Why is groundwater sometimes a problem at construction sites? How tan the problems be solved? Solution Distress or failure of existing pavement; • Wet spots in pavement or subgrade material piping through cracks or joints; • Undulating pavement surface; • Unlined irrigation canals on slopes uphill of highway; • Cattails or wetlands vegetation growing in borrow ditch or on slopes; • Seepage from cut slopes or natural slopes; • Evidence of slope instability such as scarps, old landslides, and trees at adverse angles..