3-REQ-0007862 Alternatives Evaluation.pdf

Alternatives Evaluation for SFE Pump Station Capacity and Treatment

Revision: Final

Rehabilitation of the SFE Pump Station Contract Number: 2000970

July 2022

Alternatives Evaluation for SFE Pump Station Capacity and Treatment

PPS0331221027DET

Client name: NORESCO for the Great Lakes Water Authority

Project name: Rehabilitation of the SFE Pump Station

Client reference: Contract Number: 2000970 Project no: C6A18000

Document no: PPS0331221027DET Project manager: Allen Gelderloos, P.E.

Revision no: Final Prepared by: Jacobs

Date: July 5, 2022 File name: GLWA_Rehab_SFE_Pump_Station_Rep ort_FINAL

Document history and status

Revision Date Description

Draft April 2022 Alternatives Evaluation for SFE Pump Station Capacity and Treatment

Final July 5, 2022 Alternatives Evaluation for SFE Pump Station Capacity and Treatment

Jacobs Consultants, Inc.

30800 Telegraph Road Suite 4900 Bingham Farms, MI 48025-4710 United States

T +1.248.633.1440 www.jacobs.com

Copyright Jacobs Consultants, Inc. @ 2022.

All rights reserved. Reproduction and redistribution without written permission is prohibited. Jacobs, the Jacobs logo, and all other Jacobs trademarks are the property of Jacobs Engineering Group Inc.

NOTICE: This document has been prepared exclusively for the use and benefit of Jacobs’ client. Jacobs accepts no liability or responsibility for any use or reliance upon this document by any third party.

PPS0331221027DET ii

Executive Summary

Overview

The Screened Final Effluent (SFE) Pump Station (PS) at the Detroit Water Resource Recovery Facility (WRRF) pumps secondary effluent to various uses. The existing SFE PS was constructed in about 1970, and the majority of the pumps are original to the PS. There are eight vertical turbine pumps, with a total installed pumping capacity of about 180 million gallons per day (mgd). Current average SFE usage is about 24 mgd, with a maximum daily usage of 38 mgd over the past 3 years. Uses of SFE water include incinerator scrubber water, biosolids dryer scrubber water, belt filter press wash water, elutriation water for gravity thickeners, and other various process and washdown uses.

The WRRF also uses a large amount potable water at a significant annual cost to GLWA. (After potable water from the water main along Jefferson Avenue goes through backflow preventers or air gap tanks on the WRRF site, the water is considered non-potable water, or secondary water [SW], which is the term used in this report). Providing treatment for SFE and replacing SW with treated SFE has been identified as both a cost saving measure and a means to provide resiliency in case of a water main failure. Several existing SW uses have been identified for replacement with treated SFE, including:

▪ Chlorine Gas (Cl2) Injector Water. This water is used to carry the Cl2 solution from the Chlorination Facility to the point of disinfection just downstream of the existing SFE PS. SW water usage is currently about 1,200 gallons per minute (gpm) (1.7 mgd) average and 1,500 gpm (2.2 mgd) peak.

▪ Sulfur Dioxide (SO2) Injector Water. This water is used to carry the SO2 solution from the Dechlorination Facility to the point of dechlorination in the Detroit River Outfall (DRO). SW usage is currently about 600 gpm (0.9 mgd) average and 900 gpm (1.3 mgd) peak.

▪ Low-Pressure Secondary Water (LPSW). LPSW is potable water that has gone through a backflow preventer to isolate it from the potable water distribution system. It is distributed at water distribution system pressure. The average LPSW usage is approximately 1.65 mgd. Reported LPSW uses include:

- Pump seal water

- Wash down water

- Flushing water

- Hose bibs

- Fire protection

- Dry ash handling

- Boiler make-up

- Polymer make-down (dilution)

▪ Intermediate- and High-Pressure Secondary Water (IPSW and HPSW). IPSW and HPSW are potable water that has gone through an air gap tank to isolate it from the potable water distribution system and then has been pumped to the desired pressure. Average IPSW and HPSW usages are approximately 0.7 and 0.3 mgd, respectively.

Reported IPSW uses include:

- Complex II Incineration – pump seal water, flushing, cooling

- Sludge dewatering complexes – pump seal water, flushing, cooling water

Reported HPSW uses include:

- Sludge dewatering complexes – fire protection, operations flushing, cooling, belt filter press wash water (backup to SFE)

- Complex II Incineration – various operations, including incinerator mist eliminators

▪ Rouge River Outfall (RRO) Hypochlorite and Bisulfite Mixing Water. The RRO Disinfection Facility was constructed with the capability to add either SFE or SW to the hypochlorite and bisulfite feed lines to

PPS0331221027DET iii provide adequate dispersion of chemical at the feed point. Currently, the plant uses SW. There are no physical modifications needed for the plant to use SFE at this location. During wet weather events when the RRO is used, the SFE usage would be about 2.0 mgd.

Project Objectives

This project is intended to accomplish the following objectives:

▪ Replace the existing SFE PS with a new pump station. The new PS will be “right-sized” to meet the current and anticipated future SFE demands, and reduce energy costs.

▪ Increase WRRF resiliency to a potable water main failure using treated SFE as a primary source of SW water, with potable water as a readily available backup.

▪ Reduce WRRF operating costs by providing treatment to a portion of the SFE flow to make it suitable to replace SW uses throughout the WRRF.

SFE Pump Station Alternatives and Recommendations

Based on a review of existing and proposed SFE uses, the proposed SFE PS will have 60-mgd firm capacity (i.e., capacity with largest unit out of service). The proposed PS will be located north of the existing PS location. Based on the alternatives evaluated in this report, the PS will be located over the secondary effluent channels and use vertical turbine pumps, similar to the existing PS. The proposed placement of pumps will position half of the pumps in the East Effluent Channel and half in the West Effluent Channel to allow one of these channels to be taken out of service, if necessary, and maintain current maximum day SFE supply.

Through modeling of the SFE distribution system and detailed investigation of SFE uses, Jacobs determined that the critical pressure within the system is the quench sprayer water for each Complex II (C-II) incinerator. Additional investigation determined that providing booster pumps for this flow can reduce the SFE system pressure by about 27 pounds per square inch (psi). This change improves the project economics significantly.

SFE Treatment Alternatives Evaluation

The following paragraphs present the evaluation of issues and identified alternatives for each SW use.

Chlorine injector water. At the start of this project, it was discovered that the ammonia and organic nitrogen in the secondary effluent (injector water) would react with the chlorine gas to produce tricloramine (NCl3), which could cause hazardous conditions in the chlorine carrier pipes. If secondary effluent is used for chlorine carrier water, treatment using breakpoint chlorination (BPC) and advanced water treatment (AWT) of microfiltration (MF) and reverse osmosis (RO) is required to remove the ammonia and organic nitrogen prior to chlorine addition. An alternative to AWT is either to continue using SW for carrier water or to switch from chlorine gas to an alternate disinfectant, such as sodium hypochlorite. The alternatives for chlorine carrier water and backup provisions are summarized in Table

ES-1.

PPS0331221027DET iv

Table ES-1. Identified Alternatives for Chlorine Injector Water

Alternative Description Primary Source for Chlorine Injector Water

Backup Source for Chlorine Injector Water

Continued Use of

Chlorine Gas and Use

Treated SFE for Injector

Water

SFE treated by BPC and AWT (see

Section 4.6.4)

SW

Continued Use of

Chlorine Gas and

Continued Use of SW for

Injector Water

Continued use of SW No backup for injectors. Rather, sodium hypochlorite feed from

RRO Disinfection Facility to existing chlorine feed location

(See Section 3.3.2.2) used as backup to chlorine solution feed

Continued Use of

Chlorine Gas and

Continued Use of SW for

Injector Water

Continued use of SW Water storage tank for backup injector water (See Section 3.3.1)

Switch from Chlorine Gas to Alternate Disinfectant

No chlorine injector water needed.

Sodium hypochlorite provided by an expanded RRO Disinfection Facility

(See Section 3.3.2.1)

Backup to be determined, if alternate disinfection is selected alternative

Sulfur Dioxide Injector Water. The proposed alternative source of this water is from the DRO access shaft near the Dechlorination Facility and immediately upstream of sulfur dioxide addition. Other than strainers, no additional treatment is needed. SW will serve as the backup water supply.

LPSW. The proposed alternative low-pressure water supply will serve the current uses (listed above) except for boiler make-up and polymer make-down. Based on the need to maintain higher water quality for process performance reasons, the boiler make-up and polymer make-down will be served from the alternative high-pressure water supply, or they will be connected to the SW system.

The proposed treatment of SFE for LPSW supply includes filtration, sodium hypochlorite addition to form chloramines, and alkalinity addition. The primary and backup source waters for LPSW are presented in Table ES-2.

Table ES-2. Alternatives for LPSW

Alternative Description Primary Source Water Backup Source Water

LPSW SFE treated by filtration, sodium hypochlorite addition to form chloramines and alkalinity addition

SW

IPSW. The IPSW and HPSW are currently part of the same SW system that starts at the air gap tanks and booster pumps. Based on the reported uses of IPSW; however, the proposed level of treatment of SFE for the IPSW is the same as that for LPSW. The HPSW, however, requires a higher level of treatment. As such, the LPSW and IPSW treatment system will be combined and will include filtration, chlorination, and alkalinity addition. The primary and backup source waters for IPSW are presented in Table ES-3.

PPS0331221027DET v

Table ES-3. Alternatives for IPSW

Alternative Description Primary Source Water Backup Source Water

IPSW SFE treated by filtration, sodium hypochlorite addition to form chloramines and alkalinity addition

SW

HPSW. Most of the HPSW uses, in particular the incinerator mist elimination system, require higher water quality than the treatment to be provided for the LPSW and IPSW. Based on these uses, the proposed treatment for HPSW should produce water similar to the potable water. SFE treatment for HPSW includes BPC for ammonia removal, MF, RO, chemical conditioning, and sodium hypochlorite addition to form free chlorine for biofouling control. The MF and RO is considered AWT.

Based on the high cost of AWT, an alternative is to continue to use SW as the primary water source. Under this alternative, the emergency backup source of water would be SFE treated by the same treatment system used for the LPSW and IPSW systems, with slightly higher capacity for the HPSW flow.

The primary and backup source water alternatives for HPSW are presented in Table ES-4.

Table ES-4. Alternatives for HPSW

Alternative Description Primary Source Water Backup Source Water

HPSW with AWT SFE treated by BPC, MF, RO, chemical conditioning, and sodium hypochlorite addition to form free chlorine

SW

HPSW with Continued Use of SW Continued Use of SW SFE treated by filtration, chlorination and alkalinity addition (combined with LPSW and IPSW treatment system)

Table ES-5 summarizes the primary and backup water sources for each use, except sulfur dioxide carrier water, which is the same for all alternatives.

PPS0331221027DET vi

Table ES-5. Summary of Primary and Backup Water Sources

Alternative No.

Secondary Effluent Disinfection

Chlorine Injector Water LPSW/IPSW HPSW

Primary Source Backup Source Primary Source Backup Source Primary Source Backup Source

Continued Use of Chlorine

Gas

SFE treated with BPC and AWTa (combined with HPSW AWT) SW

SFE treated with Filtrationb

SW

SFE treated with BPC and AWT SW

2 SFE treated with BPC and AWT SFE Treated with Filtration

(combined with HPSW backup) Continued Use of SW Filtrationc

Continued Use of SW Hypo from RROd

SFE treated with Filtration SFE treated with BPC and AWT SW

SFE treated with Filtration

(combined with HPSW backup) Continued Use of SW Filtration

Continued Use of SW

Storage Tanke

SFE treated with Filtration SFE treated with BPC and AWT SW

SFE treated with Filtration

(combined with HPSW backup) Continued Use of SW Filtration

Alternate Disinfectant

(Eliminate Chlorine Gas)

If sodium hypochlorite, SFE (untreated) for mixing.

Backup to be determined, if alternative is selected

SFE treated with Filtration SFE treated with BPC and AWT SW

SFE treated with Filtration

(combined with HPSW backup) Continued Use of SW Filtration

Notes:

a AWT includes MF and RO and chemical stabilization.

b Filtration for the LPSW/IPSW includes media filters, sodium hypochlorite addition to form chloramines, and alkalinity adjustment.

c Filtration for the HPSW involves the same treatment system as the LPSW/IPSW, with additional capacity to supply the HPSW.

d “Hypo from RRO” involves connecting a new hypochlorite feed line from the RRO Disinfection Facility to the existing chlorine solution line to allow sodium hypochlorite to replace the chlorine solution in a backup situation.

e “Storage Tank” involves construction of an SW storage tank to supply injector water in a backup situation.

PPS0331221027DET vii

Contents

Executive Summary ........................................................................................................................................................... ii

Acronyms and Abbreviations .......................................................................................................................................... x

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

1.1 Project Overview and Objectives ..................................................................................................................... 1-1

1.2 Alternative Evaluations in this Report ........................................................................................................... 1-2

2. SFE Pump Station Alternatives Evaluation .................................................................................................. 2-1

2.1 Existing SFE System ............................................................................................................................................. 2-1

2.1.1 SFE Pump Station..................................................................................................................................... 2-1

2.1.2 SFE Distribution System ........................................................................................................................ 2-3

2.1.3 Evaluation of Historical SFE Usage ................................................................................................... 2-5

2.1.4 Evaluation of SFE Distribution System Pressure Requirements ............................................ 2-9

2.2 Projected SFE Usage and Pump Station Capacity ................................................................................. 2-13

2.3 Alternatives Evaluation for SFE Pump Station ........................................................................................ 2-15

2.3.1 Pump Station Location Alternatives .............................................................................................. 2-15

2.3.2 Pump Type Alternatives ..................................................................................................................... 2-19

2.3.3 Addition of Booster Pumps to Reduce SFE Distribution System Pressure ..................... 2-21

2.3.4 Pump Capacity and Drive Alternatives ......................................................................................... 2-22

2.3.5 Ancillary Systems .................................................................................................................................. 2-26

2.3.6 Summary of Recommended SFE PS Alternative ...................................................................... 2-26

3. Disinfection Alternatives.................................................................................................................................. 3-1

3.1 Overview ................................................................................................................................................................... 3-1

3.2 Alternative Disinfection Approaches – Rouge River Outfall Evaluation .......................................... 3-1

3.3 Alternative Disinfection Approaches – Wastewater Master Plan Evaluation ................................. 3-2

3.3.1 Gas Chlorine ............................................................................................................................................... 3-2

3.3.2 Delivered Sodium Hypochlorite ......................................................................................................... 3-3

4. SFE Treatment Alternatives Evaluation........................................................................................................ 4-1

4.1 Overview ................................................................................................................................................................... 4-1

4.2 Chlorine Injector Water Supply ........................................................................................................................ 4-3

4.2.1 Description of Existing Chlorination Facilities .............................................................................. 4-3

4.2.2 Proposed Alternative Water Supply .................................................................................................. 4-4

4.3 Sulfur Dioxide Injector Water Supply ............................................................................................................ 4-6

4.3.1 Description of Existing Dechlorination Facilities ......................................................................... 4-6

4.3.2 Proposed Alternative Water Supply .................................................................................................. 4-7

4.4 Low-Pressure Water Supply .............................................................................................................................. 4-7

4.4.1 Existing Water Supply ............................................................................................................................. 4-7

4.4.2 Proposed Alternative Water Supply .................................................................................................. 4-9

4.5 Intermediate- and High-Pressure Water Supplies ................................................................................ 4-11

PPS0331221027DET viii

4.5.1 Existing Water Supply .......................................................................................................................... 4-11

4.5.2 Treated SFE Requirements for Fire Protection .......................................................................... 4-12

4.5.3 Proposed Alternative Supplies ........................................................................................................ 4-12

4.6 SFE Treatment Alternatives Evaluation ..................................................................................................... 4-13

4.6.1 SFE Pumping to SFE Treatment ...................................................................................................... 4-13

4.6.2 Ammonia Removal ............................................................................................................................... 4-13

4.6.3 Media Filtration ...................................................................................................................................... 4-21

4.6.4 High-Pressure Secondary Water ..................................................................................................... 4-34

4.7 Preliminary SFE PS and Treatment System Site Layout ..................................................................... 4-44

5. References ........................................................................................................................................................... 5-1

Appendices

Appendix A. SFE Hydraulic Model Review and Calibration Technical Memorandum

Appendix B. Pump Performance Curves

Tables

Table 2-1. Existing SFE Pump Information ........................................................................................................................... 2-1 Table 2-2. Flow Correction Factors .......................................................................................................................................... 2-5 Table 2-3. Current SFE Usage by Use and Location .......................................................................................................... 2-8 Table 2-4. SFE System Pressures with Constraint of 50 psi for Complex II Incineration Quench Sprayer 2-10 Table 2-5. SFE System Pressures with Constraint of 40 psi for Complex II Incineration Booster Pumps . 2-11 Table 2-6. Current and Projected SFE Usage by Use and Location .......................................................................... 2-14 Table 2-7. Comparison of Advantages and Disadvantages for Vertical Turbine Pumps and Submersible Pumps ............................................................................................................................................................................................... 2-20 Table 2-8. Design Information for Complex II Incineration Quench Water Booster Pumps ........................... 2-21 Table 2-9. SFE PS Alternative Pump Combinations ....................................................................................................... 2-22 Table 2-10. System Head Conditions for New SFE Pump Station with Quench Water and Boosted Quench Water ................................................................................................................................................................................................. 2-23 Table 2-11. Comparison of Energy Costs for Alternatives – With Quench Water ............................................... 2-24 Table 2-12. Comparison of Energy Costs for Alternatives – With Boosted Quench Water ............................. 2-24 Table 2-13. Comparison of Present Value Costs for SFE PS Alternatives – With Quench Water .................. 2-25 Table 2-14. Comparison of Present Value Costs for SFE PS Alternatives – With Boosted Quench Water 2-25 Table 3-1. Sodium Hypochlorite Requirements for RRO Disinfection, DRO Disinfection, and BPC ............... 3-4 Table 3-2. Sodium Hypochlorite Storage Based on Chemical Concentration and Storage Volume ............. 3-4 Table 4-1. Historical Secondary Effluent Characteristics ................................................................................................ 4-3 Table 4-2. Intermediate-and High-Pressure Secondary Water Flows (Hourly Data from May 1, 2020, to November 12, 2021) .................................................................................................................................................................. 4-12 Table 4-3. Design Criteria for Breakpoint Chlorination Facility ................................................................................. 4-18 Table 4-4. Media Filtration Facility Design Criteria and Construction Cost .......................................................... 4-27 Table 4-5. Comparison of Filter Options............................................................................................................................. 4-33 Table 4-6. Microfiltration and Reverse Osmosis Design Criteria and Footprint .................................................. 4-38 Table 4-7. Permeate Storage Tank, and Permeate Pump Station Design Criteria and Footprint ................ 4-40

PPS0331221027DET ix

Figures

Figure 2-1. Plan View of the Existing SFE Pump Station (from SFE Standard Operating Procedure Manual) ................................................................................................................................................................................................................ 2-2 Figure 2-2. Schematic of the Existing SFE Pump System................................................................................................ 2-3 Figure 2-3. SFE Yard Piping......................................................................................................................................................... 2-4 Figure 2-4. Historical SFE Daily Flows for 3-Year Period ................................................................................................ 2-5 Figure 2-5. Frequency Plot of SFE Flows Over 3-Year Period ....................................................................................... 2-6 Figure 2-6. Hourly SFE Flows for 1-Year Period ................................................................................................................. 2-7 Figure 2-7. SFE Pump Station Discharge Pressure for 3-Year Period ..................................................................... 2-12 Figure 2-8. Pump Curve Illustrating Increased Head at Lower Flows ...................................................................... 2-13 Figure 2-9. General Location of the New SFE Pump Station and Treatment System ....................................... 2-17 Figure 2-10. Pump Station Location Alternative on Top of the Secondary Effluent Channels ..................... 2-18 Figure 2-11. Pump Station Location Alternative Beside the Secondary Effluent Channel ............................. 2-18 Figure 2-12. Example of Submersible Pump Layout ..................................................................................................... 2-19 Figure 2-13. Proposed Location for Skid-Mounted Quench Sprayer Booster Pumps ...................................... 2-21 Figure 2-14. Proposed SFE Discharge Piping and its Connection to the Existing SFE Yard Piping ............. 2-27 Figure 3-1. Possible Location of 6.5-MGD Storage Tank for Potable Water Storage .......................................... 3-3 Figure 3-2. Potential Expansion of Existing RRO Disinfection Facility for Additional Hypochlorite Storage 3- Figure 3-3. Potential Piping for Backup Hypochlorite Feed to Secondary Effluent Diffuser ............................ 3-7 Figure 4-1. Aerial View of the Key Facilities.......................................................................................................................... 4-2 Figure 4-2. Proposed Chlorine and Sulfur Dioxide Injector Water Supply ............................................................... 4-4 Figure 4-3. Secondary Water Distribution System ............................................................................................................. 4-8 Figure 4-4. Simplified Process Flow Schematic of Breakpoint Chlorination Process and Transfer Pumps .... 4- Figure 4-5. Location of Sodium Hypochlorite Transfer Pumps in RRO Facility (Process Plan)..................... 4-17 Figure 4-6. Proposed Location of Sodium Hypochlorite Transfer Pumps in RRO Facility .............................. 4-18 Figure 4-7. Cloth Disk Filter Cut-Away View ...................................................................................................................... 4-23 Figure 4-8. Cloth Disk Filter Simplified Process Flow Schematic .............................................................................. 4-24 Figure 4-9. Horizontal Pressure Filters (WesTech brochure) ...................................................................................... 4-25 Figure 4-10. Pressure Filters Simplified Process Flow Schematic ............................................................................ 4-25 Figure 4-11. Granular Media Gravity Filters Cut-Away View ....................................................................................... 4-26 Figure 4-12. Gravity Filter Simplified Process Flow Schematic ................................................................................. 4-27 Figure 4-13. Advanced Water Treatment Simplified Process Flow Schematic .................................................... 4-36 Figure 4-14. Microfiltration Skid ............................................................................................................................................ 4-37 Figure 4-15. Reverse Osmosis Trains ................................................................................................................................... 4-37 Figure 4-16. Preliminary SFE Pump Station and Treatment Layout ........................................................................ 4-45 Figure 4-17. Location of Key Facilities and Proposed Underground Pipe Routing............................................ 4-46

PPS0331221027DET x

Acronyms and Abbreviations AASI Aqua-Aerobic Systems Incorporated

ADWF average dry weather flow

AFD adjustable frequency drive

AWT advanced water treatment

AWWF average wet weather flow

BDF biosolids drying facility

BPC breakpoint chlorination

CaCl2 calcium chloride

CaCO3 calcium carbonate

CBOD5 5-day carbonaceous biological oxygen demand

Cl2 chlorine

CO2 carbon dioxide

CPES Conceptual and Parametric Engineering System

DBNPA 2,2-dibromo-3-nitrilopropionamide

DRO Detroit River Outfall

EGLE Michigan Department of Environment, Great Lakes, and Energy

FRP fiberglass reinforced plastic

ft. (ft) feet ft2 square feet gal. gallon(s) gfd gallons per square foot per day

GLWA Great Lakes Water Authority gpd gallon(s) per day gpm gallon(s) per minute

H2SO4 sulfuric acid

HP high pressure hp horsepower

HPSW high-pressure secondary water

HSC hydraulic system centers

in. inch(es)

IP intermediate pressure

IPSW intermediate-pressure secondary water

PPS0331221027DET xi lb/d pound per day

LPSW low-pressure secondary water

MBR membrane bioreactor

MF microfiltration mg/L milligram per liter mgd million gallons per day mm millimeter

N2 nitrogen gas

N2O nitrous oxide

NaHSO3 sodium bisulfite

NaOCl sodium hypochlorite

NaOH sodium hydroxide

NCl3 trichloramine

NH3-N ammonia-nitrogen

Nos. number(s)

NTU Nephelometric Turbidity unit

O&M operation and maintenance

OSG onsite generation (of sodium hypochlorite)

P&ID piping and instrumentation diagram

PDC power distribution centers

PF peak flow

PS pumping station psi pound per square inch psig pound per square inch gauge

PVDF polyvinylidene difluoride

RO reverse osmosis rpm revolutions per minute

RPZ reduced pressure zone

RRO Rouge River Outfall

SCADA supervisory control and data acquisition scfm/ft2 standard cubic feet per minute per square foot

SFE screened final effluent

SO2 sulfur dioxide

SP submersible pump

PPS0331221027DET xii

SW secondary water

TDH total dynamic head

TOC total organic carbon

TP total phosphorous

TS total solids

TSS total suspended solids

UV ultraviolet

VFD variable-frequency drive

VTP vertical turbine pump

WRP Wastewater Reclamation Plant

WRRF Water Resource Recovery Facility

PPS0331221027DET 1-1

1. Introduction

1.1 Project Overview and Objectives

The Screened Final Effluent (SFE) Pump Station (PS) pumps secondary effluent from the secondary effluent channels to various treatment processes at the Detroit Water Resource Recovery Facility (WRRF).

The SFE PS contains eight pumps that distribute water through the SFE distribution system. There are two, 600 horsepower (hp) fixed-speed pumps and six, 1,000-hp fixed-speed pumps. Uses of SFE water include incinerator scrubber water, biosolids dryer scrubber water, belt filter press wash water, elutriation water for gravity thickeners, and other various process and washdown uses.

The WRRF also uses a large amount potable water at a significant annual cost to Great Lakes Water Authority. (After potable water from the water main along Jefferson Avenue goes through backflow preventers or air gap tanks on the WRRF site, the water is considered non-potable water, or secondary water [SW], which is the term used in this report). Providing treatment for SFE and replacing SW with treated SFE has been identified as both a cost saving measure and a means to provide resiliency in case of a water main failure. Several existing non-potable and SW uses have been identified for replacement with treated SFE. These uses are listed here and further described in Sections 4.2 through 4.5.

▪ Chlorine Gas (Cl2) Injector Water. This water is used to carry the Cl2 solution from the Chlorination Facility to the point of disinfection just downstream of the SFE PS.

▪ Sulfur Dioxide (SO2) Injector Water. This water is used to carry the SO2 solution from the Dechlorination Facility to the point of dechlorination in the Detroit River Outfall (DRO).

▪ Low-Pressure Secondary Water (LPSW). LPSW is potable water that has gone through a backflow preventer to isolate it from the potable water distribution system. It is distributed at water distribution system pressure.

▪ Intermediate- and High-Pressure Secondary Water (IPSW and HPSW). IPSW and HPSW are potable water that have gone through an air gap tank to isolate it from the potable water distribution system and then pumped to the desired pressure.

▪ RRO Hypochlorite and Bisulfite Mixing Water. The RRO Disinfection Facility was constructed with the capability to add either SFE or LPSW to the hypochlorite and bisulfite feed lines to provide adequate dispersion of chemical at the feed point.

This project is intended to accomplish the following objectives:

1. Replace the existing SFE pump station (PS) with a new PS. The new PS will be “right-sized” to meet the current and anticipated future SFE demands, and reduce energy costs.

2. Reduce WRRF operating costs by providing treatment to a portion of the SFE flow to make it suitable to replace SW uses throughout the WRRF.

3. Increase WRRF resiliency to a potable water main failure through the use of treated SFE as a primary source of SW water, with potable water as an readily available backup.

The project is being delivered using a progressive design-build delivery method under two phases. Jacobs is providing design services and NORESCO is the Prime Contractor. Phase 1 will provide a 60% design and allow for NORESCO to generate a Lump Sum.

PPS0331221027DET 1-2

1.2 Alternative Evaluations in this Report

To meet the objectives listed in Section 1.1, this report contains three major alternative evaluations:

1. SFE PS alternatives: These evaluations include alternatives related to the PS location, pump type, number and capacity of pumps, and types of drives. Section 2 provides the SFE PS alternatives evaluation.

2. SFE treatment alternatives: These evaluations include alternatives to recommend the level of treatment and type of treatment for SFE to be a suitable replacement for current non-potable and SW uses throughout the WRRF. Section 4 provides the SFE treatment alternatives evaluation.

3. Alternatives to chlorine gas. For chlorine injector water, at the start of this project it was discovered that reactions of chlorine gas with ammonia and organic nitrogen in the secondary effluent would create tricloramine (NCl3), which could cause hazardous conditions in the chlorine carrier pipes. If secondary effluent is used for chlorine carrier water, advanced water treatment (AWT) using breakpoint chlorination (BPC), microfiltration and reverse osmosis (RO) is required to remove the ammonia and organic nitrogen prior to chlorine addition. An alternative to AWT is to either continue using SW for carrier water or switch from chlorine gas to an alternate disinfectant, such as sodium hypochlorite. The use of alternate disinfectants to replace chlorine gas is described in Section 3.

PPS0331221027DET 2-1

2. SFE Pump Station Alternatives Evaluation

2.1 Existing SFE System

SFE is secondary effluent that is pumped by SFE pumps from the secondary effluent channels, screened by mechanical strainers, and distributed to various processes throughout the plant. The following subsections describe the SFE PS and the distribution system.

2.1.1 SFE Pump Station

The existing SFE PS is located on top of the secondary effluent channels near the Administration Building.

There are eight vertical turbine, 2-stage pumps, with a total capacity of about 180 mgd. The existing pump information is shown in Table 2-1. The secondary effluent is screened through a strainer where suspended solids larger than 1/64 of an inch (in.) are removed. The strainers are backwashed to prevent clogging.

Currently, backwashing is manually performed by operations staff; however, an automatic backwash system had been previously installed and operational. The backwash water is returned to the effluent channel beneath the SFE PS.

A plan view of the existing SFE PS is shown on Figure 2-1 and a schematic view of the SFE pump and discharge piping is shown on Figure 2-2.

Table 2-1. Existing SFE Pump Information

Pump Nos. 1, 3, 4, 5, 7, 8 2 and 6

Manufacturer Peerless Peerless

Size/Model 32HXS 26HXS

Type Vertical Turbine Vertical Turbine

Flow, gpm (mgd) 13,000 (25.2) 10,500 (15.2)

TDH (rated), ft 185 186

Motor hp 1,000 600

Motor Voltage 4,160 4,160

Speed, rpm 885 1,180

Notes:

ft = feet gpm = gallons per minute Nos. = number(s) rpm = revolutions per minute TDH = total dynamic head

PPS0331221027DET 2-2

Figure 2-1. Plan View of the Existing SFE Pump Station (from SFE Standard Operating Procedure Manual)

SFE PUMP

(TYP.)

STRAINER (TYP.)

BACKWASH

VALVE (TYP.)

DISCHARGE VALVE (TYP.)

CHECK VALVE

(TYP.)

S F

E P

R E

S S

U R

E M

A

IN

S F

E P

R E

S S

U R

E M

B

C K

W A

S H

H E

A D

E R

BACKWASH SUPPLY

VALVE (TYP.)

B O

O S

T E

R P

U M

P R

O O

M

L E

C T

R

IC

A L B

U

IL

D

G

T

Y A

D

P

IP

Y A

D

P

IP

PPS0331221027DET 2-3

Figure 2-2. Schematic of the Existing SFE Pump System

Source: GLWA SFE Standard Operating Procedure Manual

2.1.2 SFE Distribution System

The SFE distribution system around the plant site is shown on Figure 2-3. SFE flow is monitored by two transit time flow meters, with one meter on the 60-in. main and one meter on the 48-in. main. It should be noted that the flow to the Biosolids Drying Facility (BDF) is not measured through these meters; it is separately measured at each of four processing trains within the BDF.

The major uses of SFE are at the locations listed here. Section 2.2 provides the measured or calculated flows at each location.

▪ Incineration Complex II

▪ Sludge Processing Complex A

▪ Sludge Processing Complex B

▪ Sludge Dewatering Complexes I and II

▪ BDF

▪ PS-1 - Rack and Grit Complex

▪ RRO Disinfection Facility

▪ Primary Clarifiers

FLOW INDICATOR

MANUAL VALVE

PRESSURE GAUGE

M MOTOR ACTUATOR

BUTTERFLYL VALVE

PRESSURE SWITCH

DIFFERENTIAL PRESSURE SWITCH

PRESSURE REGULATOR

HAND STRAINER

SYMBOL LEGEND

UNDERGROUND UTILITIES PLAN

SCREENED FINAL EFFLUENT

SF-YP-00

N

APPR

F

DESCRIPTIONS / REVISIONS CHK'D DATE

E D C B A

DRAWING No.

GLWA CIP No.

GLWA CONTRACT No.

RANGESECTION MAP SECTIONTOWN

MDEQ PERMIT No.

Q QQ

DRAWN BY:

CHECKED BY:

APPROVED BY:

DESIGNED BY: SEAL / STAMP

No.

FIRM NAMEFACILITY

PROJECT TITLE

WRRF

YARD PIPING AND UNDERGROUND UTILITIES

SCALE: DATE

CDM Smith Michigan Inc.

535 Griswold Street, Suite 930 Detroit, MI 48226

FEB. 2022

CAP - NOT FOR CONSTRUCTION

YP-1

(NOT USED)

YP-2

(NOT USED)

YP-3

(NOT USED)

YP-4

(NOT USED)

YP-5

(NOT USED)

YP-6

(NOT USED)

YP-7

(NOT USED)

YP-8

(SF-YP-08)

YP-9

(SF-YP-09)

YP-10

(SF-YP-10)

YP-11

(SF-YP-11)

YP-12

(SF-YP-12)

YP-13

(SF-YP-13)

YP-14

(SF-YP-14)

YP-15

(NOT USED)

YP-16

(NOT USED)

YP-17

(SF-YP-17)

YP-18

(SF-YP-18)

YP-19

(SF-YP-19)

YP-20

(SF-YP-20)

YP-21

(SF-YP-21)

YP-22

(SF-YP-22)

YP-23

(NOT USED)

YP-24

(SF-YP-24)

YP-25

(SF-YP-25)

YP-26

(SF-YP-26)

YP-27

(NOT USED)

YP-28

(SF-YP-28)

YP-29

(SF-YP-29)

YP-30

(SF-YP-30)

YP-31

(SF-YP-31)

YP-32

(SF-YP-32)

YP-33

(NOT USED)

YP-34

(NOT USED)

YP-35

(NOT USED)

YP-36

(NOT USED)

YP-37

(NOT USED)

YP-38

(NOT USED)

YP-39

(NOT USED)

YP-40

(NOT USED)

YP-41

(NOT USED)

YP-42

(NOT USED)

YP-43

(NOT USED)

YP-44

(NOT USED)

YP-45

(NOT USED)

YP-46

(NOT USED)

YP-47

(NOT USED)

YP-48

(NOT USED)

REHABILITATION OF THE SFE PUMP STATION

FIGURE 2-3: SFE YARD PIPING

PPS0331221027DET 2-5

2.1.3 Evaluation of Historical SFE Usage

Figure 2-4 shows the daily average SFE flow through the three flow meters, the 24 in., 48 in., and the 60

in. The average flow for the 3 years (from June 2018 to May 2021) varied from 15 to 38 mgd, with an average of 24 mgd. The flow data from Ovation was revised by applying the correction factors obtained from dye tests conducted by the GLWA’s Wastewater Analytics Task Force. Table 2-2 provides the correction factors for the three flow meters. Figure 2-5 provides a frequency plot of the 3-years of flow data. Figure 2-6 provides hourly data to illustrate the relatively limited fluctuations in SFE flow data on a daily basis.

Table 2-2. Flow Correction Factors

Time Period 24 in. Flow Meter 48 in. Flow Meter 60 in. Flow Meter

June 2018 to April 2020 1.0000a 0.9585 0.9958

May 2020 to October 2021 1.1560 0.9844 1.1560 a Correction factor of 1.0000 was determined to be from May 2019 to April 2020. The same correction factor is assumed for the t ime June 2018 to April 2019.

Figure 2-4. Historical SFE Daily Flows for 3-Year Period

PPS0331221027DET 2-6

Figure 2-5. Frequency Plot of SFE Flows Over 3-Year Period

PPS0331221027DET 2-7

Figure 2-6. Hourly SFE Flows for 1-Year Period

PPS0331221027DET 2-8

Table 2-3 details the current SFE usage by use and location.

Table 2-3. Current SFE Usage by Use and Location

SFE Use Typ No. of Units In Service Total No. of Units Flow per Unit, gpm Typical SFE Usage, gpm Source of Flow Information

C-II Incineration Scrubber Water 4 8 2,120 8,480 Scrubber manufacturer P&ID; review of SCADA

C-II Incineration Strainer Backwash -- -- -- 400 5% of C-II Incineration Scrubber Water

Complex A Thickener Make-Up Water 4 6 600 2,400 Site observation and O&M staff input

Complex B Thickener Make-Up Water 4 6 600 2,400 Site observation and O&M staff input

BDF Scrubber Water 3 4 600 1,800 90 percentile of flow rate for each train from SCADA data

C-I BFP Washwater 0 10 100 0 From BFP manufacturer specs

C-I BFP Conveyor Washwater 0 1 50 0 Estimated usage

C-II BFP (Upper Level) Washwater 6 12 100 600 From BFP manufacturer specs

C-II (Dewater and Incin) Conveyor Washdown 4 6 100 400 Estimated usage

C-II BFP (Upper Level) Strainer Backwash -- -- -- 30 5% of C-II Dewatering Washwater

PS 1 Rack and Grit -- -- -- 60 2 hose bibs for typical usage; Grit Channel flushing for max. usage

C-II Incineration Wet Ash Booster Pump 0 1 1,600 0 Wet ash has not been used in 10 years; Incinerator Ash Study recommended maintaining

Primary Tank Cleaning -- -- -- 0 Based on 3 hoses at 600 gpm each

SFE PS Strainer Backwash -- -- -- 840 5% of Current Use Flow

Subtotal of Current Uses, gpm

17,410

Subtotal of Current Uses, mgd 25.1

Notes:

No. = number

O&M = operation and maintenance

P&ID = piping and instrumentation diagram

SCADA = supervisory control and data acquisition

PPS0331221027DET 2-9

2.1.4 Evaluation of SFE Distribution System Pressure Requirements

In collaboration with the ongoing WRRF Yard Piping Upgrades project, a hydraulic model of the SFE distribution system was updated, verified, and calibrated to existing conditions under this SFE PS project.

Appendix A provides a description of the hydraulic model investigation.

Jacobs and Applied Science, Inc. investigated minimum pressure requirements for SFE uses throughout the WRRF. The pressure requirement of 50 pound per square inch (psi) for the Complex II Incineration quench sprayers (located on the fourth floor of the building) is the controlling pressure requirement.

Table 2-4 presents pressures at various locations throughout the plant and various SFE PS flow scenarios (i.e., minimum, average and anticipated design capacity). As shown, to meet the 50 psi quench water pressure requirement, the SFE header pressure at the existing SFE PS location must be at least 94 psi.

The next highest-pressure requirement in the SFE distribution system is 40 psi at the inlet of the existing booster pumps on the first floor for each venturi scrubber in Complex II Incineration. Table 2-5 presents pressures in the SFE distribution system when the constraint of 40 psi is applied at this location. As shown, the pressure at the quench sprayer is less than the required 50 psi because it is assumed that this flow would be boosted using new booster pumps. Jacobs and NORESCO recognize that significant energy and cost savings could be obtained if the quench sprayer water could be separately boosted to meet the 50 psi requirement, while the remaining SFE distribution system meets the 40 psi requirement for the Complex II Incineration booster pumps. To meet the 40 psi pressure requirement, the header pressure at the existing SFE PS must be at least 67 psi, which is about 27 psi less than current conditions of at least 94 psi. The addition of booster pumps for quench water is further discussed in Section 2.3.3.

PPS0331221027DET 2-10

Table 2-4. SFE System Pressures with Constraint of 50 psi for Complex II Incineration Quench Sprayer

Scenario

Total

SFE

Flow at

SFE

Header, mgd

Pressure at Location (psi)

SFE

Headera

C-II

Incin.

Strainer

C-II

Incin.

Booster

Pumps

C-II Incin

Quench

Sprayerb

C-II

Dew

PS1

Rack and

Gritc

PS2

R&G

Screen

PS2 R&G

Collector

PS2 R&G

Processing

Sludge

Complex

A

Sludge

Complex

B

End of

Fire

Loop

BDFd

Minimum

Pressure

Requirements

40.0 50.0

60.0 50.0 59.0

45.0

Scenario 1 15 91.9 85.0 67.2 50.0 87.5 88.9 92.9 92.9 92.9 88.5 90.9 88.5 83.3

Scenario 2 25 92.2 85.0 67.2 50.0 87.5 88.8 92.6 91.9 92.7 88.6 90.8 88.5 83.5

Scenario 3 58 93.4 85.0 67.2 50.0 87.4 81.5 90.2 89.5 91.0 88.6 89.7 70.0 84.4 a At the SFE Header, losses from the pump through the strainer and discharge line are not included. They are added later in this analysis.

b Current node elevation = 155.0 ft c PS-1 peak demand set to 400 gpm to maintain at least 50 psi at the location for all constraint scenarios d Current node elevation = 117.0 ft

PPS0331221027DET 2-11

Table 2-5. SFE System Pressures with Constraint of 40 psi for Complex II Incineration Booster Pumps

Scenario

Total

SFE

Flow at

SFE

Header, mgd

Pressure at Location (psi)

SFE

Headera

C-II

Incin.

Strainer

C-II

Incin.

Booster

Pumps

C-II

Incin

Quench

Sprayerb

C-II

Dew

PS1

Rack and

Gritc

PS2

R&G

Screen

PS2 R&G

Collector

PS2 R&G

Processing

Sludge

Complex

A

Sludge

Complex

B

End of

Fire

Loop

BDFd

Minimum

Requirements

40.0 50.0 60.0 50.0 59.0 45.0

Scenario 1 15 64.7 57.8 40.0 22.8b 60.3 61.7 65.6 65.7 65.7 61.3 63.7 61.3 56.1

Scenario 2 25 65.0 57.8 40.0 22.8b 60.3 61.6 65.4 64.7 65.5 61.3 63.6 61.3 56.3

Scenario 3 58 66.2 57.8 40.0 22.8b 60.2 54.3 63.0 62.3 63.8 61.4 62.5 42.8 57.2 a At the SFE Header, losses from the pump through the strainer and discharge line are not included. They are added later in this analysis.

b Values represent pressure prior to proposed booster pumps. Because these values are less than the minimum pressure requirement, booster pumps would be required.

c PS-1 peak demand set to 400 gpm to maintain at least 50 psi at the location for all constraint scenarios.

d Node elevation and pipe dimensions leading to BDF Tray Scrubber may still be modified in the model. Current node elevation = 117.0 ft

PPS0331221027DET 2-12

A review of current PS operation was conducted by Jacobs to take reasonable effort that operational issues are addressed in the new PS. It was found that GLWA’s SFE PS Standard Operating Procedure recommends “pump discharge pressure should be 72 to 90 psig,” with “normal discharge pressure being 85 psig.” This standard operating procedure applied to the SFE distribution system prior to the new scrubber system, installed under PC-791 and completed in about 2018. As noted above, the SFE Distribution System Model indicates that the current SFE header pressure must be above at least 95 psi to meet the 50 psi requirement at the quench sprayer. Figure 2-7 shows that the SFE PS header pressures have been consistently in the 90 to 110 psi range over the past 3 years, thus confirming the SFE model.

Figure 2-7. SFE Pump Station Discharge Pressure for 3-Year Period

It should be noted that the existing large SFE pumps are rated for 25 mgd and 185 ft total dynamic head (TDH), or 80 psi. To achieve 100 psi, two large pumps must be operated simultaneously at lower than design flow capacity at all times. Over the past year, average flows have been about 21 mgd. To meet the flow and head conditions, the pumps must operate at 10.5 mgd (7,300 gpm) and 100 psi, which is outside their acceptable operating range, as shown on Figure 2-8. Operating outside the acceptable operating range leads to increased pump vibration, inlet recirculation, and other detrimental effects to the pump.

These issues will be addressed by providing new pumps that more closely match current and projected flows and pressure requirements.

PPS0331221027DET 2-13

Figure 2-8. Pump Curve Illustrating Increased Head at Lower Flows

2.2 Projected SFE Usage and Pump Station Capacity

Table 2-6 shows the current and the projected SFE usage by use and location. Jacobs used site investigations, operator input, manufacturer information, and operations and maintenance (O&M) manuals to obtain the flow rates per unit used each process. Typical or average usage per process is based on the typical number of units in service and firm or maximum usage is based on the firm number of units or maximum expected usage per process.

Jacobs also included GLWA-identified future SFE uses for the RRO hypochlorite and bisulfite carrier water, which is already piped to the feed system, and the future use of SFE at PS-2 Rack and Grit improvements, which is currently in the design phase.

Treated SFE to replace existing SW uses (i.e., chlorine [Cl2] carrier water, sulfur dioxide [SO2] carrier water, and LPSW, IPSW and HPSW) will be pumped using separate pumps from the SFE pumps. The reason for separate pumps is that the required head pressure for the SFE treatment pumping system is significantly less than the SFE distribution system, making the operating costs…