T-T Pumps’ Jon Whittingham discusses the rise in use of package pumping stations as sites using gravity drainage for waste or surface water become rarer – and the key points that architects should consider.
When it comes to specifying a solution for the removal of waste and surface water from a development, package pumping stations are an increasingly popular choice. With so many options available in today’s market, including a wide range of chamber sizes and pump models that cater to different applications, they are a versatile solution that can be implemented on diverse sites.
Package pump stations can be procured within short timescales to fit with tight project deadlines and benefit from a ready-to-use design that permits quick installation below ground in comparison to bespoke methods such as pre-formed concrete rings.
Conventionally, systems consist of a pre-formed chamber (traditionally made from glass reinforced plastic). Chambers are now more commonly constructed in materials like polyethylene due to production repeatability and lower environmental impact), pre-assembled internal pipework and valve assemblies – delivered to site ready for immediate installation.
The increasing need for pumped drainage solutions is also driving package pumping station use. As new infrastructure is developed across the UK, the number of sites available with topography that facilitates gravity drainage is dwindling, necessitating an increased use of pumped drainage systems. These systems play a crucial role as part of the infrastructure they serve, but informed selection is essential to effective waste management that protects buildings and the environment from spills.
Compliance
Approved Document H details essential design features for drainage and waste disposal systems. This includes key aspects for pumping stations, such as provisions for 24 hours of storage within the pump station chamber, in the event of a system or power failure.
Individual product certifications can also be a clear indication of both high quality and compliance with relevant regulations – such as BBA Approval.
Specification
An understanding of the application that the station will serve and its associated risks is equally as important as the product itself. Pumping stations are designed to collect and deliver waste and surface water to an appropriate destination where another service then takes over, like a sewer. The composition of the medium to be pumped needs to be studied so that the correct product is selected for water to be transferred effectively. For example, a pump to transfer wastewater from a single domestic property will be different on flow rate and solids handling ability to a surface water drainage pump on a sports ground.
Often overlooked, the size of the delivery pipe work – or rising main – can also be a restricting factor to how a pumping station performs. The designer of the pumping station itself should advise upon the correct selection of discharge pipe.
Septicity within the foul water network is an ever-increasing concern. Modern day water saving utilities mean sewage waters are becoming naturally more concentrated. Less wastewater passing through pumping systems is leading to an increase in retention and therefore septicity.
Air management
Pumping systems can block, and blockages can result in down time and potentially costly repairs. Blockages are often the result of poor system design or abuse by users incorrectly disposing of foreign objects, yet trapped air can also be the cause.
As pumping stations become a more frequent requirement, so does the need to pump over further distances – with water travelling through numerous kilometres of pipework not an uncommon occurrence.
Identifying points where air may collect along this pipework and establishing the risk of system syphon in advance of pumping station installation can prevent the need for costly and time-consuming remedial works. A competent pumping system designer should identify the need for, number of and positioning of air release valves to ensure uninterrupted flow.
Jon Whittingham is pumping stations manager at T-T Pumps