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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
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City of Wichita TOC-2 Burns & McDonnell
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
Main Water Treatment Plant Improvements Table of Contents
City of Wichita TOC-3 Burns & McDonnell
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
Main Water Treatment Plant Improvements Table of Contents
City of Wichita TOC-4 Burns & McDonnell
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
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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.
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City of Wichita 1-2 Burns & McDonnell
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
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City of Wichita 1-5 Burns & McDonnell
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.
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City of Wichita 1-6 Burns & McDonnell
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
> 3-log removal/inactivation
> 3-log removal/inactivation
4-log removal/inactivation
3-log removal/inactivation
2-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;
Main Water Treatment Plant Improvements Introduction
City of Wichita 1-7 Burns & McDonnell
• 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
Main Water Treatment Plant Improvements Introduction
City of Wichita 1-8 Burns & McDonnell
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;
Main Water Treatment Plant Improvements Introduction
City of Wichita 1-9 Burns & McDonnell
• 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
City of Wichita 2-1 Burns & McDonnell
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
Main Water Treatment Plant Improvements WTP Evaluation
City of Wichita 2-2 Burns & McDonnell
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
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City of Wichita 2-3 Burns & McDonnell
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
Main Water Treatment Plant Improvements WTP Evaluation
City of Wichita 2-7 Burns & McDonnell
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)
Main Water Treatment Plant Improvements WTP Evaluation
City of Wichita 2-10 Burns & McDonnell
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
Jar No. (mg/L) (mg/L) (mg/L)
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
Jar Test 2 – 100% EBWF
– 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
Jar Test 3 – 100% EBWF
– 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
Jar No. (mg/L) (mg/L) (mg/L)
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
Main Water Treatment Plant Improvements WTP Evaluation
City of Wichita 2-16 Burns & McDonnell
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
Jar No. (mg/L) (mg/L) (mg/L)
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
Jar No. (mg/L) (mg/L) (mg/L)
1 80 20 3
2 80 30 3
3 80 40 3
4 80 50 3
5 80 60 3
6 80 70 3
Main Water Treatment Plant Improvements WTP Evaluation
City of Wichita 2-19 Burns & McDonnell
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
Solids Contact Clarifier
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
Main Water Treatment Plant Improvements WTP Evaluation
City of Wichita 2-23 Burns & McDonnell
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
Main Water Treatment Plant Improvements WTP Evaluation
City of Wichita 2-24 Burns & McDonnell
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
City of Wichita 3-1 Burns & McDonnell
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
Main Water Treatment Plant Improvements East WTP Improvement Alternatives
City of Wichita 3-3 Burns & McDonnell
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
New Flocculation Bypass Channel
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
Main Water Treatment Plant Improvements East WTP Improvement Alternatives
City of Wichita 3-7 Burns & McDonnell
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
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
Second
ary
Basin
In
flu
ent
Flu
me
K -
60"
East B
asin
Eff
lue
nt C
han
nel
East B
asin
Efflu
ent W
eir
J -
72"E
ast B
asin
Influen
t C
hann
el
Second
ary
Basin
In
flu
ent
Flu
me
West B
asin
Eff
lue
nt C
han
nel
West B
asin
Eff
lue
nt W
eir
I -
72"
We
st
Ba
sin
In
flu
ent
Cha
nne
l
H -
54"
Rap
id M
ix P
ipe
G -
72
" R
apid
Mix
Cha
nne
l
Aera
tor
Colle
ction C
han
nel
Aera
tor
Wate
r Le
ve
l
E -
Ae
ratio
n U
nit I
nfluen
t (x
12)
D -
30"
Ae
ratio
n In
flu
ent
C -
24"
Hea
dw
ork
s
B -
36"
He
adw
ork
s P
ipin
g
A -
48"
He
adw
ork
s P
ipin
g
Head L
oss (
ft)
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
New Flocculation Bypass Channel
Main Water Treatment Plant Improvements East WTP Improvement Alternatives
City of Wichita 3-10 Burns & McDonnell
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
mo
nia
Ch
lori
ne
Alu
m/F
erri
c
Lim
e
Recarb UF/MF Membrane Modules
`
Clearwell
Pump Station
Aeration
Po
lym
er
Solids Contact Clarifier
Raw Water Splitting Structure
`
Ch
lori
ne
Settled Water
Blending Structure
`
Flash Mix
Ch
lori
ne
CO
2
Po
lyp
ho
sph
ate
Future
Future
Main Water Treatment Plant Improvements East WTP Improvement Alternatives
City of Wichita 3-12 Burns & McDonnell
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
City of Wichita 4-1 Burns & McDonnell
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
Main Water Treatment Plant Improvements Chemical Feed System Improvements
City of Wichita 4-2 Burns & McDonnell
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,
Main Water Treatment Plant Improvements Chemical Feed System Improvements
City of Wichita 4-3 Burns & McDonnell
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.
Main Water Treatment Plant Improvements Chemical Feed System Improvements
City of Wichita 4-4 Burns & McDonnell
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.
Main Water Treatment Plant Improvements Chemical Feed System Improvements
City of Wichita 4-5 Burns & McDonnell
Figure 4-4: Existing Ammonia Storage Tank and Vaporizer
Main Water Treatment Plant Improvements Opinions of Probable Cost
City of Wichita 5-1 Burns & McDonnell
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.
Main Water Treatment Plant Improvements Opinions of Probable Cost
City of Wichita 5-2 Burns & McDonnell
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
Main Water Treatment Plant Improvements Opinions of Probable Cost
City of Wichita 5-3 Burns & McDonnell
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
Main Water Treatment Plant Improvements Opinions of Probable Cost
City of Wichita 5-4 Burns & McDonnell
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
$ 8,270,000 General Contractor Markups
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
Main Water Treatment Plant Improvements Opinions of Probable Cost
City of Wichita 5-5 Burns & McDonnell
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
$ 9,750,000 General Contractor Markups
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
Main Water Treatment Plant Improvements Opinions of Probable Cost
City of Wichita 5-6 Burns & McDonnell
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
$ 228,800,000 General Contractor Markups
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
Main Water Treatment Plant Improvements Opinions of Probable Cost
City of Wichita 5-7 Burns & McDonnell
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
$ 1,790,000 General Contractor Markups
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
City of Wichita 6-1 Burns & McDonnell
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
Main Water Treatment Plant Improvements Conclusions
City of Wichita 6-2 Burns & McDonnell
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
Main Water Treatment Plant Improvements Conclusions
City of Wichita 6-3 Burns & McDonnell
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.
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