2/25/2016
SOURCES OF FRESH WATER IN THE
COASTAL PLAIN, AND ASSOCIATED
IMPACTS TO SOURCES
JAMES K. HOLLEY, P.G.
SENIOR HYDROGEOLOGIST
GROUNDWATER MANAGEMENT ASSOCIATES, INC.
ADJUNCT LECTURER – DEPARTMENT OF GEOLOGICAL SCIENCES - EAST CAROLINA UNIVERSITY
AND
DR. RICHARD K. SPRUILL, PH.D., P.G.
PRINCIPAL HYDROGEOLOGIST
GROUNDWATER MANAGEMENT ASSOCIATES, INC.
ASSOCIATE PROFESSOR – DEPARTMENT OF GEOLOGICAL SCIENCES – EAST CAROLINA UNIVERSITY
HOW DO WE DEFINE FRESH WATER?
FRESH WATER
• TOTAL DISSOLVED SOLIDS (TDS) <500 mg/L (NC GW QUALITY STANDARDS)
• CHLORIDE CONCENTRATION <250 mg/L (NC GW QUALITY STANDARDS AND NATIONAL
SECONDARY DW STANDARD)
BRACKISH WATER
• TDS >500 mg/L and <35,000 mg/L
SALT WATER
• TDS >35,000 mg/L
1
2/25/2016
BEST USE OF FRESH
WATER!
WHAT ARE THE FRESH-WATER SOURCES
OF THE NORTH CAROLINA COASTAL PLAIN?
GROUNDWATER
SURFACE WATER
ULTIMATELY SOURCED
FROM PRECIPITATION
2
2/25/2016
GENERALIZED CROSS SECTION OF NC
General Geologic
Map of NC
A
A’
Source USGS http://nc.water.usgs.gov/albe/maps/NCxsect.jpg
Source: Ralph Heath, 1983, “Basic Ground-Water Hydrology, USGS Water-Supply Paper 2220
3
2/25/2016
Source: Ralph Heath, 1983, “Basic Ground-Water Hydrology, USGS Water-Supply Paper 2220
Ghyben-Herzberg Principle
Source: Ralph Heath, 1983, “Basic Ground-Water Hydrology, USGS Water-Supply Paper 2220
4
2/25/2016
Recharge and
Discharge in
Coastal Plain
Aquifers
From Barlow, 2003
5
2/25/2016
Central Coastal Plain Capacity Use Area Zones
6
2/25/2016
7
2/25/2016
8
2/25/2016
9
2/25/2016
10
2/25/2016
11
2/25/2016
9
ABR
8
7
25%
Withdrawal (MGD)
6
5
50%
4
3
75%
2
1
CCPCUA Rule-Based Reductions
0
0
2
4
6
8
10
12
Time (Years)
14
16
18
20
12
2/25/2016
Good confinement and
Lower Permeability
Enhanced Recharge
Results in Broad
Transition Zones
Leaky Aquifer with
Higher Permeability
From the NCDWR’s Central Coastal Plain Capacity Use Area Status Report 2009
Point Sources of Saltwater Intrusion
13
2/25/2016
Fresh Recharge
Fresh Recharge
Fresh Recharge
Local
Saltwater
Intrusion
SURFACE WATER
• HAS BECOME INCREASINGLY RELIED UPON FOR DRINKING WATER
IN THE NC COASTAL PLAIN
oNRWASA
oGUC
oMARTIN COUNTY
14
2/25/2016
SURFACE WATER CHALLENGES AND RISKS
• EXTENSIVE TREATMENT (FOR TURBIDITY, NUTRIENTS, BACTERIA, CHEMICALS, MANGANESE, ETC.)
• VARYING TEMPERATURE (CREATES CHALLENGES FOR CHEMICAL FEEDS)
• VARYING DISCHARGE VOLUMES (LIMITS AVAILABLE SUPPLY DURING DROUGHTS)
• IN COASTAL AREAS, MAY BE VULNERABLE TO SALTWATER INTRUSION
• MORE EXPENSIVE TO DEVELOP AND TREAT THAN GROUNDWATER
• OFTEN IS ABLE TO MEET LARGER WITHDRAWALS MORE EFFECTIVELY THAN GROUNDWATER
SUPPLIES
Location
of GUC’s
surface water
treatment
plant,
groundwater
production
wells, and
ASR System
No. 1
15
2/25/2016
16
2/25/2016
Historic Migration of Salt Wedge
WHAT ARE SOME ALTERNATIVES FOR THE FUTURE OF
FRESH WATER IN THE NC COASTAL PLAIN?
• EXPAND USAGE OF BRACKISH GROUNDWATER (WITH RO)
• ACTIVE QUARRIES AND RECLAIMED QUARRY LAKES
• AQUIFER STORAGE RECOVERY
17
2/25/2016
Onslow
Quarry
BELGRADE QUARRY
18
2/25/2016
LARGE MINE OPERATIONS IN EASTERN NC
AQUIFER
STORAGE
RECOVERY
Innovative water
management strategy
to store pre-treated
water underground
and recover the water
during times of need.
19
2/25/2016
Questions?
20