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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.

Table 9.

OFF-SITE TOP SOIL
Contaminant Maximum Concentration ppm Sample Depth feet Reference HAC Value ppm HAC Source

Metals (Indicator)
Arsenic 3 0-2 MMFS 50 EMEG
Barium 154 1-3 MMFS 3,500 RfD
Cadmium 0.005 2-3 MMFS 200 EMEG
Chromium 40 2-3 MMFS 200 EMEG
Lead 91.1 0-2 MMFS None None
Manganese NA NA MMFS 5,000 RfD
Mercury 1.0 2-3 MMFS 40 EMEG
Volatile Organic Compounds
Benzene 55.4 0-6 WCEA 30 EMEG
Chloroform 18 2-3 MMFS 1,000 EMEG
1,1-dichlorethane 0.19 2-3 MMFS 5,000 RfD
1,1-dichloroethene 28 2-3 MMFS 400 EMEG
1,2-dichloroethane 170 2-3 MMFS 200 EMEG
1,2-dichloropropane NA NA NA 3,000 EMEG
1,3-dichloropropylene NA NA NA None None
Methylene Chloride 7.8 1-2 MMFS 2,000 EMEG
1,1,2,2-tetrachloroethane 5.8 2 BVII 10,000 RfD
Toluene NA NA NA 10,000 RfD
1,2-transdichloroethylene NA NA NA 1,000 RfD
1,1,2-trichloroethane 570 2-3 MMFS 2,000 EMEG
Trichloroethylene 0.26 2 BVII 100,000 EMEG
Vinyl Chloride ND 0-3 MMFS 50 EMEG
Semi-Volatile Organic Compounds
Acenaphthene 113 0-6 WCEA 3,000 RfD
Acenaphthylene 114 0-6 WCEA 5,000 MRL
Anthracene 781 0-6 WCEA 15,000 MRL
Benz (a) anthracene 33 1-2 WCEA 5,000 MRL
Benzo (a) pyrene 3.4 0-6 WCEA 5,000 MRL
Benzo (b) fluoranthene 3.1 0-6 WCEA 5,000 MRL
Bis(2-chloroethyl)ether 9.2 0-6 WCEA 1,000 EMEG
Bis(2-ethylhexyl)phthalate ND 0-3 MMFS 1,000 RfD
Chrysene 63.6 0-6 WCEA 5,000 MRL
Fluoranthene 76 0-6 WCEA 2,000 RfD
Fluorene 22 0-6 WCEA 2,000 RfD
Naphthalene 869 0-6 WCEA 66,500 MRL
Phenanthrene 550 1-2 WCEA 5,000 MRL
Pyrene 218 0-6 WCEA 1,500 RfD

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


Table 10.

OFF-SITE SHALLOW SUBSURFACE SOIL
Contaminant Maximum Concentration ppm Sample Depth feet Reference HAC Value ppm HAC Source

Metals (Indicator)
Arsenic 812.3 33-35 WCEA 50 EMEG
Barium 12,830 33-35 WCEA 3,500 RfD
Cadmium 9.0 21 WCEA 200 EMEG
Chromium 911.5 43-45 WCEA 200 EMEG
Lead 813.5 33-35 WCEA None None
Manganese 550 16 BVII 5,000 RfD
Mercury 10.3 28-30 WCEA 40 EMEG
Volatile Organic Compounds
Benzene 44 28-30 WCEA 30 EMEG
Chloroform 0.01 48-50 MMFS 1,000 EMEG
1,1-dichlorethane ND 6-50 BVII/MMFS 5,000 RfD
1,1-dichloroethene 0.12 5 WCEA 400 EMEG
1,2-dichloroethane 390 6-8 WCEA 200 EMEG
1,2-dichloropropane NA NA NA 3,000 EMEG
1,3-dichloropropylene NA NA NA None None
Methylene Chloride .008 33-35 MMFS 2,000 EMEG
1,1,2,2-tetrachloroethane ND 10-50 BVII/MMFS 10,000 RfD
Toluene 47 43-45 WCEA 10,000 RfD
1,2-transdichloroethylene 3.7 3+ BVII 1,000 RfD
1,1,2-trichloroethane 1200 6-8 WCEA 2,000 EMEG
Trichloroethylene 15 6-8 WCEA 100,000 EMEG
Vinyl Chloride 13 6-8 WCEA 50 EMEG
Semi-Volatile Organic Compounds
Acenaphthene 24 43-45 WCEA 3,000 RfD
Acenaphthylene 77 43-45 WCEA 5,000 MRL
Anthracene 140 43-45 WCEA 15,000 MRL
Benz (a) anthracene 6.5 43-45 WCEA 5,000 MRL
Benzo (a) pyrene 4.5 43-45 WCEA 5,000 MRL
Benzo (b) fluoranthene 3.4 43-45 WCEA 5,000 MRL
Bis(2-chloroethyl)ether 1,000 23-25 WCEA 1,000 EMEG
Bis(2-ethylhexyl)phthalate ND 6-50 MMFS 1,000 RfD
Chrysene 290 6-8 WCEA 5,000 MRL
Fluoranthene 17 43-45 WCEA 2,000 RfD
Fluorene 49 43-45 WCEA 2,000 RfD
Naphthalene 213 43-45 WCEA 66,500 MRL
Phenanthrene 78 43-45 WCEA 5,000 MRL
Pyrene 37 43-45 WCEA 1,500 RfD

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


Table 11.

OFF-SITE DEEP SUBSURFACE SOIL
Contaminant Maximum Concentration ppm Sample Depth feet Reference HAC Value ppm HAC Source

Metals (Indicator)
Arsenic 117.1 53-55 WCEA 50 EMEG
Barium 370 58-60 WCEA 3,500 RfD
Cadmium 6.4 50 WCEA 200 EMEG
Chromium 411 148-150 WCEA 200 EMEG
Lead 316.4 148-150 WCEA None None
Manganese NA NA NA 5,000 RfD
Mercury 0.6 53-55 WCEA 40 EMEG
Volatile Organic Compounds
Benzene ND 53-160 MMFS 30 EMEG
Chloroform ND 50-160 MMFS 1,000 EMEG
1,1-dichlorethane NA NA NA 5,000 RfD
1,1-dichloroethene ND 50+ MMFS 400 EMEG
1,2-dichloroethane 0.12 53-55 WCEA 200 EMEG
1,2-dichloropropane NA NA NA 3,000 EMEG
1,3-dichloropropylene NA NA NA None None
Methylene Chloride ND 53-160 MMFS 2,000 EMEG
1,1,2,2-tetrachloroethane ND 53-160 MMFS 10,000 RfD
Toluene NA NA NA 10,000 RfD
1,2-transdichloroethylene NA NA NA 1,000 RfD
1,1,2-trichloroethane 0.025 53-55 WCEA 2,000 EMEG
Trichloroethylene NA NA NA 100,000 EMEG
Vinyl Chloride ND 53-160 MMFS 50 EMEG
Semi-Volatile Organic Compounds
Acenaphthene ND 50+ WCEA 3,000 RfD
Acenaphthylene ND 50+ WCEA 5,000 MRL
Anthracene ND 50+ WCEA 15,000 MRL
Benz (a) anthracene ND 50+ WCEA 5,000 MRL
Benzo (a) pyrene ND 50+ WCEA 5,000 MRL
Benzo (b) fluoranthene ND 50+ WCEA 5,000 MRL
Bis(2-chloroethyl)ether ND 50+ WCEA 1,000 EMEG
Bis(2-ethylhexyl)phthalate ND 50+ MMFS 1,000 RfD
Chrysene ND 50+ WCEA 5,000 MRL
Fluoranthene ND 50+ WCEA 2,000 RfD
Fluorene ND 50+ WCEA 2,000 RfD
Naphthalene ND 50+ WCEA 66,500 MRL
Phenanthrene ND 50+ WCEA 5,000 MRL
Pyrene ND 50+ WCEA 1,500 RfD

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


Table 12.

OFF-SITE SHALLOW GROUND WATER
Contaminant Maximum Concentration ppm Reference HAC Value ppm HAC Source

Metals (Indicator)
Arsenic 0.036 WCEA 0.01 EMEG
Barium 22.0 WCEA 0.7 RfD
Cadmium 0.060 WCEA 0.005 EMEG
Chromium 0.140 WCEA 0.05 EMEG
Lead 1.4 WCEA None None
Manganese 13.9 BVII 1 RfD
Mercury 0.0026 WCEA 0.008 EMEG
Volatile Organic Compounds
Benzene 15.05 WCEA 0.007 EMEG
Chloroform 0.020 WCEA 0.2 EMEG
1,1-dichlorethane 0.112 BVII 1 RfD
1,1-dichloroethene 8.7 WCEA 0.09 EMEG
1,2-dichloroethane 164.0 WCEA 0.05 EMEG
1,2-dichloropropane .069 BVII 0.07 EMEG
1,3-dichloropropylene 0.173 BVII None None
Methylene Chloride 0.026 BVII 0.5 EMEG
1,1,2,2-tetrachloroethane NA NA 2 RfD
Toluene 0.184 BVII 2 RfD
1,2-transdichloroethylene 1.012 BVII 0.2 RfD
1,1,2-trichloroethane 149.0 WCEA 0.4 EMEG
Trichloroethylene 0.105 BVII 20 EMEG
Vinyl Chloride 56.0 WCEA 0.01 EMEG
Semi-Volatile Organic Compounds
Acenaphthene ND MMFS 0.6 RfD
Acenaphthylene ND MMFS 1.0 MRL
Anthracene ND MMFS 3.0 RfD
Benz (a) anthracene ND MMFS 1.0 MRL
Benzo (a) pyrene ND MMFS 1.0 MRL
Benzo (b) fluoranthene ND MMFS 1.0 MRL
Bis(2-chloroethyl)ether 1,414 WCEA 0.02 EMEG
Bis(2-ethylhexyl)phthalate ND MMFS 0.2 RfD
Chrysene ND MMFS 1.0 MRL
Fluoranthene ND MMFS 0.4 RfD
Fluorene ND MMFS 0.4 RfD
Naphthalene 220 WCEA 13.3 MRL
Phenanthrene 0.2 WCEA 1.0 MRL
Pyrene ND MMFS 0.3 RfD

*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


Table 13.

OFF-SITE DEEP GROUND WATER*
Contaminant Maximum Concentration ppm Reference HAC Value ppm HAC Source

Metals (Indicator)
Arsenic 0.005 WCEA 0.01 EMEG
Barium 0.362 WCEA 0.7 RfD
Cadmium ND MMFS 0.005 EMEG
Chromium 0.008 WCEA 0.05 EMEG
Lead 0.001 WCEA None None
Manganese NA NA 1 RfD
Mercury ND MMFS 0.008 EMEG
Volatile Organic Compounds
Benzene ND MMFS 0.007 EMEG
Chloroform ND MMFS 0.2 EMEG
1,1-dichlorethane ND MMFS 1 RfD
1,1-dichloroethene 0.005 WCEA 0.09 EMEG
1,2-dichloroethane 0.007 WCEA 0.05 EMEG
1,2-dichloropropane NA NA 0.07 EMEG
1,3-dichloropropylene ND MMFS None None
Methylene Chloride ND MMFS 0.5 EMEG
1,1,2,2-tetrachloroethane ND MMFS 2 RfD
Toluene NA NA 2 RfD
1,2-transdichloroethylene NA NA 0.2 RfD
1,1,2-trichloroethane 0.006 WCEA 0.4 EMEG
Trichloroethylene ND MMFS 20 EMEG
Vinyl Chloride ND MMFS 0.01 EMEG
Semi-Volatile Organic Compounds
Acenaphthene ND MMFS 0.6 RfD
Acenaphthylene ND MMFS 1.0 MRL
Anthracene ND MMFS 3.0 RfD
Benz (a) anthracene ND MMFS 1.0 MRL
Benzo (a) pyrene ND MMFS 1.0 MRL
Benzo (b) fluoranthene ND MMFS 1.0 MRL
Bis(2-chloroethyl)ether 0.025 WCEA 0.02 EMEG
Bis(2-ethylhexyl)phthalate 0.021 WCEA 0.2 RfD
Chrysene ND MMFS 1.0 MRL
Fluoranthene ND MMFS 0.4 RfD
Fluorene ND MMFS 0.4 RfD
Naphthalene 0.002 WCEA 13.3 MRL
Phenanthrene ND MMFS 1.0 MRL
Pyrene ND MMFS 0.3 RfD

*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


Table 14.

OFF-SITE SURFACE WATER
Contaminant Range Concentration ppm Reference HAC Value ppm HAC Source

Metals (Indicator)
Arsenic 0.28 BVII 0.01 EMEG
Barium 0.32 BVII 0.7 RfD
Cadmium 0.027 BVII 0.005 EMEG
Chromium 0.15 BVII 0.05 EMEG
Lead 0.19 BVII None None
Manganese 4.0 BVII 1 RfD
Mercury 0.0014 BVII 0.008 EMEG
Volatile Organic Compounds
Benzene NA NA 0.007 EMEG
Chloroform ND MMFS 0.2 EMEG
1,1-dichlorethane 0.003 WCEA 1 RfD
1,1-dichloroethene NA NA 0.09 EMEG
1,2-dichloroethane 0.192 WCEA 0.05 EMEG
1,2-dichloropropane NA NA 0.07 EMEG
1,3-dichloropropylene NA NA None None
Methylene Chloride NA NA 0.5 EMEG
1,1,2,2-tetrachloroethane NA NA 2 RfD
Toluene ND MMFS 2 RfD
1,2-transdichloroethylene NA NA 0.2 RfD
1,1,2-trichloroethane 0.252 BVII 0.4 EMEG
Trichloroethylene NA NA 20 EMEG
Vinyl Chloride 0.031 WCEA 0.01 EMEG
Semi-Volatile Organic Compounds
Acenaphthene NA NA 0.6 RfD
Acenaphthylene ND MMFS 1.0 MRL
Anthracene NA NA 3.0 RfD
Benz (a) anthracene NA NA 1.0 MRL
Benzo (a) pyrene NA NA 1.0 MRL
Benzo (b) fluoranthene NA NA 1.0 MRL
Bis(2-chloroethyl)ether NA NA 0.02 EMEG
Bis(2-ethylhexyl)phthalate ND MMFS 0.2 RfD
Chrysene NA NA 1.0 MRL
Fluoranthene NA NA 0.4 RfD
Fluorene NA NA 0.4 RfD
Naphthalene ND MMFS 13.3 MRL
Phenanthrene ND MMFS 1.0 MRL
Pyrene ND MMFS 0.3 RfD

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


Table 15.

OFF-SITE SURFACE SEDIMENT
Contaminant Range Concentration ppm Reference HAC Value ppm HAC Source

Metals (Indicator)
Arsenic 33 WCEA 50 EMEG
Barium 408 BVII 3,500 RfD
Cadmium 0.98 BVII 200 EMEG
Chromium 201 WCEA 200 EMEG
Lead 483 WCEA None None
Manganese 1800 BVII 5,000 RfD
Mercury 1.3 WCEA 40 EMEG
Volatile Organic Compounds
Benzene NA NA 30 EMEG
Chloroform 0.014 WCEA 1,000 EMEG
1,1-dichlorethane NA NA 5,000 RfD
1,1-dichloroethene NA NA 400 EMEG
1,2-dichloroethane 0.027 BVII 200 EMEG
1,2-dichloropropane NA NA 3,000 EMEG
1,3-dichloropropylene NA NA None None
Methylene Chloride NA NA 2,000 EMEG
1,1,2,2-tetrachloroethane NA NA 10,000 RfD
Toluene 0.016 WCEA 10,000 RfD
1,2-transdichloroethylene NA NA 1,000 RfD
1,1,2-trichloroethane 0.019 BVII 2,000 EMEG
Trichloroethylene NA NA 100,000 EMEG
Vinyl Chloride NA NA 50 EMEG
Semi-Volatile Organic Compounds
Acenaphthene NA NA 3,000 RfD
Acenaphthylene 0.30 BVII 5,000 MRL
Anthracene NA NA 15,000 MRL
Benz (a) anthracene NA NA 5,000 MRL
Benzo (a) pyrene NA NA 5,000 MRL
Benzo (b) fluoranthene NA NA 5,000 MRL
Bis(2-chloroethyl)ether NA NA 1,000 EMEG
Bis(2-ethylhexyl)phthalate 0.36 BVII 1,000 RfD
Chrysene NA NA 5,000 MRL
Fluoranthene NA NA 2,000 RfD
Fluorene NA NA 2,000 RfD
Naphthalene 0.025 WCEA 66,500 MRL
Phenanthrene 0.22 BVII 5,000 MRL
Pyrene 0.26 BVII 1,500 RfD

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.

Table 16.

CONTAMINANT CONCENTRATIONS IN BLUE CRAB AND MULLET*
CONTAMINANTS** ORGANISM UPSTREAM VALUE (ppm) DOWNSTREAM VALUE (ppm)

arsenic blue crab
mullet
0.33
0.23
0.43 - 0.70
0.23 - 0.43
barium blue crab
mullet
0.76
3.7
0.70 - 1.7
0.93 - 4.9
chromium blue crab
mullet
1.3
23.0
1.1 - 4.3
8.4 - 24.1
copper blue crab
mullet
14.4
1.7
24.0 - 37.7
0.94 - 3.4
lead blue crab
mullet
0.17
0.23
0.17 - 0.26
0.19 - 1.2
mercury blue crab
mullet
ND
ND
ND - 0.10
ND
selenium blue crab
mullet
0.36
0.23
0.27 - 0.47
ND - 0.32
benzyl alcohol blue crab
mullet
ND
ND
ND
2.5
di-ethyl phthalate blue crab
mullet
ND
ND
2.7
4.4
di-n-butyl phthalate blue crab
mullet
ND
ND
0.18
ND

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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