Water Availability Study

Water Availability StudySafe Yield Analysis

Lori A. Burkert, P.G.lburkert@entecheng.com610-373-6667

Inflow vs Outflow

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

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

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

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

Mass Curve

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)

Case Study Jim Thorpe

•

INTAKESafe Yield = 1.88 MGD

Allocation = 0.425 MGD

MAUCH CHUNK CREEK RESERVOIRStorage = 1.36 BGWater Supply Capacity = 122 MGLow Flow Release = 0.58 MGD

STREAMQ7/10 Low Flow = 0.892 MGD

?

Case Study Jim Thorpe

Q7/10 Low Flow

ReservoirLow Flow Release

Drought Available

Flow

0.892 MGD - 0.58 MGD = 0.312 MGD

Case Study Jim Thorpe

•

INTAKESafe Yield = 1.88 MGD

Allocation = 0.425 MGD

MAUCH CHUNK CREEK RESERVOIRStorage = 1.36 BGWater Supply Capacity = 122 MGLow Flow Release = 0.58 MGD

STREAMQ7/10 Low Flow = 0.892 MGD

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

Case Study Jim Thorpe

• DRBC groundwater and surface water allocation (11/10/2015)

• Surface water allocation remained the same• Groundwater allocation decreased

• SW allocation = 13.175 MGM (0.425 MGD)• GW allocation = 12.4 MGM (0.400 MGD)

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

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

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)

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

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

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

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

lburkert@entecheng.com