SITE INFORMATION AND CORRESPONDENCE

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L L During its early period of record(1994-2001),nitrate concentrations in samples retrieved from the L Brown's New well were stable, fluctuating between 6 and I 1 mg/L; and its recent samples are within that range or lower. Nitrate concentrations in the Granite#3 and Granite#4 range from 6.5 to 16 mg/L. L The greatest long-term variability and seasonal variability is exhibited by the Brown's#1 well. Nitrate concentrations initially increased from 12 to 30 mg/L in 1994,decreased to 12-16 mg/L in 1997-98,and since then increased to 48.5 mg/L(May 2004). Since nitrate concentrations began increasing in 1999, seasonal fluctuations also increased. LThe presence of the observed nitrate concentrations is likely related to both the historical agricultural land use in the area prior to the commencement of aggregate mining by Teichert Aggregates and also Lcontinuing farming practices. This includes the nitrate concentration increases in the Brown's#1 well. Copper,iron,and zinc concentrations in shallow groundwater samples are typically low and frequently L below their respective reporting limits. For example, the record(73 monitoring events)for the Hall well shows two copper detection(100 µg/L in May 1999 sample and 20 Itg(L in November 2013 ),five iron detections(50 to 100 µg/L),and six zinc detections(30 to 130 µg/L). To date,manganese has not been detected in the Hall well. In samples retrieved from the Faulkner well,copper and manganese L concentrations have always been nondetect;iron and zinc concentrations have ranged from<10 to 210 µg/L and from<20 to 220 µg/L,respectively. L As in shallow groundwater samples,traces of copper concentrations in most deep groundwater samples are rarely detected. In contrast,iron,manganese and zinc are frequently detected in most deep wells; and variability is high. Most frequently,these metals were detected in samples retrieved from the Brown's L New well and the Brown's#1 well. These metals are also present in well water more recently retrieved from the Granite#3 well. Metal detections in the South Tracy#1 and#3 wells are few. Total coliform bacteria have been nondetect from the Hall and Faulkner domestic wells with few L exceptions. Most recently,total coliform bacteria were detected at the reporting limit of 1.1 MPN/100 mL in the August 2008 sample retrieved from the Hall well. Fecal coliform organisms were nondetect. The sporadic presence of coliform bacteria can be due to sample contamination at the time of collection, L the introduction of coliform bacteria to the well structure during well and pump maintenance work,or the detachment of bacterial biofilm from the well structure in combination with naturally occurring coliform organisms. I- L I. L L L L ©WHDORFF&SC LMANINI on — n —1- 1E[— 7 L