Sewer design

Sewer design

Sewerage design: main stages and tasks

Designing a sewerage system is a process of developing a set of engineering and technical solutions aimed at creating an efficient, reliable and environmentally friendly system of collection, transportation, treatment and utilization of wastewater.

The main factors in calculating the need for sewerage

When designing a sewer system, it is important to consider various factors that affect its size and complexity. These include:

  • Population and facility needs: Depending on the population and the use of the building (residential, commercial, industrial), wastewater volumes are determined.
  • Climatic conditions: In regions with intense rainfall or flooding, additional measures are required to prevent clogging and overflows.
  • Geographic and geologic features: Terrain and soil type affect pipe laying methods and equipment selection.

Methods for calculating sewerage demand

Various calculation methods are used in the process of determining the size and capacity of a sewage system. One of the key ones is hydraulic calculations, which help to determine the volume of wastewater, its velocity through the pipes, and the required width and slope of the pipes. In addition, calculations based on national and local building codes and standards play an important role. These codes define the basic parameters that a sewer system must meet, including its safety, efficiency, and environmental compatibility.

Consequences of sewer design errors

Design errors can lead to serious consequences:

  • Repair and upgrade costs: An underpowered or improperly designed system will require costly redesign.
  • Environmental problems: Improper operation or accidents can lead to environmental pollution.
  • System malfunctions: Clogs, overflows and failures can seriously compromise the comfort and safety of living or working in a building.

Thus, each phase of sewer system design plays a critical role in ensuring its efficiency and reliability.

Design Requirements

The functional requirements of sewer pipes determine their ability to perform their tasks efficiently and reliably. The basic requirements include:

  • Strength and durability: Pipes shall be resistant to mechanical damage, corrosion, wastewater and weathering.
  • Hydraulic efficiency: Pipelines shall provide uninterrupted wastewater discharge with minimum pressure losses.
  • Environmental safety: Pipe materials shall not release harmful substances into the environment and shall be suitable for prolonged contact with wastewater.

Rules and regulations for the arrangement of utilities

When designing and constructing sewerage systems in Ukraine it is necessary to comply with a number of regulations:

  • Construction norms and rules of Ukraine (SNiP): These documents establish general requirements for the design, construction and operation of sewerage systems.
  • Local building codes and standards: Additional requirements may apply in different regions due to local climatic and geological conditions.
  • Environmental regulations: Specific requirements aimed at minimizing the environmental impact of sewerage systems.

Design of internal and external sewerage systems

Sewerage system design includes the development of both internal and external drainage systems. This process requires special attention to detail and strict adherence to technical norms and standards.

What does a wastewater system design include?

The wastewater system design includes the development of a set of documentation that covers several important aspects. The key element is a plan of location of pipelines and plumbing equipment. The project also involves making calculations to determine the capacity and diameter of pipes to ensure they meet the needs of the facility. An important part of the project is the selection and specification of materials and equipment used in the system. In addition, the project includes the development of schemes of connection to centralized sewerage systems or, in the case of autonomous systems, detailed plans for their organization and operation.

The design process can be divided into several key stages:

  1. Pre-planning: Study of requirements, definition of the overall concept and strategy.
  2. Specification development: Finalization of details, material and equipment requirements.
  3. Development of design documents : Creation of detailed drawings and schematics.
  4. Project coordination and approval: Obtaining all necessary permits.

It is important that each sewerage project includes technical calculations and justifications, pipe and equipment layouts, a list of required materials and equipment, and instructions for installation and operation.

When selecting materials, consider their strength and resistance to corrosion, compliance with environmental standards, compatibility with types of wastewater, and their durability and reliability.

Creating a project and estimate for the assembly of internal sewerage system begins with the preparation of the technical specification, calculation of the necessary materials and works, and is completed with a detailed cost estimate.

In the design of the external system, special attention is paid to the scheme of drainage and drainage, the arrangement of manholes and pumping stations, as well as measures to prevent flooding and overflow.

Projects for industrial facilities are characterized by high loads on the sewage system, specific requirements for wastewater treatment and disposal, and the need for integration with other engineering systems.

Selection and sizing of pipes

The following factors should be considered when selecting sewer pipes:

  • Capacity: Pipes must be able to provide uninterrupted sewage disposal, taking into account the volume and flow rate of wastewater.
  • Material: It is important to choose materials that are resistant to corrosion, mechanical damage and wastewater (e.g. PVC, polypropylene).
  • Diameter and wall thickness: Determined based on design loads and hydraulic requirements.
  • Resistance to external conditions: It is important to consider climatic conditions and the likelihood of mechanical impact.

Pipe size (diameter)

Pipe purpose



32 mmInternal sewerage for water drainage from sinksPVCUsed in residential and office buildings
50 mmInternal sewer for waste water drainage from showers and bathtubsPVCCommon in residential buildings
110 mmExternal sewerage for waste water disposalPolypropyleneUsed for connection to central sewerage networks
160 mm and moreMain sewer mainsReinforced concrete, asbestos cementUsed in industrial and municipal applications

This table gives a general idea of pipe sizes and applications. However, keep in mind that choosing a specific pipe size and material depends on many factors, including site specifics, regulatory requirements, and local conditions.

What is needed for sewer construction

When connecting to the central network

  • Compliance with standards and codes: Ensure that the system complies with local and national building codes.
  • Coordination with local utilities: It is important to coordinate plans and connections with the responsible organizations.
  • Ensure proper slope of pipelines: For efficient drainage of wastewater.

When installing stand-alone systems

  • Selecting the type of system: It must be determined whether it will be a septic tank, cesspool or other wastewater treatment system.
  • Consideration of environmental regulations: The system should minimize the impact on the environment.
  • Preparing the installation site: Ensuring accessibility for maintenance and compliance with technical requirements.

Proper selection and sizing of piping plays a key role in creating an efficient, reliable and durable sewer system that can meet the needs of the site and meet environmental standards.

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