Laserfiche WebLink
Unfortunately, I am not able to use most of the data in a quantitative manner, even with the aid of Mr. <br />Barton's explanations. The water tests did not analyze many of the metals and other parameters that are <br />regulated in surface water, and most of the parameters that actually were measured are not regulated. <br />Manganese, iron and sulfate appear on the regulated list, so the analyses of these parameters are useful. <br />For the sediment sample, which was analyzed by the TCLP method for TCLP metals and some other <br />metals, I find some information to be indicative but not definitive. As with the water samples, some of <br />[he parameters regulated in surface water were measured by the TCLP method whereas others were not. <br />Hence, there is no way to assess, even empirically, those regulated metals that were not measured. <br />But the lack of measurement of all regulated metals is only part of the problem. The TCLP testis <br />designed to evaluate leachability of materials that might be placed in a landfill. The test uses a suite of <br />acids that simulate what might be present in a landfill to leach a solids sample, then compares the <br />analytical results to values, established in regulation, that presumably represent upper limits above which <br />there might be some adverse effect on groundwater receptors. <br />In the extant case, appropriate tests should have measured potential effects on surface water receptors, not <br />groundwater receptors around a landfill, and should have used leach reagents simulating chemical <br />conditions of the gravel pit. Such tests, had they been properly addressed, should have used simulated <br />rainwater or even local groundwater, not the aggressive acids employed in the TCLP tests. <br />I realize that the samplers employed the TCLP test in order to provide a strong measure of conservatism. <br />For some elements, the approach paid off. That is, for those metals that registered below surface water <br />quality standards, I could conclude that the chances of mobilizing those metals under pit operating <br />conditions is nil because the only "reagent" that might leach the gravel is water, and water is far less <br />aggressive and is far less capable of dissolving rock than the TCLP acids. <br />However, for barium, cadmium and manganese, each of which registered above water quality standards, <br />the results are not definitive. These results show that the concentrations of Ba, Cd and Mn might exceed <br />surface water quality standards if released from a landfill, but they do not tell whether those standards <br />would be exceeded if water were released from the Line Camp gravel pit. One cannot say these metals <br />would or would not be problematic because the TCLP test does not simulate gravel pit conditions. <br />For two of the three metals that exceeded surface water standards in the TCLP test of the sediment, better, <br />more definitive information was provided in the water tests. Both Mn and Fe in the pit water are present <br />in concentrations that are below surface water standards. Therefore, it can be concluded that mining has <br />not increased concentrations of these two metals to such an extent that they would exceed surface water <br />standards. However, for Cd, and for all of the regulated metals that were not analyzed by any method, the <br />tests cannot tell whether gravel mining will cause increases in concentrations of those metals sufficient to <br />exceed surface water standards. <br />Under previous evaluations using observations from gravel operations where metals concentrations were <br />measured, I concluded that gravel mining has extremely low potential to appreciably change water <br />quality, except for temperature and suspended sediment, and in those cases, suspended sediment is <br />controlled by sediment ponds. CDPHE has concluded likewise as evidenced by the fact that it is the <br />exceptional operation where anything other TSS, pH, conductivity or temperature is required to be <br />measured in the discharge. <br />2 <br />