On a major project currently underway in the UK on the A-14 roadway, HydroBlox is replacing existing methods of filtering silt . While HydroBlox has been approved and specified for this project, the engineer & contractor were skeptical. They fabricated a weir and stacked HydroBlox inside the uprights. The pumps were turned on to simulate a rain event. The result was a drop to 17 PPM to 110 PPM! Even better is the maintenance on the HydroBlox system is practically completely unnecessary. Sediment will eventually build up (but not clog) and will need to be removed. Notice in the last flow picture the water height is the same on both sides of the weir. HydroBlox did not impede the flow. This is the first non mechanical, passive filter that does not require a replacement cartridge. No other system can make that claim.