About Time!

We’re long overdue for an update and I think I’m finally getting my head above water here. I’m not sure how long it will last but I’ve been so busy over the past 3 weeks that I haven’t even managed to keep a regular dog-walking schedule, much less get on the Interweb.

The long and short of my new job is that I’m working for Atkins. For those that don’t know, Atkins is the largest Engineering practice in the UK and around 11th in the world. So my career has moved from smaller, independently owned, companies to the bigger, publicly traded, multi-disciplinary firms.

Needless to say, things are different! Just to put it in terms of day-to-day, I’m currently sitting on the 27th floor looking south over London. I’m sitting in a group of Engineers / Technicians working on surface water drainage for the Olympics. Traditionally, I would be the only guy discussing drainage in an office. Now, everywhere I turn I’m surrounded by conversations, computer screens and drawings covered in drainage. One of my directors called our area a “swamp”!

Lately I’ve been split between three offices: Epsom in Surrey, Euston in London and Canary Wharf in London. Canary Wharf is an interesting place. The offices are very nice and there’s access from the station all the way to the basement of my building through the massive low-level shopping plaza. I can understand why it’s a prime destination for business. The work in Canary Wharf has been some bits and pieces on Crossrail. When I get my head around storm drainage for Crossrail I’m going to definitely do a post about it.

The most interesting part of working on projects like Crossrail and the Olympics is that I am having difficulty working out who is paying for my work. I know where the money is coming from, but how it gets to Atkins is a mystery to me! This is partly because the work is all mega-urgent so I’ve had to just stick my nose down and get on with it rather than spending (wasting?) time on long introductions to the project. But as things settle down around here I’ve started to pay close attention to the current political discussions about public spending and the future of major infrastructure projects, and I’m not sure how much I like being relevant! Hopefully things will continue on the way they are now, keeping goliath companies like Atkins in good stead and able to employ many thousands of engineers!

More on IDF curves

Hi Folks

Just so you know, I finally dug out that IDF curve from Alabama. Calera, Alabama actually, I get nostalgic just thinking about it.

At my new place of work I have been using Civil 3D a little bit. I was excited to use it as it finishes off my journey of software packages from: LDD > Eagle Point > PDS > Civil 3D. I like to spend a few years on a Civils package before moving on. It’s healthy.

Civil 3D comes equipped with an add-on of Hydraflow for storm sewer design. I haven’t really messed with it yet but I understand I could use it in the UK if I input the IDF curves I came up with below. Although, after comparing the IDF curves below with Alabama’s curve I am wondering if I’ve done this correctly. They seem so extreme in their gradient change!

This brings me to my next piece of news. Civil 3D bought Boss International last fall and I assume they have incorporated Boss’s software into AutoCAD in order to make it the most uber-design package known to man.

A little birdy told me today that Boss will be rolling out a fully functional UK version of their software for drainage design. Could this be the package that gives Microdrainage a run for their money? Up to now we haven’t seen much, so I’m hoping the competition is a little more fierce from Boss. A little competition can go a long way to improving these software packages!

Intensity Duration Frequency for London

Well, I’ve been saying I was going to do it. So I did it. In fact, it is one of the most often reasons someone visits the site. That I mentioned Intensity Duration Frequency (IDF) curves for London in a previous post has generated a lot of site activity for me. So, in return for the traffic I sat down and worked out a first attempt at the graphs.

Using Microdrainage and the Flood Studies Report (FSR) I cut out a lot of the hand work from the Wallingford Procedure (Rational Method). Their generate rainfall looks like this:

Pretty nice, eh? After a laborious bit of data entry and clicking it gives us everything we need to create a nice set of IDF curves.

So here it is, in all its glory, the IDF curve for London, UK in mm/hr:

Or, for you Americans, inches/hr:

Obviously I can take no responsibility for this information, or whatever you might do with it, but it does go a long way to pointing out why they get away with 6 inch pipes everywhere here. I’ve got an old IDF curve for Birmingham, AL somewhere so I might dig it out and do a little comparison. From memory though I believe they’re about 10-12 inches per hour in the 100 year storm. Quite a difference!

Fish need healthcare too

Okay, it’s been a couple of weeks and I have started to settle in at the new company. My impressions I’ll keep to myself for the moment until I can clear all the blogging issues with HR/PR.

I said I was going to run through some of my favourite Curtins projects and I meant to do it. So there is no reason I still can’t update with some of the projects I enjoyed doing most. I would like to run through one of my all time most favourite projects: Marine Scotland, Fisheries Research project. As it is in research and probably fairly protective of its data I will spare you the gritty details and leave you with the Youtube video:

Nice huh? I particularly like the part where they see the pond. That’s my pond! Hopefully it will look like that in reality but I have the sneaking suspicion that it will end up like all the small ponds I’ve ever designed (horrible).

The thing I enjoyed most about this project was that it was in Aberdeen and I got to fly there once a month for about 18 months. And most importantly, I loved the design team. The Architects were some of the best I’ve ever worked with and the whole group of us got on really well. That’s not to say that there wasn’t the odd bit of heated debate (I believe the design team leader once suggested to my director that I be “taken outside and shot”) but in all it was one of the most satisfying projects to work on, both in complexity of design and involvement throughout delivery.

And did I mention the fish and chips you could get at the golf course club house across from site?! I’m not a huge fish eater, but when you’re designing a building to protect fish health you can’t help sitting there thinking about a nice piece of deep-fried ocean dwelling animal. See here a photo of Niren enjoying the dish:

Fish of the North Sea, I enjoyed eating you almost as much as I enjoyed being a part of the delivery of your future healthcare.

Look back: Larden Road

I’m finishing up here and while I’m going through old files and cleaning out drawers I’ve started to wax philosophically about all the projects I’ve worked on over the past five years. My first large scheme and the project I used for my Civils exam was Larden Road.

Larden Road was a £68 million housing scheme with a mix of for sale/affordable residential and commercial units. The project comprised approximately 500 individual residential units spread across a 2.1 hectare site. The small plan area of the site required that the units be situated in high density multi-storey buildings with a central private access road. The site is located within the floodplain of the river Thames.

This resulted in a host of design and feasibility problems. I think this project has a special place in my memory because I was part of the team that not only secured planning for the scheme, but also part of the design and build design team for the contractor who built it. This meant that I wrote a Flood Risk Assessment, carried out preliminary designs for costing, produced construction information and saw the construction through to site.

The site:

The Microdrainage Model:

The basic idea is that the Environment Agency asked us to attenuate to Greenfield rates. This meant we needed a large amount of attenuation in order to achieve the required volume of storage necessary to meet the rates. I designed a system that cascaded permeable paving zones through the site with a single outfall. I even selected recycled material for use beneath the paving.

The recycled material:

And the finished product:

Ch Ch Changes.

Well, it’s been official for 2 weeks now. My time at Curtins is finally at an end. I will be leaving here this Friday and start at the new job on 16th August. I’m not certain what their policy is on employee blogs yet so I won’t name and shame them by associating myself directly. Not yet anyway.

By way of send-off I thought I’d take a look back at some of my favorite projects I’ve completed here. I haven’t done a full count, but by my reckoning I’ve been involved in over 80 different schemes during the last 5 years. I also used my time here to get Chartered. Curtins are tied into my whole British experience. They were the first people we met when we moved here and many of them remain close friends. I’ve spent a fair few great nights and days working and playing with the people here. I am going to miss them!

The 2009 office Christmas Party:

The 2009 drainage team:

There are too many good times to cover in one post. I’m going to try and update throughout the week with some more memories/projects.

Some of the places I’ve done work in include (in no particular order):

Greater London
Weybridge
Pirbright
Birmingham
Nottingham
Rochester
Canterbury
Chelmsford
Southsea
Southend
Norwich
Norfolk (Hopton, Flegg, Hobart, Winterton, Glebeland, Gilingham)
Colchester
Ramsgate
Reading
Luton
Aberdeen
Bristol
Cardiff
Coventry
Grimsby
New Castle

I’m sure the list could continue, but I won’t bore you any longer. I just want to say that working for Curtins has been a pleasure.

Your argument is invalid

I’ve got a nice little job in one of England’s port towns. There are some good Civil Engineering works like ground improvement and roads/drainage. But something happened recently that got my eyebrows lifting. It’s times like these that I worry about the industry.

That’s the site. The short version of this little debacle, if that’s what I’m calling it, is that the future building and its owners would like to flush the toilet. They’d like to flush the toilet in the knowledge that the water will drain away and not end up in the English Channel.

Funny thing about that, the water company had their consultant send me a letter after accepting the application form and roughly £500 to look into the possibility of a future connection. In my letter I asked:

1.) Could we please connect surface water to your storm overflow culvert that crosses the site?
2.) Could we please conect our foul via pump into your combined sewers draining into the pump station?

Here’s the site plan:

Their response was this:

1.) No, please look for an alternative connection location like a local watercourse.
2.) Yes, so long as the flow does not exceed 1 liter per second. Also, please connect to MH 0302.

Now this leaves me in a funny spot. I’m guessing by watercourse they are referring to the *&$£ing English Channel that is obviously adjacent to the site. I mean, if the site location plan didn’t make it obvious then the joker who works for the OS Mapping service should have given it away with the hilarious “Dolphins” note. I can only assume that this refers to some kind of named pier and was not based on observations from the day.

And to make matters worse, 1 liter per second from a pump has got to be the most asinine solution I’ve ever heard of. What sort of tom-foolery resulted in that number? I’m guessing they want us to use some sort of hand-pump to achieve these rates. Either that or we have some kind of operational siphoning regime in which the person who draws the short straw has to go out to the outfall and “get the siphon started…”.

The biggest insult was that they denied my connection to the combined sewage overflow from 0302 and asked that I instead connect my foul to this manhole. Really? You want me to connect my foul drainage into a chamber that drains directly to the English Channel? ARE YOU SURE?!?!

My discussions with the company in question have been drawn out and tiring since their initial nonsense letter. To their credit they have some very intelligent and hard-working engineers that have worked with me to resolve some of the issues we’re having.

Despite our best efforts we’re still not there. Because of this I’ve decided I’m going to use internet Memes to counter argue local water authorities in these situations. Because believe me, if four months of discussions haven’t resulted in a suitable solution then maybe it is time for a change in tactics. Perhaps I would have been better served to have responded in the first instance with this:

Enough said.

The new office

Things have been wild for me lately! By wild I mean relatively boring with the odd bit of unwanted change.

First up, it has been too long since my last update so I’ve decided to get back into the swing of things this week with, “a day in the life” of this Civil Engineer.

To start with, I take you to our new digs. That’s right, Curtins London have moved shop and last Friday we finished packing and today we tried to pick up the pieces. I’m actually impressed at how well it’s gone!

This is our space.  The new office is L shaped with the entrance about mid-way through the long part of the L.  We are in the end of the long part of  the L.  Note the nice open workspaces with teams coming together by spinning around in their chairs.  Brilliant.

You can almost make out our new entrance area.  There appears to be some kind of interference in the frame.  I can only assume that a zoo creature of some sort escaped from Regents Park and made its way to Clerkenwell and into our office.

This is from the corner of the L looking back up the long side of the office.  Our room in the distance.

And finally the Structural Engineer’s space. Note the poorly laid out desks into quads where teams have to stand up ad walk around to discuss project aspects.  They are truly unfortunate in so many ways.

So, they ran my editorial

Last week I sent the NCE an email with a hope they’d print it in the “Your views and opinions” section. Today it hit my desk!

The text is a little annoying to me now as I think I sound like a little pretentious but you have to remember that I was excited about being back from the Gulf and after having such a good time there I was/am devastated by how bad it is now. They closed my beach to swimming. CLOSED!

So, the blurb went something like this:

Recently floods, volcanic eruptions and the Gulf oil hemorrhage have reminded us of our inability to fully control the natural world. I was fortunate to spend some time on Alabama’s Gulf coast last week, and I was able to swim in the ocean days before the oil began drifting ashore. Despite the fact there was a visible sheen on the water, the experience was similar to many I’ve had over the years, the only difference being the realization that it could have been my last for many years to come. Since returning to the UK I am disappointed by the small amount of coverage of the catastrophe by the NCE. The calculation of risk and the interpretation of consequences is first undertaken by civil engineers when trying to determine the impacts of natural events. What do we know about how the engineers calculated risk in the Gulf? What can we learn about the assumptions and how does the industry need to react to the apparent failure in judgment? As engineers are we too reliant on “black boxes”, be they blow-out preventers or the never-failing Thames Barrier, in how we understand risk? These questions are at the heart of the disaster in the Gulf and deserve some effort to comprehend.

I think the Thames Barrier analogy is a little off. It wasn’t really what I was trying to say. I was trying to reference the Ed Wilson comment that I recently posted here.

Essentially, what I wanted to say was that I am more inclined to blame the engineers for the spill. It isn’t the oil execs or Mineral Management Service who set the limit on what is safe, it is the engineers carrying out their risk assessments. And I wholly disagree with any person who says the engineers would alter the scope of their reports to allow for unsafe activity. I think it is more a case of not fully comprehending the consequences while relying too heavily on man-made backup technology.

Or, what Ed Wilson said, “The oil spill is like the economic meltdown, we depend too much on black boxes. The complexity of our society has moved past our ability to comprehend the consequences of our actions, and it would be foolish to blame bad guys, even though they are out there, for situations that are a result of our own daily choices.”

In this case, we the engineers are responsible for the black boxes! And we need to do better!

Margins of error

Recently I received some comments from a local authority stating that my run-off rates for the pre-developed site were not consistent. They stated that although the site was 1.5 hectares I was only developing 0.6 hectares. Therefore, the Greenfield rate should be calculated for the 0.6 and not the 1.5.

Essentially this means that instead of 6 l/s they want me to drain at 2.4 l/s. They went as far as stating this in the report. Rather than argue that peak flows from the hard-standing areas will discharge sooner than the remaining soft landscaping from the site and therefore there will be no increase in peak flows (albeit an increase in volumes will occur) I thought I’d look at some of the error involved in a simple Greenfield run-off calculation to IH 124 (or ICoP if you’re savvy).

It’s silly to do it this way, but I can’t help it. The SAAR maps and soil maps that make-up the inputs to this horrifyingly simple equation are based on the Wallingford Volume 3 maps (1:1,000,000 of Great Britain) and let’s face it, you can’t get an accurate reading off a 1:1,000,000 map!

Here’s the input dialogue in MicroDrainage:

The first thing I tell people to do when working with these maps is to be careful with the soil group they select. For instance, this site is located just north of Canterbury at the convergence of two soil groups. If you click the wrong spot in Microdrainage then you’re liable to get the chalky, high soakage soils common to Kent that yield extremely low run-off rates. Our site has clay soils and steep slopes. Reading the descriptions goes a long way to saving us. For instance, when the calculation was first run the numbers were derived from clicking within the software. No soil descriptions are given and it wasn’t checked against the actual maps. The results are as below:

Soil Type 1: SAAR 700mm = 1.5 l/s
Soil Type 2: SAAR 700mm = 6.8 l/s

Now, imagine if we’d never checked the soil descriptions against our site soils and forced our client to pay for enough attenuation to hit 1.5 l/s! Disaster! Not to mention that with a click of the button you can get over 75% error.

Looking the other way, if we agree it should be soil type 2 then what range of error can you get from reading the standard average annual rainfall wrong?

Soil Type 2: SAAR 700 = 6.8 l/s
Soil Type 2: SAAR 750 = 7.1 l/s

Here again we have about 4% error for a given soil type between readings of SAAR.

But what is the reality of these errors? How do they compare with other methods of calculation? In the past I’ve used IDF curves to calculate runoff based on a modified rational equation. The duration was loosely based on the time of concentration. In this way you’re at least factoring things like slope and travel time into the formula.

However, I’m unable to compare these results because I don’t have an IDF curve for the UK and although I’ve considered making one for London I’m too busy(lazy) to actually sit down and do it.

So let me ask you, internet, do you have an IDF curve for somewhere in the UK? If so, please send it my way!

As for the Council’s comments regarding the flows. I will say this, the comments were sensible and well formulated, but I cannot imagine caring less about a difference of 3.6 l/s between our two results. The real damage being done by the development is the increase in volume of run-off. And don’t get me started on the inaccuracies found when calculating that.