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Page 3 <br />Aug 8, 2008 <br />Daniels Sand Pit #2 <br />minimal growth medium. The biggest problem with the pit bottom is its sandy texture. This is fine <br />for invading trees and shrubs, but no so good for grasses. By simply increasing the fine content (silt <br />and clay particles) to about 30%, grass will grow very well in addition to shrubs and trees. Thus, <br />blending soil into the top several inches is the intent of the plan rather than creating a thick soil <br />layer that could become very soggy if the water table rises unusually high. In short, there needs to <br />be sufficient fines to grow but the medium must also be well drained. In the event there is <br />insufficient salvaged soil available for completing this, other materials may be required. On the <br />Castle Concrete Queens Canyon Quarry reclamation where virtually no native soil was available, <br />topsoiling was done using donated soils mostly excavated from construction sites. This was all a <br />part of the enhanced reclamation plan for that site which was a joint company-community <br />association to implement a higher level of reclamation than would otherwise occur. It was a very <br />successful approach. At this time, it cannot be known whether some similar, much smaller scale <br />approach will be needed here. The wording in the amendment application is simply to provide the <br />opportunity to do this if it is needed. The source of the material, other than material generated on <br />site such as excess wash fines derived from the sand itself, is not known. Thus, if this <br />supplementation is done it will need to be addressed at that time with regard to the Reclamation <br />Permit and possibly the Special Use Permit. The primary issue of concern would be possible <br />contamination of the aquifer that flows beneath portions of the pit floor. It is suggested that it be <br />made a condition of the approval that prior to importing materials for use in augmenting the <br />growth medium on the pit floor, consideration of the source and suitability of the material be given <br />and approved prior to the actual importation. It is important not to close the door on this often <br />useful and beneficial approach, but it is also important to insure it doesn't create more problems <br />than it solves. Thus a permit condition might well be the best way to address this at this time. <br />Item D. - Sediment Basin Reclamation: A concern is expressed regarding the grass understory and tree/shrub <br />density in the sediment basin reclamation. <br />Response: The sediment basin presently west of Academy Boulevard has demonstrated excellent invasion rates <br />of trees, shrubs, and some grasses. But the basin is still active and the water supply is almost <br />continuously available. What will happen after the water supply is lost is the real question. Will the <br />growth medium be sufficient to maintain good tree and shrub cover? As for the grass understory <br />that should not be a problem and if it needs to be supplemented the pit floor mixture would be <br />appropriate for this area as well as after the water supply is lost. The texture of the sediment is a <br />silty clay that holds a great deal of water but also drains fairly rapidly. So, once the water is lost will <br />there be sufficient water retention to support a good growth of trees and shrubs? Clearly, densities <br />such as those seen with a steady water supply cannot be expected, but a tree density of 80 to 100 <br />trees per acre and a canopy cover of at least 80% should be sustainable in a silty clay growth <br />medium in more or less a shallow basin topography. Supplemental planting would only be needed if <br />the density and cover declines to around 50 trees per acre or a canopy cover of around 50% to <br />60%. But supplemental planting should be done with a consideration as to whether the growth <br />medium can actually support a higher density. Clearly, a good deal of attrition will occur after the <br />water supply is lost and a judgement at that time will need to be made as to what is actually <br />sustainable. It may be that around 50 trees per acre is all that can be sustained, but it is also possible <br />that attrition would drop the density below that which is actually sustainable. Examination of the <br />tree growth itself is the only way to tell whether the holding capacity is greater than the result after <br />two or three years of attrition. If new seedlings are common and growing well, then some <br />supplemental planting would be indicated. But if new seedlings are uncommon and struggling then <br />the post attrition population density is probably what is sustainable. The inclusion of supplemental <br />planting in the plan is there simply to provide recognition that the post attrition population may be <br />lower than the holding capacity as indicated by the tree growth and condition. At the Castle Sand