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Virginia Groundwater Availability Issues. AQUIFERS YORKTOWN-EASTOVER PINEY POINT AQUIA. MARINE SEDIMENTS. FLUVIAL SEDIMENTS. POTOMAC AQUIFER. BASEMENT BEDROCK. VA Coastal Plain Aquifer Cross-Section. McFarland & Bruce, 2006. Proportional Drawdown from Pre-Pumping Levels. WEST.
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AQUIFERS • YORKTOWN-EASTOVER • PINEY POINT • AQUIA MARINE SEDIMENTS FLUVIAL SEDIMENTS POTOMAC AQUIFER BASEMENT BEDROCK
VA Coastal Plain Aquifer Cross-Section McFarland & Bruce, 2006
Proportional Drawdown from Pre-Pumping Levels WEST EAST +150 +140 100% PRE-PUMPING LEVEL FRANKLIN +100 80% +50 MSL +30 D I P PRESENT-DAY LEVEL 77% POTOMAC AQUIFER -180 -250
Simulated Change in Storage of Water in the Potomac Aquifer from Pre-development to 2008 Values >1 indicate head is below the 80% criterion
Groundwater Storage Calculations Loss of compressible storage within calculation area Expressed as a percent of storage available above 80% criterion levels September, 2011
Simulated Water Levels Aquifer: Piney Point Scenario : 3 Mode : Steady State End Date : - Pumping : Permitted VA Wells - Reported 2008 rates (90.4 Mgal/d) Franklin Wells - Reported 2008 rates (33.3 Mgal/d) Water Level Ft (MSL) > 160 140 to 160 120 to 140 100 to 120 80 to 100 60 to 80 40 to 60 20 to 40 0 to 20 -20 to 0 -40 to -20 -60 to -40 -80 to -60 -100 to -80 -120 to -100 -140 to -120 -160 to -140 < -160 • Notes: • NC and MD wells at 2005 rates • Estimated domestic withdrawals at 2008 rates • Water levels vertically averaged over full aquifer thickness • Permitted VA wells include Franklin wells 80% Criterion Violations Dewatered Cells 20’ contour September, 2011
Simulated Water Levels Aquifer: Aquia Scenario : 3 Mode : Steady State End Date : - Pumping : Permitted VA Wells - Reported 2008 rates (90.4 Mgal/d) Franklin Wells - Reported 2008 rates (33.3 Mgal/d) Water Level Ft (MSL) > 160 140 to 160 120 to 140 100 to 120 80 to 100 60 to 80 40 to 60 20 to 40 0 to 20 -20 to 0 -40 to -20 -60 to -40 -80 to -60 -100 to -80 -120 to -100 -140 to -120 -160 to -140 < -160 • Notes: • NC and MD wells at 2005 rates • Estimated domestic withdrawals at 2008 rates • Water levels vertically averaged over full aquifer thickness • Permitted VA wells include Franklin wells 80% Criterion Violations Dewatered Cells 20’ contour September, 2011
Simulated Water Levels Aquifer: Potomac Scenario : 3 Mode : Steady State End Date : - Pumping : Permitted VA Wells - Reported 2008 rates (90.4 Mgal/d) Franklin Wells - Reported 2008 rates (33.3 Mgal/d) Water Level Ft (MSL) > 160 140 to 160 120 to 140 100 to 120 80 to 100 60 to 80 40 to 60 20 to 40 0 to 20 -20 to 0 -40 to -20 -60 to -40 -80 to -60 -100 to -80 -120 to -100 -140 to -120 -160 to -140 < -160 • Notes: • NC and MD wells at 2005 rates • Estimated domestic withdrawals at 2008 rates • Water levels vertically averaged over full aquifer thickness • Permitted VA wells include Franklin wells 80% Criterion Violations Dewatered Cells 20’ contour September, 2011
Simulated Water Levels Aquifer: Piney Point Scenario : 4 Mode : Steady State End Date : - Pumping Rates : Permitted VA Wells - Total Permitted 2005 (165.5 Mgal/d) Franklin Wells - Total Permitted 2005 (37.8 Mgal/d) Water Level Ft (MSL) > 160 140 to 160 120 to 140 100 to 120 80 to 100 60 to 80 40 to 60 20 to 40 0 to 20 -20 to 0 -40 to -20 -60 to -40 -80 to -60 -100 to -80 -120 to -100 -140 to -120 -160 to -140 < -160 • Notes: • NC and MD wells at 2005 rates • Estimated domestic withdrawals at 2008 rates • Water levels vertically averaged over full aquifer thickness • Permitted VA wells include Franklin wells 80% Criterion Violations Dewatered Cells 20’ contour September, 2011
Simulated Water Levels Aquifer: Aquia Scenario : 4 Mode : Steady State End Date : - Pumping Rates : Permitted VA Wells - Total Permitted 2005 (165.5 Mgal/d) Franklin Wells - Total Permitted 2005 (37.8 Mgal/d) Water Level Ft (MSL) > 160 140 to 160 120 to 140 100 to 120 80 to 100 60 to 80 40 to 60 20 to 40 0 to 20 -20 to 0 -40 to -20 -60 to -40 -80 to -60 -100 to -80 -120 to -100 -140 to -120 -160 to -140 < -160 • Notes: • NC and MD wells at 2005 rates • Estimated domestic withdrawals at 2008 rates • Water levels vertically averaged over full aquifer thickness • Permitted VA wells include Franklin wells 80% Criterion Violations Dewatered Cells 20’ contour September, 2011
Simulated Water Levels Aquifer: Potomac Scenario : 4 Mode : Steady State End Date : - Pumping Rates : Permitted VA Wells - Total Permitted 2005 (165.5 Mgal/d) Franklin Wells - Total Permitted 2005 (37.8 Mgal/d) Water Level Ft (MSL) > 160 140 to 160 120 to 140 100 to 120 80 to 100 60 to 80 40 to 60 20 to 40 0 to 20 -20 to 0 -40 to -20 -60 to -40 -80 to -60 -100 to -80 -120 to -100 -140 to -120 -160 to -140 < -160 • Notes: • NC and MD wells at 2005 rates • Estimated domestic withdrawals at 2008 rates • Water levels vertically averaged over full aquifer thickness • Permitted VA wells include Franklin wells 80% Criterion Violations Dewatered Cells 20’ contour September, 2011
Pre-Development Flow ~ Potomac Aquifer CRATER 0 FT 140 FT
Post-Development Flow (2003) ~ Potomac Aquifer -180 FT CRATER 0 FT -180 FT
Saltwater Intrusion – Water Quality Changes McFarland, 2010, USGS Professional Paper 1772
Saltwater Intrusion Space / Time Relations HAMPTON ROADS FRANKLIN WEST POINT EPISODIC CONTINUOUS YEARS-DECADES UPCONING WEEKS-MONTHS REVERSIBLE LATERAL INTRUSION CENTURIES VERTICAL SCALE GREATLY EXAGGERATED
Groundwater Storage Calculation Drawdown Ft (MSL) For each model cell, changes in compressible storage are calculated by: Change in Storage = Specific Storage x Cell Volume x Change in Water Level Aquifer compaction and land subsidence are not simulated. • 100’ drawdown contour in the Potomac aquifer • defines area for storage calculations > 160 140 to 160 120 to 140 100 to 120 80 to 100 60 to 80 40 to 60 20 to 40 0 to 20 -20 to 0 -40 to -20 -60 to -40 -80 to -60 -100 to -80 -120 to -100 -140 to -120 -160 to -140 < -160 20’ contour September, 2011
Land Subsidence – Relative Sea-Level Rise Rates of Elevation Change (1940-1971) mm/year Holdahl and Morrison, 1974 Measurement of Compaction and Subsidence Suffolk Extensometer June 1982 – Dec. 1995 Depth = 484 m Chesapeake Bay West Point Franklin Extensometer Oct. 1979 – Dec. 1995 Depth = 255 m Major Pumping Centers Suffolk Miles Franklin 0 25
Projected Extent of Subsidence West Point INDUSTRIAL HAMPTON ROADS Franklin Suffolk
Scott Kudlas, Director Office of Surface and Ground Water Supply Planning (804) 698-4456 scott.kudlas@deq.virginia.gov http://www.deq.virginia.gov/watersupplyplanning/homepage.html