Background

Siltbuster’s team was commissioned by HB Tunnelling to assist with an underground tunnelling project in the Nottingham area, where pipework for a new water main had to be placed underground in areas where there were crossings for road or rail. The job involved deep excavation works in an area affected by large amounts of groundwater.

The Challenge

Once tunnelling works had begun, it was found that there was a significant amount of clay and other small particles in the water being displaced by the works.

Suspended solids such as clay particles are smaller, lighter and are challenging to settle out of the feed water.

An attempt to use clarifiers to separate the clay from the water had proved unsuccessful, and to avoid the risk of discharging pollutants into local watercourses, a solution needed to be found.

A key requirement was that any system used should be mobile – so that it could be moved along to different locations as the tunnelling progressed through its various phases.

The Solution

The nature of the clay and other particles present at this site, along with issues relating to the pH of the wastewater, meant a chemical dosing system was required.

Chemical dosing helps bind fine particles together, creating ‘clumps’ which then sink to the bottom of a treatment tank so they can be safely separated out. It also neutralises the pH levels for safe discharge, due to possible concreting or lime stabilisation works.

After the job was specified by Siltbuster’s specialists, a full solution was assembled and tested at our Monmouth headquarters.

This involved an MT20 mix tank where the chemical dosing took place, three HB50 Lamella Clarifiers, and an Integrated Chemical Dosing System – a specialist unit developed by Siltbuster that can deliver highly effective chemical dosing on a footprint much smaller than those needed for traditional solutions. The system, transported to site and installed by Siltbuster engineers, was capable of handling flows of up to 100 cubic metrics per hour.

The Outcome

The modular nature of Siltbuster’s solution meant it could be adapted precisely to HB Tunnelling’s needs, incorporating advanced functionality such as flow-proportional dosing to their exact requirements.

The solution ensured that only visually clear water was discharged, ensuring compliance and protecting the local environment as well as the reputation of our customers.

Because of the urgent nature of the job, Siltbuster’s highly flexible and capable teams were able to go from first call to installation of the job in under a week, making sure work could continue with minimal interruptions.