PUBLIC HEALTH ASSESSMENT ADDENDUM

MOTCO, INCORPORATED
TEXAS CITY, GALVESTON COUNTY, TEXAS

B. Off-Site Contamination

1. Soil Contamination

The off-site soil investigation, was divided into three samplingareas: top soil, shallow subsurface, and deep subsurface soils.Sixteen top-soil samples (0-6 feet in depth) were collected offsite. A slightly elevated level of benzene was found (55.4 ppm)(see Table 9). The highest VOC levels were detected west of Pit3, outside the site boundary fence at a depth of two to threefeet. The highest levels of PAHs were detected northwest of Pit3. No significant levels of metals were detected in the topsoil.

Shallow subsurface soil sampling indicated elevated levels ofVOCs and semi-VOCs. (See Table 10.) The highest concentrationsof contaminants were found northwest and southeast of the site. VOC contamination consisted of 1,1,2- trichloroethane (1200 ppm),1,2-dichloroethane (390 ppm) and benzene (44 ppm). Semi-VOCcontamination was primarily due to PAHs; however, bis(2-chloro-ethyl)ether, a non-PAH semi-volatile compound, ranged up to at1,000 ppm.

Elevated levels of arsenic, lead, and barium were also detectedin shallow subsurface soil samples (812.3 ppm, 813.5 ppm, and12,830 ppm respectively). The highest metal concentrations weredetected southeast of Pit 7. In addition, arsenic was seen at anelevated level (117.1 ppm) in the deep subsurface soil. (SeeTable 11.) No other appreciable levels of contaminants weredetected in deep subsurface soil.

2. Ground-water Contamination

Fifty-eight off-site monitoring wells were used to investigatethe ground water near the MOTCO site. Fifty-one wells werescreened in the shallow aquifer and seven were screened in thedeep aquifer. In addition, two deep industrial wells owned byDel Industries and Central Freight Lines were sampled. Bothindustrial wells are used for non-potable purposes. The DelIndustries well is screened at 700 feet, and the Central FreightLines well is screened at 600 feet. Both wells are locateddowngradient from the site.

Elevated levels of VOCs, semi-VOCs, and metals were detected inthe shallow aquifer. (See Table 12.) VOCs with the highestconcentrations included 1,2-dichloroethane (164 ppm),1,1,2-trichloroethane (149 ppm), vinyl chloride (56 ppm), andbenzene (15 ppm). Two other VOCs, 1,1-dichloroethene, and1,2-transdichloroethylene were also detected at elevated levels. The highest concentrations of VOCs were located southeast andnorthwest of the site.

Two semi-VOCs were detected at elevated levels. Naphthalene andbis(2-chloroethyl)ether had concentrations of up to 220 ppm and1414 ppm, respectively. The highest semi-VOC concentrations werelocated southeast of the site.

Several metals were detected at levels above health assessmentcomparison values. These included arsenic, barium, cadmium,chromium and manganese. Lead levels in the off-site shallowground water ranged up to 1.4 ppm.

A total of seven off-site monitoring wells were screened in thedeep aquifer with only low levels of VOCs, semi-VOCs, and metalswere detected in these wells. (See Table 13.)

A private well is also located at the nearest residence at adepth of approximately 160 feet. This residence, however, usesthe municipal water supply for potable purposes. In 1982, Blackand Veatch took water samples from the private well. Naphthalene(15 ppm), benzene (3.8 ppm), ethylbenzene (4.9), 1,2-dichloro-ethane (0.25 ppm), and toluene (82 ppm) were detected abovehealth assessment comparison values.

3. Surface-Water Contamination

Surface-water sampling was conducted at total of 19 locations. Samples were taken from: drainage ditches adjacent to ordowngradient from the MOTCO site, nearby marshes, Jones Bay, theBayou near the cities of Hitchcock and LaMarque, and the canal inthe Omega Bay Subdivision. Table 14 lists chemicals detected asa result of surface-water sampling.

Elevated levels of the VOCs 1,2-dichloroethane (0.192 ppm) andvinyl chloride (0.031 ppm), along with the metals arsenic (0.28ppm), cadmium (0.027), chromium (0.15 ppm), and manganese (4.0ppm) were detected. The highest levels of contamination weredetected in the surface water of the HL&P drainage ditch on thewest side of the MOTCO site.

4. Sediment Contamination

During the sampling events for the SFSI and EA, 19 off-sitesediment samples were taken. The locations of sediment samplingcorresponds with the locations of surface-water sampling. Lowlevels of metals, VOCs, and semi-VOCs were detected in thesediment samples. (See Table 15.) Only chromium (201 ppm)slightly exceeded the HAC value for soil; lead was also detectedin sediments up to 483 ppm.

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

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

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

*Transmissive Zones 1,2, & 3
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

*Upper Chicot Aquifer
ND = not detected
NA = not analyzed
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

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

5. Biota Contamination

An investigation of aquatic fauna was conducted in 1988 todetermine whether biologic organisms in the vicinity of the MOTCOsite were accumulating any chemical constituents. Two species ofaquatic fauna, one crustacean (blue crab) and one fish (mullet),were collected from five locations. Samples were taken fromlocations 0.5 mile upgradient and 0.125 miles, 0.25 mile, 0.5mile, 1 mile and 2.5 miles downgradient from the MOTCO site. Blue crabs were chosen because they are bottom feeders with arelatively small habitat range, making them good indicators ofchemical migration to the off-site aquatic food chain. Mulletwere chosen due to their abundance and relative ease ofcollection.

The aquatic samples were analyzed for metals and semi-volatiles. Table 16 lists chemicals detected in biota analyses.

ND = not detected
* sampling data from Woodward-Clyde Consultants, November 1987
** no other contaminants detected

A few metals were detected in both aquatic species; however, there was not a significant difference between the levels detected in the upgradient and downgradient species. Arsenic was detected in all downgradient samples. The highest level found was 0.7 ppm in blue crab samples from Jones Bay and the marsh southwest of MOTCO. Lead was detected in all samples, with the highest level at 1.2 ppm in the mullet sample from Jones Bay. Copper, with the highest concentration at 37.7 ppm (blue crab from the marsh southwest of MOTCO) was also detected in all samples. All values reflect whole specimen sampling.

Of the semi-VOCs, only three were detected at low levels in thedowngradient samples. Both mullet and blue crab containeddi-ethyl phthalate, but di-n-butyl phthalate was detected only inblue crab. Benzyl alcohol was detected at 2.5 ppm in mullet. Nosample was found to contain all three semi-volatile compounds.

6. Air Contamination

Initial air quality monitoring was conducted in the vicinity ofthe MOTCO site in September 1981 to evaluate the necessary levelsof respiratory protection for initial site work. Air samplingdid not take place during the SFSI or the EA. Six sampling pumplocations were chosen with two upwind and four downwind of theMOTCO site. One sample was taken downwind of the tank area wherethe highest on-site OVA reading occurred. During sampling eventsthe general wind direction was toward the west-southwest. Nocontaminants of concern were identified as a result of airquality monitoring.

C. Quality Assurance and Quality Control

Quality assurance and quality control information for the MOTCOsite was reviewed by TDH staff. Analyses that did not meetaccuracy and precision standards were flagged as unusable in theSFSI and EA and were not used in the preparation of this HealthAssessment Addendum. In preparing this Addendum to the HealthAssessment, TDH staff members relied on the information providedin the referenced documents and assumed that adequate qualityassurance and quality control measures were followed with regardto chain-of-custody, laboratory procedures, and data reporting. The analyses and conclusions in this Health Assessment Addendumare valid only if the referenced information is complete andreliable.

D. Physical and Other Hazards

On May 16, 1990, TDH and GCHD staff, with assistance from theMOTCO Trust Group, performed a site visit. The entire site isfenced and has locked and monitored entrances. The fence is alsoposted with warning signs.

The major on-site physical hazards are the remaining six wastepits, which cover 4.6 acres of the 11.3 acre site. The maximumpit depth is estimated at 15 to 20 feet. At the time of the sitevisit, the waste pits were open, with only yellow caution tapeposted around the circumference of each pit. No on-site fencesor other physical barriers were present to prevent persons fromfalling into or entering the waste pits.

Another on-site physical hazard was equipment that is used toconstruct and operate the incinerator and to excavate wastepits. In addition, the two water-filled borrow pits, locatedsouthwest of the site, could pose a drowning hazard, although thepits are not directly a result of the MOTCO site activities.

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