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Preparation and Response Plan for Green River Flooding

Nov. 2009 – Spring 2010

Date of Plan: September 9, 2009

Background: The Army Corps of Engineers (Corps) and the King County Flood Control District has warned residents, businesses and farms below the Howard Hanson Dam to prepare now for a higher risk of flooding.

The higher risk is due to water seeping more rapidly through the earthen bank next to the dam after record high water last winter. Until the Corps can make repairs, it will limit the amount of flood water it stores behind the dam. The restricted flood storage means if heavy and prolonged rain occurs this flood season, many homes, businesses and agricultural lands in the Green River valley that don’t typically flood could be flooded by several feet of water. The Green River may have flows greater than 12,000 cfs for the first time since the dam and levees were built in the 1960’s. The high flows could cause flooding in four ways, either singly or in combination: overtopping of the levees, weakening of the levees due to saturation and water level fluctuation, catastrophic levee breach or failure, and levee breach or overtopping due to debris damage.

Areas that could be flooded include parts of Auburn, Kent, Renton, South Seattle and Tukwila.

The US Army Corps of Engineers has kept all of cities in the Green River valley and King County well informed about the situation at the dam. The local jurisdictions have formed the Howard Hanson Dam Planning Group. The planning group has devised an Operation Action Plan (OAP) based on Incident Command System (ICS) organization. The purpose is to coordinate planning for a potential flood; it will not respond during an actual flood event. During a flood event, the State Emergency Management will coordinate response, as will King County Department of Emergency Management.

See a copy of the Organization Chart for the Operation Action Plan below.

Jurisdictions involved in local planning:

• King County is the lead in emergency management.
• City of Tukwila
• City of Kent
• City of Auburn
• City of Renton
• US Army Corps of Engineers
• Public Health of Seattle and King County
• State of Washington Emergency Management
• State of Washington Department of Ecology

Department of Ecology: Summary of Key Actions

Mapping: Ecology has mapped locations of underground tanks and hazardous waste sites in Green River valley and shared these with other agencies.	Cleanup crews: Ecology’s Spill Response Program can deploy WCC crews able to assist with cleanup efforts.	Helicopter overflights: Ecology’s Spill Response Program arranges for helicopter overflights to photograph flooded areas to locate sheens, oil spills, and visible hazardous releases.
Interagency coordination: Ecology staff are participating in two of the County’s emergency preparedness work groups: the Hazardous Materials Task Force and the Environmental Unit of the Planning Section.	Site inspections: Inspectors will visit hazardous waste sites before flooding, and inspect underground storage tanks after flooding.	Information for tank owners: Ecology’s Toxics Cleanup Program tank unit developed and distributed information sheets for underground storage tank owners.

General Ecology Flood Information

The Department of Ecology has a website with general information on flooding: http://www.ecy.wa.gov/programs/sea/floods/index.html

Ecology involvement by program:

Note: Changes and updates to this plan may occur as needed. Coordination with other agencies is continuing.

Water Quality Program:

• Wastewater treatment plant technical assistance: All of the wastewater in the Green River valley goes to King County’s South Wastewater Treatment plant (WWTP) in Renton. The service area of the treatment plant also includes many other jurisdictions (Bellevue, Issaquah, and Redmond). The sewer lines are not combined with stormwater. In a flood event, flood water could enter the separate sanitary sewer system through manholes. It is believed that individual residents and businesses may remove the manhole lids to relieve the street flooding, which would inundate the South WWTP. Bypassing of treatment units at the plant could be necessary and result in effluent limit violations. The plant has a plan for emergency operations, and Ecology will be meeting with staff from the treatment plant (September 15) to learn more about their emergency preparedness. Ecology’s facility manager can provide technical assistance and guidance to the plant.
• Water sampling: Ecology’s Water Quality Program does not collect or test floodwater samples during flood events but King County will be sampling their WWTP influent and effluent on a routine basis. Note: If industrial waste permittees cannot discharge to the sewer system during a flood event, many businesses will be impacted, including those not located in the Green River valley.

Toxics Cleanup Program:

• Underground Storage Tanks: Ecology staff from the Underground Storage Tank unit (Cathie Richardson) has been attending King County’s Hazardous Materials Task Force meetings. Ecology has provided both a list and a map of potential UST/LUST sites that are within 250 feet of the 100-year floodplain. There are approximately 40 sites.
• Information for storage tank owners: Ecology has 3 Focus sheets to disseminate information on how to properly manage underground storage tanks before, during, and after a flood. The informational sheets are:
  • Focus on Flooding: Evaluating Your Underground Storage Tank System Before Restart
  • Focus on Instructions for Service Providers: Underground Storage Tank System Restart After Flooding
  • Focus on Flooding Prevention: Flood Prevention for Underground Storage Fuel Tanks in the Green River Valley
• Distribution of information sheets: Ecology will mail the Focus sheets to sites within the flood zone in September. They are available on Ecology’s web page. Additionally, King County will put a summary and link in an e-mail bulletin.
• Underground tank inspections: Ecology will inspect tank sites after flooding occurs.
• Cleanup sites: A GIS map with locations of cleanup sites in the Green R. valley is available and has been provided to King County.

Hazardous Waste and Toxics Reduction (HWTR) Program:

• Expert contact: Dave Misko is the point of contact for HWTR Program for flooding issues.
• Locations of hazardous waste sites: Ecology has provided an excel spreadsheet to King County’s with the locations of the hazardous waste sites, with type and quantity of waste generated. Info will be added to the tank GIS map. King County may also be generating a map.
• Information for business owners: King County Industrial Waste section has asked for Dave Misko’s input and review for message to business owners. It is important that businesses that discharge industrial waste to the sewer system that goes to the South Treatment Plant in Renton understand that they may be affected by the flooding even if they are not inundated, if the treatment plant is not able to accept the waste.
• Site visits planned: Ecology is planning to conduct site visits in October to hazardous waste generators in the Green River valley to convey information on how to prepare for flooding.
• Information on Internet: HWTR program is looking into taking information developed during Lewis Co. flood, tailoring it for Green R. flooding and providing that information on the internet.

Spill Prevention, Preparedness and Response (SPPR) Program and Shorelands and Environmental Assistance Program (SEA):

• Expert contact: Dick Walker of Ecology’s SPPR Program is a member of the Environmental Unit in the Planning Section of the Operation Action Plan.
• Interagency planning: The Environmental Unit is making a plan to address environmental health issues before, during, and after flooding. So far they have developed information and messages for residents and businesses in the Green River valley.
• Helicopter reconnaissance: After a flood, Ecology’s SPPR Program can arrange for helicopter overflights to photograph the flooded area. This helps to locate and identify oil spills and sheens, above-ground tanks, and other areas that may need cleanup assistance to protect from hazardous materials.
• Cleanup crews: Ecology’s SPPR Program can request assistance from Ecology’s Washington Conservation Corps (WCC) crews from the SEA Program. The crews are Hazwoper trained and can assist with cleanup efforts.

Shorelands and Environmental Assistance (SEA) Program:

• Expert contact: Chuck Steele is Ecology’s flood program contact person for the Green River valley.
• Flood insurance: Ecology (Chuck Steele) works closely with FEMA to encourage participation by communities in the National Flood Insurance Program’s Community Rating System (CRS). The City of Auburn participates in CRS, so residents in the City receive a 25% reduction in their flood insurance premiums.
• Long term studies: Legislative mandates are funding two efforts related to long-term levee maintenance.
  • The legislature appropriated $10 million for the City of Kent to address levees in the Horseshoe Bend area on the Green River. More than $ 5 million will be for property acquisition and setback levees. Ecology is the grant manager and is working with the City of Kent on a contract.
  • A Flood Protection Study was funded in the last legislative session. Ecology will research the levee certification process, identify which levees are certified and which are not certified, and point out the long term implications. The Green River levees are a high priority. Ecology will deliver a report to the legislature in June 2010.

Water Resources:

• Water Right and Availability Related Actions: Ecology can work with jurisdictions if situations arise from the flood scenario that may involve a water right or emergency approval. For example, the City of Kent requested and received a temporary water use authorization from Ecology earlier this summer to use Green River water to fill “aqua dams” to elevate several miles of levees in advance of a major flood. (To note: The City subsequently determined this is not the approach they would be taking.)
• Drinking Water: Water Resources Program does not regulate or monitor drinking water quality.
• Dam Safety: Ecology does not inspect federal dams in Washington State and has no regulatory role in the operation or maintenance of the Howard Hanson Dam. As a courtesy, the Corps is keeping Ecology informed of its efforts to repair the seepage problem and also has involved Ecology’s dam inspectors in table top exercises dealing with flooding scenarios during the rainy season this winter.

Contacts at Department of Ecology:

Jeannie Summerhays, Regional Director   425-649-7010

Alice Kelly, Regional Planner   425-649-7128

Dick Walker, Spill Response   425-649-7116

Chuck Steele, Flood Program   425-649-7139

Mark Henley, Water Quality   425-649-7103

Andy Dunn, Water Resources   425-649-7270

Dave Misko, Hazardous Waste   425-649-7014

John Wietfeld, Underground Storage Tanks   425-649-7282

Rob Spath, Washington Conservation Corps   360-407-6936

Doug Johnson, Dam Safety   360-407-6623