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HomeMy WebLinkAboutDrainage Reports - 07/05/1996M.ii ;��.; 0 �� -,A �. Final Drainage and Erosion Control Report for MULBERRY GREEN Lot 4, Block 105, Harrison's Addition) Fort Collins, Colorado Prepared for: B.K. Maxwell Company, Inc. 524 Spring Canyon Court Fort Collins, Colorado 80525 Prepared by: SHEAR ENGINEERING CORPORATION Project No: 1151-24-95 DATE: June, 1996 4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-031 1 r 'a PAGE 1 Project No. 1151-24-95 Final Drainage and Erosion Control Report I. GENERAL LOCATION AND DESCRIPTION: A. Location 1. Mulberry Green is located in the Northeast One Quarter (1/4) of Section 14, UN, Range 69 West of the 6th P.M., Ft. Collins, Colorado. The site is Lot 4, Block 105, Harrison's Addition. 2. More specifically, Mulberry Green is located approximately 100 feet west of the intersection of Mulberry Street and Mason Street on the south side of Mulberry Street (See Vicinity Map). 3. The site is surrounded by full development. This includes Mulberry Street and Kings Auto Dealership along with several single family residences. B. Description of Property 1. There is an existing house on the site that will be renovated as part of this project. 2. The site area is approximately 0.39 acres. 3. Development of the site will consist of 1 duplex and 2 triplex apartment units, parking for the units and the necessary utilities to service all units. 4. A gravel alley borders the site on the west side. This alley will be paved from Mulberry to the proposed south entrance to the site in accordance with the requirements of the City of Fort Collins. a. The alley will be concrete paved and provided with an inverted crown section to assist in the conveyance of stormwater to West Mulberry Street. 5. There are no major drainageways located on or within 150' feet the project site. See Drainage and Erosion Control Plan in stuffer envelope. H. DRAINAGE BASINS AND SUB -BASINS: A. Major Basin Description 1. The site is situated within the Old Town Drainage Basin as designated on the City of Fort Collins Stormwater Basin Map. a. There are no drainage fees associated with the Old Town Basin. PAGE 2 Project No. 1151-24-95 Final Drainage and Erosion Control Report H. DRAINAGE BASINS AND SUB -BASINS: A. Major Basin Description (continued) 2. Stormwater from the site drains to conveyance element 205 as delineated on figure 4.1 of the Old Town Master Drainage Basin Plan. a. According to the Old Town Master Drainage Basin Plan, stormwater flows in conveyance element 205 are split at the intersection of Mason Street and Mulberry Street. b. Some of the flows are conveyed east in the existing storm sewer while others are conveyed north on Mason when the storm sewer capacity is reached. B. Sub -Basin Description 1. The site is extremely flat. There is currently no defined flow path for the site. It appears that the majority of the existing site contributes runoff to West Mulberry Street. III. DRAINAGE AND EROSION CONTROL DESIGN CRITERIA: A. Regulations 1. All storm drainage design criteria from the City of Fort Collins Drainage Criteria Manual was considered. 2. Recommendations made in the Old Town Master Drainage Basin Plan prepared by Resource Consultants & Engineers, Inc. were also considered. a. Flood elevations noted in the Old Town Master Drainage Basin Plan were utilized to establish the minimum Finished Floor Elevations of the proposed buildings. 3. All erosion control design criteria from the City of Fort Collins Erosion Control Reference Manual was considered. B. Development Criteria Reference and Constraints 1. All grading design must match the existing elevations at the property line due to fully developed properties adjacent to the site. 2. The intersection of Mason Street and West Mulberry Street is subject to flooding due to insufficient capacity of the existing storm sewer. a. According to the Old Town Master Drainage Basin Plan, the 100-year flood elevation on Mulberry Street in the area of Mulberry Green is approximately 4993.5 feet. Refer to figure 5.6 in the Old Town Master Drainage Basin Plan attached in Appendix IV. PAGE 3 Project No. 1151-24-95 Final Drainage and Erosion Control Report M. DRAINAGE AND EROSION CONTROL DESIGN CRITERIA: B. Development Criteria Reference and Constraints (continued) 3. Minimum finished floor elevations shall be set at an elevation of 4995.0 feet in order to provided the minimum 1.5 feet separation above the defined 100-year water surface elevation. A note stating this is provided on the Master Grading, Drainage and Erosion Control Plan. 4. Detention is required if the imperviousness of the site exceeds seventy percent (70.0%). This is in accordance with the assumptions of the Stormwater Management Model (SWMM) for subcatchment 205 in the Old Town Basin. Impervious area will be less than 70%. C. Hydrological Criteria 1. The Rational Method (Q = CIA) was used to determine the pre -developed and/or post development peak flows for the 2, 10 and 100-year storm events at critical points. D. Hydraulic Criteria 1. Storm sewer and drainage channel capacities were based on the Mamungs Equation. The Mannings coefficients are as suggested by the City of Fort Collins Storm Drainage Criteria Manual. IV. DRAINAGE FACILITY DESIGN: A. General Concept 1. Stormwater is conveyed to to West Mulberry Street by a combination of overland and gutter flow. 2. The alley will be graded with an inverted crown to facilitate conveyance of stormwater into Mulberry West Street. 3. Detention is not required because the imperviousness of the developed site does not exceed 70%. 4. In addition, the Times of concentration for catchment area 205 and the site to the inlet at the southwest corner of the intersection Mullberry and Mason are significantly different. They are 60 minutes and less than 10 minutes respectively. The time of concentration for catchment area was obtained from the Old Town Master Drainage Report. Refer to exhibit A located in Appendix IV. PAGE 4 Project No. 1151-24-95 Final Drainage and Erosion Control Report W. DRAINAGE FACILITY DESIGN: B. Specific Details The following table summarizes the land cover and the appropriate percent imperviousness on the historic site. The imperviousness percentages are taken from Table 3-1 in the Urban Storm Drainage Criteria Manual - Volume 1. The Runoff Coefficient is taken from the City of Fort Collins Drainage Criteria Manual. Area Impervious Runoff Coefficient (acres) % "C" ---------- Lawn 0.36 ------------- 0.00 ---------------------- 0.20 Roof 0.03 100.00 0.95 Concrete 0.00 100.00 0.95 Total 0.39 The percent imperviousness of the historic site is 7.69%. 2. The following table summarizes the land cover and the appropriate imperviousness on the developed site: Area Impervious Runoff Coefficient (acres) % "C" ---------------------- ----------- Lawn 0.16 --------------- 0.00 0.20 Roof 0.10 100.00 0.95 Concrete 0.13 100.00 0.95 Total 0.39 The resultant imperviousness of the developed site is 58.97%. 2. The proposed development results in an increase from 7.69% impervious to 58.97% impervious. Detention is not required because the site is less than 70% impervious. 3. The alley has a minimum slope of 0.70%. Concrete will be used in the alley and parking lot. The alley will act as a channel for the runoff from the site. a. The peak 100-year flow from the site and the portion of the alley that borders the site is 3.49 cfs. This peak occurs where the alley intersects sidewalk along Mulberry Street. b. The capacity of the alley at the minimum slope is 3.35 cfs. c. Grading constraints do not allow an increase in the minimum slope of the alley without adversely affecting the adjoining properties. PAGE 5 Project No. 1151-24-95 Final Drainage and Erosion Control Report V. EROSION CONTROL: A. General Concept 1. Erosion control measures will be as identified on the Final Grading, 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 $1,000.00. 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. i The cost to install the proposed erosion control measures is approximately $ 945.00. Refer to the cost estimate attached in Appendix I. 1.5 times the cost to install the erosion control measures is $ 1,417.50. ii. 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 0.39 acres), we estimate that the cost to re - vegetate the disturbed area will be $ 507.00 ($ 1,300.00 per acre x 0.39 acres). 1.5 times the cost to re -vegetate the disturbed area is $ 760.50. The $1,300.00 per acre for re -seeding sites of less than 1 acre was quoted to us by the City of Fort Collins Stormwater Utility personnel. iii The erosion control deposit for Mulberry Green will be $1,417.50 This deposit is refundable. VI. VARIANCE REQUEST: A. Variance from City of Fort Collins Requirements 1. There will be no requests for any variances from the City of Fort Collins Storm Drainage Criteria for Mulberry Green. VIL 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, the City of Fort Collins policy, and the Old Town Master Drainage Basin Plan. 2. All Erosion Control design complies with the City of Fort Collins Erosion Control Reference Manual and generally accepted practices. PAGE 6 Project No. 1151-24-95 Final Drainage and Erosion Control Report VII. CONCLUSIONS: B. Drainage Concept 1. The drainage design for Mulberry Green is in accordance with the City of Fort Collins requirements and the recommendations of the Master Drainage Basin Plan for Old Town Basin. 2. There will be no adverse downstream effects due to the development of the site. VIH. REFERENCES: 1. Fort Collins Storm Drainage Criteria Manual 2. Urban Drainage and Flood Control District Drainage Criteria Manual 3. Fort Collins Storm Erosion Control Reference Manual 4. Old Town Master Drainage Basin Plan; Prepared by Resource Consultants & Engineers, Inc.; Dated January 7, 1993 APPENDIX I Storm Drainage Calculations FLOW SUMMARY FOR MULBERRY GREEN PAGE 1 DESIGN CONTRIBUTING AREA C2 C10 C100 Tc Tc I2 I10 I100 Q2 Q10 Q100 DESIGN POINT SUB 2,10 100 BASIN(S) ac. min. min iph iph iph cfe cfa cfo r rrrrrx+++++rrrrrrrrrr+tttttrrrrrrrrrrt rtrt+ttrrrrrrrr rrrrttt+rrrrrrrr rrtt++++r+t++rrrrrtrrtrxxrrr+r++ A HISTORIC 0.39 0.26 0.26 0.32 11.00 11.00 2.46 4.31 6.92 0.25 0.43 0.87 REFONLY A DEVELOPED 0.39 0.64 0.64 0.80 5.00 5.00 3.29 5.64 9.30 0.82 1.41 2.91 REFONLY B Ib 0.04 0.39 0.39 0.48 5.00 5.00 3.29 5.64 9.30 0.05 0.09 0.18 OFFSITE KINGS Io 0.04 0.39 0.39 0.48 5.00 5.00 3.29 5.64 9.30 0.05 0.09 0.18 OPPSITE END ALLEYIaa 0.40 0.75 0.75 0.94 5.00 5.00 3.29 5.64 9.30 0.99 1.69 3.49 CHANNEL A Iaar 0.53 0.76 0.76 0.95 5.00 5.00 3.29 5.64 9.30 1.32 2.26 4.67 REFONLY Iaa = Ia & Ialley Iaar = Ia & Salley & Irow SHEAR ENGINEERING CORPORATION PAGE 2 PROJECT: MULBERRY GREEN DATE 06/13/96 LOCATION:FORT COLLINS BY HBO PROJ. N0.1151-24-95 FILE: MULRAT SUBBASIN BREAKDOWN TOTAL SITE AREA = 0.39 TOTAL BASIN AREA = 0.61 Ia & SUB BASINS Ialley HISTORIC DEVELOPED Ia Ib Io Ialley Irow Iaa ASPHALT 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 CONCRETE 0.00 0.13 0.13 0.00 0.00 0.06 0.08 0.21 GRAVEL 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.01 ROOFS 0.03 0.10 0.08 0.01 0.01 0.00 0.00 0.08 LAWNS,SANDY SOIL FLAT < 2% 0.00 0.00 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 0.00 0.00 STEEP > 7% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 LAWNS, HEAVY SOIL: FLAT < 2% 0.36 0.16 0.10 0.03 0.03 0.00 0.03 0.10 AVERAGE 2 TO 7% 0.00 0.00 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 0.00 0.00 TOTAL 0.39 0.39 0.31 0.04 0.04 0.09 0.13 0.40 RUNOFF COEFFICIENT SUB BASINS AND / OR BASINS HISTORIC DEVELOPED Ia Ib Io Ialley Irow Iaa C2-C10 0.26 0.64 0.71 0.39 0.39 0.90 0.78 0.75 C100 = 1.25-C2 0.32 0.80 0.89 0.48 0.48 1.00 0.97 0.94 C100 IS NEVER GREATER THAN 1.0 FOR REFERENCE ONLY PAGE 3 PROJECT: MULBERRY GREEN LOCATION:FORT COLLINS FILE: MULRAT AREA (A)= 0.390 ACRES SHEAR ENGINEERING CORPORATION FLOW TO WEST MULBERRY STREET FROM HISTORIC BASIN DATE 05/22/96 PROD. NO.1151-24-95 BY MHO RUNOFF COBF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.26 0.26 0.32 SHE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (TO OVERLAND TRAVEL TIME (Ti) LENGTH = 200 FEET SLOPE = 0.50 4 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 29.92 29.92 28.26 TRAVEL TIME (Tt)=L/(60-V) FLOW TYPE L (ft) _? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S (i) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S (t) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (£t) _? S M = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S (t) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S 00 = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S (t) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 ALL VELOCITIES TAKEN FROM FIGURE 3-2 TOTAL TRAVEL TIME (min) = 0.00 TOTAL LENGTH = 200 L/180+10= 11.11 < 29.92 CHOOSE LESSER . Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 29.92 29.92 28.26 USE Tc = 11 11 11 INTENSITY (I) (iph) 2 YEAR 10 YEAR 100 YEAR I = 2.46 4.31 6.92 NOTE: INTENSITIES TAKEN FROM FIGURE 3-1 RUNOFF (Q= CIA) (cfe) 2 YEAR 10 YEAR 100 YEAR Q = 0.25 0.43 0.87 CONCLUDE:COMPARE WITH DEVELOPED FLOWS FOR REFERENCE ONLY PAGE 4 PROJECT: MULBERRY GREEN LOCATION:FORT COLLINS FILE: MULRAT AREA (A)= 0.390 ACRES SHEAR ENGINEERING CORPORATION FLOW TO WEST MULBERRY STREET FROM DEVELOPEDBASIN DATE 06/13/96 PROD. N0.1151-24-95 BY . MEG RUNOFF COBF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.64 0.64 0.80 SEE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (Tc) OVERLAND TRAVEL TIME (Ti) NOT APLICABLE LENGTH = FEET SLOPE =NA i 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 0.00 0.00 0.00 TRAVEL TIME (It) =L/(60*V) FLOW TYPE L (ft) = 200 S (%) = 0.50 GUTTER V (fps) = 1.50 Tt(min)= 2.22 L (ft) _? S (%) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S (t) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S (%) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _. S (i) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _. S (6) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _. S M = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 ALL VELOCITIES TAKEN FROM FIGURE 3-2 TOTAL TRAVEL TIME (min) = 2.22 TOTAL LENGTH = 200 L/180+10= 11.11 > 2.22 CHOOSE LESSER Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 2.22 2.22 2.22 USE Tc = 5 5 5 INTENSITY (I) (iph) 2 YEAR 10 YEAR 100 YEAR I = 3.29 5.64 9.30 NOTE: INTENSITIES TAKEN FROM FIGURE 3-1 RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAR Q = 0.82 1.41 2.91 Qhist, 0.25 0.43 0.87 CONCLUDE:THE INCREASE IS ANTICIPATED BY THE SWMM MODEL FOR CONVEYANCE ELEMENT 205 IN THE SWMM MODEL FOR THE OLD TOWN BASIN PAGE 5 PROJECT: MULBERRY GREEN LOCATION:FORT COLLINS FILE: MULRAT AREA (A)= 0.040 ACRES SHEAR ENGINEERING CORPORATION FLOW TO CONCENTRATION POINT B FROM SUBBASIN Ib RUNOFF COEF. (C) 2 YEAR 10 YEAR C = 0.39 0.39 SEE SPREAD SHEET ATTACHED ON PAGE 2 100 YEAR 0.48 TIME OF CONCENTRATION (Tc) OVERLAND TRAVEL TIME (Ti) not applicable LENGTH =na FEET SLOPE =na % 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 0.00 0.00 0.00 DATE 06/13/96 PROJ. NO.1151-24-95 BY MEO TRAVEL TIME (Tt)=L/(GO +V) FLOW TYPE L (f t) = 50 S ($) = 1.00 LAWN V (fps) = 0.70 Tt(min)= 1.19 L (f t) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (f t) =? S ($) = 1.00 NONE V (fps) = 0.00 It(min)= 0.00 L (f t) =? S ($),= 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (f t) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (f t) =? S M = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (f t) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 ALL VELOCITIES TAKEN FROM FIGURE 3-2 TOTAL TRAVEL TIME (min) = 1.19 TOTAL LENGTH = 50 L/180+10= 10.28 > 1.19 CHOOSE LESSER Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR TC (min)= 1.19 _1.19 1.19 USE Tc = 5 5 5 INTENSITY (I) (iph) 2 YEAR 10 YEAR 100 YEAR I = 3.29 5.64 9.30 NOTE: INTENSITIES TAKEN FROM FIGURE 3-1 RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAR Q = 0.05 0.09 0.18 CONCLUDB:THESE FLOWS ARE NEGLIGIBLE PAGE 6 PROJECT: MULBERRY GREEN LOCATION:FORT COLLINS FILE: MULRAT AREA (A)= 0.040 ACRES SHEAR ENGINEERING CORPORATION FLOW TO KINGS AUTO PLAZA FROM SUBBASIN I0 DATE 04/20/96 PROD. NO.1151-24-95 BY MBO RUNOFF COEF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.39 0.39 0.48 SEE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (Tc) OVERLAND TRAVEL TIME (Ti) LENGTH = 2S FEET SLOPE = 6.00 $ 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 4.66 4.66 4.40 TRAVEL TIME (It) =L/(60*V) FLOW TYPE L (ft) =? S ($) = 0.50 GUTTER V (fps) = 1.50 Tt(min)= 0.00 L (ft) _? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 ALL VELOCITIES TAKEN FROM FIGURE 3-2 TOTAL TRAVEL TIME (min) = 0.00 TOTAL LENGTH = 25 L/180+10= 10.14 > 4.66 CHOOSE LESSER Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 4.66 4.66 4.40 USE Tc = 5 5 5 INTENSITY (I) (iph) 2 YEAR 10 YEAR 100 YEAR I = 3.29 5.64 9.30 NOTE: INTENSITIES TAKEN FROM FIGURE 3-1 RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAR Q = 0.05 0.09 0.18 CONCLUDE:THESE FLOWS ARE NEGLIGIBLE R. PAGE 7 PROJECT: MULBERRY GREEN LOCATION:FORT COLLINS FILE: MULRAT AREA (A)= 0.400 ACRES SHEAR ENGINEERING CORPORATION FLOW TO NORTH END OF ALLEY FROM SUBBASIN Iaa DATE 06/13/96 PROJ. NO.1151-24-95 BY MEO RUNOFF COEF. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.75 0.75 0.94 SEE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (Tc) OVERLAND TRAVEL TIME (Ti) NOT APPLICABLE LENGTH =? FEET SLOPE =? 11 2 YEAR 10 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 0.00 0.00 0.00 TRAVEL TIME (Tt)=L/(60*V) FLOW TYPE L (ft) = 200 S M = 0.50 GUTTER V (fps) = 1.50 Tt(min)= 2.22 L (ft) =? S (%) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S (&) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S (t) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S (t) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S (8) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) =? S (4) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 ALL VELOCITIES TAKEN FROM FIGURE 3-2 TOTAL TRAVEL TIME (min) = 2.22 TOTAL LENGTH = 200 L/180+10= 11.11 > 2.22 CHOOSE LESSER Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 2.22 2.22 2.22 USE Tc = 5 5 5 INTENSITY (I) (iph) 2 YEAR 10 YEAR 100 YEAR I 3.29 5.64 9.30 NOTE: INTENSITIES TAKEN FROM FIGURE 3-1 RUNOFF (Q= CIA) (cfs) 2 YEAR 10 YEAR 100 YEAR Q = 0.99 1.69 3.49 CONCLUDE:COMPARE WITH CAPACITY OF ALLEY SEE PAGE 9 FOR REFERENCE ONLY PAGE 8 PROJECT: MULBERRY GREEN LOCATION:FORT COLLINS FILE: MULRAT AREA (A)= 0.530 ACRES SHEAR ENGINEERING CORPORATION FLOW TO CONCENTRATION POINT A FROM SUBBASIN Isar DATE 04/20/96 PROJ. NO.1151-24-95 BY HBO RUNOFF CORP. (C) 2 YEAR 10 YEAR 100 YEAR C = 0.76 0.76 0.95 SSE SPREAD SHEET ATTACHED ON PAGE 2 TIME OF CONCENTRATION (Tc) OVERLAND TRAVEL TIME (Ti) NOT APPLICABLE LENGTH =? FEET SLOPE _? A 2 YEAR 30 YEAR 100 YEAR C = 0.20 0.20 0.25 Ti (min)= 0.00 0.00 0.00 TRAVEL TIME (Tt)=L/(60-V) FLOW TYPE L (ft) = 200 S (%) = 0.50 GUTTER V (fps) = 1.50 Tt(min)= 2.22 L (ft) = 1B S ($) = 3.50 GUTTER V (fps) = 3.67 Tt(min)= 0.08 L (ft) = 100 S ($) = 0.50 GUTTER V (fps) = 1.50 Tt(min)= 1.11 L (ft) _? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 L (ft) _? S ($) = 1.00 NONE V (fps) = 0.00 Tt(min)= 0.00 ALL VELOCITIES TAKEN FROM FIGURE 3-2 TOTAL TRAVEL TIME (min) = 3.42 TOTAL LENGTH = 318 L/180+10= 11.77 > 3.42 CHOOSE LESSER Tc =Ti+TOTAL TRAVEL TIME 2 YEAR 10 YEAR 100 YEAR Tc (min)= 3.42 3.42 3.42 USE Tc = 5 5 5 INTENSITY (I) (iph) 2 YEAR 10 YEAR •100 YEAR I = 3.29 5.64 9.30 NOTE: INTENSITIES TAKEN FROM FIGURE 3-1 RUNOFF (Q= CIA) (cfe) 2 YEAR 10 YEAR 100 YEAR Q = 1.32 2.26 4.67 CONCLUDE:FOR REFERENCE ONLY SHEAR ENGINEERING CORPORATION PAGE 9 CHANNEL CAPACITY PROJECT NAME: MULBERRY GREEN DATE: 06/13/96 PROJECT NO. 1151-24-96 BY MEO SWALE DESCRIPTION: PAVED ALLEY WITH INVERTED CROWN FILE: MULCHAN CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL CHANNEL CONFIGURATION: TRIANGULAR Q100 (cfe) = 3.49 CHANNEL LINING: CONCRETE Da Db Dc Sc n W I (ft) (ft) -_-- (ft) (%) ____ _--- (ft) (ft) ----- __-- ---- -___ 10.00 10.00 0.20 0.703 0.016 0.00 0.05 0.02 = LEFT BANK SLOPE 0.02 = RIGHT BANK SLOPE ' DEPTH WIDTH AREA PBRIM R 2/3 Sc 1/2 Q V (ft) (ft) (s.f.) (ft) (A/P) (cfe) _______ _______ (ft/sec) _______ ______________ 0.20 20.00 ______________ 2.00 20.00 _______ 0.22 0.08 3.35 1.68 0.15 15.00 1.13 15.00 0.18 0.08 1.56 1.38 0.10 10.00 0.50 10.00 0.14 0.08 0.53 1.06 0.05 5.00 0.13 5.00 0.09 0.08 0.08 0.67 0.00 0.00 0.00 0.00 0.00 0.08 0.00 0.00 #t#i*tftifif4f)t*fffit#4*t#fftifi iitk#fk*44#titiifiifffiikf *4##iiYf iiifftRt DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V (ft) (ft) (a.f.) (ft) (A/P) (cfs) (ft/sec) CONCLUDE:ALLEY CAPACITY IS ADEQUATE BECAUSE THE CROSS SLOPE AND THE FLOWLINE INCREASE TO 3.3% AND 3.2% RESPECTIVELY AT THE SIDEWALK. THEREFORE THE CAPACITY IS INCREASE AT THIS POINT SHEAR ENGINEERING CORPORATION PAGE 9 CHANNEL CAPACITY i PROJECT NAME: MULBERRY GREEN DATE: 06/13/96 PROJECT NO. : 1151-24-96 BY : MHO SWALE DESCRIPTION: PAVED ALLEY WITH INVERTED CROWN FILE: MULCHAN CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL CHANNEL CONFIGURATION: TRIANGULAR Q100 (cfs) = 3.49 CHANNEL LINING: CONCRETE Da Db Dc Sc n W I Aft) (ft) (ft) (1k) (ft) (ft) ____ ---_ ---- ____ ----- --_- -_-- 10.00 10.00 0.20 0.703 0.016 0.00 0.05 0.02 = LEFT BANK SLOPE 0.02 = RIGHT BANK SLOPE DEPTH WIDTH AREA PERIM R 2/3 . Sc 1/2 Q V (ft) (ft) (s.f.) (£t) (A/P) (c£s) (ft/sec) ------- ----------------------------------- -------------- 0.20 20.00 2.00 20.00 0.22 0.08 3.35 1.68 0.15 15.00 1.13 15.00 0.18 0.08 1.56 1.38 0.10 10.00 0.50 10.00 0.14 0.08 0.53 1.06 0.05 5.00 0.13 5.00 0.09 0.08 0.08 0.67 0.00 0.00 0.00 0.00 0.00 0.08 0.00 0.00 r xxttxxx+rrrrr++++txt+++rrrrrtttrtrxtr+rrrrrrr+++++rxrr+r++x+++r+rrrrtrx DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V (ft) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec) CONCLUDE:ALLEY CAPACITY IS ADEQUATE BECAUSE THE CROSS SLOPE AND THE PLOWLINE INCREASE TO 3.3% AND 3.2% RESPECTIVELY AT THE SIDEWALK. THEREFORE THE CAPACITY IS INCREASED AT THIS POINT SHEAR ENGINEERING CORPORATION PAGE 9A CHANNEL CAPACITY PROJECT NAME: MULBERRY GREEN DATE: 06/24/96 PROJECT NO. : 1151-24-96 BY : MEO SWALE DESCRIPTION: CURBED CONCRETE CHANNEL BETWEEN UNITS 2-8 AND EAST PROPERTY LINE. SHE DETAIL ON SHEET 6 FILE: MULCHAN CAPACITY OF TRIANGULAR OR TRAPEZOIDAL CHANNEL CHANNEL CONFIGURATION: RECTANGULAR Q100 (cfs) = 0.18 CHANNEL LINING: CONCRETE Da Db Dc Sc n W I (ft) (ft) (ft) (%) (ft) (ft) ____ ____ ---- -_-- _____ ____ ____ 0.001 0.001 0.56 0.400 0.016 2.00 0.05 560.00 = LEFT BANK SLOPE 560.00 = RIGHT BANK SLOPE DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V (ft) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec) _______ ______________ _______ ______________ _______ _______ 0.56 2.00 1.12 3.12 0.51 0.06 3.33 2.97 0.51 2.00 1.02 3.02 0.49 0.06 2.91 2.85 0.46 2.00 0.92 2.92 0.46 0.06 2.50 2.72 0.41 2.00 0.82 2.82 0.44 0.06 2.12 2.58 0.36 2.00 0.72 2.72 0.41 0.06 1.74 2.42 ++x+++++++++r++rtrxxxxrt+rt+x++++rt++r++++rrrrrrrrrx+xxx+rt++++++r+++rrrtxrx DEPTH WIDTH AREA PERIM R 2/3 Sc 1/2 Q V (ft) (ft) (s.f.) (ft) (A/P) (cfs) (ft/sec) CONCLUDE:THE CURBED CONCRETE CHANNEL AT MINIMUM SLOPE IS ADEQUATE -WN BASINS #1,02,/3 ..100 YR STORM.. FUTURE CONDITIONS L.,-.NE/BULL FARM CHANGES..220/90/220 CPS NEW MERCER CAP ... ADD'L IMPERV COLLEGE ... PEAR FLOWS, STAGES AND STORAGES OF GUTTERS AND DETENSION DAMS **• CONVEYANCE PEAR STAGE STORAGE TIME ELEMENT (CFS) (FT) (AC -FT) (HR/MIN) 238 125. (DIRECT FLOW) 0 45. 213 156. 1.1 0 50. 233 156. (DIRECT FLOW) 0 50. 235 146. (DIRECT FLOW) 0 50. 234 10. (DIRECT FLOW) 0 50. 210 120. .9 0 40. 209 99. .8 0 40.., 212 140. 1.1 0 55. 208 185. 9.1 0 40. 207 249. 9.3 0 45. 132 176. (DIRECT .FLOW) 1 0. 221 140. (DIRECT FLOW) 0 55. 232 86. (DIRECT FLOW) 0. 55. 206 581. 3.8 9.1 1 0. 222 99. (DIRECT FLOW) 0 55. 211 122. 9.0 0 45. 205 696. .0 2.9 1 0. 230 195. (DIRECT FLOW) 0 50. 227 696. (DIRECT FLOW) 1 0. 113 86. .8 0 40. 117 15. (DIRECT FLOW) 1 0. 231 109. (DIRECT FLOW) 0 50. 228 577. (DIRECT FLOW) 1 0. 127 86. (DIRECT FLOW) 0 40. 107 81. 8.8 0 40. 217 486. (DIRECT FLOW) 1 20. 338 0. (DIRECT FLOW) 0 0. 204 669. .0 11.1 1 5. 128 43. (DIRECT FLOW) 0 40. 106 160. 9.0 0 40. 344 436. (DIRECT FLOW) 1 25. 342 486. (DIRECT FLOW) 1 20. 314 10. 1.5 2.4 1 35. 307 91. 1.8 2.2 0 40. 223 41. (DIRECT FLOW) 0 55. 224 669. (DIRECT FLOW) 1 5. 126 159. (DIRECT FLOW) 0 50. 105 279. 9.3 0 40. 311 438. 9.6 1 30. 343 50. (DIRECT FLOW) 1 20. 313 41. 8.5 0 40. 306 82. 2.0 5.5 1 15. 225 637. (DIRECT FLOW) 1 5. 115 223. 1.2 0 55. 104 320. 9.3 0 45. 357 438. (DIRECT FLOW) 1 30. 312 67. .9 0 40. 305 139. 3.0 4.5 0 55. 203 612. .0 5.9 1 15. 114 82. .8 0 40. - 129 43. (DIRECT FLOW) 0 40. 130 223. (DIRECT FLOW) 0 55. RCE ref:90-411 - Sept. 16, 1993 APPENDIX II Erosion Control Calculations Erosion Control Sequencing schedule Erosion Control security deposit estimate RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: STANDARD FORM A COMPLETED BY: DATE: ¢ �b DEVELOPED ERODIBILITY Asb Lsb Ssb Lb Sb PS SUBBAgIN ZONE (ac) (ft) M (feet) M M U .31 zoo 0.5 7 0,o� TD o.o 2� Z SAY 4-7 p,s U.65 i•U -A-L 11�Yi L� g� 161 7ZI Zoe MARCH 1991 8-14 DESIGN CRITERIA o rnrn000 o v4totoIn in ODOD00Ooo o mmm0000000 o 4 4 44U;llitntnlntn v WW000000000oCocOco 0 CDOtrnOnrn(AONDtrnON0C%000 . . . . . . . . . . . . . . . O 444444444444InU;to M O000DOCDtpCOOtOCOOlb00Olb o rc000coo�rnrnrnrno+o+o+o�mo�o+rno�o�rn . . . . . . . . . . . . . . . . . . . N 00 CO O O 00 O W 00 CO CO 00 W O OD O CO 00 O CO O o OM V 0 0 W W0r,rnrnrnrnrnr000o0000CID 00 . . . . . . . . . . . . . . . . . . . . o ❑ H OD000o0000oocotoOwco000000COCO000oowOCID o 0 OoNM-qru)totn%D%D%D%a%D%orrrrnrnnrrCOCIO 00 p 00 � 00 00 O O CO 00 O CO 00 00 00 00 c0 co 00 co 00 00 co CO OD 00 co 00 co co U O t0 O N M V' V' 111 to In IL1 t0 t0 tD t0 tD t0 t0 t0 t0 t0 r r n r r n . . . . . . . . . . . . . . . . Cn O c�1V'44; V'44V'V'44 V' V'444444V'V' 4V'V' z 00 CO 00 00 00 O O 00 O OD O O O CO 00 00 CO 00 00 00 O 00 CO 00 00 O H a O V'OtHNMM V' V' V'vtnLnLntnlnLnu)tntnwtDw%Dt0tDn a O n cnr�v�rav����r�v�vwvwv�rv���r�sry U aoo0ooa0000oaowomoo0oa0000000000�o� E-4 O 0 w w 0 H H N N m m m m V I*--W-' V'lw KrvLLltntnmw 0 x °, to oMo 0mw owm�m ow o�m ow o oa�oo�o oo�o oo�ow�m�w o ..o 0NIt)nOm00HrgHNNNNNMMMMM w v v CT'%T 1 o de . . . . . . . . . . . . . . co Cs. ..iln N M M M M M V' V' -0 V q v V' V V' V V' V' -0 V' V' CO OD CO O OD 00 00 O OD O CO co co O 00 CO 00 CO 00 00 Co 00 CO 00 CO CO W N W .a❑ aIn HOOHMvtototDtDtorn000000Co0000mrnrn00000 Q.' R C a d' N N M M M M M M M M M M M M M M M M M M M d' V' d' 4; Er❑ N OD 00 co Co 00 00 00 00 CO OD CO OD CO CO CO CO OD OD 00 00 OD 00 co co 00 co 0 tDInODOHNMa V'InIntot0tDWtDtDnnrroCoCoOtOl H . . . . . . . . . . . . . . . . . . . . . . . . . . En V' H N N M M M M M M M M P' ) M M M M M M M M M M M M M M COOCO0000OD000000 W OOOD0000OOD00OD00CDCOCOCD00OD W U to HHtonooOHNN MMMsr V'-w V V to to totDt0Wrr z . . . . . . . . . . . . . . . . . . . . . . . . . . . M H N N N N M M M M M M M M M M M M M M M M M M M M M Co co CO OO oo 00 00 00 Co 00 OD CO 00 OD CO O CO CO CO 00 00 OD OD OD CO 00 p O C7NtD00010HNNen(nm v V w.0 v a7lnM Lnlnt0t0%Dt0 W . . . . . . . . . . . . . . . . . . . . . W M O O0 CO O0 O CO O OD O O 00 00 O0 O O OD 00 CO 00 00 00 O CO 00 CO O a to InInrnNMvtntDrrrcoo0000,o+rnrnrnrn000000 ,a . . . . . . . . . . C. N r000DOD000000OD00000000ODODCOCO00ODOD0000OD00000000 Ga Z O V'InOMIf1tDOD0001000HH.-�IHNNNNMMMMMM H . • . • • . • . . • . . . N coON0000000H H1-1HHHH.-IHr1HHHHrIHH n r 00 Co 00 00 00 CO 00 CO OD CO 00 0o CO 00 00 Co 00 00 CD 00 CO 00 00 00 In ON COH V'IA- n n0 M Ot O O H H H H H N N N M M M M M H tpCOCOO;O�OOo000 nnrnnnnnnnnc0000oco0o00mcocococowooww O w m 0 V'n01OHNM m-cr -cr m 0 mm%Dt0t0%Drnt0tDt0 H V'10nnnnCtl000OCOCDOCo000000CDOCOCCICOCOCD000DCO rnnnnrrrnnnnrrnrnrrrrrnrnr In D,o V tDr W COrtrrtGtotDtn V V mmc%aN %D-w ON %0 . . . . . . . . . . . . . . . . . . . . . O ONNNNNNNN NNNNNNNNNNNHt- r;1400 rnnrrrrrrrrrrrrrrrrrrrnrrr x 00000000000000000000000000 O O H 00000000000000000000000000 azk+ .-INC1dInt0n000tOHNM V IntOrCOHNCNcnmv V U) W Wes, HHHHH.-IHHHHNNMM V' V'In a EFFECTIVENESS CALCULATIONS PROJECT: I�U1.>3�'r��si { 6RC >u STANDARD FORM B COMPLETED BY: _ 1�EUJ 51}�,� ��(,1�1L�na�� DATE: Erosion Control C-Factor P-Factor Method Value Value Comment CQJV f�ICF-` U.U� I.0 iUhlC, ��Oi1 10 U•RO 5;14 �cavL� 1'U 0,0-1 So Apall �i� MAJOR PS SUB AREA BASIN BASIN (Ac) CALCULATIONS �2•gb 1� U' .31 GiNcokc. U.13�, Gm-t-Grao0A 6,0Z u. Sor� O,\o ., .(,�3t,lu) I,u(,u3�o.35 = 1U C Cool+ 0.21 0,5'xo:(X� LU�a3t,lU�+ U:,�o•Uaoa3 �Z11oX,3oh1) ►YIUU= �3.��• l: o.�7 i C = C o.ol (I,u) t ,G3� •ul)� I ,U� — �,� �� 5 6 Fr =tl — (-Z�-y'w6d)] x,o 0 MARCH 1991 8-15 DESIGN CRITERIA CONST SEQ M-client/Maxwell/Erosion/ConstSeq CONSTRUCTION SEQUENCE PROJECT: Mulberry Green STANDARD FORM C Project No: 1151-24-95 Date: 3/28/96 Revised:04/03/96 SEQUENCE FOR 19 _ONLY COMPLETED BY:MEO/Shear Engineering Corp. Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. Year 196 Month J J A S O N D OVERLOT GRADING *** WIND EROSION CONTROL * Soil Roughening *** Perimeter Barrier Additional Barriers Vegetative Methods Soil Sealant Other RAINFALL EROSION CONTROL STRUCTURAL: Sediment Trap/Basin Inlet Filters Straw Barriers Silt Fence Barriers *** *** *** *** Sand Bags Bare Soil Preparation Contour Furrows Terracing Asphalt/Concrete Paving *** *** Other VEGETATIVE: Permanent Seed Planting Mulching/Sealant Temporary Seed Planting *** *** Sod Installation Nettings/Ma ts/B l anke is Other 97 J F M A M J STRUCTURES: INSTALLED BY: OWNER MAINTAINED BY: OWNER VEGETATION/MULCHING CONTRACTOR: OWNER DATE PREPAREDA/22/96 DATE SUBMITTED: 4 22 6 APPROVED BY THE CITY OF FORT COLLINS ON: May 23, 1996 Project No: 1151-24-95 Basil Hamdan City of Fort Collins Stormwater Utility P.O. Box 580 Ft. Collins, Colorado 80522 Re: Erosion Control Cost Estimate for Mulberry Green Lot 4, Block 105, Harrison's Addition; Fort Collins, Colorado Dear Basil, Attached is the erosion control security deposit estimate for Mulberry Green. ESTIMATE 1: 315 LF of Silt Fence ® $ 3.00 per LF TOTAL ESTIMATED COST: ESTIMATE 2: re -vegetate the disturbed area of 0.39 acres at $1,300.00 per acre TOTAL ESTIMATED COST: $ 945.00 $ 945.00 x 1.50 $ 19417.50 507.00 $ 507.00 x 1.50 S 760.50 In no instance shall the amount of the security be less than $1,000.00. Therefore, the total required erosion control security deposit for Mulberry Green will be $1,417.50. If you have any questions, please call at 226-5334. Brian W. Shear, Shear Engineering Corporation BWS / meo cc: B.K. Maxwell Company, Inc. Dave Stringer, City of Fort Collins 4836 S. College, Suite 12 Ft. Collins, CO 80525 (970) 226-5334 FAX (970) 282-031 1 May 23, 1996 Project No: 1151-24-95 Re: EROSION CONTROL SECURITY DEPOSIT REQUIREMENTS: Erosion Control Cost Estimate for Mulberry Green Lot 4, Block 105, Harrison's Addition; 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. i The cost to install the proposed erosion control measures is approximately $ 945.00. Refer to the cost estimate attached in Appendix I. 1.5 times the cost to install the erosion control measures is $,1,417.50. ii. 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 0.39 acres), we estimate that the cost to re - vegetate the disturbed area will be $ 507.00 ($ 1,300.00 per acre x 0.39 acres). 1.5 times the cost to re -vegetate the disturbed area is $ 760.50. The $1,300.00 per acre for re -seeding sites of less than 1 acre was quoted to us by the City of Fort Collins Stormwater Utility personnel. CONCLUSION: The erosion control security deposit amount required for Mulberry Green will be $19417.50. 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 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 witch a minimBusiness umstrict — lot area equal to 1 /2 ofs an the totarea of lfloorta area of the building. busi- nesses 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 Runoff Coefficient Character of Surface 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 Average 2 to 7% ............... 0.25 0.35 Steep>7%......... :................................................................................ MAY 1984 3-4 DESIGN CRITERIA 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 1.1CC,) Dtr2 S'3 Where Tc = Time of Concentration, minutes S = Slope of Basin, % C = Rational Method Runoff Coefficient D = Length of Basin, feet C, = 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 Stone Return Period Frequency Factor (years) C, 2 to 10 1.00 11 to25 1.10 26 to 50 1.20 51 to 100 1.25 Note: The product of C times C, shall not exceed 1.00 3.2 Analysis Methodology 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, cis A = Total Area of Basin, acres Cf = Storm Frequency Adjustment Factor (See Section 3.1.8) C = Runoff Coefficient (See Section 3.1.6) 1 = 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 analysis. This procedure is detailed in the Urban Storm Drainage Criteria Manual, Volume 1, Section 4. MAY 1984 3-5 DESIGN CRITERIA DRAINAGE CRITERIA MANUAL RUNOFF 50 30 t— 20 z Cr U w 0. 10 z w a O 5 U w cc 3 0 U 2 w F- Q 1 =MN111111� ����I�lpffm ' r mill .• I0111110 ��� ► •I Il mw■mm� ■ Ili LAN■Ca .� =Mw■■■■�■ ��►�■M��►%■�ii �MMMN NN■� 2 .3 .5 1 2 3 5 10 20 VELOCITY IN FEET PER SECOND FIGURE 3-2. ESTIMATE OF AVERAGE FLOW VELOCITY FOR USE WITH THE RATIONAL FORMULA. *MOST FREQUENTLY OCCURRING"UNDEVELOPED" LAND SURFACES IN THE DENVER REGION. REFERENCE: "Urban Hydrology For Small Watersheds" Technical Release No. 55, USDA, SCS Jan. 1975. 5 =1-84 URBAN DRAINAGE & FLOOD CONTROL DISTRICT No Text Appendix IV Portions of the Old Town Master Drainage Basin Plan e l I li[i[iliji IiII111,111 Scale: 1"=1 mi a to Figure 1.1: GENERAL LOCATION MAP OLD TOWN MASTER DRAINAGE BASIN PLAN for the CITY of FORT COLLINS 1.2 � LLJF o m �I ce W J m u LU usO gE ZU 5 { \. rn LLJ N ¢OOG b O n ZKZO—o rrU IJ Jo wap ii N O:FmU , .JLj JINX El co dT' I of �.lr—Ir r , r - ILI _ r V i I I 1 I Ir Ii i v j�j J - — .��—� r----�I Lf - H. _+•_�-�'L�u—I�_mx. II Q. !II f( l II.Ilnr 3nN ��� r CaO - - li IRE 0 d E 1 ooz> > (u j u < oO �j Y'CNV 2:C <2. CO < �= 00 J O)N I Lo LZ Ln 0 �C<o U CAI A F T L UN Storage functions were used at elements 203, 204, 205, and 206 in Subbasin 2 to simulate the ponding of floodwaters behind the various north -south streets with high crowns. During the 100-year flood, these ponds filled before the peak runoff. Once filled, the ponds did little to attenuate flood peaks;.the inflow rate essentially equaled the outflow rate. However, this was not the case with the less severe storms. -Snlitter functions wer . is .d at elements 997- B-229 and' 4 5 99to idistributp ois rom t r oon Ana areas hehind Colle.oe and M con to either the dnwntn�a area nr Mvrtle Street Splitter functions were used at elements 215-216-217 and 218- 219-220to direct a portion of the runoff near the intersection of Myrtle`and Peterson Streets into Subbasin 3. Splitter functions were also used at elements 324-325-326 and 327-328-329 to determine the amount of water that would be carried under Riverside through the storm drains and the amount that would be left flowing down Riverside parallel to the railroad tracts. A splitter function was used at elements 357-358-359 to account for surface returns back to Mulberry along Smith Street. Runoff in Upper' Part of Subbasin 3. In the upper part of Subbasin 3, most of the flood runoff, which included spills from the Larimer County Canal No. 2, collected along Elizabeth Street. The runoff moved across Shields and onto CSU property. Storm drains diverted some of the runoff to the south and into the Spring Creek drainage, although most of the runoff flowed across CSU through the intramural field and eventually discharged into ' an open reach of the Arthur Ditch. The Arthur Ditch diverted much of the intercepted flood runoff into a box culvert that extended under the CSU campus. The culvert, in turn, carried water out of the Old Town drainage and into the Spring Creek drainage.' The , I capacity of the open reach of the ditch was exceeded during the course of the 100-year flood, resulting in excess waters spilling into the CSU lagoon located immediately downstream of the ditch near the CSU Student Center. Routing and storage of floodwaters in the Arthur Ditch and CSU lagoon were simulated through the use of splitter functions at elements 353-354-355 and 336-337-338 and through the use of the storage function for element 315.- It was assumed that the Arthur Ditch was carrying 60 cfs of irrigation water for the duration of the flood. It was estimated that the ditch could carry an additional 35 cfs before water. would overtop the ditch banks and spill into the CSU lagoon.' Inflows exceeding 35 cfs were routed into the lagoon using the splitter function for elements 353-354-355. It was further estimated that releases through the Arthur Ditch box culvert under the CSU campus would increase once the water elevation in the lagoon reached the top of the open ditch. The dam creating the CSU lagoon is higher in elevation than the Arthur Ditch. Estimates for the additional surcharged capacity of the box culvert were incorporated into the release rates for the storage pond function at element 315. Surface spills, which would result from a complete filling of the lagoon, were simulated to occur first at the low spot near the intersection of Pitkin and Center Streets and then over the top of the dam itself near the Student Center. The splitter function for elements 336-337-338 was used to distribute any surface spills. Surface spillage did not occur from the lagoon for the future condition runs. The regional detention pond near Skyline and Elizabeth Streets coupled with improvements to the Larimer #2 Canal, reduces the current spilling into the Old Town Basin. The future condition runs assumed those proposed improvements. The simulated spillage from the lagoon for existing conditions was all to the south, near the intersection of Pitkin and Center; no spillage occurred over the top of the dam into the lower part of Subbasin 3. 4.18� Table 4.1. Design Storms for Old Town Basin. Time Penod ::.:,x Rainfall ....... . . ....... ..... Infenq,ie .. ........... . .......... .. ........ . . . ....... ... ........... . . Entlirg ...... ........... ......... ... . i% �i;:: m ear 5 Year Y 25 yia, b:Year . 5 0.12 0.36 0.48 0.48 0.60 10 0.36 0.60 0.60 0.72 0.96 15 0.48 0.60 0.72 0.96 1.44 20 0.60 0.84 0.06 1.32 1.68 25 0.84 1.56 2.16 2.28 3.00 30 1.80 2.52 3.12 3.72 5.04 35 3.24 4.68 5.64 6.84 9.00 40 1.08 2.04 2.28 2.88 3.72 45 0.84 1.08 1.12 1.56 2.16 50 0.48 0.72 0.84 1.08. 1.56 55 0.36 0.48 0.72 0.84 1.20 60 0.36 0.48 0.60 0.72 0.84 65 0.36 0.48 0.60 0.72 0.60 70 0.24 0.36 0.48 0.48 0.48 75 0.24 0.36 0.36 0.36 0.36 80 0.24 0.24 0.24 0.36 0.36 85 0.24 0.24 0.24 0.36 0.24 90 0.12 0.24 0.12 0.36 0.24 95 0.12 0.12 0.12 0.24 0.24 100 0.12 0.12 0.12 0.12 0.24 105 0.12 0.12 0.12 0.12 0.24 110 0.12 0.12 0.12 0.12 0.24 115 0.12 0.12 0.12 0.12 0.12 120 0.12 0.12 0.12 0.12 0.12 at hand, recognizing that it is always possible to make additional refinements or revisions to any model. 4.1.2 Basin Subdivision As can be seen from Figure 4.1, the Old Town Basin below Larimer County Canal No. 2 was subdivided into three smaller subbasins numbered 1, 2, and 3. Subbasin 1 encompassed the area in the northern part of the drainage; Subbasin 2 encompassed the central part, including the downtown area; and Subbasin 3 covered the southern part. Each of the subbasins was drained by a major storm sewer. 4.3 w. Table 4.3. Differences in Impervious Area Percentages for Existing and Future Conditions. . ..... .. . ... . ..... . I .... .. u6catcli m 6 nt PercentImpervious' . R N Urribb Existing ,.: :u.:ure: .. . ... ... 6 40 70 102 50 70 108 40 60 109 40 60 201 40 60 203 50 70 204 60 70 205 50 70 206 40 60 211 40 60 304 40 60 305 40 60 312 40 50 360 20 40 361 60 100 M z 0 < ow z Z < Q) ........... LLJ T CZ 77i < ZQ 0 P w LLJ 1 M In Z LLJ 08. W <U- In OW_i CL 0 F— OW 00 LLJ R Off \Wl �11. d %- .m 0 1 [D M lO ID co 00 00 rz 00 co M O Cq N M m M a v m 00 m °' m m m m m 0) m D) m m a a a a a a m a m a m a aa) a a 0 c � u0i o u0i v0i M M M o O o 0 00 0o CO co 00 M 00 00 Do n M On 00 0o M n W. .; M t0 to e- n 00 0o O a (D N a U) 0 Lo a 0a0 00 M n CO M 00 O cn N N M M M to 3Y a a v v a v a m 0) m m m m m ro a a a a a a a It o ,g m 3 o O o O o O o O 0 0 0 O O M M c co (0D M O O M •Y i 'iiQiii`i:ii`?, N N M M O W co M M (D IO ID 00 M a M M O) t^ _i ' N 00 co O 00 N M M M M a V7 0o 00 W a a a v v a a N � w )n 0 0 m 0 0 0 0 0 0 o 0 0a > w N N N N N in N LO co o co O coo co p Y O N N N M N N N N ED W .. O O .- M M w O � N .- N N 00 N N M 00 co 00 CO co 0) N M M M M a )O 3CY) oI m a a a a a a a a a a a a a a a Q lL 0 3CD O �' 0 0 0 O O p N O 003 M m ao M O` O O LL W r. m 0 n I a U) r. r. n O •- N •� :: CO oaD co 00o m Di ai .= N Cl) 00 of Cl) v _ 3 a a a a O1 °' a a a a a v O1 a a a co TD ~ 3 0 m a a a a O a O a o O N o M 0 0 w a M 0 0 0 o m M Cl) 6 m 6 M M n LO o) a m 0 n C •K 00 a co c0 00 O 00 o) 00 00 c0 O) O •- — —N M C` 10 A M W M a a)0) o) 00 D) o) m a a a a a a a a a a m 7 C C 0 C O O co coO O O r, O O O 00 00 O m V tO 00 On- M toO O O M 00 M N M 1D r0 0) O <D n OD n O co co W O L U L z° 07 a a v a a a a a U m v e in�; a Ll 5.17 m (D o a 0 a m m 00 00 m O m co (� (D m n to n m a m a m m 0 0 °' °' (D D' n °' D( n m m C00 a a m } o u»" o 0 0 0 0 0 0 o o o o 0 0 j Wes, n n n n n f0 a _o m 0 (o (O N M M M fD O m CD vn M M a m to O M N 0 M n .., m m m m 0 fD n m a (D Cn0 m m m m p (O m to m M m n m n m n n a00 000 m m m m m o: 0 0 0 0 O O O O O O O O O O w (O 10 (O OD M co N co M Cl) N m 00 N N Cl N N 0 O M 0 C U W n (D Cl) N N M n M m 10 M N n U .. N •�' m m m m O to n Cn M 1q O O O O 01 m o to m (D CD n n n n n 00 00 m m m m m m m m m m r m } LL y. O O 00 O O O O O O O O O O O O C m V; LL :: N 40 N 00 N 00 N 0 NC) 10 m m N a M 0 111 0 O O Y Q N (`a') ca Qi N M O N O wm n co mo mm m (: n n co ao mo 0) a) m m r, m m naa0 m m m v C3 iy fmmmo m Go O O o o o O o 0 p n > m m M n LL rn m CO m a-- y •� (D n m m O 00 (O n D( n n n in 3 m m m m 0 (D CD n 0) n 000 a a a a (O a a a a a a a a a a> m: t0 w H O �, O O O O 0 O O O O O Otoo W - - .- au a a m � m s m O m °� m a O n °� m a GO m m a m °> m a n m m m a CD w (D m a 00 0 (D m v O a)O (D m a n m a m N n m a m M n m a CG (D n m a O n n m a m n m a O OLei 00 m a c U [f On m O m m m 0 M O 0 0 O � O m M (D O O 0 m m O N 0 N t U co cc t U m ) fD 0 n O 00 0 m 0 O 0 00 (ND 0 co 0F rl (D co (D mD (DC) On !aC� APPENDIX V Stuffer Envelope Master Grading, Drainage and Erosion Control Plan S S let — v. i tot J, It w Ztd, X- 3 16, c It 1-t-3-11-.1" Z. locy 7 ot 441 W,THf:Ir1a:11,Y1�.TI:RB]�RS:fl F.f�, iL13; LEGEND NOTE: MLVLMIIM ALLOWABLE. FMOHBD FLOOR I r Ill V Rum J.uq mYmmA o d .rmA ELEVATION L9 MEN MICE INORDER TO PROVIDE Ian Cyly Srxrldypwy.is, .nmyy 61lAFMABYOPLNI'ERVIOL'1MFSSF46 IRE REQUIR 1.5 SEPARATION FROM IMH 100. dmaeYrt rrLmwmrms.y 9.mra.M �G SITE YEAR FLOOD ELEVATION NOTED M ME OLD Vasw•J 3xdw.nrl P•alP rtl6�•: fa„eI N•+ rr PxvlrvrAw —•—BASDi BOUNDARY TO" MASTER DRAINAGE BASH PLAN. THE 100- supwit ammry^•^+""b"I"d'r N'n q'°' ICI u�,„%'w.. xm.rt c.:m.bm .�qs As YEAR FLOOD ELEVATION IR 535 ACCORDING TO _e. _ _ _OFFER v se BASIN DESIGNATION THE OLD TOWNMASIER DRAINAGE BASIN PLAIN. 2 TYPED aR d Kam oxti. ale m by q...ee a.U^ Ium 9w Iw�w ).10 aaR, w " u..u,r nm:,.Yxws r.11'xu mw.. Pl.vs Isms 9a) O CONCENTRATION FOUNT FINAL GRADING LY THE ALLET SHALL MATCH ^r �+.• a ID]ro Noll 0 9aIMP'N is SWUC VIVO' THE EXISTING ELEVATIONS ON THE WEST SIDE 3. a mw.n�m .Al.xb I,x .m:pr .n as, Saw, d T"1 - W. ist— FLOW DIRECTION OF IHEALLEI'. I Colm:bmpwtixrF®Im •Rw�.le, 1M.,Wp Tr..�Y.MWpenb^m. d.WnYle{Wsulbaa. r���r . � �: �I. r.W�x�r. 19az3V EXISTING ELEVATION AVAw1 dla Cr�r AN.Y).• b Nm:w:mSIR I 2' 9PII�� Cob.0 o., d HSISa . Q+IKy Cm�a:.J m. w�vMD1Ow Owy C...k SUMMARY OF LaS"VIOU3IN%S FOR. TALIA Irr. rTslvgl�. .... PROPoSED ELEVATION Dnn Smnx D• PSC mmm MONE I5w N DEVELOPED SR'E D�6� (' MimeWlelminaa 5aU¢ PaeOOLO 3JSW.r 8 Mn Am MRa.mm wrcmm.::. NMm""IN3 mom"" rrAvrel a C Amn•iY u m tr :r m mJl mtiJy,hn •Sus (Soul f �IInIr QwuW WusrW, VuyE Rmm vREPPE PRO P,,, INS EROSION CONTROL LEGEND RN Ir K .I-.m„ m W. _ mr,. Val —0;6 -am — am wend9eu�m.l a Iwro N.D m 005 SILT Y. KID HAYBALNCE I T v SIN. •m ,,.In.l� i�0.`� 'rwr u]v �Ni:.=.I ma, r F,......,Y.�.+. W tlAYBA1.E BARR2EB lY.�eY.w y..rxrdlY,Nrtbr•<oeY58nt cam 9:111 AALE^ V. LIP UTO INS III \ __ YYtrll �yta.. LYENGS A P A R K N c RI, as d R ..uL�..•r := .""".' v,a::.. xvro,ua...., ..u..a.x i. S T N G "EA S I 6 AY 0s6Ra ! Y• 21R1 o.'vM Arl• ram CONCRETE BLOCK AND FRAME YM,N�N•N3•r I��A8yyEm m I SEMICE GARAGE AND OFFICE tr 2�'Oi tl \ all 1 M" L a w1wOmNw I FINISH FLOOR 6996.)) I RW 9.n. w I3tr"rU ,a.Rlf.Am II (: KEDGE OF ASPHALT .N i,rarYl�Nr•iY Va mY•F•Wvf w.�.�lrtry `.��`INArerYYMYim�.A.x,a I. Y 9 aa� PARKING LOT LIGHT (TYPICAL) P�Nr M..•MKa.A.SKF+iAt Fn E •pl rlxY,e.avu 4a�rLr„rL.wiI8r11wA V r.jAE.„5^> wl n II ARE F, CRISP IWAY"W Re M1 a ''En _ M1al I ° l�P 9J.[9:. � � _ _A 9 ])) .�a Mv. r,v.Y a Fm MwIq.WF.. (93 US . - ur A�= bN W.. :... fM NJSE� I ... �F CE,N...mo+.rw4mw�.:®.mwa F I I F.F. 98.3 F.F. BILL LF. 96.7 F.F. 65.E lb CONMUCDON SEQUENCE A I F.F. 9fA jF'FtW89)5 PRIPPRIP FF. 95.0 0.01AC. 4 .u• Fj v I 6 7 AC• PRW3 : ALAAI Gram II.j rOw C v1. SE9VLYCe lox isONLYIF Pill „„�D' t� J DO 4 )N9 x.N, Ir � F.F.9 LO a•1Ell 7 TtJ�5�)�� ' ;LF> a D, " < PER_ la W — C!— �x O.OIAr A� N a ONLY) Frt T� ,:,ry _ ... ......(IIIONLY)u : AnVL ( u .x I ONE STORY BRICK RESIDENCE 0 i _Pluramm le I jo � WITH BASEMENT � I N�4aNmfl..m J NHR 9 f I FRAME r,NLY n OSYn...:::::,. 9FENEH __ — . I•' r Al la d, OW GARAGE w .L.rE wTruxai 1 Yo:x, TxNw uwnlw A 9im cF .,,Y,,.w..,��..:,.wu..A U..,,a. ___j L Ay as a 9, f A • .. n. r•, „s. m w is • ` +. I 1 alley A PAT RISE o� ay, ® �•u I Ed 0.0 SAO je 4 —{p •t r APHILL •alkt Pr —I — P—•�CJ ,x VW`T R�W y •~� —P x uP ��L—� munm Ia•�x,mu w�a•W. •.a. LIP 1 RISER l a LINE OF 029 4 ... ... J I P'l „, •,,R'r +,•�. W , . .., .... •.. City of Fart Colonel, Colorado II 1 < I La JTIII PLAN APPROVAL EXIST. BERM TO REMAIN ... 'LIP L -06 L I „..„m,.x...R.v .... s, n. I. ,. a ... 11" w all 91„ ,Rm .. .. .... PIPE 1. ARNWE' N PLACE DURING CONSTRUCTION DIRECTOR OF munmiwo am IN PLACE OF SILT FENCE Iw. a... ... II .... I.) m. w. ,•• FEES ,„ n. P. .,. ....... ...... • •n ..• m.... ..„ ..„ .:.... .,.. ..• wrzx • x crosrtx w,m PREY wu, Hun ,v. CHECKED BY PAR • •..." •a .m,... e.•. ..r• "1 "1 .. . .. _ CHECKED BY smwurte ww n¢ • 11 u, @ ILL"1 •." a." ,." •.x ...• ,.w •.n .n ..0 .., SASS ,...0 •.a. ... • ,a .r Far .n .o •.x . a .... a e. .... .... .: CHECKED BYE SECTION A —A .:m.. m. ::..A.. .m :. .. .w.: NO .F..:.), w) ..) SCALE ..a ..,...,...„ S." •.IN ........................ s, �.. ... cxICRE9 Er — w.E _. CHECKED Rr eFvlsloxs oa: IRBB o�.N anw. 9M M SHEAR •ENGINEERING CORPORATION TITLE MASTER GRADING rDRAINAGE IF EROSION CONTROL PLAN Panto No. SHEET No, No OF -- - ---- - OeIE 9E)k Cox I H W C IM EO B.K. MA ELL CO.. INC. 4636 90. COLLEGE AVE, SUITE 12. FORT COLLINS, COLORA00 W525 MULBERRY GREEN 3 La SwM MNOVN ews PHONE: (9T0) 226-5334 (9T0) 226-4451 FAR: (9]0) 2B2-0311 FORT COLLINS, COLORADO 1161-24,5 V