A walk laid stone by stone until the joints run true — that is the kind of result S & M Landscape & Contracting LLC leaves behind in Billerica, a hardscape that sits level with the ground and looks like it was always meant to be there. The work runs deeper than the surface: excavation and site work that shapes a lot before anything is built on it, demolition that clears the way, grounds management and development that keeps a property looking cared for from the road. This is a town of river bends and old mill streets, of low woods off the Concord and yards that slope more than they let on, and every job here begins with reading the land honestly. Come winter, commercial snow and ice management takes over — lots opened and salted while the sky is still black over Route 3, so the first cars of the morning arrive to clean pavement and never think about how it got that way. From Billerica out across Eastern Massachusetts and into Southern New Hampshire, the satisfaction is the same: a place left better graded, better edged, better able to hold its season.