The Ballard NDS 2015 Project would design and construct infiltrating raingardens (bioretention cells) along up to 22 city blocks. Those raingardens would be located primarily in existing planting strip areas within City street rights-of-way. Existing planting strips would be converted from landscaped, lawn, or impervious areas to vegetated bioretention cells and upland planting areas.

The raingardens would be designed to receive stormwater that currently flows in roadway gutters to combined sewer inlets. The raingardens would include bioretention soil to provide water quality treatment. Inlet curb cuts would be installed to route stormwater flow from the roadway gutter to the raingardens. Outlet curb cuts would be installed on the downstream end of the raingardens to allow conveyance of excess flows (during high flow events) via roadway gutter to the nearest down-gradient existing combined sewer inlet.

The project would include two general types of raingarden designs: 1) Planting Strip Raingardens and 2) Curb Bulb-out Planting Strip Raingardens. The curb bulb-out design typically would be used for traffic calming and improved pedestrian and bicyclist sightlines at select locations. At the Loyal Heights Elementary school, bulb-outs also would shorten the crossing distances across Northwest 80th Street and Northwest 77th Street, a priority identified as part of SDOT’s Safe Routes to School program. Mid-block bulbouts are also planned along Northwest 75th Street to provide additional raingarden infiltration area and to provide traffic-calming benefits to the neighborhood.

All raingardens would be located to avoid existing driveways, historic/significant trees (if any), hydrants, and utilities where possible. All raingardens would have a vertical wall on the sidewalk side, a flat bottom, and a side slope (2.5 horizontal: 1 vertical) on the road side. Only the Planting Strip Raingarden would incorporate a passenger loading (parking egress) area.

Where feasible based on utilities and geotechnical analyses, “pit drains” would be installed under the raingardens to enhance vertical infiltration of stormwater runoff. Pit drains are shallow, vertical drains (between 10 to 15 feet deep) constructed by digging a hole through naturally layered or interbedded sediments and then backfilling the excavation with free-draining materials such as pea gravel.

In addition, the project would construct pedestrian and safety improvements such as curb ramps where required, at up to 15 intersections adjacent to the raingardens. Certain utilities such as side sewers and natural gas mains may need to be relocated or replaced during construction. The project would opportunistically demolish an undetermined area of impervious surfaces and replace those surfaces with pervious surfaces such as turf.

Proponent

Seattle Public Utilities
Seattle Municipal Tower Suite 4900
P.O. Box 34018
Seattle, WA 98124-4018

Location of Proposal

This project is located within the Ballard neighborhood of the City of Seattle, King County, Washington, and is located entirely within improved City-owned street rights-of-way. The project is located within Section 2, Township 25N and Range 3E. The project would construct infiltrating roadside raingardens along up to 22 blocks. (One block is equal to 330 feet.) Raingardens may be constructed on the following blocks:

• 17th Avenue Northwest: 7700, 7800, 7900, 8000, 8100, and 8200 blocks
• 19th Avenue Northwest: 7500 and 7600 blocks
• 25th Avenue Northwest: 8000, 8100, and 8200 blocks
• 26th Avenue Northwest: 7700, 7800, 7900, 8000, 8100, and 8200 blocks
• Northwest 75th Street: 1700, 1800, 2000, 2100, 2200, and 2300 blocks
• Northwest 77th Street: 1700, 1800, and 2500 blocks

The project may also construct intersection improvements (such as curb ramps) at one or more of the following 15 intersections:

• Northwest 75th Street and 17th, 18th, 19th, 20th, 21st, 22nd, 23rd, and
Jones Avenue Northwest
• Northwest 77th Street and 17th, 18th, 25th, and 26th Avenues Northwest
• Northwest 80th Street and 17th, 25th, and 26th Avenues Northwest

Neither the specific intersection improvements nor the number, locations, and design of raingardens have been finalized at the time this Environmental Checklist was prepared.

Lead Agency

Seattle Public Utilities, the lead agency for this proposal, has determined that it does not have a probable significant adverse impact on the environment. An environmental impact statement (EIS) is not required under RCW 43.21C.030(2)(c). This decision was made after review of a completed environmental checklist and other information on file with the lead agency. This information is available to the public on request.

This Determination of Non-Significance (DNS) is issued under WAC 197-11-340(2); the lead agency will not act on this proposal for fourteen (14) days from the date below.

A copy of the environmental checklist is available at:

• Seattle Public Utilities, Director’s Office Main Reception Area, Seattle Municipal Tower,
Suite 4900, 700 Fifth Avenue, Seattle, Washington

• Seattle Central Library, Public Review Documents, Level 5 Reference

• www.seattle.gov/cso/ballard

Public and Agency Comments

Comments must be submitted by December 4, 2014 and must be sent to:

Betty Meyer, SEPA Responsible Official
Seattle Public Utilities
Seattle Municipal Tower, Suite 4900
P.O. Box 34018
Seattle, WA 98124-4018
betty.meyer@seattle.gov

Appeals

Appeals of this DNS must be accompanied by an $85.00 filing fee and must be filed by 5:00 p.m. on December 11, 2014. Delivery of appeals filed by any form of USPS mail service may be delayed by several days. Allow extra time if mailing an appeal.

· Written appeals must be sent to:

City of Seattle Hearing Examiner
700 5th Avenue Suite 4000
P.O. Box 94729
Seattle, WA 98124-4729

· Appeals can be filed electronically. Details on electronic filing procedures are available
under “e-File” at the Office of the Hearing Examiner’s web site:
http://www.seattle.gov/examiner/

· Filing fees must be paid by the appeal deadline and can be paid via check (made payable
to the City of Seattle) or credit/debit card (Visa and MasterCard only).
Credit/debit card payments can be made in-person or over-the-phone.

You should be prepared to make specific factual objections. Please refer to the Hearing Examiner Rules of Practice and Procedure for rules that govern appeals. These rules are available on the Hearing Examiner’s website at www.seattle.gov/examiner/rules-toc.htm or by calling 206-684-0521.