Aquifer mapping in Kent and Sussex Counties, Delaware: A key to

understanding groundwater sources

A Presentation to the 2013 Region 3 Source Water Protection Meeting

June 6, 2013

Pete McLaughlin, Amanda Lawson, and Jaime TomlinsonDelaware Geological Survey, University of Delaware

• Your challenge: Identifying drinking water sources and protecting these source waters from contaminants

• An understanding the source aquifer and groundwater flow within it allows delineation of source water assessment boundaries

• An understanding of subsurface geology is necessary to accurately characterize the ground water source

• Key geologic aspects:– Aquifer delination (geographic, depth)– Aquifer hydrologic characteristics– Nature of associated confining units

Where Source Water Protection Meets Geology

Starting Premise

Accurate Understanding of Aquifer Geology

is essential toAccurate Understanding of Groundwater Occurrence

Geology controls where the groundwater is, where it goes, and how much we get

The Idea: A Project

• Identify and delineate the aquifers of southern Delaware (Kent and Sussex Counties) the are sources of public drinking water

• Determine where these aquifers are used as drinking water sources and the magnitude of withdrawals

• Conducted by DGS, supported by DNREC

Outline

1. Objectives and Background2. Aquifers of Southern Delaware3. Water Use in Southern Delaware

• Goal: To establish an up-to-date summary of the groundwater resources of Kent and Sussex Counties, Delaware

• Incentives: The last comprehensive report on ground-

water availability and aquifers in Sussex County was published more than 40 years ago (Sundstrom and Pickett, 1968)

Reported aquifers in state, federal, and SWAPP databases are not always correct

• Benefit: The results of this work will support source water protection, well permitting, and water supply planning programs in Delaware

Data from USGS (http://water.usgs.gov/watuse/data/2005/ )

Kent + Sussex Groundwater Use

0102030405060708090

100

1985 1990 1995 2000 2005

MG

D

Data from USGS (http://water.usgs.gov/watuse/data/2005/ )

Kent + Sussex Population

0

50000

100000

150000

200000

250000

300000

350000

1985 1990 1995 2000 2005

0102030405060708090

100

1985 1990 1995 2000 2005

Kent + Sussex Groundwater Use

if 130Kpopulation growth

MG

D

in2030

+ 13? MGD

PLUSmore irrigation

ObjectivesPrimary purpose: Updated summary of the ground-water resources of Kent and Sussex Counties, Delaware, in two parts:• Aquifer geology:

– to compile geological cross-sections highlighting the correlation of aquifers

– to construct structural contour and isopach maps of the aquifers

– to acquire new data in areas where geological control is lacking, including new drilling and geophysical logging

• Hydrology:– to compile data on water use in Sussex County, – to characterize the hydrologic characteristics of each aquifer, – summarized these within the updated aquifer framework.

ObjectivesRecent related work: • Confined aquifer mapping for Kent County (McLaughlin and

Velez, 2006)• Unconfined aquifer mapping for Sussex County (Andres and

Klingbeil, 2006) Strategy: • use selected, high-quality data; • establish carefully documented methodologies for

estimation/interpretation where high-quality data are lacking; • identify issues where a lack of adequate data indicates a need

for further study (project will not address organizational/ quality control issues of all potentially available data).

Geology&

Hydrology

Geology: Formations

Geology: Aquifers

Geology Methods & Data• Stratigraphic picks for tops and bottoms of

aquifers (and formations)• Assembled stratigraphic picks database of

14000 records plus another 2300 records of sites where picks not made or were redacted

• Stratigraphic picks database includes app. 6600 wells with stratigraphic picks and records of app. 2100 others evaluated but not suitable for picks

Geology Methods & Data• Dense coverage of picks in

Delaware• Extended picks into MD

and NJ to minimize edge effects at borders

GeologyMethods & Data

• Drilled test holes at 10 locations where availability of confined aquifer data was sparse

• Holes ranged from 600 to 840 ft depth• Cuttings sample were collected, lithologic logs were

created, and geophysical logs (gamma-multipoint electric) were recorded

• Benefit: High quality deep confined aquifer picks

Unconfined Aquifer Methods & Data

• New picks for Kent County; for Sussex used data and maps of A&K-2006

• Utilized geophysical logs, geologist logs, and driller logs– maximize data volume given

degree of local variation• Well ranking system

– 1 = Geophysical log and a descriptive log

– 2 = Geophysical log only– 3 = Descriptive log only– 4 = Poor quality log– 5 = Unable to make pick

Unconfined Aquifer Methods & Data • Can we take single driller logs

face value?• Aim for consistency, esp. with

geologist & geophysical logs

exam

ple:

blo

ck M

d42

Unconfined Aquifer Methods & Data• Created Kent County unconfined aquifer grids

1. Reviewed drillers logs in detail, aggressive accept/reject approach emphasizing consistency

2. Elevation of Base Unconfined grid created using Radial Basis Function method in ArcGIS Geostatistical Analyst

3. Unconfined Thickness grid computed from surface DEM and base elevation grid

4. Final grids corrected for 3-dimensional constraints (topography)

• Created a K-S unconfined grid by stitching new Kent unconfined elevation grid and existing A&K-2006 Sussex unconfined elevation grid

Unconfined Aquifer

Elevation Grid:

Kent County

Unconfined aquifer & geology•Common scattered beds

of clayey silt•Silt to fine sand over

medium to coarse sand in upper 5-25’

•Rare discontinuous clayey silt beds

•Heterogeneous coarse to fine sand, gravelly sand, and pebble gravel

Unconfined Aquifer, Sussex County

• Thickness map• Elevation of base• Transmissivity map • > 4200 data points• Used drillers’ and

geophysical logs

Klingbeil and Andres, 2006

Unconfinedaquifer

• Thickness map• Elevation of base• > 1600 data points• Splice with Sussex

map

Unconfinedaquifer

Kent + Sussex

Confined Aquifer Methods & Data• Picks mostly from geophysical logs, a smaller

number from lithologic logs with high-confidence data

• Depths converted to elevation by subtracting from well elevationsignificant elevation data QC required

• Values exported from stratigraphic database and imported into ArcGIS as point data

Confined Aquifer Methods & Data• Gridding utilized Radial Basis Function

(multiquadric) method in ArcGIS Geostatistical Analyst

• Used 100 m grid resolution• Grids made for each confined aquifer of:

– top aquifer from picks– base aquifer from picks– aquifer thickness by grid math

Confined Aquifer Methods & DataGrid QC work• Grids checked against intersection with overlying

and underlying surfaces– in some cases, dummy or projected values used to

ensure non-intersecting grid position in sparse data areas

• Grid surfaces are cut-away where overlying surface occurs lower– most significant case: base of unconfined aquifer

occurring below top of base of a confined aquifer, which means normally confined sand unit is not confined there

Mount Laurel aquifer

Rancocas aquifer

Piney Point aquifer

Lower Calvert sandsand unit below the Cheswold sand

Cheswold sand

Example of how to represent an aquifer in 3D context

Cheswold sandaccurate in 3 dimensions

not represented on grid where based unconfined is lower

somewhat simplifiedrepresented to updip limit of presence regardless of

elevation of base unconfined

“Federalsburg” sand

Frederica sand

Milford sand

middle Choptank sand

upper Choptank sand

Manokin aquifer

Manokin aquifersimplified, unconfined not accounted for

Manokinaquifersubcrop

Implications forRecharge andSource Water

Protection

Pocomoke aquifer

Pocomoke aquifersimplified, unconfined not accounted for

Pocomokeaquifersubcrop

Implications forRecharge andSource Water

Protection

GroundwaterUse

Groundwater Use Methods & DataGroundwater Use Calculations

LivestockIndustrialPublic DomesticIrrigation

EstimatedPopulation outside public-served areas

X

socioeconomic-based per capita coefficient

Calibrated to

Known usage in similar public served

areas

Metered/Reported

for big systems

+Estimated

For smaller systems

Assumed usage rates per user type

X

Population or size of facility served

Metered/Reported

EstimatedIrrigated acres

X

Estimated water use by crop type and soils

calibrated to

Known usage for metered irrigation

EstimatedLivestock populations

X

Average water use/type of livestock

Compilation of Water Use DataTheoretically:• Reported Water Use (large users, allocations)

– large public– industrial & thermoelectric– irrigation (ag & golf course)

• Non-Reported Water Use (smaller users)– smaller public– domestic self-supplied– livestock– lawn self-supplied– other minor types

Groundwater Use Data

Well location data• DGS WATSYS Oracle database, includes

multiple regular dumps of DNREC well database

• SWAPP database dump used for list/locations/depths of public wells

Groundwater Use Data2004-2008 Water Use Database with ~42,000 records and 930+ wells

Compilation of Water Use DataIn reality, in this study:• Well data, reported

– large public– industrial & thermoelectric

• Well data, estimated– small public (CWS, TNC, NTNC)– golf course (some reported)

• Area data, estimated by census block– domestic self-supplied– irrigation (agricultural)– livestock (poultry)– lawn self-supplied

Groundwater Use Methods & Data Reported Use: Public & Industrial

• Categories:– Public (446 wells)– Industrial Self-Supplied (62 wells)

• Approach– Compiled and cleaned up monthly water use data– Subtotal annual water use for 2004-2008– Verified locations and fixed as needed– Verified screen depths and fixed as needed

Groundwater Use Methods & DataReported Use: Public & Industrial

Groundwater Use Methods & Data Census Data vs. Water Use Relationships

for Census-Based Water Use Estimates

• Used public wells and service areas (block or subblock) with principally domestic use• Examined reported pumping vs census factors used in Horn et al., 2007 USGS New Hampshire

Seacoast water use report; 5 selected:

Variables Coefficients

BldYrWtAvg -0.006891889317145660

HHSizeWtAvg -0.217913102554659000

HouseValWtAvg 0.000001850164162435

HsgDensityWtAvg 0.000113449101106628

PopDensityWtAvg 0.000030698704019032

Intercept 4.933770428394450000

• Subblock percentages derived from basis of percentage of parcels plus extensive manual editing• Use the census populations, for calculation of the calibration data, gallons pumped per day per person (from reported pumpage)• Use the normal log of the weighted average GPCD (gallons per capita daily) for each pumping network to plot against the five census factors selected from the NH study, and do a multiple

regression to determine the correlation coefficent for each -- so we have correlations of census factors (which includes population-based numners like pop density and household density to water use that includes more-than-census

• then I take those coefficients and use them to calculate resident-population-based modeled water use for each census block/subblock (latter where a block is divided) -- so that is also based on real population

• then I calculate expected peak population addition and annualized average summer population addition (on basis of average 66 days occupancy) and scale up the water use from that population numbers based on that block’s coefficient-based GPCD

• then those total block/subblock water use calcs are subtotaled (resident plus vacationer use modeled together) for each service polygon and then into each pumpage network (group of polygons) so that actual pumpage can be correlated to modeled pumpage

-

50

100

150

200

250

f(x) = 0.85038152330854 x + 17.4947293454124R² = 0.707239158396268

Gallons Per Capita Daily

Groundwater Use Data2010 and 2000 census data for populations and demographics

13,218 census blocks in Kent & Sussex

Groundwater Use Methods & Data Estimated Use: Public Community

• Public Community (178 wells)– Estimated total water

use for system on basis of census-based water use determinations

– Split the system use totals among the wells in the system (usually 1, 2, or 3

– no basis for estimation of different pumping by year

will update CWS NR map

Groundwater Use Methods & Data Estimated Use: Public Community & Non-Community

• Public Non-Transient Non-Community (69 wells)• Public Transient Non-Community (154 wells)

Water Use estimated either by:• direct factor by

facility type, including size

• population served with a factor for facility type

Groundwater Use Methods & Data Estimated Use: Public Non-Community

will update NCNT map will update NCT map

Non-Public System Water Use• Self-Supplied Domestic• Irrigation (crops)• Irrigation (golf courses)• Irrigation (lawns – separate self-supplied)• Livestock (poultry)

a quick summary of those methods...

Groundwater Use Methods & Data Estimated Use: Self-Supplied Domestic

• Basis: Population by Census Block, not wells– Utilized previously described method of estimating

water use via five census- and pump-data-based coefficients

Groundwater Use Data

Ag-related data• Irrigation: 2,400+

irrigation polygons• Livestock: 2,600+ chicken

houses

Groundwater Use Methods & Data Estimated Use: Irrigation

• Approach: Build a model to estimate irrigation – Method: KanSched irrigation scheduler using nearest

weather station data– Input:

• Irrigated areas catalogued by James Adkins (UD Ag) via 2008 aerial photography

• Climate (precipitation , evapotranspiration) nearest each irrigated area

• Crop Type in each irrigated area (National Agricultural Statistics Service 2008 Cropland Data Layer)

• Soil Type (water capacity) predominant in each climate polygon (USDA NRCS)

Groundwater Use Methods & Data Estimated Use: Irrigation

Groundwater Use Methods & Data Estimated Use: Livestock (Poultry)

Chicken house numbers: • 2611 houses in Kent and Sussex

Counties likely/possibly active

Chicken house sizes:• Majority of existing houses around

50 x 500 (use as average)

Water Use estimate for average house:• 374,000 gallons/house/yr drinking• 201,600 gals/house/yr cooling

Groundwater Use Methods & Data Estimated Use: Lawn Irrigation (“Ag”)

Approach:• identify how many lawn wells per census block

(1074 wells in 177 blocks)• calculate water use per household (not per

capita) per month in those blocks• assume in summer months that lawn watering

can add 50% to baseline water use on basis of public data

• calculate lawn watering ag water use for each block by number wells x 0.5 x 3 months

2004-01

2004-05

2004-09

2005-01

2005-05

2005-09

2006-01

2006-05

2006-09

2007-01

2007-05

2007-09

2008-01

2008-05

2008-090

100000

200000

300000

400000

500000

600000

Viola system: Public example

VIOL

Groundwater Use Methods & Data Reported & Estimated Use: Golf Course Irrigation

28 golf course wells on basis of allocations• A minority of courses reported reliably -- 8 of 28 wells• 11 of 28 wells did not report data any year• 9 of the 17 reported something (but 5 only reported

once)

Approach:• For wells with reported data, subtotaled monthly

reported pumpage for annual totals (though some look to have questionable accuracy)

• Where not reported, assume the 1.5 x full allocation was pumped every year and divided it between wells

How much from which aquifer?• The above steps get us to how much water is

being pumpeda. from a well; orb. in an area

• However, if we are concerned about the source of drinking water, or volumes of groundwater withdrawals, we need to identify the relevant aquifers

• Grids compared with database of screen depths• Water use and hydrological characteristics assigned to aquifer where

screened instead of reported aquifer

EmphasisCorrect Aquifer Assignment

Well A

Well C

Well BReported in X

Hydrology and Water Use Meet Geology

Water Use Analysis

Frederica

Cheswold

Piney PointPiney Point

Approach: Analysis of screen depths to aquifer depths

2006 pumping0 or no data 0 - 20 MG20 - 50 MG50 - 60 MG60 - 120 MG> 120 MG

Aquifers:• Geographic trends in water

use by aquifer• Totals of water use by aquifer

Groundwater Use Methods & Data Aquifer Assignment: Well Specific Usage

Types: Public, Industrial, Golf Course

1. Tabulate well sources: elevation of well, top screen depth, bottom screen depth, and convert depths to elevations• where well elevation missing, sample DEM• where top and bottom of screen is missing, use hole depth

and/or top and bottom of gravel pack• cross compare DGS, DNREC, SWAP databases for these data

2. Determine aquifer depths using grids. At the location of each well, “sample” (pick depth) from the grid of the elevation of the top and base of each aquifer; so each well location has 13 pairs of aquifer elevation values

Groundwater Use Methods & Data Aquifer Assignment: Well Specific Usage

Types: Public, Industrial, Golf Course

3. Compare screens to aquifers. Run an ArcMap script OR a series of Excel formulas that compares the top and bottom screen elevations (or proxies) to the sampled top and bottom of each aquifer• where all screen falls between top and bottom of one

aquifer – easy! assign aquifer• where the screen crosses two aquifers or falls between

aquifers (all or in part), further investigation is needed• there is no grid for “confined Columbia” so that is usually a

manual interpretation for screens between highest confined and base unconfined.

Groundwater Use Methods & Data Aquifer Assignment: Non-Well Specific Usages

None include Public Water Supply wells

Use Source Aquifers Cross-Reference

Domestic self-supplied

Clusters of domestic screen depths by census block

Sample grids at block center point

By proportion in each aquifer in block

Irrigation Clusters of irrigation screen depths by census block

Sample grids at block center point

By proportion in each aquifer in block; many in multiple aquifers

Poultry Clusters of ag well depths near chicken house by census block

Sample grids at block center point

By proportion in each aquifer in block

Lawn All very shallow All unconfined aquifer

One aquifer

Water Use Results

Summary by UseUSE Kent

MGDSussex MGD

Total MGD

USGS 2010

USGS 2000

Public Reported (high use yr) 11.0 15.2 26.2

25.24 23.05Public Reported (low use yr) 10.1 12.7 22.8

Public Non-Reported (estimated) 0.58 1.23 1.81

Domestic self-supplied (model) 4.24 7.37 11.61 5.73 10.79

Industrial self-supplied (high use yr) 1.35 6.96 7.667.29 9.41

Industrial self-supplied (low use yr) 0.83 5.56 6.66

Irrigation: Ag (model high use 2007) 19.12 71.69 90.8253.84 33.82

Irrigation: Ag (model low use 2006) 5.62 44.53 50.16

Irrigation: Golf Course (median rpt+est) 0.17 2.00 2.17 - -

Ag: Lawn wells (estimated) 0.008 0.022 0.03 - -

Ag: Livestock (estimated) 0.7 3.6 4.3 1.44 3.63

Total (high end) 37.2 108.1 144.6 94.5 81.2Total (low end) 22.2 77.0 99.5

updated 6/5/13

Public Water Supply – Reported• Project & County Totals

calculated– number of wells and volumes by

year tabulated– water use volumes calculated by

aquifer – water use can be displayed by

map, symbolized or subtotaled by census block

• Strengths & Weaknesses of Data & Analysis– based on fairly complete, error-

checked reported data– well construction information

generally good by combining DNREC and DGS information

Public Reported

2004 2005 2006 2007 2008

Kent (gallons)

3,674,429,787

3,864,285,976

3,844,692,303

4,016,520,959

3,973,377,535

Sussex (gallons)

4,644,680,600

4,973,593,996

5,129,326,570

5,540,338,394

4,788,754,001

Total (gallons)

8,319,110,387

8,837,879,972

8,974,018,873

9,556,859,353

8,762,131,536

Kent (MGD) 10.07 10.59 10.53 11.00 10.89

Sussex (MGD) 12.73 13.63 14.05 15.18 13.12

Total (MGD) 22.79 24.21 24.59 26.18 24.01

• app. 25 MGD in public water system reported water use• app. 11 MGD in Kent• app. 14 MGD in Sussex

updated 6/5/13

Public Reportedgallons/yr

Kent MTL RAN PPT CHE FED FRE MIL COLC UNC2004Total 3,103,400 89,883,100 1,573,605,207 1,228,865,848 200,669,900 464,507,284 - 10,200 102,426,920

2005Total 3,988,300 81,144,800 1,350,243,658 1,214,445,008 286,381,800 466,941,906 - 29,500 424,314,004

2006Total 5,661,500 85,727,000 1,162,468,238 1,459,185,900 317,876,500 487,375,165 - 24,200 260,576,500

2007Total 14,574,000 76,593,300 1,321,510,728 1,342,726,900 310,287,543 562,429,300 1,074,300 3,400 447,395,720

2008Total 13,280,800 72,259,100 1,210,682,194 1,307,237,897 342,731,500 521,403,500 444,200 - 529,244,400

Wells 1 5 35 57 13 28 3 1 17

Sussex CHE FED FRE MIL UCH MAN POC COLC UNC2004Total 41,000 56,117,000 181,312,400 272,280,000 49,302,900 659,818,897 982,162,847 738,642,128 1,730,794,428

2005Total 65,000 66,601,000 203,569,500 240,599,000 54,953,690 776,326,175 1,156,997,485 870,109,521 1,641,169,625

2006Total 76,000 56,210,000 224,952,000 200,765,000 45,707,710 597,426,413 1,493,379,037 774,076,509 1,776,174,901

2007Total 29,025,600 56,589,000 180,262,500 217,728,000 49,744,260 700,885,276 1,440,677,701 970,932,087 1,810,128,250

2008Total 45,088,700 54,124,000 185,565,700 142,164,000 48,898,500 669,536,800 1,234,207,714 750,262,936 1,614,352,851

Wells 1 1 15 4 3 27 84 55 98

Total MTL RAN PPT CHE FED FRE MIL UCH MAN POC COLC UNC2004Total 3,103,400 89,883,100 1,573,605,207 1,228,906,848 256,786,900 645,819,684 272,280,000 49,302,900 659,818,897 982,162,847 738,652,328 1,833,221,348

2005Total 3,988,300 81,144,800 1,350,243,658 1,214,510,008 352,982,800 670,511,406 240,599,000 54,953,690 776,326,175 1,156,997,485 870,139,021 2,065,483,629

2006Total 5,661,500 85,727,000 1,162,468,238 1,459,261,900 374,086,500 712,327,165 200,765,000 45,707,710 597,426,413 1,493,379,037 774,100,709 2,036,751,401

2007Total 14,574,000 76,593,300 1,321,510,728 1,371,752,500 366,876,543 742,691,800 218,802,300 49,744,260 700,885,276 1,440,677,701 970,935,487 2,257,523,970

2008Total 13,280,800 72,259,100 1,210,682,194 1,352,326,597 396,855,500 706,969,200 142,608,200 48,898,500 669,536,800 1,234,207,714 750,262,936 2,143,597,251

Wells 1 5 35 58 14 43 7 3 27 84 56 115

• annual variations largely reflect water use and not just reporting irregularities

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Public ReportedMGD

Kent MTL RAN PPT CHE FED FRE MIL COLC UNC2004Total 0.009 0.246 4.311 3.367 0.550 1.273 0.000 0.000 0.2812005Total 0.011 0.222 3.699 3.327 0.785 1.279 0.000 0.000 1.1632006Total 0.016 0.235 3.185 3.998 0.871 1.335 0.000 0.000 0.7142007Total 0.040 0.210 3.621 3.679 0.850 1.541 0.003 0.000 1.2262008Total 0.036 0.198 3.317 3.581 0.939 1.429 0.001 0.000 1.450% (2007) 0.4 1.9 32.3 32.8 7.6 13.7 0.0 0.0 10.9

Sussex CHE FED FRE MIL UCH MAN POC COLC UNC2004Total 0.000 0.154 0.497 0.746 0.135 1.808 2.691 2.024 4.7422005Total 0.000 0.182 0.558 0.659 0.151 2.127 3.170 2.384 4.4962006Total 0.000 0.154 0.616 0.550 0.125 1.637 4.091 2.121 4.8662007Total 0.080 0.155 0.494 0.597 0.136 1.920 3.947 2.660 4.9592008Total 0.124 0.148 0.508 0.389 0.134 1.834 3.381 2.056 4.423% (2007) 0.5 1.0 3.3 4.0 0.9 12.9 26.5 17.9 33.3

Total MTL RAN PPT CHE FED FRE MIL UCH MAN POC COLC UNC2004Total 0.009 0.246 4.311 3.367 0.704 1.769 0.746 0.135 1.808 2.691 2.024 5.0232005Total 0.011 0.222 3.699 3.327 0.967 1.837 0.659 0.151 2.127 3.170 2.384 5.6592006Total 0.016 0.235 3.185 3.998 1.025 1.952 0.550 0.125 1.637 4.091 2.121 5.5802007Total 0.040 0.210 3.621 3.758 1.005 2.035 0.599 0.136 1.920 3.947 2.660 6.1852008Total 0.036 0.198 3.317 3.705 1.087 1.937 0.391 0.134 1.834 3.381 2.056 5.873% (2007) 0.2 0.8 13.9 14.4 3.8 7.8 2.3 0.5 7.4 15.1 10.2 23.7

• Kent: Cheswold and Piney Point are largest sources for reported public use (1/3 each)• Sussex: Unconfined (1/3) and Pocomoke (1/4), then confined Columbia and Manokin

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Public Non-ReportedCommunity: 1.31 MGD (479,735,667)• Kent: 0.45 MGD (163,685,332)• Sussex: 0.87 MGD (316,050,335 gals)

Non-Community Transient: 0.387 MGD (141,382,833 )• Kent: 0.083 MGD (30,419,500 gals)• Sussex: 0.304 MGD (110,963,333 gals)

Non-Community Non-Transient: 0.111 MGD (40,381,517 gals)• Kent: 0.047 MGD (17,115,000 gals)• Sussex: 0.064 MGD (23,266,517 gals)

Total: 1.81 MGD (661,500,017 gals)• Kent: 0.58 MGD (211,219,832)• Sussex: 1.23 MGD (450,280,185)

PWSEstPumpage w rev

Public Community Non-Reported• Project & County Totals

calculated– number of wells tabulated– water use volumes calculated

by aquifer – water use can be displayed by

map, symbolized or subtotaled by census block

• Strengths & Weaknesses of Data & Analysis– census-based methodology for

service area, same coefficients as used for domestic

will update CWS NR map

Public Community Non-Reported

Kent PPT CHE FED FRE MIL BLU COLC UNC UNK

Gallons/yr

2,914,383

97,202,376

8,874,870

6,111,715

43,311,611

431,521

3,750,855

4,376,882

1,653,373

MGD 0.008 0.266 0.024 0.017 0.119 0.001 0.010 0.012 0.005

Well Count 3 29 8 5 5 1 2 5 2

Sussex FRE MIL ORA BLU MAN POC COLC UNC UNK

Gallons/yr

20,476,085

23,890,467

6,436,395

6,403,838

60,989,226

46,273,035

91,805,834

101,990,388

21,557,640

MGD 0.056 0.065 0.018 0.018 0.167 0.127 0.252 0.279 0.059

Well Count 5 8 4 2 18 22 33 36 11

Kent+Sussex PPT CHE FED FRE MIL ORA BLU MAN POC COLC UNC UNK

Gallons/yr

2,914,383

97,202,376

8,874,870

26,587,800

67,202,078

6,436,395

6,835,359

60,989,226

46,273,035

95,556,689

106,367,270

23,211,013

MGD 0.008 0.266 0.024 0.073 0.184 0.018 0.019 0.167 0.127 0.262 0.291 0.064

Well Count 3 29 8 10 13 4 3 18 22 35 41 13

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Public Non-Transient Non-Community

• Project & County Totals calculated– number of wells tabulated– water use volumes calculated by

aquifer – water use can be displayed by

map, symbolized or subtotaled by census block

• Strengths & Weaknesses of Data & Analysis– based on facility type, so a leap

of faith in assumed water use (per capita user or per facility size)

will update NCNT map

Public Non-Transient Non-Community

Kent PPT CHE FED FRE MIL UNC UNK

Gallons/yr

8,575,000

1,725,000 980,000

2,765,000

1,125,000

2,080,000

600,000

MGD 0.023 0.005 0.003 0.008 0.003 0.006 0.002

Well Count 2 3 4 12 1 5 1

Sussex CHE FRE MIL ORA BLU MAN POC COLC UNC UNK

Gallons/yr 150,000

1,155,000

540,000

22,000

125,000

835,833

5,760,000

5,509,100

8,916,667

1,587,500

MGD 0.000 0.003 0.001 0.000 0.000 0.002 0.016 0.015 0.024 0.004

Well Count 1 2 2 1 1 6 5 9 23 4

Kent+Sussex PPT CHE FED FRE MIL ORA BLU MAN POC COLC UNC UNK

Gallons/yr

8,575,000

1,875,000 980,000

3,920,000

1,665,000

22,000

125,000

835,833

5,760,000

5,509,100

10,996,667

2,187,500

MGD 0.023 0.005 0.003 0.011 0.005 0.000 0.000 0.002 0.016 0.015 0.030 0.006

Well Count 2 4 4 14 3 1 1 6 5 9 28 5

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Public Transient Non-Community• Project & County Totals

calculated– number of wells tabulated– water use volumes calculated

by aquifer – water use can be displayed by

map, symbolized or subtotaled by census block

• Strengths & Weaknesses of Data & Analysis– based on facility type, so a

leap of faith in assumed water use (per capita user or per facility size)

will update NCT map

Public Transient Non-Community

Kent PPT CHE FED FRE MIL COLC UNC UNK Total

Gals/yr

1,675,000

14,446,500

1,260,000

5,969,000

1,000,000

2,010,000

1,959,000

2,800,000

31,119,500

MGD 0.005 0.040 0.003 0.016 0.003 0.006 0.005 0.008 0.085

Well Count 4 16 3 9 1 3 6 4 46

Sussex FRE MIL ORA BLU MAN POC COLC UNC UNK Total

Gals/yr

2,525,000

2,860,000

1,030,000

60,000

1,100,000

25,263,666

24,418,833

52,771,000

2,751,500

112,780,000

MGD 0.007 0.008 0.003 0.000 0.003 0.069 0.067 0.145 0.008 0.309

Well Count 5 4 1 1 2 28 23 44 5 113

Kent+Sussex PPT CHE FED FRE MIL ORA BLU MAN POC COLC UNC UNK Total

Gals/yr

1,675,000

14,446,500

1,260,000

8,494,000

3,860,000

1,030,000

60,000

1,100,000

25,263,666

26,428,833

54,730,000

5,551,500

143,899,500

MGD 0.005 0.040 0.003 0.023 0.011 0.003 0.000 0.003 0.069 0.072 0.150 0.015 0.394

Well Count 4 16 3 14 5 1 1 2 28 26 50 9 159

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DomesticSelf-Supplied

• Total & County estimates by year– MGD– per person

• Map of Use By Block • Table of Use By Aquifer• Strengths & Weaknesses

of Data & Analysis– complete inventory of all

active wells not available– census-based water-use

coefficient is calibrated to public domestic use

Domestic Self-SuppliedKent1,546,648,769 gallons/yr = 4.24 MGD60,604 self-supplied residents69.9 gals/pp/day

Sussex 2,690,000,000 gallons/yr = 7.37 MGD96,451 self-supplied residents (plus up to 15,339 average

non-resident population in self-supplied housing in summer)

76.4 gals/pp/day

Domestic Water Use Census Block Totals on Pivot

Domestic Self-Supplied

Kent PPT RAN CHE FED FRE MIL ORA BLU COLC UNC Total

Gallons 69,334,051

31,074,968

236,148,160

56,375,442

72,318,972

33,450,555

1,560,151

10,394,432

28,499,827 1,007,493,785 1,446,241,324

MGD 0.190 0.085 0.647 0.154 0.198 0.092 0.004 0.028 0.078 2.760 3.96

Percent 4.8 2.1 16.3 3.9 5.0 2.3 0.1 0.7 2.0 69.7

Sussex CHE FED FRE MIL ORA BLU MAN POC COLC UNC Total

Gallons 2367688.981 527600.3932 24623640.96 17846720.59 4025907.085 4048993.959 104657505.8 166550668.6 552609112.5 1812726044 2,689,983,883

MGD 0.006 0.001 0.067 0.287 0.049 0.011 0.011 0.456 1.514 4.966 7.370

Percent 0.1 0.0 0.9 0.7 0.1 0.2 3.9 6.2 20.5 67.4

Kent + Sussex RAN PPT CHE FED FRE MIL ORA BLU MAN POC COLC UNC Total

Gallons 31,074,968 69,334,051

238,515,849 56,903,043 96,942,613 51,297,276

5,586,058 14,443,426

104,657,506

166,550,669

581,108,939 2,820,219,829 4,136,225,207

MGD 0.085 0.190 0.653 0.156 0.266 0.141 0.015 0.040 0.287 0.456 1.592 7.727 11.332

Percent 0.8 1.7 5.8 1.4 2.3 1.2 0.1 0.3 2.5 4.0 14.0 68.2

unconfined aquifer is largest source, supplying more than 2/3 of domestic self-supplied water

Groundwater Use TotalsSo, these results allow us to chop-slice-and-dice water use data/estimates from many angles

• Project Total• County Totals• By Block• By Aquifer• By Use• By Year

USE Kent MGD

Sussex MGD

Total MGD

Public Reported (high use yr) 11.0 15.2 26.2

Public Reported (low use yr) 10.1 12.7 22.8

Public Non-Reported (estimated) 0.58 1.23 1.81

Domestic self-supplied (model) 4.24 7.37 11.61

Industrial self-supplied (high use yr) 1.35 6.96 7.66

Industrial self-supplied (low use yr) 0.83 5.56 6.66

Irrigation: Ag (model high use 2007) 19.12 71.69 90.82

Irrigation: Ag (model low use 2006) 5.62 44.53 50.16

Irrigation: Golf Course (median rpt+est) 0.17 2.00 2.17

Ag: Lawn wells (estimated) 0.008 0.022 0.03

Ag: Livestock (estimated) 0.7 3.6 4.3

Total (high end) 37.2 108.1 144.6Total (low end) 22.2 77.0 99.5

Groundwater Use TotalsSummary by Aquifer

MTL RAN PPT CHE FED FRE MIL MCH UCH MAN POC COLC UNC UNK

0.02 0.12 1.52 0.58 2.57 1.18 1.38 0.77 7.75 7.06 10.86 57.12 Irrigation (2007)

0.02 0.04 0.08 0.02 0.22 0.08 0.04 0.14 0.26 1.04 2.36 4.3 Livestock

0.03 Lawn (self-supp)

2.75 Golf

0.04 0.21 3.621 3.758 1.005 2.035 0.599 0.136 1.92 3.947 2.66 6.185 Public Reported(2007)

0.008 0.266 0.024 0.073 0.184 0.018 0.019 0.167 0.127 0.262 0.291 0.064 Community NR

0.023 0.005 0.003 0.011 0.005 0.002 0.016 0.015 0.03 0.006 Non-Community Non-Transient

0.005 0.04 0.003 0.023 0.011 0.003 0.003 0.069 0.072 0.15 0.015 Non-Community Transient

0.085 0.19 0.653 0.156 0.266 0.141 0.015 0.04 0.287 0.456 1.592 7.727 Domestic Self Supplied

0.02 0.54 0.02 0.89 2.17 0.02 3.69 Industrial (2007)

0.06 0.38 4.05 6.80 2.01 5.06 2.16 1.42 1.11 11.28 14.89 17.84 82.27 0.085 Total MGD

0.04 0.25 2.71 4.55 1.35 3.39 1.45 0.95 0.74 7.55 9.96 11.94 55.07 0.06 Percentage

preliminary sum of maximum estimates

Groundwater Use Totals

By Census Block• Tabular Form• Map Form

Summary and Wrap-Up

Starting Premise

Accurate Understanding of Aquifer Geology

is essential toAccurate Understanding of Groundwater Occurrence

Geology controls where the groundwater is, where it goes, and how much we get

• Understanding Aquifers. We started with identification of aquifers in boreholes and then mapping aquifers in Kent and Sussex Counties

• Tabulating Water Use. We brought water use into the picture by tabulating all records of water use from Kent and Sussex Counties, and by estimating water use where complete, high-quality data were not available

• Identify Groundwater Sources. We identified the sources of public drinking water (and water for other uses) by projecting well screen depths onto digital aquifer grids

For Kent and Sussex Counties, this project highlightswhere Source Water Protection intersects Geology

• Protection. The results will contribute to accurate delineation of these public water supply resources, and potential groundwater flow pathways, to support source water protection efforts in Delaware

• Permits. The geologic products will also support identification of aquifers for well permitting

• Planning. The water use products will be useful for water supply planning efforts, such as the current Kent-Sussex focus of Delaware’s Water Supply Coordinating Council

Benefits

Thank you

Funding by: