Page 28

SOURCE - Spring 2013

sources have some chromium. USEPA is having larger utilities across the country monitor for Cr(VI) and total Cr for the third Unregulated Contaminants Monitoring Rule (UCMR3). CDPH has been collecting Cr(VI) data from utilities for years. We know that, depending on the MCL level proposed by CDPH, hundreds to maybe thousands of California utilities will have to comply. So how can water systems control their chromium? Fortunately, the City of Glendale and other nearby water agencies took the lead to find ways to remove Cr(VI) from their groundwater starting more than a decade ago. Around 1999-2000, when the movie Erin Brockovich was released and OEHHA first proposed its vastly lower PHG, the water utilities in Glendale, Burbank, Los Angeles and San Fernando pooled their money and had the AWWA Research Foundation (now, the Water Research Foundation) oversee a 28 SOURCE spring 2013 study on how to reliably get Cr(VI) below 5 ug/L. Subsequently the U.S. Congress (through USEPA), California (through Proposition 50), the Association of California Water Agencies (ACWA) and other groups funded a sequenced series of studies to continue and refine the initial results. Three treatment technologies look promising and are in refinement as we speak. Weak base anion exchange, strong base anion exchange and reduction, coagulation and filtration may each work under specific conditions. Capital, operations and maintenance and waste disposal costs vary by circumstance, but are significant. In this sense, treatment for Cr(VI) is similar to treatment for arsenic. A lot of small groundwater-based systems will have to figure out what might work for them and try to find the money to pay for it. Those from Nevada and other states have time to watch what happens in California. USEPA will use the data from UCMR3 and a pending revised risk assessment to consider whether to revise downwards the current total chromium MCL of 100 ug/L or create a new Cr(VI) MCL. But that won’t be for several years. S Cr(VI) Conference Abstracts Chromium Treatment Studies at Glendale, Residuals and Treatment Testing Guidelines Treatment options for hexavalent chromium removal from drinking water were presented, including anion exchange (weak and strong base), reduction/coagulation/ filtration, and high-pressure membranes. Testing at the City of Glendale California has shown that residuals waste and pre- and post-treatment needs can be significant for the treatment approaches, impacting cost and technology applicability for individual utilities. Nicole Blute, Hazen And Sawyer, Email: nblute@hazenandsawyer.com. Tel: 310.266.6212. Cr(VI) Regulatory Update, continued from page 21 100% Environmental | Employee Owned | Offices Nationwide BrownandCaldwell.com ©2013 Brown and Caldwell Engineers | Scientists | Consultants | Constructors Continued on next page


SOURCE - Spring 2013
To see the actual publication please follow the link above