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1.0 INTRODUCTION On behalf of Nutrien Ag Solutions, Inc(Nutrien),Rubik is submitting this Monitoring Well Network results are shown on Figure 7 and historical groundwater analytical results are summarized in Replacement Work Plan for the s,facilityIna located at ubik i South Highway 33 Monitoring Vemalis,Well aliforniaNetwork Table 3. Graphs comparing CDC concentrations overtime are included as Appendix A. (site, Figure 1). This work plan was requested by the Central Valley Regional Water Quality 5.0 PROPOSED MONITORING WELL DESTRUCTION AND INSTALLATION Control Board(RWQCB)during their April 8,2020 meeting with Nutrien. 1.1 Objective The current monitoring well network will be destroyed and replaced wlth wells installed to 65 feet bgs.The proposed monitoring well network modifications are summarized below and shown on The objective of this project is to replace the monitoring wail network at the site due to declining Figure 8: groundwater levels in the current wells. • Well destructions:MW-1,MW- 2,MW-3,MW-4, MW-5,MW-6R,MW-7,and MW-B 1.2 Chemicals of Concern • Well installations:MW-2R, MW-3R,MW4R,MW-SR,and MW-BR The primary chemicals of concern (COCs) in groundwater are nitrate, 1,2-dichloropropane WellMW-1 standardswilll notell beis replaced because luded in theconcentrations n Redont'andsamplingam historicallybelow water quality (1,2-DCP),and 1,2,31richloropropane(1,2,3-TCP). not needed to evaluate the groundwater Flow direction.Additionally,wells VW-6R and MW- 7 will g Program,and the well is 2.0 SITE DESCRIPTION not be replaced because the proposed well MW-2R i will provide representative data at the same location. The site is used for sales of bulk liquid and dry fertilizers and liquid pesticides and prepackaged fertilizers and pesticides. Current and former she features are shown on Figure 2. 5.1 Permitting 3.0 GEOLOGY AND HYDROGEOLOGY Well installation and destruction permits will be obtained from the San Joaquin County Environmental Health Department (SJCEHD) prior to the start of field work. Encroachment The soil beneath the site consists primarily of day from the ground surface to approximately 25 permits will also be obtained from SJC for the replacement of wells MW-5 and MW-8 along Welty feet below the ground surface (bgs).The day is underlain by discontinuous layers of sand,silt, Road. Rubik will notify the SJCEHD and RWQCB at least 48 hours prior to the field work and day to at least 75 feet bgs,the maximum depth explored. Cross section path locations are S•2 Health and Safety Plan shown on Figure 3 and geologic cross sections are included as Figures 4 and S. A siteing subcontractors, Health and Safety Plan(HASP)will be reviewed and signed ti all field personnel, Site monitoring wells are installed to between 45 and 50 feet bgs with between 20 and 24 feet of inducting subcentrectors,priorto work initiation.The HASP will identify potential health and safety feet bgs, Groundwater elevations have decreased approximately 15 feet since approximately and wells HASPhazards will each phase ofonsite work include requirements and procedures ant plan The HASP will be maintained R id will during the field d included q traffic management plan for work M W4, MW-5, and M W-7 have been dry since 2018. The water column height in the wells that performed along Welty Road will be developed and indutled in the SJC encroachment permit. contained water in February 2020 ranged from approximately 1 to 6 feet. Groundwater 5.3 Utility Clearance ast at an Monitoring well locations tare shoy flows wn on the eF gore 2 and wnge strraudion details dient of 06 summarized in foot( ) Underground Service glert(USA)wili be ies.A notified minimum Dior hours in advance ofsubsurta l Table 1.Historical groundwater elevation data are provided in Table 2 and groundwater elevation activities urvey in to identify underground drilling Jes.A private ity locator allll also perform a geophysical contours from the February 2020 event are shown on Figure 6. Graphs depicting the depth to survey in the vicinity of each drilling location to identify groundwater overtime in the wells are included as A obstructions. If facility potential utilities or other subsurface Appendix A. ty personnel, data from previous borings, and/or the utilityvanedcleara to contractor are unable to verify a location is utility afree, a hand auger will be advanced to 4.0 ENVIRONMENTAL BACKGROUND approximately Sfeet bgs prior to drilling to manually dear the location. Groundwater beneath the site has been monitored and sampled since 1997. Concentrations of 6.4 Monitoring Well Destruction the COCs in groundwater beneath the she have historically exceeded their respective MCLs in The well casing and annular seal will be destroyed by overdrilling to 2 feet belowthe constructed some of the wells,including wells that have gone dry.The February 2020 groundwater analytical depth using a hollow stem auger drilling rig in accordance with SJCEHD requirements, The resulting annular space will be sealed using neat cement delivered through a tremie pipe from the Nutden Vemalis,California t Monitoring Well NehaoA Replaceman,WOA plan Ru.�i i(t Nutrien Vemalis,Ggkmia g Monitoring WNl NalWgk Replamment WOA Plan Q"4