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' May 2014 Groundwater POC Update Memorandum♦6 <br /> ' The water level measurements collected from 3-Dam monitor wells support the following <br /> conclusions: <br /> ' • Continuous groundwater is observed at only one monitoring location east of 3-Dam <br /> (MLGW-17). Groundwater at this location occurs in a 20 to 30 foot zone near the <br /> ' base of Qd sediments. <br /> • At all other locations, groundwater occurs within Qd sediments intermittently, <br /> primarily in response to late Spring/early Summer snowmelt events. Water at these <br /> locations is not interpreted to represent a laterally extensive aquifer system. Rather <br /> ' the appearance of water at these locations is intermittent and is interpreted to <br /> represent pulses of water infiltrating the shallow Qd sediments during Spring and <br /> ' Summer months. <br /> • Since no laterally extensive aquifer system is indicated it is not possible to measure <br /> ' hydraulic gradients and calculate groundwater flow direction. Our interpretation is <br /> that flow direction is primarily controlled by the slope of the Qd/bedrock contact, <br /> ' which is northeasterly based on drill logs of the completed monitor wells. Measured <br /> groundwater elevations at the shallower MLGW-20 are consistently higher than <br /> ' elevations at the deeper MLGW-17, suggesting a perched aquifer at MLGW-20 and <br /> downward flow gradients. <br /> ' 4.3 WATER QUALITY SAMPLING <br /> ' Quarterly groundwater sampling events were completed for MLGW-17 and MLGW-20 <br /> beginning in December 2012. Five water chemistry samples were collected from N LGW-17 <br /> ' and three samples were collected from MLGW-20 when sufficient water was recorded in the <br /> monitor well (after May 2013). Time-series charts for indicator parameters chloride, sulfate, <br /> manganese, and pH are presented in Figure 10 to Figure 13 and water quality data is <br /> presented in Table 2. The following is a summary of analytical results from water chemistry <br /> ' samples collected from MLGW-17 and MLGW-20: <br /> Concentrations in wells MLGW-17 and MLGW-20 are below the numeric <br /> ' protection limits (NPLs) as set forth in the DRMS-approved GWMP. <br /> 1 <br />