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Well purging devices are selected on the basis of the well diameter and the total volume to be evacuated In most ` cases the well will be purged using an electric submersible pump (i e Grundfos) suspended near (but not touching) the bottom of the well Small volumes of purgewater are often removed by hand bailing with a ' disposable bailer PARAMETER STABILIZATION Well purging completion standards include minimum purge volumes, but additionally require stabilization of specific groundwater parameters prior to sample collection Typical groundwater parameters used to measure stability are electrical conductivity, pH, and temperature Instrument readings are obtained at regular intervals ' during the evacuation process (no less than once per case volume) Stabilization standards for routine quarterly monitoring of fuel sites include the following Temperature is ' considered to have stabilized when successive readings do not fluctuate more than t/- 1 degree Celsius Electrical conductivity is considered stable when successive readings are within 10% pH is considered to be stable when successive readings remain constant or vary no more than 0 2 of a pH unit DEWATERED WELLS ' Normal evacuation removes no less than three case volumes of water from the well However, less water may be removed in cases where the well dewaters and does not recharge ' Wells known to dewater are evacuated as early as possible during each site visit in order to allow for the greatest amount of recovering Any well that does not recharge to 80% of its original volume will be sampled prior to the departure of our personnel from the site in order to eliminate the need of a return visit In jurisdictions where a certain percentage of recovery is included in the local completion standard, our personnel follow the regulatory expectation PURGEWATER CONTAINMENT All non-hazardous purgewater evacuated from each groundwater monitoring well is captured and contained in ' on-board storage tanks on the Sampling Vehicle and/or special water hauling trailers Effluent from the decontamination of reusable apparatus (sounders, electric pumps and hoses etc ), consisting of groundwater combined with deiomzed water and non-phosphate soap, is also captured and pumped into effluent tanks ' Non hazardous purgewater is transported under standard Bill of Lading documentation to a Blaine Tech Services, Inc facility before being transported to an Exxon approved disposal facility (e g Romic Environmental ' Technologies Corporation in East Palo Alto, California) SAMPLE COLLECTION DEVICES All samples are collected using a disposable bailer SAMPLE CONTAINERS Sample material is decanted directly from the sampling bailer into sample containers provided by the laboratory, ' which will analyze the samples The transfer of sample material from the bailer to the sample container Lrpo18 809