United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/ROjf-90/033
June 1990
Superfund
Record of Decision:
Northwestern States Portland
Cement, IA
-------
50212.101
REPORT DOCUMENTATION 11. REPORT NO. 2. 3. Recipient'l Acc"lion No.
PAGE EPA/ROD/R07-90/033
4. TItle and Subtitle 5. Report Ol'e
SUPERFUND RECORD OF DECISION 06/26/90
Northwestern States Portla~d Cement, IA
First Remedial Action - Final e.
7. Author(l) 8. Performing Orglniution Rap\. No.
t. Performing Org8lnlution Heme and Add.... 10. ProjectlT88.I./Work Unit No.
11. Cont..c~C) o. a.lnl(G) No.
(C)
(G)
12. Sponeoring O.ganization Heme Ind Addre.. 13. Type of Report & Period Covered
U.S. Environmental Protection Agency
401 M Street, S.W. 800/000
Washington, D.C. 20460 14.
15. SUPPlementary No".
Ie. AlleIr8ct (Umfl: 200 word.)
The Northwestern States Portland Cement site, a cement manufacturing facility, is in
Mason City, Cerro Gordo County, Iowa. Calmus Creek flows between the Northwestern
States Portland Cement Company (NWSPCC) facility and another cement manufacturing plant
facility located just north of the site. The site includes a l50-acre area named the
West Quarry where NWSPCC disposed of 2 million tons of waste cement kiln dust from 1969
to 1985. Local ground water and surface water have been impacted by elevated pH levels
as a result of waste cement kiln dust disposal in the West Quarry. Two seeps emerged
from the northeastern portion of the West Quarry in 1979 with high pH water from the
seeps flowing overland into Calmus Creek. In 1984, the State found elevated pH levels
in Calmus Creek downstream of the seep area, and in 1985 ordered NWSPCC to cease
discharge from the seep area to Calmus Creek and to cease kiln dust disposal in the
quarry. In 1987, NWSPCC installed an acid-neutralization system to treat the seep
water and to dewater the West Quarry pond, the open area of the quarry filled with
approximately 420 million gallons of water. This action has significantly decreased the
contact of the water with the kiln dust and, as a result, pH levels in the quarry water
have declined. 'This Record of Decision (ROD) addresses the contamination source, the
(See Attached Page)
17. Doc:ument An8IyaIa .. DHcr\pIDI8
Record of Decision - Northwestern States Portland Cement, IA
First Remedial Action - Final
Contaminated Media: gw, sw
Key Contaminants: organics (phenols), metals (chromium, lead), other inorganics
(waste cement kiln dust)
b. Idtntltl8nlOpen.End8d T-
c. COSA T1 Fl8ld/Group
tl. Avallabllty SI8t8ment 1 t. Security Cle.. (!hI. Report) 21. No. 01 Plge.
None 42
20. Security CI... (!hI. Page) 22. Price
lIII"'In..
(4.11)
(See ANSl-Z38.1')
See Ine!ruel/one on Rell8-
(Formet1y NTIS-35)
De~lofCO~08
-------
EPA/ROD/R07-90/033
Northwestern States Portland Cement, IA
First Remedial Action - Final
Abstract (Continued)
cement kiln dust disposed of in the West Quarry, and the resulting ground water and
surface water contamination. The primary contaminants of concern affecting the ground
water and surface water are organics including phenols; metals including chromium and
lead; and other inorganics including waste cement kiln dust.
The selected remedial action for this site includes continued acid neutralization of the
water from the dewatered West Quarry, followed by discharge of the neutralized water to
Calmus Creek; construction of a permanent drainage system in the dewatered west Quarry
to collect precipitation runoff and ground water inflow to the West Quarry, followed by
onsite treatment of contaminated water prior to discharge of the treated water to Calmus
Creek; installation of bedrock dewatering wells to collect contaminated ground water
beneath the West Quarry, to prevent migration of the contaminated ground water from the
site, and to maintain ground water levels below the kiln dust; installation of kiln dust
dewatering wells, if necessary, to facilitate kiln dust dewatering; capping of the West
Quarry area containing cement kiln dust; pumping and treatment of ground water; and
monitoring of ground water and treated discharge. The estimated present worth cost for
this remedial action is $2,037,129, with estimated O&M costs of $210,000 for year one
and $65,000 for subsequent years.
PERFORMANCE STANDARDS OR GOALS: Discharges to
limitations including pH 6.0 to 9.0 and phenol
meet State ground water action levels and SDWA
lead 0.05 mg/l (MCL), and pH 6.5 to 8.5 (MCL).
Calmus Creek will meet State effluent
0.05 mg/l. Treated ground water will
MCLs, including chromium 0.05 mg/l (MCL),
~
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RECORD OF DECISION
FOR
NORTHWESTERN STATES PORTIAND CEMENT COMPANY SITE
MASON CITY, IOWA
PREPARED BY:
IOWA DEPARTMENT OF NA'IURAL RESOURCES
June 20, 1990
-------
1.3
RECORD OF DECISION
NORTHWESrERN STATES PORTI.AND CEMENT COMPANY
MASON CITY, IOWA
Declaration
1.0
Site Name and Location
Northwestern States Ponland Cement O>mpany, Mason City, Iowa
1.1
Statement of Basis and Pur;pose
This decision document presents the selected remedial action for the Nonhwestern States Ponland
Cement O>mpany Superfund site located in Mason City, Iowa. The remedial action was chosen in
accordance with CERCLA, as amended by SARA, and, to the extent practicable, the National
Contingency Plan. This decision document explains the {actual and legal basis (or selecting the
remedy for this site. .
The Iowa Depanment of Natural Resources concurs with the selected remedy. The information
supponing this remedial action decision is contained in the administrative record for this site.
1.2
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, it not addressed by implementing
the response action selected in this Record of Decision. may present a current or potential threat to
public health, welfare or the environmenL
Description of the Remedv
The se!ected remedy consists of the following actions:
.
Dewatering of the West Quarry which contained high pH water, acid.neutralization, and
discbarge to Calmus Creek. (Action completed September 1989.)
Coastrue:tion of a permanent drain system in the dewatered West Quarry to conect
precipitation runoa and groundwater in1low to the quarry.
.
.
Placement of an engineered clay cap over the area of the West Quarry filled with cement kiln
dust to minimize intUtration through the kiln dUSL
InstaUation of bedrock dewatering wells to collect contaminated groundwater beneath the
West Quarry, prevent migration of contaminated groundwater from the site. and maintain
groundwater levels below the kiln dUSL
.
2
-------
.
Iostallation of Id1n dust dewatering wells, if necessary to facilitate kiln dust dewatering. (It
is un1.ikely that this action will be necessary.)
.
1)'eatment of contaminated waters to meet Iowa NPDES discharge permit limits with
discharge to Calrnus Creek.
.
Assurances that the dewatering system will be operated in perpetuity to maintain isolation
of water from the waste kiln dust and collect and treat any contaminated water which is
generated.
The selected response action constitutes final action for this site. The selected response action
addresses the principal threats of contaminated surface water and groundwater and the source oCwater
contamination, the waste kiln dust The existing contaminated groundwater will be removed and
treated thus preventing ofC.site migration. The waste kiln dust will be isolated from water to the
extent practical to minimize production of contaminated water. Any contaminated water which is
produced will be collected, treated, and discharged.
1.4
Declaration of Statutory Determination
The selected remedy is protective of human health and the environment, complies with Federal and
State requirements that are legally applicable or relevant and appropriate to the remedial action, and
is cost-effective. This remedy utilizes permanent solutions and alternative treatment (or resource
recovery) technologies to the maximum extent practicable and satisfies the statutory preference Cor
remedies that employ treatment that reduces toxicity, mobility or volume as a principal element
Because this remedy will result in the source of hazardous substances (kiln dust) remaining on-site,
the five year review will apply to this action.
~L:~STRATOR
ENVIRONMENTAL PROTECTION AGENCY, REGION VII
b-2,6-9{)
DATE
"
Concu'rred on by:
~~~--
STOKES, ADMINISTRATOR
IOWA DNR, ENVIRONMENTAL PROTECTION DMSION
6~O
. DATE
3
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Decision SammaIy
2.0
Site Name. Location. and Description
The Nonhwestem States Ponland Cement Company (NWSPCC) is located in the south halt of
Section 33, Township 97 North, Range 20 West of the Fifth Principal Meridian and in the north halt
of the Northwest Quaner of Section 4 Township 96 North, Range 20 West of the Fifth Principal
Meridian, in Mason City, Cerro Gordo County, Iowa. (Refer to Figures 1 - 3.) The site is located
on the north side of the Mason City residential area. Another cement manufacturing plant is located
just north of the NWSPCC site with Calmus Creek between. Calmus Creek flows to the Winnebago
River which is less than a mile east of the site.
2.1
Site Historv and Enforcement Activities
The NWSPCC facility has manufactured cement since 1908. An area referred to as West Quarry site
was mined for limestone, a raw material for cement production, until 1950. The West Quarry had
reached a depth of approximately 40 feet and covered about 150 acres. In 1969, NWSPCC began
using the West Quarry for the disposal of waste kiln dUSL When disposal activities ceased in 19&5,
approximately twO million tons of kiln dust had been placed in the quarry and the quarry's unfilled
area bad been reduced to approximately 40 acres. The open portion of the quarry filled with
approximately 420 million gaIJons of water, known as West Quarry pond. (Refer to Figure 4.)
NWSPCC personnel began a pH monitoring program of the water in the West Quarry in April of
1974 in response to a change in color of the Quarry water. During April. 1974 to January, 1976 the
water in the quarry slowly became more alkaline (pH increased from 8.0 to 8.7). The quarry water
pH rose sharply following January 1976, increased to 11.8 in April, 1976, and leveled off at about 12.5
in 1980. The increase in pH is attributed to the breakdown of the natural buffering system which was
sustaining the quarry water at a near-neutral pH. In response to quarry dewatering initiated in 1981,
current pH levels are about 10.5.
In 1979 twO seeps emerged from the northeastern ponion of the filled West Quarry (Refer to Figure
4.) High pH water from the seeps flowed overlaDd into Calmus Creek. In 1984. the state initiated
a study of Calmus Creek and found pH in the creek elevated 2.0 pH units downstream of the seep
area. In April 1985, the state ordered NWSPCC to immediately cease discharge from the seep area
to Calmus Creek. NWSPCC was also ordered to cease kiln dust disposal in the quarry and to conduct
a hydrogeologic investigation.
In May, 1985, as a temporal}' solution to control groundwater seeps from the West Quarry, NWSPCC
install~ twO groundwater extraction weJls in the vicinity of the seeps. The water that was coIJected
by the weUs was circulated back intO the West Quarry pond.
NWSPCC completed. bydrogeologic investigation of the West Quarry in August 1985, Their
conclusioas included:
.
Re&fonaJ groundwater flow was nonbeastward towards the WinDebago River.
.
Loca1 groundwater flow is complex due to sucb influences as water level in the West Quarry,
fill distribution. and permeability.
Wells installed west of the West Quarry could be used to obtain background water quality
data.
.
.
Groundwater quality was degraded as determined from weJls installed around and within the
panialJy.OUed quarry.
..
-------
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-1
,
'~SKA
Figure I
Location Map
/"
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LEGEND
. MC-7
MASON CITY WELL
SCAU 1~48000
Map of Mason City with NWSPCC Site and City Wells
6
-------
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---....--
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- 1110-.....
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Figure 3
Map ot Area Nonh ot Mason Oty ShowiDa NWSPCC Site and Location ot Private Wells
7
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17 STI'IEET
sc.tU
LEGEND
.00
.
200
o
.&00-
I
~_)IWEl.I.NEST (1884) .. I
. &..OCA'OON of SEEPS and
EXTRACnON WELLS
Fi~
. 8
-------
.
Total dissolved solids, dissolved iron and pH exceeded secondary drinking water standards
(limitS for aesthetic qualities).
.
Groundwater quality impaCt in the vicinity of the West Quarry decreased with depth.
In response to a fish kill in Calmus Creek in September 1986, the WAWM again sampled Calmus
Creek. Water in the creek upstream of the seep area had a pH of 8.4 and four samples downSlream
ranged in pH of 10.2 to 10.5. Elevated potassium and white residue on the stream bed were also
noted. In October 1986, the W A WM again ordered NWSPCC to cease discharge from the seep area
to Calmus Creek. NWSPCC installed an acid treatment system in June, 1987 adjacent to Calmus
Creek in the northeastern portion of the filled West Quarry. In addition to treating the seep water,
the system was utilized in the dewatering of the West Quarry pond. Up to 1,100 gallons per minute
of high pH water from the West Quarry pond were pumped to the acid-neutralization treatment
facility with discharge to Calmus Creek in accordance with an NPDES permit issued by the Iowa
Department of Natural Resources (DNR). At present, water formerly accumulated in the West
Quarry pond has been removed by these procedures and the system is pumping approximately 70
gallons per minute to remove incoming water. This action bas significantly decreased the contact of
water with kiln dust and, as a result, pH levels in the quarry water have declined about two orders
of magnitude to about 10.5 pH units, as shown in Figure 5.
In 1987, EPA conducted a Site Inspection of the NWSPCC site and based on the findings o( this
investigation and the site was scored with the Hazard Ranking System for possible inclusion on the
National Priorities List (NPL). Since the site had a documented impaCt on Calmus Creek. did not
fall under RCRA jurisdiction, had an unknown potential for human risk. and had a sufficiently high
HRS score; it was proposed for the NPL in June 1988. The EPA has not yet finalized this proposed
listing.
In 1988, NWSPCC initiated a Remedial Investigation/Feasibility Study (RIIFS). In September 1989,
the DNR issued an administrative order to NWSPCC for completion of the RIIFS. In November
1989, this order was replaced with a consent order (or the same. NWSPCC completed the RUFS in
March 1990. The Remedial Investigation assessed the potential impact of the West Quarry on the
local surface water and groundwater now systems. This investigation demonstrated that significant
impact to groundwater outSide the West Quarry boundaries has not occurred. Discharge Crom the
acid treatment system to Calmus Creek was (ound to contain total dissolved solids and phenols at
levels which may cause violations of Iowa water quality standards in Calmus Creek (these parameters
were not included in the original NPDES permiL)
2.2
Hi2hli2hts of Communitv Panicipation
The Remedial Invcatigation and Feasibility Study Reports and the Proposed Plan (or the
Nonhwestern site were released to the public for comment March 30, 1990. These two ,documentS
were made available to the public in the administrative record maintained in an information repository
at DNR Records Center, 5th Aoor, Wallace Building. 900 East Grand, Des Moines, Iowa, and in the
Mason Qty Public Ubrary.
The notice at availability for these two documentS was published on March 30, 1990, in the Mason
City Globe.Gazette. A public comment period on these documentS was held from March 30, 1990
through May 29, 1990. Also, a public meeting was held aD May I, 1990 at the Mason City Public
Library. At this meeting. representatives from the DNR. EP A and NWSPCC discussed the site and
the selected remedial alternative. Questions from the medii. were answered regarding tbe severity of
the existing problem at NWSPCC and the potential for future hazards at the site. A response to
commentS rC(:Civc4 during this period is included in the Responsiveness Summary. which is pan of
9
-------
13.0
12.8
12.6
12.4
12.2
12.0
11.8
:r: 11.6
0.11.4
11.2
11.0
10.8
10.6
10.4
10.2
10.0
1978.
Ape 5
1980
1982
1984
YEAR
1986
1988
1990
Temporal Trend of pH in the West Quarry
10
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2.4
the record. This decision document presents the selected remedial action for the NWSPCC site in
Mason Ciry, Iowa, chosen in accordance with CERCLA, as amended by SARA and, to the extent
practicable, the National Contingency Plan. The decision for tbis site is based on the Administrative
Record.
2.3
Scope and Role of Response Actions Within Site Strate2V
Tbe selected response action addresses the principal threats of surface water, groundwater
contamination and the source of water contamination. Based on investigations of the site prior to
1989, and based on the Remedial Investigation, the source of contamination is the cement kiln dust
disposed of in the West Quarry. Of particular concern is its impact on the groundwater and on
Calmus Creek. The kiln dust would be sufficiently isolated from water in the selected alternative to
minimize production of contaminated water. Any contaminated groundwater whicb is produced, as
well as existing contaminated groundwater, will be removed, treated and discharged, thus preventing
oCf.site migration of contaminated water.
The response actions selected in this ROD address aU principal threats posed by this site and are
intended to constitute f1Dal action for the site.
Summary of Site Characteristics
The major concern at NWSPCC is contaminated surface water and groundwater as a result of contact
with waste cement kiln dust in the West Quarry. The kiln dust is composed of a major cement
constituent, calcium oxide (CaO), which reacts with water and releases hydroxide ions (OH1 into
solution. The hydroxide ion concentration directly controls the pH level of an aqueous solution.
Local groundwater and surface water have been impacted by high pH levels, and by an increase In
total dissolved solids content, as well as elevated concentrations of potassium, sulCate, sodium and
other relatively nonhazardous parameters. Figures 6 - 9 show the distribution of pH, total dissolved
solids, sulfate and potassium concentration found at site monitoring weUs. Trace amounts of heavy
metals and phenol have also been detected sporadically. (Refer to Table L) Of the contaminants
identified, only arsenic is a suspected carcinogen. Levels of metals found in soil/sediment samples are
not considered to be significantly different than background soils. The kiln dust in the West Quarry
is a RCRA special study waste, not a RCRA bazardous waste. Water at the NWSPCC site having
a pH value exceeding 12.5 would exceed the RCRA criterion for corrosiviry and be considered a
RCRA hazardous waste.
Surface water contamination was previously a problem with water from the West Quarry entering
CalmuS Creek and adversely impacting tbe aquatic habitat of the creek. The primary problems have
been sharp increases in the pH and mineral deposition in the stream. Actions taken by NWSPCC
have eUminated untreated discharges from the West Quarry to Calmus Creek. Discharge of water
from the add-neutralization fadUry, however, still poses potential water qualiry problems in Calmus
Creek due to elevated levels of total dissolved solids and pbenols.
Imp8Cled JI'OUDdwater bas been found to exist within the kiln dust fill and in the bedrock underlying
and adjacent to the quarry. The degree of impact bas been shown to lessen with depth. No
signitlcut oU-site groundwater contamination bas been found. Figure 10 is a groundwater now map
showing cunent conditioDS. Prior to dewatering of the quarry groundwater Oow was primarily toward
nonheast to Calmus Creek and/or the Winnebago River. Potential pathways of groundwater
migration exist via the upper bedrock (Devonian aquifer). The Devonian aquifer yields moderate
amounts of water to wells. Devonian wells produce water primarily from the upper weathered ponion
of tbe rock and solution-enlarged fractures. Nearby weUs wJUch draw water from this aquifer include
10 private weUs about a mile nOnh of the site and 3 weUl in tbe Ume Creek Nature Preserve about
a mile and a ball nonheast of the site. (Refer to Fipre 3.) WeUs with bilher capaciry in the area
are completed in the Cambrian Jordan Sandstone at-depths pater than 1200 feet, including tbe
11
-------
Fipg.
Groundwater pH - Jan. 1989
12
lEGENQ
.. WEU. NEST (1"')
. WELl, NEST (1...)
S~
D DEEP
.00
I
~CAU
200
.--
o
-------
sc.t.L.I
.00 :100
I
o
AOO-
Azure 7
Total Dissolved Solids Concentrations in Groundwater - Jan. 1989
13
-------
LEGEND
S~
. --I
. I
.00 200
I
o
.00_'
. WEU. NEST (1884)
. WEU. NEST (1888)
. SfW..LOW
D DEEP
. .
CoMentratlon8.....-aM In "'II/L
Sulfate Concentrations in Groundwater - Jan. 1989
fig
14
-------
Fipre9
Potassium Concentrations in Groundwater - Jan. 1989
15
LEGEND
.. WEl.1. NEST (18M)
. WEl.1. NEST (1888)
S SHAllOW
D DEEP
eo.-nt..tIon8 8qor-8d In "'II/l
5~
.00 200
I
.00 ....
o
-------
Table 1
Concentration Values in Various Environmental Media - Mean and Maximum Values
ug/l (ppb) ug/l (ppb) mglkg (ppm)
Chemical Groundwater Surface Water Soi1JSediment
Man Max ~ M!! Mean Max
Antimony 12 12 NA ND NA ND
Arsenic 12 45J 15 15 5.0 13J
Cadmium 5.6 6 5 8 1.1 1.1
Total Chromium 41.7. 170 38.7 61 10.9 16.0
Copper 20 20 20 20 11.0 11.0
lad 12 74J 10 10 59.7 150
Mercury 0.63 1.2 NA ND NA 'NO
Nickel 153.7 460 66.5 90 NA 12.0M
ZJnc 42.3 720J 70 70 57.3 130
Pbenol 195" 230-. 133 469 NA ND
J-
M-
NA-
ND-
Compound was, qualitatively identified; however, oompound failed to meet aU QA criteria and, therefore, is onJy an estimated value.
Compound was qualitatively identified; however, qualitative value is less than oontract required detection limits.
Not applicable
Not detected
NOTE: J and M - roded data not Induded in calculation of mean values.
.
The three bighest chromium measurements of 70,90, and 170 ppb all occurred on the first sampling event in March 1984. Subsequent
total chromium measurements have averaged 14 ppb.
..
Phenol values In groundwater based on seep water only which is believed to be more representative of surface water.
16
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~
~..
SCAL8'
~
.
aoo
o
~-
I
VAL:' nrr
COHT- '1fTEII
Fiprcl0
Aow - Jan. 1989
Groundwater
17
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.2.5
NWSPCC plant wen and Mason City water supply wells. (Refer to Figure 2) These deep wells ar.
typically uncased though the Devonian aquifer, allowing Devonian water to enter the well, albeit a
small ponion of the total wen capacity.
Direct exposure to high pH water in the West Quarry pond was a past risk which has since been
eliminated by dewatering of the quarry.
Summary of Site Risks
The U.S. Public Health Service Agency for Toxic Substances. and Disease Registry (ATSDR)
conducted a draft Health Assessment for the NWSPCC site. They concluded that the site is of
potential health concern because of the potential risk to human health resulting from possible
exposure to hazardous substances at concenuations that may result in adverse health effects. The
A TSDR repon expressed a concern for potential human exposure to chromium, lead, sodium, sulfate,
and elevated pH via ingestion of groundwater from on-site and off-site private wells. Also human
exposure to elevated pH may occur and may have occurred in the past via dermal contact, ocular
contact, and incidental ingestion of on-site soil, sediment, surface water and groundwater; and via
inhalation of reentrained dUSL Human exposure pathway of concern includes the sodium and sulfate
concentrations in the groundwater which may be detrimental to high risk populations.
An Endangerment Assessment was conducted as pan of the remedial investigations and is included
in the Adminisuative Record as a separate repon. T1Us Endangerment Assessment provided a
baseline risk assessment to assist in the development of remedial alternatives. It assessed only the
hazardous substances listed in Table I, which was subsequently reduced to the chemicals having the
most potentiaJ impact as listed in Table IL The Endangerment Assessment did not consider pH,
sodium, potassium, sulfate, or total dissolved solids which are the primal)' parameters impacting water
quality at the site. These parameters are naturally occurring, often at relatively high concentrations;
are not panicularly toxic; and, as a result, do not fit into the endangerment assessment process. Witi'>
this in mind, the Endangerment Assessment had the fonowing conclusions: '
1)
2)
There are no complete exposure pathways identified for contaminants in the soil or air.
The surface water does not pose any adverse bealth exposure potential to the general public.
Neutralizing and monitoring water quality of the West Quarl)' before releases should be
continued.
3)
" The only potentially complete exposure pathway for the West Quafl)' is through groundwater
in the bedrock. There is no current or anticipated adverse exposure potential Cor the
surrounding public and private wells in the near future.
The West Quany at NWSPCC is not a present threat to the public bealth or welfare of the
Malon City uea.
4)
Poteadal risks from drinking site JfOundwater were calculated in the Endangerment Assessment and
are IUIIUI8rized fa Table IL These hazards were based upon .potential. consumption of water with
the mean contaminant concenuations found in on-site monitoring wells. In reality there is no current
consumption ot this impacted water and modeling has demonstrated that there is little potential Cor
significant migration ot impacted groundwater fa the neaf future (e.g. 30 years). The fonowing
paragraphs explain the information presented in Table IL
Reference doses (RCds) have been developed by EP A for indicating the potential for adverse bealtb
effects from exposure to chemic:als exhibiting noncarcinogenic effC(:ts. RIDs, which are expressed in
units of m&'kg~y. are estimates of lifetime daily exposure levels for bumans, including sensitive
18
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Table D
Summary of Potential Hazards from Chronic Consumption of Contaminated groundwater
CHEMICAL mI RFD
Arsenic 3.4d~ NA
Chromium 1.2110"1 5.0Jt 1 0"1
Lc.ad 3.411~ 1/4x1- oJ
Nickel -4.511al 1.0Jt10"1
HS2 CPF ELC
NA 15 5.1110.1
0.2.4 NA NA
0.25 NA NA
0.-45 NA NA
Hazard Index - 0.94
Total Excess Lifetime Cancer Risk - 5.111al
EDJ - Estimated Daily Intake (mglkyc1ay)
RFD . Reference Dose
HQ - Hazard Quotient
CPF - Cancer Potency Faoor'
ELC - Excess Lifetime Cancer Risk
"
"
19
-------
individuals, that are not likely to be without an appreciable risk of adverse health effects. ~timatcd
intakes of chemicals from environmental media (e.g., the amount of a chemical ingested from
contaminated drinking water) can be compared to the RID. RIDs are derived from human
epidemiological studies or animal studies to which uncertainty factors have been applied (e.g., to
account for the use of animal data to prediCt effects on humans). These uncertainty factors help
ensure that the RIDs will not underestimate the potential for adverse noncarcinogenic effects to occur.
Potential concern for noncarcinogenic effects of a single contaminant in a single medium is expressed
as the hazard quotient (HQ) (or the ratio of the estimated intake derived from the contaminant
concentration in a given media to the contaminants's reference dose). By adding the HQs for all
contaminants within a medium or across aU media to which a given population may reasonably be
exposed, the Hazard Index (HI) can be generated. The HI provides a useful reference point for
gauging the potential significance of multiple contaminant exposures within a single medium or across
media. HI values less than one are acceptable.
Cancer potency faCtors (CPFs) have been developed by EPA's Carcinogenic Assessment Group for
estimating excess lifetime cancer risks associated with exposure to potentially carcinogenic chemicals.
CPFs, which are expressed in units of (mglkg-dayr1, are multiplied by the estimated intake of a
potential carcinogen, in mglkg-day, to provide an upper-bound estimate of the excess lifetime cancer
risk associated with exposure at that intake level. The term .upper bound. reflects the conservative
estimate of the risks calculated from the CPF. Use of this approach makes underestimation of the
actual cancer risk highly unlikely. Cancer potency factors are derived from the results of human
epidemiological studies or chronic animal bioassays to which animal-to-human extrapolation and
uncertainty factors have been applied.
Excess lifetime cancer risks are determined by multiplying the intake level with the cancer potency
factor. These risks are probabilities that are generally expressed in scientific notation (e.g., lxlO~).
An excess lifetime cancer risk of a 1xlO~ indicates that, as a plausible upper bound, an individual has
a one in one million chance of developing cancer as a result of site-related exposure to a carcinogen
over a 70-year lifetime under the specific exposure conditions at a site.
In summary, Table II shows that long-term consumption of the impaCted site groundwater would not
pose a significant noncarcinogenic effect since the HI value is less than one. An estimated excess
cancer risk of one in 5,000 would be posed due to consumption of arsen~ at the estimated mean
concentration found in site groundwater. This would be an unacceptable risk it people were drinking
this water. However, arsenic has been detected in only three of eleven samples from the two
monitoring wells which have otherwise yielded the most impacted groundwater. Therefore, the
consistc,!'cy of arsenic occurrence in site groundwater is uncenain. Regardless, the selected remedy
will prevent off-site migration of any impacted groundwater and consumption of contaminated water
will not oc.cur.
As stated previously, the Endangerment Assessment did not address the major parameters affecting
water quality of the NWSPCC site. Figures 6-9 illustrate the concentrations o{ pH, total dissolved
solids (J'DS), sulfate, and potaSSium found in groundwater thr~ughout the NWSPCC site. Sodium
concentndoftS have also been found to be substantially elevated with levels greater than 800 mg/1
found in weD 2-A compared to background levels of around 20 mg/l in well B-3.
National secondary drinking water regulations set non-enforceable limitS for contaminantS in drinking
water which may affect the aesthetic qualities or the public's acceptance of drinking water (e.g., taste
and odor). These secondary maximum contaminant levels (SMCLs) have been established for pH
(6.5-8.5), sulfate (250 mg/l) and TDS (500 g/I). In addition, a guidance of 20 mg/l sodium exists for
people on low-sodium dietS. Significantly elevated levels, much in excess of tbe SMCLs, have been
identified in the groundwater and surface water at the site. The elevated pH levels have been the
20
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2.6
primary concern associated with the NWSPCC West Quarry site. Levels of pH in excess of 13 have
been found in site groundwater and the West Quarry pond had pH levels in excess of 12.5 (the level
above which a liquid is considered a hazardous waste) prior to dewatering operations which were
begun in 1987 (refer to Figure 5).
No significant off-site effect in groundwater has been found and groundwater modeling results suggest
that significant migrations of the constituents associated with the SMCu and sodium will not occur
in the near future (e.g., 30 years). However, significant long-term off-site impacts to groundwater arc
possible if no response action. is taken. Also continued adverse impacts to the Calmus Creek aquatic
habitat and threats of direct contact to high pH water in the West Quarry pond will exist wilhoul
response action.
Actual or threatened releases of hazardous substances from this site, if not addressed by implemenling
the response action selected in this ROD present an imminent and substantial endangerment tu public
health, welfare, or the environment.
Description of Alternatives
The alternatives for soil and groundwater cleanup have been evaluated and listed below.
Remedial Action Alternative 1 - No Action
Remedial Action Alternative 2 - Waste stabilization.
Remedial Action Alternative 3 - Waste isolation.
Remedial Action Alternative 4 - Offsite disposal.
Remedial Action Alternative S - Drainage of Quarry.
Alternative 1- No Action
The no action alternative includes allowing conditions at the site to return to what they were prior
to 1985. Evaluation of this Alternative is required by the National Contingency Plan (NCP) and also
provides a baseline of comparison for the other alternatives. ARAR's would not be attained.
There would be no COSt associated with this alternative.
Alternative 2- Waste Stabilization
The implementation of this alternative would be expected to result in the total remediation of the
West Quarry, anain all ARAR's, and provide a permanent remedy.
DewateriDl of the West Quarry would continue. This would require a pumping system, water
treatmeat to meet Iowa NPDES discharge permit limitS, discharge to Calmus Creek. and groundwater
monilorina. There would be laboratory kiln dustJflX8tive tests performed to establish the most
effective fixative agent and concentrations. The waste kiln dust would be stabilized and solidified in-
situ with the rlX8tive agent introduced through kiln dust augering. The aquifer beneath the quarry
would be remediated through the installation of extraction wells screened within the bedrock beneath
the quarry. This water would be treated and discharged along with the quarry drainage water.
The estimated present wonh cost of this alternative is 18.6 million dollars. It would take about twO
years to implement.
21
-------
AHemative 3 . Waste Isolation
The implementation of this alternative would resull in the total remediation of the West Quarry. It
is expected to attain all ARAR's and provide a permanent remedy.
In this alternative, the Quarry would continue to be dewatered. This would require a pumping system,
water treatment to meet Iowa NPDES discharge permit limits, discharge to Calmus Creek and"
. groundwater monitoring. In conjunction with dewatering of the West Quarry, a low-permeability clay
cap and a topsoil surface cover would be placed over the existing kiln dust flU areas. Several
monitoring wells would be installed within the kiln dust to determine if dewatering has been effective.
U necessary, several kiln dust dewatering wells would be instaUed to facilitate kiln dust dewatering
with the resultant water being treated and discharged along with the quarry drainage water. A deeper
recovery weU system would be installed to collect impacted groundwater in the limestone bedrock
beneath the quarry. This water would also be treated and discharged along with the quarry drainage
water. Appropriate portions of the pumping system would be maintained to continually induce
hydraulic gradients toward the quarry, and prohibit any migration of contaminants from the quarry.
Assurances for perpetual operation of this system would be provided.
The estimated present wonh cost of this alternative is 2.0 million doUars. It would take about 1.5
years to implemenL
Alternative 4 . Orrsite Disposal
The implementation of this alternative would result in a total remediation of the site, is expected to
attain all ARAR's, and would provide a permanent remedy.
Water would continue to be drained from the Quarry. This would again require a pumping system,
water treatment to meet Iowa NPDES discharge permit Umits, discharge to Calmus Creek, and
groundwater monitoring. Kiln dust would be removed from the quarry and uansferred to an oCf-site
engineered landfill storage facility. The aquifer beneath the quarry would be remediated through the
installation of extraction wells screened within the bedrock beneath the quarry. This water would be
treated and discharged along with the quarry drainage WIter. Continued pumping of inllowing
meteoric water from the quarry would be done until completion of aquifer restoration when the
quarry ,would be aUowed to fill with water.
The estimated present wonh cost of this alternative is 18.5 million dollars. It would take about 3 to
5 years to complete.
"
Alternative S . Drainae of the Quam
The implementation of this alternative would reduce the threat from the conwninated water within
the West Quarry, but could not attain aU ARAR's since DOthiDg would be done to address existing
groundwater conWDination. .
The quny would continue to be drained. This would require I pumping system. water treatment to
meet Iowa NPDES discharge permit UmitS, discharge to Calmus Creek, and groundwater monitoring.
The estJmatcd present WOnh cost of this alternative is $312,000. It ,could be implemented in about
6 months.
2.7
Summary of Comparative Analvsis of Alternatives
The treatment of impaCted groundwater and surface water i$ a' common remediation denominator to
several of the alternatives. Although the aCtual quantity of water to be treated varies somewhat
22
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betWeen individual alternatives, treatment processes and costS would be similar. This similarity
resultS from the interim actions NWSPCC has already taken to remedy the problems on the site.
A comparative analysis of each alternative against the following nine criteria bas been made.
1) OveraU protection of human health and the environment
. 2) Compliance with applicable or relevant and appropriate requirements (ARARs)
3) Long-term effectiveness and permanence
4) Reduction of toxicity, mobility, or volume through treatment.
5) Short-term effectiveness
6) Implementability
7) Cost
8) State acceptance
9) Community acceptance
Table III shows a relative ranking ot the first seven of these criteria for each alternative.
0vCI'alI Protcc:t1on of buman bealth and the CDVirolUDCDt
The No ACtion alternative and the Drainage ot Quarry alternative are not protective of human health
because they do not provide for removal of existing impacted groundwater. The No Action alternative
also fails to protect the environment because discharges of high pH/TDS water to Calmus Creek
would occur. The Waste Stabilization, Waste Isolation, and OCf-Site Disposal alternatives are
protective ot human health and the environment because tbey would remove the contaminated
groundwater and prevent future discharges of contaminated water to Calmus Creek and the bedrock.
With the Waste Isolation alternative, a long-term monitoring program would be necessary to protect
against future threatS to human health and the environment. It would also be necessary to conduct
a long-term monitoring program for the off-site disposal alternative to evaluate the impact of a new
disposal area on itS sUrTounding environmenL
Compliance with ARARs
The No Action alternative would not comply with ARARs for tbe discharge to Calmus Creek or for
the groundwater contamination. The Drainage of Quarry alternative would not be expected to comply
with ARARs regarding groundwater contamination, but would comply with ARARs for the discharge
to Calmus Creek.
"
The Waste Stabilization, Waste Isolation, and Off-Site Disposal alternatives all would comply with
ARARs regarding groundwater and discharges to Calmus Creek. The OCf-Site Disposal alternative
would be ClpCCted to atlain state solid waste disposal ARARs.
LoD""" ~ and perm.--Dce
The No AaJon alternative and the Drainage of Quarry alternative lack long-term effectiveness and
cannot be mnsidered as permanent cleanup actions.
The Waste Isolation alternative has long-term effectiveness and permanence, but requires assurances
for continued pumping and groundwater monitoring to maintain long-term compliance with this
criterion. The Waste Stabilization alternative and the Off-Site Disposal alternative provide long-term
effectiveness and permanence without the need for long-teqn'pumping and monitoring at the West
Quarry site. However, the off-site disposal alternative would require long-term monitoring at the new
disposal site and muld result in adverse impaCtS at the ~ew site.
23
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Table m
Ranking of Remedial Action Alternatives
/
;.:: PROTECTION Of t C(JV>lIANCE LONG- tER" i/ REDUC1lON Of SHORT - TER" :::: IHPLEHENTABIlI" COST
:::: IlUMAIJ HEALTH r: "ITH THE;:: EHEC1IVNESS it TOXICI". :::: EfFEC1IVENESS :\ ......
[j AND THE ~:: APPLICABLE::::: AND ;::i. HOSHI". OR [:::! i.:::
::::: ENVIRONMENT f: REOUIREHENTS .::::. PERMANENCE :::::. VOlUHE . ,::::: .........0.00.0....0.0..."..."..00."... ,::::
..... ............
..............-........
,.;.
.
t~
:;";";:::::;:::::::;:;:::::::;::";:.:;:::;::;::';";:.:;:.:::.::.;:;"::.::"."."::::;:::.
.....:....,......o..o.o.......:.:~il.:::::.;;::..
S
.".::'::::.;.;'
2
RATliG:
'-HIGHEST
5-L04EST
-------
Reduction of tmidty, mobility, aad \'Olumc through treatmcDt
The No Action alternative would not reduce the toxicity, mobility, or volume of the contaminated
materials. All other alternatives include treatment of water prior to discharge. The Drainage of
Quarry alternative would reduce the volume of the contaminated water, but would not reduce the
toxicity or mobility of the contaminants that remain in the groundwater. Future leachate production
in the kiln dust deposit would also be a concern with this alternative.
The Waste Stabilization, Waste Isolation, and OCf-Site Disposal alternatives would all reduce the
volume, mobility, and toxicity of impacted groundwater to similar levels. Impacted groundwater would
be removed and treated. Future discharges of contaminated water to Calmus Creek and to the
bedrock would be eliminated.
Only the waste stabilization alternative addresses treatment of the waste kiln dust which is the source
of contamination.
Shon-term e1I'ectMacsa
The No Action alternative lacks shan-term effectiveness. The Drainage of Quarry alternative is
panially effective in the shon-term, since it preventS discharge to Calmus Creek and to the bedrock.
It has no shon-term effect on the groundwater contamination already present at the site.
The Waste Stabilization, Waste Isolation, and Off-Site Disposal alternatives are all similarly effective
in stopping discharges to Calrnus Creek and to the bedrock. They also will have similar shon-term
effectiveness in removing the groundwater contamination present at the site. The Off-Site Disposal
alternative would take considerably longer time to implement and would have shon-term impacts due
to airborne dust and transportation of large quantities of kiln dust.
Implemeatability
The No Action alternative presentS no implementation difficulties. The Drainage of Quarry
alternative also is unlikely to present implementation difficulties because much of the necessary
equipment and personnel are in place and operational
The Waste Stabilization alternative requires that a usable fixative be identified and that it be augered
and mixed intO the kiln dust deposit that is over 3S feet deep and over 100 acres in area.
Implementation would be technically difficult and would require at least two years.
,
The Waste Isolation alternative involves technologies which are well established and would be easy
to implement.
The Otr..site Disposal alternative would require the siting and construction of a landfill capable of
contaiDin. tile kiln dust. Then the kiln dust deposit would have to be dewatered and transferred to
the IlndftU. Airborne dust would have to be controlled during this process. Siting of a landfLIl will
be dUlk:u1t because 01 problems in finding a suitable location, landfill permitting and design time,
likely pubUc opposition to a new landfill, and other factors. This alternative is considered to be the
most difficult to implement.
Cost
The costS of the alternatives are presented in the Descriptiol\ot Alternatives section of this document.
2.S
-------
ScaLe aazptIJMZ
This criterion addresses the a:>ncern and degree of suppon that the State government has expressed
regarding the remedial action alternative. The Iowa Depanment of Natural Resources (DNR) has
been the lead agency for this project under a cooperative agreement with EP A. The DNR reviewed
the documents pertaining to the site and prepared the Proposed Plan and this ROD. The DNR has
given its concurrence on the selected remedial action.
Community accep1aDCe
At the end of the public comment period (May 29, 1990), there were no comments objecting to the
preferred remedial alternative. This includes comments during the public hearing held May I, 1990.
No wrinen comments were received during the March 30 through May 29, 1990 public comment
period.
2.8
The Selected Remedv
The selected remedy is the Waste Isolation alternative.
Isolation of the kiln dust will be accomplished by sequential implementation of remedial technologies.
The initial remedial action, the draining of the West Quarry, has been accomplished as of September,
1989. Easeways and water a:>llection systems have also been installed in the floor of the dewatered
Quarry. The water removed from the Quarry continues to be acid neutralized and discharged to
Calmus Creek. Subsequent site remediation activities will include: construction of a permanent drain
system in the dewatered Quany; placement of an engineered clay cap over the kiln dust body;
installation of bedrock dewatering wells; installation of kiln dust monitoring wells; installation of kiln
dust dewatering wells, if necessary; and treatment of all extracted waters prior to discharge to Calmus
Creek.
A permanent drain system will be installed in the dewatered Quarry to collect precipitation runoff as '
well as groundwater seeps. The system will be designed to segregate contaminated from
uncontaminated water as shown in Figure 11. The contaminated water collected within the Quarry
will be pumped to the site water treatment system for ueatment to attain Iowa NPDES discharge
limitations and discharged to Calmus Creek.
The hydraulic isolation of the wasLe kiln dust and the extraction of adjacent contaminated
groundwater would be achieved through the placement of bedrock dewatering wells (Figure 11). The
drawdown cones formed by the pumping of the dewatering wells placed around the perimeter and
within the filled portion of the Quarry will limit lateral and venica1 ,roundwater flow into the kiln
dust thereby limiting future resaturation. These wells will be cased through the kiln dUSL The wells
will pump approximately 10 gpm and be completed to a depth of approximately 150 Ceet in order to
proYidc lor etlieicnt isolation syStem. As the impacted groundwater is extracted from beneath the
West Quarry and eventually purged, treatment of the extraCted water may not be necessary.
Ki1D dUSt atraetfon wells will be installed, it necessary to facilitate dewatering of the kiln dUSL Such
wells willlikdy not be necessary.
The kiln dust body within the West Quarry will be isolated from surficial resaturation through the
placement of an engineered clay cap (Figure 11). The clay for the cover will be obtained from
adjacent NWSPCC property. The clay cap instalJation will requite excavation, transport, and
placement 01 clay-rich soils and topsoil I
,
26
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400 200
L
o
£00-
I
OPTIONAL KILN DUST
. DEWATrRINC WELLS
Figure II
Sile Map Showing the ComponenlS or lhe Selected Remedy - Remedial AJlernalive No.3. Wasle Isolation
27
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As pan of the remediation, maintenance manuals will be generated by NWSPCC to instruct NWSPCl.
personnel ooncerning the continual and proper operation of the system. The site will be monitored
during and after remediation to insure the effectiveness oC the alternative. The monitoring will consist
of engineering oversight of the installation and operation of the system; and of sampling the
groundwater on a selected interval and analyzing (or indicator chemicals. The treated discharge to
Calmus Creek will monitored to insure oompliance with the Iowa NPDES permiL Long-term
pumping will be necessary to maintain the separation of the kiln dust deposit and the groundwater
system. A contingency plan will be required to ensure continued operation, including financial
assurances.
The remedy was selected from among three alternatives that would provide for protection of human
health and environment; comply with ARARs; reduce the toxicity, mobility, and volume of the
contamination through ueaunent; and have both long-term and shon-term effectiveness. Tbe No
Action alternative and the Drainage oC Quany alternative would not meet all o( these criteria; and
were not selected. OC the remaining three alternatives, the Waste Isolation alternative could be
implemented with greater assurance oC effectiveness, without risk oC adverse oCC-site impacts associated
with removal oC the kiln dust to another location, and at a substantially lower COSL
A summary of the estimated costs oC the selected remedy are presented in Table IV.
2.9
Statuto" Determinations
Under its legal authorities, EPA's primary responsibility at Superfund sites is to undertake remedial
actions that achieve adequate protection of human health and the environmenL In addition, section
121 oC CERCLA established several other statutory requirements and preferences. These speaty that,
when oomplete, the selected remedial action for this site must oomply witb applicable or relevant and
appropriate environmental standards established under Federal and State environmental laws unless
a statutory waiver is justified. The selected remedy also must be cost-effective and utilize permanen'
solutions and alternatives ueatment technologies or resource reawery technologies to the maxim u fi..
extent practicable. Fmally, the statute includes a preference for remedies that employ ueatment that
permanently and significantly reduce the volume, toxicity, or mobility of hazardous wastes as their
principal element. The following sections discuss how the selected remedy meets these statutory
requirementS.
Prott:cdoD of Human Health IDd the EavirolUlleDt
The ~I'ected remedy protects human health and the environment by removing and ueating impacted
waters and minimiziD, funher impacts on water from the ki1D dust by minimizing kiln dust contact
with water. 'Ibis should result in groundwater oontamiDant levels below bealth-based standards and
surface water meetina state water quality standards. 'Ibis will be aa:omplished througb capping the
waste Id1D dust, quany drainage, and su!HIuany dewaterinJ.
E.xis1iq Impacted poUDdwater will be extracted and treated. 'Ibis will prevent off-site migration of
impaaed JrOUDdwater thus eliminating potential bUJIWI exposure via drinking water wells. AU water
cUscbarJed to Calmus Creek from the site will be ueated as Decessary to meet Iowa water quality
standards which are established to protect aquatic life.and secondary buman contact (e.g. wading).
Capping of the kiln dust will reduce productioD of leachate due to iDfiltration of precipitation.
-
.~
28
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Table IV Estimated Costs for the Selected Remedy
- .~._-~. -_.
CAPITAL OUTLAY 1st YEAR ANNUAL
Ranae MidDoint OPERATING OPERATING
Drain Quarry
Pumping $25,000
Trenches $45.000
$70,000 $10,000 $10,000
Surficial capping
Clay Cap/Topsoil
Seed $875,000
Dewatering System
Bedrock Wells $200,000
Kiln Dust Wells $4,000
Piping Runs $50,000
$255,000 $25,000 $20,000
Waste Water Treatment
Acid
Neutralization $40,000 $125,000 $25,000
Engineering $120,000
Design/Construction
Management $100,000
,
Longterm Monitoring
and Maintenance $40,000 $50,000 $10,000
TOTAL: 1.500.000 $210.000 $65.000
The Projected Value Cost for RAA 3, assuming a 10% interest rate,
would be $2.037.129.
29
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CompUaDcz with Applicable or Relevant and Appropriate Requirements
The following ARARs apply to the selected remedy. It should be noted that levels of metals detected
in groundwater are generally low and in all likelihood will not be a determining factor. The primary
water quality parameter of concern is pH.
, Current and anticipated Iowa NPDES effluent limitations for discharge to Calmus Creek:
pH 6.0 to 9.0
IDS 750 mg/1
Phenol 0.050 mg/1
Iowa Groundwater Action Levels:
Chromium(total) 0.1 mg/1
Lead 0.05 mg/1
Cadmium 0.05 mg/1
Nickel 0.2 mg/1
Maximum Contaminant Levels, Federal Safe Drinking Water Act (SDWA):
Chromium 0.05 mg/1
Lead 0.05 mg/1
Cadmium 0.005 mg/1
pH 6.5 to 8.5
The selected remedy should be able to attain these ARARs.
Cost-dfectM:Dcss
The selected remedy is cost-effective because it is the least expensive action alternative and yet
provides a high degree of overall protection. The other alternatives which were less costly did not
provide long-term remediation or compliance with ARARs. It was also uncertain whether tbe Waste -
Stabilization alternative, which would be much more costly (18.6 million dollars), could be effectively
implemented. The Off-Site disposal alternative was also more costly (18.5 million dollars) and moved
the source of the probl,,:m to another site where additional problems could resulL The selected
remedy will meet all ARARs and provide a long-term solution to the problem at a substantially lower
COSL Thus there are no significant advantages to the more expensive alternatives.
Utilization of Penoanent SolutioDS aDd AltcrDatM Treatment (or Resource Recovery) Technologies
to thc,Mmmum EdcAt Practic:able (MEP):
The Iowa DNR and EP A have determined that the selected remedy represents the maximum extent
to which permanent SOlutiODS and ueatment technologies can be practically utilized in a cost-effective
manner for the 6DaI respouse actiODS at the NWSPCC site. Of those alternatives that are protective
of hWDID bealth and the environment and comply with ARARs, the State and EP A have determined
that tbJI selected remedy provides the best balance of tradeoffs in terms of long-term effectiveness and
pennanace; reduction in toxicity, mObility, or volume achieved through treatment; short-term
effectiveness; implementability; cost; consideration of the statutory preference for treatment as a
principal element; and State and community acceptance.
Preference for Treatment IS a Principal Element
The cement kiln dust is not a hazardous substance in itself. Ir is through interaction with water that
high pH conditions are created. The selected remedy does Dot ueat the kiln dust, but it does isolate
the kiln dust (rom water to minimize funher productio~ of high pH water. Existing impacted water
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will be treated prior to discharge. Therefore, the statutory preference for remedies that employ
treatmeDt as a principal element is satisfied.
Documentation or Sirznificant Chanrzes
The Proposed Plan for the NWSPCC site was released for public comment March 30, 1990. The
Proposed Plan identified Remedial Action Alternative 3, Waste Isolation, as the preferred alternative.
The Iowa DNR reviewed all comments reaived during the pubUc comment period. Upon review ot
these comments, it was detetmined that no significant changes to the remedy, as it was identified in
the Proposed Plan, were necessary.
"
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RESPONS~SS~Y
The Proposed Plan for NWSPCC was released for public comment on March 29, 1990. The Proposed Plan
identified Remedial Action Alternative 3, Waste Isolation, as tbe preferred alternative. Verbal comments
during the public meeting were received during the public comment period. Upon review of these comments,
it was determined that no significant changes to tbe remedy, as it was originally identified in the Proposed .
Plan, ,were necessary.
No written comments were received. Several oral comments were received at the public meeting as discussed
below.
1.
Question: What is the status of tbe final listing on the National Priorities List (NPL)?
Response: The site is currently proposed for the NPL. The next update is due in a month or two
and this site is expected to be included in that update. However, that is a EP A headquaners decision.
2.
Question: Is there any indication that there is any degradation of well water in Winnebago Heights
or in the shallow wells from the area of Calmus Creek and Winnebago River?
Response: No, there is no indication that there is any contamination tbere. . Those wells were
sampled as pan of the EP A study back in 1987. The Nonhwestern site has had a number of sampling
events and contamination has not been found to leave the site.
3.
Question: Is contamination entering Calmus Creek?
Response: With the dewatering of the West Quarry Pond, the groundwater table has been lowered
and, as a result, groundwater is now Oowing tOward the quarry and not from the quarry to Calmus
Creek. Treated water Crom dewatering of the quarry, however, has been found to contain levels of ~
total dissolved solids and phenols which may cause cxceedances of water quality standards in Calmus
Creek.
4.
Question: What about the questions about turbidity and dissolved solids entering Calmus Creck?
The repon indicates that stream life bas been adversely affected in Calmus Creek and even in the
Winnebago River.
Response: That is UUe. It was quite obvious back in 1979 when this original problem was identified.
There is no longer high-pH water being discharged to Calmus Creek Crom Nonhwestern. The
Nonhwestem discharge does still have high levels of dissolved solids and phenols. The dissolved
solids still may be causing some problem by a wbite mineral deposit occurring on the streambed
downstream of the Nonhwestern site. As pan of the remedial aCtion, Nonbwestern is going to be
required 10 meet some new discharge requirements. In the past, their discharge permit has only
included UmiIS for pH, but additional limits for dissolved solids and possibly phenols will be added.
s.
Question: Recently the Creek was seen to run yellow after a rain. Is that pan of this problem and
will it be mediated by this dissolved solids standards being proposed?
Response: The West Quarry site could not be the source of that water because tbe quarry is nearly
dry. The local DNR field office is aware of this situation a.nel will be investigating other suspected
sources.
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6.
Question: Is there is any indication that the water is penetrating the duper layers of rock and
entering the layer of rock from which the Winnebago Heights people pump their water?
Response: The Nonhwestem site has bedrock monitoring wells at different depths. Impacted water
has been (ound in some of these wells. However, the degru o( impact lessens with depth and also
lessens laterally from the site. No evidence of impacted water leaving the site has been found.
. Therefore, impacted water has entered the rock layer from which the Winnebago Heights people
pump their water. However, .the impacted water in the bedrock has not been found to leave the site
and there is little potential for contamination of the Winnebago Heights wells. The selected remedy
will insure this by removing impacted water and minimizing production of additional impacted water.
7.
Question: Since there does not appear to be much of a threat from the NWSPCC site, how much of
a chance is there that this site will make the Superfund NPL list?
Response: The NPL list addresses potential problems and It is very hard to assess potential problems
from groundwater contamination. It is almost impossible to say that thr.re is no potential risk from
groundwater contamination. In the Superfund program, just the existence of contaminated
groundwater and the existence of drinking water supplies in the vicinity arc all it takes to get on the
NPL lisL During the more intensive RI/FS studies the degru and likelihood of threat arc
demonstrated.
8.
Question: How did this site first come to your attention?
Resoonse: In 1979, there were problem in Calmus Cruk and the Winnebago River with water
quality. In 1984, the Iowa Hygienic Laboratory did a study of Calmus Cruk and did water sampling
in Winnebago and Calmus Creek and various locations, as weU as sediment samples. They tracked
the source of this contamination to an overflow from the nearby Lehigh Portland Cement Company
site and seeps or blow-Out areas on the Nonhwestem site.
Since then, both companies have done a considerable amount of work and have been under order by
the DNR to eliminate those discharges at Calmus Cruk. which they both have done.
In 1987, a contractor (or the U.S. EPA did additional investigations, based on data from that
investigation, the site was assessed and proposed (or the NPL in 1988.
9.
Questiom. Can you describe what the conditions for stream life were back in 1979 and what they are
now? '
Response: Prior to 19'79, Calmus Cruk supponed a good diversity of aquatic lite. EP A recently
conducted a study OD the aquatic lile 01 Calmus Creek which found a lack in the variety of species of
aquatic Ute just below the NWSPCC discharge. Thus, despite improvementS in stream pH, there does
not appear to be a significant improvement in the aquatic habitat since NWSPCC began treatment.
High cUuolved solids causing mineral depositS on the streambed is the likely cause for poor continued
aquatic babitaL 1b.is situation will be addressed as part of the selected remedy.
10.
Question: How mucb tax money has been spent on this RI/FS study?
Response: Nothing. The study has been paid for totally by the NWSPCC. The EP A. along with the
DNR, has bad expenses in oversight of these projects. That is not tax money, per se, and that money,
in aU likelihood, will be recovered from the responsible pat]ies at the conclusion of the projectS.
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11.
Question: What happens if we have a couple ohery wet years and it rains a lot and the quarry begil\r
to refill?
12.
Response: NWSPCC will have equipment in place to keep the quarry dewatered.
Question: What about the method that was overlooked because of the costs (Waste Stabilization)?
Response: Other than costs, there are other potential problems with stabilization of the kiln dust.
It would be very difficult to implement and its success would be uncertain. Assuming it was
successful, it would be the best option because there would no longer be any potential for interaction
with the kiln dust. In the Superfund process there are a number of evaluation criteria that, are looked
at. It was concluded that the selected alternative presents the best trade-off among the alternatives.
13.
Question: How much has Nonhwestem States had to spend on remediation, to date?
Response: To date, approximately $750,000 has been spent on the project. Another million and a
half is anticipated.
14.
Question: How many gallons of acid have been used to neutralize the 400 million gallons of water
that were in there?
15.
Response: Approximately SOOO gallons per week.
Question: How thick would the clay cap be?
Response: That layer would depend on what was determined necessary to efl'ectively reduce
infiltration of water. There is no specific thickness required. The cap is an additional safeguard.
since aU the water which would be generated from the site would be coUected in the dewaterinr
system in any event. The cap prevents contaminated water from being produced in the first place.
16.
Question: Are there other cement plants around the state where this is going on?
Response: The Lehigh Portland Cement Company site just north of NWSPCC has a similar problem.
17.
Question: How would you characterize a degree of human risk from this problem?
R~nSe: It is very low. However, prior to dewatering of the West Quarry, the high pH water in
the quarry posed a human risk from direct contact. '
18.
Questton: Wu it known to be low when you started?
Res... No. The extent of mntamination and degree of risk were not known. It was the objective
of \be IUIPS to determine those.
19.
Question: It you knew then what you know now, would you have required Northwestern States to
go through aU this? '
Response: It we knew then what we know DOW, they wouldn't have had to mnduct the RIIFS, but
they would still have had to do the remediation that is being proposed. While the human risk is low,
adverse environmental impact to Calmus Creek is a confirm~'problem which needs to be addressed.
Also, without remediation there would be potential impacts to groundwater which could alf'ect current
or future water supplies.
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20.
Question: Where does Northwestern take its kiln dust now, since 1985?
21.
Response: They no longer generate kiln dust. They have changed their source of raw materials so
the kiln dust can be placed back into the product without adversely impacting the product.
Question: Did the State receive any comments from people who were concerned about their drinking
water?
Response: No such comments were received.
22.
Question: Could you summarize why it was the second least expensive alternative chosen as the
proposal here?
Response: The least expensive alternative was not chosen because it did not address the existing
groundwater contamination at the site. Of the remaining alternatives, aU of them were believed to
meet the regulatory requirements. They were believed to provide long-term, permanent solutions to
the problem. The selected alternative was chosen because it was the least expensive and managed to
meet aU of the other criteria. In addition, the stabilization of the kiln dust was questionable as to
whether or not it could be implemented realistically and effectively. The off-site disposal of kiln dust
alternative raised whole new issues and brings potential for moving a problem to another site and
raising a lot of public concern about an additional site.
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