Case Study: Tough Sewer Clearance for Thames Water in London SE1

A Lateral Approach from IWJS Achieved a Solution for Thames Water


Thames Water was presented with what seemed to be an insurmountable and potentially extremely expensive sewer clearance problem. However a solution was found to be at hand, courtesy of IWJS, when they took over this new challenge for major client Thames.

The serviceability of the sewer located at Waterloo in London had become severely affected by 8 cubic metres of C40 high strength, heavy construction grade cement. This challenging situation seemed a thorny problem that could have presented enormous civil engineering costs potentially for the client and caused major disruption. Especially as the sewer was located within a highly busy central London urban area, therefore it was difficult to rectify the problem without affecting traffic flows adversely for prolonged periods.

IWJS was therefore tasked by Thames to come up with a more creative, cost effective solution, without resorting to a radical and hugely expensive civil engineering intervention. Following a comprehensive survey of the sewer initially by IWJS, to ascertain the full extent of the problem, a full sewer clean was then scheduled. This would follow after the careful removal of the concrete and silt from the 1.2 metres elliptical profile sewer approximately 160 metres in total length.

The Challenge Ahead

Presented with the task, IWJS examined the problem thoroughly from an open perspective that required lateral thought and ingenuity to arrive at a workable solution. A uniquely creative approach was proposed by IWJS, working collaboratively with civil engineering partners, as this was found to be the best way forward, to achieve a cost effective solution. Thames Water therefore commissioned IWJS to head up and carry out the project.

IWJS acted as the principal contractor working alongside First Intervention Team (F.I.T) and major civil engineering partners Amey and McAllister.

Early planning meetings took place to orchestrate the smooth delivery of the project and minimalise any disruption to the area.  With essential traffic management being arranged to provide a temporary bus stop suspension and pavement closure within 2 metres of the curbside. Due to the busy central urban area, much night working had to be employed to deliver the project with as little impact as possible.

The adopted plan was for the McAllister crews to enter in the upstream manhole outside a public house. There inserting bungs to stop the flow, enabling the Amey mining crew to enter at the downstream manhole to drill out the offending concrete from the line. IWJS positioned a tanker adjacent to the upstream manhole strategically, to control the flows safely around the clock, enabling the work to continue unimpeded for the teams working below in the sewer.

Obstacles to Overcome

However, upon closer inspection the McAllister teams were unable to insert the bungs, due to excessive silt constricting the line.  IWJS then carried out a line clean of approximately 130 metres downstream to remove the silt effectively, thus allowing this essential operation to proceed smoothly as planned.

The McAllister team was then able to enter the manhole to insert the bungs and inflate them. Once these were in position and inflated, the Amey mining team was then able to enter the manhole downstream to commence drilling and secure removal of the concrete. With the rescue team (F.I.T.) on hand for all entries into the manholes to ensure maximum safety at all times.

A Positive Outcome

The safe removal of the highly tough concrete proved to be a laboriously slow process. However, once all of the concrete had been removed from the sewer successfully, IWJS was then able to carry out a full clean and provided a further monitoring survey to ensure the line was completely free. The end result of this challenging project, to restore the compromised sewer back to a free flowing line, was achieved effectively. Thames Water was highly delighted with the outstanding results attained, with minimal cost and disruption to their services and the area.

With the mission being fully accomplished, Thames gratefully acknowledged IWJS for their professionalism and skill in managing such a challenging and difficult project.



Felixstowe to Harwich Tankering Project for McNicholas


Client’s Delight at Smooth, Hitch Free Operation Delivered by IWJS


In 2017 major tankering work was awarded to IWJS from leading client McNicholas. The major contract valued at over £350,000 was for water tankering delivery over a six month period during borehole drilling for the primary client of McNicholas, UK Power Networks. The extensive drilling work between Felixstowe to Harwich, required significant amounts of cooling water at the drill heads, on average 400 cubic metres of tankered water delivered each day, for the duration of the contract.


Challenges Faced

The project required extensive planning and scheduling to provide logistical support for the client as was deemed necessary. The round the clock operation met without any hitches, to the delighted approval of the client. One particular challenge of the project other than the sheer logistics of the operation was the fact that much of the vehicle movements were conducted through urban areas. This therefore required as little hindrance as possible to normal traffic flows within built up urban areas, during the prolonged tankering operation.

Below is a quote from McNicholas Project Manager Phil Williams, to Shaun Leeder at IWJS who was instrumental in winning the work:

“Further to our previous conversations I write to thank you and the great team of IWJS drivers for all of the hard work they have undertaken on the project, needless to say the last 4 months have been challenging as it’s not often you are asked to supply water at 40m3 to 60m3 per hour for prolonged periods of time. We then for period just to make it more interesting started to increase this requirement to 24 hrs a day, however you still never let us down which is a fantastic achievement. It’s no understatement to say that we would not have been able to complete these works without the support of IWJS and the drivers who took ownership of the task.

I am also very pleased to report that for all of the traffic movements through a tight housing estate, in and out of the single road to Shotley, and movements within an operation port at Harwich that I did not receive a single complaint, considering the volume of vehicles and timescale that is a superb effort, well done.

Your contact details are in my phone for the next time!!”


Phil Williams

Project Manager, McNicholas