The succession of huge winter storms that battered the UK during December and January 2013/4 wreaked havoc in towns and villages throughout the country, resulting in severe flooding, transport disruption and coastal devastation.

A year down the line, the question is: “Are we ready for whatever this winter may throw at us?”

With the recent government announcement of £2.3bn planned expenditure on more than 1400 flood defence projects, Specification examines some of the products and techniques developed by geotechnical engineers Maccaferri, which could help provide protection against future severe weather events.

According to the Meteorological Office reports, the initial weather impacts of December 2013 were mainly due to strong winds across the north of the country. As the sequence of storms developed and the heavy rainfall totals accumulated the focus of concern shifted in January 2014, from strong winds to flooding, especially in the large river catchment areas of the Severn and Thames.

Rivers, swollen by the equivalent of several weeks of rain falling over a matter of hours, broke their banks causing widespread flooding.

So rapidly were the rises in water levels that old river management systems were quickly overwhelmed with nearby properties, land and infrastructure badly affected.

In coastal areas high spring tides and large waves whipped up by gale force winds combined to cause severe damage and flooding, particularly to west facing shorelines.

A year on, and £2.3bn of public money is being invested in flood defence schemes which is hoped will prevent an estimated £30bn of damage.

With the building of strong protective embankments and erosion prevention systems now crucial priorities, the civil engineering industry has its work cut out to address these construction challenges.

One company whose origins are in the development of innovative erosion protection and watercourse management products is Oxford based Maccaferri, part of the Italian industrial Group, Officine Maccaferri.

Best known for the ubiquitous wire mesh Gabion Basket system, the company is a world leader in environmental engineering solutions with expertise in flood prevention, erosion control and river training, coastal protection, and other related disciplines.

Gabions, normally used to build retaining walls, actually started life as mattress-like wire cages which were filled with clean stone and placed on river beds to prevent erosion. They took the name of the Italian River Reno in which they were first used in 1893 and have been known as “Reno Mattresses” ever since.

Since then the company has devised creative and cost efficient solutions to a variety of water related engineering challenges. Here we take a look at a couple of examples.

St Andrew’s Scotland

Erosion of the coastal sand dunes on which the famous St Andrews golf links in Fife are built risked the ongoing viability of the course. As the dunes were designated a site of special scientific interest [SSSI], Fife Council and St Andrews required a robust yet environmentally sensitive solution that would arrest the erosion of the dunes and prevent further retreat of the nearby River Eden estuary, without damaging their environmental integrity.

A combined “hard and soft” solution was devised by HR Wallingford, comprising a 0.5m deep Reno Mattress revetment covering the inter-tidal zone with a 0.5m-2.0m high Gabion wave-wall at the crest.

Indigenous sand was placed over the revetment mattress, effectively hiding the structure beneath a new beach area. The revetment mattresses were installed on top of a high performance filtration geotextile to prevent loss of sand particles through the mattress

during high tide conditions and periods of heavy wave action. The area soon colonised with natural beach grasses.

A Reno Mattress® is a rectangular, basket enclosure structure with a large footprint area and a small thickness, made from double twist hexagonal wire mesh. The Mattress is filled with stone on site to create a flexible, permeable and monolithic structure to be used for river and canal bank protection works.

FlexMac® DT Emergency hydraulic protection

Hand placed sand bags are probably the most recognised and basic tool for emergency flood prevention for homes and commercial properties. They are slow to fill and install and extremely labour intensive.

New from Maccaferri is a Gabion derived system which offers fast assembly, deployment and mechanical fill using locally available materials.

The system, FlexMac® DT is a modular structure made from double twisted, heavily galvanised wire mesh panels, reinforced with vertical steel bars and lined with a geotextile membrane.

The geotextile lining allows the FlexMac DT to be filled with locally available bulk materials such as sand, general fill or similar.

FlexMac DT is supplied ready assembled but folded to allow easy handling on site. The unit opens to form three rectangular cells nominally 0.5m cube, which can be connected to form linear runs of any required length.

The open base of the FlexMac DT cells also means that the units can be removed by lifting, allowing the fill to discharge, then folded away and retained for future use.

Their simplicity makes them ideal for temporary flood protection, embankment repair and rapid-response, inundation-prevention wherever they are required.

To deploy and assemble a single FlexMac DT unit requires only two – three people and 20-30 seconds. Using conventional hand placed sand bags, it is estimated that it would take thirty people three hours to construct a 10.0m long embankment. Using FlexMac DT, five people could construct a 60.0m long embankment in the same three hour period.

Software

To help engineers model and assess how changes to channel profile and surface characteristics affect crucial flow patterns in rivers, streams and other watercourses, Maccaferri also has a free software package available.

The “Macra 1” software package is simple and straightforward to operate and allows users to calculate flow depths in rivers and watercourses and see how altering the channel profile or modifying surface characteristics, such as by adding vegetation or applying protective measures, can affect watercourse performance, instantaneously.

For a copy of the free Macra1 software or further information on any of the Maccaferri range of erosion and environmental engineering products, visit www.maccaferri.co.uk

01865 770555

info@maccaferri.co.uk