NCD981023260_19900718_Potters Septic Tank Service Pits_FRBCERCLA SPD_Preliminary Health Assessment-OCR

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.. PRELl'MINARY
.Health
. Assessment
for
POTTER'S SEPTIC TANK SERVICE PITS
MACO, BRUNSWICK COUNTY, NORTH CAROLINA
CERCLIS NO. NCD981O2326O
JUL 18 1990
U.S. DEPARTMENT OF lHEAlLT!H AND !HUMAN SERVlICE§
PUBLIC HEALTH SERVICE
Agency for Toxic Substances and Disease Registry
--------------------------------------------------
THE A TSDR HEAL TII ASSESSMENT: A NOTE OF EXPLANATION
Section 104 (i) (7) (A) of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980
(CERCLA), as amended, states " ... the term 'health assessment' shall include preliminary assessments of potential risks to
human health posed by individual sites and facilities, based on such factors as the nature and extent of contamination, the
existence of potential pathways of human exposure (including ground or surface water contamination, air emissions, and
food chain contamination), the size and potential susceptibility of the community within the likely pathways of exposure,
the comparison of expected human exposure levels to the short-term and long-term health effects associated with
identified hazardous substances and any available recommended exposure or tolerance limits for such hazardous
substances, and the comparison of existing morbidity and mortality data on diseases that may be associated with the
observed levels of exposure. The Administrator of ATSDR shall use appropriate data, risks assessments, risk evaluations
and studies available from the Administrator of EPA."
In accordance with the CERCLA section cited, A TSDR has conducted this preliminary health assessment on the data in
the site summary form. Additional health assessments may be conducted for this site as more information becomes
available to ATSDR.
Use of trade names is for identification only and does not constitute endorsement by the Public Health Service or the
U.S. Department of Health and Human Services.
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In May 1976, the North Carolina Department of Natural Resources (NCDNR)
notified the owner of the three waste hauling companies that the oil
disposal pit in Area 2 violated North Carolina statutes and must be
cleaned up. The pit, which was approximately 60 feet long, 20 feet wide,
and 2 to 4 feet deep, contained approximately 2,000 to 3,000 gallons of
waste oil. The owner pumped the oil from the pit and covered the pit with
soil. The composition of the oil, its ultimate fate, and the
characteristics of the soil or sludge buried on site are unknown.
Soil-gas sampling has been conducted in Area 2. Results were negative,
suggesting that, if there was once contamination in this area, the cleanup
must have effectively removed most, if not all, of the contamination.
This area is not now considered to be part of the NPL site.
Soil-gas and soil sampling were recently performed in Area 3. The
soil-gas samples were unremarkable. If the soil samples reveal similar
results, Area 3 will not receive further consideration as part of this NPL
site.
In August 1976, an earthen berm in Area 1 failed, and approximately 20,000
gallons of oil flowed into Chinnis Branch, a nearby stream. The
contamination then flowed via Chinnis Branch to the Rattlesnake Branch.
The U.S. Coast Guard was notified of the contamination of this Class C
water body, and a cleanup was initiated.
Due to ineffective cleanup methods, the oily contamination in the swampy
areas of Rattlesnake Branch was left in place. An additional 20,000
gallons of oil remaining in the pit was pumped out and disposed of at Fort
Bragg, North Carolina. Oil sludge also was removed from the pit, and
transported to Brunswick County Landfill in Leland, North Carolina. Three
other pits found in the area were similarly remediated. Thick sludge that
could not be pumped out was mixed with sand and buried on site. About
1982, the property in and around the site was subdivided for residential
property known as Sandy Creek Acres. At least three occupied residences
are located on or near the site.
In July 1983, after development of the subdivision, the owner of one of
the lots found sludge in his front yard and informed the North Carolina
Department of Human Resources (NCDHR). Subsequent investigation by NCDHR
indicated that the residence appeared to be located over at least one of
the former pits. The water well for this residence may have been sited
through one of the pits. Water samples from this well were found to
contain phenols, substituted benzenes, creosote and septic tank sludge.
Subsequent sampling by NCDHR revealed these and other contaminants in soil
near the surface. NCDHR advised the owner to discontinue use of the
well. The residence reportedly is now supplied with water from the well
of a residence across the street. The well purportedly is upgradient.
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In September 1983 and February 1984, EPA's Office of Emergency Response
conducted various site investigations--collecting air, subsurface soil,
surface water, and groundwater samples, and evaluating the magnitude of
the buried wastes. On March 9, 1984, ATSDR certified to EPA that the site
represented a threat to hwnan health and warranted immediate cleanup.
Subsequently, EPA initiated an immediate removal action that centered
around the residential property initially reporting contamination. Two
areas were excavated to various depths, and 1,770 tons of oily sludges and
contaminated soils were removed. The areas were refiiled with clean soil,
then graded and seeded.
In May 1984, a groundwater study, of 12 wells determined that the shallow
aquifer was contaminated with various organic chemicals; but the deep
aquifer had not been impacted. In a groundwater monitoring program
recommended by EPA, NCDHR confirmed the shallow aquifer contamination in
May 1988. This more recent data indicated the possibility that the deep
aquifer had become contaminated.
The site is in a mostly forested area, except for that land cleared for
residential housing. Each house has a private domestic water well. The
area is primarily flat, lying in the coastal plain. Significant surface
water bodies nearby are: Chinnis Branch, Little Green Swamp (the
headwaters for Chinnis Branch, west of the site), and Rattlesnake Branch
(northeast of the site). Hood Creek receives water from Rattlesnake
Branch, and then flows northeast into the Cape Fear River, which flows
into the Atlantic River. The site maps in the Appendix show these
relationships.
Groundwater in the shallow aquifer is believed to flow in a variable but
generally east-southeast direction. Groundwater in the deep aquifer is
believed to flow in a north-northeast direction.
B. SITE VISIT
A site visit was performed by representatives of ATSDR on March 15, 1989.
Land use in the site vicinity is residential, with mobile homes and single
family residences. Access to the site is unrestricted. The surface
grasses and ground cover are typical of residential lot. Private wells
provide drinking water for residential use.
C. COMMUNITY HEALTH CONCERNS
On February 28, 1990,
regarding this site.
following topics were
ATSDR representatives attended a community meeting
Approximately 78 people were in attendance. The
discussed.
1.
2.
Long-term health effects of benzene and other voes.
What carcinogenic chemicals are found at the site.
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3.
4.
Tests of the drinking water used by the residents living
near the site.
Installation of an alternative water supply.
DEMOGRAPHICS, LAND USE, AND NATURAL RESOURCE USE
The site's disposal areas are located in a rural section of Brunswick
County called Sandy Creek Acres, approximately one mile west of Maco
(population unknown). Approximately 1,000 people living within 3 miles of
the three areas are dependent upon groundwater for water supplies.
Most.if not all. local residential wells tap the deep aquifer, which
apparently is separated from the shallow aquifer by a continuous clay
layer. The shallow aquifer is estimated to be 10 to 12 feet thick and 5
to 17 feet below land surface. There are no municipal water systems for
Maco or the area of Brunswick County surrounding Maco.
ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS
A. ON-SITE CONTAMINATION
Heavy metals, volatile organic compounds (VOCs), and polynuclear aromatic
hydrocarbons (PAHs) have been detected in groundwater, sediment, surface
water, and soil at the site. The following tables highlight the
documented chemical contamination, the media in which the contamination
was measured, and the maximum concentrations reported.
Sampling data are available for 1983, 1984, and 1988. Some of the data un
individual compounds were estimated values and are not listed here.
Results of heavy metal analyses from 1984 and 1988 were unremarkable.
Substances other than those listed in the following tables were detected
at this site. However, those chemicals will not be considered further in
this preliminary health assessment for one or more of the following
reasons: the chemicals were detected in very few samples; the chemicals
were detected in limited areas; the chemicals concentrations were low
relative to levels considered to be of public health importance; the
chemical concentrations were low relative to typical background
concentrations; or the chemicals were detected in low concentration and
had similar environmental fate and transport characteristics to other
evaluated chemicals.
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Table 1
ON-SITE CONTAMINATION
POTTER'S SEPTIC TANK SERVICE PITS SITE
Contaminant
benzene
toluene
total xylenes
lead
arsenic
zinc
total PAHs
total PAHs
benzene
toluene
total xylenes
benzene
toluene: _
total xylenes
ethylbenzene
B.. -OFF-SITE CONTAMINATION
Medium Max. Cone. i££IB1
1983 Data
groundwater 1.3
6.6
21
0.24
0.01
11
0.79
subsurface soil 45
1983 Data
groundwater
1988 Data
g"t"oundwater
10
35
23
7 .4
77
25.3
4. 6
The only samples that will be considered "off-site" are two private
well samples, three EPA monitoring well samples, and two surface
water ·and sediment samples from Chinnis Branch. The locations are
.depicted in Site Map 2. _These samples presumably would. indicate if
contaminants have migrated from the immediate disposal areas. The-s·e·
rePortetj results for benzene, toluene, and total xylenes are
summarized in the table below.
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Table 2
OFF-SITE CONTAMINATION
POTTER'S SEPTIC TANK SERVICE PITS SITE
Contaminant Medium Max. Cone. (ppm)
1983 Data
No concentrations of public health significance.
total xylenes
1984 Data
groundwater
1988 Data
0.65
No concentrations of public health significance.
C. QUALITY ASSURANCE AND QUALITY CONTROL
The analytical data regarding extractable organic material often were
estimated, presumptive, or average values. Such data were not used.
Detection limits for analytical methods were not indicated. It is assumed
that the data provided for this Preliminary Health Assessment were
collected and analyzed according to standard methodology, and in the
absence of definitive information regarding these procedures, are
acceptable for the purpose of Preliminary Health Assessment.
D. PHYSICAL AND OTHER HAZARDS
No physical hazards were identified at the site.
PATHWAYS ANALYSES
A. ENVIRONMENTAL PATHWAYS (FATE and TRANSPORT)
The environmental pathways of concern at the site are: contaminated
groundwater, surface water, sediment, surface and subsurface soil, and
air.
Groundwater has been shown to contain high concentrations of hazardous
substances. Benzene, toluene, ethylbenzene, and xylene, arsenic, lead,
and PAHs (several polynuclear aromatic hydrocarbons of varying degrees of
toxicity are grouped and referred to as total PAHs) have been measured in
groundwater and subsurface soil. Data since 1984 were collected after an
emergency removal operation took place, and suggests that a considerable
reservoir of contamination remains.
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Due to the removal action, contaminated surface soil may no longer exist;
however, this has not been confirmed by sampling. Unless substantial
surface soil contamination is present, airborne contamination by V0Cs or
contaminated particulates is unlikely.
Based on the most recent groundwater sampling, subsurface soil
contamination is believed to be present. Asswning that the shallow
groundwater flow is south-southeast, the potential exists for
contamination of Chinnis Branch and joining surface water bodies.
The VOCs detected are soluble in water (solubilities range from 198 to 515
mg/L), so solution from soil to groundwater can occur. This transport
phenomenon can be retarded by soil with a high organic content. The log
octanol/water coefficients measure of tendency to partition between
organic and inorganic media--range from 2.79 to 3.26. Volatilization from
surface water or surface soil can occur. Vapor pressures of these VOCs
range from 10 to 22 millimeters of mercury at 20 degrees Centigrade).
Soluble forms of arsenic tend to be very mobile in water, while less
soluble forms tend to adsorb to soil particles and migrate according to
surface water and groundwater movements. Acidity (pH) is important with
respect to arsenic leaching from soil, with higher acidity soils tending
to retain arsenic to a greater extent. Transformation (such as
methylation) to organic forms will cause release back to the water
column. Methylation and reduction by soil and water microorganisms
increases the volatilization of arsenic from these media, so arsenic may
be released to the atmosphere. Bioconcentration occurs in aquatic
organisms, primarily algae and lower invertebrates. Biomagnification of
arsenic in aquatic food chains does not appear to be significant. Some
plants can accumulate arsenic via root uptake.
Lead is transferred continuously between air, water, and soil by natural
chemical processes such as weathering, runoff, precipitation, dry
deposition of dust, and stream or river flow; however, soil and sediments
appear to be important sinks for lead, and very little is transported into
surface water or groundwater. Many plants commonly take up lead from
soil. Lead in aqueous solution may occur in many forms, however it has a
tendency to form insoluble compounds with carbonate, hydroxide, and
sulfide. The amount of lead remaining in water depends on the acidity of
the water. Except for some shellfish such as mussels, lead does not
appear to bioaccumulate significantly in most fish.
Polynuclear aromatic hydrocarbons (PAHs) occur in the environment mostly
as a result of man-induced incomplete combustion of organic material such
as coal, oil, and wood. PAHs are primarily partitioned to soil and
sediment and are very persistent in these media, with the main degradation
mechanism being biodegradation. PAHs have low water solubilities and a
high propensity for binding to organic or particulate matter. Aquatic
organisms can assimilate PAHs readily; however, metabolism and excretion
of PAHs by aquatic organisms is rapid.
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In swnmary, groundwater and soil contamination are the environmental
pathways of most concern. Surface water and soil will release most VOCs
to the atmosphere. Some arsenic and lead may be retained by aqueous
media, but most arsenic and lead is expected to adsorb to either soil or
sediment. PAHs will be retained by the sediment or soil they contact.
B. HUMAN EXPOSURE PATHWAYS
The human exposure pathway of primary concern is conswnption of
contaminated groundwater. In addition, inhalation of VOCs released from
groundwater used for bathing, showering, and cooking also can be important
pathways. Because of the removal operations that took place, dermal
contact with contaminated groundwater and surface water, soil, and
sediment, and ingestion of contaminated soil and sediment probably are
less important pathways.
PUBLIC HEALTH IMPLICATIONS
The limited sampling information in Table 2 suggests that most of the
contaminants present on site have not migrated off site in groundwater,
sediment, surface water, or soil. However, this conclusion may be in
error, since sample locations may be upgradient of the groundwater flow.
The data from Table 1 indicates high concentrations of contaminants
remained on site after the emergency removal. Heavy metal, PAH, and VOC
contamination has been docwnented in groundwater at the site. Of these
substances, benzene, arsenic, and PAHs have been shown to cause cancer.
VOC contamination appears to be the most significant in terms of
concentration. Using the maximum concentration measured, and assuming 2
and 1 liters (L) of water per day and a body weight of 70 and 20 kilograms
for an adult and child, respectively, the potential public health impact
of the individual contaminants can be estimated.
Calculations using the assumptions noted above and the data in Tables 1
and 2 indicate that chronic conswnption of the groundwater may exceed the
intake levels recommended by EPA for toluene, xylene, lead, zinc, and
ethylbenzene. In addition, similar calculations for arsenic, benzene, and
PAHs suggest that persons are at increased risk of developing cancer as a
result of drinking this groundwater.
CONCLUSIONS
Based upon information reviewed, ATSDR has concluded that this site is of
potential public health concern because of the risk to human health
resulting from possible exposure to hazardous substances at concentration~
that may result in adverse human health effects. As noted in the Human
Exposure Pathways Section above, hwnan exposure to heavy metals, PAHs, and
VOCs may be occurring and may have occurred in the past via contaminated
groundwater, surface water, soil, sediment, air, and the food chain.
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Off-site contamination has not been investigated. Our definition of off
site was based on the suspected location of the waste pits. Shallow
groundwater is suspected of flowing in the direction of Chinnis Branch,
which would place the off-site well, surface water, and sediment samples
in an upgradient location. Hence, these data may be useful in defining
the upgradient contamination boundaries.
The removal operation at the site was not evaluated for cleanup
efficiency. The potential may exist for residents to come in contact with
contaminated surface soil.
Further environmental characterization and sampling of the site and
impacted off-site areas during the Remedial Investigation and Feasibility
Study (RI/FS) should be designed to address the environmental and human
exposure pathways discussed above. When additional information and data
become available, such material will form the basis for further assessment
by ATSDR at a later date.
RECOMMENDATIONS
In accordance with the Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) as amended, the Potter's Septic Tank Pits site
has been evaluated for appropriate follow-up with respect to health
effects studies. Since human exposure to on-site or off-site contaminants
of significant public health concern may currently be occurring and may
have occurred in the past, this site is being considered for follow-up
studies. After consultation with Regional EPA staff and State and local
health and environmental officials, the Epidemiology and Medicine Branch,
Division of Health Studies, ATSDR, will determine if follow-up public
health actions or studies are appropriate for this site.
The following recommendations are offered:
1. Sample the deep aquifer underlying the site to determine if it has
been affected by site contaminants.
2. Sample surface soil sampling to determine the efficiency of the
removal effort.
3. Conriuct a sampling program for present residential wells. All new
residential wells should be sampled before occupancy. A monitoring
program may be necessary to prevent future contamination of wells
initially judged to be acceptable. An alternate water supply should
be identified should its use become necessary.
4. When indicated by public health needs, and as resources permit, the
evaluation of additional relevant public health outcome data and
community health concerns, if available, is recommended.
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PREPARER OF THE REPORT
Environmental and Health
Assessor:
Clifford L. Moseley
Remedial Programs Branch
Division of Health Assessment and
Consultation
ATSDR REGIONAL REPRESENTATIVE
Regional Representative: Casimer Pietrosewicz
Public Health Advisor
Region IV
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REFERENCES
The following documents were used by ATSDR to prepare this Preliminary
Health Assessment. Further information made available after the
development of this preliminary health assessment will be addressed in any
subsequent health assessment.
Ebasco Services Incorporated. Draft Work Plan, Potter's Pits Septic Tank
Site. March 1989.
Hazard Ranking System Package Scoresheet and Documentation. September 22,
1986.
NUS Corporation.
Pits. August 27,
Sampling Investigation Report, Potter's Septic Tank
1985.
Agency for Toxic Substances and Disease. Registry.
dated march 12, 1984, concerning emergency cleanup
Site.
Memorandum to EPA,
of Potter's Pits CERCLA
Agency for Toxic Substances and Disease Registry. Toxicological Profiles
for various Polynuclear Aromatic Hydrocarbons. Atlanta, Georgia. In
draft.
Agency for Toxic Substances and Disease Registry. Toxicological Profile
for Arsenic. Agency for Toxic Substances and Disease Registry Publication
No. ATSDR/TP-88/02. Atlanta, Georgia. March 1989.
Agency for
for Lead.
Toxic Substances and Disease
Atlanta, Georgia. In draft.
Registry. Toxicological Profile
Agency for Toxic Substances and Disease Registry. Toxicological Profile
for Benzene. Agency for Toxic Substances and Disease Registry Publication
No. ATSDR/TP-88/03. May 1989.
Agency for Toxic Substances and Disease Registry. Toxicological Profile
for Toluene. Agency for Toxic Substances and Disease Registry Publication
No. ATSDR/TP-89/23. December 1989.
Agency for Toxic Substances and Disease Registry.
for Zinc. Agency for Toxic Substances and Disease
No. ATSDR/TP-89/25. December 1989.
Page 11
Toxicological Profile
Registry Publication
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APPENDIX
Site Map 1, three areas of suspected waste disposal, Potters Proposed NPL
Site.
Site Map 2, suspected location of waste pits in Area 1, Potters Proposed
NPL Site.
Site Map 3, general location of site to major geographic features, Potters
Proposed NPL Site.
Page 12
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. ~,k.<'!.cf;?", . /---··· .•·w
___ ... APPROX. SCALE
0 350 700 FEET
-~ /
LEGEND
===PAVED ROAD
t I I I 1 1 I RAILROAD TRACKS
- · -OLD ACCESS ROAD = = = = UNPAVED ROAD
-···-STREAM
:@J;@ STUDY AREA
/.. ·----.. .•·
/ EA 2
SITE MAP 1
LOC<\TION OF THREE STUDY AREAS
POi !ER'S SEPTIC TANK PITS SITE
MACO, NOf:ITH CAROLINA
-------------------
-----• • -.--. •• CHINIIIS ... --·.
--··
PITS-<-"'-~.
RESIDENCE--..___
CJ
RESIDENCE
--·-··-
\
6 c==sJ
===-------
D
RESIOEIICE
SITE MAP 2
SAMPLE POINT LOCATIONS
SEPTEMBER 6-9, 1983
1
1 -~-~"~ -~ktv, ---
•WATER SAMPLE •
■ SOll/Sl'DIMEl<T
SAMPLE
NOT "lO SCALE
'
POTTER'S SEPTIC TANK PITS SITE
MACO, NORTH CAROLINA
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' /
QUAOA-'NC.lf. LOCA TLON
~\,J\t_f: IN F((T I _....,.
0 1000 2000.
/
/ /
SITE MAP 3
SITE LOCATION MAP
POTTER'S SEPTIC TANK PITS SITE
MACO, NORTH CAROLINA