HomeMy WebLinkAbout2014-06-09 ROCK CREEK LIFT STATION OVERFLOW LETTER CITY OF
TWW FALLS
41
SERVING
P.O. Box 1907 324 Hansen Street East Twin Falls,Idaho 83303-1907 Fax: (208)736-2293
ENGINEERING 208-735-7265
June 9, 2014
Director, Office of Compliance and Enforcement
US EPA, Region 10
Attn: ICI Data Entry team, OCE-133
1200 Sixth Ave., Suite 900
Seattle, WA 98101-3140
Re: NATIONAL POLLUTION DISCHARGE ELIMINATION SYSTEM PERMIT NUMBER
ID-002127-0
To: Director, Office of Compliance and Enforcement;
Pursuant to Section III Part G.2 of National Pollutant Discharge Elimination System(NPDES) Permit
ID-002127-0, the City of Twin Falls (City) is required to submit a report in writing within five (5)
days from the time the City became aware of the event.
On June 4, 2014, between 11:20 AM to 11:50 AM the City's Rock Creek lift station experienced an
overflow event. It is estimated that approximately 50,000 gallons overflowed from the lift station and
discharged to the ground. Some of the discharge filtered through a neighboring pasture on the west
side of the Rock Creek lift station site. A large portion of the discharge was retained in the pasture, and
this went subsurface within a matter of a few hours after the event. Of the 50,000 gallons that
overflowed, the City approximates that less than 5,000 gallons actually reached and discharged into
Rock Creek. The discharge, once being filtered through the pasture, was again filtered through the
riparian vegetation along Rock Creek.
City personnel responded quickly and returned the Rock Creek lift station to proper operation within
30 minutes of being notified.
The City notified the Idaho Department of Envionmental Quality (IDEA) after arriving on site, and
IDEQ personnel came and investigated the overflow event. No water quality samples were taken in
Rock Creek as the event had already transpired and the fast flowing stream have mixed the discharge
rather quickly. IDEQ continued their investigation the same day and into the next two days; and later
contacted the City to notify them that no fish kill was observed in Rock Creek down stream of the lift
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station. DEQ also ascertained that there was no evidence of recreationists swimning in the stream or
in the Rock Creek Park area, which is immediately downstream of where the discharge occurred.
The City initially thought that a power bump during its weekly scheduled standby generator test
caused the lift station to lose power. After further investigation the City had not lost the power feed to
the facility as initially thought. Through the troubleshooting process, it was discovered that the 480
voltage breaker that feeds the 120/240 volt transformer had tripped. The 120/240 volt transformer
powers the programmable logic controller (PLC) that operates the lift station pumps.
After resetting the 480 volt electrical breaker the Rock Creek lift station was returned to proper
operation. At this time the City does not know exactly why the 480 volt electrial breaker tripped.
However, the City is continuting to have their electricians perform tests to try and determine a cause
and prevent recurrence of this situation.
If you have any question regarding this event please contact Jason Brown at (208) 735-7272 or by
email at ibrown@tfid.org.
Sincerely,
Jacqueline D. Fields
City of Twin Falls
City Engineer
JHB/
cc: Dave Anderson/IDEQ
Balthasar B. Buhidar/IDEA
Jon Caton/City of Twin Falls
Shawn Moffitt/CH2M Hill
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