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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-24 <br /> Measuring Point NGVD 29 NAVD 88 <br /> MP 1 10.38 12.77 <br /> M P 2 14.49 16.88 <br /> Groundwater Groundwater <br /> Date Sampled DTW(ft) Elevation Elevation <br /> ft,NGVD 29 ft,NAVD 88 <br /> 11/5/2020 13.93 0.56 2.95 <br /> 5/4/2021 13.02 1.47 3.86 <br /> 10/18/2021 13.97 0.52 2.91 <br /> 4/29/2022 13.73 0.76 3.15 <br /> 11/8/2022 12.99 1.50 3.89 <br /> 3/24/2023 10.60 3.89 6.28 <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 MacKay&Somps,August 2010 following <br /> modifications to the top of the well casing.Groundwater elevations calculated from depth to groundwater measured before <br /> August 2010 are calculated using MP 1 and after August 2010 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 /> EKI Environment &Water, Inc. <br /> July 2023 Page 58 of 145 EKI B90088.03 <br />