Terminal 18 Stormwater Outfall
Renewal and Replacement
Marine Stormwater Utility
Date: February 13, 2018
Item No.: 8b
Highlights
• Marine Stormwater Utility formed in 2014 to protect water quality of the Puget
Sound
– Won AAPA Comprehensive Environmental Management Award
– Tenant fees about 15% lower compared to City’s Utility fees
• System assessment & rehabilitation
– Obtain baseline conditions of entire system, due to be completed end of 2019
– A dozen urgent repairs completed preventing safety & operational hazard
• Investments in the stormwater system
– Green Stormwater Infrastructure such as oyster shell barrels & rain garden
– Installation of tide gates
• Tenants expressed positive feedback on our efforts
Highlights of work accomplished
2
Utility Revenue & Goals
Utility Revenue Breakdown
NWSA
NWSA tenants
Port
Port tenants
Provide triple bottom line benefits
3
• Assess all 78 miles of
infrastructure by 2019
• Invest in asset
rehabilitation to
improve water quality
• Collected $4.96 million in
2017, $5.33 million in 2018
Terminal 18 Stormwater
• Drainage area roughly 175 acres
(nearly 9 Safeco Fields)
• Most site drainage enters Duwamish
East Waterway through 13 Port-
owned outfalls
• Outfalls were installed ~50 years ago
Largest active container terminal
4
T-18 Stormwater System
East Waterway Outfall Locations
5
Existing Outfall Conditions
Visible conditions under the dock
6
Broken Pipes
Ponded water in the pipes
Missing tide gates
Current Assessment / Scope of Work
• Focus from last manhole to end of pipe
• Repair broken and cracked pipe
• Realign pipe grade or slope
• Install new tide gate valves
Current Conditions and Repair
7
New tide gate installation
Project Schedule
• Commission Authorizations
– Design & partial construction authorization - Q2 2017
– Full Construction authorization - Q1 2018
• Construction Activities
– Non-disruptive activities postponed until 2018
– Repair and replacement construction phased between
2018 and 2020
Schedule phased over 4 years
8
