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Febnury 1998 Hayden Culch Mint • Phate 2 fi 3 Bond Release ADDlication ~ PaRe 9 <br />determined by field sampling. A good approximation of the average topsoil <br />• depth, for the A horizon, was calculated by adding the high and low values and <br />then dividing by two: <br />20" + 34" = 54" = 2 = 27" (average topsoil depth) <br />During final mine reclamation, topsoil was placed to an average depth of 21 <br />inches purruant to HGCC commitments made in January 1985 and accepted by <br />DMG in a letter dated January 21, 1988. DMG performed independent <br />measuremenu of topsoil depths across the reclaimed area in October 1987 <br />which confirmed topsoil replacement depths. Exhibit 5, Topsoil Information, <br />presents a copy of the January 21, 1988 letter from DMG indicating that topsoil <br />placement at the Hayden Gulch Mine was adequate and met the requirements <br />of the approved topsoil replacement plan. <br />6) Demonstration OjYields From Prime Farmlands: <br />• The Hayden Gulch Mine site did not disrurb any prime farmlands. <br />7) Documentation Of Total Suspended Solids (TSSJ Conditions: <br />• Table 10, Summary of Total Suspended Solids Data, presents pre-mining and <br />post-mining TSS condi[ions in Hayden Gulch. The table presents TSS data for <br />sampling stations which are located upstream of the disturbance azea (sampling <br />• station UHG), at two sedimentation pond outfalls (sampling stations Pond 003 <br />and Pond HG-8; these two ponds were constructed as sediment control <br />structures for the facilities area and mine area, respectively), and downstream of <br />the disturbance azea (sampling station LHG). <br />Baseline sampling conducted as part of the Hayden Gulch Mine Permit <br />Application indicate that the maximum TSS concentration measured in <br />Hayden Gulch pre-mining was 543 milligrams per liter (mg/l). However, the <br />TSS data indicates a typical TSS concentration range from below the <br />instrument detection limit to less than 100 mg/1. TSS concentrations measured <br />in Pond 003 and Pond HG-8 discharge generally have been less than 100 mg/l. <br />Since the completion of final reclamation and successful establishment of <br />revegetation, TSS measurements at LHG have generally ranged from below the <br />instrument detection limit to 20 mg/l. <br />8J <br />In a letter dated November 25, 1985, DMG approved Pond 003 and Pond HG-8 as <br />permanent impoundments. The two ponds are the impoundments which were <br />constructed as sediment control structures for the facilities area (Pond 003) and the <br />mine-pit area (Pond HG-8). <br />• <br />Montgomery Wauon Americas (dba TenaMatnzJ ' P.O. Boz 774018 <br />Steamboat Springs, Colorado 80477 • (970J 879-6260 <br />~r.~smp~~ci e:r..~,.~yp..m~~ mw...,ciewe,m<..nM~wo, <br />r~ero, r. <br />