2008-02-20_REPORT - C1980001 - Laserfiche WebLink

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limit from 0.05 m to 0.01 m. In 2000, the laborator raised the detection limit for pp pp Y unionized ammonia back to 0.05 ppm, then lowered the detection back to 0.01 ppm in 2001. The 2007 sampling period shows consistent sampling results to all previous events. Unionized ammonia concentrations were below the detection limit of <0.01 mg/L at all sites ' for all sampling dates of 2007. 3.3.11 Surface Water Nitrite ' Chart 16 shows nitrite concentrations for monitoring sites TR-A, TR-B, TR-C and TR- D for the period of record. Nitrite concentrations have been consistently below detection limits with few exceptions. Nitrite was elevated at site TR-D with a value 0.32 mg/L in April 1999. This value is not consistent with historical data or the other monitoring sites during the April 1999 monitoring event. The April 1999 TR-D value is considered to be a sampling/laboratory error. The nitrite concentration upstream of the mine at TR-A was 0.06 ppm in the July 2001 ' sample. The concentration decreased as it passed by the mine site as a result of dilution. Samples collected in May and October 2001 show nitrite levels at TR-A below the detection limit. The 2007 sampling period shows consistent sampling results compared to all previous events. Nitrite concentrations were below the detection limit of <0.01 mg/L at all sites for all sampling dates of 2007 with the exception of site TR-A in July with a concentration of 0.03 mg/L. 3.3.12 Surface Water Orthophosphate ' Chart 17 shows orthophosphate concentrations for monitoring sites TR-A, TR-B, TR- C and TR-D for the period of record. Values obtained for orthophosphate have been low with ' most being below detection limits throughout the duration of monitoring. Orthophosphate showed some perturbation during the 2001 sampling period at TR-B. However, concentrations downstream of TR-B are consistent with previous sampling results. Therefore, ' either sample contamination or laboratory error is suspected. The 2007 sampling period shows slightly elevated sampling results compared to the previous decade. The lowest orthophosphate concentration in 2007 was the lower detection limit of <0.01 mg/L at ' numerous sites for numerous months and the high was recorded at all monitoring sites in October with a value of 0.03 mg/L. 3.3.13 Surface Water Chloride, Potassium and Iron Charts 18, 19 and 20 show chloride, potassium and iron concentrations for monitoring ' sites TR-A, TR-B, TR-C and TR-D for the period of record. Chloride and potassium were added to the monitoring program in 1993 while iron was added in 1994. The concentrations of all of these parameters in Trout Creek water are generally low. The 2007 sampling period ' shows consistent sampling results to the previous monitoring events regarding these constituents. Chloride and potassium have shown a trend decrease and stabilization over the past decade. Iron levels during the 2006 and 2007 monitoring periods slightly decreased