Temporary Dechlorination System Helps Keep Stablewood Pipeline Works Compliant

Project Overview

The Daer-Stablewood trunk main had been isolated since December 2022 before George Leslie Ltd were appointed to return the main to service as part of a recommissioning project.

Although the pipeline itself had clean water present, Manganese and Iron contamination had been identified at other points in system. As such the project would involve superchlorination, flushing and dechlorination to ensure water passing through the recommissioned main was compliant with regulatory standards.

Challenge

George Leslie Ltd prioritised ensuring water was clean to reduce the environmental impact when discharged to a nearby field. With Scottish Water and Public Health Representatives being directly involved in the project, compliance had never been more important.

As well as the additional scrutiny throughout the project, the trunk main had a capacity of approximately 3 million litres when full. Where the chlorination, flushing and dechlorination took place would need careful management to ensure water was treated fully and thoroughly and meet the standards of their environmental permit.

George Leslie approached RVT Group to support them with the dechlorination process before discharge, knowing they could rely on dechlorination experience and water treatment expertise throughout.

Solution

During the dechlorination process, RVT Group provided three EnviroHub^® TT10 Treatment Tanks connected via a T-piece on the existing pipeline, reducing the outlet from 26" to 6" and making the water flow more manageable.

Once the contaminated water entered the treatment tank, two EnviroHub TU02 Dosing Skids supplied automatic dosing of sodium thiosulfate based on readings provided by probes in the water. This ensured the previously chlorinated water was no longer contaminated and any chemical interference was reduced to safe levels. Once dosed, the cleaned water was pumped into a holding tank, allowing the reducing agent to sit and fully complete the disinfection process before discharge.

Throughout the dosing process, flow, pH and Redox were monitored to ensure the dechlorination system in place was able to manage and treat the all water that flowed through before being discharged to an adjacent field in-line with their permit.

"RVT Group were professional from start to finish. The installs were carried out per the brief and kit helped us stay compliant. From the moment we contacted RVT Group, everything was handled immediately." - Site Manager, George Leslie Ltd