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<br /> <br />(3)(a) Vertical alignment. Maritnum road grades shall be as follons: <br />(i) The overall grade shall not be steeper than /0lr: /v (/0 percent). <br />(ii) Maxitmutr pitch grade shall not be steeper thmt 6.Sh: /v (/5 percent). <br />(iii) There shall not be more thmt 300 feet of pitch grade e.rceeding /0 percent xdthin <br />mrv consecutive /,000 feet, but in no case slur!! there be arry pitch grade steeper than 6.Sh: /v <br />(l5 percent). <br />Significant portions of haul road B extension exceed the required vertical alignment (Station 5+00 to <br />Station 40+00 has an overall grade approaching 14%) yet no analytical demonstrations by a PE have <br />been submitted to validate that such alternatives will be as environmentally sound as those resulting <br />from haul roads complying with the requirements of 4.03.1(3). <br />Paragraph 2, page I8, Tab 13 states "...some haul road segments exceed a 10% grade...However, <br />erosive velocities ntay occur during the design storm eti•en[". <br />This statement implies that the "engineered" roadside ditches are really not engineered correctly, or <br />that SCC does no[ plan to install the protection necessary to prevent erosion from occurring. <br />4. (3)(e)(vii) Each layer of the embankment sltnll be completed, leveled, and compacted before dte <br />stecceeding layer is placed... <br />I was unable to find any information concerning the subgrades, base, subbase, or surface material <br />depths, or engineering properties. <br />Paragraph I, page 16, Tab 13 is a quote from our regulations, however, nothing is presented about the <br />specifics of the proposed haul roads. <br />All comments listed below refer to Attachment 13-12, Seneca Yoast Mine Drainage and Sediment <br />Control Plan. <br />As mentioned earlier, many of the problematic issues listed below are a result of deficiencies with the version <br />of Sedcad 4 [hat was utilized by the engineering firm at the time the designs were prepared. <br />5. Page 2, paragraph 2.4 Hydrograph response shape. SCC explains the three types of response <br />times available in Sedcad ,fast, medium, and slow, then describes typical conditions representative of <br />each type. SCC states that a medium response time corresponds to average conditions and then chose <br />this response as representative of the mine site. Although this approach might sound if there was <br />little disturbance planned and site conditions were relatively uniform throughout, [his is no[ the case. <br />Since the Sedcad program makes it extremely easy to assign correct response times to each sub- <br />watershed, and that changing the response from medium to fast can affect the peak flow by 30-50%, it <br />is recommended that each sub-watershed be assigned the response shape that most appropriately <br />applies. <br />6. Page 2,paragraph 2.8 Curve Number, CN. SCC `s table of curve numbers list the reclaimed land <br />with B type soils CN [o be 71, but [his was previously approved [o be 70, (Table 13-1 in the permit). <br />This is satisfactory for B type soils; however, over 95% of the soil types in [he planned disturbance <br />areas are either C or D with corresponding CN's of 80/78/74 and 84/S2/80. This significantly affects <br />