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<br /> Ms. Linda Turkatte
<br /> Dccemher 13, 1991
<br /> Page 2
<br /> t Ls i bon , cry
<br /> The Presence of free-phase hydrocarixin5 or free-hydrocarbtm sheen in the monitoring uc11s was
<br /> evaluated using Procedures described in Enclosure A. Free-phase hydrocarbons were detected in
<br /> monitoring well MW-4 (thickness 0.04-foot), on October 30, 199], and in monitoring wrll MW-2
<br /> (thickness 0.02 foot)when it was sampled on November 15. Hydrocarbon.
<br /> water saP.tples collected franr the Other monitorheen w;ts not p ell ed on
<br /> monitoring wells. Observatiars are included in Table 1.
<br /> A Westinghouse Pneumatically-operatedproduct-only pump was opera a gall. leiy in monitoring wells
<br /> n bot and MW-7 between January and April 1991. Hydrocarbon rocovery pumps have been operating
<br /> in bath wails simultaneously since May 1941. The totai amount of free-phase hydrocarbons recovered
<br /> since May 1991 is not knoiun because the Pumps have been discharging ground water as well as p.oduct.
<br /> fr�►und Ws�ltr$�mnlin un. n i ' R .'tt1
<br /> Ground water samples wet--collected from monitoring wells MW-1, MW-3, MW-5, MW{y ,4IW-7,
<br /> M1V-8, A4iV-9, and A7W-10 on October 30, 1991. Monitoring wells MW-2 and MW-4- were not
<br /> sa:ttpted due to the presi nee of free-pha hydrocarbons, as described above. Ground water samples
<br /> 'tvcre collected using Procedures describLd in Enclosure A. Each ground water sample vas submitted
<br /> 1a: analysis of benzene, toluene, ethylbenzene, xyh:nes (11TE
<br /> hydrocarbons(TPH) as gasoline, using �° and to [Wtraleum
<br /> Department of Health Services approved methods. The analytical samplesrortmental results forn AgencymroundCaltwrmr
<br /> in samples collected On October 30, 1991,are summarized in Table 2. Previous results are also provided
<br /> 13
<br /> Table 2 for comparison. Copies of the certified laboratory reorts fur the October 1991 sampling
<br /> event are included in Enclosure B. p
<br /> Analytical test results indicate that detectable concentration of Petroleum hydrocarbon constituents were
<br /> Present in each of the ground water samples collected on October 30, 1991, except far MW-6.
<br /> W
<br /> Concentrations of 1 p'1 as gasoline ranged from none detected (less than 30 parts per billion (ppb))
<br /> in MW-6 to 220,000 ppb M -9, and benzene concentration ranged from none dete
<br /> than 0.3 ppb) in MW-6 to 21.000 pph in MW-9. cted (less
<br /> ground wafer samples shoes Concentrations of total Petroleum hydrocarbons 'n
<br /> no consistent trend from the August sampling Measured concenuatioRS
<br /> Of benzene in samples Collected from monitoring wells have decreased since Auguspt;or MW
<br /> results is included as Figure 5. ,
<br /> A dissolved benzine isoconcentradon map prepared from the October 30, 199! texce -9.
<br /> ground water somal ng
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<br /> ecmwn�s
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