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' Work Plan Page 17 Former Manna Pro Site ' Project No 207 3 August 16, 1999 ' a sleeve, or a water sample may be collected through a screen The probe is then withdrawn and the sample is conveyed back to the surface ' 6.2 Groundwater Sample Collection ' 6.2.1 SimulProbe The SimulProbe can be used to collect in-situ groundwater samples A soil sample is ' collected by hammering the SimulProbe into the formation at the base of the boring The rods are then pulled back to retract the sliding drive shoe and expose the screen between the drive shoe and the core Water enters the chamber below the screen and a water level ' sensor alarm sounds when the chamber is full The sample is then retrieved Extreme care must be exercised while collecting samples to prevent agitation of the water contained in the SimulProbe chamber Water samples will be carefully transferred from the SimulProbe into 40 ml VOA vials preserved with hydrochloric acid (provided by the analytical laboratory) All samples will be tapped to check for head space bubbles, labeled, inserted into foam holders and conveyed to the onsite mobile laboratory A chain Iof custody document, listing all samples collected and their intended analyses will accompany the samples a means to track their movement and insure their integrity 6.2.2 Monitoring Well The monitoring wells will be sampled no earlier than 24 hours after development A groundwater sampling event will then proceed as follows The well is unlocked and opened The groundwater level will then be measured in each well before any purging of that well occurs A groundwater level measuring tape with an electronic sensor will be used This tape has an accuracy to the nearest one-one hundredth of a foot If floating product is suspected, then a bailer will be lowered into the well to determine and measure I the thickness of free product at the surface of groundwater The presence of floating product will affect water elevations and sampling protocol The sounding tape will be decontaminated before and between sounding each of the wells Stagnant water in the well casing will be purged using a submersible Grundfus pump The rate of well purging will be monitored Each well will be purged of at least three casing volumes and then purged until the groundwater parameters (temperature, conductivity, and pH) have stabilized indicating that water, representative of actual aquifer conditions, is entering the well Three successive temperature pH and conductivity readings within 10% of each other will be used as the criteria to suggest that representative formation water is entering the well 2937 Veneman Ave,#8240 Geo-Phase Environmental Inc Phone(209) 569-0293 Modesto,CA 95356 Fax(209) 569-0295 I