How do sand and gravel pits cause impacts that can endanger life or property?
There are three potential impacts of sand and gravel mining: (1) When floodwaters enter a pit, erosion occurs or the upstream lip of the pit and moves upstream in a process known as “headcutting.” Floodwaters in natural streams in Mohave County contain huge quantities of sand and gravel in motion. When these sediment-rich waters enter a large pit, the solids settle out, and the water leaving the pit is relatively clean. (2) This cleaner water tends to pick up more sediment after leaving the pit and causes downstream erosion, or “tailcutting.” (3) Deep pits with steep slopes and inadequate embankment stabilization tend to collapse into the pits as floodwaters pass, causing lateral migration of the pit.
