Adding more permeable surfaces in the center of Bend could save millions of dollars and eliminate flooding problems like the one that closed the Franklin underpass for several hours Friday, an engineer said.

The underpass closed for several hours in the middle of the day as city employees vacuumed water that accumulated because of steady rainfall. That kind of flooding would be less common if the city invested in stormwater and street improvements in the Bend Central District, a 206-acre area that extends south from Revere Avenue to railroad tracks between the parkway and Fourth Street, said Jim Lord, a principal engineer at Ashley & Vance in Bend.

“When it rains, all that water races down the street and ends up in a low point, which happens to be the Franklin and Greenwood underpasses,” Lord said.

Lord’s office is on Franklin Avenue just west of the underpass, and he said he could see at least 2 feet of water building up on the road. It was the first time he’d seen flooding bad enough to close the street since he started working there three years ago, but flooding of the underpasses is an age-old problem in Bend.

Major improvement projects to address flooding at both underpasses are included in Bend’s capital improvement plan, but they’re not scheduled. A third railroad underpass on Third Street that frequently flooded was improved by adding planters and swales — ditches that collect rainwater — and pumping excess water to a nearby stormwater pond.

The Bend Central District is mainly covered by asphalt and roofs, Lord said. A lack of green space leads to more runoff, and older stormwater infrastructure can’t handle heavy, steady rainfall.

Supporters of urban renewal in the Bend Central District — a process that allows the city to pay for improvements in an area with expected increases in tax revenue once the improvements are complete — say improving streets and stormwater infrastructure in the district at the same time will help with flooding at the underpasses. Reducing the amount of hard surfaces by 10 percent to 15 percent would be a big help, Lord said.

“By improving the streetscape, we could save the city $1 million,” he said.

Bend Public Works Director Paul Rheault said it’s been a while since either underpass flooded. On Friday, the city called in employees who were on vacation to help with vacuuming up water at the underpasses. Crews used vehicles that can suck up large amounts of water and transport it away.

“The two normal spots whenever we have significant rainfall are Franklin and Greenwood,” Rheault said.

Rheault said stormwater improvements near the underpasses are a lower priority compared to some sewer infrastructure because Bend rarely gets enough rain to flood.

Instead, the city frequently clears debris out of storm drains, he said. But when enough rain falls, it can overwhelm even clean storm drains.

Along with flooding at the Franklin underpass, there was reported flooding on Wall Street downtown, with water up to the doorway of the Paper Jazz gift shop at 858 NW Wall St., said Bend Police Lt. Clint Burleigh, a department spokesman. That flooding appeared to be caused by a clogged drain and downtown remained passable, Burleigh said.

A monitoring station southeast of Bend reported about three-tenths of an inch of rain, with most of it falling between 9:30 and 10:50 a.m., said John Peck, a forecaster with the National Weather Service.

— Reporter: 541-633-2160; jshumway@bendbulletin.com

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