Main drain (collector / trunk)
Larger-diameter pipe that gathers water from the laterals and conveys it to the outlet. Its diameter is sized based on the drained area, slope, and drainage coefficient.
Technical terms for agricultural drainage and large infrastructure projects — highways, railways, warehouses, mining, and solar energy — explained directly and grounded in Brazilian reality: soils, climate, codes and standards (DNIT, ABNT, ANM), and products.
No results found.
This is what a lot of people in the field call the coiled corrugated drain pipe — because of how it's rolled up, it really does look like a big hose. Technically it isn't a hose (which is smooth and doesn't let water in through its body): it's a corrugated, perforated drain pipe, with slits that capture water from the soil along its entire length. If you came here looking for a "drain hose," this is what you need.
Saturated water zone in the subsoil. Its fluctuation (rising with rain, falling in dry spells) is controlled by subsurface drains, which lower the water level only down to the depth at which they are installed.
Very low-pH effluent (typically < 4) generated by the oxidation of sulfide minerals (pyrite, FeS₂) exposed to water and oxygen during mining. It produces sulfuric acid and dissolves heavy metals that contaminate water bodies. Prevention: impermeable covers, geomembranes, and controlled drainage.
Minor drainage structure for crossing thalwegs under embankments and road platforms. Types: BSTC (concrete/NBR 8890), box culvert (DNIT 025/2025-ES), and double-wall corrugated PEAD (DNIT 093/2016-EM). PEAD has lower roughness (n ≈ 0.009–0.011 vs. 0.013 for concrete), resistance to acidic soils, and faster installation.
Increase in soil density from a reduction in pore space, caused by machinery traffic or trampling under wet conditions. It restricts air, water, and roots. See plow pan.
Geotechnical test that measures the soil's relative resistance to penetration compared to a standard crushed-stone reference, performed after 96 hours of soaking. A low CBR under saturated conditions indicates a weak subgrade when wet — the central argument for justifying deep drainage on highways and railways.
Chimney filter: a vertical drain embedded in the core of an earth dam, with layers of increasing grain size, designed to intercept internal seepage and convey the water to the toe drain. Inverted filter: a system of layers with increasing grain size that prevents fines migration under flow. Nonwoven (NT) geotextile is the modern equivalent of the granular inverted filter.
Depth of water (mm/day) the system needs to remove, used to size pipe diameter in the drainage calculator. Techduto guide references for mineral soils: 9 mm/day (forage and grain crops), 12 mm/day (commercial crops), and 20 mm/day (specialty crops). In regions with concentrated rainfall, a more conservative value is adopted ("tropical mode").
Distance from the soil surface to the top of the pipe (different from depth, which is measured to the bottom of the trench). Minimum cover protects the pipe from machinery loads — generally 600 mm for lateral drains.
Continuous layer of drainage material (crushed stone or drainage geocomposite) installed horizontally under foundations, slabs-on-grade, tailings piles, or embankments, to capture and convey percolated water to collector drains. It relieves base pore pressure and prevents differential settlement and fines pumping.
Techduto sealing tape used to seal connections (for example, at the internal joint of the Techdreno DW), ensuring a watertight seal against sediment ingress.
Controlled process of removing the risk from a tailings dam that will become permanently unnecessary — removal of the tailings, demolition of the structures, and rehabilitation of the area. Law 14.066/2020 mandated the decharacterization of all upstream dams in Brazil. Drainage is a critical component for ensuring stability during and after the intervention.
Drain parallel to the roadway or railway alignment, installed at a depth ≥ 1.5 m (minimum per ISF-210/IPR-724), to intercept and lower the water table at least 1.5 m below the grade line. Consists of a perforated corrugated PEAD pipe (Techdreno KC in fine soil) in a trench with a minimum slope of 0.5%.
Mining tailings disposal method using material that has been pre-dewatered by filtration (~75–85% solids) and compacted into stable piles. It eliminates the risk of liquefaction failure and allows reuse of up to 95% of process water. It requires a robust base drainage blanket (geocomposite + PEAD pipe) and slope erosion control.
Granular material (crushed stone or coarse sand) placed around the pipe to facilitate water entry and maintain hydraulic contact with the soil. It differs from filter material, whose function is to block fine particles.
Geosynthetic product made of a geonet (PEAD core with drainage channels) + nonwoven (NT) geotextile on the faces (filtration). It replaces crushed-stone + geotextile systems with a much smaller thickness (5–25 mm vs. 150–300 mm of crushed stone). Applied under industrial slabs-on-grade, at the sub-ballast/railway-platform interface, as a dam drainage blanket, and on retaining slopes.
Internal cleaning of the pipe with a water jet, to remove sediment and clear the system.
Distance from the soil surface to the bottom of the trench. For soybeans, depths around 80 cm are usually sufficient; in sandy soils it does not exceed 750 mm. See drain cover.
Detention (a dry basin known locally as a "piscinão"): stores the peak volume of a rainfall event and releases it slowly at the restricted flow rate. It sits empty between events. Retention (pond): maintains a permanent water surface. Detention is required by São Paulo's Decree 41.814/2002 (the "Lei das Piscininhas") in impermeable areas > 500 m².
Open-air channel for conveying water; it can be the receiving point for the outlet of subsurface drains.
Hydraulic structure installed at the outlet of culverts, chutes, and spillways to reduce flow velocity and prevent regressive erosion of the receiving channel. Most common types: stilling basin (with concrete baffle blocks) and rock riprap. The absence of an energy dissipator is one of the main causes of erosion on highways and railways.
The carrying away of particles by water. Well-designed drainage reduces surface runoff and, with it, erosion and nutrient loss; on the other hand, high velocities inside the pipe or at the outlet can cause erosion and require energy dissipators.
Section of rigid, continuous, unperforated pipe used at the drain outlet, to protect the discharge point against erosion, weather, fire, animals, and crushing.
Upward migration of fine particles from the subgrade into the upper layers of the roadway or track, caused by cyclic heavy-traffic loads on saturated soil. Responsible for ~92% of the structural problems on railways and highways. Prevention: drainage geocomposite at the subgrade-ballast interface and a deep longitudinal drain with Techdreno KC. How to identify and eliminate it on railways.
The amount of water the soil holds after the excess has drained away by gravity. It's the practical target of drainage: remove the excess without drying out the soil.
Layer (geotextile, synthetic fabric, or graded gravel) that wraps the pipe to reduce the migration of particles from the soil into the drain, maintain soil stability, and improve flow. In Brazil it is frequently necessary, since many soils have a fine texture (fine sands and silts from 50 to 250 microns) that are prone to internal erosion. Techdreno KC already includes the envelope built in. Learn when to use (or skip) the envelope.
Synthetic material with filtration, layer separation, erosion protection, and soil stabilization functions. In drainage, it wraps the pipe as a filter layer. The choice takes into account the apparent opening size and the soil texture. In Brazilian fine-textured soils the filter is usually necessary — a function that Techdreno KC already incorporates.
Indicator that relates velocity and pipe diameter; values above 1 indicate a steep slope, requiring design precautions (half-section reaches, unperforated pipe, relief wells) to avoid excess pressure and erosion.
A lowland area subject to periodic flooding by a river. In irrigated rice, drainage is part of the management practice, with alternating soil saturation; floodplains with a permanent water table are prone to ochre.
See Filter / geotextile.
Grayish or bluish colors and mottling in the soil profile, indicating prolonged saturation and lack of oxygen. It's a field diagnostic of poor drainage, typical of Gleissolos and Plintossolos. See the field signs in detail.
Impermeable barrier made of textured or smooth PEAD, used to prevent the percolation of liquids between layers. Main application in mining: lining of tailings basins, leach pads, and pile covers. It works together with the drainage geocomposite: the geomembrane blocks the passage, and the geocomposite/PEAD pipe drains on top of the barrier.
International standard published in 2020 by UNEP/PRI/ICMM in response to Mariana (2015) and Brumadinho (2019). It defines 6 topic areas, 15 principles, and 77 tailings management requirements, with mandatory review by an independent engineer. The largest global and Brazilian mining companies (Vale, Anglo, Glencore) have committed to full compliance; institutional lenders already require it as a condition of credit.
Drain installed at the upper end of the laterals or at the field boundary, to capture water that would otherwise flow into the agricultural area.
Subsurface drainage system with a central collector and oblique lateral drains (30–60°), forming a herringbone pattern. Installed at shallow depth (0.5–1.5 m), it distributes capture laterally to reduce surface moisture on highways, industrial yards, and fields.
Formula that calculates lateral drain spacing under steady-state conditions, as a function of permeability, depth, and the impermeable layer. It is the basis for sizing in the Techduto guide and the drainage calculator; under concentrated rainfall, it is complemented with the Glover-Dumm equation.
Metal extraction technique (gold, copper, silver) in which crushed ore is stacked on a pad lined with a PEAD geomembrane and a leaching solution is sprayed on top. The PLS (Pregnant Leach Solution — metal-rich solution) is collected by the pad's drainage system (geocomposite + corrugated PEAD pipe over the geomembrane) and conveyed to the recovery plant.
Drain positioned across the slope to intercept groundwater before it surfaces, installed close to the restrictive layer, where flow is concentrated.
The soil's capacity to absorb rainwater. It is reduced by compaction and by restrictive layers.
Deposit of iron oxide that forms inside the drain when iron dissolved in the soil meets air and oxidizes, often with bacterial involvement. It occurs mainly in very open, acidic sands and in floodplain soils with a permanent water table (anaerobic conditions), and is identified by intense reddish deposits at the drain outlet. There is no definitive solution — which is why it is hard to predict and requires careful design. See how to identify and reduce the risk.
Structure where several drains meet, used to join branch lines, safely change direction, and facilitate inspection and maintenance of the system.
Pipe that captures water from the soil and conveys it to the main drain. Installed in parallel, they form the capture network.
Phenomenon in which saturated, unconsolidated soil suddenly loses its shear strength and behaves like a fluid, generally triggered by a dynamic disturbance (earthquake, rapid loading). It is the main mechanism behind catastrophic upstream dam failures — upstream dams have been banned in Brazil since 2020 (Law 14.066/2020). Prevention requires tailings consolidation and effective internal drainage to reduce the degree of saturation.
Correction of small surface depressions to eliminate ponding and provide more uniform percolation. It complements subsurface drainage in flat, fine-textured soils.
Larger-diameter pipe that gathers water from the laterals and conveys it to the outlet. Its diameter is sized based on the drained area, slope, and drainage coefficient.
Unlined channel formed in clay subsoil without a pipe — a temperate-climate technique. Not very applicable in tropical Brazil; mentioned only for context.
Calcareous material that is not classified as soil. Installing subsurface drains is generally not recommended in marl or in stratified rock at shallow depth.
See gleization.
Empirical equation (V = (1/n)·R²/³·S¹/²) used to calculate flow velocity in pipes and channels based on diameter, slope, and roughness. The coefficient n represents the roughness of the inner wall: double-wall PEAD (smooth inside) n ≈ 0.009–0.011; single-wall corrugated PEAD n ≈ 0.015–0.022 depending on diameter; concrete n ≈ 0.013. A lower n means the same flow with a smaller diameter or a gentler slope — this is the basis for the diameter-selection charts and the drainage calculator.
Soils that make up most agricultural areas; the main subject of the Techduto guide's drainage recommendations.
The point where the main drain and laterals discharge into the ditch or water body. It's the most critical part of the system — it needs to be well built and well maintained; a clogged outlet is the #1 cause of failure. Protected by a rigid end pipe and energy dissipators.
Peat-type soils, which typically do not drain well and can subside when drained. Subsurface drainage is usually not economically viable; pasture or grasses tend to be the best option.
Compacted layer just below the implement's working depth, created by repeated machinery traffic. It blocks water and roots; it must be corrected with subsoiling before considering drainage.
Polymer used in drainage pipes for its flexibility, chemical resistance, and durability — the predominant solution in Brazil. See the resource on PEAD.
The ease with which water moves through the soil. It determines drain depth and spacing.
Iron-rich material that hardens with alternating wet and dry conditions. Common in Brazilian soils and associated with poor drainage and ochre formation.
It's a condition, not a soil type: upward pressure from groundwater in fine sands or silts prevents soil compaction, reduces its bearing capacity, and compromises the drain's service life. It requires a stable bed and, sometimes, a temporary drain before final installation.
Dense or low-permeability horizon (for example, the textural B horizon of an Argissolo or plinthite) that blocks water from moving downward and causes waterlogging even on high ground. It is the basis for calculating drain spacing.
Fraction of rainfall that becomes surface runoff (dimensionless, 0 to 1). It depends on the surface: metal roof C ≈ 0.90–0.95; paved/asphalt yard C ≈ 0.85–0.90; turf/grass C ≈ 0.15–0.40. Used in the formula Q = C·i·A to size capture systems and detention reservoirs in logistics warehouses and solar power plants.
Statistical frequency of a rainfall event (for example, 1 in 10 years). Higher-value crops justify protection against rarer events.
Structure installed at the base of steep sections to relieve excess hydraulic pressure in the drain and prevent erosional collapse.
Vertical pipe that conveys surface water into the subsurface drain; it can be fitted with flow-restriction devices.
The corrugated pipe's resistance to collapse from soil pressure and traffic loads. ABNT NBR 15073 classification: SN2 (agricultural, no heavy traffic), SN4 (moderate), SN8 (highways with trucks/trailers, maneuvering yards, railways). Techdreno DW is manufactured at SN8, with 0.8 to 6.0 m of cover under heavy traffic.
Maximum outflow rate from an urbanized area into the public system, corresponding to the pre-urbanization flow rate (without impervious surfaces). It's the limit that detention reservoirs must respect when discharging water into the network. In São Paulo, Decree 41.814/2002 and Law 12.526/2007 require retention/detention structures in impermeable areas > 500 m².
Renewal of air in the soil pores. Waterlogging drives oxygen out of the root zone; drainage restores aeration, reduces root rot, and improves plant development.
How drains are arranged in the field: systematic (parallel across the whole area), herringbone (laterals oblique to a central main, for sloped areas), random (only in the wet spots of irregular terrain), and double main (when there are obstacles such as watercourses or roads).
Deposit of fine particles (silt and fine sand) inside the pipe, reducing flow capacity. Common in sandy soils and when the drain outlet stays submerged for long periods. Self-cleaning velocity and settling boxes help prevent it.
Structure that retains the sediment carried by the water before it settles inside the pipe. Recommended when the slope doesn't guarantee self-cleaning velocity or when there is a risk of siltation.
Structures used in urban stormwater drainage for water capture and inspection. They appear in infrastructure projects, not in agricultural subsurface drainage.
Longitudinal incline of the drain that ensures gravity flow. Insufficient slope reduces self-cleaning; excessive slope can generate excess pressure and internal erosion. Reverse grade (a backward incline) should be avoided.
Controlled removal of excess water from the soil profile using buried pipes, lowering the water table down to the depth of the drains and creating a suitable environment for roots. See the complete guide.
Removal of water pooled on the surface through shallow ditches and land grading. It reduces the volume that would percolate into the soil and makes the subsurface system more efficient; recommended for flat, fine-textured areas.
Rainwater that flows over the surface instead of infiltrating. A sign of poor drainage or compacted soil.
Brazilian technical standards applicable to corrugated polyethylene drainage pipes. They define dimensions, ring stiffness classes (SN), and compliance requirements. See the detailed breakdown of NBR 15715.
Water-table management in which the same system alternates between draining and raising the water level to irrigate from below. It requires specialized design, a water source, and a water abstraction permit.
Operation that breaks up the compacted layer (plow pan) with deep shanks, restoring infiltration. It often precedes or complements drainage.
Flow velocity inside the pipe that prevents sediment deposition. The Techduto guide recommends designing for 0.45 m/s whenever possible; where sedimentation is not a risk, a minimum of 0.15 m/s is acceptable.
Damage to the soil surface caused by animal hooves on waterlogged ground; a sign of poor drainage in pastures.
Techduto's corrugated drain pipe line with a built-in filter envelope, developed for the unstable, fine-textured soils typical of Brazil — it eliminates the need for a separate geotextile application and has been validated by UFLA.
Techduto's double-wall pipe line (smooth inside, corrugated outside), recommended when higher flow capacity and strength are needed; its internal joint is sealed with DutoSeal tape.
The soil's condition to support machinery without bogging down or compacting. Drainage widens the planting and harvest window — a direct economic benefit in mechanized agriculture.
Drain-installation equipment (a trencher/plow type) that opens the furrow, shapes the trench bottom to the pipe diameter, and lays the pipe with slope control. It requires care in fine, wet soils so as not to compromise drainage performance.
Reference design train for structural sizing on heavy-haul railways in Brazil, with a load of 36 t per axle. Pipes and culverts under TB-360 railways must have their stiffness verified for this load — the justification for Techdreno DW (double-wall, SN8). DNIT's ISF-210 allows "pipe + drainage geotextile wrap standardized by the manufacturer".
Time needed for rain falling at the most remote point of a basin to reach the control section. It defines the design storm duration: tc is used as the duration to obtain the most intense rainfall that puts the entire basin in simultaneous contribution. Logistics warehouse yards have a low tc (5–20 min) — more intense rainfall and higher peak flows.
Fine sandy soils and silts that, at drain depth, allow particles to migrate into the pipe. They require a filter-need test and, generally, a filter envelope (Techdreno KC).
Device installed at the top of steep sections to prevent negative pressure (vacuum) in the drain.
Authorization from the managing agency (ANA or a state agency) to intervene in water resources. Relevant when drainage affects water bodies.
Our engineers can validate the calculations and specify the ideal solution.
Talk to a specialist Request a quote via form