A gravel-filled hole is a dry well, and it works only when the soil underneath it can absorb water faster than the hole collects it. On ground that drains, a properly sized one solves a wet spot. On ground that sheds, it is a bucket that fills up and stays full.

Whether a soakaway empties here

81% of the mapped ground in Syracuse sheds water rather than absorbing it, and the shallowest mapped seasonal water table sits 3.1 inches down. Both of those say the same thing about a gravel-filled hole here: it will fill and it will not empty. On the shallow-table months it is below the water line before the rain starts. This is the ground condition where a soakaway is storage and nothing else, and the water still has to be taken somewhere.

The reasoning behind that

A dry well is storage plus infiltration. The stone holds a volume of water temporarily; the soil at the sides and base is what empties it. If infiltration is slow, the storage fills on the first storm and has not emptied by the second.

Sizing follows from that. The volume has to hold the runoff you are directing into it long enough for the surrounding soil to absorb it, which means it is set by the infiltration rate and the area draining to it — not by how big a hole is convenient to dig.

Two details decide how long it lasts. Fabric between the stone and the soil keeps silt out of the voids. An inspection point lets you see whether it is emptying, which is the only way to know it is still working.

A dry well also has to sit well away from foundations and above the seasonal water table. Below the table, it is already full before the first drop of rain arrives.

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