Document QkEJeVOZVov5y70pXMZggqv07
PPG Industries. Inc. Chemicals P.O. Box 1000 Lake Charles. Louisiana 70602
January 7, 1991
Ms. Diana Buck Enforcement Branch (6W-E) U S Environmental Protection Agency 1445 Ross Avenue, Ste. 1200 Dallas, TX 75202-2733 Dear Ms. Buck: Permit No. LA0000761 - Unanticipated Bypass Report In accordance with the NPDES Permit #LA000076l Part II Section D reporting requirements, PPG Industries, Inc., Lake Charles Plant is hereby submitting the attached report of the January 2, 1991 unanticipated bypass resulting in exceedance of the effluent mercury limitation at Outfall 101. If you have any questions regarding this report, contact me at (318) 491-4450. Sincerelv.
Mark Wood Associate Research Chemist MWW/vc CERTIFIED MAIL
SL 026721
UNANTICIPATED BYPASS REPORT
DATE 1/2/91
OUTFALL 101
PARAMETER
Hg (24 hr composite)
limit
0.30 lb/day
EXCURSION +4.2 lb/day
EXPLANATION
At 3:55PM on the above date, after several hours of rain, collection of stormwater runoff was halted for 3-1/2 hours. The diversion of runoff directly to the outfall was necessary to prevent overflow from the raw wastewater storage and is proper operating procedure after extended periods of heavy rain. The rarely utilized diversion does not normally result in increased mercury discharge as the "first flush" of surface contamination is collected and treated prior to the cessation of collection. Analysis of the composite sample ending on January 3, 1991 at a point downstream of the confluence of both Mercury Internal Outfall Locations and the diverted stormwater resulted in the measurement of 4.5 lb/day mercury discharged. NPDES compliance monitoring for this same period at Outfall 101, locations 2 and 3, indicated.proper mercury control with a combined discharge rate of 0.013 lb/day.
Investigation of the system by operations personnel revealed no malfunction or condition that could account for the discharge. The downstream composite sample. Outfall 101, location 1, analyzed for mercury the following 24-hour period, was near normal.
SL 026722