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2. PROCEDURES 2.1 General Monitoring well development shall be performed, as soon as practical, after well installation, but not sooner than 72 hours following placement of the grout seal. Monitoring well redevelopment should occur if a monitoring well planned for sampling exhibits 20% or more of the monitoring well screen blocked by sediments. Well development and redevelopment will consist of a combination of bailing, surging, and pumping. First, a bailer will be utilized to remove any accumulated sediments from the bottom of the well. Then, a surge block will be used to flush the filter pack of fine sediment and to agitate the formation and the filter pack around the well screen. Following bailing and surging, purging will be performed with a submersible pump. The pump will be set in the middle of the well screen or in the middle of the standing water column. The pump will be brought up and down across the screened interval periodically while pumping. Groundwater quality parameters (temperature, pH, specific conductance, and turbidity) will be measured during the purging. Monitoring well development will continue until the development water appears to be free of fines (from filter pack or well screen) and groundwater quality parameters (temperature, pH, specific conductance, and turbidity) have stabilized for three consecutive readings according to the following criteria. • ±10% for temperature; • ±0.1 units for pH; • ±3% for specific conductance; and • Turbidity is less than 50 NTU or±10%. Effective and efficient well development is possible only when a monitoring well is able to yield a adequate flow rate. Groundwater monitoring wells may be installed in water bearing zones that do not convey water readily. In these cases, a groundwater monitoring well may dewater during bailing or pumping. If a groundwater monitoring well dewaters during development, the well should be allowed to recharge before continuing the well development. Water shall not be added to the well to aid in development. A well is considered fully developed when all the following criteria are met: • the sediment thickness remaining in the well is less than one percent of the screen length; • the total volume of water removed from the well equals five times the standing water volume in the well (including the well screen and casing plus saturated annulus, assuming 30 percent porosity);