“I feel the earth move under my feet.” I see the snow tumbling down, tumbling down.
Unlike the romantic cause of this turmoil in Carol King’s song, my imbalance comes from a heaving of the ground around me.
This unevenness is a result of fluctuations to the ‘frost line’, the subterranean point below which soil does not freeze. This winter’s barrage of wet snow and ridiculously cold temperatures pushed this freezing point deeper than I can remember.
As water below the surface freezes and expands upward, everything is lifted out of the ground, fracturing existing stability. These actions are known as ‘frost heaves’.
The most common affect of frost heaves are roadway potholes. Resulting conditions this year also see concrete paver walkways buckle like roller-coasters, brick and stone patios bulge as if pregnant, and mortar joints in stone walls and steps pop as if crowbars were used to forcibly separate them.
Houses and other buildings are not affected by a deepening frost line. These permanent structures are built on solid concrete footings at least three feel below ground – beyond any possible disturbance of a lifting frost. Landscape elements are more susceptible because they are not built atop concrete, only requiring a base of dry-laid compacted material one foot or so deep.
As a garden designer and builder, my livelihood depends on observations of the weather. My company’s installations must stand the test of time, and as more frequent and forceful rain and snowfalls challenge historic projections for ‘hundred year floods’, our construction techniques are being adapted to withstand the seeming ‘new norm’. Because of the accumulated precipitation this year, even well-established garden elements, some over fifteen years ago, were upset for the first time.
What to do?
The remedy depends on the surface material involved. Streets are patched with new blacktop, although once a spot is weakened it seems to become a perennial problem.
Disturbed brick and precast pavers must be re-laid. The affected areas must be re-graded, leveled and compacted before the surface material is righted.
Concrete patios and walkways set on slabs at least four inches thick usually aren’t affected by frost. If they are, repairs are minimal and generally limited to cleaning out and reapplying the mortar joints between stones. These joints are the outdoor equivalents to the grout between ceramic tiles inside your home.
The winter of 2014 - 2015 penetrated the earth to new depths and left a wake of damage to our environment.
Writing this on one of the first mild days of late winter, I do feel hope on the horizon. True to lore, March came in like a lion. Hopefully it will go out “mellow as the month of May”.