Sewer connection contractors all agree that urban sites are usually the trickiest to work on. In a built-up environment, it’s often more likely that deep excavation will be required in order to connect to a mains sewer, and that there will be restrictions on the space available – both to do the work on the private drains and the sewer main itself, as well as limitations on the above-ground area available for equipment and waste storage.
It’s also more likely that there will be added complexity to any sewerage system works because of the busy road network above – not to mention the paperwork that comes with all the rules and regulations that must be complied with in busy urban areas.
Sewerage system works in towns and cities
The biggest problem when it comes to connecting to a mains sewer in a town or city centre is the close proximity of other buildings. Not only does a highly built-up area mean a complex sewerage system with many different connections from all the different buildings, but often the excavations required to work on sewer mains are very deep. This requires not only the right tools for the job, but a specialist skillset too. A key consideration is that excavation for public sewer connection purposes doesn’t negatively affect other buildings close by – and these could include historic buildings, which need particularly careful treatment in order to preserve their integrity.
The use of timber headings is commonplace where the location of the sewer main means that trench excavation isn’t an option. A tunnel is manually excavated, supported by timber sets along the way, to allow sewer pipes to be laid. This method of trenchless sewer connection dates back hundreds of years, but it can still be the best option where access is limited. We find that it’s a particularly sound choice where the high cost of road closures – such as on London’s Red Routes, which also incur TFL rental scheme daily charges – would make trench digging prohibitive (we’ve got a great case study example, here).
Urban sites are also more likely to involve the technical challenges presented by difficult ground conditions. Not only are ground conditions likely to be mixed, owing to centuries of development, but they may possibly suffer from high groundwater infiltration, requiring ground improvement measures such as dewatering before a sewer connection can be made. Additionally, because built-up areas tend to have a lot of impermeable surfaces, there is usually quite a lot of run-off, which needs to be factored into plans for any groundworks.
Public sewer connections in urban areas: in a tight spot
It’s not just a case of access for digging trenches that is restricted. Even access to the site itself can be tricky. Low bridges or areas that can only be reached through a restricted-height zone (perhaps underneath a skyscraper) bring their own challenges. We’ve even completed a public sewer connection inside a building, which meant that there were very significant restrictions on the equipment we could use, and our site practices had to be carefully tailored to meet the constraints involved.
There’s also usually little space for the storage of equipment and materials in urban centres, too, which can create complexity for sewer connection contractors. The problem of finding space for waste material can be mitigated by scheduling regular grab lorry visits to take it away to a local registered tip – though, of course, some space still needs to be found. We find that local authorities can be open to the idea of suspending some parking bays close to site, in order to make some space available while minimising the length of a road closure.
With buildings almost on top of each other, and each one full of households or businesses, there are a lot of people that could be affected by the works – so it’s important for sewer connection contractors to not only consider the impact of their works on external stakeholders, but where necessary, communicate clearly and respectfully with them too. After all, subcontractors represent the main contractor, and should consider themselves equally responsible for upholding a positive reputation with local workers and residents.
Sewer main works in highways
Sewer connection contractors must also be more aware of traffic issues when working in built-up areas. With heavy traffic volumes in urban zones already, lane closures for groundworks are ideally kept to a minimum. Local authorities in city centres will be particularly keen to minimise the impact of sewerage system works, since gridlock is easily achieved through even the smallest hold-up of traffic flow. Connecting to a mains sewer within the area of a busy arterial roads is certainly one of the biggest challenges, but the location of schools or healthcare facilities might also add complexity, both in terms of the works themselves, and the accompanying paperwork.
At Premier Drainage Solutions we’re able to tackle the trickiest sites, thanks to our wealth of experience in deep excavation, timber headings, and working with restricted access. To find out more about our problem-solving approach to sewer connections in city centres and other urban areas, and for free advice on your sewer connection works, call 01268 950050 or send us an email to [email protected].