Cell Encapsulation

This involves the excavation of Japanese Knotweed from an area required by the customer to be developed with the contaminated spoil being buried to a pre-determined depth.

The EA guidelines state that ideally there should be one treatment with a non-persistent herbicide to reduce the vigour of infective material. Soil to a depth of at least 3m and within a radius of 7m of the plant growth should be excavated for burial.

The periphery of the excavation should be checked by the site manager to ensure that adequate volume of material has been removed.

On site burial should be performed to a depth of at least 5m. The potentially viable Japanese Knotweed material should be then covered with a geo textile membrane or a heavy gauge polythene sheet prior to infilling.

Advantages

  • Relatively fast results
  • Allows construction programme to commence more quickly
  • Works with phased developments

Disadvantages

  • Very site dependant
  • Cannot deal with boundaries or utilities
  • Logistically Complex
  • Requires large, deep excavations

Integrated Cell Encapsulation

This again involves the excavation of Japanese Knotweed from an area required by the customer to be developed with the contaminated spoil being buried to a pre-determined depth. The excavation of this area will be under the supervision of experienced staff, the rhizomes will be accurately followed to reduce the amount of material excavated. A suitable sized burial pit will be identified from the contaminated spoil and full GIS maps will be undertaken to show both the areas of excavation and the burial area.

The burial pit will be lined with a bespoke membrane with the entire joint being heat sealed by a team of experts. Only then will the contaminated material be placed inside the cell. Once the cell has been filled, the membrane will be placed on top and again the joints are sealed.

Advantages

  • Relatively fast results
  • Requires less excavation than standard burials – up to 70%
  • Material only needs to be buried 2m below final site level
  • Allows construction programme to commence quicker
  • Works with phased development
  • Material can be compacted

Disadvantages

  • Site dependant
  • Does not account for services
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