Newsletter August 2023

While there are more than 5 reasons for why pipes fail across various industries,
here are 5 common reasons why Drainage Pipes fail:

1)  Tree roots intrusions into the drainage network.
2)  Land movement, settlement and subsidence causing displaced joints and collapsed sections of pipes.
3)  Fractures and cracks caused by wear and tear. This can often be corrected by relining, however there will be loss of flow area within the pipe due to the new lining.
4)   Construction activities and excessive loading on existing pipes. This can become more pronounced where there is inadequate cover and pipe protection.
5)   Buildup of encrustations and settlement of sediments, reducing the capacity of the pipe through loss of area.

One of the best ways to establish the condition of a drainage system is to commission a CCTV survey which gives detailed information on the existing drainage system.

Nowadays it is common for CCTV reports to include a plan of the drainage networks accurately overlaid on a topographical survey as an appendix to the CCTV report.

This report can help design teams to accurately plot and plan proposed drainage works, while also providing background information for planning applications.

We at Civilistix have extensive experience using CCTV reports to help identify drainage solutions.

Civilistix Consulting Engineers were appointed to discharge drainage and external hardstanding planning conditions and prepare the detailed private and adoptable civils design.  This included Highway S278/S38 and Drainage S104/S106 technical approval packages.  The project was for a 25-unit residential scheme and associated infrastructure.

We prepared a surface water drainage design which proposed a significant portion of permeable paving for the private external hardstanding areas.  The design included a large geo-cellular tank which together with the permeable paving, provided the required attenuation for the scheme whilst adhering to the Internal Drainage Boards extremely tight discharge rate of 1.1 l/s to their receiving watercourse.

The recently released Design Construction Guidance (DCG) provided greater responsibility on sewerage undertakers to adopt SuDS structures.  With this in mind, we worked closely with Anglian Water to ensure the geo-cellular storage tank would be suitable for full adoption under S104 of the Water Industry Act.

Due to site levels and shallow public sewers within the vicinity of the site, we proposed foul water from the development be collected via carrier pipes, operating via gravity, before discharging to a Type 3 foul water pumping station.  This then connected via a rising main, to an existing foul water sewer.

Further to onsite works, our scope also included for preparation of an offsite S278 design package to widen an existing public highway to accommodate development proposals.

As a Senior Civil Engineer working for Civilistix, I provide civil engineering solutions for exciting and challenging commercial, residential and mixed-use developments.

With over 8 years’ experience working in the United Kingdom and South Africa on design and construction projects, I am pleased to continue gaining invaluable experience with the team at Civilistix.

My key strengths lie in coordinating civil engineering works, namely Highways & Drainage Design, External Works Packages, Earthworks, Utility Coordination and 3D Modelling for Clash Detection.

At Civilistix I interact with a range of clients from large developers down to private clients who are looking to make upgrades to their personal homes. On the backend, I also engage with Local Highway Authorities, Municipalities, Local Flood Authorities and Utility Boards to assist our clients in achieving results that are compliant with industry standards and practises.

When it’s time to kick back and relax, I enjoy Go-Karting, Formula 1, taking part in motorsport, traveling, watching debates, food & wine tasting, gardening and learning about dog-psychology.

I also have an interest in learning about IT, cyber-security and software development, and I practise building small apps as a hobby.

The term “100-year plus 40% climate change event” is a term often used in civil engineering drainage design projects, but what does this actually mean?

In civil engineering, particularly in the design of drainage and sewer systems, engineers often use a design criterion called the “return period” or “recurrence interval” to estimate the likelihood of extreme events such as heavy rainfall and floods. The return period represents the average time between events of a certain magnitude occurring or being exceeded.

The term “100-year event” is commonly used to refer to a rainfall event that has a 1% chance of occurring or being exceeded in any given year.  Similarly, a “40% climate change event” suggests that the magnitude or intensity of the rainfall event is expected to increase by 40% due to climate change impacts.

Therefore, a “100-year plus 40% climate change event” would indicate a rainfall event which has a 1% chance of happening in any given year, while also considering an additional 40% increase in rainfall intensity due to projected climate change effects. This design criterion ensures that drainage systems are adequately sized to handle extreme rainfall and prevent flooding under these conditions.