Kate Sundeen

Environmental Science

Instructor:  Leslie Anderson

PIM #3

In order to comply with the 1998 Disinfectant Byproducts Rule (DBR), the city of Washington D.C. changed its primary disinfectant from chlorine to chloramine.  This was done, because, among other things, the DBR regulates levels of trichloromethanes, a byproduct of chlorine use that is produced when hypochlorite reacts with humic acids, which the Potomac (a water source for Washington D.C.) has in abundance.  Trichloromethanes have been shown to be carcinogenic, as well as a possible cause of miscarriage in high enough amounts. 

In response to public outcry that arose from raised awareness from several highly publicized cases, and a class action law suit, Capitol Hill passed the DBR, despite warnings given by scientists and advisors to the EPA that the requirements of the DBR could be in direct conflict with another act, the Lead and Copper Rule (LCR) which regulates levels of lead and copper in drinking water.  At the time, Washington D. C. water was registering 75 ppb of chlorine byproducts (http://www.waterandhealth.org/newsletter/new/summer_2004/reducing_ lead.html).  However, it is unclear exactly how much of that 75 ppb is comprised of trichloromethanes, as the EPA lumps together all chlorine byproducts, and tests by looking for representative species.

So, given the DBR, and despite the warnings, and even some apparent concern on the part of the EPA in the form of a publication urging caution and testing of DBR-related changes in disinfection, the city of Washington D.C. moved forward with its plan to change from chlorine to chloramines.  Ultimately, the scientists’ concern was proven valid when, in February 2004, lead testing done in homes showed that over 150 homes had lead concentrations exceeding 300 ppb, thousands had lead exceeding the mandated 15 ppb, and two homes had readings in 24-48000 range (http://www.waterandhealth.org/newsletter/new/summer_2004/reducing_lead.html).

So what happened in the pipes as a result of the switch to chloramine?  Marc Edwards and Michael Schock, in a series of experiments and studies done to advise the EPA, made several discoveries.  The primary discovery was that the lead scale that had built up in the Washington D.C. pipes had begun to dissolve, resulting in the high lead readings when house water was tested.  Before the switch to chloramines, the chlorine (and resulting hypochlorite) had caused the D.C. water to be highly oxidizing, thus an insoluble environment for the lead.  The introduction of chloramines lowered the oxidizing potential, resulting in soluble conditions for the lead scale.  Furthermore, the switch from chlorine to chloramines reversed the galvanic roles of the copper pipes and the brass fixtures.  Normally, the brass fixtures were the cathode, and the copper pipes the anode.  When chloramines was introduced, the brass fixtures became the anode, resulting in leaching of lead from the fixtures.  The conclusion that they came to was that the only way to solve the problem was to deal with the change in ORP, either by increasing the ORP back to its original levels, or by increasing the pH, so that the lead would return to a stable insoluble state.

Since then, because of public scrutiny and another class action lawsuit (http://www. dcwatch.com/wasa/040308.htm)  (http://query.nytimes.com/gst/fullpage.html?res =9B0CEEDE1E3FF935A35750C0A9629C8B63&sec=&spon=&pagewanted=1) that resulted in the requirement that Washington D.C. replace over 300 million dollars worth of pipe in its drinking water system, the lead levels have dropped to 7 parts per billion (http://www.wtop.com/?sid= 1439453&nid=768).  However, even these numbers might be considered suspect, as some have suggested that many municipalities, Washington D.C. included, are fabricating their statistics in order to make the situation look better than it actually is (http://www.washingtonpost.com/wp-dyn/articles/A7094-2004Oct4.html).   Further, WASA has begun to add phosphates, specifically orthophosphates to the water in an attempt to reduce the levels of lead leaching into the water (http://www.dcwasa.com/waterquality/faqs.cfm). 

However, there is speculation that the addition of phosphates would only lead to an increase in galvanic corrosion.  In fact, experiments conducted by Marc Edwards  have shown that the addition of orthophosphate to the water and chloramines party increased the level of lead contamination in the water above those of just chloramine, alone.  Now, the experimental condition was that Edwards had connected old lead and new copper pipes, in a galvanic connection, so as to create the galvanic corrosion atmosphere, but the implication holds water.  In Washington D.C., as well as other municipal areas, there is a mixture of lead and copper pipes.  In addition, many homes have copper plumbing.  Given this factor, the presence of a galvanic connection is pretty much assured.

Furthermore, there are environmental considerations in reference to use of phosphates.  According to Metcalf and Eddy it is necessary to add ferric chloride or aluminum sulfate to water to remove phosphates.  In addition, lower pH values are necessary.  This is directly in contradiction to the problem that is being addressed by the addition of the phosphates in the first place, which is a need to raise the pH so the lead is no longer in soluble conditions.  However, removal of the phosphates is necessary (as indicated by the fact that wastewater treatment includes a phosphate removal stage), because release into the environment causes hypergrowth in plant life, usually resulting in situations such as algae blooms (http://www.ceep-phosphates. org/Files/Document/80/CEEP%20eutrophication.pdf) (http://www.saw.usace.army.mil/wetlands/ Projects/PCS/feis.html).

What does this mean for Philly?  Well, besides the documented cases of Philly underreporting lead levels, my Wissahickon water sample had an Eh of -.04619 and a pH of 7.84.  With these data, according to Shock’s table, there would be lead, lead, everywhere, and nary a drop to drink.