Water movement can bring great benefits in many situations, as rain brings needed moisture to crops and broad, deep rivers carry ships laden with cargo down to the sea. But even in normally desirable circumstances, water movement can become destructive - too fast, too much, edging beyond its normal boundaries. In truth, water is one of the most destructive forces known to man and maintaining control over it is a high-stakes industry.
Controlling water might mean reinforcing a dam so that leaks don’t lead to a collapse. It might mean reinforcing banks of a river so that fast moving water doesn’t erode them to a dangerous point. It could mean collecting and diverting stormwater within a city to temporary basins where silt and other solids can settle out before it’s released in a controlled manner to local waterways.
Sometimes, the main objective in controlling water is to simply slow it down or force it to drop whatever it’s carrying. Baffle curtains are used whenever construction sites are adjacent to surface waters, and their mission is to slow flowing water enough that mud, sand, and silt have time to settle to the bottom before the water moves on downstream, downriver, or along with the tides.
Stormwater Management
Simply put, stormwater is rain or melting snow that travels across the ground. In urban areas especially, large expanses of the ground are covered with hard surfaces such as buildings, roads, sidewalks and so on. In this environment, stormwater can carry dangerous pollutants into local surface waters, traveling across hard surfaces, creating dangerous and damaging floods and cause significant health hazards when septic and sewage systems overflow. For this reason, controlling the movement of stormwater and managing how it’s released into the environment is a high priority for cities and towns of all sizes.
Stormwater management can be classified into two approaches: structural and non-structural management practices. Non-structural might include expanding natural areas, minimizing the use of impervious surfaces as new areas are developed, providing vegetative buffers along surface waterways, and encouraging the use of green roofs.
Structural management covers measures which are intended to reduce, capture, or direct flowing stormwater. To manage flooding and risks to infrastructure and local populations, the first line of defense is to expand areas where water can flow and be absorbed directly into the soil. Porous concrete, permeable pavements, planted areas, vegetated roofs, and decks erected on pier foundations are all excellent examples. In a less than ideal solution for water that isn’t immediately absorbed, pipes, canals and floodways may be used to direct excess water into natural or constructed reservoirs and used to replenish groundwater or stored for future use. Those measures may be adequate for most storms, but exceptionally heavy rainfall for any given region is increasingly common, and artificial stormwater systems are often unequal to the need.
Structural solutions for managing pollutants might include directing captured stormwater and directing it into a series of detention ponds, where the water is kept stationary. This allows fine sediment and other suspended pollutants to settle out before it’s further cleansed at a water treatment plant. Alternatively, stormwater may be directed into constructed wetlands, where both settling and natural filtration can occur. The plants that inhabit wetlands are adept at breaking down and isolating common pollutants, producing water that is once again clean enough to be released into the environment. Rain gardens and bioswales serve similar purposes on a much smaller scale.
When stormwater has flowed over impermeable surfaces like pavement, it is considered polluted and should be prevented from soaking into the ground before it has been treated, whether naturally or artificially. In cases like constructed wetlands, water is actively detained within the wetland environment as the ecosystem works to remove pollution and excess nutrients. These constructed wetlands are lined with impermeable geomembranes so that stormwater cannot escape before it has had a chance to be decontaminated.
Temporary Erosion Control
Nearly every type of land development and construction involves practices which disturb soil, leaving it vulnerable to erosion when exposed to wind, rain, and physical disturbances. When there is a chance that eroded soil may be carried off and flow into surface waters, most states and municipalities step in to ensure that the quality of those waters is not compromised.
While most erosion control plans begin by defining and maximizing areas that maintain natural with established vegetative layers, they also include plans for interrupting or diverting flow to settling ponds and similar impoundments before it reaches rivers, streams or lakes. Erosion control also includes measures to dissipate the energy of rapidly moving water, which might include placing wattles or other elements to disrupt the flow. These are typically accompanied by measures that prevent concentrated flows from developing and cutting around these kinds of disruptions and expanding the eroded area. Constructed berms and slopes to keep the water flowing within a defined space are common solutions.
RPE liners are often used to protect the soil on berms and slopes from the effects of fast-moving water. A combination of riprap and an impermeable liner can be employed to slow and dissipate the energy of stormwater while preventing that water from seeping through and destabilizing the supporting slope. In this type of case, RPE is an excellent choice because of its exceptional durability and resistance to damage from weathering, including temperature extremes. Whether the erosion control measures are temporary or permanent, it’s important to have confidence that your liner will not fail due to mechanical damage or degradation from exposure to the environment.
Sports field, turf drainage
Sport is a huge industry in the US and elsewhere, and there’s often a lot riding on games, whether it’s the monetary investment in a major league playoff game or the emotional investment in the local high school’s homecoming game. The need to maintain a high-quality field, that can be played in most weather conditions, requires carefully designed drainage systems that can rapidly move water away from the field and restore a relatively dry and safe playing surface.
When artificial turf is installed, subsurface drains allow rain to quickly move through the surface layers, where it is captured and diverted before soaking into the soil underneath. This is to ensure that the soil doesn’t become saturated, keeping the playing field wet, and to prevent it from becoming unstable, which can create significant damage if it shifts or erodes. Since the goal is to move water away as quickly as possible, an impermeable liner is usually the best option, particularly in situations where the underlying soil has a high clay content. RPE liners are excellent candidates for this type of application because of their long life and extreme durability.
