United States   ,
        Environmental Protection
        Agency
Office of Research and \
Development    j
Washington, DC 20460'
EPA/600/R-00/063
June 2000
http://www.epa.gov
        Arsenic Removal from
        Drinking Water by
        Coagulation/Filtration and
        Lime Softening  Plants

0
            As (III)
        As(V)
      fe-
      fc

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                                                     EPA/600/R-00/063
                                                         June 2000
Arsenic  Removal from Drinking Water
          by Coagulation/Filtration
         and Lime Softening Plants
                            by

                        Keith A. Fields
                        Abraham Chen
                          Lili Wang

                          Battelle
                    Columbus, OH 43201-2693
                     Contract No. 68-C7-0008
                      Work Assignment 2-09
                            for
                     Work Assignment Manager

                        Thomas J. Sorg
                Water Supply and Water Resources Division
              National Risk Management Research Laboratory
                      Cincinnati, OH 45268
              National Risk Management Research Laboratory
                  Office of Research and Development
                  U.S. Environmental Protection Agency
                      Cincinnati, OH 45268
                                          o
Printed on Recycled Paper

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                              Disclaimer
The information in this document has been funded by the United States Environ-
mental Protection Agency (EPA) under Work Assignment (WA) 2-09 of Contract No.
68-C7-0008 to Battelle. It has been subjected to the Agency's peer and administra-
tive reviews and has been approved for publication as an EPA document. Mention of
trade names or commercial products does not constitute an endorsement or recom-
mendation for use.

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                                Foreword
The  United States Environmental Protection Agency is charged by Congress with
protecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement action leading to
a compatible balance between human activities and the ability of natural systems to
support and nurture life. To meet this mandate, EPA's research program is providing
data and technical support for solving environmental problems today and building a
science knowledge base necessary to manage our ecological resources wisely, under-
stand how pollutants affect our health, and prevent or reduce environmental risks in
the future.

The National Risk Management Research Laboratory is the Agency's center for inves-
tigation of technological and management approaches for reducing risks from threats
to human health and the environment. The focus of the Laboratory's research pro-
gram is on methods for prevention and control of pollution to air, land, water, and sub-
surface resources: protection of water quality in public water systems; remediation of
contaminated sites and ground water; and  prevention and control of indoor air. The
goal of this research effort is to evaluate the performance on a full-scale level of five
processes, including coagulation/filtration, lime softening, iron  oxidation/filtration, ion
exchange, and  activated  alumina, to consistently remove arsenic over a sustained
period of time (1 year).

This publication has been produced as part of the Laboratory's  strategic long-term
research plan. It is published  and made available by EPA's Office of Research and
Development to assist the user community and to link researchers with their clients.

                                                    E.  Timothy Oppelt, Director
                                 National Risk Management Research Laboratory

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                                 Abstract
This report documents treatment plant information as well as results of sampling and
analysis at two coagulation/filtration plants (referred to in this document as Plants A
and  B) and one lime softening plant (referred to as Plant C). The objective of sam-
pling and analysis was to evaluate the effectiveness of the water treatment plants to
consistently remove arsenic (As) from source water. Additionally, data were collected
in this study to evaluate the characteristics of the residuals produced by the treatment
processes.

The  study was divided into three phases:  source water sampling, preliminary sam-
pling, and long-term evaluation. The first phase, source water sampling, was con-
ducted to evaluate source water characteristics at each plant. The second phase,
preliminary sampling, consisted of a four-week sampling period to refine procedures
prior to implementing the long-term evaluation phase. The third phase, long-term
evaluation, consisted  of weekly sample collection and  analysis for approximately
1 year. Sludge samples also were collected at each facility during a single sampling
event from settling  lagoons/ponds during  a two-month period. Samples of  recycle
supernatant water (Plant A) and supernatant discharge water (Plants B and C) were
collected monthly beginning in November 1998 and continuing until June 1999.

Long-term  evaluation  of Plants A and B demonstrated that conventional coagula-
tion/filtration can consistently achieve low levels of arsenic  in the treated water (i.e.,
less  than 5 ug/L). The total  arsenic concentrations at Plant A were reduced by an
average of 52%, which represents a decrease of average arsenic concentrations
from 7.5 ug/L in the source water to 3.5 ug/L in the finished water. Average total arse-
nic removal efficiency at Plant B was 79%, with an average source water concentra-
tion of 19.1 ug/L and an average finished water concentration of 4.0 ug/L. Adsorption
and  coprecipitation of As(V) with iron and aluminum floes are believed to  have been
the primary arsenic removal mechanisms at these plants.

The  lime softening facility,  Plant C, was not able to consistently reduce arsenic to low
levels in treated water. The average  total  arsenic  concentration in Plant C source
water was 32.0 ug/L, and  the lime softening plant reduced the average total arsenic
concentration to 16.6 ug/L in the finished water, which equals a 45%  removal effi-
ciency. As(lll) was the primary species of soluble arsenic in the raw water and was
almost completely oxidized to As(V) as a result of two chlorination steps that occurred
prior to softening and prior to filtration. The primary mechanism of arsenic removal
was  likely adsorption and  coprecipitation of As(V)  with iron that was present in the
source water. Plant C operated at a pH of 9.6, a level at which arsenic removal by
coprecipitation with  calcium  carbonate is reported to be less than 10% (Sorg and
Logsdon, 1978; McNeill and Edwards, 1997b).

None of the sludge samples  collected at Plants A, B, and C qualified as a hazardous
waste based on Toxicity Characteristic Leaching Procedure (TCLP) testing for metals.
Therefore,  nonhazardous waste landfills should be able to accept the sludge gener-
ated by these treatment processes.
                                      IV

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                                Contents

Foreword	iii

Abstract	iv

Appendices	vi

Figures	vii

Tables	viii

Acronyms and Abbreviations	x

1.0 Introduction	1
     1.1  Background	1
         1.1.1 General Chemistry of Arsenic	1
         1.1.2 Determination of Arsenic Species	'.	3
         1.1.3 Treatment Technologies for Arsenic Removal	3
               1.1.3.1 Coagulation/Filtration	:	3
               1.1.3.2 Lime Softening	4
         1.1.4 Data Gaps	5
     1.2  Objectives	5
     1.3  Report Organization	5

2.0 Conclusions	6

3.0 Materials and Methods	7
     3.1  General Project Approach	7
     3.2  Preparation of Sampling Kits and Sample Coolers	8
         3.2.1 Preparation of Arsenic Speciation Kits	8
         3.2.2 Preparation of Recycle Backwash Water/Supernatant
              Discharge Sampling Kits	9
         3.2.3 Preparation of Sample Coolers	9
     3.3  Sampling Procedures	10
         3.3.1 General Approach and Sampling Schedules	10
         3.3.2 Arsenic Field Speciation Procedure	10
         3.3.3 Recycle Supernatant Water/Supernatant Discharge Sampling
              Procedure	13
         3.3.4 Sampling Procedure for Other Water Quality Parameters	13
     3.4 Analytical Procedures	13

4.0 Results and  Discussion	17
     4.1  Plant Selection	17
     4.2 Plant A	17
         4.2.1 Plant A Description	18

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         4.2.2 Initial Source Water Sampling	18
         4.2.3 Preliminary Sampling	19
         4.2.4 Long-Term Sampling	22
                4.2.4.1  Arsenic	22
                4.2.4.2  Other Water Quality Parameters	24
                4.2.4.3  Recycle Supernatant Water	26
                4.2.4.4  Sludge	27
     4.3 Plant B	28
         4.3.1  Plant B Description	29
         4.3.2 Initial Source Water Sampling	29
         4.3.3 Preliminary Sampling	30
         4.3.4 Long-Term Sampling	33
                4.3.4.1  Arsenic	33
                4.3.4.2  Other Water Quality Parameters	35
                4.3.4.3  Supernatant Discharge Water	38
                4.3.4.4  Sludge	38
     4.4 Plant C	39
         4.4.1  Plant C Description	39
         4.4.2 Initial Source Water Sampling	40
         4.4.3 Preliminary Sampling	41
         4.4.4 Long-Term Sampling	44
               4.4.4.1  Arsenic	44
               4.4.4.2  Other Water Quality Parameters	46
               4.4.4.3  Supernatant Discharge Water	49
               4.4.4.4  Sludge	49

5.0 Quality Assurance/Quality Control	51
     5.1  Quality Assurance Objectives	51
     5.2 Overall Assessment of Data Quality	51
         5.2.1  Total Arsenic, Aluminum, Iron, and Manganese	51
         5.2.2  Water Quality Parameters	52
         5.2.3  TCLP Metals in Sludge	52

6.0 References	53


Appendices

Appendix A.   Complete Analytical Results from Long-Term Sampling at
              Plant A	55
Appendix B.   Complete Analytical Results from Long-Term Sampling at
              Plant B	69
Appendix C.   Complete Analytical Results from Long-Term Sampling at
              Plant C	,	83
                                     VI

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                                 Figures
                                                                         Page
Figure 1 -1.    Solubility Diagrams for As(III) and As(V)	2
Figure 3-1.    Example of Sample Bottle Label	10
Figure 3-2.    Photographs of a Typical Sample Cooler (with Three Sample
             Compartments) and a Color-Coded Instruction Sheet	11
Figure 3-3.    Instruction Sheet for Arsenic Field Speciation	14
Figure 3-4.    Instruction Sheet for Recycle Supernatant Water/Supernatant
             Discharge Sampling	15
Figure 4-1.    Schematic Diagram of Plant A Treatment Process	18
Figure 4-2.    Process Flow Diagram and  Sampling Locations at Plant A	20
Figure 4-3.    Total Arsenic Analytical Results During Long-Term Sampling at
             Plant A	24
Figure 4-4.    Arsenic Form and Species Analytical Results During Long-Term
             Sampling at Plant A	25
Figure 4-5.    Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at
             Plant A	!	27
Figure 4-6.    Schematic Diagram, Plant B	29
Figure 4-7.    Process Flow Diagrams and Sampling Locations at Plant B	31
Figure 4-8.    Total Arsenic Analytical Results During Long-Term Sampling at
             PlantB	35
Figure 4-9.    Arsenic Form and Species Analytical Results During Long-Term
             Sampling at Plant B	'.	36
Figure 4-10.  Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at
             PlantB	38
Figure 4-11.  Schematic Diagram, Plant C	40
Figure 4-12.  Process Flow Diagram and  Sampling Locations at Plant C	42
Figure 4-13.  Total Arsenic Analytical Results during Long-Term Sampling at
             Plant C	46
Figure 4-14.  Arsenic Form and Species Analytical Results During Long-Term
             Sampling at Plant C	47
Figure 4-15.  Inlet Turbidity, pH, Hardness, and Alkalinity Analytical Results at
             Plant C	49
                                     VII

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                                 Tables
                                                                       Page
Table 3-1.   Sample Containers and Preservation Methods	9
Table 3-2.   Summary of Sampling Activities at Plants A, B, and C	12
Table 3-3.   Summary of Sampling Schedule for Plants A and B	12
Table 3-4.   Summary of Sampling Schedule for Plant C	13
Table 3-5.   Summary of Analytical Methods for Arsenic Treatment Study	16
Table 4-1.   Initial List of Treatment Facilities Identified for the Study	17
Table 4-2.   Source Water Analytical Results at Plant A (February 3,1998)	19
Table 4-3.   Analytical Results from Preliminary Sampling at Plant A
            (April 9,1998 through April 30,1998)	21
Table 4-4.   Summary of Arsenic Analytical Results at Plant A (June 1998-
            June1999)	23
Table 4-5.   Summary of Water Quality Parameter Analytical Results at Plant A
            (June 1998-June 1999)	26
Table 4-6.   Summary of Analytical Results from Recycle Backwash Water
            Samples at Plant A (November 11, 1998-June 16, 1999).	27
Table 4-7.   Previous Analytical Results of Sludge Sampling at Plant A (1996-
            1997)	28
Table 4-8.   Analytical Results of Sludge Sampling at Plant A
            (December 2,1998)	28
Table 4-9.   Source Water Analytical Results at Plant B (February 5,1998)	30
Table 4-10.  Analytical Results from Preliminary Sampling at Plant B (April 23,
            1998 through May 14,1998)	32
Table 4-11.  Summary of Arsenic Analytical Results at Plant B (June 1998-
            June1999)	34
Table 4-12.  Summary of Water Quality Parameter Analytical Results at Plant B
            (June 1998-June 1999)	37
Table 4-13.  Summary of Analytical Results from Supernatant Discharge Water
            Samples at Plant B (November 12,1998-June 17, 1999)	39
Table 4-14.  Analytical Results of Sludge Sampling at Plant B
            (December 15, 1998)	39
Table 4-15.  Arsenic Concentrations in Ground Water Wells at Plant C (1992)	40
Table 4-16.  Source Water Sampling Analytical Results at Plant C
            (February 27,1998)	41
Table 4-17.  Analytical Results from Preliminary Sampling at Plant C (April 27,
            1998 through May 18, 1998)	43
Table 4-18.  Summary of Arsenic Analytical Results at Plant C (June 1998-
            June 1999) 	45
                                    VIII

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Table 4-19.  Summary of Water Quality Parameter Analytical Results at Plant C
            (June 1998-June 1999)	48
Table 4-20.  Summary of Analytical Results from Supernatant Discharge Water
            Samples at Plant C (November 9,1998-June 14, 1999)	50
Table 4-21.  Analytical Results of Sludge Sampling at Plant C
            (November 16,1998)	.;	50
                                    IX

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                  Acronyms and Abbreviations
AF           after-filtration sampling location
AWWA       American Water Works Association

Dl            distilled

EDR          electrodialysis reversal
EPA          United States Environmental Protection Agency

GFAAS       graphite-furnace atomic-absorption spectrophotometer
Gl            gastrointestinal
gpm          gallons per minute

HOPE        high-density  polyethylene

ICP-MS       inductively coupled plasma-mass spectrometry
ID            identification
IN            inlet sampling location

MCL          maximum contaminant level
MDL          method detection limit
mgd          million gallons per day
MS           matrix spike
MSD          matrix spike duplicate

ND           not detected
MOM          natural organic matter
NTU          nephelometric turbidity units

PAC          powdered activated carbon
PAX-18       liquid  polyaluminum chloride
PF           before filtration (prefiltration) sampling location
POC          point of contact

QA           quality assurance
QAPP        Quality Assurance Project Plan
QA/QC       Quality Assurance/Quality Control

RPD          relative percent difference

SDWA        Safe Drinking Water Act
STLC         soluble threshold limit concentration

TCLP         Toxicity Characteristic Leaching Procedure
TDS          total dissolved solids

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TOC
TSS

WA
WAM

%R
total organic carbon
total suspended solids

work assignment
work assignment manager

percent recovery
                                    XI

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                         Acknowledgments


Sincere appreciation is extended to the three water treatment facilities that partici-
pated in this study. The staff from each facility contributed greatly to this project by
collecting samples every week for more than 12 months. The success of this study
depended on the personnel of these  plants, and all performed exceptionally well.
Their work on this  project was uncompensated, making their superb efforts even
more remarkable. Personnel from all  plants are thanked for their hard work and
dedication throughout the duration of this project.
                                    XII

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                                            .  Introduction
This project consisted, in part, of a field study to collect
samples from various locations throughout the treatment
processes  at two coagulation/filtration plants and one
lime softening plant. These samples were analyzed and
used to evaluate the effectiveness of conventional coag-
ulation/filtration and lime softening processes to consist-
ently reduce arsenic (As) in source water to low levels.
This project also includes the collection of process resid-
ual samples that were used to determine the quantity
and  chemical characteristics of  the  residuals produced
by these treatment processes. This report describes the
design and operation of the three treatment plants and
presents the results of the analyses of the water samples
collected from the plants during one year of operation.

1.1  Background

The  Safe Drinking Water Act (SDWA) of 1994 mandates
that  the United States Environmental Protection Agency
(EPA) identify and regulate drinking water contaminants
that  may have an adverse human health effect and that
are known  or anticipated to occur in public water supply
systems. Arsenic is a naturally occurring contaminant
that  has known adverse human health effects. Excessive
amounts of arsenic can cause acute gastrointestinal (Gl)
and  cardiac damage. Chronic doses can cause vascular
disorders such as blackfoot disease (Chen, S.L., et al.,
1994), and epidemiological studies have linked arsenic
to skin and  lung cancer (Tate  and Arnold,  1990). In
1975, under  the SDWA, EPA established a maximum
contaminant level (MCL) for arsenic at 0.05 mg/L. Since
that  time, revision  of the MCL  has been considered a
number of  times, but  no change has been made. The
SDWA was amended in 1996 and  these amendments
required that the EPA develop an arsenic research strat-
egy  and publish a proposal to  revise the arsenic MCL by
January 2000.

A draft arsenic research plan was prepared by the EPA
in December 1996 and was finalized in  February 1998
based upon a technical review  by the EPA's Board of
Scientific Counselors  (EPA, 1998). The plan identifies
the research  needed by the EPA to support a proposed
revision of the arsenic MCL. The plan also identifies a
number of treatment methods  available for arsenic  re-
moval and recognizes the need to determine the capabil-
ity of these  technologies to reduce arsenic  to a  level
significantly lower than the current MCL. This study was
conducted as part of the EPA's arsenic research strat-
egy to determine the ability of conventional water treat-
ment processes to consistently remove  arsenic  from
drinking water.

1.1.1  General Chemistry of Arsenic

Arsenic is a  common, naturally occurring drinking water
contaminant  that originates from arsenic-containing rocks
and soil and  is transported to natural waters through ero-
sion  and dissolution. Arsenic occurs in natural waters in
both organic and inorganic forms.  However, inorganic
arsenic is predominant in natural waters and is the  most
likely form of arsenic to exist at concentrations that cause
regulatory concern (Edwards et al., 1998).

The  valence and species of inorganic arsenic  are de-
pendent  on  the oxidation-reduction conditions  and the
pH of the water. As a general rule of thumb, the reduced,
trivalent form [As(lll)] normally  is found in ground water
(assuming anaerobic conditions) and the oxidized, pen-
tavalent form [As(V)] in surface water (assuming aerobic
conditions), although this does not always hold true  for
ground water, where both forms have been found  to-
gether in the same water source. Arsenate exists in four
forms  in  aqueous  solution  based  on  pH:  H3AsO4,
H2AsO4~, HAsO42~, and AsO,,3".  Similarly, arsenite exists
in five forms: H4AsO3+,  H3AsO3, H2AsO3~,  HAsO32~, and
AsOg3". As shown in Figure 1-1, which contains solubility
diagrams for As(lll) and As(V),  ionic forms of arsenate
dominate at pH >3, while arsenite  is neutral at pH  <9
and  ionic at  pH >9. Conventional treatment technologies
used for arsenic removal, such as  coagulation/filtration
and  lime softening,  rely on adsorption and coprecipita-
tion  of arsenic to metal hydroxides. Therefore, the va-
lence and species of soluble arsenic are very significant
in evaluating arsenic removal.

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                      .1
                   .032
                 a.
                     .01
                  .0032
                   .001

                           -H2AsO3+
Conditions
As(III) .Ippm
                                                            10
                               12
                     14
                                                pH
                S
                n.
                                 / HyAsQ.- \  /" HAsO42- \  /AsO43-
                                i    *    *    \  /         *      \ /     *
          X
          /   I
                                                                 x
                                                    Conditions    '
                                                    As(V) .Ippm /
                                                               /
                  .0032
                   .001
 \    i
 \    i
 \    i
 \  i
 \  i
	i__i	
                                    \ 5
                                                            10
                               12
                     14
                                                pH
Figure 1-1. Solubility Diagrams for As(lll) and As(V)

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Although soluble arsenic species typically make up the
majority  of the total  arsenic concentration in  natural
waters, some research indicates that particulate  arsenic
can exist at significant concentrations. Studies by Chen
et al. (1994) and  Hemond (1995) measured particulate
arsenic at levels of 17 and 50% of the total arsenic con-
centration, respectively,  in the  subject source  waters.
Therefore, determination of the  particulate arsenic con-
centration is important because it can provide insight into
the arsenic removal mechanisms that occur during treat-
ment.

1.1.2 Determination of Arsenic Species

Although total arsenic can be  effectively preserved  in
field  samples, presently no method exists to consistently
preserve inorganic arsenic species in field samples. Pre-
servation of total  arsenic is accomplished  by acidifying
the sample to pH  < 2  in the field. However, a high level
of ambiguity exists when acids such as nitric acid (HNO3)
or hydrochloric acid  (HCI) are used to preserve inorganic
species of arsenic.  Interconversion of As(lll) and As(V)
in samples preserved with 0.05 N  HCI  have been  re-
ported to occur within one day (Andreae, 1977). Another
laboratory study conducted by Eaton et al. (1997) exam-
ined  preservation  of arsenic using humic acid, ascorbic
acid,  and HCI; the study concluded  that no effective
methods exist for preserving As(lll)  and As(V) in water
samples. Some researchers have used freezing of sam-
ples  as  a means  of preserving the inorganic species  of
arsenic. However, freezing is neither a cost-effective nor
a practical method for field sampling.

In response to the lack of techniques available for ade-
quately  preserving arsenic species, field speciation pro-
tocols have been developed by Ficklin (1982), Clifford et
al. (1983), and Edwards  et al. (1998). In each of these
studies, an anion exchange resin column is used  for field
speciation of arsenic. Ficklin (1982) used a strong anion
exchange resin (Dowex 1 x 8,  100-200 mesh,  acetate
form) in  a 10 cm x 7  mm glass  column  to sieparate
As(lll) from As(V)  in water samples that had been filtered
through a 0.45-um membrane filter and acidified with 1 %
HCI. The resin was supplied in chloride form and was
converted to the acetate form. However, in  the protocol
by Clifford et al. (1983), a chloride-form strong base anion
resin (ASB-2, 30-60 mesh) was used to separate As(lll)
from As(V). In this method, the sample was not filtered
or preserved with acid. Both Ficklin  and Clifford used a
graphite-furnace  atomic-absorption   spectrophotometer
(GFAAS) to determine the arsenic concentration.

More recently, Edwards et al. (1998) made the following
modifications to Ficklin's method: (1) substituted 50-  to
100-mesh resin for  the 100- to 200-mesh resin to allow
faster sample flow; (2)  used 12-cm x 15-mm polypro-
pylene columns to improve safety and speed of sample
treatment; (3) Used 0.05% H2SO4 instead of 1% HCI to
acidify samples  prior to resin  treatment. Edwards et
al.'s use of H2SO4 helped to  prevent potential  problems
associated with overacidification  of the sample, and also
helped to prevent CP from interfering with the inductively
coupled plasma/mass spectrometry (ICP-MS) analysis.
The reported recoveries of As(lll) and As(V) ranged from
80 to  120% by Ficklin (1982), 95 to 117% by Clifford et
al. (1983), and 100 to 105% by Edwards et al. (1998).
For this study, the decision was made to utilize a field
speciation technique similar to that used by Edwards et
al. (1998).

1.1.3 Treatment Technologies for
       Arsenic Removal

Several common treatment technologies are used for re-
moval of inorganic contaminants, including arsenic, from
drinking water supplies.  Large-scale treatment facilities
often  use conventional  coagulation with alum or  iron
salts followed  by sedimentation  and filtration to remove
arsenic. Lime' softening is another common,  conven-
tional  treatmeht  process that can potentially remove
arsenic from source waters. Smaller-scale systems and
point-of-entry systems often use anion exchange resins
or activated alumina. Other arsenic removal technologies
include manganese greensand, reverse osmosis, electro-
dialysis reversal (EDR), nanofiltration, and adsorption on
activated carbon. This report focuses on the two conven-
tional  treatment  processes commonly used for arsenic
removal at large-scale operations: coagulation/filtration
and lime softening. Two  additional reports will  be devel-
oped  that focus on (1) iron removal plants and (2) anion
exchange and activated alumina plants.

1.1.3.1 Coagulation/Filtration

Conventional coagulation/filtration is  a common  water
treatment methodology used to  remove suspended and
dissolved solids from source water. The coagulation pro-
cess  promotes aggregation of the  suspended solids to
form floes, which then can be removed through sedimen-
tation and/or filtration. Coagulation is typically described
as a process consisting of three steps: coagulant forma-
tion, particle destabilization,  and interparticle collisions.
The first two steps, coagulant formation and particle de-
stabilization, occur  during rapid mixing,  and  the third
step occurs during flocculation. Alum and iron  (III) salts,
such as ferric chloride, are the most common coagulants
used  for drinking water treatment (Amirtharajah  and
O'Melia, 1990).

Coagulation using alum  and  iron (III) salts can be used
to remove dissolved inorganic  drinking water  contami-
nants, such as arsenic.  Removal mechanisms for dis-

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solved inorganics consist of two primary mechanisms:
adsorption and occlusion (Benefield and Morgan, 1990).
During the adsorption process, the dissolved contami-
nant attaches to the surface of a particle or precipitate.
Occlusion occurs when the dissolved contaminant is
adsorbed to a particle and then entrapped as the particle
continues to agglomerate. Several factors affect the co-
agulation process, including coagulant dosage, pH, tur-
bidity, natural organic mater (NOM), anions and cations
in solution, zeta potential, and temperature (Amirtharajah
and Q'Melia, 1990).

Numerous  bench- and  pilot-scale  studies  and  some
short-term full-scale evaluations have been performed to
evaluate arsenic  removal  using conventional coagula-
tion/filtration using alum and iron (III) salts. Most of these
studies  have focused  on removal of As(V)  rather than
As(lll) because better As(V) removal can be achieved
under comparable conditions, and As(lll) can easily be
converted to As(V) using a strong oxidant such as chlo-
rine (Hering et al., 1996; Sorg, 1993). Ferric and alum
coagulation  are equally effective  on  a molar  basis
(Edwards, 1994). However, on a weight basis (e.g., mg/L
of ferric chloride vs. mg/L of alum), coagulation with iron
(III) salts achieves better removal than coagulation with
aluminum salts  (Sorg  and Logsdon, 1978; Sorg,  1993;
Chen, B.C., et al., 1994; Scott et al., 1995). These results
are observed primarily because iron hydroxide is less
soluble than aluminum hydroxide over a wider pH  range
(Benefield and  Morgan,  1990). McNeil! and Edwards
(1997a) observed that aluminum floes with sorbed arse-
nic could pass through filters and that arsenic removal
increased when  capture of  aluminum floes  increased.
Other research  indicates that As(V) removal is not pH
dependent between pH 5.5 to 8.5 when iron coagulants
are used, although As(V) removal efficiency  decreases
above pH 7 using alum (Sorg, 1993).

Previous studies also indicate that arsenic removal is
directly correlated with coagulant dosage (i.e., more co-
agulant  increases arsenic removal) (Sorg and Logsdon,
1978; Sorg, 1993; Hering et  al.,  1996; Gulledge  and
O'Conner, 1973). Also,  arsenic removal efficiency ap-
pears to be independent of initial arsenic concentration
at levels of interest to drinking water treatment (Hering et
al., 1996; Chen,  R.C., et al., 1994; Edwards, 1994). Al-
though no correlation between turbidity removal and arse-
nic removal has been established, turbidity removal is a
prerequisite for  arsenic removal  (Chen, B.C.,  et al.,
1994).

1.1.3.2  Lime Softening
Lime softening commonly is used to reduce hardness in
source waters.  Hardness is  due primarily to the pres-
ence of calcium and magnesium ions. The lime provides
hydroxide ions that increase pH, which results in calcium
and magnesium removal due to the formation of CaCO3
and Mg(OH)2 precipitates. Also, lime softening has been
used for removal of heavy metals, radionuclides, dis-
solved  organics, and  viruses (Benefield and Morgan,
1990) through adsorption and occlusion with calcium
carbonate and magnesium hydroxide. The typical lime
softening treatment process train includes rapid mixing
of the  lime, flocculation of solids, and sedimentation.
These three processes are often combined into a single
unit referred to as a solids-contact softener (Benefield
and Morgan, 1990). Filtration usually follows these three
processes. Lime and  lime-soda typically are used for
softening, and selection is dependent on  the type  of
hardness. Lime alone is used for source  waters that
contain  little or ho noncarbonate hardness, while high
noncarbonate hardness may require both lime and lime
soda. Caustic soda  is sometimes  used  instead of lime
and lime-soda to decrease sludge production (increases
dissolved solids, but produces less sludge).

Only a few  studies  have been  conducted to evaluate
arsenic removal during lime softening. Bench-scale and
pilot-scale studies by Sorg and Logsdon (1978) indicate
that  arsenic removal  during  lime  softening  is  pH
dependent. Bemoval of As(lll) and As(V) are low  at pH
less than 10; however, As(V) removal approaches  100%
and As(lll) removal approaches 75% at pH greater than
10.5. As part of a survey of full-scale water treatment
plants by McNeill and Edwards (1995), lime softening
plants were able to achieve up to 90% arsenate removal
if pH was high enough to precipitate magnesium hydrox-
ide (i.e.,  near  pH 11). When only  CaCO3 precipitated,
As(V) removal was between 0 and  10%; however,  when
CaCO3 and Mg(OH)2 were precipitated, As(V) removals
were between  60 and  95% (McNeill  and  Edwards,
1995). Coprecipitation of As(V) with Mg(OH)2 appears to
be the primary arsenic  removal mechanism for  As(V)
during lime softening.

McNeill and Edwards published results from bench-scale
experiments designed to evaluate the basic mechanisms
of arsenic removal during lime softening (McNeill and
Edwards,  1997b).  Consistent  with  previous findings,
greater than 90% arsenate  removal  was observed  at
above pH 11 where Mg(OH)2 was precipitated (McNeill
and Edwards, 1997b). Also, it was determined that trace
amounts of orthophosphate and the presence of carbon-
ate could limit arsenate removal by Mg(OH)2. If  man-
ganese was present in the source water, some As(V) re-
moval could be achieved through sorption with Mn(OH)2,
although Mn3(AsO4)2 precipitate formation was not deter-
mined to be a  major mechanism (McNeill and Edwards,
1997b). Other  findings from the same study indicated
that arsenate removal percentages were relatively con-
stant for arsenic concentrations between 5  to 75 ug/L.
Also, addition  of  iron  before softening  could increase

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arsenic removal; however,  competition between arsenic
and carbonate for sorption sites  on the iron hydroxide
reduced the  removal efficiency to levels  below those
normally achieved with a conventional coagulation/filtra-
tion process using iron (111) salts (McNeill and Edwards,
1997b).

1.1.4 Data Gaps

The removal  of arsenic from drinking water by conven-
tional coagulation/filtration has been extensively studied
at the laboratory and pilot-scale  level. To  a lesser de-
gree,  arsenic removal by lime softening has been stud-
ied at the laboratory and pilot-scale level. Although some
short-term full-scale  evaluations  have been performed
for both treatment processes, little data  exist on the
capability of these processes in full-scale applications to
reduce arsenic on a sustained basis. Thus, a need exists
to determine the  effectiveness  of  coagulation/filtration
and lime softening to produce drinking water low in arse-
nic on a long-term basis, under varying operational and
seasonal conditions.

Another data  gap that exists concerning  conventional
drinking water treatment processes is the production and
disposal of residuals. Currently, little or no data exist on
the amounts and the chemical composition of residuals
generated by the arsenic  removal processes  and the
methods that  are environmentally  acceptable  for their
disposal. Therefore, information needs to be collected on
the quality and the chemical characteristics of the wastes
produced by the coagulation/filtration and lime softening
plants.
1.2  Objectives

One objective of this project was to evaluate the effec-
tiveness  of conventional coagulation/filtration  and lime
softening to consistently reduce arsenic concentrations in
source water to low levels. This report presents the  re-
sults of weekly monitoring for approximately one year at
two coagulation/filtration plants and one lime  softening
plant.

Another objective of this study was to examine the resid-
uals produced during treatment at conventional coagula-
tion/filtration and lime softening plants. Information was
collected on the quality and chemical characteristics of
the wastes produced by these drinking water treatment
processes.

1.3  Report Organization

Section 1.0 provides background information for the field
study and project objectives. Section 2.0 of this report pre-
sents the conclusions from the study of the two conven-
tional coagulation/filtration plants and the lime  softening
plant. Section 3.0 describes the materials and methods
used to conduct this study. Section 4.0 discusses the
results  of the study  and Section  5.0 provides specific
information on quality assurance/quality control (QA/QC)
procedures. Section 6.0 is a list of references cited in the
text. Appendices A, B, and C present the complete set of
analytical data collected at Plants A and B (the two coagu-
lation/filtration  plants), and C (the  lime softening plant),
respectively, during long-term sampling.

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                                           2.  Conclusions
The U.S. EPA currently is in the process of revising the
arsenic MCL, and it is anticipated that the revised stand-
ard will be significantly lower than the existing MCL of
0.05 mg/L  Therefore, there is a need to determine the
ability of existing treatment processes to consistently re-
move arsenic to  low levels. The primary objectives of
this  project were to document arsenic  removal at  two
conventional coagulation/filtration plants and  one lime
softening plant, and to characterize the residuals (sludge
and supernatant water) at these treatment plants.

The study was divided into three major phases:  source
water sampling (February 1998),  preliminary  sampling
(April and  May 1998), and long-term evaluation  (June
1998 through June 1999). For the first phase, Battelle
staff traveled  to each facility to conduct source water
sampling,  which provided  information on source water
characteristics. The second phase, preliminary sampling,
consisted of a 4-week sampling period to refine the sam-
pling approach before implementing the long-term evalu-
ation phase. Battelle staff again traveled to each facility
to coordinate the first sampling event  and train plant per-
sonnel in sampling procedures for subsequent events.
The third phase, long-term evaluation,  consisted  of weekly
sample collection and analysis at each of the water treat-
ment plants, sludge sampling (November and December
1998), and recycle supernatant water (Plant A) and super-
natant discharge (Plants B and C) sampling (November
1998 through  June 1999). During the  long-term evalu-
ation phase, plant  personnel conducted sampling and
Battelle staff coordinated sampling logistics.

The primary focus of this study was the long-term per-
formance  of two coagulation/filtration  plants  and one
lime softening plant. The two coagulation/filtration plants
demonstrated  the  ability  to  consistently achieve  low
levels of arsenic in the treated  water  (i.e.,  less than
5 ug/L). Adsorption and  coprecipitation  of As(V) with
metal hydroxides, such as iron hydroxide and  alum hy-
droxide, are believed to be the primary arsenic removal
mechanisms in coagulation/filtration  plants. As(lll)  re-
moval  during coagulation/filtration was not  observed
during this study because both plants had surface water
source where the soluble arsenic was primarily arsenate.
Interestingly,  Plant B conducted  a 6-week test wherein
the coagulant was  changed from alum  to liquid poiy-
aluminum chloride  (i.e.,  PAX-18). During  this test, arse-
nic removal was negatively  impacted. Average removal
efficiency using alum was 84% compared to 43% using
PAX-18.  The difference in removal efficiencies may be
the result of  the difference  in pH achieved with each
coagulant.

The lime softening plant (Plant C)  evaluated for this
project was not able to  consistently reduce arsenic  to
low levels in the treated water. The plant did not operate
at a significantly high pH to precipitate magnesium hy-
droxide, and the arsenic  removal by coprecipitation with
calcium carbonate is  low (<10%)  (Sorg  and Logsdon,
1978; McNeill and Edwards, 1997b). However, arsenic
removal efficiency at Plant C was approximately 45%. It
is believed that the primary mechanism  of arsenic re-
moval is  coprecipitation of As(V)  with iron that is present
in the source  water. Prior research  indicates that arsenic
removal  by iron oxides  during  lime softening can be
hindered by competition for sorption sites  with carbonate
(McNeill  and  Edwards, 1997b). Also, little research ex-
ists on the coprecipitation of arsenic and  iron hydroxide
at pH values greater than 8.

The secondary focus of this study was on residual pro-
duction and the chemical characteristics of the residuals.
None of  the sludge sampled during this  study qualified
as  a hazardous waste  based on  the Toxicity Charac-
teristic Leaching  Procedure  (TCLP) tests for  metals.
Therefore, the sludge generated  by these treatment pro-
cesses  should be  accepted by nonhazardous  waste
landfills. However,  stricter requirements in California re-
garding  hazardous waste classification were not met by
Plant A  based  on  total  arsenic  concentrations. Super-
natant water from sludge lagoons was either discharged
to surface water bodies under state permits (Plants B
and C) or recycled back to the inlet (Plant A). The recy-
cle supernatant did not appear to contain high concen-
trations of arsenic. The ecological  risks associated with
discharging these waters were not assessed.

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                                    3.  Materials and Methods
This section discusses the materials and methods used
for performing the source water, preliminary, and long-
term sampling and data collection at two coagulation/fil-
tration plants and one lime softening plant. Section 3.1
describes the general  project approach.  Section  3.2
describes the preparation of arsenic speciation kits and
sample coolers. Section 3.3 provides detailed sampling
procedures. Section 3.4  discusses  pertinent analytical
procedures.

3.1  General Project Approach

Several consecutive tasks were performed to accomplish
the project objectives described in  Section  1.2.  These
tasks involved the following activities:

  •   Select treatment plants and conduct an initial site
     visit to collect source water samples at each
     selected plant

  •   Prepare a preliminary sampling  and data
     collection plan for each plant

  •   Finalize the sampling and data collection plan
     after completion of four weekly preliminary
     sampling events at each plant

  •   Implement the final sampling and data collection
     plan with weekly sampling events at each plant for
     one full year.

For  initial plant selection, a list of  potential treatment
plant candidates was compiled. Plant operators or other
key  personnel were contacted via telephone to  obtain/
confirm information  and solicit  interest in participating in
the  project. Each facility was evaluated,  in order of
importance, on source water arsenic  concentrations,
source water type,  available manpower to conduct the
year-long study,  availability of historical arsenic data,
and  plant size. Batteile recommended the selection of
two coagulation/filtration plants (designated as Plants A
and  B) and one lime softening  plant  (designated as
Plant C) for initial site visits and source water sampling.
These recommendations  were later approved  by  the
EPA Work Assignment Manager  (WAM). The informa-
tion collected during the site visits, including the concen-
tration and speciation of arsenic in  each source water,
was tabulated!and used as the basis for the final plant
selection.

Following  the final plant selection (Plants A,  B,  and C
again were selected), a preliminary sampling and data
collection plan was prepared for each plant to document
the plant's operation  and performance  for arsenic  re-
moval and the critical  parameters that would impact  the
removal. Each preliminary plan also described the data
collection  effort to characterize the  residuals  produced
by the  treatment  process.  The  approved preliminary
plans were implemented at Plants A, B,  and C during a
4-week trial period. A Batteile staff member revisited  the
plants during the first week of the trial period to observe
plant operations, perform sampling, conduct training of
plant support personnel, and establish/coordinate all re-
quired logistics (such as  receiving/shipping of  sample
coolers, chain-of-custody  coordination,  communication
methods,  and emergency/contingency  plans). The  re-
maining three sampling events during  the preliminary
sampling were performed by a designated point of con-
tact (POC) or an alternate at each  plant. The experience
gained during'the  trial period  was used to finalize  the
long-term sampling and data collection plans.

All water  and  residual samples were collected  and
analyzed  in accordance  with  the Category III  Quality
Assurance Project Plan  (QAPP)  prepared by Batteile
(1998) for this  project. Water samples  were collected
weekly at  Plants A, B, and C at three locations: (1)  the
inlet to the treatment plants (IN); (2) before the filtration
process (PF);  and (3) after the filtration process/at  the
plant outlet (AF). During  the preliminary and  long-term
sampling phases, field arsenic speciation was conducted
once every four weeks.  Starting from November 1998,
samples of recycle supernatant water (from the settling
pond  at Plant A) or supernatant discharge  water (from
lagoons at Plants B and  C)  were collected once every
four weeks from each plant. Three sludge samples also

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were collected from either the settling pond or lagoons
during one sampling event at each of the three plants.

All sample containers and arsenic speciation kits were
prepared by Battelle and sent in coolers on a weekly
basis to each plant via Federal Express. The  coolers
were returned to Battelle immediately after the  sample
collection had been completed. Analyses of arsenic, alu-
minum,  iron, and manganese  in  water were conducted
by Battelle's ICP-MS  laboratory. Wilson Environmental
Laboratories in Westerville,  OH, was subcontracted to
perform all other chemical analyses. Battelle coordinated
all sampling logistics.


3.2  Preparation of Sampling Kits and
    Sample Coolers

All arsenic speciation kits, recycle supernatant water/
supernatant discharge sampling kits, and sample coolers
were prepared at Battelle. The  following sections de-
scribe the relevant preparation procedures.

3.2.1  Preparation of Arsenic
      Speciation Kits

The  arsenic  field speciation  method  used an anion
exchange resin column to separate the soluble  arsenic
species, As(V) and As(lll). A 250-mL bottle (identified as
bottle A)  was  used to contain  an  unfiltered sample,
which was analyzed to determine the total arsenic con-
centration (both soluble  and  particulate). The  soluble
portion of the sample was obtained by passing the unfil-
tered sample through  a 0.45-um screw-on disc filter to
remove  any particulate arsenic and collect the filtrate in
a 125-mL bottle (identified as bottle B). Bottle B con-
tained 0.05% (volume/volume) ultra-pure sulfuric acid to
acidify the sample to about pH 2. At this pH,  As(lll) was
completely protonated as H3AsO3, and  As(V) was pres-
ent in both ionic (i.e., H2AsO4")  and  protonated forms
(i.e., H3AsO4) (see Figure 1-1). A portion of the acidified
sample  in bottle B was run through the resin column.
The  resin retains the As(V) and  allowed As(lll) (i.e.,
HjAsO,,) to pass through the column. (Note that the resin
will retain only H,AsO4" and  that H3AsO4, when  passing
though  the column, will be  ionized to H2AsO4" due to
elevated pH values in the column caused by the buffer
capacity of acetate exchanged from the resin.) The elute
of the column was collected in  another 125-mL bottle
(identified as bottle C). Samples  in bottles A, B, and C
were analyzed for total  arsenic using  ICP-MS. As(lll)
concentration was the total arsenic concentration of the
resin-treated  sample  in  bottle C. As(V) concentration
was calculated by subtracting As(lll) from the total solu-
ble arsenic concentration of the sample in bottle B.
Arsenic speciation kits were prepared in batch at Battelle
based on a method modified from Edwards et al. (1998).
Each arsenic speciation kit contained the following:

 •  Two anion exchange resin columns
 •  Primary and duplicate A, B, and C bottles
 •  One 400-mL disposable beaker
 •  Two 60-mL disposable syringes
 •  Several 0.45-um syringe-adapted disc filters.

Each speciation kit was packed in a plastic zip-lock bag
along with  latex gloves and a step-by-step  speciation
sampling instruction sheet. All chemicals used for pre-
paring  the  kits were  of analytical  grade or higher. The
arsenic speciation kits were  prepared according to the
following procedures:

 •  Resin  Preparation,. Before packing into columns,
    the anion exchange resin (Dowex 1-X8, 50-100
    mesh)  was converted from the chloride form (as
    supplied  by Supelco) to the acetate form accord-
    ing to the method used by Edwards et al. (1998).
    First, 1 kg of the resin was placed in a 3-L beaker.
    One liter of 1N sodium hydroxide (NaOH) then
    was added to the resin, stirred for an hour using
    an overhead stirrer, and drained. This NaOH rinse
    was repeated sequentially three times. The
    NaOH-treated resin was  then rinsed with two 1 -L
    batches of reagent grade water, followed by three
    acetic  acid  rinses. Each acetic acid rinse
    consisted of adding 1 L of 1N reagent grade
    acetic  acid  to the resin, stirring for 5 minutes, and
    draining the spent acid. The acetic acid-treated
    resin was subsequently rinsed with 3-L batches of
    reagent-grade water. The resin slurry was stored
    in a 2-L bottle and kept moist until use.

 •  Anion Exchange Column Preparation.  The
    resin columns used were 12 cm x 15 mm in size
    and made of polypropylene (Bio-Rad Labora-
    tories,  CA). Each column was slurry packed with
    about 20 g  (drained weight) of the prepared resin,
    yielding a resin depth of approximately 10.5 cm.
    The column was sealed with two plastic caps (one
    each on top and bottom) to prevent contamination
    and retain moisture prior to use.

 •  Sample  Bottles. VWRbrand™ TraceClean™ high-
    density polyethylene (HOPE) sample bottles (250
    and 125  mL) were used to prepare bottles A, B,
    and C. Bottles A and C were spiked with 500 and
    250 uL of concentrated ultra-pure nitric acid
     (HNO3), respectively; and bottle B was spiked with
     1.25 mL of 5% (volume/volume) ultra-pure sulfuric
    acid (H2SO4). H2SO4 was used to acidify the
    sample in bottle B because chloride (Cl~) in HCI
    could interfere with the ICP-MS arsenic detection

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    and HNO3 (an oxidizing agent) could damage the
    resin or form nitric acid-arsenic redox couples
    (Edwards et al., 1998).

  •  Beaker, Syringes, and Filters.  One 400-mL
    disposable plastic beaker was used to collect a
    water sample. Samples were filtered using 60-mL
    disposable plastic syringes with 0.45-um screw-on
    disc filters. All disposable beakers, syringes, and
    filters were rinsed with distilled (Dl) water and air-
    dried before being packed into the sampling kits.

3.2.2 Preparation of Recycle Backwash
       Water/Supernatant Discharge
       Sampling Kits

The recycle backwash water/supernatant discharge sam-
ples were collected for pH, hardness  (Plant C only), total
and soluble As, Al, Fe,  and Mn measurements. Each
sampling kit contained the following items:

  •  Primary and duplicate A and B bottles (both
    preserved with HNO3) to  contain unfiltered and
    filtered samples for total and soluble As, Al, Fe,
    and Mn analyses

  •  One 400-mL disposable beaker
                                   •  Two 60-mL disposable syringes

                                   •  Several 0.45-um screw-on disc filters

                                   •  Bottles provided by Wilson Environmental
                                     Laboratories used for pH and hardness (Plant C
                                     only) analyses.

                                 The sampling  kit was prepared in a similar way as the
                                 arsenic speciation kit except that bottle B was preserved
                                 with  HNO3 instead of H2SO4.  The sampling  kit was
                                 packed in a plastic zip-lock bag  along  with latex gloves
                                 and a step-by-step sampling instruction sheet.

                                 3.2.3 Preparation of Sample Coolers

                                 Sample containers for analysis of all water quality param-
                                 eters  except for total As,  Al, Fe, and Mn were provided
                                 by Wilson Environmental  Laboratories. These containers
                                 were  new,  rinsed with Dl water, allowed to air dry, and
                                 contained appropriate preservatives before being deliv-
                                 ered to Battelle. These bottles were labeled with the let-
                                 ter D, E,  F, or G, designating the specific analysis to be
                                 performed. Table 3-1 lists the sample container size and
                                 type (for  water and sludge samples), sample preserva-
                                 tion used, analysis to be performed, and holding time. All
                                 sample containers were labeled prior to shipment.
Table 3-1.  Sample Containers and Preservation Methods
      Container Size
     Container Type
                                                Preservation Method
                          Analyte
                                                                                             Hold Time
    Arsenic Speciation Samples
       250 mL (A)       certified clean HOPE bottles
       125mL(B)       certified clean HOPE bottles
       125mL(C)       certified clean HOPE bottles
                         4ฐC, HNO3 for pH <2
                          4ฐC, 0.05 % H2SO4
                         4ฐC, HNO3 for pH <2
    Recycle Backwash Water/Supernatant Discharge Samples
       250 mL (D)               plastic
       250 mL (A)
       250 mL (B)
certified clean HOPE bottles
certified clean HOPE bottles
    Water Quality Parameter Samples
       250 mL (D)                plastic
       250 mL (D)
        plastic
      4ฐC

4ฐC, HNO3forpH<2
4ฐC, HNO3forpH<2
                                4ฐC
                                                      4ฐC
                      Total As, Al, Fe, Mn         6 months
                    Dissolved As, Al, Fe, Mn       6 months
                    Dissolved As, Al, Fe, Mn       6 months
        pH               immediate
       TSS                7 days
  Total As, Al, Fe, Mn         6 months
Dissolved As, Al, Fe, Mn       6 months
                          Alkalinity              14 days
                            pH               immediate
                          Turbidity              48 hours
                           Sulfate              28 days
                          Fluoride              28 days
250 mL (E)
250 mL (F)
500 mL (G)
Sludge Samples
8oz(SL1)
4 oz (SL2)
4 oz (SL2)
TOC = total organic carbon.
TSS = total suspended solids.
plastic
plastic
glass

glass jar
glass jar
glass jar


4ฐC, HNO3 for pH<2
4ฐC, H2 SO4 for pH <2
4ฐC, H2SO4 for pH<2

4ฐC
4ฐC
4ฐC


Hardness
NCV/NCV
; TOC

Total As, Al, Fe, Mn
Water content, pH,
: TCLP metals
Water content, pH,
TCLP metals


6 months
28 days
14 days

6 months
14 days
14 days



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Figure 3-1 presents an example sample bottle label. The
sample identification (ID) consisted of five parts, includ-
ing a two-letter code for a water treatment plant, the
sampling date (mm/dd/yy), a two-letter code for a spe-
cific sampling location (e.g.,  IN  for inlet water, PF for
before the filtration process, and AF for after the filtration
process or at the plant outlet), a one-letter code desig-
nating the  analyses to be performed (see Table 3-1),
and a code indicating whether the sample is a primary
sample or a field duplicate sample. A field duplicate was
identified by adding a "dup" to the label and a primary
sample used no additional coding.
           AC-02/15/98-PF-B-DUP

  Date: 02/15/98          Time:  11am
  Collector's Name: Sample Collector
  Location: Any City WTP
  Sample ID: AC-02/15/98-PF-B-DUP
  Send to: Battelle
  Analysis Required: Total As, Al, Fe, and Mn
  Preservative:  0.05% sulfuric acid
Figure 3-1.  Example of Sample Bottle Label

After the sample bottles were labeled, they were placed
In coolers subdivided into three compartments, each cor-
responding to a specific sampling location at each plant.
Color coding was used to identify sampling locations and
all associated  sample bottles. For example, red,  blue,
and yellow were used to designate sample locations for
raw water at the plant inlet, before the filtration process,
and after the filtration process  (or at the plant outlet),
respectively. Other sampling and shipping-related mater-
ials, including latex gloves, chain-of-custody forms, pre-
paid Federal Express  air bills, sampling instructions, ice
packs,  and bubble  wrap, also were packed into coolers.
Arsenic speciation  kits or recycle supernatant water/dis-
charge sampling kits were included in the cooler when the
arsenic speciation or recycle supernatant water/discharge
samples were collected. After preparation, sample coolers
were sent to all  plants every Thursday via Federal Ex-
press for the following week's sampling activity. Figure 3-2
shows  photographs of a sample cooler with three sam-
ple compartments  and a color-coded instruction sheet
placed under the lid of the cooler.

3.3  Sampling Procedures

3.3.1  General Approach and Sampling
       Schedules

One or two Battelle staff members traveled to each plant
to collect source water samples, meet plant operators,
solicit interest in participating in this year-long sampling
program, and obtain plant design and operating informa-
tion  and historical water quality data. After  the  plant
selection, one Battelle staff member returned to  each
plant to collect samples at  selected sampling locations
and train the plant operator or a designated POC to per-
form sampling and field arsenic speciation. The remain-
ing three preliminary sampling events  and  long-term
sampling events then were conducted  by the trained
plant personnel. Residuals sampling, including a single
sludge sampling event and the monthly collection of re-
cycle supernatant  water or  supernatant samples  from
either a settling pond or lagoon also were collected by the
designated plant employees  with detailed  instructions
provided by Battelle over the telephone. Table 3-2  sum-
marizes the sampling activities at Plants A, B, and C.

During the preliminary and long-term sampling, the  sam-
ple collection was  conducted on a  4-week cycle, with
each week having unique sampling requirements. Ta-
bles 3-3  (Plants A  and B) and 3-4 (Plant C) summarize
the schedules for the initial source water,  the prelimi-
nary, the long-term, and the sludge sampling.

After receipt of the weekly sample coolers, plant person-
nel began sampling activities at the selected locations on
the scheduled dates. Upon  completion, all sample bot-
tles were sealed with tape and placed in the same  cool-
ers for return shipment to Battelle by Federal Express.
Upon receipt of the samples, the designated Battelle
sample custodian immediately examined and compared
the conditions of all sample bottles with those indicated
in the  chain-of-custody forms. Samples then were dis-
tributed to Battelle's ICP-MS laboratory and Wilson  Envi-
ronmental Laboratories for chemical analyses.

Throughout the duration of the study, Battelle staff main-
tained  frequent telephone contact with  each plant  to
ensure that all  sampling activities were  carried out as
planned.  For example, after scheduled arrival of sample
coolers, one Battelle staff member would call to confirm
the receipt of the coolers, answer any questions, discuss
irregular plant operations and unusual observations, and
propose/suggest corrective actions. When available, re-
sults of the chemical analyses also were discussed over
the telephone and data sheets were sent quarterly to the
plants  for review. Further,  plant operational and water
quality data (such  as plant  flowrate, chlorine addition
rate, ferric  chloride or alum  dosage [Plants A and B],
lime dosage [Plant C], pH, hardness [Plant C], and tur-
bidity)  were sent along with sample coolers  or trans-
mitted via facsimile to Battelle for information/evaluation.

3.3.2  Arsenic Field Speciation Procedure

The  procedures  for performing  field arsenic speciation
are shown  in Figure 3-3 and are  described as  follows
("steps" refer to Figure 3-3):
                                                    10

-------
Figure 3-2. Photographs of a Typical Sample Cooler (with Three Sample Compartments) and a Color-
           Coded Instruction Sheet
 •  Bottle A: A 400-mL disposable plastic beaker was
    rinsed thoroughly with the water to be sampled.
    The beaker then was used to collect a water
    sample and to fill bottle A with an aliquot of that
    sample (step 3). If necessary, additional sample
    water was added to the beaker after bottle A was
    filled to complete arsenic speciation sampling.

 •  Bottle B: A 60-mL disposable plastic syringe was
    rinsed thoroughly with the water in the plastic
beaker by completely filling and emptying the
syringe (step 4). After attaching a 0.45-um disc
filter and wasting about 10 drops of the filtrate, the
syringe was used to filter the water sample from
the beaker and fill bottle B. Bottle B then was
tightly capped and vigorously shaken for about
15 seconds to allow thorough mixing of the filtered
water and sulfuric acid (step 5).
                                                    11

-------
         Table 3-2. Summary of Sampling Activities at Plants A, B, and C
Sampling Activities
Initial source water sampling
Preliminary sampling
Long-term sampling
Sludga sampling
Recycle water sampling
Sampling
Frequency
Once
Weekly
Weekly ""
Once
Weekly
Plant A
02/03/98
04/09/98 through 04/30/98
06/24/98 through 06/16/99
12/02/98
1 1/1 1/98 through 06/1 6/99
PlantB
02/05/98
04/23/98 through 05/14/98
06/25/98 through 06/17/99
12/15/98
1 1/12/98 through 06/17/99
Plant C
02/27/98
04/27/98 through 05/18/98
06/22/98 through 06/14/99
11/16/98
1 1/09/98 through 06/14/99
         (a) Exceptforthe weeks of 11/23/98,12/21/98, and 12/28/98.
         Table 3-3. Summary of Sampling Schedule for Plants A and B
                                                               Water Sampling
Analyte
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
Al (total)
Fe (total)
Mn (total)
Al (dissolved)
Fe (dissolved)
Mn (dissolved)
Alkalinity
Sulfata
NO,-NO, (N)
TOG
Turbidity
PH
Hardness
Ca Hardness
Mg Hardness
TCLP Metals
Percent Moisture
PH
As (total)
Fe (total)
Initial Source
Water Sampling
(Once)
W>
W">
W>
W"
W">
W
W"
W"



W"
wซ
W"
W1"
W"1
W"
W"
W1"
W"





Preliminary Sampling Cycle
Week 1 Week 2
W1"
W"
W1
W"
Wc>
W"
W"
W1"



W
W
W
W
W
W








W




W
W
W



W"
ww
Ww
w">
W"
W"








Week 3 Week 4
W




W
W
W



W
W
W
W
W
W








W




W
W
W



W
W
W
W
W
W









Week
W1"
W1"
W1"
W"1
W11"
W"
w"ป
W"
W1'1
W">
ww
W
W
W
W
W
W








Long-Term
Sampling Cycle

1 Week 2 Week 3 Week 4
W




W
W
W



W"
W'ซ
W"
W"
W"
W"








W, R<"
R""
R">


W, R">
W, R">
W, R1"
W, R"1
W, Rw
W, R("
W
W
W
W
W
W, R1"








W




W
W
W



W
W
W
W
W
W








Sludge
Sampling
(Once)




















S
S
S
S
S
           (a) s Duplicate samples collected and analyzed.
           W s Water samples collected from the inlet, prefiltration, and after filtration locations.
           R = Recycle supernatant water sample collected at Plant A; Supernatant discharge water sample collected at Plant B.
           S s Sludge sample; three sludge samples were collected at each of Plants A and B.
           Empty cells indicate no samples taken.
             Bottle C: The protective caps on the top and
             bottom of a resin column were removed and
             approximately 40 ml_ of the water in bottle B was
             wasted through the column. This initial 40 ml_ was
             used to displace the water in the resin column and
             to ensure attainability of a representative sample
             from the column. The resin  column then was posi-
             tioned over bottle C, and the water from bottle B
             was passed through the column until approxi-
             mately 20 mL of the resin-treated sample had
             been collected in bottle C (step 6).
•  The procedure as described under the above
   three bullets was repeated to obtain duplicate
   bottles A, B, and C.

•  Upon completion, the individual performing the
   speciation signed on a chain-of-custody form
   (step 7). All sample bottles (for arsenic speciation
   and other water quality parameters), along with
   the signed chain-of-custody form, were placed in
   the original cooler with ice packs and shipped via
   Federal Express to Battelle (step 8).
                                                               12
_

-------
Table 3-4. Summary of Sampling Schedule for Plant C
Analyte
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
Al (total)
Fe (total)
Mn (total)
Al (dissolved)
Fe (dissolved)
Mn (dissolved)
Alkalinity
Sulfate
NO3-NO2 (N)
TOC
Turbidity
pH
Hardness
Ca Hardness
Mg Hardness
TCLP Metals
Percent Moisture
pH
As (total)
Fe (total)
Initial Source
Water Sampling
(Once)
W*
W"ป
W"
W""
W"
W""
W"*
W'ซ



W""
W"
W""
W""
W"
W"
W"
W'*
W""





Preliminary Sampling Cycle
Week
W"
W(ซ>
W"
W""
W"1
W"
w">
W""



W
W
W

W
W
W
W
W





1 Week 2
W




W
W
W



w(!"
W""
W""

W1"1
W""
W"11
W"'1
W1"1





Week3 ' Week 4
W




W
W
W



W
W
W

W
W
W
W
W





W




W
W
W



W
W
W

W
W
W
W
W





'
Week
W<"
W"ป
w!"
W!a)
W1"1
W!"
w"ป
W1*
w1"
w1"
W!"
W
W
W

W
W
W
W
w





Long-Term
Sampling Cycle

1 Week 2 Weeks Week 4
W




W
W
W



W""
W*1
w">

W""
W"
w"1
w""
w1"





W, Rw
R""
R"1


W, Rw
W, Rw
W, Rw
W, Rw
W, R1"
W, R"1
W
W
W

W
W, R""
W, R""
W, R("
W, R""





W




W
W
W



W
W
W

W
W
W
W
W





Sludge
Sampling
(Once)




















S
S
S
S
S
(a) = Duplicate samples collected and analyzed.
W = Water samples collected from the inlet, prefiltration, and after filtration locations.
R = Supernatant discharge water sample.
S = Sludge samples; three collected at Plant C.
Empty cells indicate no samples taken.
 3.3.3 Recycle Supernatant
       Water/Supernatant Discharge
       Sampling Procedure

 Figure 3-4 shows an instruction sheet for performing re-
 cycle backwash water and supernatant discharge sam-
 pling. Because both total and dissolved As, Al, Fe, and
 Mn were  analyzed, the  procedure for recycle superna-
 tant water/supernatant discharge sampling was similar to
 that for arsenic speciation, except that the steps for col-
 lecting samples in bottle C were omitted.

 3.3.4  Sampling Procedure for Other
       Water Quality Parameters

 All other water quality parameters identified in  Tables 3-3
 and 3-4, were analyzed using samples either in bottles A,
 B, and  C  or in bottles provided by Wilson  Environmental
 Laboratories  (i.e., bottles D, E,  F, and G).  All bottles D,
 E, F,  and G  were filled directly from  sample taps and
 preserved according to the respective analytical methods.
These  sample bottles along with bottles A, B, and C
were placed in the original  coolers  with ice packs and
shipped via Federal Express to Battelle.

3.4  Analytical Procedures

The  analytical procedures  used for this  project  were
described in  Section  4.0  of the QAPP  prepared by
Battelle (1998). Table 3-5  presents a summary  of all
analytical methods used. All of the methods used  are
standard EPA methods. Analyses of As, Al, Fe, and Mn
in water samples were accomplished  by ICP-MS  using
EPA Method 200.8. ICP-MS was chosen as the method
for As, Al, Fe, and Mn analyses because it had  a  low
method detection limit (MDL) and was a relatively low-
cost method (about $35/sample). ICP-MS analyses were
conducted on a Perkin Elmer Sciex Model 6000 equipped
with a  crossflow pneumatic  nebulizer and  an automatic
sampler. Yttrium (889Y) was  added to all samples  as an
internal standard to correct for instrument drift. Because
arsenic is monoisotopic, all measurements were made at
a mass/ charge ratio of 75.  To eliminate an appreciable
                                                    13

-------
                 Step 1:
                 Go to sampling point
                 (Inlet, Prefiltratfon, or Outlet)
                            Important Note;
                            DO NOT RINSE ANY BOTTLES!!
                            THEY CONTAIN PRESERVATIVES!!
                Step3;
                Collect water sample
                                   Preservative
                  a) Avoid agitation
     b) Fill bottle A
                             Step 4:
                             Prepare the syringe
              Fill and empty syringe to rinse
                StepS;
                Collect filtered sample
                                                                          Preservative
                                                                            (H2S04)
                                                                                                 B
                   a) Refill syringe
b) Attach filter to syringe
  and waste 10 drops
c) Fill bottle B
d) Cap tightly; shake (about 15 seconds)
                Step 6:
                Collect resin-treated sample
                                                            H;
                                                          A
                     a) Fill resin column from bottle B;
                       drain column to rinse; repeat
                       (waste approx. 40 mL)
                         Preservative
                                                               /
                                               b) Drain column into bottle C;
                                                  repeat (collect approx. 20 mL)
                                       Step 7:
                                       Fill in all blanks on chain-of-custody form
                                       Step 8:
                                       Pack and ship samples
                                                                    EPA14.CDR


                                      a) Tighten caps of all bottles   b) Tape cooler before shipping
Figure 3-3.  Instruction Sheet for Arsenic Field Speciation
                                                               14

-------
       Sfep 1:
       Go to recycle backwash water
       or supernatant discharge
       sampling point
   Sfep 2;
   Put on gloves
I m portant Note:
DO  NOT RINSE ANY BOTTLES!!
THEY CONTAIN PRESERVATIVES!!
        Step 3;
        Collect water sample
                          Preservative
                            (HN03)
          a) Avoid agitation
b) Fill bottle A
                       Sfep 4:
                       Prepare the syringe
          Fill and empty syringe to rinse
        Step 5;
        Collect filtered sample
                 a) Refill syringe
        b) Attach filter to syringe
          and waste 10 drops
                                                                                 inn*
                                                                                     /Preservative
                                                                                    I/  (HN03)
                   c) Fill bottle B
       Sfep 6:
       Fill in all blanks on chain-of-custody form
                    Sfep 7;
                    Pack and ship samples
                                                                    B
                                                           a) Tighten caps of      b) Tape cooler before shipping
                                                             all bottles
Figure 3-4.  Instruction Sheet for Recycle Supernatant Water/Supernatant Discharge Sampling
                                                      15

-------
Table 3-5.  Summary of Analytical Methods for Arsenic Treatment Study
Sample Matrix
Aqueous (Including samples collected at the
plant inlet, before the filtration process, after the
filtration process, and supernatant water from
sludge settling ponds/lagoons that was recycled
or discharged)






Sludge




Analyte
As (total)
Total Al
Total Fe
Total Mn
Alkalinity
PH
Turbidity
Hardness
so,2-
TOC
N03-/N02-
Water content
PH
TCLP metals
Total As
Total Fe
Method
EPA 200.8
EPA 200.8
EPA 200.8
EPA 200.8
EPA 310.1
EPA 150.1
EPA 180.1
EPA 215.1/242.1
EPA 375.4
EPA 415.1
EPA 353.2
ASTMD2216
SW-846 9045
SW-8461311
SW-846 305 1,6020
SW-846 305 1,6020
Analytical Laboratory
Battelle ICP/MS
Battelle ICP/MS
Battelle ICP/MS
Battelle ICP/MS
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
interference from a chloride molecular species (40Ar35CI),
all ion current data at m/e  75 were corrected  using
chloride measurements in all samples, and the MDL was
0.1 pg/L As. All the unfiltered water samples (i.e., in bot-
tle A) were digested using EPA Method 200.8 prior to
analysis. Filtered water samples (i.e., in bottles B and C)
were analyzed directly without digestion. Wilson Environ-
mental Laboratories  in  Westerville, OH, was subcon-
tracted to perform all other chemical analyses. QA/QC of
all methods followed the guidelines provided in the QAPP
(Battelle, 1998) and the data quality in  terms of preci-
sion, accuracy, MDL, and completeness is discussed in
Section 5.0 of this report.
                                                    16

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                                    4.  Results and Discussion
This section presents the results of the treatment plant
selection process, which resulted in the selection of two
coagulation/filtration plants, referred to as Plants A and
B, and one lime softening plant, referred to as Plant C. In
addition, results from  water and residuals sampling and
analysis at Plants A, B, and C are summarized and dis-
cussed. Complete analytical results from long-term water
sampling at Plants A, B, and  C are presented in Appen-
dices A, B, and C, respectively.

4.1  Plant Selection

The plant selection process consisted of identifying  po-
tential treatment facilities, contacting  these  facilities via
telephone, and conducting initial site visits during which
source water samples were collected and analyzed. Ini-
tially, a list was prepared consisting of six potential coag-
ulation/filtration treatment facilities and two  lime soften-
ing facilities. These potential candidate facilities were
contacted to discuss the study and determine details of
plant operation.  Each  facility  was  evaluated  and  as-
signed an  overall plant rating based, in order of impor-
tance, on  source water arsenic concentrations, source
water type, available manpower to conduct the year-long
study, availability of  historical arsenic  data, and plant
size. Selection was based primarily on source water ar-
senic concentrations, and preference was given to facili-
ties with  arsenic concentrations greater than 20 ug/L.
Another major consideration was the availability of man-
power, because the year-long study would require signi-
ficant resources. Also, it was desirable to have historical
arsenic analytical data, fairly large facilities (i.e., >20,000
                         people served), and to have a mix of plants using ground
                         water and/or surface water sources.

                         From the eight initial plants, three plants (two coagula-
                         tion/filtration and one lime softening)  were selected for
                         site visits and source water sampling (Plants A, B, and C
                         in Table 4-1). The same plants that were selected for the
                         initial site visits also were selected for the subsequent
                         phases of the study. Results from source water sampling
                         at each of the three facilities are presented in the sec-
                         tions that follow.

                         4.2  Plant A

                         Water and residual samples were collected and analyzed
                         at Plant A,  a-coagulation/filtration plant, during three
                         phases of the ptudy. The first phase consisted of source
                         water sampling used to help determine if the plant should
                         be considered:for additional phases. Source water sam-
                         pling at  Plant A was performed in February  1998.  Fol-
                         lowing source .water sampling, the second phase of the
                         study  was initiated. This second phase consisted  of
                         weekly water sampling for a 4-week period in April 1998
                         and  was designed to determine if the  sampling locations
                         and  proposed, water quality analyses were appropriate
                         for the third phase, long-term evaluation. The third phase
                         was initiated in June 1998 and continued through June
                         1999. This long-term evaluation consisted of weekly sam-
                         pling and analysis  of process  water  at three locations
                         throughout the treatment process. Also, arsenic speci-
                         ation sampling was conducted every fourth  week.  The
                         third phase of  the  study also included residual sample
 Table 4-1.  Initial List of Treatment Facilities Identified for the Study
Source Water Arsenic
Concentration, July 1994
Plant ID Process (ug/L)
A C/F
B C/F
C LS
NS
NS
33.2
Source Water Arsenic
Concentration, March 1995 Population
(ug/L) Served
66.9
33.2
52.5
2,500,000
65,000
: 35,000
Historical Data
Yes
Yes
Yes
Source
Water Type
SW
SW
GW
 C/F = coagulation/filtration.
 LS = lime softening.
GW = ground water.
SW = surface water.
                                                       NS = not sampled.
                                                      17

-------
 collection and analysis. Recycle supernatant water sam-
 ples from the settling pond were collected monthly begin-
 ning in November 1998, and three sludge samples were
 collected during a  single sampling  event from a  de-
 watered sludge pond.

 4.2.1  Plant A Description

 Plant A  began operation  in December 1986  and can
 treat up to  600 million gallons of water per day (mgd).
 However, based on discussions with plant personnel, the
 average plant  flowrate is approximately 420 mgd. This
 plant uses ozonation,  coupled with coagulation/filtration
 for water treatment. Figure 4-1 is a schematic diagram of
 the treatment process at Plant A.

 During treatment, the influent water is split into four treat-
 ment trains  immediately prior to ozonation and the trains
 are recombined prior to distribution. At the design flow-
 rate, the treatment process takes approximately 40 min-
 utes. Typically, it takes approximately 1 hour for raw
 water to be processed. The treatment process consists
 of the following major elements:

  •  Screening. The raw water is passed through a
     screen with a 2-inch mesh to remove debris.

  •  Ozonation. Ceramic diffusers are used to feed
     1.5 mg/L of ozone at the influent of the unit. There
     Is approximately a 5-minute contact time. Ozona-
     tion is used for disinfection and microflocculation
     to improve filtration and control taste and odor.
     The plant produces approximately 13,000 Ib/day
     of ozone with six generators.
  •  Rapid Mixing. 1 to 2 mg/L of ferric chloride and
     1 to 5 mg/L of cationic polymer are mixed with the
     water.

  •  Flocculation.  Flocculation occurs in three basins
     placed in series with approximately 8.5 minutes of
     contact time.

  •  Filtration. Filtration is accomplished with a high-
     rate filter (13.5 gpm/ft2). The filter media is anthra-
     cite coal (1.5 mm effective size) and a thin layer of
     pea gravel. Typically, backwashing occurs every 6
     to 40 hours  (average 20 hours) and the backwash
     water is sent to settling ponds. Supernatant water
     is fed into the water treatment plant influent. Back-
     washing accounts for approximately 2% of plant
     flow.

  •  Chlorination.  Chlorine is added during the treat-
     ment process for disinfection. The treatment plant
     chlorinates in order to maintain approximately
     2 mg/L of residual chlorine.

4.2.2 Initial Source Water Sampling

Source water for Plant A is  supplied  primarily via  an
aqueduct system that  carries  ground water and surface
water  runoff from the  Sierra Nevada  Mountains. This
water is collected and stored  in a series  of eight reser-
voirs. The aqueduct is enclosed  for 200  miles between
the last of the eight reservoirs and the water treatment
plant. Due in part to the high arsenic concentrations in
the source water, a water treatment facility was con-
structed in 1995 at the inlet of the  last reservoir. This
plant doses 3 to  7 mg/L of ferric  chloride  and a cationic
Screening     Ozonation
  Raw
  Water
 Rapid     Rapid
 Mixing   Mixing
Basin 1   Basin 2
           D
                                                               Flocculation
                          Filtration
                  D
                            Cationic n_
                            PolymerLb-J
                   Recycle Backwash Water
                                                                                                  Finished
                                                                                                  Water
                                                              >• Sludge to Hazardous Waste Facility
Figure 4-1.  Schematic Diagram of Plant A Treatment Process
                                                    18

-------
polymer  into the reservoir, which  is used  as a  large
settling basin. The reservoir is relatively effective at re-
moving arsenic. The long-term average arsenic concen-
tration in the source water prior to entering the reservoir
is approximately 25 ug/L and the reservoir effluent has
an average arsenic concentration of 8 to 10ug!/L The
reservoir treatment plant is not considered part of Plant A
and is not included in the sampling phases of this study.

An initial site visit to Plant A was conducted February 3,
1998, during which time source water samples were col-
lected. The total arsenic concentration during  the  initial
sampling  event was 10.4 ug/L.  Particulate arsenic ac-
counted for 2.4 ug/L of the total arsenic concentration,
and soluble arsenic, primarily arsenate, accounted for
the remaining 8.0 ug/L of the total arsenic. The particu-
late arsenic is probably attached to the iron, which was
detected at a concentration of 170 ug/L. The As(V) con-
centration  was 7.9 ug/L and  the As(lll)  concentration
was 0.1 ug/L, which is  consistent with  what would be
expected for a surface water source. Table 4-2 presents
the analytical results from the source water sampling.

Although the total arsenic in the source water at this plant
was below the desired concentration of 20 ug/L, it was
selected  for incorporation  into the preliminary sampling
and long-term evaluation phases. Selection of Plant A was
based on the very large size  and the availability of re-
sources at the facility to conduct the long-term sampling.

4.2.3 Preliminary Sampling

During the  preliminary  sampling phase of  this; study,
water samples were collected at three  locations within
the treatment iplant:  IN,  PF,  and AF. The IN samples
were collected from a tap located after  initial screening
and after the supernatant from the sludge settling lagoons
had been recycled. The PF and AF samples were col-
lected from sample taps located on treatment train two of
the four parallel  trains  at Plant A. The PF sampling tap
was located after flocculation and just prior to filtration.
The AF sampling tap was located after filtration and prior
to final chlorine addition and distribution. Figure 4-2 is a
process flowchart for Plant A that shows sampling loca-
tions within thp  treatment process  and the associated
sample analyses performed at each location.

Alkalinity, turbidity, pH, total  aluminum, total iron, total
manganese, TOC, and total arsenic analyses were per-
formed on samples collected each of the four weeks at
each of the three sampling locations. Arsenic speciation
was conducted  once during the preliminary  study  on
samples  collected from each sampling location. Soluble,
and particulate were determined as  part of the arsenic
speciation, as; well as  the species  (arsenite  and arse-
nate) making up the soluble fraction of the total arsenic.
Table 4-3 presents the results of the 4-week preliminary
sampling period.

Results from  the preliminary  sampling events indicated
that inlet  total, arsenic  concentrations ranged from ap-
proximately 12 to 17 ug/L. As found during the initial
source water sampling, the total arsenic in the source
water was primarily As(V) and contained only minor con-
centrations of ,As(lll) and  particulate arsenic. As  would
be expected,  the species of arsenic did not vary during
the treatment process. The average total arsenic remov-
al by Plant A  was approximately 48% during preliminary
Table 4-2.  Source Water Analytical Results at Plant A (February 3, 1998)
Parameter
Alkalinity
Sulfate
Turbidity
pH
Hardness
Ca Hardness
Mg Hardness
Total Al
Total Fe
Total Mn
NO3-NO2 (N)
TOC
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
Unit
mg/L"'
mg/L
NTU
—
mg/L""
mg/L"1
mg/L""
ug/L
ug/L
ug/L
mg/Llb)
mg/L
ug/L
ug/L
pg/L
ug/L
ug/L
Primary
Sample
98
44
0.67
8.1
104
74
29
<400
160
<20
0.12
1
11.1
7.3
3.8
ND
7.3
Duplicate
Sample
95
44:
0.68
8.1
93.5
65 ^
29
<400i
180;
<20:
0.13
2:
9.6
8.6
1.0
0.2
8.4
Average
Concentration
97
44
0.68
8.1
98.8
70
29
<400
170
<20
0.13
1.5
10.4
8.0
2.4
0.1
7.9
                (a) As CaCO3.
                (b) Combined NO3-N and NOa-N.
                ND = not detected.
                NTU = nephelometric turbidity units.
                                                     19

-------
WASTE LANDFILL
X">i As (total), water content,
(SSJ- —^- PH, TCLP metals
hi TT7TTT TIMf" TWMT4C! li
W olil 1JL1JNVJ JrAjINlJb t'
MONTHLY
As (dissolved and total),^. 	 ( 4 J
PH \_y
As (total), As (III), As (V) ^
Treatment Train
Cationic Polymer fe
FeCl fc
iCV-lj f
DA- PI

As (total), As (HI), As(V) ^.
Backwash Water
Asftotan.AsfIin.AsW <*. 	
INFLUENT
^f
RECYCLE
' BACKWASH WATER
T
SCREENING
1
A 	
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FLOCCULATION
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Plant A
Coagulation/Filtration
Design Flow: 600 mgd
WEEKLY
As (total), Alkalinity, pH,
.--^. TOC, Turbidity, Total Al,
Total Fe, Total Mn
LEGEND
0 Water Sampling
Location
ฎ Sludge Sampling
Location
DA- Cl Disinfectant Addition
2 Pmnt

FILTRATION Unit Process
Chemical Added to
FeC13 Unit Process

As (total), Alkalinity, pH,
s k .w TOC, Turbidity, Total Al,
^ ^ ^ Total Fe, Total Mn
r ir
FILTRATION
u


As (total), Alkalinity, pH,
__w. TOC, Turbidity, Total Al,
        NOTE:
        Four treatment trains operate in
        parallel at this plant These trains
        split immediately before ozonation
        and rccombine prior to distribution.
        Sample locations 2 and 3 are located in
        Treatment Train 2.
DA: C12

k-

i
ฑ_+
^
^
^
r ^
1
r
DISTRIBUTION
SYSTEM
                                                                                          Total Fe, Total Mn
Figure 4-2.   Process Flow Diagram and Sampling Locations at Plant A
                                                                20

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 sampling, reducing the finished water total arsenic con-
 centration to 6.1  to 9.5 ug/L. Plant A does not have a
 sedimentation step following flocculation; therefore, the
 majority of the arsenic removal occurred during filtration.
 The As(V) attaches to iron floes and is then  removed
 during filtration, which is why the PF sampling location
 consistently has higher total arsenic concentrations.

 McNeill and Edwards (1997a) developed the  following
 simplified  model for predicting arsenic  removal at  iron
 and alum coagulation facilities based on raw water Fe
 and Al concentrations:
    Arsenic Sorbed(%)=100x
 where K = 78 mM"
  Kx[Fe + AI]mM
(l + Kx[Fe + AI]mM)
(1)
 This model was based on data collected at over 14 full-
 scale facilities, and was able to accurately predict arse-
 nic  removal within  ฑ13% (90th  percentile  confidence
 interval). Applying this model to the preliminary results
 from Plant A, the predicted removal ranged between 51
 and 62% compared to actual removals ranging from 43
 to 52%. During the first sampling event, the actual  and
 predicted arsenic removal percentages were very close
 (51% predicted and 52% actual). However, a 19% differ-
 ence in arsenic removal was observed during the  last
 sampling event in which the calculated removal  was 62%
 and the actual removal was 43%.  Estimated arsenic
 removal percentages for  the other two sampling events
 were within ฑ13% of the actual removal observed. There-
 fore, the simplified  model appeared to approximate the
 arsenic removal at Plant A fairly well.

 Other water quality parameters were analyzed to support
 understanding of the mechanisms of arsenic  removal.
 TOO and  pH  concentrations were  relatively  constant
 throughout the treatment process during the preliminary
 sampling phase. Also, the pH was approximately 8.0 and
 in the range where no effect on arsenic removal efficien-
 cy using iron (III) salts has been observed in  previous
 studies (Sorg and Logsdon, 1978; Sorg,  1993; Hering et
 al., 1996).

 A slight decrease in alkalinity was observed  after  the
 addition of  the  ferric chloride  coagulant  (i.e., at the PF
 sampling location). This decrease in alkalinity is a result
 of a chemical reaction with ferric chloride:
          2FeCI3 + 3Ca(HCO3)2 -> 2Fe(OH)3i
                    3CaCI2 + 6CO2
                                                 (2)
Total  aluminum concentrations  were below detection
limits  at all three locations during each sampling event
 and were not considered to play a role in arsenic  re-
 moval; however, the detection limits were relatively high
 (400 |jg/L). Total manganese concentrations ranged from
 <20 to 70 ug/L in the inlet and <20 to 50 ug/L  in the
 outlet. The total iron  concentrations averaged 293 ug/L
 at the inlet, 980 ug/L at the prefiltration sampling loca-
 tion, and 63 ug/L at the after-filtration sampling location.
 The increase at the  prefiltration location is due  to the
 addition of FeCI3 as  a coagulant. The iron then is  re-
 moved in the filters. It appears that the primary arsenic
 removal mechanism at Plant A is adsorption and copre-
 cipitation of As(V) with the iron floes.

 Based on  the results  of the preliminary sampling effort,
 only minor changes were made to the approach for the
 long-term  evaluation. Sampling locations and  primary
 analytes remained unchanged. However, aluminum, iron,
 and manganese analysis was modified to achieve lower
 detection limits by using ICP-MS.  Also, it was  deter-
 mined that part of the sample in bottle B from the arsenic
 speciation kits would be  used to determine dissolved
 aluminum, iron, and manganese concentrations.

 4.2.4 Long-Term Sampling

 Long-term sampling and analysis consisted of 49 weeks
 of sampling with 12 arsenic speciation sampling events.
 During the long-term sampling phase of this study, water
 samples were collected at the same three locations that
 were used during the preliminary sampling phase:  IN,
 PF, and AF. Alkalinity, turbidity, pH, total aluminum, total
 iron, total manganese, TOG, and total arsenic analysis
 was performed on samples collected each week. Arsenic
 speciation sampling was conducted  12 times during the
 long-term sampling phase on samples  collected from
 each sampling location. Dissolved aluminum, iron, and
 manganese concentrations  at each sampling location
 were determined monthly using a sample from bottle B
 of the arsenic speciation kits. Additionally, residual sam-
 pling was performed during this phase and consisted  of
 collection and analysis of recycle supernatant water and
 sludge from the settling pond. The following subsections
 summarize the analytical results for arsenic, other water
 quality parameters,  and residuals. Figure 4-2 is a pro-
 cess flow diagram for Plant A that  indicates  sampling
 locations during the long-term evaluation and the analy-
 ses performed on samples from each location.

 4.2.4.1 Arsenic

Table 4-4 provides a summary of the arsenic  analytical
 results collected  at the three treatment process locations
at Plant A. Total arsenic concentrations  at  the inlet
 ranged from 2.6 ug/L to 12.1 ug/L with an average con-
centration of 7.5 ug/L.  These concentrations are slightly
 lower than  what was observed during the initial  source
water and  preliminary sampling  phases of this study.
                                                    22

-------
Table 4-4. Summary of Arsenic Analytical Results at Plant A (June 1998-June 1999)
Parameter
As (total)


As (total
soluble)

As
(particulate)

As(lll)


As(V)


Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
M9/L
Mg/L
M9/L
Pg/L
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
.pg/L
pg/L
pg/L
pg/L
Number of
Samples
49
49
48
VI
12!
12!
12!
12!
12!
12!
12!
12!
12!
12!
12!
Minimum
Concentration
2.6
2.0
0.8
5.1
2.7
2.0
<0.1
1.7
<0.1
0.3
<0.1
<0.1
4.8
2.2
1.6
Maximum
Concentration
12.1
23.4
6.0
10.9
6.0
! 4.8
1.9
7.8
0.5
2.0
2.1
1.9
10.2
5.4
: 4.3
Average
Concentration
7.5
8.7
3.5
7.7
4.3
3.5
0.5
4.3
0.2
0.7
0.6
0.6
6.9
3.6
3.0
Standard
Deviation
2.1
3.9
1.1
1.7
1.1
0.9
0.6
1.8
0.2
0.5
0.6
0.5
1.7
0.9
0.7
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
These results are due to a general trend of slightly high-
er arsenic concentrations that occur seasonally during
the months of February through July. Total arsenic con-
centrations at the PF sampling location ranged from 2.0
to 23.4 ug/L, with an average of 8.7 ug/L. Therefore, in
general, no reduction of arsenic was  observed between
the inlet and prefiltration sampling locations.  In fact, the
data indicated that a slight increase in total arsenic con-
centration occurred due to the formation of iron floes which
sorbed the arsenate. The floes accumulated just prior to
the filtration step where the  PF samples were collected.
Samples  collected  at the  after-filtration location con-
tained total arsenic concentrations ranging from 0.8 ug/L
to 6.0 ug/L with an average concentration of 3.5 ug/L.

The average removal percentage  of total  arsenic  be-
tween the inlet and after-filtration sampling locations was
53%. The average  arsenic removal  predicted by  the
McNeill and Edwards (1997a) sorption model was 43%,
which  is within the 90th percentile confidence interval of
the model. However, individual sampling events showed
differences in actual and predicted arsenic removals as
high as 63% and the  average  difference was approxi-
mately 20%,  which is outside of the 90th percentile confi-
dence interval for the model. The discrepancies between
the actual and predicted values may be due to tempera-
ture and competition for sorption sites by natural organic
matter (McNeill and Edwards, 1997a). Also, the  low
arsenic concentration  in the source  water  (average
7.5 ug/L)  likely contributed  to the discrepancy between
the predicted and actual removal efficiencies. However,
it appears that the difference is not a result of iron  floe
passing through the filter because the particulate arsenic
and total  iron concentrations at the outlet are very low.
Figure 4-3 is a graph showing the total arsenic concen-
tration recorded at  each sampling  location throughout
the study, as well as removal percentages calculated for
each sampling 'event.

Particulate arsenic concentrations averaged 0.5 ug/L at
the inlet, 4.3 ug/L at the prefiltration sampling location,
and 0.2 ug/L at the after-filtration sampling location. The
increase of particulate arsenic at the  prefiltration sam-
pling location is due to sorption  and coprecipitation of
arsenic on/with the iron floes formed. This observation is
supported by the decrease of particulate arsenic in the
after-filtration sampling location.

As(lll) and As(V) make up the soluble portion of the total
arsenic concentration. Throughout the duration  of the
study and at each sampling location, As(V) made up the
majority of  the soluble arsenic.  As(lll)  concentrations
averaged 0.7 ug/L at the inlet, 0.6 ug/L at the prefiltration
location, and 0.6 ug/L at the after-filtration location, indi-
cating that As(lll) was not removed by the treatment pro-
cess. Although the  As(lll) concentrations were low, no
apparent conversion to As(V) was observed after ozona-
tion. Average As(V) concentrations were 6.9 ug/L at the
inlet, 3.6 ug/L at the prefiltration location,  and 3.0 ug/L at
the after-filtration location. The As(V) concentration de-
creased at the prefiltration location due to coprecipita-
tion/adsorption of the arsenic with iron floes. This result
correlates with the increase in particulate arsenic at this
same location. The arsenic  that was not removed with
the coagulant  passes through the system. Figure 4-4
provides charts showing the fractions of the total arsenic
concentration made up by  particulate arsenic,  As(lll),
and As(V) throughout the long-term evaluation.

The Plant A water treatment system was  able to con-
sistently remove arsenic to low levels (i.e., average
treated water total arsenic  concentration  is  3.5 ug/L).
                                                     23

-------
                                                                                  90%
                                                                                  -10%
       6/4/98     7/24/98    9/12/98    11/1/98   12/21/98    2/9/99     3/31/99    5/20/99     7/9/99
                                            Date

Figure 4-3. Total Arsenic Analytical Results During Long-Term Sampling at Plant A
The primary arsenic removal mechanism appears to be
coprecipitation/adsorption with iron floes followed by filtra-
tion. The simplified sorption model developed by McNeill
and Edwards (1997a) appears to approximate the arse-
nic removal process at Plant A reasonably well, although
discrepancies were noted.


4.2.4.2  Other Water Quality Parameters

In addition to arsenic analysis, other water quality param-
eters were analyzed to provide insight into the  chemical
processes occurring at the treatment facility. Table 4-5
summarizes the analytical results for several water qual-
ity parameters obtained during the long-term sampling at
Plant A.

Alkalinity concentrations ranged from 45 mg/L to 112 mg/L
(as CaCO3) in the inlet with an average of 89 mg/L. The
analytical data  indicated seasonal variations in alkalinity
concentrations,  with a dip occurring during July and
August. This dip correlated with the snow melt in the
Sierra  Nevada mountains, which resulted  in  a  higher
percentage of the source water coming from lower-alka-
linity melted snow. However, these data did not appear
to correlate with arsenic analytical results or removal effi-
ciencies at Plant A. Figure 4-5 plots the inlet alkalinity,
turbidity,  pH, and TOG  concentrations throughout the
duration of the study.
During long-term sampling, turbidity concentrations aver-
aged  1.2 NTU  at the inlet,  1.8 NTU at the prefiltration
location, and <0.1 NTU at the after-filtration location. As
seen in Figure 4-5, spikes in the inlet turbidity concentra-
tions were observed during the study and are most likely
due to precipitation events that increase suspended sol-
ids in the source water. The ferric chloride dosages are
adjusted to account for the  varying turbidity concentra-
tions. The data show that Plant A effectively removes tur-
bidity from the source water, although no correlation was
observed regarding arsenic removal efficiency.

The average pH was 8.0 at the inlet, 7.9 just prior  to
filtration, and 7.8 in the finished water. These pH values
are in the range (pH 5.5 to  8.5) where arsenic removal
efficiency by iron oxides is not affected (Sorg, 1993). On
March 24, 1999, a pH of 5.2 was reported; however, this
figure is considered to be an outlier because plant oper-
ational data did not indicate any change in pH. TOC con-
centrations also were relatively constant, with averages of
2.4 mg/L, 2.7 mg/L, and 2.4 mg/L, at the inlet, prefiltration,
and after-filtration sampling  locations,  respectively. TOC
does not appear to impact arsenic removal efficiency.

Total  iron concentrations  at the inlet  sampling location
ranged from <30 to 767 ug/L and averaged 146 ug/L.  At
the prefiltration sampling location, total iron concentrations
ranged from  <30 to 2,646 ug/L and averaged  642 ug/L.
                                                     24

-------
        Inlet
                                   14



                                   12 .



                                - 10
                                o   4.
                                    2 -
                                   14
        Prefiltration
                                   12 -
                                 T 10 .
                                 5  4
                                    2 -
                                          *
        After Filtration
  14



  12




3- 10



T  8
_o

ซ

ฃ  6
O
o


I  4



   2



   0




  -\>
                                            Q
Figure 4-4.  Arsenic Form and Species Analytical Results During Long-Term Sampling at Plant A
                                                     25

-------
 Table 4-5.  Summary of Water Quality Parameter Analytical Results at Plant A (June 1998-June 1999)
Parameter
Alkalinity


Turbidity


pH


TOC


Total Al


Total Fe


Total Mn


Dissolved Al


Dissolved Fe


Dissolved Mn

;,'
Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiitration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
mg/L
mg/L
mg/L
NTU
NTU
NTU
—
—
—
mg/L
mg/L
mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
MQ/L
Mg/L
Mg/L
(jg/L
Mg/L
pg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Number of
Samples
48
48
48
48
48
48
48
48
48
47
48
48
49
49
49
49
49
49
49
49
49
12
12
12
12
12
12
12
12
12
Minimum
Concentration
45
43
42
0.3
0.4
<0.1
5.2
7.5
7.4
1.5
<1.0
1.5
<11
18.2
<11
<30
<30
<30
4.4
8.9
<0.5
<11
<11
<11
<30
<30
<30
1.1
1.4
<0.5
Maximum
Concentration
112
111
109
5.5
18.5
0.2
8.3
8.1
8.0
4.8
12.0
7.4
717
246
39
767
2,646
63.8
112
85.5
45.4
22.6
<11
18
45.7
<30
<30
10.8
69.7
5.8
Average
Concentration
89
88
87
1.2
1.8
<0.1
8.0
7.9
7.8
2.4
2.7
2.4
68
64
12
146
642
<30
20.9
27.1
4.7
<11
<11
<11
<30
<30
<30
3.1
8.7
2.3
Standard
Deviation
20.7
20.6
20.5
1.0
2.7
0.04
0.4
0.1
0.2
0.6
1.5
0.9
104.2
48.8
7.6
175.1
474.5
14'7
20.0
17.0
7.2
4.9
NA
3.7
8.9
NA
NA
2.6
19.2
2.3
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
The total iron concentration increased at the prefiltration
location due to the addition of FeCI3 as a coagulant. The
average total  iron concentration  at  the  after-filtration
sampling location was <30 ug/L. Also, average dissolved
iron cqncentrations were below the detection limit at the
inlet, prefiltration,  and after-filtration sampling locations.
As stated previously, iron is the key factor  in arsenic
removal at Plant A. It is believed that the majority of the
arsenic removal is through adsorption and coprecipita-
tion of As(V) with iron hydroxides.

Total aluminum concentrations averaged 68 ug/L  at the
Inlet, 64 ug/L at the prefiitration location, and  12 pg/L at
the after-filtration location.  The average dissolved alum-
inum concentration at all three locations was less than
the detection limit. It  did not appear that coprecipitation
with aluminum, hydroxide was a significant factor  in  the
removal of arsenic at Plant A, because minor concentra-
tions were present and almost all of the aluminum was in
the paniculate form at the inlet.

Total  manganese concentrations  averaged  20.9 ug/L,
27.1 ug/L, and 4.7  ug/L, at the inlet, prefiltration, and after-
filtration sampling  locations, respectively. Average dis-
solved manganese concentrations were 3.1 ug/L at the
inlet, 8.7 ug/L at the prefiltration location, and 2.3 ug/L at
the after-filtration location.

4.2.4.3  Recycle Supernatant Water

Approximately 2% of the total flow at Plant A is used for
backwashing filters. The filter backwash water then is
sent to  a sludge settling pond and the supernatant is
recycled. The supernatant water is added continuously
to the source water and processed at the facility. Super-
natant samples were collected from a sample tap in the
piping that transports the water from the sludge settling
pond to the source water  inlet.  Results of  supernatant
sampling are summarized in Table 4-6.

The soluble  arsenic concentrations are  approximately
equal to those measured in the source water; however,
the particulate arsenic is approximately 3.0 ug/L higher
on average. This result would  be expected because the
backwash water contains some  unsettled iron solids, which
most likely contain sorbed arsenic. The low dissolved iron
concentrations observed during  the study support this
assumption. Based on  these results, it does not appear
                                                     26
                                                                               it • • t

-------
        ฃ

        1  3
                                                                       -• 100
                                                                        80 „
                                                                           I

                                                                        60 c
                                                                           0
               -  40
                                                                       . 20
                          -Turbidity (NTU)
                          -pH (units)
                          -TOG (mg/L)
                          -Alkalinity (mg/L as CaCO3)
           6/4/98    7/24/98   9/12/98    11/1/98  12/21/98   2/9/99   3/31/99   5/20/99   7/9/99
                                         Date

Figure 4-5.  Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at Plant A
that the recycle backwash water would impact the treat-
ment process either positively or negatively.

4.2.4.4  Sludge
Sludge  is generated at Plant A from backwashing the
anthracite coal/pea gravel filters. Typically, backwashing
occurs every 6 to 40 hours (average 20 hours) and the
backwash water is sent to settling ponds. Supernatant
water from the settling ponds is recycled into plant influent.
Approximately 2% of plant flow is used for backwashing.

Approximately once per year, or as required, the settling
ponds are drained and the sludge is removed. Approxi-
mately 18,000 tons of sludge are removed per year. The
sludge is considered California  hazardous waste due to
elevated concentrations of arsenic and copper based on
exceedances of regulatory levels for the soluble thresh-
old limit concentration (STLC). Total arsenic  and TCLP
results have  not exceeded regulatory levels  for classi-
fication  as California hazardous waste.  Table 4-7 con-
tains analytical results from sludge sampling  conducted
during three sampling events at Plant A in October 1996,
March 1997, and May 1997.

During the long-term evaluation phase, sludge  samples
were collected on December 2, 1998, from three locations
within a dewatered sludge pond. These sludge  samples
were analyzed,for pH, percent moisture, total arsenic, and
total iron. Also, a TCLP test was  performed on  each
sample to determine the quantities of  leachable arsenic,
Table 4-6. Summary of Analytical Results from Recycle Backwash Water Samples at Plant A
           (November 11, 1998-June 16,1999)
Parameter
As (total)
As (soluble)
As (particulate)
PH
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Number of
Units Sample Events
pg/L
pg/L
M9/U
—
ug/L
M9/L
M9/L
P9/L
pg/L
pg/L
8
8
8
7
8
8
8
8
8
8
Minimum
Concentration
3.7
3.8
<0.1
7.6
<11
174
52.8
<11
<30
33.2
Maximum
Concentration :
19.7
10.9
11.7
7.9
113
1367
572
<11
127
235
Average
Concentration
10.2
7.1
3.2
7.8
47
535
169
<11
37.9
78.3
Standard
Deviation
5.1
2.6
4.1
0.1
44
420
174
NA
39.3
67.0
                                                     27

-------
Table 4-7.  Previous Analytical Results of Sludge Sampling at Plant A (1996-1997)
                    Analyte
Description
October 1996   March 1997   May 1997
Total Arsenic




Arsenic-STLC




Arsenic-TCLP



	
Number of samples
Minimum concentration (mg/kg)
Maximum concentration (mg/kg)
80% UCL concentration (mg/kg)
Regulatory level (mg/kg)
Number of samples
Minimum concentration (mg/L)
Maximum concentration (mg/L)
80% UCL concentration (mg/L)
Regulatory level (mg/L)
Number of samples
Minimum concentration (mg/L)
Maximum concentration (mg/L)
80% UCL concentration (mg/L)
Regulatory level (mg/L)
10
110
740
418
500
10
4.1
37
22
5
10
<0.2
<0.2
NA
5
10
73
370
265
500
10
5
21
15
5
10
<0.2
0.3
NA
5
10
110
210
180
500
10
9.5
15
13
5
10
<0.2
0.3
NA
5
                UCL = upper confidence level.
barium, cadmium, chromium, lead, mercury.selenium, and
silver. The sample collected from location 2 did not have
the same appearance as the samples from  locations  1
and 3. It was reported to look more like soil than dried
sludge. This difference in appearance probably accounts
for the differences in measured arsenic and iron concen-
trations between the location 2 sample and the samples
from locations 1 and  3. Assuming that the samples col-
lected from locations 1 and 3 are more representative of
the sludge produced by Plant A,  total arsenic concen-
trations were 806  and 880 mg/kg dry, respectively, and
total iron concentrations were 83,200 and 95,000 mg/kg
dry, respectively. These total arsenic concentrations  ex-
ceed the regulatory levels for total arsenic in  California,
which would classify this sludge  as hazardous  waste.
Arsenic was detected in  one sample leachate at  a con-
centration of 0.106 mg/L, which was well below the regu-
latory limit of 5 mg/L. Table 4-8 presents the results of
sludge analysis at each of the three sampling locations.
                 4.3  Plant B

                 Water and residual samples were collected and analyzed
                 at Plant B,  a coagulation/filtration  plant, during three
                 phases  of the study: source water sampling, preliminary
                 sampling, and long-term evaluation. Source  water sam-
                 pling at Plants was performed in February 1998. Pre-
                 liminary sampling consisted of weekly water sampling for
                 a 4-week period in April/May 1998 and was designed to
                 determine if the sampling  locations and proposed water
                 quality analysis were appropriate for the third phase, long-
                 term evaluation. The third phase was initiated in June
                 1998 and continued through June 1999. Arsenic specia-
                 tion sampling was conducted every fourth week. The third
                 phase of this study also included residual sample collec-
                 tion and analysis. Supernatant water  samples from the
                 settling tank were collected monthly beginning in Novem-
                 ber 1998, and three sludge samples were collected during
                 a single sampling event from a dewatered sludge lagoon.
Table 4-8. Analytical Results of Sludge Sampling at Plant A (December 2,1998)
                     Parameter
                                    Unit
                                             DL
                                                     Location 1
                                                                  Location 2
                                                                                Location 3
As-TCLP
Ba-TCLP
Cd-TCLP
Cr-TCLP
Pb-TCLP
Hg-TCLP
Se-TCLP
Ag-TCLP
TCLP extraction
PH
Percent moisture
Total As
Total Fe
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NA
—
%
mg/kg, dry
mg/kg, dry
0.05
1.0
0.020
0.030
0.50
0.0002
0.05
0.020
NA
—
0.1
2.0
1,370
0.106
1.1
<0.020
<0.030
<0.50
<0.0002
<0.050
<0.020
Complete
7.0
31.6
806
83,200
<0.05
1.1
<0.020
<0.030
<0.50
<6.0002
<0.050
<0.020
Complete
8.1
14.6
9.0""
17,600
<0.05
<1.0
<0.020
<0.030
<0.50
<0.0002
<0.050
<0.020
Complete
7.2
" 38.6
880
95,000
                   (a) Confirmed by sample re-analysis. The sample looked like soil instead of dry sludge.
                   DL = Detection limit.
                                                     28

-------
4.3.1  Plant B Description

Plant B is used to treat surface water for a population of
approximately 65,000. The plant processes 6 to 8 mgd
during the winter months and 30 to  35 mgd during  the
summer. The design flowrate is 62.5 mgd. The plant uti-
lizes coagulation, sedimentation, and filtration for water
treatment. Figure 4-6 is a schematic diagram of the treat-
ment process used at Plant B.

The treatment process at Plant B consists of the follow-
ing major elements:

  • Screening. Screening is required to remove
    debris from the raw water at the river intake.

  • Pre-Chlorination. Approximately 3 to 4 mg/L of
    chlorine is added  to the raw water for disinfection
    and to provide residual chlorine for the distribution
    system.

  • Rapid Mixing. Depending on influent turbidity,
    25 to 30 mg/L of alum is added to the water. Also,
    0.75 mg/L Cat Floc-TL polymer is used when
    water temperature is less than 10ฐC, typically
    October through April. Jar testing conducted by
    the treatment plant was used to develop relation-
    ships for estimating alum dosage based on
    influent turbidity.

  •  Flocculation. Flocculation of alum hydroxide and
    various contaminants, including arsenic, occurs
                     during this treatment process. During late
                     summer, powdered activated carbon (PAC) may
                     be added for taste and odor control.

                  ซ  Sedimentation. Sedimentation of floes occurs in
                     primary and secondary clarifiers.

                  •  Filtration.  Additional solids removal is accom-
                     plished through filtration. Filtering is accomplished
                     with a dual media consisting of anthracite and
                     sand. Backwashing occurs approximately every
                     50 hours.

                  •  Clean/veil Storage.  Ammonia is added prior to
                     clean/veil storage to form monochloramine. No
                     posttreatment chlorination is performed.

                  •  Backwash. Backwashing occurs approximately
                     every 50 hours. The sludge eventually is sent to a
                     landfill and the supernatant water from the sludge
                     lagoon is discharged to the Missouri River under a
                     state permit.

                 4.3.2 Initial Source Water Sampling

                 Plants  influent water is  supplied from the  Missouri
                 River. Based on discussions with plant personnel,  the
                 turbidity ranges from 2 to 3  NTU  in the winter and  be-
                 tween 10  and 100 NTU during  the spring and summer
                 due to snow melt and rain. The primary source of arse-
                 nic in the source water is believed to come from  the
                 Yellowstone Basin that  drains into the Madison River,
                 the largest tributary of the Missouri River. Historically,
       Raw Water-
         from
         River
                               Rapid Mixing    Flocculation
                                                                   Sedimentation
                                                                                        Filtration
                   AI2(S04)3|-L,
                    [Alum]  Lb-1

                      PolymerPT_
Sanitary.^.
 Sewer
                                                 uuy
1

I

Settling
Tank


Backwash W
ater
Cle
Stc
                                        Supernatant Water
                                       Discharged to the River
                                                 Sludge Lagoon
              Explanation

         PAC Powdered Activated Carbon
              (Only used during summer for taste and odor control)
                                                afHj	^
                                                      Finished
                                                       Water
                                 >• Sludge to Landfill
 Figure 4-6.  Schematic Diagram, Plant B
                                                     29

-------
 arsenic concentrations in the source water have ranged
 from 16 to 25 ug/L.

 An initial site visit tp Plant B was conducted on February
 5, 1998, during which time source water samples were
 collected. During this sampling event, samples were col-
 lected and analyzed for arsenic (total, particulate, soluble,
 AsfJII], As[V]) and various other water quality parameters
 that may affect arsenic removal.  Table 4-9 presents the
 analytical results  from the source water sampling. The
 total arsenic concentration in the source water averaged
 21.2 ug/L.  Particulate arsenic averaged  1.4 ug/L of the
 total, and all of the soluble arsenic was As(V). The inlet
 iron concentration averaged 2,790 ug/L, which was rela-
 tively high and  did not correlate  well with the total iron
 data collected during the preliminary sampling and long-
 term  evaluation phases. Aluminum concentrations were
 less than the detection limit, and manganese concen-
 trations were 30 ug/L.

 Alkalinity concentrations averaged 122 mg/L (as CaCO3)
 and total hardness concentrations averaged 281.5 mg/L
 (as CaCOa). Therefore, the source water would be clas-
 sified as hard.  Based on discussions with plant person-
 nel, turbidity concentrations are typically in the range of
 2 to 3 NJU in the Winter, Consistent with this information,
 turbidity concentrations were relatively low during the
 source water sampling event conducted in  February, aver-
 aging 1.1 NTU. The pH averaged 8.2, which is relatively
 high for effective arsenic removal using alum (Sorg and
 Logsdon, 1978; Sorg, 1993).

 4.3.3 Preliminary Sampling

Water samples collected during the preliminary sampling
phase of this study were taken at three locations within
 the treatment plant: (1) the IN; (2) PF; and (3) AF. The
 IN and PF sampling locations were open channels trans-
 porting the raw and partially treated water to the various
 treatment  processes in  the  plant.  Therefore,  a scoop
 was used  to take grab samples at  IN and PF sampling
 locations. The IN sample was collected from a channel
 immediately following  initial screening. The PF sample
 was collected from the channel  located after rapid mix-
 ing, flocculation and sedimentation. A sink facet located
 in the plant was used  as the AF sampling location and
 represents the finished  water entering the distribution
 system. Figure 4-7 is a process flow diagram for Plant B
 that shows sampling locations used during the prelimi-
 nary  sampling, as  well as the analyses  performed  on
 samples collected from each location.

 Alkalinity,  turbidity, pH, total aluminum, total iron, total
 manganese, TOC,  and total  arsenic analysis  was per-
 formed on  all  water samples collected at Plant B. Arse-
 nic speciation  sampling was conducted at each sampling
 location once  during the preliminary study. Arsenic form
 (soluble and  particulate) and  species (arsenate and
 arsenite) were determined as part of the arsenic specia-
 tion. Table 4-10 presents the results of the 4-week pre-
 liminary sampling period.

 Results from the  preliminary sampling events  indicated
 that inlet total arsenic  concentrations ranged  from ap-
 proximately 20.9 to 23.3 ug/L. The  total  arsenic in the
 source water was primarily As(V) and contained only mi-
 nor concentrations of As(lll) and particulate arsenic. As
would be expected, the species  of arsenic did not vary
significantly during the  treatment process. The average
total arsenic removal by Plant B was approximately 86%
during preliminary sampling. In general, the majority of the
arsenic removal occurred during sedimentation  (average
Table 4-9.  Source Water Analytical Results at Plant B (February 5,1998)

Parameter
Alkalinity
Sulfate
Turbidity
PH
Hardness
Ca Hardness
Mg Hardness
Total Al
Total Fe
Total Mn
NCy-NO2 (N)
TOC
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
(a) AsCaCO3.

Units
mg/L("
mg/L
NTU
—
mg/Lw
mg/L1"
mg/L"1
Mg/L
Mg/L
Mg/L
mg/L1"
mg/L
Mg/L
ug/L
M9/L
M9/L
Mg/L

Primary
Sample
122
38
1.08
8.2
286
147
138
<400
2,780
30
0.23
3
22.5
20.3
2.2
<0.1
20.3

Duplicate
Sample
122
37
1.11
8.2
277
140
138
<400
2,800
30
0.22
3
20.0
19.3
0.7
<0.1
19.3

Average
Concentration
122
37.5
1.095
8.2
281.5
143.5
138
<400
2,790
30
0.22
3
21.2
19.8
1.4
<0.1
19.8

(b) Combined NO3-N and NO2-N.
                                                    30

-------
            MONTHLY
       As (total), As (III), As (V)

       As (total), Water Content,
       pH, TCLP metals

As (dissolved and total), ^-
pH
       SUPERNATANT WATER
          DISCHARGED TO
          MISSOURI RIVER
                 SETTLING
                   TANK
                 SETTLING
                  LAGOON
              SLUDGE SENT TO
                 LANDFILL

             As (total), As (III), As (V)
         Backwash Water
             As (total), As (III), As (V)

                            NH3
                                             FLAPID MIXING
                                                  BASIN
                                            FLOCCULATION
                                                PRIMARY
                                              CLARIFIER (5)
                                              SECONDARY
                                              CLARIFIER (2)
                                              FILTRATION
                                             DISTRIBUTION
                                                 SYSTEM
                                                                                  Plant B

                                                                             Coagulation/Filtration
                                                                            Design Flow: 62.5 mgd
                                                                               WEEKLY
                                                                            As (total), Alkalinity, pH,
                                                                            TOC, Turbidity, Total Al,
                                                                            Total Fe, Total Mn
A12(S04)3

Cat Floc-TL Polymer
                                                                                  LEGEND
  o
                                                                          A12(S04)3
                                                                                  Water Sampling
                                                                                  Location

                                                                                  Sludge Sampling
                                                                                  Location

                                                                                  Disinfectant Addition
                                                                                  Point

                                                                                  Unit Process

                                                                                  Chemical Added to
                                                                                  Unit Process
As (total), Alkalinity, pH,
TOC, Turbidity, Total Al,
Total Fe, Total Mn
As (total), Alkalinity, pH,
TOC, Turbidity, Total Al,
Total Fe, Total Mn
Figure 4-7.   Process Flow Diagram and Sampling Locations at Plant B
                                                      31

-------
 CO
 2L     c
 ^     o

 >•    "ni
 &     IS
 co
 CM
 Q.
D.
 I-
 0)
JQ
.OS
                                                     CO    O)
                                                     CO    
-------
75%). Additional arsenic removal occurred during filtra-
tion to achieve the 86% average removal, leaving only
2.4 to 4.2 ug/L in the finished water.

Very good correlation with the sorption model proposed
by McNeill and  Edwards  (1997a) was observed. Pre-
dicted  arsenic removal ranged  between  89 and 91%,
while actual removals ranged between 82 and 89%. The
largest deviation between the predicted and actual arse-
nic removal was 10%, which is within the 90th percentile
confidence interval of the model. Therefore, this simpli-
fied sorption model appeared to approximate the system
performance and was used in evaluating long-term data.

Other water quality parameters were analyzed to support
understanding of the mechanisms of arsenic removal.
TOC concentrations were relatively constant (i.e., 3 mg/L)
throughout the treatment process, indicating no signifi-
cant TOC removal by the  plant. Similar to Plant A, the
lack of TOC removal does not appear to impact arsenic
removal.

During alum  coagulation, the alum  reacts with natural
alkalinity to form aluminum hydroxide:
     AI2(SO>14.3H20 + Ca(HCO3) -> 2AI(OH)3

           + 3CaSO4 + 14.3H2O +6CO2
(3)
Therefore, alkalinity concentrations and pH values de-
creased  between  the  inlet  and  prefiltration  sampling
locations. Average alkalinity concentrations decreased
from 132 to  111  mg/L (as CaCO3) and  average pH val-
ues decreased from 8.6 to 7.5. The alkalinity and pH then
remained constant between the prefiltration and after-
filtration sampling locations. Turbidity concentrations aver-
aged  5.6 NTU during the preliminary sampling phase.
These turbidity values are almost 6 times higher than the
values observed during the preliminary sampling  event;
however, this would be expected due to snow melt and
precipitation during the spring months.

Total  aluminum  concentrations ranged between <400
and 680 ug/L in the inlet and between 500 and 600 ug/L
in the prefiltration location. Total aluminum was less than
detection during all four sampling events at the after-
filtration  sampling  location.  An increase in aluminum
concentration due to the addition of alum is not observed
at the prefiltration sampling location because it is located
after sedimentation. However, based on plant alum dos-
age data, the calculated aluminum concentration avail-
able for coagulation ranged between 2.5 and  4..1 mg/L.
Total  manganese  concentrations  ranged from  40 to
90 ug/L in the inlet and <20 to 50 ug/L in the prefiltration
and after-filtration locations. The total iron concentrations
averaged 460 ug/L at the inlet, 44 ug/L at the prefiltration
sampling  location, and <30 ug/L at the after-filtration
sampling location. The inlet iron concentrations were sig-
nificantly lower than the concentration  obtained during
the source water sampling event and consistent with the
concentrations: observed during the  long-term evalua-
tion phase.  It appears that arsenic removal is primarily
achieved through adsorption and coprecipitation of As(V)
with the aluminum floes formed from the alum coagulant
and the iron in the source water.

Based on the results of the preliminary sampling effort,
only minor changes were made to the approach for the
long-term evaluation. As with Plant A, sampling locations
and primary  analytes remained  unchanged;  however,
aluminum, iron, and manganese analyses were modified
to ICP-MS. Also, part of the sample in bottle B from the
arsenic speciaiion kits was used to determine  dissolved
aluminum, iron, and manganese concentrations.


4.3.4 Long-Term Sampling

Long-term sampling and analysis consisted of 49 weeks
of water sampling at the same three locations used dur-
ing the preliminary sampling phase. All  weekly samples
were  analyzed  for alkalinity, turbidity,  pH, total alumi-
num, total iron, total manganese, TOC, and total arsenic.
Arsenic speciation sampling was conducted at each sam-
pling  location ;12  times during the long-term  sampling
phase on samples collected from each sampling location
and included determination of dissolved aluminum, iron,
and manganese concentrations. Supernatant discharge
water and sludge sampling and analysis also was per-
formed during this phase. The following subsections sum-
marize the arsenic, other water quality parameters,  and
residuals analytical results.

4.3.4.1 Arsenic
Table 4-11 provides a summary of the arsenic  analytical
results collected at the three sampling locations. Total
arsenic concentrations at  the  inlet  ranged from 15 to
23.9 ug/L with, an  average  concentration of 19.1 ug/L.
These arsenic concentrations correspond well with the
historical data collected by the plant where total arsenic
concentrations have  ranged from 16 to 25 ug/L. Total
arsenic concentrations at the prefiltration location ranged
from 3.0 to 15.5 ug/L with an average of 6.4 ug/L. There-
fore, an average arsenic removal  rate of 66% occurred
prior to filtration in the sedimentation basins. Samples
collected after-filtration location contained total arsenic
concentrations  ranging from 1.5 to 11.8 ug/L with  an
average concentration of 4.0 ug/L. The average removal
percentage of'total arsenic  (comparing raw water  and
finished water concentrations) was 79%. These removal
percentages were calculated based on an average of all
total arsenic data collected during the  long-term evalu-
ation, including the 6-week period when a polyaluminum
                                                    33

-------
• 	 ': • ":i;


Table 4-11.

•IfUII, „' , '


Summary of Arsenic
, ,jj.j 	 ni i "
^nj,,,,, 	
Parameter Sample Location
As (total)


As
(total soluble)

As
(particulate)
	
As(lll)


As{V)

..,i,,i
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
' Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet 	
Prefiltration
After filtration


Analytical


Units
pg/L
pg/L
P9/L
Pg/L
PS/L
Pg/L
pg/L
pg/L
pg/L
Pg/L
pg/L
pg/L
pg/t-
M9/L
P9/L


Results at Plant
,i
Number of
Samples
49
49
49
12
12
12
12
12
12
12
12
12
12
12
12


" ,
111 ' ':

"
,l! !' i ' II'!1
-il !'!'•
B (June 1998-June 1999)

Minimum
Concentration
15
3.0
1.5
18.3
2.1
2.2
<0.1
0.6
<0.1
0.1
<0.1
<0.1
17.9
1.8
1.9
E(, ' ,'!]• i
Maximum
Concentration
23.9
15.5
11.8
23.0
12.1
12.5
0.6
4.5
0.3
i 	 ' !
1.2
1.2
0.8
21.8
11.8
12.1

Average
Concentration
19.1
6.4
4.0
20.3
4.3
4.6
0.2
2.6
<0.1
0.6
0.4
0.4
19.7
3.9
4.2
1 " ']• *!:'" !;
Standard
Deviation
2.4 	
2.7
2.7
1.3 	 "
3.1
3.2
0.2
1.2
0.1
1 . , t si
0.3
0.3
0.2
1.2 	
3.2
3.3
pne-hajf of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculation.
chloride coagulant was used instead of alum. The  re-
moval efficiencies observed during the long-term evalu-
ation correspond well with the removal percentages ob-
served during the preliminary sampling phase (75% and
86% arsenic removal achieved  at the PF and AF sam-
pling locations,  respectively).  Figure 4-8 is a graph
showing the total arsenic concentration recorded at each
sampling location throughout the study.
      iij	 ,.,  '(i(i '  I'jjjii;1,! . • ,     , '.     .    "   „ •     :
Particulate arsenic concentrations averaged 0.2 ug/L at
the  inlet, 2.6 ug/L at the prefiltration sampling location,
and <0.1 ug/L at the after-filtration sampling location. The
increase of particulate  arsenic  at the prefiltration sam-
pling location  was attributed to  the sorption and copre-
clpitation of the arsenic and the  aluminum floes. The de-
crease of particulate arsenic in the after-filtration sam-
pling location supports this observation. The low levels of
particuiate arsenic at the after-filtration location indicated
that the  system  effectively removes arsenic sorbed to
metal floes.

As(lll) and As(V)  make  up the soluble portion of the total
arsenic concentration.  Throughout the duration of the
study and at each 'sampling location, As(V) made up the
majority  of the soluble arsenic, averaging  97, 90, and
91% at the IN, PF, and AF sampling  locations, respec-
tively.  As(lll)  concentrations  averaged 0.6 ug/L at the
inlet, 0.4 ug/L  at the prefiltration  location, and 0.4 ug/L at
the  after-filtration location. The treatment  process re-
moved approximately 33% of the inlet As(lll). This re-
moval was probably due to conversion of As(lll) to As(V)
during chlorination, followed by sorption/occlusion  with
alum floes, sedimentation, and filtration. Average As(V)
concentrations were 19.7 ug/L at the inlet,  3.9 ug/L at
the prefiltration location, and 4.2  ug/L at the after-filtration
location. The As(V) concentration decreased at the prefil-
tration location due to adsorption and coprecipitatiori of
the arsenic with the aluminum floes in the sedimentation
basins. This  result correlated with  the  increase In par-
ticulate arsenic at this same location. Figure 4-9 shows
the fractions  of the total arsenic concentration made up
of particulate arsenic, As(lll), and As(V).

As seen in Figure 4-9, a significant decrease in arsenic
removal efficiency was observed  beginning  October 29,
1998, and continuing through December 10, 1998. This
decrease in removal efficiency corresponded to an oper-
ational change at the plant.  During this period, Plant B
was testing an alternative coagulant to alum called PAX-
18, which is  a liquid polyaluminum chloride coagulant
that is supposed to reduce the amount of  sludge pro-
duced.  During  the six sampling events  that "occurred
while  this alternative  coagulant was used, total arsenic
concentrations averaged 18.8 ug/L at the inlet, 12.9 ug/L
at the prefiltration location,  and 10.8 ug/L at the  after-
filtration location.  In cprnparison, results from total arse-
nic concentrations measured during the 43 sampling
events when  alum was used as the coagulant averaged
19.1 ug/L at  the  inlet, 5.5 ug/L at the prefiltration loca-
tion, and 3.0 ug/L at the after-filtration location.  These
results correspond to arsenic removal efficiency bf"43%"'
when  the PAX-18 coagulant was being  used and  84%
when  the alum coagulant was used.

Removal efficiency using alum correlated very well to the
simple sorption model (McNeill and Edwards, 1997a). In
fact, the maximum deviation between the calculated and
actual removal was 12%, which is  within the 90th per-
centile confidence interval of the model.  Based on the
correlation, it  is believed that arsenic removal is achieved
through adsorption on and coprecipitation with the alumi-
num floes. The iron concentrations  in the source water,
                                                     34

-------
     30
     25
     20
   ง  15
   c
   o
   o
   o
      10
                          100%


                        -  90%


                        - • 80%


                        -  70%
                                                                                - • 20%
                                                                                 10%
                                                                                 o%
      6/4/98     7/24/98    9/12/98    11/1/98    12/21/98    2/9/99     3/31/99    5/20/99    7/9/99
                                           Date

Figure 4-8.     Total Arsenic Analytical Results [During Long-Term Sampling at Plant B
which were figured into  the  sorption model, also may
contribute to arsenic removal because the paniculate
arsenic at the inlet is most likely attached to the iron.

Removal efficiency  using the PAX-18 did not correlate
well to the sorption model. Actual arsenic removal was
28 to 42% less than removal predicted  by the model.
Based on the arsenate results at the outlet,  it appeared
that significantly  less As(V)  attached to the aluminum
floes produced  by the PAX-18 than the alum. Research
indicates  that  arsenate  removal  efficiency decreases
above pH 7 using alum (Sorg and Logsdon,  1978; Sorg,
1993). During operation with  PAX-18, the average pH of
the finished water  increased  from 7.4  to 7.8.  This
increase may explain the difference in  removal efficien-
cy. Additional research is needed to identify the mechan-
isms  affecting  removal  of  arsenic  using  polyaluminum
chloride. However, this study indicated that removal effi-
ciency using PAX-18 was significantly less than alum.

The Plant B water  treatment system was able to con-
sistently remove arsenic to  low levels when alum is used
as the coagulant (i.e., average treated water total  arse-
nic concentration was 3.0 ug/L when alum was used as
the coagulant). The primary arsenic removal mechanism
was adsorption and coprecipitation with the alum coagu-
lant followed by  sedimentation and filtration. Based on
the literature, increased  arsenic removal could possibly
be achieved by lowering pH to 7 or below and by increas-
ing coagulant dosage.

4.3.4.2 Other Water Quality Parameters

Other water quality parameters also were analyzed to
provide information regarding the ability of the treatment
plant  to  remove  arsenic. Table 4-12 summarizes the
analytical results  for several water quality  parameters
obtained during long-term sampling.

Alkalinity concentrations  ranged from 119 to 146  mg/L
(as CaCO3) in the inlet with an average of 131 mg/L. Fig-
ure 4-10 shows that alkalinity in the source water fluc-
tuated slightly ^seasonally with the lowest concentrations
in the late summer and the highest concentrations in the
spring. Concentrations  decreased between the inlet and
prefiltration sampling location and remained  relatively
constant between the prefiltration and after-filtration loca-
tions. These data do not appear to correlate with arsenic
analytical results or removal efficiencies.

During long-term sampling, turbidity concentrations aver-
aged 3.4 NTU at the inlet, 0.8 NTU at the prefiltration
location, and <0.1  NTU at the after-filtration  location. In-
let turbidity concentrations ranged from 11.8 to  1.0 NTU
and varied seasonally (see Figure 4-10).  The highest tur-
bidities were observed in the late spring, corresponding
                                                     35

-------
        Inlet
                                    25
                                    20 -
                                  to

                                  o 10 •
                                     5 -
                                    25
        Prefiltration
                                     ^ ^ ^  ^  oS>*  ^  J?  &  &   •&   &  
-------
Table 4-12. Summary of Water Quality Parameter Analytical Results at Plant B (June 1998-June 1999)
Parameter
Alkalinity


Turbidity


pH


TOG


Total Al


Total Fe


Total Mn


Dissolved Al


Dissolved Fe


Dissolved Mn


Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
mg/L
mg/L
mg/L
NTU
NTU
NTU
—
—
—
mg/L
mg/L
mg/L
pg/L
pg/t-
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
Number of
Samples
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
12
12
12
12
12
12
12
12
12
Minimum
Concentration
119
96
96
1
0.3
<0.1
7.9
7.2
7.2
2.8
2.3
1.7
43.4
67.6
28.1
32.2
<30
<30
11.0
0.6
<0.5
<11
41.7
25.7
<30
<30
<30
1.8
1.3
<0.5
Maximum
Concentration
146
132
126
11.8
1.2
0.3
8.6
: 8.1
8
9.8
8.6
8.7
501
809
98
507
75.6
57.4
39.0
18.2
5.8
'. <11
120
77
<30
<30
<30
7.5
9.7
<0.5
Average
Concentration
131
114
113
3.4
0.8
<0.1
8.4
7.5
7.4
3.7
3.1
3.1
173
493
56
164
<30
<30
19.6
9.3
0.7
<11
73
43
<30
<30
<30
4.0
5.5
<0.5
Standard
Deviation
7.8
10.2
9.4
2.3
0.2
0.04
0.1
0.2
0.2
1.0
0.9
0.9
129.7
145.3
18.2
129.3
14.1
6.4
7.1
3.7
0.8
NA
22.4
17.1
NA
NA
NA
1.9
2.7
NA
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
to snow melt and spring  rains, while the lowest values
were observed in the winter. Coagulant dosages were
determined by the source water turbidity concentration
and ranged from  29.0 to 44.7 Ib/day (2.6 to 4,1 mg/L)
when  alum was  used and  14.0  to  16.7 Ib/day (1.3 to
1.5 mg/L) when PAX-18 was used. The data show that
Plant B  effectively removed turbidity from the source
water; however, no correlation between turbidity removal
and arsenic removal was observed. Turbidity removal
was still very good (i.e.,  typically <0.1 NTU) when  the
plant was using  PAX-18, although PAX-18 was used
during the winter when turbidities were lowest.

The average pH was 8.4 at the inlet, 7.5 before filtration,
and 7.4 after filtration. As seen in Figure 4-10, inlet pH
was constant throughout the duration  of the study. As
stated previously, the pH increase, noted at the before-
and after-filtration  sampling  locations,  during  usage of
the  PAX-18 may have  adversely  affected the arsenic
 removal efficiency. TOC concentrations were  relatively
constant (see Figure 4-10), with averages of 3,7  mg/L,
3.1 mg/L,  and 3.1 mg/L at the  inlet,  prefiltration, and
after-filtration sampling locations,  respectively. A spike in
the TOC concentration was observed on May 20, 1999,
although the cause is not known. Eliminating  this data
point would reduce the average TOC concentrations to
3.5, 3.0, and 3.0 mg/L at the  IN, PF, and AF  sampling
locations, respectively. The  decrease in TOC between
the inlet and prefiltration sampling location is most likely
due to the coagulation process followed by sedimenta-
tion. The decrease corresponded to an average 14%
TOC removal.

Total aluminum concentrations averaged 173 ug/L at the
inlet, 493 ug/L before filtration, and 56 ug/L after filtration.
The average  dissolved aluminum concentrations were
<11 ug/L at this inlet, 73 ug/L at the prefiltration location,
and 43 ug/L at the after-filtration  location. The increase
in total  and dissolved aluminum at the prefiltration sam-
pling location  was due to the use of alum as the coag-
ulant. Based on plant data,  alum dosages  ranged from
29 to 44.7 Ib/day during the study, corresponding to alu-
minum  concentrations ranging from 2,600 to 4,100 ug/L.
The PAX-18  dosages  ranged from 14 to 16.7 mg/L,
corresponding to aluminum concentrations of 1,300 to
1,500 ug/L. These relatively high aluminum concentrations
                                                     37

-------
                                                                                                          :.•:	I	•
          14
                   80  ฃ
                                                                                     -Turbidity (NTU)

                                                                                     -pH (units)
                                                                                     -TOC (mg/L)
                                                                                     -Alkalinity (mg/L as CaCOS)
          6/4/98
                  7/24/98
                         9/12/98
                                 11/1/98
                                        12/21/98

                                         Date
                                                 2/9/99
                                                        3/31/99
                                                                       7/9/99
 Figure 4-10. Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at Plant B
were not observed at the prefiltration location because it
was located after trie sedimentation basin.

Total  manganese  concentrations  averaged  19.6 ug/L,
9.3 ug/L, and 0.7 ug/L, at the inlet, prefiltration, and after-
filtration sampling locations, respectively.  Average  dis-
solved manganese concentrations were 4.0 ug/L  at the
inlet, 5.5 ug/L at the prefiltration location, and <0.5 ug/L
at the after-filtration location. These relatively minor man-
ganese concentrations  probably did  not have a signifi-
cant impact on arsenic removal efficiency.

Total iron concentrations at the inlet sampling  location
ranged from 32.2 ug/L to 507 ug/L and averaged 164 ug/L.
At the prefiltration sampling location, total iron  concen-
trations  ranged from  <30 to 75.6 ug/L and averaged
<30 pg/L. The average total iron concentration at  the
after-filtration sampling location was <30 ug/L. Also, aver-
age dissolved iron concentrations were below the detec-
tion limit at the inlet, prefHtration, and after-filtration sam-
pling locations. These data indicate that iron probably was
not a major factor in As(V) removal during treatment oper-
ations. However, arsenic may have been attached  to the
Iron particles in the raw water, showing up as particulate
arsenic, which were subsequently removed.

4.3.4.3 Supernatant Discharge Water

The filter backwash water at Plant B is sent to a sludge
settling pond and the supernatant  is discharged to  the
adjacent  river  under a state permit.  Supernatant dis-
charge water samples were collected from  a manhole
located in the piping that transports the water from the
sludge settling lagoon to the river. Total arsenic  con-
centrations ranged from 4.6 to 56.1 ug/L and averaged
14.0 ug/L, approximately half of which was soluble and
half particulate. Total aluminum  concentrations ranged
from  359 to 7,500 ug/L and total  iron concentrations
ranged from  <30 to 191.5 ug/L. Results of supernatant
discharge sampling are summarized in Table 4-13.

4.3.4.4 Sludge

Sludge is generated at Plant B  from  sedimentation  in
primary and secondary clarifiers and from backwashing
filters. For most of the year, wastewater and sludge from
the clarifiers  is sent directly  to a sludge lagoon. How-
ever, the wastewater and sludge are sent directly to the
sanitary sewer for 3 to 4 months in the winter due  to
freezing conditions in the lagoon.

Backwashing occurs approximately every 50 hours. Back-
wash water is sent to a sludge settling tank. Sludge is
transferred from the settling tank and combined with the
wastewater and sludge from the  clarifiers prior to  dis-
charge into the sludge lagoon. Approximately once per
year, the sludge lagoon is dewatered using an  underdrain
system and the dewatered sludge is sent to a landfill.
The volume of  sludge sent to the landfill has not been
recorded,  nor has metals analysis been performed.
                                                     38

-------
Table 4-13. Summary of Analytical Results from Supernatant Discharge Water Samples at Plant B
           (November 12, 1998-June 17, 1999)
Parameter
As (total)
As (soluble)
As (particulate)
PH
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Number of
Units Sampling Events
M9/L
pg/L
ug/U

ug/L
Mg/L
Mg/L
pg/L
Mg/L
ug/L
8
8
8
8
8
8
8
8
8
8
Minimum
Concentration
4.6
2.5
0.2
7.5
359
<30
7.1
46.4
<30
<0.5
Maximum
Concentration
56.1
19.2
44.9
8.0 :
7,500
191.5
160.5
2,216.0
62.7
22.5
Average
Concentration
14.0
6.7
7.3
7.8
1,610
49.3
32.5
327.7
<30
4.0
Standard
Deviation
17.6
5.8
15.2
0.2
2,457
60.7
52.1
763.2
16.9
7.6
Sludge samples were collected on  December 15, 1998
from three locations from  within  a dewatered  sludge
lagoon.  These  sludge samples were analyzed for  pH,
percent  moisture, total arsenic,  and total iron. Also,  a
TCLP test was  performed on each sample to determine
the quantity of leachable arsenic, barium, cadmium, chro-
mium, lead, mercury, selenium, and silver.  Total arse-
nic concentrations ranged  from 293 to 493 mg/kg  dry,
and  total  iron  concentrations  ranged from  14,600 to
15,800 mg/kg dry. Arsenic was detected in leachate from
all three samples at concentrations as high as  0.160 mg/L;
however these concentrations were  well below the regu-
latory limit of 5  mg/L. Table 4-14 presents the results of
sludge analysis at each of the three sampling locations.

4.4  Plant C

Water and residual samples were collected and analyzed
at Plant C, a lime softening plant, during three phases of
the study: initial source water sampling (February 1998),
preliminary sampling (April and May 1998) and long-term
evaluation (June 1998 to June 1999). Arsenic speciation
sampling was conducted during the initial source water
sampling, once during preliminary sampling, and every
fourth week during the long-term  evaluation. The third
phase also included residual sample collection and analy-
sis. Supernatant discharge water samples were collected
monthly beginning in  November 1998, and three sludge
samples were'collected during a single sampling event
from a dewatered sludge lagoon.

4.4.1  Plant C Description

Plant C  serves a population  of approximately  35,000
(more than 14,000 taps).  The plant processes approxi-
mately 6.1 mgd and the design flowrate is 10 mgd. The
plant treats ground water using a lime softening process
followed by  sand filtration.  Figure 4-11 is a schematic
diagram of the,treatment process used at Plant C.

The treatment process at  Plant C consists of the follow-
ing major elements:

  •  Intake. Raw ground water from multiple wells (up
     to 4) is combined in a common header.

  •  Aeration. Aeration is used to  oxidize iron.
Table 4-14. Analytical Results of Sludge Sampling at Plant B (December 15, 1998)
                 Parameter
                                 Units
                                             DL
                                                      Location 1
                                                                    Location 2
                                                                                 Location 3
As-TCLP
Ba-TCLP
Cd-TCLP
Cr-TCLP
Pb-TCLP
Hg-TCLP
Se-TCLP
Ag-TCLP
TCLP extraction
pH
Percent moisture
As (total)
Fe (total)
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NA
—
%
mg/kg, dry
mg/kg, dry
0.05
1.0
0.020
0.030
0.20
0.0002
0.05
0.020
NA
—
0.1
61
379
0.058
1.3
<0.020
<0.030
<0.500
<0.0002
<0.050
<0.020
Complete
7.0
74.9
353
14,600
0.160
1.2
<0.020
<0.030
<0.500
<0.0002
<0.050
<0.020
; Complete
6.9
82.3
493
14,800
0.114
1.2
<0.020
<0.030
<0.500
<0.0002
<0.050
<0.020
Complete
6.9
78.2
293
15,800
                                                    39

-------
                                            Clarification
                                Aeration  (4 Units in Parallel)
          Filtration
                    Raw Water—
                   i	:,  from
                   Groundwater
                  ••"'.   Wells
                  1 „,   ™h i
           Supernatant Water-*.
           Discharged to Creek
              Under permit
                                             Clarifier   C'2Clb-
                                Sludge
                                Lagoon
  Backwash Water
                                           Sludge to Local Farm Fields
 Figure 4-11. Schematic Diagram, Plant C
  •  Clarification. Immediately after aeration, lime is
     added to the water in the middle section of each
     of four precipitators (solids-contact softeners) at a
     rate of 245 mg/L (dry lime stored on site in silos).
     In each of the precipitators, lime and water are
     mixed using a paddle-wheel mixer. The retention
     time In the precipitators is approximately 60 min-
     utes. Sludge is collected from the bottom of the
     precipitators, sent to a slurry tank, and then
     placed in a sludge lagoon. Sludge from the lagoon
     is used on local farm fields.

  •  Chlorination. Chlorine is added into each clari-
     fier collection trough at a  rate of approximately
     100 to 200 Ibs/day (correlating to approximately
     15 mg/L).

  •  Filtration.  Filtering media consists of 10 inches
     of graded gravel and 2 feet of sand.  There are
     15 separate filtering units that are backwashed
     approximately every 80 hours. Backwashing
     includes a surface scour.

  iป  Clearwell Storage. Treated water is chlorinated
     prior to clean/veil storage. The final chlorine con-
     ce^tration in finished water is approximately
     6 mg/L (<0.5 mg/L free chlorine).

  •  Backwash.  Backwashing occurs every 80 hours
     and the backwash water is combined with sludge
     from the clarifiers, sent to a slurry tank, and then
     on to a sludge lagoon. Sludge from the lagoon is
     used on local farm fields.  Approximately
     200,000 gal/day of water goes to lagoons.

4.4.2 Initial Source Water Sampling
      ''if. ,         '" ! i,   'il!i.i,<  i'l
!' „„     <„'!,!,          '"  1|"1!1!            '
The influent  water is supplied from four deep (approx-
imately 300 ft) ground water wells. Typically, only three
wells are used due to problems with the fourth well re-
garding, among other things, high arsenic concentrations.
Based on plant records, the ground water hardness is
approximately 350 to 400 mg/L (as CaCO3) and iron con-
centrations are approximately 2 to  2.5  mg/L. Also, the
raw  water contains 70 to 100 mg/L of  CO2. Based on
samples collected and analyzed by the plant, arsenic
concentrations observed in the source water wells range
from <0.01 to 89 ug/L. Arsenic concentrations in samples
collected near Plant C on November 25, 1992, from each
of the ground water wells are presented in Table 4-15.
Table 4-15. Arsenic Concentrations in Ground Water
           Wells at Plant C (1992)
Well
Number
6
7
8
9
Arsenic Concentration
(M9/L)
89
75
38
; <0.01
On February 27, 1998, an initial site visit to Plant C was
conducted and water samples were collected. The ground
water supplying Plant C is hard (averaging 336.5 mg/L as
CaCO3), with an average calcium hardness of 214.5 mg/L
as  CaCO3 and  an average magnesium  hardness of
121.5 mg/L as CaCO3. Plant C also had relatively high
turbidity,  averaging 20.5  NTU  during the  source  water
sampling event.  Consistent with plant records, the  iron
concentration was relatively high, averaging 2,370 ug/L.
As  would be expected for a ground water source, the
majority of the soluble arsenic  existed as arsenite (83%
of the soluble arsenic). AsJV)  was  detected during the
source water sampling at an average concentration of
2.0 ug/L.  Particulate arsenic  was not detected in  the
                                                     40

-------
source water samples. Table 4-16 presents the analytical
results from the source water sampling.

The average arsenic concentration detected during the
source water sampling event was 9.4 ug/L. This concen-
tration is lower than the minimum required for inclusion
into the preliminary and long-term phases of the study.
However, the  historical  data indicated that the source
water concentrations were much higher (see Table 4-15).
Therefore, the plant was included in the preliminary and
long-term sampling phases of this study.  It was; deter-
mined during the preliminary sampling phase of the study
that the sampling tap used during the initial source water
sampling was  not located properly  (this  issue is dis-
cussed in detail in Section 4.4.3).


4,4.3 Preliminary Sampling

Water samples were collected at three locations (i.e., IN,
PF, and AF) during the preliminary sampling phase of
this study. Sampling taps were available at the IN and
AF sampling locations; however, a  scoop was used to
collect samples at the PF location. The  inlet sampling
location  represents a combined sample  from the four
ground water wells and was located in the manifold piping
where the water from the wells is combined. The PF sam-
ples were taken from the channel surrounding precipitator
(i.e., solids-contact softener) No. 3 that  transports the
softened water to the filtration vessels. Therefore, PF
sampling location represents water that has been aerated
and processed through the solids-contact  softener. The
AF sampling tap was located after the  filtration  units
and represents water that enters the distribution  system.
Figure 4-12 is a process flow diagram for Plant C that
shows each of the sampling locations.

Consistent with Plants A and B, preliminary sampling at
Plant C consisted of weekly sample collection and analy-
sis of various parameters (alkalinity, turbidity, pH, hard-
ness,  total  iron,  total  manganese,  and total  arsenic
analysis).  Arsenic speciation  sampling, which included
determination of soluble and particulate arsenic, was con-
ducted once during the preliminary study on samples col-
lected from each sampling location. Table 4-17 presents
the results of the 4-week preliminary sampling period.

Results from the preliminary sampling events indicated
that inlet total arsenic concentrations varied widely, rang-
ing from approximately 2.4 to 83.4 ug/L. The  influent
samples collected on April  27 and May 11,  1998,  con-
tained relatively low concentrations of arsenic (i.e., 3.5
and 2.4 mg/L, respectively), when compared to concen-
trations in prefiltration  and postfiltration  samples. Re-
analysis of samples confirmed the concentrations of the
influent samples.  Similarly, the inlet  concentrations ob-
served during the source water sampling event were rela-
tively low. Subsequent discussion  with plant personnel
determined that the cause of the problem was the sam-
ple tap location. The sampling location was situated in
the manifold piping downstream of wells 6  and 9 and
upstream  of wells 7 and 8.  Review of the well operation
log indicated that well 6 (producing the highest As con-
centration among the four  wells) was not in operation
during sampling on April 27 and May 11, 1999; however,
well 6 was running on May 4 and May 18. As a result of
this finding, a new sampling location downstream of all
Table 4-16. Source Water Sampling Analytical Results at Plant C (February 27,1998)

                      Parameter    Units   Primaiy Sample   Duplicate Sample   Average Concentration
Alkalinity
Sulfate
Turbidity
PH
Hardness
Ca Hardness
Mg Hardness
Total Al
Total Fe
Total Mn
NO3-NO2 (N)
TOG
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
mg/L<"
mg/L
NTU
—
mg/L<*
mg/Lw
mg/L""
Mg/L
Mg/L
Mg/L
mg/L5"
mg/L
Mg/L
Mg/L
pg/L
Mg/L
Mg/L
400
7
20
7.2
341
217
124
<400
2,410
200
<0.02
3
9.4
12.0
ND
10.2
1.8
397
7
21
7.2
332
212
119
<400
2,330
210
<0.02
3 I
9.4
12.0
ND
9.7
2.3
398.5
7
20.5
7.2
336.5
214.5
121.5
<400
2,370
205
<0.02
3
9.4
12.0
ND
9.9
2.0
                   (a) As CaCO3.
                   (b) Combined NO3-N and NO2-N.
                                                     41

-------
               MONTHLY

            As (total), As (III), As (V)

      SLUDGE USED ON LOCAL
           FARM FIELDS

            As (total), Water Content,
            pH, TCLP metals
                                          INFLUENT
                  SETTLING
                  LAGOON
                                                AERATION
                                             PRECIPITATORS
                                            (4 Units in Parallel)
                       SUPERNATANT WATER
                    DISCHARGED TO BAYU TECHE
           As (dissolved and total), pH

           As (total), As (III), As (V)



         Backwash Water
                                               FILTRATION
           As (total), As (III), As (V)
NOTE:
Prefiltration water samples were
collected from Precipitator 3.
                                             DISTRIBUTION
                                                 SYSTEM
                                                                          WEEKLY
                                                                       As (total), Alkalinity, pH,
                                                                       Hardness, Turbidity,
                                                                       Total Fe, Total Mn
                                                                            Plant C

                                                                          Lime Softening
                                                                       Design Flow: 10 mgd
                                                                       As (total), Alkalinity, pH,
                                                                       Hardness, Turbidity,
                                                                       Total Fe, Total Mn
                                                                       As (total), Alkalinity, pH,
                                                                       Hardness, Turbidity,
                                                                       Total Fe, Total Mn
                                                                               LEGEND
                                                                         T .
                                                                         Lime
Sampling Location

Sludge Sampling
Location

Disinfectant Addition
Point
                                                                             Unit Process

                                                                             Chemical Added to
                                                                             Unit Process
Figure 4-12. Process Flow Diagram and Sampling Locations at Plant C
                                                   42

-------
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T- v v ;


CD in
T-" CD O O in <

CO




































oo
1
^
c.
0
c
CD
CD
CD
S
CO
CD
Q.
CO
CO
Duplicate
As CaCO.
ss
                                           43

-------
 wells (i.e., wells 6, 7, 8, and 9) was used for the long-term
 sampling phase of the study. This  new sample tap was
 located just prior to aeration, the first treatment process
 implemented at Plant C.

 The inappropriate sampling location used during the pre-
 liminary sampling  events  complicates  evaluation  of
 arsenic removal efficiency. However, some observations
 regarding the  arsenic  can be made. For example, the
 soluble arsenic in the  raw water entering the treatment
 plant was approximately 94% As(lll). This level would be
 expected for a ground water source. It appeared that the
 majority of  the  As(lll) was oxidized to As(V) prior  to
 filtration using two chlorine treatment steps. The average
 As(V) concentration observed at the sampling location
 situated after softening and chlorine addition made up
 approximately 97% of the soluble  arsenic. The  soluble
 arsenic in the finished  water consisted of approximately
 95% As(V). Particulate arsenic was not detected  in any
 of the samples collected during the preliminary sampling.

 Total arsenic concentrations in the finished water ranged
 between 18.8 ug/L and 41.6 ug/L and averaged 27.4 ug/L.
 Although arsenic removal  efficiency could not be deter-
 mined because of the  raw water sampling location, the
 data indicate that Plant C was not able to reduce arsenic
 concentrations  to low levels.  Prior research indicates
 that As(V) removal approaches 100% and As(lll) remov-
 al approaches 75% at pH  11 (Sorg  and Logsdon,  1978);
 however, arsenic removal efficiency decreases rapidly
 below pH 11. McNeill and  Edwards (1997b) showed that
 the primary arsenic removal mechanism during lime soft-
 ening Is adsorption and coprecipitation of As(lll) and As(V)
 with magnesium  hydroxide, which is precipitated near
 pH 11. Therefore, it appeared  that pH limited arsenic
 removal at  Plant C, where the average pH after lime
softening was 8.9. This conclusion was further supported
 by the limited removal of magnesium hardness. The aver-
age magnesium hardness concentrations decreased from
 113 mg/L in the  raw water to only 107 mg/L in finished
water.

Total hardness   concentrations  averaged  304  mg/L,
 164 mg/L, and 153 mg/L (as CaCO3) in the IN, PF,  and
AF sampling locations,  respectively. The plant did  soften
the raw water significantly;  however, Plant C removed
 primarily calcium hardness, which was reduced an aver-
age of 76% during preliminary sampling. As stated in the
previous paragraph, magnesium hardness was  not ef-
fectively removed by  Plant C, averaging only 5% re-
moval. Alkalinity  decreased  after  softening and then
remained constant between the softening and after filtra-
tion. This decrease  was expected  due to the chemical
reactions that occur during the lime softening  process
(for carbonate hardness only):
                                                 (4)
        CO2 + Ca(OH)2 = CaCO3i + H2O           (4)
    Ca(HCO3)2 + Ca(OH)2 = 2CaCO3l + 2H2O       (5)
Mg(HCO3)2 + Ca(OH)2 = CaCO3i + MgCO3 + 2H2O   (6)
    MgCO3 + Ca(OH)2 = Mg(OH)2i + CaCO3i       (7)
 Similarly,  pH increased  between the inlet and prefiltra-
 tion sampling locations due to the addition of lime; how-
 ever, this  pH is significantly less than the optimal pH for
 arsenic removal (i.e., pH 11).

 Total  manganese concentrations ranged  from 130 to
 230 ug/L in the inlet, <20 to 50 ug/L before filtration, and
 <20 to 40 ug/L after filtration. The  total iron concen-
 trations averaged 2,851 ug/L at the inlet, 543 ug/L at the
 prefiltration sampling location, and 41 ug/L at the after-
 filtration sampling location. The iron  in the  raw water is
 most likely in the reduced state since the soluble arsenic
 was primarily As(lll) in the raw water. As observed in
 Plant A, arsenic  removal by iron oxides  can be signifi-
 cant. Therefore, the concentration of iron in the raw water
 was important and research indicates that this iron can
 positively  impact arsenic removal efficiency  (McNeill and
 Edwards,  1997b).

 Similar to  Plants A and B, the preliminary sampling effort
 at Plant C resulted  in only minor changes to the long-
 term sampling approach. Dissolved aluminum, iron,  and
 manganese  concentrations  would be determined  every
 fourth week using leftover samples from the arsenic spe-
 ciation kits. In addition, aluminum was added to the list
 of analytes and the inlet sampling location was changed
 to be downstream of all ground water well inflows.

 4.4.4  Long-Term Sampling

 Weekly long-term sampling and analysis was performed
 for 49  weeks to determine concentrations  of  alkalinity,
 turbidity, pH, hardness, total aluminum, total iron, total
 manganese, and total arsenic. Long-term sampling also
 included 12 arsenic speciation sampling events that were
 used to determinate arsenic form and species as well as
 dissolved  metals  (iron, manganese, and aluminum) at
 each sampling location. The same three sampling loca-
tions that were used during the preliminary sampling phase
 also were  used during long-term  sampling.  Additionally,
 residual sampling was performed during this phase  and
 consisted  of collection and analysis of supernatant  dis-
 charge water and sludge. Figure 4-12 shows  the sam-
 pling locations during the long-term evaluation phase.

4.4.4.1 Arsenic

Table 4-18 provides a summary of the arsenic  analytical
 results collected at the three treatment process  locations.
Total arsenic concentrations at the inlet ranged from 15.9
                                                   44

-------
Table 4-18. Summary of Arsenic Analytical Results at Plant C (June 1998-June 1999)
Parameter
As (total)


As (total soluble)

As (particulate)


As(lll)


As(V)


Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
ug/L
ug/L
ug/L
ug/L
ug/L
pg/L
M9/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Number of
Samples
49
49
49
12
12
12
12
12
12
12
12
12
12
12
12
Minimum
Concentration
15.9
7.7
6.3
21.9
17.3
13.9
<0.1
<0.1
<0.1
22
<0.1
<0.1
<0.1
12.6
13.7
Maximum
Concentration
84.9
: 32.6
, 33.1
\ 40.8
: 31.0
, 22.5
7.3
4.0
1.1
37.2
17.8
1.5
10.2
29.9
22.1
Average
Concentration
32.0
23.2
16.6
33.8
24.2
17.1
1.2
1.0
0.3
30.0
1.9
0.4
3.9
22.3
16.7
Standard
Deviation
10.5
5.6
4.2
6.0
4.6
2.4
2.2
1.5
0.4
4.9
5.0
0.4
2.9
4.9
2.4
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
to 84.9 ug/L with an average concentration of 32.0 ug/L.
Total arsenic concentrations at the prefiltration location
(i.e.,  after softening and before filtration) ranged from
7.7 to 32.6 ug/L with an average of 23.2 ug/L. Samples
collected  after filtration contained total arsenic concen-
trations ranging from 6.3 to 33.1 yg/L with an  average
concentration  of 16.6 ug/L. The total  arsenic analytical
results were relatively constant, with the exception of a
peak in the raw water arsenic concentration that occurred
on April 26, 1999. The cause of this peak is not known;
however,  it is likely due to the  ground water wells; operat-
ing during this sampling event (i.e., wells 6 and 7, which
have much higher arsenic concentration, may have been
contributing more to the influent flow). The average  re-
moval percentage of total arsenic between the inlet and
prefiltration sampling locations  was 28%.  The  average
removal  percentage of total  arsenic between 'the inlet
and after-filtration sampling locations was  48%. Total
arsenic removal efficiency also was  relatively constant
during the long-term evaluation with  the exception of
March 22,1999, when arsenic removal was a minus 53%.
The explanation for  this data point is not known but may
be a result of well operation schedule, resulting in lower
than normal inlet arsenic concentrations. Figure 4-13 is a
graph showing the total arsenic concentration recorded
at each sampling location throughout the study, as well as
removal percentages calculated for each sampling event.

Particulate arsenic concentrations averaged 1.2 ug/L at
the  inlet,  1.0 ug/L at the prefiltration sampling  location,
and 0.3 ug/L at the after-filtration sampling location. This
indicates  that approximately 75% of the particulate arse-
nic is removed  by the system, primarily during  filtration.
As(lll) concentrations averaged 30.0 ug/L at  the inlet,
1.9 ug/L at the  prefiltration location, and 0.4 ug/L at the
after-filtration  location.  Substantial conversion of As(lll)
to As(V) occurred between the inlet and finished water
due to the two chlorination steps. As(V) concentrations
were 3.9 ug/L at the  inlet, 22.3 ug/L at the prefiltration
location, and 16.7 ug/L at the after-filtration location. The
data were relatively consistent regarding As(lll) and As(V)
concentrations at each sampling location.  One deviation
occurred on August 3, 1998, where the As(lll) concen-
tration  after the precipitators and before the filters was
17.8 ug/L and the As(V)  concentration was 12.6 ug/L
The cause of this deviation is not known.

These  data showed that the inlet water at Plant C  con-
tained  primarily the  reduced species of  arsenic  (i.e.,
Asflll]) with only minor concentrations of As(V)  and par-
ticulate arsenic. The As(lll) was converted to As(V) dur-
ing the aeration and chlorination step prior to clarification
(softening) arid  the chlorination step  prior to  filtration.
The arsenic in the finished water consists almost entirely
of As(V). Figure 4-14 shows the fractions of  the  total
arsenic concentration made up of  particulate arsenic,
As(lll), and As(V).

Based on studies by  Sorg and Logsdon (1978), arsenic
removals should  be low at Plant C due to the  relatively
low pH (average pH is 8.8 after lime softening) achieved
during the softening  process.  Documented arsenic re-
moval  efficiencies when  only calcium  carbonate  is pre-
cipitated are between 0 and 10% (McNeill and Edwards,
1995). However, the average arsenic removal at Plant C
was 48%. This removal most likely is associated with the
iron in the source water. Total iron concentrations in the
source water  averaged  2,303 ug/L,  practically all  of
which was in reduced state. It is believed that adsorption
and coprecipitation with the iron is the primary factor in
arsenic removal at this plant. Based on the simple sorp-
tion model by McNeill and Edwards (1997a),  estimated
                                                      45

-------
90



80



70



60



50


40 J



30



20.



10
                                                                                     100%
                                                                                     80%
                                                                                    . 60%
                                                                                          •a
                                                                                     40%  >
                                                                                          E
                                                                                          o
                                                                                          o:

                                                                                     20%  |
                                                                                     0%
                                                                                          S
                                                                                          01
                                                                                          0.
                                                                                     -20%
                                                                                     -40%
                                                                                     -60%
    6/4/98     7/24/98    9/12/98    11/1/98    12/21/98     2/9/99     3/31/99    5/20/99    7/9/99

                                           Date


Figure 4-13. Total Arsenic Analytical Results During Long-Term Sampling at Plant C
arsenic removals should  average approximately  75%
(approximately 30% higher than observed). However, in
another study by McNeill and  Edwards (1997b), it was
reported that carbonate can interfere  with arsenic re-
moval by iron hydroxide due to competition for sorption
sites. Additionally, the available research provides little
information  on arsenic removal by coprecipitation with
Iron hydroxide at pH values greater than 8.5. Therefore,
arsenic removal through adsorption and coprecipitation
with  iron hydroxide appeared to be limited by the lime
softening process.

The  Plant C water treatment system was not able to
consistently remove arsenic  to low levels (i.e., average
total arsenic concentration in treated water was 16.6 ug/L).
The  literature indicates that removal  efficiency would
Increase if the pH was increased. The primary arsenic
removal mechanism is coprecipitation with the iron in the
source water followed by sedimentation and filtration.


4.4.4.2 Other Water Quality Parameters

As with Plants A and B, sampling and analysis of other
water quality parameters  were  performed to  provide
insight into the arsenic removal efficiency at the plant.
                                                     Table 4-19 summarizes the analytical results for several
                                                     water quality parameters obtained during long-term sam-
                                                     pling.

                                                     Inlet alkalinity concentrations  were  relatively  constant,
                                                     ranging from 300 to 411 mg/L  (as CaCO3) with an aver-
                                                     age of 399 mg/L (see Figure  4-15). The alkalinity con-
                                                     centration decreased  between the inlet and prefiltration
                                                     sampling location and remained relatively constant be-
                                                     tween the prefiltration and after-filtration locations. This
                                                     reduction  in  alkalinity was  associated with  hardness
                                                     removal during the softening process.

                                                     During  long-term  sampling,  turbidity concentrations
                                                     averaged 26.3 NTU at the inlet, 9.8 NTU at the prefiltra-
                                                     tion location, and 1.3  NTU at the after-filtration location.
                                                     The  inlet turbidity  concentrations  were relatively high,
                                                     ranging from  16.1 to  33  NTU, and are plotted on Fig-
                                                     ure 4-15. The data show that Plant B achieves an aver-
                                                     age turbidity removal efficiency of approximately 95%.

                                                     The average pH was 7.2 at the inlet, 8.8 at the prefiltra-
                                                     tion sampling  location, and 8.6 at the after-filtration loca-
                                                     tion.  Inlet pH  was relatively constant (see Figure 4-15).
                                                     The pH increased at the prefiltration location due to the
                                                     46

-------
                                  45.0
         Inlet
40.0 .
35.0 -
^ 30.0 -
.3
| 25'ฐ "
| 20.0 .
1 15.0 -
O
10.0 .
5.0 -
0.0





























































DAs(V)
BAs (III)
gAs (particulate)



                                                                                "x
         Prefiltration
45.0
40.0 -
35.0 -
1 30.0 -
o 25.0 -
•&
| 20.0 ,
= 15.0 -
o
O
10.0 -
5.0 -
0.0
J























-

















I
I






— I











,— 1





I





	



































—





"
if:







—1




i
^** nป 0 1 **? N^1 (V^1 (0?* k^ f^^ r \^
         After Filtration
45.0
40.0 .
35.0 .
75, 30.0 -
? 25.0 -
•a
ฃ 20.0 -
0)
= 15.0 .
o
O
10.0 -
5.0 .
0.0 -






























m



,— I











r-i





— ,





-






















nAs(V)
• As (III)
gAs (particulate)




Figure 4-14. Arsenic Form and Species Analytical Results During Long-Term Sampling at Plant C
                                                     47

-------
Table 4-19. Summary of Water Quality Parameter Analytical Results at Plant C (June 1998-June 1999)
Parameter
Alkalinity


Turbidity


pH


Total Hardness


Total Al


Total Fe


Total Mn


Dissolved Al


Dissolved Fe


Dissolved Mn


Sample Location
Inlet
Prefiltration
After filtration
Inlet
Preflitration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
mg/L
mg/L
mg/L
NTU
NTU
NTU
—
—
—
mg/L
mg/L
mg/L
Pg/L
P9/L
pg/L
P9/L
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
Number of
Samples
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
12
12
12
12
12
12
12
12
12
Minimum
Concentration
300
125
146
16.1
0.7
<0.1
7.1
7.9
7.8
267
85
110
<11
13.4
<11
92
81
<30
75.9
3.6
1.0
<11
<11
<11
1512
<30
<30
106
<0.5
0.7
Maximum
Concentration
411
382
321
33
25.5
25
7.4
10.1
9.3
353
304
290
63
87
99
3768
766
1110
204
48.9
54.7
<11
36
12
2966
<30
<30
189
7.8
4.6
Average
Concentration
399
214
198
26.3
9.8
1.3
7.2
8.8
8.6
318
179
163
12
43
20
2389
397
76
140
12.6
4.8
<11
18
<11
2303
<30
<30
146
2.6
1.9
Standard
Deviation
15.4
40.9
30.4
4.2
5.9
3.61
0.1
0.5
0.3
17.6
37.3
29.1
13.3
16.1
15.9
556.7
181.8
165.2
27.5
8.2
8.0
NA
10.6
2.0
363
NA
NA
28.7
2.1
1.2
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
lime softening  process.  A similar trend was observed
with total hardness concentrations;  however, the hard-
ness concentrations  were  relatively high at the  inlet
(average 318 mg/L as CaCO3) and decreased after the
lime softening  process to an average concentration of
179 mg/L at the prefiltration location and 163 at the after-
filtration location. It is important to note that the hardness
reduction consisted primarily of calcium  hardness re-
duction;  magnesium  hardness  was  relatively constant
throughout the  treatment process. This result is not sur-
prising considering that  optimal magnesium hydroxide
formation is achieved at  pH 11. Precipitation of magne-
sium hydroxide is associated strongly with  arsenic re-
moval, because the arsenate adsorbs and coprecipitates
with the Mg(OH)2 (McNeill and Edwards, 1997b).

Total aluminum concentrations averaged 12  ug/L at the
inlet, 43 ug/L at the prefiltration location, and 20 ug/L at
the after-filtration location. The slight increase in alumi-
num at the prefiltration sampling location  is probably due
to trace amounts of aluminum in the lime. Manufacturers
data indicated the lime contains 0.45% AI2O3. The aver-
age dissolved aluminum concentrations were <11 ug/L at
the inlet, 18 ug/L at the prefiltration location, and <11 ug/L
at the after-filtration location. Because of the low concen-
trations, aluminum is not considered a significant factor
in arsenic removal.

Total  manganese concentrations averaged  140 ug/L,
12.6 ug/L, and 4.8 ug/L, at the inlet, prefiltration, and after-
filtration sampling locations,  respectively. Average dis-
solved manganese concentrations were 146 ug/L at the
inlet, 2.6 ug/L at the prefiltration location, and  1.9 ug/L at
the after-filtration location. However, due to the relatively
low concentrations of manganese compared to iron, it is
not believed that the manganese is a significant factor in
arsenic removal at Plant C.

Total  iron concentrations  at the inlet sampling location
ranged from 92 to 3,768 ug/L and averaged 2,389 ug/L.
At the prefiltration sampling location, total iron concentra-
tions ranged from 81 to 766 ug/L and averaged 397 ug/L.
The average total iron concentration at the after-filtration
sampling location was 76 pg/L. Also, average dissolved
                                                     48

-------
   46 .
   41
   36
 I31
 H
 — 26
   16
   11
                                                                         450
                                                                         400
                                                                         350
                                                                             2-
                                                                         300 .ฃ
                -I- 250 ป
                     C
                     •o
                     i
                  200 •?
                                                                        -. 150
                                                                        .-100
_•—Turbidity (NTU)

_•—pH (units)
—A—Hardness (mg/L as CaCO3)

_x—Alkalinity (mg/L as CaCOS)
    6/4/98    7/24/98   9/12/98    11/1/98    12/21/98   2/9/99    3/31/99    5/20/99    7/9/99
                                      Date

Figure 4-15. Inlet Turbidity, pH, Hardness, and Alkalinity Analytical Results at Plant C
iron  concentrations were 2,303 ug/L at the  inlet  and
<30 ug/L at both the prefiltration and after-filtration loca-
tions. The data indicated that the iron in the source water
was  in the reduced state and was completely oxidized
during the aeration and chlorination steps. The average
concentration of total iron at the inlet was reduced 97%
by the treatment process. It is believed that the primary
arsenic  removal mechanism was adsorption and copre-
cipitation of As(V) with the iron.

4.4.4.3  Supernatant Discharge Water
The filter backwash water at Plant C is sent to a slurry
tank and then to a sludge  settling lagoon. The super-
natant of the sludge lagoon is discharged to an adjacent
creek under a state permit. The plant is required to moni-
tor the  supernatant discharge for pH weekly  and total
dissolved solids (TDS) monthly as part of its discharge per-
mit. Supernatant discharge water samples were collected
at the outfall of the sludge lagoon where it discharges to
the creek.

Results of supernatant  discharge water sampiing are
summarized in Table 4-20. Total arsenic concentrations
averaged 20.8 ug/L, consisting of an average of 21.2 ug/L
of soluble arsenic and 0.7 ug/L  of  particulate arsenic.
The pH was elevated due to the lime softening process.
As would be expected based on the concentrations in
the source water, total  iron concentrations in the super-
natant water were relatively high and total aluminum and
manganese concentrations were relatively low.

4.4.4.4 Sludge
Sludge is generated from the lime softening precipitators
and from backwashing the  sand filters. Sludge is col-
lected from the bottom  of the four precipitators and sent
to a slurry tank. Filter backwashing occurs approximately
every 80 hours and the backwash water  is combined
with sludge  from the precipitators in  a slurry  tank and
then sent to a sludge lagoon.  Approximately 230,000
gal/day of water goes to the lagoon. Approximately once
every 2 years,  or as required, the lagoon is dewatered
using an underdrain  system and the sludge is removed
(approximately  14,500 yd3 of sludge was removed in the
spring of 1998). Sludge from the lagoon is used on local
farm fields.

Sludge samples were collected  on  November 16,  1998
from  three locations from within  a dewatered  sludge
lagoon at Plant C. These sludge samples were analyzed
for pH, percent moisture, total arsenic, total aluminum,
                                                     49

-------
Table 4-20. Summary of Analytical Results from Supernatant Discharge Water Samples at Plant C
            (November 9, 1998^June 14, 1999)
Parameter
As (total)
As (soluble)
As (participate)
PH
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Units
M9/L
M9/L
M9/L
—
M9/L
(jg/L
M9/L
M9/L
M9/L
ug/t-
Number of
Sample
Events
8
8
8
8
8
8
8
8
8
8
Minimum
Concentration
14.7
14.9
<0.1
9.0
35
223
7.2
<11
<30
1.3
Maximum
Concentration
27.2
27.2
4.3
9.7
98
1,545
35.2
24.3
44.3
25.5
Average
Concentration
20.8
21.2
0.7
9.3
60
716
19.3
<11
<30
7.4
Standard
Deviation
4.3
4.0
1.5
0.3
24
505
10.1
7.2
10.9
7.9
total iron, total manganese, and TCLP metals (arsenic,
barium, cadmium, chromium, lead, mercury, selenium,
and  silver). Total arsenic  concentrations ranged from
17.0 to 35.3 mg/kg dry, and  total iron concentrations
ranged from 3,190 to 7,920 mg/kg dry. Arsenic was not
detected in leachate from any of the three samples; how-
ever,  minor concentrations of barium,  cadmium, chro-
mium, lead, and silver were  detected. Consistent with
Plants A and B, none of the sludge  analytical results
from Plant C indicate exceedances of  regulatory levels.
Table 4-21   presents the results of sludge analysis at
each of the  three sampling locations.
Table 4-21. Analytical Results of Sludge Sampling at Plant C (November 16,1998)
                    Parameter
                                   Unit
                                              DL
                                                      Location 1
                                                                   Location 2
                 (a) Detection limit is in units of ug/L for digestate.
                                                                                Location 3
As-TCLP
Ba-TCLP
Cd-TCLP
Cr-TCLP
Pb-TCLP
Hg-TCLP
Se-TCLP
Ag-TCLP
TCLP extraction
pH
Percent moisture
Total As
Total Al
Total Fe
Total Mn
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NA
—
%
P9/9- dry
M9/9, dry
Pg/9, dry
pg/g- dry
0.05
1.0
0.020
0.030
0.20
0.0002
0.05
0.020
NA
—
0.1
0.1 <"
11'"
30("
0.5">
<0.05
3.3
0.03
0.06
0.25
<0.0002
<0.05
0.04
Complete
9.7
51.7
17.0
1,370
3,190
230
<0.05
2.6
0.03
0.06
0.27
<0.0002
<0.05
0.03
Complete
10.3
51.2
35.3
841
7,920
261
<0.05
3.9
0.03
0.05
0.25
<0.0002
<0.05
0.03
Complete
9.5
51.4
28.2
919
6,510
281
                                                    50

-------
                           5.  Quality Assurance/Quality Control
5.1  Quality Assurance Objectives

The  precision,  accuracy,  MDL, and  completeness for
each of the  analytical measurements required for this
study have  been established in  the QAPP  (Battelle,
1998) and are listed in Table 1 of the QA/QC Summary
Report, which is  being prepared under separate cover.
These terms serve as indicators of data quality and were
calculated in accordance with the formulas provided in
the QAPP. The precision, accuracy, and MDL of each of
the measurements  performed during  the present study
are presented  in the summary report.  These  quality
assurance (QA)  data are organized according  to  the
date of sample receipt or sample analysis and are not
site-specific. Therefore, the QA/QC section of this report
shares the same QA data with other water treatment
plants that have been included in the study.

5.2  Overall Assessment of Data Quality

Quantitative QA objectives listed in the QA/QC Summary
Report include precision as  relative  percent difference
(RPD), accuracy as percent recovery (%R), MDL, and com-
pleteness. The precision, accuracy, and MDL or reporting
limit  of each of the measurements performed  during the
present study are presented. Total arsenic,  aluminum,
iron, and manganese analyses on water samples were
conducted in Battelle's ICP-MS laboratory. The QA data
associated with these metal analyses also are present-
ed. Other water quality parameters, including alkalinity,
pH,  turbidity, hardness,  nitrate-nitrite, sulfate, fluoride,
TDS, and TSS, were analyzed by Wilson Environmental
Laboratories and their QA data were summarized. QA
data for TOC analysis performed by CT&E Environmen-
tal Laboratory are presented. The TCLP metal analysis
on sludge samples also was  conducted by Wilson Envi-
ronmental Laboratories  and  its  associated  QA  data
are summarized.  Overall, the QA objectives of precision,
accuracy, MDL, and completeness were achieved by all
laboratories. Therefore, all the valid data were used to
evaluate the effectiveness of the treatment  processes
and  support conclusions.
5.2.1  Total Arsenic, Aluminum, Iron,
      and Manganese

At the early phase of the study, total arsenic analysis
was performed by Battelle's ICP-MS laboratory, and total
aluminum, iron, and manganese were analyzed by Wilson
Environmental Laboratories. Starting from June 1998, all
four metals were analyzed by Battelle ICP-MS labora-
tory. Therefore', QA data for only the total arsenic analy-
sis before June 16, 1998, and QA data for all four metals
afterwards are presented.

The laboratory duplicate and matrix spike (MS) analyses
were performed every 10 samples instead of 20 samples
as required by the QAPP. All the samples were analyzed
for four metals although metals other than  arsenic may
not be required  for every sample.  Therefore,  Battelle's
ICP-MS  laboratory performed more QA/QC  analyses
than what were specified in the QAPP. This fact should
be considered when QC data are evaluated.

Greater than 99% of the precision  results for all metals
met the QA objective of ฑ25% (with only two iron out-
liers: 27% on August 8,  1998, and 74% on December
22, 1998; three arsenic outliers: 27% on August 18,
1998, 182% on  October 1, 1998, and 27% on July 30,
1999; and  four  aluminum outliers: 26% and 33% on
August 18,  1998, 48% on December 15, 1998, and 48%
on January 25, 1999). The majority of the accuracy data
associated  with  MS analysis  on  August 31,  1998,
exceeded the QA  limits of 75 to 125%. It  is suspected
that MS analyses were not performed correctly on that
day. After this problem had been identified,  Battelle's
WAL, laboratory QA officer, and Battelle's  task leaders
met to discuss  the cause of the deviation. Corrective
actions were taken including reanalyzing samples and
adjusting the amount of spike added to samples (i.e., the
iron spike was increased  from 50 to 100,  200, 225,  or
even as high as 2,000 ug/L due to the fact that most of
samples  contain much  more than  50 ug/L of iron). As
indicated in the QA/QC Summary Report,  the MS data
quality was significantly improved since November  3,
                                                  51

-------
 1998. Excluding the data on August 31, 1998, only five
 As data were outside the acceptable range for accuracy.
 However, 15 Al, 2& Fe, and 14 Mn accuracy data did not
 meet the QA objective. With exceptions of one 23% and
 one  38% of accuracy, the Al accuracy data range from
 65 to 125%.  The Mn  accuracy data range from 67 to
 106%, with exception of one 37%. The Fe accuracy data
 range from 55 to 142%, with exceptions of one 14%, one
 23%, and one 38%.

 All laboratory control samples showed %R  within the
 acceptable QA limit of 75 to 125% except for six outliers
 for total Fe with %R ranging from 73 to 143%. Al was not
 spiked to laboratory control samples  until November 3,
 1998, after corrective actions were taken. The MDL of
 Fe is the same as target MDL; however, MDLs of other
 three metals were far below the target levels as specified
 in the QAPP.

 5.2.2  Water Quality Parameters

Water quality parameters include alkalinity, pH, turbidity,
 hardness (Ca and  Mg),  nitrate-nitrite, sulfate, fluoride,
TDS, TSS and TOG. As shown in Table 3 of the QA/QC
 Summary Report, all the precision  data were within the
acceptable  QA limit of ฑ25% except for two Mn analysis
with  a 29% RPD (April  10 and 17,  1998) and three
nitrate-nitrite analyses with 40% RPD  (August 6, 1998,
January 13, 1999,  and February 11,  1999). The  high
RPDs of these analyses might have been caused by the
low measured concentrations in the samples that were
close to the detection limits for Mn and nitrate-nitrite. The
accuracy data indicate that only one Al (70% on March
2, 1998), two Mn (66% and 64% on May 12, 1998), and
one Mg (126% on August 7, 1998) %R slightly exceeded
the QA objectives of  75 to 125%. Although the matrix
spike duplicate (MSD) analysis was not required by the
QAPP, the accuracy and the precision data relating to
MSD also were presented. The MS/MSD analyses are not
applicable to pH and turbidity measurements,  though.
The laboratory did not perform MS/MSD analyses on Ca
and Mg hardness analyses till October 15,  1998 upon
Battelle's request. All laboratory control samples  showed
%R within the acceptable QA limit of 75 to  125%. Re-
porting limits were below the required  levels for all the
analytes except for sulfate. The reporting limit of sulfate
was 5 mg/L, exceeding the required MDL of 3.66 mg/L.
All precision, accuracy, and %R values for the TOG analy-
sis were within acceptable QA limits with the exception
of one  accuracy value that was slightly below the 75 to
125% range at 72% (February 21, 1999).

5.2.3  TCLP Metals in Sludge

The  TCLP metals  analyzed in the  sludge samples
included As, Se, Hg, Ba, Cd, Cr, Pb, and Ag. The preci-
sion data were within  QA limits of ฑ25%. The accuracy
of MSs and percent recovery of laboratory control sam-
ples were all within QA limits of 75 to 125%, except for
one slightly elevated RPD for TCLP Se MS/MSD at 26%
(November 17, 1998).
                                                  52

-------
                                          6.  References
Amirtharajah, A., and C.R. O'Melia. 1990. "Coagulation
  Processes: Destabilization, Mixing, and Flocculation."
  In American Water Works Association (Eds.),  Water
  Quality and Treatment:  A Handbook of Community
  Water Supplies. New York: McGraw-Hill.

Andreae, M. 1977. "Determination of Arsenic Species in
  Natural Waters." Anal. Chem., 49: 820-823.

Battelle. 1998. Quality Assurance Project Plan for Evalu-
  ation of  Treatment  Technology for  the  Removal of
  Arsenic from Drinking Water. Prepared for EPA..

Benefield, L.D., and J.S. Morgan. 1990. "Chemical Pre-
  cipitation." Water Quality and Treatment.

Chen, S.L, S.R. Dzeng, M. Yang, K. Chiu, G. Shleh, and
  C.M. Wai. 1994. "Arsenic Species in Groundwaters of
  the  Blackfoot Disease Area, Taiwan." Environmental
  Science and Technology. 877-881.

Chen, R.C., S. Liang, H.C. Wang, and M.D. Beuhler.
  1994. "Enhanced  Coagulation for Arsenic Removal."
  J. AWWA (September): 79-90.

Clifford,  D.,  L.  Ceber,  and  S. Chow. 1983.  "Arse-
  nic(lll)/Arsenic(V)  Separation  by  Chloride-Form  Ion-
  Exchange  Resins."  Proceedings of the  XI AWWA
  WQTC.

Eaton, A.D., H.C.  Wang,  and J.  Northington.  1997.
  "Analytical  Chemistry of Arsenic  in Drinking Water."
  AWWARF Project 914.

Edwards,  M.  1994. "Chemistry of Arsenic Removal
  during  Coagulation and  Fe-Mn Oxidation." J. AWWA
  (September): 64-78.

Edwards,  M., S.  Patel,  L.  McNeill, H.  Chen, M. Frey,
  A.D. Eaton, R.C. Antweiler, and H.E. Taylor. 1998.
  "Considerations  in  As   Analysis  and  Speciation."
  J. AWWA (March): 103-113.
EPA, see U.S. Environmental Protection Agency.

Ficklin, W.H. 1982. "Separation of Arsenic (III) and Arse-
  nic (V) in  Groundwaters by Ion  Exchange."  Talanta,
  30(5): 371-373.

Gulledge, J.H., and  J.T. O'Conner. 1973. "Removal of
  Arsenic (V) from Water by Adorption on Aluminum and
  Ferric Hydroxides.  J. AWWA (August): 548-552.

Hemond, H.F: 1995.  "Movement  and  Distribution of
  Arsenic in the Aberjona Watershed." Environmental
  Health Perspectives.

Hering, J.G., P.Y. Chen, J.A. Wilkie,  M. Elimelech, and
  S. Lung. 1996. "Arsenic Removal by  Ferric Chloride."
  J. AWWA. (April): 155-167.

McNeill, L.S., and M. Edwards. 1995. "Soluble Arsenic
  Removal  at Water  Treatment  Plants."  J.  AWWA.
  (April): 105-113.

McNeill, L.S. and M. Edwards.  1997a. "Predicting As
  Removal   During   Metal  Hydroxide  Precipitation."
  J. AWWA. (January): 75-86.

McNeill, L.S. and M.  Edwards. 1997b. "Arsenic Removal
  During Predipitative  Softening."  Journal  of  Environ-
  mental Engineering (May): 453-460.

Scott, K.N., J.F. Green,  H.D.  Do,  and  S.J. McLean.
  1995. "Arsenic Removal by Coagulation." J. AWWA
  (April): 114-126.

Sorg,  T.J.  1993. "Removal of Arsenic From  Drinking
  Water by Conventional Treatment Methods." Proceed-
  ings of the 1993 AWWA WQTC.

Sorg,  T.J.,  and G.S. Logsdon. 1978. "Treatment Tech-
  nology to Meet the Interim Primary Drinking Water
  Regulations for Inorganics: Part 2."  J. AWWA (July).
                                                   53

-------
Tate, C.H., and K.F. Arnold. 1990. "Health and Aesthetic
  Aspects of Water Quality." In American Water Works
  Association (Eds.), Water Quality and Treatment: A
  Handbook of Community Water Supplies. New York:
  McGraw-Hill.
U.S. Environmental Protection Agency. 1998. Research
  Plan for Arsenic in Drinking Water. EPA/600/4-98/042.
  Office of Research and Development, Washington, DC.
  February.
                                                  54

-------
                      APPENDIX A
Complete Analytical Results from Long-Term Sampling at Plant A
                           55

-------
CO
U3
 3
 CO
$

E
 o,

 o
 cu
CC

 S
;:'


;::;,l"
!2
:::""- 	 '
; 	 :: -i
	 ' 	 "l"""
„„,,,,, ,,,,,,, 	

i 	 '


^
ฃi






eg
S




CO
o>

tฃ>









^^
As (particulate

O O
V V


o o

•* co
0 0





























1


V)
CM CM
CM CM

0 O
co co


CO CO





























4


1
in o
CO ฃ.

CO T—
in oo
t m

o in
OO T-
m m

^
^"


o>
s

CO
in
co

•>"
V
CM
en
o
EM
in
CM

^
in
m




in

T—

_]


Total Al

CO CO
V V

CO 5
co co

CO 1^-
•* CO


o
CO
V

s
"3-
^
co

CO
v

V

1
s
V

in
^



^~

\('

1


Total Fe
in in
ฐ ฐ


en i-
i- CM

•* 05
CM O
CM CM

in
o
V


CO

en
CO
in
"v

^
"-
in
^
in
o

en
CO



CO
CM
CO


ฐ5>


Total Mn

^ ^
V V

y~ y~
V V

••- T-
V V




























1


1 Dissolved Al

ง g
V V

co co
V V

g g
V V




























1


Dissolved Fe
in in
o o
V V

O 0
co co

en in
•*- '-





























4


	 	
Dissolved Mn





























c
o
2
ซ=
CD
*;
co
ii

•s
Q.
(a) As CaCO3.
IN = inlet; PF =
                                                56

-------
oo
CD
O5
CM
 D)
CM
CM
<

 c


CL

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15.


 at


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 05


I


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 CD
CC

"co
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CO
5ป
Si
>S ;
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CO
i



CO
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s
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CO
S-


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/ฃ
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CO

<

Q.

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<

0-

z
u.
<
u.
Q.
Z;-

^
^
a.

z
7ci
o
1^ Sampling Locji
Parameter'N-

5!^

CM CO
•* •<*•

in CD
•* •*

CM
•*

5

in
•*
5
?
!?

o o
in in

59

T- CM
in in
L
D)
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c
I
<

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CM T-

•* •*
O 0

?
05
O
CO
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m
CO
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V V
CO CO
0 0
T- O
co to
3
Z
.&
T3
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r~ h~
in in
r^ N-
f~ N
r~ i^
r~
r~
CO
h~
CO
t^
t^
t^
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K
0
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in in
r~ r~
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i-~ r^
en en
r~ t^

5.
en co

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h~ co

o
co
en

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CD
in
en r~

h~ co

CO CO

^
g
CO
0
N
•*
CO
•*
 in
•*• CD
CM
0
d
CO
in
CO
CM
CO
1^
in
0
1
1






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CM CM
1^ 1^
CM CM
en co
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1
As (total soluble)






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0 0
T- in
to co

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V









i
As (particulate)






* •*
0 0
CM CM
O 0
in in
o o









i
CO
<






r-- CD

in in
00 CM
"3- i-
in in









i
>;
CO
<
I--
CM
CD
IO
CO
CM
CO
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T- CM
V ^~
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CD CO
CM CM
CM
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8
CO
r-.

CM
CD

05
CO
CM
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O5
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<
I

?

CO
CO
•t
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.0
•Cn

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CO CO
V V

CO Cn
CM CO
in in
N
•* CO
en co
in
d
.CO
;g
,""
>cd
00

o
CO
1 V

8
•*

CO
s
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a.
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1-
in
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V









S
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ฐ?
en h-
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s
Dissolved Mn


















c
o
I
CD
i
II
<
CO
Q.
•„ II
Ou.
O Q.
CO .-
O m
<7
"ca^Z
                                                       57

-------
cn
fc
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CO
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<
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<

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<

0.

z
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<
U_
Q.
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LL
<
U-
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g =
'•S
ป Sampling Loc
Parameter


t^

CL
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CM CM
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T- CM
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en

05
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t^ o>
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co
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4
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co •*
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CO CO






4
As (total soluble)







o o
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cn cn
CM i-
CM T-
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4
ปAs (particulate)







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V V

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V V
co co
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la
ฅ






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co co
co o
CO •*
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co co






4
>
CO
<

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CM
CO
CO
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CO
co i-
CO CM
cn cn
CM t~-
CM CM
(^ CO
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cn
CO
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co
cn
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8
fe
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m

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co co
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33
CO
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CO
c\i
in
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in
CO
0
S
1
CO
CO
•*
tn
(^
r~-
4
ฃ
I
i^.
o
CO
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in
cn
in in
o o
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CM in
co co
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f~ CM
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in
CD
CO
c\i
CO
K
^
•*
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co
CO
CM
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4
Total Mn







V V

V V

V V






4
Dissolved Al







O O
CO CO
V V

go
CO
V V

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CO CO
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Dissolved Fe






to in
o o
V V
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CM CM
CM 
-------
CO
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•* in
•;
3.
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CO
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1^ CM
co en
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co in
in CM
%$
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si
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CM
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in
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m co
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co in
i- t
CO CM
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in in
in
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CO
co
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CO
cri
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CO
CM
1
Total Mn






'v 'v

t— T—
V V

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'v V






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CD
a.
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o o
CO CO
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o o
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in in
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o
lalysis.
= after filtral
?<
2 if
Q) O
fl
(a) AsCaC03.
[b) Confirmed by sa
N = inlet; PF = prefi
                                                       59

-------
Tf
I
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 03
JD
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1




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10/14/98

S
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u.
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Parameter

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8

in
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CO
in
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in
CO
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co
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in
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in
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oo oo
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si
in
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1
in
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62

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o
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o o

ii

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co
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t
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in •*
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CO CO
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CO
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t
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CO CO
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CO
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in
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1^.
CO
in
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%

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CO
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in
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co
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18
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1
<
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CO
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co co
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W

o o
CO CO
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1
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1
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5









CM O
in in
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05 CD
CM T-



1
C
1
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CO
b

   c <
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8
                                                                                          ft

                                                                                          0 "
                                                                                          o u.

                                                                                          JD Q.

                                                                                          D_ rj

                                                                                          E .0

                                                                                          CO C
                                                 65

-------
i
CM






S


CO
JO

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1
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<
u.
n.
z

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CL

z

<

0.

z
u.
<
u_
Q.
z
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Sampling Loc
Parameter

in
o
|
in
o

II

8ง

II

in
o

1

fe
s
T—
s
T—
CO
o
1
ฃ?
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<

$
p
CD
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t
CM
CM
O
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en
o
I
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T3
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o>
1^
0
CO
CO
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h- 00
o o
CO CO
v- CM
co co

1^

K

CO
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t^
CO

Q.

o
CO
CM
CO
CO
c\i
in cj
CM CM
CO O>
CM CM
•* co
CM CM



CM
in
CO
CO
CM
in
CM
o
c\i
t
g

a
CO
CO
(0
1^
co
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•st- in

o o
V V



4
As (particulate)










in m
o o
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0 0
t^ (^
o o



4
3










co co
•* •*
h- CM
in in
CO CM
o o



ll
s
3

V
CO
&
o
CO

V
"tf-
O5
in
in
CM

CO CO
CO CD
V
•*
fe
00
O5
(M
1
Total Al

f
CM
in
in
en
o
CM

ง

CO
O5
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o
o

o o
co co
V V

oo in
co in
CO CO

05 h~
c\i in
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Tf
s
05
05
in
i
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CO
O5
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in
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CO
in
o
o
CM
0
ci
CO
in CD
in in
CO CO
ctS
CO 0
CO O
•>- co
co
CD
O5
in
C5
T-
1
c.
I











'v 'v

V V

V ^v



1
Dissolved Al
in ' •
i










o o
co co
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^y

o o
w



1
Dissolved Fe










co co
in in
CO CO

o to
CM 1-



4
Dissolved Mn

















c
o
nated.
: = after filtra
E <
f g
|1
m -•
a) AsCaCO3.
b) Sample contains
N = inlet; PF = prefi

                                                        66
                                                                                                                            ..:	:	::	1	.:.. :.::.

-------
O5
C3)
co
CM
JO
Q.

 cป
 c

"o.


 as
CO
 O)


3
 8
 (Q
o
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Y'- <•

A'-;

'<$'
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1
Y
y/
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-
1?
fil
,-,

Q
1"
CO
/'U.
it''
*-/
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^JVH

ซ
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--

".'?^
D_

\ vv
1'
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a.
z
|
ป,:, . Sampling LOG
Parameter
O
T—
ฃ
CM

88

O) O)
O 0

ฃS

o>
o

o

CM
8
8
1
1
ฐc
1
CD
U3
CO
-

ฐฐ
•r-M-
CM CM
CM CM


O
V

CO

CM
i
t--.
cq
H
'•5
'•&
O
CO
0
CO
CM
CO
o o
CO CO
o o
CO CO
CM CM
CO CO

CO

CO
CM
CO
CO
o
CO
CM
CO


in
0
CM
CO
CO CO
CM CM
O CO
co co
co in
CM CM




CO

co
c\i
CO
CM
en
CM
t
o
R
5
ed
3
i-O
••*•
CT

•r-
•r—
CCI CO
,,
T" O
m co
T— T—
CD in
CTl CO
m
CM
to
CO
CO
A
II
As (total)









co in

CM CM
m in
0 i-
cn CD



1
1 As (total soluble)










o o
V V
en co

m •*
O 0



'S)
a.
As (particulate)









o o

to m
o o
co co
O 0



1
CO









CD in
CO CO
co i~-

•>t in
CO CO



1
CO
"v
5?
C\l
cq
CO
r^
^
m
CO
in
CO

•r— T-
V V

CO CM
CM CM

as
CO
ง
8
1
i
o
•3
CM"
g

o
CO
V
m
1

CM
K

W

co_co_

CM CM
CM
CO
CM
ง
8
1
o
LL
5
CM
CM
0)
CO
CO
CM
CO
s
CO CO
in in
o o
CNJ CO
CO CO
1^ T-
CM CM
CO
in
in
cq
ll
c
5
\-










T- r-
V V

V V

••y -^



'a
Dissolved Al










o o

o o
co co
V V

o o
CO CO
V V



ll
Dissolved Fe









CO CO

o en
CO CM
CM *-




4
Dissolved Mn




•














8"
o
                                                                                                         g

                                                                                                         13
= after
S
iฑ
"S
Q.
                                                      67

-------
1 '!>
                          CO
                           CD

                          ~3
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                          I

                          JL
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8
T-

8

O
Y—
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8
S
T—
1
^
^
t






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t--
c\i
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V
CO
CO
CO
0
3
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?
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CO O)
r- h~
01 0>
l^ t^-
CM CVl
CO CO

!•-:

CO
CM
CO
q
CO
o
CO
CO
CO


Q.





CJ -r-
CM CM
•* U3
CM CM
o in
CM CO

CM

c\i
co
CM
o
CM
in
CM'
•*
CM
1

.


CO
co
(0
CO
in
CO
CO
CM
co
o
ป*•
1^
in in
CO CO
in en
O CO
•* o
T- 0
T— T—
CM
•*
I~-
(0
o
cri
i
t
^
,










co in
CO CO
CO CM
•* •*
•* in
en en



i
total soluble)
3.












o o
V
CM h-
in M-
O CD
CM O



1J>
particulate)
CO
<











•* •*
O 0
^ CO
o o
co en
o o



ll

^












co co
o en
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CO CO
CO CO



i
>
3


CO
CO
1
CO
K

V

o
o
o
e
t-- in
05 1-
t- en
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in -
CO
O3
CO
3
1
<
1


o
V
!
o
5i

?

o
l-~
CO

|

W

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in
in

•* r-
in in
CM CM
o
^
CM
CO
•*
s
1
ฃ
5


CM
in
N-
c\i
in
CO
CO
en
CO
r--
8
h~
Si
CO rf
CO CO
r~ co
88
CO O
in co
co in
h-
co
in
in
o
0
1
C
e












T— 1—
V V

~v V
CO
^v



1
solved A!

-------
                      APPENDIX B
Complete Analytical Results from Long-Term Sampling at Plant B
                           69

-------
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in
ca

q>
m
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co
s:


1
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rr

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m




CO
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CO
j 	 ..•<>:
i'

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CO


i





Q-

Z
LL
U.
Q-
z
LU
U.
D.
Z
U-
u.
Q.
z
1
1 Sampling Loc
Parameter



CO
03

CO
03

S
V-
T—
O
8
in
CM
S
ฐ
CO
CM
1
OO
o
T—
o)
"co
i1 • i "


v
CO
o
^
oo
i
oo
d
CM
i
CO
d
in
co
d
en
d
CO
^—
1
|
i .•

CO

CO

co
CO
CO
CO
CM
CO
CM
CO
CO
CO
CO
1-^
1^
CO

Q.


CM
co
CM
co
en
CO
5
CO
co'
en
CO
CO
CM
CO
CM
CM
CO
co
CM
CD
CM'
CM
co
t
o
ฃ


t^ CD
CM CM
CD •*

l-~ I--
00 h~
o
CM
CO
co
0
in
CO
o
co
CO
CO
^
co
CO
CO
10
T-
i
i


en en
CM CM
CO CO
CM CM
•* CO
en en









4
As (total soluble)



vv
O CO
CM T-
V- V
o o
V V









i
As (particulate)


co o
O T-
 d
CM i-










i
5.
	 Iv

co en
CM T-
0 f~
CM T-
CM CM
CO CO









4
1


f~ CO
co in
CO CO

co en
CM CM
in tn

co co
CO CO
ง
in
S
in
i
1
i
5-
CO
8
1
4
i
"i ' !J!
q

O O
CO CO
V V

o o
co co
V V

5$
s
o
co
V
in
S
1
ซ
CO
o
•9
ซ
m
4
Total Fe
'| V:

co in
o o
V
en en
00 00
t i-
i- CM
co co
in
CO
in
CM
in
en
CO
CO
co
in
d
CO
CO
CO
CO
co
4
Total Mn
1 -i

^f CD
OO CO
CO CO
h- CO
(^ CO
in in
in CM










4
Dissolved Al



o o
CO CO
V V

o o
co co
V V

o o
CO CO
V V









4
Dissolved Fe


in in
o o
V V
CO CO
in in
Is- CO
CM CM









4
Dissolved Mn
.'.•i..














d
= after filtrati
'1
Q.
•„ II
Ou_
oo.
3 if
w c
^ II
                                                   70

-------
03
C35
OS
CO
 O)
CO
CM
00
a.
"5.

 C3
CO
 O)

jj

 2
 CO
 
ฃ1
 CO
•••ฃ
-
r-g,
rง;

v^
l'
/*'
O>
f
"* l!~
&s

1
*•"',/
•
,-"
CO,
1

-
1
a
g:
"a.
,
\

' a.
*
— '


-',
a.
~
— *
•*
U.
n, .
ซ''

*
r

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z
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c.
f!
o o
So?

O CD
o en

t- O
CM CM

8
o
en
en

S3
o
ฃ
o
s
8

88

SS

sl
L
B
&

ฐฐ


10 co
co co

?
CM

co
co
i
00
C3
O
CO
T- 1—
ฐฐ
o o

00 i-
co t^
ฃ
'o
1
CO CO

CO CO

10 to
CO 00


to


00
CO
s
CO
00
^
l^ h~
ป*


00 00

a.
00 h-
CM CM
00 CD
CM CM
to co
CO CO
f-
i—
O
CO
CO
co
0
CO
en
CM
IO
CO
en o
CM CO
en oo
CM CM
CO CO
CO CO
_i
E
O

CM
CM
to
CO
*-
T- |-~
•<)• CO
N CM
to 10
CD T-
^- co
CO
00
00
to
CO
CO
o
co
CM
00
^
I






CO 1^
CO CO
oo oo
CM CM
O CD
00 00
T— T-









1
As (total soluble)






co i-
v
en ••*•
CM CM

vv









1
As (particulate)






CM CM
o o
CO CM
o o
**
O 0









1
=•






co to
CO CO
CO IO
CM CM
CO CM
X CO









1
I
CO
T—
CO

IO
ง

CM
0> i-
CO f-
co co

CM en
งT-
IO

^f en
i- O
CM
CO
CM
5
to
"

CO
O)
to

o
to
s
i

o
CO
V

'5

CM

o o
CO CO
V V

o o

CO CO
CM CM
*
;ซ
1

"
CM
co
co

CO
: en
. _i
1
00
o
N
IO
^
00
h- oo
o o
IO CO
•* CM
•* •*
•t CO
en
c>
co
co'
CO
CM
to
V
CM
CO
o
en
CO
1
c






CM 0
O5 O
"3- IO
CM T-
O> O
CO N-

V V









1
Dissolved Al







0 O
co co
V V

0 O

o o
VV









s
CD
U-
1
a






IO IO
O 0
V V
oo oo
00 00
r- co
CM CM









1
Dissolved Mn

S
                                                      71

-------
 o
 t^

 CD


1
 O
 *-*
 8
 CO
 P>


 "5.



 I





 ฃ
 GO
 M
 s>
 CO
 <

 s
 Q>

 ?


CO
0>
a
s
III
1


II1 II 1
CO
o>


, ฃ:,„
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I

1
Q

ft

Q_

z

<

a.

z
u.
<
U-
Q-
z
ft
LL.
a.
z
|
w g
o
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05
Y—
0
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en
T-

cn en

CM
o
0
CO
en

8
T-
1
1
ง
s
*—
0
T—
s
1
.2-
]c
"3
26
<

?o
V
to tn
o o
tf CO
•* •*

o
V
0

co
•*
^
h-
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?'
en
C3
co
CO
3
S-
TO
e
H
CO CO
1^- C-
co co
r- r-
CO CO
co oo
CO
i~-
co
t~.
•*
00
CO
l^
co
i^
•>t
CO
in
l^
CO
t^
CO
CO

a.
in CM
CO CO
o en
CO CM
1- O
•* •*

CO
Oil
CO
f~
CO
o
CO
CM
co
I--
CO
en
CM
co'
r-
eo
1
g

CO

M-
co
CO
i- in
CO CO
in co
in ^i-
O CO
CO CO
c-
CO
en
in
en
r-.
CM
co
in
CO
in
T—
1
I






co co
CO CO
CO f-
CM CM
co in
en en






1
1 As (total soluble)






T" T-
d d
V V
i^. en
CM -^

o o
V V






1
As (particulate)






T— ,—
??

?]
CO
<
CO
s

ง
CO
in
S
CO i-
Sa>
CO

CO O
CO •ป—
in in

co in
r- r-
C3
K
S
TT
oo
••fr
oo
0
CM
CO
(0
ES
g
1
1 Total Al

s

?
CO
s

งs
V V

o o
co co
V V
CM •*
Sfc
o
^
o
CO
V
CM
s
ซ
•*
ง
s
CM
i
[Total Fe
in
?
•*
I--
1^
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in in
0 0
h- en
CM O
r- CO
co in
CO
d
eo
d
in
in
I^
d
o
•*
00
1
c
H






en CM
SS
r^ -r-
CO 1^
t^ t-~

V V






i
Dissolved Al







o o
co co
V V

o o
CO CO
V V

o o
<3 V






1
Dissolved Fe






in in
o o
V V
oo h~
O) O5
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•* •*






^
Dissolved Mn
















5
= after filtrati
ft
cf
o
1
•g
D.
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Ou.
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co .-
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< II
Ifz
                                                      72

-------
OO

O)
oo
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1

S



i_
CD


"E
0)

S.
CD



m
 cป
 c

"5.


 co
CO
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 D)
 CO
 o
CC


1

is,
 CO
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8

f-<'
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Q.
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z
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1

88

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ii

0

in
o

o
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o
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o
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8
o
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1
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t
T— T—
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CO 00

T- CO
C\J CM


CM
i
1^
C>
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3
t
ซ
H
•* •*
r- i--
•* Tf
h- 1^.
•* •*
00 00
CO
h~
•*
(^
CO
CO
co
i--:
co
(^
CO
00
CO
i^
co
h-^
CO
CO

o.
CM CM
co co
co co
•* CO
00 0>
CO CO
CM
CO
CO
CO
en
co
co
0
CO
O)
co
t^
CO
CO
CO
en
CO
t
O
g
•*
CO
in
l^.
CM
CO
CO ^'
CO Kl
CO CT.I
(-ป [v.
co o
CO 0-.I
o>
CO
0
in
in
CO
0
•^
CO
in
CM
CO
"&
I
*






co co
CO CO
•* co
co co
CM •*
en en






1
As (total soluble)







o o
V V
•* CO
•* •*

o o
V






i
As (particulate)






in 10
O O
in in
0 0
CO CO
O O






1
3






00 00
CM CM
en oo
CM CM
CO CO
CO CO






1
g
3
CO
s

8
CO

5
T-
o co
co i-~
in in

S fc
is
1^ CO
•^f 00
00 CO
h-:
ฃ
1
0
fc
o
s
CO
ง
f~
s
4
1 Total Al

":

^
|
CM i

O O
co co
V VI

80
co
V V;
f- •*]
in co
N l^1
j
<
00
S ;
o
CO
V
o ,
•9 ,
CO
fc
4:
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T— ^~
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co co
i^
0
t^
o
o
•*
T—
in
CD
CD
d
o
i^
1
c
2
ฃ






CO CM
CO CD
^- CO
co co
SCO
CO

"v *v






i
Dissolved Al







•9*9

o o
CO CO
V V

co co
V V






1
Dissolved Fe






in in
?
-------
CO
•I—•


I
Q



i
cn
cu
DC

15
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m
o>

a
a


CO
s.




1?
1



1

• 	 "
10/15/98 ,

S
1 Sampling D



Q.

z



u.
Q.

Z
*
u.
D-
z
il-
ia.
D.
Z
a;
o
1
[Sampling Loc
Parameter

CD O5
T- Y—

O5 CO

•* co
CM CM

CO

CO
Y—

a
1
1
a
CO
o
o
i
1
.ฃ>
c
1
T— T—
vv
CO CO
o o
CM CM


?
CO
0
„

i
CO
o
T-
5
f.
o
oo
CM
ID
'u
&
3
O 0
00 CO
CM O
CO CO
CM CM
CO CO
N

00

^
00
TO
5
TO
CO
2
5
TO
CO

Q.
T- CM
TO TO
O O
TO TO
•* in
TO TO
^
TO
TO
TO

TO
TO
0
TO
TO
00
CO
CO
CO
t
g
00
'-
in
in
CO
o
CM
00 CM
cn o
TO •*
CM CM
T- T-
CO Iป-
cn cn
T- Y-
CO
cJ
0
in
05
cn
TO
in
CO
CO
1
I
cn







0 0
in in
05 05
•* CM
cn cn






1
As (total soluble)







ฐฐ
co cn
CM CM
•* in
o o






1
As (particulate)






TO TO
O O
TO TO
0 0
•* •*
O O






ll
5.






00 CO
O5 O5
CM CM
cn cn
o co
O5 CO






1
>
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CO
CD

g

ง
CO 
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CO
cn
CO

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m
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DC



1
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CO
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f
y.t

A
^00
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2
in

-
;
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r>
CO j
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v-









~i
a
CO
c
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2
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a.
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tQJ
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T—




CO




Sj
t?

1
CM
0

CO
0
in


';-'

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V
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0

CM
Y—


o

CO
0




o
Tซ




1-

'•5
!a
3
00
f-

00


CO
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"
"'f,


^
^.

00
!"•••

en
[^

00
I^

00
f-




CM
CO






a.
en
CM

en
CM
in
CO


_^
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o
co

0
co

o
CO

o
CO

o
co




,-
co




'&>
H

O
R
o en
T- O

en co
CM CM
O CM
•^ t~.

L\^ 1
^



CM
0

co
CM


^

m
o

CO
o




CO
CO




1

I
CO f~-
CM CM

CO 0
CM CM
1— V-
T- CO
s?


, f.

^! j-

























1

As (total soluble)

o o
V V

CO CD
o o

vv
<

ss
,-c.-
>v ' f
,
























\

As (participate)

0 O

•* CO
o o
^ •*
o o
~>?




. - •
























_l

=;
a> co
T- C\l

en i^-
^ ^
r~ en
en co
*^*v ~



u/

























4

f
•* CO
en en


a co

CM i-
n o
:Y,,:




i <,
^
0
en

j*
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CD
01
in
en
fe

CO
en
CO




f-
in
t~-



1

1

co co

•* o
S"

SCO
CM
I^V



N
v / s

o
v

o
co
v
CM
CM


O
CO
V

o
CO
V



0
m
in



i

n
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en |~-
0 0

TfT-
CO CO
in ro
^- *-
-
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',
/""'
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m
o

CO
•*


CO

in
o

CO
o




7-
in




4

c
S
CM cn
S S


ฐฐ

V V
s ^
a,

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1

Dissolved Al

o o
CO CO
V V

""

V V



-


























_1

Dissolved Fe
in in
o o
v v


CM CM
CO CM


- '*

'


























1

Dissolved Mn




























, c
>. o
CO 4=
"O CO
"o =

en CD
C 4ฑ
> *
fll
LL
C <
a..
H .2
o oj
3 V-
(a) AsCaCO3.
(b) No sampling c
IN = inlet; PF = prc
                                                     75

-------
 O)
 O
a:

15
.9

m
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I
v;=.:=
T—


'"-' 	 • 	 =
Bll2/24/98^
il - 1. .
i nil
	

	
i



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n—


to
0
s
LL
LL
0.

*
*
U-
D.
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LL

LL
Q.
H

<

Q.

Z
sn
In
! Sampling Loc
Parameter








o>
"
o
CM
*

ss

T— T—

T— T-
1
"c
1








C3
V

in
o
0
Cvj

vv
co r-~
o o
CD en

1—
H








5

5
co
CO
00 CO
r^ r^
00 CO

co co
CO 00

O-








oo
CM

en
CM
CM
CO
05 CM
CM CO
CM i-
CO CO
CM CO
co •*
t
o








in
c\i

5
|^
CM
'-
CO
CO
CM
2
4
I
3.


















i
As (total soluble)


















4
As (particulate)


















4
CO


















4
CO








co
c\i

ง
in
t^
in
E5

*

Sj
4
1 Total Al








o
co
V
8
V
in
9

o
co
V

0
CO
V
CD
CM
in
4
[Total Fe








in
o
V

CO
CO
o
CO
co
o
f-

CD
in
'S.
a.
Total Mn





-












4
Dissolved Al


















O)
3.
Dissolved Fe


















O)
Dissolved Mn








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sj.
uses alum ir
;i5/98a<0.1
01
o
.c
a>
1
1
2 c.
o -J!
.ฃ !2 "ฃ'
ra-c ..
*O *~* ^"-
(a) AsCaCO3.
(b) The plant stoppf
(c) No sampling duf
IN = inlet; PF = prefi
                                               76

-------
0)
CD
00
CVI
O
 co

 CO
CO
jg
0.
 O)
"o.
 co
CO
 D)

jj

 2
 CO
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 15
 o
 '
 co
3
^p'
"<•> ,
\
y'
i
?'i
O i
'
/^

s"
&\
'ป
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o
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/-' J/
\
8-
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0

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a
m
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5
4. y

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u.
EL
„
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u.
<
u.
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z
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IL. -
0.
z
as
f 'C
o>*
c
I*!
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05
™
fe

^ lป-

^ CO

STO

t
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T-
^;

TO
00
tซ.
T—
T—
co
1
I Alkalinity
i
00
CD
CO

O O
V V
i- O

!•ป 00
CM CO

o
V
00
o
CO

3
CO
o
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1
&
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•*
i-:
•*
r^
TO
CO
•* •*
1*- C-
•* •*
t^ r-
TO TO
00 CO
•*
f~
•t
CJ
•*
C\i
CD
c\i
o o
TO TO
0 •*
TO TO
05 CO
TO TO
CO
CM
t~-
CM
CM
TO
CO
CM
CO
CM'
in
TO
=g>
g
CD
TO
uj
0
CO

a.
As (particulate)









•* •*
o o
CM CM
O 0
•* •*
O 0



1
I









o> en

CM CM
CD (O
o o
CM CM



1
>;
(/)
<
en
ง
o
CD
CO
in
co
CO
^
TO
•*

cn
SI

TO
TO
CM O
99
li
CO CM
fcS
O
LO
TO
CO
>*
•*
9
4
<
K
?
in
c\i
TO
CO
s

"

o
TO
V

?

งง
V V
i~- in
Sง
t^
O CO
TO^
O
CT
cn
TO
•*
TO
s
4
ฃ
eg
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h~
d
CM
CO
•*
CO
co
o
cn
*3-
t^
TO
0 t-

CJ TO
in in
in •*
TO TO
in
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g
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                                                 78

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                                                   79

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i
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1
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•i: iiiii f
                                                                                  82

-------
                      APPENDIX C
Complete Analytical Results from Long-Term Sampling at Plant C
                           83

-------
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g
i
1

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S, II
Oii.
oo.
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                                                               84

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g ""
5 f.
-€|
 cn
CM CM

n 5
""

5S


co
CO
"

ง

U5


t—

?


CO
CM
co

1


w
cu
i
10

to
CM
2


0


88
cn CM
? ?


O CM
T— O
CM CM

cn
^
^*.


s
1—

8

CM
5
CM
cn
in


s

g
I"


Ca Hardness

O
CM

in


8


\*

i in
> 0


j?


^_
i^


o
CM

S

CO
CO
cn

CM
CO


CM

^
1"


ii 	
Mg Hardness

S3

t


CM

CO
^
^
CO
CM

co
8

CD O
T- C\
^ ^—

i- cn
^ CO
cn in
CO •*
CM CM

r-
co
in
co

cn
CM

i


I
















^
^- ^*
T-* 1"~

CO O)
00 CO
^N
S!w









4

CD
As (total solub

















D O



O O
V V
CO CO
1- CM









1

,_,
As (particulate
















in •*
0 0


in in
O 0
in in
CMS!









1


1
















cn o
CO •*
'

CO •*
r-~ co
CO i-
ฐv









1


s
^
CM
o
!n


V

CO
00
00
5


T"

O 0
m [^
*

in co
O CM
CD CO

'v 'v

ii-~
!-^
CO
:5


V

i


:|

o

co


0
in
CM

0

o


o
cn
CM

o o
w *w


CO S

Is
CM CM

ง
V

1


in
CM
4


s.
I
^
co
f-
cn


|

N
s
^.
CM


CO

CM CO
^t" ^J"


^^
CM CM

5S

^
CM
CO
CO




4


Total Mn
















CD CM
CM CM
• •

cn cn
m m
co co

V V









1


	
Dissolved Al

















o o
w *w


V V

•* co
CO C\
in in
CM CM








4


Dissolved Fe
















cn c
i- CM


co cn
i-~ f-

T— T—









4


Dissolved Mn




























c
E?
B
•fe
II
LL
|
P
Q.
oct
CD • -
o ts
ฃ •-
u
                                                             93

-------
'!', • '•


f, "" i
t ' :
!:-;:i ' '
tit'.i
	 "
""in'1'1 i ,T"*
of
	 T™
~:,, a.
	 r=c
o
"|
^
i_
• 	 • 	 5
iii'i'S.
	 :". O
IfM" ^
Q.
.i
&
"ฃ'.: 0)
r:vt-
ra
.;::-;- .ง
'.' ":,;^
tl
-I
*
si
rfijit. a>
,1
'"!
:. ::

I
": :„::_:

I



8
1



!

(D
s.
i '. ;j|;
'„' !|

%
u.
0.
z
u.
<
u.
0.
z

!fe

a.

z
Ife
u.
a.
z
gl
1 Sampling \jxs
Parameter


1
CM
S
1
oo a
II
ss
•
T3
'•B


cq
00
co
co'
CM
r^
CO CO
co co
CO CO
cri cn
CM CM
r^ h-
co
cn
in
CO
CO
c-
00
(^
co
CO
CM
r--:

i.


s
T—
CO
in
o
CO
5 in
4 ^
10
ss
CO CM

a
1—

SI
CM

3
5!
CM
in
CO
8
CO
V
Total Hardness


iv.
S
CM
d
r-~
fe
05 CM
S3
in CV
t^ CD
co co
f- CM
X> CC
CM
co

8

in
CM
^
f-
8
s
1
Ca Hardness


O
JE
00
•* CO
8?8
C~ 00
sis
CO ,3.
c-.
i^
00

CO
T-

m
CM
en
Y—
8
in
55>
Mg Hardness


C-;
CM
CO
CO
CM
CO
8
in
CM
f-
cS
CO
s
co cvi
00 CO
-*• co
t- O
co co
i- CM
O Cn
•* co
CM'
CN
EM
in
CO
CO
o>
a.
3








f- h-
CO CO
in in
O t-
co co
CO CM
??



1
As (total soluble)









ฐ^
en i-
ฐ<3

^^



i
As (particulate)
ii:1'







CO CO
0 O


•* o
1^ 1^
co co



1
ฅ








•* •*
CO 03
•
CO
<
;!!: ''

o
CO
cn
S
CO
(N
o
CM
co
CO
CM
in
co cn
CM CO
Tf CO
CM 1^
in •*

V 'v
cn
N
in
ง
^
1
1 Total Al
...
lit!
.: !

CO
in
in
5
s
CD
CM
CO
m
ง
i'
co"

88
V V

in in
t ••s-

CO CO
i- OO
in *i-
cJcJ
CO
CO
CO
g
PI
in
CM"
1
ฃ
I
'•' 1 :

co
CO
CO
oi
^_
h-
CO
CM
K
r-~
i^
•* >*•

i- O
;=;:

II
CO
si
CM
CO
^
^)
a.
Total Mn
1 •!:








V V
in T-
co •*
CM CO

'v V



1
Dissolved Al









O O
co co
V V

o o
CO CO
V V

CM" CM"



i
Dissolved Fe








N i~-
0 0
CM CM
•* •*

CM i-
n in



1
Dissolved Mn
1 i
i













c.
o
1
S
H
1
II
U-
<
I
1
V, 11
Ou.
OD-
S%
**.
"a-z.
94

-------
CD

O5

O)
O)
en
O)
co
CM
O

•E
 ca

a_

 ro


"a.

 CO
(73

 E
 TO
 o
 3
 CO
 CD
cr

15
 o
 03

5

O4

6

.2
A
 n
&
/
X
,•$,
O3 '
n
ป•
,•ง;•
^w1-'
?" j
V;IV''*
.ปv
'*en'
3S
ฐ"f"
"" ^ฑ
t^=
•'Uy4
&*&-
^^ l
^S-"'

,ง'
-••&
j-if*

^^u
TS
,'•>"&
^-''
V?'
-ซ
'% Sampling Da
,u/
,<
rgff
% "'^
>,/*"V
f ^
i-
^
;•'
"-#
• •;'?,'
<"Vฐ r*
*

: u. .
Q.I."
• V'
" ,R~
xtt
•l'< ,
f[f
,,'•'•
:z:;-
•'<',
&.' '
','U.
~CL
^\\-
,M>!
''•Hz
'•',-; •*'**
•' c
ง5
ss' '
a
•J
S.1
Q.^
<& Cl>

CM
r^
CO CO
CO CO
h- r^
CO CO

CM i-
K i--^
CM
0>
05
CO
CO
t^
CM
r-
1^
CO
o
05
CM
h-:

a.
O5
CO
1—
CO
T-
o>
o
co
T- in
CO CO
co co
O 0)
CM T-
00 O5
ss

CO
J

r-~

8

co
T-
co
fe
T—
CM
CM
o
co
1
I
ฃ
O5
CO
•*
l^~
CD
co
0
s
t ^
o P
CD •*
35 ro

XI CO
T— T-
05
5-
h-
O5
in

fe

fe
en
s
O5
o
in
O)
i
Ca Hardness
N
•*
ca
co
ฃ
ง
•* CO
T" T—
o> f-
o o

ex> r-
I-- f—
T" T—

CO
O

ฃ

CO
T—

o>
ง
3
m
1
II 	 	
II Mg Hardness
•t co
•* •*
o en
•* CO
o
CO
CO
&
05
s
1
I
3







co l^
r~ t^
•* CM
N CM
CO CO
CO CO
CO CO
CM CO
co8



1
As (total soluble)







,_ T_
"??
CO CM
CM in
CM T-
O CO
CM m
en in



1
As (particulate)







h- CO

03 i-
O i-
in r-
ss
O) CO
88



*&
3







I-- in
in co
in i-
co co
CM CM
tซ- CO
•* CO
^ ^
o o
V V



1
>
3
in
co
co
te
"v
1--
cd
CD
fci

i
't
^ ^v
in co
in o
CM CO

^ 'v

^v 'v
o
in
CM
in
CO
;s
1
:<
I
o
CO
V
i
^
in
CM"
•*
ง
CO
CO
I--
8
CM"

o o
^^

CO 0
•? 5-

in 'tf-
•* 00
O5 CO
CM"CO"

O5 1-
co co
CM" CM"
o
V
1
CM"
1
ฃ
1
CO
co
co
t^
s
^~
•*
(^
CO
CM

s
CM •*
CM 1-
CO O5
05 ro

a> i-
co •*

ss
CM
CO
CD
CO
in
CO
T-
1
c
1








V 'v

^v 'v

V V

^v ^v



1
Dissolved Al








88
V V

88
V V

T- h-
O> t-
co o

co in
•* •*
CM" CM"



ll
Dissolved Fe







en T-
o *-
.,_ T-
CM CM

2<2

co •*
CO CO
1— T—



"a
Dissolved Mn















after filtration
ii
!4
b~
g
?
f
~2
Q.
II
LL
O.
O
1
(D
CO
. II
Orr
o <
c3t;

-------
illi"'
I	') !';!
                      C
                     T3
                      O
                     O
                     •e
                     _co
                     Q.
                      TO

                     I
                      <ฃ.
                      t
- 	 ' 	 : 	 ::-
1
I

1
	
- ' 	 "•

'• 	 :":"-.:
$ 	
o

	 :::::

	
1
"
	 &
1 ! = ==J
Sampling Da

ife
u_
0.
Z
$
u_
a.
2

%
u.
Q-
tt
<
2

U.
<
u.
a.
2 ;
t
13
Sampling Loca
Parameter

•*
03
CM
a
V-
•*
CO 00
II
8S
T •<ซ•

CM
CD

t^
O>
CO
CM
"*
O)
03
00
Si
CO
o
•*
1
ฃ?
'd
1
5

•*
O
CO
o
s
T- O
ui in
CM O
?ฃ?'
ฐ. ฐ.
m co
CO
o
CM

CO
CO

CD

m
CD
CM
00
o
EM
3
ฃ•
•o
S
3

CD
CO
in
CO
CM
h-:
O CD
CD 03
CO CO
CD CO
CM CM
1^ (^
CD
CO
CD

N-
f-

CM
r-^

i^
03
CO
03
N:

Q.

UJ
O
Si
EM
co
r~- co
co co
3ง
T- V
[-~ in
 o
co CD
in if>
•* CM
STi-
CO
o r-
CM CO
CM •>-

CO CO
to
CO
•
I
$







CM O
1^ CD
CD CO
CM CM
CM CM
T- CD
CO CO
CO CO
CO t^
S3



ll
As (total soluble)







T- CO
?ฐ
1^ 1^
CO CO
CM i-
0t
CM
S'
^v
00
CD
CM
CO
ง
CO
Sf
CO
T- T—
^~ V
0 t^
CD N
•*
•^ CM
-V-M

V "v
o
CO
CO
ฃ
v
O)
a.
<
H

0
fe
1
i
CM"
s
CO
in
in
g
CM"
t^ CO
Sc^

sฃ
St-~
K CD
CM" CM"
CM •*
O> f—
CM" CM
o
co
V
1
ff
CO
CM"
_i
D)
i
Total Fe

co
o
S
ฃ
CD
f-
1^
ง
in in
CM CM
CO CM
SSi

fcS
T— If—

^p
h~
r~
cj
CO
f~
^
c
ฃ








T~ T—
"v V

'v V

V V

T7 'v



^
Dissolved Al
i







o o
co co
V V

co co
V V

CM CO
CO CO
•* h-
Sen
CO
CM" CM"



^
Dissolved Fe







r^ co

CM CM
CM CM

CD CO
|-~ CO
->— 1—

CO CO



1
Dissolved Mn















ifter filtration
II
u.
<
c
g
^
1
0.
ll
LL.
0.
O
?
S
a) As CaCO3.
N = inlet; AR = afte

                                                                               96

-------

-------
United States
Environmental Protection Agency
National Risk Management
   Research Laboratory, G-72
Cincinnati, OH 45268
Please make all necessary changes on the below label,
detach or copy, and return to the address in the upper
left-hand corner.

If you do not wish to receive these reports CHECK HEREEH ;
detach, or copy this cover, and return to the address in the
upper left-hand corner.
PRESORTED STANDARD
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          EPA
    PERMIT No. G-35
Official Business
Penalty for Private Use
$300
EPA/600/R-00/063

-------