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VI spool in a large stainless steel barrel of soap and water and then thoroughly rinsed. . Once all the wells have been sounded, the appropriate purging equipment is then determined to complete the necessary tasks required at each purging / monitoring point. In the case of dedicated purging and sampling systems this is not an issue. However, the dedicated system at the well head is inspected for it's integrity and operational status to produce a representative sample. Prior to beginning the monitoring well purging and sampling event, all field equipment used during the event is steam cleaned and stored inside of individual clean containers. New Nitrile gloves are worn during the time the monitoring and sampling tasks are completed. After completing the tasks at each sampling point the gloves are changed and disposed of so that no possible outside contamination can come into contact at the next sample location. At each sample point they are also changed routinely if there is any question of possible outside contamination contact has occurred. No purging, monitoring or sampling equipment will be used at the next sample point until each piece has been thoroughly cleaned and decontaminated. Each one of the wells are then purged at a steady flow rate. Our goal is to not over-stress or draw down the water formation within the well casing and to establish a smooth lateral flow through the 1 well screen interval. Dependent on geological conditions, the ability of the well to recharge is usually unpredictable, however the techniques used for purging can skew the field monitoring results and possibly the laboratory results. Each well is purged for a proposed minimum of three calculated casing purge volumes. Purge volumes are determined by subtracting the standing water level from the top of casing from the total depth.. The standing water column is then multiplied by the correct multiplier that is relevant to the well casing diameter. i.e. ( 85 .33 feet depth to water - 100.00 feet total depth = 14.67 feet standing water column X . 1632 for a two inch well or .6528 for a four inch well = 2.39 gallons of standing water would be inside a 2"well casing.) The multiplier is changed accordingly in respect to the well casing diameter. Del-tech has many different types of purging and pumping systems in our inventory. Each of these systems have a unique characteristic that will perform the purging tasks with the greatest effectiveness for each wells unique condition. The type of system used during these monitoring events will be logged on the Del-Tech monitoring well field log. Occasionally, one type of purging system will not do the job as well as another type of purging device. In the case of dedicated systems this determination of proper purging devices is usually not an issue and has been predetermined. However, dependent on the exposure to the naturally occurring elements or chemical consistuents at any given sampling location, dedicated units have shown to be vulnerable to the elements. In some cases the dedicated unit has become almost a sacrificial anode and been destroyed. In those situations we carry backups for the dedicated units in the field. During the purging of the well the sample integrity is always considered. We attempt to purge the well without stressing the subsurface static conditions. As each well casing volume is removed the pH, temperature, conductivity, turbidity and odor is monitored. A laboratory grade Y.S.I. 556 muli- Del -Tech Geotechnical Support Standard Operating Procedures / Groundwater Monitoring 2004