Review of the Final EE/CA Report Opinion:

It is still my opinion that future operation and maintenance (O&M) costs can best be reduced by covering the tailings, cutting off seepage and by stabilizing the slopes. I continue to advocate for a cap or cover over TP-1 and TP-2 to reduce future infiltration, seepage and pore water buildup which could contribute to the global instability of the mass.

It was in October 2001 and still is my considered opinion that reducing or eliminating the drainage from TP-3 will reduce the O & M costs. Sherwood Reed has independently and quite eloquently laid out numerous chemical, biological and hydrological reasons for removing all of I listened intently at the March 13, 2002 meeting for new technical questions from the audience. I heard many procedural questions , but only two of a technical nature: Will the passive treatment systems work? And, Are the costs as given justified?

In his Final EE/CA Review (Report#6), Sherwood Reed has said he believes the O &M costs as they relate to the passive treatment systems are reasonable. I have reviewed the materials given out by EPA at the March 13, 2002 meeting and have reached similar conclusions relative to the construction costs.

Background for Cost Estimates:

Nearly all engineering cost estimates are based on the actual costs of building recent similar projects. The only better estimate is a bid price. A bid is the price for which a Contractor is actually willing to build the project. In effect, a bid is the Contractor's estimate, well padded to cover his risk. EPA has used R. S. Means Construction Cost Data, 2001 to calculate their estimate. R. S. Means data is recognized by construction professionals throughout the U.S. as a primary source of average project cost data. The materials and labor costs are updated annually using actual bid data from all across the U.S. Therefore, I feel the methodology followed by EPA for arriving at the construction cost estimates for the Elizabeth Mine remediation is consistent with good engineering practice. However, project cost estimates can be in error for one of the following reasons: The unit costs of each item are either too small or too large. The math is incorrect, i.e., quantities multiplied times the unit costs or additions. Certain items were overlooked or left out of the estimate.

Estimated Quantities

I have carefully studied the project cost estimate for Alternative 2C (Appendix 2C). I do not have the maps and data to check the actual quantities of materials shown in the presentations. I was, however, able to determine whether the dimensions were of the right order of magnitude. The estimated dimensions and volumes for the Clean Trench needed for diversion channels, for the contaminated water trench at TP-3, and for the slope regrading all seem reasonable. The number of truck loads for earth moving are based on the productivity of common, large, over-the-road dump trucks with 3 or 4 axles, usually having a 12 cubic yard capacity.

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Unit Costs

Local truck hauling is estimated to cost $66.41/ hour. Independently using the 2000 edition of R. S. Means and adjusting to values to the year 2001, I computed the hourly cost of a 12yd truck to be $63.40. The cost of an 11yd scrapper is estimated to cost $2.24/ yd. I would have estimated the cost at $2.47/ yd. Loaded gravel is estimated at $9.00/ yd. I would have estimated it at $9.84. 100mil Very Low Density Polymetric Liner is variously estimated to cost $2.98 to $3.39/ square foot. I would have estimated the cost at $2.13/ sf. 60 mil Very Low density Polymetric Liner is estimated to cost $0.71/ square foot. I would have estimated the cost at $1.38/ sf. Math I checked several calculations and found no errors, probably because the estimates were prepared using a spread sheet program.

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Missing Items

I found no obvious missing items. I would have increased the contingency from 10% to 15%.

Opinion

Given the unknowns and the risk involved in executing this project, I find the project cost estimates to be reasonable. Would a Contractor have arrived at a different number? Yes, would it have been 20% higher or lower, probably not.

TP-3 after Total Removal

What would TP-3 look like after total removal? With the intent being to remove all toxic waste, EPA will undoubtedly want to clean the waste piles down to the bedrock. The area can then either be left devoid of all soil or a thin layer of top soil and grass can be placed over the area. With some top soil, in a few years the area would naturally revert back to a mix of brambles, bushes and small trees.

Project Phasing

It has always been my opinion that the Elizabeth Mine closure would end up as a phased project. The first year EPA needs to do extensive and comprehensive geotechnical, hydrologic, chemical and biological testing. The seeps need to be monitored over a full year and the data correlated with available long-term hydrologic sequences. We are all well aware of the recent drought conditions and that we should not base our designs on such limited data. I project it will be two years before the actual design phase begins. As Sherwood Reed has suggested, the pilot passive treatment studies should run over at least one winter. I suspect at least two full years will have elapsed before EPA and the State are satisfied with the design of the passive treatment systems. It is reasonable to assume that good seepage and runoff data will ultimately dictate the parameters of the final capping designs. I think it is reasonable to assume that the capping of TP-1 and TP-2 will not begin until the diversion ditches are in place and the issue of TP-3 has been completely resolved. My crystal ball says capping will not begin before the Spring of 2006.

Respectfully,

Richard N. Downer, P.E.

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