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Home My WebLink AboutDrainage Reports - 01/16/2004tOPERTT OF VMT COLLV46 UTU Drainage Analysis for Best Western Remodel Fort Collins, Colorado October 9, 2003 CIVIL ENGINEERS 1 435 WEST 29TH STREET LOVELAND, CO 80538 (970) 46 1 -266 1 FAx (970) 46 1 -2665 www.dmwcivilengineers.com I Drainage Analysis for Best Western Remodel Fort Collins, Colorado October 9, 2003 Prepared for: Mr. Allen D. Curtis 3109 South Taft Hill Road Fort Collins, CO 80526 Pre ared by: t PVIERS _{ 1435 W. 29" Street Loveland, Colorado 80538 Phone: (970)461-2661 Fax:(970)461-2665 Project Number: 0304.00-BST I 1 t t RS CIVIL �� EI October 9, 2003 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 Re: Drainage Analysis for Best Western Remodel Fort Collins, Colorado Dear Staff: 1 43 5 WEST 29� STREET LOVELAND, CO B053B (970) 461-2661 FAx (970) 461-2665 WWW. DMWCIVILENGINEERS.COM 1 DMW Civil Engineers is pleased to submit this drainage study for the Best Western Remodel for your review. This report complies with technical criteria set forth in the City of Fort Collins' Storm Drainage Desion Criteria and Construction Standards manual and ' I the Urban Storm Drainage Criteria Manual, Volume 3, by the Urban Drainage and Flood Control District. 1 1 We acknowledge that the City of Fort Collins' review of this study is only for general conformancewith submittal requirements, current design criteria and standard engineering principles and practices. If you should have any questions or comments as you review this report, please feel free to contact me at your convenience. Sincerely, DMW CIVIL ENGINEERS Jade P. Miller, P.E. (CO #33885) Project Engineer 1 I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I Drainage Design Considerations for Best Western Remodel TABLE OF CONTENTS VICINITY MAP Page No I INTRODUCTION 1.1 Objective.................................................1 1.2 Project History and Previous Studies ............................ 1 1.3 Mapping and Surveying ...................................... 1 1.4 Site Reconnaissance........................................1 II SITE LOCATION AND DESCRIPTION 2.1 Site Location..............................................1 2.2 Site Description ............................................ 1 III DRAINAGE BASINS AND SUB -BASINS 3.1 Major Basin Description ...................................... 1 3.2 Sub -Basin Description.......................................2 IV DRAINAGE DESIGN CRITERIA 4.1 Design Criteria and Constraints ................................ 2 4.2 Hydrologic Criteria .......................................... 2 V DRAINAGE FACILITIES DESIGN 5.1 Proposed Site Development .................................. 2 5.2 Developed Drainage Patterns ................................. 2 5.3 Detention.................................................3 5.4 Erosion Control ............................................ 3 5.5 Water Quality .............................................. 3 VI CONCLUSIONS 6.1 Compliance with Standards ................................... 3 REFERENCES..................................................4 1 1 1 1 1 1 1 Drainage Analysis for Best Western Remodel EXHIBITS Exhibit 1 Best Western Remodel Drainage Exhibit APPENDICES Appendix A Existing and Developed Hydrology Computations Best Western University Inn - Fort Collins, Colorado 1V7-VO.VVV w 1V�-VD.VVV W 1V7-VV.VVV IN WUJO•F 1V�-VJ.VVV n h � : 1 T C, •.I_ ,c ,rail« • -� 'Subsia �• __. z CANAL_ _ C Ic It \ + Lt W. - .. a _ CN fA$T �.ru••J.'rc MIItF Nbly VarC " —Ssm�Izi Ander•mrvi7le l ' LaPorti, Ave t _ r 4 1L - r—,� po , {� = \ C ,i ,�pyv, —...a. OR �— c J OuM v t '�,� ty _ l �� IdJ RES�� ` .. _,_ i • ' t\ ti•'. � aN�. _- - `•[ L'I. IMAIRA:NI. NI`4 — � � � 13 � I ! •a. rsice�m. �yt ,.. L y �1 .. ram• a _W.y41 IN • .�- �-; ^�'x , '' y .}�'�•. .'.... rtl- �r Hof:&r r '• 1 �P•'_ :: i'V y' Z CT yy ill: , ii `kh� �--_-- R llil / 1 S-46 \ . saw�'Hi J. L.�e .Lakritrnx _ •T ' 1 G y O OR ._ 105006.000, W 105005.000, W 105004,000' W WGS84 105003.000' W Ili i I .. !0° L�1000RM Q_... •_000 t0p0MF,rEHS ' P mW from TOPO! 02000 Wildflower Prodwtbm (w .to com) Drainage Analysis ' for Best Western Remodel Fort Collins, Colorado ' October 9, 2003 INTRODUCTION 1.1 Objective This study documents the results of an analysis of the effects of the Best Western Remodel on runoff coefficients from historic to post -development conditions. t 1.2 Project History and Previous Studies There are no known previous studies for the Best Western site other than the City of Fort Collins Master Drainage plan. ' 1.3 Mapping and Surveying Topography for the project was taken from City of Fort Collins Aerial Topography ' with a two (2) foot contour interval. 1.4 Site Reconnaissance t The project engineer performed site visits to the Best Western Remodel site in Fort Collins in May and August, 2003. Existing drainage patterns and structures were observed for use in defining drainage basin boundaries and historic flow patterns. II GENERAL LOCATION AND DESCRIPTION ' 2.1 Site Location The site is located in the southwest quarter of Section 13, Township 7 North, Range 69 West of the 6th Principal Meridian in the City of Fort Collins, Colorado. The site ' is bounded by South College Avenue on the West, East Elizabeth Street on the south, and Remington Street on the east (See Vicinity Map). ' 2.2 Site Description The Best Western Remodel site is approximately 1.37 acres of existing motel ' buildings and paved parking. There is very little vegetation on the site which consists of trees and turf grasses. The west half of the site is zoned C-C (Community Commercial District) and the east half of the site is zoned N-C-B ' (Neighborhood Conservation Buffer District). The Best Western Remodel site is surrounded with existing commercial development as well as existing single family and multi family housing. III. DRAINAGE BASINS AND SUB -BASINS ' 3.1 Major Basin Description The Best Western Remodel site is within the Old Town Drainage Basin as identified by the City of Fort Collins Master Drainage Plan but not within any regulatory ' floodplains designated by either the City or FEMA. The Old Town Drainage Basin is located in north -central Fort Collins. The basin has a drainage area of Drainage Design Considerations DMW Civil Engineers ' The Farmstead July 30, 2003 ' approximately 2,120 acres, including approximately 400 acres of the Colorado State University campus. The entire basin is urbanized, with some development occurring in the late 1800s. In general, the basin drains from west to east. The Old Town ' Basin receives some runoff water from the Canal Importation Basin directly west of Old Town. Most of the water from Old Town drains to the Poudre River, just to the east. t 11 �J 1 3.2 Sub -Basin Description Stormwater runoff from the Best Western Remodel site drains overland generally from south to north at slopes of approximately 2.0%. Stormwater runoff is currently conveyed from the site towards the northeast and north west via surface drainage across parking lots. The affected area of the site has been divided into two (2) on -site historic drainage basins (See Exhibit 1). Runoff from Basin 1 is conveyed from the site to the northwest via the gutter in South College Avenue. Runoff from Basin 2 is conveyed from the site to the northeast via an 8 inch steel pipe which flows into the alley between South College Avenue and Remington Street. IV. DRAINAGE DESIGN CRITERIA 4.1 Design Criteria and Restraints Drainage design criteria specified in the City of Fort Collins Storm Drainage Design Criteria and Construction Standards manual and the Urban Storm Drainage Criteria Manual, Volume 3 by the Urban Drainage and Flood Control District have been referenced in the preparation of this study. 4.2 Hydrologic Criteria The rational method has been used to evaluate stormwater runoff from the project site. Runoff coefficients for new construction were compared to those for the existing conditions (see Table 1). V. DRAINAGE FACILITIES DESIGN 5.1 Proposed Site Development Remodel of the Best Western site will consist of an additional story to the single story motel office, new facade, and enclosure of a new swimming pool facility to replace the old one. A new driveway onto South College Avenue will be constructed as well as landscape islands in the parking lot. 5.2 Developed Drainage Patterns The affected area of the site has been divided into two (2) on -site developed drainage basins (See Exhibit 1). Runoff from Basin 1 is conveyed from the site to the northwest via the gutter in South College Avenue. Runoff from Basin 2 is Page 2 1 Drainage Design Considerations DMW Civil Engineers ' The Farmstead July 30, 2003 conveyed from the site to the northeast via an 8 inch steel pipe which flows into the alley between South College Avenue and Remington Street. No changes in flow patterns is proposed for either basin. Additional landscape areas were used to mitigate the effects of enclosing the pool and adding impervious areas such as paving and roofing. Therefore, runoff calculations are not necessary and have not been provided. ' 5.3 Detention Onsite water quantity detention has not been provided for the Best Western ' Remodel site. The proposed improvements to the site will mitigate additional impervious area created by enclosing the outdoor pool. [1 5.4 Erosion Control Plan and Criteria The erosion control plan presented here is intended to control rainfall erosion. The Erosion Control Reference Manual for Construction Sites (ECRM), City of Fort Collins, has been referenced for this erosion control plan. The proposed rainfall erosion control plan during construction will consist of temporary structural erosion control measures. Temporary sediment control consisting of silt fencing will surround areas of the proposed construction. See the Grading and Erosion Control Plan for locations of proposed erosion control measures. 5.5 Water Quality Because of the limited physical restraints of the site and the minimal change in character of runoff from the site, onsite water quality detention has not been provided for the Best Western Remodel site. VII. CONCLUSIONS 7.1 Compliance with Standards All drainage analyses have been performed according to the City of Fort Collins' Storm Drainage Design Criteria and Construction Standards manual and the Urban Storm Drainage Criteria Manual, Volume 3, by the Urban Drainage and Flood Control District. Due to the mitigating effects of additional landscaping on the site, the runoff coefficients of the Best Western Remodel site basins remain unchanged. Page 3 1 Drainage Design Considerations The Farmstead July 30, 2003 REFERENCES DMW Civil Engineers 1) Storm Drainage Design Criteria and Construction Standards, City of Fort Collins, Colorado, May, 1997, revised 1999 2) Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control District, Wright McLaughlin Engineers, Denver, Colorado, September, 1999. Page 4 2 0.42 0 5 ioo 15b Fqet—. 0 FEET ") I in = 5 ( ft. O El Lu w z z w J LEGEND: ell DOITTING STORM SEWER EXWNG STORM SEWEON WOH INLET PROPOSED STORM SEWER OR CULVERT o PROPOSED STORM SEWER OR CULVERT WITH INUET W20 OWNG CONTOUR w - PROPOSED CONTOUR PROJECT ROUNOW RESERVOIR MONSOON DESIGN DIUUDE MIN BOUNOW RON UJIM 5.0 AREA IN ACRES MORON POINT PROPOSED RIPRAP OUn.ET PROTECTION 0 Appendix A ^^NN' 94 ew x 41 (county seat) 54 .. `35... �_..; . 64 SHIiLDO.v , LAKE 6494 lb 5 •` 35 ' r. t a ]a 47 36 7� St L ,• O 10' 594 3 1 36 3 76 94 54 94 95 3 3 3 36 53 101 102 4 95 73 76 J 62 74 El 22 ,r /� 1 65 '101 76 30z ` 4 r, 76 95 4 - . 73 3 81 4 76 6 3 95 74 22 a 75 74 75 35 � 7 2 ' 0 95 1 4 74 73 LAMS \J RE SE VOIR 35 / 73 74 35 35 102 73 1\ 63' )5 74 35 •�. y5 74 10, a 36 74 73 76 7 75 73 c 74 ]]] 74 74 7 3 74 25 73 s GG t 3 >. 75 Oe .. 2V 34 36 6 36 22 . 36 r 3 .. 73 \ �6 3 36 74 V75 74 3 . 74 75 74 76 3 24 35 73 36 Y 74 76 73 76 3 4 36 74 36 3. 3 73 76 � 74 � v 4 i0j♦ lOB �4 +73 74 76 4899 - r' ul 4 3 74 Ili! 90 89 (\4 � 76 _ 3 .. 348 ti 76 ® WARREN p . 49 7 .90 106 e, 4 LAKE 77)YYY777 1 1 1 1 1 ld1RI n COUNTY AREA, COLOMW TABLE 8. Soil and water features —Continued Soil name and map symbol Hydro" logic Flooding Depth to seasonal high water Bedrock Paten, fros attic — group Frequency Duration Months table Depth Hardness Fut I"Ch" Elbeth: *30: Elbeth part -------- B None -------- -------------- ---- --------- >6.0 >60 ----------- Madera Moen part ------ —_ C None ---- --_ --------- ---- -------------- >6.0 20-40 Hard ____ Madera Farnuf: 31------------------ B None ------- -------------- -------------- >6.0 >60 ---------- Madera `32. Farnuf part ------- B None ---- ---- --------------------------- >6.0 >60 ----------- Madera Boyle part --------- D None ________ ______________ ______________ >6.0 9-20 Rippable -_ Madera Rock outcrop part. Fluvaquente: 33 ___________________ ________ Frequent --_ Brief __-_r_ April -June __- 0.5-26 >60 ----------- Low. Fort Collins: 34, 35, 36, 37 ---------- B None ____________________________________ >6.0 >60 ----------- Madera Foxcreek: 39 --- --------------- C Rare -------- Brief ------- April -May ___ 0-0.6 >60 ----------- High. Gapo: 39--- — --------- ---- D None -------- ------------- -------------- 3.0 >60 ----------- High. Garrett: 40----------- ------- B Rare ------- Very brief --- -------------- >6.0 >60 --------- __ Madera 41------------------ B None------------------------------------ >6.0 >60 ----------- Madera Gravel pits: 42. Haploborolla: •43: Haploborolls part --- -------- None -------- -------------- ------------- >6.0 ---------- ----------- Rock outcrop part. Haplustolls: 44 - ------- - None ---- -- ------ >6.0 ---------- ------------ •45: Haplustolls part ---- -------- None -------- -------------- -------------- >6.0 ---------- ----------- Rock outcrop part. Henan: 44. 47---------------- B None -------- -------------- -------------- >6.0 >60 ----------- Modera Heldt: 49 49 _—______<__>>_ -• C -- Nor_ ________ _____________ ___________ -- >� G �cn �VV ___________ M..a.,_., ---V Ar O Keith: So----------- — --- -- B None -------- -------------- ------------- >6.0 >60 ----------- Madera Kildor: 51---- -------------- C None ----------------------------------- >6.0 20-40 Rippable __ High. M: Kildor part — ------ C None ________ ______—__---- -------------- >6.0 20-40 Rippable __ High. Shale outcrop part. Kim: 51, 54, SS --- -------- B None ---------------------- ------------- -------------- >6.0 >60 ----------- Moders •S6: Kim part --------- B None --------- ------------- -------------- >6,0 >60 _---^___-- Madera Thedalund part ----- C None ---- —__ ______________ ______________ >6.0 20-40 Rippable __ Modera Kirtley: 57 ---------- -------- C None ---- —__ ______________ ----------- —_ >6.0 20-40 Rippable __ Madera P I I 1 1 u 1 Existing Conditions Area, A (so Coefficient (C) A*C Swimming Pool Removed 766 0.00 0.00 Landscape Removed 247 0.20 49.40 Impervious Removed (Roof, Pavement) 7037 0.95 6685.15 Total Removed 8050 6734.55 Average Runoff Coefficient 0.84 New Construction Area, A (so Coefficient (C) A`C Landscape Added 1298 0.20 259.60 Impervious Added (Roof, Pavement) 6752 0.95 6414.40 Total Added 8050 6674.00 Average Runoff Coefficient 0.83 Table 1 Runoff Coefficient Comparison