Introduction

Leakage (inflow) of surface water  via manhole and inspection covers and frames (jointly referred to throughout this document as “covers”) into foul sewers can represent a significant, and frequently unrecognised, contribution to total flow in foul sewers.

Submergence of even a small number of covers within a foul sewer network can be sufficient to overwhelm the capacity of pipelines, pumping stations or treatment works. At worst, foul flooding of property, and environmental contamination, can be the consequences. In less extreme circumstances, increased pumping and treatment costs can result.

This specification provides a means of product testing to determine the leak tightness of covers. Products tested in accordance with this specification can be assigned a leak tightness classification between 0 – 3 based on measurement of a product’s maximum leakage rate, expressed as litres/m² per 30 minute period of submergence.

Use of this specification will permit designers, specifiers and procurement staff, working together, to select products that are appropriate to the type of sewerage system under consideration and the risk of such covers’ submergence.

The existence of this specification will assist product manufacturers and suppliers to measure and understand the performance of their existing product range and, where appropriate, amend their product offerings to meet performance criteria specified in accordance with this document.

Caveats

None.