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WEAT - NTS February Seminar 2020
February 18, 2020
Planning for a Greenfield
Water Resource Recovery Facility
to Meet 50 Years of Growth and Beyond Donna Long, PE
Samir Mathur, PE
Outline
• Project Drivers
• Treatment Process Alternatives Evaluation
• Site Planning
• Current Schedule and Status
Project Drivers
NTMWD Service Area Population and Flow Projections
Population Projection
Flow Projection
Wilson Creek RWRRF cannot be expanded beyond 64 mgd
New RWRRF Phasing Considerations
Sister Grove Regional Water Resource Recovery Facility
REVIEW OF OVERALL PROJECT OBJECTIVES
Parameter Phase I Phase II Phase III Phase IV
16
64
Annual
Average
Daily Flow
(AADF),
MGD
Peak Flow,
MGD
32 48 64
128 192 256
Goal: Phase 1 Facilities fully
operational by April 2023
TCEQ Permit
New RWRRF Phasing Considerations
Treatment Process Alternatives Evaluation
Influent Wastewater Characteristics
Parameter
Average Flow
and Loading
Maximum
Month Flow
and Loading
Maximum
Month
Factors
Flow, MGD 16 21 1.3
BOD, lbs/day (mg/L) 29,360 (220) 36,700 (210) 1.25
NH3-N, lbs/day (mg/L) 4,003 (30) 4,804 (27.5) 1.2
TSS, lbs/day (mg/L) 29,360 (220) 38,170 (218) 1.3
P, lbs/day (mg/L) 801 (6) 961 (5.5) 1.2
Permit Limits
Parameter
Annual
Average
(mgd)
Pollutant Effluent Limits
CBOD5 (mg/L)TSS
(mg/L)
NH3-N (mg/L)Total P*
(lbs/yr)
Total P
(mg/L)
DO
(mg/L)
E. coli, CFU
or MPN
per 100 mlSummer
(Apr-Sep)
Winter
(Oct-Mar)
Summer
(Apr-Sep)
Winter
(Oct-Mar)
Interim I 16 5 10 5 1.3 3 53,576 1.10 6.0 126
Interim II 32 5 10 5 1.7 3 50,654 0.52 6.0 126
Interim III 48 5 10 5 1.5 2 49,679 0.34 6.0 126
Final Phase 64 5 10 5 1.2 2 48,706 0.25 6.0 126
* The daily mass loadings calculated for each day of the month shall be summed to determine the total pounds of total phosphorus discharged during the calendar month. The total monthly
and rolling annual mass loadings shall be reported on a monthly basis.
Treatment Process Alternatives Evaluations –
Process Evaluation Methodology
• Screen potential alternatives for key treatment processes
– Liquids, Headworks, Peak Flow Handling, Disinfection, and Solids
• Identify 2 to 3 most preferred alternatives for further evaluation
• Reconvene to discuss most preferred alternatives in detail, and select one process
for the new RWRRF
• Task Outcome/Deliverable
– Documentation of process selection methodology
– Preliminary PFD for new RWRRF
Headworks Alternatives
Selected Alternative:
• Influent Screens
– Step Screens
– No coarse screening
• Grit Removal
– Free Vortex (Headcell)
– Flooded suction pumping
– Grit cone washer
• Use one common belt
conveyor to convey
screenings and grit to
dumpster
Peak Flow Handling Alternatives
Selected Alternative:
• Peak Flow Basins
– Provide 32 MG Basins (adequate for Phase II)
– Volume based on 5 year storm followed by 2 year storm
Benefits:
• Lower Cost option
• Ability to contain plant upsets
• Operational and construction flexibility
• Could offer relief to Wilson Creek during rehabilitation
Liquid Treatment Alternatives
Selected Alternative:
• Primary Clarifiers - Provide Two Primary Clarifiers
• Biological Process - Plug Flow Activated
Sludge with Step Feed Capability
• Secondary Clarifiers - Provide Two
Secondary Clarifiers
Tertiary Filtration Alternatives
Selected Alternative:
• Cloth Media Filters
– Lower life cycle cost
– Extensive NTMWD operating experience
– Only outside in-type filters were considered
– Preselection recommended
Disinfection Alternatives
Selected Alternative:
• UV Disinfection
– Considering only vertical or inclined
systems
– Design dose conservative and same
as that recently used for Wilson
Creek and South Mesquite
– Preselection recommended
• Differences in structural and
electrical sizing requirements
amongst manufacturers
Solids Treatment Alternatives
Selected Alternative:
• Thickened Primary Sludge Storage Tank
– Pumped Mixing System
• WAS Storage Tank
– Blowers for aeration
– No WAS Thickening in Phase 1 because the system is solids limited
• Blend Tank
– Pumped Mixing System
• Dewatering Centrifuges
– Emulsion Polymer
• Cake Storage Silo
– Screw Conveyors to convey the cake
Solids Treatment Schematic
Thickened Primary
Sludge
To
Landfill
Blend/
Storage
Tank
WAS
Combined
Sludge
Primary
Clarifier
Influent
WW
WAS
Pump
Station
Dewatering
Building
Polymer
System
TPS
Pump
Station
WAS
Future
Cake
Storage
Dewatered
Sludge
Site Planning
Site Planning
• Phase 1 and Long-Range Site Planning
– Plant Hydraulic Profile and Site Grades
– Full Buildout and Phase 1 Site Layouts
– Site Utility Corridors Master Planning
– Utility Availability
Hydraulic Grade Line
El 650
El 640
El 640
Southward
Sloping
Ridgeline
El 630El 630
Site Layout to
Phase IV (64
MGD)
Site Utility Corridors Master Planning
Dedicated corridors for:
• Electrical/Communications
(20’ N/S & 50’ E/W)
• Potable Water (10’)
• Plant (Non-Potable) Water (10’)
• Sludge/filtrate/Drains (20’)
• Equalization Pipelines/Drains (30’)
Consistent positioning of corridors relative
to N/S and E/W roads and consistent range
of depths by utility type
Utility Availability
• Natural Gas – Not available
• Electrical
• Potable Water
– New potable water connection from North Collin SUD
Site Utilities
Availability –
Electric Power
Site Utilities
Availability –
Potable
Water
Current Schedule and Status
2016 2017 2018 2019 2020 2021 2023
Project
Start
Plant Final
Design/
Pipeline Prelim
Design Start
Pipeline
100%
Design
Final
Completion
TWDB Environmental
Review
Substantial
Completion
2022
ConstructionPermitting
Plant
100%
Design
Plant
Preliminary
Design Start
Pipeline
Final
Design
Start
Planning Design
Questions?
Samir S. Mathur, PE(214) 346 2800
Donna Long, PE(469) 626 4719
