Stormwater Management and Planning—Seattle

Client: Vigor Shipyards
Evaluation, treatment design, mixing zone analysis, and construction oversight of improvements to stormwater infrastructure to for a central facility-wide stormwater treatment system at an active 27-acre shipyard on Harbor Island.

Overview of Floyd|Snider Contributions

Design lead for environmental and civil stormwater improvements
Stormwater treatment analysis
Successful agency negotiations
Site planning for active shipyard operations
Regulatory compliance

Project Summary

Vigor Shipyards (Vigor) operates a 27-acre shipyard on Harbor Island in Seattle, Washington, offering new construction and repair for mid-sized to large vessels and routinely services fishing vessels, ferries, barges, and military ships.

A portion of Vigor discharges stormwater to the West Waterway of the Duwamish River and Elliott Bay under the facility’s NPDES Individual Permit, and the other areas discharge stormwater to the King County sanitary sewer under a waste discharge authorization. As part of a habitat construction project and a requirement to discontinue discharge of industrial stormwater to the sanitary sewer, Vigor is completing stormwater infrastructure improvements to convey all industrial active areas of the shipyard to a central location for treatment at a new stormwater treatment system.

Vigor Shipyards (Vigor) operates a 27-acre shipyard on Harbor Island in Seattle, Washington, offering new construction and repair for mid-sized to large vessels and routinely services fishing vessels, ferries, barges, and military ships. A portion of Vigor discharges stormwater to the West Waterway of the Duwamish River and Elliott Bay under the facility’s NPDES Individual Permit, and the other areas discharge stormwater to the King County sanitary sewer under a waste discharge authorization. As part of a habitat construction project and a requirement to discontinue discharge of industrial stormwater to the sanitary sewer, Vigor is completing stormwater infrastructure improvements to convey all industrial active areas of the shipyard to a central location for treatment at a new stormwater treatment system.

Our Approach

Floyd|Snider has served as the lead consultant at the Vigor facility since 2000.

For the recent stormwater improvements, Floyd|Snider has led project efforts for treatment technology evaluations, a stormwater treatment system pilot test, mixing zone analysis, and development of a facility-wide stormwater engineering report. The stormwater improvements include retrofitting existing pump stations and detention tanks along with abandonment and reconveyance of stormwater infrastructure that currently discharges to the habitat restoration area. Stormwater will be conveyed to a central area for treatment by a chitosan-enhanced sand filtration system prior to discharge to the West Waterway and Elliott Bay. Floyd|Snider completed a mixing zone analysis to establish appropriate dilution factors for setting NPDES permit limits that will be protective of human health and the environment. Floyd|Snider is progressing the design of these stormwater improvements with construction completion in 2022.

Project Milestones:

2019–2020. Pilot test and treatment selection
2020. Mixing zone analysis and engineering report
2022. Stormwater improvement completion (projected)

Floyd|Snider has served as the lead consultant at the Vigor facility since 2000. For the recent stormwater improvements, Floyd|Snider has led project efforts for treatment technology evaluations, a stormwater treatment system pilot test, mixing zone analysis, and development of a facility-wide stormwater engineering report. The stormwater improvements include retrofitting existing pump stations and detention tanks along with abandonment and reconveyance of stormwater infrastructure that currently discharges to the habitat restoration area. Stormwater will be conveyed to a central area for treatment by a chitosan-enhanced sand filtration system prior to discharge to the West Waterway and Elliott Bay. Floyd|Snider completed a mixing zone analysis to establish appropriate dilution factors for setting NPDES permit limits that will be protective of human health and the environment. Floyd|Snider is progressing the design of these stormwater improvements with construction completion in 2022.

Project Milestones:

2019–2020. Pilot test and treatment selection
2020. Mixing zone analysis and engineering report
2022. Stormwater improvement completion (projected)

Project Team

Floyd|Snider
KPFF Consulting Engineers
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