Background
Here at Access Irrigation we are frequently privileged to be involved with interesting and unusual projects. This case study focuses on one such example – green wall watering at Barker and Stonehouse. The project involved a very prominent green wall, located on the south-facing wall of established British company Barker and Stonehouse’s new flagship store, at the bustling Teesside Retail Park near Middlesborough. As the store was intended to be constructed in an eco-friendly way, the green wall represented the jewel in its crown, being created with the intention of providing a more pleasant, greener environment for customers and the wider retail park, with its natural green colour promoting a more calming, relaxing atmosphere.
The Green Wall Project
Access Irrigation were responsible for the design, supply, and installation of the complete irrigation system watering the substantial green wall. The system was fully automated, using a highly reliable Heron Mi-4 irrigation controller featuring a large digital display for easy, accurate programming. Soil moisture sensors were included, to ensure that the system did not operate during or after wet weather – overriding the programmed watering until the soil had dried out sufficiently, to prevent water wastage and damage to plants. The controller was linked to an advanced remote-control system, enabling monitoring and control via mobile phone if required. This system would also immediately send a text message should a critical fault develop. The Heron controller was also supplied with the facility to provide an alarm output if the green wall was suffering from a lack of water, which can happen due to their high, exposed positions – which cause increased evaporation. These advanced functions therefore ensured that problems could be quickly resolved, providing peace of mind that the green wall would be protected from any potential damage.
The Water Supply
The system was fed from a substantial 9500l underground MDPE rainwater harvesting tank with an automatic, Divertron submersible pump fitted securely inside the tank. The tank had a turret with a pedestrian duty cover to provide access to the submersible pump and control float switches if required. An automatic mains water top up system for the tank was also included, to ensure that the tank always contained sufficient water for the system to operate efficiently. As the Water Regulations require that the mains water supply to the underground tank be protected by an above ground air gap to prevent backflow, the mains water supply was run via a 24v solenoid valve to a wall-mounted tundish with a Type AA air gap and outlet to a standard drainpipe.
The water levels at which the tank fills and stops filling with mains water are controlled by a float switch in the underground tank, which in turn operates the solenoid valve. The system also includes a warning light and alarm to warn of any problems with the mains water supply not shutting off properly, to prevent water wastage or damage occurring. As this was a rainwater harvesting system, the tank was also supplied with a separate filter suitable for rainwater collection, to protect the system against any build-up of debris that would otherwise occur over time.
Hunter PGV 24v solenoid valves were used to split the system – one valve used for each zone. Each valve is opened and closed in sequence by the controller – connected to the controller via multi-core signal cable, and to the pump via 25mm MDPE supply pipe. When the first valve opens, the pump will detect a drop in pressure (due to pressure release from the open valve) and will begin to operate to boost the pressure back up again. This will cause water to flow through the first (now open) solenoid valve to water the first zone. The controller closes the first valve, and immediately opens the next valve in the sequence. Once the last valve has closed, the water flow will cease, pressure will build again, and the pump will then stop operating.
The solenoid valves were housed in the building’s plant room, built into a wall-mounted manifold along with the Heron controller, isolating valve, drain point, filter, fertiliser injector (to provide liquid feed for the plants), and water meter. An adjustable pressure regulator was also included to ensure that the system always operated at the correct pressure. 20mm LDPE supply pipe ran from the solenoid valves to the green wall, being secured horizontally along the base of the wall and then running vertically up the wall at intervals, strapped securely behind the panels. Pozilock tees and elbows were included to connect from the horizontal run to the vertical runs.
The green wall itself was split into 12 different rows of individual panels, the watering being divided into 4 separate zones to enable efficient, managed watering for each zone, each controlled by a separate solenoid valve. Each zone was comprised of 3 rows of panels. Water was applied using sophisticated Netafim CNL drippers – each having a 2 L/h water output. They include a built-in anti-drain mechanism to keep the driplines full and prevent dirt being sucked into the drippers between irrigation cycles. The drippers also have a continually self-cleaning design to give excellent resistance to blockages. Pozilock tees were connected to the vertical runs, teeing off horizontally to small bore 6mm supply pipe (securely strapped on), with 6mm tees connecting the supply pipe, and the drippers connected via additional 6mm supply pipe running from the outlet of each tee.
The Green Wall Watering Installation
Our experienced engineers were responsible for the installation, testing and commissioning of the green wall watering at Barker and Stonehouse (apart from the underground tank, and the drippers and their 6mm supply pipe and connections – which were installed by others). The installation was carried out in phases according to actual site conditions and the program of works. We also provided full instructions on the operation and maintenance of the system, to enable our client to benefit from its full potential in the future, and to ensure its longevity.
The Result
Our project to design and supply green wall watering at Barker and Stonehouse has helped to enhance the retail park by creating a large natural backdrop that brings a much-needed splash of natural colour to an area that would otherwise be a dull, urban grey. Its inclusion has also helped to decrease air pollution and increase biodiversity – attracting birds and insects to the area. Additionally, the green wall acts as a barrier to block sunlight hitting the building – helping to keep the store cooler during the hot summer months, whilst also keeping it warmer during the winter months as the green wall acts as an extra layer of insulation. We are delighted with the result and are proud to play our part in helping to promote urban greening, and the many benefits it provides.
