By Kevin Hanson-The Courier-Herald

Years of planning, budgeting and dealing with state and federal agencies have largely been wrapped up, so the city of Enumclaw is ready to take the formal first step toward improving and expanding its wastewater treatment plant.

A groundbreaking ceremony is planned for 1 p.m. Tuesday to celebrate the beginning of construction on the plant - the largest project in city history. The public is invited to the festivities, planned for 451 Semanski St., or the northwest corner of the existing treatment plant.

City Administrator Mark Bauer said a handful of dignitaries will be invited, most notably those who helped with the funding process. Included will be members of the state Legislature, along with officials from King County, federal agencies and neighboring communities.

Expansion plans have been in the works for years, since the city learned its present treatment plant was failing to meet contemporary standards. Sewage treated at the plant is discharged into the White River and the fact that the river is a salmon-spawning waterway makes the situation especially dicey.

Outflow from the treatment plant was found to be contributing to river problems and led to a citywide moratorium in new developments, a situation that has stymied Enumclaw growth for years.

Bauer said the state's Department of Ecology first contacted the city in the mid-1990s, insisting that Enumclaw change its way of processing sewage. For most of the next decade, Bauer said, Ecology worked on explaining exactly what the city needed to do.

A suitable plan was arrived at and, in 2003, the city received a permit.

During that time, the cost of materials and labor has expanded considerably. The original price tag was in the neighborhood of $16 million and it has now grown to closer to $28 million.

The city has received a series of low-interest loans from the state to initially pay for construction and the City Council has already been raising utility rates to repay the loans.

Work on the plant expansion and upgrading is expected to take about a year. City officials are anticipating something of a building boom once the moratorium can be lifted.

Kevin Hanson can be reached at khanson@courierherald.com.