Root invasion

Root penetration is a biological process that can take place on encryption or waste lines, such as in sewers or sewage manholes. Root penetration occurs because roots within their lines and pipe joints space available, which is not present in the backfill and bedding material of the pipes, due to its compaction.

The basis for the occurrence of root penetration, the presence of the root cap cells of the root tip and their reaction to the soil conditions encountered at each growing area. The cell walls in the root cap partly dissolve on, the cells lose their cohesion and are shifted against each other. The root tip is thus not a rigid drill, but has a soft, gelatinous tip. The root tip is pushed through the root pressure from the initials into the substrate. By sliding the apex of the root cap cells, the apex acts as a hydrostatic drill is driven into the pores between the particles of the soil. The root cap is formed, extending a channel into which the root is forced. The path of the roots to the line is determined, in that the elastic cover is changed in root growth of the roots through the bottom in shape. The root cap and thus also the root is deflected in the direction from which the root of the smallest pressure is met with by the soil particles. The root gives himself space where the surrounding soil is the most compliant. Erroneously, it was assumed ( until about 1999 ) to find the root by moisture or nutrients as the sole cause for growing roots in earlier literature.

Growing roots in the urban conurbation

The sealing of land in the urban environment may have the consequence that the entry of oxygen is reduced into the ground. Roots are, like all plant parts to a functioning respiration (oxidation) of carbohydrate-rich compounds instructed to generate energy. The oxygen required is located in a natural soil structure in soil air and can be picked up there by the roots. By compaction of a soil at its void space, and the amount of oxygen contained therein decreases. The growth of roots in lines is low porosity backfill materials, such as flowable filling materials, referred to in the case of a product as a liquid bottoms is prevented.

Technical Background

The most common technical solution for connecting sewer pipes make connections dar. In this system, the pointed ends of the respective tubes with the socket of the next pipe or with separate sleeve couplers are connected. They offer over other systems the advantage that they are relatively easy to produce, even under difficult site conditions. From root intrusions affected lines were usually by digging a trench, then backfill and compaction of the backfill material incorporated laid underground [ EN 1610 ]. Because of the need for the mating geometry remains at all connectors, an annular gap, which forms the inlet opening for the roots in the annular space located behind it. For bonded or welded pipe joints, as it is typical for example in supply lines, root penetration occurs only rarely, because the ring gaps occurring in this case are not accessible due to the adhesive or welding. In general, however, root penetration may also occur with glued and welded pipe joints.

Examination of the root strength according to DIN EN 681 4060/DIN

From a technical point of view considered, all pipe connections today sold in Germany are resistant to root penetration. The root resistance of pipe joints applicable in Germany according to DIN 4060 detected when the pipe connection, a leak test with over-or under pressure under shear load. The mechanical properties of the seal are tested according to DIN EN 681. The geometry of the seal and the resulting influence on the pressure generated in the pipe joint, however, are not considered. Biological aspects are not taken into account in the assessment of root strength, so that only highly idealized mechanical methods are used to detect the root strength of pipe joints. The test criteria described in DIN 4060 are to be considered as minimum requirements. Depending on the pipe materials and their pipe connection or load class exist the same or higher standards as DIN 4060 in further pipe standards.

Consequences of growing roots in sewers

Roots grow into the annular space and ultimately in the cable cross-section of the relevant lines. As a result of growing roots in sewer lines can root pad ( outflow obstructions ), leaks, cracks or damage to the cable may occur. The error-free operation of the relevant sewage plant is in many cases no longer possible, since the growth of the roots continues, as long as the growth of the tree stops.

Mechanical removal of root penetration

In accessible ducts can be a root removal to be performed manually. The mature roots are removed with the use of tools ( chisels, knives or spades ). In non- accessible sewers mechanical methods are used. Roots extend generally from the pipe connections forth in the cross-section of the respective line. Many cases they have grown through the pipe connection in the region of the apex and remain fixed there. The roots hang down in the line in the form of a curtain. They should be removed with the help of rotating tools, such as chain knocking or milling. The mechanical removal of root penetration is to eliminate acute problems ( blockages of sewers ). By severing of roots during mechanical root removal the re-growth is stimulated. A lasting solution to offer only the elimination of root penetration in conjunction with a professional restoration on this line.

Chemical removal of root penetration

The elimination of growing roots in sewer lines is possible with the help of herbicides.

Avoid root penetration

The relationships between root growth and the realities of underground lines were first described in the context of a research report. Roots grow not only in accordance with the state of the art leaking pipe joints, but instead they overcome " tight " pipe connections and the hypothesis "If a pipe joint is tight, then also resistant to root is " not true. Low-porosity soil areas, as they are created by the installation of flowable backfill materials, for example, are not durchwurzelbar. Controlled incorporation of low pore filling materials is growing roots in pipes or ducts can be avoided. Roots grow usually preferred in areas, which are easily durchwurzelbar. These areas meet the demands of the roots with respect to water availability ( soil water ), oxygen supply ( soil air ) and a small, mechanical resistance (soil structure). Root growth is optimal when these requirements are met. Roots, find the location of the tree on ideal conditions that do not grow in line routes and thus do not lead to root penetration.