cc: SPGEG, GTLO, ACORN, Sierra Club
sb: Arsenic in groundwater question
The TCEQ Asarco remediation website says that "...Currently, the highest concentration of arsenic in the groundwater occurs in onsite well EP-49 with a concentration of 62.5 mg/L, which is above the MCL for arsenic. This well is located on the east side of Paisano Drive. The area of contaminated groundwater is shown in Figure 2."
- I am confused why Well EP-49 is mentioned having a top concentration of 62.5 mg/L but leaves out that "above the MCL" is actually "6,200 times above the MCL.g " (see: "The groundwater at the facility has arsenic, lead, and cadmium concentrations above the maximum contaminant level (MCL). ......The most prevalent COC in the groundwater is arsenic. Currently, the highest concentration of arsenic in the groundwater occurs in onsite well EP-49 with a concentration of 62.5 mg/L, which is approximately 6,200 times the MCL for arsenic. The area of contaminated groundwater is shown in Figure 5."
Would you add those words to that webpage? (i.e. "6,200 times")
- Also, I am concerned that this Well EP-49 is being reported as having the max groundwater arsenic level when another map shows a well with 332.8571 mg/L level (see attached, and the figure at the bottom of this email.) Why the discrepancy?
- In addition, we know that in a "May 14, 1999 sampling event, Asarco reported a concentration of 0.302 ppm for arsenic in the groundwater. The previous sampling event (February 25,1999) from the same well reported a concentration of 320 ppm for arsenic in the groundwater. #EPRI-9905-118. On further review, well EP-49 has a sample identification. Finding that sample identification in the lab sheets appendix, the lab reported a concentration of 302 ppm for arsenic in the groundwater. Please correct the table and incorporate a procedure to include well identification numbers corresponding to submitted plats on lab reports." (see attached 20011002 response)
This refers to the same well that you say has a max arsenic level of 62.5 mg/L -- yet the 2/25/99 sampling event for that well showed 302 ppm.
Would you explain this, please?