Green River Interim System-Wide Improvement Framework Mark Isaacson Division Director FCD Advisory Committee July 27, 2016 Department of Natural Resources and Parks Water and Land Resources Division River and Floodplain Management Section
Pr Present esentation ation Over ervi view w PL 84-99 Program and SWIF • Project Area and Context • Advisory Structure • Technical Studies Deficiency Action Plan Capital Plan Vegetation Plan Interim Risk Reduction Measures Funding and Implementation • Lower Russell Project Example
Wha hat t is a Sy a System em Wide de Imp mprov rovement ement Fram amework ork (SWIF) F)? USACE SWIF policy, November 2011: “A plan prepared by levee sponsors and approved by the USACE to implement system-wide improvements to a levee system (or multiple levee systems within a watershed) …” “… solutions will satisfy the multiple requirements that apply to levee systems (ESA, Tribal Treaty Rights, etc.) while allowing levee sponsors to remain eligible for PL84-99 funding while addressing deficiencies.”
1. Deficiency Action Plan to correct unacceptable or minimally acceptable deficiencies 2. Capital Plan to correct slope stability deficiencies that cannot be corrected through routine maintenance actions 3. Vegetation Plan to guide the design, maintenance and stewarship of shoreline vegetation on levees 4. Interim Risk Reduction Measures
Gre reen en Ri River er SWIF: F: Who ho is Inv nvolv olved? ed? • King County Flood Control District, lead agency • King County • Green River Cities • Muckleshoot Tribe • USACE, FEMA, NOAA • WRIA 9 • PSP, Ecology, WDFW • Business community • Environmental organizations • Citizens
Tec echn hnica ical l Stud tudies: es: Flood d Risk sk Assessm sessment nt • Geomorphic Assessment – channel patterns and gradient, stream incision, and damages to levees and revetments • Geotechnical Assessment – levee stability, vulnerability, and potential breach locations • Hydraulic Assessment – flooding patterns, channel capacity, and floodplain inundation (for flood flows of 12,000 to 26,800 cfs) • Economic Analysis – Expected annual damages and economic impacts Aq Aquatic, tic, Floodpla dplain, in, and nd Ripa parian rian Habitat tat • Riparian vegetation – trees, shrubs, invasive species • Aquatic Habitat – pools, large wood, edge habitat
Def efici iciency ency Actio tion n Pl Plan an Unacce ceptable ptable slo lope e stability bility 356 Deficiencies Across 11 Levees 1. Near-term actions: 2015-17 • Culvert CCTV, fence removal, flap gates/tide flex, 2. Mid-term actions to complete within 6-year CIP (2016-2021) 3. Long-term actions: capital projects • Capital plan – slope stability 4. Programmatic actions (ongoing) – vegetation and animal burrows 5. Monitoring actions (ongoing) – monitoring acceptable slope stability problems Anim imal al burrows
Types of Problems… Cul ulver erts ts – CCT CTV V an and Inspe pect/r t/rep eplace ce flap ap gat ates s an and Tidefl deflex Slope e stab ability ility – ran ange e from 1:1 to to 1.7:1 :1 slopes
…More Problems Levee vegetati tion on – trees s an and shrub ubs, s, rotting ting stumps, mps, inspe pect ctabi bilit lity Encro croachm hments ents – fences/gate s/gates, s, stai airs
Cap apital al Pl Plan an 11 minimally acceptable or unacceptable slope stability deficiencies on 4 levees • Address slope stability deficiencies that cannot be corrected by maintenance • Achieve provisional level of protection from flooding goal (500-year containment) • Achieve factors of safety to support future certification/accreditation • Capital Projects: Lower Russell setback levee Tukwila 205 – 3 locations Horseshoe Bend – 3 locations Tukw kwil ila 205
Vege egetat atio ion n Pl Plan an • Goals – (1) levees and floodwalls function as designed, (2) inspectability, (3) compliance with Clean Water and Endangered Species acts Achieve desired outcomes: • Vegetation management and maintenance to support annual inspections Improved riparian habitat and shade conditions along PL 84-99 shorelines Alignment of flood risk management activities Six Vegetation Management Zones with requirements to protect and restore natural - Landward zone resources - Landward slope zone • Vegetation M&O: - Crest zone Annual brushing/mowing (before flood season) - Upper riverward slope zone - Riverward bench zone Hazard tree mgmt. (public safety, levee integrity) - Lower riverward slope zone Vegetation maintenance on levees
Inte teri rim m Risk sk Red eductio uction n Meas easure ures • Physical: • Physical: Sand bags Flood Warning Center and Program Bulk bags (e.g., Hescos) – Flood Patrol and Levee Inspection temporary increase in height Public Communications – preparedness, Earthen levee raising (low spots) education, understanding of residual risk Small capital projects for scour Emergency Response (post-flood recovery) and erosion Animal Burrow Response Plan Temporary rock placement Tech studies, assistance, and consultation Flood hazard area regulations Effectiveness monitoring to improve performance
Fun undi ding ng an and d Imp mplem ement entat ation ion SWIF implementation organized to resolve PL 84-99 deficiencies using a worst-first approach: Funding constraints limit pace of capital project implementation Capital Project Costs = $85-101 million PL 84-99 Levee M&O costs = $780,000/yr Vegetation, encroachments, culverts, burrows, assessments/monitoring IRRM Costs: Non-structural = $523,000 countywide Structural = variable (per LF) Submittal of SWIF to USACE – Feb 2016
Fun unding ing an and Imp mplem emen entat atio ion
Project website: Google “Green River System Wide Improvement Framework”
Questions? Mark Isaacson, Division Director Water and Land Resources Division 206-477-4601 mark.isaacson@kingcounty.gov
Examp xample e Gr Gree een n River er Levee ee USACE CE PL 84-99 99 Rep epair airs Galli’s levee – toe ro rock k and wil illows Kent t Shops ps-Nari rita ta Segal ale – la launchab hable toe and flo floodwa dwall ll Lil ily Point inte
Pr Projec oject t Ar Area: ea: Gre reen en-Duw Duwamish amish Ri River er • Water ershed shed Area = 475 mi 2 • Populati ulation on = 370,000 • 10 10 cit itie ies Resid identi ential, commerci cial, al, • in industri strial and agricu culture ture • Green n Riv iver: r: 36 mil iles es of leve levees es and revet vetmen ents ts • Howard rd Hanso son n Dam (cons nstruct tructed d 1962 at RM RM 64.5) • All ll speci cies es of salm lmon on present sent
Lower er Green een River er: : Cont ntext xt Socio-Econo Economic mic • $7.3 billion in floodplain structures and contents • 100,000+ jobs 100 million sf warehouse • + distribution space (2 nd largest on West Coast) • Comprises 1/8 th of the GDP for WA State Annual taxable revenue of • $8 billion • Boeing, REI HQ, Amazon Fulfillment Center, Starbucks roasting plant
Lower er Green een River er: : Cont ntext xt Salmon Populations & Habitat • All species of salmon present, including ESA-listed Chinook salmon Historical pop. approx. 38,000 40-year average = 5,000 Low of 800 adults in 2009 25-65% hatchery origin • Limited spawning in Lower Green (above RM 24) • Lethal water temperatures (> 23 o C) have occurred in Green River mainstem (July 2006); TMDL water quality standard is 16 o C • Tribal fishing rights
Green een River er Fl Floo ood Fac acili lity ty Def efic icienci iencies es Levees and Revetments Revet vetments ents Tot otal Location Leve vees es (#/mi miles) es) (#/mil miles es) Miles Duwamish (RM 5.5-11) 3 (0.6 miles) 22 (3.3 miles) 3.9 Lower Green (RM 11-32) 41 (17.7 miles) 45 (9.8 miles) 27.5 Middle Green (RM 32-44) 12 (1.9 miles) 13 (2.9 miles) 4.8 Tot otal 56 (20.2 miles es) 80 (16.0 miles es) 36.2 PL 84-99 levees (RM 12.4-30.8) 12 (16 miles) • Aging system of levees – built to protect agricultural land uses, not regionally significant urban areas • Slope stability and toe scour issues Other deficiencies – culverts, vegetation, encroachments, animal burrows, • etc. • Current containment = 12,000 cfs with variable freeboard • Certification and Accreditation of Levees; FEMA mapping
Levee ee Defic eficiencies iencies (PL8 PL84-99) 99) Horse sesh shoe e Be Bend Levee e System m exa xample mple Unacceptable Min. Acceptable Category (item) Total Acceptable Encroachments 0 20 6 26 Unwanted Veg. Growth 19 3 1 23 Other (e.g., culverts) 7 1 6 14 Slope Stability 0 4 1 5 Depressions/Rutting 0 4 0 4 Erosion/Bank Caving 0 4 0 4 Debris 0 1 0 1 Cracking 0 1 0 1 Total 26 38 14 78 Deficiency Action Plan Near-term actions: encroachments, animal burrows, debris, depressions, brushing Mid-term actions: vegetation Long-term actions: slope stability (and toe scour)
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