The discussion came up at my kids’ school of replacing some more of the blacktop with greenspace. The idea is to fundraise and write grants to make it happen, as naturally there is no money for anything extra – at least not at most schools. This also means that there is no money for maintenance. If anything needs cutting, it will likely have to be done by volunteers. In addition, living west of the Cascades where rains are commonplace during the colder months, many grass fields turn into veritable mud pits. So, not unexpectedly, the idea of shooting for the installation an artificial turf field emerged.
Being a perpetual skeptic and a bonafide tree hugger, I immediately cringed. Somewhere from the annals of my beleaguered brain, articles about heatstroke, burns, landfill problems, and other pleasantries associated with synthetic turf started to float to the surface. I decided to refresh…
First, let’s review a couple of basic concepts. Do you know what the ‘Heat Island Effect’ is? It is a thermal phenomenon, where the abundance of hard, impermeable surfaces in urban areas absorb heat during the day, and radiates it back into the atmosphere at night. The more hard, artificial surfaces we have, the higher the radiated temperature will be. This means, in larger cities, the temperature can rise as much as 6-10 ° F, compared to that of the surrounding countryside. At its worst, in exceptionally large paved areas, this phenomenon has been known to alter local weather patterns.
The other important concept is something called ‘evapotranspiration’. Plants have a high water content, which gives them an ability to balance temperature similar to that of large expanses of water. Through the process, the plants will return moisture to the atmosphere and subsequently cool the air around them. In essence, plants serve as great modulators of temperature.
Synthetic fields – although not impermeable – add to the Heat Island Effect. In fact, as you can see here, they become far hotter than asphalt! (This site will also give you a good cost breakdown of various options.) The average synthetic field has a 6-10” sub-base of chipped rock to enable drainage. On top of this rests two inches or so of fine granulated recycled rubber tires, usually mixed with sand, and then the “grass” layer. On a day where air temperatures reach 94°F , the rubber field becomes a scorching 165°F. On really hot days, temperatures of up to 200°F have been reached! People have gotten heat blisters on their feet by being on these hot surfaces, and as you can imagine, the risk for heat stroke is greatly increased. Attempts have been made to cool fields off by spraying them with water. The effect is very temporary, and essentially a waste of water, as temperatures return to the original high within minutes. Of course, having to do this negates any ideas of synthetic fields being water savers. They are not – they need to be both cooled on warm days and cleaned – at least once in a while. Because artificial fields require water for their maintenance, even interior fields need a built-in functioning drainage system, or it will have puddling problems. A good drainage system usually amounts to about 2/3 of the field’s installation cost.
Regular grass breaks down bacteria through natural processes, and regenerates itself. This regeneration is, obviously, the main reason for its long-standing maintenance costs. It needs to be cut! Every gardener knows that cuttings left on top of the lawn will quickly break down and add instant nutrients to the soil, in a cycle of rejuvenation beneficial to all living creatures. Artificial turf on the other hand, can’t do that. It requires pesticides and disinfectants to eliminate algae, bacteria and mold. It is treated with silver-based antimicrobial components that are deemed totally safe to both birds and mammals – as long as it is surrounded by air. Different story when it gets wet – silver sodiumhydrogen zirconium phosphates are very toxic in aquatic environments.
The leaves of synthetic grass are often made of polyethylene or nylon, which in the grand scheme of things is usually not so bad – except in those cases where lead has been discovered to have been a component. The cushiony layer is far worse. In recycled rubber, espcially in that from tires, you will find a veritable smorgasboard of unsavory substances. Varying levels of aluminum, cadmium, lead, chromium, copper, iron, magnesium, manganese, molybdenum, selenium, sulfur, and zinc, to name a few of the most common. These, along with all the disinfectants and pesticides used for cleaning, will continue leaching into the groundwater long after the field is no longer in use. This is the exact opposite of what a regular grass field does, as it acts as a filtration system to the percolating water, seeping back into the ground. In addition, as the synthetics of older fields break down from weathering and use, dust and particulates will invariably be kicked up and inhaled and absorbed by its users. According to the CDC, it is difficult, if not impossible, to adequately measure how much of those particulates go into the body.
So, other than burns, increased risk for heat stroke, and chemical exposure, are there other health implications of synthetic fields? Astroturf and similar products have less “give” than regular lawns, so there is an increase in injuries like “turf toe”. As it is also more like a carpet than a lawn, rug burns tend to be more serious than on grass, as the distance you tend to slide during a fall, is farther on artificial surfaces. In addition, the allergen latex is a component of rubber. An estimated minimum of 6% of our population is allergic to latex. A counter argument might of course be that many are also allergic to pollen. If lack of maintenance budgets leaves the grass uncut (which is likely, given this year’s $22 million state budget cuts for Portland schools), this might become an issue as well.
The average useful life of a synthetic layer of turf grass is 8-10 years. After that, it needs to be switched out, at costs quite prohibitive for most elementary schools. Of course, those will be 8-10 years of year-round green coverage. Once a field is decommissioned, it will all end up in landfill. As part of its normal cycles, regular grass will at some point go dormant, and offer a more seasonally dictated usability, as eveyone who has seen their kids come home covered in mud will testify. The premium natural grass sports fields have a base consisting of mostly sand to enable rapid drainage, not natural top soil as in most other places.
There have been great advances made in the development of grass seeds. There are now varieties available with extraordinarily long roots, developed to resist drought, and minimize water use. Still, installing a sand-based grass field, of course, costs serious money. And, given our dry Oregon summers, using even the optimal seed variety will demand water and maintenance during the year, as well as over summer break. This is never more evident than when looking down our street during the heat of August. Out of those who still have grass patches adorning their front yards, only that of my dear neighbor’s is still green. The lawn of this old lady is her pride and joy, as evident by it’s edged and manicured emerald green glow. I have to give her credit, though. In an attempt to save our water supply, she hasn’t watered it as much in recent years, and she recently did away with her hell strip. But I know it pains her to see the inevitable patches of yellow emerge…
Interestingly, very few of the types of grasses we commonly use for lawns and athletic fields, are native to North America. Per this fascinating article from the New Yorker, documenting the American obsession with lawns: “Kentucky bluegrass comes from Europe and northern Asia, Bermuda grass from Africa, and Zoysia grass from East Asia.” Usually, the “ideal” grass seed for each region consists of a mix of seed types. If you find that you really can’t live without a lawn, your best bet is to call your local university extension service, and ask what they recommend. Steer clear of the ubiquitous “Contractor’s Mix” in the isles of the mega home improvement stores. It is very rarely the right kind for optimal results, regardless of where you are.
So considering perpetually low (no?) budgets – what can a community of families excited to greenify their luxuriously expansive, but mostly blacktopped school yard do? I think the answer lies in the unassuming, humble clover.
It may be a compromise, but there are a number of great aspects to clover that benefits our funding as well as our maintenance predicaments:
- It’s cheap – both to plant and to maintain. $5-10 for a bag large enough to cover the average yard.
- Relatively fast growing.
- Can be planted any time of year. In our case, we should probably shoot for six weeks prior to first frost. This way, roots can become firmly established, and survive relatively undisturbed during winter break, successfully setting it up for rapid coverage in early spring.
- Drought tolerant (meaning it stays green throughout the summer. In western Oregon, it is practically an evergreen.)
- Bullying enough to push out most weeds, so it is essentially pest-free.
- Needs no fertilization – in fact it pulls nitrogen from the air, and adds it to the soil, which improves it.
- Is self-aerating, which prevents soil compaction.
- Attracts beneficial insects like honey bees. If some students are allergic to bee stings, the clover should be mowed when it is about to flower, as this is when the bees will come.
- Low growing and rarely needs mowing.
- Is impervious to, and will not develop yellow spots from peeing dogs.
- It is cool and soft to walk on, although it doesn’t have the best track record for heavy use. Perhaps for optimal results to stand up extensive exposure to running feet, a clover/grass mix would be more appropriate. I think a call to the OSU Extension Service might be in order, to see what would be the ideal combination.
Through this process, I was recently made aware of a great non-profit here in Portland called Depave. (Thank you, Amy!) I think our best bet is to try to reach out to them for help and advice in how best to tackle our blacktop. Not to mention what a great community builder it would be! In the meantime, check out their website and get inspired!