Welcome to Phase 3
So after a nice period of leave (Iceland is a great holiday destination!) I am now in a design office.
I’ve been given two projects to get me started: designing a crossing point for quarry vehicles to get over a high pressure gas pipeline, and designing a drainage solution to a flooded National Grid site. Additionally I’m also getting pulled into a job designing a new facility for the Somalian SF next to Mogadishu airport, not too dissimilar to one I did for our SF in Lash just before it shut. So plenty to get stuck into.
Both of these jobs were sold to me as “nice simple ones to get started with”. Which it turns out is not true for either. The drainage job requires applying for a Section 50 licence to dig up a road and a discharge consent from the environment agency. The design itself is pretty straight forward but the hoops you need to just through are not.
The pipeline crossings job is more of a design headache as what I was told was gravel is in fact clay. Despite three different surveys being conducted, at no point did anyone do an SPT, or lab testing and so no Geo properties, ground water data or test results are available. So the first step is to get a “proper” site investigation done.
Additionally the company I am attached to (WYG – a fairly holistic medium sixed engineering consultancy) do the obvious structural, civil, mechanical and electrical design work, but they also do planning, transport, force protection, international development and aid work to name a few. So the plan seems to be for me to do about four months in the Civils/Structural design dept. (overuse of the work dept. – there are three of us in the London office) then a month in any three other depts. of my choice. I’m thinking International development, Project Management and Adjudication, but I’d be happy to get suggestions!
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Guz,
Glad to hear leave was good. For the benefit of an E&M who may at some point have to get involved in ground conditions can you elaborate on what was wrong the three surveys that have been done to date? Is it a case of boundaries, contaminants, water level and type not being applied or more than that?
The previous surveys that were conducted were looking at agricultural use (therefore mineral make up and topsoil depths), quarrying (therefore amount of gravel and sand that can be extracted, and particle size) and an environmental survey (looking at contaminants – which by the way takes 97 pages to say “its ok”).
So none of them looked at properties of ground water. Not ideal. So I’m sending a bloke out to hit it with a stick!
So am I right in thinking that the initial survey’s weren’t “wrong”, they were just looking at something different?
Yes exactly. Conducting SPT and triaxial tests are costly and so unless the purpose of the survey is to estimate soil properties (everything in soil is an estimation) then they won’t do it.
Are the site surveys you have access to historical then, rather than being for the job or even National Grid? Or were they just what was given when someeone asked for a ‘site survey’ without determining why they wanted it or defining what they wanted?
They’re historical of sort. They’re all fairly recent, but when the client commissioned them they were still trying to work out what they could do with the land for best profit. They thought maybe farming, then quarrying and thus the slightly obscure surveys that have been completed.
Guz, sounds like a good range of projects to keep you going. I am sure there was mention of protection of critical national infrastructure in that infrastructure resilience lecture at the ICE – I wonder if other substations have designs that can be compared/looked at for similarities. Sounds like a fairly topical issue to have to resolve at the moment. I understand that Desmond fell into a greater than a 1 in 100 event so most of the defences were not designed to withstand it, therefore is one of your options to use temporary works to dewater, rather than a permanent solution?
Sounds like the initial GI fell into the trap John spoke about in the first 6-weeks – you need to know what you are building before the investigation. Out of interest how far below the ground surface is the pipeline?
All local planning regs (for Essex at least) require designing for a 1in30 year storm event unless they are connected to basements or someone else’s property in which case a 1in100 event must be considered, all with an additional 30% to allow for climate change. That last bit is a relatively recent addition and it is my understanding that it’s that omission from many older drainage designs that is causing problems in the North. Richard – Any comments?
The gas pipeline to be crossed is between 1.3 and 1.8 m down in (mostly) made ground and organic topsoil. It’s been agricultural for as long as anyone can remember so it’s all pretty loose for at least the top 300mm.