The Spin® injection technology has been developed to give an answer to the limitations of the traditional direct push technology (DPT) for direct injection of reagents into the subsurface for remediation purposes.
With DPT technology, an injection rod is being pushed or hammered into the soil. Injection products are being injected – mostly at discrete depths - while going down (top-down) or retraction of the rods (bottom-up). By pushing injection rods with a conical point into the subsurface, the soil is being pushed aside and compaction and soil smearing occur at the point of injection. As a consequence, the hydraulic conductivity of the soil reduces dramatically and increased injection pressures are needed to be able to distribute the injection solution into the surrounding soil. Often, the critical injection pressure is being exceeded, causing unwanted fracturing and short-circuiting of the injection product. The injection product can even appear at the surface (daylighting or blowout next to the injection rods). The applied injection pressures can remain into the soil fractures for a long period and injection product can come back to the surface after retraction of the injection rods (reflux). These phenomena (fracturing, daylighting, reflux, blowout) cause injection products not to be distributed at the right location and lead to a decreased efficiency of the remediation.
An additional limitation of DPT is that huge force is needed to push the rods into the soil. On the one hand, this power is provided by the mass of the machine itself and as a consequence, these machines need to be heavy and large, restricting its use inside buildings. On the other hand, when the mass of the machine is insufficient to develop the necessary downward pressure, injection rods are being hammered into the soil. This process causes lateral vibrations creating a preferential flow path for the injection product next to the injection rods what can cause blowout to the surface.
Beginning of 2015, a first Spin® prototype was developed with the goal to eliminate these drawbacks. As these first tests had positive results, the technology has been further developed and refined in the last 2 years based on experiences on multiple field sites to come to the current final design. For this final design, patent is pending.