Imran Khan of Black and Veatch talks about modeling collection systems and InfoWorks


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Imran, where do you fit into the Black and Veatch organization?

Black & Veatch is a leading global engineering, consulting and construction company, and has around 3,500 staff working in the area of water and wastewater around the world. I'm a consultant in the Infrastructure Planning Department with special responsibility for collection systems modeling. My role is to provide specialist advice to all our offices in North America on the best approach to proposing and undertaking collection systems modeling and wastewater Master Plans.


My background is more than 16 years of hydraulic modeling experience on both sides of the Atlantic, both in the UK and the US. During that time I've used all the major commercially available software suites, and seen the evolution of both hydraulic modeling and its software. I bring this experience to relevant Black and Veatch hydraulics contracts to provide our clients with the approach that best suits their need.

You mentioned the evolution of modeling software over recent years – how would you characterize the changes?

If you compare the modeling software of seven or eight years ago with the best of today's software the key differences are:

• There are now dynamic (unsteady-state) models available, rather than only static (steady-state) models. In terms of modeling to analyze peaks dynamic models are far more accurate. There are many reasons for this, but simplistically speaking, they move away from the assumption that all peaks in the collection system occur at exactly the same time and can simply be added together to get the total picture. In reality peaks in various parts of the system occur out of phase and the system total is less than the sum of the component peaks. This ultimately translates to more cost-effective Capital Improvement Plans (CIPs).

• Links to other systems are very important – GIS clearly, but also other inputs such as digital terrain maps, digital rainfall data, and output routines.

• Ease of use is subjective, but in my opinion has improved considerably, so that the best of today's software is intuitive, making it easy to get started, although that is not true of all dynamic modeling software on the market.

All these developments offer really valuable benefits to the user, giving both greater accuracy and better value for money from hydraulic modeling.

How do you choose which software to propose for a project?

Black & Veatch have wide and extensive experience in many dynamic modeling packages. If our client has a preference for a particular suite, that is what we will use. However, we may be asked to provide an evaluation of different software packages against criteria defined specifically for particular relevance to the goals of our client. We have expertise across all the major commercially available modeling solutions, and we happily use them all.

However, having spent my entire professional career in hydraulics, hydrology, and hydraulic modeling, I naturally have a preference. My preference for large and medium sized projects is to use InfoWorks. On small projects there are occasions when it may not be cost effective or our client's goals do not align themselves with the InfoWorks software, so other solutions come into the picture. But InfoWorks is my preferred option in most cases. Demand for InfoWorks and our experience in its use and application is increasing in the US.

What are the attributes of InfoWorks that lead you to this preference?

I've already listed the key developments – dynamic models, good interfaces, especially to GIS, and ease of use. InfoWorks is foremost in all of these.

I also like the fact that it is based on the way in which I feel wastewater flows are generated in reality – which types of data are used, and how they are used. For example, diurnal profiles are important in any dynamic hydraulic model. These can be generated easily in InfoWorks via population and a per capita water consumption rate. The software is fundamentally very sound for engineers to use as a trustworthy basis for decision-making.

Another key factor for any business is high productivity of the software. We can bid for projects at a very competitive price without sacrificing quality, so our clients benefit. An example of this is customizable reporting. Dynamic models have hundreds of data items available, only a few of which may be required for reporting purposes. With most software, a report is defined by checking each data element to be included in the output report. InfoWorks operates by removing data elements from a list – this is quicker and easier. The automatic upstream and downstream traces are also a simple functionality, but save a large amount of time, especially when analyzing model results. The software is also able to grow with the expertise of the user. A novice user can cut and paste data directly from spreadsheets. A more experienced user may want to use the data import center, or a SQL query to update data. Just a small example among many of the well thought out customizability of InfoWorks – many people do not realize the benefits of the full range of functionality available.

InfoWorks is not the lowest cost software on the market. However, the highest cost of a Master Plan is in the Capital Improvement Plan (CIP) which can run into several millions. The CIP is defined and refined in the final phase of a Master Plan. InfoWorks automates much of the model development, allowing more time for results analysis and CIP definition. More time available for CIP definition can lead to large cost savings in the final CIP recommendation. Therefore, InfoWorks as an analytical tool to help derive the most cost-effective CIP, and with its high productivity comes out very well in total project costings.

Finally, when we evaluate software we look also at the software support available for our clients after the completed model is delivered to them, the track record of the company, and the number of central programmers and other development staff required to keep the product leading the industry. Wallingford Software, with excellent product support and a very large development team, meets all these criteria.

You've explained why InfoWorks is useful for carrying out the study. What happens at the end of a study?

This is a moot point. When the consultancy has completed their report and made their recommendations, the model is available for future use. So who should do that work? Some say it should be handed over to the client to own and work with, and the consultant's job is over. Others say that clients can never really understand a model fully and use it accurately, and all modeling should be undertaken by consultants.

I take a middle path on this. Building models and calibrating models is as much an art as a science. It takes many years to acquire the expertise to know when something is not right. Black & Veatch's Infrastructure Planning Department has this expertise. Also, a good calibrated model is highly dependent on the tasks undertaken prior to model calibration. For example, analyzing the base flow and inflow and infiltration (I&I) from rainfall data and flow meters is demanding, and we have developed a proven method and automated tools for doing this. So there is no doubt that a highly experienced consultant, working every day with the wide range of modeling issues can avoid a number of mistakes during the model development and calibration process.

After that, the client can take ownership of the model. We facilitate this by documenting our work carefully, specifying what was done, why, and how, which includes documenting the model, the data used, and the quality of all the model inputs. The client can then use the model to support their decision making into the future, simulating various rainfall and population scenarios and making minor changes to the model as the collection system is improved. But in my view significant changes to the model that require re-calibration – and it requires experience to know which collection system changes are at that level – need to involve the consultants again.

Clearly, the extent to which the client can take ownership of the model and use it confidently is partly determined by how easy it is to use the model – and that takes us back to InfoWorks. It is a very good platform for this vital process of handover, which involves not just the physical transfer from consultant to client but also as much knowledge transfer as possible.

Finally Imran, what are your views on the next few years of modeling?

I worked with the regulatory initiatives in the UK over a number of years, the Asset Management Planning (AMP) rounds designed to point utilities towards more formal planning of their wastewater systems. I see similar regulatory initiatives in the US. The Capacity, Management, Operations, and Maintenance (CMOM) regulations address sanitary sewer overflows (SSOs), and the 9 Minimum Controls - 9 criteria required to meet the technology-based requirements of the Clean Water Act - address combined sewer overflows (CSOs). One of the effects of AMP in the UK was to underline the importance of collection system modeling for making informed, cost-effective decisions on collection system infrastructure. I believe these regulatory frameworks in the US will have the same effect. Modeling will become more prevalent and more important, and InfoWorks will be my recommended platform in most circumstances.


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