2006-03-22_REVISION - M1988044 - Laserfiche WebLink

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Page 2 Adequacy Response March 22, 2006 to sustain the tree and the groundwater supply is usually reliable enough that the loss of feeder roots on one side is not fatal. But in situations such as ephemeral streams where groundwater support may vary considerably over the year the trees axe usually living in an intensely water limited environment. In these simations, the loss of any significant part of the feeder soots can be fatal ox can weaken the tree to a point where it is susceptible to diseases. Thus, in these situations, excavating to the drip line can be fatal to a tree. Unfortunately, one cannot say fox sure that any pazticular tree will, in fact, die if feeder roots are lost. It is possible that any paxriculax tree has most of its feeder roots asymmetrically distributed such that where the excavation would occur there aze few feeder roots. The problem is, without excavating the tree it isn't possible to know how the feeder roots axe distributed. Therefore, the best course of action is to assume the feeder roots are equally distributed around the tree which is the "normal" condition. With deciduous trees, like cottonwood, the feeder root zone is usually not more than two or three times the height of the tree. It can be greater, but the largest mass of feeder roots axe usually within that zone. In the case of evergreens, this zone can be much wider. For example, Ponderosa Pine has been found to sometimes have sigtuficant feeder roots that extend as far as five to ten times the height of the tree. This is why Ponderosa Pine is often so sensitive to ground disturbances neaz the tree. Furthermore, many conifers have their feeder roots comparatively close to the surface while deciduous trees tend to be more deeply rooted. Thus, shallow disturbance near a Ponderosa may kill the uee while that same depth of excavation may not affect a cottonwood tree ox most other deciduous trees. There axe exceptions though. The depth of rooting is mostly a blend of local environmental limitations and the tree's generics. So, this is the reason why this change in the uee setback has been included in this plan. Preservation of the forests along this stretch of Coal Creek is a priority for the Land Board and because the forests in this immediate area very moisture limited considerable care must be exercised to minimise damage to the trees. Item V. You axe correct in your understanding. All water fox the operation is purchased from nearby wells. No mining will occur below the level of the groundwater, if any is encountered. It is significant that in all of the exploration holes only two showed the presence of groundwater and those aze in areas that will very likely never be mined. All other exploration holes were dry. Item VII. Thank you for your agreement with our cost calculations. Submittal of the additional bond amount will be provided well in advance of operations beginning in the new areas. Sincerely, ~~~ Mark A. Heffner, E ogist cc: Scott Davis Don Opheim Mark Davis Melissa Feeder