Complying with California's New Hexavalent Chromium Regulation

California, always striving to be at the forefront of just about everything, is now the first state in the US to implement a drinking water regulation for hexavalent chromium, or chrome 6.  Even though the regulation remains hotly contested, it is now the law.  So what does that mean to water quality professionals and operators in the field?  Let’s take a look at the regulation and see.

The new regulation went into effect on July 1, 2014. That’s the same day that responsibility for the drinking water program in the state transferred from the California Department of Public Health (CDPH) to the State Water Resources Control Board Division of Drinking Water (DDW). CDPH sent out a letter on June 20 that had a good overview of the regulation. You can get a copy of the most recently updated drinking water related regulations from the still functioning CDPH  website, or you can download a copy of it here. Chrome 6, or hexavalent chromium as they have it listed, is included with the other regulated inorganic contaminants starting at the bottom of page 109.  The approved method for analysis is EPA Method 218.6 or 218.7, and a list of laboratories approved to run these methods as of May 22, 2014 is available here.  Make sure you call and talk to whatever lab you chose just to make sure they are currently certified and what their sample submission guidelines are.

Although the regulation takes effect July 1, §64432(b) states “…each community and nontransient-noncommunity water system shall initiate monitoring for an inorganic chemical within six months following the effective date of the regulation…”, so you have until the end of the year to take your initial sample. If you've already taken samples, §64432(b)(1) allows you to use data collected in the previous two years as your initial sampling, so chrome 6 data from July 1, 2012 thru June 30, 2014 can be used if you so desire. You would just have to go back and ask your lab to upload it to the state database to make sure it’s been entered as compliance data.  You would also need to make sure the samples had been analyzed using one of the appropriate methods, because if they weren't they won’t be acceptable as compliance data.

Alternately, §64432(b)(2) of the regulation allows you to use total chromium data in lieu of chrome 6 data if your total chromium results are below the total chrome detection limit for purposes of reporting (DLR) of 0.010 mg/L.  The logic there is since chrome 6 is included as a part of the total chromium analysis, if total chrome is below 0.010 mg/L, then chrome 6 must be as well.

The regulation allows you to collect samples at the source or at the entry point to the distribution system.  §64432(e) states “Samples shall be collected from each water source or a supplier may collect a minimum of one sample at every entry point to the distribution system which is representative of each source after treatment.” It’s a good idea to discuss with you local DDW office where you want your compliance point to be, and be sure to sample from the same location every time.

Like most inorganics, the initial monitoring will determine your subsequent monitoring schedule.  §64432(j) states, “If a system using groundwater has collected a minimum of two quarterly samples or a system using approved surface water has collected a minimum of four quarterly samples and the sample results have been below the MCL, the system may apply to the Department for a reduction in monitoring frequency.”  Compliance with the MCL will be determined on a running annual average (RAA) of 4 quarters of data.  If you take more than one sample per quarter, the average of the samples for that quarter will be used in calculating the RAA.

There is a provision in the regulation (§64432(f) on the bottom of page 112) for any inorganic contaminant that allows you to composite up to 5 wells. However, you have to get approval from CDPH for such a plan, and it is based in part on 3 years of historical data.  I’m guessing that with the political nature of chrome 6, the newly minted DDW may not want to venture down this road. 

So what are the options if you have wells over the MCL? There are various forms of treatment, which of course are all very costly. Best available technologies (BAT) for chrome 6 are coagulation/filtration; ion exchange; or reverse osmosis.  All of these have quite high capital and operational expenses. I think systems with a mix of wells, some over the MCL and some under, need to look long and hard at blending. If you’re wells are scattered that means installing dedicated transmission mains, which is costly and disruptive. But I think when you do a cost analysis on how much treatment is going to cost, looking at both capital and operations, you might find that installing transmissions mains, even long ones, to facilitate blending doesn't look so bad.

That’s a general overview of the new regulation, and a synopsis of compliance issues to be aware of. If you have any other questions, don’t hesitate to reach out to me and ask. You can always contact me via LinkedIn or e-mail at patrick.vowell@wework4water.com.