Background
Sitting in the heart of the beautiful Oxfordshire countryside, Bicester Village is a designer outlet shopping centre on the outskirts of the town of Bicester, having opened in 1995. The Village contains over 150 boutiques of world-renowned fashion and lifestyle brands – all amazingly offering substantial savings on the original retail price. The Village also boasts an array of exquisite eateries serving both seasonal and international cuisine, in a beautiful open-air setting. Open a staggering seven days a week, the Village is always accessible – boasting its own train station and being only a short car drive from the bustling capital of London, with ample free parking available. The Village is part of the prestigious Bicester Collection, which comprises 11 other distinctive destinations in Europe and China, with Bicester Village being the second most
popular destination for Chinese tourists in the whole of the UK after Buckingham Palace!
The Irrigation Project
Access Irrigation were responsible for the design, supply, and installation of the complete Bicester Shopping Village irrigation system watering the planted borders and trees surrounding the main shopping complex – these substantial borders running in an extremely prominent position along the whole front side of the complex and also along the smaller side nearest the main road. There were also a multitude of planted borders and trees running between the large number of customer parking bays. The system was fully automated, using a Heron Mi 12-zone irrigation controller. This controller has a large digital display for easy, accurate programming and is very reliable. The controller features a pump freeze facility, which in conjunction with a float switch will suspend the programme in the event of a failure in the water supply. To prevent operation in wet weather, and therefore saving water usage, a Heron rain sensor was included. A 19,000 litre underground rainwater storage tank was used to collect the rainwater runoff from the building roof and the ground level paving, with a Graf Universal Industrial Filter with telescopic shaft supplied to remove leaves and debris before water enters the tank, thus keeping the irrigation system water supply as clean as possible to ensure the longevity and efficiency of the system. This tank was also supplied with mains water to ensure that it always contained enough water for the system to operate efficiently. An underground tank mains fill kit was included for this purpose, which included a float switch to trigger mains water operation as soon as the water level fell below a certain point. This kit also featured an alarm to be triggered by a float switch if the opposite happened and the water level rose too high due to excessive rainfall, ensuring that the system complied with the Water Regulations regarding backflow prevention. A Divertron DAB submersible pump was supplied, to be secured inside the underground tank to provide a pressurised water supply to the system. The irrigation controller and tank fill controls described above were installed in a plastic-coated steel cabinet, by Glasdon. To ensure their protection, the cabinet has a double skin wall with foam insulation, louvred ventilation panel and a single, lockable door for security. The cabinet was also coloured dark green, to ensure that it was discreet and blended in within the planted border where it was located.
The irrigation system was split into a total of 11 zones, with Hunter PGV solenoid valves being used to control each zone. An advanced Hunter Accu-Sync pressure regulator was fitted 
to each solenoid valve, to ensure that the system always 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. Once the duration set for the first zone comes to an end, the controller then closes the first valve, and immediately opens the next valve in the sequence. Once the last valve has closed, the water flow will cease, the pressure will build again, and the pump will stop operating. The solenoid valves and their electrical connections were conveniently housed in underground valve boxes, these boxes being connected to the pump and tank unit by 40mm MDPE pipe, buried in trenches underground, these trenches ensuring that the pipe was protected from frost and potential overhead damage. 32mm MDPE pipe was then connected to the solenoid valve outlets, to run towards the relevant planted borders and trees, where it then transitioned into smaller bore 20mm pipe. This 20mm pipe then spurred upwards towards the surface, then connecting to take off points, using compression and Pozilock fittings to transition to the dripline watering the planted borders and trees.
Permadrip-Pro dripline was used to water the planted borders and trees. This is a brown coloured dripline designed for landscape irrigation with a 16mm pipe diameter and a wall thickness of 1.2mm. The 1.6 L/h drip emitters are pressure compensating, ensuring uniform output over a wide pressure range and include a built-in anti-siphon mechanism, to prevent dirt being sucked into the drippers at the end of the irrigation cycle. These features make it ideal for sub-surface use and for use on sloping sites. The emitters also have a large inlet filter and unique, continually self-cleaning design, giving excellent resistance to blockages. For the planted borders, dripline of 0.3m dripper spacing was used, being laid out in lengths spaced every 0.5m apart. For the trees, dripline of a more frequent 0.15m dripper spacing was used, being laid out in a ring around the base of every tree. Anchorage pegs were used to secure the dripline in place, and Pozilock fittings being used to connect the dripline, with stopends used to terminate each run of dripline.
The Irrigation Installation
Our experienced engineers were responsible for the installation, testing and commissioning of the complete Bicester Shopping Village irrigation system, with relevant risk assessments and method statements being provided to our client. This process was carried out in phases according to actual site conditions and the program of works. Once the installation was complete, we provided the client with full instructions on the operation of the system, to enable them to realise its full potential and to ensure its longevity for the future.
The Result
Our Bicester Shopping Village irrigation system has resulted in green and lush planted borders and trees located in a very prominent position, within close proximity to the main entrance and roads leading into Bicester Village, greatly enhancing the whole area and experience of the Village. The thriving planting has also provided healthier, cleaner air and helped to reduce pollution. We are delighted with the result and are proud to play our part in helping modern, popular developments like Bicester Village to thrive, whilst simultaneously boosting their green credentials.
