PUMPS, WASTE MANAGEMENT & WATER TREATMENT More efficient drainage stack replacement
Graham Hicks, project development manager at Polypipe Building Services looks at the challenges of RMI projects in more detail and the possible solutions to help keep them running efficiently
R
MI projects are by their nature, complex challenges. This is certainly true for public sector projects where waste management services such as drainage stacks often
need replacing. This leads to a raft of considerations that must be addressed if the project is to be completed efficiently. Not only does potential disruption to residents need to be a primary concern, but there can also be a host of technical challenges in buildings that have been lived in and adapted over decades. Quite often, using “off-the-shelf” components simply does not offer the most effective solution.
The challenges
Drainage stack replacement is a major piece of remedial work which inevitably means some period of time where residents are without the ability to use their sinks, toilets and other facilities. In multiple occupancy buildings where there are many individual homes, perhaps 100 or more, this can mean a significant level of disruption.
Unfortunately, this is something that the traditional approach of assembling loose stack components on site can make even worse – requiring drainage systems to be out of action for long periods of time whilst installation is completed. This disruption not only meant upheaval for residents, but can mean greater cost for building owners too.
Added to this is that the older a building, the
more likely that what’s actually found on site differs to the original plans – if these plans are even still around. Bathrooms may have been moved or reconfigured, additional appliances may have needed extra drainage. This adds up to a range of challenges unique to each project, and the potential for time-consuming surprises if a traditional approach is taken and they are dealt with as they are encountered. Again, the traditional approach does little to help remove this problem. The use of standard loose parts will not always be suitable for the requirements of an older building that has undergone previous phases of renovation. For example, the proximity or angles of joints needed may not match standard parts and so demand further work to address – using more time on site and potentially impacting on the layout of some rooms.
The solution to these challenges often lies in how projects are planned and how drainage stack components are manufactured to help reduce time needed onsite.
A better solution
A good example of how this approach can reap benefits is the recent refurbishment of a 15 storey tower block in the West Midlands. Existing pipework was showing several signs of failure including splits within the cast and failing seals on the lower ground floor, while tenants had complained of bad smells due to the leaks, often created through waste buildup within the pipework with items such as cooking oils being poured down the sinks. Over 25 years this had built up inside the cast iron leading to the splits and leaks. In this project the installation team had to
remove a wall within the kitchen pantries of properties running all the way up the stack in order to replace the original stack, and as this was a tight and awkward space the stack was supplied in two halves per property to enable the installer to drop it into this existing space. The two pieces allowed for an expansion joint in the middle of the stack making it fully rotatable so the installers can place the access door exactly where needed. Furthermore, some of the flats had been changed from the standard bathroom configuration to wet rooms, meaning basins and toilets had moved to different areas which
28 BUILDING SERVICES & ENVIRONMENTAL ENGINEER OCTOBER 2022
required a change to the seal adapters and some offsite engineered pipework solutions. These included cutting back of the boss as close to the stack as possible (to around 30mm) and also elbows with as little as 94mm from centre line to centre line in some cases which would be difficult to achieve on site. Assessing these requirements up front and
producing engineered designs to address them meant that a bespoke drainage stack could be produced offsite. This helped to avoid a significant amount of time that would otherwise have needed to be spent on-site in cutting standard stack lengths to size and working around the unique layout of the building. The use of HDPE – an exceptionally durable material – for the pipes was key here. Whereas cast iron stack replacements would have meant that branches from the main stack could only have been be accommodated at 90 or 45 degrees, using HDPE meant that angles could be bespoke engineered to accommodate a range of fittings, and proved essential to working effectively in the tight spaces on site. HDPE also offers advantages in how it can be prefabricated, with bespoke configurations – such as two connections almost touching each other – produced using
mirror-welding offsite. Furthermore, 3D Printed jigs can be used to create plastic moulds for cutting aids, allowing closer cuts which both ensures a better quality product and is a safer method than installers managing this on site. With HDPE it’s also easy to futureproof pipework should the contractor need extra fittings for additional connections going forward. This speeds up future installations as spigots with welded-on end caps can be left ready for additional appliances in the future. These can then be simply cut off and a ring seal adapter added to take an additional waste pipe.
A more efficient way of working
The use of a prefabricated HDPE system meant that live stack replacement could be completed at a quick rate, as the majority of work to overcome the unique challenges of the building had already been addressed in the design and manufacturing stage. With most public sector housing RMI projects facing problems of this ilk, planning ahead and working with a supplier who can help to head issues off before installation begins can be a significant benefit.
Read the latest at:
www.bsee.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46
