Here at Access Irrigation, we are regularly involved with a wide variety of projects, many of which are located in unique and unusual areas of the country – several of these being offshore. This particular project involved a bespoke irrigation system for a property located on the Scilly Isles, which form an archipelago 28 miles southwest of Land’s End and only accessibly by air or by a 3 hour ferry ride. The Scilly Isles are designated as an Area of Outstanding Natural Beauty, boasting five main inhabited islands and up to 140 other, smaller uninhabited islands. The Scilly Isles are unspoiled and truly peaceful, offering spectacular coastal paths, rugged nature trails, lush tropical gardens and lakes, sweeping sandy beaches, fields filled with natural flowers and an enormous variety of bird species.
The property was based on the Island of Tresco, enjoying sea views – being positioned by the beach. Lawns surrounded the property on all sides bar one, with the different areas of lawn being split into separate sections and levels, such as upper lawn, lower lawn, and sun lawn. The property already contained two 7500l underground rainwater storage tanks (buried adjacent to each other below the lower lawn) – these tanks being linked together. Our client had a mains water back up system already in place – to ensure that mains water would be supplied as soon as the tanks began to run low. A mains water back up system typically involves an automatic switching device (such as a float switch positioned in the tank) which will switch on mains water when the water level within the tank gets below a certain level. If using a rainwater harvesting system, a mains water back up system is essential – as during periods of little or no rainfall (e.g., a long, dry summer) the irrigation system would be unable to operate without the addition of a mains water back up system, due to insufficient water remaining in the tank.
Access Irrigation were responsible for the design and supply of the complete irrigation system watering all the lawns surrounding the property. We supplied a DAB Divertron submersible pump to be secured inside one of the 7500l tanks. This pump is also an auto-restart pump – meaning that it is ideally suited to rainwater harvesting systems such as this one. This is because unlike other pumps, which need to be manually primed and reset if the tank runs dry, this pump will periodically attempt to operate again – ensuring that the system will be up and running as soon as there is sufficient water present in the tank. This is also obviously much more convenient. Fittings were used to secure the pump inside the tank and MDPE supply pipe was included to run from the tank outlet to two underground solenoid valve boxes – one being a 4-zone valve box, the other a 2-zone. A Hunter X2 controller was included to split the system into 6 separate zones, with multicore signal cable running from the controller to the individual solenoid valves within the underground valve boxes, sharing underground trenches with the supply pipe. 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 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. When the controller closes the first valve, the water flow will cease, and pressure will begin to build again. Once pressure has increased to its original level, the pump will stop operating. This process will repeat throughout the opening and closing of all valves in turn, until all zones have been watered. 19 Hunter PGP Ultra popup sprinklers comprised the 6 zones watering the lawns – with MDPE supply pipe running from the valve boxes to each zone of popup sprinklers. Compression tees were used to tee up from the MDPE supply pipe (for the final popup sprinkler on each run an elbow was used to elbow up to the swing joint), with swing joints being threaded above the compression tees and connecting below the sprinklers – to ensure that the top of the popup sprinklers was located at the perfect height, just below the mowing level.
Our project has resulted in a property surrounded by lush, green lawns, which add additional beauty to an already beautiful location. The green lawns provide a pleasant contrast to the dry beach areas nearby, adding a variety of colour to the area, as well as attracting small birds and insects. In addition, we are proud to play our part in conserving water usage and protecting the environment by integrating our irrigation system with the clients existing rainwater harvesting system.