Solution provided for the issue of concrete wastewater for Heathrow hotel development

Contractor: Toureen Group
Project: Heathrow Terminal 4
City: London, UK
Application: 750-bedroom hotel development
Solution: Concrete Washout System

During construction of a new 750-bedroom hotel development at London Heathrow’s Terminal 4, Conquip worked closely with the Toureen Group to develop a new Concrete Washout system to help manage and reuse concrete wastewater.

The Challenge:

The new seven-storey hotel, which is due to open in 2018, will comprise both a 455-bedroom Crowne Plaza and a 300-bedroom Holiday Inn Express and benefit from direct access to Heathrow Terminal 4. The site occupies over 6000 square metres and is part of a long term, multi-site scheme at Heathrow by the Arora Group.

Due to the volumes of concrete being poured on this project, Toureen required an effective system for managing the wastewater created when washing out equipment following a concrete pour. This includes concrete skips, pump lines and delivery vehicles.

Managing concrete wastewater is a challenge as it cannot be safely discharged into the mains sewer or allowed to drain away on site. Due to the presence of calcium hydroxide, the wastewater is alkaline and so even in small quantities can be harmful to the environment.  The upper pH limit for water discharged into sewers is pH10 while concrete wastewater typically has a pH of between 11 and 13.6.

“Water usage and waste is an incredibly important issue in construction generally and concrete production, delivery and usage in particular.”

George Critchley, Conquip Director

The Solution:

The Conquip Concrete Washout System allows the team on site to contain, recycle and ultimately reuse, rather than dispose of, this wastewater.

Concrete equipment is washed out directly into the system’s filtration tray where the water passes through filtration bags to capture the heavy aggregate. The bags can then be lifted out and the aggregate removed through the usual waste disposal process. The small particles of sediment left in the water then sink to the bottom of the tray and the water flows over a weir into the second section. Here the remaining particles are removed as the water passes through a filter into the final section, to then be pumped into a storage tank.

This filtered water can be reused on site for wet-curing of concrete structures of washing out concrete skips, trucks or pump lines.  Alternatively, the water left in the tank can then be collected by the concrete supplier to be reused in the manufacturing process. This is particularly important due the water intensive process of producing concrete. As much as 170 litres of water is required to produce 1m3 of concrete.

This concrete washout system was the brainchild of Toureen site manager Patrick Heston who Solution identified the opportunity to reuse the wastewater while working on St. Bernard’s Hospital in Ealing. Toureen then approached Conquip to develop the concept further by adding the filtration elements and in doing so open up a range of additional uses for the wastewater.

The Feedback:
We’ve always had an excellent relationship with Conquip and we are really pleased with how the system has developed. They have really adopted the idea and run with it and the result is a highly valuable addition to our kit on site.
On a project like this where we are dealing with large volumes of concrete and where space on site is limited it is vital to have a compact and efficient system for processing the skips, pumps and trucks once a pour is complete..”

Patrick Heston, Toureen Site Manager

“This system not only provides a way to manage the potentially harmful waste products but also reduce the levels of water consumption by allowing excess water to be returned to the manufacturing process.”

George Critchley, Conquip Director