The process of digging a trench for sewerage and the rules for laying pipes

In order to guarantee efficient wastewater management for communities and buildings, trench excavation for sewerage requires meticulous planning and execution. Marking and surveying the area where the trench will be dug is the first step in this process. In order to avoid subterranean utilities and to make sure the trench is dug in the proper place, this step is essential.

Following the marking of the area, trench-digging equipment such as excavators and trenchers is used to start the excavation process. Local building codes and the requirements of the sewer system being installed dictate the trench’s depth and width. In order to accommodate the sewer pipes and enable appropriate drainage, it is imperative to maintain the proper dimensions.

Soil conditions are closely monitored during excavation. To avoid collapse, different types of soil might need different methods or more support. During construction, safety precautions are taken to protect workers and guarantee the integrity of the trench, such as shoring or trench supports.

The sewer pipes must be laid after the trench has been excavated to the necessary depth and width. These pipes are carefully positioned along the trench bed and are usually composed of sturdy materials like concrete or PVC. For wastewater to flow efficiently towards treatment facilities or septic systems, proper alignment and slope are essential.

After the pipes are installed, they are joined using joints and fittings made to stop leaks and guarantee a smooth sewage flow. Before backfilling the trench, the connections are tested to ensure their integrity and functionality. Backfilling is the process of replacing the earth that has been carefully dug up around pipes to provide stability and protection from damage.

To minimize settling over time, the trench is compacted at the end. Maintaining the structural integrity of the sewer system and reducing the chance of ground subsidence are two benefits of proper compaction. This thorough trench excavation and pipe laying procedure is essential to the establishment of dependable sewerage systems that satisfy environmental regulations and promote public health and hygiene.

When to use?

Without a sewer system, a home cannot be designed to provide normal conditions for a comfortable existence. Waste is moved to the external mains, which leads to the septic tank, after passing through the internal pipeline.

An infrastructure like this can last for several decades if the pipes are installed in trenches properly. First, trenches are dug in order to organize a sewer system.

There are various circumstances in which rutting is required:

• pipes should not be located in a visible place on the site;
• the distance from the object to the septic tank is large and it will not be possible to lay a pipe on the surface;
• climatic conditions;
• compliance with regulatory requirements;
• protection from mechanical damage;
• saving land on the site.

There are instances in which trench pipe laying is not practical. The severe weather that a tenth of the nation experiences has an impact on this.

For instance, permanent permafrost develops in areas where the yearly average temperature is too low.Underground sewer pipes could freeze. They are positioned on the earth’s surface as a result. For repairs, the above-ground location is also practical.

Additionally, if the outer section is small, it makes no sense to lay a pipe underground. Sewer pipes can then be installed above ground and directed to the septic tank.

Parameters and requirements

When excavating a trench and installing pipes on their own, they follow the guidelines in SNiP 2 collection.04.03 from 1985. Clear guidelines for trench depth, width, and reinforcement are provided in the regulatory document.

The prerequisites for a private residence are as follows:

• pipes are laid at a depth of 0.8 to 1.4 meters in a trench;
• the freezing depth in central Russia is 300 mm, so the pipe should lie 30-50 cm below the freezing level;
• from the ground surface to the pipe itself must be at least 70 cm.

The minimum values of the system level are raised by one meter when the system is organized beneath a concrete platform and in areas where there is continuous traffic. This is required to lessen the possibility of soil subsidence brought on by heavy loads.

Regulations state that the type of soil to be dug into should be taken into account before beginning any trench work. For instance, compared to sandy soil, soil with a high clay content freezes more slowly. The highest level of freezing is found in gravel-rich soil. The area is constantly in focus. Cities have varying degrees of soil freezing.

The minimum trench depth for sewerage should be 50 cm, according to SNiP. The trench walls are reinforced when the pipeline is dredged by one meter.

Digging methods and necessary tools

There are two approaches used to dig a trench:

• manual;
• mechanized.

The value of manual earthworks is higher than that of mechanized ones. A rectangular or trapezoidal shape is typically used when making an open excavation in the earth.

It is preferable to employ manual labor to achieve a particular shape. When it is not possible to transport equipment to the job site, this approach is used. The road in front of the house is too small to accommodate an excavator or bulldozer.

The type of soil and the caliber of the builders’ work both affect how effective the manual method is. It is less likely to be dug up normally if it is too loose. Since workers cannot dig normally in inclement weather, they also select favorable weather for manual digging.

A mechanized trench-digging method is more dependable and faster. Though it is only feasible if the bulldozer can drive to the construction site, it is more accessible than manual labor. The computation of the cost is predicated on the amount of time invested in the task. In the event that significant soil development is anticipated, the mechanized approach will be pertinent.

Always use a shovel and bayonet when performing manual labor. Soil is dug up with a bayonet tool and collected with a shovel tool.

Using machinery to dig entails:

1. excavator;
2. bar machine;
3. mounted trencher.

Trapezoidal trenches can be dug with an excavator; working in frozen or heavy soils calls for a digging machine; and narrow trench widths call for a mounted trencher.

The process and technology of digging a trench

Consideration must be given to the width of future pipes before excavating. You must allow the worker to be at the bottom of the trench in order for the sewer installation to go properly. Its depth is ascertained to accomplish this.

The actual digging procedure is easy:

1. Shape selection trenches. There are several shapes for sewer trenches: rectangular, trapezoidal and mixed. Rectangular is used on dense soils when strengthening the walls is not required. Trapezoidal is needed when buried at a distance of more than 1.5 meters. A mixed type of trench is suitable when the pipe needs to be located at the groundwater level.
2. Width selection. This indicator is determined based on the diameter of the pipes used. It is also important to consider the width of the tool for work: for manual work – shovels, for mechanized work – the width of the bucket. Standard sizes from 0.5 to 0.8 meters depending on depth.
3. Marking trenches. Choose the shortest route for the route. Pegs are used for marking and a string is pulled between them. The beginning of the route will be where the sewer leaves the house, and the end will be where the septic tank is located. If there are obstacles on the path of laying the route – trees, objects, then they are bypassed at an angle of 90 degrees. This makes pipe joining easier in the future. Before marking and digging, be sure to cover the lawn grass with a tarpaulin and also protect other objects from damage.
4. Manual digging. First remove the top turf layer. Then the soil is loosened with a bayonet shovel and removed using a shovel. When digging by hand, it is better to use a stepwise method, gradually going deeper inside. When the trench has reached the desired width, but is not yet so deep, use a cutting shovel. An assistant is needed here: one worker ties a rope to the base of the shovel, and the second pulls the soil to the surface.
5. Mechanized digging. Specialized equipment arrives at the site and is capable of digging a large number of trenches in a few hours.

Diagram of sewage in the trench:

The developed soil is left above ground, where it will be useful for backfilling sewage pipes in the future.

What pipes are used?

There are various types of pipes that are used when installing a sewer system on a site.

Pipe type	Features of use
Cast iron	Strong and durable pipes, affordable and easy to install. Difficulties may arise when connecting joints. Cast iron corrodes over time and is heavy. The inner surface of cast iron will not be smooth, which will make it difficult to transport waste to the drainage pit
Asbestos-cement	They have a smooth surface, so no blockages form. They are easily mounted using couplings, have less weight, but are fragile and can break during transportation
Polymer	High strength, low weight. One person can lay such sewer pipes. Easy to connect, excellent sealing. Available in PVC, HDPE and polypropylene
Corrugated	They withstand dynamic loads well and are resistant to freezing, but can become deformed at too low temperatures.

Plastic pipes are advised by experts for sewer installation. In this instance, the number of bathrooms in the home determines the cross-sectional diameter. A pipe with a diameter of 110 mm is appropriate for two toilets; a pipe with a diameter of 160 mm must be installed for three or more bathrooms.

Laying process and technology

Excavation work is the first step in laying sewer pipes. A trench is dug, the pipeline is installed, and finally the soil is backfilled. The entire sewer pipe system needs to be cut and connected by workers after the trench is dug.

There are multiple stages to the procedure:

1. Installation begins from the point where the pipe exits the building.
2. Pipes are laid along the trench, their sockets should be directed in the direction opposite to the flow of wastewater.
3. To connect the pipeline, the sockets are cleaned and rubber O-rings are installed. Place a mark on the pipe and measure the level at which the socket enters the pipe. Use lubricant to make insertion easier. To compensate for deformations, the pipe is not inserted completely, leaving a gap of 1 cm.
4. For turns, bends of 15 and 30 degrees are used.
5. Inspection wells are installed – this is necessary to prevent blockages and allow them to be cleaned.
6. Insulation is carried out if provided for by the project.
7. Backfilling of the trench occurs gradually, first 10-15 cm are covered with sand. It is compacted along the edges of the pipe, but not compacted on the pipe itself. Next, the sewer is filled with ordinary soil without large stones.

Diagram for sewage installation:

Make sure that the pipe slopes in the direction of the septic tank during installation. Wastewater will flow more effectively the closer the slope indicators are to the averages.

The absence of slope will cause the system to silt up and cause blockages. For instance, the trench for the pipe should be 50 cm deep when leaving the house, and 1.5 meters deep when connecting to a septic tank.

Is it possible to lay sewer pipes and water supply at the same time??

Water pipes are occasionally installed alongside sewage systems. If the site’s layout prohibits them from excavating multiple nearby trenches, they take this action. This is not permitted in other circumstances.

Justifications for not allowing concurrent laying:

• there must be a distance between the pipes;
• water pipes must be insulated;
• construction of the main water pipeline.

Installing a sewer pipe close to the main water pipeline is strictly prohibited. It is best to install a sanitary protection strip close to it. However, in private homes, it’s common practice to install sewage and water supplies in the same trench at the same time.

Although SNiP regulates this, it is crucial to adhere to the project standards while construction is underway. As an illustration, you could dig one trench and install two pipes in it. In this instance, there should be a minimum of 1.5 meters separating them. As a result, a trench must be dug that is at least two meters wide—quite a bit for tiny spaces.

In the event that it was decided to install two pipelines side by side, you must make sure that the sewer pipe slopes at least 40 centimeters in the direction of the septic tank. Since a slope is not required to lay the water pipe, this is a challenging task. The pipe’s depth is one of the drawbacks and variations. It must be at least two meters for wastewater and less for a water conduit.

Advantages and disadvantages

The process of digging trenches for sewer installation has both advantages and disadvantages.

Advantages	Flaws
Compared to the trenchless installation method, this method is cheaper	It is impossible to carry out work without opening the soil: you will have to remove fertile soil and uproot vegetation on the site
The sewerage system will be covered with a layer of soil and will not be damaged	Material and time costs for digging a trench increase
Self-execution	You can not do work in the winter season

If underground installation is the best option for a sewer system, there are more opportunities than above-ground installation. You can correctly arrange the slope and adhere to all rules and specifications in this way.

Problems and errors

There are a number of construction errors that could have detrimental effects on the way the sewer system functions:

1. No soil compaction. If this is not done, then in the future there may be erosion by groundwater, as well as disruption of the integrity of communications due to heavy rainfall.
2. No slope. If the slope has not been completed, then wastewater will not flow into the septic tank. The slope should be 1-2 cm per meter of pipeline. If there is no slope, sewage will quickly clog the system.
3. Lack of well. It is definitely recommended to install an inspection well – for cleaning and repairing the system.

Another mistake is made when laying the wastewater and water supply pipes in a single trench. In this case, it’s crucial to abide by the regulations and technology; the pipes should be 150 cm apart.

How much does the work cost??

Digging a trench by hand will cost more than using mechanized labor. For instance, one cubic meter of excavated soil will typically cost between 1000 and 2000 rubles for manual labor. The cost is lowered multiple times when a bulldozer is used for the excavation. One cubic meter of digging with a bulldozer is expected to cost between 300 and 400 rubles.

The diameter of the pipeline and the technique used to install the sewerage system determine the cost of installation. For instance, employing 200 mm-diameter, high-strength cast iron pipes will set you back 32,000 rubles per linear meter when materials are taken into account. Additionally, working with pipes made of reinforced concrete will save you 20% of the cost.

It is essential to comprehend the procedure for excavating trenches for sewage and to follow the guidelines when installing pipes in construction and remodeling projects. This article explains how to dig trenches step-by-step, making sure they are the right width and depth to accommodate sewer pipes. It also covers the fundamental rules for pipe laying, such as materials, connection techniques, and gradient considerations. Builders can guarantee effective drainage systems that satisfy safety and regulatory requirements by carefully adhering to these procedures, which are crucial for the completion of building and renovation projects.

Useful video

We would like you to view the following video about the subject of the article:

Step	Description
Planning	Determine the path and depth of the trench based on the sewer layout and local regulations.
Marking	Use stakes and string to mark the trench path, ensuring a straight and accurate line.
Excavation	Start digging the trench, keeping the depth consistent and maintaining a slight slope for proper drainage.
Base Preparation	Level the trench bottom and add a layer of sand or gravel to create a stable base for the pipes.
Pipe Laying	Place the sewer pipes in the trench, connecting them securely and ensuring they follow the slope.
Backfilling	Cover the pipes with soil, compacting it gently to avoid damaging the pipes.
Final Inspection	Check the trench and pipes for any issues before completing the backfill process.

The first step in ensuring adequate drainage in your home is to precisely dig a trench for sewerage and install pipes in it. By taking the recommended actions, you can avoid problems like leaks and obstructions in the future, which can cause serious harm and expensive repairs.

During this process, it’s crucial to follow the suggested guidelines and any applicable local laws. This guarantees not only the effectiveness of your sewage system but also the project’s safety and compliance with environmental regulations.

To avoid any potential hazards, always use the proper tools and materials and take the required safety precautions. If you are uncertain at any point, seeking professional advice can give you the know-how required to finish the task successfully.

You can create a dependable and long-lasting sewerage system that will improve your home’s general hygienic conditions and functionality with careful planning and attention to detail.

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