Spotting Erosion and Sediment Control Problems
Proper Construction Control
Spotting Control Failures | Monitor Construction Sites |Resources
With an understanding of the basic design and function of priority erosion and sediment controls, it’s possible to determine if controls are failing and/or pollution is leaving the site. Most problems occur because the controls were not installed, were designed incorrectly, were applied for wrong purpose, or were not maintained.
Here are common signs of construction site control failures and the pollution impacts that may be observed from public areas adjacent to construction sites.
When an entrance is too small, does not include enough rock or matting, or does not hold rock in place, heavy equipment and vehicles can drag mud off-site on their tires. Signs of a poor construction entrance include spillage of the majority of rock out into the roadway, ponding of water in and around the entrance, and tracking of mud in the road.
If sufficient temporary or permanent stabilization is not installed in a timely manner, mud will move and problems will be readily evident. Telltale signs that the stabilization techniques are failing are spots of bare mud, gullies, brown burnt-out grass, water ponding, and mud in off-site areas.
Improper installation or damage to the fence can allow water to run under, over, through, or around it, carrying sediment off the site. A poorly maintained fence may fail if it sags and falls or has too much mud built up behind it. Fencing that is falling, sagging, or has visible gaps underneath it, and the presence of mud and muddy water below the fence line, are all symptoms of problems.
When left in place too long, straw bales fall apart or rot and fail to do their job. Similarly, bales can fail if they are not placed joining one another end-to-end and firmly anchored. Bales that have lost their form (resemble a pile of straw), gaps between individual bales, and mud downgrade of the bales are all evidence of failure.
Soil stockpiles left unprotected without properly installed and maintained stabilization and sediment barriers will readily erode and release mud when it rains. Signs of problems are knocked-down or absent silt fences, gullies and mud slides, and presence of soil outside the stockpile area.
Storm Drain Inlets
Storm drains, sewers, and other inlets located on site or immediately below construction entrances or other activities must be protected. Signs of problems are significant mud deposits at the inlet; filter, sandbag, or rock barriers that have holes or gaps; or puddles of water around the inlet.
Stormwater conveyance channels, such as roadside ditches, are designed to carry rainwater within sites prior to discharge. Signs of poor operation or maintenance are undercutting of the channel, spots of bare mud, ponding or flooding in the channel, and mud accumulation or erosion around the end of the channel.
Sediment traps are designed to slow down water and allow mud to settle out of runoff from active construction sites. Symptoms of problems are an accumulation of mud and ponding of water at the trap entrance; traps that permanently hold water; gaps in the sides of the trap that allow water to rapidly pass through; and traps placed above (upgrade of) the channel delivering runoff. Further, traps that remain in place after the development appears complete may indicate that more permanent long-term stormwater management solutions for the finished development have not been installed.
Outlet protection is intended to slow down concentrated water flows carried by pipes and channels. Signs of problems are “hanging” pipes or channels that discharge to receiving waters without any protection; placement of insufficient size or amount of riprap; an eroded depression below the outlet; or an outlet that is clogged that never releases water.
Off Site Pollution—Sedimentation, Nutrient Pollution, Chemicals, and Streambank Damage
Off-site problems can be visible if the suite of installed erosion and sediment control efforts is unsuccessful in preventing off-site impacts. Signs of problems include: