Villages at Riverdale Thornton, CO

Transcription

1 FINAL UTILITY REPORT Villages at Riverdale Thornton, CO October 14, 216 Revised: March 29, 217 JN: 1539 Prepared for: PCS Group, Inc th Street #3 B-18 Denver, CO 8265 P: Prepared by: Jansen Strawn Consulting Engineers 45 W. 2nd Avenue Denver, CO 8223 P: F: Thomas C. Jansen, PE No Principal solutions. partnerships. success. t f West 2nd Avenue, Denver, Colorado

2 Villages at Riverdale October 14, 216 Page 2 City of Thornton Development Engineering Division 95 Civic Center Drive Thornton, CO 8229 Attn: Cassie Free Dear Ms. Free: The purpose of this letter in to present the final design for the proposed water and sanitary utilities within the Villages at Riverdale Subdivision development. The attached report defines and analyzes the impact on the existing public water and sewer systems and the size of the facilities included in the Villages at Riverdale Subdivision development. Water and sanitary demands were calculated for the 6 single-family attached residential lots included within the overall development. Upon analyzing the sanitary sewer demands for the total development, the flow within the proposed 8 sanitary sewer never surpasses the 5% design capacity of.38 cfs per City of Thornton Criteria (See report and Appendix to follow). Similarly, the water system for the total development has been analyzed for the scenarios required by City of Thornton Criteria including: Average Day Demand, Maximum Day Demand, Maximum Hour Demand and Maximum Day Demand plus Fire Demand. In all cases, the pipe pressures and velocities were all within the guidelines set by the City of Thornton. Should you have any questions or comments, please feel free to contact me at (33) Sincerely, Jansen Strawn Consulting Engineers, Inc. Todd Lyon, PE Project Manager

3 Villages at Riverdale October 14, 216 Page 3 CERTIFICATIONS PCS Group, Inc. hereby certifies that the utilities (water and sanitary sewer) for the Villages at Riverdale Subdivision will be constructed to the design presented in this report. I understand that the City of Thornton does not and shall not assume liability for the utilities designed and/or certified by my engineer. I understand that the City of Thornton reviews utility plans but cannot, on behalf of the Villages at Riverdale Subdivision guarantee that final utility design review will absolve PCS Group, Inc. and/or their successors and/or assigns of future liability for improper design. I further understand that approval of the Final Plan and/or Final Development Plan does not imply approval of my engineer s utility design. Attest: Name of Responsible Party Notary Public Authorized Signature I hereby certify that this report (plan) for the Final Utility design of the Villages at Riverdale Subdivision was prepared by me (or under my direct supervision) in accordance with the provisions of the City of Thornton Standards and Specifications for the Responsible Parties thereof. I understand that the City of Thornton does not and will not assume liability for utilities designed by others. Thomas C. Jansen, PE State of Colorado Registration No For and on behalf of Jansen Strawn Consulting Engineers, Inc. Date

4 Villages at Riverdale October 14, 216 Page 4 T A B L E O F C O N T E N T S INTRODUCTION... 5 I. GENERAL LOCATION AND DESCRIPTION... 5 II. EXISTING UTILITIES... 5 III. PROPOSED UTILITIES... 6 IV. REFERENCES... 9 APPENDIX A Vicinity Map APPENDIX B Sewer Calculations A P P E N D I C E S APPENDIX C WaterCAD Scenario 1/2: High/Low HGL and No Demands APPENDIX D WaterCAD Scenario 3: Low HGL and Maximum Hour Demands APPENDIX E WaterCAD Scenario 4: Low HGL and Max Daily Demands w/ Fire Flow APPENDIX F Overall Utility Map

5 Villages at Riverdale October 14, 216 Page 5 I. GENERAL LOCATION AND DESCRIPTION A. Location The proposed Villages at Riverdale Subdivision (site) is located in the southwest quarter of Section 28, Township 1 South, Range 67 West of the Sixth Principal Meridian, County of Adams, Colorado. The overall Conceptual Site Plan area currently includes approximately 9.91 acres of property, including 5.13 acres of single-family attached residential, 2.26 acres of Parks/Open Space. The site lies to the north of East 128 th Avenue and to the east of Tamarac Street. The site is bounded to the east and west by residential property and to the north by Horizon Tributary. Adjacent developments to the site include the already developed portions of Villages at Riverdale Filing No. 1 to the north and west, while Gleneagle Estates Subdivision lies directly to the east. The site is currently zoned as and will remain zoned with portions of single family attached (SFA). See Appendix A for a vicinity map, and a Final Utility Map in Appendix B. Utility Reports for surrounding developments that would be affected by the proposed waterline development include the previously developed portions of the Villages at Riverdale Filing No.1 to the north and west. B. Description of Property The Villages at Riverdale Subdivision has been platted with the City of Thornton. Ultimately, the Villages at Riverdale Subdivision shall be controlled by the Villages at Riverdale Zoning Amendment 2/Conceptual Site Plan, which is under review by the City of Thornton. The entire Villages at Riverdale Subdivision is approximately 9.91 acres, which includes open space and 6 residential lots. The existing site is undeveloped land covered by short native grasses. Horizon Tributary runs to the north of the property, and the proposed development remains outside of the

6 Villages at Riverdale October 14, 216 Page 6 1-year floodplain. The site generally slopes from west to east at roughly 2%, with a small ridge running through the center from west to east. II. EXISTING UTILITIES A. Potable Water System Information regarding existing water facilities have been gathered from the City of Thornton. According to their records, the subject property is located within Pressure Zone 1C. This zone has a Hydraulic Grade Line (HGL) of 534. The site elevations range from 515 to 587 that correspond to a static pressure of 84 psi and 86 psi. An existing 16-inch water main currently runs within East 128 th Avenue. There is an existing hydrant along the property frontage which will be reset to act as a waterline connection. Additionally, there are two 8-inch stubs off of the existing 12-inch waterline within Tamarac Street. B. Sanitary Sewer The Villages at Riverdale Subdivision is located within Basin J of the Wastewater Master Plan for the City of Thornton. The site will be serviced by the 12-inch Horizon Tributary Outfall Sewer which runs to the north of the site. There is an existing stub to the site off of Tamarac Street at the northern roundabout. This stub is going to be abandoned since the invert does not vertically allow for a sanitary service main to service the eastern portion of the site. The proposed 8-inch sanitary main will connect directly to SSMH-14 of the Horizon Tributary Outfall Sewer. The proposed sanitary sewer system will be designed in accordance with all City of Thornton Criteria. All proposed land uses comply with what is shown on the City of Thornton Future Land Use Map provided within the Wastewater Masterplan. Ultimately, the sanitary outfall from the proposed development were initially intended to connect to the Horizon Tributary Outfall sewer, and now will simply be connected in a different manner. III. PROPOSED UTILITIES A. Potable Water System All proposed waterlines within the proposed Villages at Riverdale Subdivision are proposed to be 8-inch waterlines which loop throughout the site. All proposed domestic services and fire hydrants will be tapped off of the proposed 8-inch main. A WaterCAD model was prepared for this development utilizing City of Thornton Criteria and the following scenarios within Zone 1C. Although this water system technically connects different zones, it has been analyzed based upon the immediate zone it has been located in. Zone delineations should not be affected based on the results of this report

7 Villages at Riverdale October 14, 216 Page 7 and were included within the City of Thornton Masterplan. Demand nodes have been placed throughout the site; each node has been assigned a demand based on the number of adjacent units and the criteria referenced earlier in this report. The residential density for the single-family detached has been calculated using the maximum dwelling units per acre of 12 and 2.45 persons per unit. Average Day - Max Pressure=11 psi, Min Pressure=5 psi Max Daily + Fire Flow - Min Pressure=2 psi, Max Velocity=11.2 fps Peak Hour - Min Pressure = 4 psi, Max Velocity=5 fps Fire Flow Rate = 1,5 gpm Design criteria used is as follows: 2.45 persons per dwelling Average Day = 15 gallons per person per day Maximum Daily = 3.2 x Average Day (Residential) Maximum Hourly = 5.76 x Average Hourly (Residential) WaterCAD scenarios have been prepared in accordance with City of Thornton Criteria. The scenarios run for the project include High/Low HGL with No Demands, Maximum Hour Demand and Maximum Day Demand plus Fire Demand. Due to the lowest HGLs being equal to the highest HGLs, only one scenario was run with no demands. Spreadsheets have been provided within the appendix detailing the pipe flows, velocities and pressures at junctions called out within the WaterCAD plan sheet. Pipe sizes and materials have all been provided within the WaterCAD pipe spreadsheets. The pressures and pipe velocities are all within the City of Thornton Criteria. No revisions are required based on the findings of the WaterCAD model provided. B. Sanitary Sewer The Villages at Riverdale Subdivision proposed 8-inch gravity sanitary sewer systems runs throughout the entire site. The proposed 8-inch sanitary main will connect directly to the Horizon Tributary Outfall Sewer to the northwest of the existing roundabout at the northern end of Tamarac Street at SSMH-14. Ultimately, sanitary flows from the site were initially intended to outfall into this manhole. The sanitary sewer has been designed to meet City of Thornton Standards and Specifications. Criteria used is as follows: 2.45 persons per dwelling Average Day (F) = 8 gallons per person per day Peaking factor = 1.72 / (F.295 ) [3.5 max, 2. min]

8 Villages at Riverdale October 14, 216 Page 8 Design Slope for 8 pipe between.4% and 5.% Velocity between 2 and 1 feet per second Design capacity for pipes smaller 15 = 5% maximum capacity Demand results are as follows: Average Day Demand: o SFA = 11,76 GPD Peak Demand from Development o SFA = 41,16 GPD (.6 cfs) Assuming a minimum pipe slope of.4% for an 8-inch main and a maximum of 5% depth, the allowable capacity has been calculated to be.38 cfs. In the proposed sanitary system, the peak flow has been calculated to be.6 cfs, which corresponds to a 8.3% full pipe. The demand is far less than the maximum per City of Thornton Criteria.

9 Villages at Riverdale October 14, 216 Page 9 IV. REFERENCES 1. City of Thornton Standards and Specifications for the Design and Construction of Public and Private Improvements, City of Thornton, October 212.

10 APPENDIX A Vicinity Map

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12 APPENDIX B Sewer Calculations

13 1/26/217 Sanitary Calculations for Villages at Riverdale City of Thornton Standards low density (less than 5 DU/acre) 3.45 people / unit mid density (5 to 12 DU/ acre) 2.45 people / unit high density (more than 12 DU/acre) 2.2 people / unit Residential average demand: 8 gal / person / day Commercial average demand: 6 gal / acre DU = dwelling units Planning Area Land Use: DU (ac) People / Unit No. of People Average Demand (gal/person/day) Average Flow (gpd) Average Flow (gpm) Average Flow (cfs) Used Peaking Factor 1 SFD , ,16.6 Peak Flow (gpd) Peak Flow (cfs) Total= 11, ,16.6 Design Average flow (cfs) Used Peaking Factor Peak Flow (gpd) Peak flow (q) (cfs) Minimum Full Flow Pipe Size (in) Pipe Slope Q full (cfs) Capacity 1 Q cap. (cfs) q/q full (%) (%) (%) 1 11, , %.76 5% % 1. Pipes smaller than 15" are designed with no more than 5% maximum flow (q/q) per 212 City of Thornton Standards and Specs. Page 1 of Sewer Demands.xlsx

14 APPENDIX C WaterCAD Scenario 1/2: High/Low HGL and No Demands

15 J-1 J-2 J-3 J-4 J-5 J-17 Label Hydraulic Grade (ft) 5,34. 5,34. 5,34. 5,34. 5,34. 5,34. Pressure (psi) FlexTable: Junction Table Demand (gpm) 1596-WaterCAD Model.wtg 3/29/217 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 2 W Watertown, CT 6795 USA Bentley WaterCAD V8i (SELECTseries 6) [ ] Page 1 of 1

16 P-1 P-2 P-3 P-4 P-5 P-6 P-7 P-17 Label Diameter (in) Material Hazen-Williams C FlexTable: Pipe Table Flow (gpm) Velocity (ft/s) Headloss Gradient (ft/ft) WaterCAD Model.wtg 3/29/217 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 2 W Watertown, CT 6795 USA Bentley WaterCAD V8i (SELECTseries 6) [ ] Page 1 of 1

17 APPENDIX D WaterCAD Scenario 3: Low HGL and Maximum Hour Demands

18 J-1 J-2 J-3 J-4 J-5 J-17 Label Hydraulic Grade (ft) 5,34. 5,34. 5,34. 5, , ,33.99 Pressure (psi) FlexTable: Junction Table Demand (gpm) WaterCAD Model.wtg 1/26/217 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 2 W Watertown, CT 6795 USA Bentley WaterCAD V8i (SELECTseries 6) [ ] Page 1 of 1

19 P-1 P-2 P-3 P-4 P-5 P-6 P-7 P-17 Label Diameter (in) Material Hazen-Williams C FlexTable: Pipe Table Flow (gpm) Velocity (ft/s) Headloss Gradient (ft/ft) WaterCAD Model.wtg 1/26/217 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 2 W Watertown, CT 6795 USA Bentley WaterCAD V8i (SELECTseries 6) [ ] Page 1 of 1

20 APPENDIX E WaterCAD Scenario 4: Low HGL and Max Daily Demands w/ Fire Flow

21 J-1 J-2 J-3 J-4 J-5 J-17 Label Hydraulic Grade (ft) 5, , , , , , Pressure (psi) FlexTable: Junction Table Demand (gpm) , WaterCAD Model.wtg 1/26/217 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 2 W Watertown, CT 6795 USA Bentley WaterCAD V8i (SELECTseries 6) [ ] Page 1 of 1

22 P-1 P-2 P-3 P-4 P-5 P-6 P-7 P-17 Label Diameter (in) Material Hazen-Williams C FlexTable: Pipe Table Flow (gpm) ,5 Velocity (ft/s) Headloss Gradient (ft/ft) WaterCAD Model.wtg 1/26/217 Bentley Systems, Inc. Haestad Methods Solution Center 27 Siemon Company Drive Suite 2 W Watertown, CT 6795 USA Bentley WaterCAD V8i (SELECTseries 6) [ ] Page 1 of 1

23 APPENDIX F Overall Utility Map

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