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Home My WebLink About20061229.tiff CORRESPONDENCE RESPONSE DEPARTMENT OF * * * PLEASE RESPOND WITHIN THREE DAYS.* * * IF RESPONSE WILL BE DELAYED, PLEASE NOTIFY "CTB GROUP" BY E-MAIL OF EXPECTED DATE FOR RESPONSE. RECOMMIEND_ETD ACTION: Narrative: p cnonE MAR 2 7 2006 BOARD ACTION: (Initial by Approval) MG RM BJ DL f GV t y! ✓ Agree with Recommedation Worksession — — — — —� METHOD OF RlESPONSE -- - Board Action Work Session X Letter (Attached) - Telephone Call No Response (explain) Department Head Signature M:\CAROL\OPMAN\RDCOM P2 � vi bd 2006-1229 C iiL SC-�v/K /�ccnroA ( T O6 e/- Df„, OFFICE OF BOARD OF COUNTY COMMISSIONERS PHONE (970) 356-4000, EXT. 4200 C FAX: (970) 352-0242 O WEBSITE: www.co.weld.co.us 915 10th Street, P.O. BOX 758 COLORADO GREELEY, COLORADO 80632 March 27, 2006 Jasper Freese P.O. Box 913 217 East 18th Street Greeley, CO 80631 Dear Mr. Freese: In response to your letter dated March 14, 2006, regarding proposed construction and FEMA mapping of the Cache la Poudre floodplain in the vicinity of WCR#29(71st Avenue),I have referred your concerns to Weld County Public Works Department Engineering. Their comments are attached. Pursuant to current County Code, only floodproofed agricultural exempt buildings are approved for construction in floodways. For further information,please contact the Weld County Department of Public Works at 970-304- 6496. Sincerely, BOARD COUNTY COMMISSIONERS M. J. Geile, Chair Enclosures pc: Frank B. Hempen, Jr., Director of Public Works/County Engineer Dave Bauer, Storm Water Engineer Monica Mika, Planning Services Kim Ogle, Planning Services WCR 29 file M:\DAVE B\&FLOOD\Geile-Duran Itr.doc a MEMORANDUM ID TO: M.Mika,K. Ogle, Dept. of Planning Services DATE: 24-March-2006 WI C FROM: David Bauer,P.E.,Public Works Department COLORADO SUBJECT: FHDP for garage on Duran-Blietz property Weld County Public Works Department has reviewed the March 14, 2006 letter from Freese Engineering regarding the WCR 29/71`Avenue bridge elevations in relation to the FHDP for Duran-Blietz property located at 760 N. 71st Avenue, Greeley. The subject property,parcel ID 23923, consists of approximately 29.3 acres with a single residence. Comments ❑ The Duran-Blietz property lies completely within 100-year floodplain of the Cache la Poudre River shown on the current `Effective' FEMA floodplain insurance rating map (FIRM) dated 1982 (see attached map). ❑ The property lies completely within proposed `Effective' floodplain of the Cache la Poudre River shown on the 2005 preliminary FEMA floodplain insurance rating map that is currently in the public comment period and will be adopted by FEMA by mid-year 2006 (see attached maps). ❑ All but approximately 2 acres of the southern part of the property lies within the Floodway proposed on the 2005 preliminary FEMA floodplain insurance rating map that is currently in the public comment period. The existing residence on the property is completely within the floodway. Floodways can be characterized as the area of highest flow velocities and highest risk to life safety. ❑ The letter from Freese Engineering (on behalf of Duran-Blietz) states that the existing 71st Avenue bridge deck elevation is 4703.85 feet, and that the preliminary flood elevation shown in the 2003 FEMA Cache la Poudre River study is 4698.0 feet. The letter "suggests" that the bridge may act as a dam across the river. However Freese provided no evidence, computer modeling, or calculations to justify the claim that the existing bridge is causing harm. ❑ The Effective floodplain shown on the 2005 preliminary FIRM does not show widening of the floodplain upstream of the 71St Avenue bridge that is typical in cases where a bridge and approach roads cause a backwater condition (the "dam" effect mentioned by Freese). FEMA's 2005 floodway map also does not show any widening due to bridge effects. ❑ The FEMA procedures, guidance, and regulations require that parties (landowners, developers, communities) may request changes to proposed and designated floodplains and floodways by submitting technical evidence such as updated topography and elevations, new engineering calculations, or new hydraulic computer models of flood flows showing the proposed corrections. The information submitted with the March 14, 2006 letter from Freese Engineering contained no new information not already included in FEMA's 2005 floodplain insurance rating map. Without supporting new, different information than what was utilized in compiling FEMA's 2005 floodplain insurance rating map, there is no basis to recommend a change or dispute the proposed FEMA map. The 2005 floodplain insurance rating map that is currently in the public comment/appeal period will be adopted by FEMA by mid-year 2006. O:\ %DevReviewWrite-Ups\Dnran Bhetr&FHDPcommentdoc Page 1 of 2 3/27/2006 Recommendation Regardless of any flooding effects that may or may not be a result of the configuration of the existing WCR19/71st Avenue bridge and bridge approach road, the existing Duran-Blietz residence lies within the Cache la Poudre River floodplain and proposed floodway. The floodway is the area of highest flow velocities and highest risk to safety. Per Weld County Code, Sec. 23-5-250,FW (Floodway) District: "No development shall occur in the Floodway District with the exception of FLOODPROOFED agricultural exempt buildings". Construction of a garage in the floodway exposes that proposed building to flood damage and exposes the public to potential risk should rapidly moving flood waters remove portions of the building downstream where the debris may block other drainage structures causing additional flooding. Public Works recommends that no construction, included the requested garage, be permitted within the floodway. • • • O:\%Dev Rev icwWri te-Ups\Duran Bhet7FHDPcommeni.doe Page.2 of 2 3/27/2006 FREESE ENGINEERING P.O.BOX 913 \.. .-217 EAST 1810 STREET _. -GREELEY,COLORADO 80631 (970)352-0100 JAq+R RECERERED BECHMEENAL EtCWEER FE ISIER•D LAtc SURWYLR - March 14th, 2006 Honorable Mike Geile Chairman,Weld County Board of Commissioners P.O. Box 738 Greeley Colorado, 80632 Subject: FEMA Map Sta 788+06 WCR #29 (AKA 71st Avenue) Dear Sir At the request of Mary Jane Duran-Blietz of 760 N. 71st Ave, Greeley Colorado, Freese Engineering made an elevation survey of the centerline of 71st Ave, south from the south end of the existing bridge. (Map of elevations enclosed). The centerline of 71st Ave. appears to correspond with Sta 788+06 as shown on the FEMA preliminary Map. From the draft Flood Insurance Study Revision- Cache La Pourde River, City of Greeley and Weld County, Colorado, July 2003. The water surface elevation without floodway is 4698.0 at Sta 788+29. The results of our survey show an elevation of 4698.74, 300 feet south of the south end of the bridge. The bridge deck itself is at 4703.85, nearly six (6) feet above the 100-year flood elevation. While not within the scope of our employment, I feel that the elevations leading up to the north side of the bridge would be similar to those on he south side. It appears that the bridge and WCR #29 may act as a dam across the river. From the elevations shown on the flood map (Copy Enclosed), it is difficult to determine if the effects of the elevated road and bridge have been considered in the defining the floodway and floodplain. We would therefore request that prior to the approval of this portion of the FEMA Map that this situation at WCR#29 (71st Ave.) and the Cache La Poudre be more fully investigated. If you ... -• c . estions, please contact me at(970) 352-0100. Cc. ti, tv9- Zoa< .E. : S 92 J . ,g,71st Ave.) • '. : . :r Map) CC: of Greeley FEMA Mary Jane Duran-Blietz Job•2004-012 ROAD PROFILE WCR 4429 (AKA 71ST AVENUE) FREESE ENGINEERING 760 NORTH 71ST AVE 217 E 18th Street GREELEY COLORADO, 80634 GREELEY, COLORADO (970> 352-0100 0+00 4703.85 SOUTH END OF BRIDGE CONCRETE 0+50 4703.39 1+00 4702.65 APPROXIMATE STATION NORTH 788+06 N.T.S. (FLOOD STUDY MAP) 1+50 470L85 WCR #29 1+70 4701.44 e DRIVEWAY 2+00 4700.79 4697.60 2+26 470027 E e NW HOUSE CORNER GROUND ELEVATION e NW HOUSE CORNER 2+50 4699.68 FE. NORTH ' 4698.05 F.F. SOUTH tr 46%.50 BASE FLOOD ELEVATION (BEE> 4697.3 3+00 4698.74 ELEVATIONS BASED ON C.P.N. KING SURVEYORS 4698 P9 NAVD '29' 3+50 4697.98 3+63 4697.86 C e fL DRIVEWAY SOUTH JOB 02004-012 I certify the elevations on the above described road profile, on this . date, 16 Feburay, 2004. Q� :�' ], 1STE, S F <c; * 39 Oc FREESE ENG ERI JASPER FREESE, PE-PLS 04392. 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