Laserfiche WebLink
MBR <br /> We utilized reported quarterly water level data to calculate and contour average <br /> 2003 groundwater elevations in the vicinity of the City of Lathrop's Water <br /> Recycling Plant No. 1. The contours show inferred average 2003 groundwater <br /> gradients and flow directions up and down gradient to the MBR Wastewater <br /> Treatment Plant (see the attached revised Figure 2c). In general, shallow <br /> groundwater flows to the west, toward the leaky stormwater drain located east of <br /> 1-5. We utilized Figure 2c (revised) to justify/revise the MBR (Phases I and II) <br /> monitoring well locations and monitoring objectives. The well locations are <br /> shown on the attached Figure 6c (revised), and the monitoring objectives are <br /> summarized in Table 4 (revised) below. <br /> Table 4 revised).Construction information and objectives for Pond 3MBR and Storage Basin E. <br /> Map ID Screened <br /> (Locations Old Well Status' Diameter Depth Interval Monitoring Objective' <br /> shown in ID (inches) (feet) (feet) <br /> Fi ure 6c <br /> KMW-4 KMW-4 E 4 25 10-25 Up gradient Basin E. <br /> MBRMW-1 N 4 32.0 15-30 Down gradient Basin E. <br /> MBRMW-2 N 4 32.0 15-30 U gradient Pond 3MBR. <br /> MBRMW-3 N 4 32.0 15-30 Down gradient Pond 3MBR. <br /> MBRMW-4 N 4 32.0 15-30 Down gradient Basin E. <br /> 1: E=existing,and N=new. <br /> 2: Locations relative to present-day flow directions shown on Figure 2c(revised). <br /> 4) Employ a 10-inch auger to prevent possible sand bridging when installing the <br /> filter pack. <br /> The drilling rigs scheduled for well construction shall utilize 10-inch augers. <br /> 5) Maximize the cement well seal-especially in wells located within disposal <br /> fields. Revise Figure 7 to show well monument style wellhead cover. <br /> Well construction plans have been modified to increase the cement well seal 3 to <br /> 5 feet, corresponding to a final seal thickness of 8 to 10 feet thick. Actual well <br /> seal thickness shall be determined on a site-by-site basis employing one or a <br /> combination of the following: shortening the sand filter pack above the well <br /> screen (original proposed thickness of 3-feet); shortening the well screen <br /> (original proposed length of 10-feet); and shortening the well sump (original <br /> proposed length of 2-feet). The actual design modifications shall consider water <br /> table depth and historical seasonal variations in groundwater levels. <br /> Figure 7 was revised to show the well monument style wellhead cover, which is <br /> provided as an example of proposed monitoring well design. Additional design <br /> information for above and below ground well completions is provided in narrative <br /> form within the April 18, 2005 workplan; Attachment F ("Requirements for Well <br /> - 8 - <br />