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HomeMy WebLinkAboutEVERGREEN PARK REPLAT (NO. 1), BLOCK 5, LOTS 1 & 2 - PDP/FDP - 24-96A - SUBMITTAL DOCUMENTS - ROUND 4 - DRAINAGE REPORTASPEN ST LIMITS 11i j EATON 420- STREET ,to CEDAR SY C YF V1 I L CIF LN /I A y ILOODPLAIN EXHIBIT 1p�JV) LEGEND SPECIAL FLOOD HAZARD AREAS INUNDATED BY 100-YEAR FLOOD ZONE A No base fl nod elevations determined. ZONEAE Base fh,ml elevations determined. ZONE AH Flood depths of I to;3 feet (usually areas of panding): base flood elevations determined. ZONE AO Flood depths of I to 3 feet (usually sheet flow on sloping terrain); average depths determined. For areas of alluvial fan flood. ing, velocities also determined. ZONE Agg To be pr6tected from 100-year flood by Federal flood protection system under construction; no base elevations determined. i ZONE V Coastal flood with velocity hazard (wave action); no base flood elevations deter. 0 mined. ZONE VE Coastal flood with velocity hazard (wave action); base flood elevations determined. FLOODWAY AREAS IN ZONE AE r 1": 600' LOTS 1&2, EVERO 31 CI e4970 C 4968 9 14967 J tl PARK COMMUNITY -PANEL NUPncR 080102 0& MAP REVISED: C MARCH 18, 1996 It is understood by the undersigned that, by acceptance of this dedication, the Owner of Record of Lot 3, Block 5, Replat (No. 1) of Evergreen Park does not have the duty to maintain the easement. Witness our hands and seals this day of , 19 Kaufman and Robinson, Inc. STATE OF COLORADO) ) SS COUNTY OF LARIMER) The foregoing instrument was acknowledged before me this day of 19 , by Kaufman and Robinson, Inc. Witness my hand and official seal. Notary Public My Commission Expires: ATTORNEY'S CERTIFICATE This is to certify that on the day of , AD 19 . , I examined the title to the property hereon described and established that the owners and proprietors of record of said property as construed in C.R.S. 1973) 31-23-111, are as shown hereon as of said date. Signature: Address: Registration No. EASEMENT DEDICATION KNOW ALL MEN BY THESE PRESENTS: That the undersigned being the owner of record of Lots 2, Block 5, Replat (No. 1) of Evergreen Park, City of Fort Collins, County of Larimer, State of Colorado, as recorded in Larimer County records at Book 1157, Page 0128, Reception Number 85405, do hereby dedicate and convey to the Owner of Record of Lot 3, Block 5, Replat (No. 1) of Evergreen Park for their use forever hereafter a Slope Easement described as follows: Beginning at the southwest corner of Lot 2, Block 5, Replat (No.. 1) of Evergreen Park, -and being the TRUE POINT OF BEGINNING of this description. Thence continuing along the west property line of said Lot 2, North 0°00'00" West, 5.00 feet; thence leaving said west property line and continuing North 90°00'00" East, 383.00 feet; Thence South 00°00'00" West 5.00 feet; Thence South 90°00'00" West 383.00 feet to the TRUE POINT OF BEGINNING. Refer to Exhibit B attached hereto and by this reference made a part hereof Said easement contains 1,915 square feet, more or less. It is understood by the undersigned that, by acceptance of this dedication, the Owner of Record of Lot 2, Block S, Replat (No. 1) of Evergreen Park does not have the duty.to maintain the easement. Witness our hands and seals this day of , 19 Premier Custom Builder, Inc. Shawn Archer, President STATE OF COLORADO) ) SS COUNTY OF LARIMER) The foregoing instrument was acknowledged before me this day of 19 , by Premier Custom Builder, Inc. Shawn Archer, President Witness my hand and official seal. Notary Public My Commission Expires: ATTORNEY'S CERTIFICATE This is to certify that on the day of , AD 19 , I examined the title to the property hereon described and established that the owners and proprietors of record of said property as construed in C.R.S. 1973, 31-23-111, are as shown hereon as of said date. Signature: Address: Registration No. EASEMENT DEDICATION KNOW ALL MEN BY THESE PRESENTS: That the undersigned being the owner of record of' Lots 3, Block 5, Replat (No. 1) of Evergreen Park, City of Fort Collins, County of Larimer, State of Colorado, as recorded in Larimer County records at Book 1157, Page 0128, Reception Number 85405, do hereby dedicate and convey to the Owner of Record of Lot 2, Block 5, Replat (No. 1) of Evergreen Park for their use forever hereafter as a Slope Easement described as follows: Beginning at the northwest corner of Lot 3, Block 5, Replat (No. 1) of Evergreen Park, and being' the TRUE POINT OF BEGINNING of this description; Thence continuing North 90°00'00" East, 383.00 feet; Thence South 00°00'00" West 5.00 feet; Thence South 90°00'00" West 393.00 feet to the west property line of said lot 3; Thence continuing along the west property line of said Lot 3, North 0000100" West 5.00 feet to the TRUE POINT OF BEGINNING. Refer to Exhibit C attached hereto and by this reference made a part hereof Said easement contains 1,915 square feet, more or less. F'UIN I - tiLUINNINU FOP. 'AGE ESMT\ TRUE P0114 BEGINNING FOR DRAINAGE ESMT 0 ^II w >_ w J ry U n j W o0 () o 0 O Ln � O o � z cf) t. W J m 0- S00'00'00"E —16.00' 16' EXIST UTIL & DRAIN ESMT N90'00'00"E 283.00' PROPOSED 9' DRAINAGE ESMT N90'00'00"W 283.00' N%�2,547.00 S.F. 0.0585 AC. LOT 1, BLOCK 5 N90'00'00"E S90'00'00"W 289.77' LOT 2, BLOCK 5 N90'00'00''E TRUE POINT OF BEGINNING FOR ACCESS, DRAINAGE & UTILITY ESMT. 383.00' N90'00'00"E 100.00' / wo � 00 0 0 0i 0 O 0 0 0 Ln z 5,770.53 S.F. 1.0737 AC.'/ a L=3.01 /Tan=1.51 N / o Delta=08'37'37" ^%� 0 Chord=/N04'18'4E 0 co z R=20.OG L=31.42 Tan = 20.00 Del t a=90'00 ;00' Chord = N45'42 EVERGREEN PARK A PORTION OF SECTIONS 1 AND 12 T. 7 N., R. 69 W. OF THE 6TH P.M. CITY OF FORT COLLINS, COUNTY OF LARIIdER, STATE OF COLORADO z a F� X/ w /A ti 3 0 0 0 0 O J A DEDICATION OF ACCESS, DRAINAGE AND UTILITY EASEMENT AND DEDICATION OF DRAINAGE EASEMENT EXHIBIT A N EXHIBIT A ACCESS, DRAINAGE, AND UTILITY EASEMENT DESCRIPTION Beginning at the southwest corner of Lot 2, Block 5, Replat (No. 1) of Evergreen Park, and being the TRUE POINT OF BEGINNING of this description; Thence continuing along the west property line of said Lot 2, North 0°00'00" West, 23.50 feet; thence leaving said west property line and continuing North 90°00'00" East, 270.00 feet; Thence 31.42 feet along the arc of a curve to the left having a central angle of 90°00'00", a radius of 20.00 feet, a long. chord which bears North 45°42'26" East a distance of 28.64 feet; Thence North 00°00'00" West 48.72 feet; Thence 3.01 feet along the arc of a curve to the left having a central angle of 8°37'37", a radius of 20.00 feet, a long chord which bears North 04' 18'48" West a distance of 3.01 feet; Thence South 90°00'00" West 289.77 feet; Thence North 0°00'00" West, 58.00 feet; thence North 90°00'00" East, 283.00 feet; Thence North 0°00'00" West, 88.00 feet; thence North 90°00'00" East, 100.00 feet; Thence South 0°00'00" West, 241.22 feet; thence South 90°00'00" West, 383.00 feet to the TRUE POINT OF BEGINNING. Refer to Exhibit A attached hereto and by this reference made a part hereof, Said easement contains 46,770 square feet, more or less. DRAINAGE EASEMENT DESCRIPTION Beginning at the northwest corner of Lot 2 Block 5, Replat (No. 1) of Evergreen Park, and being the POINT OF BEGINNING of this description; Thence continuing South 00°00'00" East, 16.00 feet to the TRUE POINT OF BEGINNING; Thence North 90°00'00" East 283.00 feet; Thence South 00°00'00" West 9.00 feet; Thence North 90°00'00" West 283.00 feet; Thence North 00000'00" West 9.00 feet to the TRUE POINT OF BEGINNING. Refer to Exhibit A attached hereto and by this reference made a part hereof, Said easement contains 2,547 square feet, more or less. ATTORNEY'S CERTIFICATE This is to certify that on the day of , AD 19 , I examined the title to the property hereon described and established that the owners and proprietors of record of said property as construed in C.R.S. 1973, 31-23-111, are as shown hereon as of said date. Signature: Address: Registration No. EASEMENT DEDICATION KNOW ALL MEN BY THESE PRESENTS: That the undersigned being the owner of record of Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park, City of Fort Collins, County of Larimer, State of Colorado, as recorded in Larimer County records at Book" 1157, Page 0128, Reception Number 85405, in consideration of ten dollars ($10.00) in hand paid receipt of which is hereby acknowledged, and other good and valuable consideration, does hereby dedicate, transfer and convey to the City of Fort Collins, Colorado, a Municipal Corporation, for public use forever hereafter a permanent easement for Access, Drainage and Utilities and for Drainage in the City of Fort Collins, County of Larimer, State of Colorado, more particularly described on Exhibit "A" attached hereto and by this reference made a part hereof. It is understood by the undersigned that, by acceptance of this dedication, the City of Fort Collins does not have the duty to maintain the easement. Witness our hands and seals this day of , 19 Owner of record of Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park STATE OF COLORADO) ) SS COUNTY OF LARIMER) The foregoing instrument was acknowledged before me this day of 19 , by Owner of record of Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park Witness my hand and official seal. Notary Public My Commission Expires: Accepted by the City of Fort Collins on the day of , 199 City Clerk of the City of Fort Collins APPENDIX V Stuffer Envelope ❑ Grading, Drainage and Erosion Control Plan ❑ Easement dedication exhibit for Lots 1 and 2, Block 5 ❑ Sheet 3 of 9 Final Utility plans for Major Storm Drainage Way for Evergreen Park; Engineering Professionals; EPI Project No: 97-1; plans dated March, 1981 ❑ Floodplain Exhibit IPA, li4T' C'l to Ct) r7 easterly to Pond 5 (conceptual). The detention volume required for the basin, in order to meet the prescribed release rate, was estimated to be 6.4 acre-feet. Basin SA. The basin was assumed to be completely developed for commercial use with an estimated imperviousness of 90 percent. On -site detention is required for this basin. The allowable release from this basin is 5 cfs, or 0.40 cfs/acre. The designated release point for Basin 5A is Pond 5; this pond will release flows to Dry Creek. The detention volume required for the basin, in order to meet the prescribed release rate, was estimated to be 2.3 acre-feet. Basin 5B. The basin was assumed to be completely developed for commercial use with an estimated imperviousness of 90 percent. On -site detention is required for this basin. The allowable release from this basin is 11 cfs, or 0.36 cfs/acre. The designated release point for Basin 5B is Dry Creek at the southeast comer of the basin. The detention volume required for the basin, in order to meet the prescribed release rate, was estimated to be 5.6 acre-feet, Basin 6. The basin was assumed. to be primarily developed for commercial use (79 percent), with 8 percent devoted to medium density residential housing. The remaining 13 percent was assumed to be open space associated with emstuag wetland, which is functioning as a detention pond (Pond 6). It is noted that 13 percent is probably a: conservatively low estimate of the wetland area within this basin. The resulting average imperviousness is 75 percent. On -site detention is not required for this basin; however the integrity of the downstream storm drainage system requires that "Pond 6" continue to operateaxs a detention pond. In fact, this Master Plan specifies that Pond 6 act as a regional detention pond, receiving on -site detention releases from Basins 7A, 7B and 9. . Assuming that the pond will receive releases from these three basins as well as runoff - from from Basin 6, the existing pond and outlet will limit the developed condition 100-year release to 13.8 efs. The detention volume required for the basin, based on the current release rate of 13.8 cfs, was estimated to be 15.5 acre-feet. It is imperative that this pond release rate be maintained due to the capacity of downstream conveyance and detention facilities. The designated release point for Basin 6 is the upstream end of the Blue Spruce Drive roadside channel/culvert system which conveys flow to the Evergreen West Pond. Basin 7A. The basin was assumed to be fully developed with medium and low density residential housing at 32 and 68 percent, respectively. Consequently, the estimated imperviousness is 42 percent. On -site detention is required for this basin, with releases routed through Pond 6 for additional attenuation of the ,flood peak. The allowable release from this basin is 12 cfs, or 0,51 cfs/acre. The designated release point for Basin 7A is a conceptual drainage channel/ pipe system through Basin 7B which will convey flows to Pond 6. The detention volume required for the basin, in order to meet the prescribed release rate, was estimated to be 3.7 acre-feet. Basin 7B. The basin was assumed to be fully developed with a combination of commercial, and low and medium residential housing. The resulting imperviousness was 20 MAR-21-97 FRI 13:02 Basin 1F. The basin is part of Greenbriar Village PUD, Second and Fourth Filings. Consequently, the basin was assumed to be fully developed with medium residential land use. An imperviousness of 40 percent was assumed. Runoff will concentrate along the west side of Redwood Street near the end of Fox Glove Court; it will then be conveyed under Redwood Street in a proposed pipe system designed to carry 100-year flows. Therefore, on -site detention is not required for this basin, as all storm rwwff will be conveyed under Redwood street to the proposed Greenbriar Wetland Pond. Basin 1G. The basin is part of the Greenbriar Village PUD, Third Filing; therefore, it was assumed to be 40 percent impervious. Runoff from the basin will be conveyed directly (undetained) to the outfall pipe for the Greenbriar Wetland Pond, thereby being routed directly to the Redwood Pond. The Greenbriar Wetland Pond has been configured to over -detain such that undetained runoff from Basin 1G will not result in an adverse impact to the Redwood Pond. Consequently, on -site detention is not required for this basin. Basin 2. The basin was assumed to be developed with commercial, and both high and low density residential housing to 5, 35 and 60 percent levels, respectively; the result being an average imperviousness of about 50 percent. On -site detention is not required for this basin; storm runoff will be conveyed to the existing Redwood Pond. Outflow discharges from this pond will enter the proposed outlet channel which .will' carry flows easterly to Lemay Avenue while picldng up runoff from Basin OB and outflows from the Evergreen East Pond near the east end of the channel. Basin 3A. The basin was assumed to be completely developed for commercial use with an estimated imperviousness of 90 percent. On -site detention is not required for this basin; storm runoff`' will be transported to the existing inlet channel for the Evergreen West Pond. WThe basin was assumed to be developed for 37 percent commercial use, and 63 percent residential housing at levels representing 11, 49 and 3 percent of the entire basin for high, medium and low densities, respectively. The result is a developed imperviousness of 63 percent. On -site detention is not be required for this basing storm twill be transp_orted_to the existin8_E_v_ergr_eezt-West_Eand- Outflow from this pond Will enter the existing outlet channel which will transport flow southerly to Pond 5 (conceptual). Basin 4D. By definition, the basin is currently fully developed for commercial use; the amount of impervious area for the basin was determined to be 97 percent. eDue to the fully -developed condition of this portion of Basin 4, on -site detention is not fasi Storm runoff will be conveyed to Pond 5 (conceptual). Basin 4U. The basin was assumed to be completely developed for commercial use with an estimated imperviousness of 90 percent. On -site detention is required oror this in. The allowable release from this basin is 17 c s or 0.47 cfs/acre. The designated release ,,,,;.,► fir Basin 4U is the storm sewer and street along Conifer Street which convey flows 19 J Table 5.3. Summary of Hydraulic Analysis and Design Information for the Existing Conveyance Facilities Which Require Mou,iications or Improvements, and the Conveyance Facilities Which Have Been Designed but Not Constructed. Element Descri lion Bottom Width o of Side Slo Invert Slops '; Manning's n 100 Year ,:Discharge' Flow D th Flow Velocity Comments Number P Dametat (n)::: ZZH:,1� (ft/!t) cfs ( ) . t 06 f ps) : West Area Basins 7A and 7B Outlet 36" RCP. n/a 0.0040 0.013 28 - - Pipe full capacity = 42 cfs P1 Pipe to Pond 6 P2 Evergreen West Pond 30 ft 4 0.0025 0.060 (Node0252) 1.5 1.5 Freeboard provided = 1.0 ft. Inlet Channel Evergreen West Pond 7 ft 4 0.0019 0.060 24 1.6 1.1 Freeboard provided = 2.5 ft (min.) P3 Outlet Channel P4 Conifer Street Channel 7 ft 4 0.0025 0.035 (Nod0i32) 3.2 3.2 Freeboard provided = 3.8 ft . .::Norlheast;Arra. PVE-B Perimeter 0 ft 4 0.0068 0.060 16 1.5 1.7 Freeboard provided = 0.5 h (min.) P5 Channel, East Reach (A) PVE-B Perimeter 25 ft 4 0.0043 0.035 445 2.8 4.6 Freeboard provided,= 0.7 ft (min.) P6 Channel, East Reach (B) . PVE-B Perimeter 0 ft 4 0.0080 0.060 8 1.2 1.5 Freeboard provided = 0.8 ft (min.) P7 Channel, West Reach PVW-B Perimeter 0 ft 4 0.0070 0.060 17 1.6 1.7 Freeboard provided = 0.8 ft (min.) P8 Channel, East Reach East Pipe Crossing of Latimer and Weld Canal in le 42" &Cps n/a 0.0067 0.013 445 - - Available driving head 9.5 ft (see Appendix F.2) West Pipe Crossing of single 42" n/a 0.0063 0.013 111 -- _ Available driving head . 12.8 ft (see Appendix F.2) P 10 L.arimer and Weld Canal RCP SoutheastArea. PitGreenbrier Wetland Pond 15' RCP n/a 0.0033 0.013 4 -- -- Pipe full capacity = 4 cfs Outlet Pipe Redwood Pond Outlet 5 ft 4 0.0025 0.060 17 1.4 1.2 Freeboard provided = 1.6 ft (min.) P12 Channel P13 Evergreen East Pond 3 ft 1 0.0025 0.016 49 2.0 5.1 Freeboard provided = 1.1 ft Outlet Channel (concrete) P14 Greenbriar Outfall 12 ft 4 0.0020 0.060 64 (Node 269) 2.2 1.4 Freeboard provided = 0.3 ft Channel, North Reach P15 Greenbriar Outfall 16 ft 4 0.0020 0.060 77 (Nock 270) 2.1 1.5 Freeboard provided = 0.4 ft Channel, South Reach. • Refer to Appendix F for explanation of design discharges. -Z7Ve r('c'/' rl 'a,5'1i f 1G>/i �l 14' %2ki-'t" Table 4.2. Summary of Results for Regional Detention Ponds for the Developed Condition Hydrologic Analysis. Pond 6 Contributing Basu+(s) Allowable Release,.ReleaseStorage Rate (cfs) Actual. Rate"' (cfs) LReq Actual_ Capacity" (ac-CQ Maximum Permissible :WSEL° (R, msl) Actual 100-Year WSEL (11, msl) Direct° Indirectb West Area G 7A, 7B, 9 17` 14 15.5 24.0 4975.5 4974.4 Greenbriar East II GBE ( CV, GBOE, PVE-A, PVE-B, II PVW-A PVW-B 30h I 16 II 7.9 J I 8.1 II 4962.0 I 4961.9 Southeast. Area... Greenbriar Park IC, lE none 4' 2.2 3.4 3.8 4965.6 4965.5 Greenbriar Welland IA, I B, ID, 1 F IC, I E 271 4.7 7.2 7.2 4964.0 4964.0 Redwood IG, 2 IA, 1 B, IC, ID, I E, IF 171 17 9.0 9.3 4959.0 4958.9 Evergreen East OA none 34' 19 8.0 8.3 4954.5 4954.4 Basins which contribute runoff directly into the pond without on -site or prior regional detention. b Basins whose runoff is detained prior to reaching the indicated pond. ` Runoff from Basin PVW-B is currently detained by the temporary Pheasant Ridge South Pond; this pond may be abandoned when the Greenbriar North Pond and the associated conveyance facilities across the I-arimer and Weld Canal are constructed. d Also known as the Redwing Marsh Natural Area. ` Total 2-year runoff from existing Basin 6. t Total 2-year runoff from existing Basins 3A, 3B and 6. C Total 2-year runoff from existing Basins 3A, 3B, 6, 41), 4U and 5. h Discharge based on the capacity of the northern segment of the Greenbriar Oulfall Pipe. ' Total 2-year runoff from existing Basin IC. Total2-yearrunoff from existing Basins IA, IB, IC and 1D. t Total 2-year runoff from existing Basin 2. t Total 2-year runoff from existing Basin OA. '" This Master Plan recognizes the actual release rate listed as the "adopted" allowable release rate duet'No system interdependence, potential adverse impacts downstream if the actual release rate is not met, anti�capacity constraints of existing drainage facilities. " Active capacity after proposed improvements; not including the requited freeboard. ° Maximum water surface elevation al the 1-Ct freeboard level; proposed minimum bank elevation is 1.0 ft higher. I g. FINAL REPORT GREENBRIAR-EVERGREEN BASIN MASTER DRAINAGE PLAN PREPARED FOR: City of Fort Collins Stormwater Utility 235 Mathews Fort Collins, CO 80524 PREPARED BY: Lidstone & Anderson, Inc. 736 Whalers Way, Suite F 200 Fort Collins, CO 80525 (LA Project No. COTST05.4) May 1, 1996 APPENDIX IV Greenbriar-Evergreen Basin Master Drainage Plan; Lidstone & Anderson, Inc.; Project No COTST05.4; dated May, 1996 TABLE 4 CIRCULAR PIPE. FLOW CAPACITY Full Flow (cubic feet Per second) Mannings "n"= 0.012 Dia. *Cony. % Slope (feet per 100 feet) (in.) Factor 0.02 0.05 0.10 0.20 0.35 0.50 0.75 1.00 1.25 1.50 1.75. * 2.0 2.5 5.0 10.0 20.0 (c.f.s.) 3 0.957 0.014 0.021 0.030 0.043 0.057 0.068 0.083 0.096 0.107 0.12 0.13 0.14 0.15 0.21 0.30 0.43 4 2.062 0.029 0.046 0.065 0.092 0.122 0.146 0.179 0.206 0.231 0.25 0.27 0.29 0.33 0.46 0.65 0.92 5 3.738 0.053 0.084 0.118 0.167 0.221 0.264 0.324 0.374 0.418 0.46 0.49 0.53 0.59 0.84 1.18 1.67 6 6.079 0.086 0.136 0.192 0.272 0.360 0.430 0.526 0.608 0.680 0.74 0.80 0.86 0.96 1.36 1.92 2.72 8 13.091 0.185 0.293 0.414 0.585 0.774 0.926 1.134 1.309 1.464 1.60 1.73 1.85 2.07 2.93 4.14 5.85 10 23.74 0.34 0.53 0.75 1.06 1.40 1.68 2.06 2.37 2.65 2.91 3.14 3.36 3.75 5.31 7.51 10.61 12 38.60 0.55 0.86 1.22 1.73 2.28 2.73 3.34 3.86 4.32 4.73 5.11 5.46 6.10 8.63 12.21 17.26 15 69.98 0.99 1.56 2.21 3.13 4.14 4.95 6.06 7.00 7.82 8.57 9.26 9.90 11.06 15.65 22.13 31.30 18 113.80 1.61 2.54 3.60 5.09 6.73 8.05 9.86 11.38 12.72 13.94 15.05 .16.09 17.99- 25.45 35.99 50.89 21 171.65 2.43 3.84 5.43 7.68 10.16 12.14 14.87 17.17 19.19 21.02 22.71 24.28 27.14 38.38 54.28 76.77 24 245.08 3.47 5.48 7.75 10.96 14.50 17.33 21.22 24.51 27.40 30.02 32.42 34.66 38.75 54.80 77.50 109.60 27 335.51 .4.74 7.50 10.61 15.00 19.85 23.72 29.06 33.55 37.51 41.09 44.38 47.45 53.05 75.0 106.1 160.0 30 444.35 6.28 9.94 14.05 19.87 26.29 31.42 38.48 44.44 49.68 54.42 58.78 62.84 70.26 99.4 140.5 198.7 36, 722.57 10.22 16.16 22.85 32.31 42.75 51.09 62.58 72.26 80.79 88.50 95.59 102.19 114.25 161.6 228.5 323.1 42 1089.9 15.41 24.37 34.47 48.74 64.5 77.1 94.4 109.0 121.9 133.5 144.2 154.1 172.3 243.7 344.7 487.4 48 1556.1 22.01 34.80 49.21 69.59 92.1 .110.0 134.8 155.6 174.0 190.6 205.9 220.1 246.0 348.0 492.1 695.9 * Conveyance Factor = (1.486 x R2/3 x A) / n rf 3.1.7 Time of Concentration In order to use the Rainfall Intensity Duration Curve, the time of concentration must be known. This can be determined either by the following equation or the "Overland Time of Flow Curves" from the Urban Storm Drainage Criteria Manual, included in this report (See Figure 3-2). Tc =1.87 (1.1 — CC,) D 1/2 S"' Where Tc =Time of Concentration, minutes S = Slope of Basin, C = Rational Method Runoff Coefficient D = Length of Basin, feet Ct = Frequency Adjustment Factor Time of concentration calculations should reflect channel and storm sewer velocities as well as overland flow times. 3.1.8 Adjustment for Infrequent Storms The preceding variables are based on the initial storm; that is, the two to ten year storms. For storms with higher intensities an adjustment of the runoff coefficient is required because of the lessening amount of infiltration, depression retention, and other losses that have a proportionally smaller effect on storm runoff. These frequency adjustment factors are found in Table 3-4. Table 3-4 RATIONAL METHOD FREQUENCY ADJUSTMENT FACTORS Storm Return Period (years) 2lo 10 11 to 25 26 to 50 51 to 100 3.2 Analysis Methodology Frequency Factor C, 1.00 1.10 1.20 1.25 Note: The product of C times C, shall not exceed 1.00 The methods presented in this section will be instituted for use in the determination and/or verification of runoff at specific design points in the drainage system. These methods are (1), the Rational Method and (2) the Colorado Urban Hydrograph Procedure (CUHP). Other computer methods, such as SWMM, STORM, and HEC-1 are allowable if results are not radically different than these two. Where applicable, drainage systems proposed for construction should provide the minimum protection as determined by the methodology so mentioned above. 3.2.1 Rational Method For drainage basins of 200 acres or less, the runoff may be calculated by the Rational Method, which is essentially the following equation: Q = C,CIA Where Q = Flow Quantity, cfs A =Total Area of Basin, acres C, = Storm Frequency Adjustment Factor (See Section 3.1.8) C = Runoff Coefficient (See Section 3.1.6) I = Rainfall Intensity, inches per hour (See Section 3.1.4) 3.2.2 Colorado Urban Hydrograph Procedure For basins larger than 200 acres, the design storm runoff should be analyzed by deriving synthetic unit hydrographs. It is recommended that the Colorado Urban Hydrograph Procedure be used for such ana!ysis. This procedure is detailed in the Urban Storm Drainage Criteria Manual, Volume 1, Section 4. MAY 1984 3-5 DESIGN CRITERIA R-M-P Medium Density Planned Residential District — designation for medium density areas planned as a unit (PUD) to provide a variation in use and building placements with a minimum lot area of 6,000 square feet. R-L-M Low Density Multiple Family District — areas containing low density multiple family units or any other use in the R-L District with a minimum lot area of 6,000 square feet for one -family or two-family dwellings and•9,000 square feet for multiple -family dwellings. M-L Low Density Mobile Home District — designation for areas for mobile home parks containing independent mobile homes not exceeding 6 units per acre. M-M Medium Density Mobile Home District — designation for areas of mobile home parks containing independent mobile homes not exceeding 12 units per acre. B-G General Business District — district designation for downtown business areas, including a variety of permitted uses, with minimum lot areas equal to 112 of the total floor area of the building. B-P Planned Business District — designates areas planned as unit developments to provide business services while protecting the surrounding residential areas with minumum lot areas the same as R-M. H-B Highway Business District — designates an area of automobile -orientated busi- nesses with a minimum lot area equal to 112 of the total floor area of the building. B-L Limited. Business District — designates areas for neighborhood convenience centers, including a variety of community uses with minimum lot areas equal to two times the total floor area of the building. C Commercial District —designates areas of commercial, service and storage areas. I-L Limited Industrial District —designates areas of light industrial uses with a minimum area of lot equal to two, times the total floor area of the building not to be less than 20,000 square feet. I-P Industrial Park District —designates light industrial park areas containing controlled industrial uses with minimum lot areas equal to two times the total floor area of the building not to be less than 20,000 square feet. I-G General Industrial District — designates areas of major industrial development. T Transition District — designates areas which are in a transitional stage with regard to ultimate development. For current and more explicit definitions of land uses and zoning classifications, refer to the Code of the City of Fort Collins, Chapters 99 and 118. Table 3-3 RATIONAL METHOD RUNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS Character of Surface Runoff Coefficient Streets, Parking Lots, Drives: Asphalt................................................................................................ 0.95 95 Concrete............................................................................................. 0. Gravel................................................................................................. 0.50 Roofs.......................................................................................................... 0.95 Lawns, Sandy Soil: Flat<2%............................................................................................. 0.15 Average2 to 7%.................................................................................. 0. 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 No Text SECTION 3. HYDROLOGY STANDARDS 3.1 General Design Storms All drainage systems have to take into consideration two separate and usualldistinct drainage problems. The strst is the orm, dependito ten-year ng on and use. The runoff frostorm which occurs at m this type of storm regular intervals, isconsidered the " uased on esanoce flow". The second is the major storm which is usually based on an infrequent storm, such as the 100-year storm. In some instances the major storm routing will not be the same as the initial storm. In this case, a complete set of drainage pians shall be submitted for each storm system. 3.1.1 Initial Storm Provisions As stated before, the initial storm shall be based on the two to ten year storm. The objectives of such drainage system planning are to minimize inconvenience, to protect against recur- ring minor damage and to reduce maintenance costs in order to create an orderly drainage system at a reasonable cost for the urban resident. The initial storm drainage system may in- clude such facilities as curb and gutter, storm sewer and open drainageways, and detention facilities. 3.1.2 Major Storm Provisions The major storm shall be considered the 100-year storm. The objectives of the major storm planning are to eliminate substantial property damage or loss of life. Major drainage systems may include storm sewers, open drainageways, and detention facilities. The correlation between the initial and major storm system shall be analyzed to insure a well coordinated drainage system. 3.1.3 Storm Frequency The initial and major storm design frequencies shall not be less than those found in the fol lowing table: Table 3-1 DESIGN STORM FREQUENCIES Design storm Return Period Initial Storm Major Storm Land Use or Zoning t Residential: (RE, RL, RLP, RP, ML, RM, RMP, RLM, MM, RH)...................................................................... 2 year 100 year Business: 10-year 100-year (BG, BL, BP, HB, C. IL, IP, IG).............................................. 10-year I00-year Public Building Areas.................................. ............................. 2-year 100-year Parks. Greenbelts, etc.............................................................. 100-year Open Channels & Drainageways............................................. — 100-year Detention Facilities................................................................... — See Table 3.2 for zoning definitions. 3.1.4 Rainfall Intensities The rainfall intensities to be used in the computation of runoff shall be obtained from the Rainfall Intensity Duration Curves for the City of Fort Collins, included in these specifications as Figure 3.1. 3.1.5 Runoff Computations Storm Runoff computations for both the initial and major storm shall comply with the criteria de in the design of set forth in Section 3.2 "Analysis Methodology." All runoff calculations ma both initial and major drainage systems shall be included with the storm drainage plans in the form of a Drainage Report. Reports submitted for approval should have a typed narrative with computations and maps in a legible form. 3-1 MAY 1984 DESIGN CRITERIA APPENDIX III Backup Diagrams and Exhibits Table 3-3; Rational Method Runoff Coefficients for Composite Analysis Table 3-4; Rational Method Frequency Adjustment Factors Figure 3-2; Estimate of Average Flow Velocity for Use with the Rational Formula Figure 3-1; City of Ft. Collins Rainfall Intensity Duration Curve Table 4 - Circular Pipe Flow Capacity SHEAR June 24, 1998 Project No: 1466-14-96 Re: EROSION CONTROL SECURITY DEPOSIT REQUIREMENTS: Lots 1 & 2, Block 2, Replat (No. 1) of Evergreen Park; Fort Collins, Colorado A. An erosion control security deposit is required in accordance with City of Fort Collins policy (Chapter 7, Section C: SECURITY; page 7.23 of the City of Fort Collins Development Manual). In no instance shall the amount of the security be less than $1000.00. 1. According to current City of Fort Collins policy, the erosion control security deposit is figured based on the larger amount of 1.5 times the estimated cost of installing the approved erosion control measures or 1.5 times the cost to re -vegetate the anticipated area to be disturbed by construction activity. a. The cost to install the proposed erosion control measures is approximately $ 2,475.00 Refer to the cost estimate attached in Appendix I. 1.5 times the cost to install the erosion control measures is $ 3,712.50 b. Based on current data provided by the City of Fort Collins Stormwater Utility, and based on an actual anticipated net affected area which will be disturbed by construction activity (approximately 2.12 acres), we estimate that the cost to re - vegetate the disturbed area will be $ 1,126.21 ($ 531.00 per acre x 2.12 acres). 1.5 times the cost to re -vegetate the disturbed area is $ 1,689.31. The $ 531.00 per acre for re -seeding sites of less than 5 acres was quoted to us by the City of Fort Collins Stormwater Utility staff. CONCLUSION: The erosion control security deposit amount required for Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park will be $ 3,712.50 4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-0311 June 24, 1998 QENGINEERING Project No: 1466-14-96 Basil Hamdan City of Fort Collins Stormwater Utility P.O. Box 580 Ft. Collins, Colorado 80522 Re: Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park; Fort Collins, Colorado Dear Basil, Attached is the erosion control security deposit estimate for Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park. ESTIMATE 1: 600 LF of Silt Fence Q $ 3.00 per LF $ 1,800.00 1 - Gravel Inlet Filter @ $ 75.00 each $ 75.00 4 - Haybales in channel © $ 150.00 each $ 600.00 TOTAL ESTIMATED COST: $ 2,475.00 x 1.50 $ 3,712.50 ESTIMATE 2: re -vegetate the disturbed area of 2.12 acres at $ 531.00 per acre $ 1,126.21 TOTAL ESTIMATED COST: $ 1,126.21 x 1.50 $ 1,689.31 In no instance shall the amount of the security be less than $ 1,000.00. Therefore, the total required erosion control security deposit for Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park will be $ 3,712.50 If you have any questions, please feel free to contact me at 226-5334. Sincerely, c\,' Mark Oberschmidt Shear Engineering Corporation MEO / meo cc: Premier Custom Homes Jean Paquette, City of Fort Collins Stormwater Utility 4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-031 1 RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: LOT 1 & 2 EVERGREEN PARK STANDARD FORM A COMPLETED BY: MARK OBERSCHMIDT DATE: 03/25/97 txrrrrrtttxx x+♦++r rrrx xtt xxxrrx+rtr rr trxxr+rrtxtxrrtxxr+r+ttrr xttx+rrrxrxtxx+r+xrr++++xr tx DEVELOPED ERODIBILITY Aab Lob Sob Lb Sb PS SUBBASIN ZONE (ac) (Et) (t) (feat) (4) M xxrxtxxrr+rrtrtxxettxr:rrrrtrtxrxtxrrrtrrxxxxrx+trrtxxrrrtttxttrxxxxrttrxtxtxxtxtrxrxtxr xe Iw MODERATE 0.92 120.00 0.50 110 0.46 Ie MODERATE 1.40 260.00 0.50 364 0.70 tx xrrxrttrxxxtxxrrr+rttxx xtxxrrrttxrxxxx+xxrttrrxxxxt xxxxrttrxxrxxx txrrr LINEAR INTERPOLATION SLOPE 2.32 204.48 0.50 LENGTH 0.50 200 72 204.48 72.02 -• 300 72.4 CONCLUDE:PERFORMANCE STANDARD = 72.02U EROSION CONTROL PLAN OVERALL EFFECTIVENESS MUST EXCEED THIS EFFECTIVENESS CALCULATIONS • STANDARD FORM B PROJECT: LOT 1 & 2 EVERGREEN PARK PROJ. NO.1466-14-96 BY: MARK OBERSCHMIDT DATE 03/25/97 ------------------------------------------------------------------------------------------ EROSION CONTROL C-FACTOR P-FACTOR COMMENT METHOD VALUE VALUE ------------------------------------------------------------------------------------------ ROUGHENED GROUND 1.00 0.9 ROOF AREAS SILT PENCE 1.00 0.5 SUB -BASINS Ie ONLY ASPHALT 0.01 1.0 BOTH SUB -BASINS SOD 0.01 1.0 BOTH SUB -BASINS GRAVEL INLET FILTERS 1.00 0.8 SUB -BASIN Iw ONLY ------------------------------------------------------------------------------------------ MAJOR PS SUB AREA CALCULATIONS BASIN 6 BASIN acre AREA' C P ------------------------------------------------------------------------------------------ ALL 72.02%Ae 1.20 ROOF 0.14 ACRES 1.00 0.90 SOD 0.48 ACRES 0.01 1.00 EQUATIONS ASPHALT 0.5E ACRES 0.01 1.00 C - WEIGHTED AVG OF C X AREA P= (WEIGHTED AVG OF P X AREA) X P C= 0.1255 EFF - (1 - P X C) X 100 P = 0.4942 EFF 93.80% ------------------------------------------------------------------------------------------ Aw 0.92 ROOF 0.20 ACRES 1.00 0.90 SOD 0.31 ACRES 0.01 1.00 ASPHALT 0.41 ACRES 0.01 1.00 C = 0.2252 P = 0.7826 EFF 82.37% i tfft♦tf if♦ii if iif it iii ie iifiiiit irr iirtxrrtxxxr+rr+tttifiiff ii irtx+t+fffftf iff ttf iftrf if if rr TOTAL AREA = 2.12 ACRES OVERALL EFFECTIVENESS = 88.84% > 72.021, CONCLUDE:EROSION CONTROL PLAN IS EFFECTIVE U99:10I1]0.101 Erosion Control Calculations Erosion Control Sequencing schedule Erosion Control security deposit estimates Cross Section C-C FOR Q = 80 CFS Cross Section for Irregular Channel Project Description Project File c:\haestad\fmw\premier.fm2 Worksheet Cross Section C-C Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Section Data Wtd. Mannings Coefficient 0.060 Channel Slope 0.003700 fttft Water Surface Elevation 67.08 ft Discharge 80.00 cfs 70.5,-,------------- I -------_----------------- - ---------------- ------ I 1 I I 1 I I 1 I 1 I I I I I I I I I I 1 I I 1 I I I I I I I 1 70.0 ______1-------- I-------- 1__-----J-------- L-------- -------- L_______J I I I I 1 I I I 1 1 I I 1 I I I 1 I 1 I 1 1 1 1 1 1 1 I I 1 I 1 69.5 ------=----------------r---------------*---------------------------- 1 1 I I 1 1 I 1 I I 1 I I I 1 I 1 I I I I I 1 1 I I I I 1 1 I 69.0 -------------- '-------- 1-------- '-------- 1-------J---------------J 1 I I 1 I I 1 I 1 I I 1 I I 1 1 I I I I I I I I I I I I I I 68.5-------- _--____I______--T--______I__----__T-----_-1__ ______1 1 I I I 1 1 I I 1 1 I I I 1 I 1 y_ I I II I 1 I I 1 ___---_ -- _____I_ ------- 1-------- I-------- 1------ J-------- L_______J 1 1 1 1 () I 1 1 I 1 1 I I I 1 I 1 I I 1 1 I 1 1 I I W I I I I I I I I 1 I I 1 1 1 I I 1 1 67.0--_____J___----1________1_-- ____1__---__-L ______J______--L___-___J I 1 1 1 1 I I I 1 I 1 1 1 1 I I I I 1 _ I I I I 1 1 I 66.5-------=------- I--------T-------------- T--------;--------r-------- I I I I 1 1 I I I I I I 1 1 I I 1 1 I I 1 I I I 1 1 1 1 1 I 1 66.0-__----1--______1_ ------ 1-------- I---- --- L------- J---_____L_______J I I 1 I I I I I 1 I 1 1 I 1 1 1 I I I 1 I 1 1 1 I I 1 1 I 1 I 1 65.5 I I 1-------I 1 I I I I 1 I I 1 I I I I I I 1 I 1 I 1 1 1 I 1 I 1 I I I I I 1 I 1 65.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Station (ft) 09/22/98 FlowMaster v5.13 09:33:49 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 CROSS SECTION C-C FOR Q == 80 CFS Worksheet for Irregular Channel Project Description Project File c:\haestad\fmw\premier.fm2 Worksheet Cross Section C-C Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Input Data Channel Slope 0.003700 ft/ft Elevation range: 65.10 ft to 70.45 ft. Station (ft) Elevation (ft) Start Station End Station Roughness 3.00 70.45 3.00 71.00 0.060 24.00 65.50 36.00 65.10 44.00 65.80 58.00 68.00 71.00 69.10 Discharge 80.00 cfs Results Wtd. Mannings Coefficient 0.060 Water Surface Elevation 67.08 ft Flow Area 45.06 ftz Wetted Perimeter 35.22 ft Top Width 34.89 ft Height 1.98 ft Critical Depth 66.15 ft Critical Slope 0.060008 ft/ft Velocity 1.78 ft/s Velocity Head 0.05 ft Specific Energy 67.13 ft Froude Number 0.28 Flow is subcritical. 09n2198 FlowMaster v5.13 09:33:43 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 Cross Section B-B FOR Q = 80 CFS Cross Section for Irregular Channel Project Description Project File c:\haestad\fmw\premier.fm2 Worksheet Cross Section B-B Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Section Data Wtd. Mannings Coefficient 0.060 Channel Slope 0.003700 ft/ft Water Surface Elevation 67.28 ft Discharge 80.00 cfs 71.0----------------I- ------- T-- ------ ---r------ ---------r------ 1 1 I I I I I I 1 1 1 I 1 I I I 1 1 1 1 1 1 1 I 70.5 ------�--- ' _- ---- --- ' _---- --� 1 I I I 1 I I 1 1 I 1 _-J-------- I-------- +-------I--------+-------J--------L-------J I 1 I I I 1 1 1 I 1 I I 1 1 1 1 I 1 I I 1 I 1 1 1 I I , I I I I I I I I I I 1 I I I I I I I 1 I 1 I I 1 69.0------- --------'-------- I '---------'--------1--------'------- 1 I I 1-,----- - I I I I I 1 I 1 I I I I 1 1 1 I 1 I I I I 1 1 I I I v I I I I I I I 68.0 ' -- - - - - - I ---!-------1 I C I I I 1 I I I 1 0 I I I 1 +-' 1 I 1 1 1 1 I I j67.5 -------1---- --- I--------L-------- --------L-- ---- J-------- L-------J I 1 1 1 I I I 1 1 I I LLB 1 I 1 = 1 I 1 I 1 I 1 I I 1 1 I 1 1 1 I 1 I I I I I I I 1 1 1 I 1 1 I 1 1 I 66.5 ' --------I ----I 1-------I I -------'f------- T---- I-------r--------1- r-- - - - - - I 1 I 1 1 I I I I I 1 1 I I I I I I 1 I 1 1 I I 66.0 - - - - - - - J - - - - - - - -I- - - - - - - L - - - - - - - -I - - - - - - - L - - - - - - - J - - - - - - - - L - - - - - - - J 1 I 1 1 I I 1 I 1 1 1 I 1 1 1 1 1 1 I I I 1 65.5-------y--------r------ I------- - ------- r--------------- r-------� I 1 I 1 I I 1 1 1 I 1 I I I I 1 1 1 1 1 I I 1 65.0 ----- I 1 _______T________i T____-_ 1_-___-_-T-___-----_---___r_______- I I I I 1 I 1 I I I 1 I 1 1 I 1 I 1 I I 1 I I 1 64.5 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Station (ft) 09/22/98 FlowMaster v5.13 09:32:23 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 SECTION B-B FOR Q = 80 CFS Worksheet for Irregular Channel Project Description Project File c:\haestad\fmw\premier.fm2 Worksheet Cross Section B-B Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Input Data Channel Slope 0.003700 ft/ft Elevation range: 64.90 ft to 70.80 ft. Station (ft) Elevation (ft) Start Station End Station Roughness 3.00 70.80 3.00 79.00 0.060 23.00 65.70 35.00 65.30 39.00 64.90 40.50 65.95 58.50 68.05 79.00 69.10 Discharge 80.00 cfs Results Wtd. Mannings Coefficient 0.060 Water Surface Elevation 67.28 ft Flow Area 45.32 ft2 Wetted Perimeter 35.72 ft Top Width 35.09 ft Height 2.38 ft Critical Depth 66.28 ft Critical Slope 0.059812 ft/ft Velocity 1.77 ft/s Velocity Head 0.05 ft Specific Energy 67.33 ft Froude Number 0.27 Flow is subcritical. 09/22/98 FlowMaster v5.13 09:32:18 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 Section A -A FOR Q = 80 CFS Worksheet for Irregular Channel Project Description Project File c:\haestad\fmw\premier.fm2 Worksheet Cross Section A -A Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Input Data Channel Slope 0.003700 ft/ft Elevation range: 65.70 ft to 71.05 ft. Station (ft) Elevation (ft) Start Station End Station Roughness 3.00 70.90 3.00 77.00 0.060 23.00 66.00 35.00 65.70 48.00 66.00 60.00 69.05 69.00 70.25 77.00 71.05 Discharge 80.00 cfs Results Wtd. Mannings Coefficient 0.060 Water Surface Elevation 67.37 ft Flow Area 45.63 ftz Wetted Perimeter 36.35 ft Top Width 36.01 ft Height 1.67 ft Critical Depth 66.52 ft Critical Slope 0.062056 ft/ft Velocity 1.75 ft/s Velocity Head 0.05 ft Specific Energy 67.42 ft Froude Number 0.27 Flow is subcritical. 09/22/98 FlowMaster v5.13 09:28:20 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 Cross Section A -A FOR Q = 80.0 CFS Cross Section for Irregular Channel Project Description Project File c:\haestad\fmw\premier.fm2 Worksheet . Cross Section A -A Flow Element Irregular Channel Method Manning's Formula Solve For Water Elevation Section Data Wtd. Mannings Coefficient 0.060 Channel Slope 0.003700 ft/ft Water Surface Elevation 67.37 ft Discharge 80.00 cfs 71.5----------------- 1-------- r-------- 1-------- r------- -------- r------- 1 1 1 1 I 1 I I 1 I I I 1 1 I 1 1 1 I I I 1 I I I I I 1 1 I I 1 1 I I I I 1 I 1 1 I 1 I 1 1 I I I 1 I I I I 1 I I I-------1 I I 1 I I I 1 I I 1 1 1 1 I I I I I I I I 1 1 I 1 1 I I I 1 I I 1 I I I I I I 1 I 1 1 I I 1 1 I 1 1 1 I I 1 1 1 1-------1 I I I I ----1 I I I I I I I I I 1 1 1 1 1 1 1 1 I 1 1 I I I I 1 I I 1 C 1 1 1 I I 1 I I O 68.5-------+ -- ----- ----- - -+--------I--------+- - - --- -+--------L--- - - - - a. > I I 1 I 1 1 I 1 I 1 1 1 I I 1 W 68.0 ___--__--- ---- L------- 1------_-I-------- L---- __J-------- L------- J I I I I I 1 I I 1 I I I 1 I I I I I 1 1 I I I I 1 1 1 1 1 I 1 1 67.5-------1-------1------- I --------I-------- L------ 1-------- L------- J 77 I I I 1 1 1 = I 1 I I 1 I I I I 1 I 1 I 1 1 1 1 I I I I 67.0 ____--_1------- L_______1______--1--------L_ _____J_-------L-------J I 1 1 1 I 1 I 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 I I I I I 66.5 --------- _______1-------- I-------- ------- J-------- L------- J 1 1 1 I 1 1 I 1 1 1 I I I I I I I 1 1 1 I I 1 I I 1 I 1 1 1 1 66.0 __-____1________ 1-- ---- 1-------- I____L-___---J-------- L_______J 1 I 1 1 I I I I 1 1 1 1 1 1 I 1 1 1 1 I 1 I 1 I I I I I I I 65.5 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Station (ft) 09/22/98 FlowMaster v5.13 09:28:28 AM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 CHANNEL Project No: 1466-14-96 Shear Engineering Corporation By: MEO 9/15/98 Prempond OUTPUT PIPE AREA (SF) = 1.23 WETTED PERIMETER 3.93 FEET HYD. RAD (FT) = 0.313 FEET R"2/3 = 0.4603 OUTLET PIPE CAPACITY = 10.30 CFS LOWER ORIFICE AREA (A) = 0.0491 SQUARE FEET HEAD OVERFLOW WEIR ELEV. OVER LOWER HEAD LOWER ORIFICE OVER WEIR TOTAL ELEV. NOTES ORIFICE FLOW WEIR FLOW FLOW ft ft cfs ft cfs cfs ft 67.00 0.00 0.00 0.00 0.00 0.00 67.00 REQ'D WSEL ACTUAL WSELJ OVERFLOW WEIR WSEL FOR Q100 TOP BERM 67.25 0.13 0.09 0.00 0.00 0.09 67.25 67.50 0.38 0.16 0.00 0.00 0.16 67.50 67.75 0.63 0.20 0.00 0.00 0.20 67.75 68.00 0.88 0.24 0.00 0.00 0.24 68.00 68.25 1.13 0.27 0.00 0.00 0.27 68.25 68.50 1.38 0.30 0.00 0.00 0.30 68.50 68.75 1.63 0.33 0.00 0.00 0.33 68.75 69.00 1.88 0.35 0.00 0.00 0.35 69.00 69.12 1.99 0.36 0.00 0.00 0.36 69..12 69.25 2.13 0.37 0.00 0.00 0.37 69.25 69.301 2.18 0.38 0.00 0.00 0.38 69.30 69.30 1 2.18 0.38 0.00 0.00 0.38 69.30 69.50 2.38 0.39 0.20 5.81 6.21 69.50 69.626 2.50 0.40 0.33 12.09 12.49 69.63 69.75 2,.63 0.41 0.45 19.62 20.04 69.75 70.00 2.88 0.43 0.70 38.07 38.50 70.00 70.25 3.13 0.45 0.95 60.19 60.64 70.25 70.30 3.18 0.46 1.00 65.00 65.46 70.30 ORIFICE EQUATION: CA(2gH) 1/2 WEIR FLOW EQTN. : CwLH 3/2 NOTE: HEAD OVER ORIFICE = HEAD OVER CENTER OF ORIFICE APPROXIMATE W.S.EL. FOR Qrel = 0.38 CFS = 69.30 FT OK > REQUIRED Qrel Q REQ'D W.S.EL. = 0.36 CFS OK LESS THAN ALLOWED Freeboard provided = 1.00 feet - based on outlet hydraulics Verify that overflow weir is adequate to pass the design flow if orifice clogged Qdesign = 12.49 cfs Weir capacity = 65.00 cfs overflow weir adequate Flow Depth over weir given Qdesign 0.33 ft W.S.Elev = 69.63 ft Flow line elevation at lowpoint in parking lot = 69.82 ft CONCLUDE: Outlet structure is adequate Install Headwall with orifice plate Orifice diameter is 3" Overflow weir will pass the developed Q100 to the pond without causing the W.S.Elev. to encroach on the parking lot Page 6 of 6 Project No: 1466-14-96 Shear Engineering Corporation By: MEO OUTLET STRUCTURE FOR LOT 1 & 2 EVERGREEN PARK PROJECT: LOT 1 & 2 EVERGREEN PARK DETERMINE ORIFICE SIZE Q= CA(2gH)A0.5 A = Q/(C(29H)"0.5 H (ft) = 2.12 C = 0.65 Q (cfs)= 0.38 A (sf) = 0.05 DIAM(ft)= 0.2525 USE DIAM= 0.25 3" 9/15/98 Prempond LOWER ORIFICE DIAM. (ft) = LOWER ORIFICE INV. (ft) = LOWER ORIFICE COEF. (Cl) = 100 YR RELEASE RATE (cfs)= 100 YR WSEL REQUIRED (ft)= OUTLET PIPE DIAM. (ft) = PIPE SLOPE (U = MANNINGS n = INPUT OVERFLOW WEIR DESIGN FLOW (CfS) WEIR LENGTH (ft) WEIR INVERT (ft) WEIR COEF. (Cw) TOP OF BERM (ft) JINIT. DELTA (ft) DELTA HEAD (ft) BROADCRESTED 12.49 25.00 69.30 2.60 70.30 0.25 0.25 0.25 67.00 0.65 0.38 69.12 1.25 2.170 0.012 Page 5 of 6 Project No: 1466-14-96 Shear Engineering Corporation By: MEO AVERAGE END AREA METHOD PROJECT : LOTS 1 & 2 EVERGREEN PARK INVERT 67 FEET FIRST EVEN CONTOUR 68 FEET INCREMENT 1 FOOT TOP BERM ELEV 70.3 FEET STAGE ft ELEV ft AREA (A2) sq ft VOLUME (V1) cf CUM. VOLUME cf CUM. VOLUME cy CUM. VOLUME ac-ft 0.00 67.00 0 0 0 0 0.00 1.00 68.00 4596 2298 2298 85 0.05 2.00 69.00 11211 7904 10202 378 0.23 3.00 70.00 14105 18701 20999 778 0.48 9/15/98 Prempond VOLUME REQUIRED = 11467 CF = 0.26 AF W. S. ELEV. REQ'D = 69.12 FEET - based on stage storage only FINISHED FLOOR ELEVATION = 72.10 FEET LOT 2 FINISHED FLOOR ELEVATION = 72.10 FEET LOT 1 SEPARATION PROVIDED =. 2.98 FEET FREEBOARD PROVIDED = 1.18 FEET - based on stage storage only :ONCLUDE: '= OVERFLOW WEIR INVERT AT 69.3 FEET JOLUME AVAILABLE AT OVERFLOW = 13441 CF VS 11467 CF 0.31 AC -FT VS 0.26 AC -FT ?OND VOLUME IS ADEQUATE e,. Page 4 of 6 Project No: 1466-14-96 Shear Engineering Corporation By: MEO 9/15/98 Prempond DETENTION VOLUME REQUIRED FOR DETENTION POND OF LOT 1 & 2 EVERGREEN PARK PROJECT: LOT 1 & 2 EVERGREEN PARK CUMULATIVE RUNOFF METHOD FOR SIZING DETENTION PONDS DESIGN STORM: 100 YEAR RUNOFF COEFFICIENT RELEASE RATE: 0.38 CFS AREA: INITIAL TIME: 5 MINUTES TIME INCREMENT: 0.91 1.47 ACRES 5 MINUTES INFLOW INFLOW RELEASE STORAGE STORAGE TIME TIME NTENSIT RATE VOLUME VOLUME VOLUME VOLUME min sec iph cfs cf cf cf ac-ft 5 300 9.30 12.44 3732.2 114.0 3618.2 0.08 10 600 7.14 9.55 5730.7 228.0 5502.7 0.13 15 900 6.06 8.11 7295.8 342.0 6953.8 0.16 20 1200 5.21 6.97 8363.3 456.0 7907.3 0.18 25 1500 4.63 6.19 9290.3 570.0 8720.3 0.20 30 1800 4.20 5.62 10113.0 684.0 9429.0 0.22 35 2100 3.81 5.10 10702.9 798.0 9904.9 0.23 40 2400 3.60 4.82 11557.7 912.0 10645.7 0.24 45 2700 3.28 4.39 11846.7 1026.0 10820.7 0.25 50 3000 3.02 4.04 12119.6 1140.0 10979.6 0.25 55 3300 2.80 3.75 12360.3 1254.0 11106.3 0.25 60 3600 2.60 3.48 12520.9 1368.0 11152.9 0.26 651 3900 2.43 3.25 12677.4 1482.0 11195.4 0.26 70 4200 2.30 3.08 12922.2 1596.0 11326.2 0.26 75 4500 2.17 2.90 13062.6 1710.0 11352.6 0.26 80 4800 2.07 2.77 13291.4 1824.0 11467.4 0.26 85 5100 1.96 2.62 13371.6 1938.0 11433.6 0.26 90 5400 1.87 2.50 13508.1 2052.0 11456.1 0.26 95 5700 1.77 2.37 13496.1 2166..0 11330.1 0.26 100 6000 1.70 2.27 13644.5 2280.0 11364.5 0.26 105 6300 1.63 2.18 13736.8 2394.0 11342.8 0.26 110 6600 1.57 2.10 13861.2 2508.0 11353.2 0.26 115 69001 1.50 2.01 13845.2 2622.0 11223.2 0.26 120 72001 1.44 1.93 13869.3 2736.0 11133.3 0.26 DETENTION VOLUME REQUIRED = 11467 cf = 0.26 ac-ft NOTE: RELEASE RATE IS THE DEVELOPED 2-YEAR PEAK FLOW FROM THE PORTION SITE SITUATED IN THE SUB -BASIN 3B AS DELINEATED IN THE •AMENDED EVERGREEN GREENBRIAR REPORT LESS THE UNDETAINED FLOWS FROM THE WESTERN PORTION OF THE SITE Page 3 of 6 Project No: 1466-14-96 Shear Engineering Corporation By: MEO DETENTION POND RATING CURVE ELEV. FT STAGE FT VOLUME CF VOLUME AF RELEASE CFS 67.00 0.00 0 0.00 0.00 68.00 1.00 2298 0.05 0.24 69.00 2.00 10202 0.23 0.35 70.00 3.00 20999 0.48 38.50 DETENTION POND SUMMARY BOTTOM OF POND 67.00 FT RELEASE RATE 0.38 CFS REQUIRED VOLUME FOR 100-YEAR STORM 11467 CF 0.26 AF TOP OF BERM ELEVATION 70.30 FT VOLUME PROVIDED 20999 CF 0.48 AF 100-YEAR WATER SURFACE ELEVATION (based on outlet hydraulics) 69.30 FT FREEBOARD PROVIDED 1.00 FT 9/22/98 Prempond Page 2 of 6 Project No: 1466-14-96 Shear Engineering Corporation 9/15/98 By: MEO Prempond DETENTION Page 1 of 6 Job No: 1466-14-96 Shear Engineering Corporation 9/15/98 By: MEO Premrat DEVELOPED FLOW TO CONCENTRATION POINT 4 FROM SUBBASIN 1N PROJECT: LOT 1 & 2 EVERGREEN PARK AREA (A)= 0.490 ACRES RUNOFF COEF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.51 0.51 0.64 SEE SPREAD SHEET ATTACHED ON PAGE 2 TIME'OF CONCENTRATION (Tc) OVERLAND TRAVEL TIME (Ti) LENGTH = 30 FEET SLOPE = 10.00 `c 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 4.31 4.31 4.07 TRAVEL TIME (Tt)=L/(60*V) NB: ALL VELOCITIES TAKEN FROM FIGURE 3-2 Length Slope Flow Type Velocity Tt ft s fps min 360 0.50 swale 1.11 5.41 ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 TOTAL TRAVEL TIME (min) = 5.41 Total Length = 390 L/180+10= 12.17 > 9.48 Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR TC (min)= 9.72 9.72 9.48 USE Tc = 9.50 9.50 9.50 INTENSITY (I) (iph) NB INTENSITIES TAKEN FROM FIGURE 3-1 2 YEAR 10 YEAR 100 YEAR I = 2.62 4.57 7.36 RUNOFF (Q= CIA) (Cfs) 2 YEAR 10 YEAR 100 YEAR IQ = 0.65 1.14 2.29 CONCLUDE: Flow to channel along north side of Lot 1 from site Undetained Flow Reduce Release Rate from Pond by 0.65 CFS Page 9 of 9 Job No: 1466-14-96 Shear Engineering Corporation By: MEO 9/11/98 Premrat )EVELOPED 7LOW TO CONCENTRATION POINT 3 ?ROM SUBBASIN 2-N PROJECT: LOT 1 & 2 EVERGREEN PARK 0.1 RUNOFF COEF. (C) 2 YEAR 10 YEAR C = 0.72 0.72 SEE SPREAD SHEET ATTACHED ON PAGE TIME OF CONCENTRATION (TC OVERLAND TRAVEL TIME (Ti) LENGTH = 30 FEET 2 YEAR C = 0.20 Ti (min)= 7.33 101 YEARI 0.89 �i 11- SLOPE = 2.00 °s 10 YEAR 100 YEAR 0.20 0.25 7.33 6.93 TRAVEL TIME (Tt)=L/(60*V) NB: ALL VELOCITIES TAKEN FROM FIGURE 3-2 Length Slope Flow Type Velocity Tt ft % fps min 147 0.50 GUTTER 1.50 1.63 ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 TOTAL TRAVEL TIME (min) = 1.63 Total Length = 177 L/180+10= 10.98 > 8.56 Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 8.97 8.97 8.56 USE Tc = 9.00 9.00 8.50 INTENSITY (I) (iph) NB INTENSITIES TAKEN FROM FIGURE 3-1 2 YEAR 10 YEAR 100 YEAR = 2.69 4.69 7.79 RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAR Q = 0.31 0.54 1.11 :ONCLUDE: FLOW TO INLET AT LOWPOINT ON BLUE SPRUCE FROM 1/2 ROW IN FRONT OF SITE AND FRONT OF BUILDINGS UNDETAINED FLOW REDUCE RELEASE RATE FROM POND BY 0.31 CFS Page 8 of 9 Job No: 1466-14-96 Shear Engineering Corporation 9/11/98 By: MEO Premrat DEVELOPED FLOW TO CONCENTRATION POINT 2 FROM SUBBASIN 2-S PROJECT: LOT 1 & 2 EVERGREEN PARK AREA (A)= 0.220 ACRES RUNOFF COEF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.72 0.72 0.89 SEE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (TC) OVERLAND TRAVEL TIME (Ti) LENGTH = 30 FEET SLOPE = 2.00 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 7.33 7.33 6.93 TRAVEL TIME (Tt)=L/(60*V) NB: ALL VELOCITIES TAKEN FROM FIGURE 3-2 Length Slope Flow Type Velocity Tt ft % fps min 168 0.50 GUTTER 1.50 1.87 ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 TOTAL TRAVEL TIME (min) = 1.87 Total Length = 198 L/180+10= 11.10 > 8.79 Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR TC (min)= 9.20 9.20 8.79 USE Tc = 9.00 9.00 9.00 INTENSITY (I) (iph) NB INTENSITIES TAKEN FROM FIGURE 3-1 2 YEAR 10 YEAR 100 YEAR I = 2.69 4.69 7.57 RUNOFF (Q= CIA) (Cfs) 2 YEAR 10 YEAR 100 YEAR IQ = 0.42 0.74 1.49 CONCLUDE: UNDETAINED FLOW FROM 1/2 ROW IN FRONT OF SITE AND FROM FRONT OF BUILDINGS REDUCE RELEASE RATE FROM POND BY 0.42 CFS Page 7 of 9 Job No: 1466-14-96 Shear Engineering Corporation By: MEO FOR REFERENCE ONLY HISTORIC FLOW TO CONCENTRATION POINT 1 FROM SUBBASIN SITE PROJECT: LOT 1 & 2 EVERGREEN PARK AREA (A)= 2.120 ACRES RUNOFF COEF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 LAWN CLAY SOIL, FLAT 9/11/98 Premrat TIME OF CONCENTRATION (TC) OVERLAND TRAVEL TIME (Ti) LENGTH = 400 FEET SLOPE = 1.00 °s 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 33.66 33.66 31.79 TRAVEL TIME (Tt)=L/(60*V) NB: ALL VELOCITIES TAKEN FROM FIGURE 3-2 Length Slope Flow Type Velocity Tt ft % fps min ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 TOTAL TRAVEL TIME (min) = 0.00 Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 33.66 33.66 31.79 USE Tc = 33.50 33.50 33.50 INTENSITY (I) (iph) NB INTENSITIES TAKEN FROM FIGURE 3-1 2 YEAR 10 YEAR 100 YEAR I = 1.47 2.60 4.20 RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAR IQ = 0.62 1.10 2.23 CONCLUDE: HISTORIC FLOW TO EVERGREEN WEST DETENTION POND BASED ON TOPOGRAPHY EXISTING TOPOGRAPHY DOES NOT MATCH MASTER PLAN DELINEATION Page 6 of 9 Job No: 1466-14-96 Shear Engineering Corporation By: MEO DEVELOPED FLOW TO CONCENTRATION POINT 1 FROM SUBBASIN 1P PROJECT: LOT 1 & 2 EVERGREEN PARK 1.470 ACRES RUNOFF COEF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.73 0.73 0.91 SEE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (TC) OVERLAND TRAVEL TIME (Ti) LENGTH = 30 FEET SLOPE = 2.00 % 2 YEAR 10 YEAR 100 YEAR C = 0.95 0.95 1.00 Ti (min)= 1.22 1.22 0.81 TRAVEL TIME (Tt)=L/(60*V) NB: ALL VELOCITIES TAKEN FROM FIGURE 3-2 Length Slope Flow Type Velocity Tt ft % fps min 310 0.50 GUTTER 1.50 3.44 40 2.00 LAWN 1.00 0.67 TOTAL TRAVEL TIME (min) = 4.11 Total Length = 380 L/180+10= 12.11 > 4.93 TC =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR TC (min)= 5.33 5.33 4.93 USE Tc = 5.50 5.50 5.00 INTENSITY (I) (iph) NB INTENSITIES TAKEN FROM FIGURE 3-1 2 YEAR 10 YEAR 100 YEAR C = 3.22 5.52 9.30 9/15/98 Premrat RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAR Q = 3.45 5.93 12.49 Developed Flow Q3B = 1.77 3.03 6.25 Allowable Flow DELTA = 1.68 2.90 6.24 Excess Flow to pond Qundet= 1.38 2.41 4.90 Undetained Flow Q3B-Qund= 0.38 0.62 1.35 "-ONCLUDE: DETAIN AND RELEASE INTO EVERGREEN WEST POND SIZE OVERFLOW WEIR FOR Q100 = 12.49 CFS RELEASE RATE = 2-YEAR (Q3B)-(Qundet) = 0.38 CFS Page 5 of 9 Job No: 1466-14-96 Shear Engineering Corporation By: MEO DEVELOPED FLOW TO CONCENTRATION POINT 7 FROM CITY SUBBASIN 3B PROJECT: LOT 1 & 2 EVERGREEN PARK = 1.150 ACRES RUNOFF COEF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.47 0.47 0.58 SEE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (Tc OVERLAND TRAVEL TIME (Ti) LENGTH = 30 FEET 2 YEAR C = 0.95 Ti (min)= 1.22 SLOPE = 2.00 10 YEAR 100 YEAR 0.95 1.00 1.22 0.81 TRAVEL TIME (Tt) =L/(60*V) NB: ALL VELOCITIES TAKEN FROM FIGURE 3-2 Length Slope Flow Type Velocity Tt ft °s fps min 150 0.50 GUTTER 1.50 1.67 40 2.00 LAWN 1.00 0.67 ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 ? ? ? 0.00 0.00 TOTAL TRAVEL TIME (min) = 2.33 Total Length = 220 L/180+10= 11.22 > 3.15 Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 3.56 3.56 3.15 USE Tc = 5.00 5.00 5.00 CNTENSITY (I) (iph) NB INTENSITIES TAKEN FROM FIGURE 3-1 2 YEAR 10 YEAR 100 YEAR [ = 3.29 5.64 9.30 RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAF 2. = 1.77 3.03 6.25 �ONCLUDE: USE AS RELEASE RATE FOR POND RUNOFF FROM SUB -BASINS ROW-N AND ROW-S IS UNDETAINED COMPENSATE FOR UNDETAINED FLOWS BY REDUCING RELEASE RATE SEE CALCULATIONS ON PAGE 5 9/15/98 Premrat Page 4 of 9 Job No: 1466-14-96 Shear Engineering Corporation 9/15/98 By: MEO Premrat SUB -BASIN BREAKDOWN PROJECT: LOT 1 & 2 EVERGREEN PARK TOTAL SITE AREA = 2.12 ACRES 1P = 1.47 Acres - site only 1W = 0.09 Acres- site only- included in sub -basins 2-N and 3-N 1S = 0.07 Acres - site only 1N = 0.49 Acres - site only TOTAL = 2.12 ACRES- SITE ONLY 2-N = 0.16 Acres - included/2 ROW and parts of 1W 2-S = 0.22 Acres - included/2 ROW and parts of 1W TOTAL = 0.38 ACRES SUB BASINS SUB BASINS 1P 1S 1N 3B 2-N 2-S ASPHALT 0.61 0.00 0.00 0.24 0.09 0.12 CONCRETE 0.07 0.00 0.02 0.02 0.02 0.04 GRAVEL 0.00 0.00 0.00 0.00 0.00 0.00 ROOFS 0.36 0.00 0.13 0.15 0.00 0.00 LAWNS, SANDY SOIL FLAT < 2° 0.00 0.00 0.00 0.00 0.00 0.00 AVERAGE 2 TO 7% 0.00 0.00 0.00 0.00 0.00 0.00 STEEP > 7% 0.00 0.00 0.00 0.00 0.00 0.00 LAWNS, HEAVY SOIL: FLAT < 2% 0.43 0.07 0.08 0.74 0.05 0.06 AVERAGE 2 TO 7% 0.00 0.00 0.00 0.00 0.00 0.00 STEEP > 7% 0.00 0.00 0.26 0.00 0.00 0.00 TOTAL 1.47 0.07 0.49 1.15 0.16 0.22 RUNOFF COEFFICIENT SUB BASINS 1P 1S 1N 3B 2-N 2-S C2-C10 0.73 0.20 0.51 0.47 0.72 0.75 C100 = 1.25*C2 0.91 0.25 0.64 0.58 0.89 0.93 NB BASIN 3B IS 35.65% IMPERVIOUS Page 3 of 9 Job No: 1466-14-96 Shear Engineering Corporation 9/15/98 By: MEO Premrat FLOW SUMMARY FOR LOT 1 & 2 EVERGREEN PARK DESIGN CONTRIBUTING AREA C2 C100 Tc Tc I2 I100 Q2 Q100 DESIGN POINT SUB 2,10 100 BASIN(S) ac. min. min iph iph cfs cfs HISTORIC SITE 1 SITE 1 2.12 1 0.20 1 0.25 1 33.66 1 31.79 1.47 4.20 0.62 2.23 DEVELOPED SITE 1 3B 1.15 0.47 0.58 5.00 5.00 3.29 9.30 1.77 6.25 RELRATE 1 1P 1.47 0.73 0.91 5.33 4.93 3.22 9.30 3.45 12.49 DETAIN 2 2-S 0.22 0.72 0.89 9.20 8.79 2.69 7.57 0.42 1.49 UNDETAIN 3 2-N 0.16 0.72 0.89 8.97 8.56 2.69 7.79 0.31 1.11 UNDETAIN 4 1N 0.49 0.51 0.64 9.50 9.50 2.62 7.36 0.65 2.29 JUNDETATN NOTES: 3B IS THE PORTION OF THE SITE LOCATED IN SUB -BASIN 3B AS DELINEATED ON THE CITY MASTER PLAN 2-YEAR PEAK FLOW FROM SUB -BASIN 3B IS USED AS RELEASE RATE FOR POND LESS THE UNDETAINED 2-YEAR PEAK FLOWS FROM THE WESTERN PORTION OF THE DEVELOPED SITE Page 2 of 9 Job No: 1466-14-96 Shear Engineering Corporation 9/11/98 By: MEO Premrat RUNOFF Page 1 of 9 APPENDIX I Storm Drainage Calculations Final Drainage and Erosion Control Report for Lots 1 & 2 Block 5 (Replat No. 1) Evergreen Park Page 14 of 14 1466-14-96 VII. CONCLUSIONS: A. Compliance with Standards 1. All drainage analysis has been performed according to the requirements of the City of Fort Collins Storm Drainage Criteria Manual and the City of Fort Collins policy. 2. All Erosion Control design complies with the City of Fort Collins Erosion Control Reference Manual and generally accepted practices. B. Drainage Concept 1. The drainage design for Lots 1 and 2, Block 5, Replat (No: 1) of Evergreen Park is in accordance with the City of Fort Collins requirements with the exception of the variances noted above. 2. There will be no adverse downstream effects due to the development of the site. VM. REFERENCES: A. Fort Collins Storm Drainage Criteria Manual B. Urban Drainage and Flood Control District Drainage Criteria Manual C. Greenbriar-Evergreen Park Master Drainage Plan; Engineering Professionals D. Final Utility plans for Major Storm Drainage Way for Evergreen Park; Engineering Professionals; EPI Project No: 97-1; plans dated March, 1981 E. The Amended Greenbriar-Evergreen Basin Master Drainage Plan; Lidstone & Anderson, Inc.; Project No COTST05.4; dated May, 1996 Final Drainage and Erosion Control Report for Lots 1 & 2 Block 5 (Replat No. 1) Evergreen Park Page 13 of 14 1466-14-96 VI. VARIANCE REQUEST: A. Variance from City of Fort Collins requirements 1: A variance from the requirement that detention be provided for the runoff from the 1/2 ROW in front of the site is formally requested with the submittal of this report and Drainage and Erosion Control Plan. a. The central driveway is located at a high point on Blue Spruce Drive. Conveying runoff into the site from Blue Spruce Drive is difficult to achieve at best. b. A low point on Blue Spruce Drive is located at the northwest corner of the site. Storm sewer inlets are located at this point. This is part of the major conveyance system to the Evergreen Regional Pond. C. The release rate of the detention pond has been reduced to compensate for the undetained runoff from the western. sub - basins (1-N and 1-S). 2. A variance from complying with the Master Plan for this area is also formally requested with the submittal of this report and the Drainage and -Erosion Control Plan. a. The existing topography does not reflect the Basin Delineation of the Amended Greenbriar-Evergreen Basin Master Drainage Plan. b. Detention has been provided in the eastern portion of the site. Release rates are restricted to less than the allowable from the site into the regional pond. C. The decision to provide detention in the eastern portion of the site was discussed and verbally approved by personnel from the City of Fort Collins Stormwater Utility. Final Drainage and Erosion Control Report for Lots 1 & 2 Block 5 (Replat No. 1) Evergreen Park Page 12 of 14 1466-14-96 V. EROSION CONTROL: A. General Concept Erosion control measures are specified on the Drainage and Erosion Control Plan. 2. An erosion control security deposit is required in accordance with City of Fort Collins policy (Chapter 7, Section C : SECURITY; page 7.23 of the City of Fort Collins Development Manual). In no instance shall the amount of the security be less than $ 1000.00. 3. According to current City of Fort Collins policy, the erosion control security deposit is figured based on the larger amount of 1.5 times the estimated cost of installing the approved erosion control measures or 1.5 times the cost to re -vegetate the anticipated area to be disturbed by construction activity. 4. Refer to the security deposit document located in Appendix II of this report. B. Specific Details 1. Temporary erosion control measure to be installed on the site during construction include: a. Silt fence along the south and east property lines to be installed prior to the commencement of overlot grading. b. Gravel inlet filter at the outlet device on the east side of the site. C. Haybales will be place in the channel along the north property d. A sediment trap will be provided in the, detention pond. 2. Buried riprap will be placed at the outfall of the storm sewer and on the downstream side of the emergency overflow weir. The riprap from the storm sewer will extend down to bottom of the bank of the detention pond. a. All riprap will have a D50 of 12". b. Dimensions of the riprap apron and at the weir are shown on the Drainage and Erosion Control Plan. Final Drainage and Erosion Control Report for Lots 1 & 2 Block 5 (Replat No. 1) Evergreen Park Page 11 of 14 1466-14-96 IV. DRAINAGE FACILITY DESIGN (Continued): C. Specific Details — Detention (continued) 3. The separation provided between the actual 100-Year W.S.EI. and the finished floor elevation of the building on lot 2 is 2.83 feet. 4. The outlet structure will consist of a headwall with an orifice plate. The orifice plate has a 3" diameter orifice cut into it. Refer to page 6 of 6, Appendix I for the hydraulic analysis of the outlet structure. 5. An emergency overflow weir will be installed in the berm along the eastern property line at an elevation of 69.30 feet. The weir is sized to pass the developed Q100 from Sub -basin 1P in case the outlet is clogged. 6. The Rating curve for the detention pond is summarized below. • 11 1 11 � 1 11 1 11 •: 11 11 .I': 1 1 1 •• 11 11 1 1 �� 1 11 11 1••• 1 �: 1 n Final Drainage and Erosion Control Report for Lots 1 & 2 Block 5 (Replat No. 1) Evergreen Park Page 10 of 14 1466-14-96 IV. DRAINAGE FACILITY DESIGN (Continued): C. Specific Details - Detention 1. The detention pond in the eastern portion of the site is sized using the Cumulative Runoff method. a. The runoff coefficient (C100) utilized with the Cumulative Runoff method for sizing the detention pond is 0.91. b. The pond is sized to restrict the release rate to 0.38 cfs. Refer to page 5 of 9 in the calculations. 2. The pond is sized using the area of Sub -basin 1P. This area totals to 1.47 acres Refer to page 5 of 9 in the calculations. a. The required detention pond storage volume is 11,467 cubic feet. Refer to page 3 of 6, Appendix I for the detention pond volume calculations. b. The actual volume that is provided in the detention pond is 20,999 cubic feet. Refer to page 4 of 6, Appendix I for the Stage -Storage calculations. C. The required 100-year W.S.EI based on the stage storage curve is 69.12 feet. Refer to page 4 of 6, Appendix I for the Stage -Storage calculations. d. The actual 100-year W.S.EI based on the hydraulics of the outlet structure is 69.30 feet. Refer to page 6 of 6, Appendix I for the Outlet Structure calculations. e. The finished floor elevation for the building on lot 1 is set at an elevation of 72.1 feet. f The finished floor elevation for the building on lot 2 is set at an elevation of 72.1 feet. g. The freeboard provided is 1.0 feet based on the outlet hydraulics. h. The separation provided between the actual 100-Year W.S.EI. and the finished floor elevation of the building on lot I is 2.83 feet. Final Drainage and Erosion Control Report for Lots I & 2 Block 5 (Replat No. 1) Evergreen Park Page 9 of 14 1466-14-96 IV. DRAINAGE FACILITY DESIGN (Continued): B. Specific Details - Channel 1. Lidstone and Anderson in the amended Greenbriar-Evergreen Master Drainage Plan did a preliminary channel design for the channel on the north side of the site. The preliminary channel geometry, design flow and capacity are summarized below. Bottom width = 30.0 feet Mannings n = 0.060 Slope = 0.0025 ft/ft Side slopes = 4:1 (Run: Rise) Design Flow = 80.0 cfs Depth = 2.5 feet Top width = 50.0 feet Flow depth = 1.52 feet Freeboard = 0.98 feet Flow capacity — 195.0 cfs 2. The design flow of 80 cfs was obtained from Table 5-3 in the Greenbriar Evergreen Master Plan (Draft) — element number P2. The table is attached in appendix IV of this report. Analysis of the existing channel cross sections indicated that the constructed channel does not conform to the original design by EPI or the design by Lidstone and Anderson done with the Amended Greenbriar-Evergreen Master Drainage Plan. 4. Grading modifications will be completed on the south side of the existing channel with this project to provide the .necessary conveyance for the design flow (Q100 = 80 cfs). 5. Refer to the Haestad print outs in the drainage calculations for flow capacity and High Water Level in the modified channel. 6. Refer to channel sections included on sheet 5. Final Drainage and Erosion Control Report for Lots I & 2 Block 5 (Replat No. 1) Evergreen Park Page 8 of 14 1466-14-96 IV. DRAINAGE FACILITY DESIGN: A. General Concept The stormwater from the site will be directed to the east and west by creating a high point approximately 30 feet east of the west property line. 2. Detention pond release from the eastern portion of the property. (Sub -basin IP) will occur near the property line of Lot I and 2. 3. The outlet will consist of a headwall with an orifice plate. 4. The orifice plate will be act as the restriction device to reduce flows to the regional detention pond. Final Drainage and Erosion Control Report for Lots 1 & 2 Block 5 (Replat No. 1) Evergreen Park Page 7 of 14 1466-14-96 M. DRAINAGE AND EROSION CONTROL DESIGN CRITERIA (Continued): C. Hydrological Criteria The Rational method (Q = CIA) was used to determine the pre - developed and post development peak flows for the 10 and 100- year storm events (commercial requirements). 2. Planning Department requirements do not allow for adequate area to provide detention in the western portion of the site (Basin 4U of the master plan). 3. Stormwater from Basin 3B may be released undetained to the Evergreen West regional detention pond according to the Greenbriar-Evergreen Basin Master Drainage Plan. 4. It was agreed that detention would be provided at the eastern end of the site in order to compensate for there being no detention at the western end of the site. 5. All runoff from the site eventually reaches the Evergreen West Regional Detention Pond. 6. Runoff from the western portion of the site (Sub -basins ROW-N and ROW-S) will be released. undetained into Blue Spruce Drive. These flows will be compensated for by reducing the allowable release from the pond at the east end of the site. D. Hydraulic Criteria Orifice and weir equations and coefficients suggested by the City of Fort Collins Storm Drainage Criteria Manual were used. Final Drainage and Erosion Control Report for Lots I & 2 Block 5 (Replat No. 1) Evergreen Park Page 6 of 14 1466-14-96 II. DRAINAGE BASINS AND SUB -BASINS (Continued): B. Sub -basin Description (continued) 11. Note: Runoff from sub -basins IS) 2-S and 2-N will not be affected by the development because the imperviousness of these sub - basins will not be changed. M. DRAINAGE AND EROSION CONTROL DESIGN CRITERIA: A. Regulations 1. Storm drainage design criteria from the City of Fort Collins Drainage Criteria Manual was utilized. 2. Storm Drainage design criteria modification was considered based on data provided by City of Fort Collins Stormwater Utility personnel concerning conclusions presented with the amended Greenbriar-Evergreen Park Master Drainage Plan. 3. Erosion control design criteria from the City of Fort Collins Erosion Control Reference Manual was utilized. B. Development Criteria Reference and Constraints Previous studies which were considered include: a. Greenbriar-Evergreen Park Master Drainage Plan; Engineering Professionals b. The Amended Greenbriar-Evergreen Basin Master Drainage Plan; Lidstone & Anderson, Inc.; Project No COTST05.4; dated May 1996. C. Blue Spruce Drive is developed and paved. All grading along Blue Spruce Drive will have to match the existing grade at the curb and gutter. d. New American Disabilities Act (ADA) requirements affect the final parking lot grading design. Maximum allowable design grades for handicap parking, and access from the public right-of-way effect the drive and parking lot final grading. Final Drainage and Erosion Control Report for Lots I & 2 Block 5 (Replat No. 1) Evergreen Park Page 5 of 14 1466-14-96 H. DRAINAGE BASINS AND SUB -BASINS (Continued): B. Sub -basin Description (continued) 8. There is an existing drainage channel along the north property line of Lot 1, Block 5 that conveys storm water from the storm sewer under Blue Spruce Drive to the Evergreen West Pond. a. The channel is located along the common property line of Lot 1, Block 5 of Evergreen Park and Coachlight Plaza PUD. b. There is an existing sixteen (16') foot Utility and Drainage easement along the south side of the north property line of lot 1 as shown on the plat of Replat (No. 1) of Evergreen Park. C. There is an existing thirty eight (38') foot Utility and Drainage easement along the north side of the north property line of lot 1 as shown on the Replat of Coachlight Plaza PUD. 9. Portions of the site are situated in the 100 -year flood plain according to the Flood Insurance Rate Map (FIRM) for the City of Fort Collins; Community Panel Number 080102-0004-C; Dated March 18,1996. The base flood elevation for the site is approximately 4970 feet according to the FIRM. 10. The development of the property will create 5 sub -basins which are summarized in the table below; Sub -basin Area C100 Detained Outfall Undetained Location 1P 1.47 0.91 Detained Regional Pond 1N 0.49 0.64 Undetained Channel/Regional Pond 1S 0.07 0.25 Undetained Regional Pond 2-S 0.22 0.93 Undetained Blue Spruce Drive 2-N 0.16 0.89 Undetained Blue Spruce Drive Final Drainage and Erosion Control Report for Lots 1 & 2 Block 5 (Replat No. 1) Evergreen Park Page 4 of 14 1466-14-96 H. DRAINAGE BASINS AND SUB -BASINS (Continued): B. Sub -basin Description (continued) 2. a. the basin, in order to meet the prescribed release rate, was estimated to be 6.4 acre feet. 3. According to the Amended Greenbriar-Evergreen Master Drainage Plan the eastern portion of both lots are situated within Basin 3B as defined the amended Greenbriar-Evergreen Basin Master Drainage Plan. See the Exhibit from amended Greenbriar-Evergreen Park Master Drainage Plan included with the Drainage and Erosion Control Plan in the stuffier envelope. 4. Page 19 of the draft of the Amended Greenbriar-Evergreen Basin Master Drainage Plan states the following: a. BASIN 3B. The basin was assumed to be developed for 37_ percent commercial use, and 63 percent residential housing at levels representing 11, 49 and 3 percent of the entire basin for high, medium and low densities, respectively. The result is a developed imperviousness of 63 percent. On -site detention would not be required for this basin; storm water runoff would be transported to the existing Evergreen West Pond. Overflow from this pond would enter the existing outlet channel which would transport flow southerly to Pond 5 (conceptual). s. All of Lot 1 is situated in Basin 3B based on the existing topography of the site and the street. There is a high point located approximately 40' north of the south property line of lot I and the existing site topography slopes to the east. 6. All of Lot 2 is situated in Basin 3B based on the existing topography of the site. 7. After discussions with the personnel from the Fort Collins Stormwater Utility, it was decided that the majority of the site would be allowed to drain to the Evergreen West Regional Pond and that onsite detention would be provided to compensate for the additional runoff Final Drainage and Erosion Control Report for Lots I & 2 Block 5 (Replat No. 1) Evergreen Park Page 3 of 14 1466-14-96 I. GENERAL LOCATION AND DESCRIPTION (Continued) B. Description of Property (continued) 6. There are no irrigation canals or systems located on or within 100' of the project site. H. DRAINAGE BASINS AND SUB -BASINS: A. Major Basin Description The site is situated within the Greenbriar-Evergreen Drainage Basin as designated on the City of Fort Collins Stormwater Basin Map. The Master Drainage Plan for the Greenbriar-Evergreen Basin is currently being amended. 2. The Basin fee rate for the Greenbriar-Evergreen Basin is $ 10,000 per gross acre according to the development fee section of the City of Fort Collins Development Manual. This may be reduced if detention is provided. B. Sub -basin Description According to the Amended Greenbriar-Evergreen Master Drainage Plan the western portion of both lots are situated within Basin 4U (undeveloped) as defined on the amended Greenbriar-Evergreen Basin Master Drainage Plan. See the Exhibit from the amended Greenbriar-Evergreen Basin Master Drainage Plan included with the Drainage and Erosion Control Plan in the stuffier envelope. The entire site should be situated in Basin 3B based on the existing site topography. 2. Page 19-20 of the draft of Amended Greenbriar-Evergreen Basin Master Drainage Plan states the following: a. BASIN 4U. The basin was assumed to be completely developed for commercial use with an estimated imperviousness of 90 percent. On -site detention would be required for this basin. The allowable release from this basin is 17 cfs, or 0.47 cfs/acre. The designated release point for Basin 4U is the storm sewer and street along Conifer Street, which convey stormwater runoff easterly to Pond 5 (conceptual). The detention volume required for Final Drainage and Erosion Control Report for Lots I & 2 Block 5 (Replat No. 1) Evergreen Park Page 2 of 14 1466-14-96 I. GENERAL LOCATION AND DESCRIPTION: A. Location Lots 1 and 2, Block 5, Replat (No. 1) of Evergreen Park are located in the Northeast One -Quarter of Section 1, T7N, R69W of the 6th P.M., Ft. Collins, (Larimer County), Colorado. These are platted lots. 2. More specifically, Lots 1 and 2, Block 5, Replat (No. 1) of Evergreen Park are located on the east side of Blue Spruce Drive approximately 1000 feet north of Conifer Drive in the Northeast part of Fort Collins, Colorado (See Vicinity Map). 3. Blue Spruce Drive is an existing street with sewer, water, curb and gutter, and street paving installed. These improvements were installed with the final utility plans for Replat (No. 1) of Evergreen Park. 4. This project will consist of two (2) warehouse style buildings and the necessary parking for the intended use. B. Description of Property There is an existing foundation on the site. This foundation will be removed and two (2) buildings will be constructed. The remainder of the site is undeveloped. Existing ground cover consists primarily of native dry land grasses. 2. The site area of lot 1 is approximately 54,087 square feet (1.24 acres). 3. The site area of lot 2 is approximately 38,300 square feet (0.88 acres). 4. An existing regional detention pond (Evergreen West Pond) and outfall channel are located east and north of this property respectively (See Drainage and Erosion Control Plan in stuffier envelope). The 100-year High Water Elevation in the Evergreen West Pond is 4965.2 feet according to the Greenbriar - Evergreen Master Plan prepared by Lidstone and Anderson. Refer to Table 4.2 located in Appendix IV. 5. There is an existing channel along the north property line of lot 1 that conveys stormwater to the Evergreen West Pond. No Text September 23, 1998 Project No: 1466-14-96 Basil Hamdan City of Ft. Collins Stormwater Utility P.O. Box 580 Ft. Collins, Colorado 80524 Re: Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park; Ft. Collins, Colorado Dear Basil, Enclosed, please find the Final Drainage and Erosion Control Report for Lots 1 & 2, Block 5, Replat (No. 1) of Evergreen Park. The hydrology data and the hydraulic analysis presented in this report complies with the requirements of the City of Fort Collins Storm Drainage Criteria Manual; dated March, 1984, and the Erosion Control Reference Manual. The site historically drains to the east. Submittal of this project has been delayed while decisions were made concerning the drainage. The new City plan requirements prohibited compliance with the Amended Greenbriar - Evergreen Basin Master Drainage Plan prepared by Lidstone & Anderson, Inc; Project No. COTST05; Dated May 1996 which would have required detention at the western end of the site. After discussions with the personnel from your office it was decided that the majority of the site would be allowed to drain east to the Evergreen West Regional Pond and that onsite detention would be provided to compensate for the additional flows. A copy of the channel design drawing is included in Appendix V for immediate reference. Regrading of the channel will be performed with this project. The regrading will be limited to the south side of the channel in order to comply with the channel typical section requirements indicated on the attached plan sheet. It is apparent from the cross sections that the channel was not built according to the original design. If you have any questions or comments, please contact us at 226-5334. Sincerely, Mark Oberschmidt Shear Engineering Corporation MEO/meo cc: Premier Custom Homes Shear Engineering Corporation 4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-0311 Final Drainage and Erosion Control Report For LOTS 1 & 2, BLOCK 5, REPLAT (NO. 1) OF EVERGREEN PARK Fort Collins, Colorado Prepared for: Premier Custom Builders, Inc. 401A South Link Lane Ft. Collins, Colorado 80524 Prepared by: SHEAR ENGINEERING CORPORATION Project No: 1466-14-96 DATE: September 1998 4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-0311