I have been in communication with Cardy Construction and Thanet district Council about the condition of the cliff façade. My take being that whatever happens over the Pleasurama issue the doubts of the cliff there have to be resolved.
It is my intention to report both the cliff façade and the sea defence as safety issues and below is a first draft, of the cliff façade part of this report, any help improving this would be appreciated.
In the first instance plans for The Royal Sands development were submitted and approved without investigating the civil engineering problems peculiar to the site.
About half of the planning sheets relating to the development are on http://www.ukplanning.com/thanet Application No: F/TH/03/1200, it should be noted here that pages on this site do not retain the same web address so it isn’t possible to bookmark them or send links to them by email.
The plans were changed on several occasions due to concerns about the height of the development, the issue being that the height of the development, for which plans had been approved, was greater than the distance between the baseline of the building (the existing promenade) and the height of the cliff (public footpath gardens and bandstand in the cliff top).
This is mostly relevant here because the reduction in height was partly achieved by lowering the ground floor ceiling of the proposed development, this meant the two-way access road through the development (residents cars and HGVs delivering to the hotel and retail units and removing refuse) was moved into the 4 metre gap between the back of the development and the cliff façade. There are potential problems here with lorries trying to manoeuvre past other vehicles catching the cliff façade support columns and the columns supporting the building.
After the planning consent was approved the intention was to build the development using the driven pile method of construction, as the concrete cliff façade appeared to be in poor condition (visible cracks with vegetation growing out of them) I raised concerns with the council about its condition.
In 2005 the cliff façade was inspected, see http://thanetonline.com/cliff/id2.htm this inspection was a visual inspection of the exposed parts of the façade and didn’t include any investigation of the façade foundations or the brick part of the façade at the north-eastern end of the site which was constructed in 1860.
Please note 6.34 Conclusion “Marina Esplanade façade is in a condition that would be defined as of short serviceable life.”
Work on the façade maintenance regime occurred during 2009 this mostly consisted of filling the cracks, coating the façade and resurfacing the cliff top footpath above the façade to mitigate surface water ingress behind the façade. There was also extra work using soil nails to increase the structural integrity of the area where the upper barrier had moved horizontally, see http://thanetonline.com/cliff/id4.htm Appendix D.
Scaffolding was erected for the work and this involved some levelling of the ground adjacent to the cliff façade it was at this point that I first noticed that aspects of the cliff façade foundations seemed inconsistent with the rather limited foundation designs published in the reports.
I can send you copies of the emails about this between me and Jacobs if you require confirmation of this.
After the façade maintenance work was finished at the end of 2009 I was concerned that part of the façade appeared to be bulging and that there should be some sort of inspection of the façade foundations so I contacted the council.
At the end of 2009 beginning of 2010 the council arranged for the bulging part of the façade to be hacked out and rebuilt, but didn’t appear to address the issues relating to the façade foundations.
Around this time the developer SFP appointed the third main contractor as the main construction firm for the new development, Cardy Construction.
I discussed the issues relating to the cliff faced with their MD ***** ***** on several occasions both by email and by telephone. I think a fair summery of the various communications is that he wasn’t happy about the façade foundations, the overall condition of the façade or the quality of the work on the repair to the bulging part.
Early in 2010 Cardy Construction made a limited investigation of the south-western, portal part of the façade, see http://thanetonline.com/cliff/index.htm most of this façade consists of a line of square cross section concrete pillars, forming oblong portals, cast against the inclined chalk cliff face. Above these is a solid concrete cliff wall, or apron, cast onto the chalk cliff face which has had dovetail horizontal grooves cut into the chalk to it to give additional support to the apron.
My understanding is that the upper, apron part of the façade was built first and originally sat on top of the bare chalk cliff which stepped out at the level of the bottom of the apron, the portals being erected at different times as the chalk beneath the apron deteriorated.
The largest and most substantial looking of the pillars is in the form of a buttress which 2010 Cardy Construction’s investigation says has inadequate foundations and the short term remedial underpinning they recommended in 2010 has never occurred.
It also begs the question: if one pillar foundation in the portal part of the façade was investigated and found to be inadequate, why weren’t the other foundations there investigated?
During 2011 more cracks, another bulge and significant amounts of vegetation appeared on the façade and once again I contacted the council and asked them to inspect the façade.
This inspection occurred in 2011 or very early in 2012 as the draft report was dated 2/3/2012, see http://thanetonline.com/cliff/id14.htm firstly I should point out that the remedial work recommended then hasn’t occurred.
The most concerning aspect of this inspection report concerning the façade foundations are 6.1 which says that the foundations and subsoil was exposed by the construction work which occurred in 2010.
I should point out here that the pillars of the portal section are not supported by the chalk cliff being stepped, as they are in the arched section. This means that the entire load of the concrete pillar plus any additional load from supporting the apron appears to be sitting chalk subsoil which has been exposed now for around four years and will have been subject to weathering.
Such design drawings as are available show concrete load spreading pads in the form of an inverted T however in many cases the profile of the façade pillar continues below the concrete in chalk. It wouldn’t seem possible that an inverted T could have been dug in the chalk and the concrete poured into it, so it would seem unlikely that there is any load spreading provision for these concrete pillars.
Either the profile of the pillar has been dug down below the exposed level and what is visible is the chalk adhering to the concrete, or the concrete pillar is sitting an exposed chalk pillar. This is a problem that needs investigation.
The other part of the cliff façade needing serious investigation is the 1860 brick structure at the north-eastern end of the site. The rest of this structure, steps and tunnel portal collapsed with no warning in the 1960s, the cliff was surveyed and during the rebuild there was a further large chalk fall there which demolished much of the reconstruction work.
It isn’t possible to see the foundations of the two large brick pillars as they have not been exposed during construction work. The foundations of the brick buttress wall between them has been and still is exposed and isn’t sitting on solid chalk but on some sort of made ground which appears to contain a proportion of topsoil, chalk pieces and brick rubble.
From the point of view of the development restarting to the approved planning application F/TH/03/1200 the significant issues are:
Is the cliff façade safe enough for work to commence on the development and if not what are the costs involved in making it so?
What is the expected life of the cliff façade?
Is it possible to adequately and economically maintain the cliff façade in the 3 metre gap between the cliff façade and the development?
The big question though is will there be proper economic and civil engineering provisions made to ensure the cliff façade is and remains safe for people to live under it for the life of the development?
My own opinion is that trying to patch up a cliff façade “of short serviceable life” is unlikely to be the best solution both economically and in terms of public safety.