Waste is, quite essentially, any substance that is intended to be discarded. In this modern age, where landfill as a waste disposal option is considered a last resort, maximum material reuse and correct classification of waste is supporting the transition to more sustainable and cost effective material management - including at railways and rail depots.
With rail improvements and renovation nationwide, railway engineering and construction is a big part of the UK’s industry – producing unwanted material as a result.
25 million tonnes of soil are sent to landfill each year and can incur a range of costs, depending on the classification of landfill waste. Disposing of inert waste to landfill can cost in the region of £25 per tonne, with non-hazardous waste costing £100 per tonne and hazardous waste exceeding hundreds of pounds per tonne.
On the rail, generation and disposal of ballast waste also needs to be considered. Ballast deterioration can occur from stones eroding beneath the rail sleepers over an extended period of time. Just because it no longer has use in its current position, there are a number of other options that can be considered when looking at rail construction, renovation or ballast renewal.
The Waste Hierarchy
To help evaluate the processes of waste management, the waste hierarchy is used across industries to establish the most effective way to manage waste. Starting with the most preferred option, the waste hierarchy is as follows:
- Prevention or reduction in the amount of waste produced
- Reusing materials for a similar purpose to its origin
- Recycling materials into new products for different purposes
- Other recovery – this refers to energy from waste, such as anaerobic digestion or incineration to product energy
- Disposal – the least preferred and ‘last resort’ option due to environmental impact and associated costs
Regardless of whether the site is a rail depot, construction site, manufacturing site or otherwise, the waste hierarchy aims to generate the minimum amount of waste.
Cost implications of disposing of waste to landfill can be considerable for the railway engineer; reuse is both environmentally sustainable and economically beneficial. While energy from waste is not an option for soil and ballast waste, reusing and recycling materials could generate cost savings and minimise environmental impact.
Reusing material, or transferring material for reuse on another site or depot, is subject to appropriate risk assessment and compliance with the environmental legislation; for example, carrying out the work under a waste exemption or environmental permit, or using a Materials Management Plan.
To determine the suitability of material for reuse, the following needs to be considered:
- Is the material suitable geotechnically?
- Is the material suitable from a contamination point of view?
Two types of risk assessment include:
- Human health – soil samples are collected and analysed to assess risks to end users
- Controlled waters – soil leachate samples collected and analysed to assess risks to surface and groundwater
If there is no intention to reuse materials, it cannot be stockpiled. Similarly, material can only be reused in a quantity that is required. Excessive or unnecessary formations, such as screening bunds, cannot be proposed, simply to reuse material.
If a material is not directly suitable for reuse – if it is considered contaminated or hazardous – then appropriate treatment may be required to make it suitable.
For any spent ballast for which there is no direct reuse option, processing it to form recycled aggregates should be considered ahead of disposal to landfill. Uses of the resulting product can include subbase, pipe bedding and capping layers.
What if my material is contaminated?
Most of the waste generated in the UK comes from construction sites, chemical plants or factories and is at risk of containing toxins and contaminants that can cause harm to people or the environment. In the rail environment, soil and ballast may be contaminated with a range of substances, including fuel, oils and asbestos.
The presence of contamination does not mean that the material cannot be reused. With the appropriate risk assessment, and potential treatment, it is still possible for soil and ballast to be reused and recycled.
Material should not be considered as waste unless it is fully intended or required to be discarded. If the only option for a waste is disposal, it must be classified by law and abide by the Environment Agency’s waste classification guidance, WM3.
Waste Acceptance Criteria (WAC) testing needs to be undertaken once a waste has been characterised as hazardous. WAC testing also needs to be done if a non-hazardous waste is to be disposed of to an inert landfill site.
In terms of waste ballast, different procedures and testing apply depending on whether the material is being transported by road or rail.
Often, having an independent expert involved to determine the optimum disposal route is beneficial, to ensure the end result is cost effective and does not adversely affect the environment.
If you would like more information on managing material reuse, please get in touch!