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City of Ripon Well#12 Nitrate Study Report May 31,2006 5.2 SGI Sampling of RFS Monitoring Wells As mentioned previously (Section 3.3), the nitrate analysis results from shallow well samples collected by RFS were not consistent between the two laboratories that analyzed the split samples. Because of the uncertainty caused by the inconsistent lab results, SGI sampled these monitoring wells with the intention of conducting additional analyses to evaluate the source of uncertainty in the laboratory results. On March 7, 2005, SGI visited the RFS site to sample wells MW-5, MW-103, and MW-104. SGI also sampled an additional supply well owned by Joe Kamps on the same day. The details of this well sampling event are presented below. 5.2.1 Well Sampling and Analyses Wells MW-103, MW-104, and MW-5 were purged prior to sampling by the following method. At least three well casing volumes of groundwater were removed from each well using a clean submersible pump. During purging, water parameters including pH, temperature, conductivity, and turbidity were monitored using a YSI 556 equipped with a flow-through cell. Groundwater parameters including temperature, electrical conductivity, pH, dissolved oxygen, and oxidation-reduction potential were allowed to stabilize to within 10% for each parameter to ensure that groundwater representative of the aquifer was entering the well. The field sampling sheets for wells MW-5, MW-103, and MW-104 are presented in Appendix A. After purging, the wells were allowed to recharge to at least 80% of their original water levels prior to sampling. Groundwater samples were collected using a polyethylene disposable bailer attached to new string. Samples were decanted into laboratory provided containers, appropriate for the analysis to be performed. The containers were capped, labeled, and placed on ice for transport to JL Analytical Laboratory for analysis. Split samples were given to the RFS consultant for analysis. The following analyses were requested for samples collected in March 2006. • Nitrate as NO3 by chromatography(EPA Method 300), • Nitrates as NO3 by chromatography (EPA 300) where a nitrate spike had been added, and • Nitrates as NO3 by selective anode probe (SM 4500D). 5.2.2 Equipment Decontamination All non-disposable sampling equipment was cleaned with a non-phosphate detergent solution, rinsed with tap water, and rinsed a third time with deionized water prior to use. RT Well 12 Ra aoc 5-2 Ile ISGU000 G OUR, Inc.