Q&A WITH OUR SITE AGENT, PAUL DUNNE

What initially motivated you towards a career in civil engineering?

Growing up the thought of working in an office doing the same things day in and day out never appealed to me so I wanted something that meant I wouldn’t be in the same location for an extended period of time, I wanted different challenges each day. Since a young age, I’ve always been interested in how buildings, roads and general infrastructure are constructed so this led to me studying Civil Engineering at university and going on to get a career in it when I graduated.

Where is your current position based and can you give me a bit of background about your career history at Mackenzie Construction?

I’ve been with Mackenzie Construction for almost nine years, I started as a site engineer and have progressed up to site agent over this time. I’ve always worked on deep drainage and sewers with the majority of work being undertaken for Scottish Water and Scottish Water Horizons.

I’m currently working in Edinburgh repairing a Brick Built Combined Sewer which has badly deteriorated over the years and caused a sinkhole, this is next to a major gas main that supplies most of Edinburgh so there are a lot of engineering and potential H&S difficulties that we need to overcome to successfully complete this project.

How do you feel that the projects you have worked on with MCL have impacted the communities around them?

Although the majority of the projects we work on cause temporary delays and inconveniences to local residents and/or businesses during the construction phase they all ultimately have a positive impact on local communities which vary from flood prevention works, improving sewer and surface water networks and improving existing roads/pedestrian footpaths.

What do you find is the best part of your day-to-day job?

Overcoming any challenges that arise onsite. Most recently, the project I’m currently working on in Edinburgh. We were employed by Scottish Water to repair a collapsed small diameter sewer which was initially thought to have caused a sinkhole. However, upon further investigation, we found that the large diameter brick built combined sewer next to it was in very poor condition and this was the root cause of the sinkhole. We had an initial design to completely remove the deteriorated brick built combined sewer but after several meetings with SGN and their designers, we were advised by them not to remove this as it could cause movement and ultimately failure of their large diameter gas main which is in very close proximity to it.

As a result, we have had to come up with a solution of fitting a new pipe through the existing brick built combined sewer, due to the awkward shape and difficult access conditions we have had to get specialist pipes fabricated to exact dimensions and angles so they can be lowered down into the existing structure and built in situ. Before any of this can go ahead, we have had to get GPR surveys carried out to locate any voids around the existing structure and the gas main which will need to be filled by injecting a polyacrylate non-expansive grout that will improve the surrounding ground conditions and prevent differential settlement of the ground and the gas main.

What has been your biggest career highlight to date?

Mauldslie Bridge was a challenging and unique project for me. It is a category A listed building that was in a state of disrepair and SW needed this so their tankers could access their WWTW. Due to the poor structural integrity of this, we had to carry out full repairs and structural strengthening works to get this open to SW tankers and the public again.

There were many different parts to this project including, structural repairs, stone masonry repairs, drainage, working over a watercourse with varying water levels so we had to use an overhanging scaffold to repair the underside of the three arches over the Clyde and there were also ecology issues where we had to build bat bricks out of sandstone and fit into the bridge structure so we complied with ecology licenses from Nature Scot. Overcoming these issues and successfully completing the project was a highlight as it involved a lot of thought, problem-solving, planning and management of multiple contractors.