The City of Berkeley (COB) Gilman field project team presented their results. Here are highlights from each of the presenters:
A Shock Pad is Recommended for Turf Fields to Reduce Injuries
Wesley Bexton, Carducci Associates:
The main take away: a shock pad is recommended for all of the infill types. A shock pad would last for 16 years, i.e. two field renovation cycles. Shock pads help reduce knee, ankle, foot, and toe injuries, and head-to-ground concussions. Gmax ratings measure the hardness of the surface of fields. Natural turf has a Gmax rating of 78 to 115. The synthetic turf industry guideline is for a Gmax rating is under 165. Fields with crumb rubber infill and no shock pad have ratings over 165. When the Gmax rating exceeds 200, fields should be closed. He stated that the field is the safety equipment for soccer players.
(The turf fields at Gilman do not currently have shock pads.)
Crumb Rubber From Tire Waste Manufactured in China Has Substantially Higher Toxicity Levels
David Teeter, Millennium Consulting Associates:
When consultants work in the realm of environmental risks and public health, they attempt to quantify those risks in terms of the likelihood of negative outcomes due to exposure. The two most dangerous carcinogens in crumb rubber are arsenic and PAH benzoin pyrene. Acceptable risk is defined as the range of probabilities between 1 in 100,000 and 1 in 1,000,000. Crumb rubber risk is estimated at 7 in 10,000,000, which is less than 1 in 1,000,000, and is therefore deemed an acceptable risk. Increasingly, **crumb rubber from tires manufactured in China with higher toxicity levels have been incorporated into the crumb rubber supply in the US. This crumb rubber falls under the not acceptable risk range, and it’s not feasible to exclude it from the mix.
(**We, Safe Gilman Turf Coordinators, think this is a strong argument against another field with crumb rubber!)
The consultants to the City of Berkeley presented three field options, with definitive budget numbers due shortly:
- cork field with shock pad
- crumb rubber with shock pad
- crumb rubber without shock pad
Cork and Coconut infill material (corkonut) is not being considered, as it would cost substantially more, partly due to an irrigation system needed. Additionally, the non-organic corkonut has a higher metal content due to pesticides used. GreenPlay corkonut is organic, therefore we found out that it does not have the higher metal content.