Buffalo Excavating, From a Footing Trench to a Full Basement

Sand over clay: reading the ground before we dig

Some ground around Buffalo digs easily for the first two or three feet and then turns into something else. The Cheektowaga soil series, whose official USDA description is based on a site in the Town of Clarence, shows the pattern: 20 to 40 inches of sandy soil sitting on varved (finely layered) silty clay loam and silty clay, described as firm and plastic. Water moves quickly through the sand and slowly through the clay, so it collects right where the two meet.

In an open hole, that contact line is where trouble starts. Sand has no real cohesion and sloughs off the wall as it dries, water weeps out at the top of the clay, and wet clay smears and clings to the bucket. Neighboring soils such as Lakemont and Madalin formed in clayey lake deposits and are poorly drained as well.

That is why we read the ground before we price it. How the lot drains after rain, where the low spots sit and how deep the dig must go tell us whether the hole needs a pump, how far back the spoils go, and whether the work should wait out a wet week. Soil type also sets how the walls are cut, which the next section covers.

811 marks, white paint and the private lines in your yard

Under Part 753, the state's rule for protecting buried utilities, the excavating contractor files the locate ticket, not you. UDig NY, the 811 call center, needs that ticket at least two working days before the first scoop, and it can't be filed more than ten working days early. We outline the work area in white paint so locators know where to look, and the bucket stays parked until every utility on the ticket has painted its lines or reported nothing within 15 feet.

Paint colors are set by the same rule. Red is electric, yellow is gas, orange is phone or cable, blue is water and green is sewer. Around each mark sits a buffer the rule calls the tolerance zone: 24 inches each way from the middle of the mark, widened by half the line's diameter when its size is known. Where a gas line's tolerance zone overlaps the dig, the pipe has to be exposed with hand-dug test holes before a machine works there, and once any line is verified, no powered bucket comes within four inches of it unless the utility agrees in writing.

What 811 leaves out matters just as much. Public lines are typically marked only up to the property line, with gas marked to where it enters the house, and UDig NY lists sewer laterals, water services, sprinkler lines, invisible dog fences and wires to lamp posts among the private lines that may go unmarked. Tell us where yours run and we hand-dig where they should cross. A cracked lateral goes to our sewer lateral repair service, and new water or electric runs go in through our underground utility installation work.

Cave-in rules and the real footprint of a dig

Federal OSHA rules shape every deep hole. Once a trench or excavation in soil reaches five feet and people will work in it, the walls need protection: sloped or benched back, shored, or shielded with a trench box. Trenches four feet or deeper need a ladder, ramp or stairs within 25 feet of each worker, and spoil piles sit at least two feet back from the edge.

How far the walls get laid back depends on the soil class. Clay that tests at 1.5 tons per square foot or more in unconfined compression can rate as Type A, the most stable class short of solid rock, but not if it is fissured, shaken by heavy traffic or previously disturbed. Sand, loamy sand and any soil with water freely seeping out of it are Type C, the least stable. A layered wall is normally rated by its weakest layer, and where firmer clay lies under the sand, each layer may be rated on its own, which still leaves the sand band in Type C, and rain can force a downgrade mid-job.

A full basement hole covers much more of your yard than the foundation outline, and that extra width gives room to set forms and lay drain tile for your new foundation and basement walls. Beside an existing house, the soil against the wall was disturbed during construction and can't count as Type A, so we plan a flatter cut or a box and never undermine the old footing. On a tight city lot with no room for a two-foot setback, OSHA notes that spoils may need to be hauled off temporarily, and we price that in from the start.

Keeping a footing trench sound through freeze and thaw

Footings have to sit below the depth frost reaches, or freeze-thaw cycles can lift and crack them. The required depth comes from your local building department and can differ from one municipality to the next, so the number on your permit drawings is the one that counts. As one example, the City of Niagara Falls deck guidelines set deck footings 42 inches deep, measured from finished grade to the bottom of the footing.

Our job is to get the trench bottom to that depth and keep it sound. We cut footing trenches down to undisturbed soil at the depth on your plans, clean the bottom by hand where the bucket leaves loose crumbs, and keep water out so the concrete bears on firm ground. Soft pockets get dug out and replaced, not covered over.

Winter changes the plan. A footing trench left open on a January night can freeze at the bottom, and concrete should never go onto frozen ground, so winter digs get timed to the pour or the bottom gets covered. Frozen chunks stay out of the backfill too: Part 753 bars backfilling with frozen earth, large rock or rubble that could damage buried utilities. Spring thaw brings the opposite problem, when saturated clay goes soft and a loaded truck can rut a lawn that looked solid a week earlier.

Backfill in lifts and a plan for every load of spoils

Backfill is where a sound dig can still go wrong months later. Dumping loose clay into a trench and tracking over the top leaves voids that settle after the first wet spring, which is how you end up with a sunken strip over a new water line or a low spot along the foundation. We place backfill in thin lifts and compact each one before the next, with stone or sand bedding around pipe and soil that will actually compact higher up. Part 753 also requires the fill beneath and around buried utilities to be properly compacted and to support the line.

Large-diameter pipe raises the stakes. A 24- or 30-inch storm pipe or culvert needs a trench wide enough to work compaction equipment down both sides, because the soil packed under the lower curve of the pipe, called the haunch, carries much of the load. Skimp there and the pipe can deflect, sag or crack.

Extra spoils either leave the site or stay for a reason. Wet clay that won't compact gets hauled off, while stripped topsoil can be stockpiled for final grading and topsoil spreading. On a raw lot, the dig is one step in a longer sequence of clearing, utilities, pads and grading that our site development page lays out.