Arborfield Garrison (Parcel X and Y Licensed Asbestos Removal), Berkshire

OVERVIEW:

As part of a demolition programme of the entire Arborfield Garrison site, Lawson Environmental (part of Lawson Group) were contracted to remove licensed asbestos from buildings that formed an area known as Parcel X and Y.

CHALLENGE

This would be one of the larger phases of the programme so would need meticulous planning. Buildings 12, 11, 10, 07, 08, 06, 05, 04, 03 would need demolishing but only once the licensed asbestos materials had been removed from each building. Asbestos reports found licensed asbestos in 6 of the buildings, which were: 12, 7, 8, 6, 5 and 4.

SOLUTION

After identifying which buildings contain Asbestos Containing Materials (ACMs) in them, Lawson Environmental set about planning which buildings would be processed first and putting a methodology in place for each building.

Building 12

ACMs were located within the ceiling of this single storey disused dog kennel in the form of 15m2 AIB ceiling Tiles.

The ceiling tiles had been screwed on but not all screws were visible. These were removed using hand tools and cordless drills. The fixings were removed in conjunction with using shadow vacuum procedures (LEV). Once the first ceiling tile had been released, one operative lowered one side in order to make the back of the ceiling tile accessible for decontamination. The back of the tile was then carefully vacuumed and a water and surfactant mix was carefully applied by a hand held manual pump up spray to the rear face of the remaining tiles and left to penetrate. They were then lowered horizontally. The ceiling tiles were then placed into red bags, sealed and put neatly to one side until ready to be removed from the enclosure.

Any MMMF insulation in the ceiling void above was sprayed with surfactant and double bagged for disposal as contaminated waste. The tiles have been screwed into metal/timber tracking which was also removed and disposed of as asbestos waste. Setup was similar to that described in building 8 below.

Building 8 

ACMs were located throughout this building on both floors. There were areas of AIB debris on each of the floors, AIB ceiling tiles, AIB ceiling edging strips, AIB cladding to steel beams and columns, panels above and below windows, heater panels. Quantites found in this building were:

• 1Lm AIB ceiling packers
• 4m2 AIB ceiling tile debris
• 170m2 AIB ceiling tiles
• 300Lm AIB edging strip to ceiling
• 320m2 AIB panels above & below windows
• 124Lm panels above and below windows
• 340m2 AIB panels behind heaters
• 10m2 AIB strip to the sides of windows
• 16Lm AIB strip to the sides of windows
• 200Lm AIB lining to steel beams
• 240Lm AIB fascia boards in ceiling voids
• 3m2 AIB to back of fibreboard boxing
• 1Lm Paper linings with fuse box
• 2Lm Rope around flu for incinerator
• 1m2 Textile flash guard
• 2Lm Textile gasket to metal ducting joints
• 2m2 Textile pad within heater

Prior to any works commencing within the building, the decontamination unit was set up and all connections were made, including connections to electrical power (wired connection) from site supply or generator, to the water supply via a pumped tank and bottled gas.

Operatives carrying out the removal work wore red disposable hooded and elasticated coveralls. Safety wellingtons were also worn along with suitable hand protection. A positive powered respirator was also worn during removal works with red hooded and elasticated coveralls. Blue was worn during the transit procedure and white for all work outside the working enclosure.

The enclosures were formed using existing structural elements of the building and timber framework to which 1000-gauge polythene had been fixed. Staples were used to secure polythene sheeting to the timber framework. 75mm polycloth tape and spray adhesive were used on all joints and areas that needed to be sealed. The floor of the enclosure was formed again with 1000-gauge polythene and any joints were closed with 75mm tape.

A sacrificial sheet of polythene was used whilst removal took place. This sheet was disposed of as asbestos waste before any visual inspection or air monitoring was carried out. Vision panels were installed within the enclosure showing all areas, with more vision panels on the 3rd stage of the airlocks and baglocks. These enclosures were located in three areas external to the building, as shown in the plan at the top of this page. Enclosure airlocks were constructed using 1000-gauge polythene, fixed over square sectioned metal tube frames approximately 1m wide x 2m high. All joints and seams were then also sealed with 75mm polycloth tape. The middle and third compartments of the airlock included washing facilities for personal decontamination prior to entering the DCU.

The baglock for bag transfer was incorporated onto the external part of the enclosure for the transfer of waste. The third compartment of the bag lock also included cleaning facilities for decontamination and cleaning waste bags before being double bagged.

Vision panels were installed in the enclosure and the dirty end of the Airlock and Baglock. No removal works would be carried out unless it could be observed from the vision panels.

Negative pressure units (NPUs), giving a minimum effect of 10 changes per hour, were attached to the opposite end of the enclosures from the entry and exit points. The size of the NPU depended on various inputs and this was noted in volume of enclosures where applicable. The NPU vented to an external atmosphere wherever possible.

Operatives, wearing type 5/6 white overalls and half mask fitted with a P3 particulate filter, accessed the external areas of the building at ground level. The external timber fascias, which were painted blue, were covered with 1000g polythene and sealed with timber which was fixed to the existing building frame. This was required to enable the AIB panels to be removed internally without losing negative pressure. All ill-fitting windowpanes were made airtight using expanding foam. On completion of the construction of the enclosures, a smoke test was carried out in the enclosure area.

The ceiling tiles were removed using a similar process to that used in building 12. AIB cladding to beams was accessed from the floor but where necessary, scaffold towers or podium steps were used.

The AIB Cladding had been fixed to the structural beams with flat headed screws which were visible in most places, these were removed using hand tools and cordless drills to reduce breakage – this was completed using the shadow vac technique. The longest length of AIB Cladding was approximately 8 feet long. A baglock of suitable size was constructed to allow for double wrapping of this size of waste. If any waste was too large for the bag lock then it was double wrapped in 1000-gauge polythene, left in the enclosure and passed off as part of the four-stage clearance.

Once the AIB cladding had been released, one operative applied an application of fibre suppression to the back of the AIB which was then lowered horizontally onto a prepared polythene sheet – this polythene sheet was used to wrap the cladding.

Fully trained operatives accessed the windows from ground level, the plasterboard that surrounded the windows was carefully removed using small hand tools whilst employing similar techniques already mentioned before. The same applied to the AIB panels located behind radiators as well as panels above and below windows.

To remove the AIB Fascia boards in the ceiling voids, operatives erected a 3-sided enclosure inside the platform of a scissor lift. It contained all the equipment required to remove the AIB panel including Hvac hoovers and handheld pump sprayers. Operatives treated the fascia panel as they would for a full enclosure – using a powered full face RPE and red overalls. Once at the correct height, external aluminium fascias were removed to expose the AIB panels. The panels had been screwed on, but not all screws were visible. These were removed using hand tools and cordless drills. Like before, all the fixings were removed in conjunction with using shadow vacuum procedures (LEV).

Once a panel had been released, a fully trained Lawson Environmental operative lowered one side in order to make the back of the panel accessible for decontamination. The back of the panel was carefully vacuumed prior to applying an application of fibre suppression fluid and then was lowered horizontally. The panel was then placed into red bags, sealed and put neatly to one side until ready to be lowered.

Any MMMF insulation that was found in the ceiling void above was sprayed with surfactant and double bagged for disposal as contaminated waste. Anything that the panels were screwed or fixed to was treated as AIB waste.

All waste was lowered in the scissor lift to ground level, one operative exited the platform whilst a second operative passed the bags of waste to the first operative on the ground who then carried them to the waste skip via a 3-stage bag lock. All removal of waste was carried inside a pre-erected respirator zone and under the control of the supervisor.

Building 7

ACMs were located within the ceiling, walls doors and corridor of what was a single storey, disused workshop. A DCU was on site, operational and was directly connected to the enclosure. Bag and Airlocks were positioned at the furthest point from the NPUs. The waste route was as short as possible. A similar setup and process was used as per Building 8 above. ACMs to be removed included:

• 120m2 AIB ceiling tiles
• 14Lm AIB edge seals to doors
• 82Lm AIB edging strips to ceiling
• 37Lm AIB panels behind radiators
• 12Lm AIB external facias to the corridor

Building 6

In the largest building on this parcel, ACMs were located throughout the building to all 4 floors. A DCU was directly connected to the ground floor enclosure. A transit route was established for the 1st, 2nd and 3rd floors.

First floor enclosure was accessed via the main entrance. Negative Pressure Units (NPU’s) were positioned at ground level for Enclosure 1, NPU’s for the 1st, 2nd and 3rd floors were positioned on each floor. Waste and transit routes from the 1st, 2nd and 3rd floors were via the building’s existing staircase. AIB Fascia boards in ceiling voids were removed from an enclosed scissor lift, utilising a 3-sided partial enclosure erected inside the scissor lift platform to remove the fascia panels.

Again, a similar setup and process was used as per Building 8 above. ACMs to be removed from this building included:

• 554 Lm AIB panels above and below windows
• 64Lm of AIB panels between ceiling void steel and window
• 1m2 AIB panels behind radiator
• 20Lm AIB lining to steel beams
• 590Lm AIB fascia boards in ceiling voids
• 24m2 Ceiling panels to canopy

Building 5

The ACMs in building 5 were located throughout the building on both the ground and 1st floor. A DCU was directly connected to enclosure one, but was indirect for the remaining enclosures where a transit route was established.

Enclosure one was set up to be accessed via the main entrance. Negative Pressure Units (NPU’s) were positioned at ground level for all ground floor enclosures, the NPU’s for the remaining enclosures were positioned as per the agreed plan. Waste and transit routes for the remaining enclosures were via the building’s existing staircase. AIB fascia boards found in the ceiling voids were removed from an enclosed scissor lift utilising a 3-sided partial enclosure erected inside the scissor lift platform. A similar setup and process was used as per Building 8 above. ACMs to be removed from this building included:

• 734Lm AIB panels above and below windows
• 60Lm AIB panels behind radiator
• 90Lm AIB cladding to steel columns
• 442Lm AIB fascia boards in ceiling voids
• 128m2 AIB ceiling panels
• 6m2 AIB door panels
• 246m2 AIB ceiling tiles
• 288m2 AIB ceiling edging strips
• 32m2 AIB wall panels
• 4m2 AIB ceiling panels in lift shaft

Building 4

Building 4’s ACMs were located throughout the building. Like the other buildings, a DCU was indirectly connected to the enclosure with an established transit route. The enclosure was accessed via the main entrance. Negative Pressure Units (NPU’s) were positioned at the fire exit.

AIB fascia boards in ceiling voids were removed from an enclosed scissor lift utilising a 3-sided partial enclosure, erected inside the scissor lift platform to remove the fascia panels.

A similar setup and process was used as per Building 8 above. ACMs to be removed from this building included:

• 42Lm AIB cladding to steel columns
• 74Lm AIB ceiling void fascias
• 45Lm AIB panels behind radiator
• 4Lm AIB boxing panels

RESULT

All buildings on Parcel X and Y that contained ACMs were successfully decontaminated ready for the demolition stage.

To find out more on how Lawson Group can help with your next demolition or asbestos removal project, call 01793 782000, email enquiries@lawsongroup.co.uk.