C - Hanford Site

U '. Richland
WHC-SD-EN-TI-136, Rev. 0
Department of Eblergy-
Operations Office
0Richland, Washington 99352 Incoming: 9102476
91-ERB-116
Mr. Mike C. Osweiler
Nuclear and Mixed Waste,
Hanford Project
State of Washington
Department of Ecology
7601 W. Cleatrwater, Suite 102
Kennewick, Washington 99336
Dear Mr. Osweiler:
.i U . 1991
PERMANENT CLOSURE OF UNDERGROUND STORAGE TANK (UST) 100N-SS--28
The purpose of this letter, as required by WAC 173-360-385, is to provide the
Washington State Department of Ecology (Ecology) with at least 30 days advance
notification prior to beginning permanent closure (removal) of UST 100N-SS-28.
This tank is located at the lOON Area of the Hanford Site, has a capacity of
2,000 gallons, and is constructed of 3/16" wall carbon steel with an asphalt
coating. Originally, the 100N-SS-28 tank contained diesel fuel. Unleaded
fuel was transferred from the UST IOON-SS-27 into UST IOON-SS-28 following
closure of the 100N-SS-27 UST in June of 1990. The 100N-SS-28 tank was
tightness tested in October of 1990 and found to be tight per 40 CFR 280/281.
This tank is no longer needed and is being removed to facilitate the site
assessment of the 10ON fuel station site. These two tanks were both part of a
self-service gas station and were located approximately nine feet apart. Tank
100N-SS-27 was removed in December 1990 after it had failed tightness testing
and the decision made, because of its age, to close the tank rather than
upgrade it to new tank standards. Contaminated soil was discovered at the
site after the tank was removed. (See Enclosure 1, Twenty-Day Report; and
Enclosure 2, Forty-Five Day Report.)
Since this site has already been confirmed as a release site and the required
24-hour notification given after the removal of the 100N-SS-27 UST, an
additional 24-hour notification pursuant to WAC 173-360-372 will not be given
unless there is other evidence of a release emanating from tank JOON-SS-28.
However, all other reporting requirements as given in WAC 173-340-450 will be
met. A plan for the remediation of the site will be prepared following the
IOON-SS-28 removal and site characterization activities, which are expected to
be completed by August 15, 1991. Also, additional site characterization is
being conducted to determine the extent of the contamination. Ecology will be
provided with a draft of the remediation plan for review prior to initiating
remedial activities.
B-28