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' Ground•Monitor Well Installation Work Plan City of Manteca Wastewater Treatment Facility ' Page 3 A filter pack of No. 3 Monterey sand will be placed in the annular space to approximately 2 feet above the screens while the augers are in place. The depth of the sand in the annulus of the well will be ' monitored with a clean weighted tape measure while the sand is being placed and the augers are being gradually retracted to avoid bridging. To form a protective seal, approximately 2 feet of bentonite chips will be installed above the sand in the well. The bentonite chips will be installed as the augers are ' retracted. The bentonite will be hydrated using potable water. A surface seal of neat cement will be placed in the annulus of the well and will extend from the bentonite to the ground surface. The monitor well will be completed with a locking, monument-type protective structure. The ground surface around the well will be completed with a 2-foot by 2-foot by 4-inch concrete pad. Four crash posts will be installed to protect the well head. Well completion details recorded on logs will include the type of screen and casing, depth intervals of the screen, blank casing, sand pack, bentonite seals, surface seal, and the quantities of materials added to the annular spaces. A diagram of the proposed monitor well construction is shown on Figure 3. ' 5.3 MONITOR WELL SURVEYING Following installation of the monitor well, a survey of the location and elevation of the well collar, will ' be completed. The well collar will be surveyed with a vertical precision of 0.01 foot referenced to NAVD88 vertical datum and horizontal accuracy of 1.0 foot referenced to California Coordinate System Zone 3, NAD83 horizontal datum. The measuring point for water-level measurements will be marked on the well collar. Ground surface elevation at the well will be recorded to the nearest 0.1 foot by measuring down from the measuring point. 5.4 MONITOR WELL DEVELOPMENT After the well is completed, the well will undergo initial development by bailing and pumping for approximately 1 hour or until field parameters (electrical conductivity and temperature) stabilize and the ' discharge water is relatively clear. Development water will be discharged to the ground surface near the well. The time, method of development, amount of water purged, purge water discharge location, and other field notes related to purging activities at each well will be recorded and retained for inclusion in ' the report. A dedicated submersible pump will be installed for the collection of future groundwater samples. Following initial development and placement of the dedicated pump the well will undergo disinfection to assure that no coliform bacteria were introduced to the well from the sandpack or during well completion. Well disinfection will follow the standard operating procedures (SOP) written for the Lawrence Livermore Laboratories for monitor wells that will be sampled for coliform bacteria. A copy of ' this SOP is included in Appendix A. The disinfection procedure uses chorine bleach as the disinfectant. The disinfected well will be purged until residual chlorine is no longer detected. 6.0 REPORTING Ag roundwater monitor well installation report will be submitted to the City. The report will include: (1) project background information, (2) a description of the fieldwork conducted at the site, (3) a scaled site plan, (4)a drilling log, (5)conclusions, and(6)recommendations. The report also will include a geologic log and an as-built construction diagram for the monitor well. Information provided will include the ' calculated and actual volumes of the filter pack and annular seal materials used in the well installation and the surveyed reference point elevation for the well. ' CONDOR