Background
Here at Access Irrigation we are frequently privileged to be involved with interesting and unusual projects. This case study will focus on one such example – a project involving a very substantial green wall watering system which was constructed from environmentally friendly coconut fibre matting. The green wall was located in the heart of the bustling town of Slough, near London, and was created with the intention of providing a natural, permanent green barrier to block out a large building being used as a new data centre for Barclays Bank. The green wall was designed specifically to create a more pleasant environment for the residents of Slough – as several public footpaths and residential areas were located within close proximity of the site. Indeed, thick growing ivy was chosen for the green wall to ensure that it was densely covered, and provided a calming, relaxing atmosphere due to its solid, green colour, and wave like growth. The green wall was also intended to boost urban greening within Slough, by working alongside other green projects within the town to help to decrease air pollution, increase biodiversity, and help keep the urban area cooler during the hot summer months.
The Project
Access Irrigation were responsible for the design and supply of the complete irrigation system watering the substantial green wall, which was 8m high and 200m long. Each coconut fibre matting panel was 1.9m high, with a frame structure running between the panels to secure them together to form the wall. The system was fully automated, using a highly reliable Heron irrigation controller which features a large digital display for easy, accurate programming. To prevent operation in wet weather an adjustable rain sensor
was included, thereby preventing water wastage and potential damage to the plants and coconut fibre matting due to overwatering – ensuring that only the right amount of water was applied.
To comply with the Water Regulations, the system included a pre-assembled break tank and pump. The compact tank included a Type AB air gap to prevent backflow into the public mains and was supplied with a float valve inlet, to prevent the tank from overfilling by closing the inlet when the water level raises the float valve too high. The pressurised supply to both systems was provided by a compact Lowara BG Series pump featuring a stainless-steel body and motor shaft for long life.
The watering for the green wall irrigation was divided into 5 separate zones to enable efficient, managed watering for each zone. Each zone consisted of a horizontal run of 16mm Permadrip Pro dripline, with each run travelling the full 200m length of the green wall. The dripline running along ground level at the base of the green wall comprised the first zone, with the dripline attached to the frame above the first coconut fibre matting panel comprising the second zone, and so on, up until the dripline running along the very top of the frame above the highest panel comprising the fifth and final zone. Hunter PGV solenoid valves were used to split the system – one valve used for each zone. The valves included flow control adjustment and manual override for emergency operation. An adjustable pressure regulator was fitted to each valve, ensuring that the system operated at the correct pressure. Each solenoid valve is opened and closed in sequence by the controller. 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 stop operating.
For ease of installation and security, the control equipment was fixed to a black metal control plate. The irrigation controller, a filter and the solenoid valves were attached to the plate and pre-configured – requiring only input and output connections. The control plate was also supplied with a connection for the mains power supply and a steel braided hose to connect to the outlet of the pump and tank unit. For convenience and practicality, both the control plate and the pump and tank unit were located close to the end of the green wall nearest to the mains water and mains electric supply.
20mm black MDPE supply pipe was used to run from each solenoid valve outlet to the 5 take-off points at the start of each of the 5 dripline runs. The connections from the MDPE supply pipe to the dripline were made by connecting a compression fitting (connected to the supply pipe) to a Pozilock fitting (connected to the dripline). Stakes were included to peg the ground level dripline to the ground for security, with pipe clips included to secure the other 4 dripline runs to the frame levels above. Stopends were used to terminate each run of dripline at its end.
The Installation
Our experienced engineers were responsible for the green wall irrigation installation, testing and commissioning of the pump & tank set. All other parts of the system were installed by others, however we did provide advice and support on the installation process as and when required, also providing full instructions on the operation and maintenance of the system, to enable our client to experience its full benefits.
The Result
Our project has helped to enhance the local area by creating a large natural backdrop that brings much needed colour into an area that would otherwise be a dull grey. This not only helps to improve residents’ mental health and lets them know that their local area is being developed in a positive way, but also helps to improve the natural environment. We are delighted with the result and are proud to play our part in helping to promote awareness of the many benefits that urban greening provides.
