Help Instruction File:

Polymer Module Overview

Provided by the Office of Surface Mining Reclamation and Enforcement (OSMRE), the Pennsylvania Department 

of Protection (PADEP), the U.S. Geological Survey's (USGS) and the West Virginia Department of Environmental 

Protection (WVDEP).
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Polymer Module Overview

Table of Contents

1.0 OBJECTIVE 3

2.0 OVERVIEW AND APPLICATION 3

2.1 Physical and Chemical Properties 3

2.2 Benefits/Drawbacks, Equipment and Typical Treatment Configurations 6

2.2.1 Benefits: The major reason why polymer is popular is its ability to promote the formation of floc from 

individual metal precipitates, enhancing the settleability of the particles and creating an effluent with low 

suspended solids. The benefits of using polymer as a component of a mine drainage treatment system include: 7

2.2.2 Drawbacks: The drawbacks of using polymer as a mine drainage treatment chemical include: 7

2.2.3 Equipment and Typical Treatment Configurations: 8

2.2.3.1 Dry Polymer 8

2.2.3.2 9

2.2.3.3 Pre-Diluted 9

2.3 Application and Financial Analysis 10

3.0 POLYMER MODULE OVERVIEW 10

3.1 Layout and Workflow 10

3.2 Module Inputs 11

3.2.1 Water Quality and Flow Input 11

3.2.2 Anionic Polymer Flocculant Information 12

3.2.3 Equipment and System Installation 12

3.2.3.1 Dry Polymer Equipment 12

3.2.3.2 Emulsion Polymer Equipment 13

3.2.3.3 Pre-Diluted Polymer Dosing Equipment 13

3.2.4 Annual Cost Input 14

3.2.4.1 Polymer System Operational Time - 14

3.2.4.2 Unit Cost of Water - 14

3.2.4.3 Polymer Pump Power - 14

3.2.4.4 Electrical Unit Cost - 15

3.2.4.5 Delivered Unit Price of Selected Polymer Product - 15

3.2.5 Other Capital Items 15

3.2.6 Other Annual Items 15

3.3 Module Outputs 15

3.3.1 Sizing Summary 15

3.3.2 Capital Cost 16

3.3.3 Annual Cost 16

3.3.4 Net Present Value 16

3.3.4.1 Financial Variables 16
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3.3.4.2 Cost Categories 17

3.3.4.3 Rationale for Recapitalization Recommendations 18

3.4 Assumptions of Design Sizing and Costs 19

4.0 REFERENCES 20

5.0 FIGURES 21

Figure 1: Blending skid with progressive cavity pump and computerized controls for emulsion polymer 

used at a site for flocculating iron hydroxide sludge and dewatering in Geotubes. 21

Figure 2. Emulsion polymer totes (275-gallon) for use at a mine drainage treatment facility in 

Pennsylvania. 22

Figure 3. Super sack (1,650 lbs) feeder option as part of an automatic dry polymer make down system that 

automatically dispenses dry polymer product to produce a made down solution. 23

Figure 4. Manual make down of dry polymer into day tank using Hootonanny Eductor system on top of 

tank at a mine drainage treatment facility. 24

Figure 5. Stainless steel blending/aging tank for made down dry polymer solution with mixers mounted 

over the tanks. 25

Figure 6. Pumps and inline static mixers for mixing the made down polymer solution with push (dilution) 

water prior to addition to the mine drainage source. 26

Figure 7. Photo of two pumps as part of the dosing skid component of a dry polymer automatic system. 27

Figure 8. Application point of polymer into the mine drainage at a treatment facility. 28
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1.0 Objective

The objectives of this overview are to: (1) Provide an understanding of the application of polymer in mine 

drainage treatment and (2) Provide an overview of the Polymer module to guide users in developing an 

estimate of the cost to construct, operate, and maintain the polymer component of mine drainage

treatment systems. The module can also be applied to reverse cost model the polymer component of an 

existing treatment system to establish and evaluate future financial and investment decisions. The

information is presented in two sections, Overview and Application and Polymer Module Overview. 

2.0 Overview and Application

A basic understanding of the chemical and physical properties, the application, and equipment 

requirements of the polymer component of a mine drainage treatment system are required to develop a 

treatment strategy using the AMDTreat software. These topics are discussed below before discussing the 

module interface and functionality to provide the necessary context. The Overview and Application 

section is organized into three parts: (1) Physical and Chemical Properties and (2) Benefits/Drawbacks, 

Equipment and Typical Treatment Configurations, and (3) Application and Financial Analysis. 

2.1 Physical and Chemical Properties

The most common type of polymer products used in mine drainage treatment are synthetic (man-made) 

anionic polyacrylamide flocculant polymers, which are organic compounds used as flocculants. Polymers 

are manufactured in different forms but the most common three used in mine drainage treatment include a 

dry granular material, emulsion, and pre-diluted polymer. These types of readily available polymers are 

classified as non-hazardous substances by the Occupational Safety and Health Administration (OSHA). 

However, some of the hazards indicated on polymer material safety data sheets (MSDS) consist of (1) 

skin irritant and (2) eye irritation. Polymer is also extremely slippery, particularly in liquid form, and 

should be cleaned up based on the manufacturer’s recommendations if spilled. A system designed with a 

small containment concrete curb or similar containment structure will greatly facilitate cleanup of spilled 

polymer and minimized associated slip and fall hazards. Please see the MSDS for additional information 

on the applicable polymer product. This help file and AMDTreat Polymer Module does NOT

comprehensively address the overall site safety precautions that must be considered when 

designing, operating or maintaining a polymer component of a treatment system. System designers 

and operators must consult with qualified and knowledgeable chemical and equipment providers in 

order to adequately address site and personnel safety concerns. 

Polyacrylamide polymers are chains of organic molecules made up of smaller molecules referred to as 

monomers. Anionic polymers have a negative charge and are commonly used in applications to settle 

inorganic solids such as metals, clays, and silts as they are effective at the separation of mineral-based 

liquid-solid applications. Cationic polyacrylamide polymers are also organic in composition but possess 

positive charged surfaces and are much less commonly used in most mine drainage treatment 

applications. Polymer manufacturers offer a variety of different molecular weight and charge density 

configurations. Typically, polymer sales technicians will assist treatment plant designers and operators in 

selecting the best performing polymer for their particular application through on-site testing of the treated 

mine water. 
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Metal precipitates (solid) that form when either alkaline addition is performed increasing the pH for net 

acidic mine drainage or oxygen is added to net alkaline mine drainage may hold a surface charge that 

prevent the individual floating particles from combining to form larger particles allowing them to more 

readily settle out of the water. In the case of mine drainage this is most commonly a net positive surface 

charge. Consequently, anionic polymers which by definition have negatively charged surfaces are the 

preferred choice. This is apparent particularly where a net alkaline mine drainage source surfaces, is

introduced to oxygen through aeration and is observed in multiple settling ponds in series appearing to be 

a cloudy orangish color due to the suspended iron precipitates that have formed from ferrous iron being 

oxidized to ferric iron. If sufficient retention time is not provided for the suspended iron particles to 

eventually floc naturally in order to settle out of the water or if surfaces such as those present in wetland 

vegetation are available for the iron particles to adsorb/attach then the suspended iron particles will 

discharge from the treatment system. There are a number of examples where polishing wetlands have 

been employed as components of both passive and active treatment systems to enhance flocculation and 

settling. In much the same manner as anionic polymers, surfaces of wetland plants are net negatively 

charged which promote removal of suspended iron and other positively charged metal particles. The 

following weblink to OSMRE’s Flight 93 webpage provides a much more detailed discussion of 

enhanced solids removal by polishing wetlands:

https://www.arcc.osmre.gov/programs/TDT/flight93.shtm

Polymer functions by allowing the iron particles to floc together, bonding to the oppositely charged 

polymer surface, forming larger particles that will settle out of the water. There are many different 

manufacturers of anionic polymer flocculant products and it is important to conduct the appropriate jar 

tests or bench scale testing using the water to be treated with any perspective polymer product to confirm 

the effectiveness at settling the precipitated solids, desired solution strength of polymer, and the dosage 

that works the best. The anionic polymer flocculant product is most commonly applied prior to the mine 

water entering the settling pond or clarifier in order to maximize the floc formation by causing the 

precipitated metal solids to combine or “floc” forming larger particles that will more readily settle out of 

the water. The polymer increases the rate of sedimentation of the solids producing a dense sludge in the 

settling pond/clarifier allowing the water to contain low suspended solids upon discharge from the settling 

unit. The resulting sludge when polymer is applied is also more readily dewatered for disposal.

The type of polymer product selected is important since it will dictate the type of equipment needed to 

prepare the polymer for addition to the mine drainage treatment process. In general, polymer is water 

soluble and has a finite shelf life depending on the type of polymer to be used. Dry Polymer contains the

highest amount of active flocculant ingredient, normally greater than 90%, and is expected to last up to 2

years if kept dry until it must be used. For a Dry Polymer product, the product will need to be mixed 

with water as part of a process referred to as make down in order to dissolve the polymer product and to 

be stored in a holding tank for use. The made down polymer product is normally made with a solution 

strength less than or equal to 0.5% by weight (% wt). If solution strengths of the made down polymer are 

greater than 0.5% wt and the initial high energy mixing process is not efficient, the solution will result in 

the formation of “fish-eyes”, which are unhydrated polymer particles surrounded by a gelatinous layer of 

hydrated polymer, rendering the unhydrated particles ineffective at carrying out the role of the polymer.

“Fish-eyes” can also create clogging issues in the feedlines and equipment. The made down polymer is 

then mixed with what is commonly referred to as ”push water” in order to provide further dilution to 

create the desired solution strength of 0.1% or less and transport the polymer solution to the application 

point with the mine water. In-line static mixers are often utilized to further promote mixing of the 

polymer (neat) solution with the additional push water. The lowest solution strength practically 
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achievable is the objective as this will promote mixing of the polymer/push water solution with the mine 

water as the mine water density and solution density will closely approximate one another. At the point 

of polymer application to the mine drainage the correct volume of polymer must be added to result in the 

target dosage commonly expressed in parts per million (ppm) in the mine drainage. Typical target dosing 

rates for anionic Dry Polymer in mine drainage are between 0.5 and 1.0 ppm. Please note, in this module

it is assumed that the Dry Polymer will be delivered as a solid in either 55 lb Bags or 1,650 lb Super 

Sacks (bulk). The product must then be made down on site in order to create the necessary solution 

strength for the dosage rate needed with the mine drainage, which requires a clean water source at the 

treatment site for both the make down process and to use as push water. Clean water sources are not 

necessarily limited to potable or purchase water sources. In many cases treated effluent is utilized for both 

the make down and push water components. However, suspended solids concentrations must be low and 

ideally Total Dissolved Solids (TDS) concentrations of the source water should not be excessively high. 

Low TDS water is most applicable for the initial make down of Dry Polymer, or as in the case of 

emulsion polymer for the initial polymer inversion step and much less of a consideration for push water 

applications.. System designers should also note that in sizing storage tanks for the made down neat 

polymer solution several factors must be considered. First, neat solutions made from Dry Polymer should 

be allowed to “age” for approximately 24 hours before use for peak efficiency. Secondly, neat polymer 

solutions made from Dry Polymer will have a shelf life and ideally should be fully utilized no longer than 

2 to 3 days after make down. Otherwise, the organic molecules within the polymer will significantly 

degrade. Emulsion Polymers and the dilute solutions made from them do not requiring aging to achieve 

maximum efficiency and are not as susceptible to shelf-life degradation concerns. Please see Section 3.4 

of Help File for assumptions. 

The second option for anionic polymer products to use in mine drainage treatment is Emulsion Polymer. 

The Emulsion Polymer product is a liquid consisting of coiled chains of polymer suspended in water 

droplets dispersed in oil. The percent activity of Emulsion Polymers ranges from 20 to 50% wt, requiring 

a dose of Emulsion Polymer two to three times greater than that of Dry Polymer (90% active). Emulsion 

Polymer is most commonly supplied in 275-gallon totes at mine drainage treatment sites. The Emulsion 

Polymer is then pumped from the tote to a mixing unit where it is first mixed with a clean water source to 

provide inversion, and then mixed with additional push water for dilution before conveyance to the 

application point with the mine drainage. Most Emulsion Polymers contain an inverting surfactant that 

assists with the inverting phase from a coiled polymer dispersed in oil to coiled polymer dispersed in push 

water. Many of these inverting surfactants contained in Emulsion Polymers are intended to start inversion 

when the polymer is diluted to a concentration between 1 to 2% wt. As a result, some treatment sites will 

first pump the Emulsion Polymer into an aging tank where water is added to the polymer to produce a 

solution strength of 1 to 2% wt for inversion and then pumped to a mixing unit where it is blended with 

push water to further dilute the polymer to a 0.1% wt solution strength. However, many of the more 

recent Emulsion Polymer pump skids and mixing units are designed to pump the Emulsion Polymer

directly into the mixing unit where it is mixed with push water using sufficient energy to promote 

inversion of the product without the use of the aging tank step. Typical dosing rates of Emulsion Polymer

in mine drainage treatment is 2.5 to 3.5 ppm. If kept airtight in a tote, Emulsion Polymer can be stored 

roughly 6 months before it must be used.

Pre-Diluted Polymer is the third and final type of anionic polymer used in mine drainage treatment,

particularly at remote sites where electricity is not available. Similar to Emulsion Polymer, Pre-Diluted 

Polymer is most commonly provided in 275-gallon totes. The Pre-Diluted Polymer is made by chemical 

distribution companies by dissolving Dry Polymer into water to produce a 1.0 to 1.25% wt solution. 
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Some companies produce Pre-Diluted Polymer products using a brine solution to allow the polymer to 

dissolve but not fully uncoil in order to allow an extended shelf life of more than 3 months. The most 

common application of pre-diluted polymer in mine drainage treatment is to pump or gravity feed with a 

needle valve the polymer solution directly into the mine drainage. Alternatively, where the mine drainage 

source is pumped, static mixers are used to more thoroughly mix the mine water and polymer solution. 

Target dosing rates for Pre-Diluted Polymer is the same as made down Dry Polymer, ranging from 0.5 to 

1.0 ppm.

Table 1 provides characteristics of the three types of polymers used in the module including the default 

values for each item in the Anionic Polymer Flocculant Information section.

Polymer 

Type

Product 

Container 

from 

Supplier

Target 

Dose 

(ppm)

Product 

Density 

(lbs/gal)

Activity 

(%)

Desired 

Strength of 

Made 

Down 

Polymer 

(% wt)

Desired 

Strength 

in Push 

Water 

(% wt)

Product 

Unit Cost 

($/lb)

Dry 

Polymer

55 lb Bags, 

1,650 lb 

Super Sacks

0.5-1.0 6.68 90 <0.5 0.01 $1.65 (55 lb 

Bags), $1.55 

(1,650 lb 

Super Sacks)

Emulsion 

Polymer

275 gal 

Tote

2.5-3.5 8.59 30 N.A. 0.05 $1.17

Pre-Diluted 

Polymer

275 gal 

Tote

0.5-1.0 8.34 90 0.08 N.A. $0.24

Table 1: Specifications for three most common polymer products used in mine drainage treatment.

Ferrous Iron is the primary multi-valent contaminate in flooded underground coal mines in the eastern 

U.S., although some underground mines also require manganese and aluminum treatment. An operator 

can consider using polymer to maximize the settling of any precipitated solids within a mine drainage 

treatment system. For net acidic mine drainage, following the addition of alkalinity and aeration 

(oxygen), the goal is to oxidize the ferrous iron (Fe2+), dissolved aluminum (Al3+) and dissolved 

manganese (Mn2+) forming solid precipitates of each. Historically, operators have used lime or caustic 

soda addition in active treatment systems and limestone in passive systems to increase pH in order to

precipitate metals. This is then followed by the addition of polymer prior to or within the settling pond or 

clarifier to promote settling of the solids, forming a sludge layer that is ultimately removed for disposal. 

The polymer is effective at removing the solids from the mine drainage within the settling unit to achieve 

effluent standards (Figure 1). However, if the mine drainage source is net alkaline, the role of polymer 

remains the same in that it aides in removing the solids following aeration, forming a sludge layer within 

the settling pond or clarifier.

2.2 Benefits/Drawbacks, Equipment and Typical Treatment 

Configurations

This section summarizes some of the benefits, drawbacks, equipment, and treatment configurations of the 

polymer systems used at mine drainage treatment sites. 
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2.2.1 Benefits: The major reason why polymer is popular is its ability to promote the formation 

of floc from individual metal precipitates, enhancing the settleability of the particles and creating 

an effluent with low suspended solids. The benefits of using polymer as a component of a mine 

drainage treatment system include:

1. Quick reacting allows for precise dosage and reduced size of the settling pond/clarifier.

2. Can be effectively mixed with mine drainage using passive mixing, like turbulent flow, 

provided that solution density differences between the dilute polymer and the treated mine 

water are minimal.

3. Works very well at promoting flocculation of target mine drainage constituents, improving 

their settleability and removal from the water within a settling pond/clarifier prior to 

discharge.

4. Maximizes sludge production by generating larger, more dense sludge particles, and may 

enhance the dewatering of sludge upon removal for disposal.

5. Depending on the type of polymer selected, the lower the capital costs the higher the annual 

costs and vice versa (higher capital costs may have lower annual costs).

6. Minimal maintenance, with the dose pump and electric mixer being the only mechanical 

parts.

7. Relatively small equipment footprint (automatic Dry Polymer systems that utilize 1,650 lb 

Super Sacks have the largest footprint of polymer types, whereas Dry Polymer systems using 

55 lb Bags have a comparable footprint to most Emulsion Polymer systems).

8. Relatively stable chemical (Dry Polymer) allows for long-term storage in instances of 

ephemeral or periodic treatment.

9. The use of Pre-Diluted Polymer is possible at remote sites where electricity is not available, 

which is common for many mine drainage treatment systems.

10. Depending upon preference, systems can be highly automated or very basic (manual) in 

design philosophy.

2.2.2 Drawbacks: The drawbacks of using polymer as a mine drainage treatment chemical 

include:

1. Annual cost, polymer is a relatively expensive chemical and depending on the needs of the 

system it can be a considerable cost component of the annual costs. Pre-Diluted Polymer is 

the most expensive polymer product used in mine drainage treatment on a cost per active 

ingredient basis since you are purchasing primarily water, therefore this type of polymer 

should be reserved for remote sites where electricity is not available and it is the only option

when polymer is needed.

2. The polymer system and product should be stored within a temperature-controlled building or 

structure in order to prevent freezing and inconsistency issues with the product, especially 

during the cold weather months.

3. The capital costs and footprint associated with the equipment options for Dry Polymer can be 

significant compared to other polymer types, especially for an automatic system for use in 

mine drainage treatment.

4. Emulsion Polymer systems tend to require more frequent maintenance than Dry Polymer

systems. Typically, several hours per week of downtime maintenance is needed to clean 

injection ports, nozzles and lines associated with the emulsion pump mechanism. 
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2.2.3 Equipment and Typical Treatment Configurations:

2.2.3.1 Dry Polymer - The module assumes the Dry Polymer will be delivered in either 

55 lb bags or 1,650 lb Super Sacks (bulk). The Dry Polymer, which is most common in a 

granular form but may be delivered as a powder depending on the manufacturer, must be 

made down (diluted) at the treatment site using either a manual or automatic make down 

system. The two types of Dry Polymer systems that the user must choose between in the 

Polymer module are assumed to have standard components for each. 

Manual System

For a manual Dry Polymer system, the make down equipment is composed of an extralarge HDPE (XLHDPE) day tank with a low revolutions per minute (RPM) mixer. The 

XLHDPE day tank size can be estimated by the software, based on calculating the 

volume of diluted polymer solution required to achieve the user-defined target polymer 

dose for a 24-hour period (why it’s called a day tank) and provide an additional 20% 

volume as a safety factor for the tank size. Alternatively, the user can specify a Custom

cost for a known day tank size and mixer. This manual make down system assumes the 

operator will add water to the XLHDPE day tank and manually add the Dry Polymer, 

preferably into a Hootonanny Eductor (see Figure 4) for pre-wetting, into a vortex created

by a low RPM (less than 400 RPM) mixer and mixed for approximately 30 minutes to 

fully dissolve the Dry Polymer. The made down polymer in the day tank is then 

processed through a separate pump and mixing equipment system, which consists of two 

diaphragm pumps (one primary and one back-up) that pump the made down polymer 

from the day tank to two inline static mixers where the diluted polymer solution is mixed 

with either additional dilution water (push water) or with the mine drainage. The user 

can select to allow the module to Estimate the cost of the diaphragm pumps and inline 

static mixers using the default unit cost or to provide a known Custom cost for this 

portion of the manual polymer system. Either component of the manual Dry Polymer

system can be excluded by the user as deemed appropriate for the specific application.

Automatic System

For an automatic dry polymer system, the make down equipment is composed of a 

stainless-steel (or fiberglass) blending/aging tank, piping, and a hopper that continuously 

makes a diluted polymer solution. The hopper gravity feeds Dry Polymer into a prewetting chamber where the Dry Polymer is mixed with water with high shear agitation to 

pre-wet polymer granules to prevent unwanted agglomeration, referred to as ‘fish-eyes’, 

and ensure proper activation of the active polymer ingredient. Note that if the 1,650 lb 

Super Sacks are the selected delivery method (bulk) for Dry Polymer in the module, an 

option is automatically included in the equipment section for a bulk bag (Super Sack) 

feeder option. However, the user can choose to deselect this option in the Automatic Dry 

Polymer Equipment section by unchecking the corresponding box. Following the prewetted chamber, the polymer and water are conveyed into a second stage mix tank where 

the polymer and water are mixed in a low shear environment to produce the desired 

polymer solution strength set by the operator on a computer control screen for the system

(Desired Solution Strength of Made Down Polymer). Following this mix tank, the diluted 

(made down) polymer is conveyed to a holding tank. As the product is pumped from the 

made down polymer solution holding tank, a low-level sensor in the tank automatically 

initiates the production of another batch of polymer solution from the hopper. The 
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default selected dosing pump and mixing skid is responsible for pumping the made down 

polymer solution from the holding tank and mechanically mixing it with push water 

(clean water source) for further dilution to achieve a constant solution strength 

electronically set by the operator on the skid using the computerized controls or remotely 

from a 4-20 milliamp (mA) signal. The dosing pump and mixing skid unit automatically 

adjusts the flow of the push water and made down polymer solution from the holding 

tank to prevent disruptions. The dosing pump and mixing skid consists of two high 

quality diaphragm pumps, one primary and one back-up, and a mixing unit which are all 

mounted on a stainless-steel skid frame geared with computerized controls for the 

equipment. The user can select to allow the module to Estimate the cost of the pump and 

mixing skid, an optional item, or the user can choose to deselect it by unchecking the 

corresponding box, using the default unit cost, or provide a known Custom cost for this 

portion of the automatic Dry Polymer system.

2.2.3.2 Emulsion Polymer System - An Emulsion Polymer system is much less 

complicated and requires less equipment than what is typically required for Dry Polymer. 

The default equipment provided in the module for Emulsion Polymer consists of a 

computerized pump and blending unit mounted on a stainless-steel skid frame. The 

operator sets the desired solution strength for the polymer in the dilution (push) water on 

the computer control panel, which controls the progressive cavity pumps (2) that pump 

the Emulsion Polymer from the tote to the mixing unit. In the mixing unit, dilution 

(push) water is pumped to mix with the Emulsion Polymer to achieve the desired solution 

strength and additional mechanical mixing is provided to promote inversion and 

unwinding of the polymer chain in order to react with the mine drainage. A default unit 

cost is provided that can be adjusted by the user or a Custom cost for the Blending Skid 

w/ Progressive Cavity Pump and Computerized Controls unit can be specified.

2.2.3.3 Pre-Diluted Polymer System - The Pre-Diluted Polymer system is also less 

complicated and requires less equipment than what is typically required for Dry Polymer. 

The default equipment provided in the module for Pre-Diluted Polymer consists of two 

Diaphragm Dosing Pumps (one primary and one back-up) and two Inline Stainless-Steel 

(SS) Static Mixers with Removable Mixing Fins. Pre-Diluted Polymer is pumped using a 

diaphragm pump from the totes in which it is delivered to the site to two static inline 

mixers to blend the Pre-Diluted Polymer with the mine drainage. The static inline mixers 

are only used in situations where the mine drainage source is being pumped in order to 

provide the pressure needed for the mixers to blend the Pre-Diluted Polymer and water. 

If the mine drainage is gravity fed through the system, common at many surface mine 

sites, the user can deselect the line static mixers since the Pre-Diluted Polymer would 

simply be pumped directly into the mine drainage. The operator can also further dilute 

the Pre-Diluted Polymer solution by pumping it from the storage totes into the static 

inline mixers for mixing with push water prior to adding to the mine drainage. Default 

quantity and unit costs are provided for the Diaphragm Dosing Pump and Inline SS Static 

Mixer with Removable Mixing Fins that can be adjusted by the user, or a Custom cost can 

be entered for all of the equipment as one lump sum amount.
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2.3 Application and Financial Analysis

Polymer is typically used as a flocculant to improve settling of iron, aluminum and manganese

precipitates in mine drainage. It is used to cause suspended particles of metal precipitates to combine,

forming larger particles that are more readily settled. To achieve this the diluted polymer solution is

added to the mine drainage as it is conveyed to the settling unit, most commonly a clarifier or less often a 

settling pond. The most common solid precipitates in mine drainage are Fe(OH)3, Al(OH)3, and MnO2. 

The selected polymer product can be based on the preference of the design engineer or the operator or as 

determined by a cost analysis for the capital and annual costs of the three anionic polymer options. 

Polymer is typically selected for use at a mine drainage treatment site based on:

1. The need for rapid settling of suspended metal precipitates within the settling unit (e.g., clarifier). 

2. Fast reaction time.

3.0 Polymer Module Overview

3.1 Layout and Workflow

In general, inputs are on the left-hand side of the module and calculated outputs are on the right. The 

module inputs on the left-hand side are arranged into six sections: (1) Water Quality and Flow Input, (2) 

Anionic Polymer Flocculant Information, (3) Equipment and System Installation, (4) Annual Cost Input,

(5) Other Capital Items, and (6) Other Annual Items. The workflow for the module is for users to start at 

the top left-hand side. Enter the Typical Flow (gpm) and Density of Water in lbs/gal. Under the Anionic 

Polymer Flocculant Information enter the Target Polymer Dose (ppm) followed by selecting the specific 

polymer product (Dry Polymer, Emulsion Polymer, or Pre-Diluted Polymer). If Dry Polymer is selected, 

the user must select either 55 lb Bags (non-bulk) or 1,650 lb Super Sacks (bulk), followed by accepting 

the default values or specifying the Density of Dry Polymer, Activity of Dry Polymer, Desired Solution 

Strength of Made Down Polymer, and Desired Strength of Made Down Polymer in Dilution (Push) Water. 

If Emulsion Polymer is selected, the user can accept the default values or specify the Density of Emulsion 

Polymer, Activity of Emulsion Polymer, and Desired Strength of Emulsion Polymer in Dilution (Push) 

Polymer. Finally, if Pre-Diluted Polymer is selected, the user can accept the default values or specify the 

Density of Pre-Diluted Polymer, Activity of Polymer, and Solution Strength of Pre-Diluted Polymer. 

AMDTreat uses this information along with the typical flow to estimate the polymer consumption, based 

on the specified operational times.

Next, users can accept default values or provide custom costs in the Equipment and System Installation 

section for the polymer treatment equipment. Based on the selected polymer product in the Anionic 

Polymer Flocculant Information section, the applicable product equipment is shown in the Equipment and 

System Installation section. If Dry Polymer is selected, the user must select either Manual or Automatic 

Dry Polymer Equipment. If Manual Dry Polymer Equipment is selected, the items XLHDPE Day Tank & 

Low RPM Mixer (Make Down Equipment) and Two Diaphragm Pumps, Feeder Tube, & Two Inline SS 

Static Mixers are included. For each of these two items the user can select to exclude either item, have 

the software estimate the sizing and cost for each (default) or the user can enter a Custom cost for each 

item if that information is already known for an existing system. If Automatic Dry Polymer Equipment is 

selected, the items Automatic Dry Polymer Make Down Unit (Stainless steel blending/aging tank, piping, 

hopper) and Polymer Dosing and Diaphragm Pump Skid with Computerized Controls are included. If the 

user selected 1,650 lb Super Sacks (bulk) for the Dry Polymer, an additional item, Bulk Bag/Super Sack 
11 

Feeder Option is automatically included with the Automatic Dry Polymer Equipment items. For each of 

these two or three items the user can select to exclude any of the items, have the software estimate the 

sizing (excludes Bulk Bag/Super Sack Feeder Option) and cost for each (default) or the user can enter a 

Custom cost for each item if that information is already known for an existing system. If Emulsion 

Polymer is selected, the default item includes a Blending Skid with Progressive Cavity Pump and 

Computerized Controls. For this item the user can select to exclude it in addition to have the software 

estimate the cost (default) or the user can enter a Custom cost for the item if that information is already 

known for an existing system. If Pre-Diluted Polymer is selected, the default items include Diaphragm 

Dosing Pump and Inline SS Static Mixers with Removable Mixing Fins. For these items the user can select 

to exclude it in addition to have the software estimate the cost (default) based on the desired quantity and 

unit cost or the user can enter a Custom cost for the item if that information is already known for an 

existing system.

The Annual Cost Input section allows the user to specify the polymer and water (dilution/push) unit costs, 

operational periods, and electrical unit cost to ensure polymer and water consumption and electrical costs 

are correctly estimated. Based on the user selected polymer product, the default unit cost is activated for 

the applicable polymer product, which can be adjusted by the user. Finally, users can specify additional 

capital and annual costs not considered by the module under the Other Capital Items and Other Annual 

Items headings. 

Module output is provided on the right-hand side of the module. Module outputs on the right-hand side 

are arranged into four sections: (1) Sizing Summary, (2) Capital Cost, (3) Annual Cost, and (4) Net 

Present Value (NPV). The Sizing Summary section provides estimates based on the selected polymer 

product such as the dose corrected for percent activity, polymer consumption at different rates based on 

user-specified operational times, push/dilution water volumes, tank sizes where applicable, pump rates, 

and product refill frequency. The estimated cost to construct and operate the polymer component of a

treatment system is provided under the Capital Cost and Annual Cost headings. Lastly, users can opt to

conduct a NPV analysis to obtain the total cost to operate and maintain the polymer system for a defined 

time period. 

A general overview of the module input and output sections is presented below, however, users are 

directed to the numerous tool tips located in the module that provide additional detailed information, such 

as definitions of terminology. In most cases, the tool tips are accessed by clicking on the information icon 

( ) in each of the subheadings in the module. 

3.2 Module Inputs

3.2.1 Water Quality and Flow Input: The Water Quality and Flow Input section is where users 

specify the Typical Flow and Density of Water values. These values are used to (1) estimate the 

polymer consumption and (2) estimate the size of various equipment items such as the day tank for 

Dry Polymer. 

The definitions for Typical Flow and Density of Water can be found in the tool tip for this section. 

Click on the information icon ( ) on the right side of the Water Quality and Flow subheading. In 

short, Typical Flow is the flow rate “typically” experienced at the site. This flow rate is used to 

calculate the polymer consumption, so one must take careful consideration to calculate this value. 
12

Density of Water represents the density of water to be treated with polymer as specified by the user 

for use in calculating polymer consumption rates. 

3.2.2 Anionic Polymer Flocculant Information: After specifying the Target Polymer Dose, users 

can select from three different polymer products including Dry Polymer, Emulsion Polymer, or PreDiluted Polymer. After selecting the polymer product, the user can adjust specific input parameters 

based on the polymer product selected. For Dry Polymer, the user must first select the preferred 

delivery product either 55 lb Bags or 1,650 lb Super Sacks. The remaining items in this section can 

be adjusted or the user can accept the default values, these items are Density of Dry Polymer, Activity 

of Dry Polymer, Desired Solution Strength of Made Down Polymer, and Desired Strength of Made 

Polymer in the Dilution (Push) Water. Emulsion and Pre-Diluted Polymer are typically only 

available in 275-gallon totes delivered to the site, so no options are provided for delivery method. 

The items in the Emulsion Polymer section can be adjusted or the user can accept the default value for 

Density of Emulsion Polymer, Activity of Emulsion Polymer, and Desired Strength of Emulsion 

Polymer in the Dilution (Push) Water. Pre-Diluted Polymer has very similar items to Emulsion 

Polymer that can be adjusted in this section, which include Density of Pre-Diluted Polymer, Activity 

of Polymer, and Solution Strength of Pre-Diluted Polymer. It is assumed 100% of the dosed polymer

reacts in the mine drainage; therefore, mixing efficiency is not a parameter that is considered in this 

module. 

3.2.3 Equipment and System Installation: This section allows users to design and select a polymer 

system setup. Polymer systems are straightforward, after the user decides which polymer product to 

utilize, they can decide which equipment items to include as part of the design. The software provides 

the common components for each polymer type by default including unit costs. The system will 

estimate the equipment and associated costs, unless the user has specific cost information for an 

existing system. The following subsections discuss these items: 

3.2.3.1 Dry Polymer Equipment - The module assumes that if the user selects Dry Polymer that 

the solid polymer will be mixed onsite; therefore, the Dry Polymer equipment items are only 

available when the user selects Dry Polymer. Users have two options to choose from when 

selecting Dry Polymer, either Manual or Automatic Dry Polymer Equipment.

Manual Dry Polymer Equipment

Since Manual Dry Polymer Equipment is selected by default, we will review the calculations for 

it first. The volume of the XLHDPE day tank is estimated by determining the required daily 

pump rate volume (gal/day) of made down polymer at the user specified made down solution 

strength multiplied by a conservative surplus volume factor of 1.2, using Equation (1).

Where: 

Daily PumpVolDP = Daily pump rate volume of made down dry polymer in gal/day of specified 

% solution strength.

XLHDPE Day Tank Volume = Calculated volume of XLHDPE day tank for made down dry 

polymer solution. 
13

The user can edit the XLHDPE Day Tank & Low RPM Mixer unit cost of $8.50 per gallon (day 

tank volume) accordingly in order to get an accurate capital cost for these items. The default unit 

cost of $6,500 for the Two Diaphragm Pumps, Feeder Tube & Two Inline Stainless-Steel Mixers

is provided, and the user can adjust this unit cost or provide a custom cost for this equipment if 

known. Two diaphragm pumps are recommended in order to have a primary and back up pump 

on-site.

Automatic Dry Polymer Equipment

If the user selects Automatic Dry Polymer Equipment, the first item is the make down unit that 

includes a stainless-steel blending/aging tank, piping, and a hopper. The volume of the 

blending/aging tank is estimated using the same equation as shown above (Equation 1) for the 

XLHDPE day tank volume. A low-level sensor is provided in the blending/aging tank that 

automatically initiates the production of another batch of made down polymer. The user can edit 

the Automatic Dry Polymer Make Down Unit default unit cost accordingly in order to get an 

accurate capital cost for these items. Default unit costs are also provided for the other two items 

included for an Automatic Dry Polymer System, including a Polymer Dosing and Diaphragm 

Pump Skid with Computerized Controls. If the user selects 1,650 lb Super Sacks for Dry Polymer

(Anionic Polymer Flocculant Information section) a Bulk Bag/Super Sack Feeder Option is 

included by default to hold and dispense the Dry Polymer from the super sacks. If the user 

selects 55 lb Bags for the Dry Polymer then the Bulk Bag/Super Sack Feeder Option is not 

provided in the Automatic Dry Polymer Equipment section. The Polymer Dosing and Diaphragm 

Pump Skid with Computerized Controls is used to control and regulate the pumping of the made 

down and diluted polymer from the stainless-steel blending/aging tank and mechanically mix it 

with dilution/push water to generate a constant solution strength electronically set by the operator 

on the skid or remotely from a 4-20 mA signal. This diluted polymer solution is then applied to 

the mine drainage source. The user can select if they prefer not to include any of these items 

using the check boxes for each and adjust the unit costs or provide a Custom cost for this 

equipment if known.

3.2.3.2 Emulsion Polymer Equipment - If the user selects Emulsion Polymer, the Emulsion

Polymer Equipment includes a Blending Skid with Progressive Cavity Pump and Computerized 

Controls with a default cost of $25,000 for the entire skid unit. The user can select if they prefer 

not to include this item using the check box and adjust the unit costs or provide a Custom cost for 

this equipment if known. The operator specifies the desired solution strength on the computer 

control panel of the skid for the progressive cavity pumps to pump the Emulsion Polymer from 

the 275-gallon tote from which it is delivered to the mixing unit where it is mixed with 

dilution/push water to create the desired solution strength for addition to the mine drainage.

3.2.3.3 Pre-Diluted Polymer Dosing Equipment - If the user selects Pre-Diluted Polymer, the 

Pre-Diluted Polymer Dosing Equipment allows the user to select the Estimate option using 

default equipment including Diaphragm Dosing Pumps and Inline Stainless-Steel Static Mixers 

with Removable Mixing Fins or select the Custom option where the cost for the equipment, if 

known, can be specified such as for an existing polymer system. The default values for the 

Diaphragm Dosing Pumps include a quantity of two (2) and a unit cost of $1,700 per pump. The 

default values for the Inline Stainless-Steel Static Mixers with Removable Mixing Fins include a 

quantity of two (2) and a unit cost of $1,300 per mixer. All default quantities and unit costs can 
14

be adjusted by the user as needed. The basic premise of the default equipment for Pre-Diluted 

Polymer is to use a diaphragm pump, one primary and one back-up, to pump the Pre-Diluted 

Polymer from the 275-gallon tote to two static inline mixers to mix with the mine drainage stream 

if the water is also pumped such as from an underground mine. However, if the Pre-Diluted 

Polymer is simply pumped into a gravity fed mine discharge such as what is common for many 

surface mine sites, the user can deselect the inline stainless-steel static mixers since they are not 

applicable and not include the cost.

3.2.4 Annual Cost Input: This section allows users to specify critical items needed to calculate 

many of the items contained in the Sizing Summary including the amounts of polymer needed, 

volume of dilution/push water needed if applicable, in addition to the annual cost of several items 

including polymer, water, and electric. The specific items included in this section that may be 

applicable to all of the polymer types include the following: Polymer System Operational Time, Unit 

Cost of Water, Polymer Pump Power, Electrical Unit Cost, and Delivered Unit Price of Selected 

Polymer Product.

3.2.4.1 Polymer System Operational Time - The operational time directly affects the estimates of 

polymer consumption that are provided in the Sizing Summary of the module. The operational 

time also affects the refill frequency of tanks and hoppers, the consumption of dilution or push 

water, and the electrical costs of operating pumps and other equipment associated with polymer 

systems. The default values for the operational times, 24 hours per day and 365 days per year, 

assume the polymer system will be operated continuously. However, there are situations where 

mine drainage treatment systems that pump and treat underground mine pools to maintain the 

mine pool storage can be periodically operated rather than continuously. These two input items 

allow the user to specify their unique operational time to more accurately estimate polymer, water 

consumption and electrical costs.

3.2.4.2 Unit Cost of Water - The Unit Cost of Water is applicable if the site requires the purchase 

of water from a public water supply in order to use the water for the make down process and for 

any further dilution and/or as push water to transport the polymer to the application point. It is 

important to make sure that all taxes, distribution costs, and other fees are included when 

calculating the Unit Cost of Water ($/1,000 gallons) to the site for accurately estimating the 

annual water cost. The best way to estimate the Unit Cost of Water is to review a water bill for 

the site and divide the bill amount by the total gallons of water used for the billing period and 

multiply that value by 1,000. As an example, if the water bill for a 30-day period is $60 and 

approximately 7,000 gallons of water was consumed at the site, then the unit cost of water would 

be calculated as follows:

3.2.4.3 Polymer Pump Power - The Polymer Pump Power is the power consumption associated 

with the applicable pump(s) used for the specific type of polymer system selected. The default 

value of 130 watts is common for most polymer pumps used in mine drainage but the user can 

specify a value for the pump to be used if known.
15

3.2.4.4 Electrical Unit Cost - The unit cost of electricity is the applicable rate charged to provide 

electricity to the site. The value used for polymer should be the same value used for any other 

module where electric is required to operate that component. Make sure all taxes, distribution 

costs, and other fees are included when determining the Electrical Unit Cost in order to 

accurately predict the annual electrical costs. Similar to the Unit Cost of Water, the Electrical 

Unit Cost can be calculated by reviewing an electric bill for the site and dividing the total bill 

amount by the total kWhs used for the billing period that results in a $/kWh value. The Electrical 

Unit Cost is then multiplied by the power consumed by the polymer equipment and operational 

time to estimate the annual cost of electric for the polymer system.

3.2.4.5 Delivered Unit Price of Selected Polymer Product - The delivered unit cost for each type 

of polymer including default values are provided in order to estimate the annual cost of polymer 

consumption. Whichever polymer type the user selects in the Anionic Polymer Flocculant 

Information section is automatically activated in this section including which type of Dry 

Polymer delivery container is selected, 55 lb Bags or 1,650 lb Super Sacks, since the unit cost is 

different due to the bulk discount for the Super Sacks. When attempting to obtain a quote for unit 

cost of a polymer from a supplier make sure the unit cost includes both the purchase and delivery 

costs, which is the value that should be used for the Delivered Unit Price of Selected Polymer

Product.

3.2.5 Other Capital Items: The Other Capital Items section allows users to capture the capital cost 

of equipment and other items that are not included in this module. For example, a small number of 

polymer systems have electronic weight scales to help monitor the amount of raw polymer product 

available in the delivered container. Since this is relatively uncommon it was not included in the 

module, however, users who want to include this capability can input the cost into the Other Capital 

Items section to capture the capital cost for such a system component. 

3.2.6 Other Annual Items: The Other Annual Items section allows users to capture the annual cost 

of equipment and other items that are not included in this module. For example, users could include 

the annual subscription cost to remotely control the Polymer Dosing and Diaphragm Pump Skid with 

Computerized Controls in order to make adjustments as needed to the mixture of diluted polymer 

solution and push water in the Other Annual Items section. 

3.3 Module Outputs

3.3.1 Sizing Summary: The Sizing Summary section displays important calculated module outputs

and is specific to the type of polymer the user selects, which is denoted in the Sizing Summary title 

block on the right-hand side. For Dry Polymer the Sizing Summary includes estimated polymer dose 

corrected for percent activity, polymer flocculant and made down and dilution (push) water 

consumption per the operational time, refill frequency and annual quantities of delivered containers, 

made down polymer pump rates, and day tank capacity. For Emulsion Polymer, the Sizing Summary

includes estimated polymer dose corrected for percent activity, polymer flocculant and dilution (push) 

water consumption per the operational time, and refill frequency and annual quantities of delivered 

containers. For Pre-Diluted Polymer, the Sizing Summary includes estimated polymer dose corrected 

for percent activity, polymer flocculant and pre-diluted polymer solution consumption per the 

operational time, and refill frequency and annual quantities of delivered containers. The refill 
16

frequency provides users with an estimate of how often the polymer product delivered container (e.g., 

1,650 lb Super Sack) will need refilled based on the estimated polymer consumption. 

3.3.2 Capital Cost: This section provides the estimated costs for the various user-specified 

components and the total estimated cost to construct the polymer system. Based on the selected 

polymer type, the Capital Cost may include make down system (Dry Polymer), made down polymer 

dosing and mixing equipment, Emulsion Polymer blending and pump skid, Pre-Diluted Polymer

equipment, and other capital items specified by the user in the Other Capital Items section. Users can 

opt to estimate the installation cost by specifying it as a percentage (cost-multiplier) of the Capital 

Cost or by entering a User-Specified cost. 

3.3.3 Annual Cost: The Annual Cost section provides an estimate of the cost to operate and 

maintain the polymer component of the mine drainage treatment system. Users can select to have 

AMDTreat estimate the annual chemical (polymer) cost or specify an annual polymer cost. 

Specifying an annual chemical cost is often used when AMDTreat’s NPV calculations are being used 

to estimate water treatment liability. The annual operation and maintenance for the polymer 

components can either be specified by the user or estimated by assuming it is a percentage of the 

polymer system Capital Cost. The latter method assumes that more expensive systems are more costly 

to maintain. The Electric cost for the polymer system can either be estimated using the software based 

on polymer pump power and Electrical Unit Cost or specified by the user. The estimated annual cost 

of water for the polymer system is important to consider especially if the source is a public water 

supply where consumption charges are based on a Unit Cost of Water ($/1,000 gallons), which is a 

user-specified variable. The user can choose to allow the software to estimate the Estimated Water 

Cost broken down by make down water and push water or the user can specify a known annual cost 

of water. Any other Annual Cost specified by the user in the Other Annual Items section would also 

be included.

3.3.4 Net Present Value: The NPV section determines the cost to operate a treatment system 

component over a specified time period. The NPV calculates the present-day financial investment 

required to generate the income to pay for future operation and equipment/materials replacement 

costs. Both Financial Variables and Cost Categories are required to calculate the NPV. 

3.3.4.1 Financial Variables - The Term of Analysis, Inflation Rate, and Rate of Return are three 

variables used in the NPV calculations. The default values for these terms are shown under the 

Net Present Value section of each module. Users must access the Net Present Value menu at the 

top of the main user interface to change the default values as they would apply to all modules 

used for an entire mine drainage treatment system. While NPV is determined for each AMDTreat 

module activated by the user, the goal is to determine a total NPV for an entire mine drainage 

treatment system project (a collection of cost estimates for individual modules creates a treatment 

system project in AMDTreat). Therefore, a single value for Term of Analysis, Rate of Return, and 

Inflation Rate is applied to all modules and cannot vary between modules.

• Term of Analysis: The time period used by the NPV calculation to determine the 

financial investment required to pay for all future costs of the treatment system. 

• Inflation Rate: Represents the average price increase of goods and services over 

time. AMDTreat uses the inflation rate to calculate the future cost of the annual 

operation and maintenance (O&M) and recapitalization items. 
17

• Rate of Return: Describes the expected profit on an investment. 

3.3.4.2 Cost Categories - For each treatment module, AMDTreat provides a list of recommended 

equipment and materials that require recapitalization. In addition, AMDTreat provides 

recommendations (default values) for Life Cycle and Replacement Percentage. Users can click 

on the default values for Life Cycle or Replacement Percentage and use the +/- buttons to change 

the default values. In addition, users can select Custom Cost and enter a new cost to represent the 

current cost of the equipment. Users can add new recapitalization items or deactivate/delete 

existing items for calculating the NPV. 

An example of how the recapitalization variables are used to determine NPV is to 

consider the following hypothetical scenario. Assume a vertical turbine pump has a Life

Cycle of 50 years but requires the pump motor to be rebuilt every 20 years. Assume the 

present-day cost to purchase the motor is $500,000, and the cost to remove, rebuild, and 

reinstall the pump motor is $20,000. Now assume we want to determine the amount of 

investment required today (NPV) to generate the income to pay for the future cost of 

rebuilding the pump motor over a 50-year Term of Analysis, which is also equal to the 

Life Cycle of the pump. Assume an Inflation Rate of 5.0% and Rate of Return of 8.1%. 

The goal is to place the money in a relatively secure investment vehicle to generate 8.1% 

annually. The NPV will calculate the size of investment required to generate income for 

future costs. 

There are several ways to model the replacement cost. One way is to replace 4% of the 

present-day cost of the pump (4% of $500,000 = $20,000) with a Life Cycle of every 20

years. If the Term of Analysis is 50 years, then the entire pump would not require 

recapitalization since the Life Cycle of the pump is 50 years. However, the motor would 

require two replacements (50 years / 20 years = 2.5 rounded down to 2). 

To determine the NPV to recapitalize rebuilding of the motor, AMDTreat calculates the

future cost to rebuild the motor at each Life Cycle, 20 and 40 years. The program uses the 

Inflation Rate to inflate the present-day default cost to rebuild the motor in 20 and 40 

years from now. While the present-day cost to rebuild the pump motor is $20,000, the 

future cost to rebuild the motor in 20 years at a 5.0% Inflation Rate is $53,065 and 

$140,799 in 40 years (Equation 2). Assuming an 8.1% Rate of Return, the 50-year NPV

for the pump is $17,422. In other words, an initial investment of $17,422 is needed at an 

annual Rate of Return of 8.1% to generate the investment income required for the two 

motor rebuilds over the 50-year Life Cycle of the pump. 

• Annual Operation and Maintenance Cost: By default, AMDTreat transcribes the annual 

O&M cost from the Annual Cost section to the Net Present Value section. The program 

assumes the module is being used to estimate the Annual Cost for a treatment system 

component, so it automatically transcribes the Annual Cost to the NPV section. If this is 

not the case or the user wants to use some other Annual Cost, the Use Custom box can be 
18

selected to allow the user input of a different Annual Cost to utilize in the NPV 

calculation. 

• Recapitalization Cost: Certain treatment system components, especially mechanical and 

water conveyance equipment, require periodic replacement. The recapitalization cost of 

an item is an estimate of the amount of money required to pay for future replacement 

costs for the item. In addition to the Financial Variables described above, three additional 

values are required to calculate the NPV of recapitalization costs, the Present-Day 

Equipment Cost, the Life Cycle, and the Replacement Percentage.

• Default Cost: This represents the current cost to purchase the equipment or material.

• Life Cycle: The time frame between equipment or material replacement is termed as its 

Life Cycle. Some equipment manufacturers provide recommended Life Cycles for their 

equipment to provide consumers with an estimate of how long the equipment is expected 

to be operational. Some Life Cycles, such as those used for treatment media (limestone), 

are based on best professional judgement. Some operators prefer to periodically purchase 

and replace equipment before failure to preserve the continuity of operations, while 

others wait until failure to replace an item.

• Replacement Percentage: The Replacement Percentage is an adjustment factor to the 

default cost to accommodate situations where the entire piece of equipment or all the 

material does not require recapitalization. For example, a passive treatment component 

may be designed to contain enough limestone to neutralize the acidity load for 20 years, 

however, the accumulation of metal hydroxide precipitates within the void space of the 

limestone layer may require that 25% of the limestone be replaced every seven years to 

prevent hydraulic failure such as plugging or short-circuiting. For this scenario, the 

initial cost of the limestone making up the limestone layer is discounted by 75% and 

assigned a Life Cycle of seven years to determine the amount of money required to cover 

the cost of replacing 25% of the limestone layer every seven years over the Term of 

Analysis. 

3.3.4.3 Rationale for Recapitalization Recommendations - Recapitalization recommendations are 

based on professional experience of the AMDTreat Team and may not apply to all situations. 

Users are encouraged to customize the recapitalization assumptions to their treatment scenario. 

AMDTreat Team members are located in Pennsylvania and West Virginia and have collective 

experience in design, funding, and/or operation/maintenance for over 100 passive and active 

treatment systems. Users may have different experience and opinions than those listed. 

By default, AMDTreat includes a list of between three and five recapitalization items based on 

the polymer type selected in the Polymer module. However, the items the user selects to include 

in the module will also determine which items are included in the NPV section. Users can delete 

or modify any of the default recapitalization items by either deselecting the item or by setting the 

Replacement Percentage to zero. If the item is deselected, the Total Cost for the item will still be 

shown but the cost will be subtracted from the NPV, shown in the NPV heading. For example, the 

default value for the Life Cycle of a Diaphragm Pump (Dry Polymer) is seven years due to basic 
19

wear and tear. However, users may opt to increase the Life Cycle if the pump will be used 

intermittently as determined by the user specified operational time. Users are free to fully 

customize the replacement items, including adding new items or deleting default items. 

Dry Polymer:

Manual Dry Polymer Make Down System: The manual Dry Polymer make down 

system default Life Cycle is 20 years with 100% replacement. This will depend on the 

day tank type and material (HDPE). The user can adjust these values accordingly. 

Polymer Low RPM Mixer Motor Rebuild: The low RPM electric mix motor 

component of the manual Dry Polymer make down system requires being rebuilt with a 

default Life Cycle of seven years. The Life Cycle may be adjusted based on the quality of 

the motor. 

Diaphragm Pumps: As part of the Manual Dry Polymer Equipment, the diaphragm 

pumps that convey the made down polymer from the day tank to mix with the dilution 

push water have a Life Cycle of seven years before the equipment requires replacement.

The Life Cycle may be adjusted based on the quality and usage of the pumps.

Automatic Dry Polymer Make Down System: The automatic Dry Polymer make down 

system default Life Cycle is 30 years with 100% replacement. This will depend on the 

day tank type and material (SS). The user can adjust these values accordingly. 

Polymer Dosing and Pump Skid: The default Life Cycle is 30 years for the polymer 

dosing and diaphragm pump skid unit with computerized controls at 100% replacement. 

The user can adjust these values accordingly.

Emulsion Polymer:

Emulsion Polymer Blending Unit: The default Life Cycle is 30 years for the Blending 

Skid with Progressive Cavity Pump and Computerized Controls at 100% replacement.

The user can adjust these values accordingly.

Pre-Diluted Polymer:

Diaphragm Dosing Pump: The default Life Cycle for the Diaphragm Dosing Pumps that 

convey the Pre-Diluted Polymer from the tote to the application point is seven years at 

100% replacement. The user can adjust these values accordingly.

Inline Stainless-Steel Static Mixers with Removable Fins: The default Life Cycle for 

the Inline SS Static Mixers with Removable Fins is 25 years at 100% replacement. The 

user can adjust these values accordingly.

3.4 Assumptions of Design Sizing and Costs

AMDTreat is a cost estimation model that uses assumptions to provide treatment sizing and both capital 

and annual cost estimates. While there are many assumptions in the program, the assumptions that follow 

are important for the Polymer module. 
20

1. Polymer functions by allowing charged suspended particles to floc together, bonding to 

the oppositely charged polymer surface, forming larger particles that will settle out of the 

water. There are many different types and manufacturers of polymer flocculant products. 

Consequently, it is important to conduct the appropriate jar tests or bench scale testing 

using the water to be treated with any perspective polymer product to confirm the 

effectiveness at settling the precipitated solids, desired solution strength of polymer, and 

the dosage that works the best. The AMDTreat development team has designed the 

polymer module with a primary focus toward treatment applications in which the most 

common mine drainage constituents (Fe, Mn and Al) are targeted for removal within a 

typical treatment pH range of 6.0 to 9.0. Users should be aware that in other instances, for 

example where a very high treatment pH is required or where additional mine drainage 

constituents such as trace metals are targeted, significant differences in polymer type, 

application rate and cost may exist.

2. In both passive and active treatment applications polishing wetlands have been proven to 

be an effective strategy for removal and retention of low concentrations of suspended 

solids. In certain treatment applications polishing wetlands may eliminate the need for, or 

significantly reduce the operational costs of, a polymer system.

3. Users should be aware that adequate and efficient mixing of the polymer solution with 

the treated water is critical for achieving optimal performance at minimal cost. While not 

specifically included within the module, the user should be aware that many mine 

drainage treatment facilities employ additional mixing strategies such as the use of 

multiple polymer dose points and or slow mix tanks or compartments within the 

treatment train in order to optimize polymer mine water mixing opportunities. 

4.0 References
21

5.0 Figures 

Figure 1: Blending skid with progressive cavity pump and computerized 

controls for emulsion polymer used at a site for flocculating iron 

hydroxide sludge and dewatering in Geotubes.
22

Figure 2. Emulsion polymer totes (275-gallon) for use at a mine 

drainage treatment facility in Pennsylvania.
23

Figure 3. Super sack (1,650 lbs) feeder option as part of an automatic 

dry polymer make down system that automatically dispenses dry 

polymer product to produce a made down solution.
24

Figure 4. Manual make down of dry polymer into day tank using 

Hootonanny Eductor system on top of tank at a mine drainage treatment 

facility.
25

Figure 5. Stainless steel blending/aging tank for made down dry polymer 

solution with mixers mounted over the tanks.
26

Figure 6. Pumps and inline static mixers for mixing the made down 

polymer solution with push (dilution) water prior to addition to the mine 

drainage source.
27

Figure 7. Photo of two pumps as part of the dosing skid component of a 

dry polymer automatic system.
28

Figure 8. Application point of polymer into the mine drainage at a 

treatment facility.