2014-01-29_HYDROLOGY - P2009025 (8)

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Baseline Hydrologic Monitoring Plan — Hansen Project 30 3.4.3 Progressive Radiochemistry Screening Five of the analytes are subject to progressive radiochemistry screening. Gross alpha and gross beta are used as screening parameters, and specific radio - isotopes are only analyzed in samples whose gross alpha and gross beta levels exceed the established threshold criteria: • Analyze for Ra -226 in surface water samples having gross alpha values greater than 30 pCi/L ((x> 30 pCi /L). • Analyze for Ra -228 in surface water samples having gross beta values greater than 25 pCi/L (3 > 25 pCi/L). • Conduct thorium isotopic analysis (Th- 228/Th- 320/Th -232) on surface water samples having gross alpha values greater than 30 pCi /L (a> 30 pCi/L). The Progressive Radiochemistry Screening is automated by the laboratory. Samples are first analyzed for gross alpha and gross beta. Based on those results, specific samples that exceed the thresholds are further analyzed for Ra -226, Ra -228, Th -228, Th -230, or Th -232. If radiochemistry results are desired for a sample that does not exceed the alpha/beta criteria, Whetstone or Black Range can override the criteria and see that the sample is analyzed. 3.4.4 Regulatory Basis for Surface Water Analytical Suite The lists of parameters in each surface water analytical suites were developed based on Colorado instream water quality standards for the specified reaches, Colorado Basic Standards for surface water (CDPHE, 2001), site - specific standards for surface water (CDPHE, 2004), EPA drinking water standards, and Colorado NPDES requirements for hard rock and metal mines (Table 11). These regulations were considered in developing the list of baseline parameters for water quality monitoring although these specific standards may not currently apply to the baseline data being collected. 3.4.5 Modifications to the Surface Water Analytical Suite The analytical suite will be reviewed annually, and may be modified to add or exclude constituents, as necessary, to meet the goals of the monitoring program. The initial laboratory analytical suite included 67 analytes listed in Table 16 plus 136 volatile and semi - volatile organic compounds (VOCs, SVOCs). The monitoring program included VOCs /SVOCs for the first sampling event only. After that time, the samples were analyzed for the comprehensive list of 67 parameters shown in Table 16. Progressive radiochemistry screening (Section 3.4.3) was implemented in June 2009. The initial surface water analytical suite contained several radio - isotopes that were consistently below detection at many of the surface water stations. The laboratory analytical suite was modified to use gross alpha and gross beta as screening parameters for further radiologic analyses. Based on those results, specific samples that exceed the thresholds are further analyzed for Ra -226, Ra -228, Th -228, Th -230, or Th -232. The modification to the monitoring plan was approved by Fremont County's third -party hydrologic consultant, Western Water & Land in 2009. A reduced analytical suite for surface water was developed in 2010. Eighteen (18) parameters were reduced or eliminated from the surface water analytical suite, and the technical justification for each was outlined in a technical memorandum (Whetstone 2010a). The modifications were approved by Fremont County and their third -party hydrologic consultant (Western Water & Land). Background NPDES monitoring of began in 2011. Colorado NPDES regulations for discharges from hardrock mining or milling operations list 48 laboratory parameters and four field parameters that must be monitored in surface water upstream of the proposed point of discharge for four calendar quarters. NPDES 4153A.140129 Whetstone Associates