We get a few enquiries asking why a liquid waste vacuum truck can’t do Non Destructive Digging.
Let’s unpack that a little bit more so you can better understand the full implications.
A liquid waste vacuum truck is designed to pick up liquid/sludge type wastes. Its vacuum system is designed to have high vacuum levels and lower (than NDD trucks) airflow. The shut off systems are also suited to high vac/low air flow. The Primary shut off and the Secondary shut offs are suited to liquid/sludge wastes, not low vacuum/high airflow type wastes. A liquid waste vacuum truck would typically use a 1000m3/75-85% vacuum, vacuum pump. whereas a NDD truck will use upwards of 2-3000m3 and sometimes as low as 40-60% vacuum, blower or whatever moves the air. Liquid waste type shut offs are not suitable to airborne waste particles which are the norm for an NDD truck.
Essentially a liquid waste vacuum truck is designed to pick up wastes which are liquids/sludges and can be lifted as a solid column through a suction hose. The usual laws of physics apply here, even the best liquid waste vacuum pump will only ever lift a solid column of liquid 8-9m. This is a discussion for another day though.
Attempting to use a liquid waste vacuum truck for NDD work will result in expensive damage the vacuum pump!
A NDD truck uses much higher airflow and will have correct separation processes to prevent waste from going through the blower.
In order to do NDD work efficiently, a well set up NDD truck will have a large blower of say 2-3000m3 if not more. It’s the airflow that does the lifting here, not the vacuum level. Air flow and vacuum are two very different beasts! Likewise, the NDD truck will have suitable cyclonic filters and the like to prevent airborne contaminants from enter the blower or pump.
At the end of the day it’s all about “Fit for purpose equipment” trying to dig a hole with the wrong equipment will cost significant time, not to mention the likely risk of damage to expensive critical components as well.
