What happens to the dirt when you dig a pool?

More than the pool holds. The excavation has to be bigger than the pool, with room around the shell for backfill and a few inches underneath for a stone base. Here is a rough worked example using two Liberty fiberglass shells and their published depths and gallons.

How we got there: we assumed an excavation 2 ft wider than the shell on every side, an average depth halfway between the shallow and deep ends, plus 6 inches for the base. Real excavations vary with the shell's shape, the steps and benches, the soil and how steep the sides can be cut, so treat these as ballpark numbers for planning, not a quote. The point is the scale: even a modest pool produces several truckloads of soil.

Soil in the ground is packed tight. Dig it up and it breaks into clods with air between them, so the same soil takes up more room in a pile or a truck. Earthwork estimators call this swell. Construction references typically put the swell of clay at about 30 to 40 percent, with heavy or wet clay at the high end.

Northeast Ohio's glacial till soils, such as Mahoning silt loam, are dense and clay-rich, and they are often wet when they come out of the ground. The USDA describes Mahoning soils as holding a seasonal water table close to the surface from October through June in most years. That is why a Northeast Ohio pool dig tends to look like more dirt than expected: the soil swells, and it is heavy and sticky.

Because the native clay is the wrong material for backfill. Clay holds water against the pool, does not compact evenly when wet, and moves with freeze-thaw. Fiberglass shells in cold, wet climates are normally backfilled with clean crushed stone that drains and locks together, a practice fiberglass maker Thursday Pools recommends for the freeze-thaw regions of the Midwest and Northeast.

So the math works against you. Every yard of stone that goes around the pool is a yard of clay that has to go somewhere else. Almost all of the excavated soil is surplus, apart from any topsoil saved for the lawn and whatever can be used for grading.

There are three, and many projects use more than one.

• Haul it off. Dump trucks take it to a site that accepts clean fill. It is the cleanest option for the yard and the most common on smaller lots. It costs money in truck time and sometimes disposal fees.
• Regrade with it on site. Fill a low spot, raise a soggy area, build a gentle berm or level part of the yard. This saves haul costs but only works where you have the room and where extra soil does not create a drainage problem for you or the neighbors.
• Split it. Keep what the yard can use and haul the rest.

Topsoil should be handled separately. It is stripped first, set aside and put back on the disturbed areas at the end so the lawn can recover. It is the most valuable soil in the pile and the easiest to waste by mixing it with subsoil clay.

When the yard has a real use for it. A low area that holds water after every rain is a good candidate, as long as filling it does not simply push water somewhere else. So is a slope where a little fill and a retaining wall create a flat patio. On large rural lots in Portage, Medina or Geauga County, there is often room to spread the soil over a wide area and seed it.

A few cautions. Wet clay makes poor fill for anything that needs to carry weight, like a patio, shed or driveway, unless it is dried, placed in thin layers and compacted. Big piles left over the winter erode, and a berm on a property line can send runoff to a neighbor. Some towns also regulate grading or mounding near lot lines, so check before you build a hill. And never place fill over a septic leach field or in a drainage easement.

It depends on the trucks. Loads are measured in loose cubic yards, and a typical dump truck carries something in the range of 10 to 15 loose cubic yards, less when the soil is wet and heavy. Using the examples above, a Hero-sized pool could mean roughly 8 to 13 loads, and a 16x40 pool roughly 18 to 29 loads, if all of it leaves the site.

That traffic is worth planning for. Loaded trucks are heavy on driveways, curbs and lawns. The route to the street, where trucks wait, and how the driveway is protected are part of the site plan. In a subdivision with an HOA, the association may want to know too.

On a fiberglass build, the excavation happens fast, and the soil has to go somewhere the moment it comes out. There are two common ways to handle it. The excavator can load trucks directly as it digs, so the soil leaves the yard right away. Or the soil is stockpiled on site, in a spot agreed in advance, and hauled or spread later.

Direct loading keeps the yard cleaner but needs trucks lined up and a route they can use without tearing up the lawn. A stockpile gives more flexibility but takes up space, can wash in a storm and has to sit somewhere it will not block access for the shell delivery or the concrete trucks. Either way, the stockpile spot and the truck route should be on the plan before digging starts, and away from septic fields, drainage swales and the neighbor's fence.

Yes. Wet clay is heavy, sticks to truck beds and turns a lawn into ruts under loaded tires. After a soaking rain it may make sense to pause hauling for a day rather than damage the driveway and yard. Dry clay is easier to move, easier to spread if some of it is staying, and easier to compact if it is being used for grading. This is one reason the drier months, from late spring into fall, tend to make for the cleanest pool digs in Northeast Ohio.

Sometimes. A neighbor filling a low yard, or a farm nearby looking for fill, may take clean soil, which can cut the haul distance. The soil has to be clean, meaning no concrete chunks, roots, trash or anything that does not belong in a yard, and the receiving site has to be reachable by the trucks. It is worth asking around before the dig. Do not count on it, though. Wet clay subsoil is not something most people want, and topsoil is usually the only part of the pile in real demand.

Spoils handling is one of the site items priced after we see your yard rather than folded into the package. Our fiberglass packages start at $68,400 installed and include the Pentair equipment, a 4 ft concrete deck, installation and startup. Spoils haul-off, dewatering, extra decking, fencing and the panel-to-pad electrical run are priced separately, because they change so much from one lot to the next.

On the site visit we look at where soil could be used, how far trucks would travel, and how access works, and the quote shows the plan. If part of the soil can stay and improve your yard, we will say so. If hauling it all is the better answer, the quote shows that clearly.

When you compare quotes from different builders, check this line in particular. A lower price that leaves the dirt piled in your yard, or says nothing about it, is not the same project as one that hauls it away and restores the lawn.

Northeast Ohio till carries stones and occasional boulders, and older lots sometimes hide buried debris, old foundations, clay drain tile or roots from trees long gone. These come out with the dirt and generally leave with it. Stones can be useful for a dry creek bed or edging if you want them. Field tile that turns up needs to be rerouted or capped so it does not keep feeding water toward the new pool. Anything that looks like buried household trash or an old fuel tank needs to stop the dig until it is handled properly.