2015:447 - Gardens and St Mary’s Parish, Kilkenny, Kilkenny

Monitoring of demolition works was carried out within the grounds of the former Smithwick’s St Francis' Abbey Brewery, Kilkenny City, on an intermittent basis from 14 September 2015 to 8 September 2016. The brewery is located in the city centre on the western bank of the River Nore and the site contains St Francis' Abbey (KK019-0260110-) which is a National Monument in state ownership, as well as other monuments including Evan’s Tower, a portion of the city wall, the site of St Francis' holy well and the site of a tower (all included under National Monument No. 72), a bridge site (KK019-026102) and remnants of the Bull Inn (KK019-026107). Immediately outside the complex’s boundary wall along the River Nore a 19th-century Tea House (B119 and NIAH 12000204) of architectural and historical heritage interest is also located.

Monitoring of demolition activities was carried out on behalf of Diageo Ireland and the programme of monitoring works was carried out in response to planning conditions (P13/43 condition 3, P13/44 condition 3 and P13/45 condition 3). Monitoring focused on demolition activities in the vicinity of the Bull Inn, Evan’s Tower and the city wall, St Francis' Abbey and the Tea House. Vibration monitors were placed on each of the monuments and vibration limits were set in accordance with international best practice for historic structures. A vibration cut-off threshold of 4 mm/s peak particle velocity was in place in line with Eurocode 3 Part 5 for transient vibrations close to ruins or buildings of architectural merit. A reading of between 3–4mm/s was linked to an amber light which resulted in work ceasing in that area until the demolition contractor amended their methodology to reduce vibrations to insure the safety of the historic structures. The demolition methodology in conjunction with an archaeological presence on site combined to keep vibrations at low levels throughout the demolition project in order to protect the vulnerable monuments within the site. It was not necessary to have an archaeological licence in place to monitor the demolition works, however Registration Number E001071 was allocated for the recording of cut stone recovered during the demolition of a wall in the vicinity of the Bull Inn (KK019-026107) and the site of a 16th/17th-century dwelling (KK019-026122). The purpose of the monitoring was to oversee the stabilization works to Evan’s Tower and the Bull Inn in advance of demolition, and generally to monitor demolition activities on the site to ensure that the protection measures agreed for the National Monuments on the site were adhered to and to be in a position to advise on changes to the demolition methodology in order to mitigate any impacts from demolition.

Consultation took place with the other members of the conservation team throughout the demolition (conservation architect and structural engineer). The scope of the work comprised the installation of temporary stabilisation works for the demolition works and the demolition and removal of the specified above-ground structures on the site to the top of the existing ground slab level. The demolition contractors on site were John Tinnelly and Sons Ltd and the vibration monitoring was provided by Glenside environmental.

The Bull Inn

In advance of the demolition of the structures in the vicinity of the Bull Inn, vegetation was removed from the recorded section of the Bull Inn wall and the surrounding area under archaeological supervision. The previously recorded section of the Bull Inn comprises the east wall of the inn and was thought to be the last upstanding remains of the structure. From the street, the east wall of the inn presents as a substantial wall approx. 4.5m high. On its east face there is a chamfered stone ope situated 1.1m above present ground level and there are large square quoin stones in the south-east corner. The window is almost identical to one recently discovered in the gable wall of No. 22 Vicar Street (KK019-026122) during archaeological investigations (Flynn, 2015). Modern repairs are evident on the east face as areas of concrete blocks, and a chimney flue is set into the wall. The wall is constructed of random uncoursed rubble limestone.

On its west face densely matted ivy was present, with much of the root system embedded in the wall. The vegetation was removed as far as was possible without dislodging stones and what was not possible to remove was drilled and treated with a biocide to prevent re-growth. Modern repairs to this side of the wall are more extensive, with several areas of concrete blocks and cement. For the most part the wall survives to c.3.5m in height, with an additional c. 1m in height at the north end. When the vegetation was removed to the west of the previously recorded section of the Bull Inn, it became apparent that some of the west wall of the inn may in fact have survived unrecorded, albeit with a large breach repaired with concrete blocks. The suggested west wall presents from the street as a rendered wall c.2.5m high with gates on both sides and it is only within the property that its similarity to the east wall is apparent.

Remnants of a rear return to the building are evident in both the east and west walls, measuring 0.8-0.9m thick and tapering slightly to the top. The portion of rear return on the west wall includes a re-used tooled stone at high level. Map sources indicate that this return was removed prior to 1841. There is an internal rebate present on both the east and west walls at c.1.7m high, further indicating that they are part of the same structure. The west wall measures c.15m in length with a large breach measuring c.6m repaired with blocks mid-way along its length. The 1871 revised edition OS six inch map provides the best map-based evidence for the west wall being part of the original Bull Inn structure.

Like the east wall it is depicted as a thick wall which changes to a lesser wall beyond the portion of the rear return. Extending from the south of the west wall of the Bull Inn, a later boundary wall includes fragments of re-used finished stone.

 

A monument report form was submitted to the Archaeological Survey of Ireland in November 2015 in relation to the discovery of the additional remains of the Bull Inn and the online record has now been updated to reflect this.

 

During demolition of the east boundary wall of the car park adjacent to No. 22 Vicar Street and the Bull Inn, 13 cut and tooled stones that had been re-used in the wall were recovered. These stones were labelled and placed on pallets and on completion of the works were stored in Kilkenny County Council lands north of the River Breagagh. The stones are located near to a collection of other stones retrieved during work on the adjacent Central Access Scheme (CAS). 

 

Evans Tower

In advance of demolition the following works were carried out to stabilise Evans Tower and the City Wall. Vegetation was removed from the tower and section of city wall and roots within 2m of the monument were drilled and treated with a biocide. Following removal of the vegetation, vibration monitors were installed as per the instructions of the structural engineer and the old propping was removed. Once the propping was removed a laser survey was carried out (Kieran O’Shea, Laser Surveys) and new propping was installed as per the designs of the structural engineer. This comprised timber stabilisation works in the form of two sets of shoring to the wall walk wall, one prop to the wall walk wall and one brace to the west wall of the tower to stabilise the large opening here. These works were all carried out under archaeological supervision.

 

Readings on the vibration monitors were checked several times each day during monitoring and when works were immediately adjacent to the tower and city wall they were observed constantly. The purpose of this was to be in a position to amend demolition methodology when particular activities were increasing the vibrations, but were still within limits. The city wall was quite sensitive to activities both on the site (up to approximately c. 50m distance) and possibly also on the neighbouring site to the north where the Central Access Scheme (CAS) bridge was under construction.

 

The buildings in the immediate vicinity of the tower and city wall (kegging plant) were dismantled by first removing the cladding and roofing which was lowered to the ground on scissor lifts, then the steel frame was cut into pieces and lifted away and the block work walls were taken down using a rubber-tyred machine with a grab attachment to lower sections of block work to the ground piece by piece. Rubber tyres and crushed rubble were placed on the ground to reduce vibrations from falling block work.

 

The demolition of the kegging plant was completed with a total of five amber and one red vibration alerts, all on the city wall, which appeared to be much more sensitive to vibrations than the tower. Some of the vibration alerts did not appear to have been caused by the demolition works, with either no works taking place in the vicinity or the alert occurring before work commenced in the morning. In these instances it was thought possible that activities on the neighbouring site (CAS bridge) may have caused the vibrations. On two occasions it was clear that rubble clearance and the removal of a steel column in the immediate vicinity of the tower and city wall were responsible for causing amber alerts. Two alerts, a red and an amber, occurred on the same day when there was no work taking place in the vicinity of the tower and city wall. In this instance the closest work taking place was segregation of materials c. 50m to the south and the nature of this work was thought unlikely to cause such vibrations at the city wall. On each incidence of an amber alert, work in the vicinity was halted and an assessment of the cause of exceedance carried out and an incident report form filled in and circulated to the conservation team. Where a cause was evident measures were put in place to avoid further exceedances before work re-commenced. On the occasion of the red alert at the city wall, all work on the site was halted and an assessment of the cause of exceedance carried out and an incident report form filled in. Glenside Environmental concluded that corrosion on one of the leads was the likely cause of the red vibration alert and once the conservation team had all been informed and the unit replaced, work re-commenced. 

 

St Francis’ Abbey

Hoarding was erected around the perimeter of the Abbey well in advance of demolition and two vibration monitors were installed, one on the west end by the entrance and one on the east end at the base of the east window. Activities in the vicinity of the Abbey comprised removing large tanks from the boiler house to the south-west of the Abbey and the demolition of structures to the south and east. The activities in the vicinity of the Abbey resulted in minimal vibrations being recorded and it appeared that the make-up of the ground surrounding the Abbey was favourable for absorbing vibrations.

 

The Tea House

Monitoring of the demolition process in the vicinity of the Tea House took place over three days from 5-8 September 2016. A vibration monitor was placed on the adjacent boundary wall south of the structure to be demolished (Brewing Material Store Building) and a visual condition survey of the Tea House was completed in advance of the proposed dismantling works (Rowntree 2016). The structure had recently undergone weatherproofing works by Tallis Construction under the guidance of Kilkenny County Council.

 

Readings on the vibration monitors were under constant observation by the monitoring archaeologist as the demolition work progressed and as before, amber alerts were followed by work stoppage, assessment of cause and changes to the methodology.

 

None of the monuments on site showed any signs of damage as a result of the demolition works.

 

Reference:

Flynn, C. (2015). Archaeological Test Trenching, Monitoring & Excavation Interim Report, Kilkenny Central Access Scheme, Kilkenny City, Ministerial Direction A62, Registration Number E4437, 20-22 Vicar St. Unpublished report for Valerie J.Keely Ltd.

Courtney Deery Heritage Consultancy, Lynwood House, Ballinteer Road, Dublin 16