Waste Water Treatment Plant Bund Lining
THE PROBLEM
The effluent plant bund was suffering from chemical attack and degradation. A new chemical resistant bund lining was required as part of the bund refurbishment project.
THE SOLUTION
Because of the variety of substrates with potential differentials of movement and evidence of cracking we proposed the application of an elastomeric yet highly chemical resistant Polythiourea (PTU) bund lining from Specialty Products Incorporated.
Initially the bund floor was prepared using a vacuum controlled surface scarifier. Upon commencing preparation works it became apparent that the asphalt and cementitious substrates were in fact toppings on the original concrete slab. Therefore these toppings were removed from the bund floor using vibration damped breakers to provide a sound base for the new bund lining. This was followed by vacuum controlled diamond grinding to remove any remaining contaminants and surface laitance.
Channels were then cut to allow the installation of the new drains that would guide any leaks or spills towards the sump and allow easy clean up. The drains were set in place using a rapid setting cementitious mortar.
When satisfied with the preparation works the concrete slab was primed using a moisture tolerant epoxy primer. This was applied in two coats to form a liquid applied damp proof membrane due to the age of the building. This guards against rising moisture that could cause blistering in the new bund lining.
Once cured falls were installed in the bund using a polyurethane mortar from Resdev (Pumabulk) with a 1:90 fall. This product was selected because of how it ‘closes out’ giving a very sealed surface – making it particularly suitable for use with Polythiourea and Polyurea bund linings. A cove was installed using a polyurethane coving mortar to isolate the bund floor from the walls which is a common point of movement.The bund was then primed to fully protect against outgassing and pin holing in the subsequent spray applied bund lining.
Only when fully satisfied with the preparation and priming works did we commence the spray application of the Polythiourea bund lining. Because this material is spray/liquid applied it can easily be used to seamlessly incorporate details such as brackets and feet – making it ideal for bund linings. The lining was sprayed into a previously cut chase at the the top of the cove to prevent the formation of an exposed edge which would present a weak point in the bund lining.
Finally the fibreglass drain covers were cut to size and the the top edge of the bund lining sealed using a polyurethane jointing compound to ensure a truly seamless finish.