Laserfiche WebLink
TENORM. When the City is required to dispose of TENORM, the cost is 700% higher <br /> than our standard disposal cost. <br /> Accordingly, it is imperative that this site is sustainably operated with drinking water <br /> source water protection and public health as priorities in both the near and long-term. <br /> The City has received the results and findings of Denver Water's extensive technical <br /> review of the amendment, and we are in agreement, in particular with the following <br /> conclusions: <br /> 1) CLL's Conceptual Site Model is deficient: The current Conceptual Site Model <br /> lacks sufficient data and quantitative analysis. It does not meet ASTM or EPA <br /> standards and guidance for the content of Conceptual Site Model. There is <br /> inadequate evidence that the subsurface hydrogeology and groundwater flows <br /> are well-characterized. Is uranium migrating offsite in the regional groundwater? <br /> This has not been studied with a quantitative groundwater model. <br /> 2) CLL has not stabilized the Mine Pool: Uranium and radium levels in the Mine <br /> Pool are extremely high. On Page 21 of the amendment, CLL states that the <br /> Mine Pool contains Uranium at levels of 12 mg/L, which is 400 times the <br /> Maximum Contaminant Level of 0.03 mg/L allowed in drinking water. Further, <br /> according to Table E-2 on Page 23 of the amendment, the average level of <br /> Radium-226 in the Mine Pool is 61 pCi/L, which is over 12 times the Maximum <br /> Contaminant Level of 5 pCi/L for combined Radium allowed in drinking water. <br /> The data in Figure E-5 also demonstrate that uranium levels are increasing in the <br /> Mine Pool. This is logical because concentrated brine from the Reverse <br /> Osmosis treatment process is not being removed from the site, but rather is <br /> being discharged back into the Mine Pool. <br /> The City does not believe CLL provides sufficient evidence to exclude the <br /> "suspect data" showing very high levels of uranium in Figure E-3 in the <br /> amendment. This needs additional study before we have confidence in the <br /> stability of the Mine Pool. <br /> Further, with only two monitoring wells used to estimate groundwater gradients, <br /> there is insufficient evidence that the Mine Pool is contained. Data on only two <br /> wells (MW-15 and MW-18) were provided in the amendment in Table E-1. <br /> 3) The long-term operational costs to minimize harm to the prevailing hydrologic <br /> balance and avoid unauthorized discharges should be reevaluated: On Page 44 <br /> of the amendment, there is a statement that the costs are "consistent with the <br /> remaining scope of work at the site." However, the current method of operating <br /> the site will require perpetual pumping and onsite treatment. This inconsistency <br /> of planning periods (limited scope vs perpetual) is very concerning to the City. <br /> The estimate of cost of operating this site (Table L-1 in the amendment) appears <br /> unrealistically low, and it also does not reflect perpetual operation. One example <br />