Our Projects

Corona Leading the Charge to Achieve Chromium (VI) MCL Compliance

Want more information? Click “Learn More” to access a webinar on chromium (VI) compliance, treatment technologies, and ongoing research.

Making Chromium (VI) Compliance Plans Simple

   Hexavalent chromium, also referred to as Cr(VI), chromium 6, or chromium (VI), is chromium found in the +6 oxidation state.  The experts at Corona Environmental Consulting have lead the charge in researching occurrence and treatment of chromium (VI) for over a decade (see references). This expertise is particularly crucial now, due to the California Division of Drinking Water finalizing the regulation for chromium (VI) in April of 2014. This directive is the first regulation in the nation for this compound. As of August 2015, 171 water systems and 409 sources in California are above the chromium (VI) maximum contaminant level.
        In the summer of 2015, Senate Bill 385 became law, allowing water systems to submit compliance plans to the Division of Drinking Water.  Once the compliance plan is approved and the plan is followed, the system is not considered to be in violation of the regulation.
        Using our extensive chromium (VI) treatment experience and ability to integrate data from the state’s database, Corona Environmental Consulting has developed a template compliance plan to assist utilities in meeting the May 1, 2016 plan submittal deadline.

Treatment and Research

        The applied research that Corona staff have conducted on chromium (VI) treatment technologies has saved our clients millions of dollars.  This research is now benefiting many chromium (VI) impacted communities.  Our focus has been on optimizing the strong base anion exchange and reduction coagulation oxidation filtration treatment processes.  Corona has the great privilege of leading the process design for the first permitted and operational full-scale units in California for both of these treatment technologies.  We are currently working with eight communities to implement treatment.

Funding Assistance

        Complying with new regulations is often very expensive.  The Corona team uses our experience and technical expertise to assist our clients to secure available and applicable grants and loans.  We have provided the technical reports that clients used to successfully secure millions of dollars in grant and loan monies.  Corona staff have also led and supported the subsequent research, permitting, design and construction efforts.

Corona Responds to Cases of Naegleria fowleri Infection


        Naegleria fowleri is a naturally occurring free-living amoeba, found in fresh warm waters worldwide. It is thermophilic and grows at temperatures up 46°C. It causes a rare and usually fatal infection of the brain called primary amebic meningoencephalitis (PAM). In the fall of 2011, PAM deaths of a 51-year-old woman and 20-year-old man in Louisiana were linked to the use of tap water in neti pots for sinus irrigation. N. fowleri was found in the pots and in the plumbing of the homes, which are in two geographically separate parts of the state, DeSoto Parish and St. Bernard Parish. A child in St. Bernard Parish died in September 2013 from PAM, and water from the home tested positive for N. fowleri. In the fall of 2013 water from these two public surface supplies tested positive for the parasite. In response to finding N. fowleri in the water systems, the Louisiana Department of Health and Hospitals (DHH) issued an emergency rule on Nov. 7, 2013 requiring that all water systems in the state maintain a residual disinfectant level of 0.5 mg/L, and increase their number of routine sampling sites by 25%. A 0.5 mg/L level has been shown to control N. fowleri in Australia where it became a problem in drinking water in the 1970s.

        Corona is supporting the LDHH and community water systems in the State of Louisiana to manage data, develop laboratory capacity, train operators and support implementation of the emergency rule.

Information System Development

        Implementation of the emergency rule requires collection and interpretation of data from many community water systems. Corona has developed a geographic information system that allows the LDHH to take on this task as well as improve and streamline other tasks such as data management for the Total Coliform Rule. The information system allows users to see distribution systems, create and manage sample locations for all community water systems and to query water quality data by sample location, source water type (ground, surface, purchased), system or statewide. The system incorporates other water system data such as treatment processes, type of secondary disinfectant and population served. Easy access to those data has helped the LDHH develop a sampling plan for understanding the occurrence of N. fowleri in treated drinking waters and the connection between plant and source water characteristics and the occurrence of N. fowleri.

Support to Utilities

        Corona and LDHH have supported utility responses to N. fowleri through review of nitrification control plans, development and delivery of training sessions to operators and by assisting utilities with distribution system management. Operator training sessions are ongoing and focused on informing operators about chlorine chemistry, maintaining a disinfectant residual, sampling and distribution system management.

Development of N. fowleri Laboratory and Methodology

        Corona is assisting the LDHH Public Health Laboratory with development of in-house capabilities for testing water for N. fowleri. Few labs outside of Australia are familiar with Naegleria testing and the State needed the ability to conduct monitoring of their water supplies to understand the extent of potential contamination and effectiveness of the emergency rule disinfection requirements for controlling the amoebae. Corona’s microbiologists began working with Dr. Vince Hill’s group at the US CDC in January 2014 to learn the methods CDC developed and uses for environmental investigations and those methods have been implemented at the DHH lab. The methods incorporate both 1L grab samples and high volume (10 to 100L) filtered samples that are processed and tested using culture methods to recover live N. fowleri cysts and trophozoites, and use PCR to positively identify the organism. Check out the CDC page on Naegleria fowleri.

Chlorine Residual Efficacy Research

        Through a subcontract with an academic partner, Corona is investigating the ability of disinfectants to penetrate sediments such as those that accumulate in drinking water distribution system storage facilities. Biofilms and sediments are a fact of life in drinking water distribution systems and can shelter organisms such as N. fowleri from residual disinfectants. This research will help fill an important data gap in our understanding of methods for control of N. fowleri and other problematic organisms associated with storage tank sediments.

West Virginia Testing Assessment Project (WV TAP)

The Elk River Spill

        On Jan. 9, 2014, a chemical storage tank leaked 10,000 gallons of crude MCHM (methylcyclohexanemethanol) into the Elk River where it travelled 1.5 miles to the intake of the West Virginia American Water’s Kanawha Valley Water Treatment Plant. The licorice odor chemical contaminated the drinking water for the 300,000 residents of Charleston, WV resulting in the governor issuing a “Do Not Use” order. A month after the incident residents continued to smell the licorice odor although the chemical was no longer detectable in tap water samples. On February 9, 2014, the governor of West Virginia charged Corona with conducting a large-scale science and engineering investigation that would examine the contradictory licorice odor reports, below detection limit analytical results, and toxicity of MCHM. This was the initiation of the West Virginia Testing Assessment Project (WV TAP).

        The WV TAP team was composed of science and engineering experts from the US and abroad. Within 48 hours, the WV TAP team had begun an in-home tap water sampling program in the affected area. Home water samples were rush-shipped by the West Virginia Army National Guard to WV TAP members across the United States for immediate analysis for MCHM. The WV TAP program was designed to obtain the knowledge needed to understand if the water was safe to use in all intended ways (drinking, cooking, washing, and flushing). Four questions became the framework of the WV TAP program and four distinct studies were designed in response. The final report can be found with the detailed reports on each of the scientific on theWV TAP website. Articles on the spill and its aftermath are also found in the Journal of the AWWA.

Moving Forward

        Responding to the major chemical spill affecting 300,000 citizens in Charleston, WV was the stepping off point in assisting water utilities in the US to take a proactive approach to source water protection. Corona Environmental Consulting has now developed WaterSuite, a cloud-based information system that facilitates the identification of chemical threats to source water and organizes available data on the health effects, treatability and recommended response in the case of a spill. This information system will help utility staff, regulators, emergency responders and the public deal with future emergencies. Corona is also working on developing sensor and early warning systems which can focus on identifying the chemicals that are known to occur near drinking water intakes.

Corona Explores Premise Plumbing: Where Good Water Goes Bad

What is 'Premise Plumbing'?

        Premise plumbing is defined as the point from the service connection line to the public distribution system to private supply extending through schools, hospitals, businesses and private buildings. At the point after the meter, the water supplier is no longer legally responsible for water quality in the pipes (an exception in US is the Lead and Copper Rule).  The water quality responsibility becomes that of the building owner – an individual, business, or property manager.  Microbiological (and chemical) water quality can degrade rapidly when water moves from the distribution system into a building for many reasons:  large surface area to volume ratio; plumbing materials; water age and temperature; little or no disinfectant residual; and cross connections.  Building owners may not recognize water quality degradation in premise plumbing as an issue or one that is under their control.

A Growing Spotlight

        Premise plumbing water quality is receiving more attention recently in part due to widely publicized outbreaks of Legionnaires’ disease (LD) caused by Legionella bacteria (large outbreak in NYC at the moment) and the deadly Naegleria fowleri (the “brain-eating amoebae”)cases in Louisiana. LD is a sometimes fatal pneumonia often affecting those that have weakened immune systems. N. fowleri causes primary amoebic meningoencephalitis or PAM, a fatal brain infection that occurs in young healthy individuals when contaminated water enters the nose.  These are only two of a group of microorganisms known as opportunistic pathogens that can colonize and reproduce in premise plumbing with devastating outcomes.  These microbes are referred to as opportunistic pathogens in premise plumbing or OPPPs.

A New Focus for Corona

        Corona is researching treatment methods to deal with pathogens in premise plumbing for the purpose of educating property owners on best management practices. We are targeting property types where people are most likely to be vulnerable to airborne pathogens like Legionella in hopes of dramatically reducing the number of fatalities these pathogens cause.

Removing Volatile Disinfection Byproducts Using Aeration Technologies


       The Stage 2 Disinfectants and Disinfection Byproduct Rule (Stage 2 DBPR) require water systems to maintain Total Trihalomethanes (TTHMs) below 80 µg/L on a locational running annual average (LRAA) basis. The compliance requirement has been especially problematic for small systems that have limited infrastructure, operational budgets and skilled staff resources. In-tank aeration has been used since the 1970s for TTHM control, especially in consecutive systems, or in distal parts of the distribution system. There are many aeration technologies available, each have their own advantages and disadvantages. Review of water quality, water age, location, and site conditions, are essential in selecting an appropriate aeration system for a given facility. Additional considerations such as air emissions, potential for TTHM reformation post aeration need to be considered during selection and design of an aeration system.


        The Table below lists the various aeration technologies commercially available for TTHM control. Multiple suppliers are available for each technology. The advantages/ disadvantages of each technology are also summarized in the Table.

Corona's Work with the Water Research Foundation

         As part of Water Research Foundation (WRF) Project # 4411, Corona performed the first side-by-side demonstration of two different aeration technologies in a small system (OTOE-Missouria Tribe, Red Rock, OK) that had historical TTHM challenges. The project was partially funded by USEPA’s Office of Research and Development, and USEPA Region 6. Various design and operational parameters including tank mixing, active and passive ventilations, and TTHM reformation were investigated as part of the project. Two online and benchtop TTHM monitoring instruments were also piloted as part of this project, and their performance was compared and validated with grab sample analyses. Guidance for aeration system selection, sizing, and operations, specifically tailored towards small systems, was developed through this study. The final project report is publically available, and can be downloaded from the WRF website at: http://www.waterrf.org/PublicReportLibrary/4441.pdf.