ARCHIVED REPORTS XR0001834 - Laserfiche WebLink

Home Browse Search

'7 • APPENDIX 1 Groundwater Monitoring Procedures 10 GROUNDWATER SAMPLING PROTOCOL All equipment that is used in a monitoring well for purging,sampling or depth measurement shall be decontaminated by steam cleaning or a TSP wash and triple-rinse procedure prior to use and before reusing when purging or sampling 1 Each monitoring well is opened and allowed to equalize to atmospheric pressure prior to to sounding This time will be approximately %z hour Each well will be accessed and the wellhead checked for damage and tampering 2 The first well to be monitored will be known or suspected clean wells The next wells to be monitored will be known or suspected wells that will contain contaminated groundwater The furthest up gradient contaminated well will be monitored first Subsequent wells will be monitored on a down-gradient basis 3 The depth-to-groundwater will be measured from the predetermined measure point on the well casing with a sounding tape and recorded to the nearest 0 01 foot In most cases the measuring point is the survey mark on the top of the well casing The time,day and other observations will be recorded in a notebook The tip of the probe will then be examined in order to determine the presence or absence of product sheen If a product sheen is detected or the well is known to have been previously identified as having petroleum hydrocarbon contaminated groundwater then prior to purging, a clean,transparent bailer is lowered into the well,and a sample of groundwater is hoisted to the surface The sample fluid is inspected for the presence of free-floating product on its surface • 4 The depth probe is then weighted and the bottom of the monitoring well is determined and recorded A calculation of the water contained in a single well casing volume will be made 5 Sampling activities conducted subsequent to the initial water level and free-product layer determination will be preceded by purging a minimum of three to five well-volumes by hand-bailing or the use of an electrically-operated pump If a pump is used,the pump will be placed in the wellbore no more than five feet below the groundwater surface and the purging rate will be controlled so as to not allow the groundwater surface to decline more than two feet from the initial measurement These restrictions are to ensure that waters coming into the wellbore are representative in chemistry from the surrounding aquifer and are being extracted from the approximate depth of the groundwater surface and not from cascading water entering the wellbore filterpack from depths significantly below the top of the groundwater surface A well is allowed to recharge to at least 80%of its prepurge groundwater surface elevation prior to sampling The purging rate will not be so great as to cause the well to go dry or have the formation water cascade down the casing If purging causes the well to be pumped dry,it will be allowed to recharge for up to 24 hours prior to sampling If the well does not recharge within 24 hours,it will be considered to be a dry well 6 Purge water will be monitored for the parameters of temperature,pH,and electrical conductivity until stabilized The groundwater temperature,pH and electrical conductivity will be measured with field instruments and recorded in a notebook If required by regulatory agencies, field readings for dissolved oxygen(d-02), displayed to the nearest tenths of parts per million,will be obtained utilizing a YSI Model 50B or Hanna Instruments hand-held, HI-9142,Portable Dissolved Oxygen Meter or an equivalent device Generally, (d-OZ) higher concentrations are expected in samples which exhibit no impaction or are marginally impacted by hydrocarbons than for samples collected from monitoring wells which yield hydrocarbon-impacted water Maln\D\.nvironmenta[\ParmarTexaco\Reports\041403QMR wpd