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' monitoring to establish new compliance standards and M-11R became the new compliance well. ' G9~-Y Once the baseline period was completed, the compliance wells were monitored on a quarterly peg ;J+ urz ' K schedule. Until July of 1998, no unusual values were recorded in the compliance wells..°The a;.~ ~' July 1998 quarterly sampling results indicated an exceedance of the TDS cotrlpliance limit at ' Well M-11R. The established compliance limit was 613 mg/I and the measured value was 661 /l I d i h TR 15 BMRI i di l ifi i ance w n accor t - , mg . mme ate y not ed the D vision and took a verification sample. The verification sample came back with a TDS value of 772 mg/l. Since ' [his was also high, a second verification sample was taken. The second verif-ication sample had a TDS value of 720 mg/I. ' BMRI then began development of a response plan to describe further actions to be taken to ' deal with this exceedance. BMRI also sought expertise in hydrology and hydnogeology from their consultant John C. Halepaska and Associates and in geochemistry from their consultant, Geochimica, Inc. It should be noted that based on the review of the limited data available, the initial TDS values measured at M-11R were within the existing background water quality data set for the aquifers that are hydraulically upgradient of M-11R. Therefore, the response plan initially focused on additional data collection to verify the existence of a real exceedance as opposed to a potential inappropriate setting of compliance standards. 1 ,~^ BMRI met with the Division on September 28'" to discuss the response plan. As a result of the meeting, BMRI began collecting water quality samples at other wells in the West Pit area which were not being used for water quality monitoring, including the old dewatering wells ' (DW series), wells along the pit wall (PW series) and wells to monitor the water level in the backfill (BF series). The samples were collected October 1"• 2nd and 5'" and the results were available October 12'". The results of this monitoring showed high levels of TDS and sulfate t PW 1 ddi th d i di l d di I i f kf ll d i i h b ent a - . on, ese ate y owngra t e ac i e p t an mme n 8 in certa n areas o t results showed that sulfate now exceed the compliance limit in Well M-11R. ' At this point, BMRI decided to re-evaluate the response plan to address the issues that the new information was presenting and met with the Division, and informed them on October 26`s that a new response plan was forthcoming. 1 13