Structural Drying & Dehumidification in Gloucester Courthouse, VA

That is a water table event rather than a runoff event, and it is common on the coastal plain. Sandy soil sits over a table that is normally a few feet down; a large tropical rainfall raises it above the crawl space floor and water appears from below with no visible surface flow. Grading and gutters cannot fix it. What helps is a crawl space drain and pump, plus keeping the ground surface as free-draining as possible.

Not until both are checked, and this matters more here than in a town on public services. A submerged wellhead can admit surface water directly into the supply, and a saturated leach field cannot accept anything until it drains. Both need to be assessed before the house is reoccupied, independent of how the structure itself is drying. Contractors focused on the building will not necessarily raise this, so it is worth asking directly.

Because it controls where the water can go. Drainage here ultimately discharges to tidewater, and at high tide there is no head available to move anything. A tropical system typically arrives with elevated water levels already, so the heaviest rainfall of the year lands during the hours when the drainage system is least able to take it. The two conditions are not independent, which is why September events here are so much worse than their rainfall totals suggest.