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Home My WebLink AboutDrainage Reports - 12/06/1991lima '�u.(J. I�tL Q1_G�D(�O NG /-rrl/1it1ila?� V'e-1"ftMMww7- F�ai Drainage and Erosion Control Report for ��o N {c'f✓i' LOUDEN CREEK DRIVING RANGE AND GOLF CENTER k2a��2 J l�sfJ; J (Tinian P.U.D. Fort Collins, Colorado INITIAL SUBMITTAL, date: _ 12/0 2 /91 �+• Prepared for KNICKERS, NC. Fort Collins, Colorado M Project No: 1230-02-91 Date: December 2, 1991 4836 S. College, Suite 12 Fort Collins, CO 80525 (303)226-5334 i is E A9RI //,4/& /Pe4,61646 A A47 ............. ---------------- -------- 74.47 —,kV 4F y -7 eo Ai ............ i .,c,7Rl 16 vx4 v e". _,OF._... j4o?17C A/ Ig "r zc.- ........ ... 7-4:-� kV I ----------- ------ 77-0 AV45.77 71n7IA/C W jo. j: 4� > ACP7 ....... ... .......... 4L 4/WIL .... . ....... ...... 77. .15 AZ.4 We" —15c. O/vf—.,o 6 -�5. eCl o4,41 47 P"C=// x 77 l :51 _V1 5__,4.ey4E/ it /Vp ................ W e4 ------ - --- oc oz FAF /72L_ --- 41,el r,7 4 6_72 4,e.��F V 7 Oe.7 7.5. _'d_ _. __. 17#4 AC A ?4.- -It . _72 A7_770. &I _75� z_5,_4W_Ae_7_-x1 AIA-7--eel— ------------ ,a APPENDIX A Storm Drainage Calculations Figures . ........... ko ... .. . ... ...... - -------------- ".0O3 A 0.61).71---C770 x 0-061) - ---- --------- ---- --- ---- --- Cq,4 — - - -------- .. .. .... .............. .. ... --------- - - --- ------- REFERENCES 1. City of Fort Collins Storm Drainage Criteria Manual 2. City of Fort Collins Storm Erosion Control Manual 3. City of Fort Collins topographic Aerial for the SE 1/4 of Section 11, T6N, R69W 4. Preliminary Master Drainage Report for the Timan P.U.D. by RBD, Inc., dated April 4, 1988 3.1.6 Runoff ;fficients The runoff coefficients to be used with the Rational Method referred to in Section 3.2 "Analysis Methodology" can be determined based on either zoning classifications or the 1 types of surfaces on the drainage area. Table 3-2 lists the runoff coefficients for the various types of zoning along with the zoning definitions. Table 3-3 lists coefficients for the different kinds of surfaces. Since the Land Development Guidance System for Fort Collins allows land development to occur which may vary the zoning requirements and produce runoff coeffi- cients different from those specified in Table 3-2, the runoff coefficients should not be based solely on the zoning classifications. The Composite Runoff Coefficient shall be calculated using the following formula: C = (ZC,A,)/At ,e, Where C =Composite Runoff Coefficient C, = Runoff Coefficient for specific area A, A, =Area of surface with runoff coefficient of C, n = Number of different surfaces to be considered A,=Total area over which C is applicable; the sum of all A; s is equal to A, Table 3-2 RATIONAL METHOD RUNOFF COEFFICIENTS FOR ZONING CLASSIFICATIONS Description of Area or Zoning Coefficient Business: BP, BL........................................................................................ 0.85 1" ; Business: BG, HB, C.................................................................. ............ 0.95 Industrial: IL, IP.......................................................................................... 0.85 Industrial: IG..................................... .. 0.95 ........................................................ Residential: RE, RLP................................................................................. 0.45 Residential: RL, ML, RP............................................................................. 0 1 Residential: FILM, RMP.............................................................................. 0 ` Residential: RM, MM.................................................................................. 0.65 Residential: RH.......................................................................................... 0.70 Parks, Cemeteries...................................................................................... 0.25 Playgrounds............................................................................................... 0.35 fyT%J RailroadYard Areas................................................................................... 0.40 Unimproved Areas...................................................................................... 0.20 /V; Zoning Definitions R-E Estate Residential District — a low density residential area primarily in outlying areas with a minimum lot area of 9,000 square feet. R-L Low Density Residential District — low density residential areas located throughout iL the City with a minimum lot area of 6,000 square feet. R-M Medium Density Residential District — both low and medium density residential areas with a minimum lot area of 6,000 square feet for one -family or two-family dwellings and 9,000 square feet for a multiple family dwelling. R-H High Density Residential District— high density residential areas with a minimum lot area of 6,000 square feet for one -family or two-family dwellings, 9,000 square feet for a multiple family dwelling, and 12.000 square feet for other specified uses. R-P Planned Residential District —designation of areas planned as a unit (PUD) to pro- vide a variation in use and building placements with.a minimum lot area of 6,000 square feet. R-L-P Low Density Planned Residential District —areas planned as a unit (PUD) to permit variations in use, density and building placements, with a minumum lot area of 6,000 square feet. MAY 1984 3-3 DESIGN CRITERIA R-M-P Medium Density Planned Residential District — desigi.adon for medium density areas planned as a unit (PUD) to provide a variation in use and building placements with a minimum lot area of 6,000 square feet. R-L-M Low Density Multiple Family District —areas containing low density multiple family units or any other use in the R-L District with a minimum lot area of 6,000 square feet for one -family or two-family dwellings and•9,000 square feet for multiple -family dwellings. M-L Low Density Mobile Home District — designation for areas for mobile home parks containing independent mobile homes not exceeding 6 units per acre. M-M Medium Density Mobile Home District — designation for areas of mobile home parks containing independent mobile homes not exceeding 12 units per acre. B-G General Business District — district designation for downtown business areas, including a variety of permitted uses, with minimum lot areas equal to 1 /2 of the total floor area of the building. B-P Planned Business District — designates areas planned as unit developments to provide business services while protecting the surrounding residential areas with minumum lot areas the same as R-M. H-B Highway Business District — designates an area of automobile -orientated busi- nesses with a minimum lot area equal to 1/2 of the total floor area of the building. B-L Limited Business District — designates areas for neighborhood convenience centers, including a variety of community uses with minimum lot areas equal to two times the total floor area of the building. C Commercial District —designates areas of commercial, service and storage areas. I-L Limited Industrial District — designates areas of light industrial uses with a minimum area of lot equal to two times the total floor area of the building not to be less than 20,000 square feet. I-P Industrial Park District —designates light industrial park areas containing controlled industrial uses with minimum lot areas equal to two times the total floor area of the building not to be less than 20,000 square feet. I-G General Industrial District— designates areas of major industrial development. T Transition District — designates areas which are in a transitional stage with regard to ultimate development. For current and more explicit definitions of land uses and zoning classifications, refer to the Code of the City of Fort Collins, Chapters 99 and 118. Table 3-3 RATIONAL METHOD RUNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS Character of Surface Runoff Coefficient Streets, Parking Lots, Drives: t?� Asphalt................................................................................................ 0.95 Concrete........................................................................................... 0.50 Gravel............................................................................................ Roofs.........................................................................................................: 0.95 Lawns, Sandy Soil: ` Ilj Flat<2%............................................................................................ 0.10 I a �I ; r . Average 2 to 7% ............................... 0.15 o ;. 5 y. Steep>7%......................................................................................:... 0.20 u Lawns, Heavy Soil: Flat <2%............................................................................................. 0.20 0.2 Average2 to 7% ......................................................................... 0.35 Steep>7% ......... :............................................................................. ... MAY 1984 3-4 DESIGN CRITERIA No Text 47 M -OR-T/ NC Engineering Consultants 2900 South College Avenue Fort Collins, Colorado 80525 303/226-4955 April 4, 1988 Susan Hayes City of Fort Collins Storm Drainage Department P.O. Box 580 Fort Collins, Colorado 80522 RE: TIMAN P.U.D. MASTER DRAINAGE REPORT Dear Susan: Site Location On behalf of Jeff Timan, RBD Inca submits the following Prelimi- nary Master Drainage Report for the Timan P.U.D. The Timan P.U.D. site is located along the west side of State Highway 287 (South College Avenue) north of Trilby Road. The 56 acre parcel is bounded on the north by Skyway Drive, on the east by State Highway 287 on the south by Trilby Road and on thewest by the First Freewill Baptist Church, Skyway Acres Subdivision and the Foothills Gateway facility. More precisely this location can be described as being situated in the east half of the southeast quarter of Section ll, 'Township 6 North, Range 69 West of the 6th P.M. in Larimer County, Colorado. Existing Drainage The site currently contains a commercial parcel in its southeast corner and one residence. The vast majority of the site is used ..for pasture. The site is traversed by a small irrigation lateral which enters the site in the southwest corner, and exits the site in the northwest corner. The lateral meanders along a ridgeline through the site. . The site slopes generally eastward at slopes of 1.5% to 8% below the ridgeline and approximately 2.57. above the ridgeline. Two op ridges protrude eastward from the prin- cipal ridge. Theseboar ridges have the effect of dividing the lower area into three basins. Each of these basins have- low areas which are formed by the state highway embankment. These areas are drained by culverts which run under State Highway 287 Other Offices: Vail, Colorado 303/476.6340 • Colorado Springs, Colorado 3031574.3504 and the commercial areas on the other side of the highway. The two northern basins appear to have limited wetlands in their low lying areas. Offsite Drainage Offsite drainage flows have a definite impact on this site. Of- fsite flows will impact the site along the west property line. No offsite flows are anticipated from any other region. The first and most southern offsite area contributing flows along the west property line is largely undeveloped area occupied by a single church building with an unimproved parking area (see Of- fsite Exhibit A in Appendix). Flows from this 7.6 acre area are currently diverted into the forementioned irrigation lateral. This lateral appears to have adequate capacity to handle 100 year flows from this area, without substantially impacting the Timan P.U.D. The second offsite area is comprised of portions of the Skyway Acres residential area and the Good Samaritan Center. Drainage flows are collected in the street system in this area and flow undetained into a concrete lined swale that runs northward just west of the west property line of the Timan P.U.D. This swale appears to be greatly undersized for 10 year as well as 100 year flows. Therefore the majority of these flow will enter -the —site undetained along the described swale. The third offsite area is comprised principally of the Foothills Gateway facility. Drainage from this area flows eastward until it is intercepted by a grass swale which is a continuation of the concrete swale mentioned in Offsite Area 2. This grass.swale has greater capacity due to a more substantial berm along its eastern sideslope. This swale carries flows northward to the storage pond which lies just west of the northwest corner of the Timan P.U.D. At this point flows either enter the storage pond or fol- low the Foothills Gateway entrance road and flow into Skyway Drive. As a result of these conditions no offsite flows are an- ticipated from this area. Proposed Drainage The attached Master Drainage and Utility Plan illustrates the ap- proach taken in facilitating drainage onsite. Onsite drainage will be handled rather simply utilizing the two. northern low areas for the required site detention. This will be done in or- der to reduce or eliminate grading in the wetland areas. An ad- ditional improvement will be the piping of the irrigation lateral from a point close to where the lateral crosses the west property line to the north property line. This will simplify site grading and access to the area above the lateral. Basin A comprises roughly the northern third of the site. Drainage flows in this area will be conveyed through a system of curb and gutter, culverts, swales and storm drain piping to the forementioned low area. This area provides the required deten- tion with a minimal amount of grading. Most of this grading will be above the wetlands thus reducing its impact. The culvert opening will be redesigned to restrict outfall to the required rate. No offsite flows will enter this basin. Basin B comprising the remainder of the site will be handled in much the same manner. Drainage flows will be conveyed in a similar system to the low area at the midpoint of the highway frontage. Again grading will be limited in the low area to areas above the wetlands. The principal difference from Basin A, will be that facilities carrying flows from the area adjacent to Of- fsite Area 2 will be oversized to accommodate the undetained of- fsite flows. Conclusion Calculations which substantiate the proposed approach appear in the attached Appendix. All calculation reflect use of the City of Fort Collins Storm Drainage Criteria. Detailed calculations for the sizing of culverts and the design of outlet works will be submitted with the Final Master Drainage Report. The approach outlined in this report should provide for the efficient and safe conveyance of drainage through the site. Sincerely, RBD, Inc. Stan A. Myers, P.E. cc: 272-001 APPEND 2X Q MA ATPA GO D. -A R I R /# cr- OFFSITE DRAINAGE EXHIBIT A y -.40, D VISION j F f -0 5 FF OTHILLS E 'i /,,GATE��", Xz 47 r 7. Z, 41 o' f QFff FSIT XRE V,_ C CRET DRAIN P N GRASS,SWAL ti \1 1 99 KB - ZEEE�� -Z::7- . SCALE: 1'=200' 0 40 4 J) if ::.J Q10" 6.4 cfs/ 07. 22.3.cfs Q = 36.85 dfs 10 Q 100 55.5 Cfs RWINC znm;nm,r*;nn rnncidfgntos j v I DATE: 3/23/99 PROJECT: TIMAN JOB NUMBER: 272-001 DESIGN ENGINEER: SAM BASIN DESIGNATION = Al DETERMINE EXISTING Q FOR 2 YEAR STORM HISTORIC RUNOFF COEFFICIENT BASIN SLOPE: 4.2 BASIN LENGTH 1200 AREA: 20.09 ACRES HIST TC = 1.87*(1.1-( 1 ))*SQRROOT 1200 1/3 = HISTORIC RAINFALL INTENSITY: HISTORIC OUTFALL: 7.055368 .25 PERCENT FEET 34.14359 C .2J .4.2 MINUTES 1.404752 1INCHES/HOUR CUBIC FEET PER SECOND DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS DEVELOPED STORM: 100 DEVELOPED RUNOFF COEFFICIENT CCFAC = 20.09 .85 DURATION MIN 5 10 15 30 45 60 90 120 180 .360 * 21.34563 GROSS VOL. CU. FT. 54966.24 84619.08 107762.6 148987.4 179001.9 188765.6 203953.7 208293.1 225650.9 2516B7.5 YEAR STORM .85 1.25 OUTFLOW VOL. CU. FT. 2116.61 4233.221 6349.831 12699.66 19049.49 25399.32 38098.99 50798.65 76197.97 152395.9 DETENTION VOL. CU. FT 52849. 64 80385.86 101412.9 136287.8 159952.4 163366.3 165854.7 157494.5 149452.9 99291.58 REQUIRED DETENTION VOLUME IS 165854.7 CU. FT. OR .3.8075 ACRE FEET CLIENT INC / _—-�JOBNO.�L PROJECT—T/AiIANSCALCULATIONMR t Engineering Consultants MADEBY.j P-DATE.��pyL +- CNECKEDSY-DATE SHEET_OF ync i t•� . . 554 1818 ; r8r9 ` ° CIO Ac: Fr i O7JSb3 ! n538;z A C� `J8.0 0500 I i S/C100 .743ea 1.75Ac Per SDa�.o 335pp I Vez/rWAA. G WAUI/OG (A*44 OF BA5/N•,4� i ! .i S 41 so i I? 1 632 j 2.79 i 48813 406788 s' 3.»2,va.Fr, • i EVENTUAL QeAO/A1Ce . I 5r f'.t S4 SE CCnr;N� i i Soo I I is DATE: 3/28/88 PROJECT: TIMAN JOB NUMBER: 272.001 DESIGN ENGINEER: SAM BASIN DESIGNATION DETERMINE EXISTING 0 FOR 2 YEAR STORM aaaaaaaaaeanaaaeaaaaaaaaaaa¢a¢¢�=s¢aaaaaaaaa=aaaa¢aa¢aaaaaaaaaaan¢aaa HISTORIC RUNOFF COEFFICIENT .25 BASIN SLOPE: 2.4 PERCENT BASIN LENGTH 1850 FEET AREA: 39.3 ACRES HIST TC ■ 1.87•(1.1•( 1 • .25 ))"SQRROOT 1850 ))/ 2.4 1/3 = 51.07826 . MINUTES HISTORIC RAINFALL INTENSITY: 1.126278 INCHES/HOUR HISTORIC OUTFALL: 11.06569 CUBIC FEET PER SECOND DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS aaasaaasaaaaaa¢saaasaaaanaasa¢asaaanaaaaaanas¢aaaanaaea=assaaasaxa DEVELOPED STORM: 100 YEAR STORM DEVELOPED RUNOFF COEFFICIENT .85 CCFAC ■ .85 * 1.25 * 39.3 = 41.75625 DURATION GROSS VOL. OUTFLOW VOL. DETENTION VOL. MIN CU. FT. CU..FT. CU. FT 5 107524.8 3319.706 104205.1 10 165531.6 6639.411 158892.2 15 210805.2 9959.116 20D846.1 30 291448.8 19918.23 271530.6 45 350163 29877.35 320285.7 60 369262.8 39836.47 329426.3 90 398973.6 59754.7 339218.9 120 407462.4 79672.93 327789.5 180 441417.6 119509.4 321908.2 360 492350.4 239018.8 253331.6 REQUIRED DETENTION VOLUME IS 339218.9 CU. FT. OR 7.787395 ACRE FEET RMINC CLIENT ?'1M. L :1� -. JOB NO. ,?7. C� 1 _—_ PROJECT M A L.T!,-:F CALCULATIONS FOR Engineering Consultants MAOEBT tL DATE ��_� CHECKED BY_,_DATE SHEET -OF JAN 6PAWA)C.. ELF V 493b.z o - �f870 �1780 p,5 Ac. PT Soo 0 24300 36080. ; 2.25 .;ao�. - 132000 23008C) - /8s� � 4/5080 9,53 • 401 G CAC1N(a :. .......: ..... ...-........ .. E.42V AZCj)6 VOL 1/OL 49°i8.2 0 ' - a i E'00 cZ I'MO 0.5 AC- F7- rood - ��300 l08080 �.Sp - /S1000 2(�0080 SI 7 acoc 88000 . CLIENT JOB NO..22.� �NC PROJECT ��/if lt!/_• CALCULATIONS FOR _aELL Tf ��t�Y.�•�� Engineering Consultants MADE BY- DATE -CHECKED By- DATE SHEET_OF AeEA = 7 (.4Ae. C= O. 2d�s))ASO 35.3 Ce u • a Tc,� = 37.uw 37 c efel� _ (il:zslo.20(sso) (7,�4) = -7,3 ef:, Q,o Aet-A= ;zo.o S. RWW Engineering Consultants CLIENT PROJECT MADEBY _ DATE CHECKED BY JOB NO. CALCULATIONSFOR DATE SHEET __OF ■�/YINC Engineering Consultants CLIENT PROJECT MADE BY_ DATE JOB NO. CALCULATIONS CHECKED BY -DATE SHEET_OF 1 . _.... :..... ._ _ ..... _ .__.. /2 r4a: i ..II' i I - . ' I) CLIENT NO. ■AINC Engineering Consultants PR04ECT MADE BY _ DATE CHECKED BY CALCULATIONS FOR DATE -SHEET -OF ►Anr�t'Tt!//ov .AREA A83 0.25 /.74 A/Uc3(7AP16-0 - c�/.95....._.p.a5 —_ as.�� -- . 7.��j _ .0.304 . .. � 4 87 ► - 0. 3046'-�S1) = /oo _ 1.13S . (47.43) i /� Qioo ' , _ i /, 2s (0.3�).� �.Si3 �,77>:= 4g(4.4) .<O9.�...10.ctrN..'.�c"—a:`- _ _..... .�..........!.. Q = C'P(2, ,4 10 FOCT'•.c/iLLS CATEr�A`/. %�/�=�..:•'►LE__�''C. __..... --- - , : + \al C�.4 /P.?13. ' e.o5 .. _ . .... 1 ;�o.....:..174/146� !/ 11 /AK)046 Q/0O i FO CL . .i