Laserfiche WebLink
• In adds tron, too samples had cadmium values that were less than an elevated detection <br />limit 120 ug/1 vs. a normal detection limit of 2 uq/1) rhirh ras higher than the COOH <br />standard of 10 ug/1. Likewise, three samples had lead values Chat rare less Nan an <br />elevated detection limit (200 ug/1 vs. a normal detection limit of 20 ug/1) which was <br />higher than the CDOH standard of 100 uq/1. The cause of these elevated detection limits <br />was a decision by the Tabora Cory to dilute the samples prior to analyses in order to <br />reduce the effects of interferences (primarily, high aalinrty). A review of October 1999 <br />lab data revels no such detection limit problems for cadmium or lead, indicating that the <br />laboratory, as requested by SCC, no longer dilutes the sample to a point whore the <br />detection limit exceeds the rater quality use standard. <br />In the CDl1G'9 caviar of the 1998 AHR, a request ras made to explain the potential sources <br />of elevated levels for certain metals and sulfates. Elevated levels of iron may be <br />attributed to natural (i.e., not mining related) conditions, since elevated levels for <br />this parameter are not found in the adjacent Seneca II spoil wells. The high levels of <br />iron displayed in the one alluvial roll (YGAL15) may be the result of organic matter and <br />plant debris present in the alluvium (Hem, 1989, pg. 77). This xell displayed high levels <br />of iron prior to mining, <br />C~ <br />High sulfate values may, in part, be due to recharge from the spoil aquifer. Horevez, it <br />moat be noted that the COOH has no ground rater agricultural eiandazd for sulfate. This <br />California etandazd ie presented here merely for compazativa purposes. It should oleo be <br />noted that all twelve relln with high sulfate values this year exhibited high sulfate <br />values prior to mining. <br />High manganese values may, in part, be due to rerhazga from the spoil aquifer, although <br />high values aze often common, especially in alluvial material (Hem, 19X9, pqa. H6-B9). <br />All four cells displaying high manganese values thin yeaz also did co prior to mining. It <br />should be noted that the CDOH standazd of 0.2 mg/1 is used to protect crops gror+~ in voila <br />rith a pe value lorer than 6.0. In soils rith a higher pe (as aze found in the Yoast <br />region), a more appropriate standard could be 10 m9/1. (HpA, 1976). This year, no roll <br />displayed a value higher than 1.32 mq/1. <br />J1 <br />~. J <br />7 <br />