NCD980602163_19790111_Warren County PCB Landfill_SERB C_Questions About PCBs-OCR

JAMES B. HUNT, JR.
GOVERNOR
STATE OF NOrtTH CAROLINA
DEPARTMENT OF HUM,~N RESOURCES
Division of llealth Services
HUGH H. TIL·SON, M.D.
DIRECTOR
SARA!: T. MORROW, M.D., M.P.H.
SECRETARY P. 0 . Box 2091 Raleigh 27602
January 11, 1979
~-lEMO RAN DUM
10: Mr. Herbert Hyde
Secretary
N. C. Department o f Cr ime Control
and Public Safety
Archdale Building
Tl:IROUGH: Marshall Staton, Chief
Sanitary Engineering Section
FROM: Jerry C. Perkins, !1ead
Solid Waste & Vector Control Branch
Sanitary Engineering Section
SUBJECT: Questions about PCB
Question No. 5 --Did we fully explore the possibility of burying the PCB' s on
State-owned land?
Yes. Every parcel of land offered by the State Property Officer
as being a possible candidate as a site to receive soil contam-
inated with PCB was investigated. These included properties
assigned to the National Guard, institution~tower sites, Prison
property, experimental farms, State Parks, State Forest, utility-
owned property, and properties belonging to the Department of
Transportation.
Question No. 6 --Did we fully explore the possibility of burying the PCB's on
Federally-owned land (such as Fort Bragg or Butner)?
Fort Bragg was considered but due to its extremely permeable soils,
referre d to as dune type soils, was not deemed a suitable solution
for the State problem. Butner is State-owned property and its
property was investigated as a possible candidate. Its properties
border the proposed extension of the Raleigh water supply project
and was not viewed as a favorable candidate for detailed invest-
igation.
Memo: Mr. Herbert Hyde
Page 2
January 11, 1979
Question No. 7 --What soil was used to determine permeability?
Surface soils on the proposed site were tested from a depth of
5 inches to 6 feet below ground level. A 5-foot layer of soils
was pro~0sed as a liner; therefore, a 5\-foot soil layer was
tested for permeability. The layer meets the permeability criteria
and enough materials are present to construct a 5-foot liner.
The sampling procedures are described
addition t o the application ,
and certified in an
Question No. 8 --How many acres do we really have to have to bury the PCB's?
Sixteen to twenty usable acres depending on the specific site .
This acreage includes the basic working area plus additional
acreage for buffer zones, monitor wells , stockpile areas, holding
ponds~ run-off control devices, fencing, immediate site access,
and other acreage required to efficiently and safely dispose of
the contaminated soil. This acreage does not include deeded
right-of-way ·which would be required from a State maintained
road to the specific disposal site.
Question No. 9 --What if water found on Warren County site --what will State do?
Water table data was established by utilization of the subsurface
borings and by consideration of information furnished by the U.S.
Geological Survey. As indicated in the application, the soil
contaminated with PCB is proposed to be disposed of at an elevation
which is no closer than 13 feet to the historical high water table.
Question No. 10 -Why was Warren County chosen? Does the Governor want to push it
further down?
Of the si.tes investigated, the site in Warren County is the best
available considering its soil, water, other geological features,
location, and access.
Question No. 14 -Why is the State asking waivers from EPA; that is, why not find
a site where waivers won't be necessary?
Of the approximately 90 sites in 20 counties investigated, this
site would require less waivers than any of the other site s
investigated.
Memo: Mr. Herbert Hyde
Page 3
January 11, 1979
Question No. 17 -What other sites in North Carolina have been considered?
Approximately 90 sites in 20 counties located on both public
and private land were investigated. Most of the sites were
elimin~ted due to the location being within a public supply
watershed, private water supply well too near, soil conditions,
rocky terrain, and access problems. Eleven sites were drilled
to establish soil conditions, water table, etc. After all sub-
surface data had been evaluated, 5 of the 11 sites drilled were
given further consideration.
Question No. 21 -Why is the State seeking a waiver of the artificial liner
requirement?
The following statement from the application answers this
question:
The State of North Carolina does not feel that the lack of an
artificial liner will present an unreasonable risk of injury
to health or the environment from PCB's for the following reasons:
... This landfill is not a commercial facility which will be in
operation for a long period of time. It is a one-shot
(90 days open) operation for a special problem. (Soil with
low concentration of PCB generally expected to be less than
500 ppm based on test dig, see attachment.)
The 5-foot compacted clay liner exceeds the requirement
found in 761.41 (b) (1) (i), EPA-Part V-PCB Disposal and
Marking.
There will be a 10 mil plastic liner placed on top of the
landfill. This "umbrella" top will be covered by two feet
of soil which will support the growth of grasses. The grass,
the 2 percent slope, drainage ditches, and the top liner will
effectively prevent any rainwater infiltration into the landfill.
Question No. 22 -Why is the State seeking a waiver of the requirement for a 50-foot
se~aration between the site and the groundwater?
The State of North Carolina does not feel that the request for
waiving the 50-foot separa tion between the site and the ground
water will present an unreasonable risk to hea lth or the environ-
ment from the soil contaminated wi th PCB f or the same reasons
stated for the liner waiver.
Memo: Mr. Herbert Hyde
Page 4
January 11, 1979
Question No. 23 -Why is the State seeking a waiver of the requirement for the
leachate collection system under the liner?
On the advice of EPA, the leachate collection system was placed
above the soil liner to prevent the occurrence of a leachate
head and to be able to detect sooner any leachate movement from
the waste conglomerate .
''uestion No. 24 -EPA requirements state that the "site must not be subject to
flooding, nor have hydraulic connection with surface water."
The proposed site is located near the fork of° Richneck Creek
and Fishing Creek. Both of these are special flood hazard
areas. What about that?
Refer to the attached letter dated November 29, 1978, from
the United States Department of the Interior, Geological Survey.
Q11estion No. 26 -(Dr. Mulchi) EPA regulations, while not specific, suggest that
a disposal area should have a thick clay layer. My observations
show the maximum concentration of clay be within 24 inches of the
surface. The figure on page 13 of the N.C. Proposal suggests a
clay layer of perhaps 10 feet in thickness at the site. It is
my judgment that the data given in the proposal on 1A-8A samples
which represent depths from 1-10 feet are more representative of
the upper 2 feet rather than for the entire 10 feet. The soils
should have been sampled at 6-inch intervals for the initial
10 feet rather than bulk sampled to such depths. In fact, the
data for the 1A-8A samples appear to represent only the initial
6 to 12 inches_ of the upper portions of the profile.
How do we respond to that allegation?
REFERENCE TO THICK CLAY LAYER
The EPA regulations are very specific on soil technical requi re-
ments. Regulations require one of two equivalent site locati ons.
One alternative is to locate the site in thick relatively imper-
meable formations such as large-area clay pans.. The equivalent
alternative is to locate the site in soils with high average clay
and silt (fine soil materials) content, with specific engineering
characteristics. There is no specification for thickness of clay
layers in either alternative.
North Carolina does not have large-area clay pan formations but
does have equivalent alternative soils. The proposed site is
located in these type soils. These soils are representative of
thick, relatively impermeable, high clay and silt formations
found in North Carolina. These soils exceed the minimum require-
ments for engineering characteristics.
Memo: Mr. Herbert Hyde
Page 5
January 11, 1979
Question No. 26 (Continued)
REFERENCE TO FIGURE ON PAGE 13 OF THE PROPOSAL
The figure on Page 13 of the proposal is a general cross-section
of the site and is not intended to be an absolute representation
of the site. The intent of Figure 13 is to indicate relative
depth and sequence of soil materials, topography, geology, and
hydrology.
Soil boring (1A-8A) data established that a layer approximately
0 to 10 feet below the surface is classified as clayey materials
by standardized engineering testing procedures. (The soil materials
are classified as A-7, and A-7 materials represent the most clayey
classification under standardized analysis procedures by the
American Association of State Highway Officials (AASHO) classifi-
cation system.
REFERENCE TO MAXIMUM CLAY CONTENT
Tpe EPA regulations do not specify any criteria for maximum clay
concentration. Regulations require a high average clay and silt
content.
Examples: Maximum concentration of clay versus avera~e clay content
(1) A soil may have a maximum clay concentration of 5 percent.
This is a low average amount of clay but is still a maximum
clay concentration. This soil would not meet EPA regulations
since it may have a max i mum clay concentration but lo.w average
clay and silt content.
(2) A soil may have a thin clay layer of 100 percent clay sand-
wiched between deep sand layers. Although the maximum clay
concentration is 100 percent clay, when the total soil is
evaluated, .it will have a low average clay content. This
soil would not meet the requirements for high clay and silt
content.
The average clay and silt content is the more adequate
criteria for soil evaluation.
Soils on the proposed site exceed the minimum required
average clay and silt content.
REFERENCE TO LOCATION OF MAXIMUM CLAY CONCENTRATION LAYER
1 · · 1 d · unoei;l 1 · · 11 Maximum cay concentration is ocate in,soi ayers in essentia y
all soils.
Memo: Mr. Herbert Hyde
Page 6
January 11, 1979
Question No. 26 (Continued)
.JUDGMENT ON DATA PRESENTED
The data from the soil borings is a result of extensive testi ng
procedu1~s established by the Ame r ican Society for Testing
Materials (ASTM) and the American Assoc i ation of State Hi ghway
Off icials (AASHQ). These tests are standardized val i d engineeri ng
procedures and are basi c to the entire field of soils engineering.
[The suggestions t hat the data from samples lA to 8A are repr e-
sentative of any soil materials ot her than presented in the
application is invalid (and unresp onsibl e) with respect to verified
and certified engineering interpretations.]
REFERENCE TO 6-INCH SAMPLING INCREMENTS
It is sugges ted t hat 6-inch sampling invervals would be more
appropriate t han collecting repres~ntat i ve material from a l aye r
sampling interval . Sma l l sampling invervals may give deta.iled
data; however, the data i s only valid f or that one small samp le
area. If one were to sample at the same depth a few feet away ,
comparison of the result s might indicate signifi cant differences.
By representati ve sampli ng and mixi ng the entire soil layer,
average data is obtained . Average data would mask any small
differences and the data is valid over a larger area than 6-i nch
sampling and analyses intervals.
For example, it was suggested that the maxirrum clay concentrat ion
i s on the upper 2 feet . When a mixed r epresentative sample i s
taken from the ~pper 10 f eet, the e ffec t of the clay con tent is
diluted by mixi ng less clayey materials with higher clay materials.
Sampling and t esting hetergenous ma t erial s from a given soil layer
is an accepted engineering procedure and on this specifi c site
provides additional safety f actors.
More detailed sampling was required and performed to test materials
for the impermeable clay l i ner. The upper clayey soil materials
were sampled and t ested on intervals of several feet rather than
6-inch interval s .
Both detailed and sampling procedu res f or average site evaluation
were used on this site.
Question No. 27 -The 1B-8B samples, which represent depths f rom 7 to 30 f ee t , show
sand, silt and clay contents of about 44%, 35%, and 21% respec tively,
which translates into a loam classifica tion . There are very small
amounts of clay present deep within the soils at the site whic h
would serve to trap escapi ng materi als in future years, wi th a
resulting r isk of groundwat er contamina t i on .
How do we respond to that allegation?
Memo: Mr. Herbert Hyde
Page 7
January 11, 1979
Question No. 27 (Continued)
REFERENCE TO TRAPPING OF ESCAPING MATERIALS AND GROUNDWATER
CONTAMINATION
The conceptual design includes detailed engineering procedures to
prev~nt any movement of materials below the clay liner. Monitoring
wells would be installed to detect any PCB movement.
Although soils below the site do increase in silt and sand content,
the materials are still classified as fine materials, are relatively
impermeable, and have a large capacity to t r ap PCB,
Trapping PCB is related (97 percent) to the surface area of soil
materials. There is a large volume of fine material below the
site. [It was suggested that soil chemical processes (cation
exchange capacity) was involved in PCB trapping. This is not a
factor in trapping PCB. Soil physical properties of surface area
and porosity will control trapping PCB, mass flow movement and
movement by diffusion. It is proposed in the design to engineer
soil physical properties in such a manner to totally contain PCB
movement. J
Qu e stion No. 28 -Even an artificial plastic liner might not give the safeguards
necessary for storage of PCB's in soil less than 50% clay, because
it will ultimately deteriorate.
How do we respond to that, especially when we are asking for a
waiver of the liner requirement?
Refer to the answer in Question No. 21. No specifications for
clay content are outlined by EPA regulations. However, the soil
materials do have greater than 65 percent clay and silt. This
amount of fine materials exceed this minimum specified by EPA .
Question No. 29 -The cores drilled at the site did not show groundwater at approx-
imately 40 feet, but this is not proof that the nearest groundwater
will be a safe distance below the rock layers . In fact, the lack
of groundwater on the top of the rock layer is probably evidence
that the rocks are unconsolidated. Such being the case, there may
be natural channels within the rocks which have hydrolic connections
with streams and wells in the region. In such regions, a drill core
may miss groundwater channels very easily. Mr. Paul Pope says it is
difficult to strike water in the region, but he has had success on
severa l occa sions .
How do we answer that?
REFERENCE TO GROUNDWATER AND HYDROLIC CHARACTERISTICS
Water table data was furnished by deep soil borings and investigations
of wells on similar topographical locations. The site has a low
water table and is representative of this area.
{
Memo: Mr. Herbert Hyde
Page 8
January 11, 1979
Question No. 29 (Continued)
Regardless of site geology and hydrology, there will be no
hydrolic connection between the PCB and surface water and no
connection between the PCB and groundwater. Therefore, no
water transport or. contamination can reasonably be expected
to occur.
Movement of groundwater in fractured rock with flow away from
the PCB site was proposed to be r epresentative of site hydro-
geology. Th is would prevent water buildup below the site and
is an asset in t hat it is additional. ·
Question No . 30 -The proposal does not provide for leachate collection beneath
the burial site, but instea.d suggests such a system "within"
the site. Thus;) possible leakage from the site would go unde-
t ected. There is no means to assess the effective~ess of drain
pipes which may be rendered r.onserviceable during backfilling
operations. There are other sites in the U.S. where leakage
from waste chemical sites has been detected, which should serve
as forewarning that "cost cutting" procedures at this site may
endanger the success of making this a "safe site."
How do we answer that?
LEACHATE COLLECTION SYSTEM
The design for the l eachate collection system, placing the system
above rather t han below the clay l iner, i s a sound engineering
practice. If the system is placed above the clay liner, then any
liquid movement can be removed at the c losest point of generation
and at the point of leas t distance of travel. It will also prevent
any water pressure buildup that would tend to push water through the
clay liner.
Wells will be installed. t o monitor any PCB movement below the clay
linero
All precautions will be taken to ensure that the drainage blanket
(sand l ayer) and the drainage pipe for liquid movement will be
installed so that it will be completely serviceable as designed.
The above measures are not cost cutting measures but are based on
sound engineering design, installation, and maintenance.
Memo: Mr. Herbert Hyde
Page 9
January 11, 1979
Question No. 31 -EPA regs require an artificial liner of more than 30 millimeters.
Originally, N.C. officials promised there would be a 30 millimeter
liner above, below and along the outsides of the clay liner. These
premises have disappeared in the formal proposal, and have been
replaced by a 10 millimeter thiclcness top on the PCB residue.
How do we answer that?
Originally the disposal problem was thought to be more severe
than the sampling results from the one-mile test run indicated
and some consideration was given to use of an artificial liner.
The reasons for not considering the artificial liner are explained
in the reply to Question No. 21.
Question No. 33 -Another place to dispose of the PCB I s is Orange County, because
JCP:bm
it contains soils high in 2:1 type clay materials or montmorillonite
clays.
How do we answer that?
It is suggested that areas with clays that exhibit greater chemical
activity _and physical properties than those on the Warren County
site be investigated for PCB disposal. Several sites containing
these clays were investigated and were not as suitable as Warren
County for the following reasons: high population densities,
located in a public supply watershed.
The greater chemical activity of these clays do not increase PCB
trapping. The greater surface area and decreased compacted
permeability would be a desired characteristic for a PCB disposal
site. However, single criteria such as type of clay is not an
appropriate ~riteria for evaluation of a PCB disposal area. In
consideration of all criteria established by EPA, the Warren County
site is the best available site.
cc: Dr. Ronald H. Levine
E
October 19> 1978
HZHO TO: lrr. Robert A. Cart~f
.
Ray E. Kelling, t~boratory Section . .• ., -.
SUBJECT: PCB Results~ Warren County Test Cleunup
Given belm, are the PCB results for the Warreil.. Couuty Test Clea..'1t!p
taken on October 5, 1978. .All results are qu&1titated. on the. I>CS-
· Aroclor 1260.
A
13
C
& D
(1)
170 ~/kg
0.13 ':lg/kg
<lOC -µc,JI·a o •'-o
tfash down
<0.77 µz/1
Special 1
II 2
fl 3
Background 1
II • 2.
(2)
3.8 mg/kg
33 mg/kg
4lµg/l
130 1-1g/kg
77 rug/kg
330 mg/kg
(3)
210 :mg/kg
<J.90 i1gikg
150 1.1g/l
Storctge P lle
(1) 290 mg/kg
{2) 270 mg/kg
(3) 330 'c1g/kg
(l}) 210 mg/kg
(S) 270 mg/kg
<100 itg/kg
<~$1' 11p;/kg
(l1)
41 mg/kg
<J.00 11g/kg
75 }.tg/1
(5)
10 r .. g/kf',
0.25 rng/kr,
<100 pg/kg
127 }?g/1
United States Departn1ent of the Interior
GEOLOGIC:.\L SUZ \TY
P.O. Box 2857
Raleigh, NC 27602
Attachrr.en t 2
November 29, 1978
Mr. Jerry C. Perkins, Head
Solid Waste and Vector Control Branc.h
Division of Health Services
N. C. Department of l:lum,:m Resources
P.O. Box 27687
Raleigh, North Carolina 27611
Dear Mr. Perkins:
The proposed PCB disposal site located in Warren County at latitude
36°?0'13", longitnde 78°09'58", is above the 100-year flood level.
The site is located on a hilltop between Richneck Creek and one of Hs
tributaries. J estimate, based on flood records collected at North
Carolina streams, that the 100-year flood height is not more than 8 feet
above average water level in these creeks . The proposed site is
approximately 80 feet above these creeks and not subject to flooding.
Sincerely yours,
-4'1---N. H. Jackson, Jr.
/ Hydrologist
filIJ:ceh