Sewer Renovation Research Articles

SEMI-COMPOSITE STRUCTURES FOR SEWER RENOVATION

In the composite pipe construction method defined in the Japan Sewage Works Association's Design and Construction Guidelines for Sewer Pipe Rehabilitation, a liner pipe is constructed inside an existing sewer and the annular space behind the liner is filled with cementitious grout under pressure to form a highly integrated structure. The Guidelines for sewer renovation in Japan define a composite pipe as a composite structure that requires complete integration between liner materials and an existing pipe. However, in general, owing to the refinement of the small and enclosed working space inside sewers and the significant extension of the pipe to be renovated, mechanical shear connectors are not used to rigidly connect a renovation layer with an existing pipe. To fully explore the advantages of the composite pipe method in sewer renovation while maintaining safe design, a semi-composite structure has been applied in the renovation design of aging sewers using nonlinear FEM analysis for more than 50 sewers (over a total length of 300 km), primarily in big cities in Japan. This paper focuses on the mechanics of the structure.

Eco-technique of sewer renovation using composite shells: structural analysis

An eco-technical renovation of the sewage system is developed in this paper; this technique involves incorporating into the existing sewer a series of jointed prefabricated sandwich or composite shells. The purpose of his study is to determine the structural shell deflection, the high displacement areas and to validate the non-failure criterion for each ply constituting the inner and outer laminate facings. The numerical results were obtained at low cost by using the finite element method. Studies have focused on structural analysis of a typical shell unit with an ovoid form (egg-shaped section) when it is subjected, during annular space filling operation, to pressure forces generated by wet concrete. To ensure the safety of the composite shell structure, Tsai-Hill criterion function is applied and results are presented for the most stressed plies Keywords: sanitation; sustainable development; composite collector en composite; sandwich shell; finite element approach

Quality Assurance of CIPP Liners According EN ISO 11296-4

Using Cured-in-Place-Pipes for sewer renovation has developed to a common and widely used trenchless technology for pipes and especially sewer rehabilitation in different countries in last 20 years. This process was accelerated with the standardization of the CIPP liners and also due to intensive quality assurance which is highly developed especially in Germany. The quality control and quality assurance is generally ruled according EN ISO 11296-4 which is not fully sufficient as our research has shown.

A New Sewage System with Best Value Procurement

The adoption rate of the BVP/PIPS or the Best Value approach (Kashiwagi 2010) has been rather high in the Netherlands (van de Rijt & Santema 2012). One of the largest industrial companies in the Netherlands, Tata Steel in IJmuiden (part of Tata Steel Group) has applied the principles of BVP/PIPS to select a vendor for a sewer renovation. BVP/PIPS is a procurement method that aims to select the most suitable vendor for the job, to spur this vendor on to highest performance, and to reduce the client’s management and control tasks. The case shows that a different way of procuring by the client leads to different behavior of the vendor and to a higher performance of the vendor and less risk.

Urban Water Management vs. Climate Change: Impacts on Cold Region Waste Water Inflows

Failure to account for non-climatic changes to water systems, such as design and operation, within climate change impact assessments leads to misconceptions because these activities buffer the human built enviroment from bio-physical impacts. Urban drainage in cold regions, which is dominated by snowmelt, is especially vulnerable to climate change and is investigated in this paper within the context of future rehabilitation of the sewer network. The objectives are to illustrate the relative response of urban drainage to changes in both the pipe network and climate and demonstrate the use of response surfaces for climate change studies. An incremental climate scenario approach is used to generate two sensitivity analyses for waste water inflows to the Lycksele waste water treatment plant in north-central Sweden. Air temperature and precipitation data (1984–1993) are altered incrementally between –5 and +15 °C and –10 and +40% respectively. These data are then used to drive a hydrological transformation model to obtain estimates of sewer infiltration from groundwater. The results are presented as winter and spring response surfaces – these are graphical representations of a response matrix where each point relates to a single model run. Climate scenario envelopes which summarise a series of GCM runs (ACACIA; Carter, 2002, pers. comm.) are overlaid to indicate the range of plausible waste water inflows. Estimates of natural multi-decadal variability are also included. The first sensitivity analysis assumes no change to the drainage system while the second simulates sewer renovation in which the system is fully separated and sewer infiltration is reduced. The main conclusions are that innovations in drainage network technology have a greater potential to alter waste water inflows than climate change and that, while the direction of climate change is fairly certain, there is great uncertainty surrounding magnitude of those changes and their impacts.

Condition Modeling of Sanitary Sewers for Capital Improvement Program Development — The Central Contra Costa Sanitary District Small Sewer Renovation Strategy Development Project

Condition Modeling of Sanitary Sewers for Capital Improvement Program Development — The Central Contra Costa Sanitary District Small Sewer Renovation Strategy Development Project

Automatic task modelling for sewer studies

Research into the development of robotic modules is discussed in the context of cost-effective, small bore, non-man entry (NME) sewer renovation. Following an introduction to the engineering problem or task and the respective task-associated sensing system, interest is centred upon suitably robust task kinematics and control, where predictive modelling is implemented employing the GRASP robotic simulation software package. The physical prototype and its accompanying environment are discussed and general conclusions drawn.

Rainfall data for urban hydrology: what do we need?

For urban hydrologists rainfall is mainly interesting if it touches the surface of the catchment and is intense enough to produce runoff. Rain data requirements for urban applications are different compared to applications in natural catchments. Especially the temporal and spatial resolution needs to be much higher. New tasks in urban drainage call for even better rain data: ideally a long data series (e.g. 20 years or more) with 1 min time resolution, 1 km 2 spatial resolution, and time synchronization errors below 1 min should be available. For some applications these requirements might be relaxed, though. It appears that only in a joint effort, hydrologists, with the support of meteorologists, might be able to supply this data. Data sources can be historical paper chart records, state-of-the-art automatic rain gauges, and radar which is attractive because it provides a high spatial resolution. As the next decades will be characterized by extremely high expenditures for sewer renovation in all industrialized countries, the rain data base to be used for proper re-dimensioning of these systems needs to be much improved.

Excluding Groundwater Infiltration into New Sewers

Much attention has been focused on the need for sewer renovation and rehabilitation of old sewerage systems, but age is not always the reason for sewer failure. Serious problems of performance have also been encountered on sewerage schemes less than 10 years old. This paper considers the problems of groundwater infiltration into new foul sewers, and suggests that deficiencies might exist in some aspects of modern sewer design and construction.Infiltration is most frequently observed at sewer joints. Results are presented of laboratory tests which show the ability of flexible fixed‐ring joints on clay sewers to withstand both internal and external pressures. Damaged polyester fairings on the spigots of these pipes can act as one‐way valves, and massive infiltration may result. The standard site water test is shown to be inadequate in detecting some of these types of defect which may result from damaged pipes or poor workmanship.