Byram Township NJDEP Matching Grant Groundwater Assessment

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Byram TownshipNJDEP Matching Grant Groundwater
Assessment

• John Robinson, PG, CPG
• Hydrogeologist
• GeoEnvironmental Research

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Project Tasks to Evaluate Byrams Water Resources

• Prepare Aquifer GIS Maps
• Gather Information
• Collect Baseflow stream samples
• Prepare Aquifer Testing Ordinance
• Prepare Report
• Prepare Educational Slide Show

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Topics of Discussion

• Geology and Groundwater Occurrence
• Aquifer Materials
• Groundwater Contamination
• Residential Well Testing

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Groundwater Occurrence

• Hydrologic Cycle
• Runoff and Recharge
• Recharge and Discharge
• Changes in the Water Table

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Precipitation may runoff, evaporate, percolate to
root zone, or enter aquifer. Water table changes
seasonally. Aquifers vary with geology
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Precipitation that enters the aquifer flows
directionally from recharge areas to discharge
areas. The constant flow of groundwater that
discharges into a stream is called baseflow.
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Baseflow water samples may be collected from
streams to evaluate the quality of the
discharging groundwater. Lubbers Run Upstream
Sample Location.
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Groundwater supply wells may alter the natural
flow groundwater. Pumping wells depress the
water table around the intake. The localized
decline is called a cone of depression. Water
drawn from a stream into a well through the
aquifer is called induced infiltration.
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Public Community Supply Wells
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This groundwater physical flow mode simulates the
recharge/discharge and baseflow of a stream
system. Water is added to the sides as recharge
and migrates to the middle (steam) as discharge.
Dye traces the groundwater flow paths.
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Shallow to deep flow paths migrate to the stream
as baseflow discharge.
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Groundwater physical model depicting injection
scenario common in septic systems. Notice
mounding and radiating flow paths that spread out
before reaching the water table.
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Groundwater flow concepts applied to typical
Wallkill Watershed aquifer. Water table occurs
as a subdued replica of the surface topography.
Notice the water table is deeper at the upland
watershed boundary and intersects the ground
surface at wetlands and streams. Town well may
draw from both groundwater and surface water.
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Physical model depicting flow to a well. Notice
the cone of depression and flow paths to the well
intake. Deeper flow paths may be influenced by
pumping but escape intake.
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Groundwater discharge from a bedrock outcrop.
Position of the water table surface is clearly
visible.
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Aquifer Materials

• Unconsolidated Deposits
• Bedrock
• Limestone and Karst

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Sand and gravel deposit in the Waterloo section
of Byram depicts the coarse grained and permeable
nature of glacial outwash aquifers.
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The Aquifers of Byram
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Glacial Sediments andSurfacial Aquifers
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Surficial Aquifers
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Buried valleys in the Northern NJ area were
formed by glaciers and the release of sediments
in the ice interacting and deposited with the
meltwater.
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Groundwater in bedrock aquifers flows through
interconnected fractures. Fractures close at
depth with increased lithostatic pressure. Wells
that miss the interconnected fracture network may
be dry.
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Bedrock Aquifers
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This fractured crystalline bedrock outcrop along
Lakawanna Road is typical of the upland areas of
the watershed. Notice the irregular occurrence
of the fracture network.
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Limestone outcrop along Route 15 in Sparta. This
type of bedrock is typical beneath the valleys in
the Wallkill Watershed. Notice the more regular
spaced and frequent bedding plane fractures.
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Limestone outcrop along Route 94 in McAfee.
Notice the soluble nature of limestone.
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Groundwater Recharge
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Soil filled vertical fracture in limestone.
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Quantitative Hydrogeology

• Groundwater and Baseflow
• Gradient and Hydraulic Conductivity
• Testing

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Seasonal changes in the water table is
accompanied with a change in gradient and volume
of baseflow.
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Aquifer yield is evaluated by conducting an
aquifer pump test. A controlled pumping stress
is applied to the aquifer and the results are
measured and interpreted.
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Pumping wells spaced too close together may
create cumulative drawdown.
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Groundwater Contamination

• Sources of Contamination
• Well Head Protection

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Contamination threats to groundwater are
everywhere. They may be organic, inorganic or
both. Each type reacts differently in the
subsurface.
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Organic chemicals, such as petroleum based fuel,
have a specific gravity less than water and float
on the water table. Their subsurface movement is
influenced by the direction of groundwater flow,
including the rising and falling of the water
table.
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Chlorinated organic chemicals, such as dry
cleaning fluid (TCE) and PCBs are denser than
water and sink to an impermeable layer. The
migration of dense non-aqueous phase liquids
(DNAPLS) is dictated by gravity, not the
direction of groundwater flow.
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In areas serviced by septic systems, delivery of
chemicals into the subsurface is as common as
going to the supermarket.
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Septic systems work by maintaining vertical
unsaturated separation of at least 4 feet between
the leach field and groundwater. In high volume
systems, the vertical separation is rarely
unsaturated.
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Septic Suitable Soils
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Karst aquifers have special problems. The
enhanced permeability created by solution makes
them exceptional aquifers. Unfortunately, this
characteristic also makes them extremely
vulnerable to contamination by run-off
short-circuiting through sinkholes.
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Contaminant Threats in Byram
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Well head protection identifies the ground
surface areas around wells which contribute to
direct recharge of the well.
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The commonly used arbitrary fixed radius method
of delineating well head protection areas is just
that - arbitrary. No thought is given to pumping
rates, aquifer properties or anything scientific.
Its use may be justified by political motives,
such as preserving current zoning.
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Calculated fixed radius is simplistic but
considers properties such as pumping rates.
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Well Head Protection Areas
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Known Contaminant Threats
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Things to Remember

• Groundwater is out of sight, but not mysterious
• Groundwater can be protected with thoughtful
  planning
• Runoff is episodic and baseflow is constant
• The landscape and movement of water and
  contaminants is dictated by underlying geology.

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Next Steps

• Collect Additional Well Information
• Implement Residential Well Ordinance
• Identify Vulnerable Environments
• Plan to protect Vulnerable Environments From
  contaminants and groundwater mining.