Featured Video: Use of Davidson Pie

What's a holiday season without a little pie? The Davidson Pie might not be very tasty, but it can help you work math problems assisting with chemical addition and process control at both water and wastewater utilities. This 3-minute video explains the construction of the pie and works an example problem using it.

For more water and wastewater math help, search our document database using the "Certification/Exam Prep" category filter and the word "math" (without the quote marks) in the keyword filter.

Common Treatment Deficiencies

This article was first published in the Summer 2012 issue of Spigot News, the Ohio EPA's drinking water program newsletter. Many thanks for allowing us to republish it! You may also be interested in the article Common Source Water Deficiencies.

Ohio EPA conducts sanitary surveys at least once every three years at community public water systems (PWS) and once every five years at non-community PWSs. The purpose of a sanitary survey is to evaluate and document the capability of a water system’s source, treatment, storage, distribution, operation and maintenance, and management. Each of these may favorably or adversely impact the ability of the system to reliably produce and distribute water that meets drinking water standards. 

This article is the second installment in a series of articles to help small water systems identify the most common problems found during a sanitary survey or other investigatory site visit conducted by Ohio EPA staff. The first article focused on source water (well) deficiencies. This article will focus on some of the more common treatment equipment deficiencies which are found during inspections of small water systems.  Future articles in this series will cover distribution deficiencies and other topics. 

Backwash discharge lines: If you have a softener or a pressure filter, you backwash your equipment to clean and replenish the media. The waste that is produced when you backwash discharges into a floor drain or another pipe, which carries the waste to where it will be treated.  If the pipe carrying the backwash wastewater from your treatment equipment is too close to, or even inserted into, the drain or pipe that carries the waste to treatment (see Figure 1), you could end up with back-siphonage.

This could occur if the pipe carrying the waste to treatment backs up and the wastewater is siphoned back into your drinking water treatment equipment, contaminating your treatment equipment with whatever waste the pipe is carrying. Solution: Ensure there is a sufficient air gap between the backwash waste pipe and the floor drain or the pipe conveying the waste to treatment to prevent backsiphonage (see Figure 2). 

Softener tanks, cover, and salt: Softener brine tanks should be kept in sanitary condition. The brine solution should be kept free of dirt and insects. Solution: The best way to accomplish this is to completely cover the brine tanks with an appropriately fitting lid. The lid should not be over- or under-sized and should be kept in place on top of the tank. Also, the brine tank should not be overfilled such that the lid does not fit snug on the tank (see Figure 3).

All substances, including salt, added to the drinking water in a public water system must conform to standards of the “American National Standards Institute/National Sanitation Foundation” (ANSI/NSF).  This is to ensure it is a quality product that will not introduce contaminants into the drinking water. Solution: Ensure the ANSI or NSF symbol can be located on the bags of salt you use or ensure your salt supplier can provide you with documentation from the salt manufacturer that it is ANSI or NSF certified. 

Cartridge filters: Over time, cartridge filters will become clogged with iron or other minerals from your source water. When clogged, the filters become a breeding ground for bacteria. Solution: Ensure filters are replaced in accordance with the manufacturers’ specifications or even more often, depending on the quality of your source water.

General maintenance: Water treatment equipment should be accessible and cleaning solutions and other non-drinking water chemicals and materials should be kept away from the equipment. If treatment equipment is not accessible for Ohio EPA staff to inspect during a sanitary survey, it will not be accessible to the water treatment operator for routine maintenance or during an emergency. Likewise, non-drinking water chemicals stored in close proximity to treatment equipment can be an invitation for a mix-up or, even worse, intentional vandalism (see Figure 4). Solution: Keep clutter and non-drinking water chemicals and equipment away from drinking water treatment equipment. Preferably, these items should be stored in a different room.

Developing A Better Understanding of Drinking Water Technology Approval: WINSSS Center Project B1

When EPA in 2014 chose to fund the National Centers for Innovation in Small Drinking Water Systems, their vision for the Centers was much more than developing new drinking water technologies; they asked them to also consider facilitating acceptance of both new and existing technologies, improving relationships between stakeholders, fostering dialogue among regulators, and facilitating the development of uniform data collection approaches for new technologies. All of the non-treatment pieces of the vision have been incorporated into the WINSSS Center’s Project B1.

Project B1 has three objectives:

1. Conduct a survey of the states to determine the barriers and data needs for technology acceptance.
2. Develop a states workgroup and use the survey results as a starting point to discuss how to overcome those barriers and develop a set of uniform data needs.
3. Take the workgroup results and apply them to the New England states to work toward multi-state acceptance.

The first objective has been completed, and the workgroup called for in the second has been meeting every other month since December.

Recognizing the importance of state buy-in to the project, the PI’s proposed to include the Association of State Drinking Water Administrators (ASDWA) as a partner in the survey implementation at the proposal stage. They have been a great partner, and the success of this project is a reflection of their involvement. It was also clear early on  that both Centers had proposed work related to developing a better understanding of acceptance of technologies, so we joined forces. It proved instrumental in the development of the questions, and there were at least eight participants from WINSSS, ASDWA, and DeRISK, that had a hand in the question development.

The survey included 16 questions asking states about their approach to technology acceptance, their experiences with new technologies, barriers to getting these technologies to small systems, data needs for acceptance of any new technology, and their interest in participating in our effort. Forty  states responded, again thanks to ASDWA’s involvement, and the data were telling. We learned that many states don’t consider new technologies for small systems because of cost and risk and that states generally struggle with having the staff and technical expertise to understand and approve new technologies. The most common barriers were a lack of staff and staff time to approve technologies, adequate performance data from vendors, funding for testing/evaluation, and training for state staff.

We asked the states to tell us what questions they needed answered to approve a technology, and over half of the states listed performance data to support the technology, pilot data from multiple locations or water qualities, residuals produced, third party certification and understanding of where technology is appropriate, and understanding the operator skills needed to operate the technology. They also listed the data deficiencies they see most often. These included range of water qualities tested, length of pilot testing, scale of pilot testing, and operating costs, among others.

The good news is that 11 of 14 “emerging” technologies provided to the states in the survey have already been implemented in at least 10 states. This suggests that more technologies are in use than we initially believed and for some technologies, better sharing and communication mechanisms between states are the most immediate needs.

We also asked states how they used the data from EPA’s Environmental Technology Verification Program (ETV) and Arsenic Demonstration Program in accepting new technologies. Nineteen states said they rely on ETV certification or testing protocols as part of their process. Fifteen states said that the Arsenic Demo Program influenced their decisions related to the tested technologies. These programs no longer exist, but they provide valuable insight into how we might consider developing a new program to support the states for sharing data and communicating technology approval information.

The last part of the survey focused on technology acceptance and asked the states if they would be interested in sharing data, developing common standards with neighboring states, or partnering with nearby states to coordinate technology approval. Six states did not answer this question, but 33 of the 34 who did were at least somewhat interested in developing a data sharing network. Twenty-eight states were also interested in developing common standards with nearby states, and 23 were interested in developing partnerships with nearby states to approve technologies. These are very encouraging results.

The survey data were shared with the states, and a workgroup of Centers, ASDWA, and state staffs was formed. The first meeting was in December 2015, and much progress has been made since. The workgroup has developed a draft framework for an entity that would support a shared data repository. They are currently developing a plan/proposal to share with the Interstate Technology & Regulatory Council board (ITRC) to consider how this entity might work with or within the existing ITRC framework. No decisions on this have been made and the workgroup is evaluating options. An open call to all industry stakeholders is planned for late July or early August to share progress to date and to get feedback.

There are no illusions that this can all be accomplished in a short time; the issues and barriers related to technology acceptance have been discussed within the industry for more than 25 years. But this project has created buzz within the industry, as well as with the states and USEPA. It has momentum, and the idea of developing a consensus approach for sharing data and fostering cooperation among all stakeholders that both supports the states need to protect public health and makes it easier for technologies to be accepted by states is now being discussed among all of the relevant players.

Educate Decision Makers With Help From RCAP

Google “drinking water” or “wastewater,” and you’re sure to find a growing list of news articles about lead safety concerns, the recent PFOA and PFOS advisory, nitrogen and phosphorus pollution, and our crumbling infrastructure. The weight and fervor of these public discussions may concern some who grapple to protect our drinking water and environment. But increased attention has its benefits. It could mean your board members and other community decision makers would be more receptive to learning about your operations and operational needs. And that’s an opportunity you don’t want to miss.

Last year, the Rural Community Assistance Partnership released two video series designed to help leaders in small, rural communities make more informed decisions about drinking water and wastewater operations, maintenance, and expansion. Each video spends roughly 2-4 minutes walking the audience through a different technical step in the drinking water or wastewater treatment process. Click on the links below to watch the videos.

Wastewater Treatment

1. Introduction
2. Collection system
3. Preliminary treatment
4. Primary treatment
5. Secondary treatment
6. Solids and sludge handling
7. Effluent disinfection
8. Effluent disposal

Drinking Water Systems

1. Introduction
2. Raw water intake
3. Pre-settlement and pre-treatment
4. Static mixers and flash chambers
5. Sedimentation and filtration
6. Distribution systems

Beyond these series, sharing the RCAP video The Importance of an Operator in a Community’s Water System with your governing body will provide insight into the day-to-day work of an operator and the importance of that role.  

Click here to browse these videos in a playlist.

To find more videos from RCAP and other technical assistance providers, visit our Documents Database and click Videos in the Type category. And subscribe to the WaterOperator.org newsletter to get featured videos and other resources sent straight to your inbox.  

Operator Math Part 3: Continuous Education

This is the third and final installment of our operator math series, and we’re closing with an eye to the future. When the exams are done and you’re thrown back into the stress of daily operations, it’s easy for math skills to get a little rusty.

Here are some great videos, blog series, and more to help you test and strengthen your knowledge of commonly—and not so commonly—used formulas and functions. And many of these resources can also double as exam prep, making them something you can turn to again and again.

Problem of the Day

Wastewater Technology Trainers gives you a keep your skills sharp and review at your own pace with their Problem of the Day blog series. Each problem is provided in the form of a downloadable document containing a page or two about working in the wastewater treatment industry followed by the sample problem. Although each of the documents appear similar at first, you’ll find the problems generally begin on the second or third page following a schedule of problems provided on earlier dates. 

Indigo Water Group Math Videos

This series of 13 videos walks through the procedures for solving common water or wastewater math problems. Viewers are able to learn how to solve problems in a step-wise process by following along with the video, which demonstrates and explains each step. The series contains three unit conversion tutorials, five geometry tutorials, three dosing tutorials, one that calculates pump run time to reduce MLSS concentration, and one that calculates VSS loading rate to an anaerobic digester.

CAwastewater.org Math Videos

These 19 HD-quality videos were created by operators for operators. They provide instruction, examples, and advice on math topics covered by the Grads 1-5 exams offered in California.

Big Books of Math Problem Generator

Also from Indigo Water Group, this tool gives you a new set of problems with every click. Each set is provided as an Excel spreadsheet, allowing you to easily work through the solutions at your own pace. Click on the “Math Problem Generator” link at the bottom of the page.

Skills Builder

This webpage allows you to test your knowledge of wastewater and laboratory topics using Skills Builder—a set of quizzes provided by WEF as a free resource for operator education. The quizzes incorporate math, safety, and a variety of other topics. Skills Builder provides feedback on your answers as well as references for follow-up study sources. Results are completely confidential and are not recorded. 

Industry groups and not-for-profits, including our partners at the Rural Community Assistance Partnership, also regularly host operator math training courses and webinars. Learn about these and other training opportunities with our Event Calendar.   

Operator Math Part 2: Online Tools and Apps

Last week, we shared a few basic tips to help you master some of the calculations used in day-to-day operations. Understanding these and other functions and formulas is an integral part of the job, but working through the problems can be intimidating. Fortunately, there is a large bank of online tools and apps geared toward water and wastewater professionals that puts solutions literally at your fingertips. 

Of course, mobile technology is fast-moving and new tools are being released almost daily. Here are just a few of the ones available at no cost right now.

Online tools

From the Pennsylvania Department of Environmental Protection:

• Temperature Conversion  
• Millions of Gallons Conversion
• Loadings Calculator
• Pounds of Chemical per Gallon
• Tank Volume Calculations
• Dry Chemical Calculation
• Removal Efficiency
• mL per Minute Conversion
• Food to Microorganism Calculator
• Metric Conversions

From the Missouri Rural Water Association:

• Circular Break Around Pipe
• Hole in Pipe
• Rectangular Break Along Pipe
• Monthly Water Loss
• Annual Water Loss Average
• Well Drawdown and Specific Capacity
• Pipe Disinfection
• Tank Disinfection
• Well Casing Disinfection
• Solution Strength Mix

Device apps

From Georg Fischer AG:

• FlowCalc – Apple

From Pipeflowcalculation.com:

• Pipe Diameter Calculator – Android

Be sure to check back here next week for the last post in our operator math series. We’ll have resources to help you keep your calculation skills sharp.

Operator Math Part 1: Practical Guidelines

Mathematical calculations can be a challenge for even for the most veteran of water and wastewater operators. The formulas for volume, chemical dosage, filtration, pipe velocity, and other daily problems vary of course, but there are a few underlying guidelines that can help you make sure your answer is correct regardless of the calculation you’re working on. 

This is the first in a three-part series dedicated to operator math. The tips below are adapted from information provided by the South Dakota Department of Environmental and Natural Resources.

1. Learn what a formula means, not just when it is used. This will help you remember when to use πR2H to calculate the volume of a cylinder instead of 2πRH—the formula for measuring the surface area of a cylinder’s sides.
2. Use unit labels throughout your calculation to help you easily see whether you need to multiply or divide.
3. Always convert percentages to decimals.
4. Convert “inches” to “feet” unless you’re trying to solve a pressure problem. Using “inches” in any other problem will almost always leave you with the wrong answer.
5. Make sure the units you end with match the problem you are trying to solve. If a volume calculation results in a “square feet” or “square yards” answer, something went wrong along the way.
6. Trust your suspicions. If the answer doesn’t seem right, check that you used the right formula and units before running the problem again.

For those looking for more detailed and specific instruction, our documents database is a great place to start. Here are some of the resources you’ll find if you search “math.”

Basic Math Handbook

This 24-page handbook is a basic math study tool. It provides formulas for basic geometry, velocity & flow rates, and pressure, force & head, and contains several typical water problems that show users how to apply the formulas in real-world scenarios. 

Formula and Conversion Sheet for Drinking Water Treatment and Distribution

This 1 page document provides conversions and formulas for water treatment & distribution operators in studying for a certification exam. 

Chlorine Contact Time Calculations

This 7-page document provides guidelines on how to solve math problems that deal with calculating chlorine contact time. It includes important equations and practice problems with solutions. 

Industrial Math Formulas

This 7-page document provides a list of valuable formulas and conversion factors important for wastewater operators. 

Intermediate Water Math

This 37-page study guide contains 82 intermediate water math questions. Solutions to the problems are provided at the end of the document. 

Advanced Wastewater Math

This 29-page study guide contains 35 advanced wastewater math questions. Solutions to the problems are provided at the end of the document.