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Stark, Jim <br />From: Mathews, Dan <br />Sent: Tuesday, October 17, 2006 3:49 PM <br />To: Stark, Jim <br />Cc: Brown, Sandy <br />Subject: Colowyo MR-83 Test Plots Proposal <br />Item 1. OK with me <br />Item 2. I don't understand their resistance to obtaining a single composite sample from each of the two test plots, for <br />analysis of basic soil test parameters. They are proposing to test the concept of using a thin layer of overburden material <br />as the surficial plant growth medium over the top of the topsoil. In effect, they would be using overburden as a topsoil <br />substitute, or as a supplement to topsoil. I assume that if they obtain favorable results from the test plots, they would want <br />to implement the practice on a larger scale basis, as a component of their standard reclamation procedures (and if results <br />are favorable, I presume we would encourage them to do so). Take a look at Rule 4.06.2(4)(a) regarding the <br />determinations we are required to make to allow for use of overburden materials as a substitute for topsoil, and let me <br />know if you think the request for sample analyses is unreasonable. <br />In the narrative, they indicate that the topsoil would be covered with six inches of "benign, nutrient-poor overburden". I <br />would agree that the Colowyo overburden is typically benign, and is also typically nutrient poor (compared to typical <br />topsoils), but I also believe it is reasonable to request that these assumptions be verified for the material used in the test <br />plots. In their response, they indicate that the Division already has a wealth of information on overburden quality from past <br />reclamation reports, and that the value of the information would be questionable because of the inability to "replicate the <br />exact overburden conditions in the future... ". I would agree that we have a lot of information on spoil quality at Colowyo, <br />and that it is probably not possible to "replicate the exact overburden conditions". But I think it is important to document <br />that the overburden material used in the test plots falls within the typical ranges documented for graded spoils in past <br />annual reclamation reports, and is reasonably representative of materials likely to be used in the future. Also, I believe the <br />information obtained from the sampling could be of value with regard to future interpretations of vegetation response on <br />the test plots. So I continue to think that our original request was reasonable and appropriate. <br />If it makes a difference, I would say we could reasonably delete selenium and boron from the test parameters; these <br />parameters are not specifically required by 4.06.2(4)(a), and excessive levels of the parameters have not been indicated <br />by any previous regraded spoil sampling. <br />Item 3. Their response is acceptable <br />Item 4??? There is no Item 4 listed, but it you remember back when I did the original MR-83 review, I called you from the <br />road with an additional recommendation, that they should include a "control plot", that would consist of the same topsoil <br />used in the test plots, but without the spoil layer on top. The control plot would need to be seeded with the same seedmix <br />as the test plots, at the same time, and otherwise treated and managed exactly the same as the test plots (including <br />fenced and non fenced control). Without such a control plot, it would be difficult to assess whether plant response <br />observed on the plots could be definitively attributed to the spoil treatment, or some other factor(s). I would still <br />recommend inclusion of an appropriate control. <br />Let me know if you have any questions. <br />Dan <br />