Innovative waste water management system deployed for Rochdale flood defence works

Construction, Infrastructure & Development

Case Study

Innovative waste water management system deployed for Rochdale flood defence works

Construction, Infrastructure & Development

Client

Volker Stein on behalf of the Environment Agency

Location

Rochdale and Littleborough

Objective

£56m flood risk management scheme

Challenge

Keeping water clean and protecting environment during major works

The challenge

The first phase of the £56m Rochdale and Littleborough Flood Risk Management Scheme is underway, using our innovative Rain Ready® system to handle polluted water created by construction activities.

The project works include the construction of a flood storage reservoir and sections of linear defences both upstream and downstream as well as modifications to existing defences along the river Roch.

Once complete, the flood scheme will better protect 723 homes and 489 businesses from flooding. The Littleborough section will better protect 337 homes and 185 non-residential properties. Additionally, the scheme aims to provide considerable environmental benefits, with 1.2 acres of woodland enhancement at Grove Lodge and over 130 trees and 160m of hedging to be planted.

The solution

Rain Ready® waste water management system supports major flood defence works

We are providing silt control products and design advice for the project – our Rain-Ready® system comprises Pipe Reactor, Gel Flocculant, Silt Capture Channels and settlement ponds.

VolkerStevin engaged with us early in the project to discuss options to implement a process for cost effective, environmentally friendly water treatment. Involving us early is extremely important and allowed detailed discussions to take place and a solution designed prior to the start of critical works requiring water management.

We carried out settlement testing, often used as part of our process in designing the best solution for a site, from water and soil samples provided by VolkerStevin.

Within a month of our first call, settlement testing was carried out, a site-specific system was designed and our products were delivered to site. With our guidance, VolkerStevin self installed the Silt Capture Channel.

We estimate that VolkerStevin are saving in the region of £50k – £128k over 12 months by using our Rain Ready® water treatment system compared with other solutions on the market. We pride ourselves in providing biodegradable, low carbon solutions that save money for our clients and protect the environment.

Collaborative working achieves environmental standards

Our technical team provide a mixture of remote and on-site support, with the majority carried out remotely communicating closely with VolkerStevin’s capable site teams.

Innovative water treatment

The design reduces the need for continual pumping with water left in the settlement pond as required. Pre-construction testing showed the soil particles are small and take over 24 hours to settle, which means the water could not be discharged without significant mitigation.

Award-winning site

The project won the Green Apple Award 2024 in the Building and Construction Flood Protection category – National Champion.

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Volker-water-treatment-diagram-e1739358312215

The results

Independently verified water testing showed our rain ready water treatment system has already achieved.

Many heavy metals were reduced as a result of the treatment including Aluminium, Arsenic, Barium. Cadmium, Chromium, Copper, Iron, Lead, Manganese, Nickel, Phosphorus and Zinc. This is reflected in the Chemical Oxygen Demand reducing by 77%, protecting the dissolved oxygen levels of the receiving watercourse and subsequently, the fishery.

Total Suspended Solids (TSS)

Up to 99% reduction (346 → 2 mg/l). Met environmental permit conditions for TSS and pH

Phosphorus

83% reduction, helping reduce eutrophication

Aluminium

99% reduction, discharge aligned with drinking water standards

Lead

98% reduction

Manganese

91% reduction, meeting drinking water standards

Iron

Filtered iron: Up to 98% reduction, within drinking water thresholds Total iron: 99% reduction, meeting Water Framework Directive standards

Zinc

91% reduction

Arsenic

85% reduction

The products

Silt Capture Channel

Captures silt and flocculated fine silt particles
Unique design utilising Frog Environmental products
Standard design polishes up to 900 litres per minute
Supplied with site review service to ensure correct placement on site

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Gel Flocculant for Silt Control

Can be deployed passively in flowing water or in pumped systems (Pipe Reactor & Clearflow GFR)
Long lasting, low maintenance silt control devices
Supplied with site review service to ensure correct site-specific deployment and efficacy
The most cost effective method to manage fine suspended solids on site

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Pipe Reactor

Portable unit for dosage of Gel Flocculant blocks
Quick and simple to set up
Treats water at up to 1,800 litres per minute
Highly cost-effective method of managing clayey water on site

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Silt Mat™

Cost effective silt pollution control on site
100% biodegradable for easy disposal or seed onsite
Can be used on land, in ditches, streams or rivers
Unique heavy-weight design delivers longevity on site

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Floc Mat®

Low cost, low carbon way to treat clay-impacted water run-off
Can be used on land and in ditches
100% biodegradable for easy disposal or seed onsite
Simple to deploy and highly effective at controlling fine particle silt pollution

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“With increasing UK rainfall over recent years, and anticipating potential delays, the site was designed with a rain-ready mitigation system to tackle the inevitable surface water.”

“Water is pumped through a Pipe Reactor where it is treated with Gel Flocculant to reduce settlement time, then into settlement ponds and a final polishing pond, which runs over a series of biodegradable mats to remove any remaining silt.”

Richard Walsh, Senior Project Manager
VolkerStein

“The rain-ready approach of using Silt Mats™, settlement ponds and Silt Capture Channels means the equipment remains in place year-round, ready for use whenever needed. Independent laboratory testing has shown that there is 99% reduction in total suspended solids and up to 99% reduction in iron. This means the water being discharged back into the river actually meets the threshold for drinking water standards.

“VolkerStevin contacted us early on in the process, giving plenty of time for discussion and review before the project’s critical works began. It really emphasises what can be achieved with early engagement towards water management.”