A major drainage improvement project on South Hill will be officially completed Monday, March 18 when a $5.5 million stormwater pump station and related improvements are dedicated.
The public is invited to attend the ribbon-cutting ceremony at 3:30 p.m. at the Hemlock Stormwater Pump Station,11919 144th St. E.
Residents in the vicinity of the Hemlock ponds near 144th Street and 122nd Avenue East experienced significant flooding on their properties during 1995-97 when winter storms produced exceptionally heavy rainfall.
Stormwater also covered roads, including arterials, resulting in a form of traffic gridlock.
The county responded with an improvement program financed by the surface water management fees that residents pay with their property taxes each year.
The drainage improvements will serve a 2.5 square mile area with an estimated 12,000 population.
“This portion of South Hill includes a closed-depression drainage basin which causes stormwater to flow to a series of natural ponds and potholes,” said Tim Ramsaur, the county’s Water Programs manager.
“There is no natural outlet for this water. Some escapes by evaporation and infiltration, but pumping is the only way to move large volumes of stormwater out of the area.”
The 2,800-square-foot, concrete-and-steel station houses three pumps, each with 7,000 gallons per minute capacity.
This winter the fully automatic station pumped 10 million gallons of water, enough to fill a 20-foot-high tank the size of a football field.
“The $5.2 million for the pump station represents the largest expenditure of surface water management funds for a capital project. The result is a state-of-the-art facility that will prevent a reoccurrence of the serious flooding experienced by the community in recent years,” said District 2 Councilmember Calvin Goings of South Hill.
Besides the pump station, the improvements included pipelines that carry water from several ponds and potholes to the Hemlock ponds, box culverts connecting several ponds and a 42-inch force main that carries water from the Hemlock ponds to the City of Tacoma’s McMillin Reservoir spillway line.
The spillway line carries the excess water off the hill to the Puyallup River at a point between Sumner and Orting.
“We owe the City of Tacoma a debt of gratitude for allowing us to use the spillway line. Their cooperation saved us at least $500,000,” Ramsaur said.
County Executive John W. Ladenburg and Councilmember Goings will be on hand for the dedication event.
Mid-Mountain Contractors Inc., Kirkland, was general contractor. Also involved were URS Corp., Seattle, design services, and Entranco Inc., Bellevue, construction services.