Main Water Treatment Plant Improvements - Wichita, … Water Treatment Plant...Number Chapter Title of Pages 1.0 Introduction 9 ... Main Water Treatment Plant Improvements Table of

Report on the

Main Water Treatment Plant Improvements

City of Wichita Water Utilities

Project No. 73925

March 2014

Main Water Treatment Plant Improvements

prepared for

City of Wichita Water Utilities Wichita, Kansas

March 2014

Project No. 73925

prepared by

Burns & McDonnell Engineering Company, Inc. Kansas City, Missouri

COPYRIGHT © 2014 BURNS & McDONNELL ENGINEERING COMPANY, INC.

INDEX AND CERTIFICATION

City of Wichita Water Utilities Main Water Treatment Plant Improvements

Project No. 73925

Report Index Chapter Number Number Chapter Title of Pages

1.0 Introduction 9 2.0 East WTP Evaluation 31 3.0 East WTP Improvement Alternatives 12 4.0 Chemical Feed System Improvements 5 5.0 Opinions of Probable Cost 7 6.0 Conclusions 3

Certification

I hereby certify, as a Professional Engineer in the state of Kansas, that the information in this document was assembled under my direct personal charge. This report is not intended or represented to be suitable for reuse by the City of Wichita Water Utilities or others without specific verification or adaptation by the Engineer.

Nathaniel K. Dunahee, P.E. (Kansas P.E. No. 20335)

Date: 3/24/2014

Main Water Treatment Plant Improvements Table of Contents

City of Wichita TOC-1 Burns & McDonnell

TABLE OF CONTENTS

Page No.

1.0 INTRODUCTION ............................................................................................... 1-1 1.1 Purpose ................................................................................................................. 1-1 1.2 Scope .................................................................................................................... 1-1 1.3 Background .......................................................................................................... 1-1

1.3.1 Configuration of the Main Water Treatment Plant ............................... 1-2 1.3.2 East WTP .............................................................................................. 1-2 1.3.3 Equus Bed Well Field ........................................................................... 1-5 1.3.4 Potential Water Sources ........................................................................ 1-5 1.3.5 Treatment Goals .................................................................................... 1-5 1.3.6 Treatment Challenges ........................................................................... 1-6 1.3.7 Solids Contact Clarifiers ....................................................................... 1-7 1.3.8 Tube Settlers ......................................................................................... 1-8

2.0 WTP EVALUATION .......................................................................................... 2-1 2.1 Process Evaluation ............................................................................................... 2-1

2.1.1 Aeration................................................................................................. 2-1 2.1.2 Rapid Mix ............................................................................................. 2-2 2.1.3 Flocculation........................................................................................... 2-2 2.1.4 Sedimentation Basins ............................................................................ 2-3

2.2 Bench-scale Testing ............................................................................................. 2-7 2.2.1 Conventional Treatment of 100% EBWF ........................................... 2-10 2.2.2 Conventional Treatment of EWBF/EDL Blend .................................. 2-10 2.2.3 Treatment of 100% EBWF with Solids Contact Clarifiers ................. 2-16

2.3 Full-scale Testing ............................................................................................... 2-19

3.0 EAST WTP IMPROVEMENT ALTERNATIVES ................................................ 3-1 3.1 Alternative No. 1 – Basin Rehabilitation ............................................................. 3-1

3.1.1 Alternative No. 1a ................................................................................. 3-1 3.1.2 Alternative No. 1b ................................................................................. 3-3

3.2 Alternative No. 2 .................................................................................................. 3-7 3.2.1 Alternative No. 2a ................................................................................. 3-7 3.2.2 Alternative No. 2b ................................................................................. 3-7

3.3 Alternative No. 3 ................................................................................................ 3-10 3.4 Comparison of Alternatives ............................................................................... 3-10

4.0 CHEMICAL FEED SYSTEM IMPROVEMENTS ............................................... 4-1 4.1 Polymer System ................................................................................................... 4-1 4.2 Lime System ........................................................................................................ 4-2 4.3 Ferric System ....................................................................................................... 4-2



4.4 Chlorine System ................................................................................................... 4-2 4.5 Ammonia System ................................................................................................. 4-3

5.0 OPINIONS OF PROBABLE COST ................................................................... 5-1 5.1 Alternative No. 1 – Basin Rehabilitation ............................................................. 5-2

5.1.1 Alternative No. 1a – Minor Repairs ...................................................... 5-2 5.1.2 Alternative No. 1b – Major Repairs ...................................................... 5-3

5.2 Alternative 2 – Basin Replacement...................................................................... 5-4 5.2.1 Alternative No. 2a – Solids Contact Clarifiers ..................................... 5-4 5.2.2 Alternative No. 2b – Solids Contact Clarifiers & Tube Settlers ........... 5-5

5.3 Alternative 3 – New Treatment Plant .................................................................. 5-6 5.4 Chemical Feed Improvements ............................................................................. 5-7

6.0 CONCLUSIONS ................................................................................................ 6-1



LIST OF TABLES

Page No.

Table 1-1: EBWF Water Quality ................................................................................................ 1-5 Table 2-1: Design Requirements for Sedimentation Basins ....................................................... 2-7 Table 2-2: Required Chemical Doses Based on Jar Testing ..................................................... 2-16 Table 5-1: Alternative No. 1a Opinion of Probable Cost ........................................................... 5-2 Table 5-2: Alternative No. 1b Opinion of Probable Cost ........................................................... 5-3 Table 5-3: Alternative No. 2a Opinion of Probable Cost ........................................................... 5-4 Table 5-4: Alternative No. 2b Opinion of Probable Cost ........................................................... 5-5 Table 5-5: Alternative No. 3 Opinion of Probable Cost ............................................................. 5-6 Table 5-6: Chemical Feed Improvements Opinion of Probable Costs ....................................... 5-7 Table 6-1: Comparison of Alternatives....................................................................................... 6-2



LIST OF FIGURES

Page No.

Figure 1-1: East Plant Location .................................................................................................. 1-3 Figure 1-2: East Plant Process Schematic ................................................................................... 1-4 Figure 1-3: Tube Settlers (Images provided by WesTech, Inc.) .................................................. 1-8 Figure 2-1: Rapid Mix Channel – HRT ...................................................................................... 2-4 Figure 2-2: Flocculation Basin – HRT........................................................................................ 2-5 Figure 2-3: Flocculation Basin - Horizontal Velocity ................................................................ 2-6 Figure 2-4: Sedimentation Basins – HRT ................................................................................... 2-8 Figure 2-5: Sedimentation Basins - Overflow Rate .................................................................... 2-9 Figure 2-6: Jar Testing - Varying Lime Doses ......................................................................... 2-11 Figure 2-7: Jar Test 1 - 100% EBWF - Lime Dosing ............................................................... 2-12 Figure 2-8: Jar Test 2 - 100% EBWF - Ferric Dosing .............................................................. 2-13 Figure 2-9: Jar Test 2 - 100% EBWF - TOC Removal ............................................................. 2-14 Figure 2-10: Jar Test 3 - 100% EBWF - Polymer Dosing ........................................................ 2-15 Figure 2-11: Jar Test 4 - El Dorado and EBWF Blend - Lime Dosing .................................... 2-17 Figure 2-12: Jar Test 5 - El Dorado and EBWF Blend - Ferric Dosing ................................... 2-18 Figure 2-13: Jar Testing - Simulation of Solids Contact Clarifier ............................................ 2-20 Figure 2-14: Solids Contact Clarifier Simulation – Turbidity .................................................. 2-21 Figure 2-15: Solids Contact Clarifier Simulation - pH ............................................................. 2-22 Figure 2-16: Raw Water pH and Turbidity - Full-Scale Testing .............................................. 2-25 Figure 2-17: Raw Water Alkalinity and Hardness - Full-Scale Testing ................................... 2-26 Figure 2-18: Chemical Dosing - Full-Scale Testing .................................................................. 2-27 Figure 2-19: Settled Water Alkalinity and Hardness - Full-Scale Testing ............................... 2-28 Figure 2-20: Settled Water pH and Turbidity - Full-Scale Testing .......................................... 2-29 Figure 2-21: Turbidity Profile through the Treatment Basins .................................................. 2-30 Figure 2-22: Photos from Full-Scale Testing............................................................................ 2-31 Figure 3-1: Alternative No. 1a - Retrofit Existing Sedimentation Basins .................................. 3-2 Figure 3-2: Alternative No. 1b - Retrofit Existing Sedimentation Basins .................................. 3-4 Figure 3-3: East WTP Hydraulic Bottlenecks ............................................................................ 3-5 Figure 3-4: East WTP Pipe Velocities ........................................................................................ 3-6 Figure 3-5: Headloss in the East WTP ........................................................................................ 3-8 Figure 3-6: Alternative No. 2 - New Solids Contact Clarifiers .................................................. 3-9 Figure 3-7: Alternative No. 3 - New Water Treatment Plant ................................................... 3-11 Figure 4-1: Existing Polymer Blending Units ............................................................................ 4-1 Figure 4-2: Existing Wallace & Tiernan Chlorinator ................................................................. 4-3 Figure 4-3: Existing Wallace & Tiernan Ammoniators .............................................................. 4-4 Figure 4-4: Existing Ammonia Storage Tank and Vaporizer ..................................................... 4-5

Main Water Treatment Plant Improvements List of Abbreviations

City of Wichita i Burns & McDonnell

LIST OF ABBREVIATIONS

Abbreviation Term/Phrase/Name

µg/L Microgram Per Liter

AOP Advanced Oxidation Process

ASR Aquifer Storage and Recovery

BMcD Burns & McDonnell

CaCO3 Calcium Carbonate

CCPP Calcium Carbonate Precipitation Potential

CO2 Carbon Dioxide

DFI Driving Force Index

DOC Dissolved Organic Carbon

EBWF Equus Bed Well Field

EPA Environmental Protection Agency

H2O2 Hydrogen Peroxide

HRT Hydraulic Retention Time

KDHE Kansas Department of Health and Environment

LAR Little Arkansas River

LSI Langelier Saturation Index

MCL Maximum Contaminant Level

mg/L Milligram Per Liter

MGD Million Gallons per Day

MR Molar Ratio

MWTP Main Water Treatment Plant

Main Water Treatment Plant Improvements List of Abbreviations

City of Wichita ii Burns & McDonnell

Abbreviation Term/Phrase/Name

ng/L Nanogram Per Liter

NTU Nephelometric Turbidity Units

O3 Ozone

ppm Parts Per Million

PTR Pilot Test Report

s.u. Standard Units

SCC Solids Contact Clarifier

SWTP Surface Water Treatment Plant

TOC Total Organic Carbon

UF Ultrafiltration

WTP Water Treatment Plant

WWU Wichita Water Utilities

Main Water Treatment Plant Improvements Introduction

City of Wichita 1-1 Burns & McDonnell

1.0 INTRODUCTION

1.1 Purpose The purpose of this study is to identify the improvements necessary to treat only groundwater (primarily

from the Equus Beds Well Field) at the Main Water Treatment Plant (WTP). This study includes a

description and results of bench-scale and full-scale testing of the Main WTP to further assess treatment

limitations, develops alternatives for process modifications to improve treatment flexibility, and evaluates

existing chemical feed systems.

1.2 Scope This project includes the following tasks to develop alternatives at the Main WTP to treat 100 percent

groundwater supply:

• Evaluation of East WTP treatment processes;

• Bench-scale testing of the following raw water scenarios:

o 100 percent Equus Beds Well Field

o 75 percent Equus Beds Well Field and 25 percent El Dorado Lake;

• Full-scale testing of treatment of 100 percent Equus Beds Well Field supply at the Main WTP;

and

• Development of potential treatment alternatives.

1.3 Background The Main WTP currently treats a blend of surface water from the Cheney Reservoir and groundwater

from the Equus Beds Well Field (EBWF), Bentley Reserve Well Field, and Local Well Field. Increasing

demand, supply limitations, and necessary repairs to supply lines require the Main WTP to be capable of

treating only surface water and/or only groundwater. The previous process evaluation conducted by

Burns & McDonnell (BMcD) in the 2011 Main Water Treatment Plant Evaluation indicated that

treatment of solely groundwater only would be very difficult with the existing processes and equipment.

This is primarily due to the high hardness of the water, the high amount of lime required to achieve

adequate softening, configuration of the treatment processes, and the inability of the sedimentation basins

Fto effectively remove the excess turbidity generated by this lime.



1.3.1 Configuration of the Main Water Treatment Plant The Main WTP currently treats a raw water blend of surface water and groundwater. The Main WTP

includes two treatment trains, commonly referred to as the East WTP and the Central WTP, with a total

capacity between 155 and 160 MGD. The Central WTP is rated at 130 MGD, but hydraulic bottlenecks

limit capacity to approximately 125 MGD. The East WTP is rated at 30 MGD and is typically used in

conjunction with the Main WTP during periods of high demand or when additional treatment is required

during times where a higher percentage of groundwater is used in the blend.

In 2011, two separate events forced the City of Wichita to operate under different treatment scenarios,

both creating a real sense of urgency to investigate what would be required to treat various raw water

scenarios. The first event was the temporary well field shutdown, which required treatment of only

Cheney Reservoir water for several weeks. The second event was the construction phase of the Aquifer

Storage and Recovery (ASR) Phase II Surface Water Treatment Plant (SWTP), which could present

another set of challenges to overcome if a portion of the ASR SWTP treated flow is sent to the Main WTP

for treatment. Additionally, the City needs to make repairs to the supply line from Cheney Reservoir

which requires the Main WTP to operate solely on groundwater supply for an extended period of time.

The treatment process of the Main WTP is designed for surface water and is not suited for the sole

treatment of groundwater; therefore, modification to the current processes and/or equipment is required.

Due to basin configuration, capacity, performance, and age, the East WTP has been identified as the best

location to make the modifications necessary to treat solely groundwater.

1.3.2 East WTP An aerial view of the East WTP is presented in Figure 1-1 and a process schematic of the existing process

at the East WTP is shown in Figure 1-2. The treatment processes is nearly identical to that of the Central

WTP and includes aeration, a combination of lime softening and conventional coagulation, and

recarbonation. After recarbonation, water is blended back with water from the Central WTP and then

passes through dual media filtration and chlorine disinfection. High service pumps then transfer the

finished water from clearwells to the distribution system.

Two sedimentation basins in parallel are currently used to facilitate softening and sedimentation. The

design of these basins makes treatment of groundwater difficult due to the lack of adequate solids

inventory in the center cone, sludge blanket, solid recycle, and weir length to achieve adequate flow

distribution. Excessive turbidity is added to the process as a result of the high lime dose which contains

grit, unreacted lime, and slaked lime particles that are too large. The combination of these factors results

Figure 1-1

Wichita, KS

East Plant Location

East WTP

Central WTP

Figure 1-2

Wichita, KS

East Plant Process

Schematic

`

Local Wells Bentley Reserve ASR Phase II SWTP

Rapid Mix

Polymer

Ferric

`

Lime

Cheney Reservoir Intake

Equus Bed Well Field

Flocculation Basin

Primary Sedimentation

Basins

Gravity Filters

Chlorine Contact Basin

Aeration

CO2 Chlorine

Ammonia

Recarb and Secondary Sedimentation

Basin



in poor softening conditions for groundwater only scenarios. Basin design and limitations are discussed

further in Chapter 2.

1.3.3 Equus Bed Well Field The EBWF consists of 69 wells and has a total production capacity of 75 MGD. Water quality is

generally characterized by high hardness and alkalinity, low TOC, low turbidity and moderate pH as

shown in Table 1-1.

Table 1-1: EBWF Water Quality

Parameter 2009 (Average) 2013 (Measured During Testing)

Total Hardness 285 266

Total Alkalinity 219 236

TOC 0.7 1.19

Turbidity 4.9 2.39

pH 7.3 7.34

1.3.4 Potential Water Sources In addition to utilizing the EBWF, the City is considering options for development of additional water

sources. One source under consideration is El Dorado Lake (EDL), which is located approximately 40

miles from the WTP. As part of this evaluation, jar testing was conducted on a blended water consisting

of 25% EDL and 75% EBWF to analyze the treatability of this source.

1.3.5 Treatment Goals The Main WTP currently meets or exceeds the existing water quality regulatory standards and must be

able to do so when treating only groundwater. These key water quality parameters and finished water

quality goals are summarized in Table 1-2.

Some of the parameters listed, such as pH and alkalinity, are not primary drinking water standards but are

included because they affect finished water stability and are of concern with respect to the aesthetic

quality of the distribution system.



Table 1-2: Finished Water Goals

Parameter Goal Regulatory Limit

Filter Effluent Turbidity (individual Filter)

< 0.1 NTU for 95% of readings

Not to Exceed 0.3 NTU

< 0.3 NTU for 95% of readings

Not to Exceed 0.5 NTU

Manganese < 0.05 mg/L SMCL = 0.05 mg/L

Iron < 0.3 mg/L SMCL = 0.3 mg/L

Total Hardness 130 mg/L as CaCO3 N/A

Pathogen Inactivation:

Viruses

Giardia

Cryptosporidium

> 4-log removal/inactivation



4-log removal/inactivation



pH 8.0 - 8.5 s.u. N/A

Alkalinity 80 mg/L as CaCO3 Lead and Copper Stability

Total Organic Carbon (TOC)

25% or 35% removal depending on raw water alkalinity

25% or 35% removal depending on raw water alkalinity

Raw or Finished Water SUVA < 2 L/mg-m < 2 L/mg-m (alternative TOC

compliance)

Bromate < 10 µg/L < 10 µg/L

TTHM < 40 µg/L 80 µg/L LRAA

In general, operators of the Main WTP target a finished water with hardness of 130 mg/L CaCO3, pH

between 8.2 and 8.4, and total alkalinity between 60 and 80 mg/L as CaCO3. Maintaining similar

finished water quality when operating on only groundwater is important in order to maintain client

satisfaction and to prevent upsets in the distribution system.

1.3.6 Treatment Challenges Groundwater sources, including the EBWF, typically have high hardness with low TOC, low dissolved

organic carbon (DOC), and low turbidity. As a result, these options will be difficult to treat with the

current WTP configuration due to:

• Design of the WTP processes;

• High lime dose requirements;

• Poor performance of flocculation;



• Lack of solids inventory;

• Formation of pin flocs that settle poorly and result in higher settled water turbidities; and

• Carryover of lime residuals to downstream processes that could impact filtration and disinfection.

The existing WTP was designed to treat EBWF and other groundwater sources with conventional

treatment processes when blended with a surface water source. Cheney Reservoir raw water provides the

necessary turbidity and organics for the ferric and lime to perform well through abundant flocculant

particle (floc) formation. Turbidity and organics are significantly less for groundwater supplies and floc

particles are formed primarily through calcium carbonate precipitation. As a result the solids inventory

generated in the flocculation zone will be less and consist of much smaller particles. The small particles

need to be recirculated in order to provide sufficient surface area for the softening process. Without

solids recirculation and adequate sludge blanket in the center cone, the process will not be sustainable,

which will eventually lead to significantly reduced primary treatment performance.

Regulatory requirements for WTPs treating groundwater vary significantly from those for surface water

WTPs. However, when a plant is cycled between the two source types or operates on a blend of the two,

the requirements for surface water must be met. This leads to additional challenges, particularly in

regards to requirements for TOC reduction.

1.3.7 Solids Contact Clarifiers Solids contact clarifiers are frequently utilized at WTPs that perform softening treatment on groundwater.

This type of equipment is much more effective for groundwater treatment than the existing conventional

equipment utilized at the Main WTP, due to the provision of solids recirculation and maintenance of an

adequate sludge blanket.

The purpose of using a solids contact clarifier is the effective removal of calcium and magnesium

utilizing precipitation in combination with aggregation or growth of the floc by solids recycle in the

center cone. The water, after combining with previously generated solids in the basin, flows beneath the

cone of the solids contact clarifier and into the sedimentation portion of the solids contact clarifier. The

sedimentation portion of the basin provides solids/liquid separation and the water flows through orifices

or over weirs in radial launders before being collected in a center launder.

Solids collect at the bottom of the basin and are raked to the center of the basin using circular sludge

collection rakes. The recirculated solids provide the source water and lime a seed with which to react and



produce a large floc that is easily settleable. The solids beneath the center cone of the solids contact

clarifier are critical to the successful operation of the basin. These solids should range from 6 to 12

percent by volume beneath the center cone of the clarifier. Internal recirculation is typically 5 to 10 times

the design flowrate. Appropriate weir length, as provided by the radial lauders, will help to reduce settled

water turbidity by increasing the number of available flow paths, which reduces flow velocities and short-

circuiting in the basin.

1.3.8 Tube Settlers Tubes or plates may be installed at an angle to the flow in sedimentation basins to enhance settling of

solids. Tube settlers create a more uniform flow in the sedimentation zone and improve settling

characteristics by reducing preferential flow paths, mixing, and the effective Reynolds number. Tube

settlers also decrease the distance a particle needs to settle before being trapped and removed. As a result,

using tube settlers will allow higher flows through a basin (typically double the overflow rate), and will

improve settled water turbidity and treatment performance.

Figure 1-3: Tube Settlers (Images provided by WesTech, Inc.)

Tube settlers present some operational difficulties that should be considered in addition to the benefits

described above. These difficulties include:

• An additional element to be inspected, cleaned, and maintained during annual or semi-annual

basin maintenance;

• Removal of possible build-up from small particles that adhere to the tube walls;



• Development of biofilm and/or algae over time, similar to that typical for submerged concrete

and plastics; and

• Restricted access that requires removal of one or more tube modules to access submerged

equipment.

These operational difficulties can be reduced significantly during design by including a water monitor and

fire-hose attachment; addition of a small, periodic, chlorine maintenance dose to minimize biofilm and

algae growth; and installation of removable tube modules near the bridge for easy access to submerged

equipment. When tube settlers are used in softening basins, the quality of lime can greatly impact the

amount of calcium carbonate scale that forms on the tubes. Use of high quality, highly reactive lime is

critical to reducing maintenance requirements associated with accumulation of scale.

Main Water Treatment Plant Improvements WTP Evaluation


2.0 WTP EVALUATION

In order to evaluate the ability (or inability) to treat 100% EBWF and identify potential alternatives, a

process evaluation was conducted on the existing East WTP basins, bench-scale testing was conducted to

determine chemical dosing, and a full-scale test was conducted at the Main WTP to demonstrate

performance of the current systems when treating only groundwater. The following sections describe

each of these aspects of evaluation.

2.1 Process Evaluation As shown previously in Figure 1-1, the East WTP includes aeration, combination of lime softening and

conventional coagulation, and recarbonation. Rapid mix occurs in an enclosed channel with four mixers

in series. Flocculation is achieved with paddlewheel flocculators in a baffled basin with serpentine flow.

Two square sedimentation basins are operated in parallel to facilitate softening and sedimentation.

2.1.1 Aeration Aeration provides many benefits to water treatment facilities, including:

• Shifting of the oxidation state of metals to allow them to become particulate and be removed in

downstream processes;

• Air stripping of volatile organic compounds;

• Removing hydrogen sulfide, carbon dioxide, and other gasses from waters that are oversaturated;

and

• Adding oxygen and carbon dioxide to waters that are unsaturated.

Aeration at the Main WTP is used for removal of excess iron and carbon dioxide. Aeration will oxidize

dissolved iron from Fe2+ to Fe3+, which is non-soluble and easily removed via physical treatment

processes. However, if iron already exists as Fe3+, aeration provides no benefit. Similarly, if the water is

not highly saturated with excess carbon dioxide, aeration provides minimal benefit.

Previous studies and evaluation of the Main WTP have indicated that aeration is not required based on

influent iron and carbon dioxide levels. While demolition of the aeration equipment is not necessary,

allowing a portion of the flow to bypass aeration will not significantly impact treatment. Iron limits in the

Main WTP effluent are currently non-detect and may increase slightly if a portion of the flow bypasses



aeration; however, directing 10 to 50 percent of the flow through the aeration bypass will not impact

regulatory compliance.

2.1.2 Rapid Mix Rapid mix for the East WTP is housed in an enclosed channel located beneath the main office building.

Rapid mix consists of four stages with four constant speed, mechanical mixers that are operated in series

within this channel. Polymer, lime, and ferric are all injected within this rapid mix channel. The total

channel volume is 1827 ft3, with each mixer responsible for covering approximately 457 ft3. Each mixer

is a vertical-mounted turbine mixer with a horsepower (HP) of 15 and a speed of 125 revolutions per

minute (rpm).

The two most important characteristics of rapid mix are mixing intensity and mixing time. The current

equipment and configuration correlates to a mixing intensity of 605 sec-1. In general, polymer activation

requires a mixing intensity of 300 to 400 sec-1; mixing above this amount can shear the polymer,

decreasing its ability to function as a bridging agent between flocs and particles. Ferric, on the other

hand, requires a much larger mixing intensity, approximately 1000 sec-1, for proper dispersion and

activation. Therefore, the current rapid mix will result in reduced chemical effectiveness due to the fact

that polymer is over-mixed and ferric is under-mixed.

Due to the layout, the mixing time is a function of flow velocity through the rapid mix channel and will

vary as flow in the East WTP varies. Hydraulic retention time (HRT) in the channel is shown in Figure 2-

1 as a function of flow. The Kansas Department of Health and Environment (KDHE) rapid mix design

guidelines recommend a maximum allowable mixing time of 30 seconds. Mixing times provided in the

rapid mix channel are higher than 30 seconds for all flows below 40 MGD as shown in Figure 2-1. This

could be adjusted somewhat by limiting the number of mixers running at lower flows; however, the

combination of long mixing time and low mixing energy is not optimal.

In order to optimize rapid mix and increase chemical effectiveness, it is recommended that the existing

rapid mix system be replaced with an inline flash mixing system. The system should be sized to provide

a mixing intensity of approximately 1000 sec-1 for ferric activation. Polymer and lime feed points should

be moved farther downstream to the center cones of the treatment basins. The gentle mixing provided in

the basins will be sufficient for dispersion and the polymer will not be subjected to harmful shear stresses.

2.1.3 Flocculation The flocculation basin of the East WTP is located just downstream from the rapid mix channel. Redwood

baffle walls are positioned to create serpentine flow through the basin. Paddle wheels with variable speed



drives are used to create a gradient of mixing energy in the basin. Hydraulic retention time is 29 minutes

at the design flow of 30 MGD, which adheres to state design guidelines as shown in Figure 2-2.

The original basin configuration did not include serpentine baffles, but rather was designed to allow flow

to travel straight through the basin. Baffles were installed as part of the 1992 Phase IIB WTP

Improvements in order to create more uniform plug flow conditions; however, this also resulted in higher

horizontal flow velocities. KDHE design guidelines state that the horizontal flow velocity in the

flocculation zone should be within the range of 0.5 to 1.5 ft/min. The graphs in Figure 2-3 show the

resulting horizontal velocities for various plant flows. The graph on the left side of the figure shows flow

conditions under the original design and the graph on the right side shows flow conditions with the

current serpentine configuration. Under current conditions, horizontal flow velocity in the flocculation

basin is approximately 11 ft/min at plant flow of 30 MGD, seven times higher than the recommended

value. These high velocities will induce shear stresses and cause damage to the floc.

Separate mechanical flocculation is not required when solids contact clarifiers with internal recycle are

used; therefore, if new treatment equipment and/or basins are installed, it is recommended that the

existing flocculation basin be bypassed to prevent floc damage.

2.1.4 Sedimentation Basins Two square sedimentation basins currently serve as the primary treatment basins for the East WTP. The

smaller basin has a process capacity of approximately 10 MGD. The larger basin has a process capacity

of approximately 20 MGD. The basins can be operated individually or in parallel. According to WTP

staff, the smaller basin has been operated in the past with 15 MGD, which resulted in deterioration of

process performance.

Design requirements for sedimentation basins vary depending on the type of source water. If solids

contact clarifiers are used rather than conventional sedimentation basins, design requirements are

modified further. A summary of some of the key design requirements are shown in Table 2-1.

Figure 2-1

Wichita, KS

Rapid Mix Channel - HRT

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35 40 45 50

Hyd

rau

lic R

eten

tio

n T

ime

(sec

)

Flow (mgd)

1 Stage

All Stages

KS Maximum Allowable (30 sec)

Figure 2-2

Wichita, KS

Flocculation Basin - HRT

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50

Hyd

rau

lic R

eten

tio

n T

ime

(min

ute

)

Flow (mgd)

KS Required Minimum (30 min)

Figure 2-3

Wichita, KS

Flocculation Basin -

Horizontal Velocity

0

1

2

3

4

5

6

0 10 20 30 40 50

Ho

rizo

nta

l Vel

oci

ty (

ft/m

in)

Flow (mgd)

Previous Configuration – Cross Flow

KS Requirement

0.5 - 1.5 ft/min

0

2

4

6

8

10

12

14

16

18

20

0 10 20 30 40 50

Ho

rizo

nta

l Vel

oci

ty (

ft/m

in)

Flow (mgd)

Current Configuration – Serpentine Flow

KS Requirement

0.5 - 1.5 ft/min



Table 2-1: Design Requirements for Sedimentation Basins

Type of Unit 10 State Standards Kansas

HRT Sedimentation Basin 4 hr 2 hr

(groundwater only) Solids Contact Clarifier

(softening) 1-2 hr

(groundwater only) 1-2 hr

(groundwater only)

Overflow Rate

Sedimentation Basin --- 1.5 gpm/ft2

Solids Contact Clarifier (softening) 1.75 gpm/ft2 1.75 gpm/ft2

Weir Length Sedimentation Basin 20,000 gpd/ft 20,000 gpd/ft

Solids Contact Clarifier (softening) 28,800 gpd/ft 28,800 gpd/ft

HRTs for the existing basins are shown in Figure 2-4. As seen in the figure, each basin has sufficient

volume to meet HRT requirements for groundwater softening for total plant flows of up to 40 MGD.

Overflow rates for the two basins are shown in Figure 2-5 and indicate that the basins are capable of

treating a combined flow of over 50 MGD without exceeding the maximum allowable overflow rate.

Based on HRT and overflow rate, the existing basins are within acceptable design ranges; however, the

structural integrity of the basins is deteriorating and the equipment is not designed for softening of

groundwater. Cracking is prevalent in the walls and floors of both basins and has caused significant

leaking to occur. Repairs to these cracks will be required in order to extend lifespan of these basins. The

existing equipment within the basins consists of a center influent well, inlet baffle, sludge collection rake,

and perimeter effluent weir. This type of equipment does not provide solids recirculation, which limits

the potential for generation of an adequate solid inventory when treating primarily groundwater.

Additionally, the location and limited weir length (perimeter effluent launder) allows hydraulic short

circuiting through the basin.

2.2 Bench-scale Testing Bench-scale testing was conducted in November 2013 to evaluate the chemical dosing required for

treatment of groundwater from the EBWF. Three main scenarios were tested: treatment of 100% EBWF

with conventional basins, treatment of a blend of 75% EBWF and 25% EDL with conventional basins,

and treatment of 100% EBWF via solids contact clarifiers. Where chemical doses are quantified in this

section, lime is recorded as CaO, ferric is listed as neat product (60% ferric sulfate), and polymer is listed

as neat product.

Figure 2-4

Wichita, KS

Sedimentation Basins -

HRT

0

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40 50

Hyd

rau

lic R

eten

tio

n T

ime

(hr)

Total Flow (mgd)

East West

KS Required Minimum (2 hr for

groundwater softening)

Figure 2-5

Wichita, KS

Sedimentation Basins -

Overflow Rate

0.0

0.5

1.0

1.5

2.0

0 10 20 30 40 50

Ove

rflo

w R

ate

(gp

m/s

q f

t)

Total Flow (mgd)

East Basin West Basin

KS Maximum Allowable (1.5 gpm/sq ft)



2.2.1 Conventional Treatment of 100% EBWF Water was collected from the EBWF and used for jar testing to determine the chemical doses required to

perform adequate treatment. For Jar Test 1, the target lime dose was determined by applying six lime

doses ranging from 80 to 180 mg/L to the six jars, as well as a constant ferric dose of 20 mg/L and no

polymer to all jars. Rapid mix was induced for 30 seconds, followed by 30 minutes of flocculation and

30 minutes of settling. Figure 2-6 shows the jar test in progress; the resulting changes in alkalinity,

hardness, and pH are shown in Figure 2-7. Softening at the Main WTP is operated to achieve a final

hardness of approximately 130 mg/L as CaCO3, therefore this was the goal of the jar testing as well. A

lime dose of 130 mg/L was selected as the target dose based on achieving this hardness goal as seen in

Figure 2-7. This lime dose also produced a final alkalinity of 80 and pH of 8.8, both of which are within

acceptable ranges.

Jar Test 2 was conducted to determine the target ferric dose. Ferric doses were varied from 20 to 70 mg/L

across the jars, with 3 mg/L of polymer in each jar. The lime dose was started at 130 mg/L for the lowest

ferric dose and increased by 5 mg/L for each 10 mg/L increase in ferric in order to counteract alkalinity

consumption. Testing conditions included 30 seconds of rapid mix, 30 minutes of flocculation, and 30

minutes of settling. Turbidity measurements were taken every 5 minutes during the settling period and

are shown in Figure 2-8. Final turbidity measurements were similar for ferric doses of 40, 50, 60, and 70

mg/L. Minimal additional turbidity reduction was achieved at ferric doses above 50 mg/L. TOC samples

were collected during the testing and analyzed after all jar testing had been completed. The TOC data for

Jar Test 2 is shown in Figure 2-9. Good TOC reduction was achieved and minimal additional benefit was

seen when doses exceeded 50 mg/L. Final hardness values from the jars ranged from 98 to 118 mg/L,

lower than the target of 130 mg/L, indicating that the required lime dose may be slightly lower than the

130 mg/L selected in Jar Test 1.

Polymer doses were varied from 0 to 5 mg/L in Jar Test 3, with lime and ferric doses held consistent for

all jars at 130 mg/L and 50 mg/L, respectively. The same rapid mix, flocculation, and settling procedures

were followed, and turbidity measurements were collected at 5 minute intervals during settling. Based on

the turbidity curves displayed in Figure 2-10, a polymer dose of 3 mg/L was selected as the optimal dose.

Similar to the results seen in Jar Test 2, final hardness measurements were 110 to 112 mg/L, indicating

potential to reduce the lime dose.

2.2.2 Conventional Treatment of EWBF/EDL Blend A similar process as described above was utilized to determine target dosing for the blend scenario of

75% EBWF and 25% EDL. Jar Test 4 was conducted to determine the optimal lime dose. Doses were

Figure 2-6

Wichita, KS

Jar Testing – Varying Lime

Doses

6

6.5

7

7.5

8

8.5

9

9.5

10

10.5

11

0

20

40

60

80

100

120

140

160

180

200

80 100 120 140 160 180

pH

Alk

alin

ity

and

Har

dn

ess

(mg

/L a

s C

aCO

3)

Lime Dose (mg/L)

Alkalinity

Hardness

pH

Figure 2-7

Wichita, KS

Jar Test 1 – 100% EBWF -

Lime Dosing

Lime Ferric Polymer

Jar No. (mg/L) (mg/L) (mg/L)

1 80 20 0

2 100 20 0

3 120 20 0

4 140 20 0

5 160 20 0

6 180 20 0

Raw Water

pH 7.34

Alkalinity 236

TOC 3.83* (1.19)

Turbidity 2.39

Hardness 266

0

5

10

15

20

25

0 5 10 15 20 25 30 35 40

Turb

idit

y (n

tu)

Settling Time (min)

Jar 1

Jar 2

Jar 3

Jar 4

Jar 5

Jar 6

Figure 2-8

Wichita, KS

Jar Test 2 – 100% EBWF

– Ferric Dosing

Lime Ferric Polymer


1 130 20 3

2 135 30 3

3 140 40 3

4 145 50 3

5 150 60 3

6 155 70 3

Raw Water

pH 7.34

Alkalinity 236

TOC 3.83* (1.19)

Turbidity 2.39

Hardness 266

Figure 2-9

Wichita, KS


– TOC Removal

0.5

0.55

0.6

0.65

0.7

0.75

0 20 40 60 80

TOC

(m

g/L

)

Ferric Dose (mg/L)

Figure 2-10

Wichita, KS


– Polymer Dosing

0

5

10

15

20

25

30

0 5 10 15 20 25 30 35

Turb

idit

y (n

tu)

Settling Time (min)

Jar 1

Jar 2

Jar 3

Jar 4

Jar 5

Jar 6

Lime Ferric Polymer


1 130 50 0

2 130 50 1

3 130 50 2

4 130 50 3

5 130 50 4

6 130 50 5

Raw Water

pH 7.34

Alkalinity 236

TOC 3.83* (1.19)

Turbidity 2.39

Hardness 266



lowered from those used in Jar Test 1 to account for the lower hardness in the blended water. In order to

achieve the target hardness of 130 mg/L as CaCO3, a dose of 80 mg/L was required, as shown in Figure

2-11. This lime dose also resulted in an alkalinity of 100 mg/L and pH of 8.75.

Jar Test 5 utilized the lime dose of 80 mg/L and a polymer dose of 3 mg/L. Ferric doses were varied

between 20 and 70 mg/L. Based on turbidity measurements collected during the settling period, a ferric

dose of 50 mg/L was determined to be optimal. As seen in Figure 2-12, 50 mg/L of ferric resulted in the

lowest turbidity measurement at the end of the 30 minute settling period.

A summary of the water quality and chemical doses required, as determined by Jar Tests 1 through 5, is

contained in Table 2-2. A range of values is shown for the required lime dose for 100% EBWF as a result

of the final hardness values Jar Tests 1 through 3.

Table 2-2: Required Chemical Doses Based on Jar Testing

Parameter Value (mg/L)

100% EBWF 75% EBWF/ 25% EDL Hardness (as CaCO3) – Raw

Water 266 226

Hardness (as CaCO3) – Target 130 130

pH 8.7-8.9 8.7-8.9

Required Doses:

Lime (as CaO) 110-130 80

Ferric (as neat product) 50 50

Polymer (as neat product) 3 3

2.2.3 Treatment of 100% EBWF with Solids Contact Clarifiers Jar Tests 1 through 5 were designed to mimic the existing treatment processes at the Main WTP. Solids

contact clarifiers are specifically designed for lime softening and are typically more effective for

groundwater softening than conventional sedimentation basins. Therefore, Jar Tests 6 through 13 were

designed to simulate the use of a solids contact clarifier to treat 100% EBWF. As discussed previously in

Section 1.3.7, solids contact clarifiers utilize internal recycle flows to recirculate solids, generating a large

solids inventory, providing additional opportunity for lime solids to interact with hardness in the influent

water, and generating large floc particles that readily settle during sedimentation.

Figure 2-11

Wichita, KS

Jar Test 4 – El Dorado and

EWBF Blend – Lime Dosing

6.5

7

7.5

8

8.5

9

9.5

10

10.5

11

0

20

40

60

80

100

120

140

160

180

60 80 100 120 140 160

pH

Alk

alin

ity

and

Har

dn

ess

(mg

/L a

s C

aCO

3)

Lime Dose (mg/L)

Alkalinity

Hardness

pH

Lime Ferric Polymer


1 60 20 0

2 80 20 0

3 100 20 0

4 120 20 0

5 140 20 0

6 160 20 0

Raw Water

pH 7.43

Alkalinity 190

TOC 1.61

Turbidity 4.44

Hardness 226

Figure 2-12

Wichita, KS

Jar Test 5 – El Dorado and

EWBF Blend - Ferric Dosing

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30 35 40

Turb

idit

y (n

tu)

Settling Time (min)

Jar 1

Jar 2

Jar 3

Jar 4

Jar 5

Jar 6

Raw Water

pH 7.43

Alkalinity 190

TOC 1.61

Turbidity 4.44

Hardness 226

Lime Ferric Polymer


1 80 20 3

2 80 30 3

3 80 40 3

4 80 50 3

5 80 60 3

6 80 70 3



In order to simulate this process, Jar Tests 6 through 13 were conducted in succession and the solids

generated during each test were saved and used in the next. This reuse of solids was utilized to generate a

larger solids inventory, simulating the internal recycle process within a solids contact clarifier. Each jar

test was conducted with a 30 second rapid mix stage, followed by 20 minutes of flocculation and 20

minutes of settling. Lime, ferric and polymer were dosed during rapid mix. After the conclusion of each

jar test, the water was drained off the top of the jars, the solids were retained in the jars, and new raw

water was added prior to beginning the next test. The increase in solids inventory can be seen in the

photos in Figure 2-13.

Initial chemical dosing started with 120 mg/L of lime, 50 mg/L of ferric, and 3 mg/L of polymer in Jar

Test 6. The lime dose was decreased slightly due to the observations made during Jar Tests 2 and 3. For

Jar Tests 7 through 12, lime doses ranged from 110 to 135 mg/L across the jars in order to determine if

there was any significant difference in performance for this range of doses. Ferric and polymer were

dosed at 50 mg/L and 3 mg/L, respectively, for all tests. For the final iteration of the simulation, Jar Test

13, the solids from Jars 1, 2, and 3 were combined into one jar and the solids from Jars 4, 5, and 6 were

combined into a second jar to maximize the solids inventory for the test.

Turbidity measurements for each of the jar tests are shown in Figure 2-14. In general, turbidities were

lower than 3 NTU for all tests except for Jar 6 which had the highest lime dose. Turbidity in Jar 6 did

decrease as the iterations progressed and the final value was 1.33 NTU. Turbidities were very similar for

those seen in Jar Test 2 after 20 minutes of settling. The pH values for each iteration of the solids contact

clarifier simulation are shown in Figure 2-15. As expected, pH generally increased as lime dose in the

jars increased.

2.3 Full-scale Testing In order to expand upon jar testing results and further define the limitation of the Main WTP to treat

groundwater only, a full-scale test was conducted in December 2013. Due to the time of year, only the

Central WTP was operating during the full-scale test. The Central WTP typically achieves slightly better

treatment performance than the East WTP; therefore, the Central WTP is the portion of the Main WTP

most likely to be capable of treating 100% EBWF without requiring modifications.

The WTP began switching from the normal influent blend to 100% EBWF during the early morning

hours on December 10. Plant flow was approximately 45 MGD, resulting in an HRT of approximately 8

hours between the head of the WTP and the effluent of the secondary sedimentation basins. By 8:00 am

the switchover was complete and the WTP was operating on 100 percent groundwater. Groundwater

Figure 2-13

Wichita, KS

Jar Testing – Simulation of

Solid Contact Clarifier

Solids accumulation after first iteration

Solids accumulation after a few iterations

Final solids accumulation after all iterations and combining of jars

Figure 2-14

Wichita, KS

Solids Contact Clarifier

Simulation - Turbidity

0.1

1

10

Jar Test 6 Jar Test 7 Jar Test 8 Jar Test 9 Jar Test 10 Jar Test 11 Jar Test 12 Jar Test 13

Turb

idit

y (N

TU)

Test Iteration

Jar 1 Jar 2

Jar 3 Jar 4

Jar 5 Jar 6

Figure 2-15

Wichita, KS


Simulation - pH

8

8.2

8.4

8.6

8.8

9

9.2

9.4

9.6

9.8

10

Jar Test 6 Jar Test 7 Jar Test 8 Jar Test 9 Jar Test 10 Jar Test 11 Jar Test 12 Jar Test 13

pH

Test Iteration

Jar 1 Jar 2

Jar 3 Jar 4

Jar 5 Jar 6



supply was maintained until 4:00 pm on December 11, and the WTP returned to normal operation with

blended raw water. Raw water quality characteristics are shown in Figures 2-16 and 2-17. As expected,

alkalinity and hardness each increased by approximately 50 mg/L with the switchover to groundwater,

which can be seen in the graph in Figure 2-17.

Chemical doses were adjusted at various time intervals during the testing period. The applied doses for

lime, ferric, and polymer are displayed in Figure 2-18. As the switch to groundwater was made, lime was

increased to 91 mg/L, while polymer and ferric were maintained at 1.2 mg/L and 12 mg/L, respectively.

After several hours of operation and observations that the settled water hardness was rising, the lime dose

was increased slightly to 96 mg/L. As the hardness and turbidity levels in the settled water continued to

rise, lime was increased gradually up to a final value of 100.8 mg/L, ferric was increased to 25 mg/L, and

polymer was increased to 1.5 mg/L.

Turbidity, pH, alkalinity and hardness were closely monitored throughout the duration of the test period

and were measured at various locations within the treatment process. Hardness and alkalinity

measurements for the settled water are shown in Figure 2-19. Hardness gradually increased during the

test period, with levels averaging around 140 mg/L. Alkalinity also increased until the ferric dose was

raised and more alkalinity was consumed in the process, lowering the alkalinity by nearly 20 mg/L.

Figure 2-20 shows the measured turbidity in the settled water just after leaving secondary sedimentation.

As indicated during jar testing and from the process evaluation, the WTP was not able to adequately

remove the additional turbidity resulting from increased lime doses. Under normal operating

circumstances, settled water turbidity is approximately 1 NTU and industry standards recommended

settled water turbidity of less than 2 NTU prior to filtration. Within 4 hours of operation with 100%

EBWF, settled water turbidity was up to 3.5 and continued to increase, eventually exceeding 10 NTU. In

addition to the sample locations normally monitored by WTP operators, turbidity measurements were

taken within the basins to generate a turbidity profile through the treatment train. This profile is shown in

Figure 2-21. The difference between the two profiles is a result of the ferric dose increasing from 12 to

25 mg/L, which resulted in lower turbidities. However, despite the improvement seen, turbidity in the

settle water was still very high (10.1 NTU).

In addition to the numerical data, physical observations of the WTP processes showed the degradation of

treatment performance. Photos contained in Figure 2-22 highlight some of the major performance

indicators that were observed. Influent water was visibly darker in color, likely due to the amount of iron

present in the groundwater. Observation of the flocculation basins showed the floc to be small pin flocs



that were difficult to settle, as opposed to the larger flocs that are typically generated under normal

operating conditions and are easily removed during sedimentation. Water in the sedimentation basins was

cloudy throughout the length of the basin and the operators quickly noticed that submerged equipment

was no longer visible. Finally, carryover of solids was seen in the filters as the water above the filter

media became cloudy.

Based on the physical observations and water quality measurements, it is clear that the existing WTP is

not capable of operating for extended periods of time with groundwater as the sole supply source.

Finished water quality was not significantly affected during the test period, due to strong performance by

the filters; however, under extended periods of operation in this manner, the high turbidity loading on the

filters would eventually cause clogging and build-up within the filter media. Filter run times would be

significantly reduced and acid washing of the media would be required for removal of calcium carbonate

buildup. Breakthrough of excess calcium carbonate would affect the clearwell and distribution system,

leading to calcium carbonate precipitation, scale, and headloss. Increased hardness in the finished water

could also lead to customer complaints.

Figure 2-16

Wichita, KS

Raw Water pH and Turbidity

– Full-Scale Testing

0

2

4

6

8

10

12

14

16

18

Tu

rbid

ity,

NTU

; pH

, SU

Raw Turbidity

Raw pH

Figure 2-17

Wichita, KS

Raw Water Alkalinity and

Hardness– Full-Scale Testing

0

50

100

150

200

250

300

350

Har

dn

ess,

Alk

alin

ity,

mg/

L as

CaC

O3

Raw Alkalinity

Raw Hardness

Figure 2-18

Wichita, KS

Chemical Dosing – Full-Scale

Testing

0

5

10

15

20

25

30

0

20

40

60

80

100

120

Ferr

ic a

nd

Po

lym

er D

ose

(m

g/L

as n

eat

pro

du

ct)

Lim

e D

ose

(m

g/L

as C

aO)

Lime

Ferric

Polymer

Figure 2-19

Wichita, KS

Settled Water Alkalinity and

Hardness – Full-Scale Testing

0

20

40

60

80

100

120

140

160

Sett

led

Har

dn

ess,

Alk

alin

ity,

mg/

L as

CaC

O3

Settled Total Hardness

Settled Total Alkalinity

Figure 2-20

Wichita, KS

Settled Water pH and

Turbidity – Full-Scale Testing

0

2

4

6

8

10

12

14

Sett

led

Tu

rbid

ity,

NTU

; pH

, SU

Settled Turbidity

Settled pH

Figure 2-21

Wichita, KS

Turbidity Profile Through

the Treatment Basins

0

5

10

15

20

25

30

35

Raw Water Sed Basin 1 Influent Sed Basin 1 Middle Sed Basin 2 Influent Sed Basin 2 Middle Settled Water

Turb

idit

y (N

TU)

12/11/2013 9:30

12/11/2013 14:00

Figure 2-22

Wichita, KS

Photos from Full-Scale

Testing

Darker Influent Water Color

Cloudy Water in Sedimentation Basin Solids Carryover to Filters

Weak and Watery Floc

Operating

Offline

Main Water Treatment Plant Improvements East WTP Improvement Alternatives


3.0 EAST WTP IMPROVEMENT ALTERNATIVES

In order to treat solely groundwater in the East WTP, process changes and modifications to the existing

plant are required. Proposed alternatives range in scale from minor improvements to the existing system

to a new water treatment plant designed specifically for groundwater treatment. All of the proposed

alternatives are based on the use of solids contact clarifiers to conduct softening treatment. In many of

the alternatives, the treatment capacity in the East WTP will be increased in the areas where

improvements are made; however, a detailed hydraulic analysis of the existing infrastructure throughout

the plant will need to be completed to verify the ability of the WTP to handle the increased flow. A

cursory examination of hydraulic capacity was completed to identify bottlenecks in the system and

highlight infrastructure that may need to be replaced in order to utilize the full treatment capacity.

3.1 Alternative No. 1 – Basin Rehabilitation Alternative No. 1 is based on utilizing the existing sedimentation basins and retrofitting them with new

equipment to allow them to operate as solids contact clarifiers. This option is split into two sub-

alternatives with varying degrees of capital expense.

3.1.1 Alternative No. 1a The first sub-alternative, Alternative No. 1a, includes installation of solids contact clarifier equipment and

minimal repairs to the existing basins at the East WTP, as well as bypassing of the existing flocculation

basin. A general depiction of this alternative is shown in Figure 3-1.

Due to the design deficiencies of the existing flocculation basin and the internal mixing that will be

provided in the retrofitted sedimentation basins, a new pipe (54 inch diameter) will be installed to transfer

water directly from rapid mix to the basins, bypassing the existing flocculation basin. This will reduce

the exposure of newly forming floc to the shear stresses that are currently generated by the high flow

velocities in the flocculation basin. Repairs will be made to the walls and floors of the existing

sedimentation basins to fix cracking and other surface concrete problems that are currently causing

leaking in the basins. Retrofitting each basin with a draft tube, center cone, radial launders, and a new

sludge collection system will allow the basins to function as solids contact clarifiers. This will greatly

improve the ability to treat groundwater and will provide adequate treatment to meet regulatory

requirements and finished water goals; however, the square, shallow configurations of the basins will not

allow for full optimization of the physical treatment processes.

Figure 3-1

Wichita, KS

Alternative No. 1a – Retrofit

Existing Sedimentation Basins

0 25 50 100

Scale

Water Supply

Existing Aeration & Rapid Mix

New Solids Contact Clarifier Equipment

New Flocculation Bypass Channel

LEGEND

Center Cone

Effluent Lauders

New Pipe/Channel



3.1.2 Alternative No. 1b In addition to the improvements listed for Alternative No. 1a, Alternative No. 1b includes more extensive

repairs to the existing basins, installation of tube settlers in addition to the solids contact clarifier

equipment, replacement of the existing rapid mix with a new flash mix system, and improvements to

piping and infrastructure in the East WTP to increase the hydraulic capacity of other processes to match

the treatment capacity of the basins. A general depiction of this alternative is shown in Figure 3-2.

Installation of a new flash mix system will increase chemical efficiency by providing optimal mixing

conditions for ferric. Structural rehabilitation of the existing basins—including repairs to the walls and

replacement of the grout layer of the basin floor—will increase the life expectancy of the basins to

approximately 20 years. Installation of tube settlers will further expand treatment capacity of the basins

due to an increase in the allowable overflow rate, raising the treatment capacity of the East WTP to 70

MGD. In order for the hydraulic capacity of the East WTP to match this treatment capacity some of the

existing piping will need to be altered or replaced and the required alterations are discussed in the

following section.

3.1.2.1 Hydraulic Capacity A cursory evaluation of the existing hydraulic profile was performed and potential limitations were

identified. A thorough hydraulic evaluation should be performed once an alternative is selected for

design. Figure 3-3 highlights piping that may be undersized if flow through the plant is increased.

Specifically, the piping through headworks and the aeration system appear to be too small to carry

increased flow.

Figure 3-4 shows the velocity through each pipe in the East WTP as flow through the plant is increased.

Typically, flow velocity within the pipes should fall within the range of 0.5 ft/sec to 8.0 ft/sec to prevent

particles from settling in the piping at low velocities but also reduce the amount of head loss in the pipe at

high velocities. In Figure 3-4, the headworks and aeration piping both exceed a velocity of 8.0 ft/sec at

relatively low flows compared to the rest of the piping in the plant. These velocities were used to identify

the undersized piping highlighted in Figure 3-3.

Figure 3-3 also notes velocities for the scenario where flow is split between the aeration system and the

aerator bypass piping. This option greatly reduces the velocity in both pipes and could reduce capital cost

by reducing the need for additional aerators or modification to the aerator piping; however, bypassing half

of the influent flow around the aerators would slightly increase the amount of iron in the finished water.

Figure 3-2

Wichita, KS

Alternative No. 1b – Retrofit

Existing Sedimentation Basins

0 25 50 100

Scale

Water Supply

Existing Aeration

New Solids Contact Clarifier Equipment


LEGEND

Center Cone

Effluent Lauders

New Pipe/Channel

Pump

Tube Settlers

New Flash Mix

Figure 3-3

East WTP Hydraulic

Bottlenecks

Wichita, KS

Label Size Description

A 48” Headworks

B 36” Headworks

C 24” Headworks

D 30” Aeration Influent

E 14” Aeration Unit Influent

F 72” Rapid Mix Channel

G 72” New Flocculation Bypass Channel

H 72” East Basin Influent Channel

I 72” West Basin Influent Channel

J 60” East Basin Effluent Channel

K 72” Filter Influent Flume

L 24” Aerator Bypass

Aeration

Raw Water

B C D E

G

East Basin

To Filters L

F

Rapid Mix

Secondary Sedimentation

H

I

J

K

A

West Basin

- No Issues

- Potential Bottleneck

0

2

4

6

8

10

12

14

16

18

20

30 35 40 45 50 55 60 65 70 75 80

Ve

loci

ty (

ft/s

)

Flow (MGD)

A - 48" Headworks (50 ft)

B - 36" Headworks (27 ft)

C - 24" Headworks (30 ft)

D - 30" Aeration Influent (20 ft)

E - 14" Aeration Unit Influent (32 ft)

F - 72" Rapid Mix Channel (48 ft)

G - 54" Rapid Mix Pipe (92 ft)

H - 72" West Basin Influent Channel (54 ft)

I - 72" East Basin Influent Channel (250 ft)

J - 60" East Basin Effluent Channel (148 ft)

K - 72" Filter Influent Flume (65 ft)

X

X2

X3

L - 24" Aerator Bypass 1/2 Full (40 ft)

M- 14" Aerator Unit Influent 1/2 Full (32 ft)

C

D

L

B

A E

G

Maximum Recommended

A

K M

H F

I

J

Pipes/Channels

Aeration Bypass Scenario

Figure 3-4

East WPT Pipe Velocities

Wichita, KS

= Potential Bottleneck



Assessing headloss in each portion of the system is also very important when identifying potential

bottlenecks. Headlosses through various portions of the East WTP are shown in Figure 3-5 for flows of

30 to 80 MGD. As previously identified, piping in the headworks and aerator portions of the plant have

the highest potential for creating hydraulic bottlenecks. The losses shown include assumptions of

headlosses through the Bailey Valve (a sleeve valve used for flow and pressure control) and Venturi Flow

Meter located on Line C and A, respectively. Additional information will need to be collected on these

items during a detailed hydraulic audit in order to determine the modifications required. Evaluation of

upstream pumping capacity will also be required in order to determine the available head. Another

potential bottleneck is the new 54” Rapid Mix Pipe which will be used to bypass the flocculation basin;

therefore, the size of this pipe will need to be increased if a high capacity alternative is selected. Review

of the hydraulic profile also indicated that flooding of the effluent weirs may occur in the existing basin

due to capacity of the downstream pipes and channels; new basins will likely need to be designed with

weir levels higher than the existing configuration or downstream hydraulics improved.

3.2 Alternative No. 2 Alternative No. 2 is based on demolishing the existing sedimentation basins and replacing them with new,

circular, solids contact clarifiers. This option is split into two sub-alternatives with varying treatment

capacities. Figure 3-6 depicts the general layout for this option.

3.2.1 Alternative No. 2a Alternative No. 2a will include replacement of rapid mix with a new flash mix system, bypass of the

existing flocculation basin, demolition of the two existing sedimentation basins, and construction of two

new treatment basins. The rapid mix system and flocculation basin bypass will be as described in

Alternative No. 1b and will provide optimal activation of ferric and protection of floc from high shear

stresses. The new basins will be circular and designed as solids contact clarifiers. The basins will be

approximately 28 ft deep (sidewater depth of 26 ft) with a diameter of 117 ft, designed for a capacity of

25 MGD, each. Equipment in the basin will include a draft tube, center cone, sludge collection rake,

radial launders and effluent collection trough. The solids contact clarifiers will be strategically designed

and will provide optimal softening treatment for groundwater. Treatment of blended groundwater and

surface water will also be possible with this configuration.

3.2.2 Alternative No. 2b Alternative No. 2b will include the same modifications as described in Alternative No. 2a, but will also

include installation of tube settlers in addition to the solids contact clarifier equipment. As mentioned

previously, the use of tube settlers allows for increased overflow rates in the basins. This will allow the

0.7 0.5 0.3 0.7 0.2 3.1

0.0 0.0

45.3

40.9

71.7

3.9

25.2

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Second

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East B

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30 MGD 40 MGD

50 MGD 60 MGd

70 MGD 80 MGD

Figure 3-5

Headloss in East WPT

Wichita, KS

Note: 25 ft (10 psi) headloss assumed for Bailey Valve in Line C and for Venturi Flow Meter in Line A. Further information for these items is required.

Figure 3-6

Wichita, KS

Alternative No. 2 – New

Solids Contact Clarifiers

0 25 50 100

Scale

Solids Contact Clarifier Basins

Demo

New Pipe/Channel

Pump

LEGEND

Water Supply

Existing Aeration

25 MGD

25 MGD

New Flash Mix

New Flash Mix

New Aeration

New Solids Contact Clarifier




same size basins to be rated for approximately 40 MGD each, increasing total treatment capacity of the

East WTP to 80 MGD. Similarly to Alternative No. 1a, modifications to piping will be required to

increase hydraulic capacity to match the treatment capacity. This alternative requires a slightly longer

construction phase and higher capital cost, but will allow the Main WTP to meet the average maximum

day demand using only groundwater for 7 to 9 of the year.

3.3 Alternative No. 3 Alternative No. 3 consists of building an entirely new WTP at a separate location. This alternative

provides the greatest degree of optimization, longest lifespan, and highest ultimate capacity, but will

require the highest capital investment.

A conceptual process schematic for this alternative is shown in Figure 3-7. The WTP includes aeration for

oxidation of iron and removal of carbon dioxide, flash mixing for coagulant activation, solids contact

clarifiers for softening and sedimentation, recarbonation, and UF/MF membranes for filtration. The WTP

will have an initial capacity of 60 MGD, with final firm capacity of 120 MGD. Each solids contact

clarifier is designed for a capacity of 20 MGD, with three basins in the initial phase and a fourth for future

expansion. Tube settlers could be installed in a future expansion to raise capacity for each clarifier to 40

MGD, providing the 120 MGD firm capacity for the WTP. The membrane portion of the facility could

also be phased, with the initial building sized to house 80 MGD of membranes. During future expansion,

a second membrane building could be added to raise the membrane capacity to 120 MGD.

3.4 Comparison of Alternatives The improvements included in Alternative No. 1a will allow the East WTP to treat groundwater and will

require the lowest capital investment of the potential alternatives; however, the life expectancy of this

alternative could be relatively short, approximately 10 years, depending on the condition of the basins and

the need for more extensive structural repairs in addition to the surface repairs that are included in this

alternative. Modifications to piping and infrastructure are not included; therefore, although the treatment

capacity of the basins will be increased to 50 MGD, the maximum capacity of the East WTP will remain

at 30 MGD. The required time for design and construction of this alternative is estimated to be a total of

approximately 16 months. This alternative will allow the WTP to treat groundwater within a fairly short

timeframe, satisfying the immediate need, but will not provide sufficient capacity for high demand

periods and is not likely to last for the anticipated duration of the Main WTP’s usable life.

In comparison to Alternative No. 1a, Alternative No. 1b will provide further enhancement of treatment

due to the replacement of rapid mix with a more highly optimized flash mix system. The additional

Figure 3-7

Wichita, KS

Alternative No. 3 – New

Water Treatment Plant

Am

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Future



hydraulic and structural modifications, along with tube settlers, make the capital cost of this option higher

than Alternative No. 1a, but provide additional plant capacity and extended life expectancy. Total design

and construction time for this alternative is estimated to be 20 months.

Alternative No. 2a will provide excellent treatment, increase the treatment capacity of the East WTP to 50

MGD, and extend life expectancy of the East WTP to nearly 50 years. New piping will be installed in

this option to increase the hydraulic capacity. Time frame for completion of design and construction of

this alternative is estimated to be 20 months, which is similar to that of Alternative No. 1b. Alternative

No. 2a will provide the City with long-term flexibility, while still allowing the City to quickly meet the

immediate need for supply line repairs.

Alternative No. 2b is very similar to Alternative No. 2a. The addition of tube settlers and installation of

slightly larger piping will provide a total flow capacity of approximately 80 MGD. These additional

items will increase capital cost of Alternative No. 2b compared to Alternative No. 2a, but estimated time

for design and construction is still 20 months.

While Alternative No. 3 will provide the highest degree of optimization for treatment of 100% EBWF,

there are many other considerations associated with this alternative that are not be present with

Alternatives No. 1 and No. 2. First, this alternative would require acquisition of new property large

enough to support the full build-out footprint of the WTP, which is estimated to be 100 to 150 acres

depending on site conditions and WTP design. Second, additional infrastructure in both the supply and

distributions systems would be require to connect this WTP to the City’s system. Third, the time required

for site selection, WTP design, and construction would make the timeline for this alternative much longer

than the other two alternatives and would not address the immediate need the City has for performing

repairs on existing supply lines. Finally, in consideration of the City’s search for additional water

supplies to meet future demands, it is likely in the City’s interest to construct a new WTP after the new

water sources have been identified, allowing the WTP to be optimized and designed around the particular

characteristics of those sources.

Main Water Treatment Plant Improvements Chemical Feed System Improvements


4.0 CHEMICAL FEED SYSTEM IMPROVEMENTS

4.1 Polymer System The existing polymer system consists of eight total blending units. The system has adequate capacity but

all blending units are aging. As with all aging infrastructure, frequent repairs are required, particularly for

the polymer feed pumps. The blending units utilize LMI – Milton Roy pumps which are very commonly

used for polymer feed applications. WTP maintenance crews frequently rebuild these pumps, but the

pumps are now obsolete and spare parts are no longer available. The on-going need to rebuild these

pumps will deplete the WTP’s inventory of spare parts, limiting the timeframe for which these pumps

may continue to be used. Once spare parts are depleted, pump failure will result in inadequate capacity to

feed polymer.

Plant staff has considered replacing only the pump on each of the blending units and re-using the

remaining portions of the system. Based on information provided by the manufacturer, this approach is

not recommended. Removal and replacement of the pumps is difficult to accomplish due to space

constraints and could ultimately cost more than replacing the entire unit. Therefore, replacement of all

eight blending units with new blending units is recommended.

Polymer storage tanks and feed piping were also evaluated. At this time the storage tanks and piping

appear to be in acceptable condition and are not in need of replacement. Minor pipe replacement may be

required in order to facilitate installation of new blending units.

Figure 4-1: Existing Polymer Blending Units



4.2 Lime System The existing lime system consists of three storage silos, four paste lime slakers, and a gravity conveyance

system constructed of PVC piping and steel troughs. Of the four slakers, two are used for the Central

WTP (each with a capacity of 4,000 lbs/hr), and two are used for the East WTP (each with a capacity of

2000 lbs/hr). The total and firm capacities of these systems are sufficient for currently dosing; however,

the higher lime doses required for treatment of 100% groundwater and the proposed increase in flow

capacity of the East WTP will require increased feed capacity for the East WTP.

Paste slakers often require a larger amount of maintenance and spare parts can be difficult to obtain. The

existing slakers at the WTP are old and require frequent maintenance. All four units are currently

working, but are in poor condition. Furthermore, the paste slaker design does not provide optimal slaking

conditions for temperature, water/lime ratio, or reaction time. These items are critical to producing high

quality, reactive lime slurry that is able to utilize the full chemical potential of the product. As the

conditions move farther away from the optimal point, the effectiveness of the lime decreases, requiring

more product to produce similar results and leading to wasted chemical.

Replacement of the existing slakers with new equipment is recommended. In order to generate higher

quality lime and increase usage efficiency, Tekkem batch slaker systems are recommended to replace the

existing past slakers. These batch slaking systems are designed to provide optimal slaking conditions and

to produce a lime slurry with high reactivity and low turbidity. System capacity should be increased to

provide sufficient capacity for treatment of 100% EBWF in the East WTP.

4.3 Ferric System The ferric system consists of two ferric sulfate feeders. These feeders are in moderate working condition

and have sufficient capacity for current operation of the WTP with blended water supply. However, for

the treatment of 100% groundwater, ferric dose will increase 3 to 5 times higher than the current dose.

The combined capacity of the two units is capable of meeting this demand, but no redundancy is

provided. Therefore, it is recommended that the existing feeders be replaced and the system’s firm

capacity be increased to match the new dosing requirements.

4.4 Chlorine System The existing chlorine feed system includes five chlorinators: three Wallace & Tiernan units and two

Portacel brand chlorinators. The total capacity of these units is adequate; however, all systems are aging

and require frequent repairs and/or rebuilds. The three Wallace & Tiernan chlorinators are nearly

obsolete and require frequent repair. The two Portacel units are newer than the Wallace & Tiernan units,



but still require rebuilds on a regular basis. The Wallace & Tiernan units are still supported by the

company, but Portacel no longer exists as a manufacturer and it is expected that spare parts will soon

become difficult to obtain.

In addition to the chlorinator units, the piping system is aging and is poorly configured. The piping

system in the chlorinator rooms does not allow for easy isolation of each chlorinator, making it difficult to

perform maintenance on the units.

Due to the aging nature of the entire chlorine feed system, it is recommended that all chlorinators be

replaced. It is also recommended that piping in the chlorinator rooms be replaced and/or reconfigured to

allow for isolation and maintenance of the chlorinators.

Figure 4-2: Existing Wallace & Tiernan Chlorinator

4.5 Ammonia System The existing ammonia feed system includes four ammoniators manufactured by Wallace & Tiernan. All

units are nearly obsolete and require frequent repairs. Total system capacity is adequate for the WTP, but

only two of the ammoniators are currently functional and the loss of one unit would result in inadequate

feed capacity. In addition, the feed rate through the units is steadily decreasing. WTP maintenance crews

have cleaned piping, made repairs, and consulted with the manufacturer, but the feed rate continues to

decrease for unknown reasons.

Similar to the chlorine feed system, the piping in the ammoniator room is not ideally configured. Piping

does not allow for isolation of each unit, making maintenance difficult.



Figure 4-3: Existing Wallace & Tiernan Ammoniators

The ammonia storage tanks and vaporizers were also considered. The system includes two storage tanks,

each with a vaporizer heating element to turn the anhydrous ammonia into a gas before it is transferred to

the ammoniators. The bulk storage tanks will require inspection by a contractor to determine their

condition. The vaporizers, however, need immediate attention. Currently, only one vaporizer is

functioning and its associated tank is being heated with blankets and small space heaters. Replacement

parts for this unit are on order, but have a long lead time and shipping time from overseas. The limited

availability of these spare parts makes repairs difficult.

Due to the aging nature of the entire ammonia feed system, it is recommended that all four ammoniators

be replaced. It is also recommended that piping in the ammoniator rooms be replaced and/or reconfigured

to allow for isolation and maintenance of the ammoniators. In addition, it is recommended that new

ammonia vaporizers be installed or that spare heating elements be purchased and stored until needed.

Inspection of the ammonia bulk storage tanks by an outside contractor is also recommended.



Figure 4-4: Existing Ammonia Storage Tank and Vaporizer

Main Water Treatment Plant Improvements Opinions of Probable Cost


5.0 OPINIONS OF PROBABLE COST

Opinions of project cost are based on conceptual designs of the required facilities and consist of

construction and other cost allowances including contingency, engineering, surveying, legal and other

related costs. Construction cost estimates are based on current construction cost levels (February 2014

ENR Kansas City Construction Cost Index = 10892.12). The opinions of probable cost provided in this

report are based primarily on our experience and judgment as a professional consulting firm combined

with information from past project experience, vendors, and published sources. BMcD has no control

over weather, cost and availability of labor, material and equipment, labor productivity, construction

contractor’s procedures and methods, unavoidable delays, construction contractor’s methods of

determining prices, economic conditions, government regulations and laws (including the interpretation

thereof), competitive bidding or market conditions and other factors affecting such opinions or

projections; consequently, the final project costs may vary from the opinion of costs provided in this

report, and funding needs must be carefully reviewed prior to making specific financial decisions or

establishing final budgets.

The Construction cost estimates presented in this chapter include 30% for General Contractor markups,

25% contingency, and 20% for additional costs (engineering, legal, Owner administration, etc.).

Additional costs for Alternative 3 are estimated to be a slightly lower percentage of 15% due to the high

overall construction cost. Construction costs provided for each alternative do not account for special

subsurface conditions. Additional costs may be incurred if subsurface conditions require deep

foundations, dewatering systems, or extensive excavation of rock.



5.1 Alternative No. 1 – Basin Rehabilitation

5.1.1 Alternative No. 1a – Minor Repairs Table 5-1 gives an opinion of probable cost for the improvements associated with Alternative No. 1a.

Basin repairs and solids contact clarifier equipment are the main cost items for this alternative.

Table 5-1: Alternative No. 1a Opinion of Probable Cost

Item Unit Unit Cost Quantity Cost Basin Rehabilitation

Basin 1 Concrete Repairs LS $ 150,000 1 $ 150,000 Basin 1 Equipment Replacement LS $ 810,000 1 $ 810,000 Basin 2 Concrete Repairs LS $ 150,000 1 $ 150,000 Basin 2 Equipment Replacement LS $ 1,250,000 1 $ 1,250,000

General

Piping LS $ 100,000 1 $ 100,000 Electrical/Controls LS $ 70,000 1 $ 70,000 Site Work LS $ 30,000 1 $ 30,000

Subtotal

$ 2,560,000 General Contractor Markups

30% $ 770,000

Subtotal $ 3,330,000 Contingency

25% $ 830,000

Other Cost 20% $ 830,000 Alternative No. 1a Total $ 4,990,000



5.1.2 Alternative No. 1b – Major Repairs Table 5-2 gives an opinion of probable cost for the improvements associated with Alternative 1b. These

improvements include significant structural repairs to the existing basins, addition of solids contact

clarifier equipment and tube settlers, and upgrading the rest of the East WTP to a capacity of

approximately 70 MGD.

Table 5-2: Alternative No. 1b Opinion of Probable Cost

Item Unit Unit Cost Quantity Cost Basin Rehabilitation Basin 1 Concrete Repairs LS $ 300,000 1 $ 300,000 Basin 1 Equipment Replacement LS $ 810,000 1 $ 810,000 Basin 1 Tube Settlers LS $ 800,000 1 $ 800,000 Basin 2 Concrete Repairs LS $ 300,000 1 $ 300,000 Basin 2 Equipment Replacement LS $ 1,250,000 1 $ 1,250,000 Basin 2 Tube Settlers LS $ 1,490,000 1 $ 1,490,000

General

Piping LS $ 200,000 1 $ 200,000 Electrical/Controls LS $ 70,000 1 $ 70,000 Site Work LS $ 30,000 1 $ 30,000

Subtotal

$ 5,250,000 General Contractor Markups 30% $ 1,580,000 Subtotal $ 6,830,000 Contingency 25% $ 1,710,000 Other Costs 20% $ 1,710,000 Alternative No. 1b Total $ 10,250,000



5.2 Alternative 2 – Basin Replacement

5.2.1 Alternative No. 2a – Solids Contact Clarifiers An opinion of probable cost for replacing the existing sedimentation basins with solids contact clarifiers

is given in Table 5-3. This table also includes the cost to replace piping in order for all designed

processes to operate efficiently and at the new design capacity of 50 MGD.

Table 5-3: Alternative No. 2a Opinion of Probable Cost

Item Unit Unit Cost Quantity Cost Rapid Mix

Equipment (Pumps, Injection, Sidestream Piping/Valves) EA $ 105,000 2 $ 210,000

Concrete Pad/Pump Housing EA $ 45,000 2 $ 90,000 New Solid Contact Clarifiers

Basin Concrete EA $ 1,600,000 2 $ 3,200,000 Basin Equipment EA $ 810,000 2 $ 1,620,000 General

Piping LS $ 600,000 1 $ 600,000 Electrical/Controls LS $ 250,000 1 $ 250,000 Site Work (Demolition & Excavation) LS $ 2,300,000 1 $ 2,300,000

Subtotal


30% $ 2,480,000

Subtotal

$ 10,750,000

Contingency 25% $ 2,690,000 Other Costs 20% $ 2,690,000 Alternative No. 2a Total $ 16,130,000



5.2.2 Alternative No. 2b – Solids Contact Clarifiers & Tube Settlers Table 5-4 gives an opinion of probable cost for Alternative No. 2b, which includes all of Alternative No.

2a plus tube settlers and the additional hydraulic modifications required to increase the capacity of the

East WTP to 80 MGD.

Table 5-4: Alternative No. 2b Opinion of Probable Cost

Item Unit Unit Cost Quantity Cost Rapid Mix

Equipment (Pumps, Injection, Sidestream Piping/Valves) EA $ 105,000 2 $ 210,000

Concrete Pad/Pump Housing EA $ 45,000 2 $ 90,000 New Solid Contact Clarifiers

Basin Concrete EA $ 1,600,000 2 $ 3,200,000 Basin Equipment & Tube Settlers EA $ 1,500,000 2 $ 3,000,000 General

Piping LS $ 700,000 1 $ 700,000 Electrical/Controls LS $ 250,000 1 $ 250,000 Site Work (Demolition & Excavation) LS $ 2,300,000 1 $ 2,300,000

Subtotal


30% $ 2,930,000

Subtotal

$ 12,680,000

Contingency 25% $ 3,170,000 Other Costs 20% $ 3,170,000 Alternative No. 2b Total $ 19,020,000



5.3 Alternative 3 – New Treatment Plant Table 5-5 gives an opinion of probable cost associated with building a new WTP on another site. This

opinion only includes the cost items for the WTP--land acquisition, pumps stations, supply piping, and

distribution piping are not included. The costs shown in Table 5-5 are intended to provide a point for

comparison of this alternative to Alternatives No. 1 and No. 2. The new WTP will have an initial

capacity of 40 MGD with the ability to be expanded to 160 MGD. Costs shown in Table 5-5 are for the

full build-out of 160 MGD. The estimated cost for the initial phase to provide 40 MGD is $204,000,000.

Table 5-5: Alternative No. 3 Opinion of Probable Cost

Item Unit Unit Cost Quantity Cost

Unit Process

Aeration (Outdoor cascading) LS $ 1,300,000 1 $ 1,300,000 Rapid Mix (Equipment and Structure) EA $ 500,000 2 $ 1,000,000

Solids Contact Clarifier Equipment & Tube Settlers EA $ 4,800,000 4 $ 19,200,000

Re-carbonation EA $ 1,200,000 2 $ 2,400,000 Membrane Equipment LS $ 72,800,000 1 $ 72,800,000 Clearwell/High Service Pump Station LS $ 10,000,000 1 $ 10,000,000 Residuals Management LS $ 25,000,000 1 $ 25,000,000 Chemical Feed Systems LS $ 15,600,000 1 $ 15,600,000

General

Buildings (Admin, Electrical, Membrane) EA $ 2,000,000 3 $ 6,000,000 Basins (Solids Contact Clarifiers) EA $ 1,600,000 4 $ 6,400,000

Structures (Raw Water Splitting & Settled Water Blending) LS $ 1,000,000 1 $ 1,000,000

Piping LS $ 6,100,000 1 $ 6,100,000 Electrical/Controls LS $ 50,000,000 1 $ 50,000,000 Site Work LS $ 12,000,000 1 $ 12,000,000

Subtotal


30% $ 68,640,000

Subtotal $ 297,440,000 Contingency 25% $ 74,360,000 Other Costs 15% $ 55,770,000 Alternative No. 3 Total $ 427,570,000



5.4 Chemical Feed Improvements Recommended improvements to the chemical feed systems include replacement of equipment for the

lime, ferric, polymer, chlorine, and ammonia systems, as well as modifications to piping for the chlorine

and ammonia systems. The opinion of probable cost for these improvements is contained in Table 5-6.

Table 5-6: Chemical Feed Improvements Opinion of Probable Costs

Item Unit Unit Cost Quantity Cost

Chemical System

Tekkem Lime Slaker System LS $ 1,000,000 1 $ 1,000,000 Ferric Feed System LS $ 200,000 1 $ 200,000 Polymer Feed System LS $ 120,000 1 $ 120,000 Chlorine Feed System LS $ 250,000 1 $ 250,000 Ammonia Feed System LS $ 220,000 1 $ 220,000

Subtotal


30% $ 540,000

Subtotal $ 2,330,000 Contingency 25% $ 580,000 Other Costs 20% $ 580,000 Chemical Feed Improvements Total $ 3,490,000

Main Water Treatment Plant Improvements Conclusions


6.0 CONCLUSIONS

Increasing demand, supply limitations, and necessary repairs to supply lines require the Main WTP to be

capable of treating only surface water and/or only groundwater. Process evaluation, bench-scale testing,

and full-scale testing has shown that the Main WTP is designed for surface water and is not capable of

treating solely groundwater for extended periods of time. Treatment of solely groundwater at the existing

Main WTP will result in high settled water turbidities and solids carryover to downstream processes.

This will lead to stress loading of the filters and eventually solids deposition in the clearwells and

distribution piping. Therefore, some type of modifications to the current processes and/or equipment is

required. Modifying the East WTP with solids contact clarifiers will allow for treatment of 100% EBWF,

100% Cheney, or various blending scenarios. This will provide the City with long-term treatment

flexibility to respond to changing raw water availability from year to year. Due to basin configuration,

capacity and age, the East WTP has been identified as the best location to make the modifications

necessary to treat groundwater.

Three alternatives have been presented to provide treatment of 100% EBWF. These alternatives are

divided into sub-alternatives to create more choices for the City in terms of capacity, capital cost, and

construction timeframe. The scope of each alternative is summarized below:

• Alternative No. 1 – Modifications to Existing Sedimentation Basin in the East WTP

o Alternative No. 1a – This alternative includes bypassing of existing flocculation, minimal

repairs to the existing sedimentation basins, and installation of solids contact clarifier

equipment in the sedimentation basins.

o Alternative No. 1b - In addition to the improvements listed for Alternative No. 1a, this

alternative includes replacement of the existing rapid mix with a new flash mix system,

more extensive repairs to the existing basins, installation of tube settlers in addition to the

solids contact clarifier equipment, and improvements to piping and infrastructure to

increase the hydraulic capacity.

• Alternative No. 2 – Demolition of Existing Sedimentation Basins in the East WTP and

Installation of New Solids Contact Clarifiers

o Alternative No. 2a – This alternative includes replacement of rapid mix with a new flash

mix system, bypass of the existing flocculation basin, demolition of the two existing



sedimentation basins, construction of two new solids contact clarifiers, improvements to

piping and infrastructure to increase the hydraulic capacity.

o Alternative No. 2b – In addition to the improvements listed for Alternative No. 2a, this

alternative includes installation of tube settlers in the solids contact clarifiers and

additional piping modification to further increase capacity of the East WTP.

• Alternative No. 3 – Construction of New WTP at a New Location

o This alternative includes construction of a new WTP designed specifically for

groundwater treatment. Treatment processes will include aeration, flash mix, solids

contact clarifiers, recarbonation and membranes.

The additional life expectancies provided, overall capacities, required capital investments, and project

durations vary for each alternative. A summary of these items is contained in Table 6-1.

Table 6-1: Comparison of Alternatives

1. Estimated duration begins with issuance of Bid Documents and ends with Substantial Completion. Bid Phase is assumed to be 2 months and is included in construction duration.

2. Dependent on subsurface conditions. Duration may be longer if deep foundations are needed or significant excavation of rock is required.

3. Estimates for water treatment plant only. Does not account for land acquisition, water supply, high service pump station, distribution system, etc.

In addition to the modifications required for the selected alternative, modifications to the chemical feed

systems at the Main WTP are recommended in order to maintain treatment capability for all treatment

scenarios. Age and condition of all the chemical systems—lime, ferric, polymer, chlorine, and

ammonia—require that the systems be updated in order to continue operation. Increased flow capacity at

the East WTP and higher chemical doses requirements for groundwater treatment will require some

Alternative Approximate Construction

Cost

Final Capacity

Added Basin Life

Expectancy

Approximate Design

Duration

Approximate Construction

Duration1

No. 1a $4,990,000 40 MGD 10 yrs 4 mos 12 mos

No. 1b $10,250,000 70 MGD 20 yrs 6 mos 14 mos

No. 2a $16,130,000 50 MGD 50 yrs 6 mos 14 mos

No. 2b $19,020,000 80 MGD 50 yrs 6 mos 14 mos

No. 3 $427,570,0003 120 MGD 50 yrs 12-18 mos2 24-36 mos2



additional capacity in the lime, ferric, and polymer systems. These improvements are anticipated to cost

approximately $3,490,000 and the total time for design and construction is estimated to be a minimum of

15 months, under standard design and equipment procurement schedule.

Burns & McDonnell World Headquarters 9400 Ward Parkway Kansas City, MO 64114 Phone: 816-333-9400 Fax: 816-333-3690 www.burnsmcd.com

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