Background
The Exchange is a multi-million pound brand new public realm located in the heart of Aylesbury, Buckinghamshire, which was completed in 2019. The development incorporates residential, leisure and commercial space. It is a stunning new public space, featuring unique and inspiring contemporary artwork for everyone to enjoy, whilst providing a beautiful outdoor setting. The impressive five-storey building sits directly adjacent to the County Court and Judge’s Lodging and is specifically designed to complement these Grade II listed buildings with its striking red brick colonnade design. The Exchange greatly boosts connectivity in the town centre, with its high-spec space being fully accessible, including sloped access routes for pushchairs, wheelchairs and other mobility aids and also providing formal and informal seating
The Project – Town Centre Irrigation
Access Irrigation were responsible for the design, supply and installation of the town centre irrigation system for the whole communal space. This included watering the lawns, borders and trees. The system was fully automated, using a Heron Ma-6 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 a rain sensor was included. As the irrigation system was a rainwater harvesting system, a 19,000 litre underground rainwater storage tank was used to collect the rainwater runoff from the building roof. A submersible pump was positioned inside the tank to provide a pressurised water supply to the irrigation system and to comply with the Water Regulations regarding backflow prevention. A mains water filling system was also included to automatically provide mains water if required. To enable this, a float switch was positioned in the underground tank, which would activate a valve to turn on the mains water supply when the rainwater in the tank dropped below a certain level – thus ensuring that in periods of dry weather the system would still function properly. A Graf Universal Industrial Filter with telescopic shaft was included to remove leaves and debris before water enters the tank, and Amiad and Big Blue filters were used to ensure the water always remained clean. In addition, an Aquada UV system was used to destroy harmful bacteria that can potentially gather in water. Solenoid valves were used to split the system into sperate zones, allowing each zone to operate at a separate time, thereby enabling good water flow and efficient watering for each zone. The solenoid valves were connected to the controller via signal cable, and connected to the pump & tank via supply pipe. The controller, pump isolation switch, filtration system, UV system and solenoid valves were all housed in a Glasdon Cadet Enclosure located above ground. This steel unit is accessed and secured using lockable double doors.
Irrigation Zones
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, the pressure will build again, and the pump will stop operating.
The town centre irrigation system was split into a total of 5 zones. The lawn areas comprising the first three zones, the border areas the fourth zone and the trees the fifth zone. K-Rain rotator Pop-up sprinklers were used to water the lawn areas. These sprinklers drop into the lawn below the mowing level when not in use, enabling them to be completely hidden from view. They emit water with multi-trajectory rotating streams, giving excellent uniformity, matched precipitation at any arc or radius and low application rate to reduce run-off. The sprinklers have a range from 2.4m to 8.2m, making them ideal for watering small to medium turf areas. Permadrip-Pro dripline was used to water the 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 borders, dripline of 0.3m dripper spacing was used, being laid out in lengths spaced every 0.5m apart. For the trees, dripline of 0.15m dripper spacing was used, being laid out in a ring around every tree.
The Irrigation Installation
Our experienced engineers were responsible for the installation, testing and commissioning of the complete town centre irrigation system. This 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.
The Result
Our project has resulted in a green and lush communal space for all to enjoy, greatly enhancing the whole area of The Exchange. We are delighted with the result and are proud to play our part in helping towns like Aylesbury to develop and thrive.
