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HomeMy WebLinkAboutDrainage Reports - 12/01/1986F �Le C) V2-Ub rtJAr'Z- FINAL STORM DRAINAGE REPORT CACHE LA POUDRE INDUSTRIAL PARK AND PITKIN - RIVERSIDE STORM DRAIN Shiloh, Inc. Technical Consultants Fort Collins, Colorado December 1986 (Rev) Page 1 Introduction Flood Plain Data Off -Site Drainage Major and Minor Storm System Design Interior Drainage References EXHIBITS AND FIGURES Exhibit A Vicinity Map Exhibit B Flood Plain Data Exhibit C Storm Hydrograph (100 YR) (4 pages) Attached computations - 4 pages Engineers Estimate of December 8, 1986 Page 2 I W y e"ki The purpose of this report is to identify and address the various drainage issues concerning the Cache la Poudre Industrial Park. The proposed development is located adjacent to and on both sides of Timberline Road (extended), a short distance north of Prospect Street in east Fort Collins. (See Exhibit A) This area is generally low-lying and flat although the western edge of the property rises abruptly. Elevations over the site range from 4900 to 4926 but most of the area lies between 4900 and 4910. Spring Creek flows close to the southeast corner of the property and the Cache la Poudre River lies 1400 feet to the north and 800 feet to the east of the boundary. Gross area of the site including various easements and rights -of -way is 109.1 acres. The site is presently owned by Mobile Premix Company and is in use for gravel extraction and a concrete batching plant. In prior years the gravel has been extracted from about three-quarters of the site and mining is underway in the northeast quadrant of the property. The owner expects gravel operations will continue for one to three years until aggregates are exhausted. Mobile's facilities are currently served by a gravel road which occupies a portion of the right-of-way for the planned extention of Timberline Road. Approximately six years ago plans were prepared by Centennial Engineering, Inc, for the Timberline Road project from Prospect Street to East Mulberry Street (Colorado Highway 14). These plans will be used for the development of this site except that the proposed cross-section required by the City of Fort Collins will have concrete curb and gutter rather than the rural cross-section shown on the drawings. Several utilities traverse the site parallel to Timberline Road including a large sanitary sewer, telephone, electric power and natural gas lines. FLOOD PLAIN DATA Current published data shows that the site is in the fringe of the 100 year flood (ref 1). See Exhibits A and B. Exhibit B is a composite of the data taken from the references with emphasis on the site under study. An examination of Exhibit B together with topographic data suggests the following: A. Due to terrain to the immediate north of the site, the site Page 3 is not in the direct flow of the River (floodway). Further, the site is in a backwater condition. This means that the higher water levels in the northeast corner of the site are in error and inconsistent with the hydraulics in the main channel, a situation not uncommon with generalized data resulting from computer analysis. B. Given the data in the reports and recent topography, water surfaces are predicted to be very near the existing ground. It is recommended that preliminary minimum finished floor elevations as follows be used to place floor levels two (2) feet above the anticipated 100 year water surface: Northwest 4912.0 Central 4910.0 Southeast 4909.0 However, before issuance of building permits or footing/foundation permit, a variance from the Fort Collins Storm Drainage Board must be applied for and approved. A criteria of floor elevation not less than 1.5 feet above the F.I.R.M. 100 year base flood elevations shall be used. It should also be noted that since the publication of the 1979 FIRMS, a new bridge has been built on the Poudre River at Prospect Street and a new FEMA study is now underway that may significantly affect the base flood elevations. Topography of the site is such that little or no storm water flow enters onto the property from anywhere except the upland west boundary. This flow entered the site through an existing railroad trestle across right-of-way owned by Burlington Northern Railroad Company. Flow was intercepted by the Chaffee Ditch, which runs along the the entire west side of the property. It is awned by the City and is no longer used to carry irrigation water. The ditch is now abandoned and obliterated along most of its length. Flaw now runs into the nearest lake in an uncontrolled earth channel. Historic flow rate is established as 40 cfs, the maximum computed discharge of a 24" cast iron pipe culvert under the Union Pacific track, 350 feet west and upstream of the aforementioned BNRR trestle. The City staff has indicated the possibility using this ditch to carry storm water originating west of the site to Spring Creek. The design flow for the outfall system provided by the City Storm Drainage staff is 375 CFS for the 100 year storm. See Exhibit C. The ditch must be repaired if it is to function as a drainage channel. In order to effect this storm water scheme, it will be necessary to construct an outfall Page 4 channel from the Chaffee near the southwest corner of the site, along the south boundary to the southeast corner and Spring Creek. Some design problems are anticipated due to the flat grade of the proposed alignment and the desire not to change the proposed profile grade for Timberline Road. It does not appear feasible to carry 375 CFS along this route and under Timberline Road. Alternatively, a flow-thru scheme was discussed with City Staff at a meeting of March 27, 1985. (Covered by letter of April 2, 1985). In this scheme, the lakes would take the off -site flows and discharge these flows into the River or into Spring Creek adjacent to our property. This appears feasible and even beneficial from a hydraulic point of view. It seems preferable to the use of the Chaffee Ditch and construction of a new channel and associated crossing under Timberline Road to Spring Creek. In view of the above discussion, the following was resolved and agreed by the City and the Mobile Premix Co. to solidify the flow-thru alternative: A. The City show some assurance of assistance regarding effects of upland pollutant spills and degrading of lakes and ajacent properties due to passing off -site storm waters. B. The City study means of control of water quality of discharges into the lake system such as appropriate structures on the inlet side. C. The City support its fair share of the maintenance and upkeep of the storm drainage facilities of the system. The above issues and other matters are contained in the Development Agreement for Cache La Poudre Industrial Park, executed August 23, 1985. The Agreement is the controlling document for the storm drainage issues and further detail can be found therein. MAJOR AND MINOR STORM SYSTEM DESIGN Through the period March 1985 to November 1986, negotiations took place with adjacent landowners and the Burlington Northern spearheaded by the City of Fort Collins Storm Drainage Utility to implement the flow -through alternative. The result is a pipeline under the existing trestle, spilling into the existing lake. The project, entitled Pitkin-Riverside Storm Drain , has the following portions in its first phase of construction: Tie into the existing RCP crossing culvert on Academy Drive; Run Class 5 concrete pipe under the trestle, 133 LF; Channel this into the lake, 63 LF; Repair and improve the lake shore in this vicinity; Inlet and culvert under Timberline Road, 200 LF; Page 5 Inlet and outfall line to Spring Creek, 605 LF. These elements are shown in detail on the preliminary drawings, specified to conform to the City of Fort Collins Storm Drainage Standards, May 1984. A City supplied hydrograph of the off -site tributory drainage is attached as Exhibit C. Results of computations and design analysis, in summary, are as follows: Discharge of the design storm event = 18.6 acre-feet, producing an estimated rise in the first lake of 2.5 feet (maximum). Under this head, Timberline 36" RCP culvert will flow at about 62 cfs. The downstream inlet and outfall line are sized to flow at the historic 40 cfs. A dry spillway to the east shall take any overflow but overflow is not anticipated due to detention in the lakes. Upstream, detention will exist west of the Academy Drive embankment and possibly, west of the trestle embankment, if Academy is overtopped. The computed capacity of the existing HE 76x48 RCP is about 200 to 300 cfs under inlet control. RCP of 54" diameter at S = 0.07 is specified downstream of this crossing; energy dissipation and rock lined channel conducts discharge to the first lake. During the major storm event, discharge velocities of about 33 fps will occur at the pipe outlet. Computations are attached. An Engineer's Estimate, related to the preliminary drawings, is also attached for clarification and cost administration purposes. The lakes shall also receive on -site runoff during minor and major storm events from the lots of the Industrial Park and Timberline Road. These lakes, an integral part of the Industrial Park improvements, will be interconnected with underground pipes so that they will maintain controlled surface elevations. The outlet will be to Spring Creek. The predicted 100 year water surface in Spring Creek is 4902.4 ( from the Gingery Associates report dated August 1980). I kIM : OC 1 0'0 In contrast to the usual situation where storm runoff flows from the lots into the streets, the streets on the site will be above the lots in most cases. There are two low points in the design of the proposed Timberline Road. One is in the approximate center of the site at the proposed Hoffman Mill Road intersection. The other is about 100 feet south of the subject property. Runoff will flow from the Timberline Road surface to curb openings or Page 6 curb inlets, to drainage swales and then to the nearby lakes. Site drainage of the individual tracts will be into on -site swales into the nearby ponds. Surface drainage is considered the most aesthetic, economical and trouble free alternative drainage method; drainage will be designed and built to City of Fort Collins Storm Drainage standards. Bath Landscaping Company borders the site on the southwest and is experiencing drainage problems. The City has requested that some of Bath's property be drained into the proposed improvements. This shall be considered in the proposed design but no drainage improvements are proposed on the Bath property itself. Due to the position of the site in the Spring Creek drainage basin, no additional detention of storm runoff is required or recommended. Shiloh, Inc. John R. Clark P.E. December 29, 1986 References: 1. Federal Emergency Management Agency (FEMA), FLOOD INSURANCE STUDY - CITY OF FORT COLLINS, COLORADO July 1979 and February 1984 (Plate 09P). (Composite data shown in Exhibit B.) 2. American Concrete Pipe Assoc. CONCRETE PIPE DESIGN MANUAL 1ST ED. 1970. 3. Morris, H.M. and Wiggert, J.M. APPLIED HYDRAULICS IN ENGINEERING 2ND ED. 1972, the Roland Press Co, New York. Note: Development Agreement for Cache La Poudre Industrial Park PUD , executed August 23, 1985 is a governing g document. Page 7 April 14, 1987 JRC/Shiloh Inc BID LIST (Revised) SCHEDULE A - BNRR UNDERCROSSING UNIT $ AMOUNT $ Al. 54" RCP, CL 5 126 LF 155.00 19530.00 A2. 72" INLET MANHOLE 1 LS 3000.00 3000.00 A3. CONC HEADWALL W/WINGS 1 LS 5840.00 5840.00 A4. CONC STOPWALL 1 LS 735.00 735.00 A5. CONC BOX ADDITICN 1 LS 2035.00 2035.00 A6. EMBANKMENT W/HAUL 800 CY 7.00 5600.00 A7. CHNL SLOPE PROTE T 39 SY 14.00 546.00 A8. PREP & NATIVE SEEDING 972 SY 2.00 1944.00 A9. RIPRAP W/FABRIC, CL12 98 TON 40.00 3920.00 A10. BOULDERS (PER SCHEDULE) 8 TCN 40.00 320.00 All. DEWATERING AND DIVERSION LS 2000.00 2000.00 Al2. MOBILIZATION LS 15% 6820.00 TOTAL SCHEDULE A $ 52290.00 SCHEDULE B - MOBILE PRE -MIX SITE WORK B1. 36" RCP, CL3 PIPE 911 LF 80.00 72880.00 B2. 36" RCP, F.E.S. 3 EA 750.00 2250.00 B3. INLET MH, PRECAST, 5' DIA 3 EA 1500.00 4500.00 B4. INLET GRATING W/HARDWARE 3 EA 400.00 1200.00 B5. CHL SLOPE PROTECTION 133 SY 14.00 1862.00 B6. PREP & NATIVE SEEDING 1800 SY 2.00 3600.00 B7. RIPRAP W/FABRIC, CL12 8.1 TON 40.00 324.00 B8. RIVER ROCK W/FABRIC CL12 65 TON 50.00 3250.00 Page 8 B9. UNCLASS EXCAVATION AND BACKFILL, POND SLOPE 1400 CY 2.50 3500.00 B10. STD MANHOLE, 5 FT DIA 1 EA 1500.00 1500.00 B11. MOBILIZATION LS 15% 14230.00 TOTAL SCHEDULE B $109096.00 TOTAL BID SCHEDULES A and B $161386.00 ADD CONTINGENCY AT 10% 16140.00 TOTAL ESTIMMATE 177526.00 ENGINEERS ESTIMATE 180,000.00 NOTE: Conversion factor for rock = 1.35 TOM per CYD. Page 9 Plummer lack OW •• f950'•., Nortn lYar " - s« °. Srh: r� JuwtJDn .•� • J' _ _. . 9 f— LO ADO A THERM ° , • •� Seung .:.-: 'z •V c SugarR nary And-1!—_•\L.� In fd I, ucki �anr I I • � (' , ,� 1141 r a 7 1 WALL ia•.. _�:2 `•: Al PARK �! '�r��'•y,� LEbti,: i -20 , • � �•- � Ro lawn \e l � Z • a ; ICe twege � -.. �� it li 49 .II" '•il met 44� 70y�,• , Arrow 0© °a p° 113 un`` nsGlal�x' ` i • c JAL SPARK b ; ? d r - 'Jir." •~OSPEC STR E' `A 9. ree .e 4ia _t h °: y r, I I G iv .; 'llllII The 24 z , I eM 4e89 r a1 J ' m yy �• i1996 4e74 • ° 1 <• I I a` �`\BC � . Shiloh inc. FORT VICI ITY MAPJ EXHIBIT A 1 703 �B2L IN567 OLORADO 8 0 ZONE OF Ml13\MAL FLa' Wtj-L � FL000w�Y CACF4& LA. pOuDR£ R.W C'= e 44FFj 01�A n ITLA J / ^`4 !!! M PM PST'{ Fuel o %5TLEE 1 I > rope \' < C �e � MINIMAL LOT, Y / MPM �YAP�TLZ `1 e �aoDlls4 wo Ij Shiloh inc. \� FORT COLLINS, COLORADO 00521 1-303-402-1557 2v h4'� � ¢96EeF pLo'o0 FRINGE �oNE of MINIM4L FLanD%tSC �PIZ�N(s CRfCK ev �"F".-- ZONE OFhmNIMp-L' EXHIBIT FLDDDI NC BASIN AREA = .1302 SQUARE MILES LENGTH OF DRAINAGE PATH = .625 MILES DISTANCE TO THE CENIROID OF THE BASIN = .303 MILES AVERAGE SLOPE OF BASIN = 1.2 % IMPERVIOUS AREA = 61 8 BASIN FULLY SEWERID Ct = .284666 Cp = .549259 Qp = 264.872 CFS Tp = 12.8677.MIN. W @ 50 = 14.7468 MIN. W @ 75 = 7.66832 MIN LIME UNIT HYDROGBAPH (MIN) (CFS) 0 0 5 119 10 214 15 228 20 137 25 107 30 80 35 53 40 26 45 0 VOLUME PRODUCED BY 1 INCH OF RAIN OVER BASIN = 6.944 AC.FT. VOLUME OF UNIT HYDROGRAPH = 6.81692 AC.FT. DIFFERENCE IN VOLUMES =-1.83001 % c 100 YEAR DESIGN STORM PERV.AREA= 39 $ INPERV.AREA= 61 % 39 % 618 TIME INC MAX DEP EFF EFF DEP LOSS EFF EFF TOT.EFF PRECIP INF'IL STORE PRECIP PRECIP STORG PRECIP PRECIP PRECIP MIN IN. IN. IN. IN. IN. IN. IN. IN. IN. IN. 5 0.05 0.04 0.01 0.00 0.00 0.05 0.00 0.00 0.00 0.00 10 0.08 0.04 0.04 0.00 0.00 0.05 0.00 0.03 0.02 0.02 15 0.12 0.04 0.08 0.00 0.00 0.00 0.01 0.11 0.07 0.07 20 0.14 0.04 0.10 0.00 0.00 0.00 0.01 0.13 0.08 0.08 25 0.25 0.04 0.21 0.00 0.00 0.00 0.01 0.24 0.14 0.14 30 0.42 0.04 0.07 0.31 0.12 0.00 0.02 0.40 0.24 0.36 35 0.75 0.04 0.00 0.71 0.28 0.00 0.04 0.71 0.43' 0.71 40 0.31 0.04 0.00 0.27 0.10 0.00 0.02 0.29 0.18 0.28 45 0.18 0.04 0.00 0.14 0.05 0.00 0.01 0.17 0.10 0.16 50 0.13 0.04 0.00 0.09 0.03 0.00 0.01 0.12 0.08 0.11 55 0.10 0.04 0.00 0.06 0.02 0.00 0.01 0.10 0.06 0.08 60 0.07 0.04 0.00 0.03 0.01 0.00 0.00 0.07 0.04 0.05 65 0.05 0.04 0.00 0.01 0.00 0.00 0.00 0.05 0.03 0.03 70 0.04 0.04 0.00 0.00 0.00 0.00 0.00 0.04 0.02 0.02 75 0.03 0.04 0.00 0.00 0.00 0.00 0.00 0.03 0.02 0.02 80 0.03 0.04 0.00 0.00 0.00 0.00 0.00 0.03 0.02 0.02 85 0.02 0.04 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 90 0.02 0.04 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 95 0.02 0.04 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 100 0.02 0.04 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 105 0.02 0.04 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 110 0.02 0.04 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 115 0.01 0.04 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 120 0.01 0.04 0.00 0.00 0.00 0.00 0.00 0.01 0.01 0.01 TOTALS 2.89 INFIL 0.50 1.61 0.63 0.10 0.14 2.65 1.62 2.24 L%IAICbkT G (z) '30 UNIT EXCESS TIME MFOGRAPH PRECIPITATION (CFS) (INCHS) (MIN) 119 .02 5 214 .07 10 228 .08 15 137 .14 20 107 .36 25 80 .71 30 53 .28 35 26 .16 40 0 .11 45 0 .08 50 0 .05 55 0 .03 60 0 .02 65 0 .02 70 0 .02 75 0 .01 80 0 .01 85 0 .01 90 0 .01 95 0 .01 100 0 .01 105 0 .01 3-10 0 .01 115 0 0 120 0 0 125 0 0 130 0 0 135 0 0 140 0 0 145 0 0 150 0 0 155 PEAK FLOW = 315 CPS m (CFS) q(70 (I-zeo9 )'iz- � Rok- S-0 zm ZZ7 170 TIME TO PEAK = 40 MIN L'7Ct-�IBtT G (3 OD CD ^� o C C V 170 00 OU (Io- Vn LLI r C , h W r �001 �iLY 1 hri cm cm T4 Un LLF- Cj-wa� owu �cN\6,T c C4) a 0 Pfjt(-ys(s . Ile R 1 Q ovejj /C 7- �13.17y1 i{E quXl� .0i8 '13-.._-___ _a3 10 d _ •4V --� : O-I U �tD -ol�l 'e Ss,V LDS 011 - --- ,ww a�yap In ta+ _i-?.s _ _ - �-t r1 3 q_. L ss-_W °` Q_ ^' 7.0Qck -- w depth-I—S.5 4-o z�ao sau�� S�Cae&ge this is c� r W,M,'Pu-{ e uk i, I " Opt�A �U �uI�Q �C i r L4�w c +t c,V,\A�Au es v%o �) I I Ao-uj n c- 4s eoAI.4, ` r3 oio-oil I oo = 0- r 0 IZ�b-�6 TO N N XP � 4) r M 94 Ci aj Q I � � O N • � _ _ f 02 � L 1 V 00 J _ J 1� _ o \n o' o r4N \n v . — ` It Q _ �.3 v- —� 1- --— 0 - - - -_------- TJ _ - - II T SI al n I �0 M 1\1 'Z (a � J Il" E6cL b - -- Lr.K 1-03f— (1_ ) -- - tz.%%.- -- —t�oN - tt+o tFc(�Nt - sce�y f �tp -tow �zx+c.tME . �-- I� L 1 t6 �Z BID LIST SCHEDULE A - BNRR UNDERCROSSING UNIT $ AMOUNT $ Al. 4'SIBCA, C �5 ` 126 LF 155.00 19530.00 A2. 72" INLET MANHOIE 1 LS 3000.00 3000.00 A3. CONC HEADWALL W/WINGS 1 LS 5840.00 5840.00 A4. CONC STOPWALL 1 LS 735.00 735.00 A5. CONC BOX ADDITION 1 IS 2035.00 2035.00 A6. EMBANKMENT W/HAUL 800 CY 7.00 5600.00 A7. CHNL SLOPE PROTECT 39 SY 14.00 546.00 A8. PREP & NATIVE SEEDING 972 SY 2.00 1944.00 A9. RIPRAP W/FABRIC, CL12 98 TUN 40.00 3920.00 A10. BOULDERS (PER SCHEDULE) 8 TUN 40.00 320.00 A11. DEWATERING AND DIVERSION LS 2000.00 2000.00 Al2. MOBILIZATION LS 15% 6820.00 TOTAL SCHEDULE A $ 52290.00 SCHEDULE B - MOBILE PRE -MIX SITE WORK B1. 36" RCP, CL3 PIPE 711 LF 80.00 56880.00 B2. 36" RCP, F.E.S. 2 EA 750.00 1500.00 B3. INLET MH, PRECAST, 5' DIA 2 EA 1500.00 3000.00 B4. INLET GRATING W/HARLX4ARE 2 EA 400.00 800.00 B5. CHL SLOPE PROTECTION 133 SY 14.00 1862.00 B6. PREP & NATIVE SEEDING 1800 SY 2.00 3600.00 B7. RIPRAP W/FABRIC, CL12 5.4 TUN 40.00 216.00 B8. RIVER ROCK W/FABRIC CL12 65 TON 50.00 3250.00 B9. UNCLASS EXCAVATION AND BACKFILL, POND SLOPE 1400 CY 2.50 3500.00 PAGE 1 B10. STD MANHOLE, 5 FT DIA B11. MOBILIZATION TOTAL SCHEDULE B TOTAL BID SCHEDULES A and B 1 EA LS ADD CONTINGENCY AT 10% TOTAL ESTIMATE ENGINEERS ESTIMATE 1500.00 1500.00 15% 11416.00 NOTE: Conversion factor for rock = 1.35 TON per CYD. $ 87524.00 $139814.00 13981.00 153795.00 155000.00 PAGE 2 5-t-6A-M uap4 faAb ar u n u t 1-7 3-ice-boo I I P-0-A aq_� M �p9 n _ 2Q u cr7, {N a t �r �-(�� S"_�b (� L 0 wv AIJ c,,st9.x YJ .. �tX ,lu �. j-e3�Y'C,-_� .�i5-g— 6, - lc�.glu�tv.F,. �_ 1'CS�rc►��tv'1.___ _ _ 4?,,k (-_ asp n uf 9.o,,- 0,�Z .