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<br />ENVIRONMENT,-INC. i ~ ,' PAGE 3
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<br />' MAY 1',5, 2008 it
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<br />`Rule 6.4.7 Exhibit G - Water Information, ' .. ' ~ - -
<br />'1) •, All the wells ~ witli'n 200. feet of ~ the mine, have :been .1-orated on ,
<br />Map Exhibit C - Prse-Mining Plan Map. Any shallow surface aquifer :
<br />• wells ;within the mine.-area will be removed..: The~deep:'wells will'
<br />- not_:be impacted when-mining takes p-lace.. No wells off 'the .site ..
<br />will be a.f fected since -this will be, a wet mine and' no dewatering ..'
<br />` ~ ,will' take -place. ~~ ~ ~ .- ,
<br />2) The, .only, aquifer impacted by:.\miningwill 'be' .the, surface aquifer. ~~
<br />' -associated with' th'e South Platte River. The depth is; approxi- :
<br />.. mately.9 feet deep': or-.lies from 6 feet below the existing surface -
<br />- to the_'top of the;~underlying impervious: shale., Underlying this ,
<br />-area are deep aquifers .that are not `connected to' the- surface that , ` ,
<br />_" will not -be impacted by .this mining .oper'ation. '
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<br />Rule 6.4..1.9 Exhibit:L -Permanent Man-Made Structures ' :
<br />' r ~Attached~ is a."copy of the, compensation agreements .from Mr.~ &- Mrs. Roy `
<br />'' . to 'cover their building.. . On the other small' structures like. electric
<br />lines, roads. and fences, we . supplied information. in the; Geotechnical- ~ ,
<br />Stability,Exh'ibit explaining how Albert Frei and Sons,:, Inc :., will
<br />protect all structures as mining progresses. Thin analysis-and ~ ~,
<br />methodology has ,been acceptable to the Division in, the past.
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<br />Attached is a.Geotechnical Stability analysis prepared by Arcadis
<br />U.S., Inc.' showing that! the."safety .factors calculated based on :our
<br />mining, methods' are weld; within, the.normal margins of safety to,, protect- ~ -
<br />Thorriton's 'structures. iPlease adv.ise.if additional'. information is -.
<br />.~ needed on this subject:'
<br />The irrigation~`structure'noted was located on the'Pre'=Mining Map.,. but ,
<br />not marked. I have corrected that. ~I ask Mr. Priola what ,this'
<br />. ~ irrigation structure'was.used-for"and he~said it wa an`old headgate
<br />':" used when .his .grandfather irrigated most .of the area' now within '
<br />`.-Thorntori's,lake',areas: I't_supplied water from the Burlington Ditch
<br />that, ran along the east!j side 'to the property prior to •~I-76' being,
<br />built.. He said it ,would be~removed as they demolish ,the structures- on~- '
<br />' the, mine .area :and has-been.abandoned for many years. ~ ~ '
<br />Miscellaneous , - .. ~ j
<br />~`We wish to thank the.Corp's of Engineers the-Colorado Historical ;'
<br />. _ Society' and .Xcel Energy.; for the time they took .-to comment. on~ this "
<br />application.. Frei will ~. be working c'losel'y. with Xcel: ~Energy~ and Qweat
<br />' as .mining progresses across .this site so-their... power' .and communication'
<br />lines.are protected or removed 'if needed: .. ,. -'
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<br />._ City of Thornton „ ~ -
<br />I will respond, to, 'Thornton's points under `their potential adverse , '
<br />' - 'impacts section. in theorder pres'ent~ed : ,
<br />' The.Arcadis-,report, addresses. this issue. It _shows`that'the~'marg'in for .
<br />safetp varies from 5`:•49~r to. 2'.233 for the'slurry ywal_i and 2:58 ,to 1.:'34 ~' .`
<br />_ for the ditch. The=•general acceptable threshold for temporary slopes."' ,
<br />is"1.35:. Backfilling will. run'simu-ltaneously:with mining and we .,
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