JAPANESE KNOTWEED
Figure 3: Knotweed Excavation with
Installation of Root Barrier
you are likely to spread any
remaining rhizomes or even cause
the knotweed to grow again. You will
also invalidate any guarantee that
came with the treatment. Change of
land use could include the following:
• Landscaping
• Driveway
• Extension
• Ground-levelling for shed or
green-house installation
• Pond installation
• Path
• Tarmacadam
An HTP cannot guarantee complete
eradication of the knotweed
rhizomes and any disturbance to
them could cause re-growth of the
aerial knotweed and the rhizomes to
restart growing.
Removal of Japanese knotweed is
achieved by complete excavation of
the affected soils. A root barrier can
be installed to prevent knotweed
ingress from neighbouring
properties, if necessary.
The knotweed-contaminated soils
are classed as controlled once
removed from site. Therefore,
an appropriate Waste Carriers
Licence is required to
transport the knotweed
contaminated waste,
which must be taken
to landfill site licenced
by the Environment
Agency to receive
knotweed.
Limitations of
Treatment
Herbicide treatment of
knotweed is adequate
in many cases and
provides very effective
control of knotweed.
Where there are plans
for a change of land use,
herbicide treatment
is not a feasible
remediation method
as the underground
rhizome is not removed.
If you disturb the
knotweed-affected area,
even after treatment,
Figure 4: Dig and Dump
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Where change of land use is
planned, you should advise that
excavation is the only suitable
method of remediating the
knotweed. Whilst excavation is a
more expensive option, paying for
the excavation before any ground
disturbance starts will be cheaper in
the long run.
Excavation Options
Not all properties or sites require
a full-depth excavation. When
we survey a site, we ensure we
understand the planned works. Our
recommended removal strategy will
be the most cost-effective, whilst
rendering the site ready for the
next stage of works, be it a pond, a
conservatory or landscaping.
Depending on the site size, we can
consider a dig and burial strategy,
where we bury the knotweed
contaminated soils on site,
encapsulated in a root barrier cell.
Alternatively, there is also the
option of a dig and relocate.
Using this method, we remove
the knotweed from where it’s
preventing the development of an
area and relocate it to an alternative
area. Once relocated, we treat it
in situ, with a standard herbicide
treatment programme.
The last option is dig and dump,
which involves digging the
knotweed affected soils out and
removing them to a licenced landfill
site. As a professional knotweed
company, the UK Government
encourages us via RPS 178 to only
consider the dig and dump option if
other options aren’t viable. However,
dig and dump is most often most
desirable option.
Know your Knotweed and your
Options
You probably feel confident in
identifying Japanese knotweed at
all stages of growth. However, if
you’re unsure about a plant, use our
free identification service: ident@
knotweed.co.uk. Send us an email
with a few pictures of the suspect
plant and we’ll get in touch with an
answer.
If you’d like to brush up on your
knotweed identification skills,
see the Japanese Knotweed
Identification page of our website.
You need to be confident you’re
adopting the right approach to
managing Japanese knotweed.
If you need help identifying
Japanese knotweed, need a
professional knotweed survey or
simply some general knotweed
advice, contact us on 0333 2414 413,
email [email protected] or
visit japaneseknotweed.co.uk
www.landud.co.uk
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