The city of Sammamish hosted its second stormwater open house on Sept. 21 at Sammamish City Hall.

Tawni Dalziel, senior stormwater program manager, provided a progress report of where the city was regarding adoption of the surface water design manual and amendments to the low-impact development code. She also touched on feedback the stormwater management program had received from community members.

Dalziel reminded those in attendance the deadline for adopted updates to the surface water design manual was Dec. 31 of this year. She said the city needs to update the design manual to comply with stricter stormwater standards to improve water quality, reduce flooding and meet the state’s National Pollutant Discharge Elimination System (NPDES) requirements.

“We’re working very hard having these open houses, stakeholder meetings, meeting with the planning commission and the City Council … to get their arms around what we’re doing and trying to make the process as smooth as possible to meet this deadline,” she said.

The city held its first open house in July and is slated to have a public hearing with the Planning Commission on Oct. 6.

Dalziel explained the low-impact development code updates as “the principles and practices that mimic natural hydrological processes” regarding water runoff and precipitation absorbing into the ground.

“What we want to do with low-impact development are these three principles: reducing impervious surfaces, retaining native vegetation and reducing surface water that leaves the site,” she said.

Among the feedback the program received from the public, Dalziel said, was that stormwater ponds lacked visual appeal, that more tree retention and planting of native seeds was needed and that water quality needed to be further addressed.

To address NPDES requirements but also community concerns, Dalziel said the program formed a stakeholder committee made up of residents, developers and representatives from local environmental organizations.

One of the topics the group discussed was incentives for low-impact development principles.

“The city currently has a low-impact development code … that allows developers to provide some LID techniques and principles to get ‘technique points,'” Dalziel said. “If they get a certain number of points, they get incentives like increased density, like increased building heights, etc.”

Moving forward, Dalziel, city staff and the consultant team proposed amendments to the surface design manual and the SMC code. The key proposed amendments included:

• The requirement of low-impact development best management practices for all new and replaced impervious surfaces.

• Drainage review would be required in areas that drain to landslide hazard areas.

• Add landscaping requirements to storm water ponds.

• Propose recreation credit for storm ponds and vaults that comply with improved requirements.

• Create a graduated scale of the points toward incentives for low-impact development techniques.