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Windsor East Sand and Gravel Mine; Martin Marietta Materials <br />June 2022 <br /> Page 1 | 4 <br />ATTACHMENT G-3: GROUNDWATER MONITORING AND SAMPLE COLLECTION PROCEDURES <br />1.1 SCOPE AND APPLICATION <br />The purpose of this Standard Operating Procedure (SOP) is to provide guidance for determining the depth to <br />water in a well using an electronic water level indicator. In this SOP, wells are defined as monitoring wells, <br />piezometers, temporary well points, and potable wells. Permanent wells should be surveyed such that wells can <br />be located and water elevations can be determined. At sites where there are multiple wells, a complete round of <br />water level measurements should be collected site-wide prior to commencement of activities that will affect <br />groundwater levels. <br />A permanent survey mark should be placed on the top of the well casing (TOC) as a reference point for <br />groundwater level measurements. If the lip of the riser pipe/well casing is not flat, a notch can be made on the <br />polyvinyl chloride (PVC) riser and used as the reference point. Alternatively, the reference point may be located <br />on the top of the outer protective casing (if present). If using a measurement reference point, it must be <br />documented in a site-specific logbook or on a field data sheet. All field personnel must be informed of the <br />measurement reference point used to ensure the collection of consistent data. <br /> <br />1.2 WATER-LEVEL MONITORING <br />An electronic water-level indicator is used to measure the depth to water in each well. The indicator consists of a <br />wired cable with a probe at the end. When the probe contacts water, the water completes a circuit causing the <br />indicator to emit a sound at the surface. The water-level indicator should be turned on, then lowered until the <br />probe emits a tone indicating contact with water. The distance from the water surface to the TOC should then be <br />recorded using the gradational scale on the cable. The water level measurement should be recorded on a water- <br />level monitoring field form or notebook, then the measurement should be repeated to confirm the reading. All <br />measurements should be recorded to one hundredth (0.01) of a foot. It is important to record the date and time of <br />each measurement along with the well identification and the depth-to-water value since water levels can vary over <br />time. Water level measuring equipment will be cleaned of visible water and particulate matter prior to and after <br />use at each measuring location via wiping/rinsing. <br />The groundwater elevation can then calculated by subtracting the depth-to-water measurement from the surveyed <br />TOC elevation. <br /> <br />1.3 WATER QUALITY SAMPLE COLLECTION <br />The procedure for collecting a water quality sample involves the use of a pump or bailer to remove three well- <br />volumes of water from the well to ensure that the water remaining is representative of aquifer water, then to use <br />the pump or bailer to pass samples of water through a filter to remove suspended particles and collect the filtered <br />sample in a bottle. <br />1.3.1 Well Purging <br />An adequate purge is normally achieved using this method by removing three well volumes of standing <br />groundwater at relatively high flow rates prior to sampling while recording the pumping rate, discharge volume, <br />water level and routine groundwater parameters over time. Routine groundwater parameters should include <br />temperature, pH, and specific electrical conductance at a minimum, but may additionally include turbidity. It is