Planning for a Greenfield Water Resource Recovery Facility

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

mathurss@cdmsmith.com

Donna Long, PE(469) 626 4719

dlong@ntmwd.com