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4 - Call Up: Elmer's Two Mile Creek Floodplain Permit (LUR2008-00068) MEMORANDUM TO: Planning Board FROM: Katie Knapp, Civil Engineer, Floodplain and Wetlands Permitting DATE: August 22, 2008 SUBJECT: Call Up Item: Elmer's Two Mile Creek, Floodplain Development Permit (LUR2008-00068) This decision may be called up before Planning Board on or before September 5, 2008 A Floodplain Development Permit was approved by Planning and Development staff on August 22, 2008. The project includes channel improvements from upstream of Glenwood Drive to Goose Creek and a Conditional Letter of Map Revision (CLOMR) submittal to FEMA for hydraulic modeling and floodplain map revisions for the entire Elmer's Two Mile Creek floodplain. The proposed channel improvements include the Department of Utilities "Elmer's Two Mile Trail Connection and Drainageway" CIP construction which starts at the confluence of Elmer's "Two Mile Creek and Goose Creek and extends to Glenwood Drive. This project includes constructing box culverts, structural walled channel, grass-lined wetland bottom channel and a bridge under Valmont Road. The project construction drawings are attached. The floodplain development permit also includes the "Elmer's Two IY1ile Creek Upstream of Glenwood Drive" channel improvements proposed by the Urban Drainage and Flood Control District (UDFCD). This project begins approximately 195 feet upstream from Glenwood Drive, extends 200 feet upstream and includes removal of a concrete lined trickle channel, removal of a box culvert and construction of a grass-lined wetlands bottom chanxrel with sections of stepped boulder retaining walls. The project construction drawings are attached. A hydraulic analysis was performed for the entire Elmer's Two Mile Canyon Creek to update the floodplain maps due to new hydrology, updated topographic information and the proposed channel improvement projects. The revised floodplain maps are attached. This floodplain development permit was approved by Planning and Development Services staff on August 22, 2008, and the decision may be called up before Planning Board on or before September 5, 2008. There is one Planning Board meeting within the 14-day call-up period on September 4, 2008. Questions regarding this Floodplain Variance should be directed to Katie Knapp in Planning and Development Services at 303-441-3273 or knappk@bouldercolorado.gov. CITY OF BOULDER r~~ Planning and Development Services 1739 Broadway, Third Floor P.O. Box 791, Boulder, CO 80306-0791 phone 303-441-1880 fax 303-441-3241 web boulderplandevelop.net Land Use Review Floodplain Development Permit Date Issued: August 22, 2008 Expiration Date: August 23, 2011 (Pursuant to Subsection 9-3-6-(e}, B.R.C. 1981) Permit Number: LUR2008-00068 Contact Information CITY OF BOULDER, PW UTILITIES PO BOX 791 BOULDER, CO $0306 303-441-4232 Eric Lessard Project Information Location: ELMER TWO MILE FLOODWORK Legal Description: Description of Work: Floodplain development permit for Elmer's Two Mile Creek. Type of Floodplain Permit: Floodplain Review W/Analysis Creek Name: Two Mile Flood Protection Elevation: Not applicable Conditions of Approval The proposed project/activity is approved on the basis that it satisfies applicable requirements of Chapter 9-3-2, "Floodplain Regulations," Boulder Revised Code 1981. Other floodplain requirements as set forth in Chapter 9-3-2 which are not specifically outlined in the conditions of approval below remain applicable to this project/activity. Improvements shall be constructed in accordance with the plans submitted as part of the floodplain development permit application, prepared by ASCG, Inc., dated July 14, 2008. The applicant is required to submit as-built drawings and written documentation certifying that the improvements have been constructed in conformance with all applicable requirements of this permit. A city of Boulder wetland permit is required prior to construction. The floodplain development permit if not appealed, is final 14 days after notification of issuance. t a _ ~ i .Li ADO :-1- _ I Ilr!I I 'j I h' ~ i L I ~•t $ c ii ' COaVEGi CONCRETE TRAIL' SO I I ~ ~ ~ 1 ~ / ~ ~ ~ ~ ~ S ENISTING GODS'' CREEK TRAIL ~ ~ I!1 ' 0 ! \ iRANAT10N FROL! 10' Y10E TO t2' i 1 I `I 'STA; ~61~62 TO STp. 52+t8. STEP;• M ~ ~J" ~ ~ ~ ;W1DEi8TA. O+DO ~TO STA 0+2D. Uuii9,OF~~ ~I TOP LF BOULDER REINNIN6 wAl" `-J ~ - ~ ~ I + _ 20~ V 0, 20 ~ qD ~ I ~ GRAUIN~C ELEVAl10N FROM 489.6 TO 292.1 INy. ~ ~ ~ ~ - I •Y~y1..._~~~ P 1 f~K1G: ~ •,6 INCRENENT$,-'EVCRY B FEET. . i ~ ~ ~ ~ .I l' ~ I 1 - Hcn ~ zD ram; i i c cReTf TRAA ~ S`r'-' ` I, ~ hi~ ! 1- I I ~ ~ - ~ I j ~ Il_. m _ AEC0.NSTRUCT B k NR OITCx STA J~Jb ~ ~~rf ^ ~ I I I ! i ~ l i I - I I I \ ~ gr 1 TO STA. 5+15. 4EE` DWG: CII) ~d3. - ^ ~.~'_~5~.~~-• ! ~ - b ""~i - ~o o i1 ~1`I PROFILE ANO TYP. SECTIONS 1 - ~ ~R"• l I / - o-' I I ' r+ p ~ 7 v ^ ~ TRA&J RACK: ~ SEE DWG. ~ ~ i 80ULDER~~ I 1 t"or' I; ~ I ~ R ~ I I ~flIED iYPE~ L SC~LdllPkn -011CH$ r ^ ~ 't'_-t- I -I CH 9 fOR DE~$.-i W-5 RETAIPoNO WALL. I - ~ /A.,l O. ¢ . I B TTOU PROtECTI rm. ~DRI Ef105 ~~~Jt ~ - ~ .T -I-- - - ;TrnlcuBOm,r ~ a t ~ a v 1 s, `•I ~ ~-I 1 - I _ ~I -_t~ - C OF ANNEL 287.1 ` ~ i ~ ~ 0 GDNCRETE CA? - I - 1 I I I ~ ' ! - ~ _ _ t ~ ~ fi ~ Q,' : 1 tl 12 t - - -I I ! ~ ! 1 ~ ~,r- - INLET lf. _ ' ~ - I .l, y\ \ ~t i _ _ - ! I - ~ - ~ ~ - F 15 PVC TYPE 13 - PROTECT ~ , ~ p ~ J i I i - ! "_I _ -W-7-_-~~- - _,159x. L - - _ TREES - \ ~ ? P _ - lANCR~tE CAP - ~ - ~ -=J , 283,53. PLACE 12~ GROUTED ! ~ R6 \ ~ ~ ~r-". ` _ s - _INl{i-TYP~I$~ i ^-_-_^r- ^ ~ ~ _ _ ~ BOULDER $ILL`ACROSS ~ i ~ ~ I ~ ~ _ - u+lEi TY~E R ~'+o a - - _ - ! ~ LOW FLOW AT $iA. 510 ~ ~ ~ Z ~ ~ s - ~ ~ _ ~ _ _ a ~ T,bA.a528J.90.~y SEE DWG. - ~ - ~CULVERtPREOAS BOX I m _ _--0 _ l~ II _ -CH7 F R DETAIL:. ~ ~ _ _ _ _ o.., Q ~ - tiV'~ c'~i I _ a_____-_ .~`i ~ - ~ CHANNEL __s.- ~ ~ -REUOYE 6t LF DF E%ISONG ~ 'I - I ~ ~ _ ~ BWLOEREOGErTYP.EACH', -0 a _ S - m ' SIDE OE LOW,FtOW~ - _ _ _Il ~ ~ _ ! - o TIfIN 8 LD~R,, r - 1---- 80% -w -f~'., ~ L~~ 00U~ t ~RENOVE.35f~SF ~ ~ ~ ~ - ~ - . -F--~ " ~ - m 30,1 ~ ddA1N ,EDGE~T041ATCH ~ ~ \ = e ~I, V _ n..01.1a-- ~--1-~~*-' TRnI...., •~EICVATIONS Oi~ _ ~F - _ I _ _ - - ~ I E%IS11ivC80'JIDERR~'~ `Df~E%¢TING-1B'.:'. _ _ ~ - JOD7 - R6%y-_ ~ - O: STA 51+00:-~,'' ~ _90ULOERS' r.. ,.r• _ _-~~6.3._5a.'. I 1 ^ O F _ _ . - - _ - - - - _ ----A~ - 30Idi' _ r S I: _ , _ ~ ~t--}:.:'e;ioi,•, - -~_,__r - _ ~ I - ~ w PROPOSED'100-KAR ~ `I~ STA. 51+tO-i05rA Z•a ''?`i~;i~'.= ,',:,I300.7y.-P T _ 6 1' _ _ _ -FLOODPUIN_U4115 51~J7-TOP Of~BOULOER ' _ r = - i. 7 Si i ~ ~ ~ \:94 - _ _ - - - - - - - ~ ~ I _ - - 1RETAINING WALL TO ~ - O - ..y _ _ _ - _ •I -WATCH ELEVATIONS CF _ I "2 - O t_ ~ _ _ t2 W1DE ~ E>nS11NG GROUND . - - - ETE - _ ~ - _ _ EONCRETE. ~ a ~ ! W__. 1 - - - - - RETAINING WAtI ? - SOUTH ACEESSiRIJI ~ I - - 00 NDT DISTU - ~ ~ i ~ PEOCSTRIAN BRIDGE - '~I^ x_20 _ ~ _ \ - E:ISIINC SHR B BE~ ~ j' _ _ - I - `1 _ X O sp4q 4 - I 18 AIIN UNGAOUIEO C _ _ - - ~e1i _1~.. STA''S1+J7 TO~STp 51170 I - - BURIED i,YPE L SOIL \ - - a3pypB ~ ~ ~ y I , $lEP TOP-Of 90U10ER + - -BURIED TYPE N STA 52+20 10 RIPRAP BANK PROTECAON• " _ - - - - - - - ' SOIL RIPRAP. CN5 1, ' > ~ Sia, 52+50.. ~ ~ _ - ~ RETNNiN6 WALL E~:Ei'AiION A ~+IS Q a - ~ - - - - FROLI 288.5 TO 291.0 IN 8' 3 STA. 51+70..10 •U I a I I `a,,,,,- u-~^ ~y y'~ o -Z. QMI STA S2+ 0. Cflt ! ~ Q - ~-_MCREuENTS EVERY 6-8 FEET. } - ~ ~ „I ~ ~ ~ 1 - A~ - - i .STA 51+70 TO STA 52;18 A - t nl ~ _ GRADUALLY $Ti,P_TOP~F. \ i ij _ BOULDER RETAiMIkB WALL I ~ ~ ELEYAAON FROAi'29'1,O TO 292,7. ~ ~ ~ I - ~ ~ `sr sAHlratY j ` ~ ~ ~ v vv r v sfilER~rottc ssl ! ' i ` ~ ~~v~\Cv l~ v FDR PROfILf I ~ ~ ~ 1 9 BURIED TYPE L SOIL PoPRAP ~ n fry 'Pfd ~A.P fOR $WIH BANK STA, ~ ^ 9 OC d9 4+25 TO STA S+iS. ~ ~ W Of 9~, _ 5304- - - - - - - - .I ~ z EkISTINC CRAOE _ d _ . . _ 100-YR DESIGN O = 83 CFS ~ I u PEDESTRiA y - w t ' - - - - w - ~i' •-Wu 5304 I I-- 1GYR DESIGN-0 12'CFS 1201 I o ~ - - YJ _PRDPOS~O. 15' - - I - ! Rl,. p I - - ° --BRIO _ SANITARY SEWER _ _ _ _ z - ~ 5302 I u u - 292.It _ - 5302:-- 2-YR DESIGN-Da 1 i CFS- - ~ - 0 - ~ SJOD oZ-i ! - S P8LAN10 ~DRA19 CF~~ i-,NN - - o ABUTIaOCNT I W PR CRA~C d I -I z ---N_-~I_---- I-~'"I-°---i ~ -~.I _SU;3 530D ' EACE_ 5298 m --j - - 1 J - - ~ - - - ~ - - - - - - I - - ~ _ - 5288 I_ 4 srRUCruRAt k - \ - _ - I i I _ IoD-Ya roRAUUC -~I I 5296 - in Z- i 1 ~ WQ -WALL. TYP. f- ~ - - ~ - i --GRADE LNE--- - j 1 - n n MATCH INVERT OF 1 -__--I WF- - I~ _ - u 15itNG'fOW~FLViY- ' - - _ 96 5291._ Ip0- WA1CR I SS ~ - \ 9-_/_ . _ _ . _ 94 2- i _CHANN0. 5287.51 - _ - _ - _ _ _ - - ~ - _ _ _ - ~ SURfA I --aa I - I ~ / ~ I _ I i n° I ~ 52 O n 5292 ~ _ I I_.-. _ 'I - i _ - ~ I ~ - n I . C I i n. d m 92 I I _ - -I - - - - - - - - I ~ ~ _ _ - - - - ~ - - -~L-- - ~ 52 51j. >aSNNG ORAOE i I ~ I I I i m S 5290 5290 ! t2' GROUTED P(70POSE0. I _ I 1 I -BOUIOER Sttl CHANNEL I _ - ~ I I 5288 - ~ -INV.-5287.5 ~ 1 _ _ _ _ RECONSTRy_CT OITC . SEE i ! I I n. 5_ I gg 5 I T 0-R:=528790 INVERT - L - - ~ _ CONCRETE CAP ST ~I, _ DWG, GH7 FOR PR ILA j - - - - - - I - - - - - - - a ~ 2 - I i _ ~ _ SJ+01 TO STA. SJ+9 i ~ ANO-TYP: S.CTION . - ~ I i ~ - - - 1 _I - I --i I - 5286 5268 0.0% I -I .1.._-.. ----f-- - - _ 1 fA 5281 i I _ - j ~ i I~I- ~ - - ~ ~ I - - - - - I 5284 - _ IN _ - I I - -SB9 ELF 13' X-S'-PRECAST BO~I~CU6VERi- - 5282 - I -1 - f'~- - 52 JEGN IIG STA. 5N00 - V. 528]5 ) - ~ _ ~ ! - ~ B2 I- n rr I- - I I __-I_.__.- ~L iIAdGR D'Au+A,,.wAY PLAN STA. 2+30 I I I 51+00 51.PJ St+60 52+00 52+10 52+80 5J+2D 57+60 51+00 51+40 54+80 55+20 55+60 56+00 56+4D 56+80 Computer File Information Sheet Revisions `\1y Dr BD~IpF~ AS CONSTRUCTED ELMER'S 2 MILS TRAiL CONNECT1dN Project No./Code Creation Dote; August 08 Initials: Q A S C G Lost Modi(icotion Dole: Initials: ~ f N C 0 A P 0 RA1' 8 D ' ' No Revisions: CHANNEL PLAN AND PROFILE STE M 110-050 Full Path: ~ ~ ~ a z 0 ~ Revised: Issued by: 15016 INNd lrt 9y.ud A.em~. 6~!te 500 / Drawing File Name: 0 n,,~,,,, d~ee p 0 Revised: Acod VeF. Scale: Units: rA°"'~~~`°°°'"'~"4°°"°° S OtiQP Void: Sheet Number 0 Sheet Subsea: Channel Subset Sheets: CH 1 OF 11 f A I, - - ;q I i - 11 I I r ~ 1~ _ ll I I ~ ~ ~I ~ r I, - T / . - . _ _ I_ ~nT ~ - F Z ~ _ _ I ` ~ ' °I I 6 WAIERLUNER~IOCADON'SEE r~ I II 1 ~7 - ~ - -i I I I 1 1 ~ - ~ a ~ OWO..wll FOIL PLAN AHD _PROrKE ~ .J w I I I I I I ~ _ _ p_ I I I I I I j[ I } ;"z.. ] _ . _ _ _ rur "u~- _ _ i _ ' 1 _ _ _ I r.t:x "-U`- J,~ _ ~ iii _'t _ _ _ ' hch = 20 Tcel ~ I f , y I I I I I ! ~i eyj II 1 -,:T,- - _ ~ - _ r-?'~, ~ ~ i'1- ~ s ~ = 3 Ley r f~ u - - _ - 1 I I sl 1. 5 VMU0NT ROAD, i ~ ~ I I I I, I .~'s" ~ ~;'-~~`-^-.vn_ } ~ d .TAIL ~ .,1I' ~ 1 ` FI - ``+,.,..r~'" ~ueD~ASre~a I ( t II ~ ~ r Gls-•1 D CHS _ ~ y_____________ <_.o--._,LL _ - ~ 1J I I• f I r If ~ 1 ~ I-- Ny ~ I I EX. DOUBLE IOKt C . CRWTEO" - - - - x ~ BOLADER RElA9RNG-MlAll. TvflCAI 1 39i'Lf16 PYC - CULVERT TD BE BANDOyED . ~ 801N SIDES OF CM NEI. 15' RCP S1pRU SEWER OU1LE~r "~F f j Iy ~~_~.i' I. I _ U4rt5 OF GRApINC,~ µ SEE DWC CN 5 F I I ' l r 1 l - ~ " ~ l ~r I _ _ ED TYPE u _ X51, - ~ f .BURIED Ie'Ury - ~ , .r- ..,..SANITARY SEWER. SEE OR DETA't' _ , - ~ ~ I ~ I ~ SOILI RIPAAP _ _ _ WC. SSI FOR PROFILE _ _ _ - v CROUIED BDULOERS : - :I- AEMpyE-704 Lf'Ex. / i - ABANDON ItSt LF ~ ~ IB LAW GROUTED- "8_ ~ ' - t 1 DgIBtC h0 !t' 4' - ' ~ ~ ~ I SEWERS SAN1IARY ~ S ch - - - OULOER I~ ICONC,80X_.CUL1~E 1 1-~ 3:1 _ ~ Lv ~ - - _ - PIUC.BOTN _ B _ ~ ~ ~ ~ 'ENDS OFPPIPE~ ~ w_7 ~ , ~ 9 pVC• jl ~ . ~ _ ~ .I ~ ~ .r jiL,.~,.~...~..~ _ , ~ STRUCIDRE ~ I ~ I ~ ~ ~ ~ - - 59 I~ -I ' ~PiARKING LOT 1 DNDER ASS..w_6 I 4 ~ C._ I ~ / ~ ~ ~ ~ ~ ACCESS RIDCF. ~ ~ ~i,rr ~d a~ 5 T///"~ ~ - OULOLR EDGE SEE ~ : I _ - ` - _ . IJ9} LF IS' PvC .y ~ -1 . 'r"._ ~1 ~ D - ~ ~ - - - - w~ 5 ~ _ T ~ ~s , i ,L Elul ON OwC C~S , _ _ ..--^~J . -'Ofi03 v - ~---'i--._ '-r ~ I I I 7 . a f„ ~ , g _ I - ° _ _ ~ ° II. _ -Lr_~L./;/~ - - - - - L . - RIPRAP BASIN. SEE~DwG. a 29L70 I, r. - - i- ~ - :,t -CHS fOR DEtna _ I I _ ' ~ 292.35 - - c - ~ y, _ - AIMN TRAL ' 91 p ~'I I I o a 296~t i ~ e - ~ ° 3o t5 ' - ;.fib.' o ti . o ~ l,y~' 3~ ~ J ~ _ v _ 303.55_ I fIPELEl _ 7g~~' 96 _ i - - ~~i-1- _ UN'-~i- _ ~~.3~%+_y ~ G5 , ~ I dub- - I '-D 'IDJ HIDE EUAIED TYP At ,•,.•,•.,~.~~.~s N ~ o -Y ~ CURB RAU ~ ~ . I o ` _ I I F00. RIP~pP I I f0' A13E 0' - v _..1 3W' CONCRETE TRAIL 10' - I ~I. - f0' WOE - - ~ ~ I _ -F--.N~il11 TR1JL 59ti i ~ ~ E_2 '14 lF 8~ PVC = T:I I' 40N[aETE TRAU. - ~ e r I f 1302.66 ° - ± -F-_ - _ I - - - - - - - - 1 I - INLFi,(SPEGAL) . _ 1:. V ~ 1 - I . _ _ _ - 302- - _ - - _ _ - _ I _ _ - _ _ _ - _ _ _ 1 _ - I , _ . _ `~S~I1TffTRAIL ~ I a "1 ~ I _IO:.IWDC I •TH TEAL ~ I _ ~ I 1`- - - - - - - ~ I 1 I rl~ I~ I CONCRETE iR L•--L-~-- - ~ I` EA9 SANrtAAY SEWER SEE II ~ _ PROPOSED 100-YEAR ~ ~ r ABANDON EXIST. _ II _ _ .l I " I i I 6WG SS2 FOR PROFlLE. kN I ~ ABANDON 30k Lf I I I I i FLOODPINN LIU115 1 U4.A OF GRADING I - I~~ I J i i ~ N MOLf~ I . d ~I x l W- 'IS' SANITARY r i _ ~ PLUG ANDI ABANDON J004 \ ~ g S(~`(I RUC BDT~ III jl I o I II I I r EN $ OF PEI I I p0 F ~ ~ / ' L.F, Of EXIST. 6' SANITARY ~ ` i r - o ~ ~ I ~ I I ~ I SEVER. ~ ! - ~ ~g~~`---~_ rl' I ~ I iI 1 I i CUBA P - - iRaCKENEO EOCE, YTR1ul STA. _ 1 ~ ~ + ' - ~..I,' I I ~ 70e TR TO STA. 30+57. ' ~ ',;I I I i SEE DW. CN7 FCR DETAIL I - I ' k k' k k k h' < < a < a < < b S ~ ° ~ 1 S)10 5310 ~ tv _ • - I. I~ _ i . - - 4 - - ~ ~ ~ - Q ~ ~,i I - ,p.~-YR OESCN 0~ BeJ CFS I ~I S7t 5706 - ~ & IdS dd - - - g~ fi - 10-5R'DEyCN 0 ~72-CFS I A 530E - J~ - - ~ - - ~ & 8 - W y r~• ~ ~ - - - - ~ - - -5'=YIt-DESGN-0 ' -281-fSS I : s~giy- - ¢ Z f" 5306 - _ _ _ _ I _ - c~ _ n- ~ - u ~ I -2 -DES!GN-0 1. 157-CFS-- - ! J 5706 DRIVEWAY I u ° < m # - m--- 1 G GRADE I I ~ n ~ d' S7W _ ---I^- k' --~J ~ m - _ ~ ~ ~ T- I- - - -tA~ N OI00- 790~CFSY S30t 5302 - - - - _ - __ri..n_: 100-YR WATER SURFACE _ I _ I _ _I_ 2 _ I I I 5300 - i u~ I m + I I I - _ ~ I 5296 I I ~ VAL110NT ROAD I _ n 1 I I . - - - _T - - - - I- - _ _ h ° _ - - i ~ _ _ e ry _ - W .~-I - -.L _ ~ - - - _ - i ~ - PROPOSE~tNN NEl ~ 5298 I. - - - 5296 _a11_..- - -_i N N i N ~ w r ' n_ - _I { _ - I 5296 i, ~ . n N SON . BOX_LVL Ri ~ 0 95 lF UNDERPASS ST UCIURE i ~ ] --W < n ~ I , - - 5291 5291 - - ~ I 5292 ~ < - I - a - 1 I - I - - - 5292 _ W m 1 ISIS I a. n." 1 ~ I - - --i 5290 1 v. _ _ I ° _ t i ~ I - 1 529D 5286 y1T I - - DJ.P.'WAIERUNE ~1TNIN 18'. L. _ _L-- _ 5286 5286 - - - I _ _ I S1EEl CA9NG SfE Dw0 WTt F ~ - - _ _ - _ _ I _ 5286 I RELOCATION PI AN AND PROFiLF. 56+80 57+20 57+60 58+DO SB+10 58+80 59+20 59160 6000 6D+10 60+60 61+20 61f6D 62+OD Computer File Informotion Sheet Revisions o°y °F B0~<o~~ AS CONSTRUCTED ELMER'S 2 MILE TRAIL CONNECTION Project No./Code Creotion Dole: August OB Init;Dls: Q A S C G Lost Modification Dote: Initials: Q I N C O R P O A A T 9 D ' No Revisions: CHANNEL PLAN AND PROFILE STE M 110-050 Full Path: Q ~ ~e~ ~ z Issued b Revised: Y 15016 Drowing File Name: Q 1461I.k..a~ee, mk~e. ~iw~ze 's' ' Revised: eeeu~. sm ree eeeo n.: vmesnne' D P Void: Sheet Number Acad Ver, Scale: Unils: Q Sheet Sub6el: Channel Subsel Sheets: CH 2 Of' 11 i.