Having Civil Engineers look at plans before submitting layouts will help you calculate the risk you might be taking in moving forward with planning and construction before completing any surveys or investigations.

You don’t want to discover, after investing in designs and planning permission, that a project is not buildable.

You might assume all projects would have site investigations, site appraisals and feasibility studies completed before money is spent on designs and planning but this can depend on the size of project.

With bigger projects, we do tend to get all the data and investigation results up front at the start of a project. A 30-house development could not go into planning without details such as a site investigation, final architect’s information, and a detailed topographical survey.

When you’re looking at a single unit, or 5-6 units, clients can sometimes go to planning before they have all this information because that size of project doesn’t need to go through a Lead Local Flood Authority (LLFA). Therefore, clients will come to us with an approved design, that hasn’t had any input from an engineer, and we will need to confirm that it can actually be built.

Recently, we picked up a project, with planning, at RIBA Stage 4. You would assume the project was buildable because it had planning, but it had had no engineering input. In this case we had to go back to the start, RIBA Stage 2, and find a solution to the drainage and discharge issue, otherwise we would have to inform the client, at this late stage, that their project is not buildable.

On this site we couldn’t use soakaways (as shown in the approved plans) because of the dissolution features. Our next option was going to watercourses, but we had none in the area that were available to us, so we had to consider a sewer. The only sewers available were foul water sewers, and unfortunately discharging surface water into foul water sewers has recently been outlawed. We entered discussions with Southern Water to see what we could get from them, and that led to a very lengthy back and forth trying to make sure we actually had a discharge point. If we couldn’t get a discharge point, the site would not be able to go ahead.

In the end we couldn’t work with Southern Water, but after taking a step back and consulting with the rest of the SWJ team, we were able to devise a solution that pumped the water up and away into a ditch. The client suffered additional costs for the extended time on site, a pump for the water, and a 6–8-week delay. But, the project was finally able to move forward with this solution.

If this client had consulted us earlier, we could have informed them of the risks of unstructured chalk, as we knew the area well. We would have been able to save them time and money. With a completed site investigation, we may have even been able to steer the architect’s layout to give the site the potential to work with a soakaway, rather than a pump, but by the time we were instructed the project was already installing foundations, and the design was locked in by the planning permission.

The one thing we keep seeing on smaller sites is a lack of information. If nothing else, we recommend you have a quick word with us prior to submission, just to give you an idea of what could go wrong, and what information we foresee you needing. We’ve all got experience – especially in the Winchester area where dissolution features increase the risk of issues – and we can highlight any potential risk early in the process.

Early-stage advice from us will help you cost that risk, so you can make a better-informed decision to investigate in more detail before the designs are locked down or to continue with planning, and risk issues with schedules and costs arising further down the line.

If you’d value some initial civil engineering advice, please give us a call on Witney 01993 225085 or Southampton 02381 920656 or email mail@swjconsulting.co.uk.