Stump Grinding in Hillsboro Park, Forest Hills

The walk to the front door has a step in it now

Hillsboro Park is the largest block of untouched mid-century housing left in the city. The median house here went up in 1959 and most of the rest between 1955 and 1973, and a good share of them still have their original front walks and driveway aprons - four inches of unreinforced concrete poured when the houses were new.

That concrete has spent sixty-five years sitting on top of the root systems of silver maples, pin oaks and sugar maples planted at the same time. Those species root near the surface, the roots thicken by a fraction of an inch a year, and eventually the panel above one of them lifts. Now the walk from the drive to the porch has a two-inch step where nobody expects one, the mower scalps a root every pass and leaves a wound that never heals, and the paver edging somebody added in 2004 is riding up out of the bed.

Which is why the call from this neighborhood usually is not about a stump at all. It is about a line of roots and what to do with them.

A lifted panel is a root problem wearing a concrete costume

Break out the slab, pour a new one and do nothing else, and you get the same heave back in five or six years, because the thing that lifted the first one is still under there and still growing.

So the order matters: deal with the root, then the concrete. Where the tree is already gone, that is straightforward - we take the offending roots down below the underside of where the new slab will sit, well past the edge of the panel so the next one along does not become the new problem.

Where the tree is still alive and you want to keep it, there is a real trade to talk about. Cutting a large structural root close to a trunk takes away both anchorage and a share of the tree's water supply, and it is the kind of decision that shows up as a leaning tree years later. The working rule we use is to stay outside a distance of roughly three times the trunk diameter from the trunk. Inside that, we would rather shave the top of the root than sever it, or tell you honestly that the walk needs to move instead.

Pin oak roots are the ones under the driveway

The 1950s plant list around Melbourne and Cromwell leaned on fast shade, and each species that came out of it misbehaves differently.

Silver maple is the champion surface rooter - broad, shallow, and quite happy to run twenty feet along the underside of a walk. Pin oak is the one that turns up under drives and aprons; it also goes chlorotic in the alkaline soil that concrete leaches into, which is why the yellowing pin oak and the cracked driveway on the same lot are usually the same story. Sugar maple stays a bit deeper but flares wide at the base. Water oak splits the difference and hollows early.

When we shave a root rather than remove it, we take the crown of it down to below the slab line and leave the underside intact, which keeps most of the conducting tissue working. That is the difference between a repair and an injury.

What sixty-five-year-old hardscape does to a grinding wheel

Old front yards hide things. The concrete on these streets sometimes has wire mesh in it, there is often a course of buried brick edging along a bed line from a landscaping job two owners ago, and the occasional length of galvanised pipe from an irrigation setup that predates plastic.

Carbide teeth handle wood and soil. They do not handle steel, so on a root chase we go slowly and shallowly on the first pass, feeling for what is in there before committing to depth. It is why root work along a walk is quoted by the linear foot and the conditions rather than by a single stump diameter.

The chip from that kind of job comes out mixed with soil and grit rather than clean, which makes it heavier and less useful than a normal grind's output. On most of these lots it goes in the truck.