The U of A maintains four monitoring wells spaced hundreds of feet apart around the Page-Trowbridge radioactive/toxic waste landfill. Water from these wells is periodically sampled to determine if the hazardous wastes buried at the landfill have begun to infiltrate the groundwater. 

Bis(2-ethylhexyl)phthalate

       Bis(2-ethylhexyl)phthalate was detected in groundwater from two of the four monitoring wells at Page-Trowbridge by U of A Risk Management and Safety personnel, on August 23. 

Bis(2-ethylhexyl)phthalate is listed as a carcinogen in California.

       The August sampling was occasioned by a meeting between concerned Oracle residents and representatives from the U of A, the Arizona Department of Environmental Quality (ADEQ) and the Environmental Protection Agency (EPA) last April. 

       At the meeting representatives from Oracle expressed discomfort with the University of Arizona's method of sampling the groundwater used for detecting possible contamination of the groundwater by the Page-Trowbridge landfill and urged that samples be taken using a different method called 'bailing'. 

       The U of A agreed that a sampling of the groundwater should be done using the bailing method and on August 23 the sampling occurred with Oracle residents acting as observers. 

       In a report issued by the independent testing laboratory that analyzed the samples, Bis(2-ethylhexyl)phthalate was present in water taken from two of the four monitoring wells at Page-Trowbridge. 

       The amounts detected ranged from 17 ppb to 52 ppb. 

       The University of Arizona has not yet informed Oracle residents what they believe the source of the Bis(2-ethylhexyl)phthalate could be.

The Unexplained Toluene Detection

       In August of this year officials from the University of Arizona disclosed that tests on a groundwater sample taken from one of the monitoring wells at the Page- Trowbridge radioactive/toxic waste landfill last April found toluene at a concentration of 3.7 ppb, resulting in re-sampling and re-testing of the groundwater 15 days later. The maximum contaminant level for toluene is 1 ppm which is equivalent to 1000 ppb.

       The subsequent test detected no toluene, according to University of Arizona officials responsible monitoring the Page-Trowbridge landfill for possible contamination of the aquifer. 

       When asked for their opinion as to what could explain the finding of toluene in one sample and no toluene in the sample taken from the same well 15 days later, U of A Risk Management personnel said that the finding was unexplainable, calling it "an anomaly".

       Toluene is also known as methylbenzene, methacide, phenylmethane, toluol and antisal 1A.

       Toluene is a volatile organic compound (VOC) that can cause a symptoms ranging from minor nervous system disorders such as fatigue, nausea, weakness and confusion, to more pronounced nervous disorders such as spasms, tremors, impairment of speech, hearing, vision, memory, coordination, as well as liver and kidney damage. 

Understanding the Anomaly 

       In order to understand the unexplained toluene detection, it is necessary to understand the sampling and testing process.

       The landfill has four monitoring wells around the landfill. Two samples are taken from each of the four monitoring wells at the site. 

• One sample from each well is sent to a lab for testing and the U of A Office of Risk Management retains the other samples (called duplicates). 

 

 

The bottles containing the samples are marked with the identification of the well from which they were taken. 
 

• The samples are then sent to an independent lab and tested for contaminants. 


In the event that contamination is detected in an original sample, the duplicate is then sent to the lab and tested to validate that the compound was actually found in the original sample. 
 

• If the duplicate is found contaminated, then contamination of the groundwater is confirmed. 

 Otherwise the finding is not confirmed, and the water is declared safe to drink if the level of the contaminant is below the limit set by the EPA. 

       The shelf life of a duplicate is 14 days. In other words, if a duplicate is over 14 days old, it cannot be used and a new set of samples must be obtained.

       Wundrock explained that normally the testing lab immediately informs the U of A by phone when a contaminant is found in a sample. But in this case the testing lab failed to call when toluene was detected in the original sample from Monitoring Well #5.

       Wundrock said that because of the unusual failure of the lab to notify the U of A, University personnel were unaware of the toluene finding until they received the written report from the laboratory. 

       Unfortunately the report was received after the 14-day ‘shelf-life’ of the duplicate sample from monitoring well #5 had expired. Because the shelf life of the duplicate had expired, the duplicate could not be used to validate the toluene finding, and U of A risk management re-sampled water from monitoring well #5 May 17. 

       Tests on this sample showed no toluene. 

Possible Explanations

       Oracle resident Cliff Russell later offered a couple of possible explanations for the anomaly, "In my experience, detection of VOC's can be sporadic -- one sample can show VOC's while a subsequent sample will not show them. 

       "So one explanation would be that the toluene originally detected in the first sample, had moved on by the time the second sample was taken a couple of weeks later.

       "Another possible explanation is that there was an error in labeling the bottles used to hold the water samples.

       "For example, if the bottle containing the original sample that showed the 'hit' of toluene was mislabeled as coming from well 5 when it really came from another monitoring well, then retest of well number 5 would show a clean sample because the toluene was really detected in a different well.

       "The U of A could have eliminated the possibility of this sort of error by re-sampling and re-testing the water from all of the monitoring wells, not just well number 5. Re-testing water from all the wells would have shown whether the toluene was actually present or not," said Russell.

       The EPA found that the U of A had mislabled samples in 1992.