6.6. SR 03-15-2010 - Laserfiche WebLink

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Fw ~1 k River ~andfi 11 -Review of Phase z~~ Report for Msw ~xpansi on . tx~~ w~ 11 not be a~Ffected by the development of the s~ te, The eng~ neeri ng design 'For surface water routi n wi 11 result i n a si gn7 f ~ cant change i n the hydraul ~ cs for the wetland area. The a sects on the wetland are unknown a~ this time, The s~ gni fi cance of 1 oval ~ zed groundwater recharge from i nf~ 1 trat7 on at the sedi mentati an ponds i s unknown at this time . zt may be appropriate to assess impacts to the wetland area and groundwater using a technical approach, pa e ~.4, water well survey: A comprehensive updated water we11 survey is presented. ~" a Ri dges of Rice Fake communi t water sup 1 y we11 i s 1 ocated ,approximately Z/3 m~ 1 e , dvwng radi ent of the s~ to . T e atent~ a for 7 mpacts to the s well 7 s very sma11 cons derv n the we11 cased to a de th f n g ' o early X40, feet, however CRS. shoal d cons der the ~ ncl use on of the s wet ~ n the res~ dents a1 wee 1 mangy tor? ng program. pale ~.5, Conti nuous Ti 11 Layer; A d~ scussi on i s rovi led regardi n~ the fine-grad ned so~1 deposits ~ti11~ separat~n~ the upper outwas unit from the lower outwash un~ t. zt i s stated that the the ckness of the ti 11 depas~ is vary es from ~ to more than 5o feet at the site. Pi~ure ~~ presents a Till zsopach Map which shows areas of the site where the ti 11 the ckness i s 1 ess than ten feet, Althouggh ~ t i s not stated within the text of the re ort ar on the ma i t i s i m 1 i ed th ~~ the ti 1 , ~~ ~p a 1 1 a er ~ s cants nuous throughout t e s~ te, ~'he ava~ 1 abl e bore ng data suggest that the ti 11 1 ayer i s cant? nuous, however, the bore ngs ~ n the west central port? on of the site do not extend to an adequate depth to definitively make this conclusion. ~t should be noted that borings 9, l~ ~?~, Z~, Z5 to do not provide evidence that the ti 11 i s centi nuous. rt should be fur~~her noted that the geo1 a~~ c cross-sects ons why ch dep~ ct a cont~ nuous ti 11 1 ayer far this porti an of the s~ to are interpretive. There exists a possibility that the ti~1 is discontinuous at the site and the u per and lower outwash units are in h' draul~c connection, rt should be noted that the absence of the ti 11 1 a er i s they i tuati an which i s re en f ' y , ~ s p ~ ~ or the ex~st~ng ~ and~i 11 ~ area i n the v~ ~~ n~ ty of the ~RL shop. n1 scanty nub ty of the t~ 11 1 ayer has ~ mpl 7 cats ons far establ ~ shy ng an effective groundwater mvn~ tore ng system at the site. Page Z0, groundwater t~ischar e; The report states ghat graundwater,in the north. central pperti on of the s~ to 1 ows northwest and ~ s ~ nterpreted to d~ schar~e to R~ ce ~.ake T1 bb~ is ~roo . ~t ~ k s understaad that WM~ .has conducted additional s~ to investigation related to the groundwater im acts from the existing waste deposit, No data has yet been presented to support t is groundwater discharge conclusion. Wage ZZ, ~rvundwater Monitoring; WMT proposes the addition of one nested piezameter in the lower outwash to evaluate the hydraulic gradient across the ti11 layer. Gives the concerns re~ardin the cantinuity,of ti11 layer, the,piezometer should be ut~ 1 ~ zed as a moni tort ng we 1 and i nc1 uded , ~ n the proposed man? Lori ng work p1 an, A second nested moni tore ng we11 CP~zZC 1 ocat~ on sug~ested~ should be installed a1 ang the western parti an of the south boundary for si m~ 1 ar gradient and water quality moni sari ng purposes . A maximum spacing of 4Qg feed between down radient compliance boundary moni~aring we11 s has be used for the ex~ sti n 1 andfi 1 ~, - s su e g ~~t ~ gg~sted that this maximum space ng be may nta7 ned for the 1 andf~ 11 expanse on. Thy s ~ mp1 ~ es that several addi ti anal upper outwash moni tar? ng we11 s would be i nc1 uded i n the ~~ani sari ng network, page ZZ, we11 installation,schedule; ,The report stakes that the current network of moni tors ng we11 s ~ s suffi c7 ent to moni for the expanse on of the f~ 11 area through Ce11 ZO' The southerly 1 i mi t of fi 11 of Ce11 ZO wou1 d correspond to plan stag an Z45, ~D~ based on avai 1 ab1 a en i neeri ng pl ons for site level apment. Frain the conce tual W dra solo is Model F' r 1 s p y ~ g g ~gu,e 7, a .authwesterly component to groundwater flow from porn ons of the pro ased f~ 11 area ~ s apparent.. There are no mon7 tori ng we11 s existing a r p1 anned wit i n a reasonabl y cl ase distance that would intercept these groundwater f1 ow 1 i Wes . The sui tabi 1 i ty of the existing network of we11 s to moni tar the level opment of the site through ce11 ZO i s questi anabl e, page Z