PUBLIC HEALTH ASSESSMENT ADDENDUM

MOTCO, INCORPORATED
TEXAS CITY, GALVESTON COUNTY, TEXAS

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The environmental media sampling program at MOTCO began with twoEPA-sponsored studies by Black And Veatch in 1981 and 1982. Additional sampling was conducted by Woodward and Clyde in 1984and 1986, and by CH2M Hill in 1984 and 1985. The types ofenvironmental media sampled included surface and subsurface soil,shallow and deep ground water, surface water, sediments, andaquatic biota (fish and crabs). The pit wastes were alsosampled. The samples were analyzed for Hazardous Substances List(HSL) metals and copper, volatile and semi-volatile compounds(HSL organics), pesticides and polychlorinated biphenyls (PCBs). Appendix C shows the locations of the monitoring wells, borings,and pits. Appendix D lists the chemical compounds that wereanalyzed in the laboratory.

We selected and discussed these contaminants based upon thefollowing factors:

1. Concentrations of contaminants on and off the site.


2. Field data quality, laboratory data quality, and sample design.


3. Comparison of on-site and off-site concentrations withbackground concentrations, if available.


4. Comparisons of on-site and off-site concentrations withATSDR Health Comparison (HAC) values for noncarcinogenicendpoints.


5. Community health concerns.

In the data tables that follow under on-site contamination andoff-site contamination, the listed contaminant does not mean thatit will cause adverse health effects from exposures. Instead,the list indicates which contaminants will be evaluated furtherin the Health Assessment. When selected as a contaminant ofconcern in one medium, that contaminant will be reported in allmedia.

The data tables include the following acronyms:

• EMEG = Environmental Media Evaluation Guide


• HAC = Health Assessment Comparison value


• ppm = parts per million


• RfD = Reference Dose

ATSDR Health Assessment Comparison (HAC) values are contaminantconcentrations in specific media that are used to selectcontaminants for further evaluation. These values includeEnvironmental Media Evaluation Guides (EMEGs) and other relevantguidelines. EPA's Reference Dose (RfD) is an estimate of thedaily exposure to a contaminant that is unlikely to cause adversehealth effects.

We conducted a search of the Toxic Chemical Release Inventory(TRI) for the zip code area containing the MOTCO site. The TRIdid not list any facilities having chemical releases in this areafor 1987-1989. Industries in the zip code area adjacent to MOTCOreported 59 releases in 1987, 55 releases in 1988, and 47releases in 1989. Several chemicals included in these reportedreleases are the same as those identified as MOTCO sitecontaminants.

A. On-Site Contamination

1. Soil Contamination

The on-site soil investigation was divided into three generalareas of sampling: (1) topsoil (0-6 feet); (2) shallowsubsurface (depths to 50 feet); and (3) deep subsurface (depthsbelow 50 feet).

In 1983, 11 surface (0.5-1.0 foot) soil samples were obtained along the northwest, southeast and southwest perimeter dikes at locations that showed visible evidence of dike leakage and five surface soil samples were obtained at locations with no evidence of dike leakage. Woodward-Clyde Consultants screened these samples for volatile and non-volatile organic compounds and metals. Metals, volatile and aromatic compounds were detected in field tests. Metals in the surface soils were further analyzed in the laboratory. Table 1 shows the maximum levels of metals detected in the on-site surface (0.5-1.0 foot) soils. None exceeded available health assessment comparison values.

The major contaminants in shallow subsurface soil samples weresemi-volatile compounds (semi-VOCs). (See Table 2.) Semi-VOCcontamination was detected as far down as 50 feet. ThePolynuclear Aromatic Hydrocarbons (PAHs) fluorene, naphthalene,phenanthrene, and pyrene were detected at depths greater than 50feet.

The highest volatile organic compound (VOC) levels were locatedat depths greater than four feet. Benzene, 1,1,2-trichloroethane, and 1,2-dichloroethane were detected at maximumlevels of 15 ppm, 640 ppm, and 1200 ppm, respectively.

The highest metal concentrations were located at depths greaterthan 33 feet below ground surface (BGS). The shallow subsurfacesoil samples containing the highest levels of contamination werelocated northeast of Pit 7 and east of Pit 2.

Only a few compounds were detected in the deep subsurface soil. (See Table 3.) In general, the highest concentrations ofcontaminants in deep subsurface soil occurred at a depths of53-55 feet. The samples containing the highest concentrations ofcontaminants were located east of Pit 2 and northeast of Pit 7.

ND = not detected
NA = not analyzed
BVII = Black & Veatch Initial Investigation, Dec. 1981
MMFS = Management Migration Feasibility Study, Vol.2, May 1988
WCEA = Woodward & Clyde Endangerment Assessment, May 1989

ND = not detected
NA = not analyzed
BVII = Black & Veatch Initial Investigation, Dec. 1981
MMFS = Management Migration Feasibility Study, Vol.2, May 1988
WCEA = Woodward & Clyde Endangerment Assessment, May 1989

2. Ground-Water Contamination

Eight on-site monitoring wells were sampled. Six of the monitorwells were screened in the shallow aquifer (transmissive zones 1,2, and 3) and two monitor wells were screened in the deeperaquifer (Upper Chicot). Seven of the wells were located in theeastern part of the site, with one well located northeast of Pit1.

The majority of the ground-water contamination in the shallow aquifer consists of VOCs although some semi-VOCs and metal contamination were also detected. (See Table 4.) Contaminants with the highest concentrations were 1,2-dichloroethane (3500 ppm), 1,1,2-trichloroethane (250 ppm), vinyl chloride (116 ppm), and benzene (40.45 ppm). In addition, methylene chloride was detected at a concentration of 0.5 ppm. The highest VOC concentrations were found southeast of Pit 7. Low levels of PAHs were detected in the shallow ground water; however, bis(2-chloro-ethyl)ether was detected at 3300 ppm. The highest levels were found in the well located southeast of Pit 7. The highest ground-water metal concentrations were detected northeast of Pit 7 and close to the plant's main entrance. Metals considered contaminants of concern were manganese (9.2 ppm), chromium (0.56 ppm), cadmium (0.48 ppm), and lead (0.45 ppm).

Only two on-site wells draw water from the deeper aquifer. Bothwells are located northwest of Pit 7. Contamination in the wellsis limited primarily to VOCs, although a few semi-VOCs and metalsare present at low levels (see Table 5). The VOCs with thehighest concentrations are vinyl chloride (0.68 ppm), 1,2-dichloroethane (0.5 ppm), and 1,1-dichloroethene (0.091 ppm). Inaddition, benzene was detected at 0.052 ppm.

3. Waste-Pit Contamination

The majority of the on-site wastes at MOTCO are contained inseven unlined waste pits. The maximum pit depth is between 15and 20 feet, and together the pits cover approximately 4.6 acres. Primary contaminants associated with the waste pits includechlorinated and aromatic hydrocarbons and PAHs. Polychlorinatedbiphenyls (PCBs) and heavy metals are also contained in the wastepits. (See Tables 6, 7, and 8.)

4. Air Contamination

Air quality monitoring was conducted at the MOTCO site inSeptember 1981, to evaluate the necessary levels of respiratoryprotection for initial site remediation work. An organic vaporanalyzer (OVA) was used. No contaminants of concern wereidentified as a result of on-site air quality sampling.

*Transmissive Zones 1,2,&3
ND = not detected
BVII = Black & Veatch Initial Investigation, Dec. 1981
MMFS = Management Migration Feasibility Study, Vol.2, May 1988
WCEA = Woodward & Clyde Endangerment Assessment, May 1989

* Upper Chicot Aquifer
NA = not analyzed
ND = not detected
BVII = Black & Veatch Initial Investigation, Dec. 1981
MMFS = Management Migration Feasibility Study, Vol.2, May 1988
WCEA = Woodward & Clyde Endangerment Assessment, May 1989

P = present
TR = trace

ND = not detected

ND = not detected

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