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Geosy ritec �l Consultants t P— -11,,22-t\mCE1 1111C111 N 2, 1 ask L\11(bit Dat, I C% E EXHIBIT S STRUCTURES EVALUATION 5 ARCOSA LN%-B INTRODUCTION As part of permit amendment application for theArco-sa I.Whmeigllt Boulder (1,%\ B) facility (Site) a -,eotechnical e\akfatiOfl OfstrLICtUreS identified %whin the facillt\ pen-nit hOLIndar\ and vvithj feet of the f1icilit\ permit bOLIndar\ Is required In lieu ot'signed Structures agreements. the purpose or this Structure,,, 1:\akiation is to assess the stabilit\ or permanent. man-made structures on site and within the 2004001 boundary offset and evaluate whether the current anti proposed facility operations have the potential to Impact those structures. The SUbSe(.ILIent sections present the rnethodolo,.,} used our the Leotechmcal stabilit\ anal\sIs and structures e\alUatI0Il. input parameters. assumptions. result--; and conclusion,,. SITE DESCRIPTION STRATIGRAPHY AND GROt NDWATER The Arcosa L\\ B taclllt\ is located in JefTerson CoUnt\. ( olorado. the Site location is described in the Site Legal Description (LOIbit A) orthe permit amendment application. The surface mine (qUarr-,) is located \\est ofl 112hwa\ 9 1. The processing area is located east of ffighk\a\ 93. Figures S-I. 'S-2 and S-1 shok\ the Site la\out and ad'jacent lands. A recent aerial SLir\e\ k\as performed hN Vc(-a to ohtain topographic data. Topography Is shown on those C12Ure,. '-;e ru,e n t. flaUskin, & Beck\\Ith (jeotechnical F.n,-,Inecr,, iSHB) PI-of\ iOLISI\ characterized the Site I—le0102\ as part of an L-nuineering Design and Operations Report' for a Certificate OfDesi2nation. purposed tOr the then-proposed Shale Mine Ash Backfill Pro,iect b% the fi)r-mer Site owner. %\estern Aggregates. Inc (\\Al). I-ILI.Lire �.1.1-I in the SIM I:nLineerim-, DesIL111 and Operations Report presents the SUrficial Geol()L,\ in the \ icInIt\ of the WWI facility (also kno%\n as '-the Site-) and a ueneralized 2Ck,l0,—)IC cross section showing [Ile Site Location. I:IL'Ure -;.J.I-I from that report is pro\ided as Attachment A. I he stratl2raph\ considered for this e\ah.lation 1s based on the SI III characterization and Includes the follovv In'-' units. 1'1i,camAlluvium - approminatek 9 feet thick and present at the -,round Surface. SIOCLIM AIIM iLInl is a silt\. sand\. and ck)bbl\ gra%el that was deposited as a f1LI\ial lag deposit dUrI112 the middle Pleistocene. Fll]'S unit is comprised orre\\orked materials frorn the nearb\ Rock\ Flats alIM ILIM and Verk.10, "I I I U\11.1111 .1 Cerdri,:ate orneiunatwt, Shale ',,Iin,- \ch Rack-fill Pmject.prepared b\ 1)erueni. FLIUskin, & Beck%%itfi in \lar,1i 1901. fk,r \\estern Ins -A ij;