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HomeMy WebLinkAboutDrainage Reports - 08/06/1992No Text FINAL DRAINAGE & EROSION CONTROL REPORT FOR BEST BUY P.U.D. MAY 28, 1992 (REVISED JULY 29, 1992) PREPARED FOR BEST BUY, INC. P.O. BOX 9312 MINNEAPOLIS, MINNESOTA 55440-9312 PREPARED BY PARSONS & ASSOCIATES CONSULTING ENGINEERS 432 LINK LANE PLAZA FORT COLLINS, COLORADO 80524 (303) 221-2400 PROJECT NUMBER: 92.10 BUY TABLE OF CONTENTS Introduction Site Description Historic Drainage Master Drainage Drainage Criteria Drainage Under Developed Conditions Erosion Control Conclusions and Recommendations Basin Summary Calculations Figure 1 Vicinity Map Figure 2 Outlet Improvements Figure 3 Drainage Schematic 1 1 3 4 6 6 8 10 11 12-21 5 7 11 FINAL DRAINAGE & EROSION CONTROL REPORT FOR BEST BUY P.U.D. FORT COLLINS, COLORADO Introduction This drainage report has been prepared along with final engineering drawings to provide design information for the development of a Best Buy retail store along the east side of South College Avenue between the Fountain P.U.D. Phase 3 and the Market Place P.U.D. This report was prepared in conformance with the City of Fort Collins "Storm Drainage Design Criteria and Construction Standards". Site Description The proposed Best Buy P.U.D. is located in the west one-half of Section 36, Township 7 North, Range 69 West of- the 6`h Principal Meridian, City of Fort Collins, Larimer County, Colorado (see figure 1). The northern portion of the site is also part of Lot 18 of the Observatory Heights Subdivision. The property is a 2.845 acre site which sits between the Fountainhead and Market Place commercial centers. Currently the parcel contains one single -1- 1 1, 1 1. i 1 1 1 1 1 1 1 1 1 1 1 w v w 0 s FIGURE i I 0 1 L H 1 1 family residence with some smaller farm buildings and is screened from the commercial centers and South College Avenue by mature trees and other landscaping. This project will include the construction of a 28,520 square foot retail building with 137 parking spaces. South College Avenue forms the western boundary and Fountainhead P.U.D. Phase 3 forms the northern boundary. A water line and access will tie to this project from the north. The adjacent parcel to the east is currently vacant, but is zoned HB and is planned for a commercial building. The southern boundary of this project is adjacent to the Market Place P.U.D. (Phar Mor Site). Water, sewer, storm drainage and roadway improvements were installed as part of the Market Place P.U.D. to provide service to this site. Historic Drainage Construction of the adjacent commercial developments has affected the drainage from this site. Prior to the construction of these centers, water ran from northwest to southeast towards the Larimer #2 Canal. The majority of the drainage from the north was eliminated when the Fountainhead Project was constructed. Fountainhead sits approximately two (2) feet higher and diverts water away from this site. A natural ridge along the eastern boundary -3- 1 keeps water from the undeveloped eastern property away from this site. South College ' Avenue drains from north to south in this area and flows are kept in the curb where they are eventually diverted to the Market Place detention ponds by two curb openings. Detailed topography was completed by field survey which verifies the direction of off -site flows. Refer ' to the Final Grading Plan for additional detailed information. ' The Market Place drainage system provides detention for the Market Place G 1 1 0 Development and an outfall line to the Larimer #2 Canal. As part of the Market Place development, an outfall line was extended into the Best Buy P.U.D. property to drain the low area that was created. Sheet 15 of 16 of the Final Drainage Report for the Market Place (dated 1-2-90) shows that the outflow pipes were sized to convey this historic flow. Runoff on the Best Buy P.U.D. parcel currently runs from the edges of the site to an inlet where it is conveyed to the Larimer #2 Canal. Sheet 4 of 8 of the Market Place construction plans shows these improvements (see Figure 2). Master Drainage The property is located within the Heart Special Improvement District. Runoff from areas within this district is limited to 0.87 cfs per acre of developed area before being -4- ' TO �I=UTU2E UI=VEL.OPM�t..IT-C�2ADE ' �IZAIN TO CATCH SdSIN Itil--_2..a3.CES f _.__G2dDE_�,CLI�SS.2.D. -Q ' S1 DE DIT 'DIES 'TO. ARV --A, \NLET A•ZA ' i To C=ATni-I '-CC7P OF CaRA�E/ 31.00 �-� \NV. 27.Zo l iZU�_L�>ZAln1AU>=_SMT. ' BASIN � -- 1-- i \ 32 STD. VERT G.4 C, (TYP) 31.25 +3l .8. i 20 co o^ ?N OUTFALL C4Cq(TYP) JN � v � / 20 --- J 90� G 1 � 20 20 31 ARE \NLET A•Z �9 7o F N- OGP,C c E 2�i.SC� 25 \ FIGURE U RE Z r �\ \vv�v. 1+ \ 20 $ discharged into the Larimer #2 Canal. The Final Drainage Report for the Market Place identifies this site as a separate basin and includes historical flows of 2.83 cfs from this site in the design of its storm sewer improvements. The Market Place Drainage provides for four parking lot detention ponds. These ponds overflow to the south via a driveway to Troutman Parkway when they eventually discharge into the Larimer #2 Canal. The Best Buy detention pond is designed to spill into these ponds. Drainage Criteria The Rational Formula was used to develop flows for this project. The Rational Formula is an excellent predictor of runoff in basins less then 200 acres. Drainage Under Developed Conditions The grading plan for the Best Buy P.U.D. site shows drainage flowing to a detention pond in the main parking lot west of the proposed building. This grading matches the existing terrain closely and conforms to the Market Place Drainage Plan. 0.33 Acres of Fountainhead In 1 1 1 1 EMST. EDG41 / OF PAVEME T --� DECEL LANE CURB INLET 0.383 PROJECT I.O. SIGN 15' SIDEWALK k UTIL EASEMENT W E)OST. SIGN TO BE REMOVED z a w 0 W PROPOSED ]' J SIDEWALK J 0 & RAMP = RIGHT-OF-WAY H O !n l® 1 ` 1 1 1 >< 1 nI / PARKING \ 1 I \ 1 RIGHT OF WAY 1 PARKING 1 I\� 1 FOUNTAINHEAD P.U.D. 1 M.-Lo BLDG �© ~ DETENTION n- i --- i--t i i i �i LkNOSCAPE AREA,., ;, T A,. R— D ,5 � �REA INLET TER 15 �1 i � I 1 wo--_�15AREA INLET 1 I 1 \ I I I I CONIC I II I I 1 I I II i Ty - RETAINING WALL / -- I SCREENING A9, REO'D. DOCK 28,820 I\ GRAVEL IT \ B — 20 FILTER 15 " 3 / Li i - .t - .....:..., ,...,.....:- 1511 CURB ——GRAVIEL-row —~ INLET -'" _ FILTER --� OVERFLOW Tu i' nmi_ull�k-jj- IT I i I I I I I I "Ab LEGEND IQ� BASIN BOUNDARY EXIST. STORM SEWER -- �_- I PROP. STORM SEWER 1 G BASIN DELINEATOR FLOW DIRECTION O 1 ROOF DRAIN 1 0 PROPOSED INLET 1 1 PPT TIAL\ _ \ C N T10a� , v. \ I \ \ —t- UttNm°�B \ \ 1 POSSIBLE SIDEWALKCON\ \ \�y \ \ PLLACE CTION 70 MARKET \ �— —)°4tr �\ \ ? \ 1� \ 1 1 I 1 1 \ 1 I I I I \ I I I i I I I OHAR-MDR I I f \ I FIGURE I r I l r r 1\ BASIN SUMMARY I Phase III (Basin C) drain towards this site. Also, runoff from South College Avenue (Basin B) adjacent to this site (0.33 acres) will be routed into the proposed detention pond (see Figure 3). An orifice plate will meter flows from the detention pond into a storm sewer which will be extended from the Market Place storm sewer system. Approximately 23,010 cubic feet of detention will be required for this site. This volume can be provided in the parking lot with .3 feet of freeboard available. Calculations for the detention pond are attached. A pipe will collect roof drainage at the southeast and southwest corner of the building and convey it to the storm sewer in front of the orifice plate. See Drainage and Grading Plan. Erosion Control This project is located within areas of moderate wind and water erosion potential as identified by the City of Fort Collins. Wind Erosion Due to the small size of the site, the protection provided to the site by existing buildings and landscaping, no wind erosion problems 'a 1 1 are expected and no provisions have been made for wind erosion control. Specifically, the northern property line has existing buildings and landscaping along the front 250' of the project. The existing site sits in a depression with existing grasses and trees. This vegetation will protect the site from wind erosion. The total construction schedule for this site is approximately 120 days. A hay mulch will be used to reduce wind created erosion during this time. Water Erosion This area sits in a natural depression created by the construction of adjacent improvements. This same concept is utilized for the final design. The detention pond will be placed in the parking lot in the lowest portion of the site. The detention pond will also be used as a sedimentation pond with gravel inlet filters being used to mitigate -erosion caused by stormwater runoff. Hay mulch will further reduce erosion from exposed areas. In 1 1 1 1 1 Conclusions and Recommendations It is recommended that a detention pond be provided to mitigate erosion and storm water runoff from the proposed Best Buy P.U.D. The detention pond will provide 24,220 cubic feet of detention in the parking lot. Off -site flows from College Avenue adjacent to the site and from a small area of Fountainhead Phase III are routed through the detention pond. Metered flows from the detention pond and roof drains will be conveyed through the storm sewer system provided by the Market Place P.U.D. and discharged into the Larimer #2 Canal. -10- t BASIN SUMMARY BASIN AREA (ACRES) RELEASE (cfs) REMARKS A 2.84 2.47 Best Buy On -Site B 0.33 0.29 South College Avenue Runoff Adjacent to Site C 0.33 0.29 Fountain Head Phase III runoff TOTAL 3.50 3.05 1. Allowed release rate is .87 cfs per acre. 2. The allowed release from this site is restricted to 2.83 cfs as per the Market Place P.U.D. Final Drainage Report. 3.: Approximately 24,220 cubic feet of detention volume. has been provided in the Best Buy parking lot. Overflow will occur to the south at the drive entrance at an elevation of 31.8. -11- F 1 1 1 1 1 1 1 r 1 I C. PARSONS & CLIENT (!_ I /Gr/I f� JOB NO. ��'r` E ASSOCIATES PROJECT U . Ur CALCULATIONS FOR stir rGCI ,J CONSULTING ENGINEERS /' 3 FL Co84u, Colamdo 80524 MADE BY— u DAT CHECKED BY DATE SHEET - OF I � —t �/'i+(�in �_� 14— �/1Ur�f ! � , _6,.5�� 3 y( i_ I syG+�r►'_%u�__i__ Sl 8.'_% __±___ I ' 71 01 _� {� fie I �— (41t /a C t I ' in((l i 33 _OT _ to t , iI/l� �v4 /�� t I I i i ��rp��! fi ,_ n( rJ777/// !� < .e r /a dHl 1''R/1'_f fff/%YCl10�S 1 { L_.+1. a ._....:_ ..J-_.... _._... __� .._•.... • _ i . _. � ._ .. .. :; I Geo��- I BL L_ 1 z �o OV I I J PEARSONS & CLIENT JOB NO. p �f —1 ASSOCLATES PROJECT o u NO, CALCULATIONS FOR — CONSULTING ENGINEERS JW VIM . Lyle 2 3 Ft. Collins, Colorado 80524 MADE BYDATE CHECKED BY DATE SHEET OF F � I 21)li rao i—)+�8 +�Jl-Irp, ff T%e I j' D�st�u� I�oluMt (c) - _Vr,(G�Q r-�- . x- (n,�.)Cft_') i184 � 30 y iS j(y is ! YzGlJS`� SD9 y _. _I ?1 T 14 L-1__( 101 _,3Z 760 - _Lo lS�a z2. S7Z -� 1 WIAla -I E_-U'll�' , �'�i��_Q�y /"Gt�i�. �� � �oi� � -;.—' ---; _ �-_..� S',l'(wa 3(•� .IS j I i i Lap �0 Initl• . � ! ' ���� . � t � ,�p—I (L_ —! `I/ 4 han (Vo�ume' '• i �ou�i PonB Ilo�u0P — r �_J� ! _`f'leginfrirl.Arru i I(ur?'J,_Ploar,�elvPd.A�ca_.'_�I/o ✓U 1 I rI I i 4 3Oo_ _fo, nL_f '. _ ;3100. ;. ► , 033 yevy . - ' 3a 50--i ; . �IOoS- 'loot 30.00_i._ 0 = ! ,I -- �- 1—=—Tell 1(061(- Ili YYI t- 12 1-711 - 2 it 210 Ft 7 13)010' I f3 PARSONS & MASSOCIMES CONSULTING ENGINEERS FL Comm. C010radO 80524 () -p / I I CLIENT JOB NO. q?, /� PROJECT11 V' CALCULATIONS FOR foaj MADE BY -JklC DATE Ld'k CHECKED BY-DATr SHEET OF 4 7_7 z613 �f T, I I :a !6 47 - rli, C4 k4fl _- --- orl V r... 7­7-- 33 fle.­11 ArA ... V# i - f t 0,0e A sf 7_7 Ji---- --- 4 +��/�1.F�N/{J-!+,S;-.S� G�,�41_ .?�.6' � -'.._ 'UJe 6.1..CI���/A9 -` --�-- - �. -- { t 4 ..... . .. (_flQjVS d� 15 wai aljo _J�Jh( ld 1�e I%Ao Aare i we in (19Y.—Iswa. d_ ih4 i dft'l�(f ro-A�y 40,jq� fr Q de f ea, W wo 461�yl"T.k Ae ro?fI)Ja �P�M_Aaf Ajo, flovs will rof I 'qy,.4 r J -1 , aim.m - kiwal 44 r+fC ra aa thIf -6,faf Killf, w1fAill 5 fv p 47, s me 'k-ylao", f? acl� 11405 /1 'it �l IS FINAL DRAINAGE REPORT 1 FOR ` THE MARKET PLACE LOCATED' AT SOUTH COLLEGE AVENUE AND TROUTMAN PARKWAY FORT COLLINS, COLORADO REVISED 1/2/90 TO' BE DEVELOPED BY: ROSENBAUM/DEAN COLORADO SPRINGS,iCOLORADO . if PREPARED BY: PARSONS & ASSOCIATES 432:;Link Lane Plaza Fort Collins, CO 80524 (303) 221-2400 I ! PROJECT NO. 89.07 ROS n PARSONS & CLIENT e-ClSF--QL=SA0kA -DF—=Aj!,j JO8NO..zL-D2 EISJ;Ei ASSOCLATES PROJECT Di !/2S C' CALCULATIONS FOR CONSULTING ENGINEERS MADE By----L-- DATE CHECKED BY—OATE SHEET --LG—OF Ft. coma ca:--Ao 8=4 L Y.3 J. L) -SF-b ts o'! C�) S.- 14. HSns, I ram i'i :.p )4-si T 7 4-- A- -L-j -4-L m i I -T—T .. .... 1-Z -4- jl _J.e�-7:77 16l! 4 -7 -/o. JI a ILI I —4— I—TLZ 1-4 s.!-77..Z. I tJ. /-.V4 C, .1 -4-1 1 -F--I--�-SLOPS-- b-%�IYi]Li 1l' ' I.. ,-� i,77(c 26-7 G `SIRE 6= No Text No Text RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: desi B uy rf 0,, 0, STANDARD FORM A �TP1 COMPLETED BY: /f Coach DATE: , -?Mz DEVELOPED ERODIBILITY Asb Lsb Ssb Lb Sb PS SUBBAyIN ZONE (ac) (ft) (%) (feet) (U . M I�Je�a% 2, gy 3so 1 / - - 77. z 'Toile S- � poye ' MARCH 1991 8-14 DESIGN CRITERIA I 20 .1 1 1 1 EFFECTIVENESS CALCULATIONS PROJECT: geji gu/ P U 0 STANDARD FORM B COMPLETED BY: DATE: Erosion Control C-Factor P-Factor Method Value Value Cominent scdlp,cAf Tme bo 0.5-0 !✓dd Vdf r,., fod padem ea 0.01 1,00 fees}iay S. 6410 o be Roof Sid¢Walk d 01 1.00 ,ZMfiavenee13 ea�� .crowd J., 00 1-00 _ Bu�1d �.� 51 ie flatNulcti a06 !0o pkim, lop �4dp,Sare . MAJOR PS SUB AREA BASIN BASIN (Ac) CALCULATIONS 71•t 2.g� Nay: MG d PAJ & 61, rOwc 2. 19 it ej pvddly Slle —(tad'¢ G.-Y0,14 a rfirms li1al4lej .C/r o7' Tato1 Z.SyfICrCS �! o X. 6s)1 (o. od x) z• fq FFF = (1- (0.5-r, x lob, = vfo gG % 77..1 a 0K_ ' MARCH 1991 8-15 DESIGN CRITERIA cl CONSTRUCTION SEQUENCE ' PROJECT: QPfI 6(14 U�/ STANDARD FORM C ' SEQUENCE FOR 19 /Z ONLY COMPLETED BY: JPJj CadCA DATE: Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for ' approval by the City Engineer. YEAR ' MONTH J F l i1 y I M 1 7 I J 0 I Al 1 0 OVERLOT GRADING �ounc�a�tOv s I • WIND EROSION CONTROL Soil Roughening I �A . Perimeter Barrier ! X�p�OYenry Additional Barriers ' Vegetative Methods Soil Sealant Other Ra11u(f� i RAINFALL EROSION CONTROL ' STRUCTURAL: Sediment Trap/Basin Inlet Filters Straw Barriers Silt Fence Barriers l Sand Bags ' Bare Soil Preparation Contour Furrows i Terracing !� Asphalt/Concrete Paving - ' other .. i , i i VEGETATIVE: i ' Permanent Seed Planting Mulching/Sealant f �, Temporary Seed Planting Sod Installation I 1 [(A1AA14l Nettings/Mats/Blankets �4adJC�N; other ' STRUCTURES: INSTALLED BY MAINTAINED BY VEGETATION/MULCHING CONTRACTOR ' DATE SUBMITTED APPROVED BY CITY OF FORT COLLINS ON ' MARCH 1991 8-16 DESIGN CRITERIA. i