questions to answer
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Questions to answer. What is the overall modeling approach (after calibration and background scenarios)? What are the WLA assumptions? How will Avista’s requirement be determined? Misc. considerations (policy) How TMDL WLA’s are translated into permits Others?. - PowerPoint PPT PresentationTRANSCRIPT
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Questions to answer
What is the overall modeling approach (after calibration and background scenarios)?
What are the WLA assumptions? How will Avista’s requirement be determined? Misc. considerations (policy) How TMDL WLA’s are translated into permits Others?
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Overall Approach: Step 0 (Scenario #1)
Establish riverine assessment point nutrient criteria
• 2001 flows
10 ug / L PhosphorusRiverine Target
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Overall Approach: Step 1(Scenario #1)Set tributary phosphorus for nonpoint source reductions.
• Hangman: 30% (Apr.-May); 35% (Jun.-Oct.)• Little Spokane: 35% (Apr.-May); 38% (Jun.-Oct.)• Coulee Cr.: Same as Hangman
10 ug / L PhosphorusRiverine Target
HC
CC
LSR
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Overall Approach: Step 2(Scenario #1)Set point source TP to Flat 50 ug/L
• March to October
• Monthly average permit limit
• Scenario #2: Lower Level of Treatment= <50 ppb for WA• Scenario #3: Account for reuse at HARSB and PF (variable TP)
TP = Flat 50 ug/L
10 ug / L PhosphorusRiverine Target
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Overall Approach: Step 3(Scenario #1)Set point source CBOD and Ammonia values
• CBOD = 5 mg/L• See handout for ammonia values
TP = Flat 50 ug/L
10 ug / L PhosphorusRiverine Target
CBOD = 5 mg/LAmmonia = variable
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10 ug/L phosphorus Riverine target
Overall Approach: Step 4(Scenario #1)Run model to determine if riverine target is met.
• TP = 30 day rolling average• DO = daily minimum• Ammonia = daily max
TP = Flat 50 ug/LCBOD = 5 ppmAmmonia = Variable
Run Model
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10 ug/L phosphorus Riverine target
Overall Approach: Step 5(Scenario #1)If target is met, run model through reservoir to analyze dissolved oxygen • DO processed into volume-weighted average for each 2 week period (>8 m depth)
• Segment 157 (LL5) to 188 (LL0) analyzed
TP = Flat 50 ug/LCBOD = 5 ppmAmmonia = Variable
Run Model
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NO SOURCE scenario in model environment
Model Segment
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Compare NO SOURCE with TMDL scenarios, compare volume weighted average of vertical cells over 2 week periods
Volume weighted average across profiles
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Additional considerations
Foundational Concepts delta management will be retained to achieve WLA’s
Can be addressed during implementation: Off season P limits Effects of stormwater Effects of high flows from Hangman Creek Bioavailability of phosphorus Nonpoint source impacts to river mainstem Avista water quality attainment plan SOD in Lake Spokane Etc.
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Average = 467.5
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Average = 467.5
Monthly Average (95th %tile) = 1,072
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Monthly Average (95th %tile) = 1,072
Average = 467.5
Daily Maximum (99th %tile) = 1,502
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