Measurement of Sewer and Water Main Renovation and Ancillary Works

Abstract

Renovation is defined in the Water Research Centre (WRc) manual³² as ‘methods by which the performance of a length of sewer is improved by incorporating the original sewer fabric, but excluding maintenance operations such as isolated local repairs and root or silt removal’. WRc has classified renovation techniques under the three broad categories of stabilisation, linings and coating, each of which is now described in outline. CESMM3 class Y incorporates these techniques but also ancillary works involved in the preparation of existing sewers, such as cleaning, removing intrusions, closed-circuit television surveys, plugging and filling laterals and other pipes and local internal repairs.

• (1) Stabilisation involves the pointing and chemical grouting of joints.

• (2) Linings are of three types: essentially, type I uses the structural capacity of the existing sewer and requires a bond between the lining and the grout, and the grout and the existing structure; type Il is designed as a flexible pipe requiring no bond between the lining and the grout or the existing structure, and no long-term strength is assigned to the existing sewer; and type Ill provides permanent formwork for the grout, and the lining cannot be assumed to contribute to the long-term strength of the sewer. Linings are mainly formed of glass reinforced cement, glass reinforced plastic and resin concrete.

• (3) In situ gunite forms an effective structural coating.