Project Offers Cost-Effective Solution to Meet New Arsenic MCL
In January 2006, the U.S. EPA estimated that between 2,300 and 3,000 public water systems still needed to install new central treatment systems, or make other operational changes, to comply with the new 10 ppb maximum contaminant level (MCL) for arsenic. Central treatment, which ensures the water in the distribution system as well as every tap connected to it complies with the new regulation, has been a challenge for many small communities, especially small groundwater systems serving populations of 3,300 or less, mainly due to cost. As a result, many of these communities are looking to apply for regulatory exemptions. While exemptions offer temporary cost savings, they don’t defend the population from possible negative health impacts.
One option for these communities is the employment of point-of-use (POU) and point-of-entry (POE) treatment technologies, which provide an alternative by only treating a portion of the water for less cost.
In order to determine the feasibility of using POU/POE technology for reducing arsenic or other similar contaminants in real-life situations, NSF International entered into a cooperative agreement with the EPA’s Office of Ground Water and Drinking Water and the National Research Institute to undertake a case study of decentralized water treatment through the application of POU/POE technology.
“The feasibility study was yet another critical step forward in the consideration of POU and POE devices as suitable tools for managing drinking water compliance,” said Tom Bruursema, general manager of the NSF Drinking Water Treatment Unit Program. “This concept is far from being a new application of a technology that has for decades provided improved water quality in the home. It is, however, an application that has been met with skepticism and concerns spanning many years.”
According to the staff of the EPA Office of Ground Water and Drinking Water, “The basic objective of the case study was to develop and document a systematic approach to decentralized treatment by evaluating POU/POE technology and applying that technology in situations when it is economically feasible to do so.”
To assist with project development, the agencies formed a project management group that included representatives from the EPA, the Association of State Drinking Water Administrators, the American Water Works Association, the National Rural Water Association and the Water Quality Association. The group outlined criteria for community and equipment selection, oversaw the project and provided comments on project results.
“We screened dozens of communities from many states,” said Joe Cotruvo of J Cotruvo & Associates, LLC, who provided general project management. “We were looking for size, arsenic less than 50 ppb and more than 10, representative income level for small communities, state regulator interest, transportation accessibility, access to a nearby service provider, and community interest and support.”
The city of Grimes, Calif., a predominantly bilingual, low-income community, was selected to participate in the study.
“Grimes was of the right size for this work; it was a good mix of lower- and middle-level residences; it had a school and small commercial sites; and had good support from the California Department of Health Services,” said Perialwar (Regu) Regunathan, president of Regunathan & Associates, Inc., who also helped manage the project.
Grimes is a small farming community located 45 miles northwest of Sacramento. It has a raw water arsenic concentration of 25 ppb, evenly split between arsenic III and V—lower than the previous standard of 50 ppb, but higher than the revised MCL. The city adds chlorine to the water, so for treatment purposes, the arsenic was all in the +5 valence state.
In addition to community selection, the project management group provided criteria for equipment selection, such as performance, cost, ease-of-use, installation and maintenance. The preferred product was media-based, included an automatic shut-off device or alarm to signal when cartridge replacement was necessary and was certified against the appropriate NSF/ANSI standards. The product also had to be commercially available, come with a warranty and have an available local service representative.
“Several manufacturers were contacted and assessed, and Kinetico, Inc. fit all the criteria,” Cotruvo said.
Mark Brotman, research scientist for Kinetico, said the company was consulted regarding which technology might be most appropriate. “The best choice ended up being POU filters that monitor water volume and automatically shut off at 500 gal.” The selected unit features two activated alumina cartridges in series followed by a granular activated carbon cartridge. It was designed to be installed under the sink with a separate drinking water tap.
“Kinetico donated the equipment, installation supplies, labor and replacement cartridges to help the project succeed,” Brotman said. “The authorized Kinetico dealer for the area, Blue Fountain Water, owned by Randy Orella, is conveniently based in Sacramento. Blue Fountain scheduled and made all the installations for the city.”
The California Department of Health Services (DHS) requested the units meet a criterion of <2 µg/L, instead of the MCL, as a precaution. To confirm performance with Grimes’ water, a pilot test was performed with the product. After disabling the shut-off devices, two units were run to exhaustion, and they continued to produce water with <2 µg/L of arsenic beyond 500 gal. The pilot test also ensured the safety of disposing spent cartridges in household trash.
“Understanding the necessary elements of the infrastructure to make this application work was exactly the foundation for the feasibility study, and the next logical step for NSF to assist,” Bruursema said. “However, it had to go one step further in terms of stakeholder participation, as none of this would work without the cooperation of the community.”
Prior to the installations, the Grimes residents were mostly unaware of the arsenic levels in their water. The project management group held community meetings to explain the project to residents and answer their questions.
“The town meetings were very good because everyone had a chance to learn about the project and get involved,” said Art Olivares, board member of the Colusa County Water Works District 1 in Grimes. “It was important to educate the community about the project and its length and cost because residents would have to be present during installations and monitor the units for leaks and other problems during the first few days after installation.”
Regunathan added, “Almost all of the residents were very cooperative with the study staff. There were a few who refused to have installations in their houses, but these were very small in number.”
Installations began in July 2002 and included all Grimes residences except for six homes, two of which already had their own RO units installed. Business and other commercial installations included two restaurants, a store, library, school and church.
The project staff encountered various challenges during installations. Initial scheduling was difficult because the project began during the farming community’s harvest season. During this time, many residents were not available, working long hours most days of the week. Communication also presented some installation difficulties. Approximately 40% of the community speaks Spanish as a first language, but a Spanish-speaking installer was not available on site.
Homes with old/unique plumbing challenged installers further. Residences with standard plumbing usually require a 15- to 30-minute installation; however, installations in Grimes took anywhere from 15 minutes to three hours. This did not include the time spent locating unusual parts and fittings.
Unit performance of <2 µg/L of arsenic was confirmed at installation, and units were sampled quarterly for one year. The majority of units continued to deliver quality water throughout the study period. A few units showed arsenic levels >2 µg/L, but most of these were in high-use locations such as schools, businesses or large-family homes.
Some units that were not in high-use locations produced water with >2 µg/L of arsenic, but upon further investigation, Kinetico discovered that the contractor filling the activated alumina cartridges was not filling them completely, resulting in channeling through the media.
In order to determine the advantages of POU/POE treatment as an alternative to central treatment for arsenic reduction, the Grimes case study included a detailed cost analysis of the project. The cost analysis took into account the total cost of equipment, installation, maintenance, compliance monitoring, replacement cartridges and other miscellaneous costs.
“The analysis was based on the actual cost data incurred in using the activated alumina technology for 150 installation sites in Grimes,” explained Patrick Mann, professor of economics at West Virginia University and author of the project cost analysis. “The analysis indicates that the annual connection cost for Grimes is $128, or $11 per month. This would result in a tripling of water bills for the residents of Grimes. However, centralized treatment could involve as much as a $90 increase in monthly water bills for Grimes residents.”
In a survey conducted after the project, Grimes residents said they would be willing to pay $8 per month for POU treatment and $12 per month for central treatment.
“The study in Grimes, Calif., is one example that on the surface may seem somewhat isolated, but in reality addresses the issues many communities face when considering the POU/POE alternative,” Bruursema said.
According to the EPA, POU treatment devices may be an option for public water systems where central treatment or even POE treatment is not affordable. This project demonstrates that the increase in Grimes residents’ water bills resulting from the use of POU technology meets EPA guidelines for affordability.
The use of centrally managed POU strategies had been very limited prior to the arsenic rule, and this project identified a number of issues that small systems will need to consider as they evaluate their treatment options.
According to Olivares, Grimes community members are happy with the taste and quality of the water produced by the units. “For the most part, it was an easy transition, and overall the project was a success.”