitches and also onthe numerous training and academy pitches of the top tier clubs.
However, sand-dominant root zones by their very nature produce harder surfaces than soil root zones; fibre-reinforced sand-dominant root zones even more so. The development of maintenance techniques, particularlyVerti-draining and other forms of solid-tine aeration, has been very important, therefore, in enabling the groundsstaff to exercise control over the somewhat conflicting requirements of hardness v stability.
The majeure problems of all t his type of pitchesare felt and thatch!
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Fibrelastic, a product of Fibresand UK
Fibrelastic® pitches are both more player friendly and more grounds man friendly than existing fibre reinforcedsand dominant pitches and, as such, represent a further step forward in root zone technology for natural turfpitches. This particular grass root reinforcement lessens the surface hardness, reducing the risk of player injury,and improves both the surface resilience and traction. A typical Fibrelastic® Root zone (FERZ) would comprise 80% by volume sand and 20% by volume organic matterreinforced with both Polypropylene and Elastane fibres. The reinforced root zone is totally premixed at our
modern production facility and delivered to site in bulk tipper vehicles. A typical Football or Rugby pitch of 7,500 m2 would require 1,200 tonnes of FERZ to form the upper root zone ata depth of 100mm. The importance of this procedure makes it essential for the Fibrelastic® pitch to be laid by aqualified and specialist sports turf contractor.Fibrelastic is different to other fibre reinforced sand dominant pitches such as Desso GrassMaster and XtraGrass.These rely on synthetic grass fibres as the root zone stabiliser.The aim has been achieved by mixing silica sand, organic matter, rigid polypropylene fibres and flexible elastanefibres to produce a completely homogeneous blend which is termed a Fibrelastic® Root zone (FERZ).The fully pre-mixed blend is then supplied to site for the sports field contractor to lay typically as a 100mm thickupper root zone followed by surface preparation, fertilisation and seeding in order to produce the final natural turffinish.This ‘elastication’ of the pitch provides a much more player-friendly surface, with less jarring of the limbs and alower risk of injury. It is also less prone to surface disturbance, giving ball players a better grip.It’s easier to look after than most current pitches because it’s just as hard wearing but doesn’t get as many divots.
In order to keep making progress and particularly in order to address the hardness v stability situation, FibresandUK in 2007, after a two year research programme at the STRI, introduced a new dual fibre reinforced root zonetermed Fibrelastic.The Fibrelastic rootzone system should ensure a firmer more resilient playing surface and comprises silica sand,organic matter, rigid polypropylene fibres and flexible elastane fibres, which produce an ‘elastication’ of the pitch. As a result, the surface should be less tiring and more player friendly, with injuries to knees, ankles and lowerbacks less likely to occur. It also should make the surface less prone to disturbance, giving players a better grip.
The aim of the product was threefold: Firstly, a reduction in surface hardness = less jarring of limbs and lower riskof player injury. Secondly, an increase in surface resilience = more energy feedback to players feet, therefore, aless tiring surface. Thirdly, a further increase in root zone cohesion = increased traction, therefore, les surfacedisturbance.
The overall result of these three factors is a surface which has all the attributes of a typical fibre-reinforced sanddominant surface but which feels considerably softer and more akin to a soil based pitch in good condition.
For more details, refer to Appendix: extracts of studies and publications concerning Turfgrids, Fibersoil and similar products
Aviva Stadium, Dubl in
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Grass reinforced with implanted artificial fibres
GrassMaster, a product of Desso
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1. The leaf blades reside above the tops of the synthetic tufts creating a fully natural grass surface. If the turfcanopy is worn away, the sand based filled synthetic matrix continues to provide a consistent, sure-footedplaying field.
2. The grass roots become entwined in the matrix of synthetic tufts and, unimpeded, grow downward throughthe plastic mesh and into the foundation material below.
3. The predominantly sand fill layer is selected to be compatible with our site’s foundation material,
minimizing the potential for layering and assuring high water infiltration rates through the turf.4. The tough plastic mesh immediately below the vertical fibres acts as the anchor for the components above
it and provides additional horizontal subsurface load bearing capacity. Depth around 20cm every 2x2cmand above the ground between 15-20mm.
This means a reinforced Grass Master Football pitch contains approximately
20 Million synthetic fibers
together with 300 Millions of natural grass fibers
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Natural grass reinforced with artificial fibres of a turf carpet
XtraGrass, a product of Greenfields
XtraGrass™ is a grass reinforcement system natural grass grows through a specially woven synthetic turf fabric.1. The presence of the XtraGrass reinforcement, with or without polystyrene amendment in the root zone, does
not significantly affect plant development.
2. The addition of polystyrene amendments to the root zone of the XtraGrass system significantly reduces
hardness of the surface, resulting in values well within the acceptable range for football.
3. Ball rebound resilience followed a similar pattern to hardness, with all values within the acceptable range.
4. All trials with XtraGrass reinforcement had significantly higher traction values than the un-reinforced natural
grass reference trials. The advantage of using XtraGrass reinforcement is evident in that even under high
intensity wear it still has better traction than un-reinforced natural turf subjected to moderate wear.
5. Infiltration rates for all treatments XtraGrass were very good.
6. Furthermore no hydrological barriers are being created for drainage and irrigation water to be obstructed to
move to lower levels of the playing field.
7. The results for hardness, ball rebound and traction from the XtraGrass reinforcement are comparable with
measurements made by STRI on professional natural turf football pitches during studies in 2000-2005.
Installation
XtraGrass™ will be supplied to site in 1,4m wide rolls or alternatively pre-manufactured into rolls of 4,2m width.Each roll or section of rolls will be laid on the prepared root zone surface ensuring the level and evenness of theroot zone will remain within the required specification. The joints will be sewn together using a hand operatedsewing machine with cotton thread. After the rolls have been sewn together the carpet is stretched over the pitchsurface, the root zone mix topdressing will be applied via a special topdressing unit either tractor mounted orstand alone. The root zone mix will be dried for this purpose. The infill rate is set for 10-15mm of material at eachapplication, followed by a tractor mounted brush in order to lift the XtraGrass™ fibres. The total infill rate of 45-50mm will be achieved after 3-4 applications. Once the final level and surface evenness has been achieved theXtraGrass™ fibres will stand up and show for a minimum of 80%. A pre-seeding fertilizer application will be addedto the root zone prior to seeding.
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The pitch will be seeded using a Brillion type of seeder ensuring the integrity of the XtraGrass™ system will notbe damaged. The type of grass seed and application rates as well as seeding depth is depending on the climateconditions at the project location and will be specified during the initial site meetings. After seeding the pitch will be rolled with a light land roll to cover and fix the seed in the top of the root zoneprotecting it from washing out or animal damage. Regular watering will commence after seeding in order toencourage the germination of the grass. Once the grass has germinated and the plants reach a length of 50mm,the initial cut will be made using a pedestrian rotary mower. A detailed maintenance program will be prescribed toensure swift settlement of the grass within the XtraGrass™ system.
Advantages
The stability of the pitch is enhanced substantially by combining the strengths of synthetic and natural turf
Increased hours of use on natural turf: up to 1000 hours of playing time can be achieved with the correct
maintenance program
Can be grown as big roll, 40-50mm thick, and cut turf.
The open structure avoids compaction, which can be enhanced by additions in the lower root zone
XtraGrass™ allows traditional turf management practices to be carried out
The increased strength of the sward and stability of the pitch, pitches can be used for different sports, such as
rugby and soccer
Excellent playability in poor weather conditions due to excellent stability and water permeabilityThe synthetic turf fibres have a green ‘natural grass-like’ appearance and protect root zone and grass plants
Level and smooth surface
Easy to exchange (parts of) the pitch with new XtraGrass turf.
PITCH PERFORMANCE CRITERIA - STRI TESTS
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Green Live, a product of Limonta
Green Live is a grass reinforcement system where natural grass grows within a special organic infill material andartificial fibres.
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Base: Volcanic gravel
Arti ficial grass: Limonta Diamond 60mm
Infill: Organic performance Infill “ Pro-Geo”
Seeding: Lolium perenne and Poa pratensis
Usage: 5-6houres a day, summer and winter
Maintenance Clipping ( mowing: 2-3 x per week in the growing season Fertilisation every 2 months Harrowing, brushing and removal of the thatch 2 x a month Over seeding: executed the traditional way
No maintenance work for: Top dressing, coring, sodding, verti-cutting, addition of sand, aeration Preventive weed control: no weeds do grow in this type of pitch Pest control: no preventive treatments (only of any symptoms manifest / are visible)
Watering 5-6mm water per day
Spring 2 x per week Summer 3 x per week Autumn 1 x per week Winter nothing
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Installation in the National stadium of San Marino
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SOME EXAMPLES OF PITCH CONSTRUCTIONS
Construct ions in Germany; according to DIN 18 035/4
• Ray grass
• Top soil mixed with volcanic gravel, 5cm; or
• Top soil & sand 50/50 15cm (coarse sand 30%, fine sand 15%, chalk 1.5%, argil less than 5%, organic materialmin.3.5%, azotes min. 0.1%, potassium 0.025 and 0.05%, PH 5 to 8)
•
Crushed rock 10 – 20cm• Drainages on top every 120cm, depth 35cm, with 5cm with round gravel min. 5cm all around
• Drainage below every 6 to 12m, diam. 60-80mm, depth min. 30cm, slope min.03%
• Bottom of the excavation, slope 0.5 - 1%
Stade de Gerland in Lyon, France
• 50% ray grass and 50% poa pratensis
• Prefabricated turf
• Supporting layer: 160mm volcanic soil (pouzzolane - scoria carboniferous)
• Gravel layer: 10/20 of 15mm
• Gravel layer: 20/40 of 40cm
• Drainages: every 6 to 10m, diam. 80 to 100mm
• Bottom of the excavation, slope 0.5 - 1%
Stade de Genève, Switzerland
• 50% ray grass and 50% poa pratensis
• Prefabricated turf
• Support: 150mm volcanic soil (pouzzolane 0/6 - scoria carboniferous)
• Layer of pouzzolane 15cm
• Gravel layer, 30cm
• Drainages
• Bottom of the excavation
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Example of cross sections
System with drainages
System without drainages (water permeable bottom of excavation)
Example: Stade de Genève
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Construction experiences outside of Europe
Example from Asia
Construction parameter
• River gravel as foundation
• Standard drainage system
• 5cm not washed see sand
• Grass cover with 50% Princess and 50% Sydney couch (20/20kg/m2)
The field and it’s surrounding with a grass cover without any treatment.
Comparison of two infrastructure compositi on on the same pitch. Sydney couch grass and treated invadergrass (yellow colour). Bigger invaders have to be removed by hand-picking.
A pitch wi th excel lent deep growing roots and a mixture of Sydney and Princess Grass
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A pitch wi th Sydney blue couch
Comparison: irrigated pit ch and non irr igated and treated spectator area
Base with purely natural top soil …… and enhanced with sand
Example from South-Africa
SSSouth African sports fields contain warm-season grass types, usually Kikuyu (Durban’s Moses Mabhida stadium isthe only match venue containing a warm-season grass called Cynoden) as Kikuyu grass doesn’t perform well in thesalty environment of Durban because it is inexpensive and drought tolerant.The FIFA however demanded that all World Cup matches must be played on cool season Ryegrass, because it isaesthetically more pleasing in colour for the television-screen. This is possible, because the World Cup is beingplayed during the South African winter, when the Kikuyu goes dormant.TTTherefore, all 72 playing fields (fields containing Rye grass spread all over the country are dedicated to the WorldCup) assigned for the World Cup 2010 were recently renovated with fraise mowing to remove the top of the Kikuyuplants leaving only the roots. These roots are very important as they serve as a reinforcement of the turf and create abase for the roots of the Ryegrass to hold on to.
The pitches were then aerated using a Verti-Drain, cracking the soil with solid tines and thus creating ideal growingconditions for the new seed which was sown using a Speed-Seed.This seeder creates close on 1900 holes per m2 with random dispersal of seed to leave no drill lines.TTThe procedure was finished off with the surface receiving a thin layer of sand from, for example, a Rink brushspreader. This ensured the seed was allowed the maximum soil contact for optimum germination. This is followed byvery heavy irrigation, between 100.000-150.000 litters per field per day, so that the thirsty Ryegrass could grow anddevelop quickly. (Information from STRI)
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Line markings
Visible displacement of the pitch playing lines to avoid overuse of the grass
Note:The security zone for UEFA is minimum 3m, however this depend national regulation.In addition, it is recommended to add a stabilised 3m surrounding between the security zone and the spectators.Elements such as filed markings goalpost etc…, have to be according to the laws of the game and the local competition regulation.
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ADDITIONAL PITCH INSTALLATIONS
Water sprinkler
Water sprinkler ins talled at the edge of the pitch
This type of sprinklers should not be installed in the middle of the pitch, as they can endanger theplayers.
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If irrigation systems are installed within the pitch, they must be small enough as not to affect andendanger the players.
Multiple irrigation system used in San Marino fo r a reinforced natural grass pit ch
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Soil heating
Samples of soil heating systems (with w ater or w ith electricity)
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Example
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Ar tif icial l ightening
Arsenal, Emi rate Stadium
Quote Paul Burgess, Greenkeeper of ArsenalIn order that the system is useful it needs 9 units for a half pitch, which cost approx. 1 Mio. SFr, withrunning cost per year of SFr.180’000.- . During the winter months, the lighting is used every day / 24hduring 6 months (except on match day).Result: the grass cover will never be below 90% (if the additional daily maintenance is done).
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Ar ti fic ial aeration below the root zone
SubAir system
The SubAir system applies a vacuum within the subsoil drainage pipe network to increase the rate at which wateris moved from the surface and through the soil profile. The management of subsoil moisture also helps with
temperature moderation in the entire soil profile.
SubAir also applies pressure to force air from the subsoil pipes through the soil profile. This patented technologycreates air movement that provides aeration while moderating temperature in the root zone.
The SubAir aeration and moisture removal system promotes healthier, stronger playing surfaces through moisturecontent management, subsurface aeration, and root zone temperature control. As a result, SubAir providesoptimum aerobic subsurface growing conditions.SubAir’s team of agronomists and engineers has developed a complete system to accelerate moisture removaland increase gas exchange. The SubAir Sport system helps provide an optimal growing environment for anyplaying surface – increasing playability and producing a more enjoyable experience for players and spectators.Through the use of the AirWave monitoring and control system, SubAir Sport is automated based on datareceived from the field.
A SubAir Elite vault, housing the blower that provides both vacuum and pressure mode, is connected to the pipingnetwork. A Distributed Separator is connected to the green’s drainage network. This patented assemblyseparates the air from the water so that the air flows to the SubAir vault and the water drains to the outfall. A Dual
Valve is used on the end of each outfall to create an air lock. This directs the air through the soil profile so it doesnot escape through an open ended pipe.
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OSMO-DRAIN System
The system for the
• Aeration
• Ventilation
• Watering
• Drainageof Football pitches can be installed into an existing pitch par a special cut machine. On the edge of the pitch every 25cma cut is made with a width of 16mm. During the same work action, a tube is laid without mixing the different subsoil
stratus. The only visible part of the work will be outside of the playing surface for the access tubes.
Aeration and venti lat ion Air can be compressed pushed through the tubes into the sub-soil. Each sector of the pitch can be treated individual.Within one hour the full pitch can be treated. On the contrary it is possible to make an aspiration of ambient oxygen fromthe top of the pitch into the sub-soil.
Watering and drainageDepend the amount of rainfall or the size of the shade covering, the water quality can be adjusted for each sectorindividually and gradually.
Access pipes….. and installation of the tubes
Existing pitch with a new installation
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A pitch being over seeded with theSpeed Seed, a machine which isproducing nearly 2000 holes per m2for the seed to drop in. Immediately
behind the Speed Seed, the soil waspenetrated vertically by hollow coringtines installed on the Verti-DrainMustang.
Thus, the soil and the seed werebrought to the surface of the field.This was followed by a drag mat,which pulled the seed and soilmixture into the millions of holesensuring a maximum germination
A pitch being over seeded with theSpeed Seed, a machine which isproducing nearly 2000 holes per m2 forthe seed to drop in. Immediately behindthe Speed Seed, the soil waspenetrated vertically by hollow coringtines installed on the Verti-DrainMustang.
Verti-Drain model hollow cores thestadium pitch 300mm deep in order toestablish a perfectly drainingsubsurface, before the new grass coverwas brought on.
MAINTENANCE
Example by Redexim
After the installation of a new grasscover of approximately 3 ½cm thick,it was then immediately followed by atreatment with the Verti-DrainMustang with thin solid tines, in orderto establish quickly the contact of thenew grass cover with theunderground.
A top dresser spreads the sand
between the grass blades, 2 weeksbefore the first game.
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MAINTENANCE COST
Cost comparison between the three mayor tur f systems
Natural grass
Reinforced natural grass (example : GreenLive)
Football Turf (artificial turf)
GRASS TYPE natural grassReinforced
natural grass Football Turf
Maximal hours of usage per year 500 - 700 700 - 1000 1800
Pitch size: 105 m x 68 m plus 3m securi ty
Cleaning 2 hours per week 7’500.00 7’500.00 5'000.00
Decompaction 7'900.00 3'600.00
Line marking 9'600.00 9'600.00
Mowing 17'200.00 17'200.00
Rolling 3'800.00
Irrigation 12'000.00 12'000.00 5'000.00
Fertilisation 4'700.00 4'700.00
Treatments 1'600.00 1'600.00
Slitting 2'500.00
Verti-cutting 6'500.00
Replacements 4'300.00
Dressing 3'000.00
Emptying the sprinkler system during the winter 400.00 400.00 400.00
Harrowing 4'500.00
Over seeding 2'500.00
Replacement or removal of granules 2'500.00
Brushing 4'500.00
Divers (fuel and power) 2'500.00 2'500.00 2'500.00
TOTAL COST 83'500.00 62'500.00 26'000.00
COST PER ONE HOUR OF PLAY 140.00 75.00 15.00PITCH CONSTRUCTION COST 600’000.00 1'700'000.00 1'500'000.00
COST PER ONE HOUR OF PLAYDURING 10 YEARS
225.- 265.- 95.-
RENOVATION COST 100'000.- 300'000.- 600'000.-
COST PER ONE HOUR OF PLAYDURING 20 YEARS
190.- 190.- 70.-
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Example of a detailed yearly report from a communi ty in the Geneva area
Usage in hours of a football pitch during one year HOURS
Janvier 0
Février 51
Mars 102
Avril 102
Mai 102
Juin 51Juillet 0
Août 51
Septembre 102
Octobre 102
Novembre 102
Décembre 51
Total 816
Entretien
Electricité / lumière terrain / an: 32 KW x 52 sem. X 5,6 h 9'318.40 0.2175 2'026.75
MO / Nettoyage du terrain par an : 2 heures par semaine 104.00 48.32 5'025.28
MO / Elimination des déchets : 1 heure par semaine 52.00 48.32 2'512.64
MO / Nettoyage des vestiaires : 2-4 vestiaires 195.00 48.32 9'422.40
1. Décompactage 7'865.552. Marquage 9'610.24
3.Tonte 17'171.52
4. Débroussaillage clôture 745.44
5. Roulage terrain 3'787.20
6. Arrosage 11'900.80
7. Engrais 4'727.40
8. Traitements terrain 1'621.28
9. Traitements clôtures 877.20
10. Fendeuse 2'524.80
11. Carottage sur-semi 6'417.20
12. Placage 4'212.64
13. Sous-sablage 3'000.00
14. Mise en eau / hors gel 386.56
15. Divers travaux d'entretien 2'512.64
TOTAL entretien 77'360.47 77'360.47
TOTAL DES COUTS D'ENTRETIEN ANNUEL 96'347.54
(*) variable : le prix de revient de la MO
Coût par heures (816) 118.00
Coût par heures (816) de jeux par jouer (22) 5.40
Coût de la construction à neuf, durée de vie 30 ans 600'000.00
Coût d'un plaquage après 15 ans 250'000.00
Coût d'entretien pendent 30 ans, 27 x 100'000.- 2'700'000.00
Coût de l'amortissement, 15 ans 600'000.- & 250'000.- 600'000.00
Coût total sur une dure de vie de 30 ans 4'150'000.00
Coût par heures (816) 170.00
Coût par heures (816) de jeux par jouer (22) 7.70
Recyclage 60 m3/30 tonnes x 28 semaines (*)estimation faite à 500 kg au m3 30.00 160.00 4'800.00
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Coût de revient détaillé1. Décompactage confié à une entreprise extérieure 7'865.55
Période et fréquence : de 1 x par an à 1 x tous les 2 ans
2. Marquage
Période 8 mois
Fréquence 1 x par semaine
Durée 1 heure
Mo interne 32 heures 32.00 48.32 1'546.24
Heures machine 32 heures 32.00 120.00 3'840.00Matériels 20 kg = CHF 132.-- par semaine 32.00 132.00 4'224.003.Tonte
Période Avril à octobre = 28 semaines
Fréquence 1,5 x par semaine en moyenne
Durée 1 heure
Mo interne 1 h x 1,5 x 28 semaines (tonte) 42.00 48.32 2'029.44Heures machine 1 h x 1,5 x 28 semaines (tonte) 42.00 120.00 5'040.00
Mo interne 0.75 h x 1,5 x 28 sem. (ramassage) 31.50 48.32 1'522.08
Heures machine 0.75 h x 1,5 x 28 sem. (ramassage) 31.50 120.00 3'780.00
4. Débroussaillage clôture
Fréquence 3 x par année
Durée 1,5 heure
Mo interne 1,5 x 3 4.50 48.32 217.44
Heures machine 1,5 x 3 4.40 120.00 528.00Recyclage compris sous point 3 160.005. Roulage terrain
Période Avril-octobre sans l'été = 10 sem.
Fréquence 1,5 x par semaine
Durée 1,5 heure
Mo interne 1,5 h x 1,5 x 10 semaines 22.50 48.32 1'087.20
Heures machine 1,5 h x 1,5 x 10 semaines 22.50 120.00 2'700.00
6. Arrosage
Période Mai à septembre = 20 semaines
Fréquence 3 arrosages par semaine
Consommation 3 x 86 m3 x 20 semaines 5'160.00 1.26 6'501.60
Mo interne 1 h x 3 x 20 semaines 60.00 48.32 2'899.20
Matériels Remplacement pièces d'arrosage 2'500.00
7. Engrais Fréquence 5 x par année
Durée 1,5 heure
Mo interne 1,5 h x 5 7.50 48.32 362.40
Heures machine 1,5 h x 5 7.50 120.00 900.00
Matériels 5 x 7 sacs de 25 kg/CHF 99.-- 35.00 99.00 3'465.00
8.Traitements terrain
Fréquence 2 x par année pour 6'000 m2
Durée 2 heures
Mo interne 2 h x 2 4.00 48.32 193.28
Heures machine 2 h x 2 4.00 120.00 480.00
Matériels 30 litres x 2 60.00 15.80 948.00
9. Traitements clôtures
Fréquence 2 x par année pour environ 50 m2Durée 2,5 heures
Mo interne 2,5 h x 2 5.00 48.32 241.60
Heures machine 2,5 h x 2 5.00 120.00 600.00
Matériels 1 litre x 2 2.00 17.80 35.6010. Fendeuse
Période Février à octobre
Fréquence 10 x par année
Durée 1,5 heure
Mo interne 1,5 x 10 15.00 48.32 724.80
Heures machine 1,5 x 10 15.00 120.00 1'800.00
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11. Carottage sur-semi
Fréquence 2 à 3 x par année pour 6'000 m2
CARROTTAGE
Durée 2 heures
Mo interne 2 h x 3 6.00 48.32 289.92
Heures machine 2 h x 3 6.00 120.00 720.00
Matériels 0,015 kg x 6'000 m2 x 3 270.00 9.00 2'430.00
PASSAGE DE LA GRILLEDurée 0,75 heure
Mo interne 0,75 h x 3 2.25 48.32 108.72
Heures machine 0,75 h x 3 2.25 120.00 270.00
PASSAGE DU ROULEAU
Durée 0,75 heure
Mo interne 0,75 h x 3 2.25 48.32 108.72
Heures machine 0,75 h x 3 2.25 120.00 270.00
EPANDAGE PAILLE 1 X par année
Durée 4 heures
Mo interne 4 h x 3 12.00 48.32 579.84
Heures machine 4 h x 3 12.00 120.00 1'440.00
Matériels 2 rouleaux à CHF 100.-- pièce 2.00 100.00 200.00
12. Placage Pour une surface d'environ 200 m2
Fréquence 1 x par annéeDurée 2 jours pour 2 personnes
Mo interne 2 jours x 8 heures x 2 personnes 32.00 48.32 1'546.24
Heures machine 0,5 jour x 8 heures x 5 personnes 20.00 48.32 966.40
Matériels 200.00 8.50 1'700.00
13. Sous-sablage confié à une entreprise extérieure 3'000.00
Fréquence 1 x tous les 2 ans
14. Mise en eau / hors gel
Période Printemps - automne
Fréquence 2 x par année
Durée 4 heures
Mo interne 4 h x 2 8.00 48.32 386.56
15. Divers travaux d'entretien
Période Toute l'année
Fréquence 1 x par semaineDurée 1 heure
Mo interne 1 h x 52 52.00 48.32 2'512.64
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APPENDIX
UEFA Competition regulations
The UEFA competition regulations are edited new each year and refer to:
• Technical Recommendations and Requirements for the Construction or Modernisation of Football Stadium,
and
• Regulations of the UEFA Champions League
The regulations require a playing field in perfect playing condition:
absolutely smooth and level
with an efficient watering system
equipped with a underground heating system in cold climates
with a recommended field area of 120m x 80m
with playing dimensions of 105m x 68m
with a natural grass cover or an artificial turf*
Arti cle 7 – Playing sur face
1 The stadium must be equipped with either a natural playing surface or a Football Turf (artificial turf).
2 A Football Turf must meet all of the following conditions:
a) it must have been granted the required FIFA licence, which can only be delivered after the turf in questionhas been tested by a FIFA-accredited laboratory as meeting the FIFA quality standards for artificial turf;
b) it must meet all the requirements of the national legislation in force;
c) its surface must be green.
UEFA Cup and UEFA Champions League competi tions
If the cover is a Football Turf, intended to be used for an UEFA competition, then the pitch has to be certifiedaccording to the FIFA Quality Concept 2 Star system and must show a valid test certificate (validity: maximum 12months).
UEFA competitions for Under-17, Under-19, Under-21 and women
Type of test certificate depending of the UEFA product manager; minimum according to IATS.
Swiss Competition regulations
The field of play must be absolutely smooth and level.
It must be equipped with a drainage system to eliminate the possibility of its becoming unplayable due to flooding.It must comply with the following dimensions and requirements
Stadium category Length Width Additional requirements
Super league
Challenge league105m 68m
1st league 100m 64m
100m 64mRegional leagues
or proportionally maximum 10% less
SlopeLength: max. 0.5%Width: max 1%
The stadium must be equipped with either a natural playing surface or a Football Turf (artificial turf).
Stadium category Football Turf
Super league
Challenge leagueFIFA 2 Star
1st league min. FIFA 1 Star
Regional leagues min. CEN-EN
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Extracts of s tudies and publications
Turfgrids, FibersoilCopyright ©2007 Fibersoils. Geofibers®, TurfGrids®, and Sportgrids®This study was conducted to determine the effect of various
types and rates of soil reinforcing materials on soil bulk density,
soil water content, surface
hardness, and turfgrass density of a high-sand root zone exposed to three levels of simulated
traffic (wear). Six soil reinforcing materials were mixed at
varying rates with a high-sand root zone. These included DuPont Shredded Carpet, Netlon, Nike Lights, Nike Heavies, Turfgrids,
and Sportgrass. Three
levels of wear were imposed on each treatment. The types and rates of reinforcing materials had varying effects
on surface hardness, bulk density,
water content, and turf density of the root zone. Surface hardness and soil bulk density were
correlated during the 2-yr test period (r = 0.63). The
reinforcing treatments that lowered soil bulk density and surface hardness
were DuPont Shredded Carpet, Nike Lights, and Nike Heavies.
Reinforcing
material treatments that increased or did not affect soil bulk density generally resulted in increased surface hardness
compared with nonamended
controls. These treatments included Netlon and Turfgrids. Surface hardness generally became more pronounced as the level of wear increased forNetlon, Turfgrids,
and Sportgrass treatments. The Sportgrass treatment consistently
measured lower in soil water content than the control and had
a
turfgrass density lower than the control on all rating dates in 1996 but did not differ from the control in 1997. Athletic
field managers considering using
reinforcing materials should be aware that the type of material and rate influence athletic
field surface hardness.
Table 5. Mean surface hardness, soil bulk density, and soil water content values for treatments across all wear levels.
SOIL REINFORCING MATERIALS have been mixed with high-sand athletic field root zones in an attempt to improve surface stability. Althoughsome of these materials have demonstrated improved
playing surface quality through greater surface stability, there
is evidence that certain reinforcing
materials increase soil bulk density and surface hardness (Baker, 1997). Surfaces that
are hard can be dangerous to athletes (Rogers and Waddington,
1990). Reinforcing materials considered for use in athletic
field root zones should provide surface stability benefits without
increasing surface hardness
to unacceptable levels.
Baker (1997) reviewed much of the research on synthetic reinforcing materials for turfgrass soils and proposed two broad categories:
(i) randomly
oriented fibers, filaments, or mesh elements and (ii) horizontally placed fabrics. Most randomly oriented fiber
reinforcing materials studied in turf consist
of relatively short polypropylene fibers. Baker and Richards (1995) incorporated
both straight and crimped polypropylene fibers (36 mm in length
and
113 µm in diameter) into sandy soils at rates up to 7.5 g kg
-1. At the 4.0 g kg
-1 rate they reported increased surface
hardness on two of the 11 rating
dates. When the rate was increased to 7.5 g kg
-1, significant increases in surface hardness were
reported on eight of the 11 rating dates. During dry
conditions at the end of the study, the fiber reinforcing materials made
the surface harder than the range the researchers considered
acceptable for
player/surface impact.
Mesh elements were first evaluated as a soil reinforcing material
by researchers attempting to increase the strength of sand for
engineering applications such as support beneath building footings (Mercer et al., 1984; McGown et al., 1985). Mercer et al. (1984)
stated that to
optimize soil strength, the size and shape of the filaments comprising mesh elements must be related to the
size of soil particles in which they are
placed. In order not to weaken the soil, the addition of mesh elements must not significantly
decrease soil bulk density (Mercer et al., 1984). Mercer et
al. (1984) found that at mesh contents up to 5.5 g kg
-1, the
bulk density of the mixture was the same or greater than the
sand alone.
Turfgrass scientists
have evaluated mesh elements, similar to those described by Mercer et al. (1984), as reinforcing materials
for athletic field root zones. Under simulated
soccer-type wear, Baker (1997) reported no significant effect of mesh elements
on the retention of grass cover, ball rebound, or surface hardness.
In a
study without simulated wear treatments, Beard and Sifers (1993) found an increase in soil water content and a small decrease
in surface hardness
values with increasing concentrations of mesh elements. In another mesh element study using a method
different from Beard and Sifers (1993) to
assess surface hardness, Canaway (1994) reported a general increase in surface hardness
as the rate of mesh elements in sand increased.
Richards (1994) conducted a laboratory study in which mesh elements were mixed with sand and compacted in 100-mm diam. cylinders.
The results
indicated reduced soil bulk density and increased total porosity of the mixture with increasing rates of mesh
elements. These results are not consistent
with the civil engineering work of Mercer et al. (1984) where the mesh elements either
slightly increased or had no effect on soil bulk density.
Another
type of reinforcing material that has been amended into turfgrass soils is shredded carpet. McNitt and Landschoot (2001b)
mixed shredded carpet
fibers into a sand-based modular turf system and found a reduction in divot size and surface hardness.
Shredded carpet is the shredded remains of
predominately nylon carpet fragments that include both pile and backing. The yarn-like
fibers range in length from 20 to 610 mm. Although shredded
carpet has not been widely studied in turf systems, some engineering research has shown that increasing rates of continuous yarn
up to 1 m in length
increased soil strength significantly more
than an equal weight of shorter yarn (Leflaive, 1982). Whereas
the strength imparted by shorter fibers is dueto friction between individual soil particles and the fibers, Leflaive (1982) explained
that continuous yarn increases soil strength by coiling tightly
around
groups of soil particles. In addition, the random looping and crossover of yarn fibers results in a tightening of slack
sections as further soil loading
occurs, thus increasing reinforcement. The conflicting soil bulk density results obtained by civil
engineers and turfgrass researchers for mesh element
reinforcing materials and the varying results obtained for surface hardness
of reinforced sand indicate that additional research is needed
on the effects
of soil reinforcing materials in high-sand athletic field root zones. Also, shredded carpet should be evaluated
as an amendment in high-sand root zones
to determine its effect on surface hardness, soil bulk density, and soil water content
under different levels of wear.
The objective of this study was to
evaluate the effects of varying rates and types of soil reinforcing materials on the surface
hardness, soil bulk density, and soil water content of a sand
root zone after wear is applied.
Descriptions of Reinforcing Materials Randomly Oriented Fibers, Filaments, or Mesh Elements DuPont Shredded Carpet. DuPont Shredded Carpet was obtained
from DuPont Nylon (Chestnut Run Plaza, Wilmington, DE) and is
the shredded
remains of carpet fragments that include both pile and backing. The shredded carpet is not commercially available,
but is a component of a sand-based
modular turfgrass system called GrassTiles (Hummer Sports Turf, Lancaster, PA). DuPont
Shredded Carpet is 70% nylon, 12.2% calcium carbonate,
10.7% latex, and 7.1% polypropylene on a weight basis (V.J. Kumar,
1998, personal communication). On the basis of 100 randomly
selected carpet
fibers, the average length was 135 mm, and the range was 20 to 610 mm. Fifteen carpet fibers were randomly
selected and measured for width. The
width of a carpet fiber averaged 2.4 mm and ranged from 0.5 mm to 4 mm. The compressed
and uncompressed density of a mass of shredded carpet
was measured
using a 1000-mL cylinder. The uncompressed density was determined
by measuring the dry weight of shredded carpet required toloosely fill a 1000-mL cylinder. The compressed density was measured
using the same mass of carpet compressed in the 1000-mL cylinder
using a 1-
kg weight. The compressed and uncompressed densities of the shredded carpet were 0.153 and 0.073 g cc
-1, respectively.
Netlon. The Netlon discrete mesh elements were supplied by Netlon Ltd. (New Wellington, St. Blackburn, U.K.). The mesh is manufactured
from
extruded polypropylene and has a mass per unit area of 52 g m
-2. The filament thickness is 0.50 mm (vertical medial
diameter) and 0.48 mm (horizontal
medial diameter). The filaments are arranged in a grid, creating rectangular openings that are
6.7 by 7.1 mm. Each element is 100 by 50 mm.
Nike Reuse-A-Shoe Materials. The Nike Reuse-A-Shoe materials are the shredded remains of used athletic shoes. In the shredding
process, the
entire shoe is granulated before the components are separated by screening and floating and sinking in water.
The Reuse-A-Shoe materials currently
do not have a size specification. Their gradation is a result of passing granulated shoes through
a 16-mm screen in the primary granulator and a 19-mm
shaker screen.
The materials that make up a shoe vary substantially. Most shoes
have uppers, midsoles, and outsoles (Malloch, 1996). The most
prevalent materials in the upper shoe component are nylon, synthetic leather (polyester with polyurethane coating), leather, cotton,
polychloroprene
(neoprene sleeves), polyester, polyurethane open cell foam, and cellulose. The midsole contains polyurethane
and ethylene vinyl acetate and the
outsole contains styrene butadiene rubber, polybutadiene (synthetic rubber), and natural
rubber (Malloch, 1996).
Nike supplied two materials from the
Reuse-a-Shoe program for this study: Nike Lights and Nike Heavies. Samples of the materials
produced at the Wilsonville, WA, processing site were
taken on 6 Sep. 1996 by technicians working on the project (Malloch, 1996).
The Nike materials were analyzed by the technicians for
purity, density,
and gradation. The Nike Lights contained 740 g kg
-1 uppers, 230 g kg
-1 midsole, and 30 g kg
-1 outsole. The
Nike Heavies contained 150 g kg
-1 uppers,
510 g kg
-1
midsole,
and 340 g kg
-1
outsole.
The compressed and uncompressed densities of the Reuse-a-Shoe
materials were measured to make acomparison with the Shredded Carpet used in this study. The uncompressed density of each
material was determined by weighing loosely placed
samples in a 1000-mL cylinder. A compressed density was measured by applying
a 1-kg weight to each material in the 1000-mL cylinder. The
compressed and uncompressed densities of the Nike Lights were 0.107 and 0.053 g cc
-1, respectively. The compressed and uncompressed
densities
of the Nike Heavies were 0.244 and 0.200 g cc-1
, respectively.
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Turfgrids. Turfgrids is a commercially available, polypropylene fiber reinforcing material manufactured by Synthetic Industries,
Inc. (Chattanooga, TN).
It is 99.4% polypropylene and individual fibers are 38-mm long and 5-mm wide. Each individual fiber is
fibrillated to form a net-like structure of finer
fibers (fibrils). When mixed with soil, each fiber expands and the net-like configuration
of fine fibers is randomly-oriented throughout the root zone.
Horizontally Placed Fabrics Sportgrass. Sportgrass is a commercially available product manufactured
by Sportgrass, Inc. (McLean, VA). Sportgrass consists of a polypropylene
woven backing with 24 yarn strand ends per 25.4 mm in the lineal direction and 11 yarn strand ends per 25.4 mm in width. Yarn
strands are 11 000
denier (1.0 denier is equal to the fineness of a yarn weighing 1.0 g for each 9000 m). The woven backing
is tufted with fibrillated polypropylene tufts. In
the lineal direction there are 16 tufts per 102 mm. In width, the tufts
are 9.5 mm apart. The pile height is 32 mm. The individual tufts
form a net-like
configuration when expanded. A fibrillated tuft is 6700 denier (W. Cook, 1998, personal communication).
Treatment Rates Treatment rates of reinforcing materials were based on industry
recommendations, previous research, and preliminary lab tests.
The preliminary
laboratory tests included mixing different rates of reinforcing materials (except Sportgrass) with the sand and
peat mixture used in the main field study.
The root zone was mixed on a volume basis using nine parts sand to one part sphagnum
peat. Two hundred-millimeter-diameter polyvinyl chloride pipe
was filled 150-mm deep with each mixture and compacted with a Proctor Hammer (American Society for Testing and Materials, 1999).
Bulk density,
total porosity, aeration porosity, and capillary porosity were determined for each mixture using a
tension table and methods similar to those listed in
American Society for Testing and Materials (1997). Two rates were chosen
for Netlon and Turfgrids; 3 and 5 g kg
-1. The 3 g kg
-1 rate
of reinforcements
for the Netlon and Turfgrids were based on standard industry recommendations for sports fields (Netlon
Advanced Turf, Blackburn, UK; and Synthetic
Industries, Chattanooga, TN). The 5 g kg
-1 rate for both of these products is considered
high for sports fields and is primarily recommended for turfgrass
horse racing track installations. Rates exceeding 5 g kg-1
were not used in this study because of the difficulty in maintaining
a homogenous blend of
sand root zone and reinforcing material in preliminary studies.
Preliminary studies indicated that the DuPont Shredded Carpet
could be mixed
effectively at rates up to 30 g kg-1
. Nike Lights and Nike Heavies treatments could be mixed at rates higher than
30 g kg
-1, but due to a lack of available
material and to make a rate comparison with the DuPont Shredded Carpet 30 g kg
-1, the 30 g kg
-1 rates were chosen. Since little data exists for
the
DuPont Shredded Carpet, four rates were chosen. The rates were 5, 10, 20, and 30 g kg
-1.
Plot Construction Field plots were established at the Joseph Valentine Turfgrass
Research Center in University Park, PA, in September of 1995.
The plot area consisted
of an underdrained gravel layer, 150-mm deep, overlaid by a 65-mm intermediate layer. A 100-mm layer
of the sand and sphagnum root zone mix
that was used during
the preliminary testing was installed over the intermediate
layer. The mix was donated by the Fertl-Soil Company, Kennett
Square,PA (Table 1).
A grid of 3.05- by 3.05-m treatment plots was laid over the
level root zone mix. A 300-mm border surrounded each treatment
plot. The
experimental design was a split block (blocks split by three levels of wear) with 12 treatments and three blocks.
All of the treatments (with the exception
of Sportgrass) were weighed and mixed with the root zone mix using a front–end
loader on an asphalt mixing pad. The sand was saturated with
water
during mixing. Wooden frames, 3.05 m by 3.05 m by 150 mm high, were placed on each treatment plot and leveled using
a transit. After filling the
frames with the mixed root zone treatments and allowing the mixture to drain, the surface was
leveled by raking and hand tamping.
The Netlon
treatments were filled to within 15 mm of the surface and 15 mm of the unarmended root zone mix was placed on the surface
of the Netlon/root zone
mixture as per industry recommendations. For the Sportgrass treatment, frames were installed and filled
with the root zone mix to within 25 mm of the
top. The Sportgrass was then cut to fit the frames. Next, small amounts of the root
zone mix was applied over the surface and worked into the pile
with
brooms. The plots were watered and allowed to dry, then more of the mix was broomed into the pile. This process was
repeated until 3 mm of pile
protruded above the settled mix. After the borders were filled with root zone mix, the frames
were removed and plots were seeded with ‘SR 4200’
perennial ryegrass (Lolium perenne L.) at the rate of 200 kg ha
-1. Nutrients and water were applied as needed to prevent
nutritional deficiency and
drought stress. The plot area received five N applications equaling 50 kg N ha
-1 during each growing
season (April–October). The turf was mowed twice
per week with a reel mower at a height of 38 mm and clippings were not
collected in baskets.
Wear level treatments were applied with a Brinkman
Traffic Simulator (Cockerham and Brinkman, 1989). The Brinkman Traffic Simulator
weighs 410 kg and consists of a frame housing two 1.2-m-long
rollers. Each roller has steel dowels or spriggs (12.7-mm diam. by 12.7-mm length) welded to the outside of the rollers, at
an average of 150 dowels m
-
2. These dowels are the approximate
length and width of the cleats on the shoe of an American football
lineman at the collegiate level. The Brinkman
Traffic Simulator produces wear, compaction, and turf/soil lateral shear. The
drive thrust yielding lateral shear is produced by different
sprocket sizes
turning the rollers at unequal speeds. The Brinkman Traffic Simulator was pulled with a model 420 tractor (Steiner
Turf Equipment Inc., Dalton, OH)
equipped with a dual turf tire package. Blocks were split with three levels of wear. The wear levels were no-wear, medium-wear (three passes with theBrinkman Traffic
Simulator three times per week), and high-wear (five passes
three times per week). According to Cockerham and Brinkman (1989),
two passes of the Brinkman Traffic Simulator produces the equivalent number of cleat dents created at the 40-yard line during one
National Football
League game. Thus, 15 passes per week are equivalent to the cleat dents sustained from 7.5 games per week.
In 1996, wear began on 1 June and
ended on 17 October. In 1997, wear began on 2 June and ended 17 October. Typically, wear was
applied regardless of weather conditions or soil
water content. Numerous wear applications occurred when the soil water content
was at or near saturation. Occasionally, due to heavy precipitation
or
schedule conflicts, wear was not applied on the scheduled day. In these cases, wear was applied on the following day.
Data Collection The criteria used for comparing treatments were surface hardness,
soil bulk density, soil water content, and turfgrass density.
Surface hardness was
measured using a Clegg Impact Tester (Lafayette Instrument Company, Lafayette, IN) equipped with a 2.25-kg missile
and a drop height of 440 mm
(Rogers and Waddington, 1989). Impact attenuation, as measured by an accelerometer mounted on the
missile, was used to indicate surface hardness
and is reported as Gmax, which is the ratio of maximum negative acceleration
on impact in units of gravities to the acceleration due to gravity.
The
average of six hardness measurements taken in different locations on each subplot was used to represent the hardness
value of the subplot.
Soil bulk
density data were derived from measurements of soil total density and volumetric water content taken with a Troxler
3400-B Series surface moisture-
density gauge (Troxler Electronic Laboratories, Inc., Research Triangle Park, NC). The Troxler
Gauge uses neutron scattering simultaneously with ray
attenuation to measure the volumetric water content and total density of
the soil (Gardner, 1986). A 150-mm deep guide hole was created
in the soil
using a template and guide rod. A137
Cs source was then inserted into the hole to a depth of 150 mm. The amount
of photons emitted from the source
and reaching the receiver on the surface is a measure of total soil density. Soil bulk density is derived by subtracting the density due to water from thetotal soil density.
Because some reinforcing materials could influence water content
measurements, the Troxler Gauge was calibrated using a Tektronix
1502B time-domain reflectometry (TDR) unit (Tektronix, Inc., Beaverton, OR). To calibrate the Troxler Gauge, water contents
were determined from
each treatment plot, using both the TDR and the Troxler Gauge, on six different occasions to provide
a range of soil water contents. Linear
relationships between the two methods for each reinforcement treatment were evident,
with regression coefficients greater than 0.90).
All water content
values reported in this experiment were collected using the Troxler gauge and then adjusted using the appropriate
regression equation. The values
represent the water content in the surface 150 mm of root zone mix. The adjusted soil water
contents were used to calculate the density due to water
which was subtracted from total density to provide soil bulk density.
Turfgrass density was rated visually and served as an estimate
of number of tillers
per unit area. Density was rated using a scale of 0 to 5 with half units. A plot with no turfgrass
present is rated as 0, and 5 indicates maximum possible
tiller density.
The turfgrass density ratings and the means of the three soil
bulk densities, three soil water contents, and six surface hardness
measurements were analyzed using analysis of variance and Fisher's least significant difference test at the 0.05 level. A LSD was
not calculated when
the F ratio was not significant at the 0.05 level.
Surface Hardness Significant treatment differences for surface hardness were
found on each rating date. Surface hardness of plots
generally increased with increasing
wear levels in both years of the study. Although surface hardness for medium
and high-wear treatments was significantly greater than for
no-wear
treatments on all evaluation dates, actual Gmax values did not differ by >10 units on any date. Surface hardness also
increased as each season
progressed for wear and no-wear treatments. When surface hardness data were averaged across all wear levels,
differences were detected among
reinforcing materials. Generally, surface hardness differences among reinforcing material treatments were greater than differences among wear
treatments. The range of Gmax values for reinforcing material treatments exceeded 20 Gmax units on all rating dates.
Sportgrass had higher surface
hardness values than all other treatments on four of six rating dates and ranged between 28
and 37% higher in surface hardness than the control on
each rating dates. Both rates of Turfgrids and Netlon produced
higher surface hardness values than the control on all rating
dates. When averaged
across all rating dates, the low rates of Netlon and Turfgrids increased surface hardness by 13 and
14%, respectively, when compared with the control,
while the high rates increased surface hardness by an average of 22 and
24%, respectively.
DuPont Shredded Carpet and both Nike treatments usually
produced lower surface hardness values than Sportgrass, Netlon, and Turfgrids. Surface hardness generally decreased as rates of
DuPont Shredded
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Carpet increased from 5 to 30 g kg-1
. When averaged across all rating dates, the 30 g kg
-1 rates of DuPont Shredded
Carpet and Nike Lights produced
surface hardness values that were 10.5 and 12.5% lower than the control, respectively.
Reinforcing material treatment x wear interactions occurred
on
18 Oct. 1996 and on all rating dates in 1997. The interactions indicate that the surface hardness values of some treatments were more strongly
influenced by wear than others. In the case of Sportgrass, surface hardness values for
the high-wear level ranged between 16.5 and 25.4% higher than
the no-wear level on each rating date. Sportgrass consistently measured higher in surface hardness than all other treatments
after wear was applied.
Whereas under no-wear, Sportgrass had surface hardness values similar to the 5 g kg
-1 rates of Netlon
and Turfgrids. DuPont Shredded Carpet 30 g
kg-1
and both Nike treatments responded differently to increasing wear than Sportgrass.
For these treatments, the surface hardness values for the high-
wear level were only 5% higher than the no-wear level when averaged
across all rating dates.
Soil Bulk Density No significant wear x reinforcing material interactions were
detected for bulk density on any of the rating dates in this
study. Bulk density increased with
increasing wear
levels in 1996 and 1997. Also, soil bulk density generally
increased for all wear levels as each growing season progressed.
Soil bulkdensity values ranged from a low of 1.35 g cc
-1 for
the no-wear treatment on 11 June 1997 to 1.47 g cc
-1 for the
high-wear treatment on 15 Oct. 1997.
Increases in bulk density on no-wear plots were presumably due to routine maintenance and foot traffic during data collection.
The drop in bulk
densities for all treatments between 18 Oct. 1996 to 11 June 1997 was likely due to freeze-thaw cycles during
the winter months.
Soil bulk density
values averaged across wear levels revealed differences among the reinforcing material treatments.
The range of bulk density values among
reinforcing material treatments was similar to the range for wear treatments (1.34
g cc
-1 for Nike Lights 30 g kg
-1 on 11 June 1997 to 1.47 g cc
-1for
Netlon 5 g kg-1
on 18 Oct. 1996). The 5 g kg
-1 Netlon treatment produced higher bulk density values
than the control plots on five of six rating dates.
This treatment generally produced higher bulk density values than Sportgrass;
the 10, 20, and 30 g kg
-1 rates of DuPont Shredded Carpet; Nike
Lights
and Heavies; and the 3 g kg-1
rate of Turfgrids. The 3 g kg
-1 Netlon treatment and 3 g kg
-1 Turfgrids treatment typically
did not influence bulk density
relative to the control. The 10, 20, and 30 g kg
-1 rates of DuPont Shredded Carpet lowered
soil bulk density relative to the control on five of six rating
dates. The 5 g kg-1
rate of shredded carpet had no affect on soil bulk density on four of six rating dates. This treatment
resulted in a soil bulk density
that was higher than the control on 23 Aug. 1996 and lower than the control on 15 Oct. 1997.
As with surface hardness, bulk density generally
decreased with increasing rates of DuPont Shredded Carpet. Nike Lights and
Nike Heavies treatments also lowered bulk densities relative
to the control
on five of six rating dates.
Soil Water Content No reinforcing material treatment x wear interactions occurred
in this study with respect to soil water content.
Differences in soil water content were
found among wear levels on four of six rating dates. When differences occurred,
water contents were higher in no-wear and medium-wear treatments
than in high-wear treatments. However, the differences were slight, with an overall variation of only 0.05 m m
-3 across
the duration of the study.
Soil
water contents differed among reinforcing material treatments during both years of the study. Nike Lights 30 g kg-1 and Sportgrass had lower soil watercontents than the control
on five of six rating dates. No other reinforcing material treatment
had a soil water content lower than the control on more than
two of the six rating dates. The only treatments which measured higher in soil water content than the control were Turfgrids
3 g kg
-1 on three rating
dates and all four rates of DuPont Shredded Carpet on one or two rating dates. The range in water
contents during both years of the study was
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The Sportgrass treatment produced the highest surface hardness of any treatment in this test. Surface hardness for this treatment
increased
substantially as wear level increased and as each season progressed. Surface hardness did not appear to be related
to soil bulk density, as there were
no differences in bulk density between the Sportgrass treatment and the control.
The increased surface hardness of the Sportgrass treatment may
have
been the result of an increase in soil strength near the root zone surface. Horizontally-oriented fabrics at or near
the soil surface have dramatically
increased soil strength and load carrying capacity (Gray and Al-Refeai, 1986). Increased
soil surface strength typically results in a higher surface
hardness (Waddington, 1992). The Sportgrass treatment showed a consistent reduction in soil
water content compared with the control throughout the
study. Dryer soil conditions produced by Sportgrass may have resulted
in slightly higher surface hardness. However, the moisture differences
between
the Sportgrass treatment and the control were only 0.02 to 0.03 m m
-3, and probably not enough to account for the large
differences in surface
hardness.
CONCLUSIONS Overall, the greatest impact of reinforcing materials subjected to different wear levels in a sand root zone was on surface hardness. This is potentiallysignificant because increased
surface hardness of an athletic field results in a greater risk
of athlete injury in the event of a fall (Baker and Canaway,
1993). Conclusions and recommendations based on surface hardness
data from the present study are difficult to formulate because
no recognized
standards currently exist for acceptable surface hardness values of athletic fields as measured by the Clegg
Impact Tester. In an attempt to relate
surface hardness to athlete performance and safety, Canaway et al. (1990) correlated athletic
field surface hardness measurements with athlete's
perceptions of surface hardness. On the basis of hardness values obtained
with the Clegg Impact Tester and a 0.5-kg missle, Canaway et al. (1990)
suggested a preferred upper limit of 80 Gmax. A 2.25-kg missile was used in the present study and has been shown to
produce lower Gmax values
compared with the 0.5-kg missile (Rogers and Waddington, 1990). Rogers and Waddington (1990) reported
that the 0.5-kg missile will typically record
Gmax values that are 24 to 50 units higher than values produced by the 2.25-kg
missile. Using this comparison, Sportgrass, Netlon 5 g kg
-1, and
Turfgrids 5 g kg-1
reinforcing material treatments resulted in hardness values that were probably greater than the preferred
upper limit suggested by
Canaway et al. (1990). Athletic field managers considering the use of soil reinforcing
materials should be aware that if a field is exposed to high
wear,
Netlon and Turfgrids at the 5 g kg-1
rate and Sportgrass have the potential to exceed the preferred upper surface hardness
limit suggested by Canaway
et al. (1990). The high rates of DuPont Shredded Carpet and Nike Lights consistently resulted
in surface hardness values lower than the control, even
under high wear, and may be less likely to result in athlete injury
during player/surface impacts.
REFERENCES• American Society for Testing and Materials. 1997. Annual Book of ASTM Standards. Vol. 15.07. End Use Products. Standard test method for
saturated hydraulic conductivity, water retention, porosity, particle density, and bulk density of putting green and sports turf rootzone mixes.F1815–97. ASTM, West Conshohocken, PA.
• American Society for Testing and Materials. 1998. Annual Book of ASTM Standards. Vol. 15.07. End Use Products. Standard test method fororganic matter content of putting green and sports turf rootzone mixes. F1647–98. ASTM, West Conshohocken, PA.
• American Society for Testing and Materials. 1999. Annual Book of ASTM Standards. Vol. 4.08. Soil and Rock. Test method for laboratorycompaction characteristics of soil using standard effort. D698–91. ASTM, West Conshohocken, PA.
• Baker, S.W. 1991. Temporal variation of selected mechanical properties of natural turf football pitches. J. Sports Turf Res. Inst. 67:83–92.
• Baker, S.W. 1997. The reinforcement of turfgrass areas using plastic and other synthetic materials: A review. Int. Turf. Soc. Res. J. 8:3–13.
• Baker, S.W., and P.M. Canaway. 1993. Concepts of playing quality: Criteria and measurement. Int. Turf. Soc. Res. J. 7:172–181.
• Baker, S.W., and C.W. Richards. 1995. The effect of fibre reinforcement on the quality of sand rootzones used for winter games pitches. J. SportsTurf Res. Inst. 71:107–117.
• Beard, J.B., and S.I. Sifers. 1993. Stabilization and enhancement of sand-modified rootzones for high traffic sports turfs with mesh elements. Arandomly interlocking me
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