When inflow of groundwater exceeds 12 inches per hour in a drilled shaft, what is the appropriate procedure?

When groundwater inflow exceeds 12 inches per hour in a drilled shaft, flooding the shaft and placing concrete using the wet method is appropriate. This method allows for the placement of concrete underwater, which can help ensure that the concrete does not mix with excess groundwater in a way that negatively affects its properties.

In high flow conditions, this approach can help maintain the integrity of the concrete placement, ensuring that the concrete sets properly and minimizing the risk of contamination with water, which could otherwise lead to weakness or other structural issues. The wet method is specifically designed for handling such challenging conditions where high volumes of groundwater are present.

Conversely, adding additional cement to maintain the water-cement ratio does not address the problem of the high groundwater inflow effectively and may lead to other structural issues. Continuing to pump groundwater during placement could undermine the stability and integrity of the shaft. Drilling deeper could increase the water flow without solving the problem of how to place concrete effectively in such conditions. Thus, the best procedure in this scenario is to flood the shaft and proceed with wet concrete placement.