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The purpose of a land drain is to allow water in wet or swampy ground to rapidly drain away [1] or to relieve hydrostatic pressure. They are subterranean linear structures which are laid to a fall which should be as steep as practicable. They are used in agriculture and in building construction sites. Modern land drains take the form of a perforated or discontinuous (i.e. open-jointed) pipe. Typically, the land drains conduct the surplus water to an open ditch or natural water source.
Traditionally, land drains were formed in clay soils and peats by excavating a trench and forming a "tunnel" using flat stones. This was very labour-intensive but could often be done using free materials at hand. Typically they were two to three feet (600mm-900mm) below the surface. Agricultural land drains have to be installed sufficiently deep to avoid plough damage. In 1843 in England short earthenware pipes were first used laid edge to edge. The earliest type consisted of a "u" shaped trough onto which a flat lid was placed. Later the extruded clay pipe was developed. These are still used. These can be laid in an excavated trench, or a horizontal hole is formed in the ground using a mole plough and the pipes are forced in by means of a hand or mechanical press. By this means, heavy wet soils, bogs and swamps could be rendered amendable to agriculture. Virtually all crops need a well-drained soil to grow well.
Many modern land drains are created utilising rigid or flexible plastic pipes pierced with holes, laid in pea gravel. (The pea gravel is pea-sized pebbles without sharp points to damage the pipe.) Geotextile material can surround the gravel to keep out silt. This can be installed in an excavated trench. Specialised mole ploughs are available that can form the hole, insert the perforated pipe (and gravel if required), all in one simultaneous and continuous process. An extremely powerful (usually tracked) tractor is necessary. The flexible pipe is carried as a roll on the back of the machine. There is a sometimes a hopper for gravel which is kept topped up by an adjacent machine. The pipe and gravel go down apertures in the plough blade as the tractor proceeds along the desired route.
The purpose of land drains in building construction is somewhat different. If voids are created in the ground for any reason they tend to fill with water. Also the static loads on any subterranean structure and retaining walls can be massively increased by the presence of water in the surrounding ground. Land drains are introduced to relieve this pressure. Traditionally, the drains were created by backfilling behind retaining walls etc. with rubble and allowing the water to drain through the rubble to some suitable point.
Instead of having open ditches at the side of highways, land drains can be installed. The excavated trenches are completely filled with gravel (i.e., no soil cover). This is far safer than open trenches if a vehicle should run off the highway.
Holes or gaps have to be left in the pipes to allow water to transfer from the subsoil to the pipe and these tend to block with soil or allow silt into the pipe, so blocking it or reducing the flow of water. This can be partially overcome by surrounding the pipes with gravel. However, with time even the gravel becomes choked with soil/silt, so in the latest practice, the gravel is surrounded with a geotextile material which filters out soil particles. Ideally, land drains are laid with access points so that high pressure water jetting is possible to clear silt. However, whatever the technology, all land drains have a finite life and eventually become ineffective due to the ingress of silt and/or the blocking of the surrounding filter media.
A plough or plow is a farm tool for loosening or turning the soil before sowing seed or planting. Ploughs were traditionally drawn by oxen and horses but in modern farms are drawn by tractors. A plough may have a wooden, iron or steel frame with a blade attached to cut and loosen the soil. It has been fundamental to farming for most of history. The earliest ploughs had no wheels; such a plough was known to the Romans as an aratrum. Celtic peoples first came to use wheeled ploughs in the Roman era.
Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging, but many soils need artificial drainage to improve production or to manage water supplies.
A dry well or drywell is an underground structure that disposes of unwanted water, most commonly surface runoff and stormwater, in some cases greywater or water used in a groundwater heat pump. It is a gravity-fed, vertical underground system that can capture surface water from impervious surfaces, then store and gradually infiltrate the water into the groundwater aquifer.
A French drain is a trench filled with gravel or rock, or both, with or without a perforated pipe that redirects surface water and groundwater away from an area. The perforated pipe is called a weeping tile. When the pipe is draining, it "weeps", or exudes liquids. It was named during a time period when drainpipes were made from terracotta tiles.
In engineering, a foundation is the element of a structure which connects it to the ground or more rarely, water, transferring loads from the structure to the ground. Foundations are generally considered either shallow or deep. Foundation engineering is the application of soil mechanics and rock mechanics in the design of foundation elements of structures.
A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed.
Septic drain fields, also called leach fields or leach drains, are subsurface wastewater disposal facilities used to remove contaminants and impurities from the liquid that emerges after anaerobic digestion in a septic tank. Organic materials in the liquid are catabolized by a microbial ecosystem.
An irrigation sprinkler is a device used to irrigate (water) agricultural crops, lawns, landscapes, golf courses, and other areas. They are also used for cooling and for the control of airborne dust. Sprinkler irrigation is the method of applying water in a controlled manner in way similar to rainfall. The water is distributed through a network that may consist of pumps, valves, pipes, and sprinklers.
A trencher is a piece of construction equipment used to dig trenches, especially for laying pipes or electrical cables, for installing drainage, or in preparation for trench warfare. Trenchers may range in size from walk-behind models, to attachments for a skid loader or tractor, to very heavy tracked heavy equipment.
Directional boring, also referred to as horizontal directional drilling (HDD), is a minimal impact trenchless method of installing underground utilities such as pipe, conduit, or cables in a relatively shallow arc or radius along a prescribed underground path using a surface-launched drilling rig. Directional boring offers significant environmental advantages over traditional cut and cover pipeline/utility installations. The technique is routinely used when conventional trenching or excavating is not practical or when minimal surface disturbance is required.
Basement waterproofing involves techniques and materials used to prevent water from penetrating the basement of a house or a building. Waterproofing a basement that is below ground level can require the application of sealant materials, the installation of drains and sump pumps, and more.
Landslide mitigation refers to several human-made activities on slopes with the goal of lessening the effect of landslides. Landslides can be triggered by many, sometimes concomitant causes. In addition to shallow erosion or reduction of shear strength caused by seasonal rainfall, landslides may be triggered by anthropic activities, such as adding excessive weight above the slope, digging at mid-slope or at the foot of the slope. Often, individual phenomena join together to generate instability over time, which often does not allow a reconstruction of the evolution of a particular landslide. Therefore, landslide hazard mitigation measures are not generally classified according to the phenomenon that might cause a landslide. Instead, they are classified by the sort of slope stabilization method used:
A vacuum sewer or pneumatic sewer system is a method of transporting sewage from its source to a sewage treatment plant. It maintains a partial vacuum, with an air pressure below atmospheric pressure inside the pipe network and vacuum station collection vessel. Valves open and reseal automatically when the system is used, so differential pressure can be maintained without expending much energy pumping. A single central vacuum station can collect the wastewater of several thousand individual homes, depending on terrain and the local situation.
A subsoiler or flat lifter is a tractor-mounted farm implement used for deep tillage, loosening and breaking up soil at depths below the levels worked by moldboard ploughs, disc harrows, or rototillers. Most such tools will break up and turn over surface soil to a depth of 15–20 cm (6–8 in), whereas a subsoiler will break up and loosen soil to twice those depths.
In geotechnical engineering, watertable control is the practice of controlling the height of the water table by drainage. Its main applications are in agricultural land and in cities to manage the extensive underground infrastructure that includes the foundations of large buildings, underground transit systems, and extensive utilities.
An agricultural drainage system is a system by which water is drained on or in the soil to enhance agricultural production of crops. It may involve any combination of stormwater control, erosion control, and watertable control.
A suction excavator or vacuum excavator is a construction vehicle that removes heavy debris or other materials from a hole on land.
Dewatering is the removal of water from a location. This may be done by wet classification, centrifugation, filtration, or similar solid-liquid separation processes, such as removal of residual liquid from a filter cake by a filter press as part of various industrial processes.
Subsurface Textile Irrigation (SSTI) is a technology designed specifically for subsurface irrigation in all soil textures from desert sands to heavy clays. The use of SSTI will significantly reduce the usage of water, fertilizer and herbicide. It will lower on-going operational costs and, if maintained properly, will last for decades. By delivering water and nutrients directly to the root zone, plants are healthier and have a far greater yield.
A tree box filter is a best management practice (BMP) or stormwater treatment system widely implemented along sidewalks, street curbs, and car parks. They are used to control the volume and amount of urban runoff pollutants entering into local waters, by providing areas where water can collect and naturally infiltrate or seep into the ground. Such systems usually consist of a tree planted in a soil media, contained in a small, square, concrete box. Tree box filters are popular bioretention and infiltration practices, as they collect, retain, and filter runoff as it passes through vegetation and microorganisms in the soil. The water is then either consumed by the tree or transferred into the storm drain system.