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HomeMy WebLinkAboutHARMONY TECHNOLOGY PARK, 1ST, CELESTICA - FDP - 12-97B - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTSEAR -BROWN VICINITY MAP N.T.S. DRAKE RD. yC> Z� A C 9 OGO �F a Li J HORSETOOTH RD. < o a Li J � uj U C � � n U Z m I r II II F] n 7-1 U r I 1 I I t I VICINITY MAP 1 I t I 11 I B. Drainage Concept The combination of swales, and street and storm drain systems will provide for the 10 and 100 year developed flows to reach the proposed on -site detention facilities. The proposed drainage concepts presented in this report and on the construction plans adequately provide for the conveyance and release of developed on -site flows into the downstream conveyance system. If groundwater is encountered at the time of construction, a Colorado Department of Health Construction Dewatering Permit will be required. C. Storm Water Quality Concept. Because storm water quality has become a requirement, the proposed design has addressed this storm water aspect. Grass lined swales and detention ponds will allow sediment to settle out before entering the downstream conveyance system. In addition silt fence and gravel inlet filters will be provided during construction ' D. Erosion Control Concept The erosion control concepts adequately provide for the control of wind and ' rainfall erosion from the Harmony Technology Park. Through the construction of the erosion control concepts, the City of Fort Collins performance standard will be met. REFERENCES Storm Drainage Design Criteria and Construction Standards, by the City of Fort Collins, Colorado, May 1984, revised January 1991. 2. Erosion Control Reference Manual for Construction Sites, by the City of Fort Collins, Colorado, January 11, 1991. I Li I I I 1 6 Basins 3,4 and OS-4 are the only basins which drain into the north east pond. The north east pond has 0.42 ac-ft of storage at elevation 19.0 and a release rate of 5.2 cfs. Based on the SWMM results included in the Appendix the volume of storage ' needed for this pond is 0.4 ac-ft. The control structure for Pond B will be a flared end section with a rectangular orifice plate that is 12" wide and 13.5" high. V. STORM WATER QUALITY The Harmony Technology Park development includes such Best Management Practices as grass lined swales, grass lined detention and retention ponds and the installation of silt fence and gravel inlet filters during construction. In addition, the outflow rate from the proposed detention pond is very small (3.5 cfs) which allows the sediment to filter out. All construction activities must comply with the State of Colorado permitting process for Storm water Discharges Associated with Construction Activity. A Colorado Department of Health NPDES Permit will be required before any construction grading can begin. VI. EROSION CONTROL ' A. General Concept This area is in the Moderate Wind Erodibility Zone and the Moderate Rainfall LErodibility Zone per the City of Fort Collins zone maps. The potential exists for erosion problems during construction and after construction until the disturbed ground is revegetated or paved. B. Specific Details Calculations for erosion control performance standards have been completed per the City of Fort Collins erosion Control Reference Manual for Construction Sites, and have been included with this submittal. The required performance standard during construction was 79.1, and the value for this erosion control design is 84.0. The required performance standard after construction was•93.0, and the value for this erosion control design is 96.0. Based on this the erosion control plan meets the City of Fort Collins Criteria. The total erosion control security deposit is $55,508.00. VII. CONCLUSIONS A. Compliance with Standards All computations completed within this report are in compliance with the Storm Drainage Design Criteria Manual. 5 historic runoff rate from the undeveloped site. The entire site drains to the south east corner with the exception of one small area in the north east comer which drains to the east. According to the results of the SWMM the 2 year historic runoff from the site is 4.9 cfs. The historic SWMM schematic and SWMM is Iincluded in the Appendix. The historic SWMM was also run for the 100 year storm event. The purpose of this run was to determine the 100 year runoff volume from the historic site. Since the downstream drainage easements have not yet been obtained part of the drainage criteria included limiting the volume of runoff from the site to less than the 100 year historic volume. Care was taken to allow the SWMM to run for a long enough period to ensure that the actual volume was determined. According to the SWMM which is included in the Appendix, the 100 year historic volume of runoff from the site is 3.9 ac-ft. ' In addition to the historic SWMM a fully developed SWMM was prepared. This SWMM was prepared in order to determine whether all of the design criteria was being met with the ponds as proposed. As stated earlier in addition to the two detention ponds, retention pond A is being provided until such time that the downstream drainage easements are obtained. The purpose of the retention pond is to store the excess volume of runoff from the site that exceeds the 100 year historic volume. In the fully developed SWMM basins 1,5,4,9,3,6,15,13 and 14 (13 and 14 are Harmony Road Basins, and 15 is Technology Parkway) all drain into the proposed detention pond. We were unable to grade the site to allow for all runoff to enter the detention pond first. If we had been able to grade the site that way, then we could have allowed that of the runoff in 100 portion excess of the year historic volume of runoff to spill over into the retention pond via weir flow. Instead, we had to limit through grading how much runoff could enter the detention pond initially. The remainder of the sub -basins are all graded to enter the retention pond. The volume of runoff which is discharged from pond A (pond 500 according to the SWMM) was determined by placing a node (node 503) downstream of the pond and plugging the node to determine the volume of runoff coming from pond 500. Again, care was taken to allow the SWMM to run long enough to ensure that the entire volume of runoff was discharged. That volume according to the SWMM was 3.7 ac-ft which is less than the historic volume of 3.9 ac-ft. In addition, the release rate from pond 500 was shown in this SWMM to be 3.5 cfs which is less than the 2 year historic rate of 4.9 cfs. The control structure for pond A (pond 500 in the SWMM) will be a flared end section with a rectangular orifice plate 7.0" wide by 10" high. Also in the fully developed SWMM the volume of retention was determined by checking the output for pond 502. The volume given for pond 502 according to the SWMM was 2.8 ac-ft. Since the City of Ft. Collins Stormwater Criteria requires providing twice this volume in the event back to back storms occur, the required volume is 5.6 ac-ft, plus 1 foot of freeboard. The retention pond as ' currently proposed provides 6.18 ac-ft of storage at elevation 4915.00. ' 4 I conveyed to a point approximately 800 feet north of the center of section, where flows from the northwest 1/4 of section 4 have historically discharged via a proposed swale. From there the flow will be allowed to sheet flow to the existing irrigation ditch imitating the historic condition. In addition, to the two detention ponds, there is one retention pond being provided as well. Retention pond A is being provided to insure that no more than the 100 year historic volume of runoff will be released from the site. B. Specific Details The Harmony Technology Park has been broken into 10 sub -basins and 4 off -site 1 basins. The off -site basins are for Harmony Road, County Road 9 and Technology Parkway. Harmony Road will have a bike lane and an acceleration lane added on the south side. The western portion of Harmony Road adjacent to the site will drain into an area inlet and into the on -site storm drain system. The inlet and storm sewer have been designed to convey the 100 year flow. The eastern portion of Harmony Road adjacent to the site will be graded to drain into pond A. Therefore, all of the historic and proposed increase in runoff from Harmony Road will be detained on -site. The revised County Road 9 will generally follow the current flow line with slight modifications. A type `R' inlet will be added at the low point which is just to the north of the second driveway into the development. The discharge from this inlet will be piped on -site and into retention pond A. The inlet, storm sewer and swale have all been designed to convey the 100 year flow into the retention pond. There is an existing elliptical pipe at the intersection of County Road 9 and Harmony Road which conveys irrigation flows. An HY8 analysis was done on this pipe to determine its' capacity. Based on this analysis this pipe can convey approximately 25 cfs under County Road 9 from the west to the east. Any additional flows would be forced due to the grading and crown of County Road 9 onto the west side of County Road 9. Aqua Engineers has provided a design to convey the irrigation flows from the downstream end of the existing elliptical pipe. An irrigation ditch will provide capacity for 21 cfs to the south and a 21" pvc pipe will provide capacity for 10 cfs to the east. This will more than be able to handle the 25 cfs coming in from the west. Technology Parkway will only be constructed to the first east entrance at this time. The end of Technology Parkway will be d cul-de-sac for the time being. The portion of Technology Parkway that is being built at this time will be conveyed into detention Pond A via a triangular channel. In the future when the remainder of Technology Parkway is constructed two Type `R' inlets will be provided at the low point to convey the runoff into the detention pond. The drainage calculations and hydraulic analysis for the future extension of Technology Parkway have been provided in the Appendix of this report in their own section. A historic SWMM was prepared for the overall site to determine the 2 year I III. DRAINAGE DESIGN CRITERIA �- A. Regulations The City of Fort Collins Storm Drainage Design Criteria is being used for the subject site. B. Development Criteria Reference, Constraints and Comparison The drainage criteria used herein is in accordance with the City of Fort Collins Storm Drainage Design Criteria and Construction Standard Manual. On -site detention is being provided with a release rate limited to the 2-year historic run-off rate from the site. In addition, because the downstream drainage easements necessary to convey the flow from this site into the Fossil Creek Reservoir have not been attained at this time a temporary on -site retention pond is also being provided. C. Hydrological Criteria The Rational Method for determining surface runoff was used for the project site. The 10-year and 100-year storm event criteria, obtained from the City of Fort Collins, was used in calculating runoff values. The EPA SWMM was also used for determining historic runoff from the site and the sizing of detention ponds. These calculations and criteria are included in the Appendix D. Hydraulic Criteria All hydraulic calculations within this report have been prepared in accordance with the City of Fort Collins Storm Drainage Criteria and are included in the Appendix. E. Variances from Criteria No variances from City of Fort Collins Storm Drainage Criteria are being sought for this project. IV. DRAINAGE FACILITY DESIGN A. General Concept The majority of the on -site runoff produced by the Harmony Technology Park will flow into the detention pond located in the south east corner of the site (pond A). Pond A will discharge into a ditch on the east side of Technology Parkway. A smaller portion of the site will flow into the detention pond located in the north east comer of the site (pond B). Pond B will discharge into the on -site storm sewer system and ultimately into Pond A. From Pond A the flow will be 2 FINAL DRAINAGE AND PROJECT DEVELOPMENT REPORT FOR THE HARMONY TECHNOLOGY PARK PUD FIRST FILING FORT COLLINS, COLORADO I. GENERAL LOCATION AND DESCRIPTION A. Location The Harmony Technology Park PUD, first filing is a proposed manufacturing facility for Celestica Inc., of North York Ontario. The site is situated on the south side of Harmony Rd., and the east side of County Rd. 9. Immediately across Harmony Rd. to the north is the existing Hewlett-Packard facility. This filing of the development encompasses approximately 34.7 acres more or less. There are plans for future filings which will increase the size of the development. All of the drainage calculations provided here -in include the area from the existing Harmony House site. More specifically the site is located in the Northwest Quarter of Section 4, Township 6 North, Range 68 West of the 6`' Principal Meridian, City of Fort Collins, Larimer County, Colorado. The project site is shown on the Vicinity Map in the Appendix. B. Description of Property The Harmony Technology Park is undeveloped at the present time. The site is currently cultivated farmland, and the topography generally slopes toward the southeast corner at approximately 0.8%. H. DRAINAGE BASINS AND SUB -BASINS NA. Major Basin Description The project site is located in the east portion of the McClellands Basin. There is a McClellands master plan, however it does not address this area. The city has currently contracted to have this portion of the Master Plan updated. B. Sub -Basin Description ' Historic flows from the site drain in a south easterly direction until reaching an inlet ditch for the Fossil Creek Reservoir. On -site detention and retention will be required for this site in order to maintain flows at historic levels. I E DESCRIPTION PAGE I. GENERAL LOCATION AND DESCRIPTION A. LOCATION 1 B. DESCRIPTION OF PROPERTY 1 II. DRAINAGE BASINS AND SUB -BASINS A. MAJOR BASIN DESCRIPTION 1 B. SUB -BASIN DESCRIPTION 1 III. DRAINAGE DESIGN CRITERIA A. REGULATIONS 2 B. DEVELOPMENT CRITERIA REFERENCE, CONSTRAINTS, AND COMPARISON 2 C. HYDROLOGICAL CRITERIA 2 D. HYDRAULIC CRITERIA 2 E. VARIANCES FROM CRITERIA 2 IV. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT 2 B. SPECIFIC DETAILS 3 V. STORM WATER QUALITY 5 VI. EROSION CONTROL A. GENERAL CONCEPT 5 B. SPECIFIC DETAILS 5 VII. CONCLUSIONS A. COMPLIANCE WITH STANDARDS 6 B. DRAINAGE CONCEPT 6 C. STORM WATER QUALITY CONCEPT 6 D. EROSION CONTROL CONCEPT 6 REFERENCES 6 APPENDIX VICINITY MAP 2 HYDROLOGY CALCULATIONS 4 DRAINAGE DESIGN FOR FUTURE TECHNOLOGY PARKWAY 10 STORM SEWER, INLETS AND SWALES 23 DETENTION 68 EROSION CONTROL 81 HISTORIC 2-YR SWMM MODEL 89 HISTORIC 100-YR SWMM MODEL 115 FULLY DEVELOPED I00-YR SWMM MODEL 129 CHARTS, TABLES AND FIGURES 159 I f I it I FINAL DRAINAGE AND PROJECT DEVELOPMENT REPORT FOR THE HARMONY TECHNOLOGY PARK, PUD FIRST FILING FORT COLLINS, COLORADO November 25, 1997 Prepared for: Celestica Inc. 844 Don Mills Rd. North York, Ontario M3C 1 V7 Prepared by: The Sear Brown Group 209 South Meldrum Street Fort Collins, Colorado 80521 (303)482-5922 SBG Job No. 785-001 I 1 1 1 1 L 1 THE SEAR -BROWN GROUP FULL SERVICE DESIGN PROFESSIONALS FORMERLY RBD, INC. 209 SOUTH MELDRUM FORT COLLINS, COLORADO 80521-2603 970-482-5922 FAX:970-482-6568 November 25, 1997 Mr. Basil Hamdan City of Fort Collins Utility Services, Stormwater 235 Matthews Fort Collins, Colorado 80522 ' RE: Final Drainage and Project Development Report for the Harmony Technology Park PUD, First Filing Dear Basil: ' We are pleased to submit to you, for your review and approval, this Final Drainage and Project Development Report for the Harmony Technology Park PUD, first filing. All computations within this report have been completed in compliance with the City of Fort Collins Storm ' Drainage Design Criteria. ' We appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. ' Respectfully, The Sear Brown Group ' Prepared by: Reviewed by: i - ' eiAllen-Morley, P.E. Kevin Gingery Project Manager Project Manager 1 1 NEW YORK• PENNSYLVANIA COLORADO•UTAH STANDARDS IN EXCELLENCE EQUAL OPPORTUNITY EMPLOYER Final Drainage and Erosion Control Report for the Harmony Technology Park PUD, First Filing Loveland, Colorado November 1997 THE SEAR -BROWN GROUP Standards in Excellence