|HEISTT is a European research project for SME clusters and stands for “High Efficiency In Situ Treatment Technology for Contaminated Groundwater”. The project is led by a Turkish Institute called TUBITAK MARMARA RESEARCH CENTER active in water, waste, air and soil, while EUCETSA’s involvement is especially in the dissemination of the results.|
The proposed HEISTT solution is the rapid installation of groundwater treatment chemicals as an in situ subsurface remediation technique, brought about by the use of ultrasonic assisted injection technology to create a closely spaced grid of single treatment small diameter wells to a depth of 20 meter. As part of the bore holing process, remediation chemicals will be introduced in to the ground contained within a geotextile sock. Diffusion of the chemicals (oxygen release compounds, hydrogen release compounds, zero-valent iron or chemical oxidants) occurs through the permeable geotextile material.
Injection target cycle time will be 5 minutes from hole to hole at 1 m spacing. The spacing of these boreholes will be decided by the concentration of contaminant and the required rate of clean-up. This whole system will be passive, i.e. requiring no energy to function after installation or operator maintenance. A range of equipment options are envisaged, from simple attachments for existing excavation plant – which will be the primary focus of HEISTT, enabling rapid take up of the process by SMEs due to the affordability of retrofit - through to dedicated bespoke machinery.
- CL:AIRE (UK)
- EFOA-CEFIC (B)
- EUCETSA (B)
- UK-HERI (UK)
- TUBITAK (Tu)
- Idea (It)
- Maves (Est)
- Dawson (UK)
- Telsonic (Swi)
- Afiliex (Fr)
- Regenisis (Irl)
- Technosam (Rom)
The HEISTT project is now in his final year and we give a summary of the state of art.
A full scale ultrasonic probe has been designed, modelled made and tested in laboratory and field conditions.
Design modelling was carried out to estimate the extent ultrasonics can fluidise soil during the driving process.
The probe has been made in stainless steel and titanium alloy and contains sensors which relay information back to the control system permitting the operator full control.
The probe was successfully integrated with both laboratory test equipment and pile driving equipment and is being further tested for robustness in different geological conditions.
The HEISTT project aim is to produce a full scale size pre-production prototype rig that will retrofit to the hydraulic system of excavator equipment, thereby providing a lower barrier to entry for its uptake and use and permitting its access to a greater number of sites. The design specifications of excavator mounted vibrator has been revised to provide a stabilising guide at the top of the leader to limit probe wobble during operation and will soon be assembled for field testing.
As part of the drive-piling process, treatment chemicals will be left in the ground to bring about remediation, with test presently trialling this via the mechanism of diffusion through a geotextile sock, anchored at the base of the driven hole. Different designs of geotextile sock have undergone encouraging laboratory trials, prior to site trialling.