Oil-Detect

Completed

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Evaluation and optimisation of a method for the detection of lubricants in rainwater from substations

Background

According to Section 62 of the German Water Resources Act (WHG), installations that handle substances hazardous to water must be designed in such a way that there is no risk of any detrimental change to the properties of water bodies. This requirement also applies to switchgear in extra-high voltage grids in which components containing substances hazardous to water are operated.

The Ordinance on Installations for the Handling of Substances Hazardous to Water (AwSV) stipulates that some large electrical appliances, such as transformers or compensation coils, require a secondary barrier to retain substances hazardous to water. This secondary barrier is realised by the foundation as a catch basin under the switchgear components. Precipitation water collects in this basin, which must be pumped out regularly and drained into a so-called soakaway, for example.

In order to prevent negative environmental impacts on soil and (ground) water during seepage, the contents of the collection trays must be sampled for lubricants each time before being discharged into the soakaway. This sampling is carried out on site using oil test strips. The collected rainwater can only be returned to the natural water cycle if no lubricants are present.

Objective

Different manual methods were used to take samples. In order to ensure comparability between the measurements, the best possible method was to be evaluated and a standardised method derived from this. In addition, new technologies and approaches were to be analysed and evaluated.

Procedure

The process used and its components were characterised on site and under laboratory conditions and optimised where necessary. The main factors influencing the method were determined, described and analysed.

The individual work steps included:

Determination of the actual state of sampling and detection of oil phase in rainwater from catch basins
Evaluation of the different sampling methods
Investigations into the detection of lubricants under laboratory conditions, e.g. "dilution series" and influence of biological material such as leaves
Determination and characterisation of possible impairments to the function of the oil test strips, e.g. influence of storage

In addition, alternative concepts to the conventional test method (oil test strips) were researched, evaluated and, if necessary, analysed with regard to a possible application in TenneT's plants.