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HomeMy WebLinkAboutDrainage Reports - 08/29/2007City of Ft. Collins Approved Plans Approved By ILS L 2MM Date S-.2q-off Final Drainage and Erosion Control Report for Testa Subdivision 1635 South Lemay Avenue Fort Collins, Colorado May 15, 2007 c 1435 WEST 29TM STREET Q�'// LovEu No, Co 80538 �/ (970) 461 -2661 CIVIL ENGINEERS FAx (970) 461-2665 WWW.dmwc1VIIan ginaars.cam Final Drainage and Erosion Control Report for Testa Subdivision 1635 South Lemay Avenue Fort Collins, Colorado May 15, 2007 I 0 Prepared for: Mr. John Testa 4221 Cobb Lake Drive Fort Collins, CO 80524 Prepared by: CIVIL ENGINEERS J" 1435 W. 29"1 Street Loveland, Colorado 80538 Phone: (970)461-2661 Fax (970)461-2665 Project Number. 0708.00-TBS I ' 1435 WEST 29TH STREET ® LOVELAND, 00 80536 (970) 461-2661 ' CIVIL ENGINEERS J` FAX (970) 461-2665 WWW.DMW01 VILENGINEERS.COM ' May 15, 2007 ' City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 ' Re: Final Drainage and Erosion Control Report for 1635 South Lemay Avenue Fort Collins, Colorado ' Dear Staff: 1 DMW Civil Engineers, Inc. is pleased to submit this Final drainage and erosion control report for 1635 South Lemay Avenue for your review. I hereby certify that this report was prepared by me, or under my direct supervision, in accordance with the technical criteria set forth 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. We acknowledge that the City of Fort Collins' review of this study is only for general conformance with 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, INC. Jade P. Miller, P.E. (CO #33885) Project Engineer I IV LTA V1 0 Final Drainage and Erosion Control Report for 1635 South Lemay Avenue TABLE OF CONTENTS VICINITY MAP Page No. INTRODUCTION 1.1 Objective .............................. 1 1.2 Mapping and Surveying ...................................... 1 GENERAL LOCATION AND DESCRIPTION 2.1 Location .......................................... * ....... I 2.2 Description of Property .............................. ........ 1 DRAINAGE BASINS AND SUB -BASINS 3.1 Major Basin Description ....... : .............................. 1 3.2 Sub -Basin Description ............... ....................... 2 DESIGN CRITERIA 4.1 Design Criteria and Constraints 2 4.2 Hydrologic Criteria ................................. ......... 2 4.3 Hydraulic Criteria ...... ..................................... 2 DRAINAGE FACILITIES DESIGN 5.1 Proposed Site Development ....... I ........................... 3 5.2 Developed Drainage Patterns ................................. 3 5.3 Detention ............... I .................................. 3 5.4 Erosion Control .... ..................... 4 5.5 Water Quality. ...... 5 5.6 Floodplain Design Considerations ............ I .................. 5 CONCLUSIONS 6.1 Compliance with Standards . . ................................. 6 REFERENCES ........... ......................................... 7 1 1 1 1 0 Final Drainage and Erosion Control Report for 1635 South Lemay Avenue I EXHIBITS Exhibit 1 100-Year Floodplain/Floodway Map, Spring Creek Master Drainage Plan Exhibit 2 8.5"x11" FIRM, Community -Panel No.08069C-0983F Exhibit 3 2446" Developed Drainage Plan r APPENDICES Appendix A Hydrology Calculations Appendix B Hydraulic Calculations Appendix C Water Quality Pond Calculations Appendix D Impervious calculations and excerpts from the Spring Creek Master Drainage Plan Appendix E Erosion Control Calculations A 1 J 0 0 0 N II J Q U N ' Final Drainage and Erosion Control Report for 1635 South Lemay Avenue Fort Collins, Colorado ' May 15, 2007 INTRODUCTION 1.1 Objective This study documents the results of a final hydrologic and hydraulic analysis of post -development conditions for the proposed 1635 South Lemay Avenue project. The utility plans which accompany this report are entitled Final Utility Plans for 1635 South Lemay Avenue prepared by DMW Civil Engineers, Inc. This report will ' also assist the contractor in the preparation of a Stormwater Management Plan (SWMP). 1.2 Mapping and Surveying ' Field survey information and topographic mapping with a contour interval of 1-foot was obtained by DMW Civil Engineers from Frederick Land Surveying, Loveland, ' Colorado. Additional topography outside of the project boundary was taken from City of Fort Collins Aerial Topography with -a two (2) foot contour interval. All elevations in this report are on NGVD29 datum. FEMA flood elevations have been ' converted from NAVD88 to NGVD29. ' II GENERAL LOCATION AND DESCRIPTION 2.1 Location ' The site is located in the northwest quarter of Section 24, Township 7 North, Range 69 West of the 6th Principal Meridian in the City of Fort Collins, Colorado. The site is bounded by Lemay Avenue to the east, Spring Creek to the south, and developed lots to the north and west (see vicinity map). 2.2 Description of Property The 1635 South Lemay Avenue site is approximately 0.38 acres. The existing site has approximately 60% pervious coverage which consists of irrigated turf grass and 'landscaping. Onsite soils are predominantly Hydrologic Group C, according to the ' Soil Survey for Larimer County, by the Soil Conservation Service. The existing runoff coefficient for the overall site prior to construction is estimated to be 0.56 for the design storm. The site is zoned Neighborhood Commercial District (NC). This ' site is within Flood Insurance Zone AE, the areas determined to be within the 100- year flood plain according to the FEMA Flood Insurance Rate Map, Community - Panel No. 08069C-0983F, dated December 19, 2006. III. DRAINAGE BASINS AND SUB -BASINS ' 3.1 Major Basin Description The 1635 South Lemay Avenue site is within the Spring Creek Basin according to Final Drainage and Erosion Control Report DMW Civil Engineers, Inc. 1635 South Lemay Avenue May 15, 2007 the City of Fort Collins Master Drainage Plan. . Spring Creek is a major watercourse that flows from Spring Canyon Dam at Horsetooth Reservoir to its confluence with the Poudre River. The Spring Creek drainage basin encompasses nearly nine square miles in central Fort Collins. The basin is dominated by residential development, but it also includes open space, parks and isolated areas of commercial and industrial development. 3.2 Sub -Basin Description Stormwater runoff from the 1635 South Lemay Avenue site drains overland generally from north to south at slopes ranging from 1.0% to 2.0% into adjacent property and then into Spring Creek. Stormwater runoff is currently conveyed from the existing site towards the south overland. The flows are conveyed overland directly to Spring Creek. Spring Creek ultimately discharges into the Poudre River. IV. DESIGN CRITERIA 4.1 Design Criteria and Constraints 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 estimate peak stormwater runoff from the project site. An initial 10-year and major 100-year design storms have been used to evaluate the proposed drainage system. Calculations made as part of this investigation, along with other supporting material, are contained in Appendix A. Rainfall intensity data for the rational method has been taken from rainfall intensity data tables contained in the City of Fort Collins Storm Drainage Design Criteria and Construction Standards manual (see Figure 3-1 a). Composite runoff coefficients were generated using Table 3-3 and 3-4 of the City of Fort Collins Storm Drainage Design Criteria and Construction Standards manual. 4.3 Hydraulic Criteria Spreadsheets, provided by the Urban Drainage and Flood Control District have also been used as a design aid for swales and water quality calculations. Hydraulic calculations are included in Appendix B. Page 2 Final Drainage and Erosion Control Report DMW Civil Engineers, Inc. 1635 South Lemay Avenue ' May 15, 2007 V. DRAINAGE FACILITIES DESIGN ' 5.1 Proposed Site Development Development of the 1635 South Lemay Avenue site will consist of remodeling the structure to convert it from residential use to commercial use as a beauty salon. The proposed site infrastructure includes a new parking and sidewalks. ' Approximately 68% of the 0.38 acre site will be disturbed with the construction of this project. Impervious area for the site will increase from approximately 2500 ' square feet to approximately 7600 square fee. The runoff coefficient for the overall site after construction is estimated to be approximately b.56 for the design storm. ' 5.2 Developed Drainage Patterns The developed site has been divided into three (3) onsite drainage basins. Stormwater runoff will be conveyed overland, through concrete gutters and chases, ' and grass lined swales. Basin 1 (0.18 acres) includes half of the building and the site west of the building. Runoff from this basin drains to the southeast to a proposed water quality pond. The 10 and 100-year. peak discharges from the basin are 0.4 and 1.1 cfs, ' respectively. Basin 2 (0.17 acres) includes half of the building and the site east of the building.. Runoff from this basin drains to the southwest to a proposed water quality pond. The 10 and 100-year peak discharges from the basin are 0.4 and 1.3 cfs, respectively. The 10 and 100-year peak discharges from both basins into the pond are 1.0 and 2.4 cfs, respectively. Basin 3 (0.03 acres) includes the eastern portion of the site that drains to Lemay ' Avenue. Runoff from this basin drains to the east directly into Lemay Avenue. The 10 and 100-year peak discharges from the basin are 0.1 and 0.3 cfs, respectively. ' 5.3 Detention Prior to construction, the 1635 South Lemay Avenue site had runoff coefficients of 0.34 and 0.43 for the 10 and 100-year storms, respectively. The proposed runoff ' coefficients for the site are 0.56 and 0.70 for the 10 and 100-year storms, respectively. The increase of runoff generated by the increase in imperviousness is 0.6 and 1.3 cfs for the 10 and 100-year storms, respectively. This increase in runoff is not detained due to the physical limitations of the site, and due to the site's . close proximity to Spring Creek. The peak for this runoff for the site will occur much ' earlier than the peak for the Spring Creek Basin at this point. Therefore increase in the overall peak of Spring Creek attributable to the 1635 South Lemay Avenue project is negligible. Page 3 N [1 Final Drainage and Erosion Control Report 1635 South Lemay Avenue May 15, 2007 DMW Civil Engineers, Inc. ' Per the Spring Creek Master Drainage Plan, the peak for Spring Creek adjacent to the site (conveyance element 420) occurs at approximately 3 hours and 28 minutes. Runoff calculations for the 1635 South Lemay Avenue site indicate that peak runoff rates are generated at a time of approximately five (5) minutes. Due to the site's close proximity to the main channel for the Spring Creek Basin, the peak flows generated on site significantly "beat the peak" of the main channel. Therefore, the site -generated peak flow does not significantly affect the overall peak for Spring Creek. According to the Spring Creek Master Drainage Plan, updated by Anderson Consulting Engineers, Inc. on May 5, 2003, the 1635 South Lemay Avenue site is situated in sub -basin 220. Impervious percentages for sub -basins in the S rin Creek Master Drainage Plan were generally assumed based upon current land use and zoning classifications. For example, the three zoning classifications within sub - basin 220 are NC (Neighborhood Commercial), MMN (Medium Density Mixed -Use Neighborhood), and LMN (Low Density Mixed -Use Neighborhood) and have assumed impervious percentages of 90%, 70%, and 50%, respectively. Sub -basin 220 was determined in the master plan to have an impervious percentage of 65%. Although the composite calculations are not included for each sub -basin in the Spring Creek Basin, the value for sub -basin 220 was confirmed by DMW, using the assumptions listed in the Master Plan, to be 59%. This demonstrates that the 1635 South Lemay Avenue site was assumed to have an impervious percentage of at least 90% in the Spring Creek Master Drainage Plan based upon the NC zoning of the site. DMW performed an analysis of actual conditions for the NC zoned area surrounding the 1635 South Lemay Avenue site. Of the 3.96 acre area, 1.77 acres, or 45 percent, is impervious. Therefore, the site will maintain an impervious percentage below that which was assumed in the Master Drainage Plan and will be in compliance with that plan. This demonstrates that the proposed improvements at 1635 South Lemay Avenue will not adversely affect the detention pond located at the Burlington Northem Railroad Crossing near Timberline Road and Lemay Avenue. 5.4 Erosion Control ' 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. Appendix E contains worksheets for erosion control design as well as for erosion control escrow security. The proposed rainfall erosion control plan during construction will' consist of minimizing soil exposure, protection of exposed soils and temporary structural sediment control measures. Page 4 1 Final Drainage and Erosion Control Report 1635 South Lemay Avenue May 15, 2007 DMW Civil Engineers, Inc. Temporary structural sediment control for. the site will consist of silt fence surrounding the areas of construction, wattle filters, and a temporary sediment control pond. All temporary structural sediment control measures shall be inspected and maintained as needed after every storm event. See the Grading and Erosion Control Plan for locations of proposed sediment control measures. 5.5 Water Qualitv The City of Fort Collins requests that 40 hour extended detention basins be used for water quality. Because of physical restraints of this site, this BMP was not practical. Constructability was a factor when evaluating the 40 hour extended ' detention basin. Because of the low flows routed through this pond, orifice sizing and trash rack construction would have been difficult. Also, a typical water quality outlet structure would require an outfall pipe that. would have to cross private ' property. It was for these reasons that a porous landscape detention basin was used for water quality. The porous landscape detention consists of a low lying vegetated area underlain by a sand bed. This BMP allows water quality containment volume below the invert of the detention pond outlet. Accumulated runoff ponds in the vegetated zone and gradually infiltrates into the underlying sand bed and subgrade. A total water quality containment volume of 210 cubic feet is provided for the impervious areas on the site. 5.6 Floodplain Design Considerations According to FEMA Flood Insurance Rate Map for Fort Collins, Community Panel 08069C-0983-F Revised December 19, 2006 this Parcel is partly within the FEMA Designated Flood Zone "AE". The Zone "AE" boundary is indicated on this map as shown.(see FIRM Panel 08069C-0983-F included with this application for zone boundaries). The FEMA Base Flood Elevation for the existing building is 4947.9 (NAVD88) which is equivalent to 4944.9 (NGVD29)., The FEMA Base Flood Elevation for the existing garage is 4948.3 (NAVD88) which is equivalent to 4945.3 (NGVD29) A floodplain use permit is required for each building and each site construction element (detention ponds, bike paths, parking lots, Utilities, etc.) in the floodplain. ' A FEMA elevation certificate will be need to be completed and approved prior to CO being issued for any new structures or additions in the floodplain. ' If the value of the remodel is less than 50% of the value of the structure, then no ' additional work to comply with the floodplain regulations is required. If the value Page 5 Final Drainage and Erosion Control Report DMW Civil Engineers, Inc. 1635 South Lemay Avenue ' May 15, 2007 meets or exceeds the 50% value, then the structure will have to be elevated or ' floodproofed to 6" above the base flood elevation. A detailed cost list will need to be provided with the building permit application to determine the value of the remodel. ' Base flood elevations on the plans are referenced to the NAVD 1988 datum. The FEMA recognized vertical datum offset to NGVD 1929 (unadjusted) for the Spring Creek floodplain is three (3.0) feet (i.e.: NAVD88=NGVD29+3.0). ' VI. CONCLUSIONS 6.1 Compliance with Standards II 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. Floodproofing shall meet the requirements of City of Fort ' Collins City Code chapter 10. There will not be any critical facilities on this site per the definition in the City of Fort Collins City Code chapter 10. J Page 6 I Final Drainage and Erosion Control Report DMW Civil Engineers, Inc. 1635 South Lemay Avenue ' May 15, 2007 REFERENCES 1) Storm Drainage Design Criteria and Construction Standards, City of Fort ' Collins, Fort Collins, Colorado, May, 1997, revised 1999. 2) Soil Survey of Larimer County Area, Colorado, United States Department of ' Agriculture, December 1980. 3) Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control ' District, Wright Water Engineers, Denver, Colorado, June, 2001. 4) Spring Creek Master Drainage Plan, Baseline Hydrologic Analyses, Volumes ' I & II, Anderson Consulting Engineers, Inc., Fort Collins, Colorado, May 5, 2003. 5) Hydrologic Modeling and Hydraulic Analyses for Spring Creek Downstream of Edora Park, Anderson Consulting Engineers, Inc., Fort Collins, Colorado, _ October 21, 2005. C Page 7 1 No Text Table 3.1 Summary of 100-Year Floodplain.and Half -Foot Rise Floodway Results._ on `hot men ircra S on f- s, nn Creek 113 4899.8 4900.1 0.3 1,037 1123 2.6 128 4900.3 4900.6 0.3 1,041 1,567 1.8 704 4901.9 4902.2 .0.3 1,003. 2194 .1.3 1335 4903.5 4903.5 0.0 472 .1036 2.8 1826 4905.7 4905.8 0.1 192 782 3.7 2055 4906.0 4906.3 0.3 179 .942 3.1 23.30 . 4906.2 4906.6 0.4 84 . - 434 6.7 2434 4907.5 4907.7 ', 0.2 87 473 6.2 2743 4908.4 4908.6 0.2 104 511 5.7 3134 4910.1 4910.2 0.1 91. 492 5.9 3204 4910.9 4911.0 0.1 95 534 5.5 3412 4911.3 4911.4 0.1 78 362 8.1 3500 4911.4 4911.4 0.0 90 277 10.5 . 3571 4916.8 4916.8 0.0 1,012 3,827 0.9 3783 4916.7 4916.7 0.0 927_ 1871 2.3 4186 4917.0 4917.0 0.0 459 814 5.1 4373 4917.0 4917.0 0.0 70 375 11.0 4642 4920.6. 4920.6 0.0 250 1038 4.0 5154 4921.3 4921-3 0.0 383 935 4.3 5218 4923.9 4923.9 0.0 459 1461 2.7 5438 4924.6 4924.E 0.0 504 .11295 3.1 5729 4924.7. 4924.7 0.0 221 742 5.4 5932 4925.1 4925.1 u 242 583 6.9 5937 4927.0 4927.0 0.0 242 425 9.4 6348 4929.2 4929.2 0.0 222 1149. 3.3 6803 4928.6 4928.7 0.1 135 539 7.1 7234 493I.0 4931:0 0.0 227 863. 4.3 7492 4931.4. 4931.4 0.0 129. 586 6.4 7662-- 4931.2 4931.2 0.0 61 23-3 16.1 7744 4936.1 4936.3 0.2 174. 344 10.9 7763 4938.2 4938.3 0.1 179 1123 3.2 7944 4938.5. 4938.5 0.0 92 806 4.5 8140 493&8 4939-0 0,2 1.13 850 4.2 8474 4939.6 4939:8 0.2 121 777 4.6 8877 4940.8 4941..1 0:3 12.3 .623 5: 9188 4942.1 4942.4 03 98 361 -9.8 9278 4944.5 4944.7 0.2 84• 501 21 9465 4945;5 4945.6 0.1 109 371. 8.4 9.777 4948.0 4948.1 0.1 339 1470 1 2.1 10253 " 4950.6 4950.6 0.0 323 676 46 1055.5 495:14 .4952.4 fj 0:0 303. 1,05-1 .3.0 COFC200510_SpringCrFPMods RepoRdoc _ 8 ANdERSON CONSUMNQ ENgMERS, INC. ,g . § � � §. 2 §■| � � §�§ �� ■ . � � © S ■ � & || \ � 9neA MUGamea \ {b ; ;||2r ■ l��� ■ g § Mai - . arm:$ ` , ! 22e�� UO � -� �. 1` --E !|! I |fk;.! ,'- , k�§�E Ed z_ 7 � w ?I is 0 a 1 AppMlZl A I ' MAY 1984 DESIGN CRITERIA Table 3-2 ' RATIONAL METHOD RUNOFF COEFFICIENTS FOR ZONING CLASSIFICATIONS Description of Area or Zoning Coefficient ' Business: BP, SL......................................................................................... Business: BG, MB, C................................................................................. Industrial: IL, IP.......................................................................................... Industrial: IG.......................................................................................... Residential: RE, RLP................ Residential: RL, ML, RP...................................:..........:..:.................. Residential: RLM, RMP ......... .............................................................................. ............ Residential: RM, MM.................................................................................. Residential: RH......................................7.......................... ........ ................. Parks, Cemeteries .............. .............. :......................................................... Playgrounds ....................... ......... Railroad Yard Areas ...:...........:.:............................................ .............. UnimprovedAreas...................................................................................... 0.85 0.95 0.85 0.95 0.45 0.50 0.65 0.70 0.25 0:35 0.20 Table 3-3 ' RATIONAL METHOD RUNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS Character of Surface Runoff Coefficient ' ,Streets, Parking -Lots, Drives: Asphalt................................................................................................ 0.95 Concrete............................................................................................. 0.95 Gravel........:.....:.................................................................I................ 0.50 Roofs............. .................... ........................................................ ................. 1 0.95 Lawns, Sandy Soil: Flat' <2%.......................................................:........... 0.10 Average2 to 7%'.................................................................................. 0.15 Steep>7%.......................................................................................... 0.20 _ Lawns, Heavy Soil: Flat <2%................................... ................................................... ....... 0.20. 1 Average2 to r/a.................................................................................. 0.25 Steep >7% ........:.................... ' Table 3-4 . RATIONAL METHOD FREQUENCY ADJUSTMENT FACTORS ' Storm Return Period Frequency Factor (years) G 2t010 1.00 .11 to25 1:10 26 to 50. 1.20 51 to 100 1.25 ' Note: The product of C times C, shall not exceed 1.00 City of Fort Collins Rainfall Intensity -Duration -Frequency Table for using the Rational Method. (5 minutes - 30 minutes) ' Figure 3-1a Duration (minutes) 2-year Intensity in/hr 10-year Intensity in/hr 100-year Intensity in/hr 5.00 2.85 4.87 9.95 6.00 2.67 4.56 9.31 7.00 2.52 4.31 8.80 8.00 2.40 4.10 8.38 9.00 2.30 3.93 8.03 10.00 2.21 3.78 7.72 11.00 2.13 3.63 7.42 12.00 2.05 3.50 7.16 13.00 1.98 3.39 6.92 14.00 1.92 3.29 r 6.7,1 15.00 1.87 3.19 6.52 16.00 .1.81 3.08 6.30 17.00 1.75 2.99 6.10 18.00 1.70 2.90 5.92 19.00 1.65 2.82 5.75 20.00 1.61 2.74 5.60 21.00 1.56 2.67 5.46 22.00 1.53 2.61 5.32 23.00 1.49 2.55 5.20 24.00 1.46 2.49 5.09 25.00 1.43 2.44 4.98 26.00 1.40 2.39 4.87. 27.00 1.37 .2.34 4.78 28.00 1.34 2.29 4.69 29.00 1.32 2.25 4.60 30.00 1.30 2.21 4.52 I NO I a DRAINAGE CRITERIA MANUAL (V. 1) RUNOFF 2.4 Time of Concentration One of the basic assumptions underlying the Rational Method is that runoff is a function of the average rainfall rate during the time required for water.to flow from the most remote part of the drainage area under consideration to the design point. However, in practice, the time of concentration can be an empirical value that results in reasonable and acceptable peak flow calculations. The time of concentration relationships recommended in this Manual are based in part on the rainfall -runoff data collected in the Denver metropolitan area and are designed to work with the runoff coefficients also recommended in this Manual. As.a'result, these recommendations need to be used with a great deal of caution whenever working in areas that may differ significantly from the climate or topography found in the Denver region. For urban areas, the time of concentration, t,, consists of an initial time or overland flow time, q, plus the travel time, t„ in the storm sewer, paved gutter, roadside drainage ditch, or drainage channel. For non - urban areas, the time of concentration consists of an overland flow time, t,, plus the time of travel in a defined form, such as a swale, channel, or drainageway. The travel portion, t„ of the time of concentration can be estimated from the hydraulic properties of the storm sewer, gutter, swale, ditch, or ' drainageway. Initial time, on the other hand, will vary with surface slope, depression storage, surface cover, antecedent rainfall, and infiltration capacity of the soil, as well as distance of surface flow. The time of concentration is represented by Equation RO-2 for both urban and non -urban areas: tc = ti + ti (RO-2) in which: t, = time of concentration (minutes) ti = initial or overland flow time (minutes) t, = travel time in the ditch, channel, gutter, storm sewer, etc. (minutes) 2.4.1 Initial Flow Time. The initial or overland flow time, ti, may be calculated using equation RO-3:, wEts i.e to Mvous o noo 0.395 1 I- C gECRU�i! S WA ttJ /o tJjt" F1 f F7- . ti 5,033 5 (RO-3) in which: t; = initial or overland flow time (minutes) C5 = runoff coefficient for 5-year frequency (from Table RO-5) 06/2001 RO-5 Urban Drainage and Flood. Control District RUNOFF DRAINAGE CRITERIA MANUAL (V. 1) L = length of overland flow (500 ft maximum for non -urban land uses, 300 ft maximum for urban_ land uses) S = average basin slope Oft) Equation RO-3 is adequate for distances up to 500 feet. Note that, in some urban watersheds, the overland flow time may be very small because flows quickly channelize. 2.4.2 Overland Travel Time. For catchments with overland and channelized flow, the time of concentration needs to be considered in combination with the overland travel time, t„ which is calculated using the hydraulic properties of the sw.ale, ditch, or channel. For preliminary work, the overland travel time, t,, can be estimated with the help of Figure ROA or the following equation (Guo 1999): V = CyS.0.5 (RO-4) in which: V = velocity (ft/sec) C,, = conveyance coefficient (from Table RO-2) SK, = watercourse slope (ft/ft) TABLE RO-2 Conveyance Coefficient, C,. Type of Land Surface Conveyance Coefficient, C Heavy meadow 2.5 Tillage/field 5 Short pasture and lawns 7 Nearly bare ground 10 Grassed waterway 15 Paved areas and shallow paved swales 20 The time of concentration, t,, is then the sum of the initial flow time, tr, and the travel time, t„ as per Equation RO-2. 2.4.3 First Design Point Time of Concentration in Urban Catchments. Using this procedure, the time of concentration at the first design point (i.e., initial flow time, tr) in an urbanized catchment should not exceed the time of concentration calculated using Equation RO-5. t°=1L +10 (RO-5) G -• . 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Q > U to N to n O tf) O N N 4) N N NO c_ v ca N A N co p ca 2W 3 O LC,a% 3 to d E cc ccaa .0 o �rnrzN �� N d co O O O y m > i pccozOR w J N co O co � > O m m 0 U C. a) O C II II L O cL F- d ~ ai o � d U CO ( E f0 co 0: «- h C Zcr o LL N U «O c W 65 C O t jLO v 0) Q O M O � 11 c H .- MGM a ��'.-.'-N 0 'c �O 0 W o) 0) 0) c_O) rc C) O W O ° �0 0 0 0 F~c Ern to to to `oE cNNNO Ef2EOCCC > � e- 0 > N cmN O cm 7 cc to rn N Z 8 r O on CD N N N O w O O O O O O O O �cNNNO J IF —EOOOO N N N N O U S T 0 0 0 0 {p cc NNNN z 8 O O O 0 O ca U) 0000 cc m O C C O in i OOO to ° J W co co Go T H t ° dOmmo) H E F F E (V (V N (V II V O NNNN O O O O O C 0 G NC cc co �. to to to to C N 0 0 O N N aoOy ICCN"4'C'4 3�3 E�c4)�0 v � �i. c vcoOO (o �nO C 0)U •EL � oocic ° cortnM a-- •- M O L «: O v C • O < Q ° O Cl a a + ° > .-C H e N N M (0co 0 + JU IV 80 .-NNM I Appendix B 1 1 1 1 1 1 1 1 1 1 1 u Normal Flow Analysis - Trapezoidal Channel Project: 1635 South Lemay Avenue Channel ID: SWALE 1 E----------- -I------------- Yo Fo 1 W Zl E-----8------> Z2 Desi n Information (input) Channel Invert Slope So = 0.0100 ft/ft Channel Manning's N N = r 0.035 Bottom Width B = 0.0 ft Left Side Slope Z1 =, 4.0 ft/ft Right Side Slope Z2 = 4.0 ft/ft Freeboard Height F = 0.6 ft Design Water Depth Y = 0.43 ft Normal Flow Condtion Calculated Discharge Q = 1.1 cfs Froude Number Fr = 0.57 Flow Velocity V'= 1.5 fps Flow Area A = 0.7 sq ft op Width T = 3.4 ft Wetted Perimeter P = 3.5 ft J Hydraulic Radius R = 0.2 ft Hydraulic Depth D = 0.2 ft Specific Energy Es = 0.5 ft Centroid of Flow Area Yo = 0.1 ft Specific Force Fs = 0.0 kip TBS-CHOi.xls, Normal 5/16/2007, 11:02 AM Normal Flow Analysis - Trapezoidal Channel 11 Project: 1635 South Lemay Avenue Channel ID: SWALE 2 F T YO Y : 1� O 1 7 Zl t-----B------ > Z2 Desi n Information (Input Channel Invert Slope So = 0.0100 Wit Channel Manning's N N = 0.035 Bottom Width B = 0.0 ft Left Side Slope Z1 = 4.0 Wit Right Side Slope Z2 = 4.0 ft/ft Freeboard Height F = 0.6 It Design Water Depth Y = 0.45 ft Normal Flow Condtion Calculated Discharge Q = 1.3 cfs Froude Number Fr = 0.57 Flow Velocity V = 1.5 fps Flow Area A = 0.8 sq ft Top Width T = 3.6 It Wetted Perimeter P = 3.7 It Hydraulic Radius R = 0.2 It Hydraulic Depth D = 0.2 It Specific Energy Es = 0.5 it Centroid of Flow Area Yo = 0.1 it Specific Force Fs = 0.0 kip 0 TBS-CH02.xls, Normal 5/16/2007, 11:02 AM I ppendix C Design Procedure Form: Porous Landscape Detention (PLD) ' Designer. J. Miller Company: DMW Civil Engineers, Inc. Date: Project: March 8, W07 ISM South Lemay Avenue Location: Water Quality Pond 1. Basin Storage Volume . (I. = 100% if all paved and roofed areas u/s of PLD) 4 = 50.00 % A) Tributary Area's Imperviousness Ratio ( = la/ 100) 1= 0.50 B) Confibutirg Watershed Area Including the PID (Area) Area = 15,280 square feet C) Water Quality Capture Volume (WOCV) WQCV = 0.17 watershed inches (WQCV=0.8•(0-01 •e-1.1g'IZ+0.78'0) D) Design Volume: Voles _ (WOCV 112) • Area Vol = 210 cubic feet 2. PLD Surface Area (ApLD) and Average Depth (dw) Aw = 210 square feet (from 210.1 square feet to 4202 square feet) (d,,,: _ (Vol / Aaa), Mn-0.6, Mar-1.0) 4,. = 1.00 feet 3. Draining of PLD (Check A. or B, or C, answer D) X Infiltration to Subgrade with Permeable Based on answers to 3A through 3D, check the appropriate method Mlembrane: 3(C) checked and 3(E) = no A) Check box if subgrade is heavy or expansive day Underdrain with Impermeable B) Check box If subgrade is silly or clayey sand FEXEI Liner. 3(A) checked or 3(E) = yes C) Check box if subgrade is well -draining soil - Underdrain with Non -Woven Geoterdile Fabric: D) Check box if underdrains are not desirable or 3(B) checked and 3(E) = no if underdrains are not feasible at this site. 16Mi. Impermeable Mlembrane with No Underdrain: E) Does tributary catchment contain land uses that may have 3(D) checked - Evapotranspiration only . petroleum products, greases, or other chemicals - present, such as gas station. ves no Other. hardware store, restaurant, etc.?X . 4. Sand/Peat Km and Gravel Subbase (See Figure PLD-1) A) Heavy or Expansive Clay (NRCS Group D Soils) Present; 18' Minimum Depth Sand -Peat Mix with W Gravel Layer. 16M1. Perforated HDPE Underdrain Used. - Impermeable Liner and a 3'to 4' Perforated HDPE Underdmin. B) Silly or Clayey Sand (NRCS Group C Soils) Present; . Perforated HDPE Underdram Used. 18' Minimum Depth Send -Peal Mix with 8' Gravel Layer and a 3'to 4' Perforated HDPE Underdrain wf Nan -Woven Pemeable Membrane. C) No Potential For Contamination And Well-Dminkg X 18' Minimum Depth Sand -Peat Mix with Non -Woven (MRCS Group A or B Soils) Are Present; Underdmins Eliminated. Pemeable Membrane and No Underdrain (Direct Infiltration). D) Underdrains Are Not Desirable Or Are Not Feasible At This Site. 18' Minimum Depth Sand -Peal Mix with An Additional I Minimum Layer Sand -Peat Mbr or SandlXass'A Compost Bottom . Layer (Total Sand -Peat Depth of 36). 16MI. Impermeable Liner Used. E) Other. Other: ' Notes: ' TBS-BMP.bs, PLD 5/162007, 10:58 AM 1 1 1 1 1 , Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility Designer. JPM Company: DMW Civil Engineers, Inc. ©T Date: May %=7 Project 1636 South Lemay Avenue j Location: Hypothetical Extended Detention pond 1. Basin Storage Volume I, = 50.00 % A) Tributary Area's Imperviousness Ratio ( = 6 / 100) i = 0.50 B) Contributing Watershed Area (Area) Area = 0.350 acres C) Water Quality Capture Volume (WQCV) WQCV = 021 watershed inches (WQCV=1.0-(o.91'h-1.19'Ir+0.78`D) D) Design Volume: Vol = (WQCV / 12) ' Area ` 1.2 Vol = 0.0072 acre-feet 2. Outlet Works A) Outlet Type (Check One) I x Orifice Plate Perforated Riser Pipe Other: B) Depth at Outlet Above Lowest Perforation (H) - H = 11.00 feet C) Recommended Maximum Outlet Area per Row, (A.) A, = 0.05 square inches D) Perforation Dimensions: ) Circular Perforation Diameter or D = 0250 inches i) Width of 2- High Rectangular Perforations W = inches E) Number of Columns (nc, See Table 6a-1 For Mmdmum) nc = 1 number J F) Actual Design Outlet Area per Row (A.) Ao = 0.1 square inches G) Number of Rows (nr) nr = 3 number L H) Total Outlet Area (A, Ad = 02 square inches, 3. Trash Rack A) Needed Open Area: Ar = 0.5 • (Figure 7 Value)" Ay B) Type of Outlet Opening (Check One) C) For 2", or Smaller, Round Opening (Ref.: Figure 6a): Width of Trash Rack and Concrete Opening (Ww ) from Table 6a•1 i) Height of Trash Rack Screen (I-W A, 6 square inches x < 2' Diameter Round 2' High Rectangular Other: t Wes= 3 inches Hm = 42 inches e ' TBS-BMP.ids, EDB 5M 6r"7,10:59 AM IIDesign Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility II Sheet 2 of 3 Designer: JPM Company: DMW Civil Engineers, Inc. Date: May 8,2007 Project 1635 South Lemay Avenue Location: Hypothetical Extended Detention pond ii) Type of Screen (Based on Depth H), Describe if "Other' 1 iv) Screen Opening Slot Dimension, Describe if'Ofhe' v) Spacing of Support Rod (O.C.) Type and Sae of Support Rod (Ref.: Table 6a-2) . 'vi) Type and Sae of Holding Frame (Ref.: Table 6a-2) D) For 2' High Rectangular opening (Refer to Figure 6b): Width of Rectangular Opening (W) i) Width of Perforated Plate Opening (W. = W + 127 ii) Width of Trashrack Opening (Wo,,;,,,) from Table 6b-1 iv) Height of Trash. Rack Screen (Hcx) v) Type of Screen (based on depth H) (Describe N-Other7 w) Crossbar Spacing (Based on Table 6b-1, Kiempn" KPP Grating). Describe K-Other vii) Minimum Bearing Bar Sae (IOempn" Series, Table 6b-2) 4. Detention Basin length to width ratio 5 Pnseedimerdation Forebay Basin - Enter design values A) Volume (3% to 5% of Design Volume from 1 D) (3% - 5% of Design volume (0.0002 - 0.0004 acre-feet) B) Surface Area C) Connector Pipe Diameter (Sae to drain this volume in 5-minutes under inlet control) D) Paved/1-lard Bottom and Sides S.S. #0 VEE Wire (US Filler) Other. 0.139- (US Filter) Other. inches W = inches W.= inches W,,,;,,= inches HTR = inches Kiemp7°" KPP Series Aluminum Other. inches Other. Iffi2l] acre-feet acres inches yesino ' TBS-BMPxIs, EDB 5f16QD07,10:59AM Designer. Company: Date: Project Location: Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility i JPM DMW Civil Engineers, Inc. ' May 8,2007 1635 South temay Avenue Hypothetical Extended Detention pond Sheet 3 of 3 _\ O#lc J5y 6. Two -Stage Design - See Figure EDB-1 A) Top Stage (Depth Derr = 7 Minimum) Dwo = feet Top Stage Storage: no less than 99.5% of Design Volume (0.0072 acre -few) Storage= acre-feet B) Bottom Stage Depth (Das = 0.33' Minimum Below Trickle Channel Invert) Das = feet Bottom Stage Storage: no less than 0.5% of Design Volume (0 acre-feet) Storage= acre-feet Storage = A ` Depth Above WS To Bottom Of Top Stage Surf. Area-- acres C) Micro Pool (Minimum Depth = the Larger of Depth= feet 0.50' Top Stage Depth or 2.5 Feet) D) Total Volume: V66 = Storage from 5A + 6A+ 6B Voles = acre-feet (Must be > Design Volume in 10, or 0.0072 acre-feet.) - 7. Basin Side Slopes (Z, horizontal distance per unit verdcal) Z = Mor¢ontaWertical) Minimum Z = 4, Flatter Preferred . 8. Dam Embankment Side Slopes (Z. horizontal distance) Z = (horaordaUvenccal) per unit verticaQ Minimum Z = 3, Flatter Preferred _ 9. Vegetation (Check the method or describe 'Other) Native Grass Irrigated Turf Grass Other. s TBS-BMP.tds, EDB 5f16=7, 10:59AM Trapezoidal Weir Calculations i Project: 1635 South Lemay Avenue Calculations By: J. MILLER Project No.: TBS DMW Civil Engineers, Inc. Location: Pond 1 Outlet Date: 05/15/07 r Input Parameters: Design Discharge = Length = Height = Weir Coefficient = Internal Angle = V-Notched Weir Exponent = Weir Calculations: Capacity = Depth of Design Discharge = r e Q = 2.40 cfs L = 2.00 ft H = 0.50 ft Cw = 3.33 O = 151.93 ° b = 1.50 4.24 cfs D = 0.34 FT TBS-OW01.xls, Pond -FAA 1 of 1 I J 0 0 Appe ix 1 wl e hAiz F c 4-y. �-' "i �� ram+ ,s� • 209 �. Eoci 1— n p n R y a 4 ..�• 2C 217 , _. yT R < ^ f .. 22 374 22 � z582 T#TE �' SPRING C 20 �, s 29 215 A�. 447 221` 2 � -.. .. �,^ eu.•�+ a ��? 4c.3 216 rs " 5 t� 'y ,,pyF*, - wl 1 "w 24 3kq. t Y caF.Y � � • i j � F - 2 � .'®a•E�'� tt -' � . y_ kk PARKW00 1 ,.• --� _ _ ; >�`, a`� LAKE77, ns 1636 SOUTH LEMAY AVENUE Bat IMPERVIOUS ANALYSIS OS/19/07 I'-=* IMPERVIOUSNESS - D BASED ON ZONING NII CIVIL ENGINEERB f 1475 Wnt 29N Street, lnwelonq Cdwo&, 60576 . Phone: (970)/61-266t, F= (970)161-2665 m.Emrpvikn9ineen.com 1 Sheet 1 Sheets m)"` 1635 SOUTH LEMAY AVENUE oats IMPERVIOUS ANALYSIS 05/15/07 scalm 1 NC ZONE IMPERVIOUSNES BASED ON ACTUAL CIVIL ENGINEERS` ` 1435 Weal 29M Sbeet, lnvdand. Ccgo de. 80538 Prom: (970)461-2661. F= (970)461-2665 a e..UmwcMlcngine =m 1 Sheet 1 Sheets Confirm Analysis in Master Drainage Plan: Imperviousness based upon zoning Zone Area Impervious NC 3.96 90.0% MMN 6.43 70.0% LMN 21.17 50.0% Total 31.56 59.1% 59.1 % is less than the 65% assumed in the Master Drainage Plan. Therefore the 1635 South Lemay Ave site, zoned NC,. was assumed to be at least 90% impervious. Actual analysis of NC zoned area: Total Area 3.96 Roof 0.41 Concrete 0.34 Asphalt 1.02 Total imp. 1.77 % imp. 44.8% No Text 1 1 J i 1 .1 r 1 1 U .1 i 1 .1 Subbasin boundaries were modified for three principal reasons:, (1) to correct inaccurate boundaries as dictated by actual drainage patterns, including major roads which act.as drainage divides; (2) to accurately reflect the area tributary to local detention ponds; and (3) to correct the point of concentration for an area. A map showing the revised subbasin boundaries within the study area is provided on Sheet Al. A schematic diagram for the 2001 SWMM.model is provided on Sheet A2. Documentation of the revised subbasin parameters is presented in Appendix B. Each of the subbasins in the study area were modified in response to the evaluation described in Section A2.1.. Within the area upstream of.Taft Hill Road and downstream of College Avenue, a complete basin re -delineation was performed to represent the actual flow divides and land usage using the best available mapping. The subbasin re -delineation was performed using City of Fort. Collins quarter section mapping at a scale .of 1 "=100' with a contour interval of 2 feet. In the extreme western portion of the basin, the subbasin re -delineation was performed using the USGS Horsetooth Quadrangle map. Where available, grading plans for individual developments were used to help define local subbasin boundaries and flow direction. The surface retention storage depth, . roughness coefficients and infiltration parameters were modified for each ofthe subbasins within the study area to conform to. current City criteria. The subbasin width for each of the subbasins within the study area was recalculated in conjunction with the current SWMM model revisions. Although SWMM does not specifically use overland flow length as an input parameter, it was estimated for each subbasin in order to calculate the corresponding subbasin width.. Generally, the overland flow length was estimated for each subbasin by averaging the distances associated with several representative flow paths as defined using the topographic mapping. The subbasin width was then computed by dividing the overland . flow length into the subbasin area For the 130 subbasins within the entire Spring Creek Basin, the subbasin width calculations resulted in a range of overland flow. lengths that vary from 70 to 1,372, with a weighted average of 524 feet: As modeled, the overland flow lengths.and corresponding subbasin widths appear to be reasonably representative of the actual runoff conditions in the Spring Creek Basin. Documentation . of the results of the subbasin width parameter calculations are presented in Appendix B. . Impervious, percentages were assigned using estimated development densities, and.. . considering current land use and zoning classifications in. the basin. The following general guidelines were developed for assigning impervious values to individual subbasins: • Open space along the foothills ridge. (POL, RF) = 20 percent • Open space and parks (POL) = 10 percent Estate and foothill residential lots (RF, UB) a 30 percent T:\OPEN\Cofc171COFC17hydrologytext.doc A-12 ANdERSoN CONSUITINq ENGINEERS, INC. ' Existing single family residential (RL) and low density neighborhood conservation (NCL) = 45 percent Future low density, mixed use neighborhood (LMN) and medium density neighborhood conservation (NCM) 50 percent ' Medium density, mixed use neighborhood (MW and neighborhood conservation buffer (NCB) = 70 percent ' Employment (E) and river commercial (RC) = 80 percent I . Commercial (C), neighborhood commercial (NC) and industrial (1) = 90 percent ' Exceptions were made to these general assumptions in areas such as cemeteries, schools and campus facilities where impervious percentages were adjusted considering.the actual existing land use. Additional parameters, including overland roughness values, surface storage, and infiltration rates were defined using standard values currently specified by the Stormwater Utility. The ' following values were used for these parameters: . . Overland roughness coefficient (impervious areas) 0.016 Overland roughness coefficient (pervious areas) = 0.250 Surface storage (impervious areas) _ .0.1 inches Surface storage (pervious areas) a 0.3 inches . _ Initial infiltration rate = 0.51 in/hr' Final infiltration rate 0.50 in/hr Decay rate coefficient 0.0018 sec 1. A2.4 Update and Addition of Detention Ponds ' As noted in Section A2.1, the rating curves for four ponds were modified in the area upstream of Taft Hill Road and eleven rating curves were either modified or added downstream of College Avenue. Since the current study represents the completion of revisions to the Spring Creek ' Master Plan model, a summary of each of the detention ponds within -the basin is given in this. section, in .numerical order of the SWMM model ID. The complete documentation of the . ' development of the rating curves is provided in Appendix C. The CSU Veterinary Teaching Hospital (VTH) Pond (#50) is a regional detention pond located within the VTH.site, directly north of Drake Road. The existing pond outlet pipe is a 24- ' TA0PEN\CofC17%COFC17 hydrology teAdoc' A-13 ANdERSON CONSULTING. ENC{iNEERS, INC. Table A3.1 Spring Creek Discharge Summary for Fully -Developed Conditions with Existing Drainage Facilities. - em t• c Spring Creek at confluence with Cache La Poudre River 702 849 1,339 2,867 Spring Creek at C&SRR 610 853 1,342 3,354 Spring Creek at Lemay Avenue 720 841 1,435 3,554 Spring Creek at Stover Street 729 820 1,249 3,123 Spring Creek at College Avenue _ 321 801 1,Z33 2,940 Spring Creek at BNRR 303 798 1,232 2,939 Total Spring Creek inflow to BNRR Pond 703 925 1,954 4,581 Spring Creek at Arthur Ditch 327 698 1,496 3,643 Spring Creek upstream of confluence with Canal Importation Channel 328 660 1,384 3,008 Spring Creek at Shields Street 330 659 1,383 2,99.6 Spring Creek atLarimer County Canal #2 331 646 1,337 2,862 Spring Creek at New Mercer Ditch 332 493 1,071 2,378 . Spring Creek at Drake Road 335 322 785 1,855 Spring Creek at Taft Hill Road 304 207 579 1,356 Spring Creek upstream of Taft Hill Road Detention Pond 236 .207 599 2,644 Spring Creek at Pleasant Valley and Lake Canal 338 162 9 1,871 Pitkin/Riverside flow path at confluence with Spring Creek 603 1 29 100 Parkwood Lake Outflow 640 3 . 4 5 Parkwood Lake Inflow 740 310 620. 1,586 Proposed VTH Outfall Channel at confluence with Spring Creek 261 88 255 579 Trend -Cedar Diversion Channel at confluence with. Spring Creek . 101 90 204 564 Ta0PEN\Cofc17\C0FC17 hydrology text.doc A-27 ANdERSON CoNsutfiNC{ ENGINEERS, INC. - SPRING CREEK EOSIN MASTER PLAN HYDROLOGIC MODEL 100-YEAR . 3.67-IN (DEVELOPED) PILE: SC100DEV FEB 2003 ANDERSON CONSULTING ENGINEERS ' . ''• PEAK FLOWS, STAGES AND STORAGES OF GUTTERS AND DETENTION DAMS '" NOTE :S IMPLIES A SURCHARGED ELEMENT AND :D IMPLIES A SURCHARGED DETENTION FACILITY CONVEYANCE PEAR STAGE STORAGE TIME ELEMENT:TYPE (CPS) (FT) (AC -FT) (HR/MIN) 7:3 110.6 (DIRECT FLOW) 0 46. 8:3 .148.1 (DIRECT FLOW) 1 16. 27:3 3924.8 (DIRECT FLOW) 1 28. 29:3 469.4 (DIRECT FLOW) 1 18. ' 34:3 20.2 (DIRECT FLOW) 0 43. 38:3 23.7 (DIRECT FLOW) 0 46. 43:3 593.5 (DIRECT FLOW) 2 10. 50:2 520.0 .0 21.3:D 1 17. 51:2 536.7 .0 16.O:D 0 56. I ' - 52:3 408.3 (DIRECT FLOW) 1 21. 101:4 563.9 4.4 0 51. 102:5 108.6 2.7 0 41. 103:2 50.5 .1 23.6:D 2 9. 104:5 461.0 '5.5 0 .42. 105:5 149.9 3.0 0 40. ' 106:5 279.8 4.4 0 37. 107:5 106.6 2.8 0 36. 108:2 88.0 .1 6.6:D 0 53. 109:2 1.7 .1 1.3:D 2 S. 110:5 118.6 2.9 - 0 35. 112:2 421.5 5.1 0 36. ' 112:2 21.5 .1 3.D:D � 1 6. 114:1 211.E 3.4 0 38. 118:1 565.9 3.6 0 50. 119:1 560.9 3.9 0 49. - 120:1 539.8 3.7 i 0 47. 123:1 441.E 4.0 0 47. ' ' 124:1 377.9 4.0 0 44. 126:1 379.9. 4.0 0 42. 127:5 407.5 4.2 0 37. - 128:1 16.1 1.3 - 1 21. 129:1 205.0 3.7 0 40. 13:. 2. 0 3. 131:5 116116 .4 3.2 0 366. 153:4 303.9 1.6 0 35. 156:3 303.9 (DIRECT PLOW) 0 35. 160:1 517.1 4.3 - 1. 21. 161:1 559.1, 2.9 1 22, 170:5' 16.6 1.6 1 6. ' 171:5 21.3- 1.6 1 '15. 173:5 164.5 2.7 0 36. 174:1 4.1 .2. 2 3. - 175:5 193.6 3.2 0 47. 177:5 263.8 4.2 - 0 48. 178:5 - 870.7 6.7 0 37. ' 179:5 223.2 3.7 0 36.' 180:5 15.3 1.8 1 16. 181:5 530.4 5.8 '1 0. 187:5 101.5 2.9 0 35. 0 i 218:5 218 :4 938.7 2938 .7 7.4 7.4 15. 3 15. ' 221:5 513.7 4.8 0 38. 222:4 2939.5 7.0 3 16. 226:4 3623.9 7.1 1 29. 227:1 3531.7 4.2 1 25. 228:1 2954.8 1 - 2291 2954.E - 6.0 6.0 19. 1 19. 230:4 2936.4 8.3 1- 17., 231:4 2440.4 6.1 1 13. 232:4 1899.9 7.2 1 10. - 233:2 402.5 '4.5 0 35. 234:4 1..2 1 S. 235:4 1477477.6 7.3 1 39. ' 236:4 2644.4 5.5 11 2. 237:4 2348.8 6.0 0 59. 238:4 1862.1 S.0 0 57. 239:4 1571.9 4.8 - 0 57. 24:1 241:9 .5 1390390.9 - 2,3 4.3 0 47, 0 47. ' 242:4 695.0 3.0 0 43. 243:4 453.5 3.1 0 41. 244:1 199.9 2.2 0 41. 245:1 176.1 2.1 0 36. 2: 26060:3 191.9 560.1 (DI (DIRECT PLOW) 0 37.E 1 20. ' 261:3 578.5 (DIRECT FLOW) 1 21. 271:3 106.3 (DIRECT FLOW) 0 47: - 272:3 21.4 (DIRECT FLOW) 0 45. 273:3 84.9 (DIRECT FLOW) 0 47. -� 274:3 72.7 (DIRECT FLOW) 0 55. 275:3 69.2 (DIRECT FLOW) 0 55. 276:3 3.5 (➢IRECT FLOW) 0 56. 277:3 289.0- (DIRECT FLOW) 0 36. 278:1 1.3 .2 1 24. . 279:4 174.2 .9 0 36. 282:2 72.7 .0 S.O:D 0 55. ' 287:2 45.6 -.1 11.5,D 1 21. 288:2 2.7 .1 4.6:D 2 11. 289:2. 4.5 '.1 6.6:D 2 13. • 295:3 372.5 (DIRECT FLOW) 2 38. .. 296:3 17.8 (DIRECT FLOW) 0 41. 297:3 46.0 (DIRECT FLOW) 0 19. Page 13 of 15 298:3 115.0 (DIRECT PLOW) 0 31. 299:3 57.0 (DIRECT PLOW) 0 26. 303:2 2939.3 .1 435.7:D 3 14. 304:2 1356.3 .1 78.O.D 1 46. 318:2 11.4 .1 8.5:D 2 6. 321:3 2939.6 (DIRECT PLOW) - 3 IS. 327:3 3643.1 (DIRECT RAY) 1 23. 328:3 3008.4 : (DIRECT PLOW) 1 21. 330:3 2995.8 (DIRECT PLOW) 1 19. 331:3 2861.5 (DIRECT FLOW) 1 14. 332:3 2378.4 _(DIRECT PLOW) 1 10. 333:2 6.4 .1 S.O.D 2 3. 334:2 6.1 .1 4.9:D 2 2. 335:3 1855.0 (DIRECT FLOW) 1 3. - 336:21 151.6 .1 4.4:1) 0 47. 337:3 409.3 (DIRECT FLOW) 0 35. 338:3 1870.7- (DIRECT PLOW) 0 55. 340:2 109.7 .1 72.O:D 2 S. 349:2 55.6 .1 8.2:D 1 13. 355:3 372.5 (DIRECT PLOW) 0 41. 356:3 117.3 (DIRECT FLOW) 0 35. 357:2 266.3 - .1 8.7:D 0 55. 350:2 126.0 .1 3.5:D 0 49. 360:2 29.0 _ .1 2.5:D 0 58. 361:2 2.3 .1 .7:1) 1 30. 362:2 1.5 .0 1.4:D 2 6. 363:2 4.8 .0 4.4:0 2 6. 364:2 7.5 .0 3.5.D 2 2. 370:2 27.7 .0 1.7:D 0 51. 371:2 106.3 .0 4.4:1) 0 47. 373:2 77.9 .0 13.8:D 1 32. 373:2 100.0 .0 .5.3:D 0 46. 374,2 4.2 '.0 1.7:D 2 0. 380:2 18.6 .0 1.3:D 0 49. 395:3 372.5 (DIRECT PLOW) 2 38. 396:3 105.0 (DIRECT PLOW) 3 38. 402:4 2866.6 5.0 1 16. 406:4 154.2 .8 0 36. .407:1 230.1 1.9 0 37. 408:4 231.9 .8 0 36. 409:4 341.4 1.4 0 38. 410:3 4243.9 (DIRECT PLOW) 0 54. 411:4 192.1 .9 0 36. 412:4 4116.3 8.1 0 54. 414:4 3815.5 7.9 0 52. 415:4 287.6 .9 0 36. 417:4 318.4 .9 0 36. 419:4 3597.4 7.5 0 50. 420:4 3113.6 5.5 3 28.4- 421:4 167.1 1.2 0 37. 422:4 265.7 '1.1 0 38. 423:4 454.0 1.2 0 41. 424:4 199.6 1.1 - 0 37. 425:4 3116.4 6.2 3 25. 427:4 357.3 .9 0 36. 428:4 104.9 .6 0 37. `429:4 3114.0 7.0 3 20.' 430:4 524.5 1.4 0 37. 432:4 3051.6 6.9 '3 19. 43324 3050.4 7.9 3 17. .434:4 152.3 .7 0 36. 435:2 119.3 3.2 0 33. 436:5 187.0 4.8 2 42. 441:4 292.7 1.1 - 0 37. 443.4 413.9 1.2 0 43. 445.1 134.8 .9 0 36. 446:4 182.6 .9, 0. 37. 447:5 845.9 6.8 0 44. 449:5 211.9 3.3 0 36., 4SOA 277.2 1.0 0 39. 451L4 212.7 1.0 - 0 37. 452:4 154.7 1.3 0 36. 453:5 541.0 5.2 0 37. 455:4 265.2 1.3 0 38. 508:1 542.8 3.5 0 39. SIOA 2868.3 5.0 1 13. 513:5 40.6 2.3 1 22. 514A 3992.3 0.0 0 53. 515:4 262.2 .8 0 41. 517:5 307.1 4.0 0 37. 518:2 9.0 .9 2 S. 519:4 3730.4 7.6 0 51. 520:4 3535.1 7.5 0 49. 521:4 164.7 .8 0 39. 522.4 894.9 .1.3 0 43. 523:4 659.3 1.6 0 42. 524:4 1046.1 - 1.7 0 43. 'S25:4 3115.0 S�.5 3 27. 528:4 96.0 .6 0 41. 529A 3119.1 6.2 3 32. 530:2 5.8 .8 3 15. 533A 3050.9 - 6.9 3 18. 534:4 139.1 .6 0 38. 535:4 81.3 .6 0 44. 536:5 189.8 4.8 2. 45. 537:2 3.3 .8 2 19. 540:2 4.8 .9 10 26. 543:4 401.7 1.1 0 45. 548:4 307.5 1.0 0 41. 549:4 181.8 1.2 0 40. 552:2 14.2 .9 1 45. 553:5 751.3 6.6 0 42. 554:5 178.3 3.7 0 36. Page 14 of 15 555:5 41.0 1.8 1 7. 595:1 187.0 1.0 2 39. 603:2 100.2 .1 22.1:D 3 26. 604:2 114.6 .1 37.6:D 2 3. 605:2 .0 .1 11.9:D 4 46. 610:2 3353.9 .1 63.7:D 1 7. 613:2 37.6 .1 _ 2.9:D 0 54. 616:2 96.5 .1 3.8:D 0 45. ' -618:2 9.1 .1 3.9:0 2 1. 637:2 3.3 .1 6.2:D 2 13. - 640:2 4.8 .1 121.9:D 10 10. 641:2 108.5 .1 7.5:D 0 57. ' 642:2 5.8 .1 1.9(D 2 0.- 646:2 59.9 .1 4.9:D 1 S. 652:4 120.9- 1.0 0 39. 655a4 200.9 1.2 0 43. 695 :3 187.5 (DIRECT FLOW) 2 38. 702:3 2866.6 (DIRECT FLOW) - 1 16: 703:3 4581.0 (DIRECT FLOW) 1 26. 706:3 918.0 (DIRECT FLOW) - 0 38. 707:3 .771.2 (DIRECT FLOW) 0 38. 708:3 562.9 (DIRECT FLOW) 0 37. 710:3 3353.9 (DIRECT FLOW) 1 7. 720:3 3553.7 (DIRECT FLOW) 0 47. 726:3 673.8 (DIRECT FLOW) 1 17. 727:3 3822.5 (DIRECT FLOW). 1 28. 729:3 3122.6 (DIRECT FLOW) 3 19. 730:3 524.5 (DIRECT FLOW) 0 37. 735:3 270.5 (➢IRECT FLOW) 0 35. 736:3 151.6 (DIRECT FLOW) 0 47. 740:3 1585.6 (DIRECT FLOW) 0 42. 749:3 211.9 (DIRECT FLOW) 0 36. 752:3 154.7 (DIRECT FLOW) 0 36. 755:3 265.2 (DIRECT FLAW) 0 38. 810:3 2920.9 (DIRECT FLAW) 1 7. ` 830:3 5.8 (DIRECT FLOW) 0 28. 835:3 111.0 - (DIRECT FLAW) 0 41. " 836:3 64.9 (➢IRECT FLOW) 0 47. 849:3 14.2 (DIRECT FLAW) 0 29. 852:3 14.2 (DIRECT FLAW) 0 38. 855:3 41.0 (DIRECT FLOW) 0 24. 910:3 433.0 (DIRECT FLAW) 1 7. 925:3 148.1 (DIRECT FLOW) 1 16. 930:3 518.7 (DIRECT FLOW) 0 37. 931:4 2873.0 8.2 1 17. 934:4 1448:8 7.1 1 39. 935:3 159.5 (DIRECT FLOW) 0 35. 936:3 86.7 (DIRECT FLOW) 0 48. 937:4 2476.5 5.8 1 1. 938:4 2149.7 5.6 - '0 58. 941:4 1349.8 4.3 0 52. 945:1 157.3 1.7 0 41. 947:1 187.9 2.0 0 40. 949:3 197.7 (DIRECT FLOW) 0 37. 952:3 140.5 (DIRECT FLOW) 0 37. . 953:1 490.5 2.4- 0 45. 955:3 224.2 (DIRECT FLOW) 0 39. 960:3 1179.7 (DIRECT FLOW) 0 44. 961:3 1411.6 (DIRECT FLAW) 0 47. 962:3 1679.5 (DIRECT FLAW) 0 51. 963:3 2155.7 (DIRECT FLOW) 0 56. 964:3 2374.1 (DIRECT FLOW) 0 57. 965:3 1769.6 (DIRECT FLOW) 1 3. 966:3 3543.3 - (DIRECT FLAW) 1 20: 967:3 4007.0 (DIRECT FLAW) 0 52. 968:3 2483.0 (DIRECT FLAW) 1 0. 969:3 3747.8 (DIRECT FLAW) 0 49.' 974:3 84.9 (DIRECT FLAW) 0 47. ERDPROGRAM PROGRAM CALLED Page 15 of 15 Spring Creek Hydrologic Model Update -July 1999 . Anderson Consulting Engineers, Inc. - COFC98.12 ' SWMM Model Subbasin Parameters i $ubbasln 1 Area I Width r1v<H.nn - 143 72.2 7000 __.449 .. 449 ..,. �..w 12 rvn 0.062 77 170 37.3 4500 361 45 0.014 78 ' 180 51.7 4900 460 11 0.030 79 182 20.5 3400 263 40 0.015 80 184 4.0 1400 124 25 0.014 50 146 51:4 1900 1178 10 0.075 60 - 168 50.9 3450 643 28 0.078 61 ' 169 25.9 3700 305 45 0.013 62- 169 19.6 2800 305 45 0.009 69 - 171 14.7 2800 229 229 '45 0.010 64 144 - 76.3 5300 30 0.013 65 145 69.3 2200 1372 10 0.090 66 ' 147 125.6 4100 1334 10 . 0.080 67 148 4027 17350 1011 24 0.219 68 149 56.1 8000 305 45 0.010 202 150 99.5 6000 722 20 0.070 203 152 81.7 4800 741 13 0,148 ' 153 205.2 8000 1117 15 0.128 .204 206 154 139.5 10000 608 18 0.083 206 1 27.8 3900 311 40 0.016 207 100 43.9 5500 348 - 40 0.016 208 2 3 10.7 10. 5000 550 280 847 40 10 0.010 0.016 209 210 4 19.3 2400 350 40 0.010 211 5 39.6 5100 338 40 0.020 211 6 47.2 6500 316 40 0.010 213 7 8 27.6 50.4 3600 7700 334 285 30 45 0.013 0.010 214 215 9 6.4 1100 253 60 0.010 216 . 10 20.0 3000 290, 30 0.033 217 11 42.4 4000 462 O70 0.013 218 12 14 18.9 2800 294 45 060 219 583 62 0.013 220 158 60.9 8000 334 332 40 0,015 221 158 70.6 70.6 9200 9200 334 40 0.015 222 137 58.4. 7600 335 40 0.015 223 38. 39.1 $000 213 63 0.0" 224 139 18.6 2500 324 45 0.020 225 141 49.4 5000 430 30 0.013 226 142 62.6 4500 606 30 . 0.034 227 121 62.4 5500 494 90 0.015 228 . 122 16.6 2500 289 75 0.010 229 125 22.6 2450 402 51 0.015 230 ' 126 72.6 7900 400 25 0.015 232 127 41.8 4557 400 25 0.015 233 128 41.7 6000 303 40 0.015 234 129 19.9, 3500 248 72 0.010 235 ' 130 131 90.3 17.8 15000 3700 262 210 50 60 0.020 0.025 236 237 132 22.1 5200 185 71 0.020 240 133 33.9 4900 301 67 0.025 241 37 17.1 2500 298 10 0.010 242 1 134 135 61.8 22.6 5500 7000 489 141 10 57 0.020 0.025 243 244 86 87 10.4 6470 70 100 0.020 245 53.7 9350 250 90 0.010 246 - - 88 17.8 3100. 250 82 0.010 247 89 7 25.4 2750. 402 90 0.010 248 14.0 2030 300 40 0.020 249 ' 71 421 4150 442 45 0.022 250 72 76.3 6650 500 40 0.020 261 73 24.9 3000 362 60 0.020 252 74 75 8.7 2920 130 60 0.015 253 34.9 3500 434 80 0.020 254 ' 76 33.2 1450 997 25 0.010 _ 255 109.1 9500 500 40 0.020 49.2 5360 400 40 0.020 9.3 1160 349 90 0.015 44.6 - 9500 205 45 0.029 30.8 3200 419 60 0.020 20.4 9800 91 90 0.010 5.9 857 300 70 0.010 18.3 3140 254 80 0.010 14.2 1550 399 90 0.010 6.5 500 566 8 0.009 ' 17.8 1550 Soo 55 0.009 29'2 1720 740 55 0.008 11.5 690 737 55 0.008 46.3 5000 403 59 0.020 24.6 - 4500. 238 90 0.020 35.6 5000 310 73 0.020 50.5 6000 367 43. 0.030 21.5 2600 360 90 0.014 37.6 4500 364 90 0.020 40.5 4400 401 54 0.012 68.2 6000 495 64 0.010 45.8 2500 798 90 0.020 26.0 3100. 365 - 75 0.015 61.4 6500 411 55 0.030 25.1 3500 312 70 0.020 48.0 4500 465 10 0.025 44.7 6000 325 55 0.010 31.3 4000 341 70 0.010 57.5 6500 385 45 0.020 18.4 - 1800 445 80 0.020 - 40.8 4500 395 79 0.035 31.7 3500 395 65F 0.035 40.3 4500 390 45 0.009 59.5 7600 370 53 0.008 74.9 7300 - . 447 45 0.005 37.4 4000 407 56 0.020 26.8 3100 377 50 0.030 35.9 4000 391 47 0.03S 48.5 5000 423 54 0.015 24.5 2500 - - 427 45 0.010 58,4 6000 - 424 50 0.025 110.2 10000 480 51 0.010 33.9 3700 399 27 0.028 33.9 3800 389 79 0.020 28.7, 3500 357 45 0.015 22.6 - 2700 365 55 0.015 20.4 3000 296 70 0.020 26.8 3500 334 60 0.020 47.9 7000 298 78 0.020 56.5 5600 439 53 -9.3 1250 324 90 .0.00.02020 34.1 5000 297 55 0.020 08 25.7 2800 400 54 0.008 22.2 2400 403 72 0.005 40.7 _ 4400, 403- 52 0.008 30.2 3300 399 60 0.013 30.3 3000 440 70 0.009 ' 35.5 5000 309 57 0.010 15.5 2500 270 67 0.008 40.9 4500 396 62 0.011 20.0 2500 348 90 0.013 I 83.7 8000 456 45 0.013 28.3 3500 352 45 0.018 J HYDROLOGICMODELINGAND HYDRAULICANALYSES ' FOR SPRING CREE%DOWNSTREAM OF EDORA PARS (Prepared in Support of a Conditional Letter of Map Revision ' Application for the C&SRR Detention Pond Pre Disaster Mitigation Grant Improvement Project and the Timberline Road Widening Project) ' Prepared jor. ' City of Fort Collins Utilities. 700 Wood Street Fort Collins, CO 80521 ' Prepared by: Anderson Consulting Engineers, Ina . 772 Whalers Way, Suite 200 Fort Collins, CO 80525 (ACE Project No.. COFC2005.06) . ' aO��Gi pRY , j'• s1)p U, i October 21, 2005 ' III. EXISTING CONDITION ANALYSES 3.1 Existing Condition Hydrologic Modeling ' The duplicate effective hydrologic (UDSWM2000) model described in Section 2.1 was modified to represent existing conditions as follows: (a) incorporating recently updated inflow ' hydrographs from both the Canal Importation and Old Town Basins; (b) revising the stage - storage -discharge curve for the Taft Hill Road Detention Pond to reflect detailed topography that ' has been acquired recently within the pond's active storage area; and (c) modifying subbasin boundaries and hydrologic parameters in the vicinity of the Timberline Road/Prospect Road. intersection in response to the recent Spring Creek Center development. These changes and the ' results of existing condition hydrologic modeling effort are described in the following sections. f Mt,D l- I6tcr1005 -7a M"FL. Do JJ&r AWE_C - fvP,T 46c.UtJ5 1 c �u B s ram` 3.1.1 Revised Inflow Hydrographs As documented in the Spring Creek. Basin Master Drainage Plan, the Spring Creek Basin receives runoff from the Canal Importation Basin primarily via spills from the three major ' irrigation canals that transect the western portion of the City of Fort Collins. Spills from the. Canal Importation Basin also enter the Old Town Basin, located directly. north of the Spring ' Creek Basin. These spills from the Canal Importation Basin to the Old Town Basin influence additional. inflows to the Spring Creek Basin, as part of the southern portion of the Old Town Basin directs runoff into Spring Creek via several existing storm sewer facilities. Two recent detention pond projects in the Canal Importation Basin have served to reduce runoff reaching the irrigation canals, thereby reducing outflows to both the Spring Creek and Old Town Basins.. These projects prompted a revised hydrologic analysis of the Canal Importation Basin, which included updating the unsteady. flow analyses of the. basin's three major canals. ' The hydrologic modeling changes and the revised inflow hydrographs to the Spring Creek and Old Town Basins are documented in the report; "Hydrologic Update for Canal Importation ' Basin," [ACE, April 2005]. Correlation of Canal Importation Basin. outflow hydrographs to Spring Creek Basin inflow hydrographs is provided in Appendix D.1 of the current report. Also included. in Appendix D:I is the documentation of the revised spill hydrographs from the Pleasant Valley and Lake (PV&L) Canal`directly to Spring Creek at the location where the canal crosses the creek. The spill hydrographs for the 2-, 10- and 100-year events at this ' location were modified pursuant to the revised hydrologic modeling for the Canal Importation Basin. ' COFC2005.06_&W domr rporLdoc - 9 ANdERSON CONSUITINC{ ENGINEERS, INC. A• •e di► Rainfall Performance Standard Evaluation Project: 1635 South Lemay Avenue STANDARD FORM A Project No.: TBS Calculations By: J. MILLER lDate: 05/15/07 DMW Civil Engineers, Inc. Developee Erodibility Area of Length of Slope of Avg Basin Avg Basin Perform. Subbasin Zone Subbasin Subbasin Length Slope Standard Asb Lsb Asb x Lsb Ssb Asb x Ssb Lb Sb PS acres (ft) /0 % (%) (ft) % 1 Moderate 0.18 85 15.30 1.00 0.18 2 Moderate 0.17 105 17.85 1.00 0.17 0:00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Total Moderate 0.35 33.15 0.35 94.71 1.00 70.66 TBS-EROS.xIs, FormA 4 1 of 1 J B B Effectiveness Calculations Project: 1635 South Lemay Avenue STANDARD FORM B Project No.: TBS Calculations By: J. MILLER Date: 05/15/07 DMW Civil Engineers, Inc. Treatment C-Factor P-Factor Comment Bare Soil Packed and smooth 1.00 1.00 Not used Freshly disked 1.00 0.90 Not used Rough irregular surface 1.00 0.90 lNot used Sediment Basin/Trap 1.00 0.50 Wattles at all inlets for sedimet traps Silt Fence Barrier 1.00 0.50 Surrounding areas of Construction Asphalt/Concrete Pavement 0.01 1.00 All existing and proposed paved areas Established Dry Land Native Grass 1.00 In undisturbed, undeveloped areas Sod Grass 0.01 1.00 In landscaped areas Temporary Vegetation/Cover Crops_ 0.45 1.00 Not used Hydraulic Mulch Q 2 Tons/Acre 0.10 1.00 Not used Erosion Control Mats/Blankets . 0.10 1.00 Not used Gravel Mulch 0.05 1.00 Not used Hay or Straw Dry Mulch 1 %-5% 0.06 1.00 Not used 60/6-10% 0.06 1.00 Not used 11 %-15% 0.07 1.00 Not used 16%-20% 0.11 1.00 Not used 21 %-25% 0.14 1.00 Not used 26%-33% 0.17 1.00 Not used >33% 0.20 1.00 Not used caFactors ano P-t-actors are taKen rrom i Me DO or ine Fort Collins Storm Drainage Design Criteria and Construction Standards 3 TBS-EROS.xIs, FormB Page 1 of 2 Effectiveness Calculations Project: 1635 South Lemay Avenue STANDARD FORM B Project No.: TBS Calculations By: J. MILLER Date: 05/15/07 DMW Civil Engineers, Inc. Major PS Subbasini Area Calculations Basin % Ac DURING CONSTRUCTION: Plan.Intent: Erect silt fence and wattles and construct sediment basin. C-Factor P-Factor Site 70.66 Total 0.35 Impervious Area: 0.20 Acres 0.01 Landscaping: b:15 Acres 0.01 Weighted C-Factor: (0.2x0.01)+(0.15x0.01)/0.35 = 0.01 Silt Fence: 0.50 Sediment Trap: 0.50 Weighted P-Factor (0.2x0.5)+(0.15x0.5)/0.35 = 0.50 Effectiveness EFF=(1-(CXP))X100 = (1-(0.01x0.5)x100 = 99.50 % Since 99.5% > 70.66%, the proposed plan is OK. TBS-EROS.xls, FormB Page 2 of 2 u Engineer's Estimate of Probable Cost for Erosion Control Escrow Security Project:_ 1635 South Lemay Avenue Project No.: TBS Calculations By: J. MILLER Date: 05/15/07 DMW Civil Engineers, Inc.. Itemized Costs: Item Unit Quantity Unit Cost" Total Silt Fence LF 245 $2.00 $490.00 Wattles LF 20 $4.00 $80.00 Sed Basin EA 1 $200.00 $200.00 Subtotal $770.00 ,Multiplier 1.5 Total $1,155.00 Formula Based: Unit Quantity Unit Cost Total Rev eta AC 0.35 $775.00 $271.25 Multiplier 1.5 Total ' $406.88 Escrow Security greater of two est., $1000 min.: $1,155.00 TBS-EROS.xIs, Cost Page 1 of 1