How Deep Should Japanese Knotweed be Buried

How Deep Should Japanese Knotweed be Buried

Burying Japanese Knotweed is a specialist job as strict regulations must be met, but if you’re planning of burying Japanese Knotweed waste please read on.

For DIY burial pits you must contact your local Environment Agency and council offices for upto date advice.

Japanese Knotweed waste should be buried in at least a 5 meter deep burial pit.

In a 5 meter pit you can fill the pit upto 3 meters of knotweed waste, then a permeable membrane layer must be installed on top of the waste, then 2 meters of sand / soil can be installed to make up ground level.

If it’s not possible to to make a 5 meter pit on site the Japanese Knotweed can be buried at 3m deep but the waste must be packed into a completely encapsulated root barrier membrane cell.

Dig your burial pit to a depth of 3 meters, line the bottom of the pit with a thin layer of sand and then it should be lined with a suitable root barrier membrane material, this also should be covered with a layer of sand to help prevent any heavy machinery puncturing the bottom membrane as you fill it. You should allow enough membrane overlap up the sides of the pit to enable you to weld the membrane together giving you totally encapsulated cell or enough to install a membrane lid that will make your encapsulated cell.

Fill the pit with Knotweed waste to around the 2 meter level then seal the cell, take utmost care and check all the seals for small gaps then cover the cell with sand and soil to finish the job.

As Knotweed Rhizomes can remain dormant for 20 years it is vital the integrity of the membrane is sustained and guaranteed for at least 20+ years.

Utmost care should be taken and a detailed plan produced of where you are going to have your burial pit, it must not be in any location likely to be disturbed at a later date. Accurately map the location and advise the local Environment Agency and local council offices of the location of the Knotweed waste burial site to prevent potential disturbance and possible re-infestation in the future.

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