Delaware

Public Water Supply System Service Areas

New Castle County

Public Water Demand in Northern Delaware

Residential48% (33 mgd)

Industrial18% (12 mgd)

Commercial21% (14 mgd)

Unaccounted13% (9 mgd)

Figure 4: Brandywine Creek at Wilmington Streamflow Data,October 2001 - December 2002

*The 7Q10 is the minimum flow necessary to protect f ishery and habitat that is likely to occur for 7 consecutive days, once every 10 years

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BWW BWW 7Q10

Record Low Flow: (21mgd) 23 August 2002

Figure 11: Chlorides, White Clay Creek at Stanton, July 2002 - November 2002

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Intake Chlorides Plant Effluent Chlorides USEPA MCL (250 ppm)

Lowest stream flows on the Brandywine Creek at Chadds Ford, PA from 1911-2001(*Data for the years 1954-1961 was unavailable*)

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am F

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Brandywine Creek at Chadds Ford, Streamflow v. Cumulative Precipitation

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Lowest Recorded Streamflow of Year, Sorted by Date

Flow

(mgd

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Figure 18. Estimate of Low Flow Recurrence Interval with the Weibull Distribution

Brandywine Creek at Chadds Ford - 1972-2001

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Low Flow 21 mgd Aug 23, 2002

p = 0.01, 100-yr. recurrence interval

2020 Supply/Demand Curve (2020 Supply/Demand Curve (mgdmgd))

Scenario Supply Demand +/- Vol (mg)1. No 7Q10 93 90 +3 180*

2.7Q10 Wc 85 90 - 5 -300*

3.7Q10 B&W 73 90 - 17 -1020*

* Volume required assuming a 60-day drought period

FUTURE WATER SUPPLY OPTIONSFUTURE WATER SUPPLY OPTIONS““AA”” LISTLISTCOMMITTED TO BY WATER PROVIDERSCOMMITTED TO BY WATER PROVIDERS• Newark Reservoir 300 mg• Access Hoopes Reservoir 500 mg• AWC Wells N. of C & D Canal 120 mg• Newark S. Wells Iron Treatment 60 mg• Artesian ASR Wells 120 mg

Total 1100 mg

FUTURE WATER SUPPLY OPTIONSFUTURE WATER SUPPLY OPTIONS““BB”” LISTLISTACHIEVABLE IN LONGER TERMACHIEVABLE IN LONGER TERM

• Increase CWA/AWC Inter. 180 mg• Raise Hoopes Reservoir WL 300 mg• AWC C&D Canal Pipeline 300 mg• Philadelphia to DE Pipeline 1200 mg• Bread & Cheese Is. Reservoir 500 mg

HoopesHoopes ReservoirReservoir

TCS

White Clay Creek at Stanton

White Clay Creek at Stanton Stream Profile7Q10 Conditions

UWD Stanton Intake

13843 (0.96)

14073 (0.85)

10800 (0.90)

AMTRAK Bridge

-3.00

-2.00

-1.00

0.00

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2.00

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7900840089009400990010400109001140011900124001290013400139001440014900

Distance from mouth of White Clay Creek (feet)

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ove

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a le

vel (

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Streambed Elevation 7Q10 WSEL (at low tide) 7Q10 WSEL (w ith TCS at low tide) 7Q10 (at high tide) Critical Depths

White Clay Creek Cross-Section 10800Critical Depth

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Streambed Elevation 7Q10 WSEL (at low tide) 7Q10 (at high tide)

White Clay Creek at StantonWhite Clay Creek at StantonStation 10800Station 10800

00.5

11.5

22.5

33.5

44.5

0 1 2 3 4 5 6 7 8 9 10 11 12Tidal Cycle (Hours)

Dep

th (f

t) Depth

At 7Q10 = 17.2 mgd, TCS uninflated

DGS Watershed Mapsouthern New Castle County

(Baxter and Talley, DGS, Aug 1996)

Availability vs. Supply Availability vs. Supply southern New Castle Countysouthern New Castle County

Watershed Availability SupplyC & D Canal, Aug. Cr. 2.62 3.57Drawyer Cr./Appo. R. 5.73 4.67Blackbird Creek 3.94 0.22Cedar swamp 0.31 0.00Smyrna River 2.83 1.05Cypress Branch/Chester R. 1.54 0.00Sassafras River 1.37 0.00Great Bohemia Creek 1.18 0.40Back Creek 0.55 3.42

Total So. NCC 20.07 mgd 13.33 mgd

PopulationPopulationsouthern New Castle Countysouthern New Castle County(Source: DE Population Consortium, 2004)(Source: DE Population Consortium, 2004)

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2010

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Year Pop. % Increase2000 29,682 0 %2005 36,792 24%2010 42,420 15%2015 47,985 13%2020 59,992 12%2025 68,115 14%2030 74,587 10%

30 year increase = 151%

Public Water DemandPublic Water Demandsouthern New Castle Countysouthern New Castle County

Year Population Indiv. Wells Water Demand(4000 wells) Normal Peak= 12,000 pop. (100 gpcd) (200 gpcd)

2000 29,682 17,682 1.7 3.5 2005 36,792 24,792 2.5 5.02010 42,420 30,420 3.1 6.12015 47,985 35,985 3.6 7.22020 59,992 47,992 4.8 9.62025 68,115 56,115 5.6 11.22030 74,587 62,587 6.3 mgd 12.5 mgd