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4 - Call Up: Power Transmission Tower Floodplain Development Permit (LUR2009-00010) MEMORAND[IM 'f0: Planning Board FROM: Katie Knapp, Civil Engineer, Floodplain and Wetlands Pern~itting DATE: February 13, 2009 SIIBJ>H;CT: Call tlp Item: Power Transmission Tower Floodplain Development Pei7nit (LUR2009-00010) This decision maybe called up before Plamiing Board on or before 1' ebruary 27, 2009 A Floodplain nevclopment Permit was approved by Planning and Development staff on February 13, 2009. The project involves removal of two existing 3-foot diameter power towers and construction of two new 9-foot diameter power towers south of Pearl Parkway and east of 55`h St. The proposed project involves the relocation of a power transmission line and requires two existing power towers to be removed and relocated. One of the relocated power towers will be within the flood conveyance zone of Goose Creek. Excavation and grading is proposed in the vicinity of the new power tower to slightly increase the flood conveyance over the existing conditions. The applicant has demonstrated that the project will not adversely impact the floodplain or cause a rise in the floodwater elevation during the 1 UO-year flood event. A copy of the floodplain development permit and the application material are attached. A simple wetland permit (LUR2008-OOU l 1) was also approved for this project for wetland buffer impacts. Simple wetland pern~ils arc not subject to Planning Board call-up. This floodplain development permit was approved by Planning and Development Services staff on February 13, 2009, and the decision may be called up before Plaiuling Board on or before February 27, 2009. There are two Planning Board meetings within the required 14-day call-up period on February 19, 2009 and on F+'ebruary 26, 2049. Questions regarding this floodplain development permit should be directed to Katie Knapp in Planning acrd Development Services at 303-441-3273 or knappk~r`bouldcrcolorado.gov. CITY OF BOULDER V 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: February 13, 2009 Expiration Date: February 14, 2012 (Pursuant to Subsection 9-3-6(e), B.R.C. 1981) Permit Number: LUR2009-00010 Contact Information CITY OF BOULDER PO BOX 791 BOUt_DER, CO 80306 Stephany Westheusen Project Information Location: 0 55TH ST Legal Description: TRI TR NW 1/4 SE 1/4 2.12 ACS M/L &TRI TR NE 1/4 SW 1/4 .88 AC M/L 28-1 N-70 PER CA 83CV00 85-2 02-17-83 PER DEED 923176 6/8/88 BCR PROPERTY ADDRESS: 000000 55TH ST BOULDER Description of Work: Floodplain development permit to remove two (2) existing 3' diameter power distribution line tower bases & install two 9' diameter bases for a relocated powerline & regrade area. Type of Floodplain Permit: Floodplain Review W10 Analysis Creek Name: Goose Flood Protection Elevation: Conditions of Approval • The proposed projectlactivity is approved on the basis that it satisfies applicable requirements of Chapter 9-3-3, "Floodplain Regulations," Boulder Revised Code 1981. Other floodplain requirements as set forth in Chapter 9-3-3 which are not specifically outlined in the conditions of approval below remain applicable to this project/activity. The proposed improvements shall be constructed in compliance with the plans submitted with the floodplain development permit. The applicant shall confirm in writing that all improvements have been completed in conformance with this Floodplain Development Permit. The applicant shall obtain a site inspection and approval from the City of Boulder Floodplain and Wetlands Coordinator upon completion of the projects. Construction activities must not encroach into any regulatory wetland area. The improvements shall be constructed to minimize and mitigate impacts to the existing wetlands in conformance with the conditions of the City of Boulder Wetland Permit issued for this project. The floodplain development permit if not appealed, is final 14 days after issuance. ~7~Yr- & Associates, lnc. voter resource consultants 800 Jsffsrson Avenue, Sulre B Phone (303) 673-9755 lovi~vllle, Colorodo 80027-1873 fax (303) 673.9796 www.LoreAssotlotes.com January 8, 2009 Katie Knapp Development Review Coordinator City of Boulder Y.O. Box 791 Boulder, Colorado 80306 RE: 0829A - FLOODPLAIN llEVELOPMENT PERM.iT FOR BOULDER Creek Xcel Power Tower Relocations Dear Katie: The City of Boulder is submitting this Floodplain Development Permit Application to remove an existing 3' diameter Xcel Power Tower and installing two (2) new proposed 9' diameter Power Towers that are located totally or partially within the City of Boulder Regulated Floodplains. Other Power Towers located outside of the Regulatory Floodplain will also be removed or constructed as a part of this project. Power Tower No. 1 is located 25' southeast of an existing Power Tower. Excavation/Grading would be performed around the existing and proposed pole locations to slightly increase flood conveyance over existing conditions at this location. Power Tower No. 1 is located along the Boulder Creek/Goose Creek Trail Corridor near Cottonwood Pond. A proposed 9' diameter Power Tower No. 2 along South Goose Creek will also be installed. The proposed Power Tower is only partially located in the-100-year floodplain. The portion of the Power Tower within the 100-year floodplain is located in shallow flood depths and construction of this tower will have no inverse effects to the 100-year floodplain in the surrounding area since the negligible increase in flood levels at this location would be totally located within the existing channel. Figure 1 shows the Project Location for Power Towers No. 1 and 2. The permit application forms, the proposed grading at Power Tower No. 1 and hydraulic 800 Jefferson Avenue, Suite B Louisville, Cobrado 80077-1873 Phone: 303b73AT95 Fax: 30373-9796 Katie Knapp January 8, 2009 Page 3 12. Whether safe access is available to the No change. property is times of flood for ordinary and ewer vehicles. 13. Whether the applicant will provide flood No. warning sysrtems to notify floodplain occu is of ' floods. 14. Whether the cumulative effect of the No change to flood levels due to this project. proposed development with other See response to question 3. existing and anticipated uses will increase flood levels. I5. Whether the expected heights, velocities, The additional capacity provided by the duration, rate of rise, and sediment proposed grading at Power Tower No. 1 should transport of the floodwaters expelled at decrease the water surface elevation of flows the site will adversely affect the within the flood area. The other variables will development or sunrounding property. remain unchanged and there will be no change to i cts on surroundin ro We thank you for the opportunity to subnut this Floodplain Development Permit Application and we look forwazd to your issuance of a flood permit for the prnposcd Power Tower installations. Please contact us if you have any comments or questions. Sincerely, LOVE & ASSOCIATES, INC. ~~~mm ~~o~`QpOfl E ~ . Q~ V~ `~o~ _.o~ 4 4 ~ David .Love, P.E. .S!9~ Al ~ ~~'iu~utui?w~u~Wy 800 Jsllason Avenus. Sines B LoulsWls, Colorado e002'T-1073 Phans: 303~6T38795 Eau 3aL873'6786 i ~ ~ i 4oa d~ o OQ o, dos - g~_ 8o Dp o $ e ; Q ov pD ~ 0 0 ~~~yy ' ~ p0 b a ? flia Q ~P ~Q O C1C:] b w ~ Qp ~ ~ ? 7 0~ O ~U'~ ~ Q Q Q ~ ~ sP ~~0~~p a a a ~ ~ a o _ p o ~ CJ Q ~.f ~ ~ PROJECT n - n ~ ~.J ~ ~ LOCATION ; - 0 0 ~g ~ , - \ ~ ~ - ~ b Q boa , , ? DD to ° ~ o o. ~ , . w i i ~ ~ ~ _ ~ ' - - ~j-~-- ~i PROP D 'vy ~ _ r'------'~ WER PROPOSED TOWER e POW NO. 1,Q ~ ~ G7 ~ ER i L~~ = N0.2 ' ° IIJJ ~~}}yy~~~ O _ ~ 00-YEAR `1 ~ _ _ _ V FLOOOPLAIN 0 0 ~ ~ - i , ~j v (TYP) - - ~ ~ ~ U _ ` , ~ $ - ? ~ ~ ~ a;a DQ, ~ o o~ . o ~ ' ~ :~°°a as ' ap ' ~ ~9 a p~~ ~ © ~ a o o~ vao cn ~ 0 4 ~ ~ D O ~ XCEL POWER TOWER ~ ~,~bt~.,~~ RELOCATION ON PEARL PKWY CITY OF BOULDER LOCATION MAP FIGURE 1 ~ E IVALENT CONVEYANCE CALCULATIONS ' i ~ NAVD 88 Area ' Section I WS Under 1.49 ~ Wetted Equivalent Number Elev. WS n Perimeter R R 2/3 I Conve ance ~ 5213.9 I Existing 1 i 1.0 I 37.25 8.0 0.13 0.2483 9.2 Pro osed 1 8.0 37.25 20.3 0.39 0.5359 159.7 i Existing 2 44.0 37.25 87.2 0.50 0.6324 1036,4 Proposed 2 89.0 37.25 83.0 1.07 1.049 3474.0 Existing 3 I 110.0 37.25 86.0 1.28 1.1793 ~ 4832.1 Pro osed 3 156.0 37.25 ~ 69.3 2.25 ~ 1.7223 10008.1 Existing 4 144.0 ~ 37.25 54.0 2.67 1.9293 10348.7 Pro osed 4 165.0 37.25 45.0 3.67 ~ 2.3882 14678.2 CONVEYANCE = 1.49 x A x R2/3 n I NGVD29 WS = ~210.7~ Conversion = -3.2' ~ NAVD88 = ~ 5213.9 ~ F:~PROJECTS - CURRENT10829A~BLOCKAGE-REV