EKG Remediation of Embankment

Forest of Dean slope stabilisation

Low Impact Benefits

Highway Embankment Stabilisation

Sewage Sludge

Mine Tailings

Railway Embankment Stabilisation

Reinforced Soil

Lagoon Consolidation

Consolidation of Soft Soil

 

 

 

“Having had a presentation on the theory, I visited the site to see the system operating in practice. It was fascinating to see it working and given that it is cheaper than traditional treatment, another example of innovation”.

Tim Harbot, Midlands Regional Director, Highways England.

EKG remediation of off-slip embankment

Project outline

Repair of earthwork failures involving landslips represents significant expenditure for Highways England across the national network each year. A variety of engineering solutions conventionally used involve significant earthworks and import of new construction materials, resulting in the generation of waste and a high carbon footprint.

Progressive shallow failures on junction 7 of the M5 motorway southbound off-slip road embankment had caused leaning of lighting columns and signposts, road surface defects and were threatening the vehicle restraint system.

The potential for the EKG system to be used on this project was identified by Amey who managed this section of the M5 on behalf of Highways England. Key factors were the desire to avoid expensive and disruptive traffic management during construction which would have created significant delays at this very busy M5 interchange, and to secure savings in cost and carbon footprint.

The original scheme for remediation of this embankment proposed by the previous Highways England service provider was for a soil nail solution. Amey as the Area 9 service provider to Highways England re-submitted the scheme to Value Management with a proposal to remediate using the EKG technique instead as estimates indicated that compared with the equivalent full soil nailing scheme, the EKG solution held the potential to deliver:

  • 8.5% reduction in cost
  • 57% reduction in emissions
  • Reduced risk of site incidents and accidents
  • Reduced environmental impact
  • No waste soil to landfill.

Project implementation

Active EKG treatment progressed along the slope between mid April and early July 2012 and was only slightly affected by the wettest April and June on record, which would have caused greater delay and disruption of conventional remediation techniques.

The embankment comprised 265m of reworked Lower Lias Clay overlain by a mantle of variable reworked Mercia Mudstone between 6 and 10.5m high, with a slope angle of 26° to 29°.

As part of the ground investigation, specialist laboratory testing was carried out by Electrokinetic Ltd. Amey and Electrokinetic Ltd then progressed and optimised the design of the remediation scheme resulting in a construction specification that varied across 6 sections. Construction was undertaken by Volker Laser Ltd as principal contractor.

Project outcomes

The project was delivered on time in the summer of 2012 despite extremely high rainfall and the target cost was achieved.

The delivered benefits of the EKG system included:

  • Zero waste to landfill
  • No lane closures or traffic management requirement during works
  • Very low labour requirement during construction
  • Construction data demonstrated a reduction in overall carbon footprint of 42% compared to soil nailing and 76% compared to granular replacement
  • The preservation of topsoil and root bowls encouraged rapid re-growth on the site without the need for re-planting or seeding
  • All cables and junction boxes were reused from a previous project and were used again on subsequent projects.

Verification testing showed a significant reduction in water content and improvement in drained and undrained shear strength properties within the targeted treatment zone of 3m depth.

The post-project testing was carried out 18 months after completion of treatment and in comparison to pre-construction data showed:

  • Reduction in water content 5-13%
  • Increase in cu by average 90kPa
  • Increase in c’ 5kPa Phi’ 2-5°.

 

 

 

 

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