A Look at Protozoa in Wastewater Treatment Systems

Wastewater treatment is fundamentally a biological process. When influent enters the microbial ecosystem of a treatment plant, nutrient removal is accomplished through the consumption of organic matter by microorganisms. The bulk of all nutrient removal is performed by bacteria, however protozoa and metazoa balance these bacterial populations and offer insight into wastewater conditions. Operators who understand the varying roles of wastewater microbes and the conditions that favor their growth can foster an ecosystem that promotes optimal treatment. In this week’s blog post we will review the niche protozoa fill in wastewater systems to enhance monitoring efforts and inform process control.

Roughly four percent of a wastewater system’s microbial ecosystem is made up of protozoa. Protozoa are single celled microbes both larger in size than bacteria and more complex. The most common types of wastewater protozoa include amoeba, flagellates, and ciliates. By consuming free bacteria and small, unsettled floc, protozoa enhance the clarity of the final effluent. Observing protozoa populations under a microscope can also alert operators of treatment conditions and sludge age.

Amoeba are predominant under a young sludge age because they require high nutrient levels or low competition to grow. Under shock loads of biochemical oxygen demand (BOD), high concentrations of particulate matter, toxic conditions, or low dissolved oxygen (DO), amoeba can also dominate. The latter two conditions generally trigger the amoeba to develop a protective gelatinous shell that gives them an advantage over other microbes. Furthermore, their slow movement reduces oxygen demand required for growth and reproduction.

Flagellates are typically present under a young sludge age as well. Since flagellates compete poorly with bacteria for the same soluble nutrients, their growth is favored at the younger sludge age before bacteria have had a chance to populate. As such, a wastewater sample relatively high in flagellates can indicate high soluble nutrient levels also known as a high food to mass (F:M) ratio.

Ciliates are favored under a healthy sludge age. While they do not consume organic matter, they do feed on bacteria making them excellent indicators of healthy floc formation and useful clarifying agents. Without ciliates, bacteria and algae populations can grow out of control in the wastewater microbial ecosystem. Among the three types of ciliates common to wastewater, each group has different conditions under which their populations are favored.

Swimming ciliates start to form as flagellates disappear. They may experience a spike in population when levels of free bacteria are abundant for predation. If too many free bacteria are present, the ciliate population surge can ultimately result in a cloudy effluent. Crawling ciliates dominate when those free bacterial populations begin to stick together forming floc through a secreted slime layer. This slime layer is produced when dissolved nutrients become limited. Since swimming ciliates cannot readily pick off bacteria within the floc, crawling ciliates begin to out-compete them. As they feed on bacteria, crawling ciliates can improve flock structure. A more mature sludge age with reduced BOD allows stalked ciliates to compete with crawling ciliates. Stalked ciliates anchor themselves to floc using the cilia surrounding their mouth structure to create currents that draw in bacteria. Once their food levels have diminished significantly more, stalked ciliates begin to branch into colonial units to acquire food more efficiently. If sludge continues to age, stentors and vaginocola protozoa grow in abundance.

For more information on wastewater protozoa and how to monitor them, we’d like to recommend the following documents. These resources and others like them can be found using our online, resource library.

Bacteria Protozoa – Toni Glymph
The guide overviews basic wastewater microscopy, slide preparation, sample collection, and the microbiology of activated sludge plants.

Wastewater Microbiology & Process Control - Wisconsin Wastewater Operator’s Association
Learn the about microscopes, slide preparation, and the microorganisms found during wastewater treatment.

Protozoan Count – Toni Glymph
This guide describes how to sample protozoa for observation under the microscope.

Developing Your Source Water Protection Program

Effectively safeguarding drinking water sources will ensure that your community has reliable access to affordable, potable water for generations to come. As such, utilities of all sizes should strive to develop and implement a source water protection program. Not only do these programs reduce the need to adopt costly advanced treatment processes, but their value extends environmentally, socially, and through public health as well. By maintaining water quality at the source, systems protect a fundamental barrier under the multiple barrier approach. Furthermore, a protection program has potential to not only maintain, but improve water quality.

Developing and enforcing a source water protection plan will act as a proactive defense against contamination introduced from various land uses such as agriculture, commercial facilities, landfills, mining, oil and gas operations, stormwater runoff, failing septic systems, and more. A plan can also act to mitigate impacts from climate changes such as drought or saltwater intrusion. To start a program, systems can break down the process into six steps:

1. Delineating your source water protection area
2. Inventory sources of potential contamination
3. Assess susceptibility of your system to these contaminants
4. Notify and engage the public about these contaminant threats
5. Develop and implement a protection plan to reduce, prevent, or eliminate threat
6. Develop contingency planning strategies if source water is compromised

Of course, some of these steps are easier said than done. To assist in your source water protection endeavors, we’ve highlighted several resources to get you started. If you expect challenges along the way, consider contacting your regional Rural Community Assistance Partnership (RCAP) partner for support.

Before developing a plan, review your source water protection area and any existing contaminant sources identified by your state’s Source Water Protection Assessment Program (SWAP). Under the 1996 Amendments to the Safe Drinking Water Act, state programs were required to identify the land area that could impact water quality at each public water system. In addition, each state program completed an inventory of potential contamination sources in that area, evaluated water quality susceptibility to that contamination source, and made these results publicly available under SWAP. States completed the source water assessments in 2002, but were not required to maintain updates. To locate the results of your assessment, start with the EPA’s Source Water Regional Contacts or contact your state’s source water protection program.

The methods in which source water protection areas were identified and evaluated depend on the state. Many states published resources on how they chose to carry out the SWAP as demonstrated in the Connecticut Department of Public Health’s SWAP document. For updated or more local source water delineations and contaminant source inventories, public water systems can reach out to local environmental consulting firms, federal agencies like the NRCS or USGS, state cooperative extensions, and local colleges. The EPA has also developed a How-To Manual to Update and Enhance Your Local Source Water Protection Assessments that describes why and how you should collect more data.

With the state SWAP results and the EPA’s How-To manual, utilities can complete the first three steps in developing a protection program. Making the public aware of these results will allow systems to start collaborating with local organizations on source water protection efforts. By engaging local stakeholders such as the town officials, environmental groups, watershed organizations, farmers, businesses, town’s conservation commission, county extension, non-profits, etc. systems will better understand any existing source water protection strategies, who is conducting them, and how the facility’s present and future strategies can collaborate with existing strategies.

Based on data gathered from the source water delineation, assessment, and susceptibility evaluation, utilities can work with local stakeholders to develop a protection and contingency plan. While protection plans are optional in many states, utilities should first check with their state’s source water protection program to determine if a plan is mandatory and, if so, what elements must be included. The ease of which a utility implements their protection plan will depend on source water location, contaminant threats, financial and technical resources, and the degree of community involvement. To develop the plan, public water systems will need to identify management strategies and the funding to facilitate the plan.

A strong source water protection plan will have clearly defined goals with a list measurable actions and those who are responsible for them. Most plans should also include a timeline to measure progress, requirements for water quality monitoring, and a plan to track the successful completion of measurable actions. The goals outlined in the plan will ultimately address the water quality risks identified in the assessment through land use controls, land acquisition, and education. The scope of the plan may range in focus from local, regional, or statewide involvement. Check out the 2019 Roswell Municipal Water System plan to view an example of a medium-sized system’s source water protection program. To help develop a plan of your own, we’d like to recommend the following:

Guides:

The Source Water Stewardship: A Guide to Protecting and Restoring Your Drinking Water
The Clean Water Fund
The handbook walks public water systems through the process of understanding an assessment, reaching out to stakeholders, and designing an action plan.

New Mexico Source Water and Wellhead Protection Toolkit
New Mexico Environment Department
This toolkit will help public water systems develop a source water protection program in six steps.>

Templates:

Drinking Water Source Protection Plan Template (Systems Serving <5,000 people)
Ohio Environmental Protection Agency
This template can be used by Ohio or other public water systems to outline a successful source water protection program. Instructions should be deleted from the Word document upon completion.

Source Water Protection Plan Template
Tennessee Association of Utility Districts
This Microsoft Word template can be used as a starting point for developing your source water protection plan.

Source Water/Wellhead Assessment & Protection Program Planning Guide
South Dakota Department of Environmental and Natural Resources
This 10-page guide describes the sections that should be included in a source water protection plan.

Notification Templates:

Wellhead Letter to Potential Contaminant Sites
Tennessee Association of Utility Districts
Use this letter template to request assistance and cooperation in implementing your source water protection program.

Wellhead Letter to County Mayor and Zoning Board
Tennessee Association of Utility Districts
This letter template can be used to request assistance and cooperation from the county mayor and zoning board in the development and implementation of a source water protection plan.

Developing an effective source water protection plan will take time and collaboration. For more resources on protection plans, check out our document library and use the category filter to filter by Source Water/Source Water Protection.

The Best YouTube Channels for Water & Wastewater Operators

Whether it’s to troubleshoot a treatment process, practice for a certification exam, or update your facility’s standard operating procedures, working as a small system water or wastewater operator means that you’re always learning something new to get the job done. Our mission at WaterOperator.org is to make sure you can easily find the best resources to manage and maintain your utility and reliably serve your community. A great way to bolster your knowledge at your own convenience is through training videos and webinar recordings. In this week’s blog post, we’d like to highlight our favorite YouTube channels so you can reference them when you need to develop a new skill, practice for a certification exam, or simply learn more about how to manage your system.

Certification:

American Water College
The American Water College features a variety of water and wastewater training videos that teach operators about operator math, treatment processes, operation and maintenance best practices, and utility management.

CAwastewater
This YouTube channel includes several wastewater math training videos for Grade 1 to Grade 5 operators of California.

Wastewater Dan
The training videos by Wastewater Dan teach operators how to calculate anything from annual energy costs to chemical oxygen demand (COD).

TheWaterSifu
Training videos on TheWaterSifu demonstrate water treatment math, laboratory techniques, and skills useful for the water treatment or distribution exam.

Treatment, Operations, and Maintenance:

Aquafix, Inc
The Aquafix YouTube channel hosts webinar recordings on wastewater treatment and process control. Please note that some of these videos may include promotions for Aquafix products.

Lagoons Do It Better
Wastewater operators can find webinar recordings on lagoon treatment and troubleshooting. The channel also features interviews with industry professionals. Please note that some of these videos may include promotional material for industry products.

R.C. Worst & Co., Inc.
On this YouTube channel, operators can learn about the selection and maintenance of valves, joints, switches, pumps, motors, and tanks involved in onsite wastewater treatment systems, packaged pumping systems, drinking water wells, and water treatment. Please note that some of these videos may include promotional material for industry products.

RCAP (Try their Vimeo and their YouTube channels.)
Both RCAP’s Vimeo and Youtube channels feature training videos and webinar recordings pertaining to water and wastewater treatment, operations and maintenance, monitoring, and utility management.

Wastewater Operations Channel
On this YouTube channel, Wastewater Operator Jon Kercher uploads educational videos filmed during the workday at his wastewater treatment facility. Videos range from troubleshooting treatment processes to learning about biosolids.

The Water Research Foundation
The Water Research Foundation includes webinar recordings of utility case studies, water research, and innovative technology.

Waterworks Training
Operators can watch brief training videos that demonstrate the installation and use of pipe fittings, restrainers, saddles, and couplings.

Utility Management:

Environmental Finance Center at UNC-Chapel Hill
This YouTube channel includes training videos and webinar recordings to teach systems how to improve their financial, technical, and managerial practices.

Smart Management for Small Water Systems
Small systems can use these webinar recordings to improve or develop asset management plans, start a capital improvement project, or better understand utility finances.

WaterOperator.org also maintains a YouTube channel of our own so you can find previously recorded webinars, interviews, and playlists that highlight our favorite videos. Check out the playlist Free Webinars for Water/ Wastewater Utilities to find other useful webinar recordings by organizations like the Association of State Drinking Water Administrators and the U.S. Environmental Protection Agency.

Featured Video: Interviewing Basics Webinar

In this week’s blog post, we’d like to feature an excellent webinar recording hosted and published by CA Water Pros with the California Water Environment Association and California-Nevada Section AWWA. The webinar introduces both incoming water professionals and those seeking new industry positions to some interview best practices that will help any operator stand out above the competition during a job hunt. The webinar is presented by Todd Novacek, Director of Operations at the Moulton Niguel Water District. Todd frequently interviews professionals for the District and started putting together popular interview questions with his favorite answers when his son received his Water Distribution II certificate.

From the video job seekers will learn how their social skills, attire, attitude, honesty, and pre-interview research can make all the difference in a first impression. Todd stresses the importance of gauging an audience and making every interview question count. You’ll learn popular questions that can likely be expected during an interview at a water district. These questions will help you start thinking of your own answers now. Remember that questions can vary with utility size, location, and job requirements. As Todd emphasizes, you should know the facility you’re applying to before the interview. Even when you feel that you’re already the best candidate for the job, practicing and preparing beforehand will demonstrate your dedication to the position.

Once an operator fulfills their certification and educational requirements, interviewing at utilities can seem like a completely different challenge that neither training workshops nor any workbook has adequately prepared them for. This one hour webinar is worth the time and will help operators start a new aspect to their professional development, interviewing.

Managing Dissolved Oxygen in Activated Sludge Plants

Sustaining optimal dissolved oxygen levels in activated sludge plants is necessary for biological treatment of organic material and ammonia. While raw wastewater often contains some amounts of oxygen, aeration systems can increase dissolved oxygen (DO), mixing, and the suspension of microbes through mechanical agitation or diffused aeration. Aerobic microorganisms use this oxygen to breakdown organic waste into inorganic byproducts. The amount of dissolved oxygen consumed by microbes during biological treatment is referred to as biochemical oxygen demand (BOD). According to an article by Triplepoint Water, approximately 1.5 pounds of oxygen is consumed for every pound of BOD oxidized. To oxidize one pound of ammonia, that value increases to 4.57 pounds of oxygen. Most plants aim to maintain around 2 mg/L of DO which allows microbes contained within the center of floc to receive oxygen.

Wastewater operators should regularly monitor oxygen availability in the form of dissolved oxygen. Insufficient oxygen levels will allow aerobic and nitrifying microbes to die and floc to break up. At DO concentrations under 1 mg/L, the potential for filamentous growth increases. On the other end of the spectrum, too much oxygen increases power consumption and, at very high levels, inhibits settling. Research has estimated that aeration can use up to 45 to 75% of a treatment facility’s overall electricity use. With an online DO analyzer equipped to automated controls, the EPA reports that energy costs can be reduced by as much as 50%.

Where and when an operator samples for DO will be determined by the requirements written in the facility’s National Pollutant Discharge Elimination System (NPDES) permit and basic process control. To compare dissolved oxygen levels throughout the day, samples should be collected at the same location. The Ohio EPA’s Activated Sludge Process Control and Troubleshooting Chart Methodology recommends that systems sample within 1-2 feet of the surface water near the discharge of the aeration tank into the clarifier. By collecting multiple samples in the same location throughout the week, operators can reliably determine if DO concentrations are sufficient for treatment while developing a DO profile. In addition, measuring DO at multiple depths and locations in the aeration tank can help find dead spots.  

To supply adequate DO, the Ohio EPA manual includes how to determine blower runtime based on organic loading and system design. We should  still note that temperature, pressure, and salinity can all influence the solubility of oxygen. Additional sampling locations can include the raw wastewater, aerobic/ anaerobic digester, and final effluent. Final effluent with high dissolved oxygen can cause eutrophication in the receiving waters, however low DO can harm aquatic organisms. Some permits set a minimum DO level for effluent to ensure aquatic organisms have the necessary oxygen levels to sustain life.

While every technique and tool has its strengths and weaknesses, operators can measure DO through a Winkler Titration test (see Michigan DEQ Laboratory Training Manual pg.91), electrochemical sensor, or optic sensor. The two sensors mentioned can be purchased as portable handheld meters or stationary devices. For automated blower control and continuous sampling, an online sensor is used. For NPDES compliance monitoring, measurements must be taken through an EPA approved method at the frequency specified in the permit.

When using any DO sensor, the EPA’s Field Measurement of Dissolved Oxygen (SESDPROC-106) procedures require that the equipment be well maintained and operated per manufacturer instructions. Upon initial purchase, probes should be inspected, calibrated, and verified for accuracy. During each additional use the instrument should be calibrated and inspected again. The EPA recommends checking instrument calibration and linearity using at least three dissolved oxygen standards annually. All maintenance and sampling activities should be documented in a logbook per NPDES requirements. Any time a measurement is taken, the temperature of the water and any notable wastewater conditions should also be recorded in the logbook. 

Dissolved oxygen is a frequently monitored parameter in wastewater treatment systems. Operators should have a firm understanding of how dissolved oxygen is involved in wastewater processes and how they can manage DO to achieve compliance. Check out our online document library to find useful resources to learn more.

Featured Video: What is Water Hammer?

Any water or wastewater operator should possess a strong understanding of water hammer and the implications it can have on piping systems. Water hammer, also referred to as hydraulic shock, occurs when there is a sudden change in flow velocity or direction that results in a momentary increase in pressure. If high enough, the pressure can cause damage to pipes, fittings, and valves. An example where water hammer can occur is when an operator rapidly closes a valve halting flow and sending a shockwave through the system. In Jefferson City, MO, operators responding to a ruptured water main created a second break during repairs as a result of water hammer. Pressure surges can also occur through unexpected power outages or equipment failures.

Engineers consider several variables when designing piping systems to limit potential for water hammer. Whenever a major change is made to the distribution or collection system, implications for water hammer should be evaluated.

This week’s featured video demonstrates how water hammer occurs and what it looks like using 100 feet of clear PVC pipe with an analog and digital pressure gauge. The host explains how engineers can modify the potential for water hammer in piping systems by manipulating the variables that make up the mathematic equation for the pressure profile of a water hammer pulse. Such design parameters include pipe size, recommended operating procures for closing valves, and more. Watch the video to understand how the design considerations for your piping system impact water hammer.

Rural Water Representation in the 2020 Census

As we approach the execution of the 2020 decennial census, rural communities and their water and wastewater facilities should be aware of the ramifications a new count will have on funding allocation in their community. The U.S. census is updated every 10 years in an effort to enumerate every living person in the United States. While it’s common knowledge that the count is used to update congressional district lines, the census is also used by many federal programs to determine funding distribution. Census data will help programs access population characteristics of communities, the allocation of funds to eligible recipients, and the success of ongoing programs.

In 2015 132 federal programs used census data to distribute over $675 billion in funding. Many of these programs targeted rural development, source water protection, emergency water assistance, and water and wastewater infrastructure.

The upcoming census will start April 1, 2020 by issuing every home on record with a mailed invitation to participate. Responses can be submitted online, over the phone, or by mail. The questions asked by the census cover information about property ownership, gender, age, race, and the number of people living in the residence. Responses are kept confidential under federal law. Census takers will also begin visiting colleges, senior centers, and large community living groups to conduct quality checks. By May 2020, the Census Bureau will visit the homes of those who have not submitted responses. To achieve an accurate count, the U.S. Census Bureau has worked to build an inclusive address list of housing units and develop methods to improve both self-response and follow-up procedures for those who do not respond.

While intensely rural and marginalized communities are historically more susceptible to undercounting than urban, the 2020 census design poses new concerns for rural areas. In an effort to reduce field costs and visits, the upcoming census strategy will be the first to encourage internet self-response. To address known areas of low internet connectivity, the Bureau will mail identified households a paper questionnaire or request responses over the phone. Areas with noncity-style addresses such as rural route numbers will receive a paper questionnaire from a census worker at their door. In the most remote areas, a census taker will enumerate households in-person. Unfortunately, two of the three ‘End-to-End’ tests to evaluate these methods were cancelled leaving insight into how rural communities will be effected by the census design poorly assessed.

The in-person visits pose significant challenges since the homes of remote areas are often spread apart, hidden from the main road, and made up of non-traditional living quarters. As a result, communities in rural Alaska and tribal lands are typically the most undercounted. Furthermore, minority groups, low-income individuals, and rural areas with slow internet connections will find response more difficult than those of urban areas.

Featured Video: Wastewater Treatment Process Control Testing

This week’s featured video was produced by the Athens Wastewater Treatment Plant. The plant serves a small town of approximately 1,050 people in West Virginia. In an effort to educate their small town and others across the country, Athens WWTP has developed a series of videos. In this particular recording, the plant will demonstrate several process control tests they use to evaluate their wastewater conditions. You’ll learn how Athens performs a settleometer test and monitors pH, temperature, dissolved oxygen, oxygen reduction potential, mixed liquor suspended solids, and volatile suspended solids.

Tests likes these are valuable for troubleshooting the dynamic environment of wastewater treatment processes and meeting regulatory compliance. As such, it’s important for sampling to be performed accurately, consistently, and in a location that is representative of the wastewater quality as a whole. The types of tests you perform, the number of samples taken, and the laboratory methods used to analyze these samples will depend on your system’s treatment type, chemical usage, equipment, and raw water quality. Results from the analysis will promote process optimization. A detailed copy of your facility’s sampling and testing procedures should be accessible in the utility Operations and Maintenance Manual for reference.

To provide more information on process monitoring, we’d also like to recommend:

• How to Utilize Your Lab Data to Optimize Process Control – Kim Riddell
• Wastewater Laboratory Basics – Illinois Water Environment Association
• Activated Sludge Process Control and Troubleshooting Chart Methodology – Ohio EPA
• Activated Sludge Process Control – Michigan Department of Environmental Quality
• Wastewater Sampling – U.S. Environmental Protection Agency

Studying for the Certification Exam

Studying for the certification exam can seem difficult or tedious for the many of us who are out of practice when it comes to taking and preparing for standardized tests. Adding to the challenge, most operators or operators in training must balance daily responsibilities and work with studying. In this week’s blog post, we hope to make your certification exam prep more productive by reviewing the best methods to study.

Before studying for the exam, operators should start by briefly researching the exam itself. Knowing the topics that will be covered and the resources that will be available during the test can help you make the best use of your study time. For starters, each certification agency can have a substantially different distribution of topics included on their need-to-know (NTK) criteria. The American Water Works Association (AWWA) published a 2018 summary of each state’s licensing requirements and NTK criteria (if developed), however operators should check with their primacy agency directly to really familiarize themselves with the test requirements, format, and design.

For most primacy agencies, certification exams are administered online at a certified testing center, however many agencies offer a few pencil and paper exams throughout the year. Operators that are taking an online exam can familiarize themselves with the feel of an online test using the Association of Boards of Certification’s (ABC) exam demo. For either exam format, the test taker should find out how many questions will be included in the exam, what the question format will be, and how many minutes they have to complete the exam. Certification agencies that use ABC testing services require candidates to bring photo ID, a non-programmable calculator, two sharpened #2 pencils, and an eraser. The exam will likely provide a Formula/Conversion table that you should practice with during your studies. Please check with your primacy agency to determine what score is required to pass. Most agencies require a 70% or higher.

The AWWA suggests that operators should begin studying immediately after submitting their testing application. Applications are generally due two to three months before the test date itself offering ample time to study. During this period, test takers should strive to learn and understand, not memorize, all the material identified on the NTK criteria. Setting a goal to study at the same times and location each day will help improve focus when you sit down to work. As you study, keep your notes and study material in the same binder or notebook to improve organization. How long you study each day will depend on your current knowledge and experience. Even if you think you know some material pretty well, set aside time to review just in case.

Deciding how to study and the resources you want to use will depend on how you learn best. Some operators retain information by reading and writing. For the exam, this might look like learning from a textbook or manual and then summarizing the information in flashcards or a study guide. Research has shown that writing down information improves retention. Generally by the time a student has finished their flashcards, they already know the material pretty well. Reviewing those written summaries will only reinforce that knowledge. Check out our previous blog post on free test prep resources to find downloadable study manuals. If you want to use a textbook instead, we recommend purchasing them used whenever possible!

Many other operators prefer a visual or auditory form of learning that comes from watching training videos online or enrolling in a certification exam prep course. If already studying from a textbook, we encourage visual learners to make their own diagrams and charts. Operators can find upcoming certification classes by visiting our national training calendar and selecting “Certification/Exam Prep” in the Category filter. Training courses are also good for kinesthetic learners that retain information by 'doing'. To really prepare for the exam, chances are high that you will need to apply a combination of these study methods. When none of these tips seem to work and you just can’t seem to remember an important fact or process, try developing your own mnemonic.

The last important tip we must offer is to repeat, repeat, repeat! In order to remember anything long-term, you should review the same material several times without cramming. For example, during the duration of your exam prep try reading from your study manual and summarizing the information in a notebook. Return to those summaries periodically, perhaps creating diagrams when possible or even rewriting the material for a second time. When you feel like you know your stuff, take a practice test to assess your knowledge.

Practice tests will help students determine where they need to improve while letting them get used to the types of questions that will be asked on the exam. Some primacy agencies have developed their own practice tests, however we recommended several additional practice exams in the October 29, 2019 edition of the WaterOperator.org Newsletter. The edition also includes some of our own practice questions and helpful test taking tips for the day of the exam.

Remember that doing well on the exam requires developing a study plan and sticking to it. With any luck, and a lot of practice, these tips will have you acing your certification exam!

Managing Hexavalent Chromium in California Small Drinking Water Systems

Photo Credit: "PG&E Did It, And Always Knew, Since 1952!" by Alison Cassidy 05/31/2015; Edited with cropping and color correction.

In recent years, hexavalent chromium (chromium-6) has become a taxing contaminant for small water systems in California to manage. The contaminant has a complex regulatory and legal history, some of which was made renowned by the 2000 film Erin Brockovich starring Julia Roberts. Presently, an invalidated state drinking water standard, an uncertain regulatory future, and varying positions on the potential drinking water health risks, leave small systems unsure how to proceed. Chromium-6 challenges have only been exacerbated by its history of environmental contamination through industrial sources.

On a federal level, there is currently no drinking water standard. Hexavalent chromium was evaluated under the third round of Unregulated Contaminant Monitoring (UCMR 3). While the U.S. EPA is still evaluating the results and risks of chromium-6, there is no current undertaking to develop a new drinking water standard. A regulation does, however, exist for total chromium which includes all forms of chromium. The total chromium standard of 100 ppb assumes that the chromium sample is composed entirely of its most toxic form, chromium-6, to safeguard against the greatest potential risk. In California the total chromium standard was set at 50 ppb. At the time these total chromium standards were established, ingested hexavalent chromium was not associated with cancer risks. Exposure through drinking water has now been linked to both cancer and skin reactions.

According to a 2018 publication by the Water Research Foundation, the three most reliable water treatment technologies for chromium-6 removal include: reduction, coagulation, and filtration (RCF); adsorption onto regenerable strong base anion (SBA) resin; and adsorption onto disposable weak base anion (WBA) resin. Each technology generates unique waste with different handling and disposal requirements that can be expensive for very small systems to adopt and maintain. In a recent 2019 publication by the American Water Works Association, researchers identified a treatment technique that does not generate concentrated waste by reducing chromium-6 to easily separable and non-toxic chromium-3.

Much of the chromium found in drinking water was introduced from rocks, animals, plants, or volcanic activity. While both chromium-3 and chromium-6 can occur naturally, chromium-6 is more often affiliated with industrial sites that use chrome plating, paints and sprays, leather tanning, or corrosion inhibitors.

Hexavalent chromium was brought to the forefront of public health concerns in 1996 as a result of a class-action lawsuit between Hinkley, CA and Pacific Gas & Electric (PG&E). Prior to 1996 PG&E had released chromium tainted wastewater into unlined spreading ponds around Hinkley, a remote desert community in San Bernardino County. When Hinkley learned of the contamination years later, it filed a lawsuit against PG&E. During this time, legal clerk Erin Brockovich worked to link cancer illnesses to chromium-6 exposure. A convoluted series of legal battles between PG&E and those who developed illnesses from the contamination left the scientific community uncertain about the health risks of chromium-6 in water.

Only in 2008 did the U.S. EPA recognize research by the National Toxicology Program identifying cancerous tumors in rats and mice who ingested heavy doses of hexavalent chromium. By 2013 the growing plume of contamination in Hinkley had spread to over six miles long and two miles wide. Following a long regulatory investigation of the chromium-6 health effects during the PG&E legal battles, California eventually recognized the link between chromium-6 and cancer in 2014, approving a maximum contaminant level (MCL) in drinking water at 10 ppb effective July 1, 2014.

The new standard proved difficult for many small utilities to meet compliance. Senate Bill 385 gave systems with source water above the new MCL until January 1, 2020 to come into compliance without violations. During this time, impacted systems had to submit plans for achieving compliance, obtain approval of the plan, and carry out the plan in a timely manner. Plans could include steps for finding funding, conducting a feasibility study, investigating treatment options, performing an environmental review, acquiring land, facilitating construction, and testing. 

Developing, implementing, and submitting reports for these plans was no small task for any utility. Drinking water systems granted time to meet compliance were also monitoring sources of hexavalent chromium quarterly. As systems notified customers of new exceedances, they took on the burden of managing strong community concerns. It’s estimated that chromium-6 has been detected in 2,475 California drinking water sources spread across 48 out of 51 counties. The Environmental Working Group published a map that includes the average detected chromium-6 concentration by county across the country.

In developing the new MCL, California estimated that costs to implement the rule would increase water bills by $64 per year for customers of large systems and $5,640 per year for customers of small systems. Polluters were not held accountable to assist with compliance costs in areas of industrial contamination. For small drinking water facilities like the Phelan Pinon Hills Community Services District (PPHCSD) or the San Bernadino County Special Districts Department, the sticker price for compliance came at a cost in the millions. Furthermore, these small systems must spread costs over fewer people making the adoption of hexavalent chromium solutions cost prohibitive. In San Bernadino County, PPHCSD opted to take on a water blending project while the San Bernadio County Special Districts began exploring a pilot program for new treatment technology. Ultimately petitioners against the rule claimed that the MCL was too stringent with compliance too expensive. As a result, the rule was invalidated in 2017 by Sacramento Superior Court under grounds that the Department of Health failed to consider the economic feasibility for small water systems. By this time towns like Phelan had already spent $3.7 million toward the mitigation of chromium-6.

Using the data collected during the standard’s three years of implementation, the State Water Resources Control Board intends to develop a new MCL. As regulatory development ensues, impacted systems are left uncertain how to proceed. There is no certainty that a new MCL will in fact be implemented. Yet if the Board successfully passes a new MCL, systems cannot be certain that the standard will remain at 10 ppb. The board developed this FAQ sheet to help systems with ongoing loans and project plans determine their next steps. The PPHCSD in Phelan believes that the 10 ppb standard will be reinstated and has continued to move forward with their $17 million blending project.

Systems that choose to pause or discontinue projects are still left uncertain whether they are providing their community with safe drinking water. While legally facilities must now comply with the total chromium standard of 50 ppb, California did set the chromium-6 public health goal (PHG) at 2 ppb. This PHG conflicts with the U.S. EPA’s total chromium maximum contaminant level goal (MCLG) of 100 ppb and existing research debating that ingestion of chromium-6 can alter its toxicity. For now systems must use their best judgement and remain transparent with their community about all decisions. If the 10 ppb standard is reinstated, operators of nearly 800 groundwater supply wells will be in violation of the rule according to a 2018 publication by Hausladen.

California small water systems are not alone in their challenge to manage drinking water contaminants in the absence of strong regulatory guidance. Water systems across the country have had to make tough decisions about treating unregulated drinking water contaminants, many of which were spread through commercial practices. An example of such contaminants is per- and poly-fluoroalkyl substances (PFAS) and cyanotoxins. Utility decision making to handle these unregulated contaminants must factor in finances, source water conditions, potential project affordability, availability for partnerships, existing infrastructure needs, and more. As we move closer to the new year, water systems and regulatory agencies should take note of the chromium-6 decision-making in California to understand the potential impacts of new regulations on small systems.

Katie Buckley substantially contributed to this article.