ML19332D058

Informs of Results of Investigation of Leaking Underground Storage Tank Sys at Plant,Originally Reported on 881111. Sketches Showing Configuration of Underground Storage Tank Sys,Soil Sampling Locations & Soil Contamination Encl

ML19332D058
Person / Time
Site:	River Bend
Issue date:	02/08/1989
From:	Booker J GULF STATES UTILITIES CO.
To:	Romanowsky P LOUISIANA, STATE OF
References
RBG-31121, NUDOCS 8911290352
Download: ML19332D058 (4)

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GULF STATES UTELET2ES COMPANY '31 "

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February 8, 1989  ;

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RBG- 31121 -

File No. G10.2.9

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,' Mr. Peter Romanowsky, Progran Manager .

Y _ Underground Storage Tank Division Louisiana Department of' Environmental Quality  :

Post Office Box 44274s Capitol Station 7 - B& ton Rouge, Louisiana 1 -70804

Dear.Mr. Romanowsky:

J This~ islto report the results of. our investigation of a leaking underground -  !

storage tank'(UST) system at Gulf States Utilities (GSU) Company's River Bend  ;

Station,'- originally _ reported via telephone.on November 11, 1988.- At the time  :

of.the initial report and the. written folkw-up four days- later, -it was '*

' belie ed that ~a minor -leak: from a jointed connection in- a waste oil sump drain

-line had contaminated a few cubic beet of-adjacent soil. We now know that  !

there- were 1 four-points of leakage which led to contamination of an estimated -

-- 60 cubic; feet of earth, in a zone about 3.5 to 5 feet below the Pface (about -

45 feet'above the nearest underlying groundwater). ,

-The attached sketches show:the configuration of the UST system, soil sampling locations,:and-the approximate extent of direct soil contamination- attributed

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to' leaks from the system. As noted' in our earlier reports,.the first indication ~of-a release was encountered while attempting to determine the size L and_' configuration of the UST system. Contrary to the descriptions (of Tank Nos. WM31 and WMS2) in a registration form filed-on May 5, 1986, tanks of 1

1,034 -and 2,329-gallon ccapacity, respectively, were found with associated piping comprised of poly-vinyl chloride (PVC). The' cylindrical' tanks were

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. side-by-side on a- level pad whien was 11 feet below grade and oriented

parallel to a vehicle maintenance shop foundation. DrainJiines about 45 feet long= ren at angles from two sumps in the shop and entered opposite ends of the top of the_ smaller tank. The west end drain line entered via a vertical line which' extended - 3 feet above grade to provide access to the first tank. A branch'from this vertical pipe provided connection to the other tank. Toward the least'end of the-second tank was its vertical clean-out pipe. This system was'apparently intended to be a make-shift wil/ water separator.

, Under separate cover GSU is submitting an amended registration form to correct u

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"the aforementioned (and other) discrepancies, as well as to notify you of our intent to permanently remove the waste oil UST system from service.

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1, y'Mr'.Romnowsky Page 2 Durirg late November and much of December 1988, the v;aste oil tank system was carr fully excavated with frequent and extensive delays due to weather, equipment problems, and waiting for analytical results. It was determined th6t some leakage had occurred at each of four points where joints and/or cennections existed in the PVC piping. None of the piping was damaged, but it ep;, eared that the four connections had become loosened due te deterioration of

.,ealant and/or slight displacements associated with surface vehicular traffic.

The' waste oil apparently had seeped from these connections at an extremely slow rate for an extended period. The aggregate volume released appears to have been very small, probably fewer than 20 gallons. It had spread mainly laterally, followin0 the -underside of pipin depending upon the specific point of release (g seeforstippled a few inches areas toinaattached few feet sketch). The major area of soil contamination was associated with the complex union of the shop drain, vcrtical clean-out, and inter-tank connection lines ,

above the wcst end of the 1,034- tank. Here the oil had migrated l Jeveral inches eastward and westward (gallon the former). There was very primarily little vertical migration of the oil, the thickest layer of contamination l being about 18 fnches in the immediate vicinity of the complex union just >

discussed.  !

Soil samples wert submitted to a contractor laboratory for analyses of total . ,

petroleum hydrocarbons (TPHC) and solvents / fuel (BT"X). Results showed an '

. absence of BTEX from all samples. TPHC concentrations in centaminated samples ranged from slightly greater than 3,500 mg/l to 14,285 mg/1. Samples from 2 feet below the UST system, opposite the four tank ends, ranged in TPHC concentration from 204 mg/l to 563 mg/1, whereas those from abov2 the tanks L and opposite their ends from depths of 3.5 - 5 feet had 324 - 1,063 mg/1.

l Much of the- soil within 5 feet of the surface in the general vicinity of the j UST system, regardless of proximity to the leaks discussed here, had TPHC 1 l concentrations of 500 - 1,100 mg/1. These slightly elevated TPHC levels are t attributed 'a the fact that the area in question has been used for parking of

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vehicles and heavy construction equipment continuously since late 1979. There- 1

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was a fairly clear distinction between soil having TPHC concentrations greater than 3,500 mg/l (which was semi-liquid to damp, discolored, and odorous) and -l' that having less than 1,100 mg/1. GSU therefore deemed the former to constitute the soil direcuy cor.taminated by the UST leaks. These estimated 60' cu5ic feet, along with several additional cubic yards of surrounding excavation spoil, have been accepted for disposal in an industrial landfill.

The waste oil tank themselves are in excellent condition and show no evidence of having leaked. Use of the system was suspended upon disconry of the l leaking pipes and, as noted above, GSU intends to permanently remove the L system from service. The tanks and much of the associated piping have already been removed as part of the leak investigation. Inasmuch as th3 excavation constitutes a nuisance and hazard, GSU would like to backfill it as soon as possible.

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We believe that- the investigation and clean-up activities described above-

--adequately addres: the. issues d dentified in your -letter of December 20..- 1988.4

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'If you have any questions, plesse contact James W. Cook at-(504) 381; 4151.

Sincerely,

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/,E J. .. Booker ..

Manager-- River Bend Oversight River Bend Nuclear Group i

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l LEGEND E E

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Diagrats depicting underground waste oil tank

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system near vehicle maintenance shop at River

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Band Station, where leaks were discovered on  ;

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November 11, 1988. Uppeta general orientation vies from northwest corner of excavation (stip-pling shows approximate locations / extent of con- 1 l

' taminated earth). Center Left: plan view indi- l l cating sampling locations. Cer.4er Rights and i , e view looking east indicating elevations of samp- I i ling locations at/near west end of excavation. I

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Lower Rights end view looking vest indicating elevations of sampling locations at east and of

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excavation. Triangles are locations of samples t I -

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taken at 3.5 - 5 f t below surf ace, near tanks e and/or piping. ~ Open squares are locations of ' I samples taken opposite the tank ends at the ', w f'

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approximate elevation (3.5 - 5 fc) where con- e / ,

taminated earth was found near piping. Solid l j g.

squares are locations of samples taken opposite the tank ends at a depth of 13 f t (2 ft below end of concrete pad). E E