Australian Standards require a properly installed pool shell to be fitted with a hydrostatic valve and to have appropriate drainage in place to control groundwater. In most instances where there is rising groundwater (due to heavy or prolonged rainfall for example), the combination of a standard hydrostatic valve and a sub-soil drainage system, should protect the pool shell against structural damage. However, there are accidental, unforeseen, or extreme events that may overwhelm these protective measures (see Note beside drawing). To help avoid such a situation occurring, you need to be familiar with an essential component of an installed pool, known as the standpipe.
Use of Standpipe
The standpipe is a critical component of the sub-soil drainage system for all pool installations, except for specific locations having highly permeable soils (such as sand sites). A complying standpipe (as shown in above drawing) includes an underground section of vertical pipe that is permanently vented to atmosphere through a removable grating (positioned in the concrete beam and adjacent to the deepest section of the pool).
A properly constructed standpipe can be used to determine the groundwater level or to lower the groundwater level. It may be necessary to lower the groundwater level when the pool is being emptied or partially drained. Written instructions for qualified pool technicians, on emptying (or partially draining) your pool shell, including instructions on how to appropriately drain groundwater through the standpipe, are available from Compass on request.
Note: Under NO circumstances can the groundwater level be permitted to exceed the pool’s water level, as this can result in bulging of the floor and walls and ultimately in structural damage to the pool shell. It is essential to inspect and monitor the groundwater level in the standpipe immediately after heavy or prolonged rainfall or wherever a water-table is present. Advise your contracted pool builder immediately if the groundwater level approaches the pool’s water level.
Emptying Your Pool
You must NOT empty your pool, or partially drain the water level below the mouth of the skimmer box, as damage can occur. Where required, you can engage your contracted pool builder (or any qualified pool technician) to empty your pool, or partially drain the water level below the skimmer box. Appropriately emptying, or partially draining the water level below the step ledge, will require the pool shell to be properly braced at the step ledge. Also, whenever a pool is completely emptied, the hydrostatic valve must be removed until the pool is ready to be filled again. Failure to properly brace a pool or remove the hydrostatic valve as required, can
result in bulging of the floor and walls, and ultimately in structural damage to your pool shell.
You can drain surplus water from your pool when the water level is too high for the skimmer box to skim, provided the water level is not drained below the normal operating level of the pool. Where a waste line is approved for use and available (as required for back-washing sand filters), surplus water can be drained through this waste line to the sewer. Where a waste line is not available, surplus water can be manually drained. Prior to draining any water from a pool, the groundwater level (if any) must be determined. This is done by observing the groundwater level in the standpipe. Under NO circumstances can the pool’s water level be drained below the groundwater level, as this can also result in bulging of the floor and walls, and ultimately in structural damage to your pool shell.
Failure to comply with industry standards and good practice, and/or failure to comply with written instructions provided by Compass, which results in structural damage to your pool shell, will affect the manufacturer’s structural warranty. Written instructions for qualified pool technicians, on emptying (or partially draining) your pool shell, are available from Compass on request. All Compass pools manufactured from March 2016 now include the patented MP Hydro hydrostatic relief valve (unless otherwise approved by Compass at the time of manufacture), and a Service Manual for this valve is available from Compass on request.
Note: Evaporation and splash out can also lower your pools water level, especially during summer where the loss can be as high as 15mm per day due to evaporation. It is your responsibility to ensure the water level never falls below the mouth of the skimmer box and always keep the water level as high as possible (3/4 of the way up the skimmer is ideal).
Future Works – Stormwater Runoff and Sub-soil Drainage
Sub-soil drainage is an underground drainage system installed by your contracted pool builder at the time of installation. Additional sub-soil drainage may also be required with any future works. Surface drainage is required to control stormwater runoff, and must also be considered with any future works. Structures that are erected after the pool is installed must include an appropriate drainage system to control stormwater runoff. For example, a newly constructed patio should NOT discharge rain water (collected from the roof) directly onto the ground around the pool as this can increase the groundwater level and cause an increase in hydrostatic pressure acting on the pool shell.
If the site is reactive (clay), then any discharge of water onto the ground may cause an increase in reactivity in the saturated areas, also resulting in an increase in pressure acting on the pool shell. Instead, all structures should discharge stormwater via guttering and downpipes into a stormwater drainage system including additional surface drains to collect additional stormwater runoff.
Structural landscaping works that occur after the pool (and the pool’s sub-soil drainage system) is installed must also include an appropriate subsoil-drainage system, and ideally should be designed by an engineer and installed by a qualified trades person. For example, construction of retaining walls (or elevated garden beds) in close proximity to the pool can create “perched water tables”, with a resultant increase in pressure acting on the pool shell. A sub-soil drainage system is required to prevent this occurring.
Be aware that damage caused to the pool shell as a result of inappropriate drainage will affect the manufacturer’s structural warranty. As such, it is your responsibility to control drainage associated with any future works.
Future Works – Concrete Surrounds
As part of the proper installation of an in-ground Compass pool, a concrete beam must be connected to the perimeter of the fibreglass coping in accordance with Compass engineering details. This concrete coping beam is a critical component in the structural integrity of the installed pool shell, it helps prevent splash water and rainwater from penetrating the backfill, and provides a stable base for coping pavers to be attached. The width, depth and design of the concrete coping beam is contingent on the size of the Compass pool and the reactivity of the site soil/clay. Refer to Compass engineering drawings for full details.
Future works may include additional concrete pavement connecting to, or abutting, the existing concrete coping beam. Such additional concrete surrounds must be installed in accordance with Compass engineering details to avoid movement and damage to the existing concrete coping beam, which in turn can move and damage the fibreglass pool shell. Approved connection detail is provided in Compass Coping Extension drawing 211, which is available from Compass on request. .
Additional concrete surrounds must also be installed in accordance with Australian Standards, taking into account the site soil/clay conditions and uniformity of bearing requirements. Be aware that damage caused by incorrect installation of additional concrete surrounds will affect the manufacturer’s structural warranty. As such, it is your responsibility to ensure compliance with Compass engineering requirements and Australian Standards for any future works associated with additional concrete surrounds.
Important Notification to the Pool Owner
It is your responsibility as pool owner to follow the ‘Care & Maintenance’ instructions in this section of the Pool Owner’s Guide. Failure to comply with any of your responsibilities that results in damage to your pool shell’s structure, will adversely affect your manufacturer’s warranty.