This is an HTML version of an attachment to the Freedom of Information request 'Report Ecclesbourne Glen – Landslides – 2014 – ref: 02255A - 25 September 2014'.


 
 
Our Ref:02255A 
Your Ref: Purchase Order Number 376142 
 
25th September 2014 
 
Hastings Borough Council 
Aquila House 
Breeds Place 
Hastings 
East Sussex 
TN34 3UY 
 
For the attention of: 
 
 
Dear 
 
 
RE:  Ecclesbourne Glen – Landslides - 2014 
 
We write in response to your enquiry for further information of earlier this month, namely: 
notwithstanding any restrictions that may be imposed by others, what actions could be taken to prevent 
or reduce the likelihood of further slips at Ecclesbourne Glen and the effect that such may have

 
By this, we presume that you are referring to preventative actions on land within the Council’s 
ownership/domain. We also presume that your enquiry above relates essentially to the larger landslide 
which extends into the Rocklands caravan park. In formulating this response, and to put in context, we 
refer also to our “Desk Study and Inspection” report of May 2014, which should be considered in 
conjunction. That report included several conclusions, summarised in Attachment A. 
 
While the general form of the landslides has been defined by the inspection, and it has been 
determined that water is a significant factor/influence, it is not possible at this stage to identify 
definitively the driving mechanism and triggers without determining more detailed characteristics, such 
as ground and groundwater conditions, depths of movement, etc. Without such an appropriate model or 
understanding, the most appropriate/cost-effective remedial measures cannot best be selected or 
implemented. 
 
Given that water is such a significant factor/influence, removing water from out of the middle and lower 
sections of the landslide mass (i.e. land within the Council’s demesne) will almost certainly have a 
positive impact in enhancing the stability. However, as indicated above, without the detailed model and 
better understanding of the driving mechanism and triggers, that impact cannot be accurately 
quantified.  
 
The installation of counterfort borehole or push-in drain (e.g. “Plati-Drain”) or herring-bone land 
drainage could draw water out of the middle and lower sections of the landslide. The outfalls of such 
drainage are critical; they need to be carefully selected and designed so as not to cause or accelerate 
instability downslope of the current study area.    
 
 
 
Coffey Geotechnics Limited 
 
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T (+44) (0) 161 499 6800 F (+44) (0) 161 499 6802 coffey.com 
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Registered in England No. 06328315  

We trust this provides you with further guidance in relation to your enquiry, but appreciate this may not 
fully address your concerns.           
 
Yours sincerely,  
For and on behalf of Coffey Geotechnics Limited 
 
 
Coffey Geotechnics 

02255AA_L_003A_RDSfurther-advice-letter 
24th September 2014 

Attachment A 
 
The conclusions of our “Desk Study and Inspection” report of May 2014 are summarised as follows: 
 
  The inspection identified two recent landslides at Ecclesbourne Glen. The larger/main of these 
is located to the west and extends into the Rocklands caravan park, while the smaller is to the 
east, adjacent to the watercourse near the bottom of the glen. The occurrence of the landslides 
has resulted in the closure of several public footpaths crossing the study area. 
 
  Both landslides are indicated to have been activated within the last couple of years, coincident 
with periods of extreme heavy rainfall. The larger landside appears to be complex and 
retrogressive, while the smaller appears to be shallow and translational in nature. Both 
landslides appear to be highly sensitive to water, and are inferred to be active; further 
movements are likely to occur associated with wet meteorological conditions. 
 
  Recommendations were given in terms of short and intermediate to long-term actions in relation 
to the two landsides. These recommendations take account of activities and land-uses at and 
adjacent to the two landslides, and potential risks, but also take cognisance of the fact that the 
study area is located within a SSSI and SAC. 
 
  The recommendations do not relate to major remedial works to stabilise the landslides; it would 
be more cost-effective to relocate and rebuild the footpaths and associated drainage which may 
assist in managing groundwater in the landslides/catchment zone. 
 
  Further investigations should be undertaken in full co-operation with the owners/ management 
of the Rocklands caravan park, to manage adverse impacts upon the SSSI and SAC. To this 
end, details of the existing drainage systems and freshwater supplies at the caravan park need 
to be investigated and determined.       
 
Coffey Geotechnics 

02255AA_L_003A_RDSfurther-advice-letter 
24th September 2014