2018 Sewer Collection Master Plan Update Collection...Prepared By: J-U-B ENGINEERS, Inc. 1047 South 100 West, Suite 180 Logan, UT 84321 Prepared For: Logan City Corporation. 255 N

Prepared By:

J-U-B ENGINEERS, Inc. 1047 South 100 West, Suite 180 Logan, UT 84321

Prepared For:

Logan City Corporation. 255 N Main Street Logan, UT 84321

2018 Sewer Collection Master Plan Update

June 2015

J-U-B ENGINEERS, Inc.

Logan City P a g e | iii Sewer Collection System Master Plan

CONTENTS

EXECUTIVE SUMMARY ............................................................................................................................... viii

1 INTRODUCTION ..................................................................................................................................... 2

1.1 Background ................................................................................................................................... 2

1.2 Project Tasks ................................................................................................................................. 4

1.3 Master Plan Purpose ..................................................................................................................... 4

2 DATA COLLECTION ................................................................................................................................ 6

2.1 Introduction .................................................................................................................................. 6

2.2 Existing System Mapping .............................................................................................................. 6

2.2.1 System Connectivity .............................................................................................................. 6

2.2.2 Sewer Cleanouts ................................................................................................................... 7

2.2.3 Lift Station Information ......................................................................................................... 7

2.2.4 Reverse Grade Pipes ............................................................................................................. 7

2.2.5 Flow Routing Adjustments .................................................................................................... 9

2.2.6 Drop manholes .................................................................................................................... 10

2.2.7 Pipe Diameter Adjustments ................................................................................................ 10

2.3 Sanitary Sewer Flows .................................................................................................................. 10

2.4 Total Flows .................................................................................................................................. 10

2.4.1 Infiltration ........................................................................................................................... 11

2.4.2 Inflow .................................................................................................................................. 12

2.5 Summer Flow Data Collection ..................................................................................................... 14

2.5.1 Summer Meter Schedule .................................................................................................... 14

2.5.2 Summer Meter Equipment ................................................................................................. 14

2.5.3 Summer Meter Locations .................................................................................................... 15

2.5.4 Summer Flow Data Evaluation ............................................................................................ 17

3 EXISTING SYSTEM ANALYSIS ............................................................................................................... 18

3.1 Introduction ................................................................................................................................ 18

3.2 Collection System Regulatory Requirements .............................................................................. 18

3.3 Development Requirements ....................................................................................................... 18


Logan City P a g e | iv Sewer Collection System Master Plan

3.4 Model Development and Assumptions ...................................................................................... 19

3.4.1 Collection System Geometry Assumptions ......................................................................... 19

3.4.2 Flow Input Location Assumptions ....................................................................................... 19

3.4.3 Sanitary Flow Assumptions ................................................................................................. 20

3.4.4 Pump Parameter Assumptions ........................................................................................... 20

3.4.5 Diurnal Curves Assumptions ............................................................................................... 20

3.4.6 Infiltration Assumptions ...................................................................................................... 23

3.4.7 Inflow .................................................................................................................................. 24

3.4.8 Flows from Others and Large Water Users ......................................................................... 24

3.5 Cost Estimating Assumptions ...................................................................................................... 25

3.6 Model Calibration ....................................................................................................................... 26

3.7 Existing System Evaluation .......................................................................................................... 27

3.7.1 Depth of Flow over Diameter of Pipe (d/D) ........................................................................ 27

3.7.2 Reserve Capacity ................................................................................................................. 28

3.7.3 Hydraulic Grade Line Profile Evaluation ............................................................................. 29

3.7.4 Condition Analysis ............................................................................................................... 29

3.7.5 Lift Station Analysis ............................................................................................................. 30

3.8 Existing System Improvements ................................................................................................... 30

3.8.1 Capacity Improvements ...................................................................................................... 30

3.8.2 Condition Improvements .................................................................................................... 33

3.8.3 Lift Station Improvements .................................................................................................. 34

3.8.4 Summary of Existing Improvements ................................................................................... 34

4 MASTER PLAN & RELIEF ALTERNATIVES ............................................................................................. 35

4.1 Introduction ................................................................................................................................ 35

4.2 Key Assumptions for Future Models ........................................................................................... 35

4.3 Creation of Future Models .......................................................................................................... 37

4.3.1 Future Lift Station Placement ............................................................................................. 38

4.3.2 Future Flow Generation ...................................................................................................... 38

4.4 2020 Evaluation and Results ....................................................................................................... 38

4.5 2025 Evaluation and Results ....................................................................................................... 40


Logan City P a g e | v Sewer Collection System Master Plan

4.6 Buildout Evaluation and Results ................................................................................................. 43

5 PRIORITIZED CAPITAL IMPROVEMENT PROJECTS (CIP) ...................................................................... 46

6 CONCLUSIONS AND RECOMMENDATIONS ......................................................................................... 49

7 REFERENCES ........................................................................................................................................ 53

TABLES

Table 1-1: Logan City Growth Table .............................................................................................................. 2

Table 1-2: Time Frames Analyzed ................................................................................................................. 3

Table 2-1: Reverse Grade Slope Summary Table, S < 0.4 ............................................................................. 8

Table 2-2: Temporary Flow Meters............................................................................................................. 16

Table 3-1: Diurnal Curve Assignments ........................................................................................................ 22

Table 3-2: Infiltration Rates ........................................................................................................................ 24

Table 3-3: Existing System Capacity Improvements ................................................................................... 32

Table 3-4: Existing System Condition Improvements ................................................................................. 33

Table 4-1: Future Time Frames Analyzed ................................................................................................... 35

Table 4-2: Future Pipe Design Parameters ................................................................................................. 37

Table 4-3: 2020 Capacity Improvements .................................................................................................... 40

Table 4-4: 2025 Capacity Improvements .................................................................................................... 42

Table 4-5: Build Out Capacity Improvements ............................................................................................. 44

Table 5-1: Existing System CIP Summary .................................................................................................... 46

Table 5-2: Future System CIP Summary ...................................................................................................... 48

GRAPHS

Graph 2-1: Wintertime Sewer Flows........................................................................................................... 11

Graph 2-2: Summertime Sewer Flows ........................................................................................................ 12

Graph 2-3: Summertime Sewer Flows and Precipitation............................................................................ 13

Graph 3-1: Diurnal Curves ........................................................................................................................... 21

Graph 3-2: Example Calibration Flow Graph .............................................................................................. 26


Logan City P a g e | vi Sewer Collection System Master Plan

DIAGRAMS

Diagram 3-1: Pipe Flow Less than Half Full ................................................................................................. 27

Diagram 3-2: Negative Reserve Capacity Illustration ................................................................................. 28

APPENDICES

APPENDIX A – REPORT FIGURES (Large maps bound separate from this report)

Figure 1 - Existing Collection System

Figure 2 - Flow Meter Locations

Figure 3 - Diurnal Curve Pattern Assignments

Figure 4 - Infiltration Rates

Figure 5 - Existing Depth over Diameter

Figure 6 - Existing Reserve Capacity

Figure 7 - Existing Peak Velocities

Figure 8 - Existing System Improvements

Figure 9 - Projected Growth

Figure 10 - 2020 Depth over Diameter

Figure 11 - 2020 Reserve Capacity

Figure 12 - 2020 Improvements

Figure 13 - 2025 Depth over Diameter

Figure 14 - 2025 Reserve Capacity

Figure 15 - 2025 Improvements

Figure 16 - Build Out Depth over Diameter

Figure 17 - Build Out Reserve Capacity

Figure 18 - Build Out Improvements

Figure 19 - Build Out System

APPENDIX B – TEMPORARY FLOW METER GRAPHS

Flow versus Time Graphs

Depth and Velocity versus Time Graphs

Velocity versus Level Scatter Plots

APPENDIX C – TEMPORARY FLOW METER SITE NOTES


Logan City P a g e | vii Sewer Collection System Master Plan

APPENDIX D – GRAPHS OF FLOWS FROM CONTRIBUTING CITIES

APPENDIX E – UNIT PRICE COSTS SUMMARY TABLE

APPENDIX F – MODEL CALIBRATION GRAPHS

APPENDIX G – CALIBRATION NOTES TABLE

APPENDIX H – BUILD OUT LOCATIONS TO MONITOR

APPENDIX I – SYSTEM IMPROVEMENT DIAGRAMS

APPENDIX J – PROJECTED POPULATIONS OF CONTRIBUTING COMMUNITIES

APPENDIX K – COMPUTER MODEL UPDATE PROCEDURE


Logan City P a g e | viii Sewer Collection System Master Plan

EXECUTIVE SUMMARY

Background

Logan City hired J-U-B Engineers Inc. (J-U-B) to complete a sewer collection system master plan. The

main purpose of the master plan is to provide a planning document and tools that help Logan City meet

its existing and future sewer collection needs. The primary tool is a computer hydraulic sewer model

that is built based on Geographic Information System (GIS) data provided by the City.

Avoiding the overloading of existing sewer pipes from new development or re-development is of major

importance. Re-development can significantly change peak flows in collection pipes near the re-

developed area. The sewer model created for this plan is detailed enough to allow each proposed

development or re-development to be evaluated to verify its potential impact on the system. Every

mapped pipe (with the exception of some dead end pipes that do not have manholes at the upstream

end) is modeled to allow for capacity checks of the pipes in these types of situations.

Master Plan Goals

• Create a detailed calibrated model that is efficient to operate and update

• Identify existing system capacity and condition deficiencies

• Identify future system deficiencies

• Master plan a conceptual collection system to serve undeveloped areas

• Provide a prioritized list of capital improvement projects needed now and for years 2020, 2025,

and build out

This master plan combined with the Logan City 2015 Sewer System Management Plan (SSMP) complies

with the requirements of the Utah Division of Water Quality’s Utah Sewer Management Program

(USMP) including the System Evaluation and Capacity Assurance Plan (SECAP) requirements. The

program is authorized under State of Utah Administrative Code R317-801.

Conclusions and Recommendations

Existing System Geometry - There are some pipe invert elevations and other system geometry data that

still need to be updated.

Update the City GIS data to include some new manhole inverts that were added as noted in the model.

In the future, the GIS data will always be the parent data and the model will be updated based on the

latest GIS data. Continue to identify and update corrections for the system GIS files and then update the

model.

System Infiltration - The total approximate base flow recorded at the treatment lagoons during winter

months is approximately 3,750 gallons per minute (GPM) based on the flows recorded during the very

early morning hours of winter days. The base flow during the summer is approximately 7,750 GPM. It is

probable that a large portion of the base flow comes from groundwater infiltration with some flow


Logan City P a g e | ix Sewer Collection System Master Plan

being sanitary flow produced mainly by industrial users that operate during early morning hours. A very

large portion of the infiltration comes from the island area.

Implement more flow monitoring in the island area during the summer months to identify more specific

sources of infiltration. This will lead to more effective efforts to reduce the infiltration.

Implement infiltration reduction methods, such as sealing open pipe joints. An ongoing fund needs to

be included in the budget to implement this maintenance program. This program will result in sewer

treatment savings if I&I is successfully reduced.

System Inflow - Small amounts of inflow were observed as a result of some small rain events recorded

while gathering flow data for this master plan. Infiltration is a much larger flow contributor to the

system then inflow from small rain events.

Collect flow data during large rain events for an accurate evaluation of the impacts of inflow on the

system.

Existing Pipes Near Capacity - Some existing pipes appear to be approaching capacity in the model (See

Figures 5 and 6).

As development occurs, the existing d/D and reserve capacity figures should be referenced to determine

where areas of concern may be. The model should also be updated to reflect new flow conditions as

new routing or new development happens.

Existing Poor Condition Areas - Some pipes in the existing system are known to be problem areas or

pipes that are deteriorated (See Figure 8). These pipes are listed in the report in Table 3-3 with the

estimated replacement costs.

Repair or replace the listed pipes. The condition of the existing pipe located in 400 North from 700 East

to Main Street is of particular concern and should be repaired/replaced as soon as possible.

Existing Over Capacity Areas - Some small isolated pipes in the existing system are over capacity at peak

flow times (See Figure 8).

Design and build the improvements listed in Table 3-4 of the report to add additional capacity as soon as

possible. The improvements are listed in order of priority.

Existing Lift Stations – New pumps will be needed at the existing lift station at the airport in the next

few years. Improvements are currently being made to the Providence lift station by city staff. New

pumps will need to be added to the West Regional Lift Station in the year 2025.

Install two pumps at the Airport lift station. Continue to monitor the existing lift stations and upgrade as

needed. Plan to add two new pumps to the West Regional Lift Station in the year 2025.


Logan City P a g e | x Sewer Collection System Master Plan

Future Areas Near Capacity - Some additional pipes appear to be approaching capacity in the model at

the Build Out time frame (See table in Appendix H).

Continue to maintain and update the model in order to manage future capacity issues.

Future Over Capacity Areas - There are some areas in the existing system that will exceed capacity in

the future based on the assumed growth projections.

Begin plans now to build the 2020 improvements as listed in Table 4-3 of the report.

Future Trunk Lines and Lift Station Upgrades - Many new trunk lines and lift stations will be needed to

serve the areas that will develop in the city in the future.

Size pipes and lift stations based on the conceptual future system plan prepared for this report (See

Figure 19).

Computer Model - The computer model is very detailed and can be used to identify impacts from new

developments.

Utilize the existing model to determine impacts from proposed new developments or areas that plan to

re-develop to higher densities. Update the existing model regularly by importing updated system

information from the GIS databases that are maintained by the Logan GIS department.


Logan City Page 2 Sewer Collection System Master Plan

1 INTRODUCTION

1.1 BACKGROUND

The Logan City sanitary sewer system collects sewer flows from Logan City and other surrounding

communities and transports those flows to the Logan wastewater treatment facility located near 600

North 1900 West in Logan, Utah.

There are approximately 895,000 lineal feet of pressure and gravity sewer pipe in the collection system

ranging from 4-inch diameter to 60-inch diameter. The majority of the collection pipes are 8-inch

diameter totaling approximately 589,000 feet in length.

Logan has grown significantly over the last few decades as shown in Table 1-1 (United States Census

Bureau, n.d.) (Utah Governor's Office of Planning and Budget, 2013).

Table 1-1: Logan City Growth Table

Logan City Growth

Year Population Average Annual

Growth Rate

1990

33,022

2.6%

2000 42,713

1.2%

2010 48,174

Logan continues to see growth around its outer edges and growth from re-development in its center as

areas re-develop to higher densities. The collections system serves six surrounding cities that will also

continue to grow. The following cities are connected to the collection system:

• Smithfield

• Hyde Park

• North Logan

• River Heights

• Providence



• Nibley

The trunk lines in the collection system that serve these cities need to be large enough to continue to

convey the flows that will come with the future growth.

The City hired J-U-B ENGINEERS, Inc. (J-U-B) to evaluate the capacity of the existing collection system,

and propose system improvements to accommodate projected growth. There are four time-frames

analyzed in this plan as listed in Table 1-2 below.

Table 1-2: Time Frames Analyzed

Time Frames Analyzed

Title

Description

2014 Existing flows during summer irrigation months when infiltration is high

2020 Projected 2020 flows during summer irrigation months


Build Out

Projected flows during the summer irrigation months at build out. Build out is defined as the condition when all of the areas in the future boundaries of the City develop to the planned densities as identified in the 2015 Water Master Plan and the contributing cities reach their projected 2060 populations as estimated by the Governor's Office of Planning and Budget (GOPB).

The goals of the master plan are:

• Create a detailed model that is efficient to operate and update

• Identify existing system capacity and condition deficiencies

• Identify future system deficiencies

• Master plan a collection system to serve Logan at build out

• Provide a prioritized list of capital improvement projects needed for 2020, 2025, and build out

• Train City staff to operate and update the model

A master plan is an essential element for any community experiencing growth. With a master plan, a

community has a tool to guide infrastructure improvements. This master plan provides direction to



continue providing adequate sewer collection services as new areas develop and existing developed

areas re-develop.

1.2 PROJECT TASKS

J-U-B performed the following tasks to complete the plan:

• Gathered system information and flow data from Logan City

• Mapped the existing collection system utilizing data provided by Logan City

• Added sanitary flows to the collection system based on winter culinary water meter data as

recorded by City water meters

• Analyzed existing sewer flow meter data provided by the City

• Performed a preliminary model calibration using existing flow data

• Recommended temporary flow data collection sites to measure summer flows during high

infiltration

• Collected flow data from 13 simultaneous temporary meter sites during the summer months to

record the high infiltration flows

• Calibrated the model to match the metered flows

• Met with City staff to identify poor condition locations in the system

• Identified existing system repairs, capacity deficiencies and areas to monitor

• Made future flow projections for 2020, 2025 and build out based on input from City Staff

• Identified system improvement projects needed for 2020, 2025 and build out

• Master planned a conceptual collection system to serve areas that will develop in the future

• Prepared prioritized lists of improvement projects and areas to monitor for each of the future

time frames analyzed

• Listed conclusions and recommendations drawn from the master plan study

• Provided model training for the city staff

A central component of these tasks is the use of computer modeling software to simulate current and

future sanitary sewer system capacity. The software and planning parameters used for this study are

discussed in greater detail in Chapter 3.

1.3 MASTER PLAN PURPOSE

The main purpose of the master plan is to provide a planning document and tools that help Logan City

meet its future sewer collection needs. This report serves as the planning document. The main tool is

the computer hydraulic sewer model. The model is detailed enough to allow each new development or

re-development to be evaluated to verify its potential impact on the collection system. Re-development

can significantly change peak flows in collection pipes near the re-developed area. For example, a multi-

story, multi-family building constructed in the place of a single family home will greatly increase the

peak sewer flows that may enter the collection system. The re-development may be connected to an



existing 8-inch sewer pipe that already is approaching its capacity limits. Every pipe in the system has

been modeled to allow for capacity checks of the pipes in these types of situations.

Conditions may change and ultimately affect the master plan. The analysis and recommendations

contained herein should be updated as necessary. The City should revisit this document and the model

prior to engaging in detailed design of any sanitary sewer facilities to verify that the model and

conclusions are still valid. The model and plan should be updated and verified with any significant

changes to the system.



2 DATA COLLECTION

2.1 INTRODUCTION

A large amount of data was required to build a model of the collection system. Existing system mapping

information, existing water use data and sewer flow data were needed. The software used for the

mapping was ArcGIS software Version 10.2.2.

2.2 EXISTING SYSTEM MAPPING

The existing collection system is shown in Figure 1: Existing Collection System (All of the report figures

are included in Appendix A and bound separate from this report). The information needed to create the

existing system figure was obtained from the City GIS department.

The following items are included in the mapping:

• Aerial image of the City

• Existing gravity sewer lines

• Existing private and City owned lift stations and associated pressure force mains

• Existing Logan City limits

• Points of connection from other cities

• Street labels

J-U-B met multiple times with City staff during the system mapping process to review the sewer

collection data and make adjustments as needed. Through this process, some updates were made to

the existing system for the model as described in the following sub-sections. The City GIS data needs to

be updated to include some new manhole inverts that were integrated and noted in the existing sewer

system model. In the future, the GIS data will always be the parent data and the model will be updated

based on the latest GIS data.

2.2.1 System Connectivity

The system connectivity had to be created to allow the model flows to be conveyed through the

system. All of the manholes in the system needed elevations in order to complete the

connectivity. The following steps were followed to create the system connectivity:

• Identified the manholes that were missing elevations

• Met with the GIS department to review the missing elevations

• Developed a plan with the GIS department to receive the updated data

• Entered the new invert elevations to the model

• Interpolated some elevations that did not come with the updated GIS data

• Added notes on manholes that we interpolated



At the meeting, it was discussed that the GIS department may not be able to identify all the

inverts and that some of the manholes would need to be interpolated. The City gathered or

calculated many more elevations, but there were still a few manholes that needed elevations.

These elevations were interpolated where possible using the manholes with elevations. Notes

were made in the model to track manholes with elevations that were calculated rather than

surveyed.

There were also many pipes in the system that were not connected together. These were

connected in the model in order for the model to run. J-U-B re-drew the un-connected pipes

from the upstream manhole to the downstream manhole and added notes to the pipes that

were adjusted.

2.2.2 Sewer Cleanouts

There are many small dead end pipes in the system that are stubbed out for future services or

line extensions but not connected to any manholes. J-U-B identified these and added manholes

or removed the pipe from the model. J-U-B added notes to all the pipes, manholes and

cleanouts to provide an identifier indicating if they were to be used in the model. J-U-B added a

cleanout or removed the dead end pipe from model at each dead end location

2.2.3 Lift Station Information

The City has multiple lift stations (Figure 1) that are needed to convey some of the flows that

come from within Logan and some of the flows that come from other cities to the treatment

facility. Pump information and wet well geometry information for the lift stations was given to

J-U-B in the form of record drawings and entered into the model.

2.2.4 Reverse Grade Pipes

The collection system GIS file from the City has some reverse grade pipes. The following steps

were taken to determine if the pipes were truly sloping the wrong direction or if the pipe

elevations needed to updated or corrected:

• J-U-B identified pipes in the system with reverse grades

• Logan and J-U-B met and decided that pipes with more than 0.4 feet of reverse

elevation difference between manholes would be verified by the City and that the city

would give updated elevations to J-U-B for the model

• J-U-B input the corrected and interpolated elevations provided by the City

• There are still 39 gravity pipes identified in the model with less than 0.4 feet of reverse

elevation difference. The model cannot calculate flows for gravity pipes with reverse

grades. For the hydraulic calculations, the modeling software assumes that the reverse

grade pipes have a downstream invert elevation that is 0.001 feet lower than the

upstream invert elevation. The elevations that are provided in the model inputs are not

changed by the model software. These pipe segments are listed in Table 2-1.



Table 2-1: Reverse Grade Slope Summary Table, S < 0.4

REVERSE GRADE PIPE SUMMARY

GIS ID UPSTREAM

INVERT DOWNSTREAM

INVERT NEAREST INTERSECTION/DESCRIPTION

SM00826 4492.815 4493.207 100 S/600 W (Runs in 600 W)

SM01007 4527.949 4527.949 400 N/100 E (Runs in 100 E)

SM01373 4516.367 4516.461 Center St./100 W (Runs in 100 W)

SM02087 4472.422 4472.422 1960 S/1100 W (Runs in 1100 W)

SM02179 4464.005 4464.282 Near Country Manor LS

SM02306 4459.495 4459.57 1800 N/600 W (Runs in 1800 N)

SM02331 4462.84 4462.86 Rosewood Circle

SM02493 4487.041 4487.053 800 S/Riverwood Dr. (Runs in 800 S)

SM02510 4472.453 4472.528 880 S/Park Ave. (Runs in 880 S)

SM02522 4788.162 4788.168 Davis Ave./Hillcrest Ave. (Runs parallel to Davis behind homes)

SM02523 4788.168 4788.273 Davis Ave./Hillcrest Ave. (Runs parallel to Davis behind homes)

SM02528 4439.449 4439.525 600 N – Near sewer lagoons

SM02554 4485.386 4485.542 100 W Hwy. 89

SM02603 4457.657 4457.813 1925 S (Connection between Rosehill Develp. and housing to the east)

SM02644 4525.421 4525.423 South of Home Depot (Runs parallel to Main St.)

SM02682 4791.085 4791.235 1220 N 600 E

SM02822 4463.692 4463.692 Between 1780 S and 1750 S

SM02893 4471.104 4471.177 Between 400 W and 600 W north of 1600 N

SM02920 4467.204 4467.26 Between 400 W and 600 W north of 1600 N

SM02956 4537.617 4537.648 100 S/500 E

SM03093 4527.988 4528.124 300 S/400 E (Runs in 400 E)

SM03154 4485.477 4485.596 1200 N/400 W (Runs in 400 W)

SM03177 4434.366 4434.475 1800 S/2000 W (Runs in 200 W)

SM03184 4483.976 4484.042 Riverwalk Pkwy/Golf Course Rd. (Back of townhomes)

SM03203 4441.084 4441.223 600 N – Near sewer lagoons

SM03292 4443.993 4444.262 200 S/1000 W (North of Codale Elec.)

SM03421 4437.396 4437.399 2500 N/900 W (Runs along 900 W)

SM03683 4468.617 4470.88 600 S/Park Ave.



REVERSE GRADE PIPE SUMMARY

GIS ID UPSTREAM

INVERT DOWNSTREAM

INVERT NEAREST INTERSECTION/DESCRIPTION

SM03693 4425.786 4425.85 600 S/2000 W (Runs in 2000 W)

SM03703 4469.789 4470.2 760 S/Park Ave. (Runs in Park Ave.)

SM03713 4445.983 4446.05 200 S/1000 W (Runs in 1000 W)

SM03720 4451.957 4452.223 200 S/1000 W (Runs in 1000 W)

SM03734 4553.551 4553.551 200 N/200 E (Runs in 200 E)

SM03824 4444.85 4444.88 200 N/1000 W (Runs in 1000 W)

SM03833 4443.89 4443.89 600 N/1000 W

SM03837 4446.753 4446.83 1000 N/1000 W (Runs in 1000 N)

SM03839 4449.662 4449.697 1400 N/1000 W (Runs in 1000 W)

SM03917 4467.781 4468.026 200 S/Rosewood Cir. (Runs in Rosewood Cir.)

SM04043 4521.559 4521.634 200 S/200 E

2.2.5 Flow Routing Adjustments

There are many manholes in the system that have two or more pipes that exit. The modeling

software splits the flows at these manholes based on the elevations of the exiting pipes and

based on the flow path of least resistance. The accuracy of the flows in the pipes downstream

of the split manholes is dependent on accurate outgoing pipe elevations, pipe sizes and slopes.

J-U-B worked with the Logan GIS department to field check as many of these locations as

possible and input updated information into the model. The following steps were followed:

• J-U-B queried the model to find the manholes with more than one pipe exiting

• J-U-B met with City staff to develop a strategy to gather more invert and flow routing

data

• City staff checked the manholes in the field:

o If outgoing inverts were different, they collected survey shots on the inverts and added new invert elevations to the system shape files

o If outgoing inverts were the same, they made an estimate of what percent of the incoming flow goes to each of the outgoing pipes

o Other notes such as “All flows go west until pipe is more than half full, then flows are split 50/50” were made

• J-U-B imported the new data and checked the flow routing

Multiple iterations of this process were followed to update the flow routing in the model.



2.2.6 Drop manholes

There are many drop manholes in the existing collection system. Drop manholes are typically

found in steeper areas of the City. They often can be identified in the field by having two inlet

pipes (one a few feet directly above the other) on the upstream side of the manhole with the

upper inlet being mostly dry or completely dry. The dry pipe is representative of the elevation of

the pipe upstream of the manhole as it approaches the manhole. However, at a close distance

from the manhole, the upstream pipe has a vertical tee installed with some vertical elbows that

drop the incoming flow through a lower pipe to an elevation that is close to the bottom

elevation of the manhole it enters.

Logan City staff provided drop manhole information that has been recorded by the GIS

department. There are still some drop manholes in the actual system that need to be input into

the model. Over time the City should continue to identify drop manholes and update the drop

manhole information in the system GIS files.

2.2.7 Pipe Diameter Adjustments

J-U-B identified some pipes in the mapped system data with sizes that did not appear to be

correct. For example, there were a few trunk lines in the data that had pipes that were smaller

than expected based on comparisons with the surrounding pipes. Some of the pipe sizes were

updated in the model after verifying the actual sizes out in the field with Logan public works

staff.

2.3 SANITARY SEWER FLOWS

The sanitary flows are the flows in the system that come directly from homes or businesses. These

flows do not include any extra flows that may enter the collection system along the way to the

treatment facility in the form of infiltration or inflow (I&I).

The sanitary flows were estimated by assuming that the daily sanitary sewer volumes from each sewer

connection are equal to the culinary water usage as recorded by individual water meters during the

winter months. During the winter, most of the culinary water that is used enters the sewer collection

system because no water is being used for outdoor watering. J-U-B obtained water usage data by

gathering water meter records from the City’s water database for the winter season of 2013-14. J-U-B

reviewed this data and selected the highest usage month to use for the model, which was November

2013. J-U-B estimated the daily volume at each meter location by taking the total volume recorded for

November 2013 and dividing by 30 days.

2.4 TOTAL FLOWS

The total flows in the collection system consist of the sanitary flows along with flows that enter the

system in the form I&I. Flow data is critical to quantify the effects of I&I on the flows in the system.



Flow data is most useful for collection system master planning when it represents the highest seasonal

flows that pass through the system. This allows for future pipe sizing that is adequate to convey the

peak seasonal flows. Based on past meter records at the treatment lagoons, the highest flows during a

given year typically occur in the summer time around July and August. The higher flows in the summer

are typically made up in large part by increases in infiltration.

2.4.1 Infiltration

Infiltration consists of groundwater that enters the sewer system through open joint pipes,

cracks in pipes, faulty service connections, leaky manhole joints and poor seals at the

connections between pipes and manholes. Infiltration flows are typically slightly less than the

total flow in a collection system during the very early morning hours when most of the people in

the city are asleep. Graph 2-1 shows the wintertime flows recorded at the sewer treatment

lagoons during the month of November 2013.

Graph 2-1: Wintertime Sewer Flows

The base winter nighttime flows (infiltration) as recorded by the treatment lagoons meter are

approximately 3,750 gallons per minute (GPM).

In Logan, many irrigation canals pass through the city and carry water during the summer

months. With so many canals located close to sewer collection lines, there is potential to have

increased groundwater infiltration when the canals are carrying irrigation water. Graph 2-2

shows the summertime sewer flows at the treatment lagoons as recorded during parts of July

and August 2014.



Graph 2-2: Summertime Sewer Flows

The base summer nighttime flows recorded at the lagoons are approximately 7,750 GPM. The

recorded summer infiltration flows were approximately 4,000 GPM greater (approximately two

times greater) than the winter infiltration flows recoded at the treatment lagoons.

2.4.2 Inflow

Inflow is surface storm water that enters into the sewer system during or after a storm event.

Inflow enters collection systems through manhole covers and direct connections such as roof

drains, foundation drains, and storm sewer connections. One way to estimate the amount of

inflow in a system is by comparing metered flows during rain events with metered flows

recorded at times without rain. Graph 2-3 shows the flows at the treatment plant during the

same summer metering period along with the precipitation data recorded at the Logan-Cache

Airport.



Graph 2-3: Summertime Sewer Flows and Precipitation

The largest storm recorded during the meter period occurred just after midnight on July 30th.

This storm lasted approximately 6 hours with a total of 0.43 inches recorded at the Logan-Cache

Airport. This was a significant rain event but not rare with a return period of less than 1 year. A

1 year 6-hour storm in Logan has a total depth of 0.7 inches.

Collection systems need to be designed to convey daily peak sanitary flows plus the peak

seasonal infiltration and any inflow that may enter the system during a rain event.

Based on the data collected in Logan for this study, infiltration is a much larger flow contributor

to then inflow from rain events. More flow data during rain events needs to be evaluated to gain

a better understanding of the inflow to the system due to rain. More specifically, more data is

needed during large rain events to understand how the system flows change as a result.

A few other observations are made based on the flow data in Graph 2-3. First, the base

nighttime flows in the system increased over a period of three or four days surrounding the

short rain events that occurred. These increases indicate that the collection system has some

delayed inflow or rainfall-induced infiltration around wet periods of time. Delayed Inflow is

defined as the portion of total inflow that is generated from indirect connections to the

collection system or connections that produce inflow after a significant time delay from the

beginning of a storm. Delayed inflow sources include: sump pumps, foundation drains, indirect

sewer/drain cross-connections, etc. Rainfall-induced infiltration cannot be distinguished from

delayed inflow and is therefore included as part of delayed inflow. Delayed inflow sources have



a gradual impact on the collection system and flow decreases gradually upon conclusion of the

rainfall event, and after peak inflow caused by direct connections (EPA, 2014).

Some short duration increases in the recorded flows occurred during or right after some of the

recorded storms. For example, the nighttime flows recorded immediately after the storm that

occurred in the very early morning hours of July 30th were significantly higher than other

recorded nighttime flows. This is likely because of inflow that quickly entered the system

during, or right after the 6-hour storm. Inflow that enters the system quickly through direct

connections is called direct inflow. Direct Inflow is defined as the portion of total inflow which is

from direct connections to the collection system such as catch basins, roof drains, manhole

covers, etc. These inflow sources allow storm water runoff to rapidly impact the collection

system (EPA, 2014).

2.5 SUMMER FLOW DATA COLLECTION

Temporary flow meters were installed during the summer of 2014 in order gather flow data needed to

have a well calibrated sewer model to match the higher seasonal summer flows. These meters were

installed at strategic locations throughout the collection system. The flow data was combined with

other meter data that Logan collected during the same meter period from permanent meters at the

existing lift stations and at the treatment lagoons.

2.5.1 Summer Meter Schedule

Flow data was collected throughout the collection system for a three-week period from July 22,

2014 through August 12, 2014. The start and end dates for the data collection vary slightly for

some of the meter sites

2.5.2 Summer Meter Equipment

J-U-B rented twelve Hach 910 area velocity flow monitors and used one March McBirney Flo-Dar

meter owned by Logan City to collect flow data from 13 temporary sites. These monitors

measured flow depths and velocities to calculate flow and recorded measurements at five-

minute intervals during the metering period. Having multiple meters collecting data throughout

the City at the same time allows for a comparison of flows and helps to isolate areas of interest

or concern.

The Hach 910 meters were equipped with submerged depth velocity sensors that use a pressure

transducer to measure flow depths and measure velocity with sound waves, using the Doppler

principle. The Flo Dar meter consists of a radar-based velocity measurement system and an

ultrasonic-based pulse echo depth measurement system.

Logan City provided additional flow data for the same meter period that was recorded at

permanent meters located at the treatment lagoons and at some of the large lift stations in the



system. Many of the permanent meters measure flows from the surrounding communities that

are connected to the collection system.

2.5.3 Summer Meter Locations

The locations of the temporary summer meters are listed in Table 2-2 and shown in Figure 2:

Flow Meter Locations. Table 2-2 also gives information about the pipe size metered and the

start and end dates of the collected meter data. The meter locations in the table include a

facility identification number which is the numbering system the City uses for all of the

manholes in the collection system.



Table 2-2: Temporary Flow Meters

TEMPORARY FLOW METER SITES

METER FACILITY ID LOCATION DESCRIPTION METER PERIOD

1 SEMH00644 In parking lot along the east side of 1000 West Street at approximately 1075 North and 400 to 500 feet east of 1000 West Street

7-22-14 to

8-11-14

2 SEMH01058 1400 North 875 West 7-22-14

to 8-12-14

3 SEMH00601 1000 North 975 West 7-22-14

to 8-11-14

4 SEMH00403 600 North 990 West 7-22-14

to 8-12-14

5 Man Hole east of

SEMH00408 by 120 feet 325 North 950 West (in parking lot just east of 950 West street)

7-25-14 to

8-11-14

6 SEMH03164 200 South 930 West 7-22-14

to 8-11-14

7 SEMH01611 200 South 950 West 7-22-14

to 8-11-14

8 SEMH01634 835 West 600 South 7-22-14

to 8-11-14

9 SEMH01996 1400 North 750 East 7-23-14

to 8-12-14

10 SEMH01412 1350 East 1405 North 7-30-14

to 8-12-14

11 SEMH01997 800 East 1350 North 7-23-14

to 8-12-14

12 SEMH01025 750 East 700 North 7-23-14

to 8-12-14

13 SEMH00116 700 East 435 South 7-23-14

to 8-12-14



2.5.4 Summer Flow Data Evaluation

J-U-B graphed and evaluated the data collected by the temporary flow meters for the summer

flow meter period. The following graphs are included in Appendix B for each of the temporary

meter sites:

• Flow vs. Time

• Depth and Velocity vs. Time

• Velocity vs. Level Scatter Plot

The Flow vs. Time graphs include the amount of precipitation in inches that was recorded on an

hourly basis at the Logan Cache Airport during the summer meter period. Notes and

conclusions about the flows recorded at each of the temporary sites are included in Appendix C.



3 EXISTING SYSTEM ANALYSIS

3.1 INTRODUCTION

J-U-B created and calibrated a computer model to simulate and analyze the existing flows in the

collection system. The model was created using InfoSWMM 5.1 modeling software which is a product of

Innovyze Incorporated. InfoSWMM functions within ArcGIS software which allows for easy assimilation

of other City mapping that is contained in Geographic Information Systems (GIS) shape files. The

computer model and findings meet Utah Department of Water Quality capacity verification

requirements for large collection systems.

3.2 COLLECTION SYSTEM REGULATORY REQUIREMENTS

The Utah Department of Water Quality requires any municipality, or other political subdivision of the

state that owns and operates a sewer collection system to comply with the Utah Sewer Management

Program (USMP) as defined in Rule R317-801 of the Utah Administrative Code. Under the USMP, Logan

City is required to have and implement a written Sewer System Management Plan (SSMP). Logan has a

written plan that was completed in August of 2015 that meets the state requirements.

The SSMP covers:

• General organizational structure for the system

• Operation and maintenance of the system

• Sewer defects

• Sewer design standards

• Sanitary Sewer Overflow (SSO) actions

• Grease, oil, sand and commercial management

• Monitoring and measuring

• System mapping

• Sewer backup flows

Larger collection systems must also complete a System Evaluation and Capacity Assurance Plan (SECAP)

to identify any potential system capacity deficiencies and a capital improvements plan to address

capacity deficiencies. The Logan City collection system falls within the larger system category and is

required to have a SECAP. The work done for this master plan meets the SECAP requirements for Logan

City.

3.3 DEVELOPMENT REQUIREMENTS

All new sewer system improvements within the city need to be constructed to meet current Logan City

and State design requirements. This is true for public systems as well as sewer systems that are

constructed as private utilities including collection piping and lift stations.



The city standards for design and construction shall be used in conjunction with Utah Administrative

Code R317-3. Where a conflict exists between these two standards, the Administrative Code shall

prevail.

3.4 MODEL DEVELOPMENT AND ASSUMPTIONS

The hydraulic model consists of following inputs:

• Collection system geometry

• Flow input locations

• Sanitary flows

• Lift Station parameters

• Daily sanitary flow patterns (Diurnal Curves)

• Infiltration flows

• Flows from others and large water users

The key assumptions used in the existing system model are explained in the following sections.

3.4.1 Collection System Geometry Assumptions

The system geometry (Figure 1) consists of all of the collection system components such as:

• Gravity pipes

• Manholes

• Lift stations

• Force mains

• Diversions

• Other ancillary items such as pumps

Each of the components has attributes assigned such as ground elevations, invert elevations,

sizes etc. The attributes were provided by the Logan City GIS department and include some

updates made during the model building process as errors or discrepancies were found. Notes

have been added in the system attributes table within the model where changes were made to

the system geometry data. Updating and adding data to the system layer in the model will be

an ongoing effort in the future for the City to continue to improve the accuracy of the model.

3.4.2 Flow Input Location Assumptions

J-U-B added flows to the collection system based on the water meter database provided by the

City in a two-step process.

1. Assigned each water meter to the nearest sewer pipe and then to the sewer collection

manhole immediately upstream



2. Reviewed the sewer lateral map data that was provided by Logan city to adjust flow input

locations as needed

3.4.3 Sanitary Flow Assumptions

The daily sanitary flows (no I&I) in the system are equal to the daily culinary water use during

the winter months. These flows were added based on the winter culinary water meter database

that was provided by the City as described in Section 2.3 of this report. A small amount of flow

was added to parks and other open spaces based on the estimated number or fixture units in

restrooms or other plumbed structures. The flows from the open spaces are very minimal.

3.4.4 Pump Parameter Assumptions

The parameters of the pumps in the existing lift stations were added based on data provided by

the City from as-built records.

3.4.5 Diurnal Curves Assumptions

Sewer flows vary throughout the day. The flow patterns during the day are known as diurnal

curves. These diurnal curves allow the modeling software to quantify the flows throughout the

day for the various types of land use. J-U-B initially input 5 different diurnal curves in the model

that have been developed and adjusted by J-U-B over time to match flows that have been

recorded in areas made up of the following flow land use categories:

1. Residential

2. Commercial

3. Industrial

4. Open Space (Parks with restrooms)

5. School

These diurnal curves were adjusted during the calibration process (Section 3.3) to match the

flows recorded by the flow meters. Graph 3-1 below shows the diurnal curves used in the

model. The graph gives the percentage of the total daily volume that is assigned to each hour

during the day for each of the curves. The diurnal curves represent only the sanitary flows and

do not include any inflow or infiltration.



Graph 3-1: Diurnal Curves

J-U-B assigned one of these diurnal curves to each of the sanitary flows added to the model

based on the land uses that were included in the water meter databased provided by the City.

There are many land uses in the City that could generate slightly different diurnal curves, but for

the model, the curves were consolidated into the 5 major types shown in Graph 3-1. The land

uses associated with the water meter database provided by the City are listed below in Table 3-1

along with the diurnal curve that was assigned for each of those land uses.

0%

2%

4%

6%

8%

10%

12%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

PER

CEN

T O

F D

AIL

Y F

LOW

HOURS

DIURNAL CURVES

RESIDENTIAL

COMMERCIAL

INDUSTRIAL

OPEN SPACE

SCHOOL



Table 3-1: Diurnal Curve Assignments

Diurnal Curve Assignments

City Land Use Diurnal Curve Assigned in Model

CR

Residential

MH

MR-12

MR-20

MU

Not Logan

NR-6

PUB

TC

AP

Commercial

COM

Community Commercial

CS

GW

MU

NC

Not Logan

PUB

REC

TC

IP Industrial

PUB

MU

Open Space PUB

REC

PUB

Schools MU (USU)

PUB (USU)



The diurnal flow pattern assignments for the existing and future service areas are mapped in Figure 3:

Diurnal Curve Pattern Assignments. The undeveloped parcels and some areas that are not connected to

the sewer do not contribute flows in the existing model and were not assigned a flow pattern. Sanitary

flow volumes are based on individual water meter data and not on the diurnal flow pattern.

3.4.6 Infiltration Assumptions

Infiltration is assumed to be a constant base flow that is approximately equal to the average

nighttime base flows. The meter data used to estimate infiltration was recorded by the

temporary flow meters that were installed in July 2014 along with data from permanent meters

for the same time period.

Because of the limitation on the number of temporary meters installed, some assumptions were

made about what localized areas may have more infiltration than other areas. For example, the

island area near the Logan River has high ground water levels and many sections of older pipe

that are not water tight. Because of these and other factors, this area was designated very high

infiltration. On the other hand, some of the areas on the east bench have much lower

infiltration because the pipes are newer, the ground water level is deeper in the ground and the

soils in these areas drains much more freely.

The developed part of the City was divided into regions and categorized into 5 different rates of

infiltration. A proportionate fraction of the total infiltration in a region was assigned to each

manhole within the region. The rates of infiltration per manhole were adjusted in each of the

regions until the base nighttime flows in the model matched the base nighttime flows recorded

by the temporary flow meters. Areas that will develop in the future do not add any infiltration

to the existing model.

The infiltration regions and the rates assigned to each region in the City are shown in Figure 4:

Infiltration Rates. Table 3-2 lists the 5 existing infiltration rates used and the flow added as

infiltration at each manhole for each of the assigned rates.



Table 3-2: Infiltration Rates

Infiltration Rates

Name Infiltration Added per Manhole

(gpm)

Very Low 0.2

Low 0.5

Medium 0.6

High 3.2

Very High 3.8

3.4.7 Inflow

No inflow was added to the model because:

• The infiltration flows measured in the system in the summer are much greater than the

flows that may be added by inflow during a typical summer rain event. The small rain

events that were recorded during the summer meter period did have some varying

effects on the flows in the system depending on the location in the system.

• More sewer flow data needs to be collected and evaluated during large storm events to

quantify the effects from inflow.

3.4.8 Flows from Others and Large Water Users

The following cities near Logan are connected to the collection system (Figure 1):

• Smithfield

• Hyde Park

• North Logan

• River Heights

• Providence

• Nibley

Providence City has two connection points and Smithfield and Hyde Park share a single

connection point. Each connection has a flow meter that records the flows as they enter the

collection system. Flows were added to the model at the connection points to simulate the



flows that enter from each of these outside communities. The flows were shaped into diurnal

flow patterns to match the patterns recorded by the meters. The flow patterns recorded by the

meters from the contributing communities are included in Appendix D.

Utah State University (USU) is another large contributing entity that is connected to the

collection system at multiple locations. Winter-water usage data was used to estimate the

sanitary flows that come from USU in the same fashion as sanitary flows were added throughout

the rest of the City. Summer infiltration from USU was estimated based on flow meter data

from the summer temporary meters as explained in Section 3.2.6. USU has many small pumps

from building basements that turn on and off multiple times during each day for short periods.

These pumps add very little volume to the system with short peaks that attenuate quickly in the

collection system.

Tyco Electronics is a large industrial water user located at 710 North 600 West in Logan that is

connected to the sewer collection system. Hourly water use data from meters at Tyco were

used to create a more accurate diurnal flow pattern.

The flows from other large water users such as Gossner Foods and Schreiber Foods are based on

monthly winter water use. The typical industrial diurnal flow pattern was assigned to these

water users and other industrial water users.

3.5 COST ESTIMATING ASSUMPTIONS

The model development is important because it identifies areas where existing or future system

deficiencies exist in the collection system. Deficiencies are typically addressed by making some kind of

improvement to the system. Funds are required to make most sewer system capacity improvements.

At the master planning stage, many assumptions are required to estimate the costs of future

improvements because there is a fairly high level of uncertainty about challenges or obstacles to

projects that will not be identified until a design process is completed. As a given improvement gets

designed, the uncertainty is reduced. J-U-B has prepared conceptual cost estimates for improvements

that are needed in the collection system now, at year 2020, year 2005 and at build out.

Cost estimates for this plan are based on J-U-B bid tabulation records for sewer collection and lift station

projects and pipe material costs provided by pipe suppliers. For piping projects, it is assumed that the

improvements will be made utilizing conventional open-cut construction in city roadways with manholes

will be placed every 350 feet. The project costs include an additional 40% factor (40% of the estimated

construction cost) to account for engineering services and for uncertainty in items that will be required

for construction. A basic unit price summary table is included in Appendix E.



3.6 MODEL CALIBRATION

J-U-B calibrated the model by adjusting the inputs until the model flows matched the existing system

flows as recorded by the meters. The first step in the calibration process is to choose a day with

relatively high flows to match with the computer model flows. A day with relatively high peak flows is

desired in order to avoid underestimating existing and future flows which may lead to having an

unexpected exceedance of system capacity.

As mentioned earlier in the report, the flows in the system are typically the largest in the summer when

irrigation water is in the irrigation ditches. Upon reviewing the flow data collected in the summer of

2014, Monday July 28, 2014 was selected as the day to match with the model.

In many collection systems, peak flows during a week occur on weekends when people are at home.

However, the peak flows recorded in Logan on the weekdays were higher than during the weekends.

This is probably because a large portion of Logan’s flows come from commercial and industrial entities

that do not operate on the weekends.

Calibration involved an iterative process of superimposing the flow graphs from the temporary flow

meters and from the treatment plant from July 28, 2014 over the model-generated diurnal flow curves.

Then, the flow generating model parameters (diurnal curve shape, infiltration etc.) were adjusted to

match the metered flows. An example calibration flow graph is shown below in Graph 3-2 for the

temporary meter that was installed near the North Logan connection point.

Graph 3-2: Example Calibration Flow Graph

400

600

800

1000

1200

1400

1600

28

-Ju

l

29

-Ju

l

FL

OW

(g

pm

)

DATE - July 28, 2014

1 - 1000 W Parking Lot

Meter

Model data



All of the flow calibration graphs are included in Appendix F to show how the model flows compared to

the actual metered flows. A summary of how the flows in the calibrated model compared to the flows

measured by the flow meters is tabulated in Appendix G.

3.7 EXISTING SYSTEM EVALUATION

The existing model simulates the existing flows based on the winter culinary water usage plus summer

infiltration to match the flows recorded in the system on Monday July 28th 2014. Four specific items

were evaluated as part of the existing system evaluation:

1. Depth of Flow over Diameter of Pipe (d/D)

2. Reserve Capacity

3. Hydraulic Grade Line Profiles

4. System Condition

5. Lift Station Analysis

3.7.1 Depth of Flow over Diameter of Pipe (d/D)

A quick way to display how well a collection system accommodates flows is by observing the

depth of flow in a pipe as a ratio of the pipe’s inside diameter. The illustrated pipe shown in

diagram 3-1 below represents a pipe flowing less than half full.

A pipe that is full would have a d/D value of 1.0. While a pipe flowing half full would have a d/D

value of 0.5. Larger pipes are able to handle more flows than are smaller pipes, at equivalent

d/D values. Larger pipes have more reserve capacity per increment of d/D value.

The InfoSWMM modeling software reports d/D values based on the hydraulic grade line

throughout the collection system. If there is a downstream choke point in the collection system

that causes the water to back up and raise the hydraulic grade line to levels above the top of a

pipe, InfoSWMM reports a d/D value of 1.0. The d/D values typically vary along the length of

pipe segments. Some pipe segments have flows that transition between full or partially full.

The d/D values recorded in this report are at the upstream end of each pipe segment in the

model.

Diagram 3-1: Pipe Flow Less than Half Full



The existing depth of flow over diameter of pipe (d/D) for each pipe in the existing collection

system is shown in Figure 5: Existing Depth over Diameter. These are the d/D values for each

pipe segment with existing flow conditions during the peak flow time of the day. Currently

there are a few isolated areas with full pipes (d/D > 0.93). The maximum non-pressurized

capacity of a pipe is achieved at a d/D Value of 0.93 because of increased friction loses created

by the water coming in contact with the tops of the pipes. Most of the full pipes are located in

the island area with a good portion of the full pipes located near 300 South and 200 East.

3.7.2 Reserve Capacity

An equally important measure of system capacity is reported in the InfoSWMM output as

reserve capacity. Reserve capacity is a measure of how much additional flow can be added to

any given pipe segment based strictly on the Manning’s open channel flow equation. The

reserve capacity is calculated for each pipe segment individually without taking into account any

backwater that may be present from a downstream choke point. Reserve capacity can be

reported in various units. For this master plan the reserve capacity is reported in units of gallons

per minute (GPM).

The reserve capacity in each of the existing pipes under 2014 summer flow conditions during the

peak flow time of day is shown in Figure 6: Existing Reserve Capacity. The pipes in the figure are

color coded based on ranges of excess capacity. There are more pipes in Figure 6 that have zero

or negative reserve capacity than pipes that are shown in Figure 5 with a d/D greater than 0.93.

This happens because there are short flat segments of pipe in the system that do not have

enough slope to convey the flows based on the Manning’s equation. However, because the pipe

segments are short and the downstream pipe segments are steeper, the hydraulic grade line

never reaches the top of the pipe. This flow condition is illustrated in Diagram 3-2 below.

Diagram 3-2: Negative Reserve Capacity Illustration

The pipe segment between the two manholes is so flat that the water is beginning to back up.

This is because the capacity of the pipe, based on the Manning’s equation, is less than the peak

flow. If the flat pipe segment were much longer, the hydraulic grade line would rise above the



top of the pipe. In InfoSWMM, the middle pipe segment gets reported as a pipe with negative

reserve capacity even though the water surface never reaches the top of the pipe.

3.7.3 Hydraulic Grade Line Profile Evaluation

Areas that were highlighted in the model as having high d/D values and low reserve capacities

were evaluated further by viewing system profiles in the modeling software. The profiles show

the peak hydraulic grade line through the pipe segments. By evaluating the model profiles, the

pipe segments that are actually causing surcharging (hydraulic grade lines above the tops of

pipes) were identified.

3.7.4 Condition Analysis

Many of the collection system pipes have been in service for a very long time and are

approaching the end of their service lives. As sewer pipes begin falling apart and leaking, more

maintenance is required, more infiltration enters the system and there is some increased risk of

having a road collapse or a large ground sink occur. As such, an ongoing effort to replace or

repair pipes that are in poor condition is important.

The public works staff members that maintain the sewer collection system are aware of areas

that are becoming deteriorated or do not function as needed. J-U-B met with the staff to review

the system and identify the greatest condition problems to address in the capital facilities plan.

J-U-B utilized some tools in the model software to help the City have a better understanding of

which areas are more susceptible to deterioration due to Hydrogen Sulfide (H2S). The velocity

of the flow through a sewer pipe is a significant factor in the amount of potential H2S buildup.

Pipes with slower velocities are more likely to have higher concentrations of H2S. This is due to

the fact that slower velocities allow for more accumulation of solids in the pipes. The

Environmental Protection Agency classified potential sulfide buildup into the following

categories based on flow velocities. (EPA, 1974)

A. Velocity of 2 feet per second - Efficient solids transport. No sulfide buildup in small

flows, up to 2 cfs. Sulfide buildup often observed in larger flows but only at a very slow

rate.

B. Velocity between 1.4 and 2.0 feet per second - Inorganic grit accumulating in the

bottom. More sulfide buildup as the velocity diminishes.

C. Velocity between 1.0 and 1.4 feet per second - Inorganic grit in the bottom, organic

solids slowly moving along the bottom. Strongly enhanced sulfide buildup; severe

problems expected

D. Velocity below 1.0 feet per second - Much organic and inorganic solid matter

accumulating, overlain with slow-moving organic solids. Sulfide problems worse than in

C.



J-U-B classified each gravity pipe segment into one of the four potential sulfide buildup

categories based on the peak velocity from the model output as shown in Figure 7: Existing Peak

Velocities. The force mains are not classified in the figure. Many of the north-south pipes have

slower velocities as they typically have flatter slopes than the east-west pipes. Many of the

pipes that are at the top ends of the system and serve a small number of homes also have slow

peak velocities. In many cases this is due to the fact that the peak flows in these pipes are small

and the flow depths are not large enough to create greater velocities.

During the installation of the temporary flow meters for this master plan, J-U-B recorded high

levels of H2S (above 10 parts per million) near the intersection of 600 North 1000 West.

3.7.5 Lift Station Analysis

The capacity of the existing lift stations was evaluated by running the model with the calibrated

flows. The lift station data was obtained through Logan City and input into the model. No lift

station condition analysis was done at the time of this report.

3.8 EXISTING SYSTEM IMPROVEMENTS

Some key system improvement projects and actions were identified through the existing system

evaluation process. These projects are categorized as Condition Improvements or Capacity

Improvements.

3.8.1 Capacity Improvements

Some areas in the collection system do not currently have adequate capacity and require

capacity improvements. A capacity improvement may be a modification to an existing manhole

to split flows differently, the addition of a new pipe, or the replacement of an existing pipe with

a larger pipe.

The existing capacity deficient areas that require improvements are listed and identified in the

existing improvements figure (Figure 8). Future capacity deficient areas are identified at each of

the future time frames modeled (2020, 2025, Build Out) and are shown in later figures as

described in Chapter 4. A list of existing capacity improvements is given in Table 3-4 along with

the engineer’s opinion of probable cost for each improvement project.

The lineal foot costs listed for each new pipe project in Table 3-4 include the anticipated bid

items for a typical sewer main installation. Some additional items are listed for projects that are

really short or small to allow for adequate funding. For example, new pipes to be installed that

are less than 350 feet long include an additional item for new manholes at each end of the

project. The lineal foot price for new pipes that are longer than 350 feet includes manholes.

Really small projects include an additional small project cost.

Diagrams of each of the improvements are provided in Appendix I with more detailed

information about how to split flows. For projects that require a weir, the estimated height of



the weir is listed in the improvement diagrams. The weir heights were adjusted in the model

until the flow levels in the downstream pipes were acceptable. The flow levels in the model are

based off of the system data used to build the model such as pipe invert elevations, sizes, slopes

and manhole geometry. It is recommended that the system data for the manholes that need

weirs be verified prior to constructing the weirs.



Table 3-3: Existing System Capacity Improvements

EXISTING SYSTEM CAPACITY IMPROVEMENTS PROJECT DESCRIPTION PIPE SIZE UNIT QUANTITY AMOUNT COST

Install new gravity pipe in 100 N. from 400 E. to Canyon Road to send approximately half of the flows to the west at the intersection of 400 E. and 100 N.

8 LF 112 $ 183 $ 20,482 Manhole EA 2 $ 3,000 $ 6,000

Small Project Cost $ 10,000 $ 10,000 Engineering & Construction Contingency (40%) $ 14,593

PROJECT COST $ 51,074

Connect south pipe to north pipe in 200 S. near 540 E.

8 LF 20 $ 183 $ 3,657 Manhole EA 2 $ 3,000 $ 6,000

Small Project Cost $ 10,000 $ 10,000 Engineering & Construction Contingency (40%) $ 7,863


Install weir (dam) at 200 S./300 E. to force more flow from the north to the west.

Weir EA 1 $ 5,000 $ 5,000 Engineering & Construction Contingency (40%) $ 2,000


Install weir (dam) in the north pipe in 300 S. near 600 W. to direct more flow north in the east sewer main.

Weir EA 1 $ 5,000 $ 5,000 Engineering & Construction Contingency (40%) $ 2,000

PROJECT COST $ 7,000 Install new 15" gravity pipe in 300 S. from 300 E. to Main Street. Replace existing 8" and 10" pipe from 300 E. to 100 East. Add parallel pipe from 100 E. to Main Street.

18 LF 2,050 $ 226 $ 463,384 Weir EA 2 $ 5,000 $ 10,000

Engineering & Construction Contingency (40%) $ 185,354


Upsize pipe or install parallel 8" gravity pipe in 725 N. from 400 W. to Kings Ct.

8 LF 500 $ 183 $ 91,436 Engineering & Construction Contingency (40%) $ 36,574


Replace existing 10" pipe from 100 N/500 E to approx. 200 N/550 E with new 12" pipe.

12 LF 1,310 $ 192 $ 251,782 Engineering & Construction Contingency (40%) $ 100,713


Install new pumps at the Airport lift station

N/A EA 2 $ 5,000 $ 10,000 Engineering & Construction Contingency (40%) $ 4,000


Install new 8" sewer pipe from 900 W to 1000 W at approx. 1230 South (Providence LS)

8 LF 900 $ 183 $ 164,585 Engineering & Construction Contingency (40%) $ 65,834

PROJECT COST $ 230,419 TOTAL EXISTING IMPROVEMENTS COST $ 1,476,300



3.8.2 Condition Improvements

Some of the older system pipes are deteriorating, are in poor condition and are in need of repair

or replacement. City staff members met with J-U-B to identify the poor condition areas of the

system that are in the most need of repair.

The highest priority poor condition areas to improve are listed and shown in the existing

improvements figure (Figure 8). A list of existing condition improvements and associated

engineer’s opinion of probable cost is given in Table 3-4.

Table 3-4: Existing System Condition Improvements

EXISTING SYSTEM CONDITION IMPROVEMENTS PROJECT DESCRIPTION PIPE SIZE UNIT QUANTITY AMOUNT COST

Replace existing pipe in 400 N (Main Street to 700 E) and 700 E

(400 N to 600 N) as described in the 2006 - 400 North Sewer Feasibility

Study.

8 LF 6,300 $ 462 $ 2,912,704.91 Engineering & Construction Contingency (40%) $ 1,165,082

PROJECT COST $ 4,077,787

Replace existing pipe in Country Club Drive, Approx. 1768-1796 (SEMH02440 to SEMH02441)

8 LF 273 $ 183 $ 49,924.14 Engineering & Construction Contingency (40%) $ 19,970

PROJECT COST $ 69,894 Replace existing pipe in 1000 N,

Approx. 950 E-1200 E (SEMH00293 to SEMH00494, Possible liner

project)

8 LF 1,680 $ 183 $ 307,225.49 Engineering & Construction Contingency (40%) $ 122,890


Replace existing pipe in 200 S, Approx. Main St.-200 E

(SEMH01765 to SEMH01665, Possible liner project)

8 LF 671 $ 183 $ 122,707.32 15 LF 696 $ 202 $ 140,366.99

Engineering & Construction Contingency (40%) $ 49,083 PROJECT COST $ 312,157

Replace existing pipe in 500 N, Approx. 550 E-600 E (SEMH02059

to SEMH02060, Possible liner project)

8 LF 345 $ 183 $ 63,090.95 Engineering & Construction Contingency (40%) $ 25,236


Replace existing pipe in 600 E and 1150 N, Approx. 1150 N - 1200 N &

550 E - 600 E (SEMH01839 to SEMH00021). Rebuild SEMH00085

at 1150 N/500 E to divert more flow west.

8 LF 711 $ 183 $ 130,022.22 Manhole EA 1 $ 3,000 $ 3,000



TOTAL CONDITION IMPROVEMENT COSTS $ 5,163,300



The condition of the pipe in 400 North/700 East was evaluated in a 2006 feasibility study and

found to be poor. The feasibility study evaluated alternatives to repair or replace the pipe and

provided a recommended repair/replacement plan ( J-U-B Engineers Inc., 2006). The estimated

linear foot cost for trenching (replacement) the new line in the feasibility study was inflated by a

factor of 3% a year and inserted in Table 3-4 above. The 40% contingency was then added to

the construction cost as shown to provide a current estimated project cost.

3.8.3 Lift Station Improvements

The only existing lift station capacity issues were noted at the Airport lift station. There are

currently no pumps in this station, therefore, pumps should be installed as requested by City

staff.

3.8.4 Summary of Existing Improvements

The existing capacity and condition improvements should be completed as soon as possible.

There are no capacity improvements needed for the existing lift stations or their associated

force mains. The estimated opinion of probable cost for all of the existing improvements is

$6,639,000. A prioritized list of these improvements can be found in Section 6.

In addition to the recommended capital improvement projects (CIP) listed above, ongoing

maintenance should be considered as an option that could add capacity and improve pipe

conditions. Reducing I&I is one maintenance item that should be a priority to city staff,

especially in the Island area. I&I maintenance would reduce the flows through the collection

system and at the treatment plant. With the future sewer treatment method switching in the

coming years, this could reduce costs of treatment and save the City money.

One method to reduce I&I is to seal open pipe joints. According to City staff, much of the piping

in the Island area was installed with open joints. These joints can now be sealed and this could

be done by City staff during slow times of the year. Equipment would need to be purchased by

the City or otherwise be contracted out to private companies. Whichever method is used to

reduce I&I, additional funding should be set aside to provide for this improvement. If the

reduction of I&I is significant enough, some CIP’s could be delayed or removed.



4 MASTER PLAN & RELIEF ALTERNATIVES

4.1 INTRODUCTION

The master planning portion of the study involves applying future growth projections in the model to

identify the future collection system improvements needed as the City grows. This master plan

specifically evaluates the future time frames listed in Table 4-1.

Table 4-1: Future Time Frames Analyzed

Future Time Frames Analyzed

Title Description



Build Out Projected flows during the summer irrigation months at build out

Build out is defined as the condition when all of the areas in the future boundaries of the City develop to

the planned densities as identified in the Logan 2015 Water Master Plan Update. Based on a projected

2.5% growth rate provided by Logan and the planned densities, build out in the City will be reached

around year 2048. It is not known when the contributing cities will reach build-out. For the buildout

model, the flows from the contributing cities are based on the projected population for each city in year

2060 as projected by the Governor’s Office of Planning and Budget (GOPB).

The master plan models were utilized as tools for sizing future capacity improvements to the existing

system and sizing future trunk lines (lines that will be serve the undeveloped areas of the city as they

develop) and lift stations. The results of the master plan model identify conceptual alignments and

required pipe and pump sizes to accommodate future build out conditions.

4.2 KEY ASSUMPTIONS FOR FUTURE MODELS

The following is a list of key assumptions used for future projections:

• Logan City Growth Rate (2.5%) - The estimated future annual population growth rate for Logan

City is 2.5% as provided by City staff.

• Logan Growth Areas – J-U-B met with City staff to determine what areas may have more

potential to develop before other areas. The areas projected in the model to grow by years

2020, 2025 and build out are shown in Figure 9: Projected Growth. The build out boundary is



also shown and is based on the future projections used in the Logan 2015 Culinary Water

Master Plan as provided by the water master plan engineer Hansen Allen & Luce Inc.

• Logan Build Out ERU’s - The build out numbers of Equivalent Residential Units (ERU’s) for areas

to develop in Logan in the future are also taken from the projections used for the Logan 2015

Culinary Water Master Plan.

• Logan Build Out Year (2048) - The undeveloped areas in Logan will be built out around year

2048 based on the 2.5% growth rate.

• Growth Rates and Build Out of Contributing Communities - The projected growth rates for the

contributing communities vary decade to decade. Year 2060 populations were used for build

out because these communities may continue to grow after the 2048 Logan build out time

frame. A table that lists the projected populations for the contributing communities is given in

Appendix J (Utah Governor's Office of Planning and Budget, 2013).

• Average Sanitary Flow per Future ERU (0.17 GPM) - Each future ERU will contribute an average

sanitary flow of 0.17 GPM. This flow is based on an average flow from two areas on the east

side of the City. The northeast bench average flow is 0.13 GPM per ERU and the southeast

average flow is 0.2 GPM per ERU. This would equate to 70 gallons per person per day if 3.5

people for each ERU is assumed.

• Future Commercial and Industrial Daily Flow Volumes – All future flow volumes for areas to

develop in the future are based on the projected number of ERU’s used for the 2015 Culinary

Water Master Plan. The diurnal flow pattern used for the future flows correspond to the

planned land use.

• Peaking Factors - The sanitary flows in the model are all assigned to follow one of the five

diurnal flow patterns (Figure 3) based on the planned future land uses. Each diurnal pattern has

a slightly different peaking factor. (Graph 3-1)

• Infiltration Rate for Future Development Areas (0.12 gpm per acre) - Infiltration for areas that

will be developed in the future were added to the model at a rate of 0.12 gpm per acre and

assigned to the nearest existing or future system manhole. The future infiltration rate is

equivalent to the low infiltration rate used in the existing evaluation (Figure 4).

• Future Pipe Design Parameters - The future trunk lines included in the master plan are sized

based on the parameters listed in Table 4-2.



Table 4-2: Future Pipe Design Parameters

Future Pipe Design Parameters

D Diameter (inches)

d/D1 Maximum Allowed Depth / Diameter

d Maximum Allowed Flow Depth

(inches)

s Minimum

Pipe Slope2

8 0.5 4 0.40%

10 0.55 5.5 0.28%

12 0.6 7.2 0.21%

15 0.65 9.75 0.15%

18 0.75 13.5 0.12%

21 0.75 15.75 0.10%

24 0.75 18 0.10%

27 0.75 20.25 0.10%

30 0.75 22.5 0.10%

36 0.8 28.8 0.10%

42 0.85 35.7 0.10%

48 0.85 40.8 0.10%

60 0.85 51 0.10%

72 0.85 61.2 0.10% 1Standard of practice based on ASCE Man. of Reports on Engr. Practice #60 - Gravity Sanitary Sewer Design and Construction 210 State Standards minimum slope for 8" - 21" Pipe, 0.1% for constructability for pipes larger than 18"

• Future Lift Stations - Future lift stations will be built inside above-ground buildings.

• Ground Elevations - The ground elevations used to create the future system layout are based on

existing ground contours at 2 foot intervals provided by the Logan GIS department.

• Minimum Depth of Future Pipes (4 feet) – The minimum depth of the future pipes to serve new

areas is set at 4 feet. Some of the area south of 1700 South along the east side of the

Blacksmith Fork River is too low to allow for 4 foot bury depths without using pumps.

4.3 CREATION OF FUTURE MODELS

The future models were created based on the future assumptions and through an iterative process to

identify the most efficient way to provide sewer service to future development areas. The build out

model was created first to identify all of the pipes and lift stations that will be needed to serve the city

at build out. The build out model provided the sizes for any new pipes that will be installed to serve the

build out growth.



4.3.1 Future Lift Station Placement

A large portion of the undeveloped area is located on the western side of the City. The western

side is lower than other areas and will require some lift stations. The iterative process followed

to develop the build out collection system focused on minimizing the number of lift stations

needed to ultimately serve the City. It will take many years for the City to fully develop, and as

such there will be some smaller intermediate lift stations that will serve for a period of time until

the larger planned regional lift stations can be put into place. For example, the City is currently

phasing out some of its smaller lift stations and connecting the areas served by those lift

stations to the West Regional lift station.

4.3.2 Future Flow Generation

The future flows in the model are based on the assumptions for average flow per ERU listed in

Section 4.2. These flows were added to the model with a slightly different method then in the

existing model. Future flows were added based on the number of projected ERU’s multiplied by

the average sanitary flow per ERU in a given parcel or region. The peaking factors are based on

the diurnal curve assigned that matches the planned land use for each parcel. The flows were

added to the future conceptual manhole upstream of the nearest region served by the pipe.

Infiltration was added based on the service area upstream of each manhole.

4.4 2020 EVALUATION AND RESULTS

A model scenario was created to evaluate the capacity of the existing sewer system at year 2020 and

identify any needed future pipes or lift stations to serve the projected growth. The 2020 scenario was

built assuming that all of the capacity and condition improvements identified and listed in Chapter 3 for

the existing system will have been made. Future growth was added to the areas that were identified as

areas that may develop in the next five years (Figure 9). The 2020 scenario also includes future flows

from other contributing cities.

An overview of the d/D values in the existing system with projected 2020 flows is shown in Figure 10:

2020 Depth over Diameter. The island area continues to have some pipes that have high d/D values

along with a pipe in 1200 South between Legrand Street and Hwy. 89/91 that is full. The reserve

capacity available in each pipe segment for the same scenario is shown in Figure 11: 2020 Reserve

Capacity.

The areas with the capacity improvements that should be focused on between now and 2020 are

identified in Figure 12: 2020 Improvements. The capacity improvements are listed on the figure as well

as future pipes that are needed to serve the areas projected to develop. The future pipes are split into

two categories:



1. Future 8” by Development - These are future 8 inch pipes that will be installed by

developers as needed for new development. The full cost of these pipes will be paid for by

the developers.

2. Future Capacity Up Size - These are future pipes that a developer will be required to install

but are recommended to be larger than the 8 inches. These pipes will serve large areas that

will develop in the future. It is assumed that these will be installed by developers with

Logan paying for the cost differential associated with upsizing to diameters larger than 8

inches. These are listed with a description of “Capacity Up Size”.

The future lift stations and force main pipes needed in year 2020 are identified in Figure 12. The

capacity improvements that are needed between now and year 2020 include upgrades to the existing

system, future lift stations, and future trunk lines. The pipe in 1200 south is approaching full capacity,

Prior to 2020 the section of this pipe from Legrand Street to HWY 91/89 needs additional capacity. A

project to add a parallel 15-inch pipe is proposed to add the needed capacity for buildout.

The future lift stations and trunk lines will need to be installed in areas that currently have no collection

system as those areas develop. All of the future lift stations are needed to serve future growth only. It

is anticipated that they will be paid for by developers through impact fees. Future trunk lines that are

installed should be large enough to serve all of the future development in the City as outlined in this

master plan.

The conceptual opinion of probable costs for the 2020 capacity improvements to the existing system,

the future lift stations and the costs to upsize the future trunk lines needed for year 2020 are tabulated

in Table 4-3. The exact sizes for the pumps and force mains will be determined during design of the lift

stations. The exact time frame for the construction of these projects is not known and will be driven by

development.



Table 4-3: 2020 Capacity Improvements

YEAR 2020 SYSTEM CAPACITY IMPROVEMENTS

PRIORITY NO. PROJECT DESCRIPTION

PIPE SIZE UNIT QUANT.

UNIT AMOUNT COST

16 Add a parallel 15" main line in 1200 South from HWY 89/91 to Legrand Street.

15 LF 800 $ 202 $ 161,341

Weir EA 1 $ 5,000 $ 5,000

Eng. & Const. Contingency (40%) $ 66,537


Sub Total $ 232,900

YEAR 2020 LIFT STATIONS AS NEEDED FOR GROWTH

ID DESCRIPTION ITEM SIZE GPM HEAD QUANT. UNIT

AMOUNT COST

Future 1

New lift station at

3000 North/2300

West

Pumps 450 56 2 $ 300,000 $ 600,000

Force Main 6 1,700 $ 30 $ 51,000

Building & Land

$ 200,000 $ 200,000



Future 2

New lift station at

2200 North/2300

West

Pumps 1700 150 2 $ 350,000 $ 700,000

Force Main 12 12,500 $ 45 $ 562,500

Building & Land

$ 200,000 $ 200,000



Future 4

New lift station at

1900 South/2000

West

Pumps 350 20 2 $ 250,000 $ 500,000

Force Main 6 900 $ 30 $ 27,000

Building & Land

$ 200,000 $ 200,000



Sub Total $ 4,256,700

YEAR 2020 FUTURE MAIN LINE UPSIZE COST TO BE PAID BY CITY AS NEEDED FOR GROWTH

MODEL ID APPROX. LOCATION DESCRIPTION SIZE QUANT.

UNIT AMOUNT COST

FUTP57 East of TP Wetlands

Capacity Up Size

12 1,980 $ 15 $ 29,700


Capacity Up Size

12 780 $ 15 $ 11,700


Capacity Up Size

18 830 $ 40 $ 33,200


Capacity Up Size

18 350 $ 40 $ 14,000




Capacity Up Size

18 1,770 $ 40 $ 70,800


Capacity Up Size

12 1,170 $ 15 $ 17,550


Capacity Up Size

12 80 $ 15 $ 1,200


Capacity Up Size

18 200 $ 40 $ 8,000

FUTP173 1400 W (Between 400 S &

600 S) Capacity Up

Size 10 1,020 $ 10 $ 10,200

FUTP177 600 S (Between 1400 W &

2000 W) Capacity Up

Size 10 3,720 $ 10 $ 37,200

Sub Total $ 233,600

Total $ 4,723,200

4.5 2025 EVALUATION AND RESULTS

A 2025 model scenario was created to evaluate the capacity of the existing sewer system and identify

any needed new pipes or lift stations to serve the projected growth. This scenario was built assuming

that all of the improvements identified for the previous time frames will have been made. Future

growth was added (Figure 9) and includes future flows from other contributing cities.

An overview of the d/D values in the existing system with projected 2025 flows is shown in Figure 13:

2025 Depth over Diameter. The two existing trunk lines that connect to the West Regional lift station

have many pipe segments with d/D values greater than 1.0. This is because the existing pumps in the lift

station do not have adequate capacity to keep up with the projected flows coming to the lift station.

The pipes themselves have capacity to convey the flows to the lift station as indicated by the 2025

reserve capacity evaluation results. The reserve capacity available in each pipe segment for the same

scenario is shown in Figure 14: 2025 Reserve Capacity.

The trunk line in 1200 South from Providence between Legrand Street and the Providence flow meter

will need additional capacity. A project to add a parallel 15-inch pipe is proposed to add the needed

capacity for buildout.

The areas that will require additional capacity along with the identified pumping capacity improvement

to the West Regional Lift Station are listed in Figure 15: 2025 Improvements. The conceptual opinion of

probable cost for the West Regional Lift Station upgrades and for the new pipe in 1200 South are given

in Table 4-4.

The future pipes that need to be installed to serve areas that are projected to develop between year

2020 and 2025 are all 8 inch pipes. Because of this fact, Table 4-4 does not list any costs for these pipes

because it is assumed that they will be paid for and installed by developers. The future 8” pipes are

shown in Figure 15.



Table 4-4: 2025 Capacity Improvements

YEAR 2025 SYSTEM CAPACITY IMPROVEMENTS

PRIORITY NO.

MODEL ID PROJECT

DESCRIPTION GPM HEAD QUANT.

UNIT AMOUNT

*COST

17 W_REGIONAL_ PUMP1

Add 2 new pumps in pump slots #3 and #4. Install 1 pump that the City has on the shelf in slot #3, purchase and install one pump in slot #4 and purchase 2 additional pumps as backups.

730 30 3 $ 18,500 $ 55,500



PRIORITY NO.

PROJECT DESCRIPTION PIPE SIZE

UNIT QUANT. UNIT

AMOUNT COST

18

Add a parallel 15" main line in 1200 South from Legrand St. to

Providence meter that is located east of Hwy. 165.

15 LF 1,850 $ 202 $ 373,102

Casing LS 1 $ 76,000 $ 76,000



19 Replace existing 8" pipe with new

10" pipe crossing 2500 N to Airport

10 LF 116 $ 187 $ 21,735



Total $ 736,900 * - The costs for the upgrades to the West Regional Lift Station are based on the assumption that the station is already plumbed

and wired for the addition of two more pumps and that the pump control equipment is already in place, and one of those

pumps is in the City inventory. If pump controls are not currently in place for the 2 additional pumps, the estimated total cost

of the improvements to the lift station should be assumed to be $90,000. The exact time frame for the improvements will be

driven by development.



4.6 BUILDOUT EVALUATION AND RESULTS

A model scenario was created to evaluate the capacity of the existing sewer system and identify any

needed new pipes or lift stations to serve the City under build out conditions as defined in Section 4.1.

This scenario was created assuming that all of the improvements identified for the previous time frames

will have already been made.

An overview of the d/D values in the existing system with the projected build out flows is shown in

Figure 16: Build Out Depth over Diameter. The island area continues to have pipes that are near or

exceeding capacity. The trunk lines that serve North Logan and Smithfield/Hyde Park are approaching

their capacity limits and a short pipe that crosses Highway 91 near 1100 South. The reserve capacity

available in each pipe segment is shown in Figure 17: Build Out Reserve Capacity.

Many pipe segments along the existing trunk line that comes from North Logan is over capacity at the

build out time frame in the model. Future alternatives to add capacity to this trunk line were evaluated

in the Northwest Regional Wastewater Study (Sunrise Engineering, Inc., 2012). The alternative selected

as a result of the study requires a new trunk line to be shared by Logan and North Logan. The new trunk

line will include some 36-inch, 42-inch and 48-inch diameter piping as described in the study. Based on

the study, Logan’s cost share is 14% for the 36” pipe, 27% for the 42” pipe and 53% for the 48” pipe.

The trunk line that comes from Smithfield/Hyde Park is at capacity at build out in the model. This trunk

line may or may not reach its capacity limits depending on development densities and I&I flow in the

future. This line should be monitored in future years (Appendix H).

The capacity improvements that are needed between year 2025 and build out include two upgrades to

the existing system, two future lift stations and future trunk lines. The areas that will need to be

monitored and the capacity improvements for build out are shown in Figure 18: Build Out

Improvements. The new pipe for Project #9 will divert some flows from the pipe that crosses Highway

91 at 100 West to Legrand Street to the south. Two future lift stations and multiple trunk lines will need

to be installed in areas that currently have no collection system as those areas develop.

The conceptual opinion of probable costs for the buildout capacity improvements to the existing system,

the two future lift stations and the cost to upsize the additional future trunk lines are listed in Table 4-5.

The exact sizes for the pumps and force mains will be determined during design of the lift stations. The

exact time frame for the construction of these projects will be driven by development.



Table 4-5: Build Out Capacity Improvements

BUILD OUT SYSTEM CAPACITY IMPROVEMENTS

PRIORITY NO.

PROJECT DESCRIPTION PIPE SIZE

UNIT QUANT. UNIT

AMOUNT COST

20 New 8" Main Line in 100 West from

US 89-91 to Legrand Street

8 LF 650 $ 183 $ 118,867



21 New trunk line

from North Logan

LOGAN SHARE

14% 36 LF 2,700 $ 393 $ 148,674

27% 42 LF 4,750 $ 380 $ 487,350

53% 48 LF 4,700 $ 400 $ 996,400


PROJECT COST (Logan's Share) $ 2,285,393

Sub Total $ 2,451,800

BUILD OUT LIFT STATIONS AS NEEDED FOR GROWTH

ID DESCRIPTION ITEM SIZE GPM HEAD QUANT. UNIT

AMOUNT COST

Future 3

New lift station at 250

South/1900 West

Pumps 80 30 2 $ 300,000 $ 600,000

Force Main 6 6,230 $ 30 $ 186,900

Building & Land

$ 200,000 $ 200,000



Future 5

New lift station at 600

North/1900 West

Pumps 200 25 2 $ 350,000 $ 700,000

Force Main 6 320 $ 30 $ 9,600

Building & Land

$ 200,000 $ 200,000



Sub Total $ 2,655,000

BUILD OUT FUTURE MAIN LINE UP SIZE COST TO BE PAID BY CITY AS NEEDED FOR GROWTH

MODEL ID APPROX. LOCATION DESCRIPTION SIZE QUANT. UNIT

AMOUNT COST

FUTP151 East of TP Wetlands Capacity Up

Size 18 2,370 $ 45 $ 106,650

FUTP181 East of 2000 W/South of 600 S Capacity Up

Size 10 1,470 $ 8 $ 11,760

FUTP100 East of 2000 W/South of 600 S Capacity Up

Size 10 2,320 $ 8 $ 18,560



FUTP03868 Btwn 1000 & 1200 W, North

of 1800 N Capacity Up

Size 24 1,380 $ 100 $ 138,000



Size 24 1,090 $ 100 $ 109,000



Size 24

1,090 $ 100 $ 109,000



Size 24 1,360 $ 100 $ 136,000

Sub Total $ 629,000

Total $ 5,736,000



5 PRIORITIZED CAPITAL IMPROVEMENT PROJECTS (CIP)

Table 5-1 below lists the needed CIP’s identified within the existing collection system in order of priority.

These should be completed in the order they are listed and as funding becomes available.

Table 5-1: Existing System CIP Summary

EXISTING SYSTEM CAPITAL IMPROVEMENT PROJECTS SUMMARY

PRIORITY NO.

PROJECT DESCRIPTION PROJECT

TYPE RECOMMENDED

TIMEFRAME PROJECT COST1

1

Install new 15" gravity pipe in 300 S. from 300 E. to Main Street. Replace existing 8" and 10" pipe from 300 E. to 100 East. Add parallel pipe from 100 E. to Main Street.

Capacity Existing $ 658,700

2

Replace existing pipe in 400 N (Main Street to 700 E) and 700 E (400 N to 600 N) as described in the 2006 - 400 North Sewer Feasibility Study.

Condition Existing $ 4,077,800

3 Replace existing pipe in Country Club Drive, Approx. 1768-1796 (SEMH02440 to SEMH02441)

Condition Existing $ 69,900

4 Replace existing pipe in 1000 N, Approx. 950 E-1200 E (SEMH00293 to SEMH00494, Possible liner project)


5

Install new gravity pipe in 100 N. from 400 E. to Canyon Road to send approximately half of the flows to the west at the intersection of 400 E. and 100 N.


6 Install new 8" sewer pipe from 900 W to 1000 W at approx. 1230 South (Providence LS)


7 Connect south pipe to north pipe in 200 S. near 540 E.


8 Install new pumps at the Airport lift station Capacity Existing $ 14,000

9

Replace existing pipe in 600 E and 1150 N, Approx. 1150 N - 1200 N & 550 E - 600 E (SEMH01839 to SEMH00021). Rebuild SEMH00085 at 1150 N/500 E to divert more flow west.


10 Replace existing pipe in 200 S, Approx. Main St.-200 E (SEMH01765 to SEMH01665, Possible liner project)




PRIORITY NO.

PROJECT DESCRIPTION PROJECT

TYPE RECOMMENDED

TIMEFRAME PROJECT COST1

11 Replace existing pipe in 500 N, Approx. 550 E-600 E (SEMH02059 to SEMH02060, Possible liner project)


12 Install weir (dam) at 200 S./300 E. to force more flow from north to west.


13 Install weir (dam) in the north pipe in 300 S. near 600 W. to direct more flow north in the east sewer main.


14 Replace existing 10" pipe from 100 N/500 E to approx. 200 N/550 E with new 12" pipe.


15 Upsize pipe or install parallel 8" gravity pipe in 725 N. from 400 W. to Kings Ct.


Existing Timeframe Subtotal $ 6,639,500

16 Add a parallel 15" main line in 1200 South from HWY 89/91 to Legrand Street.

Capacity 2020 $ 232,900

2020 Timeframe Subtotal $ 232,900

17

Add 2 new pumps in pump slots #3 and #4. Install 1 pump that the City has on the shelf in slot #3, purchase and install one pump in slot #4 and purchase 2 additional pumps as backups.

Capacity 2025 $ 77,700

18 Add a parallel 15" main line in 1200 South from Legrand St. to Providence meter that is located east of Hwy. 165.

Capacity 2025 $ 628,700

19 Replace existing 8" pipe with new 10" pipe crossing 2500 N to Airport

Capacity 2025 $ 30,400

2025 Timeframe Subtotal $ 736,800

20 New 8" Main Line in 100 West from US 89-91 to Legrand Street

Capacity Build Out $ 166,400

21 New trunk line from North Logan Capacity Build Out $ 2,285,400

Buildout Timeframe Subtotal $ 2,451,800

Total $ 10,061,000

1 – This project cost includes 40% engineering and construction contingency

Table 5-2 below lists the needed CIP to serve areas that are currently undeveloped. These should be

completed as growth dictates.



Table 5-2: Future System CIP Summary

FUTURE SYSTEM CAPITAL IMPROVEMENT PROJECTS SUMMARY

ID PROJECT DESCRIPTION PROJECT

TYPE PROJECTED TIMEFRAME

PROJECT COST1

Future 1 New lift station at 3000 North/2300 West

Growth 2020 $ 1,191,400

Future 2 New lift station at 2200 North/2300 West

Growth 2020 $ 2,047,500

Future 4 New lift station at 1900 South/2000 West

Growth 2020 $ 1,017,800

FUTP57 Capacity Up Size Growth 2020 $ 29,700










Future 3 New lift station at 250 South/1900 West Growth Build Out $ 1,381,700

Future 5 New lift station at 600 North/1900 West Growth Build Out $ 1,273,400

FUTP151 Capacity Up Size Growth Build Out $ 106,700







Total $ 7,774,500 1 – This project cost includes 40% engineering and construction contingency



6 CONCLUSIONS AND RECOMMENDATIONS

The following conclusions and recommendations are given based on the foregoing evaluation.

Existing System Geometry - There are some pipe invert elevations and other system geometry data that

still need to be updated.

• Update the City GIS data to include some new manhole inverts that were added as noted in the

model.

• In the future, the GIS data will always be the parent data and the model will be updated based

on the latest GIS data.

• Continue to identify and update corrections for the existing system GIS files and then update the

model.

System Infiltration - The total approximate base flow recorded at the treatment lagoons during winter

months is approximately 3,750 gallons per minute (GPM) based on the flows recorded during the very

early morning hours of winter days. The base flow during the summer is approximately 7,750 GPM. It is

probable that a large portion of the base flow comes from groundwater infiltration with some flow

being sanitary flow produced mainly by industrial users that operate during early morning hours. A very

large portion of the infiltration comes from the island area. With the construction of a new treatment

plant and the change in treatment methods, the costs of treatment of sewer flows per gallon is

increased. Any reduction in infiltration will result in treatment savings

• Implement more flow monitoring in the island area during the summer months to identify more

specific sources of infiltration. This will lead to more effective efforts to reduce the infiltration.

• Implement infiltration reduction methods, such as sealing open pipe joints. An ongoing

infiltration reduction fund should be created in the budget as a way to implement this

maintenance program. This program will result in sewer treatment savings if I&I is successfully

reduced.

• Focus infiltration reduction efforts first in the Island area which has been identified as the area

with the highest infiltration rates in the City. Many of the pipes in this area were installed with

open joints that can be sealed off.

• Monitor ground water levels to understand how and if the ground water changes as a result of

the pipe joint sealing efforts.

City staff could seal pipe joints during winter months when the crews are not as busy if some sealing

equipment is purchased. This work could alternatively be contracted out.System Inflow - Small

amounts of inflow were observed as a result of some small rain events recorded while gathering flow

data for this master plan. Infiltration is a much larger flow contributor to the system then inflow from

small rain events.



• Collect flow data during large rain events for an accurate evaluation of the impacts of inflow on

the system.

Existing Pipes Near Capacity - Some existing pipes appear to be approaching capacity in the model (See

Figures 5 and 6).

• As development occurs, the existing d/D and reserve capacity figures should be referenced to

determine where areas of concern may be. The model should also be updated to reflect new

flow conditions as new routing or new development happens.



Existing Poor Condition Areas - Some pipes in the existing system are known to be problem areas or

pipes that are deteriorated (See Figure 8). These pipes are listed in the report in Table 3-4 with the

estimated replacement costs.

• The condition of the existing pipe located in 400 North from 700 East to Main Street is of

particular concern and should be repaired/replaced as soon as possible.

Existing Over Capacity Areas – Some small isolated pipes in the existing system are over capacity at

peak flow times (See Figure 8).

• Design and build the improvements listed in Table 3-3 of the report to add additional capacity as

soon as is feasible.

Existing Lift Stations – New pumps will be needed at the existing lift station at the airport in the next

few years. Improvements are currently being made to the Providence lift station by city staff. New

pumps will need to be added to the West Regional Lift Station in the year 2025.

• Install two pumps at the Airport lift station. Continue to monitor the existing lift stations and

upgrade as needed. Plan to add two new pumps to the West Regional Lift Station in the year

2025.

Future Over Capacity Areas - There are some areas in the existing system that will exceed capacity in

the future based on the assumed growth projections.

• Begin plans to build the 2020 improvements as listed in Table 4-3 of the report.

Future Trunk Lines and Lift Station Upgrades - Many new trunk lines and lift stations will be needed to

serve the areas that will develop in the city in the future.

• Require stringent requirements for new developments and enforce installation of tight sewer

systems to minimize new sources of I&I.

• Size future pipes and lift stations based on the conceptual future system plan prepared for this

report (See Figure 19).

• Plan for future regional lift stations in the approximate locations indicated. This will require

extra coordination with developers during planning and development, but will greatly reduce

future operation and maintenance costs. By having fewer regional lift stations instead of many

smaller lift stations the City will have much less equipment to operate and maintain.



Future Areas Near Capacity – Some additional pipes appear to be approaching capacity in the model at

the Build Out time frame (See table in Appendix H).

• Continue to maintain and update the model in order to manage future capacity issues.

Computer Model - The computer model is very detailed and can be used to identify impacts from new

developments.

• Utilize the existing model to determine impacts from proposed new developments or areas that

plan to re-develop to higher densities.

• Update the existing model regularly by importing updated system information from the GIS

databases that are maintained by the Logan GIS department as defined in Appendix K.

• Require an update to the existing sewer model to verify that there is adequate capacity prior to

permitting new developments.

• Update the overall master plan projections every 5 to 10 years.



7 REFERENCES

J-U-B Engineers Inc. (2006). 400 North Sewer Feasibility Report. Logan.

Environmental Protection Agency. (1991). Sewer System Infrastructure Analysis and Rehabilitation.

Cincinnati, OH: United States Environmental Protection Agency, Office of Research and

Developement.

EPA. (1974). Process Design Manual for Sulfide Control in Sanitary Sewerage Systems.

EPA. (2014). Guide For Estimating Infiltration and Inflow. Water Infrastructure Outreach. Retrieved from

EPA.

Sunrise Engineering, Inc. (2012). Northwest Regional Wastewater Study.

United States Census Bureau. (n.d.). Population Estimates. Retrieved from

https://www.google.com/?gws_rd=ssl#q=Logan+City+population+1990

Utah Governor's Office of Planning and Budget. (2013). Governors Office of Management and Budget.

Retrieved from http://gomb.utah.gov/wp-content/uploads/sites/7/2013/08/Subcounty-Pop-

Projections-2013.xlsx

Documents

2018 Sewer Collection Master Plan Update Collection...Prepared By: J-U-B ENGINEERS, Inc. 1047 South 100 West, Suite 180 Logan, UT 84321 Prepared For: Logan City Corporation. 255 N