Tesco – Walking Floor Case Study
When Tesco wanted to include food waste and general waste into its backhaul model in 2014, DS Smith, as their recycling and waste management partner, was challenged with a project that the industry at that time could not deliver.
DS Smith has run an integrated recycling and waste management service for Tesco for more than a decade. Tesco has operated a successful backhaul model for a number of years, where all stores return materials such as cardboard, polythene, bakery waste and animal by-product (ABP) waste to central hubs for recycling.
This project oversaw the improvement of Tesco’s store-level logistics, and the creation of ‘walking floor’ trailers, which maximise the amount of waste that a trailer can carry at any one time.
In 2014, Tesco wanted to include food and general waste into its backhaul model. ‘Backhauling’ is a process during which any waste materials are removed from the store in the same vehicle that delivers new supplies.
As an alternative to traditional store-level collections, backhauling means that logistics processes are as efficient as possible, as vehicles never travel with any empty space on board.
Tesco uses four-sided cages to deliver products to their stores, and the partnership needed to find a way of handling their waste material streams that would ensure logistical efficiency and adherence to compliance.
Historically, waste from the cages was emptied by hand. Multiple operators at each store would empty cages into a compactor bin. The process was highly labour-intensive, slow, and costly.
Part of the logistics overhaul led to the suggestion that including animal by-product waste (ABP) in food waste – a departure from the existing process of collecting ABP separately – would generate further financial and environmental savings for Tesco. Under ABP regulations, food waste is Category 3 material, which can only transported in a fully sealed container.
This meant that a solution needed to be found which would ensure that all ABP could be transported safely.
DS Smith needed to find a suitable method for transporting food waste that would meet Animal By-Product regulations, as well as being a quick, safe way to decant waste from cages that weigh up to 500kg.
Tesco’s existing logistics relied on multi-use four-sided cages which were used to deliver product into store. These cages were selected as the most efficient method to collect and return the stores’ waste streams.
All stores taking part in the project had Recycling Zones fitted to the back-of-store area, with cages positioned into bays to receive each waste stream produced in store – cardboard, food waste, plastics, metal, paper, and general waste. A transparent, protective plastic lining in the cages ensured that food waste was safely transported to the RSU, where it was tipped into a leak-proof walking floor trailer.
In order to ensure that all material streams could be transported separately, with no cross-contamination, DS Smith worked with Whitham Mills Engineering to provide an innovative, bespoke mechanical solution.
The leak-proof walking floor was a pioneering innovation and unique within the industry at the time of its launch.
Because there was no room at the RSUs to load trailers from the side, trailers were loaded from the rear by conveyors dropping material in. Consequently, obtaining a full payload safely and efficiently was a challenge.
The leak-proof walking floor trailers create mounds of waste, ‘walking’ forward slightly each time to create room for more to be dropped in. Sensors control the trailer’s fill levels, which maximise each payload while keeping the process automated.
The walking floor trailers were specially made to be fully leak-proof, so that they could transport Category 3 ABP.
The project brought a 15% reduction in spend for Tesco through the diversion of the food waste to Anaerobic Digestion. The introduction of Recycling Zones at stores reduced waste arisings by 25% per annum.
The creation of the cage tipper reduced emptying times from 6 minutes per cage down to 1 minute and ten seconds, significantly increasing efficiency.
The innovative leak-proof walking floor trailer for transporting food waste achieved significant savings both in cost and time. Within a year, it had seen approximately 18,000 exchanges of 35yd enclosed skips removed from the back of stores each year.
The project also improved environmental performance, as fewer vehicle movements led to a significant reduction in CO2 emissions, because backhauling the waste streams reduces the number of vehicles needed on the road.
The use of transparent plastic linings to collect the food waste reduced overall waste arising by 25% in the first year of full operation, as any contamination could easily been seen. The automated process improved the average payload from 10 tonnes to 23 tonnes.
As food waste is contained, there were minimal problems with leakage, which reduced cleaning costs and hygiene concerns at stores and Recycling Service Units nationwide.
Food waste is now sent to 10 Tesco Recycling Service Units (RSUs) across the UK and then taken to an anaerobic digestion (AD) plant to be converted into biogas.