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2014 Estimate of Monitoring Well and Piezometer Closure Costs 23 -Wells <br />Per information provided by Jeff Campbell to M. Ellis on February 18, 2008, there are 49 monitoring wells ranging in <br />diameter from 4 to 6 inches and from 50 to 250 feet deep. There are also 15 piezometers that are shallow (20- 40 ft deep) <br />and they are mostly 3 inch diameter holes. Following recent additional monitoring well additions to support MLE2 there are now 80 wells. <br />The number of wells (80) was confirmed again by MDE on August 9, 2013 with M. Ticl uist. <br />Assumptions: (1) the closure of the monitoring wells involves cutting conduits off at ground level, (2) filling with bentonite chips <br />from bottom of the well to within five feet of the surface, and (3) putting in a plug of concrete of 5 feet depth on top of the <br />bentonite and extending to the surface to create the necessary seal and closure of the hole. <br />This procedure would comply with Colorado State Engineer's Office Rule 16 -- Standards for the Plugging, Sealing, <br />and Abandoning Wells and Boreholes. <br />To be conservative, assume each of the monitoring wells is 250 feet deep and 6 inches diameter. <br />To be conservative, assume each of the piezometers is 40 feet deep and 3 inches diameter. <br />Monitoring Wells <br />Number of Wells? <br />80 wells <br />Provided by CC &V Env Staff <br />Well Depth bentonite chips (ft)= <br />227 ft <br />Assumed conservatively for each well <br />Well Diameter (ft) = <br />0.5 ft <br />Measured <br />Calculated volume chips (cu ft) = <br />44.5 cu ft <br />Diameter x Depth <br />Density of bentonie chips (pcf) <br />69.25 Ibs /cu ft <br />Cetco Volclay Medium Bentonite Chips <br />Pounds of chips required = <br />3085 Ibs /well <br />Volume x Density <br />Depth of Concrete Plug (ft) = <br />5 ft <br />Required by Rule 16 State Engineer's Office <br />How many bags concrete? <br />2 bags /well <br />Enough to make 1 cu ft of plug + small cap <br />How many yards of sand? <br />1 cy /hole <br />Estimated by MDE <br />Backhoe hours per hole = <br />2 hrs /well <br />Estimated by MDE <br />Laborer hours per hole <br />4 hrs /well <br />Estimated by MDE <br />Piezometers <br />Number of Piezometers? <br />15 piezometers <br />Provided by CC &V Env Staff <br />Piez Depth bentonite chips (ft)= <br />35 ft <br />Assumed conservatively for each piezometer <br />Piezometer Diameter (ft) = <br />0.25 ft <br />Measured <br />Calculated volume chips (cu ft) = <br />1.7 cu ft <br />Diameter x Depth <br />Density of bentonite chips (pcf) <br />69.25 Ibs /cu ft <br />Cetco Volclay Medium Bentonite Chips <br />Pounds of chips required = <br />119 Ibs /piezo <br />Volume x Density <br />Depth of Concrete Plug (ft) = <br />5 ft <br />Required by Rule 16 State Engineer's Office <br />How many bags concrete? <br />2 bags /piezo <br />Enough to make 1 cu ft of plug + small cap <br />How many yards of sand? <br />1 cy /hole <br />Estimated by MDE <br />Backhoe hours per hole = <br />2 hrs /piezo <br />Estimated by MDE <br />Laborer hours per hole <br />4 hrs /piezo <br />Estimated by MDE <br />Activity <br />Work Hours <br />Eqmt Cost Labor Cost Material Cost Total Cost <br />Monitoring Well Closure <br />Cut -off pipe, capping, and <br />plugging with backhoe* <br />160 <br />$ 6,760 $ 5,222 $ 80,570 $ 92,553 <br />Labor for plugging & capping <br />320 <br />N/A $ 7,131 N/A $ 7,131 <br />Piezometer Closure <br />Cut -off pipe, capping, and <br />plugging with backhoe* <br />Labor for plugging & capping <br />*80 H.P. Backhoe (2014 Means, p. 525) <br />30 $ 1,268 $ 979 $ 823 $ 3,070 <br />60 N/A $ 1,958 N/A $ 1,958 <br />Subtotals = $ 8,028 $ 15,290 $ 81,393 $ 104,712 <br />Well and Piezometer Closure Total Cost = $ 104,712 <br />Rental Rental Cost Operating Labor <br />Monthly Hrs /month $ /hour $ /hr $ /hr <br />2,825 176 $ 16.05 $ 26.20 $ 32.64 <br />Rev. MDE (3 -4 -14) <br />3/21/2014 <br />