Wenatchee outlines Pershing Street stormwater retrofit; Ecology grant covers 85%

WENATCHEE, Wash. — City of Wenatchee staff on Aug. 22 described plans for a Pershing Street stormwater retrofit that would add underground infiltration trenches, replace aging water main pipe and route treated runoff to a 42-inch storm main at Maple Street.

The project, identified as city project 2104, is funded primarily by a Washington Department of Ecology grant that will cover 85% of construction costs; the city will pay the remaining 15% from stormwater utility rates, Utility Project Manager Darcy Ronning said. "We're very grateful for those projects," she said of the Ecology funding.

City staff told neighborhood attendees the work will treat runoff from the roughly 55-acre Pershing Street basin before it reaches the Columbia River and the neighborhood's No. 1 canyon drain. Engineers plan about 2,000 linear feet of new pipe and a series of best-management practices, with infiltration trenches as the primary treatment method. Ronning said the city designs for a 10-year storm event, "which is approximately a 100 cubic feet per second at urban stormwater." The retrofit also includes replacing a 1956 cast-iron water main with new ductile iron…