Following the installation of sewer pipes, the sewer sanitary trench must be backfilled. The method and degree of compaction, as well as the equipment and sequencing of sewer trench backfilling, are all described. The backfilling operation necessitates extreme prudence and should be carried out correctly.Sewer Sanitary Trench Backfilling The following points about sewage sanitary trench backfilling are discussed:
Consideration for backfilling Sequence of backfilling The degree of compactness Considerations for Backfilling a Sewer Trench Selection of Compaction Equipment While backfilling is being done, sewer sanitary pipe disposition and degeneration must be avoided. This can be accomplished by carefully selecting the appropriate procedures and machines for the job. The breadth of the trench, the characteristics of the excavated materials, the degree of compaction, and the excavation approach all influence the backfilling procedure.
Backfilling of Sewer Sanitary Trench in Order
Backfilling of Sewer Sanitary Trench in Order Backfilling usually begins once concrete structures such as arches and cradles have reached sufficient strength and can resist the imposed backfill material loads without harm. The backfilling of a sewage sanitary trench consists of three primary layers: embedment, final backfill, and finish grade material.It should be emphasised that each layer has its own set of issues that must be taken into account. The following parts go over these sewer sanitary trench backfill zones:Backfilling Embedment Zone-wise is the first layer, and it consists of the first backfill and haunching. The selection and placement of embedment materials is the first step in the backfilling process. From the foundation to 30cm above the pipe, the lower backfill layer is extended.
To avoid dislocation and deterioration of installed pipes, this zone should be set by hand or with appropriate machines and carefully compacted.Granular material is preferred because it does not necessitate extensive compaction efforts to achieve the desired density. When using flexible pipes, the positioning of haunching that reaches up to the spring line should be done with extreme caution.In the case of a high water table, it is necessary to reduce voids to the bare minimum in order to minimise soil movement.Zone of Intermediate Backfill The necessary compaction degree often influences the choice of intermediate backfill material. However, in areas prone to frost heave, it is recommended that excavated material be used.
Material Zone in the Upper Backfill
The degree of compaction is determined by the project’s location; for example, in a traffic region, 95 percent modified proctor compaction is required; in metropolitan areas, 90 percent compaction is required; and in rural areas, just a minor degree of compaction is required.Material Zone in the Upper Backfill The type of needed final grade, for example, whether the area will be used for agricultural or paved, determines the depth and compaction degree of the upper zone. In the latter instance, the upper zone’s elevation must be properly established in order to sustain different pavement layers. In the first situation, a top soil layer of 100mm depth must be given. Due to water accumulation in the sanitary sewage line, it may float before and during backfilling.
The degree of compaction required for sanitary sewer trench backfill is determined by the project’s location. For example, if the area is authorised to be paved, significant compaction is required; but, if the region is not densely populated or subjected to heavy traffic, less compaction is required. In other cases, such as along outfall sewers in open country, natural settlement of backfill material may be sufficient. The degree of compaction is calculated using the American Association of State Highway and Transportation Officials’ specifications. In the laboratory, the modified proctor test is used to determine optimum moisture content, and several tests are available for determining compaction value in the field.
Compaction Equipment for Backfilling
This section looks at how to choose the right compaction equipment based on the type of backfill material and the amount of space available: Cohesive Materials Compaction Equipment Small particles and minimal internal friction are two qualities that characterise cohesive materials. The strength of the adhesive force between cohesive material particles makes reshaping and compacting the particles challenging. As a result, it is recommended that heavy-duty equipment be used to counteract adhesion forces, reposition particles, and achieve the desired compaction.Pneumatic tamper, motor driven rammer, and self-propelled rammer are recommended for restricted areas, but sheep foot roller can be considered for large areas, and dozers and loaders can be employed if necessary.
Otherwise, the compaction result will be poor and unacceptable. Backfill material should be close to optimum moisture content and multiple lifts should be used.If the moisture level of the backfill material is too high, it should be dried to a compactible moisture content. This moisture content can be achieved by drying the material, mixing it with granular material, and crushing it.Backfilling a Sewer Trench using Compaction Equipment Cohesionless Material Compaction Equipment Low adhesion force and high internal friction describe cohesionless soil. The reduction of surface friction between particles, rather than moisture content, improves the degree of non-cohesive soil compaction. As a result, vibrator compaction is the best machine for compacting cohesionless backfill material and achieving an adequate compaction degree.
Borrow Material Compaction Equipment
If the trench is wide, it is required to employ a vibrating roller. In a narrow trench, a vibratory plate would offer adequate compaction. If a high degree of compaction is not necessary, the vibration impact of a dozer or a truck loader is a good option to consider.Borrow Material Compaction Equipment When the excavated soil does not meet the specifications for usage as a backfill material, borrow material is used. So, in this scenario, it may be determined to use a material with good properties, whether it is cohesionless or cohesive.It is important to be aware that the use of borrow materials may create changes in ground water levels, so this possibility should be considered while using borrow materials.
The optimal bucket width to utilise when working with a backhoe is determined by pipe size, trench depth, and local familiarity with soil conditions. The trench width, on the other hand, should be kept to a minimum to save time and potential site damage, but large enough to allow appropriate installation, i.e., enough area to make up pipe joints, tamp backfill under and around the pipe, and preserve the trench wall.In general, the trench width should be 0.3 to 0.6 m less than the pipe diameter. It’s critical to maintain the trench width as short as possible, especially under paved sections, to reduce the traffic load that’ll be transmitted down through the backfill and exerted.
Backfilling of Sewer Sanitary
Excavated debris should be heaped at least 0.6 metres away from trenches that are shallow. It must be piled even further away in deeper ditches. This reduces the chance that dirt or stones will be kicked into the construction or that excavated material would fall back. There must also be enough room for the workers to wander around the construction. Someone tripping and falling into the trench is also prevented by a safe deposit distance. Furthermore, the weight of the excavated material must be taken into account. It is possible that if it is not properly laid, the trench will cave in.The trench’s bottom should be dug as near to the stipulated grade as possible to give a continuous, even support for the soil.
The house lateral normally goes from the front or back of your property to the street, where it links to the public sewer system via a Y-shaped pipe known as a wye. A cleanout is a hole in the lateral that permits any material or obstacles that can restrict the flow of wastewater to be removed.
Typical pipe materials for small diameter sanitary sewers (8″ through 24″ diameter) include PVC, vitrified clay, and ductile iron.
Maintenance of sewers consists of the removal of obstructions, cleaning of sewers including sewer appurtenances.
The sanitary sewer system contains sewer laterals that connect individual buildings to main sewer pipelines.