HomeMy WebLinkAboutUtilities 2013-01-22 Item 2C - Update - East Marginal Way South Emergency Storm Pipe RepairCity of Tukwila
Jim Haggerton, Mayor
INFORMATIONAL MEMORANDUM
TO: Mayor Haggerton
Utilities Committee
FROM: Bob Giberson, Public Works Director
BY: Ryan Larson, Senior Engineer
DATE: January 18, 2013
SUBJECT: EMWS Emergency Storm Pipe Repair 11 -19 -12
Project No. 91241206
Project Status
ISSUE
Status update on the East Marginal Way South (EMWS) Emergency Storm Pipe Repair 11 -19 -12 Project.
BACKGROUND
On November 19, 2012, a large sinkhole was created after there was a break in a 30 -inch storm water line on EMWS, just
south of S 124th St. The pipe conveys storm water flows from the east fork of Riverton Creek, as well as local drainage in the
area near Group Health. The City Council declared an emergency per Resolution No. 1783 and Goodfellow Brothers was hired
to complete a temporary emergency repair of the failed pipe and fill the sinkhole.
In the following days, it was observed that a blockage had formed in a storm pipe just upstream of the break. City crews
investigated and found that the trash rack on the pipe was missing and that a significant amount of debris had become lodged
within the pipe. Crews removed firewood and other debris from the pipe, but were unable to completely clear it. Given the
significant damage that may have resulted from additional flooding, Green River Construction was hired on November 22, 2012
to dig up the pipe, cut a window in it, and remove the debris. All work was coordinated with the Washington State Department
of Fish and Wildlife (WDFW).
ANALYSIS
Staff has researched the EMWS pipe system and determined that it is made up of sections of 30" corrugated metal (CMP) and
36" concrete pipe. It is believed that the concrete sections were installed at a later time than the CMP and represent sections
that were improved by the County prior to annexation. City crews performed limited video inspections of the pipe and
determined that the pipe is in imminent danger of failure and repairs are needed within the CMP sections. A complete
inspection of the pipe was not completed due to standing water and sediment within the pipe.
Prior to recommending repair options, a complete video inspection will need to be performed. This will require pipe dewatering
and limited cleaning so that a camera can pass between catch basins. The complete video inspection will help determine which
specific sections need improvements.
The EMWS storm pipe conveys Riverton Creek, which is a fish bearing stream and all work is subject to WDFW review and
approval. Initial discussions with WDFW indicate that providing fish passage may not be required due to the overall pipe system
length. If the WDFW does not require fish passage of the repair sections, it is recommended that the City still consider
improvements for fish passage where feasible.
FISCAL IMPACT
A total of $61,992.94 has been spent to date on temporary repairs and permitting. The expenditures were taken from the
remaining available funding within the 2012 Small Drainage Program. Future repair costs will come from the 2013 Annual
Drainage Program including $39,403.95 for a design study that is being presented tonight. Final design and construction costs
are unknown at this time and will be forthcoming.
RECOMMENDATION
Information only.
Attachments. Vicinity Map
W;iPW EngsPROJECTS\A- DR Projects,EMW Emergency Storm Rpe Repar 11-19-12191241206 .info Memo Update UC 1 -22 -13 gl.docx
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East Marginal Way Pipe Locaton Map
EMWS Pipe Location