ARCHIVED REPORTS_XR0012617 - Laserfiche WebLink

Home Browse Search

NO WN1 A,6,2 Presampling Measurel"Cuts Prior to purging and saillpling of each well, the depth to standing water and the total depth of the well are illcasured with a decorlultninated optical interface probe. A decontaminated,clear acryl- ic bailer is then inserted into the well to just below the static water level and removed to c.onfinu the presence/absence of any floating product. 'these presample measurement data are recorded on a Record of Well Gauging and Purging and used to calculate the volume of standing water in well (one well casing volunlc), Measurements are made to the nearest 0.01 foot and refer- tilecnced to the permanent surveyed reference point on tklc well casing. A.6.3 Well Purging - To ensure that the sample collected is as representative as possible of groundwater in the aquifer, standing water in the well and the surrounding sand pack is purged. Between four and six casing volumes of well water are purged to ensure that rill stagnant water has been removed. The well is purged with submersible,airlift,or surface pumps or bailers,decontaminated as described above in Section A.6.1. Should the well pump dry after the casing is initially dewatered, purging is discontinued and the well allowed to recover. purging is continued to obtain the desired purge volume. Field parameters of l-1-1, temperature, and electrical conductance are measured as the well is purged. Measurements are taken and recorded approximately every five gallons. If any of the three field parameters has not stabilized by the time the 4-6 casing volumes have been purged, additional well water is pumped until the parameters have stabilized (but no more than 10 casing volumes). "Stabilized" is defined as it reading less than 10 percent of a previous reading. All purge water is contained in 55-gallon drums labeled with well number,du,,-, contents, and facility identification. After the well has been purged of the required volume of water,the purg- ing equipment is removed. A Teflon sampling bailer is used to collect four separate samples for presample field parameter measurements, to confirm field parameter stability and, therefore, representative aquifer samples. A.6.4 Well Sampling All samples are collected with a'1'eflon bailer cleaned as discussed in Section A.6.1. The bailer is operated by hand on a new, 114-inch polypropylene rope or on Teflon-coated stainless steel wire. The saillpling persoilnel wear clean Nitrile gloves during sampling operations and while handling sample bottles. - The collected groundwater samples are emptied from the bailer with a bottom-emptying device directly into the sample bottles. The samples are collected in either 40-m1 glass VOA vials or A-4 i