Case Studies

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The site is prominently positioned on the junction of Castle Street and Stembrook, immediately adjacent to the town centre car park and directly opposite the new St James’ retail and leisure development, to be anchored by Marks & Spencer, Next and a 6-screen Cineworld cinema.

Other tenants in St. James’ will include Superdrug, Carphone Warehouse, Costa Coffee, Frankie & Benny’s, Nando’s and Bella Italia, together with a new Anytime Fitness gym, Travelodge and a further 445 car parking spaces. The area is set to improve significantly and become the premier retail and leisure destination in Dover, providing substantial opportunity for further, complimentary residential or commercial development.

55–61 Castle Street was split over 2 commercial property sites; The former Action Carpets whose frontage is onto Castle Street and the former Co-Innovation Centre which fronts onto Stembrook.

Google Earth image – Demolition and enabling works package area demarcated in a red pathway outline.

Site constraints

1. The site is bounded on the West and South elevations by busy city centre roadways

2. The rear of the former Co-Innovation Centre (East) fronted onto River Dour

3. River Dour run through a culvert underneath the Former Action Carpets building.

4. Pencester Court, Pencester Gardens Park, and mature trees at the north elevation of former Co-Innovation Centre.

5. Demolition was to be carried out in two phases. Phase one was to commence no later than 1st March 2022. Phase two could commence only after the Environment Agency approved the Flood Risk Activity Permit (FRAP) to enter the river, which was scheduled to be after May 2022 due to fresh water fish spawning.

Dorton Demolition & Excavation Limited (Dde) were awarded the demolition and enabling works contract through competitive tendering.

Brief summary of the demolition and reinstatement works:

1. Removal of all asbestos containing materials positively identified in the R&D Asbestos Survey Report. Dde noted non-accessible areas contained within the report and made allowances for surveying these areas as required during the works

2. Working in close proximity to a water course. Full height and length of existing external wall along River Dour was to remain insitu during Phase one. Dde was to carry out a structural survey to this wall and design and install any temporary support works necessary.

3. Removal of all MEP plant and associated kit.

4. Soft strip and Demolition of all structures above the finished floor level including the removal of floor and screed finishes – predominantly ceramic floor tiles and screed.

5. Reduction of external walls to 1.20m above ground floor slab level along the River Dour in Phase two. Door openings were to be infilled and new precast concrete capping laid onto the reduced boundary walls. Repairs were to be carried out to the existing brickwork and concrete floor slab as necessary.

6. Following demolition all voids and disrepairs were to be backfilled using rolled asphalt concrete. The site was to be left open and level with borders left smooth and flowing where possible with falls for adequate drainage.

7. Knee rail fencing was supplied and installed to site boundaries.

Challenges

1. Initial access to the building for a demolition rig was by opening up the front face along Stembrook. This access was chosen due to it being an area with the least traffic. The only traffic using this access road is to Pencester Court. Site traffic used a one-way system to arrive and depart from site. A banksman controlled the interface between the site and the road. As demolition progressed, the Heras fencing and Chapter 8 barriers were stepped back into the site boundary.

2. Dde prepared and submitted a method statement to the Environment Agency in connection with the FRAP permit outlining how the walls adjacent to the River Dour were to be reduced and how the risk of dust and debris from entering the river was to be significantly reduced/mitigated. This included the walls adjacent and over the culvert. The culvert carried through the site and Castle Street emerging behind Dolphin House at the Market Square.

The FRAP permit was granted in April 2022 with conditions to ensure no increase to flood risk or detrimental impact on drainage, to prevent and minimise environmental harm, and ensure that the activities do not cause the spread of invasive non-native species. Japanese Knotweed along the river bank was undergoing a treatment plan and was to be undisturbed during the demolition activities.

3. During demolition, Dde uncovered three steel breather pipes sticking up out of the concrete slab. This suggested the possible presence of underground fuel tanks. The history of the site confirmed that the site was previously, in 1936, a motor garage and showrooms.

15 May 1936 Dover Express

11 January 1946 Dover Express

Reconstructed Castle Street premises

Dde on consulting with Dover District Council undertook a Ground Penetrating Radar (GPR) survey to establish the presence, if any, of underground fuel tanks.

Two structures with curved top surfaces were detected corresponding to the edges of cylindrical buried tanks. A large composition zone of disturbed ground corresponding to the location of a demolished or extracted tank (alternatively could simply be a poorly backfilled former excavation or demolished basement) was also recorded.

4. Potential asbestos containing material was discovered underneath the external glazing to the former Action Carpets building. This had not been identified in the asbestos demolition survey report. Works were immediately stopped pending sampling and testing by the surveying company. The laboratory report confirmed the presence of asbestos cement. There was no resulting impact on the completion date as Dde were ahead of the Contract Programme.

5. An Employer’s provisional sum was included in the Contract for remedial works to the site on completion. This was to be decided by the Council once the superstructure was demolished.

The existing metal handrail system along River Dour was deteriorated and Dde were instructed to replace with a new 1.10m high Key Clamp Barrier system with mesh infill panels. The Barrier system was also to be installed along surfaces with level changes.

Site on completion

When the demolition works were completed, all waste was removed from site and processed and recycled wherever possible. Asbestos contaminated materials were taken to a licenced tipping facility. Surplus aggregate arisings were taken to a local recycling yard and processed for reuse within the construction industry.  Bricks, roof tiles and timber floor boards were salvaged and taken to our reclamation yard in Burgess Hill, West Sussex. The recycling target achieved for this project was in excess of 95%.

Demolition was completed on time and within budget. Regular communication with the Council, neighbouring residents and businesses, and prompt response actions resulted in another successful demolition project.

The project success was also testament to meticulous planning and preparation, and was completed to the full satisfaction of the Client and local residents, without a single health and safety incident.

The site was registered with Considerate Constructors’ Scheme with a rating of

‘Excellent’.

This project was certainly challenging.  There were ‘live’ buildings in close proximity to the site – including the very busy Castle Street.  We had to maintain 24-hour access to Pencester Court and Stembrook Car Park in case of an emergency. A dedicated banksman directed all traffic movement outside the site boundaries. Parking of site vehicles was confined within the site compound. Wheel washing and road sweeping was managed on a daily basis.

Major risks were associated with this project.  The biggest risk was the potential collapse of the external wall along River Dour as the demolition works progressed.  A maximum amount of planning, preparation and care was therefore taken to prevent unexpected collapse. The wall was reduced by hand from inside the site. Ply board sheets were tied into the scaffold handrail system to act as an additional barrier to debris from entering the river.

The demolition work was further complicated by the occupied Pencester Court in close proximity to the demolition site. The tenants were highly sensitive to noise and dust; and this could not be compromised under any circumstances.  We organised and implemented a vibration monitoring programme – and are pleased to report that acceptable vibration levels were not breached once. Noisy work was only carried out during sociable hours. A water dampening system provided regular dampening down for dust control.