Groundwater & Basement Water Intrusion in Preakness, NJ

Because the basin drains slowly by nature. The river through it has very little fall, and the surrounding ground is old lake bed that holds water rather than shedding it. Once a large storm fills the basin, the water leaves on the river's schedule regardless of what the weather does afterward. Duration rather than depth causes most of the loss locally, since materials that would survive a few hours do not survive several days.

It changes when it can start and what can be saved. Nothing can be dried while the water is still there, so the first days are about extraction readiness rather than drying, and materials that sat submerged for days are usually beyond saving whatever a meter says afterward. Planning for a longer wet period, and getting a contractor committed before the water drops rather than after, is what shortens the overall timeline.

For the seasonal table, yes, and it needs to be sized for continuous running and put on backup power. For a basin flood it is not, and expecting it to be leads to burned-out pumps and false confidence. The two mechanisms are different: a sump manages groundwater that arrives steadily, and no residential pump addresses a basin that has filled. Knowing which one you are experiencing determines whether the pump is the answer.