Lab Science News

This article describes the background, stages and the new deadlines for public water systems to comply with the most current disinfectants and disinfection byproducts rule.

By Dr. Harlan H. Bengtson, PE

Background on Disinfection and Disinfection Byproducts

Jersey City, NJ was the first U.S. city to routinely disinfect its municipal water supply, starting in 1908.¹ Soon after, thousands of cities and towns across the country began to do the same and this dramatically decreased the prevalence of waterborne diseases such as cholera and typhoid. To demonstrate, the incidence rate of typhoid fever in the U.S. dropped from about 100 cases per 100,000 people in 1900 to 33.8 cases per 100,000 people in 1920.² By 2006, this rate had dropped to 0.1 cases per 100,000 people.³

While the purification of drinking water has clearly been beneficial for public health, unintended byproducts may form when disinfectants react with water’s natural minerals. Indeed, some of these disinfection byproducts (DBPs) may pose serious health risks to humans. In tests on laboratory animals, some DBPs have been shown to be carcinogenic and cause adverse reproductive or developmental effects. In 1979, concerns about the potential health risks of DBPs led to the EPA setting an interim maximum contaminant level (MCL) of 0.10 mg/L for trihalomethanes. This MCL applied to the annual average contaminant level in any community water system that served more than 10,000 people and added a disinfectant to the drinking water as part of its treatment process.⁴

Between July 1997 and December 1998, under the Information Collection Rule, 296 public water systems (serving at least 100,000 persons each) monitored and collected data on microbial contaminants, disinfectants and disinfection byproducts. The resulting information helped lead to the creation of the Stage 1 Disinfectants and Disinfection Byproducts Rule.⁵

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The Environmental Protection Agency (EPA) has determined that a new nutrient standard is necessary to meet the requirements of the Clean Water Act (CWA) in Florida. In January 2010, the EPA proposed to adopt water quality criteria for total nitrogen and total phosphorus (nutrient pollution) in Florida lakes and streams.

Similar to the human body, bodies of water require nutrients, such as nitrogen and phosphorus, to be healthy, but too much can be harmful. According to the EPA, nutrient pollution is one of the top three causes of impairment of the nation’s waters.

Although the EPA has recognized Florida as a national leader in its efforts to manage nutrient-related pollution, substantial water quality degradation from nutrient over-enrichment remains a significant challenge in the state. The EPA plans to promulgate the new standards in October 2010, meaning that lakes and flowing waters will have to meet those new criteria within twelve months and estuaries and coastal waters must comply within twenty-four months.

The combined impact of both urban and agricultural activities along with Florida’s physical features and aquatic ecosystems mean that the current use of the nutrient criteria alone is insufficient to ensure protection of water systems. Likewise, the EPA believes that the increased water quality standards will strengthen the foundation for identifying impaired waters, preparing Total Maximum Daily Loads (TMDLs) and developing National Pollutant Discharge Elimination System (NPDES or stormwater) permits.

The proposed criteria are based on more than a decade’s accumulation of data from Florida’s Department of Environmental Protection and represent more than 10,000 observations of nutrient levels, measurements of aquatic system health, and other variables. This is one of the largest data sets developed by a state for the purpose of developing nutrient criteria.

While the EPA’s current regulatory activity will apply only to Florida waters, it could have national significance as it provides considerable insight to the approaches the EPA deems adequate for numeric nutrient criteria for lakes and streams.

The EPA aims to reduce air emissions from certain stationary diesel engines and issued their first standards on February 17, 2010. The rule will help reduce formaldehyde, benzene, acrolein and other toxic air pollutants from diesel powered stationary reciprocating internal combustion engines (RICE), also known as compression ignition (CI) engines. The toxic air pollutants, also referred to as hazardous air pollutants or air toxics, are suspected of causing cancer and other serious health effects as well as environmental damage.

EPA estimates that the rule will reduce annual toxic air emissions by 1,000 tons, particle pollution by 2,800 tons, carbon monoxide emissions by 14,000 tons, and organic compound emissions by 27,000 tons when fully implemented in 2013.

The new emission limits apply to existing diesel engines meeting certain criteria for age, size, and use. EPA estimates that more than 900,000 of the engines generate electricity and power equipment at industrial, agricultural and other facilities. Industrial facilities such as power plants and chemical and manufacturing plants use these engines to generate electricity for compressors and pumps. They also are used in emergencies to produce electricity to pump water for flood and fire control. Emergency engines used at most residences, hospitals and other institutional facilities, and commercial facilities such as shopping centers are not covered by this rule.

To meet the emissions requirements, owners and operators of the largest engines will need to install emissions controls, such as catalysts, to engine exhaust systems that would limit air toxics emissions by up to 70 percent. Emergency engines covered by this rule need to comply with operating requirements that will limit emissions.

EPA will issue final emissions standards for similar existing stationary engines that burn gasoline, natural gas and landfill gas, known as spark ignition engines, by August 10, 2010.

EPA, in a recent study, found that concentrations of chemicals in recycled tire material were below levels considered harmful. Recycled tire material, or “tire crumb,” is commonly used in synthetic turf sports fields and children’s playgrounds.

According to EPA, public concerns have been raised in the past several years over the use of tire crumb materials, especially after high levels of lead were reported in some artificial turf fields. In 2009, the Synthetic Turf Council reported that artificial (synthetic) turf has been installed in approximately 4,500 fields, tracks and playgrounds.

EPA identified a number of chemicals that may be found in tires, although not all are contained in each tire:

EPA formed a workgroup in 2008 to consider the threat of tire crumb health effects via inhalation, ingestion, or skin contact. Laboratory studies were conducted to consider the tire material content, off-gassing, and leaching characteristics. EPA then produced a 105-page document entitled “A Scoping-Level Field Monitoring Study of Synthetic Turf Fields and Playgrounds,” released in November 2009.

Study findings

• Particulate matter, metals and volatile organic compound (VOC) concentrations were measured in the air samples and compared with areas away from the turf fields (background levels). The levels found in air samples from the artificial turf were similar to background levels found in any local air samples. One VOC associated with tire crumb materials (methyl isobutyl ketone) was detected in the samples collected on one synthetic turf field but was not detected in the corresponding background sample.
• No tire-related fibers were observed in the air samples.
• All air concentrations of particulate matter and lead were well below levels of concern.
• More than 90 percent of the lead in the tire crumb material was tightly bound and unavailable for absorption by users of the turf fields.
• Zinc, which is a known additive in tires, was found in tire crumb samples. However, air and surface wipe monitoring levels of zinc were found to be below levels of concern.
• Total extractable metal concentrations from the infill, turf blade samples and tire crumb material varied widely in the samples collected both at a given site and between sites, so it could not be determined to be a function of the presence of crumb material.
• The average extractable lead concentrations for turf blade, tire crumb infill, and tire crumb rubber were low. Although there are no standards for lead in recycled tire material or synthetic turf, average concentrations were well below the EPA standard for lead in soil (400 part per million).
• Likewise, the average extractable lead concentrations for turf field wipe samples were low. Although there are no directly comparable standards, average concentrations were well below the EPA standard for lead in residential floor dust (40 micrograms per square foot).

The results from this study along with results from other studies conducted by Federal, State, and local organizations, such as the Consumer Product Safety Commission (CPSC) and the Agency for Toxic Substances and Disease Registry, will be considered at an EPA meeting planned for Spring 2010. This meeting will help to identify steps to address public questions regarding the safety of tire crumb infill in ball fields and playgrounds.

For more information, visit EPA’s website www.epa.gov/nerl/features/tire_crumbs.html

EPA has finalized national effluent limitations guidelines (ELG) and new source performance standards (NSPS) for construction and development sites to help address improvement of water quality throughout the nation. While the standards focus on discharges occurring during stormwater events, these new guidelines affect all discharges of pollutants from construction activities into waterways, including dewatering and concrete washout.

Non-numeric ELGs: All construction and development sites will be required to meet a series of non-numeric ELGs beginning in February 2010. These are intended to minimize any discharge from a construction site to a water body, and may include:

• Strict stormwater runoff control from sites
• Minimization of steep slope disturbances, amounts of exposed soil, and soil compacting
• Stabilization of soils
• Provision and maintenance of natural buffer zones
• Discharge control from non-stormwater activities like dewatering, truck and tire washing, concrete washouts, etc.

Numeric Limits: Construction and development sites must sample stormwater discharges and comply with the numeric limitation for turbidity of 280 NTU (nephelometric turbidity units). EPA is phasing in the numeric effluent limitations over four years to allow permitting authorities adequate time to develop monitoring requirements and to allow the regulated community time to prepare for compliance with the numeric effluent limitation. These phases consist of:

• Sites that disturb 20 or more acres at one time will be required to conduct monitoring of discharges from the site and comply with the numeric effluent limitation beginning 18 months after the effective date of the final rule (August 1, 2011).
• Sites that disturb 10 or more acres at one time will be required to conduct monitoring of discharges from the site and comply with the numeric effluent limitation beginning four years after the effective date of the final rule (February 2, 2014).

Although streams and rivers naturally carry sediment loads, discharges associated with construction activity can elevate these loads to levels above those in undisturbed watersheds. Discharges from such sites may also increase the proportion of silt, clay and colloidal particles, along with other pollutants in receiving streams because these fine-grained particles may not be effectively managed by conventional erosion and sediment.

EPA stated the proposed rule is designed to achieve cleaner streams and waterways through implementation of erosion and sediment control measures and pollution prevention practices. According to EPA, sediment is one of the leading causes of water quality impairment nationwide. Activities such as clearing, excavating, and grading can lead to soil erosion into streams and other bodies of water. This discharge can cause a variety of physical, chemical, and biological impacts to water bodies.