The definition of a combined sewer overflow (CSO), from Water Environment Federation Manual of Practice FD-17: Prevention and Control of Sewer System Overflows is: “A CSO is the intentional or unintentional discharge of untreated sanitary wastewater mixed with stormwater runoff or snow melt and occurs when the carrying capacity of a single conveyance system is exceeded by the instantaneous rate of flow within the single conveyance system. To control where overflows occur, engineers design diversion structures at strategic locations within the single conveyance system that ultimately discharge extraneous commingled flow to receiving waters.”

The US Environmental Protection Agency (EPA) has developed a national framework in the United States for control of CSOs called the ‘Combined Sewer Overflow Control Policy’. The Policy was developed through the National Pollutant Discharge Elimination System (NPDES) permitting program, which requires that all point sources discharging pollutants to surface waters must have a permit. The CSO Control Policy provides information on how to meet the pollution control goals of the Clean Water Act flexibly and cost-effectively. The Policy, published in 1994, contains four fundamental principles to ensure that CSO controls are cost-effective and meet local environmental objectives:

• Clear levels of control to meet health and environmental objectives
• Flexibility to consider the site-specific nature of CSOs and find the most cost-effective way to control them
• Phased implementation of CSO controls to accommodate a community’s financial capability
• Review and revision of water quality standards during the development of CSO control plans to reflect the site-specific wet weather impacts of CSOs3.

As part of the CSO Control Policy, all communities with combined sewer systems were required to implement ‘nine minimum controls’ by January 1, 1997. These controls are measures that can be implemented to reduce the effect of CSOs without large engineering studies. The ‘nine minimum controls’ are summarized below:

• Proper operation and regular maintenance programs for the sewer system and the CSOs
• Maximum use of the collection system for storage
• Review and modification of pre-treatment requirements to assure CSO impacts are minimized
• Maximization of flow to the publicly owned treatment works for treatment
• Prohibition of CSOs during dry weather
• Control of solid and floatable materials in CSOs
• Pollution prevention
• Public notification to ensure that the public receives adequate notification of CSO occurrences and CSO impacts.

So it’s not surprising that one of the biggest uses that we see for FlowWorks is clients who are looking for cost-effective monitoring and reporting of CSO’s. The equipment to do this is now WAY cheaper than it used to be, so much so that it’s now possible to instrument overflow manholes or chambers with battery powered, underground wireless level equipment for about the same price that just the basic programmable logic controller (PLC) would cost in a traditional SCADA system. As a result, putting monitors in every overflow location is now within striking distance of cities that have even modest funding available. We are seeing clients instrument their overflow points with ultrasonic level sensors, pressure transducers, and even good old-fashioned float switches. There are even some amazing load-rated all-in-one monitoring manhole lids available on the market!

Once you have those locations instrumented, watching near-realtime data coming into FlowWorks is where the real fun begins. When all is well, you see all of the locations as green symbols on the FlowWorks map. When levels are nearing critical values the symbols switch to orange, and finally to red as the event begins. At several stages before and during the event, FlowWorks will issue alarm emails and text messages to everyone that needs to know. At anytime during or after the event, the FlowWorks graphing and reporting functions can tell you how long the event was. Plus, if the station is setup correctly you can get an estimate of how much overflow volume has been spilled.

It’s even possible for us to customize the reporting functions to match the exact format and requirements of your regulatory agency. After the events are over, a few mouse clicks is all it takes to produce the CSO overflow duration and volume reports to meet your regulatory obligations.

Check us out for live, online demonstrations of our powerful suite of online data collection, monitoring, and analysis and reporting tools.  You’ll discover all the benefits of the FlowWorks online system:

• it’s Flexible
• its Affordable
• its Hardware Neutral
• its Hassle-Free

Come and find out how FlowWorks’ powerful analysis and graphing tools (including Inflow and Infiltration, combined sewer overflow (CSO) reporting,  IDF and statistics) truly make it the best way to ‘Know Your Data’ – be it rainfall, CSO, water quality, sanitary/stormwater, or hydrometric.

COME BY AND VISIT US AT BOOTH #3!  (see the red circle below)

And please contact us if you would like a more information on the show.  Call 1.888.400.3288 or use the contact form.

Craig

Come by and see us at the Tacoma Dome May 12 and 13 to learn about FlowWorks – a powerful suite of online data collection, monitoring, analysis and reporting tools.

FlowWorks allows authorized municipal users to efficiently manage monitoring systems through a customizable web interface.  It consolidates data from remote loggers into real-time flow analysis and reports – available through any web browser.  And FlowWorks significantly improves the ability to collect and transform remote data into actionable insights including easy to understand charts and graphs.

The annual spring conference is the premier technical training event for water industry professionals throughout the Pacific Northwest, and FlowWorks is proud to be a part it.

Our booth is sure to be a highlight.  You’ll learn all you have to gain by using our tools:

• Flexibility
• Affordability
• Hardware Neutral
• Hassle Free

Come and see how FlowWorks can improve your remote data collection at Booth 503 on the main floor.

For more information and to sign up for the show, please visit PNWS – AWWA.

For more information on Emerald FlowWorks, including a FlowWorks brochure, please call 1.888.400.3288 or visit www.flowworks.com.

Timothy Hicks
FlowWorks Inc.
Seattle, Washington
206.859.6999

Check us out for live, online demonstrations of our powerful suite of online data collection, monitoring, analysis and reporting tools. You’ll discover all the benefits of the FlowWorks online system:

• it’s Flexible
• its Affordable
• its Hardware Neutral
• its Hassle-Free

Come and find out how FlowWorks’ powerful analysis and graphing tools (including Inflow and Infiltration, combined sewer overflow (CSO) reporting, IDF and statistics) truly make it the best way to ‘Know Your Data’ – be it rainfall, cso, water quality, sanitary/stormwater, or streamflow.

As usual, the technical program has many informative papers that are being presented, including a project that required significant use of FlowWorks to collect and analyze data.

We highly recommend attending the following presentations that showcase projects that have used FlowWorks:

Keeping the Athletes Warm with Sewer Heat – How Did the System Perform?

Presenting Author: Sarah Southwell, P.Eng.,

Process Specialist., Kerr Wood Leidal Associates Ltd (http://www.kwl.ca/) .,Burnaby, BC

According to Sarah:

“FlowWorks was an essential tool used during the commissioning and optimization of the Whistler District Energy System (DES). Originally FlowWorks was used to record key commissioning data as the tie-in to the main WWTP data recording SCADA was not complete.

Once the district energy system was running, FlowWorks was used to remotely monitor the performance of the DES and alarm the design team members of any operating abnormalities or critical issues. As the design team was able to access the PLC remotely, alarm troubleshooting and system optimization could be undertaken off site, which resulted in significant cost savings to our client and a faster response time. The ability for the design team to continuously monitor the system remotely using FlowWorks also provided an added level of confidence to the operations staff during the system handover period and the 2010 Winter Olympic Games.”

COME BY AND VISIT US AT BOOTH #831! – Click here to see the trade show floor layout

And please contact us if you would like a more information on the show. Call 1.888.400.3288 or use the contact form.

Craig

38th Annual BCWWA Annual Conference & Trade Show (view blog post)
May 1st – 5th, 2010
Whistler Conference Centre, Whistler, BC
http://www.bcwwa.org/annual_conference/2010/home.php

CANECT 2010 (view blog post)
May 4 – 5, 2010
International Centre, Mississauga, Ontario
www.canect.net

AWWA-PNWS (view blog post)
May 12-14, 2010
Tacoma Convention Cente, Tacoma, Washington
http://www.pnws-awwa.org/SectionIndex.asp?SectionID=60

63rd CWRA National Conference
June 15 – 18, 2010
The Hyatt Regency Hotel, Vancouver, BC
http://www.cwra.org/News_Events/National_Conference_2010/Default.aspx

WEF Collection Systems 2010
Conference: June 13 – 16, 2010
Phoenix Convention Center, Phoenix, Arizona
http://www.wef.org/collectionsystems/

Western Canada Water Annual Conference
September 21 – 24, 2010
Telus Convention Centre, Calgary, AB
http://www.wcwwa.ca/rakbase/events/displayEvent.php/31

WEFTEC 2010
October 2-6, 2010
New Orleans Morial Convention Center, New Orleans, Louisiana
http://www.weftec.org/home.htm

Check us out for live, online demonstrations of our powerful suite of online data collection, monitoring, and analysis and reporting tools.  You’ll discover all the benefits of the FlowWorks data service:

• Flexible
• Affordable
• Hardware Neutral
• Hassle-Free

Come and find out how FlowWorks’ powerful analysis and graphing tools (including I&I, IDF and statistics) truly make it the best way to ‘Know Your Data’ – be it rainfall, streamflow, water quality or sanitary/stormwater.

This year we will be sharing a booth with our friends at Flowmetrix. If you don’t know them, they are a technically savvy engineering support and calibration firm located in Southern Ontario (offices in Frankford and Dorchester).  If you are located in Ontario, you should definitely check them out for your flow servicing needs.

CANECT, billed as “the foremost event for Canadian environmental managers, plant personnel, government policy-makers, lawyers and consultants with responsibilities for environmental affairs”, has been drawing environmental professionals together since 1992.

This year’s show is expected to attract some 2,000 attendees responsible for environmental engineering, regulations and compliance issues.  With over 40 presentations and 10 scheduled workshop sessions, it’s a must do for industry professionals.

In addition, the show will be co-located with Partners In Prevention: Ontario’s Health and Safety Conference and Tradeshow, an annual tradeshow of the Industrial Accident Prevention Association (IAPA), expected to attract an additional 6,000 delegates.

COME BY AND VISIT US AT BOOTH #1610!  Click here for the floor plan.

And please contact us if you would like a free pass to the show.  Call toll free, 1-888-400-3288 or use the contact form.

Timothy Hicks
FlowWorks, Inc.
Seattle Washington
(206) 859-6999

Did you know that you can connect your existing SCADA system to FlowWorks? Why would you want to do this? The first reaction that many people have is “we already have a SCADA system, why would we want to use FlowWorks?” Because FlowWorks is not just for dataloggers, and it does a lot more than just store and plot data. Think of some of the things you could be doing with your SCADA data if you used FlowWorks to do it…

If you are in the municipal business, odds are that you have a SCADA system. You probably also have some dataloggers and maybe some sewer flow meters. Wouldn’t it be nice to put all of that data into one place? Do you want to easily plot flow data from your treatment plant SCADA with rainfall data collected by your dataloggers? How about adding some laboratory measurement results along side? If you use FlowWorks, you can do this.

Plus, if you want, the data flow can go BACKWARDS from FlowWorks to your SCADA! What if you use FlowWorks to collect rainfall from some rain gauge dataloggers, but your SCADA also collects rainfall data? The two can give data to each other, so you and your users see the complete dataset! Core staff who use SCADA see valuable information, using the interface that they are used to. At the same time, data from SCADA (which is often difficult to distribute to users outside of the SCADA system) is made available to a larger set of users. No more having to deal with different data formats because some of your data came from the SCADA, some came datalogger brand X and yet other info came from Brand Y.

Setup Personal Alarms

Use the FlowWorks alarming system to setup notifications for other purposes that aren’t mission critical SCADA alarms…maybe you need to know when flows at a treatment plant reach a certain point so you can take a sample…or it’s time to photograph potential flooding at a drainage location…or maybe you want to know the next time a chlorine analyzer shows a low value so that you can go and take a sample to verify it. These are all things that you can do but might not have SCADA alarms setup for…with FlowWorks you can create your OWN notifications without requiring your SCADA staff to setup these alarms for you.

Your OWN Notifications

Yes, that’s what I said – this is a big deal.  In FlowWorks, each user can customize their alarms and notifications, independent of anyone else.  This can help you do your job more efficiently, the way you want to do it, and without extra corporate overhead that is so often required.

Custom Reporting

Use the reporting functions to produce tables for your reports…total water consumption, water quality reporting, rainfall summaries and statistics, pump run times, chemical injection summaries…if your SCADA system has been measuring it there is something that FlowWorks can do to make it more useful to you. Why record it if you can’t use it for anything?

SCADA Data Security and FlowWorks

FlowWorks provides data viewing and analysis tools only.  There are no control functions that would be in a typical SCADA setup.  This means that when you are viewing data sent to FlowWorks from your SCADA system, it is a mirrored COPY of the data rather than the original data itself.  In this way the finite control details of your system are protected from the user, leaving your system and network ultimately secure.

Do you have information that you want to distribute to a larger group of users, but due to security concerns over your SCADA system you can’t do it? If your SCADA system is connected to FlowWorks then you get the best of both worlds…your SCADA system stays locked behind your corporate security, but the data that you want to distribute to others is made available. FlowWorks CANNOT be used to alter data or access your SCADA system and controls in any way.

In the meantime, you and other FlowWorks users within your organization enjoy simple, unlimited access to the information you need, from anywhere with an internet connection. Even if the only thing you use your SCADA system for is to graph data, I guarantee you that FlowWorks will do a better job than your SCADA graphing engine.

I have been doing QA/QC on hydrometric data for many years, and as part of my job I ensure that data being collected is as accurate as possible.  This extends to the instruments collecting the data – today I’m going to talk about troubleshooting a tipping bucket rain gauge, and some of the tools I use within FlowWorks to do so.

If you use a tipping bucket rain gauge you may notice that from time to time the funnel can become clogged with dirt, mud, leaves and other forms of debris.  Clearly a plugged rain gauge will not collect accurate rainfall or precipitation data!

The key is to be able to quickly identify a plugged rain gauge so it can be cleaned out without delay.  There are two ways to do this – accessing your online data (like you could if you are a subscriber to FlowWorks), or manually checking the unit in the field.  I’m going to review both of these options in this article.

Identifying A Plugged Rain Gauge Through Data Analysis

Identifying a plugged rain gauge can be easy when you know what to look for and if you have access to right analysis tools.  If you are lucky enough to be receiving live data, you will be able to identify a plugged rain gauge as often as you check the data.  Historical data is ok too because you will at least be able to identify data sets where the rain gauge was plugged and make sure to disregard that data during further analysis.

A Completely Plugged Rain Gauge

You can tell a rain gauge is completely plugged when there is no rainfall data being recorded when you clearly know that is raining. So if you are looking outside your window and its pouring rain and your live rain gauge isn’t showing any rainfall data, it is probably safe to assume that it’s plugged.  Or if you can compare the data to another rain gauge in the same area they should show similar rainfall.

In the figure below, the data from two rain gauges located in close proximity are graphed using the FlowWorks graphing tool.  The two rain gauges should show similar rainfall but during January 2, 2010, the top rain gauge basically became completely plugged.

Partially Plugged Rain Gauge

Sometimes a rain gauge is only partially plugged.  If this is what has occurred then you would see ‘weird’ rainfall patterns.  That is because during rainfall the gauge will start to fill with water and then the water will start to slowly trickle trough which looks like constant low rainfall and it will tend to continue long after the rainfall has stopped.

In the figure below, the data from two rain gauges located in close proximity are graphed using the FlowWorks graphing tool.  The two rain gauges should show similar rainfall but during the last week of August 2008 the bottom rain gauge became partially plugged.  The constant slow filtering of the rainfall is quite obvious and this is a common indicator that the rain gauge is plugged.

Identifying A Plugged Rain Gauge Through Inspection

The other way to check if a rain gauge is plugged is by pulling it apart on a site visit.  You will either see the funnel clearly plugged or the collection cylinder may be full of water and not draining.  Remove the cylinder to drain the water and make sure the funnel is completely clear of debris.  If the cylinder is not full of water but you still have suspicion that it is plugged, you can pour some water slowly into the cylinder and if the water does not drain or drains very slowly then there may be a partial plug.

Here in the Pacific Northwest it has been raining almost everyday this month. The rain gauge station closest to my house has recorded over 550 mm (22 inches) for November, which is considerably above average.

We have had several storms during this period, but very little flooding issues. My neighbour and I were talking last week after one of the storms and he commented how much it rained the previous night (the local rain gauge measured 27 mm). I agreed with him that it did seem like a good one, but later that afternoon I did a quick analysis using FlowWorks’ Intensity- Duration- Frequency Analysis tool and it turned out that the storm wasn’t “significant”.

So, what constitutes a significant rainfall event and how did I used the IDF analysis tool to quickly determine the severity of the storm?

The basics: What is an IDF Curve?

Here’s the simple answer: An IDF curve tells you how rare a given rain storm is.  Take that storm I looked up from the other night.  It is intuitive to understand the idea of how many mm or inches of rain falls.  It’s not quite as easy to say how often that storm might occur?  Every 1 year? 2 years?  Maybe it was a 1-in-10 year event? An IDF curves helps to quantify that, so you can actually say to your neighbour over the fence, yeah, it seemed like a lot of rain but really we get a storm or two like that every November.

I’ve oversimplified it, but that’s ok.  Read on for a more detailed explanation.

The Official Definition of an IDF Curve

An Intensity-Duration-Frequency curve (IDF Curve)  is a graphical representation of the probability that a given average rainfall intensity will occur (yeah, what a mouthfull!)

Rainfall Intensity (mm/hr), Rainfall Duration (how many hours it rained at that intensity) and Rainfall Frequency (how often that rain storm repeats itself) are the parameters that make up the axes of the graph of IDF curve. An IDF curve is created with long term rainfall records collected at a rainfall monitoring station. I’ll get into the details of how a to create an IDF curve and how much data you need in a future post, but needless to say, you need a lot of data. And the more data you have, the more accurate your curve will be.

How to Interpret an IDF Curve

Rainfall intensity in the IDF Curve is the average rainfall depth that falls per specific time duration. Simplified, high rainfall intensity indicates that it’s raining really hard and low intensity that it’s raining lightly. Typically the rainfall intensity is stated in mm/hr in Canada and in inches/hour in the United States.

Take a look at the graph above. The y-axis shown the rainfall Intensity in mm/hr, and the x-axis shows the rainfall Duration.  There’s the I and D” in the IDF.

The nearly parallel lines on the IDF Curve represent probability, or Frequency (yes, the “F” in the IDF).  So the 10-year line would represent rainfall events that have a probability of occurring once every 10 years. Another way to put it is that the probability of a 10-year magnitude storm (or greater) occurring in any given year is 1/10 or 10%, and of a 50-year storm occurring 1/50 or 2%. I should note that the information presented in the graph is based on statistical analysis of past data, rather than a prediction of actual storms.

Each plotted line in the graph represents rainfall events with the same probability of occurrence, in a range of durations (durations are shown on the x-axis). A 10-year storm can therefore be of any duration – a 10-year 30-min storm, a 10-year 2-hour storm or a 10-year 12-hour storm.

Finally, the last line on the curve is the actual rainfall event, based on the data collected from the local rain gauge.  In this case it falls below all the parallel lines.  Where (and if) the line crosses any of the parallel probability lines, would represent the actual Intensity, Duration, and Frequency of the storm.

Where Can you Find an IDF Curve?

IDF curves are available for many locations in Canada, produced by the Environment Canada’s Meteorological Service of Canada (formerly Atmospheric Environment Service). They are updated periodically, many as recently as 2005, and are available for free download from their FTP site.

A different system of illustrating rainfall statistics exists in the United States. Areas of same statistical rainfall depths are mapped for specific return periods and storm durations. There iso-hyetal maps are called TP40s (Technical Paper No. 40) and can be found for free download on the US National Weather Service. These links are great starting points for understanding rainfall behaviour in different areas of the US or Canada. Local or specialized agencies may have their own rainfall statistics that more closely emulate local conditions and experience, or particular uses for the rainfall information. Examples of these agencies include state/provincial transportation departments, municipalities, environmental protection agencies, etc.

FlowWorks and IDF Curves

FlowWorks can provide you with a quick severity analysis for a storm event.

Did the rain that fell yesterday meet or exceed the 10-year storm? Do you need to report to your City Council the possible reasons why flooding occurred during today’s big storm event? FlowWorks has a tool that can easily answer those questions. By linking your rainfall station to FlowWorks and using our Rainfall Analysis Tool you can plot the storm event as it occurs on the station’s IDF Curve in a matter of seconds. Many of you have likely gone through this exercise using a spreadsheet and found it to be cumbersome and time consuming. The analysis can be redone instantly as new data appears in the database. I have many clients who will “watch” a storm event as it rolls in from the comfort of their desk and send out their operations crews as a storm event hits a certain severity rating to areas where they know that may have issues.

The analysis can also be easily done on all the historical data in your database. The example graph below shows that rainfall that fell near the District of North Vancouver’s rain gauge August 13, 2009 exceeded the 1 in 10-year event for short duration storms (5-15 minutes) and exceeded the 2-year event for a 2-hour storm.

If you’re interested sign up for a free online demo where we can take you through the process of integrating your existing data and climate stations into the FlowWorks system.   Want to know more? Stay tuned for my upcoming articles on “How to Create an IDF curve”, and “What are the other uses for IDF Curves”.

I am a practising Professional Egineer who does A LOT of data collection applications, both for my clients as well as for the 150 or so employee needs within my own firm. When someone asks me what kind of data logger they should use, I always start by asking them where the data logger will be located, and what it will be used for. There are plenty of choices! Here’s a few of the systems and applications that are currently connected to FlowWorks.

Telog

We have some small water and sewer treatment plants that talk to FlowWorks using Telog’s wireless 1XRTT modem. We like the Telog products (particularly the 3307 and 3314), as these units are very reliable and they have some very flexible telemetry options (including dialup phone, wireless, and direct Ethernet connections).

ISCO

ISCO 2150 area-velocity meters in sanitary sewers come in via ISCO’s wireless 1XRTT system. The ISCO’s are purpose-built and hence not as flexible as the Telog wireless system, but the ISCO’s are compact units that generally get the job done well enough.

Marsh McBirney

There are a few Marsh McBirney FloDar’s connected to FlowWorks. These units were plugged into the Telog RU33 product, which acts as a data recording and telemetry module for the FloDar.

ADS

There is an ADS FlowShark connected to FlowWorks. We don’t have a lot of experience with these yet, but our client out East seems to be happy enough with the unit. It uses wireless 1XRTT just like the Telog and ISCO systems.

Satellite Stations

We have remote stations that use satellite because there is no other option where these sites are located. Right now we have Campbell Scientific and Unidata Neon systems connected. We know that Campbell Scientific systems have been around for a long time and have a proven track record. The Neons also seem to be holding up well.

The bottom line is that there are several ways you can do any particular data collection application. We are always doing new applications, and we keep on top of what’s out there on the market, what works well and what doesn’t. Feel free to ask us for a bit of advice the next time you are looking to do a new data collection application!  We work with an expanding list of logger manufacturers, and we provide unbiased advice.