ML20206G615

NPDES Noncompliance Notification:On 860616,50 Gallons of Raw Sewage Discharged from Primary Equalization Tank of Main Sewage Treatment Plant Into Lake.Caused by Equalization Tank Pump Trip.Pump Restarted & Catch Basin Cleaned

ML20206G615
Person / Time
Site:	North Anna
Issue date:	06/19/1986
From:	Marshall B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Kregloe W VIRGINIA, COMMONWEALTH OF
References
NUDOCS 8606250386
Download: ML20206G615 (2)

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VIRGINIA POWEft June 19, 1986 Mr. William L. Kregloe State Water Control Board Valley Regional Office 116 North Main Street P. O. Box 268 Bridgewater, Virginia 22812 North Anna Power Station - Unusual Discharge

Dear Mr. Kregloe:

This is to confirm the report made to you on Monday, June 16 of an unusual discharge to North Anna i.ake. The discharge originated from the primary equalization tank of the main sewage treatment plant at our North Anna Power Station.

At approximately 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br />, station personnel observed overflow from a manhole proceeding to a storm drain. On investigation it was found that the equalization tank pump had tripped off line causing the level in the tank to rise exerting back pressure on the main sewage line from the station. This caused a backup to the manhole and resulted in flow to the storm drain.

Drainage from this source flows to a 1500 gallon catchbasin which discharges to the lake. The catchbasin was known to contain at least 1400 gallons of stormwater runoff at the time of this incident.

It was determined that the overflow occurred for approximately one hour. It is estimated that no more than 50 gallons of raw sewage reached the catch basin where it underwent considerable (crl:30) dilution before being discharged to the lake.

Upon discovery the equalization pump was restarted, lowering the level in the tank and stopping the overflow. The catch basin was pumped and cleaned to prevent further discharge.

A condition of "no flow" was observed by the operator over the weekend but the implications of that condition were not understood. This lack of experience can be overcome with additional training and should prevent recurrence of such an incident.

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Mr. William L. Kregloe l Page No. 2 June 19, 1986 l

Should you have further questions regarding this incident, please don't hesitate to contact this office.

Sincerely, c d,,...-.L C7. n B. M. Marshall Manager Water Quality GRK/yo cc: Dr. J. Nelson Grace Mr. Harold R. Denton Mr. M. W. Branch 0591020GRK3070 l

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