Bespoke Water Treatment system supports £14million Eel protection project on the River Tyne.

Case Study Overview

The International Union for Conservation of Nature (IUCN) has the European Eel classed as critically endangered on the Red List of Threatened Species. The decline in eels arriving in Europe has fallen by around 95% in the last 40 years, and because of this, the European Eels are highly protected.

Contractor Mott MacDonald Bentley were tasked by their client to install environmentally friendly fish exclusion screens at the Ovingham raw water pumping station on the River Tyne. The large-scale project aimed to support the return of eel stocks to sustainable levels through the installation of the screens, enabling safe journeys upstream for the eels and other fish species.

Challenge

Mott MacDonald Bentley identified that managing flow rates of around 350m³/h during the drilling and installation of piles for the new fish exclusion screens was going to be a challenge. The high flow rates of water were generated as a by-product from flushing the piles, where river water was pumped into the pile during drilling.

The design called for a large number of 1220 and 660mm diameter piles within the new structure. The drilling effluent generated had to be then treated for solids removal, with visually clean water discharged immediately back into the river. Stringent restrictions were placed on the discharge water quality and the client and contractor committed to ensure their work did not adversely impact the ecology of the river.

Following an application to the Environmental Agency, the project was granted a discharge permit that needed to meet the following requirements: All water to be discharged into the River Tyne throughout the construction phase, and for pH levels to be between 6 to 9, and Suspended Solids to be at 50mg/l or below.

Solution

Following the initial project enquiry, RVT technical consultants engaged Mott MacDonald Bentley with multiple online meetings and site surveys to ensure the best understanding of the projects challenges.

A scope of works was agreed and equipment installed, taking into account restrictions including limited access, a small site footprint and stringent Environment Agency permit requirements.

RVT Group’s solution included:

- EnviroHub® HL50 Lamella Plate Settlement Tanks

- EnviroHub® TT10 Treatment Tanks

- EnviroHub® TU02 Dosing Units- Some were modified specifically for the project

- Chemicals (Ferric & Caustic)

- 40m³ holding Tank

- Small holding Tank

- Generators

- Pumps

- Pipework

- Turbidity Monitoring Probes

- pH Monitoring Probes

- SOUNDEX® Quilts

Implementing our effective and bespoke solution, the water was suitable for discharge in line with the Environmental Permit granted, and all contaminated water from the piling works met the required levels for discharge following the treatment system.

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