Provo City. Wastewater Collection System 2010 Master Plan. water Systems. Project No Prepared by:

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1 Provo City water Systems Wastewater Collection System 2010 Master Plan Project No Prepared by:, 2011

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3 TABLE OF CONTENTS Page No. Chapter 1 Purpose, Scope, and Authorization Introduction Scope of Services Authorization Impact Fee Facilities Plan Certification Project Staff Chapter 2 Existing System Description Service Area Collection System Lift Stations Diversions and Interceptors Treatment Plant Chapter 3 Flow Monitoring Flow Monitoring Observations Chapter 4 Projected Wastewater System Growth Estimating Existing Sewer Flows Domestic Flow Infiltration Inflow Projection of Future Sewer Flows Population Projections Future Sewer Flow Estimates WWTP Capacity Chapter 5 Hydraulic Modeling InfoSewer Geometric Model Development Modeled Pipelines Modeled Lift Stations Flow Model Development Chapter 6 System Evaluation Evaluation Criteria Existing System Analysis Future System Analysis Downtown Deficiencies Southeast Deficiencies Westside Gravity and Lift Deficiencies Additional System Capacity Issues BOWEN,COLLINS &ASSOCIATES i PROVO CITY

4 TABLE OF CONTENTS (continued) Page No. Chapter 7 System Improvements Eastside Improvements Westside Improvements Lift Station Improvements Estimated Cost of Improvements Chapter 8 System Renewal System Renewal Condition Assessment Concrete Pipe Assessment and Rehabilitation System Renewal Budget System Renewal Priorities Chapter 9 Conclusions and Recommendations Summary of Recommendations Chapter 10 Impact Fee Facilities Plan APPENDIX A SEWER INFORMATION BOWEN,COLLINS &ASSOCIATES ii PROVO CITY

5 TABLE OF CONTENTS (continued) TABLES No. Title Page No. 2-1 Estimated Pipe Length by Diameter in Existing Public Lift Stations Provo City Diversions and Interceptors Summary of Flow Monitoring Results for Provo City Trunk Lines Summary of ADS Flow Monitoring Results November 10-16, Summary of Westside Flow Monitoring Results October 15-29, Observed Average Flows at Site W1 (November 2000 ADS Site 3) Observed Average Flows at Site W7 (November 2000 ADS Site 13) Average Daily Domestic Flow Per Acre Based on Land Use Provo Water Service Area Projected Residential Population Projected Provo City Sewer Flows (MGD) Remaining Capacity in Westside Major System Components (As of October 2008 Flow Monitoring) Hydraulic Deficiencies with Added Flow from Provo Canyon Allowable Development Following Completion of Phase (Units) Build-out Lift Station Flow Rates Build-out Lift Station Wet Well Volumes with Recommended Improvements System Improvement Costs Costs Associated with Improvement Phases Required System Renewal Budgets for Various Rehabilitation/Replacement Scenarios Approximate Age of Collection System Pipes Year Capital Improvements Budgeting Schedule Impact Fee Facilities Plan Costs Required for Future Growth BOWEN,COLLINS &ASSOCIATES iii PROVO CITY

6 TABLE OF CONTENTS (continued) FIGURES No. Title Page No. 2-1 Existing Sewer System Service Area and Trunk Line Collection Areas Existing Wastewater Collection Facilities Flow Monitoring Locations Estimated Infiltration Rates at Flow Monitoring Locations General Plan Normalized Wastewater Production Hydrographs at Select Monitoring Locations (Infiltration Removed Based on Absolute Minimum Flow) Provo City Water Reclamation Plant Average Minimum Flow ( ) Provo City Water Reclamation Plant Average Monthly Flow ( ) Historic WWTP Flow Rates Minimum Annual Flow at Provo Wastewater Treatment Plant vs. Annual Precipitation Relationship Between Precipitation Depth and Wastewater Collection System Inflow General Plan Changes Adopted Provo City Projected Population Projected Total Sewer Flows Sewer System Modeling Sub-Areas Sewer System Model Existing Pipe Condition Sewer System Model Buildout Pipe Conditions Skipper Bay Lift Station Flow Westside Lift Station Flow Orem Lift Station Overflow Impacts Eastside System Improvements Westside System Improvements Year Design Life Pipe Replacement Costs Sewer System Costs and Revenues (15-year Implementation) BOWEN,COLLINS &ASSOCIATES iv PROVO CITY

7 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN CHAPTER 1 PURPOSE, SCOPE, AND AUTHORIZATION INTRODUCTION Bowen, Collins & Associates (BC&A) prepared a Wastewater Collection System Master Plan for Provo City in A partial update to that master plan for the City s west side was prepared in 2008 to reflect changes made in development patterns on the west side. Since that time, Provo City revised its General Plan. The primary purpose of this Wastewater Collection System Master Plan is to provide recommended improvements to resolve existing and projected future deficiencies in the Provo City wastewater collection system based on the recently adopted General Plan. As part of this process, this report will also include an Impact Fee Facilities Plan in accordance with the new requirements of State law. This document is a working document. Some of the recommended improvements identified in this report are based on the assumption that development and/or potential annexation will occur in a certain manner. If future growth or development patterns change significantly from those assumed and documented in this report, the recommendations may need to be revised. The status of development should be reviewed at least every five years. This report and the associated recommendations should also be updated every five years as well. SCOPE OF SERVICES The general scope of this project involved a thorough analysis of Provo City s sewer system and its ability to meet the present and future wastewater needs of its residents. As part of this project, BC&A completed the following tasks: Task 1: Task 2: Task 3: Task 4: Task 5: Task 6: Updated existing and future sewer service requirements based on Provo City growth, changes to its General Plan and projected growth patterns. Used a calibrated hydraulic sewer model to simulate operation of existing facilities under current development conditions. Used the hydraulic sewer model to simulate operation of facilities with recommended improvements under changes to projected future build-out conditions to identify the impacts of future development on sewer facilities. Used the hydraulic sewer model to simulate potential growth in Provo Canyon and to consider the capacity of the City s existing collection system to convey sewer flow from this area. Used the hydraulic sewer model to evaluate alternative improvements that would resolve the system deficiencies identified in Tasks 2, 3, and 4. Developed an impact fee facilities improvement plan for City budgeting and planning purposes. BOWEN,COLLINS &ASSOCIATES 1-1 PROVO CITY

8 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN Task 7: Prepared a master plan report to document the analytical procedures used in completing the study and summarize the conclusions reached. Task 8: Conducted progress and coordination meetings as required to keep City staff involved and informed of progress and activities. AUTHORIZATION Provo City contracted the services of BC&A to prepare this Wastewater Collection System Master Plan in November of The master plan study and associated report were completed March IMPACT FEE FACILITIES PLAN CERTIFICATION The analysis contained in this report has been prepared based on growth and system information provided by Provo City. Based on the data and growth assumptions provided and assuming Provo City follows the improvement plan outlined in this report, BC&A certifies that, to the best of our knowledge and in accordance with Section 11-36a-306, this impact fee facilities plan: 1. Includes only the costs for qualifying public facilities that are: a. allowed under the Impact Fees Act; and b. actually incurred; or c. projected to be incurred or encumbered within six years after the day on which each impact fee is paid; 2. does not include: a. costs for operation or maintenance of public facilities; b. costs for qualifying public facilities that will raise the level of service for the facilities through impact fees, above the level of service that is supported by existing residents; c. an expense for overhead, unless the expense is calculated pursuant to a methodology that is consistent with generally accepted cost accounting practices and the methodological standards set forth by the federal Office of Management and Budget for federal grant reimbursement; and 3. complies in each and every other relevant respect with the Impact Fees Act. PROJECT STAFF The project work was performed by the BC&A team members listed below. Team member s roles on the project are also listed. The project was completed in BC&A s Draper, Utah office. Questions may be addressed to Keith Larson, Project Manager at (801) Michael Collins Keith Larson Andrew McKinnon Angela Hansen Principal-In-Charge Project Manager Project Engineer, Sewer Modeling Word Processing BOWEN,COLLINS &ASSOCIATES 1-2 PROVO CITY

9 The projected service area for Provo City collection system is shown in Figure 2-1. Included in the service area are all areas recently annexed into Provo City or areas expected to be annexed. The sewer service area consists of a mix of residential, commercial, and industrial customers. Provo City s collection system is divided into six major collection areas as seen in Figure 2-1: Freedom, Eastside, Southeast, Industrial, Westside-Gravity, and Westside-Lifted. The majority of the sewer collection pipelines in the City discharge into the Westside and Freedom trunk lines. Future Provo Canyon development (not shown in Figure 2-1 because it is not currently served by the collection system) will also flow into the Freedom trunk line. Discharge from these two trunk lines combine just before entering the wastewater treatment plant from the west. The Freedom trunk collects wastewater for almost all of north Provo and much of central Provo. Of the area served by the Westside trunk line, most of the development east of I-15 gravity flows to the Westside trunk line. Conversely, most of the area west of I-15 needs to be lifted or pumped into the Westside trunk line from sewer mains that branch off of the Westside Trunk. The Harbor Park and Skipper Bay Lift Stations both lift wastewater from the northwest area of the City to the Westside Lift Station where it is again lifted into the Westside trunk line to gravity flow to the Wastewater Treatment Plant (WWTP). The Eastside trunk line is a 27-inch diameter pipe at the point where it discharges to the treatment plant. This pipeline collects wastewater from Provo s east benches. It also conveys most of BYU s wastewater flows to the WWTP. The remaining two trunks serve the small section of Provo south of the WWTP. The Southeast trunk is a 21-inch main as it enters the WWTP from the east. It collects wastewater from the southeast area of Provo. The Industrial trunk is a 12-inch line as it enters the WWTP from the south. It serves the largely industrial area of Provo immediately south of the WWTP. Discharging into these five main trunk lines is a vast network of smaller branch sewers and sewer laterals. The system currently consists of approximately 1.6 million feet (294 miles) of sewer pipe, not including service laterals. Figure 2-2 shows the location and size of pipes in the Provo City sewer system. The estimated total length of pipe, excluding service laterals, is summarized by diameter in Table

10 I-15 Legend Trunklines Eastside Trunk Freedom Trunk Industrial Trunk Southeast Trunk Westside Trunk Harbor Park Branch Skipper Bay Branch ³ Westside Branch Canyon Road Trunk Area Eastside Trunk Freedom Trunk Industrial Trunk Southeast Trunk Westside Trunk - Gravity Westside Trunk - Lifted 3700 North North Temple Dr. State Street BYU Campus Center Street 600 South 1600 West 500 North University Avenue 1100 West 900 East Figure Existing Sewer System Service Area and Trunk Line Collection Areas Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

11 Legend A Diversions Existing Sewer Main 6-inch 8-inch 10-inch 12-inch 15-inch 18-inch 21-inch 24-inch 27-inch 30-inch 36-inch 42-inch Private Lift Station Public Lift Station!( Small Service Pump Force Mains ³ 3700 North River Bottoms Canyon Road State Park South State Park North!( Lakeview Storage Lakeview RV Park Control Tower!(!( A A Center Street 600 South Galland Skipper Bay Airport I-15 Harbor Park Westside Grandview 1600 West A 500 North Independence 1100 West State Street A Carterville (Orem Owned) A A University Avenue Lakewood Marriott Smith-Megadiamond Raintree Apartments East Bay #1 BYU Campus East Bay #2 900 East Plant Lift Station Golf Course Golf Course!( North Temple Dr. East Bay #3 Billings Ironton Figure Existing Wastewater Collection Facilities Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan File: P:\Provo City\2010 Sewer Financial Options Evaluation\GIS\Mxd\Fig2-2-ExFacilities.mxd

12 4 9, , , , , , , , , , , , There are 21 sewer lift stations in the Provo City sewer system as shown in Figure 2-2. Most of these lift stations are small, serving only a few homes or businesses. Thirteen of these lift stations are owned and operated by Provo City. Table 2-2 lists each of the Provo owned lift stations along with their characteristics. The largest lift station, Westside Lift Station, collects wastewater from the Harbor Park, Skipper Bay, Airport, and State Park lift stations and discharges into the 36-inch main on 1600 West. 2-4

13 500 North 800 West West 50% to South 1390 North 2770 West South West 500 North Freedom Blvd (200 West) West South 800 North 600 West West South Center Street 2650 West West South Columbia Lane Riverside Drive Southwest Southeast Westside 2450 W. 560 S (2000) 6, ,000 Harbor Park 2475 W. 350 N (2005) 6, ,100 Skipper Bay 2995 W. Boat Harbor Dr , ,100 Ironton 2900 S. Mountain Vista Pkwy , East Bay I 1600 S. 180 E N/A 500 East Bay II 1325 S. 290 E , East Bay III 2000 S. Kuhni Rd , Lakewood 470 W. Lakewood Dr (Planned) Airport 3110 W. 890 S ,622 N/A 400 Billings 2040 E. Ironton Blvd , Plant 1500 S. 350 E , State Park 4200 W. 120 S ,014 N/A 230 South Grandview 2100 W N N/A Includes power for both Plant Lift Station and Headworks Bldg. Provo City has constructed several diversions and interceptors in its collection system to optimize the flow capacity in its existing system. The purpose of these diversions or interceptors has been to reduce flow to the west side of Provo City where there is the most potential for growth while utilizing available capacity in sewer trunks to the east. These diversions are shown in Figure 2-2 and listed in Table 2-3 to identify the historic direction of flow compared to the current direction of flow. 2-5

14 All of the City s wastewater is treated at the WWTP located at 1685 South East Bay Boulevard (see Figure 2-2). The plant was placed into operation in 1956 and was expanded in The plant has a maximum-month average day capacity of 21 mgd and a peak hour capacity of 42 mgd. 2-6

15 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN CHAPTER 3 FLOW MONITORING Bowen, Collins & Associates contracted with ADS Environmental Services (ADS) in November 2000 and JUB Engineering (JUB) in October 2008 to perform temporary flow monitoring at select locations throughout the Provo City sewer system. Flow monitoring was performed to accomplish three major goals: 1. Provide general system flow data to be used for model calibration; 2. Provide data to develop input hydrographs and estimate average sewage production for different types of land use; and 3. Provide data for cursory infiltration analysis. Temporary flow monitors were installed by ADS in 26 manholes in 2000 to continuously monitor sewer discharges over a seven-day period. Twelve additional temporary flow monitors were required in 2008 to obtain calibration data for Provo s Westside not included in the ADS flow monitoring. The locations of the flow monitors are shown in Figure flow monitoring is distinguished with a w prefix to indicate it was part of the Westside flow monitoring set. The selection of the flow monitoring locations was guided by the goals listed above. The majority of the monitors were placed on large mains to capture general flow patterns throughout the system. The flow monitoring data was then used in the calibration of a hydraulic computer model of the sewer system. The remaining monitors were placed on small lines serving small areas with relatively uniform land use (i.e. low density residential, high density residential, commercial, etc.). By isolating different types of land use, the results from these monitors were used to estimate sewer production patterns for each type of land use. This is discussed in detail in Chapter 4. The ADS flow monitors were installed on November 9, 2000 and flows were monitored from November 10, 2000 through November 16, The Westside flow monitors were installed between October 15, 2008 and October 29, No storms occurred during either collection period so that all monitored flow can be assumed to be groundwater infiltration or domestic flow. ADS flow monitoring was conducted at 15-minute time intervals, while the Westside flow monitoring was monitored at 6-minute time intervals. The 6-minute interval was used because of the many lift stations on Provo s west side. In order to capture the pumping cycles properly, these shorter intervals were necessary. Values of velocity, water depth, and instantaneous flow were recorded to accomplish the goals discussed above. Flow monitoring was conducted during the fall for two reasons. First, domestic sewer flow production patterns can be more closely observed when sewer flow monitoring is performed during the period of lowest infiltration. In the fall, groundwater levels are generally low and infiltration is at its lowest annual level. A second reason for choosing this time period was to try to avoid inflow from precipitation. If monitoring can occur during a dry period, inflow can be neglected. For the ADS monitoring, there was some snow fall, but temperatures prevented this precipitation from melting. Inflow was therefore considered to be negligible. BOWEN, COLLINS & ASSOCIATES 3-1 PROVO CITY

16 Legend A A ADS Flow Monitoring Westside Flow Monitoring Private Lift Station Public Lift Station!( Small Service Pump ³ 3700 North Existing Sewer Main 6-inch 8-inch 10-inch 12-inch 15-inch 18-inch 21-inch 24-inch 27-inch 30-inch 26 A A 25 North Temple D 36-inch 42-inch I-15 State Street 22 A 23 A A BYU Campus 21 A A 20 A 18 A 3110 West w12 A w11 A A 600 South A w10 A w8 w6 A Center Street w9 A w5 A AA A 1600 West A 7 w w7 w3 500 North 12 A 8 A A 15 A 16 University Avenue 9 A 11 A A East A 17 6 A 5 A 4 A 1100 West A w2 A w1 1 2 A A A 3 Figure Flow Monitoring Locations Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan 0 2,000 4,000 Feet!(

17 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN During the seven-day ADS flow-monitoring period, values of velocity, water depth, and instantaneous flow were recorded at 15-minute intervals for each location. Table 3-1 summarizes the system-wide results of the flow monitoring for major trunk lines in the system (see Figure 3-1). Table 3-1 Summary of Flow Monitoring Results for Provo City Trunk Lines (ADS 2000) Maximum Observed Instantaneous Flow (mgd) Minimum Observed Instantaneous Flow (mgd) Average Observed Flow (mgd) % Service Area % Plant Trunk Line Flow 1 Eastside Southeast Westside Freedom Industrial 2 NA NA Total (as measured at the WWTP) Based on average observed flow during the flow monitoring period 2 Flows were not monitored on the Industrial Trunk Line. Average flow in this trunk line was calculated as the difference between the average flows measured at the plant and the sum of average flows in the other four trunk lines. BOWEN, COLLINS & ASSOCIATES 3-3 PROVO CITY

18 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN The results for the 26 ADS flow-monitoring locations are summarized in Table 3-2. Table 3-2 Summary of ADS Flow Monitoring Results November 10-16, 2000 Location Max Flow (mgd) Max Velocity (ft/s) Diameter (in) Max d/d Ave d/d Min d/d d Depth in pipe D Diameter of pipe BOWEN, COLLINS & ASSOCIATES 3-4 PROVO CITY

19 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN Table 3-3 summarizes the results of the Westside flow monitoring. Table 3-3 Summary of Westside Flow Monitoring Results October 15-29, 2008 Max Flow (mgd) Max Velocity (ft/s) Location Diameter (in) Max d/d Ave d/d Min d/d W W W W W W W W W W W W Westside* 5.22 * Westside Lift Station flows are the sum of stations 5, 6, and 9. d Depth in pipe D Diameter of pipe Sites W1, W4, and W7 overlap with the ADS flow monitoring sites 3, 7, and 13. These sites were flow monitored again in 2008 for the following reasons: Sites W1 & W7 These sites were flow monitored for hydraulic model calibration purposes, but also serve to identify the effectiveness of diversions along 500 North at 800 West and Freedom Blvd. The 500 North 800 West diversion conveys approximately 50% of flow to the south. The 500 North and Freedom Blvd diversion diverts 100% of flow to the south. These two diversions convey flow south into the Freedom Trunk and away from the Westside Trunk. Based on the observed flows shown in Tables 3-4 and 3-5, it would appear that these diversions have reduced average daily flow to the the Westside Trunk by approximately 1.6 mgd. BOWEN, COLLINS & ASSOCIATES 3-5 PROVO CITY

20 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN Table 3-4 Observed Average Flows at Site W1 (November 2000 ADS Site 3) Flow % Decrease Domestic (mgd) % Infiltration (mgd) 2.85* % Total (mgd) % * November 2000 infiltration has been adjusted to account for differences in ground water conditions between November 2000 and October 2008 Table 3-5 Observed Average Flows at Site W7 (November 2000 ADS Site 13) Flow % Decrease Domestic (mgd) % Infiltration (mgd) 2.00* % Total (mgd) % * November 2000 infiltration has been adjusted to account for differences in ground water conditions between November 2000 and October 2008 Site W4 This site which corresponds with ADS Flow Monitoring Site 7 (November 2000) was flow monitored primarily to identify the approximate frequency of pump cycles at the Westside lift station. Because this site is the discharge for the station s force main, it is not possible to distinguish between infiltration and domestic flows. Based on the observed maximum flow, it would appear that the 2008 flow monitor was able to more accurately document peak flows from the station using monitoring intervals of 6- minutes compared to the 15-minute interval used in Full results for all flow monitor locations should be obtained from the 2002 Wastewater Collection System Master Plan Volume 2 of 2, and the Wastewater Collection System 2009 Westside Update. FLOW MONITORING OBSERVATIONS In addition to aiding in the development of a computerized hydraulic sewer model, the flow monitoring results reveal several categories of concern in the sewer system: Sediment Accumulation An accumulation of sediment was observed at ADS flow monitoring locations 2, 7, 14, and 17 as shown in Figure 3-1. Once observed, these locations were cleaned by Provo City personnel to ensure adequate system operation. Backwater Backwater conditions exist in a pipe when the depth of water measured in the pipe is greater than the normal flow depth for a given discharge in the pipe. This occurs when there is a restriction or some type of control downstream that causes water BOWEN, COLLINS & ASSOCIATES 3-6 PROVO CITY

21 to backup. Downstream restrictions that cause backwater conditions are generally the result of one of three things: (1) a downstream pipe is too small for the flow being carried or is installed at an insufficient slope; (2) debris or roots are blocking a downstream pipe or manhole; or (3) poor hydraulics are restricting flow in downstream manhole. Significant backwater conditions were observed at monitoring locations 11, 20, 21, W8, W10, and W11. o o o o The backwater conditions at monitoring locations 20 and 21 were the result of insufficient capacity in the 18-inch line in 800 West immediately downstream of the monitors. This backwater condition was eliminated by the subsequent construction of the diversion and interceptor at Columbia Lane and Riverside Drive. Backwater at monitoring location 11 was probably the result of roots near the intersection of 400 East and Center Street. This condition was eliminated by standard maintenance procedures. Backwater at sites W8 and W11 was a result of inadequate capacity in the sewer main in Center Street, between 2650 West and 3100 West. This was eliminated by construction of the diversion and interceptor at Center Street and 2650 West. Site W10 is immediately upstream of the Harbor Park lift station and monitoring results were affected by interference from the Harbor Park Lift Station as flow backed up and was pumped down. No other issues were observed at this site and it does not warrant any action. o Minor backwater conditions were also observed at monitoring locations 3, 7, 10, 18, and 19. The backwater at these locations was not significant enough to merit concern. However, these locations represent good locations to conduct future flow monitoring as development occurs in Provo. Several future growth related improvement projects may be triggered by development upstream of these sites. High Infiltration Figure 3-2 shows the estimated infiltration for a majority of the monitoring locations (A detailed discussion of what infiltration is and how it was estimated is included in Chapter 4.) The American Society of Civil Engineers (ASCE) recommends an allowable infiltration rate for new construction of 500 gpd/in-dia/mile. For older sewer systems, infiltration rates are usually much greater than this. Average infiltration rates for older sewer systems range between 1000 and 4000 gpd/in-dia/mile depending on groundwater depth and age of pipe. Most of the estimated infiltration rates at locations monitored in this study fall within this range of expected values. Monitoring locations 7, 9, 11, 21, and W5 all had an unusually large amount of infiltration. Since the 2000 flow monitoring was conducted, Provo City has made concerted efforts to eliminate major sources of infiltration in the vicinity of monitoring locations 7, 9, 11, and 21. It is recommended that the City re-monitor these locations to assess the effectiveness of its rehabilitation efforts. 3-7

22 20,000 Figure 3-2 Estimated Infiltration Rates at Flow Monitoring Locations 19,000 18,000 17,000 18,139 16,000 15,000 14,000 13,000 12,000 11,000 10,000 9,000 8,000 7,000 7,526 Expected Infiltration for Older Systems 6,000 5,000 6,461 5,728 4,000 3,000 2,000 1,000-4,368 3,430 3,182 3,092 2,648 2,745 2,810 2,322 2,390 1,842 1,531 1,562 1,781 1, , ,113 1, W5 W10 W12 Westside System Ave Infiltration Rate (gpd/in-dia/mile) Flow Monitor Location ID Notes: 1) Average infiltration for monitoring locations 3 and 4 shown at 3.5 2) Infiltration not shown for monitoring locations where diversions make the contributing area unclear. Bowen Collins & Associates Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

23 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN In general, flow monitors on the Westside had less infiltration than the average for other monitoring sites. This was especially true for the flow monitors upstream of the Skipper Bay and Harbor Park Lift Stations. This is most likely the result of improved construction techniques such as the use of PVC pipe with gasketed joints. Flow monitor site W5 is one of the older areas developed on Provo s Westside and did have higher than average infiltration. Although the total infiltration from this neighborhood is relatively small, it is recommended that some effort be made to identify any major sources of infiltration in this neighborhood and make repairs as necessary. BOWEN, COLLINS & ASSOCIATES 3-9 PROVO CITY

24 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN CHAPTER 4 PROJECTED WASTEWATER SYSTEM GROWTH With the flow monitoring results described in Chapter 3, it is possible to assemble and calibrate a hydraulic model of existing conditions in the City s wastewater collection system. In order to do any kind of future planning, however, it is necessary to project how these flows will increase in the future. The purpose of this chapter is to project future wastewater flows associated with City growth. ESTIMATING EXISTING SEWER FLOWS A sanitary sewer inflow hydrograph consists of three major components: domestic flow, infiltration, and inflow. To estimate sewer flows for each sub-area, the contribution of each flow component must be considered. Domestic Flow Domestic flow consists of the wastewater contributions of residential, commercial, and industrial customers. Domestic flow from residential and commercial customers varies throughout the day. Peak flows are generated during the morning hours as residents shower and prepare for the day. There is a smaller peak in the early evening as residents return from work. Domestic sewer flows are generally lower throughout the remainder of the day and are just a trickle during the early morning hours when most residents are asleep. Flow from industrial customers may vary from this pattern depending on the type of industry. For the purposes of this study, industrial flow is assumed to be constant throughout the day. Two major challenges are encountered when estimating domestic flow. First, the quantity of wastewater produced varies from area to area depending on the type of water user in the area and the density of development. Second, domestic flow is not a constant value, but varies in time. Domestic Flow Production by Development Type Average daily flow for each sub-area was estimated based on the type of land use and density of development as identified in the City s 2009 General Plan as shown in Figure 4-1. Land use was accounted for by dividing the service area into eight land use types: low density residential, medium density residential, high density residential, multiple family residential and low density apartments, high density apartments, commercial, industrial, and public facilities. Each land use type was then assigned an average daily flow per acre. These values were estimated based on the average flow for monitoring locations across the study area (with infiltration removed, see below). The final values used in the model are summarized in Table 4-1. These values represent the average domestic flow an acre would produce if an area of the given land use type were 100 percent developed. BOWEN,COLLINS &ASSOCIATES 4-1 PROVO CITY

25 I-15 Legend Provo City Roads 2009 General Plan Residential Commercial Agricultural (Developmentally Sensitive) Public Facilities ³ Industrial Airport Related Downtown Mixed Use Canyon Road Transit Oriented Development Conservation Easements 3700 North North Temple Dr. State Street BYU Campus Center Street 600 South 1600 West 500 North 1100 West University Avenue 900 East Figure General Plan Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

26 1 1 Low Density Residential Medium Density Residential High Density Residential Multiple Family Residential and Low Density Apartments High Density Apartments Commercial Industrial Downtown Mixed Use Transit-Oriented Development based on 77 gpcd and 3.9 persons/unit The public facilities and agricultural land use type has not been included in Table 4-1. Average daily flows from areas with public facility land use vary too greatly to average into one value. This is because the public facilities classification includes areas of high domestic flow production (e.g., City office buildings and the BYU campus) as well as areas of very low domestic flow production (e.g., City parks). Areas classified as public facilities were examined independently and an average daily flow was estimated for each separate area. Flow production on the BYU campus was calculated using the measurements of 18 permanent flow monitors located on campus. The exception to this was the Wymount Terrace and Wyview Park apartments. The per capita sewage production measured at these locations was unexpectedly low (17 to 34 gpcd), possibly the result of malfunctioning meters. To produce a more realistic estimate of sewage production at the apartments, a per capita sewage production of 65 gpcd has been assumed at each of these apartments. This is consistent with per capita production values at other campus housing units, but is somewhat lower than the average per capita production across the City (77 gpcd). Areas zoned as agricultural have also been excluded from the table. It has been assumed that the contribution from these areas is very small in terms of gallons per acre and can be neglected. The mixed use, downtown, and transit-oriented development (TOD) land use types were added to the Provo City General Plan in Because these land use types have not previously existed, the flow in gallons per acre for these land use types cannot be based on previous flow monitoring results. Based on the General Plan description of each land use type, it was assumed that Downtown development would most closely match flows from High Density Apartments. For mixed use land use, it was assumed flows would be approximately the average of High 4-3

27 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN Density Residential and Commercial. For TOD land use, it was assumed flows would be approximately the average of High Density Apartments and Commercial. As mentioned above, these estimated sewer production values assume 100 percent development. To account for the current density of development, a value of percent developed was estimated for each land use area using current aerial photographs. The final estimate of average daily flow for a given area is calculated by multiplying the total acreage of the area by the percent developed and the flow per area based on land use type. The values of estimated average daily domestic flow by area are included in the Appendix. It is recommended that the City closely monitor actual housing densities as development occurs. If development occurs at densities significantly different than those assumed here, the results of this report will need to be updated accordingly. Domestic Flow Variation In an attempt to analyze domestic flow variation with time, unit hydrographs were developed for 10 separate monitoring locations. These 10 monitoring locations were selected because they monitor areas similar in size to the modeling sub-areas. A unit hydrograph was developed for each of the 10 monitoring locations by dividing the monitoring location s instantaneous flows throughout the day by its average daily flow. Unit hydrographs are convenient for analysis because they allow for comparison between hydrographs regardless of magnitude. Figure 4-2 shows the hydrographs for the 10 selected monitoring locations after the estimated infiltration has been removed and the hydrographs have been normalized by the average daily flow. Although each monitoring location is composed of different types of water users, the general pattern of water use is very similar among the monitoring locations. For this reason, it has been assumed that the pattern of water use throughout the day does not significantly vary between water user types (residential, commercial, etc.) This makes it possible to develop a domestic flow hydrograph for any unmonitored sub-area by multiplying the average unit hydrograph for these 10 locations by the average daily flow for the area under consideration. Infiltration Infiltration is the intrusion of groundwater into the sewer system through cracked pipes, broken and offset joints, improper connections, leaky manholes, etc. In areas with aging sewer lines and high groundwater, infiltration can actually be the largest component of flow being conveyed in the sewer. Infiltration is very difficult to measure because it varies across the service area based on climate conditions, water table levels, pipe diameter, and pipe condition. Estimated Infiltration during the Monitoring Period One approach to estimating infiltration is to use the assumption that domestic wastewater flows will be very small during the early hours of the morning. This assumption suggests that between approximately 2:00 a.m. and 5:00 a.m. flow in the sewer system will be almost entirely BOWEN,COLLINS &ASSOCIATES 4-4 PROVO CITY

28 ADS Monitoring Location 2 ADS MonitoringLocation23* ADS Monitoring Location 8 ADS Monitoring Location ADS Monitoring Location 10 ADS Monitoring Location ADS Monitoring Location 14 ADS Monitoring Location 17 ADS Monitoring Location 22 ADS Monitoring Location 23 ADS Monitoring Location 24 Average Hourly Unit Hydrograph Note: Hydrographs are based on flow monitoring conducted in November 2000 *Peak at ADS Monitoring Location 23 was a result of the Missionary Training Center schedule for Showers. Bowen, Collins & Associates Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

29 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN infiltration. For the purposes of this study, it has been assumed that the infiltration in lines with flow monitors can be estimated as being approximately equal to the minimum observed flow. Once infiltration is estimated at each monitoring location, this information can be used to calculate an infiltration flow rate per length of pipe for all pipes upstream of the monitoring point. The calculated infiltration rates for most of the flow monitoring locations are summarized in Figure 3-2 (Chapter 3). Infiltration for any unmonitored lines can be estimated by multiplying the total length of upstream pipe by the estimated infiltration rate per length of pipe for the nearest monitoring location. Seasonal Variation in Infiltration The estimated infiltration obtained using the methods described above is only appropriate for the monitoring period. Before using the estimated infiltration values in planning scenarios, the infiltration rates used in this study may need to be adjusted to account for seasonal fluctuations in the groundwater table. The flow monitoring conducted as part of this study was performed in the late fall. Figure 4-3 shows historical monthly minimum flows at the Provo City Wastewater Treatment Plant (WWTP) from 1990 through From this figure, it can be seen that minimum flows at the WWTP are an average of 3.9 mgd higher in August than in late fall. This increase can be almost entirely attributed to increases in infiltration associated with summer irrigation and water in the Provo River. Thus, it can be concluded that observed infiltration from the monitoring records will need to be adjusted upward for system evaluation purposes. However, this adjustment will also need to account for annual variations in infiltration as discussed below. For comparison purposes, Figure 4-4 shows historical monthly average flows at the Provo City WWTP. Annual Variation in Infiltration Figure 4-5 shows historical monthly minimum flows at the City s WWTP from 1990 through Figure 4-6 shows the minimum annual flow at the plant compared to annual precipitation. From these figures, it is apparent that, in addition to fluctuating seasonally, infiltration also fluctuates from year to year. It is also apparent that this fluctuation is closely tied to annual precipitation. The figures also appear to indicate that infiltration during the most recent decade (2000 to 2009) has been notably lower than that observed from 1990 to There are two potential factors that may be causing this decrease. The first is climate. Provo City has been in a mostly dry climate cycle over the last decade. Because of this extended drought, ground water levels have likely experienced significant declines. Although there have been a few recent years with above average precipitation, these years have probably not been enough to fully recover ground water levels. It will likely take a return to wetter climate cycle for an extended period to see the full ground water recovery. The second issue that is likely contributing to the observed decline in infiltration is system improvements. Based on the flow monitoring completed in 2000, BC&A identified several areas BOWEN,COLLINS &ASSOCIATES 4-6 PROVO CITY

30 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Median *Average Minimum Flow for each month is the 30-day average of the minimum flows for every day of the month. Bowen, Collins & Associate Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

31 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Median *Average Monthly Flow for each month is the 30-day average of the average flow for every day of the month. Bowen, Collins & Associates Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

32 Bowen, Collins & Associates Average Average Minimum Flow* (mgd) Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan Jan-90 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 *Average Minimum Flow is the 30-day average of minimum daily flows for every day of the month.

33 Min Annual Flow 5 Annual BYU (in) Bowen, Collins & Associates Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

34 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN in the Provo City system with higher than average infiltration. Through inspection and repair efforts, the City was able to eliminate a number of sources of significant infiltration in 2001 and From the figures, the timing of these improvements appears to correspond with a significant downward shift in infiltration that occurred around It is difficult to quantify how much each of these factors is contributing to the reduction in infiltration. For the purpose of this study, the total infiltration rate used for conveyance modeling is 12.5 mgd. This value corresponds to the highest median infiltration in July during the period of record. This value is higher than all of the values from 2000 to 2009, but is lower than all of the values from 1990 to Using this value conservatively assumes that nearly all of the recent reduction in infiltration is the result of climate conditions and that infiltration will approach the same levels as observed in the 1990 s during the next wet cycle. The maximum value of infiltration will not be used based on the assumption system improvements have contributed to some reduction in infiltration and a full return to historic levels is unlikely. Daily Variation in Infiltration Although infiltration varies with time when examined over a period of several months or years, very little variation in time will occur during a single day. Therefore, when infiltration is added to a hydraulic model as a component of the total estimated sewer flow, it is added simply as a constant flow. The estimated infiltration rates included in the hydraulic model are presented in the Appendix. Inflow Similar to infiltration, inflow is also the intrusion of unwanted water into the sewer system. In the case of inflow, however, this water comes from rainfall and snowmelt instead of groundwater. Inflow may enter the sewer system through roof and foundation drains, yard and area drains, manhole covers, and illicit storm drain connections. In the case of the assorted roof and yard drains, discharge into the sanitary system is against City ordinances. However, illegal connections often exist and can significantly affect the performance of the sewer system. Figure 4-7 illustrates the effect of inflow on Provo City sewer flows. The figure shows measured precipitation depths from individual storm events versus the related increase in monitored flow at the WWTP. From the figure it is apparent that inflow has a significant effect on sanitary sewer flows. A best-fit line has been drawn to estimate the amount of inflow corresponding to a given precipitation depth from a single storm event. From this line it is possible to estimate the increase in sanitary sewer flow that will result from a storm event of any given magnitude. For example, a 5-year, 12-hour storm with a total precipitation depth of 0.9 inch will result in an estimated increase in sewer discharged to the WWTP of 2.1 mgd due to inflow. Flow hydrograph adjustments were not made to account for inflow in the sewer system model. Instead, a portion of the capacity of each pipe was reserved for inflow when assessing pipe capacity. In other words, a pipe will be identified as having inadequate capacity at flows somewhat less than the full flow capacity of the pipe. This will leave some capacity in each pipe to carry inflow. This is discussed in greater detail in Chapter 6 System Evaluation. BOWEN,COLLINS &ASSOCIATES 4-11 PROVO CITY

35 Precipitation Depth (in), BYU Gage Flow Increase at WWTP (mgd) Bowen, Collins & Associates Provo City Division of Water Resources Wastewater Collection System 2010 Master Plan

36 WASTEWATER COLLECTION SYSTEM 2010 MASTER PLAN PROJECTION OF FUTURE SEWER FLOWS Population Projections Population projections for the Provo City sewer system service area were prepared through the year 2060 in three steps: 1. Population projections through 2030 have been taken directly from estimates prepared by the City s Community Development Department. 2. The projected Provo City population at build-out has been estimated by BC&A personnel based on projected land use as identified in the City s recently adopted General Plan. This process is discussed in greater detail below. The final build-out population for Provo City is estimated to be 197, Population growth between 2030 and build-out was estimated by BC&A personnel by extrapolating pre-2030 growth rates into the future. Growth rates immediately after 2030 were assumed to be identical to the growth rates immediately before 2030 as calculated by Community Development. These rates were then diminished slowly as total population approached the City s build-out population. Based on this procedure, it is estimated that the City will reach full build-out by approximately While these three steps give the basics of the projections, some additional discussion is merited regarding calculation of the build-out population. When the City s last sewer master planning efforts were completed in 2002, Provo City s Community Development Department estimated that the future build-out population of the City would be approximately 170,000. Since that time, however, the City has adopted a new General Plan that has made some significant changes to projected development patterns. Figure 4-8 shows some of the areas affected by changes adopted in the most recent Provo City General Plan. For the purposes of this study, the greatest changes fall under one of two categories. First, there has been a large increase in potential development densities on the City s west side. Areas now shown as residential, industrial, and airport related zones in the figure were previously designated as agricultural or developmentally sensitive. Second, the General Plan now includes a number of new additions to encourage re-development of existing areas at higher densities. Redevelopment at higher density will mainly affect three areas: Downtown Area The new General Plan includes designation of a downtown area at the City s center. This area has recently been rezoned to encourage greater densities for redevelopment. Transit Oriented Development Immediately south of the City s downtown is an area that has been designated for transit oriented development. This area is centered on a proposed intermodal hub and has been zoned to encourage high density housing. BOWEN,COLLINS &ASSOCIATES 4-13 PROVO CITY