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i <br /> since then increased to 48.5 mgfL (May 2004). Since nitrate concentrations began increasing in 1999, <br /> 1 seasonal fluctuations also increased. <br /> L <br /> The presence of the observed nitrate concentrations is likely related to both the historical agricultural land <br /> use in the area prior to the commencement of aggregate mining by Teichert Aggregates and also <br /> continuing farming practices. This includes the nitrate concentration increases in the Brown's#I well. <br /> Copper, iron,and zinc concentrations in shallow groundwater samples are typically low and frequently <br /> below their respective reporting limits. For example,the record(69 monitoring events) for the Hall well <br /> fr shows one copper detection(100 pg/L in May 1999 sample), three iron detections(50 to 80 pg(L), and <br /> six zinc detections(30 to 130 gg(L). To date, manganese has not been detected in the Hall well. In <br /> L samples retrieved from the Faulkner well,copper and manganese concentrations have always been <br /> nondetect iron and zinc concentrations have ranged from<10 to 160 pg/L and from<20 to 220 pg/L, <br /> ` respectively. <br /> 4 As in shallow groundwater samples, traces of copper concentrations in most deep groundwater samples <br /> are rarely detected. In contrast, von, manganese and zinc are frequently detected in most deep wells; and <br /> variability is high. Most frequently, these metals were detected in samples retrieved from the Brown's <br /> New well and the Brown's#I well. These metals are also present in well water more recently retrieved <br /> from the Granite#3 well. Metal detections in the South Tracy#1 and#3 wells are few. <br /> Total coliform bacteria have been nondetect from the Hall and Faulkner domestic wells with few <br /> ` exceptions. Most recently,total coliform bacteria were detected at the reporting limit of 1.1 MPN/100 <br /> mL in the August 2008 sample retrieved from the Hall well. Fecal coliform organisms were nondetect. <br /> Coliform bacteria were also nondetect in the November 2012 samples(coliform samples were <br /> inadvertently not collected in May 2012). The sporadic presence of coliform bacteria can be due to <br /> sample contamination at the time of collection,the introduction of coliform bacteria to the well structure <br /> during well and pump maintenance work, or the detachment of bacterial biofilm from the well structure in <br /> combination with naturally occurring coliform organisms. <br /> 1 <br /> 4 <br /> ©LLf[ M 6 SGALMANINI <br /> CONSULTING ENGINEERS 7 <br /> L <br />