NCD980602163_19781227_Warren County PCB Landfill_SERB C_Review of Proposal to Use Afton Community Soils-OCR

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A REVIEW OF THE PROPOSAL TO USE
SOILS IN THE AFTON COMMUNITY OF
WARREN COUNTY, N.C. AS A DISPOSAL
SITE FOR SOILS CONTAMINATED WITH PCB
BY
Charles L. Mulchi, Ph.D.
Consultant on Environmental Issues
6223 85th Pl ace
New Carrollton, Md.
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FORWARD
On Dec. 27, 1978, I was asked by a Warren County Citizens Cormiittee
to examine the soils and general terrain at a site in the Afton community
of Warren County, N.C. which the State of North Carolina had selected as
a disposal site.for PCB contaminated soils. I was also asked to review
the proposal submitted by the State of North Carolina to the U.S. Environ-
mental Protection Agency concerning the disposal of soils containing PCB
at the Warren County site.
General Soils Information
The soils ln the region are predominately mapped as Cecil and Lloyd
series with the specific site being mapped .as a severely eroded Lloyd.
Due to the extent of the erosion of the soils at the site, most of the
remaining surface materials consist of 11B11 horizon materials. The 11B11
horizon is the zone of maximum clay concentration. The general color of
the surface material was reddish brown with the site appearing near the
crest of a h·ill-with slopes averaging 2 to 6 percent.
The surface layer averaged 5 to 12 inches in thickness and primarily
consisted of subsoil materials. The surface layer would be classified as
a clay loam with moderate subangularblockystructure. The moist soil ex-
hibited a firm consistancy but plastic when wet.
From 12 to 24 inches below the surface, the soil colors became more
reddish. The soil structure was subangular blocky. The soil became less
plastic when moist. There were no evidence of mottles. Some distinct
bands of micas began to appear.
From 24 to 60 inches below the surface, the soils became progressively
lower in clay contents with textures more characteristic of loams. The
subangular blocky structure became less firm and crushed easily between
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the fingers. The soil in the zone 30 to 60 inches below the surface ex-
hibited features of "rotten rock" with distinct bands of micas. This
would indicate that the parent materials were probably gniesses or schist. l,
The colors were reddish ye11ow with a noted absence of mottles. These
materials were very friable when moist, non sticky and nonpJastic when wet.
From the borings at the site, the parent materials or 11C11 horizon materi-
als appeared to change very 1itt1e with depth with the depth of the
regoJith being some forty feet. There was no evidence of ground-water
within the borings at depths up to forty feet. There were zones of moist
soils within the profile but these were most probably due to percolating
waters from recent rains. -
The drainage properties can best be assessed as we11 drained. This
statement is based on the fact that bright red colors -resulting from
the oxidation of iron materials forming iron oxides -were most conmon.
Also, the genera) absence of mottles and the lack of extensive amounts
of free water -a11 combined to qualify the soil as we11 drained. The
disintegrated schist and gnjesse parent materials in the lower portions
of the profile may be classed as excessively well drained due to the
higher sand and lower clay contents.
The clays in the soi) at the proposed chemical disposal site are
mainly confined to the upper 24 inches of the profile. The most conmon
clay type present appears to be kaolinite. This particular type of clay
has a 1:1 type crystal lattice formed from layers of silica and alumina
bonded together by oxygen bonds. The lattice is normally fixed thus a
small amount of expansion occurs between the units when the clay is
wett~d. Water and cations generally do not enter between the structural
units thus the effective surface of the kaolinite is restricted to its
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outer faces. The lack of expansion properties of kaolinite clay is a major
factor for its low capacity for adsorption of cations and its moderate to
excellent permeability to percolating water.
The primary vegetation at the site is soybeans mixed with weeds and
grasses. There is limited forest cover on the surrounding areas. The forest
vegetation in the region is primarily pines, oaks, hickory and gums. There
are two dry waterways bordering the proposed disposal site. No evidence of
springs or related underground waterways were found at the site. The nearest
stream (Richneck Creek) borders the proposed site property and was estimated
to be 800 to 1000 feet from the disposal site. The disposal site slopes
toward the two dry drainage ways which slope toward Richneck Creek. Rich-
neck Creek flows -in an eastward direction through the region and joins
Fishing Creek, the largest stream in the region, approximately 1.5 miles
from the proposed disposal site.
General Comments on the Proposal to Use the
Afton CO!Mlunity Site for the Disposal of PCB Contaminated Soils
There appears to be ·several points of concern --in regards to the pro-
posed usage of the Afton community site as a disposal site for waste
chemicals in general and in particular, the disposal of PCB contaminated
soil by means of burial.
1. Depth and Type of Clay. Although the EPA regulations (Title 40 -
Protection of the Environment, FRL 838-5, Chapter 1, part 761, Annex
II, 761·41) are not specific in regards to the depth of clay necessary
for soil deposition of PCB materials, the references to "thick, rela-
tively impermeable formations such as large area clay pans" do sug-
,..J!est the area should have a thick clay layer. As already discussed,
my observations show the maximum concentration of clay to
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be within 24 inches of the surface. The figure on page 13 of the
N.C. proposal suggest a clay layer of perhaps 10 feet in thickness • ~ at the site. If one examines the data provided in the laboratory
section of the proposal and average the results for the eight cores,
the 1A-8A samples, which represent depths from 0 -10 feet, suqqest
the sand, s i 1 t and clay contents in the upper 10 feet to be 26%, 26%
and 48%, respectively. It would be :,; iy d_P_@rof..el t■ th a t these results
were more representative of the upper 2 feet rather than for the
entire 10 feet. For this type of work and interpretations, 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.
The 1 B-8B samp 1 es,. which represent depths from 7 to 30 feet, show
sand, silt and clay contents of about 44%, 35% and 21%, respectively,
which translates into a loam classification. The samples listed as
(C) samples show higher sand and lower clay contents than the (A)
and (B) samples. Therefore, there are very small amounts of clay
present deep within the soils at the site which would serve to trap
escaping materials in future years. The relatively high sand con-
tents in these lower regions would suggest that moisture movement
below the burial layer would be very rapid and that there could be
a risk of groundwater contaminations resulting from leakage from
the bur i a I s i te.
A dependence on such means as artificial plastic liners and
barriers of soil less than 50"/o clay, in my judgement, may not give
the safeguards necessary for storage ot large quantities of PCB
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material. Plastic liners will ultimately deteriorate due to act ions
of natural forces operating within the soil. This will result in
moisture movement through the disposal site which in turn wilt move
toxic materials. The low adsorptive capacity of the kaolinite clay
combined with the low moisture retention properties of the clays may
not prevent the system from leakage of chemical waste at some future
date.
2. Ground-water Regulations. The N.C. proposal is in general non-compli-
ance with EPA regulations on groundwater protection on two points:
a. The proposal does not show evidence that the site of PCB disposal
will be·"at .least ·SO feet!' from .the nearest groundwater". The
cores drilled at the site did not show groundwater at approximately
40 feet but this is not proof that the nearest groundwater wi JI 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 ~he rocks which have hydrolic connections --------
with streams and wells in the region. In such regions, a drill
core may miss groundwater channels very easily. From discussions
with Mr. Paul Pope, a resident of the area, it is difficult to
strike water in the region but he has had success on several
occasions.
b. The proposal does not provide for leachate collection beneath the
burial site. The leachate collection system being proposed oper-
ates ''within" the burial site. Thus, possible leakage from the
site would go undetected.· Drain pipes have been shown to be
damaged during backfilling operations which rendered them non-
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serviceable. Without leachate collection 11outside11 the burial
site, there is no means to assess their affectiveness, irrespec-
tive of the good intentions for saving the taxpayer's dollars.
The sites around the U.S. where leakage from waste chemical sites
have been detected should be adequate forewarning to avoid 11cost
cutting" procedures which may endanger the success for making
this a "safe site11 •
In fact, the EPA regulations state the artifical liner be-
neath a site with marginal clay thickness should be )30 milli-
meters in thickness. The N.C. proposal has no such liner beneath
the kaolinite clay .layer. In discussions~ith the owner of -the --
property, Mr. Carter Pope, the N.C. officials promised there would
be a 30 millimeter liner above, below and along the outsides of the
clay liner. In affect, this would place the PCB residue within
an artificial coffin. These promises have disappeared in the
formal proposal--and have -been replaced by a 10 mi 11 imeter thick-
ness top on the PCB residue.
RECOMMENDATIONS
1. The proposal to allow the State of North Carolina to utilize the
site in the Afton corrmunity in Warren County should be denied based
on the problems with clay thickness, clay type, groundwater uncer-
tainties and the general lack of groundwater protection from leachate
outside the PCB residue area.
2. The state of North Carolina should be allowed to dispose of PCB con-
taminated soil in one of the three following manners:
a. Placement of soil containing no greater than 200 ppm (mg/kg) PCB
residue in the upper portions of soils beneath major roadways and
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airports under construction. These soils are compacted to meet
the general EPA disposal guidelines plus they are protected from
water leaching through the soils. Also, they are well above ground-
water and remain relatively dry. By placing a thin layer of PCB
contaminated clay inbetween clay layers forming the roadway, there
will be no concentration of PCB in any one spot. Since the 200
ppm concentration is below the 500 ppm limit for classification
as a hazardous material, this alternative should be very cost
affective and not be a burden on the taxpayers. The soils could
be distributed across the state where such construction activities
are in progress or are being planned. Should delays be anticipated,
the materials could be removed from their present locations and
stockpiled on plastic and covered by plastic for unspecified
periods.
b. Stockpile the PCB materials in a manner described above and
c.
arrange for the courts to .mandate that punishment for the criminals,
which illegally dumped the materials on the roadways of North
Carolina, include the transport and disposition of the materials
in an EPA approved chemical waste site. The cost of removal and
transport to be born by the criminals, their companies or their
bonding agencies. d ,~ p~-, tt-I
Establish a waste chemical d~on site on soils high in 2:1
type clay minerals or montmorillonite clays. Such clays have a
high adsorptive capacity for cations, a high moisture retention
capacity and swelling properties which effectively seals the
clays from moisture movement. The corrrnon soi 1 series which one
would examine for such clays include the ''White Store" and
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11 I rede 11" soi 1 s. Deposits of both of these soi 1 s appear in
Orange County, N.C.