United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R06-87/015
November 1986
&EPA Superfund
Record of Decision:
\
Mid-South Wood, AR
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing}
1. REPORT NO.
[EPA/ROD/R06-86/015
3. RECIPIENT'S ACCESSION NO.
14. TITLE AND SUBTITLE
SUPERFUND RECORD OF DECISION
Mid-South Wood Products, AR
First Remedial Action
5. REPORT DATE
November 14. 1986
«. PERFORMING ORGANIZATION CODE
7, AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
1. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final ROD Report
14. SPONSORING AGENCY COOE
800/00
IS. SUPPLEMENTARY NOTES
16. ABSTRACT ~~~~—— ————————.
The Mid-South Wood Products site is located in Polk County, Arkansas, approximately
1/2 mile southwest of Mena, Arkansas. The 57-acre site includes the following areas:
the Old Plant site, the Small Old Pond and Old Pond areas, the North and South
Landfarms, the landfill, Clear Lake and an existing chromated copper arsenate (CCA)
treatment plant. The Old Plant site was used to treat wood with pentachlorophenol (PCP)
and creosote; the Small Old Pond was the original impoundment for waste PCP and
creosote. These two areas have been covered with soil. The Old Pond area was used to
store PCP and creosote sludge and has since been graded and covered with soil; materials
from the Old Pond were spread over the Landfarm areas and mixed into the soil; the
Landfill area contains deposits of sawdust, woodchips, and other waste wood products;
Clear Lake receives runoff from all the above areas; the CCA treatment plant contains an
ongoing wood treating operation where the surface drainage from the plant is put in
sumps.
The plant site was originally developed by a lumber company in the late 1930s as a
post and pole production plant. In 1967, Edward Hines Lumber Company purchased the
plant and operated it as a PCP and creosote wood treating plant until 1977 when the CCA
treating process was first introduced at the plant. In September 1978, Edward Hines
Lumber Co. sold the plant to Mid-South Wood Products, Inc. Investigation of the
ISee Attached Sheet)
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Record of Decision
Mid-South Wood Products, AR
First Remedial Action
Contaminated Media: sw, gw, surface soils,
surface sediments
Key contaminants: creosote compunds (PAHs),
PCP, CCA, arsenic, chromium
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (Tins Report/
None
21. NO. OF PAGES
73
20. SECURITY CLASS (Tllispage!
None
22. PRICE
EPA Form 2220-1 (R«v. 4-77) PREVIOUS COITION i» OBIOLCTE
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EPA/ROD/R06-86/015
Mid-South Wood Products, AR
First Remedial Action
16. ABSTRACT (continued)
Mid-South Wood Product site began in 1976 when several fish kills were
reported in waterways downstream of the site. The Arkansas Department of
Pollution Control and Ecology (ADPC&E) tested the ground water, surface
water, ponds, and three wells; they found low levels of PCP in the wells and
higher levels in the surface water samples and arsenic and chromium in the
ground water and surface water. In December 1981, ADPC&E concluded that a
contamination problem existed and recommended initial remedial actions be
taken. Contaminants were found in the site surface soils, surface
sediments, surface water, and ground water beneath the site. The primary
contaminants of concern include: creosote compounds (PAHs), PCP, CCA,
arsenic, and chromium.
The selected remedial action includes: excavation of onsite contaminated
soils, with the exception of those existing in the Old Pond area, and
consolidation with the contaminated soils in the North Landfarm area;
stabilization of any free oil, liquid, or sludge found in the heavily
contaminated area of the Small Old Pond/Old Plant area and placement of
these wastes in the North Landfarm area; grading and covering the
contaminated soils consolidated in the North Landfarm and RCRA top-soil clay
cap; investigating the Old Pond area to locate any free oil, liquids, or
sludges and in-situ stabilization of these materials; capping the Old Pond
area with a RCRA top-soil clay cap; remedial action at the CCA treatment
facility; completing installation of the french drain system at the site and
pumping water to the treatment system; treating the ground water by removing
organics through carbon filtration (any ground water found to be
contaminated with inorganics will be treated by carbon filtration then used
as makeup water for the CCA treatment facility); disposal of oils and
sludges collected in the french drains in an EPA approved hazardous waste
disposal facility; discharging treated water from the ground water treatment
facility to surface drainage; and installation of a ground water monitoring
system. The estimated capital cost is approximately $3,500,000 with annual
O&M costs of $153,500.
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j^ '«v
J* — '*
f A \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
* REGION VI
? 12O1 ELM STREET
DALLAS, TEXAS 7S27O
RECORD OF DECISION
SITE
Mid-South Wood Products located in Polk County, Arkansas, approximately
1/2 mile southwest of Mena, Arkansas.
DOCUMENTS REVIEWED
I am basing my decision on the following documents describing the analysis
of cost-effectiveness of remedial alternatives for the Mid-South Wood
Products site:
B&F Engineering, Inc., 1984. Phase I and II Report Site Investigation,
Mid-South Wood Products, Inc. Prepared for Edward Nines Lumber Company.
B&F Engineering, Inc., 1983. Phase I Report Site Investigation, Mid-South
Wood Products, Inc. Prepared for Edward Mines Lumber Company.
Environmental Protection Agency, 1986. Feasibility Study Report, Mid-South
Wood Products Site, Mena, Arkansas. Prepared by CH2M Hill Southeast, Inc.
Environmental Protection Agency, 1986. Supplemental Remedial Investigation
- CCA Plant, Mid-South Wood Products Site, Mena Arkansas. Prepared by
Hill Southeast, Inc.
Environmental Protection Agency, 1985. Endangerment Assessment, Mid-
South Wood Products Site, Mena, Arkansas. Prepared by Q^M Hill Southeast,
Inc.
Environmental Protection Agency, 1984. Remedial Investigation Report,
Mid-South Wood Products Site, Mena, Arkansas. Volumes 1, 2, and 3.
Prepared by Soil 4 Materials Engineering, Inc. and CH2M Hill Southeast,
Inc,
Law Engineering Testing Company, 1984. Phase II Hydrogeologic Investigation,
Mid-South Wood Products Site, Mena, Arkansas. Prepared for Edward Hines
Lumber Company.
Law Engineering Testing Company, 1983. Phase I Hydrogeologic Investigation,
Mid-South Wood Products Site, Mena, Arkansas. Prepared for Edward Hines
Lumber Company.
0 Summary of Remedial Altenative Selection.
0 Public comments received during April 28 - May 19, 1986, on the Feasibility
Study.
0 Community Relations Responsiveness Summary, November 1986 (attached).
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Summary of Remedial Alternative Selection
Mid-South Wood Products
Mena, Arkansas
October 1986
TABLE OF CONTENTS
Site Location and Layout 1
Si te Hi story 4
Site Status 5
Nature and Extent of Contamination 10
Enforcement 19
Alternatives Evaluation Summary 21
Community Relations 53
Remedy 54
Schedule 57
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MID-SOUTH WOOD PRODUCTS SITE
RECORD OF DECISION
NOVEMBER 1986
ERRATA
The figures used in this document to illustrate the site depict the
site boundaries incorrectly. Edward Hines Lumber Co., Inc. (potentially
responsible party) has recently purchased a tract of land that previously
bordered the site along the southwest property line. Therefore, contamin-
ated soil and groundwater considered offsite during the development of the
feasibility study and located in this southwestern drainageway is now
part of the site (i.e., the site boundaries have been extended to the
southwest to include all offsite contamination found in that area during
site investigations).
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SITE LOCATION AND LAYOUT
The Mid-South Wood Products site is located in western Arkansas, approximately
1/2 mile southwest of downtown Mena, in Polk County (Figure 1). The
Mid-South site is comprised of approximately 57 acres. The northeastern
half of the site contains an ongoing wood treating operation which is
using a chromated copper arsenate (CCA) process. The current site layout
is depicted in Figure 2.
Areas of remedial investigation for the Mid-South site include the Old
Plant site, the Small Old Pond and Old Pond areas, the North and South
Landfarms, the Landfill, Clear Lake and the existing CCA treatment plant.
The Old Plant site is where the pressure cylinders used for treating wood
with pentachlorophenol (PCP) and creosote were located. The Small Old
Pond was the original impoundment for waste PCP and creosote and is
located adjacent to the Old Plant. The Old Plant site and Small Old Pond
areas occupy approximately 10,000 square feet and have since been covered
with soil.
The Old Pond is an area west of the Old Plant site, approximately 112,500
square feet in size, where PCP and creosote sludge were stored before the
pond was filled in. The landfarm areas are located on both sides of a
ridge running through the southwest part of the plant property. The area
south of the ridge is approximately 84,000 square feet and drains to the
south and west. The area north of the ridge is approximately 150,000
square feet and drains to the north. These are areas on which material
from the Old Pond was spread over the surface and mixed into the soil as
part of the Old Pond closure. Some of the mixture was put back into the
Old Pond area. The Old Pond area has been graded and covered with soil.
The Landfarm areas have not been covered.
The Landfill area is the result of depositing sawdust, woodchips and
other waste wood products in a swale area to the west of the Old Plant
and north of the Old Pond. The swale has been filled to approximately
the surrounding grade and has no vegetative cover. In 193U, Mid-South
constructed a dike across the lower end of the landfill to contain runoff
which in turn created a small area of ponded water called Clear Lake.
Clear Lake apparently receives runoff from the Landfill, the Old Plant
and Small and Old Pond areas.
The existing CCA treatment plant is located adjacent to the Old Plant
Site. It consists of a pressure-treating cylinder, several elevated
tanks for storage of the treatment solution, a concrete drip pad and a
wood drying kiln. Thf concrete drip pad is used to collect excess CCA
solution which 1s allowed to drip onto the structure after treatment.
Once the lumber has dried, it is stored in an area located in the
northeastern section of'the site. Some surface drainage from the CCA
plant area is contained by either concrete-lined sumps at the drip pad or
an unlined overflow sump adjacent to the treatiny cylinder.
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DESCRIPTION OF THE REMEDY
The Feasibility Study evaluated alternative treatment technologies including
Incineration and biological treatment. These technologies were not retained
due to engineering impracticability (a detailed discussion can be found
1n the Summary of Remedial Alternative Selection).
EPA has negotiated a remedy with the potential responsible parties which
Includes a remedial action plan summarized below.
0 Excavation of on-site contaminated soils, with the exception of those
existing in the Old Pond area, and consolidation with the contaminated
soils in the North Landfarm area.
0 Stabilization of any free oil, liquid, or sludge found in the heavily
: contaminated area of the Small Old Pond/Old Plant area and placement
of these wastes in the North Landfarm area.
0 The contaminated soils consolidated in the North Landfarm will be graded
and covered with a RCRA top-soil clay cap.
I • ° Field investigation Into the Old Pond area to locate any free oil,
: liquids or sludges. Insitu stabilization of these materials.
0 The Old pond area will be covered with a RCRA top-soil clay cap.
0 Remedial action at the CCA treatment facility.
9
• * Complete Installation of the french drain system already partially
> Installed at the site and pump water to the treatment system.
\
0 Treat the ground water by removing organics through carbon filtration.
Any groundwater found to be contaminated with Inorganics will be treated
by carbon filtration then used as makeup water for the CCA treatment
[ facility.
0 Dispose of oils and sludges collected 1n the french drains 1n an EPA
approved hazardous waste disposal facility.
0 Discharge treated water from the groundwater treatment facility to
surface drainage..
i
0 Installation of a groundwater monitoring system to monitor the effective-
ness of the remedy.
Selection of this remedy is contingent upon the responsible parties
performing bench studies during the remedial design and providing EPA
with results that support the use of stabilization as part of the remedy.
If stabilization proves ineffective, an alternative action will be required
for those wastes for which stabilization has been proposed.
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DECISION
Consistent with the Comprehesive Environmental Response, Compensation,
and Liability Act of 1980 (CERCLA) and the National Oil and Hazardous
Substance Contingency Plan (40 CFR Part 300), I select the remedy described
above for the Mid-South Wood Products site. I have determined that this
1s cost-effective and is protective of public health and welfare and the
environment. The action will require operation and maintenance to maintain
the effectiveness of the remedy. Since wastes will be left on-site, the
remedial action will be reviewed every five years to assure that the remedy
1s still protecting public health and the environment. The State of
Arkansas has been consulted on EPA's remedy (I.e., Combined Excavation
and Groundwater Recovery/Treatment) which was the basis for the negotiated
remedy, and provided verbal concurrence. I have considered the cleanup
standards of Section 121 of the Superfund Amendments and Reauthorization Act
of 1986 (SARA), Including the cleanup standards thereof, and certify that
the portion of the remedial action covered by this Record of Decision
complies to the maximum extent practicable with Section 121 of CERCLA
(as amended by Section 121 of SARA).
Negotiations with the potentially responsible parties have been successful
regarding the selected remedy; however, in the event that negotiations on
the Consent Decree are unsuccessful, on-going litigation will be pursued
by EPA and the Department of Justice in an effort to secure performance
of the remedial action.
V ^TA^^t^
__^_ '***_ (0
Date Trarices E. Phillips
Acting Regional Administrator
Attachments
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SITE HISTORY
The plant site was originally developed by Nebraska Bridge Supply and
Lumber Company as a post and pole production plant in the late 1930's.
Nebraska Bridge Supply and Lumber Company, operating under the name of
Three States Lumber Company, installed the first pressure-treating system
1n 1955.
The plant was purchased by Edward Mines Lumber Company 1n 1967. The
plant was operated as a pentachlorophenol and creosote wood treating
plant by Nines until 1977 when the CCA treating process was first introduced
at the plant. Edward Hines Lumber Company sold the plant in September of
1978 and the new owner soon afterwards formed the corporation of Mid-South
Wood Products, Inc.
Since the CCA plant was designed to be a closed loop, recycling system,
and Mid-South Wood Products, Inc., did not plan to use PCP or creosote in
their operation, the Old Pond was no longer required after 1978, although
some CCA wastewater apparently was put into the Old Pond during the first
year of operation. The pond was reportedly closed by pumping the sludye
from the pond, spraying it over the Landfarm area, and mixing the sludge
into the soil. A portion of the soil and sludge mixture was placed back
into the pond leaving the remaining waste mixture on the Landfarm area.
Use of the CCA wood treating process has continued since 1977, and is
currently ongoing.
The site has been under investigation since 1976, when it was reported
that Rock Creek and the Mountain Fork River suffered a 100-percent fish
kill for a distance of 8 1/2 miles downstream of the site and a 10 percent
fish kill to a distance of 17 1/2 miles downstream of the site. An
Arkansas Game and Fish officer traced the kill back to the site, which
was owned and operated at that time by Hines Lumber. An 8-inch pipe
existed at that time from the Old Pond to the drainage ditch along the
southern boundary of the property. The drain valve had apparently been
opened and part of the pond contents released. There is some indication
from the records that several fisn kills had previously occurred in
waterways downstream of the site, although it is not stated whether the
cause was traced to the Hines1 property.
Subsequent to the fishkill, state and federal agencies began testing for
the presence of PCP, arsenic and chromium on private property west and
northwest of the Mid-South site. Testing was initiated by the Arkansas
Department of Pollution Control and Ecology (ADPC&E) in November 1980
with the collection of groundwater samples and sediment samples at and
adjacent to a nearby pond. Results from these samples revealed the
presence of low levels of PCP, arsenic and chromium in some groundwater
and surface water samples. In February 1981, water from four nearby
wells was analyzed by the EPA which reported finding PCP (10 ppb) in
one well. About this same time, the Arkansas Department of Health tested
water from a pond, spring, and three wells. The Department of Health
found trace levels of PCP in the wells and higher levels in surface water
samples. In December 1981, the ADPC4E performed sampling at the Mid-South
site. They concluded that a contamination problem existed and recommended
that initial remedial actions be taken.
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In 1982, the Mid-South Wood Products site was added to the proposed
National Priorities List under the Comprehensive Environmental Response,
Compensation and Liability Act of 1980 (CERCLA or "Superfund").
On March 31, 1983, ADPC&E issued an Administrative Order, requiring that
Mines and Mid-South, as potentially responsible parties (PRPs), perform
certain short term remedial actions and that they submit a work plan for
a full investigation of the site to be conducted on a specified schedule,
On December 17, 1983, the ADPC&E requested that the EPA implement a
remedial investigation/feasibility study (RI/FS) to develop alternative
remedial actions for the site.
SITE STATUS
In late 1983, the EPA issued a work assignment through its Zone II Superfund
Contract to perform the RI/FS. Activities of the remedial investigation
Included collecting and analyzing surface water, groundwater, surface
soils, subsurface soils, and sediment samples from onsite and offsite
locations. Samples were analyzed for semi-volatile organics (these
Include PCP and primary creosote compounds) and metals (including arsenic
and chromium). Data generated by the responsible parties' consultants
were utilized to the maximum extent possible.
Results of onsite and offsite sampling conducted during the period January
through April 1984 are discussed in the Remedial Investigation Report
(EPA, 1984). In November 1985, a Supplemental Remedial Investigation
(SRI) of the operating CCA plant area was performed. Activities of the
SRI included collecting- and analyzing surface and subsurface soils and
groundwater from the area immediately adjacent to the CCA plant. The
results of the study were presented in the Supplemental Remedial Investigation
Report (EPA, 1986).
Physiography
The Mid-South site and City of Mena are located in the Ouachita Mountains
physiographic sub-province. Both lie In the Caddo Basin and are bounded
by the Fourche Mountains to the north and the Caddo and Cossatot Mountains
to the south. The site is located on the northern flank of a broad
syncline. Bedrock onsite dips to the southwest and consists predominantly
of shale with occasional sandstone beds. Residual soils at the site
consist of clayey silts and sands, silty to sandy clays, and some angular
gravel. The highest point on the site (elevation 1,146 feet msl) is
found in the north-central -area. Site relief is approximately 25 feet.
The site's natural topography has been modified by activities associated
with the wood-treatment processes. These include the excavation for
waste storage and later filling of the Small Old Pond and Old Pond areas,
filling of the Old Plant area, establishment of the Landfill and two
Landfarms for waste disposal, and creation of Clear Lake.
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Surface Water Hydrology
Surface water drainage in the vicinity of the site and surface drainage
patterns at the site are shown in Figures 3 and 4. A drainage divide
(maximum elevation of 1,146 feet) crosses the eastern half of the site
1n a northwest to southeast direction passing through the CCA plant area.
Drainage east of this divide is via an unnamed tributary and drainage ditch
Into Prairie Creek, a tributary of the Ouachita River. West of the
divide, most of the site drainage is through Clear Lake, East Fork Moon
Creek (which passes through Pope Pond), Moon Creek, Rock Creek, Mountain
Fork River, and eventually into the Little River. There is also a diversion
ditch around the north end of the landfill which intercepts surface
runoff from the current Mid-South operation before emptying into East
Fork Moon Creek. Along the south border of the site, there is some
offsite drainage along an ephemeral stream system which parallels the
railroad tracks. Southwest of the topographic divide this stream system
intercepts site drainage from the South Landfarm area and the Old Pond
area (Figure 4), and apparently received waste from the Old Pond prior
to 1976 or 1977. East of the topographic divide the stream system inter-
cepts runoff from the drip pad, part of the CCA plant and from treated
wood storage areas.
Groundwater Hydrology
Groundwater at the site occurs primarily in weathered bedrock and in
fractured sandstone and shales. Soils onsite have low hydraulic conducti-
vities and limited capacities to transmit water. A major fracture zone
onsite is* associated with a fault which trends through the site from west
to cast along the trace of the East Fork of Moon Creek. This fault,
named the "anomolous zone" by the Mines' consultants, is characterized by
highly fractured shales and strikes northwest through the site, underneath
the Old Pond area. The depth to water in the bedrock varies from 10 to
30 feet below land surface.
Groundwater flows at the Mid-South site are controlled primarily by
topography and follow a pattern similar to that described for surface
water (see Figure 5). East of the divide, groundwater flows offsite to
the east and southeast. West of the divide, groundwater flows to the
west, south, and southwest. Much of it passes through the Landfill (an
area with high water level), then radially into East Fork Moon Creek,
Moon Creek, and the Old Pond area.
Beneath the topographic ridge at the Landfarm is a groundwater high for
the site. This appears to be a recharge area and groundwater flows
radially from this area. Groundwater on the north side of the Landfarm
flows to the north to East Fork Moon Creek. The water table contours
indicate that groundwater is discharging into the stream. Groundwater
also flows west and south of this divide toward the drainage feature
paralleling the railroad track to the south and ultimately discharges
into Moon Creek within one-half mile west of the Mid-South site.
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10
Water Supply
The City of Mena and several of the smaller towns have developed surface
water supplies. Mena receives its municipal water supply from Ward Lake
and Irons Fork reservoir located approximately 2.5 miles north and 6
miles northeast of the site, respectively. The two sources are projected
to give Mena a yield of 8.6 million gallons per day. The remainder of
the rural water supply comes primarily from groundwater, which occurs in
the Paleozoic age bedrock. These rocks are not a major aquifer and
groundwater is derived principally from the secondary porosity of the
rock. The quality of the groundwater is considered only fair due to
elevated concentrations of iron and manganese, and it generally requires
treatment for municipal water supplies.
Several private water wells are located around the site. Recently, Mines
Lumber Company has extended the city water supply pipeline along County
Road 375 to eight homes located downgradient of the Mid-South site that
were previously on private wells. This action has effectively removed
all known downgradient groundwater usage between the onsite source areas
and the groundwater discharge area along East Fork of Moon Creek.
Cultural
Polk County is a rural county with approximately 65 percent of its population
in rural areas. Polk County had a population of about 14,800 people in
1975 with the City of Mena being the largest single population center
with about 4,500 people. The majority (83 percent) of Polk County is
forested and about 15 percent is agricultural land. There are approximately
720 farms in Polk County with cattle and chickens as the major agricultural
products.
NATURE AND EXTENT OF CONTAMINATION
The Mid-South site 1s the repository for waste products from three
separate wood-preservative processes. These wastes contain a suite of
creosote compounds (known as polynuclear aromatic hydrocarbons, PAH);
pentachlorophenol, (PCP); and chromated copper arsenate (CCA).
The most commonly detected organic compounds present in samples collected
during the remedial-investigation are listed below:
Pentachlorophenol Chrysene
Acenaphthene Acenaphthylene
Fluoranthene Anthracene
Naphthalene Fluorene
Benzo(a)anthracene Phenanthrene
Benzo(a)pyrene Pyrene
Benzo(b)f1uoranthene Dibenzofuran
Benzo(k)f1uoranthene 2-Methylnaphthalene
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11
The Inorganic contaminants found on the site are arsenic and chromium.
Eight soil samples from the site were analyzed for dioxln (2,3,7,8 TCDD)
and none was detected. Table 1 presents a summary of mean values of each
contaminant found onsite and offsite**, listed by sampling media. Table
2 presents similar data on contaminants from near the CCA plant. A more
detailed evaluation of contaminants 1s available In the RI Report (EPA,
1984), the Endangerment Assessment Report (EPA, 1985), and the SRI Report
(EPA, 1986) for the Mid-South site.
** A majority of the property considered offsite during the site investi-
gation has been purchased by Edward Mines Lumber Co. The site boundaries
have now been expanded to Include this property. Additionally, a
portion of the offsite contamination exhibited in Table 1 may now be
found in this area.
The majority of the contaminants are associated with the surface soil and
subsurface contamination in the form of oils, groundwater and soil/sludge
mixtures. Since the Old Pond was closed out, as described previously,
there is an unknown amount of non-absorbed (free) oil, containing creosote
compounds and/or PCP, located in and around the Old Pond/Small Old Pond
and Old Plant/CCA Plant areas. The. oil 1s primarily located in fill
.material, weathered bedrock (soil) and bedrock fractures.
Trenching exploration by Mines' consultants also located free oil near
Moon Springs. It appears that some of the oil has migrated from the
Old Pond area to Moon Springs via the geologic fault located during the
site Investigations.
Considerable quantities of contaminated soils and sludges exist primarily
in the Pond and Landfarm areas. To evaluate the extent of contaminated
soil on the site, concentrations of each contaminant were compared with
depth and location data collected during the site remedial investigations.
Figures 6 to 9 present the areal distribution of the contaminated soil
for arsenic, chromium, pentachlorophenol and creosote compounds (sum of
PAH compounds). The actual depths of contaminants vary with the area.
The figures showing the extent of contaminant distribution were developed
utilizing the following assumptions: the sampling efforts had adequately
characterized contamination at the site; and contamination varied uniformly
between sampling points in both concentration and distribution.
As Indicated on Figure 6, the largest amount of contaminated soil which
contains over 20 pom of arsenic 1s located within a 200-foot radius of
the current CCA plarit with a maximum observed concentration of 1435 ppm
of arsenic. Chromium concentrations Indicate a similar pattern. The CCA
process area Is the main source of arsenic and chromium contamination at
the Mid-South site. A RCRA-related Inspection performed.in April 1985
identified several problem areas within the CCA plant that were contributing
to the release of contaminants. The Supplemental Remedial Investigation
performed in November 1985 confirmed the release of-CCA solution from the
plant area.
Tables 1 and 2 indicate the degree of contamination found in groundwater
on the site. As the mean values illustrate, there is considerable
contamination onsite, primarily organic compounds.
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Table 2 .
ARITHMETIC MEANS OF CONTAMINANTS (ppb), MID-SOUTH WOOD
PRODUCTS SITE
CCA PLANT SITE AREA, 1985 SAMPLES
Groundwater Surface Soils Subsurface
Well 14,15,16,17 (0 - 12") Soils
Arsenic 18 198 2
If Chromium, Total 183 22 104
U Fluoranthene 263 33,513 20,439
Pentachlorophenol 10,230 187,627 47,387
EPyrene 194 29,078 14,545
Acenaphthene 437 5,136 23,511
Acenaphthylene . ND ND ND
Benzo(a)anthracene 35 3,372 2,602
Benzo(b)pyrene ND 1,215 786
Benzo(b)fluoranthene ND 10,579 941
Benzo (JO fluoranthene ND 1,801 770
Chrysene • 37 5,527 2,985
Dibenzofuran 300 3,709 17,410
Fluorene 280 4,845 18,488
• 2-Methylnaphthalene 730 12,091 33,953
Naphthalene 2585 2,200 44,912
Phenanthrene 617 10,007 38,264
, Anthracene 127 1,462 9,187
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ND • Not Detected
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18
The present physical condition of the site is unvegetated rolling topography
which is subject to considerable soil erosion during rainfall events.
Some temporary erosion control measures such as hay bale dikes and silt
fences have been implemented by Nines Lumber, but with very limited
success due to the large volume of sediment which erodes from the site.
The presence of PCP (a potent herbicide) in the soil prevents the establish-
ment of a vegetative cover under existing surface conditions. Given the
present site conditions, there Is ongoing migration of contaminated
sediment and runoff from the site along with movement of contaminated
groundwater and creosote compounds toward Moon Spring and Moon Creek.
There also appears to be migration of surface runoff primarily from the
CCA plant site to the east, toward Prairie Creek.
Pathways of migration from the contaminant sources onsite are by:
1) Surface drainage westward Into Moon Creek;
2) Surface drainage eastward into Prairie Creek;
3) Subsurface (groundwater) movement westward to Moon
Creek; and
4) Subsurface (groundwater) movement southwestward
and eastward from the CCA plant.
There are no known drummed or liquid hazardous wastes on the Mid-South
site other than about 270 drums of Investigation derived wastes (contaminated
waten, disposable clothing and drilling wastes) from the RI and SRI field
work. This material will be Incorporated Into the remedial action for
the site.
Future Effects of Contaminants
Of the contaminants found on the site, six are recognized as carcinogens
or suspected carcinogens. These are: arsenic; benzo(a)pyrene; benzo(a)
anthracene; benzo(b)f1uoranthene; benzo(k)f1uoranthene; and chrysene.
Additional contaminants of concern for toxic effects are chromium, naph-
thalene, and pentachlorophenol. The health and environmental effects of
these compounds are addressed In the Endangerment Assessment Report (EPA,
1985).
Without some change<1n the physical condition of the site, the migration
of contaminants will continue westward Into Moon Creek and eastward
toward Prairie Creek.. Access to the site 1s presently unrestricted and
the current Industrial operation allows worker access to the site on a
daily basis.
The Endangerment Assessment (EPA, 1985} evaluated the potential public
health impacts of the current site conditions (taking no remedial action)
on individuals under industrial and residential scenarios. These scenarios
were established to simulate existing conditions (industrial) and possible
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19
worst case, future conditions (residential) for the site. Table 3
summarizes the results of the endangerment assessment evaluations. This
table presents a summary for potential carcinogen impacts (increased
cancer risk) and potential noncarcinogen impacts (exceedence of allowable
daily intake rates) by exposure to contaminated media. The information
presented in the Endangerment Assessment supported the following objectives
for remedial action.
Objectives for Remedial Action
The potential health risks Identified for the Mid-South site are based
upon contact with or ingestion of the contaminated soil and groundwater
which contain arsenic and creosote compounds. If the source of contamination
1s removed or controlled, such that ingestion or contact 1s no longer
possible, then the endangerment to human health and the environment 1s
reduced to acceptable levels. Therefore, the following specific remedial
objectives were selected for the Mid-South site.
0 Minimize the threat to public health from the Ingestion of or
contact with onsite contaminated soil;
0 Minimize the threat to public health from direct Ingestion of
shallow groundwater, both onsite and downgradient;
0 Minimize erosion of contaminated soil and offsite migration
to protect public health and environmental quality;
•
0 Minimize leaching of contaminants Into surface water and
groundwater; and
0 Identify cost effective alternatives for remediation of the
site.
Endangerment Assessment (EPA 1985) concluded that the current site conditions
present a potential threat to the public health and the environment.
ENFORCEMENT
EPA has Identified two Potentially Responsible Parties (PRPs) namely,
Edward Mines Lumber Co., Inc. (Mines) and Mid-South Wood Products of
Mena, Inc. (Mid-South). EPA sent Notice Letters to Mines and Mid-South on
March 18, 1982, offering them an opportunity to conduct the site
Investigations. EPA negotiated with the parties for voluntary action;
however, no agreement was reached.
On August 8, 1985, EPA sent Notice Letters to Mines and Mid-South
Informing them of the completion of the remedial Investigation/feasi-
bility study (RI/FS) and EPA's Intent to take remedial action at the
site. However, on August 14, 1985, EPA decided to delay its decision on
a remedy due to potential contamination problems resulting from the
operation of the CCA wood treatment facility (an area which had not been
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investigated during the original RI/FS activities. EPA performed a
supplemental investigation during the winter of 1985. On April 17, 1986,
EPA sent Notice Letters to Mines and Mid-South informing them of the
completion of all RI/FS activities and its intent to take remedial action.
On May 8, 1986, EPA held a Public Hearing in Mena, Arkansas to discuss
with local residents the remedies being considered for the Mid-South
site.
Subsequent to the completion of the RI/FS, EPA has held several meetings
with the PRPs to discuss remedial action. On April 24, 1986, a meeting was
held in Dallas to discuss the Feasibility Study Report. On June 5,
1986, EPA met with the PRPs and listened to their proposal for remedial
action. On September 9, 1986, EPA received a remedial action work plan
from the PRPs. EPA and the PRPs met on September 17, 1986, to discuss
this proposal. Based on the comments provided by EPA during the meeting
and summarized in a letter sent to the PRPs on September 19, 1986, a
revised proposal was received by EPA on October 7, 1986.
ALTERNATIVES EVALUATION SUMMARY
Based on the remedial Investigation and endangerment assessment findings,
remedial action alternatives were developed from a list of applicable
remedial technologies to address the hazards posed by the site. Contaminants
are found in the site surface soils, surface sediments and surface water
and the groundwater beneath the site. Alternatives were developed to
address the contaminants in all media.
Table 4 presents a list of the remedial technologies (grouped by response
action) that were considered as potentially viable solutions for the
Mid-South site. Descriptions of the remedial technologies considered
applicable are summarized below.
Table 4
POTENTIAL REMEDIAL TECHNOLOGIES
Response Action Remedial Technology
Containment Capping, containment barrier,
stabilization
/
Source Removal Excavation and backfill, on-
site landfill, offsite land-
fill
Source Treatment Incineration, leaching/biotreat-
ment, landfarming
Groundwater Remediation Groundwater recovery, groundwater
treatment
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22
Other Responses Fencing, regrading, topsoil
addition and seeding (cover),
deed restrictions, alternate
water supply
In EPA's Feasibility Study Report cleanup action levels were derived to
Unit exposure to contaminated soils. Those contaminants most prevalent
at the site and of the greatest concern form a public health standpoint
were the carcinogenic PAHs and arsenic. Arsenic does not have a cleanup
standard; therefore, the concentrations found in numerous background
samples were evaluated and cleanup level was established for arsenic at
3 ppm (the mean background level).
Carcinogenic PAHs also do not have a simple concentration promulgated as
a cleanup standard. Therefore, EPA must select a cleanup level relative
to a desired excess lifetime cancer risk level. Using a model which was
developed by EPA's Carcinogen Assessment Group, the cancer risk levels
corresponding to a target range of 1x10-4 to 1x10-8 were generated. EPA
selected a 1x10-6 value of 300 ppb as the cleanup level for total carcin-
ogenic PAHs.
Due to the fractured nature of the bedrock below the site, 1t was deter-
- mined that groundwater cleanup would be best accomplished with'large
surface area, french-draln type recovery systems. These systems should
collect the majority of contaminated groundwater leaving the site. All
contaminated surface waters will be treated prior to discharge.
Potential alternatives were screened using relative rating scales based
on cost estimates, effects on public health and the environment, and
accepted engineering practices. A summary of the screening 1s presented
1n Table 5. The alternatives retained after the screening process
Included:
o Onsite Landfill
o Multi-Layer Cap
o Topsoil-Clay Cap
o Soil Treatment
o Combined Excavation/Capping
o Groundwater Recovery/Treatment
Based on the Information developed during the Mid-South Investigation
six remedial alternatives were evaluated as being feasible to eliminate
or minimize the environmental or public health threat posed by the Mid-
South site. '
Each alternative was then developed in more detail and evaluated based on
total present worth costs, public health effects, environmental effects,
technical considerations and Institutional concerns. Table 6 presents
a summary of the detailed alternative evaluation.
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Development of Remedial Alternatives
The technologies listed above represent an assemblage of potential tech-
nologies that could be implemented in various combinations to remediate
the hazardous waste problems at the Mid-South site. Each technology is
applicable for a specific function as part of a remedy and, as such,
represents a portion of the overall remedial action that is necessary at
the site. Where two similar technologies were applicable (and acceptable)
for a single alternative, the lower cost technology was selected.
The Mid-South site presents two media of concern: contaminated surface
soil/sediments and contaminated groundwater. To develop potential remedial
alternatives for these media, the screened technologies were combined to
encompass a range of possible alternatives for this site.
Each alternative, except for No Action and Groundwater Recovery/Treatment,
addresses contaminated soil media (including the small volumes of contami-
nated surface water) to varying extents. The Groundwater Recovery/Treatment
alternative as modified, was determined to be the only possible, effective
alternative for direct groundwater remediation and is presented separately.
This alternative can be combined with any of the other alternatives
depending on the desired level of remediation and cost of Implementation.
"For all alternatives, except for the No Action alternative, the remedial
investigation-derived wastes, described previously will be disposed of by
batch treatment onsite. Contaminated fluid will be treated in the ground-
water treatment unit and solids will be incorporated with solids being
disposed of under the chosen site remedy. Emptied barrels will be cleaned
and salvaged. For the no action alternative, the barrels will be left
onsite. For this small amount of waste, alternative evaluations will not
be made and the same cost is assumed to be additive to each alternatives.
Based on Initial estimates, the disposal cost has been estimated to be
approximately $10,000.
In addition, remedial actions for the CCA plant will be necessary to
control further releases of arsenic and chromium from the plant via
runoff. The drip pad (see Figure 10) has a surface area of approximately
22,000 square feet and during the first hour of a 25-year, 24-hour storm
(0.3 inches/hour 1n Mena) approximately 4,000 gallons of runoff will be
produced from the drip pad. The pad 1s sloped toward the collection
trench and plant sumps to collect the runoff. An open stormwater storage
tank exists, however, the volume of the plant sumps and stormwater storage
tank are not maintained to contain 4,000 gallons of runoff in the event
of a storm. Under current operation, the stormwater pump must be turned
on manually to function. As a result, much of the contaminated runoff is
released to the environment by overflow of the stormwater sump into the
adjacent ditch and overflow sump. In addition, the pad ,1s not completely
curbed and open joints and cracks exist in the concrete providing additional
pathways for migration.
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To remedy the CCA plant releases, better stormwater containment must be
installed and properly operated. The actual volume of stormwater to be
collected will be established based on state or federal regulatory limit-
ations placed on the quality of the water leaving the plant. For estimation
purposes, the first hour of a 25-year, 24-hour storm (4,000 gallons) is
assumed. Under average rainfall conditions this stormwater would be
expected to be heavily contaminated. A stormwater storage tank could be
connected to the existing stormwater sump by a system composed of a level
actuated pump designed to cutoff when the storage tank becomes filled.
The water in the tank should be used as makeup water for the CCA process
or run through a water treatment system prior to discharge.
To contain runoff on the drip pad, the drip pad should be curbed along
its entire perimeter. A 6-inch high by 8-inch wide concrete curb will be
substantial enough to remain Intact and provide the needed drainage
control. Protection against infiltration through the drip pad can be
enhanced by sealing all existing joints and cracks in the concrete.
To implement this alternative for stormwater control at the CCA plant, it
is estimated that the cost would be approximately $12,500. This cost
will be additive to any selected remedial action undertaken at this site.
Description of Alternatives
Upon completion of the screening process, a set of remedial alternatives
was assembled to address the remedial needs of the Mid-South site. The
assembled alternatives were selected to demonstrate a reasonable range of
remedial actions which are applicable to the Mid-South site and which are
based upon technical implementability and environmental suitability
within the limits of the specified objectives. The Groundwater Recovery/
Treatment alternative addresses only groundwater remediation within the
shallow bedrock, and can be combined with any of the other alternatives,
as deemed necessary by the EPA.
A summary of the results of the detailed evaluation of retained alternatives
1s presented in Table 6. Brief discussions of these final alternatives
are presented in the following sections of this document.
Alternative 1 No Action
Section 300.68(f) of the NCP specifies that the "No Action" alternative
be evaluated. Under1 this, alternative, no remedial action would be imple-
mented at Mid-South. Section 300.68(g)(3) states:
"Those alternatives that do not effectively contribute to the
protection of public health and welfare and the environment shall
not be considered further."
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29
The absence of remedial action would allow for long term erosion of the
site due to wind and precipitation. The following threats to public
health and the environment would be posed if no remedy was implemented at
the site:
0 Direct contact with surface soils;
0 Migration due to surface water runoff;
0 Fugitive dust emissions;
0 Migration due to leaching and subsequent groundwater
contamination.
Because the risks to public health and the environment associated with
the "No Action" alternative are unacceptable, this alternative is eliminate
from consideration.
Alternative 2 Excavation with Onsite Landfill
This alternative Includes the construction of an onsite landfill that
complies with provisions of RCRA and State of Arkansas regulations (See
Figures 12, 13 * 14). It has been stated by Nines Lumber Company that
•they own a sufficient amount of property adjacent to the site for
construction of a landfill; therefore, it was assumed that no extra
property needs to be purchased and that a sufficient amount of fill
material Is available on the adjacent property. This alternative
Includes the following operations:
Ar
0 Excavation of onsite and offsite contaminated
soils;
Dust control;
Backfill and grading of the site;
Construction of an onsite landfill;
Waste placement in the landfill;
Fencing of landfill area; and
Implementation of groundwater monitoring and deed
restrictions.
The total volume to be removed 1s approximately 80,000 cubic yards.
Figure 11 shows the extent of total contaminated soils to be excavated
which would meet the above criteria.
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Alternative 3 Multi-Layer Cap
This alternative includes the excavation of wastes and contaminated soil
from areas onsite and consolidation onto the main portion of the site.
An area of 20 acres will be covered by a multi-layer RCRA cap system (See
Figure 15). Site security will be Implemented by Including fencing,
signs, and regular Inspections. Groundwater monitoring will also be
performed. This alternative Includes the following operations:
* Excavation of onsite contaminated soils adjacent
to the CCA plant and in the Moon Creek drainageway;
Excavation of offsite contaminated soil;
Site grading;
Construction of a cap- and cover system;
Groundwater monitoring;
Fencing of site and deed restriction.
Alternative 4 Topsoll-Clay Cap
This remedial alternative has been Included in the detailed evaluation as
.an alternative which will meet the remedial objectives of the Mid-South
site and is a RCRA compliant cap alternative. The primary difference
from the multi-layer cap is the deletion of the synthetic membrane. All
other components of the alternative will be the same as discussed for the
multi-layer cap.
This alternative will allow additional potential Infiltration through the
cap and Into the contaminated soil, however, the calculated reduction of
Infiltration 1s stm over 70 percent as compared with the present conditions
at the site.
This alternative Includes the excavation of wastes and contaminated soil
and consolidation onto the main portion of the site as described for the
multi-layer cap alternative. The entire site area of 20 acres will be
covered by a topsoll-clay cap system. Site security will be Implemented
by Including fencing, signs, and regular Inspections. Groundwater monitoring
will also be performed. This alternative Includes the following operations:
0 Excavation of contaminated soils adjacent to the CCA plant and
1n the Moon-Creek and southwest drainageway;
0 Excavation bf offsite contaminated soils;
0 Site grading;
0 Construction of a cap and cover system;
0 Groundwater monitoring;
0 Fencing of site and deed restriction.
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Alternative 5 Soil Treatment
This remedial alternative (See Figure 16) along with groundwater recovery
and treatment was been inferred as the preferred alternative of Mines
Lumber Company throughout the preparation of the Feasibility Study Report.
As previously mentioned, both alternatives have been investigated by the
consultants for Nines. This combination would include the following
operations:
Excavation of contaminated soil;
Dust control;
Leaching of organic contaminants;
Biological degradation of leachate;
Discharge of effluent to surface drainage.
Alternative 6 Groundwater Recovery/Treatment
This alternative 1s designed to recover contaminated groundwater from six
contaminated locations throughout the site and treat the water to acceptable
levels so that it can be discharged.
•The contaminated groundwater would be recovered by means of six french-drains
as shown on Figure 17. Three of these systems have been partially installed
by Mines Lumber; however, RW-1 is improperly oriented. Further, RW-2
needs to be lengthened, northward to intercept groundwater flowing around
this drain. French-drains built as shown in Figure 18 should be located
as Indicated in Figure 17-for RW-1 (new alignment), RW-2 (extension),
RH-4, RW-5, and RW-6. The design pumping rate of each french-drain would
need to be determined after actual Installation, but for cost comparison,
each system has been sized for 5 gpm.
The treatment system Incorporates the following unit operations and
processes: flow equalization, batch chromium reduction followed by arsenic
and chromium oxidation, precipitation, sedimentation, sand filtration,
carbon adsorption, and sludge dewatering. A schematic of the treatment
train 1s provided on Figure 19.
Alternative 7 Combined Excavation/Capping
Implementation of this alternative Includes: excavation and onsite
landfill Ing for contaminated soil and rock from the Old Pond, Small Old
Pond, and CCA Plant portion of the site; and a topsoil-clay cap for the
landfarm area. This alternative was developed to utilize source removal
(excavation) for the heavily contaminated areas, which exists over a
major geologic fault. The Landfarm area, which presents -a primary threat
through surface runoff contamination would be capped with a topsoil-clay
cap. This alternative includes the following operations:
0 Excavation of the contaminated soil and rock as
noted above;
0 Excavation of the contaminated soils to the southwest and
northwest along East Fork Moon Creek and placement on the Landfarm
area to be capped;
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0 Excavation of any contaminated soils
offsite to the Northeast;
0 Construction of a RCRA-compliant landfill;
0 Backfill, grading and seeding of the excavated areas; •
0 Construction of topsoil-clay cap over the Landfarm
area;
0 Groundwater monitoring;
0 Fencing of site and deed restriction.
Elements of this alternative are Identical to the previously described
alternatives of excavation, onsite landfill and topsoil-clay cap except
for the specific volumes related to each process.
Detailed Evaluation of Costs
This section presents a detailed evaluation of the cost for each
of the previously described alternatives. The cost estimates presented
are order-of-magnitude level estimates. Examples Include estimates from
cost-capacity curves and estimates using scale up or scale down factors
and/or approximate ratio estimate. It 1s normally expected that an
estimate of this type would be accurate to +50% and -30%. The cost
'estimates are presented 1n 1986 dollars.
The feasibility level cost estimates presented have been prepared for
guidance in project evaluation and implementation from the information
available at the time of the estimate. The actual cost of the project
will depend on the final scope of the remedial action as designed by
others, the schedule of Implementation, actual labor and material costs
at the time of bidding, competitive market conditions and other variable
factors that may Impact the project costs. As a result, the final project
costs will vary from the estimates presented herein.
Alternative 1 No Action
No costs associated with this alternative.
Alternative 2 Excavation with Onsite Landfill
Cost
The excavation of contaminated soil from the site 1s a common Item for
several of the alternatives. The volume of contaminated soil to be
excavated to acceptable cleanup levels were discussed previously. The
excavation of 80,000 cubic yards will be required and used for the cost
estimates. Table 7 presents the cost elements for this volume. It is
also assumed that for a variation in excavated volume, the unit prices
will remain constant, (I.e., a 10 percent volume Increase will increase
cost by 10 percent).
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42
Table 7
COST ESTIMATE FOR EXCAVATION
Construction
Cost Element Cost ($)
1. Excavation and hauling of
contaminated soil (80,000 cubic
yards) $413,000
2. Dust control (20 acres) 112,000.
Total $525,000
Table 8
COST ESTIMATE FOR ONSITE LANDFILL
Construction
Cost Element Cost ($)
1. Containment Cell (5.5 acres)
A. Clear and Grub $ 7,000
B. Surface Preparation 13,000
Subtotal $20,000
2. Liner/Leachate Systems
A. Synthetic Liner " $122,000
B. Sand Cushion 58,000
C. Leachate System 87,000
D. Leachate Collection Box 10,000
E. Geotextile 49,000
F. Traffic Layer 39.000
Subtotal ' $365,000
3. Waste Emplacements (80,000 cubic yards)
A. Placement and Compaction $712,000
4. Cover System
A. Earthfill $118,000
B. Sand Cushion 19,000
C. Synthetic Membrane 208,000
D. Drainage Layer 19,000
E. Geotextile. 46,000
F. Vegetative Layer 144,000
G. Perimeter Fence 15,000
Subtotal $569,000
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43
Storm Water Runoff Containment
A. Haul and Fill $1,000
B. Grading/Compaction 2,000
C. Ditch and Bern 7,000
Subtotal $10,000
Leachate Containment Pond
A. Haul and Fill $ 1,000
B. Grade/Compaction 1,000
C. Piping 1,000
D. Synthetic Liner 11,000
F. Closure 8,000
Subtotal $22,000
7. Excavation $525,000
8. Backfill Excavated Area (20 acres)
A. Backfill Material $565,000
B. Grading/Compaction 320,000
C. Seed & Mulch 25,000
D. Perimeter Fence (2,000 feet) 19,000
E. Groundwater Well Installation 18,000
Subtotal $947,000
9. General Requirements
A. Mobilization Bond 4 Insurance 126,000
B. Health and Safety 221.000
Subtotal $347,000
10. Construction Subtotal $3,517,000
A. Bid Contingencies 527,000
B. Scope Contingencies 703,000
Construction Total $4,747,000
C. Permitting and Legal 332,000
D. Services During Construction 332,000
Total Implementation Cost $5,411,000
E. Engineering Design Cost 475,000
3BSSSZ838
TOTAL CAPITAL COST $5,886,000
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44
Table 9
POST CLOSURE ANNUAL COST ESTIMATES
FOR ONSITE LANDFILL
Cost Element Present Worth ($)
1. Long Term Maintenance
A. Mowing $ 15,000
B. Leachate Testing 9,750
C. Leachate Disposal 50,000
D. Annual Inspection 10,000
E. Groundwater Monitoring 42,500
TOTAL $127,250
Alternative 3 Multi-Layer Cap
Cost
Table 10 presents the cost elements for the multi-layer cap alternative.
•The cost estimate is based on the operations previously described.
Capping costs were based on the cover system as shown on Figure 15.
The materials used for the cap were assumed to be hauled from adjacent
property. Fencing costs include the construction of fences around the
perimeter of the site. Level C protective clothing for all personnel
onsite during the construction period (assumed to be 6 months) was used
for estimating purposes. Decontamination costs Include the necessary
equipment and materials needed to decontaminate the personnel and equipment
used. Installation of five additional groundwater wells (in addition to
the existing groundwater monitoring system) was assumed to meet the
needs for groundwater monitoring.
Table 10
COST ESTIMATE FOR
MULTI-LAYER CAP
Construction
Cost Element Costs ($)
1. Excavation and Hauling $ 66,000
2. Capping (20 acres)
A. Clay Liner 546,000
B. Sand Drainage Layers 274,000
C. Synthetic Membrane 758,000
D. Topsoil 334,000
E. Seeding 25.000
Subtotal $1,937,000
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45
3. Fencing (5,000 LF) 38,000
4. Groundwater Well Installation (5 wells) 18,000
5. General Requirements
A. Mobilization Bond & Ins. 82,000
B. Health & Safety 144,000
Subtotal $226,000
6. Construction Subtotal $2,285,000
A. Bid Contingencies 343,000
B. Slope Contingencies 457,000
Construction Total $3,085,000
C. Permitting and Legal 216,000
D. Services During Construction 216,000
Total Implementation Cost $3,517,000
E. Engineering Design Cost 309,000
• JC3S3SS38
TOTAL CAPITAL COST $3,826,000
Table 11 presents the post-closure costs which Include groundwater
sampling and analysis for 5 wells, once per quarter for the first year
and once a year thereafter for 30 years, assuming no contamination
occurs, maintenance (I.e., soil replacement and erosion repair, fence
repair, mowing, and reseeding), and site inspections and security checks,
The costs shown for the post-closure elements are present worth values
discounted using a rate of 10 percent over a period of 30 years.
Table 11
POST-CLOSURE COST ESTIMATE
FOR MULTI-LAYER CAP
Cost Element Present Worth ($)
1. Groundwater'Monitoring $ 42,500
2. Maintenance ' 20,740
3. Site Inspections & Security 20.000
TOTAL PRESENT WORTH $ 83,240
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46
Alternative 4 Topsoil-Clay Cap
Cost
Table 12 presents the cost elements for this alternative. Annual
post-closure costs are the same as Table 11.
Table 12
COST ESTIMATE FOR
TOPSOIL-CLAY CAP
Construction
Cost Element Costs ($)
1. Excavation and Hauling $ 66,000
2. Capping (20 acres)
A. Clay Liner 546,000
B. Sand Drainage Layers 274,000
C. Topsoil 334,000
D. Seeding 25.000
Subtotal $1,179,000
3. Fencing (5000 LF) 38,000
4. Groundwater Monitoring Well
Installation 18,000
5. General Requirements
A. Mobilization Bond and Insurance 52,000
B. Health and Safety 91,000
Subtotal $ 143,000
6. Construction Subtotal $1,444,000
A. Bid Contingencies 217,000
B. Scope Contingencies 289,000
Construction Total $1,950,000
C. Permitting and Legal 137,000
D. Service During Construction 137,000
Total Implementation Cost $2,224,000-
E. Engineering Design Cost 195,000
3833SS83S8
TOTAL CAPITAL COST $2,419,000
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47
Alternative 5 Soil Treatment
Costs
The cost of this alternative has not been evaluated because the consultants
for H1nes Lumber Co. did not furnish any costs of chemical requirements
for the pilot demonstration project on leaching and blotreatment of
organic contaminants 1n soil. Estimates were made for screening purposes
1n the Feasibility Study Report. A range of $4,000,000 to $8,000,000 was
estimated for the treatment of an estimated 80,000 cubic yards of contaminated
soil (plus excavation costs).
Alternative 6 Groundwater Recovery and Treatment
Costs
Table 13 presents the costs for the groundwater recovery system of six
french-dralns and a central water treatment system. The treatment system
1s sized for 30 gpm and the contaminant concentrations as previously
described. These parameters need to be accurately tested prior to design
and Implementation of this alternative. Table 14 presents the present
.worth post closure costs for this alternative. Costs for oil/sludge
disposal are based on assumptions for recovery percentages of, 90% for
the first year and 10% each year thereafter for ten years.
Table 13
COST ESTIMATE FOR
GROUNDWATER RECOVERY AND TREATMENT
Construction
Cost Element Cost ($)
1. French drains and pumps (6 each) $ 209,000
2. Pipeline (12,000 LF) 60,000
3. Power Connection 20,000
4. Controls 15,000
5. Metal Removal System
A. Tanks and reactors 110,000
B. Filter press 15,000
C. Chemical feed system 55,000
Subtotal $180,000
6. Mixed Media Filter 20,000
7. GAC Carbon Columns 200,000
8. Pumps and Piping 20,000
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48
9. Electrical and Controls 30,000
10. Building and Equipment Installation 100,000
11. Perimeter Fence (5000 LF) 38,000
12. General Requirements
A. Mobilization Bond & Insurance 36,000
B. Health & Safety 62,000
Subtotal $98,000
A. Bid Contingencies 149,000
B. Scope Contingencies 198,000
Construction Total $1,337,000
C. Permitting and Legal 94,000
D. Service During Construction 94,000
Total Implementation Cost $1,525,000
E. Engineering Design Cost 138,000
•S333S3S3
TOTAL CAPITAL COST $1,663,000
Table 14
ANNUAL OPERATING COST
GROUNDWATER RECOVERY AND TREATMENT
Cost Element Present Worth ($)
1. Carbon replacement $ 950,000
2. Chemical Cost 19,000
3. Sludge/011 Disposal 94,000
4. Electricity 142,000
5. Manpower ' 283,000
6. Chemical Analyses 377.000
TOTAL $1,865.000
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49
Alternative 7 Combined Excavation/Capping
Cost
Table 15 presents the cost elements and associated construction costs
for this alternative. The cost estimates were based on the construction
procedures and dimensions described 1n this section for the excavation
and landfilllng of 40,750 cubic yards of contaminated soil and rock from
the Old Pond, Small Old Pond and the CCA Plant area, and topsoil-clay
capping of 12 acres of site area. Approximately 5,000 cubic yards of
contaminated soil from the various drainage pathways will be
excavated and placed under the cap.
These costs Include the backfilling/grading and seeding of the excavated
area without the necessity for a complete cover system. Level C protective
clothing for all personnel during construction (assumed to be 9 months)
was used for estimating purposes. Decontamination costs Include the
required equipment and materials needed to effectively decontaminate the
personnel and construction equipment used. Groundwater monitoring wells
are proposed for the excavated and capped area.
Table 16 presents the post-closure costs for the excavation/landfill
.capping alternative. The costs include maintenance (soil replacement and
erosion repair, fence repair and reseeding), leachate removal, Including
disposal, and site inspection and security checks. The post-closure
costs are present worth values discounted using a rate of 10 percent over
a period of 30 years.
Table 15
COST FOR COMBINED EXCAVATION/CAPPING
Construction
Cost Element Cost ($)
1. Containment Cell (3 acres)
A. Clear ft Grub $ 4.000
B. Surface Preparation 7.000
Subtotal $ 11,000
2. L1ner/Leachate Systems
A. Synthetic Liner 67,000
B. Sand Cushion . 32.000
C. Leachate System 47.000
D. Leachate Collection Box 6.000
E. Geotextile 27,000
F. Traffic Layer 16.000
Subtotal $195,000
3. Waste Emplacement (45,750 cubic yards)
A. Placement and Compaction $407,000
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50
4. Cover System for Containment Cell
A. Earthfill $ 65,000
B. Sand Cushion 10,000
C. Synthetic Membrane 114,000
D. Drainage Layer 10,000
E. Geotextile 25,000
F. Vegetative Layer 79,000
G. Perimeter Fence (500 LF) 4.000
Subtotal $307,000
5. Stormwater Runoff Containment
A. Haul & Fill 1,000
B. Grading/Compaction 1,000
C. Ditch & Basin 7.000
Subtotal $ 9,000
6. Leachate Containment Pond
A. Haul & Fill 1,000
B. Grade/Compaction 1,000
C. Piping 1,000
D. Synthetic Liner 7,000
E. Closure 5,000
Subtotal $ 15,000
7. Excavation (45,750 cubic yards) $ 300,000
8. Backfill Excavated Area (45,750 cubic yards)
A. Backfill Material $ 323,000
B. Grading and Compaction 183,000
C. Seed A Mulch 15.000
Subtotal $ 521,000
9. Cap (12 acres)
A. Clay Liner $ 328,000
B. Drainage Layer 164,000
C. Topsoll 201,000
D. Seeding 15,000
Subtotal $ 708,000
10. Perimeter Fence (5,000 LF) $ 38,000
11. Groundwater Monitoring Wells $ 18,000
12. General Requirements
A. Mobilization Bond & Insurance $ 101,000
B. Health & Safety $ 177,000
Subtotal $ 278,000
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51
13. Construction Subtotal $2,807,000
A. Bid Contingencies 421,000
B. Scope Contingencies 561,000
Construction Total $3,789,000
C. Permitting and Legal $ 265,000
D. Service During Construction 265,000
Total Implementation Cost $4,319,000
E. Engineering Design Cost 379,000
TOTAL CAPITAL COST $4,698,000
Table 16
POST CLOSURE ANNUAL COSTS ESTIMATES FOR
COMBINED EXCAVATION/CAPPING
Cost Element Present Worth ($)
1. Landfill 0AM
A. Mowing $ 8,500
B. Leachate Testing 9,750
C. Leachate Disposal 27,500
D. Annual Inspection 10.000
Subtotal $55,750
2. Cap O&M
A. Groundwater Monitoring 42,500
B. Maintenance 12,500
C. Inspection 12.000
Subtotal $67,000
TOTAL PRESENT WORTH $122,750
Alternative 8 Excavation with Offsite Landfill
/
While this alternative was screened from detailed excavations, it will be
used for comparison. A more detailed cost estimate was developed for
this alternative to provide for a more accurate comparison of costs.
This estimate is presented in Table 17.
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52
Table 17
COST ESTIMATE FOR EXCAVATION WITH
OFFSITE LANDFILL DISPOSAL
Construction
Cost Element Cost ($)
1. Contaminated Soil Removal
A. Excavation $ 209,000
B. Loading & Prep. Trucks 120,000
Subtotal $ 329,000
2. Transportation (450 m1]es)
A. Haul (12 CY Trucks) 9,600,000
B. Oept. of Transportation 20,000
Manifest Charges
Subtotal $ 9,620,000
3. Offsite Landfill 8,000,000
4. Backfill Excavated Area
A. Import Backfill Material 565,000
B. Grading/Compaction 320,000
C. Seeding 25,000
D. Groundwater Well Installation 18.000
Subtotal $ 928,000
5.* General Requirements
A. Mobilization Bonds and Insurance 50,000
* B. Health and Safety 88.000
Subtotal $ 138,000
6. Construction Subtotal $19,015,000
A. Bid Contingencies 2,852,000
B. Scope Contingencies 3,803.000
Construction Total $25,670,000
C. Permitting and Legal 1,797,000
* D. Service During Construction 102.000
Total Implementation Cost $27',569,000
* E. Engineering Design Cost 814,000
SSS3SS«3S3S
TOTAL CAPITAL COST $28,383,000
*Excluding Transportation and Disposal Costs
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53
Community Relations
Public Interest 1n the Mid-South Wood Products site during the Initial
phases of the project was minimal. The interest 1n the site increased
moderately upon completion of the feasibility study. The two-week public
notice period began on April 14, 1986. This was followed by a public
comment period which began on April 28, 1986, and ended on May 19, 1986.
On May 8, 1986, a public meeting was held 1n Mena. Arkansas. Approximately
50 people attended the meeting to express their concern about the potential
for EPA's plans for remedial action resulting In the closure of the wood
treatment facility now actively operating at the site. Response to the
comments received during the comment period and public meeting are outlined
1n the "Community Relations Responsiveness Summary" attached to this
Enforcement Decision Document.
Consistency With Other Environmental Laws
As specified in the EPA policy on compliance with environmental statutes
other than CERCLA, the alternatives were developed to correspond to one
or more of the following categories:
-1. Alternatives specifying offsite storage, destruction, treatment, or
secure disposal of hazardous substances at a facility approved under
Resource Conservation Conservation and Recovery Act (RCRA). Such a
facility must also be in compliance with all other applicable EPA
standards (i.e., Clean Water Act, Clean Air Act, Toxic Substances
Control Act).
2. Alternatives that attain all applicable or relevant Federal public
health and environmental standards, guidance, and advisories.
3. Alternatives that exceed all applicable or relevant Federal public
health and environmental standards, guidance, and advisories.
4. Alternatives that meet the CERCLA goals of preventing or minimizing
present or future migration of hazardous substances and protect human
health and the environment, but do not attain the applicable or relevant
standards (this category may Include an alternative that closely approaches
the level of protection provided by the applicable or relevant standards).
5. No action.
The following alternatives for the Mid-South site correspond to the above
categories. The alternatives corresponding to categories 1 and 3 failed
to meet the screening criteria and were not evaluated in detail but are
presented for comparison purposes only.
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54
Alternative Category
No Action 5
Topsoil-Clay Cap 2
Mult1-Layer Cap 2
Soil Treatment 3
Onsite Landfill 2
Offsite Landfill 1
Combined Excavation/Capping 2
Groundwater Recovery/Treatment 2
Onsite Incineration 3
It 1s EPA's policy to select a remedial action that attains or exceeds
applicable or relevant and appropriate Federal environments and public
health requirements. Other Federal criteria and advisories, and State
standards may be used, with adjustments for site specific circumstances.
In the absence of cleanup standards, as defined by regulations or health
advsories, a risk assessment should derive the concentration of contaminants
that represent an excess lifetime cancer risk that falls within a target
range of 1x10-4 to 1x10-8 using 1x10-6 as a point of departure.
Standards have not been established for known or suspected carcinogens
such as polynuclear aromatic hydrocarbons (PAHs) which have been
identified as the primary contaminants providing the "driving force" for
cleanup action at the site. Therefore, EPA's Carcinogen Assessment Group
in Washington, D.C., has developed a model which has been used to calculate
excess lifetime cancer risks for these contaminants.
Based on the use of this model to develop action levels, EPA would be
eliminating any direct contact with these contaminated soils. This
approach is consistent with the intent of Superfund to meet applicable or
relevant Federal regulations.
Compliance with Section 121 of SARA
Section 121 of the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980, as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), states that any Record of Decisions
signed within 30 days of enactment fo SARA must comply to the maximum
extent practicable with §121 of CERCLA (§121(g)).
The selected remedy for the Mid-South site includes a RCRA compliant cap,
solidification of heavily contaminated wastes, groundwater recovery and
treatment, and extensive groundwater monitoring. In the process of selecting
the remedial alternative* a number of remedies were examined if accordance
with the National Contingency Plan, 40 CFR 300.68, and either screened of
retained for final evaluation under 40 CFR 300.68(h).
The following examines the rationale used in screening remedial alternatives
for the site under the NCP, 40 CFR 300.68, and whether this method resulted
in the selection of an appropriate remedy meeting the Intent of $121 of
CERCLA to the maximum extent practicable.
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55
Biological Treatment
As viable treatment alternatives, biotreatment has not been shown to be
effective treatment technology for the wastes onsite and the probability
of failure of this remedy, resulting from wastes not amenable to such
treatments, 1s high. The potential responsible parties conducted studies
on various forms of biological treatment; however, the results of the work
were Inconclusive.
In light of the lack of data to support the engineering practicability of
biological treatment and the risk of failure of this remedy, the promulga-
tion of §121 would not necessitate additional scrutiny of this alternative.
Excavation with Onsite or Offsite Incineration
These alternatives were not selected as the site remedy under 40 CFR
300.68(1). Both would provides permanent remedies for the site.
Offsite incineration is comparable to onsite Incineration, but would
create added risks of exposure while the wastes were being transported
and require an extended treatment period.
Onsite incineration is a proven technology which would permanently destroy
the organic constituents of the wastes and therefore reduce the toxicity
and mobility of the contaminants. However, considering that method used
for disposal of wastes at the site included mixing contaminants with clean
soil (effectively increasing the waste volume), the remaining ash would
still have considerable volume and may remain a hazardous waste since
metals contamination (i.e., arsenic and chromium) exists at the site.
Additionally, Incineration of the 80,000 cubic yards of wastes would
require a considerable treatment period. During this period there would
be a significant increase in potontial for adverse health effects from
human exposure to the excavated wastes and possible accidental disruption
of the incineration leading to an increase in the risk of hazardous
emmlslons.
Furthermore, 1t 1s possible that the ash resulting from this form of
treatment could not be delisted and would have to be disposed of as a
hazardous waste. Therefore, incineration as a treatment alternative for
this site would not be a required alternative under §121 of CERCLA.
Excavation and Offs1te,'D1sposal in a Permitted RCRA Facility
This alternative was not selected as the site remedy under 40 CFR 300.68(1)
Under §121(b)(l), the offsite transport and disposal of hazardous materials
without [permanent] treatment technologies should be the least favorable
alternative remedeal action where practicable treatment technologies are
available. This remedy is therefore unacceptible where other alternatives
are available.
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56
RCRA Compliant Clay Cap
A RCRA compliant cap with stabilization of heavily contaminated soils,
groundwater recovery and treatment, and an extended monitoring program
was the selected remedy under 40 CFR 300.68(1). The contaminants will
remain onsite, and therefore under §121(c) the remedy will have to be
reviewed "no less often than every 5 years after the Initiation of such
remedial action to assure that human health and the environment are
being protected by the remedial action being Implemented".
Wastes onsite will be stabilized and consolidated with lesser contaminated
soils then capped. This will effectively reduce the mobility of the
wastes and reduced the relative toxidty resulting from direct contact.
A cap would greatly reduce infiltration from rainwater minimizing offslte
migration of the contamination. The groundwater recovery and treatment
operations will further reduce the possibility of migration of contaminants
Into the offsite shallow groundwater. Extensive monitoring associated
with the selected remedy would illuminate problems enabling corrective
action to be taken expediantly.
The remedial investigation for the site did not indicate offslte migration
(based on present site boundaries). Endangerment was associated with the
potential for a release and direct contact with the wastes. All applicable
or relevant and appropriate standards, requirements, criteria, or limitations
shall be complied with as required for a remedy in which wastes remain
onsite under §121(d).
Permanent remedies for the site were screened during the selection process
outlined 1n the NCP 40 USC 300.68. However, since the permanant remedies
for the site do not meet the requirements of §121(b), advent of the new
law does not necessitate reevaluating the remedy selection in order to
comply with the congressional Intent of selecting permanent remedies when
it 1s practicable.
A capping remedy with stabilization of heavily contaminated soils, ground-
water recovery and treatment, and extensive groundwater monitoring complies
to the maximum extent practicable with §121 of CERCLA and therefore is an
appropriate remedy for selection within the 30 day period following
enactment of SARA as required in §121{g).
Remedy
i
Section 300.68(1) of the NCP states that "the appropriate extent of
remedy shall be determined by the lead agency's selection of a cost
effective remedial alternative that effectively mitigates and minimizes
threats to and provides adequate protection of public health and the
environment." To this end EPA has negotiated a remedy with the potential
responsible parties (PRPs) which includes EPA's Groundwater Recovery/
Treatment Alternative in combination with a remedial action plan that
will be summarized below.
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57
As stated previously, upon conclusion of the feasibility study, EPA
approached the PRPs offering them an opportunity to conduct remedial
action at the site. The parties expressed an interest in conducting the
remedial work. Negotiations relative to an appropriate remedy have been
ongoing since June 1986.
EPA's position was that there were several areas of concern namely, the
continued migration of contaminated groundwater from the site; the continued
migration of contaminated soils form the site due to surface water runoff;
the continued contamination of groundwater from the heavily contaminated
areas including the Old Plant, Small Old Pond, CCA Plant and Old Pond
areas; and the direct contact hazard posed by the site on the workers at
the wood treatment facility.
EPA's recommended remedial action included a combination of Alternative 6
(Groundwater Recovery/Treatment) and Alternative 7 (Combined Excavation/
Capping).
These alternatives would include:
0 Excavation of the heavily contaminated areas comprising the Old Plant,
Small Old Pond, CCA Plant, and Old Pond.
°* Placement of these wastes in an onsite RCRA landfill.
0 Backfill, grade, and seed excavated areas.
0 Excavation of contaminated soils located along several drainage pathways
and consolidate with contaminated soil in the Landfarm area.
* Construction of a RCRA top-soil clay cap over the landfarm area.
0 Completion of the groundwater recovery and treatment system.
0 Installation of a groundwater monitoring system to monitor the
effectiveness of the remedy.
0 Runoff control at the CCA Plant.
0 Fencing of the site and deed restrictions.
After several negotiating sessions, EPA received a proposal from the PRPs
which was derived from a combination of the EPA's recommended remedial
action technologies discussed above.
The proposal calls for the following activities:
0 Excavation of all onsite and offsite contaminated soils, with the
exception of those existing in the Old Pond area, and consolidation of
the soils in the North Landfarm area.
0 The contaminated soils consolidated in the North Landfarm would
be graded and covered with a RCRA top-soil clay cap.
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58
0 Stabilization of any free oil, liquid, or sludge found in the
heavily contaminated areas of the Small Old Pond and Old Plant
area (Stabilized waste from the Small Old Pond will be consolidated
with materials in the North Landfarm).
0 Field investigation into the Old Pond area to locate any free
oils, liquids or sludges. Insitu stabilization of these materials.
0 The Old Pond area would be covered with a RCRA top-soil clay
. cap.
0 Installation of a groundwater monitoring system to monitor the
effectiveness of the remedy.
o
Backfill, grade and seed (or gravel cover) all excavated areas.
0 Remedial action at the CCA Plant (To be proposed by Mid-South Wood
Products of Mena, Inc. but will be as effective, or more, than EPA's
recommended action).
0 Fencing and deed restrictions.
0 Completion of EPA's Alternative 6, Groundwater Recovery/Treatment,
with the exception of the inorganics treatment system. Any ground-
water found to be contaminated with inorganics would be treated by
the activated carbon system then used as makeup water for the CCA
treatment process. .
As part of'this remedy the potential responsible parties will have to
perform bench studies during the remedial design and provide EPA with
results that support the use of stabilization as part of this remedy.
If stabilization proves ineffective, an alternative approach will be
required for those heavily contaminated materials for which stabiliza-
tion has been proposed.
Cleanup Criteria
As stated above, EPA's Feasibility Study Report developed cleanup criteria
for arsenic (3 ppm) and chromium (10 ppm) based on the mean value of
these contaminants found in background samples. On the other hand, the
action level for carcinogenic PAHs was derived from the EPA's Carcinogenic
Assessment Group lifetime cancer risk model. EPA selected a 1x10-6
concentration for total carcinogenic PAHs (300 ppb) and entered into
negotiations with this platform.
The cleanup criteria resulting from PRP negotiations called for an action
level for arsenic and chromium to be set at any concentration that exceeds
the range of background concentrations (i.e., arsenic > 5.6 ppm and
chromium > 19.4 ppm). The cleanup requirements for total carcinogenic
PAH compounds (benzo (a) pyrene, benzo (a) anthracene, benzo (b) Fluoranthene,
benzo (k) fluoranthene, and chrysene) will be set at a lifetime cancer
risk of 1x10-5 (3 ppm).
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59
The remedial action plan has been thoroughly reviewed by EPA and each of
the technologies incorporated into this proposal appear applicable for a
specific function as part of the overall remedial objectives to protect
human health and the environment at the site.
EPA policy regarding selection of a remedy that attains or exceeds appli-
cable or relevant and appropriate Federal environmental and public health
requirements appear to be satisfied by the negotiated remedy summarized
above. This remedy will be constructed to meet the design standards for
a RCRA topsoil clay cap. Additionally, any free liquids, oils, or sludges
will be excavated from the site and solidified prior to consolidation and
capping, to comply with the free liquid land disposal ban. Also, It is
anticipated that the excavation, consolidation and capping activities can
be completed prior to November 8, 1988, the effective date of the ban on
land disposal of solvents.
The recommended alternative will also include a groundwater monitoring
program to determine if future conditions warrant additional remedial
action.
Costs of Remedy
The estimated capital cost of the remedy is approximately $3.5 million
for soil containment and groundwater recovery and treatment. These costs
are based on estimates provided by the PRPs in their proposal.
Operations and Maintenance
Post-closure operations and maintenance (0 & M) costs have been estimated
at an annual cost of $153,500 or a present worth cost (based on 30 years
at a 10% discount rate) of $1,404,500. The 0 4 M activities Include, but
are not necessarily limited to, groundwater monitoring, maintenance, site
Inspection and security, carbon regeneration, sludge and oil disposal from
the groundwater recovery system, electricity, and sampling and analysis.
Schedule
The schedule for the remedial design and construction of the selected
remedy for Mid-South 1s currently dependent upon reauthorization of
Superfund and the successful negotiation of a Consent Decree. Assuming
Superfund funds are available the design phase will begin once the Consent
Decree 1s signed. The design phase should take approximately 6 to 8
months to complete.
The balance of the remedial action will begin as soon as the remedial
design 1s completed and approved by EPA. This phase of construction 1s
estimated to take 6 to 8 months to complete.
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Attachment 1
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t
COMMUNITY RELATIONS RESPONSIVENESS SUMMARY
ON PREFERRED REMEDIAL ALTERNATIVE
MID-SOUTH WOOD PRODUCTS, MENA, ARKANSAS
This community relations responsiveness summary is divided into the
following sections
I. Overview - This section discusses EPA's preferred alternative for
remedial action, and likely public reaction to this alternative.
II. Background on Community Involvement and Concerns - This section
provides a brief history of site background and community interest
and concerns raised during remedial planning activities at the
Mid-South site.
III. Summary of Major Comments Received During the Public Comment Period
and the EPA Responses to Comments
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I. OVERVIEW
An assessment of possible hazards posed to public health or the
environment was completed In May 1985. This assessment evaluated
the land use of the site; the types, location, and toxicity of the
contaminants found at the site, and the potential exposure and risk
associated with these contaminants. Results of the study Indicated
that remedial action is required to reduce the potential for public
and environmental exposure through:
• ingestlon of contaminated soils;
- direct contact with contaminated soils;
- drinking contaminated groundwater;
• drinking contaminated surface water;
- Inhaling contaminated dust.
In the presentation for the public meeting at the end of the Feasi-
bility Study (FS), the Environmental Protection Agency (EPA) dis-
cussed the remedial alternatives which were examined in the FS,
for addressing the contamination at the site, as follows:
1. No Action Est. Cost: $ - 0 -
2. Excavation and Onslte Landfill Est. Cost: $ 5.6 Million
3. Top Soil-Clay Cap Est. Cost: $ 2.4 Million
4. Multi-Layered Cap Est. Cost: $ 3.8 Million
5. Leaching and Biological Treatment Est. Cost: $ 4 to 8 Million
6. Excavation and Backfill with Est. Cost: $ 28.4 Million
Offsite Landfill Disposal
7. Groundwater Recovery and Est. Cost: $ 1.6 Million
Treatment
8. Combined Excavation/Capping Est. Cost: $ 4.7 Million
EPA's recommended remedial action Included a combination of Alternative
6 (Groundwater Recovery/Treatment) and Alternative 7 (Combined Excava-
tion/Capping). These alternatives would Include:
- Excavation of the heavily contaminated areas comprising the
Old Plant, Small Old Pond, CCA Plant and Old Pond.
- Placement of these wastes in an onsite RCRA landfill.
- Backfill, grade, and seed excavated areas.
- Excavation of contaminated soils located along several drainage
pathways and consolidate with contaminated soil in the Landfarm
area.
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- Construction of a RCRA top-soil clay cap over the landfarm
area.
- Completion of the groundwater recovery and treatment system.
- Installation of a groundwater monitoring system to monitor
the effectiveness of the remedy.
- Runoff control at the CCA Plant.
- Fencing of the site and deed restrictions.
Subsequent to several negotiating sessions with the potential responsible
parties (PRPs), Edward Hines Lumber Co., Inc., and Mid-South Wood Products
of Mena, Inc., EPA received a proposal from the PRPs for a remedial action
which was derived from a combination of the EPA's recommended remedial
action technologies listed above. This proposal, in' addition to specific
requirements made by EPA, has been accepted as EPA s preferred remedial
action.
The proposal combines the following activities:
o Excavation of all onsite contaminated soils, with the exception of
those existing in the Old Pond area, and consolidation of the
soils in the North Landfarm area.
o Stabilization of any free oil, liquid, or sludge found in the
heavily contaminated areas of the Small Old Pond and Old Plant
area (Stabilized waste from the Small Old Pond and Old Plant
area will be consolidated with materials 1n the North Landfarm).
o The contaminated soils consolidated in the North Landfarm would
be graded and covered with RCRA topsoil clay cap.
o Field investigation into the Old Pond area to locate any free
oils, liquids or sludges. Insitue stabilization of these
materials.
o The Old Pond area would be covered with a RCRA topsoil clay cap.
o Installation of a groundwater monitoring system to monitor the
effectiveness of the remedy.
o Backfill, grade and seed (or gravel cover) all excavated areas.
o Remedial action at the CCA Plant (to be proposed by Mid-South
Wood Products of Mena, Inc., but will be as effective, or more,
/. than EPA's recommended action).
o Fencing and deed restrictions.
o Completion of EPA's Alternative No. 6, Groundwater Recovery/
Treatment, with the exception of the inorganics treatment system.
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o Any groundwater found to be contaminated with inorganics
would be treated by the activated carbon system and then used
as makeup water for the CCA treatment process.
As part of this remedy, the potential responsible parties will have to
perform bench studies during the remedial design and provide EPA with
results that support the use of stabilization as part of this remedy. If
stabilization proves ineffective, an alternative approach will be required
for those heavily contaminated materials for which stabilization has been
proposed.
Additionally, since wastes will be left onsite, the remedial action will
be reviewed every five years to assure that the remedy is still protect-
ing public health and the environment.
II. BACKGROUND ON COMMUNITY INVOLVEMENT AND CONCERNS
Site Background
The Mid-South Wood Products site 1s a 57-acre wood treating facility
located in western Arkansas, approximately 0.5 miles southwest of the
City of Mena. The site was operated as a pentachlorophenol (PCP) and
creosote wood treating facility from the late 1930s to 1977, when a
new wood treating facility, using a chromated copper arsenate (CCA)
process, was built adjacent to the old site. The CCA facility is
currently being operated by Mid-South Wood Products of Mena, Inc.
During early operations, waste products from wood treating were stored
1n two old pond areas onsite. In 1978, when the onsite waste ponds
were closed, the pond liquid and sludge materials were pumped onto
adjacent land to the west (landfarm areas) and mixed with the existing
soils. Some of the mixture was placed back in the ponds.
The site has been under Investigation since 1976, when 1t was reported
that Rock Creek and the Mountain Fork River suffered a fish kill
8-1/2 miles downstream. Subsequent to the fish kill, state and federal
agencies began testing for the presence of chemicals in the ground-
water, surface water, and soil. Low levels of PCP, arsenic, and
chromium were found in some groundwater and surface soil samples. In
1982, the site was placed on the National Priorities List (NPL) for
hazardous waste sites remedial action under the U.S. Environmental
Protection Agency Superfund Program.
i
Major Concerns and Issues
City and county officials, agency staff, and local residents Indicate
that concern about the site is for the most part focused 1n the
Immediate vicinity of the site. Concern 1s also primarily related
to economics in the area which would be greatly affected, should the
Mid-South Wood Products facility be shut down. Although Mena and
Hatfleld residents are generally aware of the site, remedial action
is not seen as a community-wide issue in either city.
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12
Most carcinogens do not have a simple concentration promulgated as a
standard. Therefore, EPA must select a cleanup level relative to a
desired excess lifetime cancer risk level. When assessing an appropriate
risk level for a particular site, to serve as the basis for remedial
action, EPA uses 1x10-4 to 1x10-7 as the target range and 1x10-6 as a
point of departure.
In the Feasibility Study Report EPA derived an action level to limit human
exposure to contaminated soils. This derived value is based upon
extrapolations from animal toxicity experiments to human health effects
1n order to estimate a reasonable level of risk for the contaminants
present onsite. The FS Report uses a 1 x 10-6 excess lifetime cancer
risk as Its action level. However, a 1x10-5 risk level can be considered
for use as the cleanup criteria based no the conditions Inherent to the
site.
EPA's Carcinogen Assessment Group has a desired model which 1s used to
calculate excess lifetime cancer risks. EPA acknowledges the fact that
their may be uncertainties inherent in the calculation of these risk
values. These uncertainties may act to either Increase or decrease risk,
depending on the source of the uncertainty. The uncertanties were taken
Into account when the Endangerment Assessment was prepared for the Mid-
South site. In assessing all available information EPA established a
cl-eanup level for the Mid-South site that 1s unlikely to result in a
public health or environmental problems.
8) HINES LUMBER COMPANY
The FS proposes to apply the risk level for BaP'to the aggregate of the 5
carcinogenic PAHs, being, in addition to BaP, benzo(a)anthracene,
benzo(b)fluoranthene, benzo(k)fluoranthene, and chrysene. To date, BaP
is the only carcinogenic PAH for which the toxicological data have been
adequate, In the judgment of EPA, to allow the agency to derive a quantitative
criterion. The quality of scientific data for the remaining four carcinogenic
PAHs has been deemed as inadequate to promulgate official agency criteria.
Nevertheless, there 1s sufficient data to determine that these compounds
are, for the most part, substantially less potent carcinogens than BaP.
For example a recent review by the EPA Environmental Criteria and Assessment
Office showed that benzo(b)fluoranthene was about 10% as potent as BaP,
and chrysene was about 1% as potent. (EPA 1982 Errata: PAH Ambient Water
Quality Criterion for the Protection of Human Health, page 24).
A reasonable approach for the Mid-South site would be to accept the fact
that BaP 1s the most potent of the 5 carcinogenic PAHs, that chrysene 1s
the least potent and to establish a separate cleanup criterion for BaP.
In the particular situation at the Mena site, using a 10-5 risk level,
this would mean 3 ppm for BaP, and 30 ppm for the total of the 5 carcinogenic
PAH.
t
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13
EPA RESPONSE:
EPA acknowledges that benzo(a) pyrene may be the most potent carcinogen
of the PAH family of compounds. However, as indicated in the above comments,
there 1s a lack of promulgated regulations pertaining to the remaining four
carcinogenic PAHs. In light of this fact, the Agency is reluctant to con-
sider your recommendation and is more Inclined to adopt an action level
that assures adequate protection of public health and the environment.
9) HINES LUMBER COMPANY
The estimates of contaminated yardage associated with the various areas
on the Mid-South property are shown 1n numbers that Indicate a far higher
degree of precision and accuracy than 1s warranted. These estimates
should be expressed in round numbers with the likely upper and lower
range. A more reliable estimate will be developed during the preparation
of the remedial action plan and engineering specifications.
EPA RESPONSE:
The Feasibility Study may not present an upper and lower range; however,
the excavation volumes are presented as estimates (e.g.., 80,000 cubic
yards for the Excavation and Offsite Disposal alternative).
10) HINES LUMBER COMPANY
According to the FS, a soil-clay cap is calculated to reduce infiltration
by "over 70 percent" as compared with the present conditions at the site
(FS page 5-17). For a combination of synthetic membrane and soil-clay
cap, the reduction in Infiltration is estimated to be greater than 90
percent (FS page 5-15). Unfortunately, no substantiation 1s provided to
allow a review of these two infiltration estimates. However, 1t 1s clear
that both values are far too low, probably by at least 4 orders of magnitude,
i.e. 10,000. In other words, the reduction 1n Infiltration achieved by a
cap Installed in accordance with the specifications outlined in the FS
(FS page 5-11), over the present situation, 1s almost certainly greater
than 99% under either the synthetic membrane or soil-clay cap option.
There are two major factors responsible for the reduction of Infiltration:
a. The low permeability (10-7 cm/sec) of the final engineered cap as
compared with the present situation, which consists of unconsolidated
native soils with a permeability estimated at between 10-4 and 10-5
cm/sec The engineered cap would thus have a permeability at least 100
times less than the present, situation; and
b. The FS stipulates that the cap must be graded with positive slopes of
between 3 and 5% at the top and less than 20% on the sides. The permeability
values used above refer to a static situation where water would be ponded
on the soil. Under that condition, a 10-7 cm/sec would allow the water
to penetrate the cap at the rate of about one inch per year. However,
because of the positive slopes of the cap, there will be no situation
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14
whereby water could remain ponded on the surface of the cap. The slopes
of the cap are designed to cause all water to promptly run off. It is
conservatively estimated that the fact that the water will not be able to
penetrate the cap at even the one inch per year rate implied by the
static permeability test, will further reduce the potential infiltration
by at least another two orders of magnitude, i.e., 99%.
EPA RESPONSE:
The.Feasibility Study is not a design document. This report was developed
based upon the results of the site investigations and it presents the
development and evaluation of remedial action alternatives that could
be implemented to eliminate or minimize the threat to public health and
the environment. If capping is a part of the remedy selected for the
site, then a more precise infiltration rate will be calculated as part of
the Remedial Design.
11) MINES LUMBER COMPANY
According to the FS, both the engineered soil-clay cap (page 5-17) and
the combination synthetic membrane and soil-clay cap offer similar improvements
over the present situation, i.e. a reduction of infiltration because of
the very low permeability (10-7 cm/sec) of the sloped final cover. The
difference between the two materials in effectively reducing infiltration,
i.e. 70% for the soil-clay compared to 90% for the synthetic liner is not
explained, and, as discussed above does not appear to be justified. In
any case, the clay and the synthetic membrane will achieve a similar
reduction. It is likely that the synthetic membrane will be both more
costly and shorter lived than the clay which is a natural material, less
susceptible to failure and far easier tc repair, should that be required.
EPA RESPONSE:
The 70% and 90% figures were determined by EPA's contractor. These
values were based upon their experience with the actual operation of such
structures as opposed to a theoretical derivation.
The synthetic membrane liner is a proven technology. If adequate operation
and maintenance is provided, then it should provide greater protection
from infiltration than the top-soil clay cap alternative.
12) NINES LUMBER COMPANY
The advantages, 1f any of Alternative 3, Multi-Layer cap over Alternative
2, Topsoil-Clay cap, are not documented in the FS. It is unlikely that a
convincing demonstration can be made of incremental reductions in risk
commensurate with the $1.4 million additional cost for the synthetic
membrane.
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15
13) HINES LUMBER COMPANY
By the same token, the FS does not demonstrate the additional advantages,
if any, of Alternative 6, Combined Excavation/Capping as compared with
Alternative 2, Topsoil-Clay cap. The additional cost would be $2.2 million.
EPA RESPONSE:
The Feasibility Study does in fact compare the alternatives in Chapter 6,
entitled "Comparative Evaluation of Alternatives."
WRITTEN COMMENTS PROVIDED TO EPA DURING THE PUBLIC MEETINGS (MAY 8, 1986)
EPA's response follows each question, comment, or concern raised in each
written statement or group of similar statements.
The major Issues of concern that were raised during the public meeting
and provided in written statements to EPA during the meeting are summa-
rized below:
(1) Alderman, Position 12, Waldron, Arkansas, Mr. Butch Johnston
"Many people in this area are dependent on Mid-South in Mena for
their jobs ... When considering alternatives to the problem at the
Old Mid-South location please don't jeopardize the jobs currently
provided..."
(2) Resident of Waldron, Arkansas, Ms. Regina Oliver
"When considering a solution for the cleanup at the old Mid-South,
please help keep the current Mid-South facility in operation".
(3) Resident of Waldron, Arkansas, Ms. Sherry Johnston
"... any solution that Inhibits the operations at the current Mid-
south location would create a long reaching economical problem in
this area".
(4) Resident of Waldron, Arkansas, Mr. L. J. Watkins
"... your consideration of a remedial altaernative that will allow
the continued day-to-day operation of Mid-South Wood Products, Inc.
and that will minimize its economic and financial Impact upon all of
as involved is expected and will be greatly appreciated".
(5) President and Chief Executive Officer, First National Bank, Mena,
Arkansas , Mr. Bert Hensley
"In considering an alternative to this problem, I would hope that
you could find a remedy which would not affect the normal business of
•the company or the employee job secruity. A change would tremendously
affect our community and its economy."
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16
(6) Written statement signed by approximately 346 residents provided
by Mr. Phillip Clay, attorney for Mid-South Wood Products, Inc.
M
Please consider when choosing a remedial alternative, to this
problem, a solution that will not interrupt the normal business of
Mid-South so that jobs will not be temporarily or permanently lost."
EPA RESPONSE:
It Is not the intent of EPA to close the current facility. What
we are interested in is taking remedial action primarily in the
Inactive areas which exist around the present treatment facility.
There are two potentially responsible parties, Mid-South Wood
Products, Inc. and Edward Hines Lumber Co., who share potential
liability and cost of any such cleanups.
With respect to the active facility, there are certain remedial
measures which must be taken to address the problem of storm water
runoff. We believe that there are contaminants migrating from the
current facility and contributing to an existing groundwater
contamination and surface water runoff problem.
(7) Resident of Mena, Mr. David Stewman
"I own four acres bordered on three sites by Mid-South and I have
never been contacted by the EPA. Why?"
"My property has a well about 75 feet from Mid-South property. Has
it been tested? If not why?"
"If work 1s done on Mid-South property by the EPA or their con-
tractor(s) will the EPA be responsible 1f my property 1s adversely
affected? If not why?"
"Does the EPA have the name(s) af anyone who has been harmed by the
Edward Hines Lumber Co. or Mid-South operation?"
EPA RESPONSE:
0 Mr. Stewman was never contacted because there was never a need to
contact him. The Mid-South site does not pose as a threat of contam-
ination to Mr. Stewman's property since it 1s located to the northeast
or upgradient of areas of contamination found during the site Invest-
igation.
0 No, Mr. Stewman's property has never been sampled. Sampling was done
onslte that Indicates no contamination in areas adjacent to his property,
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17
w
0 Yes, EPA 1s responsible for work done by its contractors. Also, the
Potential Responsible Parties are responsible for work performed by
their contractors.
0 EPA has no names of individuals who have been harmed by the site other
than the problems associated with those properties to the northwest of
the site which were eventually provided with alternate water supplies.
(See page 2 of the Responsiveness Summary)
CONCERNS RAISED DURING THE PUBLIC MEETING (MAY 8, 1986)
The major issues of concern that were raised during the public meeting
are summarized below:
0 Will the Mid-South facility be closed as a result of this action?
0 The people are not against cleaning up the environment; however, they
are worried about losing the jobs provided by Mid-South, and the potential
economic impacts on the City of Mena and Mr. Jim Huff (President of Mid-
South).
0 Who will pay for the remedy?
0 How will the cleanup affect the surrounding property?
0 What has the study cost?
0 Why is Mid-South responsible for something ft had nothing to do with?
0 What happens after the public meeting?
EPA RESPONSE (presented in the same order as indicated above):
0 It 1s not the intent of EPA to put Mid-South out of business. It is
our intent, however, to take those actions deemed necessary to protect
public health and the environment.
0 The apportionment of cost for any remedy that may be selected for the
site will have to be worked out between the two Potential Responsible
Parties, Mid-South Wood Products, Inc., and Mines Lumber Company.
0 Any remedial alternative that is selected, with the exception of the No
Action Alternative, will include the excavation of contaminated soils
located to the southwest of the site in an Isolated, non residential,
area. During any remedial activities sufficient measures will be taken
to insure that there is no negative impact on adjoining properties.
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The level of concern about the site was higher in the 1970s than it is
today. However, there is still concern about the groundwater and harmful
dust. As stated previously, however, the biggest concern is economics in
the area.
Activities to Elicit Input and Address Concerns
The Arkansas Department of Pollution Control and Ecology (ADPC4E) is the
lead state agency for hazardous waste issues in Arkansas. The ADPC&E
became involved at the site 1n 1976 during its Investigation of the fish
kill in Mountain Fork. ADPC&E was again involved in 1978. The ADPC&E
established requirements to be met, including dismantling of an illegal
valve used for discharging holding pond liquids into a tributary of Rock
Creek and development of a "closed system" for waste management. Between
1978 and 1984, the ADPC&E conducted a series of onsite inspections,
tested soil and water samples, and worked with the USEPA and site owners
in identifying addditional investigative activities to be conducted.
Subsequent to each of the formal studies conducted by the EPA, the Remedial
Investigation and the Feasibility Study, copies of the documents outlining
these studies were placed in strategically located repositories for
review and comments from the public. A public comment period was held at
the end of the Feasibility Study, from April 28, 1986, through May 19,
1986. During this public comment period, a public meeting was held on
May 8, 1986, to explain results of the Feasibility Study and to hear
comments on the remedial alternatives.
III. SUMMARY OF PUBLIC COMMENTS RECEIVED DURING PUBLIC COMMENT PERIOD
AND AGENCY RESPONSES
CONCERNS RAISED DURING THE PUBLIC COMMENT PERIOD
(April 28 - May 19, 1986)
The following summarizes the major issues raised in written statements
provided to EPA during the public comment period.
EPA's response follows each comment or group of similar comments.
1) HINES LUMBER COMPANY
It 1s most Important that all discussion and diagramatic representations
that pertain to the present configuration and alignment of the site
boundaries be checked to ensure that they accurately reflect the property
acquired by the Edward Hines Lumber Company ("Hines"). For example,
figure 1-2 gives the false impression that Pope Pond and Moon Springs
are offsite locations, whereas they are both within the present boundaries
of the site.
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EPA RESPONSE:
EPA acknowledges the comment and will make every effort to represent the
site in its present configuration and alignment of property boundaries in
any future EPA documents.
2) HINES LUMBER COMPANY
Since Hines took title to the former Pope and Moon properties, no
location has been identified where there is contamination that has been
transported via the groundwater route. Neither the Remedial Investigation
(RI) nor the sampling by B & F Engineering, consultants for Hines, has
detected any groundwater contamination beyond Moon Spring, a location
which 1s on property owned and controlled by the Potentially Responsible
Parties (PRPs). The only location beyond the present property boundaries
where some contamination has been detected 1s a small area near the
railroad tracks to the southwest of the site. That contamination was
transported by a surface flow as the result of an Inadvertent release
from the former pond (RI page 8.0-8). That pond, along with all other
former impoundments has since been closed.
EPA RESPONSE:
At the request of Mr. Pope, ADPC&E obtained water samples 1n November,
1980, from the Pope's well and sediment samples from near Pope Pond. The
results of these test were reported as:
Results of Analyses*
Soil
Water Water Soil Soil Drainage
Kitchen Pump West of Pope from
Faucet House Mid-South Pond Mid-South
PCP 0.036 ppb 0.063 ppb 118 ppb 232 ppb 1335 ppm
Arsenic 14 ppb < 5 ppb 1086 ppb 115 ppb
Chromium 8 ppb < 5 ppb 60 ppb 46 ppb
* ppb - parts per billion; ppm - parts per million
Subsequent to receiving these results, the Popes connected to City of
Mena water system.
In February, 1981, the U.S. EPA sent a two-man team to the site. Water
samples were taken by the team from the Pope, Hilton, McMellon, and
Melrose wells (Figure 2.2-2). With the exception of the Hilton well
which had a PCP concentration of 10 ppb, chrome, arsenic, and PCP were
not detected. About the same time, the Arkansas Health Department obtained
water samples from Pope Pond, Moon Spring (west of the Pope property) and
Frost, Hilton, and Melrose wells. The results of analysis on these
water samples are:
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Moon Frost Hilton Mel rose
Spring Well Well Well
PCP 47 ppb 1,400 ppb Trace Trace Trace
Arsenic 37 ppb 5 ppb < 5 ppb < 5 ppb < 5 ppb
Chromium 85 ppb < 5 ppb < 5 ppb < 5 ppb < 5 ppb
In 1984 several private wells along Hghway 375 were sampled by EPA;
however no groundwater contamination was found (RI, page 2.0-6).
Regardless of the comments made by Hines there 1s a significant ground-
water contamination problem onsite. Furthermore, field Investigations
referenced above do Indicate that groundwater contamination has been
found beyond Moon Spring. In light of this fact, EPA developed a ground-
water remediation strategy which is addressed, as proposed by alternative
7, in the Feasibility Study Report.
In reference to the statement concerning contamination found offsite
along the railroad tracks to the southwest of the site. The Remedial
Investigation Report identifies groundwater and surface water routes to
the southwest from the highly contaminated areas onsite. Therefore, the
past release may not be the sole contributor to contamination in this area.
3) HINES LUMBER COMPANY
The Feasibility Study ("FS") should give more recognition to the crucial
fact that the hydrogeology at the site makes 1t highly unlikely that
contaminants could migrate off the site via the groundwater. The FS
confirms that M. . . the soils onsite have low hydraulic conductivities
and limited capacities to transmit water." (FS page 1-12 and RI page
8.0-11). With the purchase of adjoining downgradient properties by
Hines, the sole identified groundwater pathway, represented by the fault/
fracture zone, has been contained totally onsite. Any groundwater in the
fracture zone 1s now recovered and treated by an engineered system that
has been operating since October 1985. Furthermore, as mentioned in the
FS, voluntary action by Hines "... has effectively removed all known
downgradient groundwater usage ..." (FS page 115).
EPA RESPONSE:
The statement "... the soils onsite have low hydraulic conductivities and
limited capacities to transmit water" 1s a correct statement; however,
the surface soils should not be used to describe the potential for ground
water migration at the Mid-South site. The Remedial Investigation Indicates
"The residual soils in the valley area are up to 6 feet thick and average
2 to 3 feet thick in most areas" (RI, page 5.0-11); however, the primary water
bearing zone 1s found at a depth of 10 - 30 feet beneath the surface in
the fractured rock regime (RI, page 7.0-16). The primary impact of surface
soil on groundwater flow is with respect to recharge of the water bearing
zone.
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8
Furthermore, the groundwater migration pathway along the fault/fracture
zone is not the "sole" groundwater pathway as indicated in the Hines comment
EPA found potential groundwater migration pathways to exist to the south
- southwest along the railroad tracks and to the east from the CCA plant.
4) HINES LUMBER COMPANY
The statement "the proposed float or liquid level controlled pump switches
are not being used and the liquid levels in the trenches are not being
kept below the lateral collector pipe inverts" (FS page 3-22) is not
correct. Also, the oils & sludges are removed from the wells.
The statement "free oils and sludge from the existing french drains were
found to quickly clog the activated carbon system during the demonstration
project" is not correct. There was a problem with silt from the wells
clogging the cloth filter ahead of the activated carbon system during the
first few weeks of operation. A second filter has been added in parallel
and this is no longer a problem.
EPA RESPONSE:
The statement made in the Feasibility Study Report is based upon an
inspection of the existing groundwater recovery system which was conducted
in November 1985. At the time of the inspection the groundwater recovery
system was not operating correctly.
5) HINES LUMBER COMPANY
Concentrations of heavy metals in the native soils of the Caddo Basin,
Ouachita Mountain region, in the general vicinity of Mena, have been
inadequately characterized in the RI. As a consequence neither the
Endangerment Assessment ("EA") nor the FS give sufficient attention to
the fact that relatively high concentrations of chromium (Cr) and arsenic
(As) are present in the native soils around the Mid-South site. The RI
report documented the fact that Cr levels as high as 18.4 ppm and 19.4
ppm, and As levels of up to 5.6 ppm were measured in the background
samples collected 3 inches beneath the surface (RI page 7.0-22). However,
the EA and FS derive a median value for Cr of 11.4 ppm and for As, 3 ppm
(FS table 2-1 and page 3-10).
The use of median or average values to represent background (uncontaminated)
levels, and certainly their extrapolation into target levels for cleanup,
1s Inappropriate. As 1s evident from the limited data, natural background
levels for these metals considerably exceed the median values. Furthermore,
total metal concentrations should be considered only for the hazard
associated with the ingestion of wind-blown dusts, I.e. surface soils
(whereas background samples were collected 3 Inches below the surface).
For considering the potential risk to groundwater off the property, the
relevant unit of measure should be the concentration of Teachable Cr and
As, as determined by the EPA stipulated EP toxicity test.
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Figures 2-1 and 2-2 which show As and Cr levels in the soil are
seriously misleading for several reasons:
a. they are based on the use of median values for background
concentrations in the native soils and do not take into account the
variation in these naturally-occurring concentrations; and
b. they are based on samples collected at depths on the site
that were different from the depths used offsite.
For the above reasons, only the areas of higher concentrations than
background should be considered as posing an incremental risk, and therefore
as candidate areas for remedial action. Concentrations of As and Cr that
fall within the range of natural background should not be considered as
posing a significant additional risk to human health or the environment.
EPA RESPONSE:
The use of an average background concentration for arsenic and chromium
for cleanup criteria may be inappropriate due to the small number of
background samples collected and the wide range of results. Therefore,
EPA will consider using an action level of any concentration above the
range of background concentrations found during the remedial investigation
(I.e., arsenic > 5.6 ppm and chromium > 19.4 ppm ).
Regarding soil collection procedures, surface-soil samples are collected
by extracting soil from the 0-3 inch depth, not at a depth of 3 inches
beneath, the surface of the siol, as indicated in your comment.
In response to the comment suggesting that the EP Toxicity procedure
be used for "considering the potential risk to groundwater...", the
EP Toxicity procedure was not developed to aid in the development of
cleanup standards. This is an extraction procedure which is used to
characterize wastes (with the understanding that any waste material
that does not exhibit the characteristic 1s not necesarily non-hazardous.
Based upon a comparison of the areal distribution of soils contaminated
with arsenic to those contaminated with total PAHs at a concentration
greater than 300 ppb (soil cleanup criteria described 1n the FS Report)
the above recommendation would not significantly affect the total surface
area which would require excavation under any given remedial alternative.
Furthermore, preliminary calculations Indicate that Increasing the cleanup
criteria for arsenic to 5.6 ppm would not significantly affect the amount
of soil requiring excavation.
6) NINES LUMBER COMPANY.
The FS report states that "... organic carcinogens [PAH group] are not
present in natural soils, therefore the 10-6 Increased cancer risk level
will be applied to the carcinogenic PAH's." (page 3-10).
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10
The premise that the carcinogenic Polynuclear Aromatic Hyrdocarbons
(PAHs) do not occur in natural soils is not correct. In fact, the situation
is exactly the opposite, as has been thoroughly documented. For example,
a recent EPA report has the following introduction with regard to benzo(a)
pyrene (BaP), the most potent carcinogenic member of the PAH family of
compounds:
"The ubiquitous presence of BaP in the environment has been docu-
mented in U.S. EPA (1980)... Human exposure occurs primarily
through ingestion of food, followed by inhalation and the consump-
tion of water. From the data presently available, it should be
assumed that a large prtion, if not all, of the human population
will be exposed to BaP in their daily activities."
(U.S. EPA 1982. Errata: PAH Ambient Water Quality Criterion for the
Protection of Human Health.) PAHs are products of combustion, and are
therefore present in the environment as a result of vehicle emissions,
agricultural burning, forest fires, wood stove smoke, cigarette smoke,
to mention just a few sources. PAHs identical to those found in creosote,
are also common in asphalt used for highway paving, roofing tars, tire
rubber, and municipal sewage sludge and effluent from treatment plants.
Because the PAHs are typically released in the form of particulate
matter 1n the atmosphere, and because they absorb very effectively to
soil, they will tend to be found in the upper layers of surface soils.
One reason that these PAHs were not detected in the few background soil
samples that were analyzed may lie in the fact that the samples were
collected under the top 3 Inches, whereas the PAHs would tend to concentrate
at or near the surface of the soil. In fact, according to the EA (page
218), significantly higher levels of BaP were found offsite than onsite,
namely up to 1,700 ppb as compared to only trace. The level confirmed by
this one PAH compound offsite is 600% higher than the cleanup criterion
proposed in the FS for the combined total of 5 PAHs.
EPA RESPONSE:
The statement in the Feasibility Study "... organic carcinogens (PAH
group) are not present in natural soil." 1s a correct statement in the
context 1n which 1t 1s presented. The Feasibility Study does not Infer
that PAHs do not or may not occur naturally in the environment. What it
does Indicate 1s that background samples were collected and analyzed and
no PAHs were found in these samples. Furthermore, as Indicated in the
above comment by Hines, the Endangerment Assessment does reference an
offsite location wherje benzo (a) pyrene (the most potent carcinogen
member of the PAH family) was found at a level of 1700 ppb which 1s, as
stated above, 600% higher than the cleanup criterion proposed in the
Feasibility Study for total PAHs. However, it should also be pointed
out that the location of this extremely high level of contamination was
1n the area offsite, to the southwest of the site, which is considered
contaminated and is thought to receive surface and ground water drainage
from the site. Additionally, the soil sample (representative of the
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1,700 ppb benzo(a)pyrene) was collected at a depth of 1.3 feet below the
surface; therefore, any inference that the presence of benzo(a)pyrene is
naturally occuring, based upon comments presented by Hines, would be
difficult to substantiate. This area is considered contaminated and is
included 1n all remedial alternatives outlined in the Feasibility Study.
7) HINES LUMBER COMPANY
The risk level that is proposed in the FS for the carcinogenic PAHs,
namely 1x10-6 is excessively conservative for the particular situation
encountered at the Mena site and a 1x10-5 risk level would be more
reasonable based on the facts documented in the EA report, in particular:
a. There 1s essentially no risk to the community from potential exposure
to contaminated drinking water, because the town and all of the proximate
downgradient dwellings are served by a municipal utility system that
draws on a surface reservoir upstream of the site. The EA states "...
there are no nearby domestic groundwater users", (page 3-6);
b. The principal risk pathway .Identified in the EA 1s exposure to windblown
dust, however, despite the fact that far higher levels of BaP, the most
potent carcinogen, were found offsite as compared to onsite (EA page
2-18) no evaluation was made of the background risk associated with BaP
and similar PAH compounds; and
c. The assumption made in the EA that 100% of the contaminant present on
the soil would be biologically available and the estimated rate of ingestion
by humans, are extremely conservative (EA page 5-25).
In a recently proposed regulation on the subject of the appropriate risk
level at a particular site that should serve as the basis for a remedial
action, EPA outlined a framework for determining the level of risk to
be permitted post cleanup. (U.S. EPA Hazardous Waste Management System;
Land Disposal Restrictions; Proposed Rule. Federal Register, January 14,
1986, pages 1602-1766. Refer to page 1635.)
Applying the procedure proposed by EPA in conjunction with the site-specific
conditions prevailing at the Mid-South site and the facts described in
the EA, it seems reasonable to base the cleanup criteria for the protection
of human health in Mena on a 1x10-5 risk level.
EPA RESPONSE:
The Endangerment Assessment was designed to address two scenarios, Indus-
trial and residential,' The Industrial scenario essentially leaves the
site in Its current state and workers are exposed to contaminated
surface waters and surface soils through Ingestion, Inhalation of dusts,
or dermal contact with soil or water on a dally basis. The other scenario
1s represented as a "worst case" scenario and it assumes that the site 1s
developed for residential use and residents would be exposed through
ingestion of groundwater, surface soils, subsurface soils or sediments,
or by dermal contact with groundwater, surface water, surface soils or
sediments.
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