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Artificial turf surfaces: Environmental compatibility as per DIN 18035

Commentary on the revised DIN standard from authorised expert H-J. Kolitzus

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Artificial turf surfaces: Environmental compatibility as per DIN 18035

Commentary on the revised DIN standard from authorised expert H-J. Kolitzus

In the past, environmental compatibility of artificial turf surfaces was tested according to the two DIN standards, DIN V 18035-6:2004 or DIN V 18035-7:2002. Both standards were withdrawn following a directive from the European commission which applied in particular to the highly contested DIN SPEC 18035-7:2011. The sole valid standard applying to artificial turf surfaces is EN 15330-1:2013. (For synthetic surfaces it is EN 14877:2013.) As these EN standards only contain details about the actual surfaces however, DIN 18035-7:2013 and DIN 18035-6:2013 were revised and reissued (the final new version of DIN 18035-7 will be pub-lished mid 2014; from DIN 18035-6 only the version currently available is a draft version da-ting from 2013). These standards now only apply to aspects of the substrate; only the tests for environmental compatibility (EC) remain unchanged.

The EC tests have been clarified in some important points in that firstly, the nitrification inhibitor test and secondly, elution in CO2 acidulated water have been eliminated. The nitrification tests proved to be questionable and elution in acidulated water to be excessive. In addition, the elution tests were limited to 24 hours which led automatically to higher elution values. Apart from the evaluation criteria for the DOC content however, the evaluation criteria have been left more or less as they were previously when they applied to the 48- hour elution – a rather haphazard approach. Determination of phthalates and chloroparaffins has been added as parameters to be observed. This appears to be superfluous as no standard or guide values are given and tests in the past have shown that there is no necessity for action in this regard in sports field construction as these materials are practically never found in sports sur-faces (this should not be taken to mean that they are insignificant).

It is important that evaluation of environmental compatibility is now only given as a recommendation ("Appendix B, Environmental recommendations"): Paragraph 4.12 "The effects of an artificial turf system on the ground and ground water are dealt with in the informative appendix B". This careful formulation leads us to imagine that the process is still unsupported.

The table with the environmental recommendations is valid to the same extent for elastic layers, artificial turf surfaces and filler material. It is astonishing that the same evaluation criteria should be valid without differentiation for all the components!

While the process for artificial turf surfaces and filler material can be carried out to a great extent analogue the old method (2002 or 2004), something new has been introduced for testing of elastic layers. Instead of cutting these layers into cubes, sealing the cut edges with a PUR adhesive cement and subjecting the cubes to an elution test, drill cores (diameter 8 – 10 cm) must now be cut from the elastic layers and exposed to a through-flow in a cylinder – a complete change of paradigm: from the elution to cylinder method.

Astonishingly, the standard runs out of steam after the first paragraph (7.8.1). It should be determined how much water must flow how often through the sample or for how long a time (contact time) etc. This situation also demands a complete revision of the evaluation criteria. It can be heard from well-informed experts that the DIN technical committee has manoeuvred itself into a blind alley. This can be seen most clearly in the test for water impermeable synthetic surfaces: How can a through-flow be created here? For this reason, the German federal institute for sport science has allocated a research task to the BAM (federal German research institute), the findings of which are expected for autumn 2014. From experience it is expected that it will take at least two years for findings of practical use to develop from this.

This means that testing of elastic layers cannot be carried out according to the new DIN 18035-7:2014. But how then? Especially as it is a requirement of many tenders. It is probably not otherwise possible than in general to use the old method (2002 or 2004). This applies to the manufacture of cubes and sealing of the cut edges with PUR adhesive cement. The elution itself is, on the other hand, carried out in non-acidulated water for 24 hours and the results evaluated according to the environmental recommendations of DIN 18035-7:2014. It remains a secret of the testing laboratory however, as to how elastic supporting layers (i.e. elastic layers with mineral grains) should be tested in an elution or cylinder method. These supplementary comments also apply to the certification programme "artificial turf surfaces" and "synthetic surfaces" from DIN Certco, which preceded the new DIN 18035-6 and -7, unfortunately also with the drawbacks.
(http://www.dincertco.de/media/dincertco/dokumente_1/zertifizierungsprogramme/Kunststoffrasenflaechen_Zertifizierungsprogramm.pdf) (in German).

For some time, the environmental compatibility concept was a German-Swiss joint venture (from the mid 1990s). In 2007, the topic underwent a critical examination in Switzerland and completely different results were obtained. Large-scale outdoor tests were carried out with different surface systems installed complete with substrate in a so-called Lysimeter (diameter 1m) and exposed to natural rain irrigation. The water which permeated through the surfaces was collected and analysed. It was found that the elution method is a haphazard method which has no relevance in practical use and that the drainage water only contained trace quantities of critical substances. In any case, practically no zinc was determined. As a result, the elution method was abandoned and regulations regarding environmental relevance reduced to a minimum (publications from the Swiss Federal Office for Sport (Bundesamt für Sport, BASPO) nos. 112 and 113, 2008). This was not even discussed by the DIN technical committee.

The Swiss approach was taken up in CEN TG 217 "Sports flooring". In a special work group it was discussed how outdoor examinations can be reproduced under laboratory conditions. Unfortunately, in the meantime no progress has been achieved on this topic.

It is perhaps of interest, how the environmental compatibility concept a la DIN 18035 came about. The author was personally involved in the creation of the environmental compatibility concept in the early 1980s. Due to unpleasant reports of toxic content in mineral sports field surfaces (clay surfaces) in the 1960s and 70s (arsenic in ash or rotgrand surfaces), the then Balsam Company had a large number of different synthetic surfaces tested by the city of Bielefeld to determine their contents using the elution method. The results of these tests showed which elutable substances (mainly heavy metals) were to be expected in which bandwidth. The reference values at this time practically marked out the bandwidths.
It had been discovered in Switzerland in the 1980s that run-off rain water from synthetic surfaces had a very low surface tension (foam formation in draining channels) and contained large quantities of mercury. Both approaches were discussed and compared in depth leading to parallel guidelines being drawn up. Unhappily, from the Swiss side, the disastrous nitrification inhibitor method was introduced as measuring method for the toxic potential of the eluates.

In this way, the reference values at that time were pragmatically/statistically determined guide values, which made it possible to see whether a product had unusual properties and if a more detailed examination was necessary. Over the years, the origins of the environmental compatibility test were forgotten and the process took on "a life of its own" in that guide values / evaluation criteria given in earlier standards (2002 and 2004) mutated to "limiting values" without any factual basis.

[Note: Determination of EOX (extractable organic halogen compounds) is questioned by independent experts. Which surfaces are extracted for hours in hexane? It would be much more sensible to carry out a GC-MS screening with the goal of identifying critical plasticisers, PAH (polycyclic aromatic hydrocarbons) etc. Currently, these are only ideas which still need to be implemented into a practicable guideline.]

One justification for cementation of the method was found in the assertion that sports fields surfaces fall under soil protection laws. As a result, the elution of zinc was often considered to be critical. It cannot be accepted however, that the few milligrams of zinc obtained over a long period of use of a sports surface from drainage water should be considered critical when compared to the thousands of tons of rubber dust from car tires which is distributed year for year into the atmosphere. Taking into account the large relative surface area of this rubber dust it releases much more zinc than the grained or fibre-like rubber additives in sports surfaces.

The environmental experts in the DIN committee have yet to demonstrate why sports surfaces should fall under the soil protection laws. When this directive should already be valid, why is §2, paragraph 2.2 ignored? Here, a zinc quantity of 1200g/ha and year is allowed, i.e. 120 mg/m2 and year. When converted to the m2 artificial turf surface with rd. 5kg rubber filler material, an elution quantity of 0.5mg/l zinc in an elution test represents a total amount of 25 mg/m2.

Finally it can be asked why environmental compatibility needs to be regulated at all in a sport-technical standard. For technical standard reasons different facts should be coded separately to prevent all other technical fields being affected when changes are made which only apply to one particular technical field. No public task exists and it cannot be accepted that in this regard, inexperienced planners and administrative authorities can decide on this topic. Environmental protection is the task of the responsible expert authorities in each case and each case should be treated separately. Environmental protection also includes more as simply the substances contained in the surface material.

Dipl.-Ing. Hans-Jörg Kolitzus
publically appointed and authorised expert ret.
hjkolitzus@bluewin.ch

 

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