ML20116H098

NPDES Noncompliance Notification:On 921006,found That Two Pumps in Sanitary Sewer Sys Manhole Electrically Tripped Off Due to Sewer Overflow.Pumps Reset.One Pump Retripped. Pump Remaining in Svc Brought Overflow Under Control

ML20116H098
Person / Time
Site:	Millstone
Issue date:	10/26/1992
From:	Chevalier R NORTHEAST UTILITIES SERVICE CO.
To:	Leavitt G CONNECTICUT, STATE OF
References
D05887, D5887, NUDOCS 9211120278
Download: ML20116H098 (2)

Text

---,

e. .

NORTHEAST UTILITIES o.n.,e On.c. . s.io.n sir t. e.,nn. Conn.cnevi 4 9 .' wi =: 4 , sa :'=< u=='

-a, .c.a ..'i n s x."co.'*** P.O. BCX 270 L t 3:Tj::'r,"";?;'.""~. HARTFORD. CONNECTICUT 06141-0270 (20m 665-5000 October 26, 1992 D05887 Mr. Gary leavitt, P.E.

Bureau of Water Management Department of Enviror. mental Prctection 122 Washington Street Hartford, CT 06106

Reference:

1. Letter (003156), R. A. Reckert to A. Freland, dated December 1, 1989.

2. Letter (001575), R. Reckert to R. Barlow, dated June 30, 1987.

Dear Mr. Leavitt:

Millstone Nuclear Power Station NPDES Permit No. CT00:'3263 Noncomoliance Report Northeast Utilities Service Company (NUSCO), on behalf of Northeast Nuclear Energy Company (NNECO) in a:cordance with Subsection (j)(ll)(D) of Section 22a-430-3, herein submits the following written report of noncompliance with NNECO's Millstone Nucle:r Power Station FPDES permit. The exceedance was reported to you by Mr. Edvard Keith of NUSCO by telephone on October 7, 1992.

Recort:

i At approximately 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br /> on October 6,1992, Millstone maintenance personnel were notified that a sanitary sewer system manhole / pump station near Unit 3 was overflowing and the effluer.t was dischargir.g to a storm drain. Upon arrival at the site, it was found that the two pumps in the manhole were electrically-7 tripped off. The system consists of duel a'ternating pumps such that if one pump l fails, the other pump activates. Both pe;a were reset; however, one immediately retripped. The pump that remain" in service brought the-sewage overflow under control. <

The effluent that overflowed had proceeded to' a storm drain which is located approximately 50 feet northeast of the Unit 2 intake structure. This storm drain, which outflows to Niantic Bay, although not in the current Hillstone permit, has been designated as DSN016 in the -permit rerewal application of December 1, 1989, Reference 1, on file with your office. Previous applicatinn for its inclusion in the permit had also been made cr. June 30, 1987, Reference 2.

g1129278921026 g ADOCK 050004g3 1 O

PDR OS3422 AEv 4 88  !

mm +" ~

s Mr. Gar'y leavitt, P.E.

D05887/Page 2 October 26, 1992 DSN016 is included in the renewal draft of Permit No. CT0003263 presently at public notice stage.

Conclusions:

Investigation of this incident revealed the pump that immediately retripped was clogged with a reg. It is felt the second pump tripped due to excessively heavy loading caused by the current Unit 2-steam generator replacement project and the malfunction of the other pump. Overficw of the manhole occurred for a total time of approximately one-half hour with a maximum estimated nyerflow volume of-300-500 gallons. 1h" repair team repu' ted the overflow was ralatively clear, contained no solid matter, and had very little odor. They- also reported the storm drain, which previously had oil absorbent " socks" or " pigs" placed around it for oil drip control during the overhaul . had no solids buildup around it.

Both oumps were returned to service the day of this incident.

Station personnel notified the Tri-Town Shellfish Commission's Chairman, Mr. John Noga, on October 7,1992, of this incident.

I Should you have any questions, please call Thomas Arcari, NUSCO Generation and i Environmental Licensing, at (203) 665-3713.

Very truly yours, NORTHEAST UTILITIES SERVICES COMPANY As Agent for Northeast' Nuclear Er:ergy Company s 1 <

R. G. ChdValier Vice President i

,