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Railway Ballast

Bioremediation at Temple Meads, UK.

The Problem

Railway lines tend to follow the bottom of valleys. This is flat land where expensive bridges and tunnels are kept to a minimum. So railways often run alongside natural watercourses – rivers and streams.

Trains have always produced unwelcome pollution, from the early steam trains to the oily waste deposited on tracks by modern locomotives.

Physical removal of the contamination is impossibly expensive. It would require closing the line, removal of rails, lifting then washing the stone bed, then relaying the stone bed and rails. The expense would be huge, the disruption would be colossal. But in-situ treatment has always been frowned upon simply because there is no way of guaranteeing that the chemicals required will not get into the adjacent watercourses. The streams close to the railway lines and the rivers next to the marshalling yards are the very reason why cleaning up the railways is so difficult. So railway operators have let decade after decade pass, with layers and layers of coal soot, diesel and lubrication oils build up. Our railways are centres of contamination in our cities and lines of contamination through our countryside.

The Solution

Clearly, if we could find a way to clean the track bed and marshalling yards with a biological, rather than a chemical cleaner, then in-situ cleaning becomes a possibility. One of our Distributors suggested that EnBac® L1800 may be a suitable product for this application.

We had to prove that the application of EnBac® L1800 was no more likely to cause migration than the rainfall that falls naturally. It was agreed that the tests should be conducted and monitored by an independent accredited laboratory. After a series of lab tests, tests moved onto railway sidings at Temple Meads, Bristol owned by Network Rail. Initially, boreholes were drilled between sleepers to ascertain the depth of the built up area and the height of the water table. They lifted handfuls of the contaminated bed and built a couple of replicas of what is below ground, above ground, then conducted a side by side trial where one replica was treated with EnBac® L1800 and open to the elements and one was not treated. By examining the run-off we were able to show that no more hydrocarbons were escaping from the treated area than the non-treated area.

So then we started spraying small areas of the track bed – the area between the rails and two adjacent sleepers – about one square metre. The trial areas were on sidings that were still in daily use and contained contamination that was up to sixty years old.

The Results

Signs of improvement were visible within about three weeks. After about six weeks it was easy to spot which areas had been sprayed and which had not. The sprayed areas were not glistening black, they were a dull, matt dark grey. The natural colour of the hardcore was beginning to show. The trial continued for three months and the improvement continued, but as expected did progressively slow.

These tests were so successful that a planned larger scale test was deemed unnecessary.

Our Distributor now plans to either manufacture small spraying machines on trucks pulled by freight trains, or to adapt four wheel drive vehicles to travel independently on the rails. In the fullness of time, we hope to be able to persuade coach designers to incorporate tanks for EnBac® L1800 and the necessary spraying equipment into conventional passenger carrying coaches. The intention is not only to halt the further contamination of our railways, but to steadily treat and reduce nearly eighty years of contamination.