COMPREHENSIVE WATER WASTEWATER MASTER PLAN · 2020-03-13 · wastewater master plan final report b&v project no. 167797 contact name: jeffrey d. coggins company name: black & veatch

COMPREHENSIVE WATER & WASTEWATER MASTER PLAN

FINAL REPORT B&V PROJECT NO. 167797

CONTACT NAME: JEFFREY D. COGGINS COMPANY NAME: BLACK & VEATCH INTERNATIONAL COMPANY ADDRESS: 8520 CLIFF CAMERON DRIVE, SUITE 210 CITY, STATE, ZIP: CHARLOTTE, NC 28259 PHONE: 704.548.8461 EMAIL: [email protected]

Union County, North Carolina DECEMBER 2011

©Black & Veatch Holding Company 2011. All rights reserved.

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Union County, North Carolina | COMPREHENSIVE WATER & WASTEWATER MASTER PLAN

BLACK & VEATCH | Table of Contents i

Table of Contents ES Executive Summary .................................................................................................... ES-1

ES-1 Introduction ...................................................................................................................... ES-1

ES-2 Community Outreach ........................................................................................................ ES-1

ES-3 System Growth - Population & Demand/Flow Projections .............................................. ES-1

ES-4 Scenarios for Meeting Future Treatment Capacity Needs ............................................... ES-2

ES.4.1 Water Treatment .............................................................................................................. ES-3

ES.4.2 Wastewater Treatment ..................................................................................................... ES-4

ES.4.3 Interbasin Transfer ............................................................................................................ ES-5

ES-5 Water Distribution System ................................................................................................ ES-6

ES.5.1 Supply and Treatment Facilities ........................................................................................ ES-6

ES.5.2 Supply and Transfer Pumping Stations ............................................................................. ES-6

ES.5.3 Storage Facilities ............................................................................................................... ES-6

ES-6 Wastewater Collection System ......................................................................................... ES-7

ES.6.1 Twelve Mile WRF and Collection System .......................................................................... ES-7

ES.6.2 Crooked Creek WRF and Collection System ...................................................................... ES-7

ES.6.3 Six Mile Basin .................................................................................................................... ES-7

ES.6.4 City of Monroe WWTP and Tributary Improvements ....................................................... ES-8

ES.6.5 Local Wastewater Treatment Plants ................................................................................. ES-8

ES.6.6 Community Outreach and New Wastewater Service ....................................................... ES-8

ES-7 Recommended Capital Improvement Plan ....................................................................... ES-8

ES-8 Project Costing Criteria ..................................................................................................... ES-9

Board Presentation .............................................................................................................................. 1

Chapter 1. Community Outreach .................................................................................................. 1-1

1.1 Waxhaw .............................................................................................................................. 1-3

1.2 Marvin ................................................................................................................................. 1-4

1.3 Stallings ............................................................................................................................... 1-4

1.4 Fairview ............................................................................................................................... 1-5

1.5 Indian Trail .......................................................................................................................... 1-5

1.6 City of Monroe .................................................................................................................... 1-5

1.7 Marshville ............................................................................................................................ 1-5

1.8 Mineral Springs ................................................................................................................... 1-6

1.9 Unionville ............................................................................................................................ 1-6

1.10 Weddington ........................................................................................................................ 1-6

Comprehensive Water & Wastewater Master Plan | Union County, North Carolina

ii DECEMBER 2011

1.11 Wingate ............................................................................................................................... 1-7

Chapter 2. Population & Demand/Flow Projections ...................................................................... 2-1

2.1 Background ......................................................................................................................... 2-1

2.2 Population Growth & Allocation ......................................................................................... 2-2

2.3 Rate of Population Growth ................................................................................................. 2-3

2.4 Population Projections ........................................................................................................ 2-5

2.5 Water Demand and Wastewater Flow Projections ............................................................ 2-7

2.5.1 Water Demand Projections ................................................................................................. 2-7

2.5.1.1 Per Capita Water Demand .................................................................................................. 2-7

2.5.1.2 Water Max Day Peaking Factor ........................................................................................... 2-8

2.5.2 Wastewater Flow Projections ............................................................................................. 2-8

2.5.2.1 Per Capita Wastewater Flow ............................................................................................... 2-9

2.5.2.2 Wastewater Max Month Peaking Factor .......................................................................... 2-10

Chapter 3. Future Water and Wastewater Scenarios .................................................................... 3-1

3.1 Introduction ........................................................................................................................ 3-1

3.2 Inter-Basin Transfer ............................................................................................................ 3-1

3.3 Water .................................................................................................................................. 3-6

3.3.1 Water Planning Considerations........................................................................................... 3-6

3.4 Wastewater ......................................................................................................................... 3-7

3.4.1 Wastewater Planning Considerations ................................................................................. 3-8

3.4.2 Catawba River Basin Service Area ..................................................................................... 3-10

3.4.2.1 Twelve Mile WRF ............................................................................................................... 3-10

3.4.3 Yadkin/Pee Dee River Basin Service Area ......................................................................... 3-11

3.4.3.1 Crooked Creek WRF .......................................................................................................... 3-11

3.4.3.2 Olde Sycamore WWTP, Tallwood Estates WWTP, and Grassy Branch WWTP ................. 3-11

3.4.4 Wastewater Reuse Considerations ................................................................................... 3-12

3.4.5 Biosolids Management Considerations............................................................................. 3-12

Chapter 4. Water System Improvements ...................................................................................... 4-1

4.1 Recommended System Improvements ............................................................................... 4-1

4.1.1 821 Zone Improvements ..................................................................................................... 4-2


4.1.3 853 West Improvements ..................................................................................................... 4-2

4.1.4 853 South Zone Improvements ........................................................................................... 4-3


4.1.6 853 East Zone Improvements ............................................................................................. 4-4


BLACK & VEATCH | Table of Contents iii



4.2 Water System Model Inventory, Update and Calibration .................................................. 4-5

4.2.1 Model Inventory and Update .............................................................................................. 4-5

4.2.1.1 Pump Curves ....................................................................................................................... 4-6

4.2.1.2 Model Junction Elevations .................................................................................................. 4-6

4.2.1.3 Base Max Elevations:........................................................................................................... 4-6

4.2.1.4 Base Min Elevations: ........................................................................................................... 4-6

4.2.1.5 Water Demand Allocation ................................................................................................... 4-6

4.2.1.6 Geocoding ........................................................................................................................... 4-7

4.2.1.7 Network Trace ..................................................................................................................... 4-7

4.2.2 Model Calibration................................................................................................................ 4-9

4.2.2.1 Calibration Day .................................................................................................................... 4-9

4.2.2.2 Pump Station Flows ........................................................................................................... 4-10

4.2.2.3 Diurnal Demand Curve Development ............................................................................... 4-11

4.2.2.4 EPS Calibration Model System Set-Up .............................................................................. 4-11

4.2.2.5 EPS Calibration Verification Results .................................................................................. 4-12

4.2.2.6 Calibration Summary: ........................................................................................................ 4-12

4.3 Base and Future-Year Water Demands ............................................................................. 4-12

4.3.1 Base Year Average Day Demand ....................................................................................... 4-13

4.3.2 Base Year Maximum Day Demand .................................................................................... 4-13

4.3.3 Base-Year Peak Hour Demand .......................................................................................... 4-13

4.3.4 Future-Year Maximum Day Demand ................................................................................ 4-13

4.3.5 Future-Year Peak Hour Demand ....................................................................................... 4-13

4.4 Facility Analyses ................................................................................................................ 4-14

4.4.1 Existing Pressure Zones ..................................................................................................... 4-14

4.4.2 Supply and Treatment Facilities ........................................................................................ 4-15

4.4.2.1 Summary of Water Treatment and Supply Facilities ........................................................ 4-15

4.4.2.2 Catawba River Water Treatment Plant ............................................................................. 4-15

4.4.2.3 Anson Supply Interconnection .......................................................................................... 4-15

4.4.3 Assessment of Treatment/Supply Capacity Surplus/Deficit ............................................. 4-15

4.4.3.1 Catawba Basin ................................................................................................................... 4-16

4.4.3.2 Yadkin Basin ...................................................................................................................... 4-16

4.4.4 Supply and Zone Transfer Pumping Stations .................................................................... 4-16


iv DECEMBER 2011

4.4.4.1 Calculation of Pump Capacities ......................................................................................... 4-16

4.4.5 Assessment of Available Supply and Zone Transfer Pumping .......................................... 4-17

4.4.5.1 821 Zone ............................................................................................................................ 4-17

4.4.5.2 853 South Zone ................................................................................................................. 4-17

4.4.5.3 853 West Zone .................................................................................................................. 4-17

4.4.5.4 853 East Zone .................................................................................................................... 4-18

4.4.5.5 935 Zone ............................................................................................................................ 4-18

4.4.5.6 762 Zone ............................................................................................................................ 4-18

4.4.6 Storage Facilities ............................................................................................................... 4-19

4.4.6.1 Summary of Storage Facilities ........................................................................................... 4-19

4.4.6.2 Equalization Storage ......................................................................................................... 4-20

4.4.6.3 Fire/Emergency Reserve ................................................................................................... 4-21

4.4.6.4 High Elevation Customers Impacting Available Storage for Equalization ......................... 4-22

4.4.6.5 821 Zone ............................................................................................................................ 4-22

4.4.6.6 853 West Zone .................................................................................................................. 4-22

4.4.6.7 853 South Zone ................................................................................................................. 4-23

4.4.7 Assessment of System Storage ......................................................................................... 4-23

4.4.7.1 821 Zone ............................................................................................................................ 4-24

4.4.7.2 853 South Zone ................................................................................................................. 4-24

4.4.7.3 853 West Zone .................................................................................................................. 4-24

4.4.7.4 880 Zone ............................................................................................................................ 4-25

4.4.7.5 853 East Zone .................................................................................................................... 4-25

4.4.7.6 935 Zone ............................................................................................................................ 4-26

4.4.7.7 762 Zone ............................................................................................................................ 4-26

4.5 Distribution System Analyses ............................................................................................ 4-26

4.5.1 CIP Modeling Results – Performance Criteria Not Met .................................................... 4-27

4.5.2 2030 Maximum Day / Peak Hour Steady State Simulation – Minimum Pressures and Maximum Velocity / Headloss .................................................. 4-27

4.5.2.1 Minimum Pressures .......................................................................................................... 4-28

4.5.2.2 Maximum Pipeline Velocity .............................................................................................. 4-29

4.5.2.3 Maximum Pipeline Headloss Gradient .............................................................................. 4-29

4.5.3 2030 Average Day Steady State Simulation – Maximum Pressures ................................. 4-30

4.5.4 2030 Maximum Day Fire Flow Simulation – Available Fire Flows ..................................... 4-31

Chapter 5. Wastewater System Improvements ............................................................................. 5-1


BLACK & VEATCH | Table of Contents v

5.1 Recommended System Improvements ............................................................................... 5-1

5.1.1 Crooked Creek Basin Improvements ................................................................................... 5-1

5.1.1.1 Crooked Creek WRF ............................................................................................................ 5-1

5.1.1.2 Crooked Creek Collection System ....................................................................................... 5-1

5.1.2 Six Mile Basin Improvements (McAlpine WWTP) ............................................................... 5-2

5.1.3 Twelve Mile Basin Improvements ....................................................................................... 5-2

5.1.3.1 Twelve Mile WRF ................................................................................................................. 5-2

5.1.3.2 Twelve Mile Collection System ........................................................................................... 5-2

5.1.4 City of Monroe WWTP Tributary Improvements ................................................................ 5-3

5.1.4.1 City of Monroe WWTP ........................................................................................................ 5-3

5.1.5 Eastside, Lake Twitty, Lake Lee & Richardson Creek Basins ............................................... 5-3

5.1.6 Local WWTPs ....................................................................................................................... 5-4

5.2 Wastewater System Model Inventory, Update and Calibration ......................................... 5-4

5.2.1 Model Inventory and Update .............................................................................................. 5-4

5.2.2 Model Calibration................................................................................................................ 5-6

5.2.2.1 Dry-Weather Calibration ..................................................................................................... 5-7

5.2.2.2 Wet-Weather Calibration .................................................................................................... 5-9

5.3 Base and Future-Year Wastewater Flows ......................................................................... 5-10

5.4 Collection System Analyses ............................................................................................... 5-10

5.4.1 Community Outreach & New Wastewater Service ........................................................... 5-11

5.5 Collection System Stress Test ........................................................................................... 5-11

Chapter 6. Capital Improvement Plan ........................................................................................... 6-1

6.1 Introduction ........................................................................................................................ 6-1

6.2 Growth versus Non-Growth Project Assessments .............................................................. 6-1

6.3 Project Costing Criteria ....................................................................................................... 6-2

6.3.1 Unit Construction Costs ...................................................................................................... 6-2

6.3.2 Water Unit Construction Costs ........................................................................................... 6-2

6.3.3 Wastewater Unit Construction Costs .................................................................................. 6-3

6.3.4 Construction Contingency Cost Estimate ............................................................................ 6-4

6.3.5 Engineering Cost Estimate .................................................................................................. 6-4

6.3.6 Total Cost Estimate ............................................................................................................. 6-5

6.4 CIP Table .............................................................................................................................. 6-5

6.5 CIP Figures ........................................................................................................................... 6-5

Appendix System Performance Criteria .......................................................................................... 1

Water ..................................................................................................................................... 1

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Wastewater ............................................................................................................................ 1

Appendix Facilities Assessment ...................................................................................................... 1


BLACK & VEATCH | Table of Contents vii

LIST OF TABLES Table ES-1 Future Served Population & Flow ............................................................................................. ES-2 Table ES-2 Available Treatment/Supply Capacity .................................................................................... ES-6 Table 1-1 Community Outreach Meetings ................................................................................................... 1-1 Table 1-2 Community Outreach Issues ......................................................................................................... 1-2 Table 2-1 Differential Total Population Growth By Area ....................................................................... 2-6 Table 2-2 Served Population Count By Type & Area ............................................................................... 2-7 Table 2-3 Water Demand Projections ............................................................................................................ 2-8 Table 2-4 Wastewater flow Projections ...................................................................................................... 2-10 Table 4-1 Base and Future-Year Demand Summary.............................................................................. 4-13 Table 4-2 Critical Customers ........................................................................................................................... 4-15 Table 4-3 Available Treatment/Supply Capacity .................................................................................... 4-16 Table 4-4 Model-Calculated Firm Pump Station Capacities ................................................................ 4-17 Table 4-5 Available Supply and Zone Transfer Pumping ..................................................................... 4-19 Table 4-6 Storage Facility Summary............................................................................................................ 4-19 Table 4-7 High Elevation Customer by Zone ............................................................................................. 4-20 Table 4-8 Effective Storage Available for Equalization ......................................................................... 4-21 Table 4-9 Effective Storage Available for Fire Reserve/Emergency ............................................... 4-21 Table 4-10 821 Zone Storage Available for Equalization ....................................................................... 4-22 Table 4-11 853 West Zone Storage Available for Equalization ............................................................ 4-23 Table 4-12 853 South Zone Storage Available for Equalization .......................................................... 4-23 Table 4-13 821 Zone Storage Assessment .................................................................................................... 4-24 Table 4-14 853 South Zone Storage Assessment ....................................................................................... 4-24 Table 4-15 853 West Zone Storage Assessment ........................................................................................ 4-25 Table 4-16 880 Zone Storage Assessment .................................................................................................... 4-25 Table 4-17 853 East Zone Storage Assessment .......................................................................................... 4-25 Table 4-18 935 Zone Storage Assessment .................................................................................................... 4-26 Table 4-19 762 Zone Storage Assessment .................................................................................................... 4-26 Table 5-1 Major Wastewater Service Areas Sewer Inventory ............................................................. 5-5 Table 5-2 Model Data Flags ................................................................................................................................ 5-6 Table 5-3 Temporary Flow Monitoring Period .......................................................................................... 5-7 Table 5-4 Major Treatment Facility Projected Maximum Month Flows By Planning Year .............................................................................................................................. 5-10 Table 6-1 Water Pipe Unit Construction Costs ........................................................................................... 6-2 Table 6-2 Elevated Storage Unit Construction Costs ............................................................................... 6-3 Table 6-3 Gravity Sewer Pipe Unit Construction Costs .......................................................................... 6-3 Table 6-4 Force Main Unit Construction Costs ........................................................................................... 6-4 Table 6-5 Wastewater Pumping Station Unit Construction Costs ..................................................... 6-4


viii DECEMBER 2011

Appendix Table 1 Union County’s Water Performance Parameters ............................................................... 1 Appendix Table 2 Union County’s Wastewater Performance Parameters................................................... 2

LIST OF FIGURES Figure ES-1 Union County Basin Boundary and Water and Wastewater Treatment Plants .............................................................................................................................. ES-3 Figure ES-2 Wastewater 2030 Service Envelope ........................................................................................ ES-5 Figure ES-3 CIP Summary ..................................................................................................................................... ES-9 Figure 2-1 Population & Flow Projection Elements ................................................................................... 2-3 Figure 2-2 Union County Residential Building Permits Issued ............................................................. 2-4 Figure 2-3 Union County Differential Growth Map .................................................................................... 2-6 Figure 2-4 Wastewater Service Area Boundary .......................................................................................... 2-9 Figure 3-1 Union County Basin Boundary and Water and Wastewater Treatment Plants ................................................................................................................................ 3-1 Figure 3-2 Scenario 1 – 5 mgd IBT .................................................................................................................... 3-3 Figure 3-3 Scenario 2 – 10 mgd IBT ................................................................................................................. 3-4 Figure 3-4 Scenario 3 - 13.5 mgd IBT 3-5 Figure 3-5 Sewer Service Areas .......................................................................................................................... 3-8 Figure 4-1 Proposed Pressure Zone Boundaries ........................................................................................ 4-1 Figure 4-2 Main Updates to the Hydraulic Model ....................................................................................... 4-5 Figure 4-3 Network Trace Demand Allocation ............................................................................................ 4-8 Figure 4-4 Pump Station Flow Estimation Example – Highway 74 Pump Station ................................................................................................................................................... 4-10 Figure 4-5 Union County Base-Year System Pressure Zones ............................................................... 4-14 Figure 4-6 Austin Tank Effective Storage for Equalization ................................................................... 4-20 Figure 4-7 2030 Maximum Day / Peak Hour Minimum Pressures .................................................. 4-28 Figure 4-8 2030 Maximum Day / Peak Hour Maximum Pipeline Velocities ............................................................................................................................................. 4-29 Figure 4-9 2030 Maximum Day / Peak Hour Minimum Headloss Gradients ............................................................................................................................................. 4-30 Figure 4-10 2030 Average Day Maximum Pressures................................................................................ 4-31 Figure 4-11 Needed Fire Flows in Excess of 1,500 gpm (ISO Reports 2001 – 2008) ...................................................................................................................................... 4-32 Figure 4-12 2030 Model-Predicted Available Fire Flows (Transmission System Only) ...................................................................................................................................... 4-33 Figure 5-1 Wastewater Collection System 2030 Stress Test ............................................................... 5-12


BLACK & VEATCH | Executive Summary ES-1

ES Executive Summary

ES-1 Introduction In the past, master planning efforts for Union County focused individually on the water system or wastewater system, were completed by several different consultants, and were conducted on differing years. The Union County Comprehensive Water & Wastewater Master Plan (Master Plan) provides an assessment of all of the public works system including water supply, water treatment and distribution, wastewater collection, wastewater treatment and disposal, and residuals/biosolids management facilities and systems. By including all utilities in the Master Plan, the result is a thorough well coordinated document that will serve as a guide to future system development and investment decisions.

A key component of the Master Plan is the outreach program which included participation from the elected officials and professional staffs of the communities of the County to ensure the Plan supports local development and community needs. In addition, the Union County Leadership Team provided their vision for the water and wastewater utility in the County going forward. They provided valuable input on key issues and provided critical policy guidance which is incorporated into the Master Plan. This policy based Master Plan approach provided needed input to allow for water supply, wastewater treatment, IBT, sewer service areas, and partnering efforts with other entities issues to be considered and coordinated resulting in a consistent and coordinated plan. The Leadership Team included 2 members of the Union County Board of Commissioners, County Manager, County Attorney, County CFO, County Planning Director, County Public Works Director, and UCPW staff. Through this internal and external outreach, the Comprehensive Master Plan captures their vision and results in an integrated water resource plan that provides a foundation for effective management of the water and wastewater systems in the County.

ES-2 Community Outreach The first task undertaken in the Comprehensive Master Plan project was executing the Community Outreach program. Leadership from each of Union County’s communities were invited to outreach discussions to understand needs, concerns, and overall expectations they have for utilities in their communities. The feedback expressed in these meetings is summarized in Table 1-2 of the Community Outreach section.

Common recurring themes included concerns of arsenic in County well water and the desire for available public water, the future transition of existing septic systems to public sewer in selected areas of the County, and enhanced water and wastewater treatment capacity to continue to support new development initiatives throughout the County. This feedback was very important as solutions and projects were identified in the Master Plan.

ES-3 System Growth - Population & Demand/Flow Projections Union County had been the fastest growing County in North Carolina in the early portion of the 2000 decade, outpacing the balance of the State’s growth by a factor of 3 to 4. A key driver to this rapid growth had been the proximity to Charlotte and the increasing base of jobs within the County. The economic recession and downturn brought the extraordinary growth rates back to more modest rates of 2 to 3 percent in the past several years. It is within this current economic and

Comprehensive Water & wastewater Master Plan | Union County, North Carolina

ES-2 DECEMBER 2011

modest growth environment that this Master Plan most differs from prior master planning projections.

After a review of current growth trends and indicators, a 2.4% population rate of growth was selected over the Master Plan timeframe. The Leadership Team confirmed this population growth was appropriate. Allocation of the future population was spatially distributed to geographic regions of the County differently based on known and anticipated growth drivers. Since the future population was not distributed uniformly across County, projected new water demands and sewer flows in some portions of the County will initially exceed the 2.4% rate of growth for select planning years.

The population projections were used to develop water and wastewater flow projections. based on historical demand data Union County has effectively implemented water conservation measures including watering restrictions and conservation rate structure which has resulted in overall reduced water demand in the system. These proactive and forward thinking policies have allowed Union County to effectively manage the water system. Similar type conservation measures will need to continue to assure that the County has adequate water supply into the future.

The population, water, and wastewater projections used in the Master Plan are summarized in Table ES-1.

TABLE ES-1 FUTURE SERVED POPULATION & FLOW

BASE CUMULATIVE

WAT

ER

2015 2020 2030 Population Served 107,054 126,073 147,336 198,049

Total Consumption (Billed Flow) (mgd) 9.2 10.9 13.3 18.9

Non-Revenue Water (mgd) 1.3 1.9 2.3 3.3

Total Flow (mgd) 10.5 12.9 15.6 22.2

Peak Day Flow (mgd) 18.1 24.5 29.7 42.2

WAS

TEW

ATER

Population Served 94,086 111,361 131,302 170,188

Total Flow (mgd) 6.7 8.5 11.4 15.4

Max Month Flow (mgd) 8.7 11.1 14.9 20.0

Peak Day water demand and Maximum Month wastewater flow are used to size treatment facilities.

ES-4 Scenarios for Meeting Future Treatment Capacity Needs Union County straddles two major watersheds, the Catawba River to the west and the Yadkin-Pee Dee River to the east. The ridge line between these two watersheds runs predominately north-south through the County (Figure ES-1). The ridge line separates the more densely populated western side of the County from the eastern portion of the County. The existing inter-basin transfer regulations (IBT) impact water supply withdrawal and wastewater discharge strategies for current



and future planning. Water supply and wastewater planning performed within this Master Plan explicitly acknowledge some constraints imposed by the IBT.

Figure ES-1 Union County Basin Boundary and Water and Wastewater Treatment Plants

The basic scenarios for treatment capacity planning are organized around IBT limits. The current North Carolina grandfathered IBT limit from the Catawba Basin to the Yadkin Basin is 5 mgd. Additional IBT scenarios of 10 mgd and 13.5 mgd were developed in the Master Plan to evaluate and assess reasonable future forecasts for treatment capacity and their respective water supply and wastewater discharge locations. It is noted that the current South Carolina IBT permit limit for the Catawba River WTP is 20 mgd, which was based on an 13.5 mgd allocation for Union County. Therefore, these additional 10 mgd and 13.5 mgd scenarios are within the allocated limit established by the South Carolina IBT permit.

ES.4.1 Water Treatment

The County’s primary water supply and treatment is delivered from the Catawba River WTP (CRWTP) in Lancaster County, SC. The CRWTP is a regional treatment facility with a permitted operating capacity of 36 mgd with the County having ownership of 18 mgd of capacity. With the County’s ownership stake in this plant, issues of reliability and water quality are proactively addressed by direct negotiation and funding of necessary improvements.

The County also has an existing agreement with Anson County for 4 mgd of maximum day capacity (bulk water purchase, no ownership rights in the Anson County WTP) and a pending agreement


ES-4 DECEMBER 2011

awaiting Anson County execution for an additional 2 mgd (6 mgd total). Additional transmission upgrades are needed within Anson County to make the full 6 mgd of supply capacity available. As a wholesale customer of Anson County, Union County has experienced multiple periods of unstable water quality and insufficient supply that has impacted the reliability and dependability of water supply from this source.

A reliable and secure eastern water supply is required to meet future water demands of the planning horizon. The Leadership Team directed staff to develop planning based on the County becoming an equity partner with a neighboring utility from the east. The partnership would emulate the current relationship with Lancaster County, SC where the County has an ownership stake in both the supply and treatment elements of the infrastructure. Discussions with Anson County, Stanly County, City of Albemarle, and Town of Norwood have occurred with the goal of entering into a viable long-term solution.

ES.4.2 Wastewater Treatment

County owned and operated treatment plants include Twelve Mile WRF (6.0 mgd), Crooked Creek WRF (1.9 mgd), Olde Sycamore WWTP (0.15 mgd), Tallwood Estates WWTP (0.05 mgd), and Grassy Branch WWTP (0.05 mgd). Capacity has also been purchased from Charlotte-Mecklenburg Utilities (CMU) at the McAlpine WWTP (1.0 mgd presently, 3.0 mgd by agreement) which serves the Six Mile basin in the County and from the City of Monroe WWTP (2.65 mgd) which serves the eastside including Marshville and Wingate. All capacities are presented as maximum month treatment capacities.

Sewer service area boundaries were developed to ensure the scenario planning could quantify future wastewater conveyed from specific geographic areas and project which treatment plant and basin would receive the discharge. These service area boundaries were shaped and influenced by a number of factors including;

Land-use Considerations - spatially allocating future growth around existing development centers or projected development drivers and preserving the rural character of the eastern and southern portions of the County.

Environmental Factors- the Carolina Heelsplitter is an endangered species and one local population has been identified in Goose Creek and Duck Creek in the northeast corner of the County. Environmental regulations in these basins require extraordinary measures to provide public sewer and these areas will not be included in the future public sewer service area.

Monroe Bypass- the new by-pass is expected to generate commercial development at proposed interchanges and residential development along the major feeder routes. Wastewater flows are planned to discharge at key points to the existing Monroe collection system for treatment at the Monroe’s WWTP. The future projected flow of the extended Monroe service area is twice the current maximum month purchased capacity of 2.65 mgd from Monroe which will require negotiations with the City.

Inter-Basin Transfer- the IBT issue places a premium on maximizing Catawba River discharges for treated wastewater effluent. The Master Plan continues that wastewater conveyance philosophy and leverages increases in the future wastewater flow transfers through the Poplin



WWPS pump-over to contribute positively to any future IBT limitations, regardless of the scenario.

The sewer service area was discussed with the Leadership Team and the approved sewer envelop is shown in Figure ES-2.

Figure ES-2 Wastewater 2030 Service Envelope

ES.4.3 Interbasin Transfer

The bond that links current and future water supply and wastewater disposal is the inter-basin transfer limitations for the Catawba River basin. The North Carolina grandfathered Catawba River IBT amount for the County is 5mgd. This means that up to 5 mgd may be transferred out of the Catawba River basin and not returned to the Catawba River basin for disposal. If the IBT is maintained at the 5 mgd limit, then significant efforts will be needed earlier in the planning horizon to develop the eastern water supply.

Increasing the IBT limit has the impact of both deferring the timeline required for developing the eastern water supply and reducing the magnitude of this supply which will decrease the overall capital costs associated with proposed alternatives. The Leadership Team provided direction to pursue increasing the IBT limit as an element of this Master Plan. For the purpose of developing the Capital Improvement Plan (CIP) and associated costs, an increase of the IBT to 10 mgd was incorporated in the CIP assumptions for the Master Plan.


ES-6 DECEMBER 2011

ES-5 Water Distribution System Improvements to the existing water distribution system were determined by evaluating the existing facilities and future conditions using a hydraulic model. The flow projections were applied to the model and a Capital Improvement Plan (CIP) was developing utilizing System Performance Criteria. Projects were identified for each of the plan years (Base Year, 2015, 2020, and 2030).

ES.5.1 Supply and Treatment Facilities

The Union County water distribution system is supplied from two water treatment/supply facilities, the CRWTP and the Anson County WTP via the supply interconnection with Anson County at the Highway 74 Pump Station. Water from the CRWTP serves about 75% of the system (in the Catawba and Yadkin Basins) and Anson WTP serves the remaining 25% of the system (in the Yadkin Basin only).

Based on the demand projections for the existing pressure zones in the Catawba and Yadkin Basins supplied by the CRWTP, the capacity of the CRWTP will be exceeded in 2014 thus requiring an expansion of that facility. To help defer the timeline for the expansion, Union County is currently pursuing the purchase or lease of 2 mgd of treatment capacity from Lancaster County’s capacity allocation in the CRWTP and continuing the demand management strategies, as needed, to limit maximum day systems demands until the CRWTP is expanded.

Based the demand projections for the existing pressure zones in the Yadkin Basin supplied from Anson County, the contracted amount (6 mgd) from Anson County will be exceeded in 2016. The County plans to pursue required steps to increase its IBT permit to at least 10 mgd by 2017.

The analysis results are summarized in Table ES-2.

TABLE ES-2 AVAILABLE TREATMENT/SUPPLY CAPACITY

TREATMENT/SUPPLY FACILITY

WTP BASIN

TREATMENT CAPACITY

(MGD) BASE YEAR

TREATMENT CAPACITY

(MDG) AFTER 2015

MAXIMUM DAY DEMAND (MGD) TREATMENT/SUPPLY CAPACITY

SURPLUS/DEFICIT

BASE 2015 2020 2030 BASE 2015 2020 2030

CRWTP Catawba 18.0 18.0 15.1 18.8 22.8 29.3 +2.9 -0.8 -4.8 -11.3

Anson WTP Yadkin 4.0 6.0 4.1 5.9 7.1 13.0 -0.1 +0.1 -1.1 -7.0

ES.5.2 Supply and Transfer Pumping Stations

The existing water distribution system allows for water to be transferred between the basins through pumping stations. Based on the flow projections, all existing pumping stations except Watkins BPS and Waxhaw-Marvin BPS will need to be expanded.

ES.5.3 Storage Facilities

Storage facilities in a distribution system serve a number of purposes, including demand/flow equalization, fire reserve, and emergency reserve. Without storage facilities, the supply, treatment, pumping, and transmission facilities would have to be significantly larger. However, by constructing appropriately sized storage tanks at strategic locations throughout the system, the



supply and production systems are able to operate in an optimized manner thus reducing operation and minimizing.

Based on the flow projections and the performance criteria, additional storage is needed to adequately meet future system pressure requirements as well as future fire and emergency need.

ES-6 Wastewater Collection System Using the flow projections, hydraulic modeling was performed for each major sewer sheds with the exception of the Six Mile Basin as CMU is responsible for capacity assessment of the Six Mile Interceptor. The performance criteria were adjusted slightly to allow for some surcharging of sewers. Using the results of the hydraulic modeling and the adjusted performance criteria, the CIP was developed for the collection system.

ES.6.1 Twelve Mile WRF and Collection System

Twelve Mile WRF is projected to be the primary wastewater treatment facility for the County. The Master Plan leverages the existing investments in this facility and recommends two additional 3 mgd capacity expansions over the planning horizon; from 6 mgd to 9 mgd and then again from 9 mgd to 12 mgd. Permit applications have been prepared to secure the necessary approvals for expansion through 12 mgd. Other WRF improvements included in the CIP are for previously identified digester heat exchange upgrades and beneficial re-use of treated effluent.

The Twelve Mile Diversion PS and Force Main project will provide the WRF headworks the ability to pump a portion of the flow from the facility north via force main to the Six Mile Interceptor. This allows Union County to maximize the existing contract with CMU.

Investments in this facility recognize that the IBT strategy must maximize Catawba River discharge of treated effluent. The WRF capacity assessment incorporates the understanding of an expanded Poplin Rd PS flows being pumped over from the eastern portion of the County to minimize the quantity of flow transferred from the Catawba River to the Yadkin/Pee Dee River basin.

ES.6.2 Crooked Creek WRF and Collection System

The long term vision for this service area is that the Crooked Creek WRF will serve the wastewater service area tributary by gravity to this facility. Forest Park PS will be the primary major pumped conveyance to this facility through the 2030 planning horizon. Crooked Creek WRF is projected to remain at its current 1.9 mgd capacity through 2030 as a result.

Improvements are required at the Crooked Creek WRF to address existing and projected peak wet weather flow. The Master Plan recommends that the pumping capacity of the headworks be increased by 8 mgd and a new 1 million gallon equalization (EQ) basin be constructed to store excess wet weather flow. Provisions should also be made at the headworks facilities to enable a portion of the flow to be pumped to the Poplin Rd force main for conveyance to the Twelve Mile WRF.

ES.6.3 Six Mile Basin

The County has an agreement in place with CMU to secure up to 3 mgd of capacity at the McAlpine WWTP and this option is being exercised.


ES-8 DECEMBER 2011

ES.6.4 City of Monroe WWTP and Tributary Improvements

As a result of the development anticipated with the Monroe Bypass service area and in general on the eastside, the projected County wastewater flows going to the Monroe WWTP will double over the planning period to a total of 5.3 mgd max month flow. An equity partnership needs to be pursued with the City of Monroe to advance a financially responsible relationship with the City for both the additional capacity that is needed and to accommodate the connections to the existing City gravity collection system. The Leadership Team directed staff to develop planning based on the County becoming an equity partner with the City of Monroe at their existing WWTP or at a new treatment plant located along Richardson Creek. Alternatives for both the treatment capacity and wastewater conveyance are available should that partnership not materialize.

ES.6.5 Local Wastewater Treatment Plants

The Olde Sycamore, Tallwood and Grassy Branch WWTP’s tributary collection systems were not hydraulically modeled or evaluated as a part of this planning. There are several existing projects identified from previous planning for the local treatment plants that are captured in this CIP. Hunley Creek WWTP has not been in service for several years, is recommended to be decommissioned. The Tallwood WWTP is recommended to be entirely replaced.

ES.6.6 Community Outreach and New Wastewater Service

The major community outreach issues and tentative solutions have been captured in CIP projects with a planning schedule. The community outreach CIP solutions are included in a category of CIP projects described as “service enhancements.” While some of these projects are actually enhancements to existing wastewater service provided in some manner, the common element for each of these projects is that they require a funding source and an agreed upon schedule to implement.

ES-7 Recommended Capital Improvement Plan Based on the service area projections and the system evaluations and assessments, needed capacity and system improvements for existing and future system conditions were identified and prioritized and compiled into a Capital Improvement Plan (CIP) for the 20-year planning horizon. The CIP is based on an assumption of an IBT increase from 5 mgd to 10 mgd granted by the State by 2017.

System improvement projects are categorized as water supply/treatment projects, wastewater treatment/disposal projects, water distribution projects, or wastewater collection projects. A project identification (ID) system defines the project location and type. A color coding system helps illustrate the project priority and timeframe. An assessment of whether an improvement project is needed to accommodate system expansion for growth versus whether the improvement project is needed to address deficiencies in the existing system is provided. Construction and engineering cost estimates are shown and distributed to appropriate future years to provide a fiscal year cash flow projection. The assumptions and criteria used to estimate project costs are described below. The entire water and wastewater CIP, including project cost information, is detailed in tabular format in the Master Plan. Individual figures illustrating the water and wastewater CIPs are also provided in the Plan.



ES-8 Project Costing Criteria In general, the planning level construction and engineering costs provided in the CIP are based on experiences with recent similar projects. Unit construction costs were developed for the purpose of establishing planning level project costs. These unit costs were derived and averaged over a range of potential site conditions from utility construction experience in North Carolina, selected site contract estimates for specific contracts, and other Master Plan unit costs.

A construction contingency of 20% and engineering allowance of 15% was included for all projects.

The total cost of the CIP by type of expenditure by planning year is summarized in Figure ES-3. All costs shown are in 2011 dollars.

Figure ES-3 CIP Summary

$0 $10 $20 $30 $40 $50 $60 $70 $80 $90

$100

Mill

ions

of 2

011

Dol

lars

Year

Treatment Water Infrastructure Wastewater Infrastructure

Documents

COMPREHENSIVE WATER WASTEWATER MASTER PLAN · 2020-03-13 · wastewater master plan final report b&v project no. 167797 contact name: jeffrey d. coggins company name: black & veatch