Most of your points are correct except I take issue with the statement that temperatures are elevated on turf 4′ above the surface. Tests by the engineering firm Milone and MacBroom in CT showed that while the temperature on the surface itself was elevated vs. ambient temperature by 15-25 degrees, it was only 1-2 degrees hotter at 5′. (I can send this study to you by email if you want it). This height of course is what sports medicine experts consider in terms of player safety, not the surface temperature. From this standpoint, most experienced trainers with turf fields do not see a health safety issue. Moreover, the temperature-humidity index on turf at this height is often equivalent to that on grass simply because the humidity at this level on a grass field is generally higher.
However, the surface of the turf IS hotter so this is not an issue that should not be addressed. A “spritz” of water before practice will reduce the heat of the surface by about 20 degrees immediately, so an irrigation system of some kind is great, although many, many (in fact, most) fields in the southwest do not have these systems and manage well. For an extra $40K, however, the cost to install the system is minimal on an $800,000 project. Very little water will be used because most of the time the surface will not be used when it is hot enough to water it and most of the year the irrigation will not be necessary. And again, little actual water needs to be put on the field–it is not like watering a grass field where the roots need to be watered.
