8/18/2019 VSL_____(2657)-1

1/2

 Anchor testing at the River Thames – England

Testing of 340 ground anchors after 30 years of service

▲  Anchors at Tilbury Fort and Tilbury Power Station.

The Environment Agency awarded

VSL a contract to carry out testing of

a large number of ground anchors

following a competitive tender

process. The anchors had been

installed by VSL more than 30 years

ago and the testing showed them to

have lasted very well despite the

The locations form part of a flood

defence system, which was installed

in the mid- to late-1970s and

incorporates approximately 340 VSL

ground anchors, many of which are

submerged twice daily by the tide.

Some have been under water since

the 1970s. The testing programme is

Scope of works performed

• Testing and inspection of▲ Grease that formed around the head

harsh tidal conditions.

The testing works were sited at fourseparate locations along the left bank

of the River Thames.

spread over a four year period and

includes testing and inspection worksin two phases.

The year 1 phase 1 testing and

inspection works were 100%

successful across all four sites. Out

of the 115 anchors tested during this

   I   D

   2   6   5   7

• Phase 1 and 2 type testing

• Suitability and acceptance

• Re-loading and adjustment

• Refurbishment

• Re-monitoring works

• Report and recommendations

o anc or num er was v s e

following removal of the

top hat cover. Remarkably the grease

was not adversely contaminated.

phase, a total of 76 anchors needed

to be re-adjusted to re-commission

them back to the original designed

lock-off loads. This enabled the

areas of the flood wall to return to

being fully effective in the event of

a flood.

www.vsl.com

8/18/2019 VSL_____(2657)-1

2/2

The inspection works proved that the

overall condition of the VSL anchors

and components at the live ends was

generally good. The corrosion

present was mainly at the surface.

This surface corrosion was removed

CLIENT

Environment Agency

MAIN CONTRACTOR

VSL Systems (UK) LTD

 

protected with new ‘hot applied’

grease, Denso Void Filler No 1,

which is specifically designed as a

dedicated corrosion-preventiongrease. The properties of the new

grease will help to arrest and prevent

the progression of future corrosion

DATE

2007-2010

▲ Prior to works commencing, ananchor shows heavy corrosion built

▼ The onset of high tide has fully submerged the anchors twicedaily for more than 30 years.

There would be high costs

associated with replacement of

anchors. It is more cost-effective and

.  

the operational life span of the

existing anchors now, rather than to

delay refurbishment work.

The VSL Ground Anchor System

installed in the late 1970s has proved

to be durable and dependable in the

this time that not a single individual

anchor has been adversely affected.

 

site and has stood the test of time,

despite a lack of maintenance.

The client, the Environment Agency,

is both impressed and delighted. Theresults are a tribute to the VSL

Ground Anchor System and All of the 115 live-end anchors have

been successfully inspected and fully

▼  A completely refurbished anchor with

a new ‘top hat’ protective cover 

  ,

and durability in withstanding such a

corrosive environment over such a

long period.

,

www.vsl.com   E

   d   i   t  e   d

   2   0   1   0

   I   D

   2   6   5   7

▲  Anchor number 10 (installed in 1978)is now in as-new condition with nosign of any corrosion.