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Appendix B- Historical Water Levels City of Lathrop <br /> Consolidated Treatment Facility <br /> Monitoring and Reporting Program R5-2016-0028-03 Rev 3 <br /> M W M-23 <br /> Measuring Point NGVD 29 NAVD 88 <br /> MP 1 10.94 13.33 <br /> MP 2 5.97 8.36 <br /> Groundwater Groundwater <br /> Date Sampled DTW(ft) Elevation Elevation <br /> ft NGVD 29 ft NAVD 88 <br /> 5/3/2021 9.12 -3.15 -0.76 <br /> 10/18/2021 6.34 -0.37 2.02 <br /> 4/29/2022 7.23 -1.26 1.13 <br /> 11/9/2022 5.98 -0.01 2.38 <br /> 3/24/2023 3.25 2.72 5.11 <br /> Abbreviations: <br /> DTW=depth to water <br /> ft=feet <br /> MP=measuring point <br /> NAVD 88= North American Vertical Datum of 1988 <br /> NGVD 29= National Geodetic Vertical Datum of 1929 <br /> Notes: <br /> (a) MP 1 elevation surveyed by MacKay&Somps,July 2005. MP 2 elevation surveyed by Associated Engineering Group,August 2012 <br /> following modifications to the top of the well casing.Groundwater elevations calculated from depth to groundwater measured <br /> before August 2012 are calculated using MP 1 and after August 2012 are calculated using MP 2. <br /> (b)Surveyed elevations referenced to NGVD 29 and converted to NAVD 88 by adding 2.39 ft. Datum conversion factor determined <br /> from National Geodetic Survey Vertcon website and is an average for the area. (www.ngs.noaa.gov/TOOLS/Vertcon/vertcon.html) <br /> (c) Open marker indicates questionable water level measurement. <br /> EKI Environment&Water, Inc. <br /> July 2023 Page 56 of 145 EKI B9O088.03 <br />