Soil Sealing: it's not what it sounds like

Soil may be sealed, but my lips are not!

Nov 05, 2021

As you may know, I recently built a home with my fiancé, James, in a new development in east Austin, TX. In case you want to google it later, and at the risk of one of you finding where I live and murdering me in my sleep, the community is called Whisper Valley.

I really didn’t like the idea of a master planned community, for all the reasons you’d think – why excavate land when we could fix up an existing home?

But 2 key things drove this decision:

Vision – Whisper Valley is the first ever master planned community to be developed with a geothermal grid. That is, heating and cooling provided without noisy condensers, at 400% better efficiency than conventional heat pumps. Seeing as that’s a pretty progressive thing to do, they went ahead and threw in solar panels, EV plugs, and energy-efficient appliances and marketed it as a sustainable community and at the time (pre-pandemic buyer), it was affordable to boot! Our sustainably-minded egos were very impressed!
Pricing – why can it be SO much cheaper to build a brand new home, on untouched land, compared to buying a moldy fixer-upper in town? (if you stick around, I investigate the economics of this…)

Anyway, now I do things like poke at our lumpy sod, observe the bajillion spiders on our property that have no prey around to eat them, and sit on the back porch watching the next phase develop. This experience gives a soil gal like me A LOT to think about and today I’m spilling!

I’ve been watching, with mixed emotions, as the brushy thicket is carved out of the landscape behind our home. All the vegetation that had once stood on the surface of the hill and valley was shredded and carted off by truckloads. The surface was then graded (or was it “grated”…🧀😣) with the zaniest looking, earth-moving machinery I’ve ever seen. And THEN the craziest thing of all happened: new soil was brought in. Where did it come from? Where did all the other stuff go?

All of this has me thinking on the cringey thing we really don’t want to talk about: how our infrastructure is built on soil, effectively sealing it off and eliminating its ability to provide benefits to our communities.

As I’ve been investigating the problem of soil sealing, I’ve been wondering: how bad is it? Are there good solutions? What can I personally do? Are there inspiring stories of unsealing land?!

First, some really boring vocabulary that will be used throughout these next couple posts:

How much land is actually sealed?

I found the EU has WAY more data and discussion on the topic of soil sealing than the U.S. I suppose that makes sense, seeing as European nations have both a longer history of sealing land, and less land in general to futz around with, making the topic more of a priority.

Here’s a few facts I found along the way to give an idea of how much land is actually sealed:

According to a geophysical report from 2004, impervious surfaces in the U.S. were estimated to cover more than 43,000 sq. miles, or roughly the size of Ohio 1
In 2017, a report called “2100 Project: An Atlas for the Green New Deal” published an estimated 2% of U.S. land use can be attributed to urban areas 2
As for the EU, a 2011 study estimated 4.4% of the total surface area of the 27 member states was considered covered by artificial surfaces, 51% of which were impervious 3. And from 2000 – 2006 such coverage increased by 3%, while the population increased by 2% 4

On the one hand, such small percentages don’t sound so bad! But then you think about the fact that it’s all so spread out. And, oh my goodness, the roads… there are so many of them splicing land up, and the green spaces they cut through are in large part, disturbed soil systems themselves in the form of agriculture. Oh, and then there’s the fact that, at least here in the states, we are by no means slowing down on paving paradise:

According to a Bloomberg report, “the US is becoming more urban - at an average rate of about 1 million additional acres a year. That’s the equivalent of adding new urban area the size of Los Angeles, Houston and Phoenix combined. US urban areas have more than quadrupled since 1945.” 5

In Germany, per a 2010 report, 77ha (or 190 acres) of land-take was occurring daily! 6

That’s mind boggling.

Why is land-take so pervasive?

In short, there’s a lot of cultural and economic factors playing into urban sprawl.

For one, it can be more expensive in many ways to repair an existing building than to build a new one on a fresh foundation. As one early 2000’s study on Memphis points out, this creates inequity, as “all residents tend to finance, through their taxes, new suburban subdivisions, but urban residents in need of social services find it difficult to access the best new ex-urban facilities and services.” 7. Oof, sprinkle on some white flight and we’ve got ourselves a topsy-turvy dynamic, manifesting itself as sprawl and social injustice.

From what I can tell, all this land-take business really boils down to land prices, and the perceived value of various types of property.

Urban properties are often either valued so high it pushes people out of the market, or perceived to not be worth the investment to restore, especially in underserved communities - an endless cycle that breeds more poverty.

Meanwhile, undeveloped land prices tend to be relatively cheap, because poorly managed farmland is either rightfully valued low or properly managed farmland is wrongfully undervalued in an industry / government that rewards and protects mega-conventional farms.

Ok, but what to do about the soil?

This all sounds like a real pickle, because you and I both know we’re not going to stop paving roads or expanding our cities any time soon, but does that mean our soil systems, and the benefits they provide, are doomed? I don’t think so.

What I see when I look at the maps of sealed surfaces among all the other land-uses is potential. If we can transition our farms and ranches to better practices over time AND make some efforts in our cities, even among all the pavement, we could restore ecosystem services of soil in a big way.

Picture sourced from this awesome Bloomberg article by Dave Merrill and Lauren Leatherby, included in References section.

When I say ecosystem services I’m talking about 👏water absorption and filtration, 👏drought tolerance, 👏flood mitigation, 👏fire mitigation, 👏heat reduction in our city centers, and 👏overall carbon sequestration. These are real possibilities for us if we’re more thoughtful with the materials we use in our built environment, and the treatment of the ground beneath us during and most importantly, post-construction.

Below are a few of my ideas as I stand on my own scraped earth and stare out across freshly “grated” sprawl.

Reuse & Restore
I wish so badly the demolition crew could create a reserve of at least some of the mulched vegetation and top soil and redistribute it on lots prior to building. Maybe one day I’ll have what it takes to influence such processes, but for now you and I can keep this in mind when we’re moving earth for our own projects. If topsoil has to be removed and can’t immediately be repurposed, at the very least we can protect it with a mulch layer and prioritize planting in it as soon as possible – same goes for the area that’s been excavated.

Inoculate
When such a disturbance takes place, I’m imagining a world in which we inherently know to inoculate the soil and any plantings with beneficial biology and organic matter. If so many laymen generally understand what it means to eat yogurt and drink kombucha (i.e. eat and drink probiotics), we can also understand what it means to inoculate our land every now and then.
Plant
The more roots the better, I say! Shallow, deep, tap roots, hairy roots. They can all improve soil structure not just by physically anchoring soil, but most importantly by feeding organisms which are responsible for creating better and better soil structure over time – the kind that absorbs and retains water. Not to mention, the more vegetated a landscape, the cooler that location will feel during the dog days of summer.
Mulch
Most people I know mulch to protect their irrigation lines from drying out. If people only knew how much more mulch is doing for us! No soil should ever be left bare, ever. Maybe I’ll dedicate a whole post to the magic of mulch ✨
Permeable materials
This is low-hanging fruit, y’all. There are a myriad of ways to change the materials used in our built environment. More on this next post!
Policies
What if it was part of building inspections to ensure soil systems had been inoculated and mulched? What if developers, farmers, and homeowners alike were fined for leaving soil bare for a certain amount of time? What if remediation projects in existing urban areas were incentivized? What if there were policies that protect the value of undeveloped land in a way that economics currently isn’t? What if permeable materials were required for all new buildings and restoration projects?
Unsealing
From green roofs to putting the “park” in parking lot… the possibilities of “unsealing” neglected gray areas in our cities is chock full of joy and creativity. We’ll explore some inspiring examples next time!

I’ll leave you with this quote, that makes me do all the head nodding.

“Cities done well can be just what nature needs. ” — Eric W. Sanderson, Manahatta

What do you think? What experiences have you had relevant to sealing / unsealing soil (for lack of a better term!) Tell me things in the comments!

Andie