Report No FR0157

Mar 1991

I OBJECTIVES

To review current practices and cost of service pipe rehabilitation and to assess the effects on water quality and flow of the various pipe rehabilitation methods.

II REASON

The cost of rectifying problems caused by poor service pipe performance has been estimated to be a significant proportion of future expenditure within the Water Industry. Furthermore, when mains rehabilitation is being carried out, the opportunity arises to perform work on service pipes.

Throughout the UK Water Industry, there is a large variation in methods, and therefore cost, of service pipe rehabilitation. There is a need to establish which methods are most cost effective.

III CONCLUSIONS

1. During mains replacement, where service pipe performance is currently acceptable, the most cost effective solution is generally direct transfer of service pipes, regardless of service pipe material.
   
2. During mains relining, the most cost effective solution is to do no work on service pipes where performance is currently acceptable.
   
3. During mains relining or replacement, in areas where service pipe performance is currently below standard, remedial action should be performed on the communication pipes.
   
4. Initial results from two zones indicate that C02 cleaning offers a cost effective remedy in areas where service pipe performance is currently below standard. C02 cleaning of supply pipes offers large flow improvements at the kitchen tap.
   
5. C02 cleaning should be attempted to remedy blocked communication pipes, except in areas with known lead problems, where replacement is recommended.
   
6. Breading as a potential remedy to poor supply complaints is not cost effective compared with C02 cleaning.
   
7. In soft water areas large benefits to water quality and flow can be achieved by replacement of galvanised iron service pipes which are providing inadequate performance.
   
8. In some circumstances the use of no-dig techniques reduces the cost of communication pipe replacement when compared with conventional trenching techniques.

IV RECOMMENDATIONS

1. Service pipe rehabilitation policies should be reviewed.
   
2. Further trials performed to investigate the methods and benefits of C02 and air scouring of service pipes.
   
3. The use of no-dig techniques increased.
   
4. Consideration given to offering supply pipe cleaning as a customer service.

V RESUME OF CONTENTS

This report reviews current service pipe rehabilitation policies and the associated costs. Several field trials performed to assess the benefits of various service pipe rehabilitation methods are described. The results are discussed and suggestions for cost effective service pipe rehabilitation policies are given.

Copies of the report are available from FWR, price £25.00, less 20% to FWR Members.