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HomeMy WebLinkAboutDrainage Reports - 05/05/1987Drainage Report for the Oakridge Village P.U.D., Filings 3, 4 and 5 April 1987 1 1 1� 1 1 1 ■rYiNC Engineering Consultants 2900 South College Avenue Fort Collins, Colorado 80525 3031226-4955 April 26, 1987 Mr. Bob Smith Storm Drainage Department City of Fort Collins P.O. Box 580 Fort Collins, Colorado 80522 RE: DRAINAGE REPORT FOR OAKRIDGE VILLAGE P.U.D., FILINGS 3, 4 AND 5 Dear Bob: We are pleased to submit this drainage report as the final drainage report for Oakridge Village P.U.D., Filings 3, 4 and 5. Please call if you have any questions. Sincerely, \\\`\\\�\111llllllllll//// "o p0 NECIs RBD, Inc. :�\\�QP'�1 A°d1y°•�F��': C.4 Co 18060 Stan A. Myers, P.E. _A ac_ �pS ; L 4 Project Manager �°� ��FSS/a!�',��` \ A` Brian H. Cole Project Engineer Other Offices: Vail, Colorado 303/476-6340 • Colorado Springs, Colorado 303/574.3504 DRAINAGE REPORT FOR OAKRIDGE VILLAGE P.U.D., FILINGS 3, 4 AND 5 April 26, 1987 PREPARED FOR: EVERITT COMPANIES 3000 SOUTH COLLEGE AVENUE FORT COLLINS, COLORADO 80525 PREPARED BY: RBD, INC. ENGINEERING CONSULTANTS 2900 SOUTH COLLEGE AVENUE FORT COLLINS, COLORADO 80525 1 1 1 1 INDEX INTRODUCTION PAGE LOCATION 1 EXISTING DESCRIPTION 1 DESIGN PROCEDURE 1 DESIGN APPROACH 1 - 3 CONCLUSIONS AND RECOMMENDATIONS 4 REFERENCES .4 APPENDIX 2 YEAR DEVELOPED CALCULATIONS Al-A7 10 YEAR DEVELOPED CALCULATIONS A8 100 YEAR DEVELOPED CALCULATIONS A10 STREET CAPACITY CALCULATIONS All-Al2 PIPE OPENING/ORIFICE A13 KEY MAP A14 PIPE NOMOGRAPHS A15-A16 10 YEAR DEVELOPED CALCULATIONS TO SIZE INLETS IN LEMAY AVE. A17 2 YEAR DEVELOPED BASIN 11 A18 100 YEAR DEVELOPED BASIN 11 A19 I� ' INTRODUCTION ' LOCATION Oakridge Village Filings 3,4 and 5 are located in the Oakridge Village P.U.D. just North of Oakridge Village Filing 1, across ' Keenland Drive. These proposed filings are also bordered by Lemay Avenue to the West, Rule Drive to the North and Wheaton Drive to the East. More specifically these filings are located in the West half of section 6, Township 6 North, Range 68 West of the 6th Principal Meridian. ' EXISTING DESCRIPTION Currently this property consists of an open grassed field sur- rounded by the streets mentioned above. The site slopes to the Southeast at about 2% on the North to 0.5% on the South. A graded earthen channel cuts across Fourth Filing of Oakridge Vil- lage in the southern portion of the site. This storm drainage channel flows from the existing pipe inverts under Lemay Avenue to the pipe inverts at the intersection of Wheaton and Keenland Drives. The channel has a slope of + 0.4%. ' DESIGN PROCEDURE All of the design flows were calculated using the rational ' method. See City of Fort Collins Storm Drainage Design Criteria and Construction Standards. Because this is a residential area, the minor storm is considered a 2 year storm and the major storm is considered a 100 year storm, according to City of Fort Collins ' criteria. The calculations for these design storms are in the Appendix. DESIGN APPRQACH In the first step of the design approach, a two year developed storm was calculated and modeled, for each basin (see calcula- tions in Appendix). This was done to determine if any flows would overtop curb and gutter. Between design point 1 and design point 4, flows will begin to sheet flow across the street before the West gutter capacity is reached, therefore the curb and gut- ter capacities will not be exceeded (see Grading and Drainage Plan, also calculations in Appendix). Stormwater will flow to existing and proposed inlets at the intersection of Keenland Drive and Wheaton Drive. ' The drainage report for the Second Filing of Oakridge Village proposed a second drainage channel to extend along the north side of Keenland Drive from its intersection with Wheaton Drive to the ' regional pond north of Oakridge Second Filing. Flows going into this North channel will be from three areas. The first is com- prised of the proposed Oakridge Village Filings 3,4 and 5; the second is a small area north of this site which is currently undeveloped and; the third and last area is north of Keenland 11 I 1] Drive and East of Wheaton Drive which is also undeveloped. When all these flows are considered the 1 0 vaar design discharge was calculated to be 25` 0 cfs, see Appendix. This figure compares to 198.4 cfs shown on the drainage plan from the drainage report from the Oakridge Village P.U.D., Second Filing. The increase is due to the fact that the northern portion of this site was to have its own detention area (see KEY MAP from Second Filing Report page A14) Site constraints have dictated the elimination of this detention area. In lieu of the previous approach flows from the northern portion of the site will flow undetained in the proposed channel to the large regional pond north of the Second Filing. The pond volume required was calculated to increase from 12.87 ac-ft to 14.85 ac-ft to accommodate the increased flows. The pond, however, will be enlarged to 21.22 acre-feet to account for additional storage required by Future developments to the north. One reason the proposed channel north of Keenland is being created is to lessen culvert crossings of Keenland Drive as ex- plained in the Oakridge 2nd Filing Report. Because of this the existing pipes and inlets must be modified (see Plan). The ex- isting inlets 1 and 2 will be plugged at the existing pipes. New pipes will then be placed at the inverts to drain into the new channel. The proposed channel has been designed to accept these 100 year flows. Any future street crossing over the new channel should be designed with storm drain piping which can handle the 10 year developed flows. A conservative design figure 150 cfs was used for design to allow for blockage and future filings (see Appendix for pipe opening/orifice design). The Oakridge Second Filing Drainage Report indicates 125 cfs off dfsite flows entering the South Keenland channel. This flow en- ters the Oakridge area from under Lemay Avenue through 3-36" RCP's. The flows continue through a channel (see Section B-B on plan in pocket) until it enters an existing storm drain under the intersection of Wheaton Drive and Keenland Drive. The flows exit the storm drain into the South Keenland channel at the Southeast corner of this intersection. The Oakridge Second Filing Drainage Report did not anticipate additional flows from Basins D-7 and D- 6 which were not a part of the 125 cfs. These 100 year flows are 24.9 cfs as calculated in Appendix. This additional flow will not, however, bring the South Keenland channel over capacity, as shown in the following calculations. Existing South Keenland channel Q = 277.2 cfs plus 33% for freeboard = 368.68 cfs plus the additional 24.9 cfs = 393.58 cfs. The capacity of the channel is 440 cfs, based on Section A -A on the drainage plan and Mannings equation, therefore the channel can handle the additional flows. Nomographs (in Appendix) show that the pipes designed for Oakridge 2 are also able to handle the flows. i 2 I ' Inlets in Lemay Avenue over the three previously mentioned 36" RCP's were not size during the design of Lemay Avenue. Inlet sizing is therefore included in this report with support calcula- tions in Appendix. Flows from Basin D-11 (Calculations in Appendix) flow around a curb return and into Keenland Drive. These flows will eventually drain into an existing inlet at the Southeast corner of the in- tersection of Wheaton Drive and Keenland Drive. The flows, which were part of the offsite flows through the 3-36" RCP's under Lemay, will not adversly affect drainage in Keenland Drive and will eventually flow into the South Keenland Drive channel. Flows in Lemay Avenue, North of Rule Drive, have been included in Basin 8. Flows from this basin enter an existing inlet at the Northwest corner of Rule Drive and Wheaton Drive. I 11 J 1 F Cl 1 I i J I I I I 1 CONCLUSIONS AND RECOMMENDATION 1. Two inlets were sized in Wheaton Drive and shown on plans to be a 5' and 2-10' type "R" inlets. This would keep the curb and gutters under capacity. The 5 foot inlet should be con nected to the existing inlet by a 24" RCP. The pipes from 2-10' inlets will intersect an existing 29"x45" storm sewer pipe at a proposed manhole. Flows from both these pipes will then continue east thru the new 5' inlet and thAVn into the channel. 2. Three existing pipes are plugged, as shown on plans, to enable the flows to be redirected in pipes to a new channel on the north side of Keenland Drive. The pipes from exist- ing inlets 1 and 2 will be 18" RCP and 36" RCP respectively layed at 0.5% minimum until daylighted. 3. A new channel will be created downstream from this site and north of Keenland Drive using the cross-section shown on plan. This channel will extend from the intersection of Keenland Drive and Wheaton Drive to the pipes under Keenland Drive from Oakridge Filing #2. 4. Pipes sized for any crossing of the above channel should be 2-36" RCP's and 1-30" RCP or equivalent for 150 cfs. 5. The pond designed in Oakridge Filing #2 should be sized from 12.87 ac-ft. to 21.22 ac-ft. 6. Two inlets were sized, in Lemay Avenue to be 1-10' type "R" sump (East) and 1-15' type "R" sump (West). The east inlet is to be constructed with these filings. The west inlet will be constructed in the future. The three existing 36" RCP's, have a total width of 18'+. For ease of construc- tion the 10' inlet should be sized to 20' to encompass all three pipes. When final design is implemented, this drainage plan will satisfy hydraulic and hydrologic considerations as well as current City of Fort Collins Regulations in providing storm water management. REFERENCES 1. Storm Drainage Design Criteria and Construction Standards, by the City of Fort Collins, May 1984. 2. Final Drainage Report for Oakridge Village P.0 D Filing No. 2, by RBD, Inc. Engineering Consultants. 3. McClellands Basin Master Plan, by Greenhorn and Omara, Inc., June 20, 1986. N I i 1 1 1 1 1 1 1 L 1 1 1 1 1 APPENDIX 1 i 1 1 1 1 1 1 i 1 1 1 i 1 1 1 1 1 i 1 0 W a 0 W cc Q V IIIIII IN Mill 111 lillI 1111111111111IIIIII MAY 1984 5-3 Q 0 z c� w 0 Q z oo to rn J , W Vi av W cm I.- W N L W rn z ¢ L 0 im OE o O LL LL J Q U a Al DESIGN CRITERIA No Text �, 1 1��11 11111111111 �I� i IIIIIII IIIII IIIII ; MAY 1984 5-3 H 0 z c� cc w 0 Z of to rn J W vi Q a4) aD w0) H c W �t d w (m ZJ Q ¢t o c� 0 E V)e It LL 0 LL L Q 0 J Q U a A3 DESIGN CRITERIA No Text 0 a O W W ►B cl Cl cn cr 96 IIIIIIIIIIIIIIIIIIII;; AIM I III ON 11111111111 MAY 1984 5.3 Q O z 0 1n w O �y IY Q_ cZ p) C a) J a(U v w� ~w v) � Or w rn Zu o L O m Q� 0 1n 2 0 LL Q 0 J Q U a r A5 DESIGN CRITERIA No Text 1 1 1 1 1 V-1 �T 1 min min IIIIIIIIII BMINo6 B B 6 MAY 1984 5.3 ¢ 0 z 0 w O a¢ z �cn J ^ (Y N (L v g _c H m �w c n N 'L w On cnl ZJ Q L L) m Q OE o Q LL 0 LL i (L O LL J U a I A7 DESIGN CRITERIA 1 i 1 1 1 1 1 1 1 i 1 1 1 1 1 1 1 i 1"11 1'11„1 11 1 MAY 1984 5-3 a 0 z a In w } Q a Z t, �a) Q a� a) M.c- W c w in c � Nt (7 Z�a, a L O p� cc 0 E In o It U LL 2 a U Q. A8 DESIGN CRITERIA No Text No Text DATE: 2-24-87 ' PROJECT: oakridge JOB NUMBER: 035-021 DESIGN ENGINEER: be ' BASIN DESIGNATION = d-1-2-3 DETERMINE EXISTING 0 FOR 2 YEAR STORM HISTORIC RUNOFF COEFFICIENT .2 BASIN SLOPE: 1.5 PERCENT ' BASIN LENGTH 1000 FEET AREA: 12.03 ACRES ' HIST TC = 1.87*(1.1-( 1 * ,2 ))*SORROOT 1000 ))/ 1.5 ^ 1/3 = 46.49923 MINUTES ' HISTORIC OUTFLOW IS SUPERCEDED BY: 2.41 CUBIC FEET PER SECOND DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS ' DEVELOPED STORM: 100 YEAR STORM DEVELOPED RUNOFF COEFFICIENT .65 * CCFAC = .65 1.25 * 12.03 = 9.774375 DURATION GROSS VOL. OUTFLOW VOL. DETENTION VOL. ' MIN CU. FT. CU. FT. CU. FT 5 26742.69 723 26019.69 10 41169.67 1446 39723.67 15 52429.75 2169 50260.75 30 72486.77 4338 68148.77 45 87089.68 6507 80582.68 ' 60 90 91840.02 99229.46 8676 13014 83164.02 86215.46 120 101340.7 17352 83988.72 180 109785.8 26028 83757.78 ' 360 122453.4 52056 70397.37 REQUIRED DETENTION VOLUME IS 86215.46 CU. FT. OR 1.979235 ACRE FEET 'ISTORICAL COEF? .2 BASIN SIN LENGTH,FT.? 1000 BASIN SLOPE,%? 1.5 ISIN AREA,AC.? 12.03 STORIC TIME OF CONCENTRATION 46.49923 DO YOU WANT TO SPECIFY ALTERNATE OUTFALL RATE,Y/N7 Y \ Al Q �LTERNATE OUTFALL, C.F.S.? 2.41 ) I [1 RMINC Engineering Consultants ' C I J ! o° u .x 1 q9 Ai [1 1 I CLIENT _�VE� �T'T JOBNO.O3S- OZ I PROJECT ©l� % Vrc CALCULATIONS FOR y'L- T--' . 4=� ACC T `tI CHECKED BY DATE SHEET OF MADEBY IL DATE b W �l J 1 L✓ I 1 CLIENT EN/ v JOB NO. O3�7 ' O Z. \ INC PROJECT(f CALCULATIONSFOR p 7 Engineering Consultants MADE BY U •C. DAT CHECKED BY DATE SHEET OF r7c> I CD, CD I � -70.03> CSC I t \ I S = 2 "io ( = 5 Z�. kR ��, 1 1 1 11 I] 0 [1 1 I NC Engineering Consultants CLIENT �cV E e-\ T JOB NO. PROJECT 42P`V- li'-\ K>( Z CALCULATIONS FOR U P k V=, e .e. MADE BY OATE/Z`� S1 CHECKED BY DATE $MEET OF Q '^r V J q ` I :3 I -70. 6370 -c� A13 KEY MAP u F u F, THE LANDINGS PUD FUTURE NEIGHBORHOOD CENTER GOLDEN MEADOWS PUD HARMONY ROAD + MLTREAR 3 J ESIDENTIA �_. \.FOX RIDGE AN4ex SOUTHRIDG9 GREENS PUD -WEENLAND—ANN'GXAT, N _3 -KNOB HILL E LIZ ABE C ATHOL lr;UR CATHOLIC` RESIDENTIAL I I O / K RIDGE _, r _,.ElflIrT COW 0 D�rT COW ARE A 0 C Soo u A14 INLET CONTROL AT KEENLAND DRIVE s�z 70 4 cEs CHART 2 180 10,000 (�� (2) (3) 168 8,000 EXAMPLE 6. ' 156 6,000 0.42 inches (3.5 feel) 0.120 ell 6 . 5 144 5,000 4,000 tLw' Mw 6. 5. ' 132 3,000 0 felt (1) 2.5 8.8 54. ' 4. 120 (2) 2.1 7.4 - 2,000 13) 2.2 1.7 4• 3' 108 3. - •0 in feet 96 1,000 3. —800 84 - 600 // 2• 2- - 500 / ' 72 - 400 3 2. _ 300 1.5 1.5 ' Z 60 in a 200 0 j / N Cr w 1.5 l' z z FfGkE P w 01, 54 t ur �i 1.Z`7 C 100 lA = a C) c(s PIPE �--_� so 4/4 z - sly' (,.f•�:. /2 _ b0 u - L NV 2'REPv 2r 0- 1.0 1.0 w ' w in 50 HW ENTR p S' ALE o -1.0 - 40 TYPE w 9 36 30 (1) square edge with a 9 3 ' w 33 heodwall _ •9 Q _ 20 12) Groove end with w 8 — 30 heodwoll x .8 - (3) Groove end .8 ' 27 projecting 10 8 .T .r ' 2 q — 6 To use scale (2) or (3) project .7 21 5 horizontally to scale (1), then — 4 use straight Inclined line through D and 0 scales, or reverse as 6 3 Illustrated. 6 .6 18 NOTE 2 (� CfS 90 --It0= [.5 15 — LA. ciale..s~pL.5 .5 ' 1.0 12 HEADWATER DEPTH ,FOR . CONCRETE PIPE CULVERTS t HEADWATER SCALES 283 REVISED MAY 1964 WITH INLET CONTROL - BUREAU Of PUBLIC ROAOB :AN. 11183 5-22 A15 INLET CONTROL AT McMURRAY DRIVE ISO 168 156 144 132 120 108 96 • 84 N 72 W V 2 = 60 LDS 3- q Dl A 54 w 46 v �42 W 0 0: W H 36 W 7 d - 33 • O - 30 27 24 21 18 UE CHART 2 10,000 . ��� ('Z) (3) 8,000 EXAMPLE 6. 6,000 D•42 Inches (3.5 rest) 5,000 a•120cis 5. 4,000 cur Is Nw 6' 3,000 D tool n) x.s 8.0 4 5 (2) x.l T.♦ 2,000 (3) 2.2 3. — oD In toot 3. 1,000 Boo — 600 500 400 3 2. 300LL LL U 200 oA-ev (0 F Z bG2+ W �-- 80 FRoc—� oraKRtOt�E Z = Q . a o 5O HW ENTRANCE lit- 0 1.0 _40 U SCALE TYPE w 30 (1) Square edge with F 3 hoodwall .9 20 (2) Groove end with W Madwall S (3) Groove end .8 projecting 5. 4. 3. 2- 1.5 I- 1.5 1.0 9 ' k.9 .6 k .8 10 7 6 T' _ .T 6 To use stole (2) or (3) project 5 horizontally to stale 4 oil straight Inclined line through D and 0 soalso,or rover as as ,6 3 Illustrated. 6 .6 2 44��7c.-��= Zr7Sc�S .s .s 1.0 5 L 12 HEADWATER DEPTH ,FOR HEADWATER SCALES 293 CONCRETE PIPE CULVERTS REVISED MAY 1964 WITH INLET CONTROL 'BUREAU OF PUBLIC ROADS JAN. 1963 • 5-22 A16 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ��IIIIIIIIIIIIIIIIIillllllllll 11111 � 011111111111111111111111111111111111 wi cr 01 I�IIIIIIIIIIIIIII�IIIIIIIIIIIIIIIIII MAY 1984 5-3 0 z 0 1n w 0 } Z cy, �(D a) J , ¢ a� d � c W cn w c LO Ur U 0) Q J Z� ¢ L 0 Ol ¢ > UE u)2 ¢ LL U LL 2 0 J Q U a A17 DESIGN CRITERIA No Text No Text