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Frontier Transportation, Inc. B23502.01 October 16, 1996 Page A-4 each groundwater monitoring well, and a 3-foot steel standpipe with locking cover or a traffic-rated box is installed around the wellhead. Nlonitoring wells are locked to restrict access to unauthorized personnel. Monitoring well construction details are recorded on the field well construction form. Construction information is transferred to Monitoring Well construction schematics for presentation in final reports. A-4 Standard O 3eratina Procedures for Groundwater Monitorin Well Development: When possible, initial Weil development is performed during installation of the sand pack. A minimum of 48 hours following installation, groundwater monitoring wells are developed in order to remove sediment that may accumulate in the well during installation, and to settle the filter pack. Groundwater monitoring well development is ' performed using a combination of either bailing, pumping, and surging. The development of each groundwater monitoring well continues until a minimum of five well casing volumes of water have been removed, and the displaced water is relatively clear, free of sediment, and the values of Ph, temperature, and specific electrical conductance (EQ have stabilized. Well development data is recorded on the Well Development Log-. Purged water is containerized in Department of Transportation-approved drums, and stored on site in an area inaccessible to the general public. The purged water is typically characterized either by sampling it, or on the basis of the groundwater sample analytical results. Twining can recommend an appropriate method for disposition of the purged water. Disposal will be the responsibility of the client. A-5 Standard Operating. Procedures for Groundwater Monitoring Well Sam lin Groundwater sampling is performed a minimum of 24 hours following development, or when the past-development water level in the well has returned to the static level. Before purging and sampling is performed, the depth to water and the total well depth is measured. If floating hydrocarbons are suspected, a bottom-filling clear bailer or hydrocarbon-detecting paste bailer may be used to record floating hydrocarbon thickness. Depth to water is measured with an electric sounder, according to Twining's "Standard Operating Procedures for Measuring Depths to Water and Calculating Groundwater Elevations". Prior to sampling a monitoring well, a minimum of 3 well casing volumes is purged using a clean, stainless steel submersible pump or a disposable bailer equipped with a length of new rope. Disposable bailers and rope lengths will be used once, and discarded. After 3 casing volumes of water have been removed from the well, purging continues until measured field parameters (Ph, specific electrical conductivity, and temperature) have stabilized. Pur,in_ data is recorded on the Well Sampling log.