ML20091L030

NPDES Noncompliance Notification:On 911216,sample Analysis of Fecal Coliform Indicated Concentration Greater than 1600 mpn/100 Ml Sample,Exceeding Limit.Caused by Sodium Hypochlorite Pump Problems.Chlorine Concentration Increased

ML20091L030
Person / Time
Site:	Calvert Cliffs
Issue date:	12/23/1991
From:	Szymkowiak J BALTIMORE GAS & ELECTRIC CO.
To:	Carlotta Coates MARYLAND, STATE OF
Shared Package
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References
NUDOCS 9201270211
Download: ML20091L030 (2)

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B Al.TIMORE '

OASAND RLECTRIC CHARLES CENTER

• P,0. BOX 1475 e BALTIMORE. MARYLAND 21203 1475

" " i N..,aUn.bN,mY,akkY,.'iN.N w m. m December 23,1991 i

l Carol J. Coates Maryland Department of Environment 2500 Broenin Highway Baltimore, M land 21224 i

Dear Ms. Coates:

RE: Maryland State Discharge Permit No. 86.DP 0187 and NPDES Permit No.

MD0002399, Monitoring Point 101. _,

' On December 16,1991,at approximately 0900, a sample for fecal coliform analysis was 1~

taken from Calvert Cliffs Nuclear Power Plent Gewage Treatment Plant offluent. The sample analysis int ilcated a fecal coliform concentration of > 1000 MPN/100 mi sample which in greater than the daily maximum limit of 400 MPN/100 ml sample. 1 The cause of this event was investigated and the failure for this eventi . y be traced to several possible plant evolutions:

1._ The high fecal coliform concentration occured during a normally low flow period when the sodium hypochlorite pump could have been adjusted to a minimal flow tale. Also, this sample was taken during a week when substituto plant operators

were on duty.

L 2.- ~ On Monday mornings, sewago is transferred from other locations on site to a l

tank truck and then delivered to the plant wetwoll. if sewago is dischargod too quickly into the wetwell, plant hydraulic overloading (temporary high flows) can occur.

3. _ A leak was found in the sodium hypochlorite tank line which may lead an i

operator to believe that the tank level changes indicate proper effluent i

I disinfection. The proper. amount of disinfectant may not of been delivered to the L chlorine contact chamber.

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4. The plant flow recorder had been found to be indicating a dischargo rate 5000 to 7000 GPD lower than the flow integrator. This may result in a lower demand L signal at the hypochlorite pump speed controller.

9001270211-920116 7

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Ms. Coates Docomber 23,1991 Page 2 Soveral steps have boon taken to provent recurrence of this type of noncompliance:

1. The STP affluunt will be sampled on Mondays and Thursdays to soo if flow serturbations during the weekends and/or the sewage transfer on Mondays may as affecting Monday's local coliform samplo,

2. The residual chlorine concentration in the contact chamber has boon increased from 2 3 PPM to 4 5 PPM. The dochlorination food flow rato has boon increased accordingly,

3. The discharge rato of sowage from the tank truck to the wot well will be decreased to prevent possiblo plant hydraulle overloads.

4. Identified chlorino piping leaks will be ropatrod.

5. The flow recordor has boon adjusted to agree with the flow integrator.

6. The Maryland Environmental Servico will be requestod to provido remedial training to tholt substituto plant personnel as nocessary.

No impact upon the receiving water would be observed from this type of event. The effluent of the Sewago Treatment Plant is normally dilutra with bay water at a minimum rate of at 1.0 million gal!ons por minuto. All other analysos taken at the same timo as those samples woro within NPDES limits. The duration of this noncomplianco is not known.

Sincerely, 4O drvid James A. Szymkowiak Chemical Analyst cc: Nuclear Regulatory Commission

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