Laserfiche WebLink
<br />C WHB\C82056\RN03\011400adq.doc <br /> <br />01/14/00 <br />informa[ion was used [o certifv the as-built condition; see D[LIG professional cert fication policy <br />memo). D~L1G cnn not verify compliance with Rule a.03.6(3)(a) and Rule ~.0~.6(~) without <br />accurate injormarion. <br />12/6/99 materials <br />Twentymile Coal Company's cover letter, received December 20, 1999, states, "The information <br />in Exhibit 8-E is for the pond in its current location. The information on page 8-97 was for the <br />original pond location and does not apply to the current location.." If the information on page 8- <br />97 is not correct then it should be corrected or removed from the permit. The Division still does <br />not have an as-built certification for Pond E. Please provide and as-built certification for Pond E. <br />Pond B -this structure continues to be deficient in a number of areas. There appears to be no <br />general or detailed design plan as required by Rule 2.O.i.3(=F)(a). DMG cannot verb compliance <br />with Rtrle =1.05.6(3)(a) which requires a demonstration that the pond can contain or treat the <br />inflow from a 10 year, 24- hour storm event. Exhibit 8F refers to only three disturbed acres <br />which is not accurate for this pond. Emergency spillway sizing jor safe passage of the 2~ year, <br />24-hour storm event is also not provided for the increased disturbed area. <br />Twentymile Coal Company submitted information for Pond B on January 10, 2000. This material <br />addresses the Division's concerns adequately. <br />Pond D -Text on page 8-3 slates Pond D has a storage capacity of 51.0 ac-ft, which is more than <br />adequate. The text also states "Since Pond D is designed to handle a much larger capacity than it <br />is utilized for, the total inflow from a 100- year, 2.1-hour (storm) event would not fill the pond to <br />the level of the emergency spillway". Both of these statements are inaccurate. Pond D is almost <br />always full and discharging, indicating the water level is above the lowest discharge point on the <br />primary spillway. Pond D needs a demonstration [hat the 10 year storm event can be contained <br />or treated The EPP survey is not cert~ed. Plate 11 is referenced in the ns-built certification in <br />Exhibit 8H, but apparently is not included in the current permit materials. The currently <br />approved W.E.T. Inc. calculations are an analysis of the hydratrfics of the spillways and do not <br />estimate or predict sediment concentration in the effluent. In addition, the elevations of the riser <br />holes in the W.E.T. calculations do not match the Epp survey included in Exhibit 8H. The <br />watershed for Pond D has also undergone changes with the addition of the refuse disposal area. <br />New SEDCAD calculations (or other calculations a! TCC's option) need to be provided. In lieu of <br />these new calculations, the original design calculations can be submitted along with detailed <br />injormarion comparing the current watershed characteristics with the original design assumptions <br />to show that the disturbed area and subsequent sediment yield is less than what would be expected <br />considering current conditions. <br />12/6/99 materials <br />The new pond Dotage/storage map does not match the new SEDCAD runs done in May for Pond <br />D. The principal spillway elevation (6846.9 fr.) shown on the November 1999 stage storage area <br />curve does not match the May 1999 SEDCAD run principal spillway elevation. Please correct <br />this inconsistency !n addition, this new map needs its Exhibit number labeled on the map. Is <br />