Water Availability Study Safe Yield Analysis. Lori A. Burkert, P.G

Transcription

1 Water Availability Study Safe Yield Analysis Lori A. Burkert, P.G

2 Inflow vs Outflow

3 What is Safe Yield? Maintainable yield of water from a surface or groundwater source or sources which is available continuously during projected future conditions, including a repetition of the most severe drought of record, without creating undesirable effects -NJ DEP

4 Why do a water availability study? PA DEP drinking water permitting PA DEP water allocation permitting DRBC / SRBC withdrawal permitting DRBC / SRBC consumptive use permitting

5 Reality! Existing sources often: Have NO previous studies Studies don t take into account change New stresses on sources: Growing population Industry Energy demands Defend your current allocation / evidence for an increase

6 SW Safe Yield Study Criteria Simulate flow in watershed (or inputs) Simulate flow through reservoir system Simulate storage in the reservoir Apply to the period of record Deterministic Based on most severe drought of record NOT based on probability of occurrence or recurrence interval

7 Mass Curve

8 Case Study Jim Thorpe West Side Mauch Chunk Creek Intake (1968) Downstream of Mauch Chunk Creek Reservoir (owned by County) East Side Well 1 (1913) and Well 4 (1980)

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10 Case Study Jim Thorpe STREAM Q7/10 Low Flow = MGD MAUCH CHUNK CREEK RESERVOIR Storage = 1.36 BG Water Supply Capacity = 122 MG Low Flow Release = 0.58 MGD INTAKE Safe Yield = 1.88? MGD Allocation = MGD

11 Case Study Jim Thorpe Q7/10 Low Flow Reservoir Low Flow Release Drought Available Flow MGD MGD = MGD

12 Case Study Jim Thorpe STREAM Q7/10 Low Flow = MGD MAUCH CHUNK CREEK RESERVOIR Storage = 1.36 BG Water Supply Capacity = 122 MG Low Flow Release = 0.58 MGD INTAKE Safe Yield = 1.88 MGD Allocation = MGD

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14 Case Study Jim Thorpe DRBC groundwater and surface water allocation (11/10/2015) Combined 2 previous dockets from the west and east sides Submitted existing average and maximum daily water demand, with 10- year projections DRBC consulted with DEP

15 Case Study Jim Thorpe DRBC groundwater and surface water allocation (11/10/2015) Surface water allocation remained the same Groundwater allocation decreased SW allocation = MGM (0.425 MGD) GW allocation = 12.4 MGM (0.400 MGD)

16 Case Study Jim Thorpe PA DEP surface water allocation (10/30/1990) SW max daily withdrawal = 425,000 GPD SW min passby flow = 746,000 GPD Application currently submitted for renewal Minimal to no land development 10 yrs ago water usage near maximum Leak detection program reduced use 50% Expectation is that DEP matches DRBC

17 SW Case Study Birdsboro Power Proposed Birdsboro Power Electric Generating Plant Proposed source of water is Reading Area Water Authority Lake Ontelaunee / Maiden Creek watershed Required consumptive use approval from DRBC

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19 SW Case Study Birdsboro Power Impounding reservoir Reservoir simulation study assuming historic flows will occur in the future Sequential analysis of inflow, outflow, and operating conditions Stream gauge information for the period of record, or surrogate watershed / stream gauge data (1930 s current)

20 SW Case Study Birdsboro Power Month by month routing showing reservoir stage, evaporation, inflow, outflow, withdrawals, operational controls, daily variations in supply Simulate worst droughts on record Flooding / flood control not studied

21 SW Case Study Birdsboro Power Water availability studies prepared in 2000, 2008, and 2012 for other proposed power plants Updated flow model from previous studies Evaluated flow from new USGS stream gauge Accounted for inflow from dewatering of a local quarry Solved for daily water balance

22 SW Case Study Birdsboro Power WATER BALANCE EQUATION Storage (today) = Storage (yesterday) + Stream inflow + Discharge from local quarry - Outflow over the dam (stage) - Regular municipal withdrawals - Proposed withdrawal for power plant - Evaporation

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27 Water Availability Study Want to learn more about the Birdsboro Power water Availability Study? Join my talk at the 2017 PA AWWA Conference Questions? Lori Burkert