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HomeMy WebLinkAboutDrainage Reports - 04/02/1999 (2)Final Moved PROPERTY OF FORT CODUNS tyrnJWMDRAINAGE REPORT FOR LOT 15, PROSPECT INDUSTRIAL POUDRE RIVER BASIN PREPARED FOR DOHN CONSTRUCTION, INC. MARCH 15,1999 PREPARED BY STEWART & ASSOCIATES 103 SOUTH MELDRUM STREET FORT COLLINS, CO 80521 TEL. 970-482-9331 FAX. 970-482-9382 I 1 ' Table of Contents ' 1-2 Text of Report ' 3 Vicinity Map 4-11 Storm Water Runoff Calculations 12 Midpoint Drive Drainage Capacity 13-16 Erosion Control Calculations ' Pocket Utility and Grading & Drainage and Erosion Control Plan t Plat of Off -site Areas Draining to Midpoint Drive Hiisioric Drainage Basin Plat 1 I F $TmART$ ssoCIATE$ Consulting Engineers and Surveyors March 15, 1999 Mr. Basil Hamdan Storm Water Utility City of Fort Collins ' P.O. Box 580 Fort Collins, CO 80522-0580 Dear Basil, The following is the Final Drainage Report for Lot 15, Prospect Industrial Park, City of Fort Collins, County of Larimer, State of Colorado. The site is in the Poudre River Basin and contains 1.3724 acres. The existing site slopes from Northwest to Southeast at an approximate slope of 0.7%. The site has a very good ground cover of grass and weeds. The historical runoff sheet flows off the property to the South. The historical drainage plan is included in the pocket of this report. It is proposed to divide Lot 15 into two new lots which each will have an office/warehouse building. The site will be phased with Lot 15-A being Phase I and Lot 15-B being Phase H. The site is in the Poudre River Basin and is within approximately 1100 feet of the Cache La Poudre River. Due to this close proximity to the River, it is proposed to not have storm water detention on site. The runoff from the basin enters the outfall system to the River at the existing inlets at the comer of Midpoint Drive and Sharp Point Drive. The Westerly inlet is only 450 feet Southeasterly of the Southwest comer of Lot 15. The two inlets drain in a 24 inch R.C.P. to an existing gravel pit which drains into the Cache La Poudre River. The OFF SITE AREAS DRAINAGE PLAN is included in the pocket of this report. The stormwater will be carried in the on -site curb and gutter to the oil and sand 'interceptor from which it will discharge into the Northeasterly gutter of Midpoint Drive. The Phase I Building is Developed Basin- 1 and the developed runoff rates for it are Qn,, = 2.47 c.£s. and Q00 = 8.57 c.f s. The second phase is Developed Basin-2 and the developed runoff rates for it are Q,,,, = 0.41 c.f s. and Q100 n= 1.15 c.f s. There is not any appreciable stormwater runoff entering this site from off site. Lots 10 & 11 which are adjacent to the rear of Lot 15, drain Southeast onto Lots 13 & 14. Lot 16 has not been developed at this time and some of its historic runoff will sheet flow onto D.B.-1 and D.B.-2. The grading on both basins will accommodate the off -site flow through each basin to Midpoint Drive. The offshe flow onto D.B.-1 is Q100 = 0.37 c.f s. and onto D.B.-2 is Q1. = 0.57 c.f s. There was some concern at the conceptual review meeting regarding the capacity of Midpoint Drive to carry the stormwater runoff that discharges into it. The flow in the Midpoint Drive South and Southwesterly gutter from Timberline Road to the North lime of Prospect Industrial Park is diverted to the East in a pan across Midpoint Drive and then to an existing pond in the Prospect East Industrial Park. The North and Northeast gutter of Midpoint Drive flows into the Specht Point Road, Prospect Parkway and the above described pan. There is a high point in Midpoint Drive 110 feet South of the pan at the North James H. Stewart and Associates, Inc. 103 S. Meldrum Street P.O. Box 429 Ft. Collins, CO 80522 970/482-9331 Fax 970/482-9382 lime of Prospect Industrial Park. The pan crosses at the Southeast comer of the existing Larimer County Jail property. Therefore, 1200 feet of Midpoint Drive is carrying runoff from the high point to the Northwesterly comer of Lot 15. Three of the lots that have been developed have onsite detention. Five lots that have been developed do not have detention and eight lots have not been built on. The resultant runoff coefficient for the 14.3 acres is 0.35 Since Lot 15 is at the low end of the basin and near the discharge to the Cache la Poudre River we are not providing on site storm water detention. The rate of runoff at the Northwesterly corner of Lot 15 is Qrn = 6.5 c.£s. and Q100yr = 24.1 c.f.s. The capacity of the street cross section is 68.45 c.£s. at 6 inches over crown, which is allowable in the 100 year storm. The total capacity of the two gutters is 10.8 c.£s. which is allowable in the two year storm. The offsite area drainage plan is included in the pocket.. EROSION CONTROL: The site is located in a moderate wind erodibility zone and in a high rainfall erodibility zone. A silt fence will be required around the perimeter of the site prior to beginning any overlot grading. ' Immediately after grading, the concrete building foundation will be installed and gravel road base shall be placed in the driveways and parking areas. This road base shall be thick enough to handle construction ' traffic without failure. Straw bales will be installed after the site is graded and before the curb and gutter and asphalt is installed at the points where the runoff discharges into Midpoint Drive. This is a fairly small site and it will be very busy during building construction so vegetative plantings will not be done until the building and paving procedures are nearing completion. Wind erosion control on the site will be provided by the silt fence, building foundation and gravel road base. tAll erosion control procedures shall comply with the City of Fort Collins Criteria. The stormwater runoff calculations, the Grading, Drainage and Erosion Control Plan and the overall Utility Plan of Prospect Industrial Park showing the stormwater flows in Midpoint Drive are enclosed as part of this report. This drainage report and the design of the drainage system for Lot 15 are in compliance with the City of Fort Collins Storm Drainage Specifications and Criteria. Ifyou have any questions regarding this report, please call Sincerely, a. . Richard A Rutherford, P.E. & L. S. it 5028 RAR/meh _ 1 � 1 E ® ■ E. sec Prospect / �; 1 �� Mid oin/ ` �n Dr. a` COL 1 1� 1 1 __ GIN 1 LL od i II 1 �. East Drake Road 1 1 , 1 � VICINITY MAP SCALE: 1 "= 1000' 1 STEWART&6SOCIATES Consulting Engineers and Surveyors I I I I I I I I I I I I 11 I I r� L� I 103 S. MELDRUM, FORT COLLINS, CO 80521 PH. 482-9331 FAX 482-9382 By: RA P- Date: 7­ If f A Client: /4 V Co .urr. = Al r— Sheet No. 4 of_ I Project: R Q S P T- AJ 7-� U C F-4 P- Ir- Subject: 4 1 C -r n P- i F- = r-All LA-) A. -rez-7 e- Aj o j= ,-- C 4 Le U I -A -r/0 AIS H--i-`s--T!- o- f G. i 8-WrILA.11 if !IM11:i 11 111 zooms' V3 I Y 0, z 0 x A, 6-773-V �H- if Z-1 0 IVi -0-—r-7- -T ry./e Ic XT-- if 11111IFTTI j1 ii if If FF ---- i I — fill if 1; if I I I I I I I I I I I I I I I I I U 1 STEWART&ASSOCIATES Consulting Engineers and Surveyors 103 S. MELDRUM, FORT COLLINS, CO 80521 PH. 482-9331 FAX 482-9382 By: F. Date: Zvi V Z 99 Client: --DoHAI (,oAjr-r, Zlqr. . Sheet No. S of Project: /,S;- , Pl-;,- oS Psr--r r" n. u-r-r-r- /A /- P4 9/c- Subject: H is -r n p— I C- 'ST-e)p-m U)A-rEP— R U /J e-) F r— L (-t) (- A-rlo x/ T F— to A al L!o T, D:6i 6. i/I A., T- L—4 -4- P'-. 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MELD1 RUAMX 4 8 29T3C8O2LLINS, CO 80521 Consulting Engineers and Surveyors By: E, A, Date: / 11-T J!7 6 Client: -i n HA) Com- r:r - Sheet No. of Project: /s, p— ge 0 jr per. -r = A) b (;-( TF- / A r - RA p- k Subject: S.J-DK/64 g oAiogz=G (^. ALr-u l-,4-r1oAlf I --7 HZ01 -ol:r-L J'-H 1J. 4-1 i Olt] 1 it x— '6 k-1 T I FJ 00 I I I tI ! z_3 � I i j � ��.v� F'R`oh_t__�.o ��s—;! �/�H��i 01.3 t 1 3- MT-121 0 F 10 - OF C-.- �13 le- I ? to z Ix 0j35 T x bS x ? -2s. E6�a4-L"z—M ;-i D�p-'-f 0 p- 01 0 1 �1 X: 614 Iq -71- .1 1 'A-z ll . : 1- 4— 1=:' J!TIIM111 -h -T 1.9 a I 103 S. MELDRUM, FORT COLLINS, CO 80521 PH. 482-9331 FAX 482-9382 1 1 [I 11 I 1 91 1 I 1 STEWART&ASSOCIATES Consulting Engineers and Surveyors By: j1 A- IZ Date: Sep—/pt,lylts Client: DO u AJ ('-Q A.s-r• stif-. Sheet No. _L2. of _ Project: o /,S- lF'zot/ae= r.-r rA)twrrg—IAA PA.PK Subject: JAinvni.vT ,vE. T22,4.iAj46, ,ry I` �Xls_T_i A7G�L-oils—Bv.%c.t�0, ll._ i(() i_T/f I�.LI ID_ETE.�T/oN I 3 —# ! 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I 1 11 1. ,..__. 1 1 1 1 RAINFALLPERFORMANCESTANDARD EVALUATION ------------- -----------------------------------------------I PROJECT: L oT !S, Fi-ospcc7 -T, -ovsnemt- I'ARK STANDARD FORM A {COMPLETED BY: %2- --ATE 7 Z ---------------------------------------------------- — ------1 {DEVELOPEDIERODIBILITY 1 SUBBASIN I ZONE I rJ� _ � Mod eraie_. I Wind Nr h I rJ13-Z Raln�a7/ Asb I (ac) ------- 10-93 I Lsb I (ft) I------- 1370� I Ssb I (ro) I------- 10.sT � I Lb I (feet) I------- I Sb I(%) I------- I PS I (A) I ------- tI 13Z 10.54,1 �2,8 I I I I I 1 I 1 I I I I I I I I I 1 I I I I I I I I I I I I I { _______________________ DI/SF-A:2989 lI A 04) EFFECTIVENESS CALCULATIONS PROJECT: LO r /S, 20SPEGT = vD(JrT e�AL t�4z E STANDARD FORM B COMPLETED BY: -A•. DATE: 7 2 76 Erosion Control C-Factor P-Factor Method Value Value Comment Bare Soil /.00 1_00 Buildin FoV� Wro� a Od A•G 4-d curtc pvm-k v.01 1.00 Gravel road b'G7e O. O!o l•00 MAJOR PS SUB AREA BASIN ($) BASIN (Ac) CALCULATIONS 23-1 72-8 0.65 6oildt�j F4117 0.17 Ac Gr,w el road.base O. Z0 AC - AG er conc Pvn . 0.0 P Ae- bare- si 0 0. 11 A c- 0. 6> G = 0.31 DB-Z 72. U,93 l3ugcl1�5 Fdn 0.17 Ac Gra�/el road bate U,ZP�A� conc. pwwk bare Sor/ 0.36Ac. G=(d.t7ko•a�+�o.zexo.o6�t�p.[a��o.o[)f•�0.38��1.va� G = 0.+3 P = o.So = s�1�- -1•e�ce Tor,4L s171_ 7Z.8 /.-58 EFF= (0.C5)(Fr4.A) 4- CO, T3)(7&-s� 51. 0/O�r ... nA.. 4.L 0 ncefr_ra roi7coie Cis CONSTRUCTION SEQUENCE IOJECT: _LOT /�. P20SF1=G7- rAv L)ST-,e/,44 /qeA;: STANDARD FORM C SEQUENCE FOR 19 ONLY COMPLETED BY: 1e.A 02. DATE: Oue-y Z,/L3 Licate by use of a bar line or symbols when erosion control measures will be installed. Sajor modifications to an approved schedule may require submitting a new schedule for 1roval by the City Engineer. 119, YEAR MONTH I -t- I C I JA I A I J. GRADING �D EROSION CONTROL Soil Roughening Perimeter Barrier Vdditional Barriers egetative Methods Soil Sealant 'Other—GKAVBL$.AS6 AINFALL EROSION CONTROL 'STRUCTURAL: Sediment Trap/Basin Inlet Filters Straw Barriers Silt Fence Barriers Sand Bags Bare Soil Preparation Contour Furrows Terracing 'Asphalt/Concrete Paving Other — Fo&1,vz>Ario v IVEGETATIVE: Permanent Seed Planting Mulching/Sealant 'Temporary Seed Planting Sod Installation Nettinge/Mate/Blankets ' Other FTURES: INSTALLED BY MAINTAINED BY ZETATION/MULCHING CONTRACTOR SUBMITTED APPROVED BY CITY OF FORT COLLINS ON MARCH 1991 B-16 DESIGN CRITERIA I I I I I I I I I I I I I I I I I I 1 STEWART9,06SOCIATES 103 S. MEL933DRUM1, FORT COLLINS, CO 80521 PH. 482-FAX 482-9382 Consulting Engineers and Surveyors By: Date: Client: Sheet No. of Project: Subject: ro-5 i a n G o ri 4-ro I C o 11 GtI-e-r-a I 0 0 == C/& 0 U_af--;k 3, �- { �' I i ( j I i I I I � I � L-L Nk I --- 1 41 I L I 1 SC4LE. 1 20' YO 0 PO IO BO fMAPNAC SG11E — FFE! z Z O O V/ U O K � N Z O U K toO t C1 W V / a w � m 0 0 Q=}3 00 U s �WWWOZyy� O Q LLLJz� o = w ^ z Q o� a Ke o PUYeFA �� iz/alga li PY£i NM9EP I � oil