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(YVATC <br /> ! <br /> A S S O C 1 A T E S I N C <br /> Analyses for CrVI will be performed by PRIMA Environmental using the diphenyl carbazide method, <br /> which has a detection limit of 0 01 mg/l If the bench scale test results indicate complete reduction of CrVI <br /> by both reductants,then the choice of reagent depends upon secondary issues such as effect of treatment on <br /> secondary water quality, including possible need for post-treatment injections, ease of implementation (e g <br /> number of injection points, need for odor control or pH adjustment), and cost. <br /> Remedial actions will be evaluated upon review of the bench scale testing If the soul samples collected from <br /> below Vault 8 are not impacted with CrVI, it is possible that a pump and treatment action with discharge to <br /> the municipal sewer system under DWG's permit will be proposed for the affected groundwater m lieu of <br /> injection. If injection is proposed, monitoring wells MW-5 and MW-6 will be used as downgradnent <br /> monitoring points for degradation products and byproducts of the reduction reactions Additionally, <br /> extraction from downgradient morutonng well MW-6 will be proposed as a contingency measure to contain <br /> the migration of the CrVI groundwater plume <br /> SCHEDULE AND REPORTING <br /> Once approval of this workplan has been received, ATC will obtain permits from San Joaquin County <br /> Environmental Health Department (EHD) and confirm a schedule for drilling activities ATC will <br /> notify the CRWQCB and EHD at least 48 hours prior to beginning any field activities A summary <br /> report will be prepared for submittal to the CRWQCB approximately seven weeks after the completion <br /> • of field activities and will include a description of the field activities, laboratory analytical results, and <br /> conclusions and recommendations A copy of the report will also be submitted to EHD <br /> If you have any questions or require additional information regarding this workplan, please contact us <br /> at(209) 579-2221 <br /> Respectfully submitted, <br /> ATC Associates Inc <br /> yANtY <br /> Todd Haffner � �; ' Y, <br /> Project Geologist =` <br /> ' L <br /> Jae Homsey,P E ,�' <br /> Registered Engineer No C47410c;la � <br /> t ti <br /> Attachments " ' ° <br /> cc Mr Mike Lescisin, Diamond Walnut Growers <br /> Mr Mike Infurna, San Joaquin County Environmental Health Department <br /> 0 <br /> sleawonmenta11625831reports\RewsedWKP-Bench test doc 7 <br />