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• P• 10 <br />June 18, 1985 <br />Daniel's Pit 2 <br />C. Farrell <br />Third, if mulch were crimped into the material in order to keep it <br />from blowing, all of that mulch would have to be stripped before that <br />area could be mined, not to mention the problems created by the mulch <br />that would blow into the material being mined. The problem here is that <br />the straw would cause untold problems in the processing of the sand. <br />Pumps would be plugged, product contaminated, and possibly sales <br />rejected because of the presence of straw bits. It may seem that straw <br />is little different from plant parts in the soil that happens to be <br />incorporated into the product, but in fact there is a big difference in <br />pliability, breakability, and washability. Large pieces of straw are <br />much more difficult to handle than small bits of native grasses that <br />tend to very eaily wash out in the processing. <br />We will keep this loss of soil to a mininmum, but also wish to <br />point out that a 1~ loss of soil is not at all unusual. You just don't <br />generally hear about it, from most operators. <br />Item 8 - Please discuss the stability of backfilling unconsolidated <br />materials to produce the final slopes. Irregularities (benching) in the <br />.~ highwall may provide a stabilization source. <br />RESPONSE: Backfilling with waste to produce final slopes is not an <br />unusual process in the sand and gravel business. Stability can be a <br />problem if the material contains too much clay. But if it tends to be <br />fairly sandy, stability is not usually a problem if the sand is sharp <br />and is compacted to some extent when placed on the slope. <br />Keep in mind that slope failure by mass wasting is not a result of <br />having too steep of a slope if the material is stable when placed on the <br />slope. Slope failure is produced by the mass increasing as a result of <br />water retention. The more water the material retains the less likely it <br />will be stable during wet periods. If it is fairly sandy and drains <br />well, then it is less likely to fail. <br />In this area there are many slopes that are steeper or as steep as <br />the ones to be produced here. No benching was used and yet a sizeable <br />slump or slope failure has never been observed. Some of these slopes <br />are in native material but others are fill. All of them have a texture <br />that ranges from sandy to a sandy clay loam. <br />Benching is uneconomic and therefore backfilling is necessary in <br />some instances. The smaller slopes will be made of existing material. <br />Item 9 - Does the mining phase enumeration suggest a chronological <br />~ sequence, i.e. will Phase I be mined prior to Phase II, etc.? <br />RESPONSE: Please refer to pages 7 through 10 in the Mining Plan. <br />Basically, the phasing represents a rough sequence, but very rough. <br />Some areas may not be mined at all and sequences may need some <br />adjustment because the area is somewhat irregular. Also, possible <br />future land acquisitions may alter the sequence. About ali we can say <br />is that the phases do roughly represent a chronological order, but <br />specifically they do not. They are simply some units that appear to be <br />more or less natural units that may be mined concurrently in some cases <br />and sequentially in others. <br />