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September 29, 2014 Monitoring Well Abandonment and <br /> Installation Workplan <br /> Monitoring well KMW-7 (located in LAA 2) shall be destroyed(see Table 1 for construction <br /> information)because water quality and water level data10 indicate faulty construction. <br /> Groundwater beneath LAA 2 is currently monitored by two wells,KMW-3 and KMW-7,and <br /> therefore the data from KMW-7 is redundant. <br /> Table 2 shows the average and range in measured pH for all WWTF and MBR WRP-1 <br /> monitoring wells.The pH in samples from KMW-7 has consistently been outside the typical <br /> range of the pH values from other W WTF and MBR WRP-1 monitoring wells (generally at <br /> least 1 pH unit higher than water from the other wells),and always exceed the interim limit <br /> for pH (6.5 to 8.5 pH units).This high pH indicates the presence of cement grout in or near <br /> the well screen and may influence the water chemistry of samples from the well. <br /> Table . ' � ' � <br /> Well ID Sample Count Min Mean Max <br /> KMW-1 35 6.88 7.07 7.30 <br /> KMW-2 35 6.93 7.17 7.50 <br /> KMW-3 35 6.81 7.33 8.19 <br /> KMW-4 34 6.58 7.02 7.50 <br /> KMW-6 36 6.53 6.84 7.20 <br /> KMW-7 36 8.51 8.98 9.97 <br /> W-1 36 6.62 6.94 7.40 <br /> W-2 36 7.29 7.68 8.00 <br /> MW-5 36 7.00 7.42 7.70 <br /> MBRMW-1 37 6.92 7.52 8.44 <br /> MBRMW-2 37 7.22 7.79 8.40 <br /> MBRMW-3 37 7.27 7,78 8.60 <br /> MBRMW-4 36 7.65 8.06 8.40 <br /> Water levels measured in KMW-7 are consistently higher than the water levels measured in <br /> nearby monitoring wells KMW-3,KMW-4,and MBRMW-4.Contours of median groundwater <br /> elevation shown on Figure 2 were constructed both with and without the KMW-7 water <br /> level data.The groundwater level contours indicate that KMW-7 is likely downgradient of <br /> wells KMW-4 and MBRMW-4,but the water level in KMW-7 is typically higher than in <br /> KMW-4 and MBRMW-4 indicating a water level mound around KMW-7.The apparently <br /> anomalous water level measurements in KMW-7 also suggest a well construction problem. <br /> io City of Lathrop Third Quarter 2013 Groundwater Monitoring Report,Crossroads Wastewater Treatment <br /> Facility.Order No.5-01-251. Prepared by Hydro Focus,Inc.and submitted to the Regional Water Quality <br /> Control Board on October 30,2013. <br /> HydroFocus, Inc. 4 <br />