POULSBO — The waterline serving Big Valley Road will be replaced with a larger pipe to replace the aging system in early June.

The City Council approved the construction bid at its May 8 meeting, awarding Pape & Sons from Gig Harbor the contract to do the project for $751,148. The total budget is $901,377.

The project will begin June 10 and will last 45 working days. Big Valley Road will be reduced to one lane, alternative traffic during construction.

The city is replacing the 8-inch, 50-year-old transmission main, covering 5,000 linear feet. Assistant Public Works Director Andrzej Kasiniak said the pipe is undersized, and the cast iron pipe with lead joins are more likely to leak.

The new line will be 12 inches wide. The line connects to two city-owned wells.

“In the wells we have pumps which pump the water from the wells to our water tanks,” Kasiniak said in an email. “The water tanks feed our water distribution system within the city limits.”

The project is expected to cost less than the engineering department’s estimate. The project was designed in-house, and the cost of construction is 13 percent lower than the city’s engineering estimate.

Kasiniak said the original budget was $1.06 million. The accepted budget also includes 10 percent for administrative costs, and a 10 percent contingency for weather or emergencies.

Kasiniak said the surplus, approximately $150,000, will be returned to the city’s water reserve budget.