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Monitoring Well Installation Work Plan White Slough Water Pollution Control Facility ' Therefore, the City's long-term goal for installing the new monitoring well WSM-2R is to replace the function of WSM-2, such that the City could then properly abandon WSM-2. A detailed justification for replacing WSM-2 with WSM-2R cannot be made until sufficient water quality data from WSM-2R are available. Therefore, if this justification is possible based on the data, it will need to be detailed in a later report. Nevertheless, reviewing the nitrate data for WSM-2 is helpful in discussing the rationale for the proposed WSM-2R location. Historical nitrate data (1989-2014) for WSM-2 is shown on Figure 3-1, which also includes historical groundwater elevation data for this well. In addition, because the recycled water from the WPCF is stored in the WPCF ponds prior to irrigation reuse, Figure 3-1 also includes recent (2008-2013) nitrate and total nitrogen (ammonia plus nitrate plus nitrite)data for the ponds. As shown on Figure 3-1, the variability and maximum nitrate concentrations for WSM-2 have substantially changed since about January 2009, when the tertiary improvements were completed. The area around WSM-2 was used for staging during the construction and thus subject to truck traffic and surface pressures that could have potentially damaged the well. The recent maximum nitrate concentrations in WSM-2 are well above both the nitrate and total nitrogen concentrations measured in the ponds. These maximum concentrations in WSM-2 thus appear to be unrelated to the City's irrigation reuse activities. The locations of the City's existing monitoring wells are included on the Site Map (Figure 2-1). As described above, the proposed monitoring well may eventually replace the function of the existing monitoring well WSM-2. Figure 3-2 shows an aerial photograph map of the area around WSM-2 and the proposed location for WSM-2R. The aerial photograph indicates other nearby surface features, including the WPCF ponds (within the scale of the map) and the nearby NCPA power plant facilities. The specific criteria used to determine the location for WSM-2R are as follows: 1. Vicinity to WSM-2: As a potential replacement well for WSM-2,WSM-2R is logically placed near WSM-2. 2. Vicinity to WPCF and Irrigation Areas: Unlike some of the City's other compliance monitoring wells,WSM-2 is not located within an irrigated field but in an adjacent area. The intent of the compliance monitoring wells is to obtain data representing WPCF operations. Therefore,relative to WSM-2,WSM-2R is placed closer to the WPCF ponds and irrigation areas just west of the ponds. The location of WSM-2R is specifically about 70 feet away from WSM-2,north and a little east of it, as shown on Figure 3-2. 3. Avoidance of Overhead Power Lines: The approximate locations of nearby overhead power lines are also shown on Figure 3-2. While a location even closer to the WPCF ponds and irrigated fields might be desirable,these power lines would be a hazard to a drilling rig and thus interfere with construction of the proposed well. WEST YOST ASSOCIATES 3 City of Lodi September 2014 Monitoring Well Installation Work Plan w\c\213\06-14-31\wp\WP\083014_1 R W P