scope of services

	detailed planning
	implementation and reporting of water quality investigations
	formulation of renovation programme
	tender appraisal
	contract administration
	project monitoring
	post project assessment

technical description

High levels of iron and manganese within the distribution system can cause intermittent discolouration. Undertakings to investigate water quality problems due to deficiencies within the distribution system were made by Mid Kent Water plc with the Drinking Water Inspectorate.

Halcrow is engaged in an ongoing programme to investigate the extent and nature of the occurrences, identify appropriate renovation schemes, prepare and administer the contract, and monitor the renovation works.

A detailed desk study of existing data, such as water quality archive data and customer complaint data was undertaken, followed by a focussed water quality survey utilising a detailed, auditable strategy and quantifiable criteria.

The water quality survey included water sampling carried out using downstream series sampling. Customer interviews were also completed at each sample location assisting in the identification of intermittent problems which may not have manifested themselves during the surveys.

Result interpretation included the consideration of water quality archive data, customer complaint data, water sample analysis results, and customer surveys.

After careful assessment of the results from the various sources, a programme of pipe sampling was undertaken to confirm the condition of the mains in the distribution system.

With due regard to the investigative works, burst frequency and pipe sample data, appropriate remedial recommendations were made. A Joint consultant – contractor team has been established to undertake the renovation works.

The previous phase of the programme comprised approximately 150km of mains renovation, completed in Spring 2000.

The current phase of the project comprises 350km of mains to be renovated or replaced by 2005. Approx 190km of renovation has been achieved by the end of December 2002. Generallly, the works comprise the relining of cast iron mains with epoxy resin and the replacement of unserviceable mains with polyethylene mains using pipeburst techniques to minimise disruption.

For operationally sensitive mains, rapid cure polymeric lining was used, to allow return to service the same day.

Other innovative techniques employed include directional drilling and narrow trenching of new mains.

The project has been successful in achieving lengths of renovation in accordance with a very tight DWI milestone programme.