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HomeMy WebLinkAbout1.01 Geological Hazards ReviewSTATE OF COLORADO COLORADO GEOLOGICAL SURVEY- seruing the people of Colorado Department of Natural Resources 1313 Sherman Street, Room 715 Denver, CO 80203 Phone: (303) 866-261 1 Fax (3@) 866-2461 COLORADO RESCI.IRCES Bill Ritter, Jr. Govemor Haris D. ShEman Executive Director Vincent Matthews Division Director and State Geologist Thank you for the land use application referral. At your request and in accordance to Senate Bill 35 (1972) this office has reviewed the materials submitted by your office and considered the geologic hazards and geologic conditions that may affect the land use development. The reports submitted are the same that we reviewed in our 2006 review of hon Bridge Phase 2 (CGS LUR No. GA-06-0006) dated December 27,2005 addressed to Richard Wheeler. The CGS has also previously reviewed the entire sketch development when it was previously called the Rose Ranch Development, with the first letter to Garfield County Planning Department on October 30,1997 (CGS LUR No. GA-98-0006). Phase 3 is the northernmost portion of Rose Ranch. A site specific investigation for Phase 3 was not submitted. Please consider the following In earlier reviews from this office, the CGS made its warnings clear that the major geologic hazards that will likely impact this development are debris flows, sinkholes and other subsidence phenomena related to evaporite bedrock dissolution (evaporite karst), and collapsible soils. HP Geotech also commented at length about these hazards and the potential risks. Concerns with debris flow hazards have been addressed by mitigation designed by High County Engineering. Other hazards and risk remains. The honbridge development is located in an area along the Roaring Fork River valley that has the highest density of sinkholes in Colorado. Collapsible soils are dry, lower density, soil where the soil structure collapses in on itself,loses volume, and densifies when it becomes wet. Commonly called hydrocompactive soil, this type of soil thickly mantles CGS LUR No. GA-07-0011 DEPARTMENT OF lrgal: NW%, Sec. 1, iec. 12,T7S, R89w NATURAL May 17,2007 Mr. Craig Richardson Garfield County Building and Planning Department 109 8t Street, Suite 201 Glenwood Springs, CO 81601 RE: Geologic Hazards Review of Iron Bridge (Rose Ranch) Phase 3. Dear Mr. Richardson, most of the honbridge development. Soil collapse manifests itself as ground settlement. It is our understanding that these geologic hazards have plagued developed portions of Iron Bridge since development began in the early 2000s. Settlement damage has occurred due to collapsible soil and recent spontaneous ground openings occurred in early 2005 that damaged thi Ironbridge golf club facilities (see photo) just above Phase 3. HP Geotech referenced another smalllr sinkhole that opened below the large one near the Phase 3 parcel. We donrt not know the location of this newer sinkhole(s) since a revised report has not been completed. HP Geotech, in their earlier preliminary reports, mapped several small and larger sized sinkholes throughout Phase 3 and made recommendation that these sinkhole locations should be avoided byresidential structures (HP Geotech report dated February 12, 1998, Job No. 197 327). Thatdoesn't appear to be the case. Lot layouts seem to have been placed on these mapped sinkhole locations. Without the locations of the mapped sinkholes shown on the plat, we can't be certain that the 20-foot setback has been adhered to. In our last review correspondence to the county, we stated: As far as we know, the northern parcel did not receive the level of subsurface investigations into bedrock that the southern parcel of Filing I and the recreational facility did. We believe that, with the recent nearby occurrences of two spontaneous - sinkholes (generally a rare phenomenon even in the evaporite karst terrain of the Roaring Firk River valley), and other historic sinkholes mapped in the areafrom HP Geotech's 1997 report, a similar level of subsurface investigations is warranted. We ,3:,i I' .lt*.'. :Ss "h Photo #1. January 9,2005 sinkhole at Ironbridge golfclub facility. believe the risk of subsidence is more elevated here than in other areas of the I ronbridge Dev elopment. Closing comments Garfield County has prudently required notes on the plat that indemnifies the county against damages related to subsidence or settlement related to the geologic hazards mentioned above. We feel the risk of damage by settlement or ground subsidence to one or more homes within Phase 3 is high over the average lifespan of a residential structure. It is important that prospective homeowners are aware of these waming and have the time to judge this risk for themselves, or hire an independent consultant to evaluate the risk for them. For development to proceed, we recoflrmend the county require the following actions and provisions: Final plan sheets should show the locations of the sinkholes mapped by HP Geotech, and building footprints for the lots that may be impacted; Ttre drainage, grading, wet utility construction, and geotechnical recommendation be complied with; There hive been more culrent reports by HP Geotech for Phase 1 (report date{ May 31, 2OO5 *Job No. 105 115-3) and the Recreational Facility (report dated. June 30, 2005). There should be an updated assessment by HP Geotech to insure that the same level of geotechnical subsurface investigation is completed for the current development plan for Phase 3. Garfield County should have, in plan documents, an answer to the following question: Does HP Geotech still consider the risk of ground subsidence related to evaporate dissolution to be "low" for Phase 3; A geotechnical consultant must be retained to inspect and evaluate all raw grading surfaces, cutslopes, utility ditches, foundation, and any other excavations before covered with structural fill, topsoil, erosion blankets, foundation elements, etc. Such an inspection by a knowledgeable engineering geologist or geotechnical engineer will insure, as best as possible, that exposed ground and soil conditions, which may indicate local ground subsidence, will be discovered and appropriately addressed. We believe the inspections are so important that the county should consider making it a development requirement; Site-specific foundation investigations be mandated for the individual sites and, most importantly; There is adequate disclosure of the potential risks to home owners concerning potential settlement from collapsible soils and risk of spontaneous glound openings related to evaporite karst phenomena. Prospective home and lot owners must be made aware that normal homeowner's insurance does not cover damages related to ground movements, including naturally occurring sinkholes. 1) 2) 3) 4) s) 6) If any interested party has any questions about this review letter, please contact this office at (303) 866-3551 or e-mail: ionathan.white@state.co.us Sincerely, Jonathan L. White Senior Engineering Geologist Cc: M. Sares, CGS EEG supervisor, e-mail attachment only V4rr)f,s>es 6.*:/\ a-_. ,ef, r<r>-$ a.s tr{e-C( fu--JrB t_Go I __ ul6 a ---., .,_..*_--_L ._-,..*-.. .,:_ - ---. -l--- " - ' I tt, -,.-i !*..+,. .-i+*+i. Page I ofl Graig Richardson From: Sent: to: Su$ct: Jim Rada Friday, May 11,2007 1:09 PM Craig Richardson lron Bridge Phase 3 Atlachmente: Jim Rada.vc{ Craig, Unless I am missing something I have no substantial comments on this submittal. The following items are general guidance. I, A CDPHE Consfuction Stormwater prmit or an amendment to an existing permit should be in phce ftr approval. 2. Application br or a letter stating no need for a construction permit ftom the CDPHE Air Pollution Conhol Divlsion should be submitted br final apprcval. 3. I have requested a copy of the Roaring Fork Water and Sanitation Distict's most reent consumor confidence rcport. The water quality data submitted is quile old and really does not serve itrs purpose br a 2007 application. 4. Developers need to abide by the Colorado noise statutes. 5. Storage of any hazardous materials on site during development needs b be managed in accordance with applicable Federal, Stah and locallaws and regulations. Thanks for the opportunity b reviar this application. Jim Rada, REHS Environmental Health Manager Garfield County Public Health 195 W 14h Street Rifle, CO 81650 Phone 970625-5200 x81 1 3 Cell 970-319-1579 Fax 970€25€304 Email jr"@ Web www.garfield-county.com yttnwT A5/23/2827 84:55 62iB6Z7 I ROAD AND BRIDGE It ior irnoh, [10 Cfo Oru! Jarrchrl0 lrmEldlf Dr Elru'np6 FBrfiE, cO lt69l lJtMcRilchU,G OdoD.r 30, e006 tufirE fofiesnmmof C/o lrf. EGk l-dflr, FO Eox ss{0 Be88lt, CO il$al Hr, Lrfieu; llm *fltng you -fib lrtrrr h.rupon$ tc yorrl httBr dcmd ArArnt 30, 2006. w. rr' concnrrrd by the shEmgntE rhdde ln pur lefir r w bdln/l rrvffd m ur rrrourea, I trs\n prw,idcd- trOorumancy Vtt wne eslficfin 6, ih3 brE you lrrrru nfatlsd h gnr rm. We r,o,Id sugErd r rnocung ln trc nirfut o b |[d\t hi tnlccrrEn rnemfllG maoe in your l€ffi| !n pur l€qt ft sEtE thd W Cmuvenoy'ril rEyrtrlrvfao E fit $e for ruoannqndatbrs on nrclffi.Lp tflofir, On lmr tS, Amt, $,a r.olfl, rn )ffiit fom yE Jlcf ,BtBrgrrmg }q , enrom o,r,tr plte.of fralr_dhpirpr d tl: nofi ffid dthr prupltty es wdiar da#r pdtrn by fr6i rh,E b;rti m Uydtr ft31 ra*rd d rirry bsr* chan+p €ffurb. t pcngrb collhild feu ir, .lunl lC, aogg via dronemd Hnel to rlicafic )firr cilftffllt om hEs hr${Jsi. ln my pturc ms5e.gc, I aLrld you !o dl| tacthrl tr wuuid mflr Er fi9fifig ln ou rmortd ru_und cJ ds*up wtrhh trd.dod $c ruh6r1 af Frngend rteFlng ahfd rffod dong hr {ver. I rryn drylv ugrr wtrn ur ranoEi a re rFas3 otrpphg- Frr. * fir comcnanov nouerho. On Juty 6, 2006, un tfuiffi ow rivr dcr{re cttdih. Vitfrn "ehed €mplged 6s ralwrl S$r Fst orurye rrcnr tnd"rh'tr ba,r$ i trnlicted lur.[ iimrrflcff,ge *d infonnd you. thst uf, nlle cornpbu ulfi rumord d lhl gr* ollopnfr anclfrt ,iwwilt n Uil mEdl tbgts of our rlvrr chrt*p iftrtr end hvitad the Coninnncy io &me to thr aftrana insped our FpgFeEE. tftfp*ry.lq J*4rb EorHDh fronr [Frg Crnwrnncy oonhq;d me 19 mtrqo r Cte vtdt, On JWlll {ts tt ?00prn, ldr, Bamildn ftx vfii mc on slb. Wr ftrt rwieri,ad tu nrEr Orrn+p err,rtion.Tlb indJdod t 6ur d trr dwr cilridtr rrtt.tlft hc dr*gp ',m Hkhg phce, a ,wla, oiOiClcfirrpkr _|4 a medhg wittr our onEaolor, .rt0 Tluc ScNiEa. JEG Tm itr\4oc ir r hlOhty quaunel fw :[=I!LTI it_T41tr_ 4qI ilF$, County b €nad ineir rrnuat r'.. ra.fairiE u,.-ErfltFtlrcr oor-rtor. ThE ha! ! mqq fLEiil m or |.NHon o{ thE co'1rrictor due to the geniltv,ty of fic Ittr.k F.ry perfomed. Mr. Borrtrin, JCB true Scrvka rnd I dl*rrrrH an nngflr ttrc gmoi * meuort 'riru pil{uffird. _ [e. Borfllbln'r onty coflcem wns thd rrw hed mel ,n5 ttre DegrGror otwrdh ot ttr rcope d our rrcrlc I iformid Mr. Bonnnin rut rro. to mc omnnnffiiiii ourgirn_{P dttt!, I lnd mel wilh Mr. Jo}rn Gruvm d$c Drpst{nfir of wtdltfa h dlsersa fic ai& or lt-tc.clrrn uP ortrlion.^ F-l.u ony Fnc{p nns thrt uru tcivc rome ot the ;d$iirg qosgitor niung b rde b pocdW r.Ec, Wc d1cl rwlarvcd tho elln up d rrc om* cupphga. *t Mr,lomitidr end thooonservans/t ttqusslr ue moHlind beok lrrto ora snB bHrpbt['nArnrna*r*-ior aOOltlonrldr*r'tlp d ttt f|3r cilppingr. hry-ltul'up oErathnlilted fu rrqc hm trilo nrofihr. Ourfig thet trme qr were wrbd by$ry q*Ity ffilanb, the DOVV, and the Gerf,dd Cnnty Fh? D?pt ir of fnr rgrncicc tuid;imd$erryft bdtlg ool*'rctrdrrTd vrrrrfrnr wlfi hr rcopr rrfo progrbfi of he dean+n tn .ao'[,fr a,$r,rrmmt wtth you Fot/tdrc hat fis Comenancy tprnO ub fdex mun pcr mofi{r.,ronturnrn Eui67tsr\n!hn oasornent eld hi Hfu. l'{trcn Fputtlott Zoni, ro m nrtrilly *dr?red-tdi y"1, n ovs,rnd rur usk il rhh fim flco. I wrr rtro ir,tu r1od ilrat p.r ,;y,outi ba iHtie rtii irvi to]iirr* o,"progrEE3. we hec fipegrcd ilm pu wnrld oontrc{ ue inriunru nrr*e u,H e pruotcm, over the PAGE 03 05/23/2487 84:55 I 6258627 ROAD AND BRIDGE BorrrH( Forx loHlErvAHcv Exmutive Director Fosr OrrlcE Box ,1q9 | E*t,r'-r, Cot.oRrpo Etorr g7o lgt1.-nga r . g7o I gt7-tt6q FAx . E-MAIL: inlodrouingfotk,org www.roaringfork,org PAGE A2 ,nrugust 30,2005 David A, loaeph LE Rose Rarrh, LLC 1007\AreetBarrk Road Ctertwood Springs, CO 8160f Dear David, The-Roarlrrg Fork Conocr{rncy ir diaplerred with end did not recomrnend or .urriura th* *'ecetrt vegetetion i{rinot'El te thc crxtttlt that ttras coru{uetd otong the Rorrlng Fork Rlver et Ircn Brldgc. In Stc intHrl pharcs of whrt wat t0 be a selective cuttingof invativ: Ruuiarrolive, rrewBtG csrtacted by lron Eridg_e,by phone. We mrdl Eorne verbrl recommrndatiotu, but we were never imtEd lor i totlrnet site vitit end rrcomtntrtdaticrre. Fotlowing the phre clll, we wtlt eonfident htt Iron Bridgn weo working cloaety wtth Garfield Comty vegEtation manrg?mcnt while temoving invufvc Rrr*ien'olive, In sub*quent weolu- fotlmving the initiei refirovd of invdsive Rrrrcian+hv€, coPiou3 amowrtr of native silver brtrffel,o berry rnd nrtlve nrrrowlmf eottonwood (live treer end utanding deed snags) were rerrorred dong tlre rivcr bank. Tfu rcsult ia.e temeni'otre lor oltraUitet fq riildlife cudr es bald eaglet, and the Iom qI bemcficial ehade created by the cenopy criticd to cold wattf rquatic keltn errd a tluiving trout populrtton. Although, s*notd prior, we have ng legd r€courue to prottiUit Ere cti,aring of, rutive veg:trtion, we bdtwt lt ig ln fie beat lnteneut of Iron Bridgs to preserye as much native habitet aD Poeoiblc. We appteciate your att€nHon to scve*rl eornplatne releted to removal of a lrrge pile oI grasr clippings along the Rorrin6 Fork, and turrrncrrd you o1 t! -yern+rel *f invigivr 1.'egPjrtion, The Cangen'en-rlnrrrruld IiLe r.o wot* with- )T ttr t6 avoid eny further rcmoval d nativc vegetltion rlong the nver ii Incn Bfidge. Therefor€, rrru offcr our ecologicrl setrrlces frce oI chir6€ it efiy time they are n:ded. Flee+ do not hesitrtc to cell on uc Ior rny futulc ecologlcal congultation rcgarding nstive vegetrtion, 85/23/2097 04:55 6258527 ,t ROAD AND BR]DGE PAGE Z4 1A ROSE RAllGl{r lJ.C Ll ir$i.trh, U.c CD Olljlt.J.c.thrrorutfirlr h trtrr{,ood lortnt[, CO tlCol RIiilF,? liiHFlj OctobsI,2005 l,tr-Msd(Em ffi#PHrrrdrngtFhnt*t Glentltod SflfiS, CO 81611 DmrMxk: c[I $ i iit05 tJ,.ii : : ' EUlLtiiii,J * ,,u., .i..,,ti,.,i Ifcrl yur fcr trhlng tr time BE drer dry b rpork wilh me trgtrlfrg lruSrldgr {rd or, ch*up efioils dmg tE rh,g. Prr our Erirartl[on. I fm,E dldnd 0rc lstEr EBrt t, trt by rle Rilfng Fofl( Comrwaney *ttl my r€spotlge lem mOrnlng fil l*u." thr ncpol*c lril*ufirt tcnt on $ptorilbcr fZ'*ro rrl lrrw h*l no rotporge fiiln ilre Corronnngy. I harc ro-geflt fie le0tr vl clillrd mC. My reponrc lctlcr breftdly *l([tstac fl oonceru b(,t I rffiJld lle h udd s hln oomrnatr. I Epofc u,ilh Utc DOVI, end t'Ey tprc ffiEd tltgy baBrc url hfit uilard r lrrgr rmanrt of livc h*s dffig hr Iii,T blnk. I orn ooofirhrtty $aE tret hh b not ttte. The rub d thumb rirp trlc wNr I t'rr b6r hS eny lblhge, $i utrrd oniy tirn lht dcsd u,Ed sff. f ho treE wEB d€sd, ulE uallcl rafilwr l, Thb was meani to impravE the hcdh d hc $ilO by ruftovtlrg dfld or dlrrtr<l iimbt ffrd hirnhg dd lhc drrd hiiD ro [r llw onis oorld fldrlrh. thry rn Cro tffirfl h* ro nmwcd ulrddiluih ebrg fie rlvr Dr1k r*l rltnintEd ffir Er !h*,s &tllhg firh. We only emorcd Russbn Olh,l dfffi rt he rivrc Gdgr t***r b ptrt 0f ow PUD Equ*tltrrm, Wr dH rttiou! riqrl e 50 yerd lerrgil' d undabrurh oF on d trr ilor. hJt hb ryE wra d bsgt 60 llurn ths dt/or bank and t)' lbort 11. '[ht DOt/l/ oarpt mnfirm hov mudr unCafbtulf or hort, ffirry fl.a ilrry frlnk ua hrve rsrnfi,Ed. TIly jutt try Uret Utry mmcmber mm thrn nlut ie fioru. I hhl ht p.tt ption le hrt whrfl pt go to the rltr rnd rrl thr chbrb pffrs, yfiJ tlrink 'rnruw, they out a lot d stut ant". ln.fact 95tt of fre dlbrl rrvut m the gnound. Nona d hr drbrtr hrw brerr ilrovrd frcfil ha tlh and w htve htentlonelly not. burn*l tnyrhhgto dEts. lt b obvlow uttrn oblrvlrU hr{rDrf illtfiB mil.rlrl her Dttn clmdfor a long6 long timr. Thr Conseruarrcy alatee h thair lgtter ftil us remontl large amounh d $ilwr BrfhloBffry Silvff Fufto Errry ir urry tlntltr E &JsBHt Oh,t h ippirffcc and any, if any, thtt wr{ ,ultovtd, wts dono tc in r eood lill sfiuf b offiply rvlh hG PUD requlrrnrnl b nfiotc tluqghn Otvr, Thr Qonrmnncy osfi1ot trl ur trmr mufi tfiey tHnk rws rsmonsd rrd'l do not thlnk it udC riucfr et El W. hrtrr nanr Uisd to tfrB rtlnhhU un unn doirg rt |tonbrHge wfh rs$rd0 to ulr B$l.. I hrd ht DCilt, alto trr tilD rrH gol [* fiffmrnts. Wewru a oouple d de],e nb0rg doautp rn6 I UECGd hem htqrgh rxdy ut* wr umr goirB to rb, t dd hc s{rtu with lte Ooruenrancy. I dlo' rtd ttrcrn rradywhet $!0 rr,trt goitg b e, ThG ffid( boi( ovtr hi,E mffitllt b GofirilEh ard vra nanr htrtl r fiirg ftorn either agrey. I h$,r urk;d an thc Rfimg Fort Vdhy rnd Ergc County for mrny lclfit mr rnd ft"tlly urulrffind thr !.nrlrw rlitrne d hh type of vrprk. ThEl hr utry rc lrMtH thc DOI/V aml tha Corumtnrrcy b tE $ts fot mk eorlmfill ft wor,rlrl hrvc drdly tekcn htu cmridrrrlfrrn fiy of thck reqr.Ett6. We uoird prurposd t tnEiiing rrulth the Cut*rtutey, flil DOW,ild hB mutty b H hdd on{tt E vltuv tm aIftr$tg ttfi $c fi tio aifi't Goms to ssne rwdutirrn of thh terw, I wurrd t*Etooma yur [prrEhtr on dir mtmr. ygu mry rrrcn mr at (719)2a&Ec3g, Olu {Hn, mat* yu rr iour tme rcgr{|ry hlr lrrw. Slnarnha {; Dar,ldA. LBRo]. R.fffi,LLC STATE OF COLOTUDO Bill Ritter, Jr,, Governor James B, Martin, Executiv€ Director Dedicateclito protecting and improving the health and environment of the people of Colorado 4300 Cherry Creet< Or. S. t"Uor"tory Services Division Denver, Colorado 80246-1530 8100 Lowry Blvd. Phone(303)692.2000 Denver,Colorado80230-6928 TDD Line (303) 691-200 (303) 692-3090 Loeated in Glendale, Colorado http/Avww.cdphestate.c!. us May 4,2407 Mr. David Joseph, Director of Development LB Rose Ranch, LLC 410 Ironbridge Drive Glenwood Springs, CO 81601 Re: Site Application and Design Approval #4921 Garfield County Dear Mr. Joseph: ColoradoDepar,tment ofl\rblicHsldr andlnvironment 2. 3. RECEIVED [rAy I 4 2007 ,',f-Tit?ff,Y^il# The Water Quality Control Division has reviewed and evaluated your site application and supporting documentation for a lift station (lift station #2) located in the SW % of SE % of Section 1, Township 7 South, Range 89 West serving the Ironbridge PUD and discharging to Prngatory Metropolitan District Wastewater Treatment Facility. We find your application to be generally in conformance with the Water Quality Control Commission's "Site Location and Design Approval Regulations for Domestic Wastewater Treatment Works." Therefore, the site application is conditionally approved with the following conditions listed below. l. Based upon application information, the WWTF design will be for: Hydraulic Design Capacity -72,000 gpd (maximum monthly average) Peak Hydraulic Capacity - 108,000 gpd Organic capacity - lg2lbs. BOD5/day Treatment processes to be used - Lift station and force main The design (construction plans and specifications) for the treatment works is approved concurrently with this site location approval. The Division must approve all construction change orders initiating variances from the approved plans and specifications. The applicant's registered engineer must furnish a statement prior to the commencement of operation stating that the facilities were constructed in conformance with approved plans, specifications, and change orders. LB Rose Ranch, LLC sA# 4921 Page2 of2 4. This site location approval will expire one year from the date of this letter if constuction of the project has not cofirmenced by that date. If constnrction will not corlmence on or before the expiration date, you must request a time extension prior to the expiration date. If you do not request the extension prior to the expiration date, then you must reapply. Construction is defined as entering into a contract for the erection or physical placement of materials, equipment, piping, earthworlg or buildings that are to be part of a domestic wastewater treaffient works. The conditions of approval, including construction of facilities with capacities in excess ofthe above limitations, are enforceable by the Division. The Division may bring an enforcement action including the assessment of penalties if these conditions are not met. In accordance with Colorado Water quafity Contol Commission regulations, this approval is subject to appeal as stated under Section 22.3 (15) of "Site Application and Design Approval Regulations for Domestic Wastewater Treafirent Works'. This approval does not relieve the owner from compliance with all Federal, State, or local regulations prior to construction nor from responsibility for proper engineering, consfiuction, and operation of the facility. Attached to this letter you will frnd a Customer Satisfaction Survey. We would greatly appreciate it if you would take a few moments to complete this survey and retum it to us. Simply fill out the fomt, fold it according to the directions and drop it in the mail. The postage is already paid! Thank you for your time. Sincerely, q)-, ,Jafuru/,Y7 David Akers Clean Water Facilities Program Manager Water Quality Contol Division DA:rkk Enclosure Dirk Gosda" P.8,, High County Engineering, Inc., 1517 Blake Avenue, Suite l0l, Glenwood Springs, CO 81601, dsurvey Garfield County Andrew Ross, Unit Manager, Permits Section Mmk Kadnuclg Disfrict Engineer, WQCD Kent Kuster, Environmental Protection Specialist, WQCD