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Testing, Sampling, and Analysis Plan <br />January 15, 2025 <br />8 <br />Zone 7 Water Agency and <br />City of Pleasanton <br />5.1. Depth-to-Water Measurements <br />1. A static depth-to-water reading shall be obtained prior to turning on the well pump. <br />2. An electric water level sounder shall be used in accordance with the manufacturer’s instructions to <br />obtain a depth-to-water measurement from a specified reference point (i.e., top of sounding tube, <br />top of well casing, etc.). The sounder shall have a 0.01-foot graduation to support direct readings with <br />a resolution of 0.01 feet. The reading shall be taken in duplicate or more to ensure that an accurate <br />measurement is obtained and recorded. <br />3. The static water level, in conjunction with well construction information, well used to calculate the <br />volume of water in the test well. This information will used to determine the minimum volume of <br />water to be purged prior to sample collection (i.e., a minimum of three wet casing volumes). <br />5.2. Purging Protocol <br />1. Wells are to be purged and sampled using the dedicated sampling port on the temporary well pump. <br />2. Wells are to be purged of a minimum of three wet casing values and, <br />3. Wells are purged until indicator parameters stabilize. Stabilization is defined as consecutive readings <br />at approximately 5-minute intervals, where parameters do not vary more than 5 percent between <br />readings. <br />4. The following indicator parameters are monitored during the well purging: <br />b. temperature (°C) <br />c. pH (standard pH-units) <br />d.ĞůĞĐƚƌŝĐĂůĐŽŶĚƵĐƚŝǀŝƚLJ;ʅ^ͬĐŵͿ <br />e. dissolved oxygen (percent saturation or mg/L) <br />f. oxygen reduction potential (mV) <br />g. turbidity (NTU) <br />2. Visual (color, occurrence of solids), olfactory (odor) and other observations (e.g., wellhead <br />conditions, well access, ground conditions, weather) are noted as appropriate. <br />3. Purge water shall be disposed of according to project specifications. <br />5.3. Sample Collection <br />1. Upon completion of purging activities, sample containers shall be filled such that the designated <br />sample tap or container does not come into contact with the sample container. <br />2. The sampler shall not touch the inside of the lip or the inside of the sample container. <br />2. The cap of the sample container shall never be laid down and shall be held facing down to minimize <br />particles settling inside the cap. <br />3. The sample container shall remain closed until the sample is ready to be retrieved. <br />4. The sample container shall not be allowed to overflow. <br />5. The sampleshall not come into contact with any other surface prior to entering the sample container. <br />6. The cap is closed without delay to minimize exposure to potential contaminants.