FINAL UTILITY REPORT Villages at Riverdale - City of … UTILITY REPORT Villages at Riverdale Thornton, CO October 14, 2016 Revised: ... WaterCAD scenarios have been prepared in accordance

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FINAL UTILITY REPORT

Villages at Riverdale Thornton, CO

October 14, 2016

Revised:

March 29, 2017

June 28, 2017

JN: 15039

Prepared for:

PCS Group, Inc.

1001 16th Street #3 B-180

Denver, CO 80265

P: 303.531.4905

Prepared by:

Jansen Strawn Consulting Engineers

45 W. 2nd Avenue

Denver, CO 80223

P: 303.561.3333

F: 303.561.3339

Thomas C. Jansen, PE No. 35942

Principal

Villages at Riverdale

October 14, 2016

Page 2


City of Thornton

Development Engineering Division

9500 Civic Center Drive

Thornton, CO 80229

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

60 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 50% design capacity of 0.38 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 (303) 561-3333.

Sincerely,

Jansen Strawn Consulting Engineers, Inc.

Todd Lyon, PE

Project Manager


October 14, 2016

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 Date

State of Colorado Registration No. 35942

For and on behalf of Jansen Strawn

Consulting Engineers, Inc.


October 14, 2016

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

A P P E N D I C E S

APPENDIX A

Vicinity Map

APPENDIX B

Sewer Calculations

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


October 14, 2016

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 128th 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 60 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

100-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


October 14, 2016

Page 6


Zone 1C. This zone has a Hydraulic Grade Line (HGL) of 5304. The site elevations range

from 5105 to 5087 that correspond to a static pressure of 84 psi and 86 psi.

An existing 16-inch water main currently runs within East 128th 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 PVC 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

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=110 psi, Min Pressure=50 psi

Max Daily + Fire Flow - Min Pressure=20 psi, Max Velocity=11.2 fps

Peak Hour - Min Pressure = 40 psi, Max Velocity=5 fps


October 14, 2016

Page 7


Fire Flow Rate = 1,500 gpm

Design criteria used is as follows:

2.45 persons per dwelling

Average Day = 150 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 PVC 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) = 80 gallons per person per day

Peaking factor = 1.72 / (F 0.295) [3.5 max, 2.0 min]

Design Slope for 8” pipe between 0.40% and 5.00%

Velocity between 2 and 10 feet per second

Design capacity for pipes smaller 15” = 50% maximum capacity

Demand results are as follows:

• Average Day Demand:

o SFA = 11,760 GPD

• Peak Demand from Development

o SFA = 41,160 GPD (0.06 cfs)


October 14, 2016

Page 8


Assuming a minimum pipe slope of 0.4% for an 8-inch main and a maximum of 50% depth,

the allowable capacity has been calculated to be 0.38 cfs. In the proposed sanitary

system, the peak flow has been calculated to be 0.06 cfs, which corresponds to a 8.3% full

pipe. The demand is far less than the maximum per City of Thornton Criteria.


October 14, 2016

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 2012.


APPENDIX A

Vicinity Map


APPENDIX B

Sewer Calculations

1/26/2017

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) 2.20 people / unit

Residential average demand: 80 gal / person / day

Commercial average demand: 600 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

Peak

Flow

(gpd)

Peak Flow

(cfs)

1 SFD 60 2.45 147 80 11,760 8.2 0.02 3.50 41,160 0.06

Total= 11,760 8 0.02 3.50 41,160 0.06

1 11,760 3.50 41,160 0.06 8 0.40% 0.76 50% 0.38 8.3%

1. Pipes smaller than 15" are designed with no more than 50% maximum flow (q/Q) per 2012 City of Thornton Standards and Specs.

DesignPeak flow (q)

(cfs)Pipe Size (in) q/Qfull (%)

Full Flow

Capacity1

(%)

Qcap. (cfs)Qfull (cfs)

Minimum

Pipe Slope

(%)

Average flow

(cfs)

Used

Peaking

Factor

Peak

Flow

(gpd)

Page 1 of 1 15096-Sewer Demands.xlsx


APPENDIX C

WaterCAD – Scenario 1/2: High/Low HGL and No Demands

FlexTable: Junction Table

Demand(gpm)

Pressure(psi)

Hydraulic Grade(ft)

Label

0855,304.00J-1

0855,304.00J-2

0885,304.00J-3

0885,304.00J-4

0905,304.00J-5

0935,304.00J-17

Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/29/2017

Bentley WaterCAD V8i (SELECTseries 6)[08.11.06.113]Bentley Systems, Inc. Haestad Methods Solution Center15096-WaterCAD Model.wtg

FlexTable: Pipe TableHeadloss Gradient

(ft/ft)

Velocity(ft/s)

Flow(gpm)

Hazen-Williams CMaterialDiameter(in)

Label

0.0000.000150.0PVC12.0P-1

0.0000.000150.0PVC12.0P-2

0.0000.000150.0PVC8.0P-3

0.0000.000150.0PVC8.0P-4

0.0000.000150.0PVC8.0P-5

0.0000.000150.0PVC8.0P-6

0.0000.000150.0PVC8.0P-7

0.0000.000150.0PVC8.0P-17

Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666

3/29/2017



APPENDIX D

WaterCAD – Scenario 3: Low HGL and Maximum Hour Demands

FlexTable: Junction TableDemand(gpm)

Pressure(psi)

Hydraulic Grade(ft)

Label

12855,304.00J-17855,304.00J-2

13885,304.00J-327885,303.99J-429905,303.99J-50935,303.99J-17

Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA+1-203-755-1666

1/26/2017


FlexTable: Pipe TableHeadlossGradient

(ft/ft)

Velocity(ft/s)

Flow(gpm)


Label

0.0000.1658150.0PVC12.0P-10.0000.0725150.0PVC12.0P-20.0000.1118150.0PVC8.0P-30.0000.035150.0PVC8.0P-40.0000.01-1150.0PVC8.0P-50.0000.19-31150.0PVC8.0P-60.0000.1321150.0PVC8.0P-70.0000.000150.0PVC8.0P-17


1/26/2017



APPENDIX E

WaterCAD – Scenario 4: Low HGL and Max Daily Demands w/ Fire Flow

FlexTable: Junction TableDemand(gpm)

Pressure(psi)

Hydraulic Grade(ft)

Label

7855,303.79J-14855,303.74J-27885,303.51J-3

15885,303.15J-416895,301.28J-5

1,500895,296.27J-17


1/26/2017


FlexTable: Pipe TableHeadlossGradient

(ft/ft)

Velocity(ft/s)

Flow(gpm)


Label

0.0011.84648150.0PVC12.0P-10.0000.71250150.0PVC12.0P-20.0011.57246150.0PVC8.0P-30.0011.52238150.0PVC8.0P-40.0063.93616150.0PVC8.0P-50.0125.75-901150.0PVC8.0P-60.0022.50392150.0PVC8.0P-70.0309.57-1,500150.0PVC8.0P-17


1/26/2017



APPENDIX F

Overall Utility Map

Documents

FINAL UTILITY REPORT Villages at Riverdale - City of … UTILITY REPORT Villages at Riverdale Thornton, CO October 14, 2016 Revised: ... WaterCAD scenarios have been prepared in accordance