SOUTH WATER PLANT RAW WATER TRANSMISSION MAIN

City of Lancaster Division of Water

SOUTH WATER TREATMENT PLANT RAW WATER TRANSMISSION MAIN CLEANING PROJECT Preliminary Design Report

June 22, 2020

South Water Treatment Plant Raw Water Transmission Main Cleaning Project

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SOUTH WATER

TREATMENT PLANT

RAW WATER

TRANSMISSION MAIN

CLEANING PROJECT

Preliminary Design Report

Prepared for:

City of Lancaster

Division of Water

225 North Memorial Drive

Lancaster, OH 43130

Prepared by:

Arcadis U.S., Inc.

100 E Campus View Boulevard

Suite 230

Columbus

Ohio 43235-1447

Tel 614 985 9100

Fax 614 985 9170

Our Ref.:

30041927

Date:

June 22, 2020

This document is intended only for the use of

the individual or entity for which it was

prepared and may contain information that is

privileged, confidential and exempt from

disclosure under applicable law. Any

dissemination, distribution or copying of this

document is strictly prohibited.

Rita Jones

Project Engineer

Michael Pilutti, P.E.

Principal Engineer

Chad Dunn, P.E.

Project Manager


arcadis.com G:\Projects\0491000 - Lancaster OH\30041927 Lancaster South WTP Raw Water Main\500 Deliverables\Raw Waterline FINAL Report.docx

VERSION CONTROL

Issue Revision No Date Issued Page No Description Reviewed by

1 0 3/18/20 Draft C. Dunn

1 1 7/1/20 Final C. Dunn


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CONTENTS

Acronyms and Abbreviations ........................................................................................................................ iv

Executive Summary ....................................................................................................................................... 1

1 INTRODUCTION.................................................................................................................................. 1-1

1.1 Project Description ....................................................................................................................... 1-1

1.2 Project Justification ...................................................................................................................... 1-1

1.3 Background Information ............................................................................................................... 1-1

2 EXISTING CONDITIONS ..................................................................................................................... 2-1

2.1 Raw Water Production System .................................................................................................... 2-1

2.2 Raw Water Piping ........................................................................................................................ 2-2

3 MECHANICAL CLEANING ASSESSMENT ........................................................................................ 3-1

3.1 Mechanical Cleaning ................................................................................................................... 3-1

3.1.1 System Modifications........................................................................................................ 3-1

3.1.2 Pigging Facilities ............................................................................................................... 3-1

3.1.3 Intermediate Pig Launching Facilities............................................................................... 3-2

3.1.4 Solids Capture Facilities ................................................................................................... 3-2

3.1.5 Water Requirements, Sources, and Availability ............................................................... 3-2

3.1.6 Cleaning Operations ......................................................................................................... 3-3

3.2 Route and Alignment Planning .................................................................................................... 3-3

3.3 Special Crossings ........................................................................................................................ 3-4

3.4 Ice Pigging ................................................................................................................................... 3-4

4 FLUSHING ASSESSMENT ................................................................................................................. 4-1

4.1 Raw Water Transmission Main Flushing ..................................................................................... 4-1

4.2 Concentrate Force Main Flushing Alternatives ............................................................................ 4-1

4.2.1 Finished Water Connection Inside West Pipe Gallery ..................................................... 4-2

4.2.2 Raw Water Connection Inside West Pipe Gallery ............................................................ 4-2

4.2.3 Raw Water Connection From Yard .................................................................................. 4-3

5 REGULATORY AND PERMIT REQUIREMENTS ............................................................................... 5-1

6 PROJECT SCHEDULE ........................................................................................................................ 6-1

7 ECONOMIC EVALUATION OF ALTERNATIVES ............................................................................... 7-1


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7.1 Class of Estimate ......................................................................................................................... 7-1

7.1.1 Class 5 Cost Estimate ...................................................................................................... 7-2





7.2 Opinion of Probable Project Costs ............................................................................................... 7-3

7.2.1 Mechanical Cleaning ........................................................................................................ 7-3

7.2.2 Flushing Connection in Plant Yard ................................................................................... 7-4

8 CONCLUSION ..................................................................................................................................... 8-1

TABLES

Table 2-1 Raw Water Production Well Physical Characteristics ................................................................ 2-1

Table 2-2 Raw Water Production Well Operating Characteristics ............................................................. 2-2

Table 2-3 Raw Water Main Water Velocity ................................................................................................ 2-2

Table 2-4 Raw Water Main Volume ........................................................................................................... 2-3

Table 3-1 Raw Water Main Water Velocity ................................................................................................ 3-3

Table 4-1 Concentrate Force Main Flushing Flow and Volume ................................................................. 4-1

Table 6-1 Preliminary Project Schedule ..................................................................................................... 6-1

Table 7-1 Estimate Classification Matrix ................................................................................................... 7-1

Table 7-2 OPPC Raw Water Transmission Main Improvements and Mechanical Cleaning .................... 7-4

Table 7-3 OPPC Flushing Interconnection for Concentrate Force Main Outside in Yard ......................... 7-5

FIGURES

Figure 1-1 South Water Treatment Plant Overall Plan .............................................................................. 1-0

Figure 2-1 Typical Production Well ............................................................................................................ 2-0

Figure 2-2. South Wellfield Plan ................................................................................................................. 2-0

Figure 3-1 Raw Water Piping Modifications ............................................................................................... 3-0

Figure 3-2 Production Well S1 Enlarged Site Plan .................................................................................... 3-0



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Figure 3-6 Temporary Piping for Pigging Operations ................................................................................. 3-0

Figure 4-1 Flushing Connections for Concentrate Force Main Inside West Pipe Gallery .......................... 4-4

Figure 4-2 Flushing Connections for Concentrate Force Main Outside in Yard ........................................ 4-5


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ACRONYMS AND ABBREVIATIONS

AACE American Association of Cost Engineers

CFS Cubic Feet per Second

DI Ductile Iron

DIP Ductile Iron Pipe

Ea Each

Fe Iron

FPS Feet Per Second

GPM Gallons Per Minute

HDPE High Density Polyethylene

LF Linear Feet

LS Lump Sum

Mn Manganese

mg/L Milligrams per Liter

MG Million Gallons

MGD Million Gallons Per Day

MPWTP Miller Park Water Treatment Plant

NF Nanofiltration

OEPA Ohio Environmental Protection Agency

OPPC Opinion of Probable Project Cost

PDR Preliminary Design Report

PTI Permit-To-Install

RO Reverse Osmosis

SWTP South Water Treatment Plant


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EXECUTIVE SUMMARY

Raw water from the South Wellfield is conveyed to the South Water Treatment Plant (SWTP) through a

24-inch diameter transmission main. Since the plant was commissioned in 2004, oxidation of dissolved

iron (Fe) and manganese (Mn) has occurred in the production wells and raw water transmission main,

resulting in the deposition of colloidal Fe and Mn in the transmission main. Depending on the number of

production wells in use and the water velocity in the transmission main, iron sediment can be transported

to the plant where it can cause fouling of the cartridge filters, pressure filters, and reverse osmosis

system. This Preliminary Design Report (PDR) present a summary on methodologies that can be

implemented to clean the raw water transmission mains to remove solids and sediment that have

accumulated in the main over the past sixteen (16) years.

In addition, the concentrate force main conveys process residuals (RO concentrate and waste backwash

water from the pressure filters) from the SWTP to the City’s sanitary sewer system. This force main is a

14-inch diameter pipeline constructed of HDPE and is approximately 4.4 miles in length. Hydraulic

capacity in this force main has diminished somewhat since its construction and commissioning in 2004 as

a result of scale formation from the RO concentrate and from deposition of iron and manganese sediment

from the pressure filter waste backwash water. The force main requires periodic flushing to maintain

capacity, however, there is not currently a source of flushing water connected to the force main. This PDR

also provides options for constructing permanent improvements that allow for the periodic flushing of the

force main to prevent sediment buildup. The following is a summary of the key recommendations made

throughout this PDR.

CLEANING OPERATIONS

Modifications to the raw water system are required to accommodate flushing and/or mechanical cleaning

by pigging. This report examines methods for making modifications to accommodate flushing for

sediment removal, and for making modifications to accommodate mechanical pigging for solids removal.

It is recommended that modifications be made to the raw water transmission main to accommodate

flushing for several reasons including:

1. Fe and Mn sediment is relatively light and can be removed from the pipe using water flowing at a

velocity of 6 feet per second (FPS);

2. Construction of facilities to accommodate flushing are permanent allowing operators to easily

conduct flushing operations on an as-needed basis;

3. Construction of facilities to accommodate flushing are less expensive than those required to

accommodate pigging;

The modifications generally consist of the construction of a new segment of pipe connecting the

transmission main to the existing concentrate lagoon. This allows flushing water and sediment to be

discharged to the lagoon. The new connection will be made in the vicinity of the visitor car park on the

west side of the water plant building.

Construction of this pipe segment allows for an additional connection between the raw water transmission

main and the concentrate force main, allowing the use of raw water to periodically flush the force main.

Sediment accumulation in the concentrate force main can be removed using a sufficient flow of raw water


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to generate the necessary cleansing velocity. A separate branch connecting to the concentrate force

main to the raw water transmission main is required.

It is estimated that construction of connecting the raw water main to the existing concentrate force main

from the plant yard with an additional connection to connect the new raw water line to the lagoon to

accommodate periodic flushing of the concentrate force main using raw water amounts to approximately

$306,000 which includes a 25% contingency at this preliminary level.


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1 INTRODUCTION

The purpose of this Preliminary Design Report (PDR) is to evaluate existing conditions and recommend a

solution to clean the raw water transmission mains at the South Water Treatment Plant (SWTP) to

remove solids and sediment that have accumulated in the main over the past sixteen (16) years. If left in

place, the accumulated solids will adversely affect operations at the SWTP when the plant production rate

is increased above the current production rate. Prior to cleaning the existing raw water piping system,

permanent modifications will need to be constructed to not only accommodate the pigging operations, but

to facilitate periodic flushing of the mains in the future.

1.1 Project Description

This PDR presents a summary on how to implement the proposed solutions for constructing permanent

modifications for flushing or pigging. These recommendations are based on site visits, reviews of record

drawings and reports, and interviews with City staff regarding the current operation of the SWTP facilities.

The recommended implementation includes construction of permanent piping modifications to enable

flushing of the raw water transmission main and concentrate force main. Recommendations to modify

existing systems to facilitate pigging of the raw water transmission main are also presented.

1.2 Project Justification

Intermittent operation of the SWTP and operation of the plant at reduced capacity has resulted in under-

utilization of the SWTP and low flow rates in the raw water transmission main, resulting in low velocity and

subsequent deposition of oxidized iron (Fe) and manganese (Mn) sediment in the transmission main.

The City currently operates one RO array, resulting in a nominal plant production of 2 MGD. The City is

interested in activating a second RO array to increase plant production which will result in increased raw

water flows. This flow increase and resulting velocity increase in the transmission main will suspend Fe

and Mn sediment, transporting the sediment into the plant. The sediment will disrupt plant operation by

causing irreversible fouling of the cartridge filters and membrane elements. The increased sediment load

will also increase loading to the pressure filters, requiring more frequent backwashing.

Cleaning the sediment from the transmission main will mitigate the risk of fouling and will allow efficient

and continuous operation of the plant at production rates required to meets customer demand.

1.3 Background Information

The City of Lancaster owns, operates, and maintains the South Wellfield and the South Water Treatment

Plant. The SWTP was commissioned in 2004 and consists of 4 raw water production wells, cartridge

filtration and nanofiltration (NF) for dissolved solids removal and softening, pressure filtration for iron (Fe)

and manganese (Mn) removal, degasification for pH adjustment, disinfection and clearwell storage, and

high service pumping. The plant has a nominal capacity of 8 million gallons per day (MGD).

In addition to the SWTP, the City operates the Miller Park Water Treatment Plant (MPWTP), located in

downtown Lancaster, which draws water from the Miller Park wellfield, with numerous wells installed in



the sand and gravel deposits along the Hocking River. Because both plants operate simultaneously, the

SWTP has not been continuously operated at full capacity since its construction.

The SWTP has been operated intermittently since 2004 at a nominal production of approximately 2 MGD.

The plant has 4 separate membrane arrays, with only one array having been loaded with membrane

elements. During this time, the plant has experienced oxidation of dissolved iron in the production wells

and raw water main, resulting in the deposition of colloidal iron in the transmission main. Depending on

the number of production wells in use and the water velocity in the transmission main, iron sediment is

transported to the plant where it causes fouling of the cartridge filters, pressure filters, and RO system.

This project will address the cleaning of the raw water transmission main to remove existing iron

sediment, and will provide options for constructing permanent improvements that allow for the periodic

flushing of the transmission main to prevent sediment buildup.

The overall plant site along with the existing wellfield and raw water transmission main is illustrated by Figure 1-1 South Water Treatment Plant Overall Plan

.



Figure 1-1 South Water Treatment Plant Overall Plan

INDICATES EXISTING RAW WATER LINE

SW-X INDICATES SHEET NO. FROM

CONSTRUCTION DRAWING SET



2 EXISTING CONDITIONS

The main facilities at the SWTP include:

South well field consisting of four (4) raw water production wells;

Raw water transmission piping;

Water treatment plant and administration building

Clearwells;

High service pump station;

Lagoon for temporary storage of RO concentrate;

Vehicle storage and spare parts garage;

Finished water transmission main and concentrate force main.

The general location of these facilities is illustrated by Figure 1-1 South Water Treatment Plant Overall Plan

.

Cleaning of the raw water piping will require facilities for inserting pigs into the raw water piping at

appropriate points, temporary piping and a sufficient water supply to move the pigs through the piping at

an appropriate velocity, and facilities for capturing spent cleaning water and debris.

2.1 Raw Water Production System

The average daily demand for the City of Lancaster is approximately 4.5 MGD. The SWTP produces

approximately 2.0 MGD and the Miller Park WTP supplies the balance of the customer demand. During

normal operation, one production well is operated as this provides sufficient water supply to the SWTP.

In the future, the SWTP will need to operate at higher production rates when the Miller Park plant is either

shut down or operated at reduced production for planned upgrades.

The South Wellfield serves as the raw water source for the SWTP and consists of four (4) ground water

production wells. Each production well is equipped with a 125 HP submersible turbine pump operating at

a nominal capacity of 2115 GPM at 145 ft TDH. Each well has a 12-inch ductile iron discharge pipe that

is equipped with an electrically actuated check valve, a 12-inch x 12-inch wye for pig insertion, a fire

hydrant for periodic flushing, and a 12-inch gate valve for isolation of the production well from the system.

Table 2-1 summarizes the general characteristics of each production well. Figure 2-1 provides a typical

plan and section of each production well.

Table 2-1 Raw Water Production Well Physical Characteristics

Parameter Production Well No.

S1 S2 S3 S4

Grade elevation (MSL) 781.7 784.51 783.9 785.64

Borehole diameter (in) 36 24 24 24

Well depth (ft) 109 110 105 110




S1 S2 S3 S4

Screen diameter (in) 20 16 16 16

Screen elevation (MSL) 712.7 – 672.7 734.51 – 674.51 733.9 – 678.9 735.64 – 675.64

Pump elevation (MSL) 696.7 699.51 698.9 700.64

Table 2-2 summarizes the operating characteristics of each well.

Table 2-2 Raw Water Production Well Operating Characteristics


S1 S2 S3 S4

Static water elevation (MSL) 757.7 733.51 740.9 738.64

Pumping elevation (MSL) 726.7 719.51 730.9 726.64

Drawdown (ft) 31 14 10 12

Flow (GPM) 1953 1750 1750 1764

2.2 Raw Water Piping

The raw water piping system is constructed of cement-lined ductile iron pipe (DIP). The raw water piping

system consists of 405 LF of 12-inch DIP, 1,068 LF of 20-inch DIP, and 1,420 LF of 24-inch DIP.

Table 2-3 summarizes the nominal water velocity (FPS) of each segment of transmission main with

various wells in operation, assuming a production rate of 2,115 GPM for each well.

Table 2-3 Raw Water Main Water Velocity

Production Well in Operation Pipe Diameter

(IN)

Flow

(GPM)

Velocity

(FPS)

PW-1 12 2115 6

PW-2 20 2115 2.1

PW-2 or PW-3 20 2115 2.1

PW-2 and PW-3 20 4230 4.3

PW-4 20 2115 2.1

PW-1 or PW-4 20 2115 2.1



Production Well in Operation Pipe Diameter

(IN)

Flow

(GPM)

Velocity

(FPS)

PW-1 and PW-4 20 4230 4.3

1 well operating 24 2115 1.5

2 wells operating 24 4230 3

3 wells operating 24 6345 4.5

4 wells operating 24 8460 6

The volume of water contained by the existing raw water piping is summarized in Table 2-4

Table 2-4 Raw Water Main Volume

Pipe Diameter

(in)

Area

(SF)

Length

(LF)

Volume

(CF)

Volume

(Gal)

12 0.79 405 318 2,378

20 2.18 1,110 2,420 18,105

24 3.14 1,300 4,082 30,533

TOTAL 6,820 51,016



Figure 2-1 Typical Production Well



Figure 2-2. South Wellfield Plan

PRODUCTION

WELL S1

PRODUCTION

WELL S2

PRODUCTION

WELL S3

PRODUCTION

WELL S4

24” RAW WATER TO SWTP

1300 LF



3 MECHANICAL CLEANING ASSESSMENT

This section summarizes the requirements for conducting mechanical cleaning operations for the raw

water transmission piping.

3.1 Mechanical Cleaning

Mechanical cleaning, also known as pigging, is the practice of using devices known as pigs or scrapers to

remove sediment, scale, or other debris from the inside of piping systems. Pigs are inserted into the pipe

to be cleaned at a pig launching station or other appropriate entry point. Once inserted, the pig is

transported through the pipe using pressurized water as the motive force, which in this case, will be raw

water supplied from the production wells. Ideally, pigs should be propelled through the pipeline at a

nominal velocity of 3 FPS or greater.

Pipeline cleaning using pigs is generally carried out using multiple passes. During the first pass, raw

water is flushed through the pipe to the discharge point to check for flow, headloss, and to allow the

contractor to assess the general operating characteristics of the pipeline. Following the initial flushing, a

pig with a diameter smaller than the pipeline is inserted and propelled through the pipe. As the pig travels

through the pipe, a certain percentage of the carrier water flows around the pig and this is known as

bypass water. The pig along with the bypass water suspends the debris in the water stream which then

carries the debris along the pipe ahead of the pig. The pig is not meant to act as a plow, pushing the

debris ahead of it as this could result in high working pressure and could result in the pig getting stuck.

Depending on the amount of debris removed during this pass, more passes may be required, or it may be

possible to use a pig of a larger diameter on the next pass. Multiple passes are performed using larger

and larger pigs until all of the debris has been satisfactory removed from the piping system.

3.1.1 System Modifications

Permanent modifications to the raw water system are required to accommodate the pigging operations

and to facilitate periodic flushing in the future. The following modifications to the system are required:

1. Adjacent to production well S3, remove the existing 24 x 24 tee and replace with a 24 x 24 cross.

Remove the existing 20-inch butterfly valves (2 valves) and replace with two 20-inch gate valves.

2. Construct 24-inch DIP pipeline to convey pigging water to the existing concentrate lagoon.

Connection to the existing 24-inch transmission main will be made in the asphalt drive near the front

door of the administration building.

These improvements are illustrated by

Figure 3-1.

3.1.2 Pigging Facilities

Entry points must be established for each pipe segment to facilitate the insertion and launching of pigs.

Each of the production wells is equipped with a 12 x 12 wye with a blind flange, located in the check valve

vault adjacent to each well head. The only well where this wye is feasible for pig launching is production



well S1 as the discharge line for this well is 12-inches, as illustrated by Figure 3-2. Each of other wells

(S2, S3, and S4) each discharge through a short reach of 12-inch piping and then into a 20-inch

discharge header, thus requiring a 20-inch pigs. Pigging the discharge header associated with production

well S2 can be accomplished by removing the plug from the existing 20 x 12 tee and installing temporary

piping and a temporary pig launching station as illustrated by Figure 3-3. Pigging of the piping associated

with production well S-3 is not required as this well connects to the production well S2 discharge header.

Pigging the discharge header associated with production well S4 can be accomplished by removing the

plug from the existing 20 x 12 tee and installing temporary piping and a temporary pig launching station

as illustrated by Figure 3-4. Pigging of the 24-inch transmission main from the wellfield to the water plant

can be accomplished by removing the plug from the new 24 x 24 cross adjacent to production well S3,

and installing temporary piping and a pig launching station, as illustrated by Figure 3-5.

3.1.3 Intermediate Pig Launching Facilities

Given the short pigging distances and the relatively low amount of sediment accumulation, intermediate

pig launching facilities are not required for this project.

3.1.4 Solids Capture Facilities

The raw water line conveys raw water from the south wellfield to the water plant where raw water is

directed to the cartridge filters and pressure filters. It is not appropriate to convey cleaning water and

sediment to these treatment processes as the sediment will cause harmful fouling. As a result, this

project requires a facility to intercept and capture the flushing water and sediment. The most feasible

alternative is to utilize the existing concentrate lagoon for this purpose. A new pipeline connecting the

raw water pipeline to the existing lagoon should be constructed to convey the cleaning water and

sediment to the lagoon. Sediment can be collected in the lagoon while clarified water can be decanted

and discharged to the existing stormwater system. Figure 3-1 illustrates a site plan for the installation of a

permanent line connecting the raw water transmission main to the existing concentrate lagoon.

3.1.5 Water Requirements, Sources, and Availability

The largest diameter segment of the raw water transmission piping is 24-inches. In order to maintain a

proper cleansing velocity and properly force the cleaning pigs to scarify and uplift the sediment, a

minimum cleaning velocity of 2.5 to 3.0 FPS will be required during the cleaning operations.

When cleaning pipe segment 1 (refer to Figure 3-6 for pipe segment labelling), the quantity of water produced

by production well S1 will be sufficient to generate the required pig velocity. When cleaning segment 2, raw

water from production wells S1 and S2 will be sufficient to generate the necessary pigging velocity.

Temporary piping can be installed to connect production well S1 to S2 to accomplish this, and is illustrated

by Figure 3-6. Similarly, when cleaning segment 3, raw water from production wells S1 and S4 will be

sufficient to generate the necessary pigging velocity. Temporary piping can be installed to connect

production well S1 to S4 to accomplish this, and is illustrated by Figure 3-6. Finally, when cleaning segment

4, three production wells will need to be switched on to generate the necessary pigging velocity. Any

combination of wells should be sufficient.

Table 3-1 summarizes the water sources, flows, and velocity for each piping segment. Figure 3-6

provides a site plan illustrating temporary piping requirements for pigging segments 2 and 3.



Table 3-1 Raw Water Main Water Velocity

Segment No. Diameter (in) Water Source Flow (GPM) Velocity (FPS)

1 12 S1 2,115 6.0

2 20 S1, S2 4,230 4.3

3 20 S1, S4 4,230 4.3

4 24 Any three of the

four wells 6,360 4.5

3.1.6 Cleaning Operations

It is anticipated that the cleaning of the raw water transmission mains be accomplished through the use of

multiple pigs. A foam pig (or soft swab pig) is typically inserted in the first run. The foam pig is not

expected to dislodge significant amounts of debris, but instead acts as a diagnostic tool. The malleable

and flexible characteristics of the foam pig will reduce the risk of it getting stuck in a pipeline which is not

routinely pigged. The usually low cost of the foam pig can also make it expendable for the contractor.

Observation at the discharge point through the initial run, will allow the contractor to assess the amount

and density of the debris. Once the contractor has had the opportunity to gauge the type of sediment,

density, speed vs rate of flow and work any kinks in the system, a customized pigging plan will be

developed specifically for the system. This pigging plan will propose the diameter and quantity of pigs to

be used to accomplish the main pigging. It should also address flow control and water availability

depending on the number of runs anticipated to accomplish the goals. It may not be necessary to

implement each run individually; the contractor may opt for time releasing multiple pigs within minutes of

each other, in order to reduce the time of the cleaning operations and the amount of water required.

Among the different types of pigs that could likely be suggested for this project are the mandrel cleaning

pig, sealing pig, higher density polyurethane pigs, gel pigs, solid cast pigs or spheres to better negotiate

changes in direction. Of the pigs listed above, polyurethane pigs are the most commonly used in the

municipal industry today.

Water and sediment from each pigging run will be discharged to the existing concentrate lagoon. The

lagoon has a nominal capacity of 880,000 gallons. Given that the approximate volume of the raw water

piping system is approximately 60,000 gallons (including the additional 420 LF of 24-inch DIP connecting

the existing raw water main to the concentrate lagoon), the lagoon has the capacity to hold approximately

14 pigging runs. Pigging water should be periodically drained from the lagoon to ensure continuity of

pigging operations.



3.2 Route and Alignment Planning

The work required to clean the raw water transmission main piping will be executed within the existing

alignments of the existing raw water piping and within property owned by the City of Lancaster. There is

no route or alignment planning necessary for this project.

3.3 Special Crossings

The proposed work does not include or require the construction of any new segments of pipe that will

require a special crossing, e.g. a road crossing, river crossing, or railroad crossing. There is a segment of

piping that was installed by jacking and boring under an existing railroad track, but this segment is the

same pipe material and diameter as the rest of the transmission main. There are no special requirements

for the cleaning of the transmission main underneath the existing railroad track.

3.4 Ice Pigging

Arcadis contacted Suez North America to inquire about the possibility of ice pigging of the raw water

transmission pipework. Suez informed Arcadis that they no long perform ice pigging services in North

America. No other contractors are permitted to perform ice pigging as Suez owns the patent. Therefore,

ice pigging is not an option for this project.



Figure 3-1 Raw Water Piping Modifications

WATER PLANT SITE PLAN

PRODUCTION WELL S3 SITE PLAN

REMOVE EXISTING 24 x 24 TEE AND REPLACE WITH

24 X 24 CROSS. REMOVE 20-INCH BUTTERFLY

VALVES AND REPLACE WITH 20-INCH GATE VALVES

420 LF 24-INCH DIP

2 24-INCH GATE VALVES



Figure 3-2 Production Well S1 Enlarged Site Plan

INSERT PIG USING EXISTING 12 X 12 WYE

IN VALVE VAULT. REFER TO FIGURE 2-1

FOR ADDITIONAL DETAILS




REMOVE PLUG. INSTALL TEMPORARY

PIPING AND PIG LAUNCHING STATION.

REPLACE PLUG WHEN FINISHED




REMOVE PLUG. INSTALL TEMPORARY

PIPING AND PIG LAUNCHING STATION.





REMOVE PLUG FROM NEW 24 X 24 CROSS. INSTALL

TEMPORARY PIPING AND PIG LAUNCHING STATION.


24 X 24 CROSS WITH 24 X 20

REDUCERS ON N & S END

2-20-INCH GATE VALVES



Figure 3-6 Temporary Piping for Pigging Operations

PRODUCTION

WELL S1

PRODUCTION

WELL S2

PRODUCTION

WELL S3

PRODUCTION

WELL S4



4 FLUSHING ASSESSMENT

This section summarizes alternatives for making modifications to existing piping systems to facilitate

cleaning of the raw water transmission main via flushing. Also included are alternatives for making

permanent modifications to facilitate flushing of the concentrate force main.

4.1 Raw Water Transmission Main Flushing

Periodic flushing of the raw water transmission main to remove accumulated Fe and Mn sediment is

recommended as this activity will help prolong the life of the pressure filters, cartridge filters, and RO

system.

There are currently no methods available for flushing the transmission main, therefore construction of

permanent modifications are required. The most feasible alternative is to construct a new pipeline

connecting the existing transmission main to the existing concentrate storage lagoon. The new

connection point would be in the vicinity of the visitor parking lot on the west side of the treatment building

where the transmission main enters the plant. Construction of this pipeline will allow operators to use raw

water to flush sediment from the transmission main and discharge the water and sediment to the existing

concentrate lagoon. Clarified water could then be released from the lagoon to the onsite stormwater

collection system. Figure 4-2 illustrates the concept for the flushing interconnection.

4.2 Concentrate Force Main Flushing Alternatives

A 14-inch diameter, 4.5 mile long force main conveys process residuals (RO concentrate and waste

backwash water from the pressure filters) from the SWTP to the City’s sanitary sewer system. Hydraulic

capacity in this force main has diminished somewhat since its construction and commissioning in 2004 as

a result of scale formation from the RO concentrate and from deposition of iron and manganese sediment

from the pressure filter waste backwash water. The force main requires periodic flushing to maintain

capacity, however, there is not currently a source of flushing water connected to the force main.

Three options are available to connect a flushing water source to the concentrate force main. Two of

these options include interconnections between the concentrate force main to either the raw water main

or to the existing finished water main from inside the west pipe gallery. Another option includes a

connection from the raw water main to the concentrate force main from the plant yard with an additional

connection installed to connect the new raw water line to the existing lagoon. This section provides a

brief description of each of these options.

Flushing of the concentrate header and force main should be conducted after each plan shutdown where

the duration of the shutdown is anticipated to be 8 hours or greater. This helps to displace concentrate

from the force main and reduce the possibility of mineral scale formation. It is also recommended that the

concentrate force main be flushed at least three to four times annually to remove accumulated sediment

from the pressure filter backwash stream. Flushing for sediment removal should be conducted using a

flow rate to generate 6 FPS to suspend settled solids. Table 4-1 summarizes flow rates and water

volume required to conduct flushing operations.

Table 4-1 Concentrate Force Main Flushing Flow and Volume



Parameter Value

Force main material HDPE DR17

ID (inches) 13.392

Area (SF) 0.98

Length (LF) 23,300

Volume (CF) 22,807

Volume (Gallons) 170,598

No. of flushing volumes (N) 3

Total flushing volume (Gallons) 511,794

Flushing velocity (FPS) 6

Flushing flow (GPM) 2636

Flushing duration (minutes) 194

4.2.1 Finished Water Connection Inside West Pipe Gallery

An existing 8-inch finished water main enters the pipe gallery in the vicinity of the existing 24-inch raw

water main (refer to Figure 4-1), and provides a source of backwash water for the pressure filters.

Connecting the finished water pipe to the concentrate header in the pipe gallery requires the following:

Cut new 8 x 8 tee into existing 8-inch main

70 LF 8-inch DIP and fittings

1 8-inch butterfly valve, electrically actuated modulating

1 8-inch pressure reducing valve

1 8-inch RPZ backflow preventer

The finished water contains a free chlorine residual (1 – 2 mg/L) and the RO concentrate contains high

concentrations of dissolved Fe and Mn. The chlorine from the finished water will oxidize the dissolved Fe

and Mn in the concentrate, converting it into particulate form, which can form additional sediment in the

force main. For this reason, it is not recommended that finished water be used for flushing of the

concentrate force main.

4.2.2 Raw Water Connection Inside West Pipe Gallery

The existing 24-inch raw water main enters the pipe gallery at the southwest end of the pipe gallery (refer

to Figure 4-1). The raw water main splits, with one leg providing raw water to the pressure filters, and the

other leg providing raw water to the cartridge filters and the RO system. The leg feeding the cartridge

filters terminates at a 24-inch blind flange in the vicinity of the RO concentrate header (refer to Figure

4-1). Connecting the raw water main to the concentrate header in the pipe gallery requires the following:

Removal of the 24-inch blind flange from the raw water header;

Removal of the 12-inch blind flange from the concentrate header;



24 x 12 reducer;

30 LF 12-inch DIP and fittings;

1 12-inch butterfly valve, electrically actuated, modulating;

1 12-inch pressure reducing valve;

1 12-inch check valve.

The concentrate piping within the pipe gallery and between the pipe gallery and concentrate lagoon was

not designed to accommodate high flow rates and velocities that would be expected during flushing

operations. Therefore it is not recommended that this alternative be implemented.

4.2.3 Raw Water Connection From Yard

A new pipeline connecting the raw water pipeline to the concentrate force main from the plant yard with

an additional connection to connect the new raw water line to the existing lagoon would require the

following:


1 24-inch gate valve;

2 16-inch gate valves;

1 12-inch check valve;


1 12-inch gate valve;

1 Precast concrete valve vault

Connecting the raw water main to the concentrate force main from the plant yard with an additional

connection to connect the new raw water line to the lagoon is preferred alternative and is illustrated by

Figure 4-2. This will allow for periodic flushing of both the concentrate force main and the raw water

transmission main. The required flushing flow can be achieved by using any two of the existing raw water

production wells. As stated earlier, flushing should be completed when a plant shutdown is anticipated to

last for more than 8 hours and should be completed on a periodic basis to flush any accumulated

sediment.



Figure 4-1 Flushing Connections for Concentrate Force Main Inside West Pipe Gallery

24

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MATCHLINE THIS SHEET

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8-I

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H F

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INDICATES FINISHED WATER FLUSHING CONNECTION

INDICATES RAW WATER FLUSHING CONNECTION



Figure 4-2 Flushing Connections for Concentrate Force Main Outside in Yard

INDICATES EXISTING 24” RAW WATER LINE

INDICATES EXISTING COCENTRATE FORCE MAIN

INDICATES PROPOSED 16” FLUSHING LINE

INDICATES PROPOSED 12” FLUSHING LINE

INDICATES PROPOSED 24-INCH GATE VALVE


INDICATES PROPOSED 16-INCH CHECK VALVE


INDICATES PROPOSED VALVE VAULT

SW-X INDICATES SHEET NO. FROM CONSTRUCTION

DRAWING SET

16-INCH FLUSHING LINE

12-INCH FLUSHING LINE

CONNECTION TO

CONCENTRATE



5 REGULATORY AND PERMIT REQUIREMENTS

Although an Ohio Environmental Protection Agency (OEPA) permit is not necessary for pigging activities

and line maintenance, construction of permanent modifications and/or operational protocol changes at

SWTP will need to be coordinated with the OEPA. A permit-to-install (PTI) from OEPA’s Division of

Drinking and Groundwaters will be required.

The new proposed improvements are located within the City’s property limits. Contractors will not be

required to obtain special permits for working on City property.



6 PROJECT SCHEDULE

The preliminary project schedule is summarized in Table 6-1. The schedule assumes that design of the

facilities required to accommodate the pigging operations will need to be completed as the first step. This

includes the modifications to the 24-inch raw water transmission main to construct new connections to the

existing concentrate lagoon and concentrate force main. Following design, the City will solicit bids from

contractors to construct the necessary facilities. It is assumed that one general contract will be let for

construction of the required facilities and contracts for this work can be combined with the cleaning of the

concentrate force main.

Table 6-1 Preliminary Project Schedule

Project Milestone Days Cumulative Days

Engineering Procurement 90 90

Design Engineering 90 180

Permitting (concurrent with design and bidding) 60 180

Bidding and Contract Award 75 255

Construction 180 335

Pigging Operations (concurrent with construction) 10 335

Removal of Temporary Facilities and Restoration 10 335



7 ECONOMIC EVALUATION OF ALTERNATIVES

This section presents an opinion of probable project cost (OPPC) of the mechanical cleaning alternatives

for the SWTP. The project cost estimates are based on the conceptual layouts and design criteria

presented and are to be considered planning level only. The costs are not to be considered final project

costs which can only be developed as a result of detailed design.

7.1 Class of Estimate

The OPPC estimate is considered a Class 4 according to the cost estimate classification system. Table

7-1 provides a summary of the estimate classes.

Table 7-1 Estimate Classification Matrix

Estimate

Class

Level of

Project

Definition

End Usage Methodology Expected Accuracy

Range

Typical

Contingency

5 <= 5%

Preliminary project

screening

estimate, capital

budget planning,

alternative

evaluation,

strategic analysis

Capacity factored,

parametric models,

judgement, analogy,

historical project

comparison

Low: -20% to - 50%

High +30% to +100% 15 – 40%

4 5 – 20%

Preliminary project

estimate, reality

check estimate,

alternative

evaluation,

feasibility study

Equipment factored

parametric models,

historical relationship

factors, broad unit cost

data

Low: -15 to -30%

High: +30% to

+100%

10 – 25%

3 20 – 60%

Project funding

estimate, fair price

check

Semi detailed unit

costs with assembly

level line items by

trade, historical

relationship factors

Low: -10% to -15%

High: +10% to +30% 5 – 15%

2 60 – 99%

Project funding

estimate, control

estimate, bid

estimate

Detailed estimating

data by trade, with

detailed takeoff

quantities

Low: -5% to -15%

High: +5% to +20% 5 – 15%

1 90 – 100% Firm bid estimate

Detailed estimating

data by trade with

detailed firm takeoff

quantities

Low: -3% to -10%

High: +3% to +15% 3– 10%



7.1.1 Class 5 Cost Estimate

Class 5 estimates are generally prepared based on very limited information, and subsequently have wide

accuracy ranges. Typically, engineering is from 2% to 10% complete. They are often prepared for

strategic planning purposes, market studies, assessment of viability, project location studies, and long-

range capital planning. Virtually all Class 5 estimates use stochastic estimating methods such as cost

curves, capacity factors, and other parametric techniques. Expected accuracy ranges are from –20% to –

50% on the low side and +30% to 100% on the high side, depending on technological complexity of the

project, appropriate reference information, and the inclusion of an appropriate contingency determination.

Ranges could exceed those shown in unusual circumstances. As little as 1 hr. or less to perhaps more

than 200 hours may be spent preparing the estimate based on the project and estimating methodology.


Class 4 estimates are generally prepared based on limited information and subsequently have fairly wide

accuracy ranges. Typically, engineering is 10% to 40% complete. They are typically used for project

screening, determination of feasibility, concept evaluation, and preliminary budget approval. Virtually all

Class 4 estimates use stochastic estimating methods such as cost curves, capacity factors, and other

parametric and modelling techniques. Expected accuracy ranges are from –15% to –30% on the low side

and +20% to 50% on the high side, depending on the technological complexity of the project, appropriate

reference information, and the inclusion of an appropriate contingency determination. Ranges could

exceed those shown in unusual circumstances. As little as 20 hours or less to perhaps more than 300

hours may be spend preparing the estimate depending on the project and estimating methodology.


Class 3 estimates are generally prepared to form the basis for budget authorization, appropriation, and/or

funding. Typically, engineering is from 10% to 40% complete, and would comprise a minimum of process

flow diagrams, utility flow diagrams, preliminary piping and instrumentation diagrams, plot plan,

developed layout drawings, and essentially complete engineered process and utility equipment lists.

They are typically prepared to support full project funding requests and become the first of the project

phase "control estimates" against which all actual costs and resources will be monitored for variation to

budget. Most Class 3 estimates involve more deterministic estimating methods than stochastic methods.

Typical accuracy ranges for Class 3 estimates are from +/- 10% to 30% (sometimes higher), depending

on the technological complexity of the project, appropriate reference information, and the inclusion of an

appropriate contingency determination. As little as 300 hrs. or less to perhaps more than 2,000 hours may

be spent preparing the estimate based on the project and estimating methodology.


Class 2 estimates are generally prepared to form a detailed control baseline against which all project

work is monitored in terms of cost and progress control. For contractors, this class of estimate is often

used as the “bid” estimate to establish contract value. Typically, engineering is from 30% to 70%

complete, and would comprise at a minimum of the following: process flow diagrams, utility flow diagrams,

preliminary piping and instrumentation diagrams, heat and material balances, final plot plan, final layout



drawings, complete engineered process and utility equipment lists, single line diagrams for electrical,

electrical equipment, and motor schedules, vendor quotations, detailed project execution plans,

resourcing and work force plans, etc. Class 2 estimates always involve a high degree of deterministic

estimating methods often involving thousands of unit cost line items. Typical accuracy ranges for Class 2

estimates are –5% to –15% on the low side, and +5 to +20% on the high side, depending on the

technological complexity of the project. As little as 300 hrs. or less to perhaps more than 3,000 hours may

be spent preparing the estimate based on the project and estimating methodology. Bid estimates typically

require more effort than estimates used for funding or control purposes.


Class 1 estimates are generally prepared for discrete parts or sections of the total project rather than

generating this level of detail for the entire project. These estimates may be prepared for to determine a

fair price or bid check to evaluate claims and disputes. Typically, engineering is 50% to 100% complete

and would comprise of virtually all engineering and design documentation for the project and complete

execution and commissioning plans. Expected accuracy ranges are –3% to –10% on the low side to +3%

to + 15% on the high side depending on the technological complexity of the project, appropriate reference

information and appropriate contingency determination. As little as 600 hours to more than 6,000 hours

may be spent preparing the estimate based on the project and estimating methodology. Bid estimates

typically require more effort than estimates used for funding or control purposes.

7.2 Opinion of Probable Project Costs

A preliminary opinion of probable project cost (OPPC) has been prepared for the construction of

permanent improvements required to facilitate mechanical cleaning, conducting the initial mechanical

cleaning, and periodic flushing of the raw water transmission piping.

7.2.1 Mechanical Cleaning

It is estimated that construction of permanent facilities within the wellfield and at the water treatment plant

site to accommodate mechanical cleaning amounts to approximately $479,500 which includes a 25%

contingency at this preliminary level. This OPPC contains a fee of approximately $50,000 for the actual

pigging services and $2,000 for the disposal of solids.

Table 7-2 provides an OPPC for the improvements to the raw water transmission main and pigging

operations.



Table 7-2 OPPC Raw Water Transmission Main Improvements and Mechanical Cleaning

7.2.2 Flushing Connection in Plant Yard

It is estimated that construction of connecting the raw water main to the existing concentrate force main

from the plant yard with an additional connection to connect the new raw water line to the lagoon to

accommodate periodic flushing of the concentrate force main using raw water amounts to approximately

$306,300 which includes a 25% contingency at this preliminary level.

Table 7-3 provides an OPPC for the flushing connection for the concentrate force main outside in the

yard.



Table 7-3 OPPC Flushing Interconnection for Concentrate Force Main Outside in Yard

1 Seeding and mulching 280 SY 5.00$ 1,400.00$

2 Curb and gutter removed 24 LF 8.00$ 192.00$

3 Full depth pavement removal and replacement 35 SY 225.00$ 7,875.00$

4 Asphalt concrete surface course, type 1 6 CY 400.00$ 2,400.00$

5 Curb and gutter 24 LF 400.00$ 9,600.00$

6 24-inch solid sleeve 1 Ea 5,000.00$ 5,000.00$

7 24 x 16 tee 1 Ea 5,000.00$ 5,000.00$

8 12 x 12 tee 1 Ea 3,500.00$ 3,500.00$

9 12-inch solid sleeve 1 Ea 3,500.00$ 3,500.00$

10 12-inch DIP waterline 50 LF 175.00$ 8,750.00$

11 16-inch DIP waterline 420 LF 200.00$ 84,000.00$

12 12-inch gate valve 1 Ea 6,500.00$ 6,500.00$

13 16-inch gate valve 2 Ea 8,500.00$ 17,000.00$

14 12-inch check valve 1 Ea 6,500.00$ 6,500.00$

15 Precast concrete valve vault 1 LS 20,000.00$ 20,000.00$

Subtotal 181,217.00$

181,217.00$

Mobilization / General Conditions 3% 5,440.00$

Contractor Overhead 7% 12,690.00$

Contractor Profit 7% 12,690.00$

Contractor Insurance / Bonds 2% 3,630.00$

Engineering Design 15% 27,190.00$

Construction Administration and Inspection 10% 18,130.00$

Construction Contingency 25% 45,310.00$

Subtotal 125,080.00$

TOTAL PROJECT COST

Low Range (AACE Class 4) -30% 268,800$

Middle Range 306,300$

High Range (AACE Class 4) 50% 459,450$

Construction

Total Construction Cost

Administrative Services

306,300$

ITEM DESCRIPTION QUAN. Unit UNIT PRICE SUBTOTAL



8 CONCLUSION

At the May 13, 2020 Progress Meeting, it was agreed that the City will not be making modifications to the

raw water transmission main at this time to facilitate pigging operations at this time. Connecting the raw

water main to the concentrate lagoon from the plant yard with an additional connection to connect the

new raw water line to the existing concentrate force main was selected as the preferred alternative and is

used as the basis of design for this report.

Arcadis U.S., Inc.

100 E Campus View Boulevard

Suite 230

Columbus, Ohio 43235-1447

Tel 614 985 9100

Fax 614 985 9170

www.arcadis.com

SOUTH WATER PLANT RAW WATER TRANSMISSION MAIN

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