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. 

SWRCB Proposing Mandatory Outdoor Water Conservation for All Californians

This is a message from the State Water Resources Control Board.

This message is to notify interested parties of the availability of the attached Proposed Emergency Regulations pertaining to the Prohibition of Activities and Mandatory Actions During the Drought Emergency; Notice of Proposed Emergency Rulemaking; Emergency Regulations Digest; and Fact Sheet.

This item will be considered at the July 15, 2014 State Water Board meeting.  The State Water Board is particularly interested in hearing comments on the applicability of the proposed regulations to wholesale water suppliers, as well as comments pertaining to other aspects of the proposed regulations.

For more information about the Board meeting please refer to the July 15, 2014 agenda that is available at:  http://www.waterboards.ca.gov/board_info/calendar

Related files:

1. Proposed Emergency Regulations pertaining to the Prohibition of Activities and Mandatory Actions During the Drought Emergency
2. Notice of Proposed Emergency Rulemaking
3. Emergency Regulations Digest
4. Fact Sheet

Why I Worry About Advanced Oxidation Water Treatment

Advanced oxidation processes are becoming more prevalent in wastewater, recycled water, and drinking water treatment. There is no doubt that these processes are very effective at treating a wide range of otherwise difficult to treat for chemicals from whatever source you start with. But what happens to the chemicals we are treating for when we use advanced oxidation? And could we be creating a bigger problem than we started with?

Advanced oxidation (AO) refers to treatment to remove chemicals by oxidation through reactions with hydroxyl radicals.  Most commonly, this is achieved by the addition of either ozone (O3) or hydrogen peroxide (H2O2) and then exposure to UV light.  The process is very effective; if you have a given chemical in your source and then treat it by an AO process and re-test it, the chemical will be found at a greatly reduced level or even be completely gone.  But where did it go?  This is not an adsorptive process like ion exchange or treatment with GAC; the chemical is not being physically removed from the water. The Law of Conservation of Mass, as well as common sense, dictates that it cannot simply disappear. And AO treatment does not break chemicals down all the way to their individual atomic constituents. So what’s really happening?

The AO process simply changes the chemical into something else.  Usually, a chemical is broken down into smaller chemicals, although that is not always the case.  Sometimes its form is simply modified.  So what you end up with after advanced oxidation is not contaminant free water.  You have simply traded one contaminant for one or more others.  That is the point at which I start to worry about the AO process.  To oversimplify, the AO process takes one contaminant that we may or may not understand the toxicity of, and modifies it into one or more different contaminants that we probably know even less about.

Some research has been done on this issue, but not nearly enough.  One group of researchers show how the cancer drug cyclophosphamide (1), when treated by AO, has as its main reaction product 4-ketocyclophosphamide.  You can see from the chemical structures in Figure 1 that the reaction product is not much changed from the parent compound.

 If you analyzed your water after treatment, it would appear the cyclophosphamide had gone, which it has, but only to be replaced by a very similar compound.  Is that good? Is the water after treatment more protective of the environment and of public health?  I don’t think we have any idea, which is exactly the point.

Another excellent paper that came out in 2007 in The Journal of the International Ozone Association (2) reviews the knowledge of a wide range of compounds and how they react in the AO process. In the paper, the authors state “In some cases, disappearance of parent pharmaceutical compounds does not indicate successful treatment because the degraded products may be as biologically active as the parent compounds.”  The degraded products may be as biologically active as the parent compounds.  Or they may not.  Or we may have absolutely no idea if they are or not, so we may have no idea whether what we are considering treatment isn’t itself a source of contamination. 

In the same paper, one of the compounds reviewed is carbamazepine, a widely used anticonvulsant that “has been found ubiquitously in the aquatic environment.”  The reaction products of carbamazepine after AO are several, and have names far too long for me to type out here. But the authors recognized that these reaction products were “polycyclic heteroaromatics known to be toxic to aquatic organisms.”  Are they more or less toxic than the carbemazapine itself? Do they have synergistic effects that cause them to be more toxic working together than separately? Again, we just don’t know.

Just this year, a paper was published describing a new tool that is available to try and answer the question of how compounds break down when subjected to AO. In the ACS Journal Environmental Science & Technology, Xin Guo, et al (3) gives the basis for a model that can be used to “predict the degradation mechanisms and fates of intermediates and byproducts produced during aqueous-phase advanced oxidation processes for various organic compounds.”  That’s sounds like a great tool that those who implement these processes should look into to help predict what’s actually happening during treatment.

AO is a promising technique that has proven applications in many water treatment scenarios, whether you’re dealing with wastewater, drinking water, or water recycling.  But a great deal more study needs to be done to make sure we aren’t creating bigger problems than we currently have.  I call upon all of those involved in the issue, manufacturers, end users, and industry associations like AWWA, WRF, and WEF, to support the investment needed for research into these questions.

1)                  Hernandez C, Fernandez LA, Bataller M, Lopez A, Veliz E, Ledea O, Alvarez C, Besada V, Cyclophosphamide degradation by ozoneunder advanced oxidation process conditions, IOA 17^th World Ozone Congress, Strasbourg, 2005, VI.3.2-1-11

2)                  Ikehata, K.; Naghashkar, N.J.; Ei-Din, M.G. Degradation of aqueous pharmaceuticals by ozonation and advanced oxidationprocesses: A review. Ozone Sci. Eng. 2006, 28, 353–414.

3)                  Computer-Based First-Principles Kinetic Modelingof Degradation Pathways and Byproduct Fates in Aqueous-Phase Advanced OxidationProcesses, Xin Guo, Daisuke Minakata, Junfeng Niu, and John Crittenden; Environmental Science & Technology 2014 48 (10), 5718-5725