Laserfiche WebLink
<br />Revision Permit C-81-071 <br />Page 2 <br /> <br />The pH meter is calibrated prior to use each day and typically recalibrated <br />every fourth or fifth sample throughout the day. The EC/Temp meter is <br />calibrated at the beginning of each day. The probe is replatenized annually. <br />In reference to the Oz meter it is calibrated daily prior to use. Finally, <br />the peristalic pump is rinsed between each sample and filters are replaced <br />after each sample. <br />Laboratory Analysis - I have attached a list of the methods used by the <br />laboratory to analyze water samples. The laboratory is given the option of <br />using any method it wishes, as long as accepted methodologics are utilized, <br />i.e., Standard Methods, EPA or ASTM Methods. <br />Surface Water Sampling <br />Flow measurements - Staff gauge readings are obtained for each sampling <br />upside. Discharge measurements are taken periodically duing the summer to <br />verify the rating curve for each station. Based upon this information the <br />rating curve is adjusted accordingly. At the USGS station the USGS is <br />responsible for all measurements and establishment of stage discharge <br />relationship. <br />Sampling - For weirs, flumes and discharge points sample bottle is moved <br />laterally across flow until sample bottle is filled. At other points, dip <br />samples are obtained. <br />Field Equipment and Calibration - Same procedures as discussed for groundwater <br />sampling are followed for the appropriate parameters. <br />Laboratory Analysis - The same options are given to the lab as described for <br />underground water sampling, except for NPDES discharge points that require low <br />level detection limits for certain parameters. Then the lab is advised that <br />the methods must allow detection to the prescribed limit. As we have <br />discussed in the past, there are certain parameters (silver and mercury) that <br />present analytical problems in that their detection limits are set too low. <br />Until further advances are made in the analytical field everyone will have to <br />live with the problem. <br />I will look forward to receiving your comments. <br />Sincerely, <br />Richard Mills <br />Senior Environmental Engineer <br />RAM/jg <br />Attachment <br />