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Home My WebLink AboutDrainage Reports - 04/10/2002FinWD d Report 7. ate ioaz LARIMER COUNTY ADMINSTRATION BUILDING DRAINAGE & EROSION CONTROL STUDY BEY ON D E N G IN E E R ING ad ILE �In i 3 zoo? 1 i 1 1 1 1 1 i 1 1 1 1 1 1 i 1 i LARIMER COUNTY ADMINSTRATION BUILDING DRAINAGE & EROSION CONTROL STUDY for ................... ................... Lar- Imer;Cou�i, .................... 2555 Midpoint Drive, Suite D Fort Collins, Colorado 80525 0 Nolte Associates, Inc. 1901 Sharp Point Drive, Suite A Fort Collins, Colorado 80525 (970) 221-2400 October 291h, 2001 Revised: January 301h, 2002 Revised: March 27th, 2002 1 1 1 1 1 1 1 1 1 1 1 NC4TE BEYOND ENGINEERING March 27, 2002 Ms. Roxann Hayes Larimer County Engineering Department 212 West Mountain Avenue Fort Collins, CO 80521 RE: Drainage and Erosion Control Study for the Larimer County Administration Building Dear Roxann: We are please to submit to you, for your review and approval, this Drainage and Erosion Control Study for the Larimer County Administration Building. All computations within this report have been completed in compliance with the Larimer County Storm Drainage Criteria. We appreciated your time and consideration in reviewing this submittal. Please call if you have any questions. Sincerely, Nolte Associates, Inc. Prepared by: Herman Feissner, E.I.T. Associate Engineer cc: File FC0174 NOLTE ASSOCIATES, INC. 1901 SHARP POINT DRIVE. SUITE A FORT COLLINS, CO 80525 970.221.2400 TEL 970,221.2415 FAX WWW.NOLTE.COM Reviewed by: Patrick W. McNamara, P.E. Managing Director NO= Drainage & BEYOND ENDING ERING Erosion Control Study Larimer County Administration Building TABLE OF CONTENTS PAGE 1.0. INTRODUCTION........................................................................................................ I ' 1.1 Site Location..................................................................................................... 1.2 1 Existing Site Description................................................................................... 1 1.3 Proposed Project Description............................................................................ 1 2.0 METHODOLOGY.......................................................................................................2 2.1 Compliance with Standards............................................................................... 2 2.2 Analytical Methods........................................................................................... 2 3.0 HISTORIC DRAINAGE CONDITIONS..................................................................... 3 ' 4.0 3.1 Major Basin Description.................................................................................... DEVELOPED 3 DRAINAGE CONDITIONS................................................................. 4 4.1 General Concept............................................................................................... 4 ' 4.2 Basin Descriptions............................................................................................. 4 5.0 EROSION CONTROL................................................................................................. 7 5.1 General Concept............................................................................................... 7 5.2 Specific Detail................................................................................................... 7 ' 6.0 CONCLUSIONS..........................................................................................................8 6.1 Drainage Concept............................................................................................. 8 ' REFERENCES............................................................................................................. APPENDIX A Developed Site Hydrology 9 - • Developed Runoff Calculations ' APPENDIX B - Hydraulic Calculations • StormCAD Output • Inlet Design APPENDIX C - Charts, Tables & Graphs ' BACK POCKET - Drainage and Erosion Control Plan (Sheet C8) I i N:\Fc0174\Drainage\Word\Fc0174_DrainageReport.doc I 1 NOLTE Drainage & Erosion Control Study B E Y O N D E N G IN E E P ING Larimer County Administration Building ' 1.0 11 1 F 1 1.1 Site Location The proposed Larimer County Administration Building (Site) will be located near Old Town Fort Collins at 200 West Oak Street. The Site is bordered by Mountain Avenue on the North, Mason Street on the East, Oak Street to the South, and Howes Street to the West (See Vicinity Map, Exhibit 1). More particularly, the Site (3.67f acres) is located in Section 11, Township 7 North, Range 69 West of the 6`h Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 1.2 Existing Site Description In general, the northern portion of the Site slopes north and east along grades that are, on average, very flat. There are currently 3 buildings that occupy the Site. The two buildings to the south and west of site are multiple level brick buildings encompassing 34,239 ft2 (0.78 acres). In addition, there is a 24'x56' pre -manufactured building on the north side of the Site. The center of the Site consists mostly of asphalt parking and sidewalks. There is a pedestrian -way around the entire block with a 10' to 14' tree -lawn. There is no on -site detention. Storm water runoff from the Site sheet flows to the surrounding streets. The Site, in its existing state, is approximately 77% impervious. 1.3 Proposed Project Description The proposed Larimer County Administration Building will consist of one five - story, predominantly brick building. The proposed building is 34,418 ft2 (0.79 acre) and the parking area will have 112 parking spaces and 6 handicap spaces. The parking is located on the south and west sides of the building. The north one- third portion of the Site will be heavily landscaped with a meandering pedestrian walkway. A truck docking area has been designed for the east side of the building. Vehicle access for the Site will be from Howes Street and Oak Street. I N:\Fc0174\Drainage\WoWc0174_DrainageReport.doc 9:10 a.m. DATE: 10/29/01 PATH: N:\Fc0174\CADD\c Wil\ R FCSI SERVICE PROJECT DRAWNG NAME: FC0174_VCMAP.DWG LetlerP I ltdial uritiou r I 0 I LARIMER COUNTY ADMINISTRATION BUILDING SHEET NUMBER NOS VICINITY MAP 1 BEYOND EN0INEERING EXHIBIT 1. OF 1 SHEETS rMx � D ° FOREx C0. °D�6 PREPARED FOR: LARIMER COUNTY DATE SUBMITTED: 10/28/Ot JOB NuuBER ra vaatt4° rw: m;vDLTEca FC0174 ' Drainage & NOL�'E BEYOND ENO INGERINO Erosion Control Study Larimer County Administration Building 2.0 METHODOLOGY t2.1 Compliance with Standards The final drainage report that follows was prepared in accordance with the ' requirements and procedures for storm drainage design set forth in the City of Fort Collins Storm -Drainage Design Criteria and Construction Manual (i.e., FC- SDDCCM) and the Urban Storm Drainage Criteria Manual (i.e., Manuai . ' 2.2 Analytical Methods The Rational Method was used to analyze the respective design storm (i.e., 2-year ' and 100-year) runoff (Refer to Appendix A). This method is widely accepted for drainage design involving small drainage areas (<160 acres) and short times of concentration. It relates peak discharge to the runoff coefficient, rainfall intensity, and drainage area. The rainfall intensity and runoff coefficients were taken from the FC-SDDCCM. This method is ideal for storm sewer sizing and simple ' detention pond sizing or design situations where only the peak flow rate and/or the total volume of runoff are needed. ' In addition to the methods mentioned above, this preliminary drainage study was prepared using several software packages, including the following Haestad Methods software: StormCAD and FlowMaster; and Urban Storm Drainage Criteria Manual software: UD Inlet and Gutter Conveyance. I 2 N:\Fc0174\Drainage\Word\Fc0174_DmiiageReportdoc ' Drainage & NOL7-E BEYOND ENGINEERING Erosion Control Study Larimer County Administration Building ' 3.0 HISTORIC DRAINAGE BASINS i 3.1 Major Basin Description The existing Administration Building lies within the Old Town Master Drainage Basin. This basin is located in the central part of Fort Collins. Historically this basin has traveled through streets to the Poudre River during major events. There are currently small storm drain systems in place to capture nuisance flows and route them to the Poudre River. Resource Consultants & Engineers, Inc. prepared the Old Town Master Drainage Plan, in January 1993. This report outlines the floodplain associated with the Poudre River and Larimer #2 Canal. There is currently a Draft Report for the Old Town Master Drainage Plan Update (Partial Baseline Analyses) prepared by Anderson Consulting Engineers, Inc. that incorporates the current urban development in the area and delineates the associated flood plain. Referencing this report dated February 16, 2001; the Site does not lie within the flood plain. Exhibit 2 reflects the flood -plain boundary in relation to the Site. Exhibit 3 is the SWMM sub -basin and conveyance map for the area and shows the runoff routing. This information relates to Table 2.4. Rocky Mountain Consultants, Inc. (RMC) are in the process of designing the Oak Street Outfall; which is a large storm drain system that will route stormwater runoff from the Old Town Drainage Basin to the Poudre River. These improvements are referred to in this report as the Off -site improvements. Currently, a 48" outfall is designed for Mason Street. It will connect to the Oak Street Outfall at the intersection of Mason Street ad Oak Street. RMC is designing the inlets at the intersection of Mason Street and Mountain Avenue as well as Mason Street and Oak Street. 3 NAFc0174\Drainage\Word\Fc0174_DrainageReport.doc jhlk.'ii iiM6 2:04 p.m. DATE: 10/25/01 PATH: W\Fc0174\c.dd\civil\ SERVER: FCS1 SERVICE: PROJECT DRAWING NAME: FC0174_SWMMMAP.DWG EXCERPTED FROM: CITY OF FORT COLLINS OLD TOWN BASIN MASTERPLAN UPDATE, ANDERSON CONSULTING ENGINEERS, INC. (02/16/01) 'fit �"'9-°.i7! fr�4. 4 I�TI� - _ � i I ` :�j'r fit\ �J'J f tis•.�1� , t 466 µ5� ix3 o < }� = k a tiL� 1S ". 43 4®6 421 'K aw 11 fit +`P .:} 560 60 OAK ST .. r 1 d s1� `:A 4:s1iT; r� i ? 1, Jt s� t n- Ip7i 1 tI Fl ii is { �1;j NTS ••... -414 N®= LARIMER COUNTY ADMINISTRATION BUILDING 'M6L1 NUM6LH Old Town Basin Subbasin and Conveyance Map 1 BEYOND ENGINEERING EXHIBIT 3. OF 1 SHEETS W NGn POW CRNE SUITE A FWt ca1M m e4e4N6 JOB NUMBER FJdrnr�ra E Iff FAX MN TEnal PREPARED FOR: LARIMER COUNTY DATE SUBMITTED: 10/26/01 FC0174 DRAFT REPORT OLD TOWN BASIN MASTER DRAINAGE PLAN UPDATE (Partial Baseline Analyses) PREPARED FOR: City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80521 PREPARED BY. Anderson Consulting Engineers, Inc. 2900 South College Avenue, Suite 3B Fort Collins, CO 80525 (ACE Project No. COFC14) February 16, 2001 ANdERSON CONSU[TINq ENgiNEERS, INC Civil • 91ater Resources • Environmental ' Table 2.4 1 I Summary of Peak Discharges for Fully Developed Conditions with Existing Drainage Facilities in the Old Town Basin and Master Plan Drainage Facilities in the Canal Importation Basin. SWMM ID Location Peak Discharge (cfs) 2-Year I 5-Year I 10-Yeaz I 25-Year '50=Yeaz I 100=Ye CSU Model 230 Elizabeth Street at Shields Street 138 209 272 367 476 614 206 Laurel Street, West of Washington Street 13 21 28 40 55 77 209 Laurel Street, West of Loomis Street ] 0 17 22 29 36 47 392 College Avenue at Locust Street 35 44 51 81 105 130 Old Town North Model (With Howes Street Outfall) 733 Mulberry Street, West of Loomis Street 40 70 97 144 201 284 419 Mulberry Street, West ofMeldrum Street 47 74 98 138 185 250 413 Myrtle Street at Meldrum Street 41 65 85 123 172 250 450 Canyon Avenue, North of Olive Street 0 0 0 0 0 4 449 Magnolia Street, East of Canyon Avenue 1 33 123 300 518 826 690 Pond 605 Release to Mason Street, North of Olive Street 2 1 6 27 82 168 287 692 Pond 605 Release to College Ave, North of Magnolia St 22 41 104 .211 318 443 693 Pond 605 Release to College/Mulberry Pond (#604) 0 0 7 34 106 226 686 Pond 604 Release to College Ave, North of Magnolia St 1 1 2 3 5 11 685 Pond 604 Release to Magnolia/Remington Intersection 2 3 5 9 15 32 682 Pond 604 Release to Myrtle/Remington Intersection 42 73 102 169 249 374 638 Peterson Street at Locust Street 0 4 8 14 24 6 812 Plum Street at Whedbee Street 37 52 67 93 132 169 727 Myrtle Street at Riverside Avenue (street flow) 63 119 180 332 514 , 8 927 Myrtle Street at Riverside Avenue (storm sewer flow) 61 79" 95 106 110 111 724 Mulberry Street at Riverside Avenue 41 71 98 159 231 318 851 College Avenue, South of Olive Street 22 41 104 211 320 1 450 852 College Avenue, North of Olive Street 21 36 80 145 208 283 860 College Avenue, South of Oak Street 22 39 81 147 212 288 861 College Avenue, North of Oak Street 18 31 61 102 139 181 577 Mountain Avenue at Shields Street 79 123 163 246 354 515 435 Mountain Avenue at Loomis Street 11 37 75 151 245 380 442 Mountain Avenue, West of Howes Street 25 35 43 55 70 90 r - "445 Mountain Avenue at Mason Street 76 115 147 194 251 349 543 Mountain Avenue at College Avenue 90 141 182 247 347 537 962 Mountain Avenue at Mathews Street 121 188 245 336 455 694 422 Mountain Avenue at Peterson Street 68 132 187 277 405 644 460 Laporte Avenue, West of Shields Street 30 47 61 88 123 172 464 Laporte Avenue at Loomis Street 44 71 96 136 187 255 631 Laporte Avenue at Howes Street (street flow) 68 124 175 286 456 700 633 Laporte Avenue at Howes Street (storm sewer flow) 113 127 127 127 127 127 447 Maple Street, West of the Howes Street Outfall 7 10 12 16 21 30 458 Howes Street Outfall, North of Maple Street 64 119 173 288 458 705 459 Howes Street Outfall, North of Cherry Street 196 299 387 537 735 1038 508 Cherry Street at Wood Street 18 28 37 53 74 103 473 Cherry Street West of Whitcomb Street 33 50 67 100 140 195 474 Cherry Street at Meldrum Street 36 59 81 119 166 226 548 Cherry Street at the Howes Street Outfall 39 65 91 136 187 260 Old Town North Model (With Howes Street Outfall and Locust Street Outfall) 967 Mvrtle Street at Riverside Avenue 1 34 93 1 156 1* 298 503 798 935' ' T.\OPEN\Cofc l 4\cofc 14 tbl 24.wpd 2.18 ANd ERSON CONSUITING ENGINEERS, INC. ' Drainage & NODE Erosion Control Study B E Y O N D E N O I N E E R I N O Larimer County Administration Building 4.0 DEVELOPED DRAINAGE CONDITIONS 4.1 General Concept ' In general, the proposed Larimer County Administration Building will reduce the effective impervious area. The proposed Site will be 70% impervious. The current Site is 77% impervious. These estimates are based on an area -weighted ' average of the impervious area of the drainage basins that were delineated for this study. The developed runoff from the proposed Site improvements will sheet flow across ' parking areas to Type `R' curb inlets and a Type 16 inlet. Roof drainage will enter the same storm drain system that routes water from the inlets to the proposed Oak ' Street Outfall. Developed runoff from the landscaped area along the west side of the building will sheet flow to existing curb and gutter that leads to a series of inlets that are proposed as part of the off -site storm system and are being designed ' by RMC. ' The Site does not require on -site detention. Likewise, developed runoff will not be routed to an off -site detention facility; it will enter the proposed off -site storm 1 drain system (i.e., Oak Street Outfall) and ultimately discharge directly into the Poudre River. 4.2 Basin Descriptions ' Basins 100 through 103 contain areas adjacent to the Site and contain half street areas as well as landscaped and sidewalk areas. ' Developed runoff in Basin 100 (0.57 ac, Q1o0=5.26cfs) will flow overland through ' sidewalk and landscaped areas to curb and gutter to D.P. 100. D.P. 100 is situated at the basin's eastern end. 11 4 N:Wc0174\Drainage\Wm ffc0174_DmmageReportdoc I 1 CIS �_I LI 1 NO= Drainage & B E Y O N D E N G I N E E R I N G Erosion Control Study Larimer County Administration Building Basin 102 envelops the northern one-third of the Site from the north side of the building to the centerline of Mountain Avenue. The developed runoff in Basin 102 (1.49 ac, Qioo=11.69cfs) will sheet flow across the proposed landscaped area to existing curb and gutter that will route the runoff east to D.P. 102. Multiple combination inlets will be designed to intercept the runoff and discharge it to the off -site drainage system via a 30" RCP. The grated inlets are being designed by RMC as a part of the proposed Oak Street Outfall project. Basin 103 is located on the east side of the Site along Mason Street. The developed runoff in Basin 103 (0.71 ac, QIoo=6.37cfs) will traverse a landscaped area and the west half of Mason Street. The overland runoff will concentrate to vertical curb and gutter that routes it north to D.P. 103. From here, the runoff will be captured by a 10' Type `R' inlet designed by RMC as a part of the proposed Oak Street Outfall project. Developed runoff in basin 200 (0.59 ac, Qloo=5.86cfs) will flow overland through the south parking lot. Curb and gutter will route the storm water to the southeast corner of the basin, D.P. 200. A 5' Type `R' inlet will intercept and route the runoff to the on -site storm drain system. Developed runoff in basin 201 (0.63 ac, Q1oo=5.91cfs) will flow overland through the west parking lot. Curb and gutter that will route the runoff to the northwest corner of the basin; D.P. 201, will intercept the runoff. A 5' Type `R' inlet will capture the water and route it to the on -site storm drain system. Developed runoff in basin 202 (0.17 ac, Qloo=1.73cfs) will flow overland through the northernmost part of the west parking lot. Curb and gutter will intercept the runoff and route the flow west to D.P. 202. An on -grade 5' Type `R' inlet will 5 N:\Fc0174\Drainage\Word\Fco174_DrainageReporLdoc I 1 LJ 1 NO= Drainage & BEYOND ENGINEERING Erosion Control Study Larimer County Administration Building capture 84% of the developed runoff and route it to the on -site storm drain system. 0.3 cfs of carryover flow will spill to basin 101. Developed runoff in basin 203a (0.08 ac, Qloo=0.54cfs) will flow overland through the loading dock area, which is situated along the east side of the building. A 35 L.F. trench -drain will intercept and route the runoff west to D.P. 203a. The trench drain will empty directly into the outfall in Mason Street. Developed runoff in basin 203b (0.14 ac, Qloo=0.74cfs) will flow overland to D.P. 203b, which is situated along the east side of the building. A single Type 16 inlet is designed to intercept the developed runoff from basin 203b and empty directly into the 48" outfall in Mason Street (proposed by RMC). Per RUC, the hydraulic grade line (HGL) at the connection point to the outfall in Mason Street is at — 4982.00. Therefore, the proposed roof drain and perimeter drain connections, which tie directly in to the previously mentioned single Type 16 inlet at elevation 4982, will outfall freely into the this inlet without being encumbered by any tailwater. Developed runoff in basin 204 (0.26 ac, Qloo=2.27cfs) will travel overland through landscaped areas and the eastern part of the south parking lot. The runoff will continue in a southeasterly direction to D.P. 204. A 5' Type `R' curb inlet will capture 78% of the developed runoff and route it to the on -site storm drain system. 0.5 cfs of carryover flow will spill to basin 100. The roof area for the Administration Building is delineated as Basin 300 (0.80 ac, Ql00=7.93cfs). Rainfall will be captured by roof drains and rout through an internal storm drain system. This system releases the water into the on -site pipe system at SD-I3. 6 N:\Fc0174\Drainage\Word\Fco174_Drainag+eReport.doc ' Drainage & BEYOND ENGINEERING Erosion Control Study Larimer County Administration Building ' 5.0 EROSION CONTROL ' 5.1 General Concept The Larimer County Administration Building is in the Moderate Rainfall and ' Moderate Wind Erodibility zones per City of Fort Collins zone maps. Until the disturbed ground is vegetated, the potential exists for erosion problems during and after construction. In accordance with the City of Fort Collins Erosion Control Reference Manual for ' construction sites, the erosion control performance standard shall be 96.0% during construction and 99.0% after construction. 5.2 Specific Detail The Site is situated such that, during construction, disturbed areas drain overland ' and to the existing curb and gutter systems. Therefore, erosion control measures such as silt fencing and inlet protection will be necessary. These areas may or may not require regular maintenance depending on the conditions during the construction phase of development. ' Following completion of the overlot grading all areas that will not be paved shall be mulched and seeded. 1 7 L ' 7 N:\Fc0174\Drainage\Word\Fc0174_DrainageReporLdoc NOLTE Drainage & BEYOND ENGINEERING Erosion Control Study Larimer County Administration Building 6.0 CONCLUSIONS 6.1 Drainage Concept The proposed drainage concepts presented in this study and shown on the final drainage plans adequately provide for the conveyance of developed runoff from the proposed development. 8 N:\Fc0174\Drninage\Wmd\Fc0174_DmmageReport.doc NOLTE Drainage & B E Y O N D ENGINEERING Erosion Control Study Larimer County Administration Building REFERENCES 1. Storm Drainage Design Criteria and Constriction Standards (FC-SDDCCM), City of Fort Collins, Colorado (Revised January 1997). 2. Drainage Criteria Manual (Manual), Urban Drainage and Flood Control District, Wright - McLaughlin Engineers, Denver, Colorado, March 1969. 3. Old Town Basin Master Drainage Plan City of Fort Collins, Colorado, prepared by Resource Consultants & Engineers, Inc., January 1993. 4. Old Town Basin Master Drainage Plan Update, City of Fort Collins, Colorado, prepared by Anderson Consulting Engineers, Inc., February 2001. (Draft Report) 9 N:\Fc0174\Drainage\Word\Fc0174_DrainageReporLdoc i FOR W101►:I_1 Developed Site Hydrology I I I I 11 I I C 1, 1 1 Developed Runoff Calculations I I I I I 1] I I I No Text F 0 z C W W Z Z W 0 Z 0 } W f0 U Ca a '3 - z k' U N N ry N W T W t O G C �'�.ornrnvv V1 h M Z N N V1 m d a a � W : � � o oo�no Qm N N 00 dF ^ W `^coon T U V C O � u U,ng000 O O O O c U d F y a 0 0 0 0 u � 61 C I 11 I 1 L 1 iJ ul' a .. y 00 Cl M -• M CO _ -• r W lD 0 Iz. r O Yl O �O C C 00 r r �/1 r 00 l0 00 vl 00 l0 00 'a -0 .. N N N N N N N N N N N Q � � �yi N D\ r .-• r DD V 7 �O W �O U o 0 6 6 0 0 6 o c o 6 GTi Lr. z N O'o m r O pv, croo �v or or o U a A. ran wr—wkn rn U hr 0 0 0 6 o c o 0 0 0 0 .. m b r� qT vri � r vi O N oOo Q O O O _ _Tr y m N y Nl O O O O O O O p 0 O w. Q Q N N N N N N t�l �o 0 0 CN m a O N N N N N N C v 0 O O C 14 m O N N CN N N N O c O O V O c Oov o00 N N N N T 5 s cC r°i �v=o C V1 N R - O ^' z a a a o ono Q F F c C vo.-.fin nt n—O\ U Darnoo� N (+1 N O U 'r'0000 T U y O � vt Vl vl vi .0 U c� Ue�r r�or U ` N o o A m� =-Ssso � m 0 G z V r O CUi. [1 1 i 1 1 1 1 1 i 1 [I 1 1 1 1 LI 1 i c Im 0 U Ca ^/y v/ y 3 U O, ,O N Q\ 1� M W O\ r vl 1- N M D\ l-: W c c ooC 0,"00, N to Vl rno,o,rrnrn kn Vl M Vl Vl V1 rn rnao�o: a C� rnrn rn Q ^ N^ M �n O, V N N R ,O O\ v C\ v1 r�o .-. O r O M N O a0 U 00-:0 00000o c G4 °z c o o o v o o 0 o00v,00 0 0 0 0 0 0 O U a a U N M N O O Vl O O M 00 O U Lnrnrnoorn C rn r-� 00 0 0000 -=o 000 hM CN I I� 00 1 V0 7, b� O N 00 Q' u 0 0 0 'O 0 0 0 0 O O I ° 0 i •in M M .n M IT CD y M OIO 0 0 CDO O O O d A N N N� N N M •'�^O CD 0 N OO 0 i N N N S N N O •C O -- N M i O co .0O O 10 CD N O N p C11 N N i APPENDIX B Hydraulic Calculations I I 1 1 u I� I 1 I I 1 r 1 I I I I I I I I I StormCAD Output tr" §/ k §§§ -4| / / co ;{ 0 !0 6 ! 0.9 ) f |° c §). )` � E r N 0 LO §7/ (\\ r�6 1 k d y t+ � O m p, CD O C n1 Z N 1 1 1 c 0 n U m O in o rn m o N O) N CO m N O O (� m) -ItQ .-. W 0) O) 0) (0 m O rn rn rn rn m rn TC9 J vvvvev x -q cn 00 U U f07 N M m C 17 m m w O O 0) co CO co 0) 0 O) 0) O) 0 %C9 J V v v v v v v 2 0 0 0 0 0 0 C v N N N co 0 W [7 10 10 O N EWE rnrnrnrn0rnm > 0) O) W 0) 0) 0) m eeevev W O O O 000 _ C co N N coCO O) 09 10 10 0) )O C— v , O CO 2> ... m 0) 0) 00) C) 00) 02 v v v v v v N O 10 )O N E o N O'v N m 3 N co U) o to LO m N N N F i LL (n O O O O O c o 0 0 0 0 0002 o 0000 c O O 10 10 n (O m o o n c0 n rn E.9 LO Ln In to (o IDm c 0, E o LL m a m = J � CO N i0 O D 0 0 0 - (n (n y O) N m� C-o 0 y N � LL a) Im C m €�a > =o L m OFF c G •m o wN U m O a CD m m Lb 0 n m 0 N 4 Scenario: Base Pipe Report Label Upstream Downstream Length Constructed Section Mannings Full Total Average Upstream Downstream Upstream Downstream Hydraulic Hydraulic Energy Energy Description Node Node (ft) Slope Size n Capacity System Velocity Invert Invert Ground Ground Grade Grade Grade Grade (ft/ft) (cfs) Flow ON Elevation Elevation Elevation Elevation Line In Line Out Line In Line Out (cis) (ft) (ft) (ft) (ft) (ft) (ft) (ft) (ft) SD-P5 1-5 SD-13 112.56 0.0373 15 inch 0.013 12.48 8.02 6.74 4.991.430 4,987.230 4,994.94 4,991.52 4,992.55 4,990.29 4,993.29 4,990.95 SD-P4 SD-14 SD-13 43.22 0.0075 18 inch 0.013 9.07 1.71 0.96 4.987.552 4,987.230 4,991.36 4,991.52 4,990.30 4,990.29 4,990.31 4,990.30 SD-P3 SD-13 SD-12 341.26 0,0075 21 inch 0.013 13.72 15.20 6.32 4,987.130 4,984.570 4,991.52 4,991,52 4,990,29 4,987.14 4,99091 4,987.76 SD-P2 SD-12 SD-11 63.32 0.0075 21 inch 0.013 13.68 20.05 8.34 4,984.472 4,984.000 4:991:52 4,990.98 4,987.14 4,986.13 4,988:22 4,987.21 SD-P1 SD-11 I SD-MH1 95.83 0.0075 24 inch 0.013 19.61 25.45 8.37 4.983.750 4,983.030 4,990.98 4,988.51 4,986.13 4,984.80 4,987.15 4,985.96 1 Title: Larimer County Administration Building ' n:l..thaestad methodslstormgd\fc0174_stmc.stm 01129/02 11:02:59 AM Nolte Associates Inc m Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666' Project Engineer. Herman Feissner StormCAD v4.1.1 [4.2014] Page 1 of 1 I Inlet Design 1 1� 1 0 n I I I I I I Project=1,arimer County Admii Inlet ID ='Design"Point.200 (100 Building" ' " WP Lu WP <------- -Y(-- ->C---3► Yd HH Gutter gn Information (Input) gn Discharge on the Street (from Street Hy) th of a Unit Inlet Width for Depression Pan Sing Factor for a Single Unit it of Curb Opening in Inches :e Coefficient Coefficient �r Depth for the Design Condition a of Throat (see USDCM Chapter 6, Figure ST-5) )er of Curb Opening Inlets a Weir al Length of Curb Opening Inlet )acity as a Weir without Clogging gging Coefficient for Multiple Units gging Factor for Multiple Units >acity as a Weir with Clogging an Orifice )acity as an Orifice without Clogging )acity as an Orifice with Clogging Percentage for this Inlet = Qa / Qo = Ovate r Flaw Direction Qo = :5:9 cfs Lu= 5.00ft Wp=..". 3.00 ft Co =. ,.;-,--,,0.20 H '-,,'6..0.& inches Cd = i:' Cw =3.30 Theta = - ;," t;''63.0 degrees No L = 77, : S:OO: It Qwi = 18.8 cis Clog-Coeff = 100 Clog Qwa = -` :i;'17.0'icfs Qoi = h "117 ; "":'8:2: cfs Qoa=;:• 6.5-cfs Qa=:{b'_^afi 5; cfs Note: Unless additional ponding depth or spilling over the curb is acceptable, a capture percentage of less than 100% in a sump may indicate the need for additional inlet units. 4 FC0174_UDinlet_DP200.x1s, Curb-S 1/28/2002, 5:11 PM I ' Project=iarimer County Administration Building Street ID = _Basin.200 streetCrown Side Walk Ts ' V ' Qw Qx �J sx ; x D , i Dr SW <------------------------> <- W><--------- T"-------- > Gutter Street Design Discharge in the Gutter ' Curb Height Gutter Width Gutter Depression Street Transverse Slope Street Longitudinal Slope Manning's Roughness ' Gutter Conveyance Capacity :r Cross Slope :rSpread Width :r Depth without Gutter Depression :r Depth with a Gutter Depression ad for Side Flow on the Street ad for Gutter Flow along Gutter Slope rate Carried by Width Ts rate Carried by Width (Ts - W) :r Flow Flow Flow (Check against Qo) it Flow to Design Flow Ratio valent Slope for the Street Area Velocity product Qo =' ;'' 5.9 cfs H=-, 6.00 inches W=: - .2.00ft Ds ==,.• •.1.36 inches Sx = �,' 0:0267- fttft So =~ ~ 0.0100.ft/ft N=i .. 0.016'. Sw = z 008 fUft D=r-!!;' .16.4-11ft Tx=Y -;,7,2 .06�ft Ts = `' 4.90,ft Qws = .., 3.4, cis Qww 1.0icis Qw ';2.9;cfs Qx '. ' 3:0; cfs Qs =; - .5.4, cfs Eo Se = . 0.05 ft/ft As=�- 1`.75sgft Vs =. 3.36 fps VsD =+ 1.37 ftZ/s FC0174_UDinlet_DP200.xis, Street Hy 1/28/2002, 5:11 PM I ; aCURRFO ENING INLET'INaA SUMP- '£` Project =:.arimer:Counfy.Adn1Wstration.Building ' Inlet ID =.-Design Point 201 (100-year Storm.Event) ' WP Lu WP E--------><----->C---i Ovate r Yd f Flaw Direction H Pan ' Gutter ' Design Information (Input) Design Discharge on the Street (from Street Hy) Qo = 5.9 cfs Length of a Unit Inlet Lu = 5.00 ft Side Width for Depression Pan Wp = 3.00 ft Clogging Factor for a Single Unit Co =.. . ' .0.20. Height of Curb Opening in Inches H=7 6.00 inches Orifice Coefficient Cd =: "- 0.61 Weir Coefficient Cw =' . - :3:30 Water Depth for the Design Condition Yd = �. - •0.71 ft Angle of Throat (see USDCM Chapter 6, Figure ST-5) Theta = 63.0 degrees Number of Curb Opening Inlets No = _ T ' a Weir Total Length of Curb Opening Inlet L =; „ 5:00 ft Capacity as a Weir without Clogging Qwi = 20.5, cfs Clogging Coefficient for Multiple Units Clog-Coeff =; 1.00• ,- Clogging Factor for Multiple Units Clog = ;: 1 .: -0.20, Capacity as a Weir with Clogging Qwa =i... ; ,:18.6;cfs As an Orifice Capacity as an Orifice without Clogging Qoi =`:' 8.5 cfs ' Capacity as an Orifice with Clogging Qoa = i' 6:8 cfs Caoacltv for Design with Clogging Qa = FT. -, t 6 6; cfs ' Capture Percentage for this Inlet = Qa / Qo = C% _ ( :' 1,00:00; % ' Note: Unless additional ponding depth or spilling over the curb is acceptable, a capture percentage of less than 100% in a sump may indicate the need for additional inlet units. 0 FC0174_UDinlet_DP201.xis, Curb-S 1/28/2002, 5:16 PM I t ' Project = Larimer County Administration Building Street ID = Basin 201 1 H � V Side Walk Ts Y Qom' QX �~ Sx D W -�Sw Do v--- 00O-' <------------------------) <--W><---------Tx-------- ) Gunter Street Design Discharge in the Gutter ' Curb Height Gutter W idth Gutter Depression ' Street Transverse Slope Street Longitudinal Slope Manning's Roughness Gutter Conveyance Capacity Gutter Cross Slope Water Spread Width Water Depth without Gutter Depression Water Depth with a Gutter Depression Spread for Side Flow on the Street ' Spread for Gutter Flow along Gutter Slope Flowrate Carried by Width Ts Flowrate Carried by Width (Ts - W) Gutter Flow Side Flow ' Total Flow (Check against Qo) Gutter Flow to Design Flow Ratio Equivalent Slope for the Street ' Flow Area Flow Velocity ' sD product Street Crown Qo = 5.9, cfs H =. 6.00 inches W = 2.00 ft Ds = 1.40 inches Sx =' 0.0250 ft/ft So = 0.0080 ft/ft N =' 0.016 Sw=i t0.0&ft/ft Y =D:304ft Tx =' -10:11 ft Ts = 5.03 ft Qws = 3.7 cfs Qww = .` 1.0 cfs Qw=._ `• - -2.7 cfs Qx=.';;, ., 13.2+cfs Qs = - 5.9 cfs Eo =' 0.46 Se = 0.05 ft/ft As = 1.95 sq ft Vs = 3.04 fps VsD = 1.27 ftz/s FC0174_UDinlet_DP201.xls, Street Hy 1/28/2002, 5:16 PM Project: Inlet ID: Point CURB OPENING INLET ON A GRADE Administration Wp L wP �— rt- -' -'�_ _ _ ► Curb Gutter Flow Direction i Discharge on the Street (from Street Hy) Qo = 1.7 cfs Flow to Design Flow Ratio (from Street Hy) Eo = 0.78 of a Single Inlet Unit Lu = 5.00 ft ig Factor for a Single Unit Inlet Co = 0.20 it of Inlet Units in Curb Opening No = 2 Length of Curb Opening Inlet L = 10.00 ft alent Slope Se (from Street Hy) Se = 0.0700 fUft red Length Lo to Have 100% Interception Lo = 13.77 It ing Coefficient C-coeff = 1.25 ing Factor for Multiple -unit Curb Opening Inlet Clog = 0.13 ive (Undogged) Length Le = 8.75 ft r No -Clogging Condition ive Length of Curb Opening Inlet (must be < Lo) L = 10.00 ft eption Capacity all = 1.6 cfs r Clogging Condition ive Length of Curb Opening Inlet (must be < Lo) Le = 8.75 ft eption Capacity Qa="' 1.4 cfs over Flow = Qo - Qa = Qco =' 0.3 cfs ire Percentage for this Inlet = Qa / Qo = C%= 83.74 % FC0174_UDinlet_DP202.xis, Curb-G 1128/2002, 5:51 PM I [G Project = Larimer Courity;Admiriistration Building- Street ID = Basin.202 ' street Side Walk Ts Y Q, ' Qx Sx H Do sw Y- T - - <----------T"--------> Gutter Street Street Geomet finput) Design Discharge in the Gutter CIO = 1:7 cfs ' Curb Height H = - 6.00 inches Gutter Width W = : 2.00 ft Gutter Depression Ds = 1.62 inches ' Street Transverse Slope Sx =' 0.0158 ft/ft Street Longitudinal Slope So = 1 ;�,',, 0.0200 ft/ft Manning's Roughness N = r ''r . -0:016 Gutter Conveyance Capacity Gutter Cross Slope Sw = -,, �.0.08; ft/ft Spread Width T ; �s ' A ft 'Water Water Depth without Gutter Depression Y i 0 11 ft Water Depth with a Gutter Depression D='t:.'.:: ~ 0:25ift Spread for Side Flow on the Street Tx == 5:11 it Spread for Gutter Flow along Gutter Slope Ts =: : -. 2.97. ft Flowrate Carried by Width Ts Qws = '''..' -.`1.4 cis Flowrate Carried by Width (Ts - W) Qww =? ., 0:V cis ' Gutter Flow Qw 1.4i cfs Side Flow Qx = i .:,' 0.4 cfs 'Total Flow (Check against Qo) Qs = 1:7 cfs Gutter Flow to Design Flow Ratio Eo =' 0.78 ' Equivalent Slope for the Street Se =`• ` , O.07. ft/ft Flow Area As = 0.53• sq it Flow Velocity Vs ='. ,. . 3.24 fps ' sD product VsD =; : ' 0.80 ft2/s 11 FC0174_UDinlet DP202.xis, Street Hy 1 /28/2002, 5:49 PM 11 SLOTTED INLET IN A SUMP 11 Project = Larinner County Administration Inlet ID = Design Point 203a 000-vear St( gn Discharge on the Street (from Street Hy) Qo = 0.5 cfs th of a Unit Slotted Inlet Lu = 35.00 ft i for Slotted Inlet W = 1.00 ft Sing Factor for a Single Unit Co = 0.50 it of Curb in Inches H = 0.00 inches :e Coefficient Cd = 0.65 Coefficient Cw = 3.00 r Depth for the Design Condition Yd = 0.15 ft Der of Curb Opening Inlets No = 1 a Weir at Length of Slotted Inlet L = 35.00 It 3acity as a Weir without Clogging Owl = 6.4 cfs gging Coefficient for Multiple Units Clog-Coeff = 1.00 gging Factor for Multiple Units Clog = 0.50 )acity as a Weir with Clogging Qwa = 3.4 cfs an Orifice )acity as an Orifice without Clogging Cot = 70.7 cfs )acity as an Orifice with Clogging Qoa = 35.4 cfs 3acity for Design with Clogging Qa = 3.4 cfs 3ture Percentage for this Inlet = Qa / Qo = C% = 100.00 % Note: Unless additional ponding depth or spilling over the curb is acceptable, a capture percentage of less than 100% in a sump may indicate the need for additional inlet units. FC0174_UDinlet_DP203a.xls, Slot-S 1/29/2002, 9:59 AM ri r r C Project = Inlet ID = COMBINATION"INLETJN .i A:SUMPiOR ".ON iA=GRADE `Le�imer'County Administration'Buildina Wp L WP F-------�--^-�it--lam Curb 1 ^ H 7tfel, Flow Direction CONCEPT In a combination inlet, consider the grate inlet and the curb opening as functioning independently. DESIGN STEPS: Case 1. Combination Inlet on a Grade: A. Grate Inlet Hvdraulics On a Grade: 1. Apply the design flow on the street. 2. Determine the interception of the grate inlet. 3. Calculate the initial carry-over flow after the grate inlet. B. Curb Opening Inlet Hvdraulics On a Grade: 4. Apply the carry-over flow on the street. 5. Determine the interception of the curb opening inlet. 6. Calculate the final carry-over flow after the curb opening inlet. Case 2. Combination Inlet in a Sump: 1. Apply the sump depth to the grate inlet. 2. Apply the sump depth to the curb opening inlet. 3. Calculate the total interception and determine whether additional inlets are required. C Project=.Larimer Street ID = Basin 21 inty Administration Building street Side Walk Ts Crown y Qx SSr H' D W - Dr ^�ST <--w><--------- T"-------- > Gutter Street to Discharge in the Gutter Height r Width r Depression tTransverse Slope t Longitudinal Slope ing's Roughness er Cross Slope :rSpread Width :r Depth without Gutter Depression it Depth with a Gutter Depression ad for Side Flow on the Street ad for Gutter Flow along Gutter Slope -ate Carried by Width Ts -ate Carried by Width (Ts - W) :r Flow Flow Flow (Check against Qo) :r Flow to Design Flow Ratio talent Slope for the Street Area Velocity product Qo =` 0.7 cfs H = `6.00 inches W = 2.00 ft Ds = 1.33 inches Sx = 0.0280 ft/ft So = . 0.0060 ft/ft N =; ;0.016 Sw= z5'r'`'0.08:ftfft T ._4.48ift Y = i `'` `="%0:13 ft Tx == . ' 2.48 It Ts = . 2.83 It Qws =' , 0.7, cfs Qww = , . "0.0 cfs Qx=, ='. -0.1,cfs Qs =' ,_ .0:7: cfs Eo = :0.89: Se = '. 10.08 ft/ft As =?: 0.39 sq ft Vs = -1.89 fps VsD = 0.45-ft2/s FC0174—UDinlet_DP203b.xls, Street Hy 1/29/2002, 8:15 AM [1 Ci ' Project = Inlet ID = n "Larimer County Administration'Building Desiqn Point 2031b 000-year Design Storm) W= Wo Lo LeCleWd Lo L Curb Gutter F— Flow >ign Discharge on the Street (from Street Hy) Qo = 0:7 cfs igth of a Unit Grate Lo = 3.27 ft ith of a Unit Grate Wo = 2.00 ft a Opening Ratio for a Grate Ar = 0.33 gging Coefficient for a Single Inlet Co = •- - - 0.50 nber of Grates No = 1 ice Coefficient Cd =, = 0.65 it Coefficient Cw =... . -3.00, ter Depth for Design Condition Yd = "t 0.24 ft 3acity of Grate Inlet in a Sumo (Calculated) igth of Grate Inlet L =k: `-327ift ith of Grate Inlet W =.,>r ` '`':'200`ft a Weir )acity as a Weir without Clogging Qwi = i , ._2:6 cfs gging Coefficient for Multiple Units C-coef = gging Factor for Multiple Units Clog =' • 0.50 )acity as a Weir with Clogging Qwa =` 2.0 cfs an Orifice >acity as an Orifice without Clogging Qoi = : -,; 5:5! cis )acity as an Orifice with Clogging Qoa =.'., 2.8'cfs )acity for Design with Clogging Qa F ,; ;.` w2A. cfs Aure percentage = Qa / Qo C% = E' •=;<a';,_ 100. 01 % Note: Unless additional ponding depth or spilling over the curb is acceptable, a capture percentage of less than 100% in a sump may indicate the need for additional inlet units. FC0174_UDinlet_DP203b.xls, Grate-S 1/29/2002, 9:25 AM I C L 1 Project = Larimer Cou Inlet ID = Design Poin iGURB'�OPENING-IINLET IN° -A!SU.MP. Administration Building 3b (100-year Design Storm) WP Lu wP C--------><-----><---t• wate r Yd Pan Gutter gn Information (Input) gn Discharge on the Street (from Street Hy) th of a Unit Inlet Width for Depression Pan Sing Factor for a Single Unit it of Curb Opening in Inches :e Coefficient Coefficient it Depth for the Design Condition of Throat (see USDCM Chapter 6, Figure ST-5) ber of Curb Opening Inlets a Weir al Length of Curb Opening Inlet )acity as a Weir without Clogging gging Coefficient for Multiple Units gging Factor for Multiple Units )acity as a Weir with Clogging an Orifice )acity as an Orifice without Clogging )acity as an Orifice with Clogging Percentage for this Inlet = Qa / Qo = Flaw Direction Qo = _0.7 cfs Lu = 3.27 ft W p = 2.00 ft Co =; 0.20 H =1 6.00 inches Cd =; . `;: 0:61 Cw== 3:30 Yd =i '0.24 ft Theta 63.0 degrees No = :1 L =' + 3.27 ft Qwi = i- .1. 2:7 cfs Clog-Coeff =; 1.00 Clog =r ." '0:20 Qwa = .'' .; . 2.4 cfs Qoa = I 0.8 cis Qa = ' , �;�n� 6:8jcfs Note: Unless additional ponding depth or spilling over the curb is acceptable, a capture percentage of less than 100% in a sump may indicate the need for additional inlet units. FC0174_UDinlet_DP203b.xls, Curb-S 1/29/2002, 9:25 AM P.O. Box 29708, Lincoln, Nebraska 68529 1 1 1 1 1 1 Deeter Foundry, Inc. 2502 Curb Inlet - Frame, Grate, Curb & Partial Frame Heavy Duty Total Wt. — 875# Open Area — 336 Sq. In. 1. Abutting side flanges may be omitted to create multiple units. 2502-L Heavy Duty Total Wt. — 850# Open Area — 310 Sq. In. 1. Same as 2502 except with L-style grate. i aQa 'NNaelN I 15 251 a=Smll 1 Catch Basin Inlet Grates & Frames Heavy Duty Total Open Wt. Area 2510 — 195# — 189 Sq. In. - r 2511 — 210# — 189 Sq. In. 1. Grate openings are measured from flat side of Gra 2. Grates are reversible. 2'/.' Illustrating 2511 Inlet Grate and Frame Illustrating 2510 Inlet Grate and Frame ' :.QUMDPENING INLET ON sA'GRADE;: Project: Larimer County Administration Building InletlD:.Design Point 204 (100-year Storm Event) WP L WP <--- -----�--at---� Curti ii A-0�- Flow Direction Gutter i Discharge on the Street (from Street Hy) Qo = 2.3 cfs Flow to Design Flow Ratio (from Street Hy) Eo = 0.76 of a Single Inlet Unit Lu = 5.00 ft ig Factor for a Single Unit Inlet Co = 0.20 :r of Inlet Units in Curb Opening No =. 2 Total Length of Curb Opening Inlet L = ,' -10.00 ft _. Equivalent Slope Se (from Street Hy) Se=;`.;'0.0700,Wit Required Length Lo to Have 100% Interception Lo =: < < 15.43,ft Clogging Coefficient C-coeff=iZ Clogging Factor for Multiple -unit Curb Opening Inlet Clog = `'.' . •. 0:13, Effective (Unclogged) Length Le = "' '13J5, ft Under No -Clogging Condition Effective Length of Curb Opening Inlet (must be < Lo) L =, <A.10A0'ft Interception Capacity Qi = • 1.9 cfs Under Clogging Condition Effective Length of Curb Opening Inlet (must be < Lo) Le =; ,: 8.75: ft Interception Capacity Qa = elti, cfs Carryover flow = Qo - Qa = Qco = ` �Yi�,:0:5_ cfs Capture Percentage for this Inlet = Qa / Qo = C % = 4�e 77c83{ % FC0174_UDin1et_DP204.x1s, Curb-G 1/28/2002, 6:10 PM I 1 ' Project = Larimer County Administration -Building Street ID = Basin.204 1 1 1 Side Walk Ts A /�--- V QW i DW �------ V W Y--- SW r <------ - ---------> <--w><--------- Tx -------- > Gutter Street Design Discharge in the Gutter ' Curb Height Gutter Width Gutter Depression 1 Street Transverse Slope Street Longitudinal Slope Manning's Roughness ' Gutter Conveyance Capacity Gutter Cross Slope Water Spread Width Water Depth without Gutter Depression ater Depth with a Gutter Depression Spread for Side Flow on the Street Spread for Gutter Flow along Gutter Slope Flowrate Carried by Width Ts Flowrate Carried by Width (Ts - W) Gutter Flow Side Flow tTotal Flow (Check against Qo) Gutter Flow to Design Flow Ratio ' Equivalent Slope for the Street Flow Area Flow Velocity sD product H Street Crown I Qo = _ .2.3 cfs H = 6.00 inches W 2.00 ft Ds = '1':45 inches Sx = r0.0230 ft/ft So 0.0200 Wit N =r,s' 0.016 Sw= T—,! `"`,ft/ft Y=t. 0:15ft Tx = i. ". 466 ft Ts = ' "t . 3.28 ft Qws 11.9. cis Qww = = 0.2 cfs Qw = (.'^:' ' .1.7 cis Qx=E"`';; `'0.6 cfs Qs =: '-2.3 cfs Se = 0.07 ft/ft As = 0.63 sq It Vs = '160 fps VsD =. .: 0.99 ftz/s ' FC0174_UDinlet_DP204.xls, Street Hy 1/2812002, 6:10 PM h �J I I I I I I I I I APPENDIX C Charts, Tables & Graphs I No Text 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 DRAINAGE CRITERIA MANUAL 5( 3C 1— 2 C z tL U Cr W a 10 z to a O 5 tL ¢ 3 m O U 2 Lu t— Q t� 1 RUNOFF ��nnn��n�■�►�rn�r nr,��iin nnn1111//II�I�/111// FAN .• I�� Ind■�� Il I' inn 0 1 inn 11010FA FJ I. lmmo■■■■� ►�mmm.■II ■��I mm■■■■- _gym 5 l •0 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR USE WITH THE RATIONAL FORMULA. *MOST FREQUENTLY OCCURRING"UNDEVELOPED" LAND SURFACES IN THE DENVER REGION. REFERENCE: "Urban HydrologJ For Small watersheds" Technical Release No. 55. USDA, SCS Jan. 1975. 5 -1-84 URBAN DRAINAGE & FLOOD CONTROL DISTRICT 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................................................................................................. 0.50 Roofs.......................................................................................................... 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 Average2 to 7%.................................................................................. 0.25 Steep>7%.......................................................................................... 0.35 MAY 1984 3-4 DESIGN CRITERIA 0 Table 5-4 ' INLET CAPACITY REDUCTION FACTORS Percentage of ' Drainage Condition Sump or Continuous Grade ........................................... Inlet Type Theoretical Capacity CDOH Type R-Curb Opening 5' 80% 10, 85% ' 15' 90% Street — Sump.............................................................. 4' Curb Opening 80% ' Street —Continuous Grade .......................................... 4' Curb Opening 80% Parking Lots, Medians ................................................... Area Inlet 80% ' - The theoretical capacity of inlets in a low point or sump shall be determined from Figures 5-2 and 5-3. The theoretical capacity of curb openings on a continuous grade shall be determined from Figures 5-4, 5-5 and 5-6. ' The standard curb -opening is illustrated by Figure 5-4 and is defined as having a gutter depression apron W feet wide at the inlet opening which extends W feet upstream and downstream from the open- ing, has a depression depth (a) equal to W/12 feet at the curb face, and a curb opening height (h) of at least 0.5 feet. The graph as presented by Figure 5-5 is based on a depression apron width (W) equal to 2 feet and depression width (a) equal to 2 inches. The pavement cross-section is straight to the curb IMAY 1994 M" DESIGN CRITERIA