Spin®injections

In a lot of cases the Spin® injection technology offers a solution for the limitations of the traditional DPT technology, the advantages are listed below:

Lower injection pressures

Because the soil is not compacted at the point of injection, lower injection pressures can be used and the risk of blowout, unwanted fracturing, daylighting and reflux is minimized.

Higher injection volumes

Due to the lower injection pressures, large injection volumes can be injected what results in a larger radius of influence of injection. Volumes of more than 600 L per meter were already successfully injected.

Soils with limited permeability

Soils or soil layers with limited or low permeability are being characterized by a high degree of soil and clay particles. These soil types are sensitive to compaction and smearing: fracturing, daylighting, blowout and reflux are likely to occur with traditional DPT injections. Because compaction and smearing do not occur with the Spin® technology, injection in silty and clayey soils is possible. Experience has learned that a large radius of influence can be achieved in these soil types.

Homogeneous distribution

With the Spin®-measure and logging system, the desired volume per meter of injection can be set in advance allowing the homogeneous distribution of the desired volume of product over the entire depth interval to be treated. Because of this, the product is being applied to every soil layer of soils with a high degree of heterogeneity and thin soil layers are not being skipped. During injection the injected volume is being registered every centimeter. In this way, it is possible to evaluate how the injection was executed compared to the initial plan.

Exact "whereabouts"

As the injection rods of the Spin® technology are not bended during injection, the location of injection can be more exactly defined. Moreover, the exact depth of injection is continuously measured with the Spin® measure and logging system.

Focused injection

The Spin®-measure and logging system allows for adaptions during the performance of every injection. For example, specifically identified soil layers can be targeted for injection or injection can be stopped at sealing clay layers.

Transparency to client and consultant

Depth, injected volume, pressure, flow rate and relative hydraulic conductivity are being registered continuously every centimeter. In this way, injection logs can be generated that give a visual overview of the distribution of product over the depth interval, the applied pressures and flow rate and the hydraulic conductivity of the subsurface. These injection logs are made available for all involved parties to make sure the injection proceeds with 100% transparency. Depending on the observations in these logs, the injection strategy can be adapted.

Efficient use of injection products

In case daylighting, blow-out or reflux occurs, injection product comes back to the surface and is of no use. Unwanted fracturing leads to the formation of preferential flow paths and short-circuiting, by which the injected product does not end up in the targeted location in the soil. By the design of the Spin® technology, these unwanted phenomenal are less likely to occur and the injected products are being applied more efficiently.

Injection hole sealing

During retraction of the injection rods, the borehole is being sealed automatically and compacted with the original soil material. As a result, preferential pathways for injection product injected in nearby injection points is being avoided and injection points can be put closer to each other if necessary. Additionally, by sealing the boreholes, the creation of vertical preferential pathways for DNAPL migration does not occur.

Accessibility of small spaces

No heavy and large machines are needed to be able to reach significant injection depths with the Spin® technology. Especially for small spaces with limited access, the Micro-Spin® injection equipment has been developed. A standard door opening (B: 78 cm; H: 200 cm) is sufficient to enter the area of injection and only a working height of 200 cm is necessary.

Hydraulic conductivity profiles of the subsurface

A relative value for the hydraulic conductivity across the depth interval can be determined from the data gathered during the injection process. In this way, additional information on the presence of more and less permeable layers in the subsurface is being gathered. This information can give more insight into the migration patterns of contamination and injection products in the soil. Because injection points are mostly executed in a more dense grid compared to investigation points (like monitoring wells or MIP), the Spin® injection method gives additional and 3D information on the permeability of the subsurface.