Groundwater
Overview of Groundwaterand Groundwater Contamination
Typical Design of a Production or Monitoring Well
Response of Water Table to Pumping of a Well
Cone of Depression: Drawdown of Water Table Near a Well
Capture Zone of a Pumping (Extraction) Well
Source of ContaminantPlume of contaminationWhat happens to water
quality at the well as plume enters the well?
Breakthrough with Finite Duration
Effect of Dispersion Caused by the Porous Medium (Soil)
Behavior of Non-Aqueous Phase (Immiscible) Liquids (NAPLs)
Methods for Pumping LNAPLS(NOT DNAPLs)
Retardation of Contaminants that Adsorb (Stick) to Soil
Particles
Retardation: Friend or Foe? Retardation slows the movement of
contaminants toward a use area, such as supply well.
BUT retardation also slows down removal via pump and treat
The Massachusetts Military Reservation (MMR)
Formerly: Otis Air Force Base/Camp EdwardsFalmouth, Cape Cod,
MA(Officially: Joint Base Cape Cod as of 7/13)
Groundwater Contamination from Fuels, Solvents, Ordnance and
from Wastewater Sludge
The Massachusetts Military Reservation (MMR)CERCLA
Site22,000-acre property
Has been used for military training activities since 1911
Located over a sole source aquifer
Provides drinking water for 200,000 year-round and 500,000
seasonal residents of Cape Cod.Main military activity started
1935
Primary mission: provide training and housing to Air Force
and/or Army units
Otis AFB closed in 1973 (Nixon): still used for National Guard
Otis AFB and Camp EdwardsHISTORYHistoric chemical/fuel spills
Fire training activities (chlorinated suppressants)
Landfills, and drainage structures.
Effluent from the former sewage treatment plant was historically
discharged into sand beds where it seeped into the
groundwater.1983-1984: Air Force detected volatile organic
compounds (VOCs) in on-site monitoring wells near the Base Landfill
and a Fire Training Area.
1984, the U.S. Geological Survey (USGS) detected contaminants in
monitoring wells downgradient of this former wastewater plant.
VOCs detected in several hundred private wells (all of which are
now on municipal water) and in one town well (now shut down).
The EPA has designated the Sagamore Lens underlying JBCC as a
sole source aquifer under the Safe Drinking Water Act.Final NPL
LISTING: November 1989 Groundwater is contaminated with VOCs TCE,
trichloroetheneDCE, dichloroethylenePCE, tetrachloroethylene,EDB,
ethylene dibromide (flame suppressant)Carbon tetrachloride(flame
suppressant)
EDB was found upwelling in two cranberry bogs, outside the MMR,
in Mashpee and Falmouth.
Soil contaminated with Heavy metalsPolycyclic aromatic
hydrocarbons (PAHs) Pesticides, PCBsPetroleum hydrocarbons
Contaminated soil was largely removed in cleanup actions in
2001-2002.Some shallow groundwater also contaminated by
sewage/sludge plume
Viral contamination
Nitrogen wastes (NH3 and NO3)
Surfactants (from detergents, personal care products)Federal
Facility Agreement (FFA) was signed in 1991 (amended in March 2000)
governing the Superfund cleanup.
Signatories include: National Guard Bureau, U.S. Air Force
EPA.
Since May 1996 Air Force Civil Engineer Center (AFCEC)
Installation Restoration Program is currently the lead agent under
the terms of the FFA.
Five year reviews have been conducted and issued in 1999, 2004,
2008 and 2013Some Cleanup Action Highlights:
1986: City water lines extended to residents on wells
1990: Interim removal of surface sludeges and wastes
1997: 10 extraction wells installed (pump & treat)
2000: Final ROD was signed on May 15: P&T, long term
monitoring
2002:
Unexploded Ordnance - UXOBombs, artillery, etc.
RDX is major contaminant
2005 Cleanup Actions:
2,800 cubic yards of soil,
8,500 ordnance items
27,000 pounds of munitions debrisUnexploded Ordnance -
UXORemediation of soil and groundwater implemented since the mid to
late 1990's.
~100,000 tons of soil have been treated at JBCC
Numerous groundwater treatment plants treat ~11.5 million
gallons per day (as of 01/15)
All treated groundwater is returned to the aquifer or discharged
to surface water.
