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Regrading to rough grade is nearing completion in the Prospect Ditch watershed of the <br />former East Pit. Technical Revision #63 (TR-631 modified the post-mining topography and <br />drainage in this area. Postmining permanent drainage profiles are shown on Map 33. <br />revised and certified 2/13/07. Plan view of this drainage is shown on Map 41. Watershed <br />Boundaries for Hydrologic Modeling, revised and certified 2/14/07, Grade of the lower <br />portion of the Prospect ditch were field checked using a Suunto PM-5 Clinometer. <br />Station Field Reading Maa 33 <br />5 to 6.5 10 degrees 7 degrees <br />6.5 to 8.5 14 degrees 7 degrees <br />8.5 and up 16 degrees 16 degrees <br />Potentially the lower portion of this ditch is steeper than the design plan. This could result m <br />erosion of the riprap channel unless careful field design practices are implemented. Some <br />gullies have already occurred, especially from flow from the north, above the substation road <br />Conditions are "worst case" at the present time due to the lack of topsoil and vegetation. <br />Revegetation _ <br />The inspection proceeded to the <br />north to observe revegetation <br />and permanent drainage in the <br />Gulch A watershed, shown at <br />right Green-up of grasses and ". ` .~~r k~;;,, .~+z~-,,,,,,M <br />(orbs is well underway- No rills ,,, <br />; ._ ~ ~ ~ sy : <br />~ , <br />`. . <br />, <br />or gullies were noted, Contour _-_ <br />~~ =- _ <br />~. <br />~ ° +. ~ ~- "';~ <br />,. <br />_ <br />ditches are present in this "` . <br />~ - ' „ y ~`' ' ~:a ~ ~ <br />..+ <br />~ <br /> <br />reclaimed area. spaced at about <br />'~ ~ , .. <br />- = -.w. {` ~,y.; <br />;+;~;,;: <br />~ <br />100 feet, and seem to function <br />. _ <br />a <br />:. • ' --_ = ~z;~. -- •~ <br />well in controlling erosion on .may <br />:: <br />long, reclaimed slopes. This <br />. ~++Cp~'"~ ~x~- ~' ,.. <br />~ <br />.. ~~ r' ~~. ; <br />~ <br />technique will likely be useful in a _ i . , ti <br />~" ' <br />- "~3 "~ <br />~ <br />the Prospect watershed as well, ,,; -~ ' <br />~- W.,r ~~ ' '-"^'~ <br />`- ~~ # <br />due to long and moderate to ,,;`.c"~~h _..~;`~'~~R: ~~ ~,~• .: ,` 3~_ ~ <br />steep slopes. The short section of nprap drainage in t his area has held up well and no <br />evidence of failure of the channel lining was noted. <br />Overall, the site appeared in good condition for the spr ing season. <br />