F Scenarios supporting documentation€¦ · Draft, February 2020 ... 18 side (inlet pressure) makes sure that a certain pressure on the outlet side (outlet pressure) is not 19 exceeded,

Draft, February 2020

Conceptual Drinking Water Supply Plan Minnesota Pollution Control Agency • Department of Natural Resources F-1

F Scenarios supporting documentation

1

This appendix provides supplemental information to Chapter 7 and Appendix E of the Conceptual 2

Drinking Water Supply Plan (Conceptual Plan) as follows: 3

• Glossary (Section F.1) 4

• Unit cost estimations (Section F.2) 5

• Small community water system analysis (Section F.3) 6

• Treatment technology comparison (Section F.4). 7

F.1 Glossary 8

This section provides a glossary of key terms used in the Conceptual Plan and appendices. 9

Alignment – Location of water lines relative to other infrastructure, typically roadways. 10

Booster pump station – A pump station located within the water supply system designed to boost the 11

pressure of water within a long pipeline. 12

Distribution line – A smaller diameter line typically between 6 and 16 inches that supplies water to 13

consumers. 14

Distribution system – The portion of a water supply network that conveys potable water from 15

transmission lines to water consumers and provides for residential, commercial, industrial and fire-16

fighting water demand requirements. A distribution system can contain distribution lines, booster pump 17

stations, pressure reducing valves, storage facilities such as water storage tanks or towers. 18

Drinking water distribution modeling – A mathematical model of a fluid flow system such as a water 19

system, a sewer system, or a storm system, constructed using modeling software used to analyze 20

systems hydraulic behavior. 21

High service pump – Pumps located at the water treatment facility that deliver large volumes of treated, 22

potable water to the water supply system. 23

Horizontal directional drilling – A minimal impact trenchless method of installing underground utilities 24

such as pipe, conduit, or cables in a relatively shallow arc or radius along a prescribed underground path 25

using a surface-launched drilling rig. 26

Jack and bore – A method of horizontal boring construction for installing casing or steel pipes under 27

roads or railways. Construction crews drill a hole underground horizontally between two points (the 28

sending and receiving pits) without disturbing the surface in between. This is accomplished by using an 29

auger boring machine that inserts a casing pipe as it moves through the earth while at the same time 30

removing the soil from within the casing pipe. 31

Municipal water system – Refers to an existing municipality’s drinking or potable water treatment and 32

distribution system. 33

Non-community public water supply wells – Wells that provide water to the public in places other than 34

their homes – where people work, gather and play (i.e., schools, offices, factories, child care, or parks) 35

and are part of a non-community public water system (see definition below). 36



Non-community public water system – A drinking water system that supplies water from private water 1

supply well(s) on a year-round basis to: 2

• A residential development with 6 or more private residences (e.g., apartment buildings, private 3 subdivisions, condominiums, townhouse complexes, mobile home parks), or 4

• A mobile home park or campground with 6 or more sites with water service hookup. 5

Non-municipal wells – Wells considered under this conceptual drinking water supply plan that exclude 6

municipal wells and include domestic, irrigation, commercial, and non-community public water supply 7

wells. 8

Operation and Maintenance - All work activities necessary to operate and maintain all water treatment 9

and supply facilities from the source of water through the distribution systems. It includes the labor, 10

equipment replacement and maintenance, chemicals (chlorine gas or sodium hypochlorite), PFAS 11

treatment media for either granular activated carbon or ion exchange removal and replacement, 12

electrical power for motors, heating, water quality testing, or other activities necessary to keep a water 13

system operational. 14

Pressure reducing stations – Locations within the water supply system where a pressure reducing valve 15

has been installed. 16

Pressure reducing valves – A valve fitted in a pipe system, which in spite of varying pressures on the inlet 17

side (inlet pressure) makes sure that a certain pressure on the outlet side (outlet pressure) is not 18

exceeded, thus protecting the components and equipment on the outlet side. 19

Regional water supply system – A water system that supplies potable water to more than one 20

community or water system. 21

Water storage tank – A water storage facility consisting of a cylindrical tank that has a base elevation at 22

the existing ground surface. Also, commonly referred to as a water tower. 23

Water storage tower – An elevated water storage facility (also referred to as a water tower) that 24

supports a water storage tank with a base elevation above the existing ground surface to provide 25

sufficient pressure to the water distribution system for the distribution of potable water, and to provide 26

emergency storage for fire protection. 27

Transmission line – A large diameter pipeline designed to convey large volumes of water at higher 28

pressures from a source (typically a water treatment facility) to a distribution systems for use. Water 29

transmission lines are typically larger in diameter (greater than 16 inches) and consumers are not 30

typically placed on transmission lines due to the high velocities and pressures. 31

Water supply system – A system for the treatment, transmission, storage, and distribution of water from 32

source to consumers, for example, homes, commercial establishments, industry, irrigation facilities and 33

public agencies for water. 34

F.2 Unit cost estimation 35

F.2.1 Introduction 36

This section summarizes the assumptions used to determine the unit costs related to several different 37

construction projects throughout Washington County. Costs were developed for: 38

• Installing water mains (Section F.2.2) 39



• Constructing water storage tanks or towers (Section F.2.3) 1

• Constructing booster pump stations (Section F.2.4) 2

• Constructing buildings used for booster pump stations, well pump houses, and water treatment 3

plants (Section F.2.5) 4

• Drilling new municipal and private wells (Section F.2.6) 5

• Land acquisition (Section F.2.7). 6

This information assisted in determining the total estimated costs associated with conceptual projects 7

included in this Conceptual Plan. 8

F.2.2 Water mains 9

An analysis was performed to estimate the approximate unit costs of installing water mains in 10

Washington County. The estimated costs relate to construction projects within rural and urban 11

communities. The analysis considered the approximate costs for varying percentages of the pipe that 12

would be aligned under the roadway for both urban and rural areas. Using the costs for street 13

reconstruction, material costs, labor, and permitting, the total cost per linear foot was estimated. By 14

knowing the approximate distance that a water main project would span, the total project costs can be 15

estimated using the costs per linear foot. 16

The cost estimates for pavement removal/replacement, trench excavation/backfill, pipe, and installation 17

costs were found using bid tabulations from cities within Washington County along with the Washington 18

County Municipal Water Coalition Supply Feasibility Assessment (SEH 2016). The assumptions used 19

during the analysis are outlined below. 20

Assumptions 21

• The sum of the total cost for street reconstruction was applied for 100% in roadway (or 100% 22 under the roadway pavement) and assumed two lanes of roadway were removed and replaced. 23 Half of the total costs for street reconstruction were applied for 50% in roadway and assumed 24 one lane of roadway is removed and replaced. None of the costs for street reconstruction were 25 applied for 0% in roadway and no lanes were assumed to be removed or replaced. 26

• Some of the pipe would not be installed under the roadway as defined by 100%, 50%, or 0% in 27 roadway (or under the roadway pavement). 28

• The curb, gutter, and sidewalks would be removed and replaced for water mains in urban areas. 29 Curb, gutter, and sidewalks were not included for water mains installed in rural areas. 30

• The pipe would be buried 8 feet deep. 31

• Excavation protection was only considered for water main installation in urban communities. 32

• Fire hydrants were assumed to be included every 300 feet. 33

• For pipes with diameters ranging from 4” - 8”, valves were assumed to be installed every 400 34 feet and fittings were assumed to be installed every 200 feet. 35

• For 12” diameter pipe, valves were assumed to be installed every 600 feet and fittings were 36 assumed to be installed every 200 feet. 37

• For pipes with diameters ranging from 16” - 24”, valves were assumed to be installed every 800 38 feet and fittings were assumed to be installed every 200 feet. 39

• For pipes with diameters ranging from 20” - 42”, the costs for valves and fittings were included 40 in the unit costs per linear foot of pipe. 41



• Stormwater protection and utility conflicts were taken into consideration as part of the street 1 reconstruction estimates. 2

• Engineering permits, Right-of-Way Permits, and construction inspections were included as a 3 percentage of the total costs. 4

The remaining costs were converted using the sum within the project total from varying bid tabulations 5

to estimate the cost per linear foot of each contributing item. The costs were organized by the diameter 6

of the pipe, the percentage in roadway, and the type of community where the project would take place. 7

Pricing found in years prior to 2019 were moved forward to 2019 pricing using the Construction Cost 8

Index from the Engineering News Record. 9

Table F.1 outlines the individual costs that were included in the total unit price per linear foot for water 10

main installations. Table F.2 summarizes the total costs per linear foot for water main installations of 11

varying pipe sizes. 12

Table F.1. Individual costs included in water main installations. 13

Urban Rural

• Roadway and driveway removal/replacement

• Curb, gutter, and sidewalk removal/replacement

• Removal/replacement of median

• Trench excavation and backfill

• Excavation protection

• Ductile iron piping, fittings, and valves

• Existing sewer, water, and utility pipe removal/replacement

• Pipe insulation and bedding

• Other trenching costs

• Costs of construction including mobilization, overhead, profit, and general conditions

• Labor

• Engineering Permits & City Inspections

• Roadway and driveway removal/replacement

• Trench excavation and backfill

• Ductile iron pipping, fittings, and valves

• Pipe insulation and bedding

• Other trenching Costs

• Costs of construction including mobilization, overhead, profit, and general conditions

• Labor

• Engineering Permits & City Inspections

14 Table F.2. Unit cost summary for water main installation. 15

Pipe diameter (in) Percent in roadway Urban costs per foot Rural costs per foot

2 0% $176 $97

2 50% $369 $140

2 100% $562 $183

4 0% $206 $127

4 50% $399 $170

4 100% $592 $213

6 0% $215 $135

6 50% $408 $178

6 100% $601 $221

8 0% $223 $142

8 50% $416 $185

8 100% $609 $228

12 0% $238 $155

12 50% $431 $198



Pipe diameter (in) Percent in roadway Urban costs per foot Rural costs per foot

12 100% $624 $241

16 0% $258 $174

16 50% $451 $217

16 100% $644 $260

18 0% $274 $189

18 50% $467 $232

18 100% $660 $275

20 0% $368 $283

20 50% $561 $326

20 100% $754 $369

24 0% $409 $321

24 50% $602 $364

24 100% $795 $407

30 0% $472 $382

30 50% $665 $425

30 100% $858 $468

36 0% $558 $467

36 50% $751 $509

36 100% $944 $552

42 0% $612 $518

42 50% $805 $561

42 100% $998 $604

48 0% $678 $581

48 50% $871 $624

48 100% $1,064 $667

54 0% $744 $645

54 50% $937 $688

54 100% $1,130 $731

60 0% $806 $706

60 50% $999 $748

60 100% $1,192 $791

F.2.3 Storage tank or towers 1

An analysis was performed to estimate the total costs required to construct a storage tank or tower in 2

dollars per gallon. This allows for the cost to build a storage tank in Washington County to be estimated 3

based on the gallons of water the tank or tower would hold. The unit costs related to sitework and 4

storage tank construction were estimated using a bid tabulation from Woodbury and Lake Elmo. Pricing 5

found in years prior to 2019 were moved forward to 2019 pricing using the Construction Cost Index from 6

ENR. The assumptions used during this analysis are outlined below. 7

Assumptions 8

• The storage tank could be constructed as a steel fluted column water tower or a steel pedestal 9 spheroid water tower. 10



• The estimated cost for the storage tank does not include the costs for all required tank 1 equipment. 2

• Yard piping was assumed to be 200 linear feet of 24” ductile iron water main. 3

• Tank maintenance was assumed to be 1.5% of tank capital cost. 4

• Site operating costs included $2,000 for heating and $2,000 for general site maintenance. 5 Operator costs were assumed to be $50 per hour for four hours per week. 6

• Internal and external tank coatings were assumed to be removed and recoated every 20 years. 7

The total cost for a storage tank varied between $1.85 and $2.00 cost per gallon based on the site. By 8

multiplying $1.85 or $2.00 to the storage capacity provides the tank installation cost. Then, this value 9

can be added to the estimated sitework cost of $300,154 to obtain an estimated total project cost. Table 10

F.3 provides example unit cost estimates for a storage tank (using $1.85 cost per gallon). 11

Table F.3. Unit cost summary for storage tank construction. 12

Cost per gallon Gallons Cost of

storage tank Sitework Total capital cost Annual O&M

costs

$1.85 50,000 $92,509 $300,154 $392,662 $17,190

$1.85 100,000 $185,017 $300,154 $485,171 $19,980

$1.85 500,000 $925,085 $300,154 $1,225,239 $42,301

$1.85 1,000,000 $1,850,170 $300,154 $2,150,324 $70,203

F.2.4 Booster pump stations 13

An analysis was performed to determine the approximate unit cost of constructing a booster pump 14

station. This was conducted to allow for the costs associated with constructing a booster pump station 15

in Washington County to be calculated based on the gallon per minute firm pumping capacity or flow 16

rate of the booster pump station. 17

The unit costs used in this analysis came from a bid tabulation in Lake Elmo. Many assumptions follow 18

those outlined in the Washington County Municipal Water Coalition Supply Feasibility Assessment (SEH, 19

2016) and from the 2019 RSMeans Data Book. All pricing from years prior to 2019 were moved forward 20

to 2019 pricing using the Construction Cost Index from ENR. The 6/10th rule was used to scale 21

construction costs. The assumptions used during the analysis are listed below. 22

Assumptions 23

• Assumed 4 hours per week operation, with an hourly cost estimate of $50 per hour. 24

• Pumping energy costs were assumed to be 74% of pump efficiency, using a -hr cost of $0.072. 25

• Assumed equipment maintenance to be 3% of pump capital cost. 26

• Additional annual maintenance costs included $2,000 for heating the building and $2,000 for 27 miscellaneous building costs. 28

From the analysis, the unit cost to build a complete booster pump station was estimated to be $800 for 29

every gallon per minute. This cost includes all related sitework and assumes two pumps were used in 30

the station. By multiplying $800 to the number of gallons per minute sent to the booster pump station 31

the total cost for equipment and construction can be estimated. The horsepower of each pump relates 32

to the pumping energy costs and contributes to the estimated annual operation and maintenance 33

(O&M) costs. Table F.4 provides example unit cost estimates for a booster pump station. This pricing 34

includes the cost to construct a building and all required sitework. 35



Table F.4. Unit cost summary for booster pump station construction. 1

Gallons per minute Horsepower Annual operating

cost Capital

cost

Cost per gallons per

minute

1,200 150 $82,300 $1,045,400 $800

F.2.5 Buildings 2

The contractor’s schedule of values from St. Paul Park’s granular activated carbon (GAC) water 3

treatment plant were used to determine the cost to construct buildings used for booster pump stations, 4

well pump houses, and water treatment plants. The cost for the buildings can be estimated by the 5

building size in square feet and includes all necessary site work. It was estimated to cost $560 per square 6

foot to construct a building. Table F.5 provides examples of varying costs based on the size of the 7

building. 8

Table F.5. Unit cost summary for building construction. 9

Building dimensions Building cost per square foot Capital cost of building

45’ x 20’ $560 $500,221

30’ x 15’ $560 $250,110

10’ x 10’ $560 $55,580

F.2.6 Municipal and Non-Municipal wells 10

An analysis was performed to determine the cost in gallons per minute to drill a new municipal well in 11

Washington County. Pricing used for this analysis came from the Washington County Municipal Water 12

Coalition Supply Feasibility Assessment (SEH, 2016) and a bid tabulation from the City of Hastings, 13

Minnesota. Using this information, the cost to drill a new municipal well capable of suppling 800-1,200 14

gallons per minute was estimated to be $2,178,000. Installation costs for wells outside of this range 15

were scaled using the 6/10th rule. Additionally, the approximate cost to drill a new non-municipal well 16

was determined using a bid tabulation from West Lakeland. 17

The results for the cost to drill a new municipal well and a new non-municipal well are shown in 18

Table F.6. The pricing includes the cost to construct a new well house and sitework. The ENR 19

Construction Cost Index was used to move all pricing from years prior to 2019 forward to 2019 pricing. 20

Table F.6. Unit cost summary for drilling new municipal and non-municipal wells. 21

Well description Gallonds per minute Capital cost

Municipal well 800-1,200 $2,178,000

Private well 3 $70,400

F.2.7 Land acquisitions 22

In order to estimate the current cost of land in Washington County, the costs of two lots per community 23

were analyzed. Based on the price per acre of each lot throughout Washington County, an estimated 24

cost of $3 per square foot was derived. The resources used include Realtor.com, Zillow, and the Metro 25

East Commercial Real Estate Services. The results from the analysis are shown in Table F.7. 26

Table F.7. Unit cost summary for land acquisition. Sorted by cost per square foot, going from lowest to 27 highest cost. 28

Acres Community Cost per square foot

5.5 Denmark $0.93

4.2 Cottage Grove $1.64



Acres Community Cost per square foot

3.4 St. Paul Park $1.82

3.0 Grey Cloud Island $2.04

5.1 Afton $2.12

1.3 Newport $2.18

2.6 West Lakeland $3.24

2.5 Oakdale $4.11

1.8 Lake Elmo $4.36

1.2 Maplewood $4.38

1.5 Lakeland/Lakeland Shores/Lake St. Croix Beach $4.41

1.4 Woodbury $6.03

F.3 Small community water system analysis 1


This section summarizes the theoretical exercise performed to examine the validity of small community 3

water systems for the rural communities in the East Metropolitan Area affected by the PFAS 4

groundwater contamination. The selected areas were analyzed to determine if drilling and treating a 5

well to service 8 or 20 homes would create a more cost-effective solution over treating each non-6

municipal well individually with a GAC point of entry treatment (POET) system. The analysis included 7

neighborhoods in Afton, West Lakeland, and Grey Cloud Island. 8

The results from this analysis demonstrate how the distance between homes and the costs associated 9

with drilling a larger well, installing pipe, and providing treatment contribute to the number of homes 10

which can be grouped together. The 1974 Safe Drinking Water Act states that when at least 15 service 11

connections or 25 people are served for at least 60 days a year by a single source, the water system is 12

considered a public water system. Redundancy requirements for public water systems do not come into 13

effect when considering a water system for 24 people or 8 homes at 3 people per household. When 14

analyzing 20 homes per well, redundancy is required consisting of two wells, a certified water operator, 15

a backup generator, and additional water quality testing. These additional costs required for a water 16

system which can service 20 homes are reflected below. A system for 8 homes with approximately 3 17

people per home is the maximum number of homes which can be grouped together and serviced by one 18

well. 19

The challenges considered during this analysis included identifying homes close enough to form an area 20

to be serviced, measuring the average distances between homes with ArcGIS Earth, and determining if 21

the cost of creating a small community water system would reduce the overall costs related to treating 22

the groundwater in the area. 23

F.3.2 Cost development and well counts 24

Costs were developed by utilizing unit costs from recent bid tabulations in the project area, obtaining 25

installation quotes from private well drillers in the project area, obtaining vendor quotes for equipment, 26

and utilizing the Minnesota Pollution Control Agency’s (MPCA) experience and current contracted rates 27

for installing POET systems on private wells. POET system costs used for individual homes/wells were 28

$2,500 for capital costs and $1,000 for annual O&M costs. 29



Well data were taken from initial well counts provided by the MPCA and the Minnesota Department of 1

Health (MDH) in 2019. These well counts do not match the final private well counts used in Appendix E 2

of the Conceptual Plan, but illustrate the conclusions of this analysis with the same efficacy. 3

The total 20 years costs for the small community water systems were calculated by the sum of the initial 4

costs for drilling and equipping a well 200-400 feet deep, installing 2”- 4” polyvinyl chloride (PVC) pipe, 5

and installing a treatment system with the sum of the anticipated O&M costs over the span of 20 years 6

with a 3% discount rate related to the net present value. ArcGIS Earth was used to identify the number 7

of homes in each community close enough to be considered for a small community water system. For 8

this analysis, clusters of 8 and 20 homes were considered. The major cost factors were the costs for 9

installing piping and drilling a new well. When more homes were connected to a small community water 10

system the costs for these options decreased. 11

Costs that are presented in this analysis are only associated with the capital and operation and 12

maintenance costs associated with POET systems and small community water systems. Legal expenses 13

and administrative costs of setting up and running a small community water system are not accounted 14

for in these cost estimates. Similarly, the legal, administrative, on-going well monitoring, and other 15

indirect or overhead costs associated with managing the POETs and carbon change-outs is also not 16

accounted for in the cost estimates. 17

18

F.3.3 Afton 19

For Afton, two analyses were performed to determine if a small community water system of 8 or 20 20

homes would create cost savings over treating non-municipal wells with POET systems. 21

The cost estimates for these analyses included the costs associated with installing 2” PVC piping to bring 22

water from a new higher capacity well to 8 or 10 surrounding homes, as well as the total 20-year O&M 23

costs. The total 20-year O&M costs assume that PVC piping would last 50 years, and a recapitalization 24

cost was estimated along with piping maintenance costs. The PVC piping service life estimate was 25

determined from the ASTM Annual Book of Standards, Volume 8.04 Plastic Pipe and Building Products, 26

American Society for Testing and Materials and Plastics Pipe Institute. The cost assumes the well pump 27

and pressure tank would need to be replaced once every 10 years. The GAC treatment system for the 28

wells was assumed to need maintenance and filter change-outs once a year. The total 20-year costs for 29

introducing small community water systems was determined by summing the initial costs for purchasing 30

and installing 2” PVC pipe, costs for drilling and equipping a large well, and each treatment system along 31

with approximating any maintenance costs the equipment may need over the course of 20 years. 32

Figure F.1 shows an example of connecting 8 homes in Afton to a small community water system. The 33

example grouping of homes shown is located off 2nd and 3rd street West of Neal Avenue. In Afton, there 34

are many pockets of homes capable of creating a small community water system. When looking at the 35

initial and 20-year costs associated with treating individual wells with POET systems versus treating 36

communities of 8 homes per well, the results shown in Table F.8 reveal no cost saving benefits. 20-year 37

costs triple from Alternative 1 to Alternative 6 as the number of small community water systems 38

increase and the number of POETs decrease. For example, Alternative 2 represents 10 small community 39

water systems of 8 homes each and 1,025 homes with POET systems. This would be 80 POET systems 40

replaced by a small community water system. The initial and 20-year pricing includes the cost for 41

treating a community well in addition to the costs for treating all remaining homes with POET systems. 42



The results shown in Table F.8 assume 8 homes can be served with approximately 3,500 feet of 2” PVC 1

pipe. The average distance of 350 feet between 8 homes was calculated using ArcGIS Earth. 2

Figure F.1. Example of four 8 home groupings in Afton. 3

4

Table F.8. Cost analysis for grouping 8 homes in Afton. 5

Alternative

Groups of 8 home small

community water

systems

Individual homes with private wells

and POETs Initial cost (capital)

Annual operating cost

20 year cost (capital +

O&M)

20 year cost (capital + O&M)

net present value with 3% discount rate

1 0 1,105 $2,762,500 $1,105,000 $28,619,500 $25,746,500

2 10 1,025 $6,324,500 $1,133,000 $32,633,500 $29,657,500

3 35 825 $15,229,500 $1,203,000 $42,668,500 $39,435,000

4 65 585 $25,915,500 $1,287,000 $54,710,500 $51,168,000

5 95 345 $36,601,500 $1,371,000 $66,752,500 $62,901,000

6 135 25 $50,849,500 $1,483,000 $82,808,500 $78,545,000

6

A similar analysis was performed to calculate the total 20-year costs for grouping 20 homes. Figure F.2 7

shows an example of a 20-home grouping located off Trading Post Trail and 42nd street in Afton. As 8

shown in Table F.9, there is a large increase in costs when connecting 20 homes to form a small 9

community water system due to the required redundancy for a public water system. However, Afton has 10

limited areas where 20 homes are close enough to be connected as one small community water system 11

and there would need to be supplemental systems with less than 20 homes per group to make this 12

option possible. This system would require approximately 6,500 feet of piping to connect 20 homes, 13

where an average home is spaced 350 feet apart. It was assumed 4” PVC piping would be used and the 14

GAC treatment system was sized based on the gallons per minute it would treat. In order for the 15

requirements of redundancy to be met, two wells would be required along with a certified water 16

operator, additional water quality testing, and a backup generator for one well. 17



Figure F.2. Example of a 20 home grouping in Afton. 1

2 3

Table F.9. Cost analysis for grouping 20 homes in Afton. 4

Alternative

Groups of 20 home small community

water systems

Individual homes with private wells

and POETs Initial cost

(capital)

Annual operating

cost


O&M)



1 0 1105 $2,762,500 $1,105,000 $28,619,500 $25,746,500

2 10 905 $17,557,500 $1,522,000 $51,756,500 $48,166,500

3 25 605 $39,750,000 $2,147,500 $86,462,000 $81,796,500

4 35 405 $54,545,000 $2,564,500 $109,599,000 $104,216,500

5 45 205 $69,340,000 $2,981,500 $132,736,000 $126,636,500

6 55 5 $84,135,000 $3,398,500 $155,873,000 $149,056,500

5

From the results above, grouping both 8 and 20 homes to create a small community water system is 6

possible but would not produce cost saving benefits when compared to treating each home individually 7

with a POET system. The unit costs used for the calculations are shown in Figure F.10. 8

F.3.4 West Lakeland 9

For West Lakeland, two analyses were performed to determine if a small community water system of 8 10

and 20 homes would create a cost savings over treating non-municipal wells with POET systems. These 11

analyses were similar to those performed for Afton (Section F.3.3).The total costs were calculated using 12

the same methods as above. 13

Figure F.3 shows an example of connecting 8 homes in West Lakeland to a small community water 14

system. The example grouping of homes shown is located east of Manning Ave off 24th street. In West 15

Lakeland, there are many areas of opportunity to create small community water systems. The homes in 16

West Lakeland are on average spaced a distance of 300 feet apart which makes connecting 8 - 20 homes 17

with a small community water system from a single well possible. The average estimated distance to 18

connect 8 homes in West Lakeland is 3,000 feet. As shown in Table F.10, grouping 8 homes to create a 19

small community water system would provide a less expensive option over grouping 20 homes but 20

would not provide sufficient cost savings over individual treatment with a POET system. As the number 21

of homes per well decrease the number of wells required to be drilled and equipped with a POET system 22

increases, which largely increase the total costs (Table F.10). 23



Figure F.3. Example of four 8 home groupings in West Lakeland. 1

2

Table F.10. Cost analysis for grouping 8 homes in West Lakeland. 3

Alternative


water systems

Individual homes with

private wells and

POETs Initial cost (capital)



O&M)



1 0 1314 $3,285,000 $1,314,000 $34,032,600 $30,616,200

2 30 1074 $12,516,000 $1,371,000 $44,010,600 $40,312,200

3 60 834 $21,747,000 $1,428,000 $53,988,600 $50,008,200

4 90 594 $30,978,000 $1,485,000 $63,966,600 $59,704,200

5 130 274 $43,286,000 $1,561,000 $77,270,600 $72,632,200

6 160 34 $52,517,000 $1,618,000 $87,248,600 $82,328,200

4


shows an example of a 20-home grouping located on Morgan Ave and Mystic Ride Ave. As shown in 6

Table F.11, there is a large increase in costs when connecting 20 homes to form a small community 7

water system due to the required redundancy for a public water system. The average estimated feet of 8

pipe required to connect 20 homes in West Lakeland is 6,500 feet. This option is less cost-effective than 9

individual treatment with a POET system. 10

Figure F.4. Example of a 20 home grouping in West Lakeland. 11

12



Table F.11. Cost analysis for grouping 20 homes in West Lakeland. 1

Alternative

Groups of 20 home

small community

water systems


private wells and




O&M)



1 0 1314 $3,285,000 $1,314,000 $34,032,600 $30,616,200

2 15 1014 $25,477,500 $1,939,500 $68,738,100 $64,246,200

3 25 814 $40,272,500 $2,356,500 $91,875,100 $86,666,200

4 35 614 $55,067,500 $2,773,500 $115,012,100 $109,086,200

5 45 414 $69,862,500 $3,190,500 $139,149,100 $131,506,200

6 65 14 $99,452,500 $4,024,500 $184,423,100 $176,346,200

2

From reviewing the information collected during the analysis on West Lakeland, by decreasing the 3

number of individual treatment installations the total costs will increase. The unit costs used for the 4

calculations are shown in Appendix E. Individual treatment remains the most cost-effective option. 5

F.3.5 Grey Cloud Island 6

For Grey Cloud Island, two analyses were performed to determine if a small community water system of 7

8 and 20 homes would create a cost savings over treating non-municipal wells with POET systems. These 8

analyses were similar to those performed for Afton (Section F.3.3) and West Lakeland (Section F.3.4). 9

The total costs were calculated using the same methods as above. 10

The homes in Grey Cloud Island are spread further apart with an average distance of 380 feet between 11

homes (compared to 350 feet for Afton and 375 feet for West Lakeland Township). Due to the large 12

spacing between homes, there is a lack of pockets where 8 - 20 homes exist within close enough 13

distance to create a small community water system. Figure F.5 shows an example of an 8-home 14

grouping in Grey Cloud Island located off Grey Cloud Island Drive west of Pioneer Road. On average, 15

4,000 feet of pipe would be required to connect 8 homes and 8,000 feet of pipe would be required to 16

connect 20 homes in Grey Cloud Island. As shown in Table F.12, grouping 8 homes to create a small 17

community water system would not lead to any cost savings over individual treatment with a POET 18

system. 19

Figure F.5. Example of three 8 home groupings in Grey Cloud Island. 20

21



Table F.12. Cost analysis for grouping 8 homes in Grey Cloud Island. 1

Alternative


water systems


private wells and


Annual operating

cost


O&M)


net present value with 3%

discount

1 0 126 $315,000 $126,000 $3,263,400 $2,935,800

2 3 102 $1,528,800 $137,400 $4,674,000 $4,312,500

3 6 78 $2,742,600 $148,800 $6,084,600 $5,689,200

4 9 54 $3,956,400 $160,200 $7,495,200 $7,065,900

5 12 30 $5,170,200 $171,600 $8,905,800 $8,442,600

6 15 6 $6,384,000 $183,000 $10,316,400 $9,819,300

2


shows an example of a 20-home grouping located off Grey Cloud Island Drive west of Pioneer Road. As 4

shown in Table F.13, creating a small community water system of 20 homes would provide no cost 5

savings over individual treatment with POET systems. The unit costs used to estimate the costs for Grey 6

Cloud Island Township are shown in Figure F-12. 7

Figure F.6. Example of a 20 home grouping in Grey Cloud Island. 8

9

Table F.13. Cost analysis for grouping 20 homes in Grey Cloud Island. 10

Alternative

Groups of 20 home

small community

water systems


private wells and


Annual operating

cost


O&M)


net present value with 3%

discount

1 0 126 $315,000 $126,000 $3,263,400 $2,935,800

2 2 86 $3,653,800 $217,000 $8,430,000 $7,951,400

3 3 66 $5,323,200 $262,500 $11,013,300 $10,459,200

4 4 46 $6,992,600 $308,000 $13,596,600 $12,967,000

5 5 26 $8,662,000 $353,500 $16,179,900 $15,474,800

6 6 6 $10,331,400 $399,000 $18,763,200 $17,982,600



F.3.6 Average cost per home for community water systems 1

Results from the 8 home and 20 home small community water systems may be extrapolated further to 2

100 home and 500 home systems. 3

For the city of Afton and West Lakeland Township only, a cost analysis was performed to estimate the 4

costs related to creating a small community system of 100 or 500 homes. This analysis was not 5

performed for Grey Cloud Island due to the small number of homes and large space between homes 6

within the township. 7

For both Afton and West Lakeland Township, the population density and lack of existing infrastructure 8

create conditions where the use of POET systems as the most cost-effective method to deliver safe 9

drinking water, when compared to community treatment systems of any size. 10

In Table F.14, the average cost per home over 20 years can be estimated to further compare the cost 11

differences between treating wells individually with POET systems or with 8-500 home community 12

water systems. Treating private wells individually with POET systems remain the most cost-effective 13

option followed by treating an 8-home community, 500 home community, 100 home community, and 14

20 home community. 15

The most significant parameters affecting the total 20-year costs include installing the GAC treatment 16

systems and installing pipe. The parameter which impacts the total cost the least is the cost for drilling a 17

new community well. Table F.15 illustrates how the small community water systems progressively add 18

costs for additional upfront capital infrastructure items. 19

Table F.14. Average cost per home over 20 years. 20

Community

Private well with

POETs

8 home community

water system with treatment

20 home community


100 home community


500 home community


Afton $25,900 $76,600 $143,600 $120,800 $131,800

West Lakeland $25,900 $67,800 $142,300 $118,500 $110,900

Grey Cloud Island $25,900 $86,100 $172,300 N/A N/A

21 Table F.15. Scope of work which influence the cost estimates of individual POET systems versus 22 community water systems. 23

Infrastructure item

POET on existing private well

Small community water system (<8 homes)

Medium community water system (20 homes)

Large community

water system (up to 100 to 500 homes)

Well Existing New

1 Required

New

2 Required

New

2 or More Required

Linear Infrastructure (water supply piping)

None New New New

Treatment system New New New New



Building In existing home New structure at well (with electrical and heat)

New structure at well (with electrical and heat)

New structure at well (with electrical and heat)

Operating Cost Annual media change out

Annual media change out

Annual media change out Annual media change out

Care and Monitoring

By homeowner By homeowner By qualified operator By qualified operator

F.3.7 Conclusion 1

The results from this analysis suggest that implementing a small community water system for either of 2

the three communities examined – Afton, West Lakeland, or Grey Cloud Island is more expensive than 3

installing POET systems. It can be noted that the costs for a small community water system of 8 homes is 4

less than the costs for a public water system of 20-500 homes due to redundancy requirements. 5

However, both options require costs greater than individually treating each well with a POET system. 6

For all three communities, the population density and presence of existing infrastructure create 7

conditions where the use of POET systems as the most cost-effective method to deliver safe drinking 8

water, when compared to community treatment systems of any size. 9



Figure F.7. Potential small community water systems in the City of Afton. 1

2



Figure F.8. Potential small community water systems in West Lakeland Township. 1

2



Figure F.9. Potential small community water systems in Grey Cloud Island Township. 1

2



Figure F.10. Cost summary for the City of Afton. 1

2



Figure F.11. Cost summary for West Lakeland Township. 1

2



Figure F.12. Cost Summary for Grey Cloud Island Township. 1

2

F.4 Treatment technology comparison 3


This section provides information on the various technologies available for the treatment of PFAS in 5

drinking water in the East Metropolitan Area. The life cycle of technology development, as presented in 6



Figure F.13, illustrates how technologies are developed from research and development through to 1

demonstration and validation, and on to full-scale commercialization. Full scale commercialized options 2

to treat PFAS in drinking water are limited due to the difficulty in degrading PFAS, especially 3

perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), and because of the strict 4

requirements for technology approval. Examples of these rigorous standards include the National 5

Science Foundation (NSF) International certification to meet the drinking water treatment requirements 6

in accordance with strict public health standards and State health department requirements for 7

approval and/or certification of drinking water treatment technologies. Current research and 8

development on PFAS treatment sites provide insights into promising and partially demonstrated new 9

technologies. Research and development activities for PFAS water treatment include chemical oxidation, 10

biological degradation, and novel sorption technologies that can be applied in drinking water 11

applications. Although this testing may show promise, these technologies are not currently applicable to 12

drinking water treatment applications and would still need to achieve applicable strict public health 13

standards and State-level certifications. To date, all mature commercially available technologies for 14

treating PFAS in drinking water rely on separation rather than degradation. 15

Below, information is presented on technology effectiveness, limitations, and sustainability pertaining to 16

the following categories of drinking water treatment: 17

• Mature technologies that are commercially available and have been implemented at full scale 18 for treating PFAS in drinking water across the U.S. 19

• GAC 20

• Ion exchange (IX) 21

• Membrane [reverse osmosis (RO, nanofiltration (NF)] 22

• Developing technologies that have been tested at various scales for treating PFAS in drinking 23 water but have not yet been implemented fully and are not approved for use in drinking water 24 treatment. While these systems show promise, they are not considered technologies that can be 25 readily deployed into a drinking water system at the current time. 26

• Zeolite/Organoclay media systems 27

• Biochar systems 28

• Advanced oxidation systems 29

• Sonolysis Treatment Systems 30

Technologies that are currently considered in the developing as well as research and development 31

stages are not considered further in this Conceptual Plan as they are not deemed appropriate for 32

consideration at this time as they are not commercially available and full-scale implementation is not 33

feasible without demonstration and validation at a minimum. 34

Treatment technologies may be similar in many ways but can present several potential advantages and 35

disadvantages regarding sustainable practices. These considerations are presented in Section F.4.2.4. 36



Figure F.13. The life cycle of technology development. 1

2 Source: S. Thomas, Wood plc, used with permission 3

F.4.1.1 Key variables for consideration 4

When developing a drinking water system for the treatment of PFAS there are many important technical 5

and non-technical considerations that need to be evaluated. Key variables are presented in Table F.16 6

and discussed for the various technologies presented. 7

Table F.16. Key treatment technology variables for consideration. 8

Technical Non-technical

Final water treatment requirements Operational costs

Pretreatment requirements Capital costs

Co-contaminants Ease of operation

Water hardness System complexity

Competing ionic species Space required

Product water generated/wastewater generated State certifications/approvals

Disposal of media/residuals NSF/ANSI certification

Performance criteria Availability of equipment/media

System contact volume Impact of changing regulations

F.4.2 Mature technologies 9

Currently, there are three (3) treatment technologies for drinking water that are commercially available. 10

These include GAC, single use IX resins, and membrane processes (RO, NF). Sections F.4.2.1 through 11

F.4.2.3 provide descriptions of these technologies, and Table F.17 provides a comparison. 12

F.4.2.1 Granular activated carbon 13

GAC is used in drinking water treatment, usually as a polishing step, to remove synthetic organic 14

chemicals, natural organic compounds, and other compounds affecting taste and odor. GAC is at the 15

current time, the most widely used treatment method for the removal of PFAS compounds from 16

drinking water. 17

The removal efficiency of PFAS by GAC depends on the functional group and perfluorocarbon chain 18

length of the individual PFAS compound. Removal efficiency increases with increasing perfluorocarbon 19

chain length. Additionally, GAC is less effective for carboxylate functional groups than for sulfonate 20

functional groups. 21



Other factors that will impact the removal efficiency of PFAS removal by GAC include: 1

• Naturally occurring organic matter (NOM): NOM competes with PFAS for adsorption sites. The 2 presence of NOM in the drinking water systems will reduce the adsorption capacity for the 3 target organic chemicals to be removed. 4

• The presence of chlorine. Activated carbon reacts with chlorine (or other oxidants) in a 5 reduction-oxidation reaction, which may change the surface characteristics of the activated 6 carbon and reduce treatment effectiveness. 7

• GAC does not degrade or destroy PFAS. This is considered a separation technology only. 8

GAC systems can be installed relatively easily and require minimal maintenance and operation effort. 9

GAC is placed in packed-bed flow-through vessels, usually operated in series (lead-lag configuration), 10

with typical empty Bed Contact Times (EBCTs) of 10–15 minutes per vessel. Breakthrough is monitored 11

by sampling water, at a minimum, between the lead and lag vessels. When breakthrough exceeds 12

identified criteria, the lead vessel is taken offline and the spent GAC is removed and replaced with new 13

(either virgin or reactivated) GAC. The spent media are disposed of off-site, typically by 14

incineration/thermal destruction, but can also be reused by employing high temperature thermal 15

reactivation. Reactivated PFAS GAC is allowed for use in drinking water application but this should be 16

considered with caution and in accordance with AWWA B605-13 Reactivation of Granular Activated 17

Carbon standard. Certain studies have also shown reduced PFAS removal using reactivated vs. virgin 18

GAC. 19

GAC can be manufactured using various materials (e.g. coal (bituminous), coconut shells, wood, etc.), 20

which all have shown some ability to remove PFAS. Bituminous GAC has generally been demonstrated to 21

be the most effective GAC media and is used for the majority of existing PFAS treatment systems. Media 22

selection and life cycle cost will depend upon a number of factors, including PFAS and co-contaminant 23

concentrations, media availability and pricing, and disposal options/costs. 24

One significant benefit of GAC is that it is widely used with a large network of providers and good 25

availability of both materials but also vendors that provide turnkey replacement services. 26

F.4.2.2 Ion exchange resin 27

IX is a widely accepted process for the removal of targeted, typically inorganic compounds. IX involves 28

the use of resins. Most synthetic IX resins are manufactured by a process in which styrene and 29

divinylbenzene are copolymerized. The styrene serves as the basic matrix of the resin, and 30

divinylbenzene is used to cross-link the polymers to produce ninsoluble tough resin beads. Important 31

properties of IX resin include exchange capacity, particle size, and stability. IX resins can be considered 32

non-regenerable (or single use) that are disposed of after one application or regenerable. IX 33

regeneration involves backwashing the resin bed with a variety of proprietary solutions to remove and 34

concentrate the PFAS and prepare the resin bed for reuse. Regenerable resins are not currently 35

approved for use in drinking water treatment applications in the US and are not considered further in 36

this Conceptual Plan. 37

According to the study conducted by Wood (Woodward, 2018), non-regenerable IX resin has the highest 38

capacity for PFAS, followed by GAC, and then the re-generable IX resin. 39

The removal efficiency of the non-regenerable IX system depends on a variety of factors including the 40

nature of the resin within the beads, competing ions, treatment design (EBCT, size of resin beads, etc.), 41

and physical and chemical properties of the PFAS requiring treatment: 42



• According to a previous literature review conducted by Wood, anion exchange resins are the 1 only effective resin for PFAS removal 2

• Competing ions such as sulfate, nitrates, and heavy metals may impact the sorption capacity of 3 the resin 4

• Based on the bench-scale study conducted by Wood (Woodward, 2018), the long-chain PFAS 5 compounds are generally more effectively removed than short-chain PFAS when using non-6 regenerable IX resin. 7

There are many factors that drive IX resin system design decisions other than removal efficiency. 8

Compared with a GAC system, the capital and operation cost for an IX resin system is lower. Factors such 9

as influent and target PFAS concentration, replacement of resin, arrangement of resin vessels (lead-lag 10

or staggered), and strength of the resin beads will all impact the operation cost of the IX resin system. 11

Non-regenerable IX resin, as indicated by its name, is for one-time use. Once it is exhausted, the resin 12

should be disposed of, thus usually resulting in a more expensive disposal cost than for GAC if that GAC 13

is reactivated. Waste disposal is discussed further in Section F.4.3 below. 14

Typically, the operational cost represents 30% to 70% of the overall life cycle cost of the IX system. The 15

efficient operation of an IX system is critical for the system to achieve optimal treatment performance 16

and maintain lower operational costs. Proper operation includes monitoring of process indicators, trend 17

analysis of influent and effluent parameters, and verification of process steps such as step sequence 18

times and volumetric totals. 19

F.4.2.3 Pressurized membrane processes (reverse osmosis, nanofiltration) 20

NF and RO are forms of membrane filtration technology that are pressure-driven and shown to be 21

effective in the removal of PFAS. Typically, NF systems reject constituents as small as 0.001 µm whereas 22

RO systems reject particles as small as 0.0001 µm. 23

The removal efficiency for PFAS by NF can be greater than 90%, while RO can achieve 100% PFAS 24

removal. The high removal rate for PFAS is primarily due to the molecular weight cut-off (MWCO) of the 25

NF and RO membranes. MWCO is a measure of the removal characteristics of a membrane in terms of 26

atomic weight. The typical range of MWCO levels for NF ranges from 200 to 1,000 Daltons while for RO 27

it is generally less than 100 Daltons (USEPA, 2018). The molecular weight for PFOA and PFOS are 500 and 28

414 Daltons respectively, meaning PFOA and PFOS can be easily removed by NF and RO system. 29

The following factors will impact the performance of membrane filtration systems: 30

• Pressure: The operation pressure will affect the water flux across the membrane and the 31 recovery rate. For NF membrane, the typical feed pressure range is between 50 to 150 pounds 32 per square inch (psi), while for RO membrane, typical feed pressure ranges between 125 to 33 1,200 psi, depending on osmatic pressure and required production flux. 34

• Temperature: The membrane filtration system performance is very sensitive to the changes in 35 feed water temperature. As the feed water temperature increases, the water flux increases 36 almost linearly (which is often preferred since it will increase the recovery rate), however, the 37 contaminant removal/rejection rate will be lowered (not preferred since it decreases the quality 38 of treated water). 39

• Salt concentration: For RO systems, osmotic pressure is a function of the salt concentration. As 40 the salt concentration increases, the osmotic pressure increases. If the feed pressure remains 41 constant, higher salt concentration will result in lower membrane water flux since the increased 42 osmotic pressure offsets the feed water driving pressure. 43



• Recovery rate: Recovery rate is defined as the ratio between permeate stream flow and feed 1 stream flow. Typically, the recovery rate for NF is typically higher than for RO systems. Systems 2 used for drinking water applications should be able to attain 90% recovery for NF systems and 3 80% recovery for RO systems. 4

Despite its high removal efficiency for PFAS, the capital and O&M costs for membrane systems are 5

usually high compared with sorption systems (i.e., GAC and IX resins). Other than economic factors, 6

operation issues such as membrane fouling and rejected stream treatment usually limits the application 7

of the membrane filtration systems. 8

Pretreatment is often necessary when working with NF and RO systems. The primary objective of 9

pretreatment is to remove/reduce the constituents that contribute to membrane fouling and make the 10

feed water compatible with the membrane. It is expected that by pretreatment, the efficiency and life 11

expectance of the membrane elements will be improved. 12

Another operation issue for the membrane filtration system is the production of a concentrated waste 13

stream. The concentrate from NF and RO facilities will not only contain elevated concentrations of 14

contaminants of interest, but it can also contain hardness, heavy metals, and high-molecular-weight 15

organics. The disposal of the concentrated waste stream includes discharge to wastewater collection 16

systems and thermal evaporation. 17

Table F.17. Comparison of drinking water treatment technologies. 18

Technology Advantages Disadvantages

GAC 1) GAC is the most widely used technology for PFAS removal, especially for long-chain PFAS; the removal efficiency is > 90% for long-chain PFAS

2) Given the design and operation configuration of the fixed-bed column, it is possible to achieve very low PFAS level in treated water

3) Low capital and operation costs 4) Waste steam can be thermally treated (i.e.,

reactivation)

1) Not suitable for treating water that contains high levels of organic compounds

2) Carbon can react with oxidants such as chlorine, so that should be avoided or used after oxidation or disinfection procedure

3) Not as efficient as IX for shorter chain PFAS

Non-regenerable IX Resin

1) Non-regenerable resin has the highest sorption capacity among GAC and regenerable IX resin; the removal efficiency is > 90% for long-chain PFAS

2) Given the design and operation configuration of the fixed-bed column, it is possible to achieve very low PFAS level in treated water

3) No concentrated waste stream will be produced (since no regeneration is required), however, need to consider the disposal of spent resin

1) Not suitable for treating water containing high levels of sulfates, nitrates, and heavy metals unless pre-treatment measures are in place

2) Since regeneration is not feasible, the spent resin needs to be changed out once exhausted. Operation cost is expected to be higher than the regenerable IX resin system, however, still significantly lower than the membrane filtration system (NF and RO). Need to consider the treatment and disposal of the spent resin.



Technology Advantages Disadvantages

NF 1) Removal efficiency for PFAS is greater than 90%

2) Less footprint compared to traditional treatment options

1) Depending on the water quality, pretreatment may be required

2) Usually high capital cost 3) Operation cost is high due to energy cost,

cleaning cost, labor, and chemical consumption

4) Recovery rate may be low depending on the quality of raw water

5) There is no real treatment for concentrated waste stream

3) High demand for O&M to achieve optimal treatment.

RO 1) Removal efficiency for PFAS is close to 100%, effective for both long-chain and short-chain PFAS

2) Less footprint compared to traditional treatment options

1) Depending on the water quality, pretreatment may be required

2) Usually high capital costs 3) Operation cost is high due to energy cost,

cleaning cost, labor, and chemical consumption

4) Recovery rate may be low depending on the quality of raw water

5) There is no real treatment for concentrated waste stream

6) High demand for O&M to achieve optimal treatment

1

F.4.2.4 Comparison of key treatment variables and sustainability evaluation 2

In the evaluation of PFAS drinking water technologies, specific treatment variables are considered to 3

ensure reliability, efficiency, and long-term system economics are optimized. Sustainability 4

considerations, including environmental impacts of the system manufacturing, carbon emissions, and 5

disposal, are also drivers to the selection of the treatment technology of choice. 6

Table F.18. Key treatment variables and sustainability evaluation factors. 7

.Sustainability consideration GAC IX Membrane Systems

Media materials Can be coal (less sustainable) or coconut shells and wood (more sustainable)

Synthetically manufactured materials

A variety of materials are used for NF and RO membranes including cellulose acetate, poly amide, and ceramic media

Media availability

More widely used treatment technology, and therefore more widely available

Media widely used, but specialty media demands may out-weigh supply

Widely used and easily procured materials

Timeline to Implement

Easily implementable systems. Vessels and media readily available.

Easily implementable systems. Vessels available but media may require lead-time.

More complex implementation. Systems are generally custom built with longer equipment lead times and on-site fabrication.



.Sustainability consideration GAC IX Membrane Systems

Vessel size/amount of media required

Larger media vessels (more media required) relative to IX

Vessels sizes are approximately 20-25% that of GAC vessels

Relatively small systems footprint compared to GAC and IX systems

Building space/footprint

Larger buildings to house treatment system due to large vessels

Smaller vessel sizes result in less building space than GAC

Small building footprint required for membrane systems, but ancillary systems for reject water management and chemical cleaning of membranes increases systems space requirements

Waste/disposal Reactivation of media; destruction or disposal of spent media available

Destruction or disposal of spent non-regenerable media available; regenerated media not applicable for drinking water applications

Reject water requires disposal. A critical factor in assessing a membrane system is the ability to dispose of the contaminated reject water

Lifespan Media in drinking water applications depends on feed water concentrations. For typical applications in drinking water expected life of media is 6 months to 1 year

Compared to GAC, media life is 2-3 times greater.

Typically RO and NF membranes have a life of 5 to 10 years in a drinking water application

O&M Simple flow through operation. Media cost and disposal are the primary O&M costs.

Simple flow through operation. Media cost and disposal are the primary O&M costs.

More complex operation due to high pressure feed pump systems and the need to re-mineralize product water

Adaptability GAC is very effective at removing longer chain PFAS compounds. Shorter chain compounds break through more rapidly.

IX systems lend themselves to future regulations on shorter chain PFAS compounds as the IX media is typically more effective in removing these compounds than GAC.

Highly adaptable to changing feedwater characteristics.

Very sensitive to flow changes.

Ancillary benefits Taste and odor control where NOM is present.

Removal of organic co-contaminants

Will provide soft water (RO)

Co-contaminant removal

Other impacts RO generated water can be aggressive towards infrastructure and needs to be re-mineralized to reduce corrosion /metal leaching impacts.



F.4.3 Waste disposal and management 1

F.4.3.1 Incineration 2

Incineration is a waste destruction process that involves the combustion of organic substances 3

contained in waste materials. Incineration and other high-temperature waste treatment systems are 4

termed thermal treatment processes. Incineration is a mature technology that has been used for a wide 5

variety of organic wastes. Heat is applied directly to the contaminated solids or liquids to completely 6

oxidize them. Gaseous combustion by-products are controlled to prevent atmospheric pollution. 7

Incineration is often preceded by the concentrated waste generating technologies previously discussed 8

(GAC, IX, or RO) as a PFAS destruction step. 9

Incineration is one of the few technologies that can completely destroy PFAS at temperatures greater 10

than 1,200 degrees Fahrenheit. Hazardous waste incinerators are fixed facilities capable of reaching 11

PFAS-destructive temperatures. Federal and state permits dictate the materials that may be processed, 12

core incinerator operations (for example, temperature and time), and control of process air, liquid, and 13

solid wastes. Permit and design/construction similarities reduce the operational and performance 14

differences between individual incinerators. Transportation costs, energy costs, and final disposal of 15

process waste residues differ among incinerators. The cost of incineration has a significant impact on 16

treatment costs. 17

The sustainability impacts of incineration include transporting contaminated material, and energy-18

intensive processing involving the combustion of fossil fuels to achieve the thermal destruction of 19

contaminants. No hazardous waste incinerators are located in the East Metro Study area with the 20

exception of the 3M incinerator at the Cottage Grove Facility. 21

F.4.3.2 Landfill 22

Landfill disposal is a common method for the disposal of solids waste materials generated by water 23

treatment and industrial residuals. PFAS treatment residuals including single use IX resins and non-24

regenerable activated carbon can be disposed in a secure industrial landfill. Some landfills, both 25

municipal and hazardous waste, will not accept PFAS containing material. Current federal regulations do 26

not define PFAS as hazardous substances or hazardous wastes however, that may be a consideration in 27

the future as new regulations are passed. 28

The sustainability impacts of landfilling include the hauling of waste material, landfill activities 29

(construction, backfill), as well as general emissions from landfills including contaminated leachate 30

treatment requirements. If future federal designation of PFAS as a hazardous waste requires out-of-31

state transportation for landfill disposal, significant costs and secondary environmental impacts may be 32

incurred for these waste materials. 33

F.4.4 Other Variables 34

Additional considerations in the selection of a PFAS drinking water technology include regulatory 35

requirements, industry specific certifications, State or Federal certifications, and regulatory performance 36

for non-regulated contaminants (short chain PFAS). Table F.19 is a summary of additional considerations 37

in the selection of PFAS drinking water treatment technologies. 38



Table F.19. Additional considerations in the selection of PFAS drinking water treatment technologies. 1

Additional considerations GAC IX Membrane Systems

NSF 61 Certification

Specific GAC media is certified NSF 61. Widest range of available NSF media.

IX resins have limited NSF certification. Of those, only a few are applicable to PFAS

RO and NF membranes are widely used in a variety of potable water applications. A wide array of membranes have NSF 61 certification.

State certification/ approval

Widely used treatment technology, most generally accepted by regulators.

Gaining acceptance with regulators as systems come on line. Not currently approved by MDH for PFAS.

Widely used treatment technology, generally accepted by regulators. Not currently approved by MDH for PFAS.

Regulatory performance

As more short chain PFAS compounds become regulated. GAC applicability may decrease or require post treatment. Able to meet regulated PFAS compound criteria.

Better performance for short chain compounds so long-term outlook may be better than GAC. Currently able to meet regulated PFAS compound criteria.

Able to remove 100% of PFAS compounds to below detection. High degree of regulatory confidence. Waste material compliance is uncertain. Liquid disposal is more difficult than solid phase media (GAC & IX).

F.4.5 Conclusions 2

In conclusion, sorption (i.e., GAC) or IX (i.e., non-regenerable IX) are currently the technologies of choice 3

for drinking water treatment for PFAS contaminated drinking water compared to membrane filtration. 4

The advantages of sorption and IX are the relative simplicity of the technologies, low residuals 5

production, and the high degree of effectiveness. Between these two methods for treatment of PFAS, 6

GAC has the widest application and has relatively low capital and O&M costs. Currently GAC is the only 7

MPCA approved technology for PFAS treatment of drinking water. IX systems will have generally lower 8

capital costs to implement over GAC systems, but the availability of resins, and disposal of exhausted 9

resin material may be a challenge with the current demand on the supply-chain for these materials. The 10

quality of the raw water needs to be considered and if the raw water has significant co-contaminant 11

concentrations, GAC will lose its sorption capacity relatively quickly, resulting in increased media 12

consumption. IX is currently undergoing pilot trials in Cottage Grove with the intent of providing MPCA 13

with data to demonstrate its effectiveness. 14

There are several technologies that are in development and have the potential to provide high efficiency 15

removals of PFAS in drinking water treatment systems. Advancements in regenerable IX technology 16

have been applied to remediation pump and treat systems, and it is possible that these systems may 17

prove to be applicable to drinking water systems in the US in the future (see Draft Technical 18

Memorandum 1, Desktop Evaluation of Alternatives – GenX and Other PFAS Treatment Options Study, 19

Black and Veatch, July 2017). Advanced oxidation systems (e.g., ozone, persulfate, electrochemical) 20

show some promise for the treatment of PFAS material and may provide a means to destroy PFAS in the 21

drinking water process. To date, these systems have shown limited effectiveness, but research 22

advancements in this area may have applicability in drinking water systems. Finally, the application of 23

biological treatment processes is an area that has seen recent advancements, with reports of complete 24

mineralization of PFAS. These systems also have the ability to destroy PFAS and may provide an option 25

for the treatment of PFAS in drinking water in the future. 26

https://www.cfpua.org/DocumentCenter/View/9227/Cape-Fear-TM?bidId=




Documents

F Scenarios supporting documentation€¦ · Draft, February 2020 ... 18 side (inlet pressure) makes sure that a certain pressure on the outlet side (outlet pressure) is not 19 exceeded,