Sewer beach main repairs to cost $7 million
May 5, 2011 · Updated 3:23 PM
The estimated price tag to rehabilitate the five corroded sewer pipes located along the Eagle Harbor shoreline totals more than $7 million, according to a consultant’s report presented to the council Wednesday.
“You’ve gone two years since the last failure, [but] can we go another two years?” said Craig Chambers, of BHC Consultants, hired to examine the beach mains. “It depends on how much of a gambler you are, but that’s the kind of notoriety that this city doesn’t need is to have sewage on its beaches. [The sewage main] is going to fail. We know that.”
The report recommends that there is an immediate need to tackle at least two of the five sewage mains – at State Route 305 and at Wing Point – with an estimated cost of $2 million before another failure occurs.
The city has $425,000 available in the form of a Public Works Trust Fund for a pre-construction loan to fund the design, engineering, environmental reviews, permits and bid development, which is about enough to cover the pre-construction phase for one of the beach main projects. No other funding mechanisms have been identified.
Two of the five segments, the pump stations at SR-305 and Wing Point, have already failed in recent years, and it’s uncertain how much longer the city can go before another raw sewer spill contaminates island beaches.
In a 2008 report commissioned to investigate earlier pipe failures in the Wing Point area, the Ductile Iron Pipe Research Association concluded that the shoreline sewer pipes were being corroded. The Eagle Harbor pipes were installed in the late 1970s; many without anti-corrosion measures in place. The ductile iron piping doesn’t do well in the salt-water and continues to corrode. Piping off Wing Point has worn the thickness of some pipes by 50 to 66 percent, according to the 2008 report.
In July 2009, the SR-305 sewer main ruptured and released an estimated 287,000 to 493,000 gallons of untreated sewage into the Harbor. The 12-inch pipe serves as a conduit for sewage from the downtown area west of SR-305, carrying about 50 percent of all incoming sewage into the treatment plant.
An additional failure of this line, depending on the breakage location, could disrupt ferry traffic and result in substantial volumes of sewage spilled on the beach, according to the report.
In order to combat the corrosion, the pipes need to be encased in polyethylene (HDPE), replaced with HDPE pipe or rerouted offshore. The consulting team also looked at the numerous construction options to replace the piping.
The consulting team recommended that the city tackle the SR-305 pipe problem with an open-cut construction method, which would run parallel to the footprint of the existing pipeline and use a backhoe or small excavator to trench around the surrounding pipe.
This solution would avoid impacting the integrity of the existing line, but it would cause the greatest disturbance to the wetland, wetland buffer and intertidal area. The process could get expensive, and time intensive if the city needs to move beyond the existing easements, which would require getting property owner approval, said Interim City Manager Brenda Bauer.
In concert with the SR-305 site, the study recommends fixing the 6-inch Wing Point pump station by inserting a new pipe inside the abandoned 16-inch diameter that previously served the treatment plant’s effluent force main.
Once those two projects are completed, the study recommends fixing: the WWTP effluence force main at a cost of approximately $2.5 million; the WWTP out fall extension for $1.1 million; and the Lovell pump station at a cost of $1.1 million.
“You are not the only community facing this,” said Chambers. “Bellevue and Mercer Island also have lines in beaches or lakes. Bellevue has 19 miles of pipe, which has been nothing but a nightmare.”
The estimates provided by the consultant allow for contingency, construction costs and sales tax, but depending on the method the council chooses there could be additional annual maintenance costs for the sewage system.
Any upgrades will be charged to the sewer utility, which serves roughly 2,100 to 2,200 customers. The utility is already strained due to costs associated with the WWTP upgrade, which required a $3 million loan from the water fund that is still outstanding.
Public Works Director Lance Newkirk recommended that the Utility Advisory Committee (UAC) investigate the options further and help prioritize the project and funding strategies.
“We think we have a very good project to score high for grant funds, which is certainly only one [funding] component,” said Newkirk. “We would like to have the UAC help wrestle with what is the appropriate strategy.”
Councilor Kim Brackett said she was troubled by not only the costs, but also the environmental message that will be sent to the community.
“It’s ironic to me that we have had a big discussion about a bulkhead, which potentially causes damage to the shoreline [at Rockaway], and now we are thinking about putting mains in the beach,” said Brackett. “It’s an inconsistent message on environmental standards.”
Waste water treatment plant update
The end of the waste water treatment plant (WWTP) construction is in sight. The project will total more than $14.7 million, according to city officials.
In 2005 the City Council approved the design of a $9.5 million WWTP upgrade to meet state and city regulations. At the time the total cost of the project, including the contingency was estimated at $14.7 million. The project was originally planned to be completed by February of 2010.
To date the project has spent about $14,741,321 according, to a city memo, and the anticipated project completion date is June 30.