Call to Ben Uhl, Hahn and Associates, “Gasco” Site Field Manager, March 23, 2012

I returned a call from Mr. Uhl earlier in the morning regarding the groundwater sampling work scheduled to begin next Monday March 26, 2012. Mr. Uhl was wondering if Hahn had approval to proceed. I indicated I wasn’t going to provide approval to proceed or not, but I had comments based on my review of their March 9^th letter recommending modifications to the quarterly/semi-annual groundwater monitoring program.

The highlights of what I communicated to Mr. Uhl are listed below.

Removing amenable and WAD cyanide was approved. Sampling will include total, free, and available cyanide.

Additional information is needed to support Hahn’s recommendations for dropping certain of the metals from the monitoring program. In many cases although many of the analytes were not detected, ½-MRL and/or “J-flagged” detections were greater than the lowest screening value (usually the MCL). Also, differences in MRLs between MFA and Hahn made it difficult to draw conclusions regarding some parameters. In general, ½-MRLs associated with Hahn’s sampling work are less than screening criteria, but in many cases (e.g., antimony, selenium) MFA’s are greater. Additional, review and analysis of the data is needed to determine whether the difference in MRLs effects Hahn’s recommendations.

In response to questions from me, Mr. Uhl confirmed the EPA 6000-7000 series methods allow all metals to be collected and provide adequate holding times (45 days) so decisions can be made regarding modifying the analyte list without requiring postponement of the work.

Sampling for general chemistry parameters, including some metals (calcium, sodium, magnesium, potassium) at monitoring wells in the monitoring program that will be included in the performance monitoring program should be maintained.

We ended the call with Mr. Uhl indicating that Rob Ede will contact me on Monday March 26^th to discuss the sampling work further.