Rehabilitation of non-accessible sewers, pipelines and manholes

As part of rehabilitation projects, we consider all requirements for an Integrated Sewer System Management. In accordance with EN 752, this means a coordinated management of planning, dimensioning, construction, rehabilitation, operation and maintenance of all sewers, manholes and structures in a catchment area, taking into account all performance aspects. In this sense, at STEIN Ingenieure planning is a process that always requires an understanding of both the existing and the planned drainage system. Only with this understanding can measures be developed which ensure the hydraulic, environmental, structural and operational performance under consideration of future conditions and economic efficiency and the specified performance requirements.

The aim of our rehabilitation planning is to rehabilitate identified defects in such a way that the structural nominal state of the drain and sewer system is maintained or restored or improved in accordance with the requirements and the value of the drain and sewer system is increased as much as possible. In this respect our services include:

  • Review of existing information: Data management, i.e. checking the data for completeness, compatibility, accuracy, consistency, plausibility and up-to-dateness
  • Assessment of data: defect, condition and fabric deterioration evaluation of sewer objects
  • Development and definition of rehabilitation strategies and rehabilitation targets in the form of a rehabilitation plan
  • Development of integral solutions and their evaluation
  • Selection of the optimal solution (development of possible solutions and definition of the necessary measures in the form of a rehabilitation concept)
  • Selection of the optimal solution (development of possible solutions and definition of the necessary measures in the form of a rehabilitation concept)
  • Action planning
  • Implementation of the measures
  • Control, documentation and approval of the measures.

Rehabilitation of accessible sewers and structures

The rehabilitation of accessible sewers and structures is one of the core competences of STEIN engineers. As a result of our many years of activity in this specialist field, we can already draw on a wealth of experience of over 200 km of rehabilitated accessible sewers.

In rehabilitation planning of large profile pipes made of cast-in-place concrete or brickwork, the established structural condition assessment standards often cannot be applied or are simply insufficient. An optimal economic rehabilitation is only possible if the actual stability of the structure is known. We have therefore developed and established in Germany an extended method for condition assessment and evaluation especially for large diameter sewers and pipes.

For the first time ever, precise statements regarding the existing stability and structural condition of these essential civil structures (residual load bearing capacity) can be made – thus allowing for the achievement of considerable cost savings throughout the rehabilitation process.

Figure: Illustration: Inspection of a large profile sewer (left), static determination of the stability (middle), renovation of a large profile sewer (right)

Based on walk-through inspections, we record the condition of the pipes or sewers and document all defects relevant to stability and serviceability. If necessary, we carry out investigations of the pipe walls and the subsoil. When taking samples, we naturally keep impairments to stability, operation and surface traffic as low as possible.

We use FEM calculation algorithms to determine the stability of the sewer line. They are designed for all required assessments, and also consider the residual load bearing capacity of the inspected line or sewer. Existing geotechnical problems are identified and solved through deformation and stability calculations of the lines, as well as the non-linear interactions between soil and structure.

This information forms the basis for a technically practical and economically optimised rehabilitation plan resulting in a reduction of investment risk for the client.

Private drainage systems

The property owner is responsible for private drainage systems. However, competent citizens as well as building societies are usually not able to find their way through the jungle of technical possibilities and legal regulations. Thus, the support by local authorities is increasingly needed; unfortunately they often lack the personnel to deal with the issue.

STEIN Ingenieure is the partner for all questions concerning private drainage for network operators and local authorities, property owners and building societies!

  • New construction of private drainage systems
  • Rehabilitation of private drainage systems
  • Small wastewater treatment plants.

New construction of private drainage systems We plan private drainage systems according to the latest technical, scientific, legal and environmentally relevant standards. This includes applying storm water management concepts (utilization, retention, seepage and treatment) to create a natural, ecological and economically optimised rainwater drainage system with the potential to reduce your sewer charges.

Rehabilitation of private drainage systems

We offer you rehabilitation planning using both open-cut and trenchless methods, as well as the assessment of your drainage system and guidance in obtaining leak tightness certification in accordance with local legislation.

As part of our planning process, we check for possible ways to optimize your rainwater management system through storm water utilisation, retention, seepage and treatment. In this way you ensure a natural, ecological and economically optimised rainwater drainage system that has the potential to reduce your sewer levy costs.

Network operators and local authorities

Ihre Wohnungsbaugesellschaft ist nicht nur für die Gebäude und Grundstücke zuständig, sondern auch Betreiber der zugehörigen Grundstücksentwässerungsanlagen. Daher sollten Sie wissen, welche kommunenspezifischen Vorgaben bestehen, nach welchen Prioritäten die Grund- und Anschlussleitungen der Immobilienobjekte am besten zu untersuchen sind und wie Kosten durch Koordination und Synergieeffekte bei der Untersuchung und ggf. Sanierung der Leitungen einzusparen sind. Hierzu beraten wir Sie gerne.

Property owners

You know that you are responsible for the proper construction and operation of your private drainage system, but you don't know how to find a reliable, competitive solution for the inspection and possible rehabilitation of your sewers and laterals? You need consulting services, assistance with the selection of suitable providers, on-site monitoring of the works, and tips for the reduction of costs?

We support you with the:

  • Evaluation of offers from specialized companies for the monitoring of your property drainage
  • Testing and evaluation of the results of the CCTV inspection and leak tightness test
  • Examination of the rehabilitation proposal prepared by the specialist company commissioned for the monitoring with regard to the selection of procedures and costs
  • Development of a rehabilitation proposal based on the results of the CCTV inspection and leak tightness test
  • Expert opinion in legal disputes.

Service areas:

  • Non-accessible sewers, pipelines and manholes
  • Non-accessible sewers, pipelines and manholes
  • Property drainage


  • SP1. Establishing the basis of the project
  • SP2. Preliminary design
  • SP3. Final design
  • SP4. Building permission application
  • SP5. Execution drawings
  • SP6. Preparation of contract award
  • SP7. Assisting award process
  • SP8. Project supervision
  • SP9. Project control and documentation

Special services:

  • Rehabilitation of culvert and pressure pipes
  • Rehabilitation of basins
  • Concrete repair