WEBVTT

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 NARPM
presents Tools for Estimating
Groundwater

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Flux to Surface Water. I'm going

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to turn things over to your
official session presenter
Robert Ford from

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U.S. EPA Office of Research and
Development. I

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will pull up the materials and
you can feel free

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to begin.

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Spark thank you --

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>> Thank you P thank you for
sharing

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our experience at Superfund
Site's. For simplicity

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I will be the only speaker for
the presentation slides although
Steve,

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Bob and Randall are all
participating this has been

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a team effort and they are
available to address questions
and

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provide additional insight
during the discussion

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period, later. We are with the
EPA and we are here

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to help. My plan for this
presentation is to address three

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objectives first to provide
context for why we would want to
evaluate

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water and contaminant Fox.
Second, to highlight a selection
of tools

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that are useful for care to
rising the pathway from
groundwater

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surface water and providing a
case study example to illustrate
data

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drive from implementing these
tools. We

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also should be familiar with the
phrase water flows downhill for

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groundwater this translates into
water flows in the direction of

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decreasing hydraulic head it's
illustrated by the

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blue flowline superimposed over
a map of the

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contoured hydraulic head for
cross-sectional area through

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an aquifer. That shows the types
of flow paths that groundwater
may

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take towards the surface water
body. For contaminated sites

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these flow paths provide routes
for contaminants that event or
the

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aquifer to reach down gradient
surface water bodies. When

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this occurs contaminant impacts
may be observed in the sediments

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and surface water. A common
question that managers must

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frequently address is
determining whether there's a
hydraulic connection

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between contaminated groundwater
and surface water bodies the
board

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of the site.

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From the perspective of the
surface water body we want to

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successfully identify and track
contaminated groundwater
discharge

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through the surface water
transition zone. This can be
challenging due

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to spatial and time dependent
variations that influence the
magnitude and

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direction of exchange flow. A
sole focus was out -- without

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knowledge of its connection can
result in mischaracterization of

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the problem and selection of
remedial approaches that are
ultimately

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not successful.

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I will now introduce several
approaches we are applying to
characterize

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the flow system connecting the
upland groundwater to down
gradient

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surface water systems. Different
methods are applied

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for the two portions of the flow
path and I will start by
discussing

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characterization of the upland
groundwater system. Some things

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have not changed. We are still
dependent

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on installation of monitor wells
and bizarre matters these are

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still the primary vehicles by
which we determine groundwater
elevation

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to assess flow direction,
determine hydraulic properties
and collect

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water samples to define the
extent of contamination. With
the network

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of wells or piezometers we can
develop

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a large-scale understanding of
the groundwater flow system and
we

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can target our hydraulic
characterization to smaller

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areas within the aquifer by
examining subsets of the
network.

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And upland area adjacent to a
surface water is where a simple
modeling

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tool recently developed by ORD
called 3PE can be

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useful.

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In September 2014 ORD published
a report

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in spreadsheet tool to
facilitate calculations of
groundwater

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flow gradient and direction from
data collected from free wells
or

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bizarre matters the report
serves as a users manual as well
as providing

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technical guidance for
appropriate use of the tool. The
model

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name 3PE stands for 3 point
estimator it implements a
three-point mathematical

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solution to calculate horizontal
direction and magnitude of

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groundwater flow this approach
is applicable for portions of
the surface

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that are planar the input is --
known information about

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the Monterey -- monitoring
points along with estimated or
measured

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properties of the aquifer within
the triangle

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your area -- this slide displays
a screenshot from

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a portion of the data entry and
outputs within a worksheet. I've

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highlighted three areas on the
worksheet with red

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outlines. The top outline
highlights the user input for
monitor well

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or piezometer locations the
middle outline highlights entry
fields

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were estimated or measured
aquifer properties. The

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bottom line highlights entry
fields for groundwater
elevations in each

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well or piezometer and
measurement date the user has
the option of

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making multiple data entries for
extended periods

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of time. The 3PE workbook
includes

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multiple worksheets for
graphical presentation of the
calculation

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output. Included on the slider
screenshots for two of these
graphs.

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The left graph shows the trend
in the calculated magnitude and
direction

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of a hydraulic gradient which is
useful for assessing changes

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over time. The right graph shows
the direction of the calculated

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gradient and groundwater
velocity for a single time or

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given time. Ultimately, this
calculation tool provides a
quick way to evaluate

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time-dependent changes in the
magnitude and direction of

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groundwater flow.

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We will now shift our tools
discussion to the surface

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water bodies with focus on the
groundwater surface water

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transition zone. I will start

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by highlighting a range of tools
that function

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to provide qualitative
understanding of what might be
occurring within

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our across the transition zone.

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These tools range from our own
visual observations of specific
features

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that may be indicators of
contaminated groundwater
discharge to instrument

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measurements that respond to

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chemical or physical
characteristics within

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water or sediment. These tools
do not

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specifically define the
magnitude of contaminant
discharge into the

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surface water body but they
provide a critical first step in
defining

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the extent of the problem and
help guide selection of
subsequent site

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characterization measurements.

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Here I've highlighted several
published resources that provide

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useful information on issues to
consider in assessing the impact

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of contaminated groundwater
discharge.

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Including discussions of various
site characterization approaches

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and tools. They also include
descriptions of specific

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sites that may provide useful
perspective for your

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own site.

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A critical step for
characterizing contaminant flux
across the

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groundwater surface water
transition so is quantifying the
Maddock to

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fight of extension flow. There

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are a range of approaches that
can be employed depending on
physical

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characteristics of that surface
water body. These tools range
from

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direct measurements of flow
gradient or volume too simple or
complex

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flow models. All have their
strengths and weaknesses. For
this

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presentation I want to focus on
the technique of

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using sediment temperature
profile measurements to quantify
the magnitude

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and direction of seepage

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flux. In December 2015 ORD
published a report providing a
technical review

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of the technology and guidance
on its application for the
groundwater

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surface water transition zone.
The report provided illustration

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of the use of a
spreadsheet-based calculation
tool to estimate the

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magnitude and direction of
seepage flux based on sediment

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temperature measurements.

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The theoretical basis for
implementing seepage

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flux calculation using heat flux
metals has been around for
decades

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it's not a new technology. In
recent years

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others have developed modeling
programs in

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freeware format or as free
plug-ins or add-ins for

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commercial software programs. We
now have available to us a wide

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variety of commercial devices to
measure temperature within
intact

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sediment as well as other
properties needed as input
parameters for

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existing models. We will first
examine the technical basis

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underpinning heat flux models.
Shown here is a graphic

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adapted from prior published
work.

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The goal of heat flux modeling
is to replicate a measured
sediment

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temperature profile based on two
processes. Heat conduction and

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heat advection. Heat conduction
is like the process of

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mass diffusion and is in the
direction from hot areas to
colder areas within

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the sediment. Heat convection is
like advection

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and is due to the flow of water
through the sediment. The final

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shape of the sediment
temperature profile is
influenced

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by the magnitude and direction
of that

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water flow.

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>> I have to stop you. We are
going to

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hide something and I noticed the
problem with your graphic which

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I have fixed. Bear with me I
want to get that there so you

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can continue. I apologize for

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the interruption.

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Feel free to carry on.

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>> Thank you. This slide
illustrates

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the types of sediment
temperature profiles that can
develop during

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a typical summer as a function
of

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water exchange with the surface
water body and an upward or
downward

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direction. The upward or
discharge direction is shown on

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the left and the downward or
recharge direction is

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on the right. Since he'd
conduction is influenced by

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static sediment properties this
allows us to estimate their
direction

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and magnitude of water flow that
would result in the observed
sediment

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temperature profile.

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There are two general types of
seepage flux models for which

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analytical solutions have been
derived.

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Steady-state models are based on
replicating the gradient of the

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sediment temperature profile and
require temperature measurements

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from three depths. Transit
models are based

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on replicating the
characteristics of the
propagation of daily or diurnal

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temperature cycles through the
sediment. They depend on changes

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in both the amplitude and timing
or phase shift of the

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daily cycle.

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The graphic on this slide
illustrates the two types of
sediment 10 motor

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data collected to support the
two types of calculations.

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The left side illustrates the
temperature profile typically
observed

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as a function of depth when --
within a sediment

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at any given time. The right
side of the graphic illustrates

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the time variable temperature
signature observed as a function
of depth

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over several days. The arrows
point out the daily peak
temperature

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that occurs each day which
decreases in amplitude and
shifts

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in time as that signal moves
down through

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the sediment.

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We have used some existing
freeware

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models available but our
personal experience using

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the technology has prompted us
to develop our own
spreadsheet-based

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models to allow use of a greater
array of analytical solutions

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to make best use of the types of
temperature data collected. Two

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types of spreadsheet-based work
techs have been developed to

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implement two versions of the
steady-state and transient

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analytical solutions that are
most widely recognized in the

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scientific literature. The
primary output from these models
is seepage

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flux which is essentially
equivalent to

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Darcy Flux or specific discharge
for

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groundwater applications.

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This slide shows a screen
capture from implementation

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of one of the steady-state
analytical solutions of the heat
flux equation

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-- equation it includes assumed
or measured

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properties of the sediment and
measured temperatures within the
sediment

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and the relative depth spacing
of the temperature sensors
within the

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sediment. All of these have been
outlined with red outlines once

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input data is entered the user
clicks

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on the calculate seepage button
to implement built in
mathematics

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that calculate both the
direction and magnitude of
seepage flux that

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results in the observed sediment
temperature

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profile distribution.

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This slide shows a screen

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capture from implementation of
one of the transient
mathematical

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solutions for replicating the
amplitude reduction and/or phase
shift of

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the diurnal temperature
signature as it propagates down
to the sediment.

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For this model one need
sufficient number of temperature

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measurements within a 24-hour
period to allow the model to

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adequately fit a diurnal he
varying temperature signal for
two depths

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like the steady-state model the
user needs to input information

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about the sediment, depth
spacing and 12 temperature

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measurements for a 24 hour
period.

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The pictures on this slide
illustrate one of the
commercially

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available temperature samplers
-- that we use along with

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a homemade device for inserting
the protected sensors

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into sediment. These sensitive
good accuracy and sensitivity,
good battery

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life and nonvolatile memory to
allow deployment for extended

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periods of time. Our typical
approach is to install three

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or more sensors at different
depths for multiple locations
within a

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monitored area and allow them to
continuously log sediment
temperatures

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for a period of several months.

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Installation and retrieval can
be accomplished in days. Once
retrieved

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we download the temperature data
for input into the spreadsheet

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work book tools.

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This slide illustrates what
those temperature data look

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like for a given location. On
the left is a graph of
temperature data

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for several sensor depth over an
extended period of time. Each
day

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of logged temperature data at
two depths with would be input

306
00:16:51.934 --> 00:16:53.200
into one transit model.

307
00:16:53.200 --> 00:16:59.000
Likewise, each individual
measurement interval generates a
depth dependent

308
00:16:59.000 --> 00:17:04.000
temperature profile illustrated
on the

309
00:17:04.000 --> 00:17:08.000
right which is input into one of
the steady-state models. This
shows

310
00:17:08.000 --> 00:17:10.000
you the advantage of using
temperature sensors that have

311
00:17:10.000 --> 00:17:18.000
built-in nonvolatile memory over
which you can log extended
periods

312
00:17:18.000 --> 00:17:24.000
of time.

313
00:17:24.000 --> 00:17:27.000
We are going to segue into the
case study portion

314
00:17:27.000 --> 00:17:30.000
of the presentation at this
juncture I want to provide
context and who

315
00:17:30.000 --> 00:17:34.000
is taking the lead for the areas
of technical

316
00:17:34.000 --> 00:17:38.934
issues. Primary responsibilities
for Steve have been development

317
00:17:38.934 --> 00:17:41.934
of best practices and he was
involved

318
00:17:41.934 --> 00:17:47.934
in the development of the three
PE -- 3PE workbook

319
00:17:47.934 --> 00:17:50.934
to my responsibility is
developing best practices for
data

320
00:17:50.934 --> 00:17:57.000
collection to support seepage
flux calculations. Bob has led
development

321
00:17:57.000 --> 00:18:01.000
work book tools. Randall was
involved in development

322
00:18:01.000 --> 00:18:06.000
of the 3PE workbook tool and is
leading development of equipment

323
00:18:06.000 --> 00:18:08.000
to deploy sediment temperature
sensors and a way to

324
00:18:08.000 --> 00:18:14.000
help ensure reliable collection
of

325
00:18:14.000 --> 00:18:17.000
usable data.

326
00:18:17.000 --> 00:18:20.000
In the previous slide I
referenced development

327
00:18:20.000 --> 00:18:25.000
of backs -- best practices
during the

328
00:18:25.000 --> 00:18:29.000
progression of the work we've
developed standard

329
00:18:29.000 --> 00:18:31.000
operating procedures to
facilitate the data collection
efforts. For

330
00:18:31.000 --> 00:18:34.000
understanding upland groundwater
hydraulics these procedures
range

331
00:18:34.000 --> 00:18:37.934
from those to ensure measurement
of accurate elevations for

332
00:18:37.934 --> 00:18:43.934
wells or piezometers to best
practices to ensure

333
00:18:43.934 --> 00:18:45.934
accurate measures. All the
listed measurement procedures

334
00:18:45.934 --> 00:18:50.934
address potential sources of air
that must be minimized. This is

335
00:18:50.934 --> 00:18:59.000
all underpinned by the
presumption the various wells
and

336
00:18:59.000 --> 00:19:03.000
piezometer have been constructed
and developed in a manner to
ensure

337
00:19:03.000 --> 00:19:10.000
they represent the actual
aquifer condition.

338
00:19:10.000 --> 00:19:13.000
We also developed internal
procedures to support data
collection and calculation

339
00:19:13.000 --> 00:19:15.000
of seepage flux across the
groundwater surface water
transition zone C

340
00:19:15.000 --> 00:19:20.000
but these procedures are
developed to help

341
00:19:20.000 --> 00:19:24.000
collect data that are most
appropriate to support model

342
00:19:24.000 --> 00:19:25.334
calculations. Included

343
00:19:25.334 --> 00:19:28.000
procedures for direct
measurement of sediment

344
00:19:28.000 --> 00:19:33.000
thermal conductivity as well as
the direction and magnitude of
the

345
00:19:33.000 --> 00:19:38.934
vertical flow gradient. These
are all

346
00:19:38.934 --> 00:19:40.934
internal procedures that we are
happy to share them to assist

347
00:19:40.934 --> 00:19:49.934
development of your own
organizations standard
procedures.

348
00:19:49.934 --> 00:19:52.934
We now arrive at a point in the
presentation where

349
00:19:52.934 --> 00:19:56.000
I describe a case study to
illustrate application of these
tools and methods.

350
00:19:56.000 --> 00:20:01.000
This work was done to support an
initial site characterization
and

351
00:20:01.000 --> 00:20:06.000
designer remedy at the site into
then monitor the results and

352
00:20:06.000 --> 00:20:12.000
performance of that remedy.

353
00:20:12.000 --> 00:20:15.000
This case study we will present
as a specific operable

354
00:20:15.000 --> 00:20:20.000
unit at the Fort Devins
Superfund Site

355
00:20:20.000 --> 00:20:23.000
in Massachusetts. In this area
of the former military base
there is

356
00:20:23.000 --> 00:20:28.000
a landfill that was inherited
and used during the base
operations.

357
00:20:28.000 --> 00:20:33.000
It predated current landfill
construction requirements and
that said no lining

358
00:20:33.000 --> 00:20:36.000
edits bottom or collection
system.

359
00:20:36.000 --> 00:20:39.934
It has been capped to control
surface infiltration

360
00:20:39.934 --> 00:20:43.934
into waste materials. The
graphic on this slide
illustrates a period

361
00:20:43.934 --> 00:20:49.934
in its operation of waste
placement specific ugly --

362
00:20:49.934 --> 00:20:52.934
specifically 1952. Overlain with
a more recent

363
00:20:52.934 --> 00:20:57.000
assessment of the groundwater
hydrology as shown by the

364
00:20:57.000 --> 00:21:01.000
contra lines which are showing
the potential metric surface for
the

365
00:21:01.000 --> 00:21:04.000
groundwater table. Highlighted
in the upper right portion of
the

366
00:21:04.000 --> 00:21:09.000
aerial photograph is an area
occupied by a

367
00:21:09.000 --> 00:21:12.000
recreational lake that abuts the
landfill. Within this part of
the

368
00:21:12.000 --> 00:21:16.000
image is a portion of the lake
referred to as Red Cove which is
a focus

369
00:21:16.000 --> 00:21:20.000
of subsequent slides. In short
contamination of groundwater
occurred under

370
00:21:20.000 --> 00:21:26.000
the landfill and impacts to the
Red Cove area of the adjacent
lake

371
00:21:26.000 --> 00:21:32.000
appear to be occurring. To help
the

372
00:21:32.000 --> 00:21:34.000
region one office pin down the
specifics

373
00:21:34.000 --> 00:21:39.934
of contaminated groundwater
impacts to the lake

374
00:21:39.934 --> 00:21:43.934
ORD initiated a field-based
characterization effort. It was

375
00:21:43.934 --> 00:21:45.934
centered on the Red Cove area of
the lake and it included
installation

376
00:21:45.934 --> 00:21:50.934
of a monitoring network to
assess groundwater hydrology and
chemistry

377
00:21:50.934 --> 00:21:56.000
adjacent to the Cove, flow
gradient and seepage flux within
the Cove

378
00:21:56.000 --> 00:22:00.000
and surface water in sediment
chemistry also in the Cove.

379
00:22:00.000 --> 00:22:06.000
Earlier screening led by Bill
Brandon in region 1 identified
the

380
00:22:06.000 --> 00:22:10.000
cold shoreline had a temperature
signal anomaly that appeared to

381
00:22:10.000 --> 00:22:15.000
be tied to groundwater
discharge. For

382
00:22:15.000 --> 00:22:19.000
the adjacent upland groundwater
a series of vertically nested

383
00:22:19.000 --> 00:22:23.000
piezometers were installed to
support hydrology and

384
00:22:23.000 --> 00:22:27.000
chemistry measurements.
Ultimately, these monitoring
locations allowed

385
00:22:27.000 --> 00:22:33.000
us to conduct flow net analysis
to assess the spatial

386
00:22:33.000 --> 00:22:38.934
and temporal distribution of
groundwater discharge to

387
00:22:38.934 --> 00:22:41.934
the Cove.

388
00:22:41.934 --> 00:22:44.934
By combining this hydrologic
information with measurement

389
00:22:44.934 --> 00:22:46.934
of groundwater chemistry we
mapped

390
00:22:46.934 --> 00:22:50.934
out the distribution of a
contaminant discharge to the

391
00:22:50.934 --> 00:22:54.000
Cove. While elevated arsenic
concentrations were observed
throughout the up

392
00:22:54.000 --> 00:22:58.000
gradient perimeter of the Cove
the primary arsenic

393
00:22:58.000 --> 00:23:03.000
flux was detected along the
southwest perimeter of the Cove.
This information

394
00:23:03.000 --> 00:23:05.000
helped us pinpoint the most
likely point

395
00:23:05.000 --> 00:23:13.000
of origin within the landfill.
Arsenic knish -- contamination

396
00:23:13.000 --> 00:23:17.000
was primarily derived along a
flow path originating from a
Southwest

397
00:23:17.000 --> 00:23:26.000
direction from within the
landfill.

398
00:23:26.000 --> 00:23:30.000
Here are pictures that give a
visual perspective of the

399
00:23:30.000 --> 00:23:35.000
outcome of this contaminated
groundwater discharge. The

400
00:23:35.000 --> 00:23:37.000
picture on the left provides a
view of the entire Cove while
the picture

401
00:23:37.000 --> 00:23:39.934
on the right provides a closer
view at the middle of the Cove.
The reddish

402
00:23:39.934 --> 00:23:43.934
orange coloration that dominates
these views is due to the
discharge

403
00:23:43.934 --> 00:23:47.934
of reduced iron in groundwater
that precipitates as an iron
oxide

404
00:23:47.934 --> 00:23:54.000
upon contact with oxygen in
surface water. The reduced
mobile

405
00:23:54.000 --> 00:23:58.000
form of dissolved iron is
present in groundwater due to
the reducing

406
00:23:58.000 --> 00:24:00.000
conditions underneath the
landfill.

407
00:24:00.000 --> 00:24:03.000
The same conditions also drive
the transport of elevated
arsenic concentrations.

408
00:24:03.000 --> 00:24:07.000
During precipitation majority of
the arsenic from

409
00:24:07.000 --> 00:24:13.000
groundwater discharged is
captured by the iron

410
00:24:13.000 --> 00:24:19.000
oxide participants. They deposit
onto

411
00:24:19.000 --> 00:24:23.000
the sediments. While the entire
Cove appears to be reddish
orange,

412
00:24:23.000 --> 00:24:26.000
this does not mean the
contaminated groundwater

413
00:24:26.000 --> 00:24:31.000
discharge is uniformly
distributed throughout the Cove.
To illustrate

414
00:24:31.000 --> 00:24:34.000
this I provide a snapshot of
some of the seepage flux
measurements

415
00:24:34.000 --> 00:24:39.000
that were conducted at multiple
locations within

416
00:24:39.000 --> 00:24:42.000
the Cove. Two of these
temperature profile locations
were adjacent

417
00:24:42.000 --> 00:24:46.000
to shallow piezometers
installations the

418
00:24:46.000 --> 00:24:50.000
temperature profile measurements
revealed actual seepage flux
varied

419
00:24:50.000 --> 00:24:54.000
by almost an order of magnitude
within a distance of

420
00:24:54.000 --> 00:25:00.000
about 30 meters. This
variability was seen throughout

421
00:25:00.000 --> 00:25:09.000
the Cove.

422
00:25:09.000 --> 00:25:12.000
It seems to be another visual
issue.

423
00:25:12.000 --> 00:25:17.000
>> I will repair that feel free
to carry on.

424
00:25:17.000 --> 00:25:22.000
>> Okay baby check ultimately

425
00:25:22.000 --> 00:25:26.000
-- ultimately for sediments and
surface water throughout the
Cove

426
00:25:26.000 --> 00:25:30.000
we established that there were
two processes resulting in

427
00:25:30.000 --> 00:25:33.000
elevated surface water arsenic
concentration.

428
00:25:33.000 --> 00:25:36.000
In areas of direct contaminated
discharge elevated

429
00:25:36.000 --> 00:25:40.934
arsenic concentrations were a
result of both discharge and
periods of

430
00:25:40.934 --> 00:25:43.934
sediment dissolution.

431
00:25:43.934 --> 00:25:46.934
In areas of the Cove with
limited discharge elevated
arsenic concentrations

432
00:25:46.934 --> 00:25:49.934
were observed in the water
column when iron oxide
precipitants

433
00:25:49.934 --> 00:25:57.000
and sediments dissolved in late
summer during die off and
degradation

434
00:25:57.000 --> 00:26:08.000
of aquatic plants within the
Cove.

435
00:26:08.000 --> 00:26:10.000
Our initial site
characterization efforts
confirmed a landfill drive

436
00:26:10.000 --> 00:26:12.000
contaminant plume was
discharging into the Cove. The
result during

437
00:26:12.000 --> 00:26:15.000
negative impacts to both
sediment and surface water
quality. These

438
00:26:15.000 --> 00:26:19.000
impacts were a source of
unacceptable exposures to

439
00:26:19.000 --> 00:26:24.000
both human and ecosystem
receptors for the recreational
lake. The decision

440
00:26:24.000 --> 00:26:28.000
was made to implement a non-time
critical removal action to
address

441
00:26:28.000 --> 00:26:33.000
this ongoing contaminant impact
prior to selection

442
00:26:33.000 --> 00:26:37.000
and implementation of final
remedy for the entire landfill.
Two steps

443
00:26:37.000 --> 00:26:42.934
were taken installation of a
hydraulic barrier wall to shut
off continuous

444
00:26:42.934 --> 00:26:47.934
plume discharge to the Cove
followed by removal of existing
contaminated

445
00:26:47.934 --> 00:26:55.000
sediments within the area of
observed impact. The hydraulic

446
00:26:55.000 --> 00:26:59.000
barrier wall shown as an orange
line in the left image

447
00:26:59.000 --> 00:27:04.000
was installed between the
existing edge of the landfill
cap and the

448
00:27:04.000 --> 00:27:07.000
Cove in year 2012. This was
followed by

449
00:27:07.000 --> 00:27:12.000
removal of existing contaminated
sediments in year 2013.
Following

450
00:27:12.000 --> 00:27:18.000
these steps, we recommenced our
monitoring program to address

451
00:27:18.000 --> 00:27:22.000
three questions. Does the remedy
influence groundwater

452
00:27:22.000 --> 00:27:26.000
surface hydrology? Does the
groundwater show a

453
00:27:26.000 --> 00:27:32.000
recovery trend? Does surface
water in the Cove show

454
00:27:32.000 --> 00:27:35.000
recovery trend?

455
00:27:35.000 --> 00:27:38.934
This slide attempts to summarize

456
00:27:38.934 --> 00:27:46.934
the arc of groundwater hydraulic
measurements that

457
00:27:46.934 --> 00:27:48.934
span -- one change in the
monitoring program resulted from
installation

458
00:27:48.934 --> 00:27:52.934
of the barrier wall. We were no
longer able to conduct

459
00:27:52.934 --> 00:27:58.000
a flow net analysis based on the
site wide network of wells and
piezometers

460
00:27:58.000 --> 00:28:01.000
however 3PE provided a way to
bridge the pre-and post

461
00:28:01.000 --> 00:28:06.000
remediation hydrology analysis
by allowing focus on a sub

462
00:28:06.000 --> 00:28:09.000
area immediately to the east of
the newly installed

463
00:28:09.000 --> 00:28:13.000
barrier wall. Monitoring the
upland groundwater

464
00:28:13.000 --> 00:28:17.000
system recommenced during year
2012 and monitoring within the
Cove sediment

465
00:28:17.000 --> 00:28:23.000
in 2014 following the sediment
removal action. Illustrated in
this slide

466
00:28:23.000 --> 00:28:26.000
is the three-point area of the
monitoring network that will be

467
00:28:26.000 --> 00:28:29.000
the focus of subsequent slides.

468
00:28:29.000 --> 00:28:34.000
This evaluation is centered on
the main source of landfill
derived

469
00:28:34.000 --> 00:28:37.934
arsenic discharge to the Cove.
The black outlined triangle

470
00:28:37.934 --> 00:28:43.934
you see on the graph illustrates
the three PE location

471
00:28:43.934 --> 00:28:48.934
of analysis. -- 3PE location of
analysis. This will summarize

472
00:28:48.934 --> 00:28:54.000
the hydraulic measurements that
spanned the period prior to and

473
00:28:54.000 --> 00:28:59.000
following installation of the
barrier wall. One layer of the
combined

474
00:28:59.000 --> 00:29:02.000
graph shows the locations of
three groundwater elevation
measurements

475
00:29:02.000 --> 00:29:07.000
with the triangle that
encompasses the aquifer and
Cove. These are

476
00:29:07.000 --> 00:29:12.000
labeled using white diamond
symbols connected by blue lines.

477
00:29:12.000 --> 00:29:16.000
Output from 3PE model analysis
for

478
00:29:16.000 --> 00:29:20.000
multiple observations between
years 2006

479
00:29:20.000 --> 00:29:24.000
and 2018 are shown by two
different symbols within a

480
00:29:24.000 --> 00:29:28.000
circular polar graph layered on
top of the observation triangle.

481
00:29:28.000 --> 00:29:33.000
The open squares show the
calculated magnitude and
direction

482
00:29:33.000 --> 00:29:35.000
of the gradient for groundwater
flow prior to installation of
the

483
00:29:35.000 --> 00:29:43.934
barrier wall. During this period
the gradient range between four

484
00:29:43.934 --> 00:29:46.934
and -- the blue circular symbols
document the magnitude

485
00:29:46.934 --> 00:29:50.934
and direction of the groundwater
flow gradient after barrier

486
00:29:50.934 --> 00:29:56.000
wall installation. The wall has
led to a significant reduction
in

487
00:29:56.000 --> 00:30:02.000
flow gradient to the Cove.

488
00:30:02.000 --> 00:30:06.000
Concurrent with the hydraulic
measurements we've

489
00:30:06.000 --> 00:30:11.000
measured chemistry in
groundwater samples from the
nested piezometers

490
00:30:11.000 --> 00:30:12.734
on the left is a graph of

491
00:30:12.734 --> 00:30:16.000
groundwater arsenic
concentration as a function

492
00:30:16.000 --> 00:30:19.000
of time for the piezometer
cluster positioned within them

493
00:30:19.000 --> 00:30:24.000
main area of contaminant
discharge to the Cove. The
downward

494
00:30:24.000 --> 00:30:33.000
grain triangle -- green triangle
shows when the wall

495
00:30:33.000 --> 00:30:35.000
was installed. There has been a
decline in arsenic
concentrations

496
00:30:35.000 --> 00:30:37.000
and aquifer which is most
pronounced for the top half of
the aquifer.

497
00:30:37.000 --> 00:30:41.934
Arsenic concentrations have not
shown a similar decline at the

498
00:30:41.934 --> 00:30:44.934
piezometer cluster Southwest of
the Cove as shown in the graph
on

499
00:30:44.934 --> 00:30:54.000
the right. Concentrations have
been relatively stable with

500
00:30:54.000 --> 00:30:57.000
some variations.

501
00:30:57.000 --> 00:31:02.000
To better comprehend what this
means we combine these sources

502
00:31:02.000 --> 00:31:07.000
of data to estimate reductions
in arsenic

503
00:31:07.000 --> 00:31:09.000
contaminant flux achieved
through a combination of
groundwater flux

504
00:31:09.000 --> 00:31:10.400
calculated using the 3PE

505
00:31:10.400 --> 00:31:13.000
workbook and median
concentrations of arsenic

506
00:31:13.000 --> 00:31:18.000
is observed in all piezometer
screens founding the
cross-sections of

507
00:31:18.000 --> 00:31:20.000
the 3PE.

508
00:31:20.000 --> 00:31:25.000
The graph shown in this slide
indicates the calculated
contaminant flux

509
00:31:25.000 --> 00:31:30.000
on September 14. 2011 was 108
milligrams per day per square

510
00:31:30.000 --> 00:31:36.000
meter across this portion of the
aquifer adjacent to

511
00:31:36.000 --> 00:31:41.934
the Cove.

512
00:31:41.934 --> 00:31:45.934
We extend this comparison on
this slide

513
00:31:45.934 --> 00:31:48.934
for the entire monitoring
period. The top graph

514
00:31:48.934 --> 00:31:55.000
on this slide shows results of
flux measurements in

515
00:31:55.000 --> 00:31:58.000
the Cove.

516
00:31:58.000 --> 00:32:01.000
Pardon me.

517
00:32:01.000 --> 00:32:03.000
The prior slide demonstrated our
accumulated

518
00:32:03.000 --> 00:32:07.000
knowledge of what was occurring
and aquifer adjacent to the Cove

519
00:32:07.000 --> 00:32:16.000
for the most significant plume
discharge was occurring.

520
00:32:16.000 --> 00:32:28.000
The top graph on this slide

521
00:32:28.000 --> 00:32:35.000
-- shows results

522
00:32:35.000 --> 00:32:39.934
of flux measurements in the cold
based on log sediment
temperature

523
00:32:39.934 --> 00:32:41.934
measurements. For a period of
three months prior to and
following

524
00:32:41.934 --> 00:32:44.934
installation of the barrier
wall.

525
00:32:44.934 --> 00:32:51.934
The orange symbols ranging in
magnitude from 10

526
00:32:51.934 --> 00:32:55.000
to 20 centimeters per day per
square meter offer calculated
seepage flux

527
00:32:55.000 --> 00:32:59.000
during the period of June to
August 2008. The green symbols
ranging

528
00:32:59.000 --> 00:33:06.000
in magnitude from zero to five
centimeters per day per

529
00:33:06.000 --> 00:33:09.000
square meter offer calculated
seepage flux during the period
of June to

530
00:33:09.000 --> 00:33:13.000
August 2014. Also shown in this
graph and open diamond symbols
are

531
00:33:13.000 --> 00:33:16.000
the corresponding groundwater
flux calculated using

532
00:33:16.000 --> 00:33:21.000
the 3PE workbook. The bottom
graph on this slide summarizes
the results

533
00:33:21.000 --> 00:33:27.000
from all dates in which
independent measurements for
groundwater and

534
00:33:27.000 --> 00:33:29.000
seepage flux were conducted. The
solid lines represent

535
00:33:29.000 --> 00:33:33.000
the average of all measurements
prior to and following barrier

536
00:33:33.000 --> 00:33:37.934
wall installation. These results
clearly show the hydraulic
connection

537
00:33:37.934 --> 00:33:43.934
between the aquifer and Cove,
along with the benefit realized
from installation

538
00:33:43.934 --> 00:33:54.000
of the barrier wall.

539
00:33:54.000 --> 00:33:58.000
Monitoring results shown on the
previous slide addressed two of

540
00:33:58.000 --> 00:34:04.000
the three questions we were
trying to answer for the remedy
performance

541
00:34:04.000 --> 00:34:07.000
monitoring period. The barrier
wall resulted in reduced
groundwater

542
00:34:07.000 --> 00:34:12.000
flux to the Cove and it has also
resulted in declines

543
00:34:12.000 --> 00:34:17.000
in groundwater arsenic
concentrations east of the
barrier wall.

544
00:34:17.000 --> 00:34:19.000
The data presented on this slide
confirms through independent
measurements

545
00:34:19.000 --> 00:34:24.000
within the Cove that there has
been a reduction in arsenic flux
to

546
00:34:24.000 --> 00:34:29.000
the Cove. The graph on this
slide shows comparison of the
interpolated

547
00:34:29.000 --> 00:34:33.000
arsenic flux from observations
within the adjacent aquifer

548
00:34:33.000 --> 00:34:38.000
to direct observations based on
measurements of seepage flux and

549
00:34:38.000 --> 00:34:40.000
sediment pore water chemistry.
The latter measurements

550
00:34:40.000 --> 00:34:41.400
have been conducted less

551
00:34:41.400 --> 00:34:44.000
frequently but these
observations support the

552
00:34:44.000 --> 00:34:53.000
direct connection in contaminant
flux between the aquifer

553
00:34:53.000 --> 00:34:56.000
and Cove.

554
00:34:56.000 --> 00:35:00.000
Lastly, we get to the question
of arsenic concentrations

555
00:35:00.000 --> 00:35:02.000
and surface water. This graph
shows concentrations of arsenic

556
00:35:02.000 --> 00:35:10.000
and surface water over the
entire monitoring period where
the

557
00:35:10.000 --> 00:35:11.000
green triangle again and
vertical Graybar represent the
timing of

558
00:35:11.000 --> 00:35:15.000
barrier wall installation
followed by sediment removal.
The open triangle

559
00:35:15.000 --> 00:35:20.000
symbols are for shallow surface
water at depths within a foot
below

560
00:35:20.000 --> 00:35:23.000
the water surface. Arsenic
concentrations

561
00:35:23.000 --> 00:35:28.000
have never been elevated at this
depth. The filled red triangles

562
00:35:28.000 --> 00:35:32.000
are for deep surface water at
depths within a foot above the
sediment

563
00:35:32.000 --> 00:35:35.000
surface. Prior to installation
of the

564
00:35:35.000 --> 00:35:38.934
barrier wall deep surface water
concentrations commonly exceeded

565
00:35:38.934 --> 00:35:42.934
either the acute or chronic
ambient water quality criteria
within the

566
00:35:42.934 --> 00:35:46.934
middle of the Cove reject
following barrier wall
installation, it seems

567
00:35:46.934 --> 00:35:50.934
the ambient water quality
criteria has been less

568
00:35:50.934 --> 00:35:56.000
frequent in most cases a
deep-sea first water
concentrations have

569
00:35:56.000 --> 00:36:00.000
been low compared to

570
00:36:00.000 --> 00:36:02.000
to those higher up in the water
column. Observation of seepage
flux

571
00:36:02.000 --> 00:36:07.000
and other chemistry data
indicate the current infrequent
exceedances

572
00:36:07.000 --> 00:36:10.000
are a result of periods of
sediment dissolution

573
00:36:10.000 --> 00:36:22.000
however these periods appear to
be short-lived.

574
00:36:22.000 --> 00:36:24.000
Ultimately the reduction in
arsenic contaminant flux has

575
00:36:24.000 --> 00:36:27.000
benefited the Cove. It's
important to note the steps
taken during than

576
00:36:27.000 --> 00:36:32.000
on time critical removal action
were not designed a

577
00:36:32.000 --> 00:36:37.000
final remedy but the steps taken
have achieved the

578
00:36:37.000 --> 00:36:40.934
desired outcome, continuous
contaminant flux has been
stopped. As shown

579
00:36:40.934 --> 00:36:45.934
in these before-and-after
pictures this is resulted in

580
00:36:45.934 --> 00:36:51.934
a significant and beneficial
change for

581
00:36:51.934 --> 00:36:55.000
the Cove.

582
00:36:55.000 --> 00:37:01.000
In summary for this case study,
evaluation of the water

583
00:37:01.000 --> 00:37:04.000
flux from the aquifer to the
Cove was helpful

584
00:37:04.000 --> 00:37:06.000
to clearly understand the causes
for elevated arsenic
concentrations

585
00:37:06.000 --> 00:37:10.000
in the water column. This
information also benefited the
selection

586
00:37:10.000 --> 00:37:16.000
and implementation of the
interim remedial design. This
illustrates

587
00:37:16.000 --> 00:37:19.000
the importance of linking water
flux measurements with chemistry

588
00:37:19.000 --> 00:37:25.000
measurements to interpret the
severity and dynamics of
contaminant impacts

589
00:37:25.000 --> 00:37:30.000
to the surface water body.
Ultimately, interpreted stations

590
00:37:30.000 --> 00:37:33.000
will benefit from matching up
the timing of

591
00:37:33.000 --> 00:37:38.934
both types of measurements
within the

592
00:37:38.934 --> 00:37:40.934
monitoring program.

593
00:37:40.934 --> 00:37:44.934
It is our hope that the results
from this case study demonstrate

594
00:37:44.934 --> 00:37:47.934
the utility of explicitly
monitoring water flux as part of

595
00:37:47.934 --> 00:37:52.934
any site assessment. The message
to

596
00:37:52.934 --> 00:37:57.000
us that's -- methods should be
relatively easy to implement.

597
00:37:57.000 --> 00:38:01.000
This is facilitated by the range
of equipment choices and data
analysis

598
00:38:01.000 --> 00:38:04.000
tools available.

599
00:38:04.000 --> 00:38:07.000
Linking these measurements to
chemistry data provides an added
dimension

600
00:38:07.000 --> 00:38:12.000
of understanding for the
monitoring effort and should
facilitate making

601
00:38:12.000 --> 00:38:18.000
site cleanup decisions that are
sustainable in

602
00:38:18.000 --> 00:38:21.000
the future.

603
00:38:21.000 --> 00:38:29.000
This concludes our presentation.

604
00:38:29.000 --> 00:38:31.000
We would like to acknowledge the
many individuals who have
contributed

605
00:38:31.000 --> 00:38:34.000
to the various stages of
fieldwork conducted at Fort
Devens as well

606
00:38:34.000 --> 00:38:38.934
as those who have helped with
testing the seepage flux work
tools to ensure

607
00:38:38.934 --> 00:38:44.934
usability. Our research and
development program

608
00:38:44.934 --> 00:38:46.934
as well as our interactions with
the

609
00:38:46.934 --> 00:38:48.934
regional offices have been
facilitated by the engineering
and groundwater

610
00:38:48.934 --> 00:38:52.934
technical support centers. We
encourage all

611
00:38:52.934 --> 00:38:56.000
to contact those centers for
assistance at sites where the
tools described

612
00:38:56.000 --> 00:38:58.000
in this presentation may be of
use.

613
00:38:58.000 --> 00:39:00.000
I've provided contacts at the
top of the slide for those who
wish

614
00:39:00.000 --> 00:39:07.000
to follow up on that. Finally, I
would like to

615
00:39:07.000 --> 00:39:09.000
express my appreciation to both
Jean and Austin the arrangements

616
00:39:09.000 --> 00:39:13.000
for facilitation of this webinar
have been top-notch. That
concludes

617
00:39:13.000 --> 00:39:17.000
my presentation and we are all
hopefully able to address

618
00:39:17.000 --> 00:39:19.000
your questions.

619
00:39:19.000 --> 00:39:22.000
>> Thank you, so very much
Robert.

620
00:39:22.000 --> 00:39:26.000
We have a number of questions
that have already been submitted

621
00:39:26.000 --> 00:39:31.000
into the question Q

622
00:39:31.000 --> 00:39:33.000
in the lower right corner. I
will remind you that you can
type those

623
00:39:33.000 --> 00:39:37.000
questions and comments in and we
will go through as many as we
can

624
00:39:37.000 --> 00:39:40.934
in the time we have. Our very
first question can you use

625
00:39:40.934 --> 00:39:43.934
more than three points or wells
to find flow direction?

626
00:39:43.934 --> 00:39:50.934
>> That's a question I will
direct to Steve.

627
00:39:50.934 --> 00:39:57.000
>> This is Steve. Yes, you can.
You don't actually have

628
00:39:57.000 --> 00:40:01.000
to use 3PE to define flow
direction you

629
00:40:01.000 --> 00:40:06.000
can extend surface at which
point you would have multiple
points or

630
00:40:06.000 --> 00:40:12.000
if you want to use the 3PE work
book it is based on the

631
00:40:12.000 --> 00:40:18.000
3 point of gradient estimator,
which in

632
00:40:18.000 --> 00:40:21.000
the past has been done
graphically.

633
00:40:21.000 --> 00:40:24.000
It's basically a hydro-10120 but
this is a

634
00:40:24.000 --> 00:40:30.000
mathematical implementation.
This particular workbook

635
00:40:30.000 --> 00:40:36.000
3PE does use only three points
there are others on

636
00:40:36.000 --> 00:40:39.934
the net that use Excel-based
workbooks that allow

637
00:40:39.934 --> 00:40:43.934
more than one -- multiple points
but this

638
00:40:43.934 --> 00:40:46.934
is only three.

639
00:40:46.934 --> 00:40:49.934
>> Excellent. We have a few
questions about

640
00:40:49.934 --> 00:40:55.000
title environments, the first
wanted to know if you could
discuss if

641
00:40:55.000 --> 00:41:00.000
and how these tools would be
applicable in tidal areas --

642
00:41:00.000 --> 00:41:03.000
title areas.

643
00:41:03.000 --> 00:41:07.000
>> I will field this question.
Certainly, both tools

644
00:41:07.000 --> 00:41:12.000
could potentially still be used
of the two approaches the one
that

645
00:41:12.000 --> 00:41:17.000
is more fraught with potential
problems will be the seepage

646
00:41:17.000 --> 00:41:21.000
flux measurements. The title
cycle represents a very

647
00:41:21.000 --> 00:41:26.000
dynamic setting and this is
where we've spent a lot of time

648
00:41:26.000 --> 00:41:30.000
working through what is a
reliable way to both collect
temperature

649
00:41:30.000 --> 00:41:34.000
data within sediments and
subsequently to

650
00:41:34.000 --> 00:41:37.934
analyze those data to calculate
a seepage flux. What we have
seen,

651
00:41:37.934 --> 00:41:42.934
at least with our personal
experience is

652
00:41:42.934 --> 00:41:46.934
that typically when you deploy
the sediment temperature sensors
deeper

653
00:41:46.934 --> 00:41:48.934
within the sediment column the
steady-state

654
00:41:48.934 --> 00:41:54.000
mathematical solutions appear to
provide fairly reliable outcomes

655
00:41:54.000 --> 00:41:59.000
where you can run into trouble
as if you rely on the shallow
sediment

656
00:41:59.000 --> 00:42:05.000
sensor depths and try to use
transient analytical solutions.

657
00:42:05.000 --> 00:42:09.000
Those solutions -- both
solutions are

658
00:42:09.000 --> 00:42:13.000
built on the assumption that you
only have vertical water flow,
that's

659
00:42:13.000 --> 00:42:19.000
the underpinning for the
boundary conditions of

660
00:42:19.000 --> 00:42:23.000
these models. Any non-vertical
flows that occur through that
sediment

661
00:42:23.000 --> 00:42:27.000
package will those cause
violation of those assumptions
and

662
00:42:27.000 --> 00:42:30.000
therefore potentially prevent
you from using

663
00:42:30.000 --> 00:42:35.000
the transient models to estimate
seepage

664
00:42:35.000 --> 00:42:37.000
flux.

665
00:42:37.000 --> 00:42:40.934
>> Okay. Talking about sediment,
does the type

666
00:42:40.934 --> 00:42:44.934
of sediment impact your ability
to measure your temperature flux

667
00:42:44.934 --> 00:42:49.934
they are considering layered or
lower permeability soils.

668
00:42:49.934 --> 00:42:56.000
>> I will field this one as
well. The answer

669
00:42:56.000 --> 00:43:01.000
is yes. The first issue you
might have to deal with

670
00:43:01.000 --> 00:43:05.000
is difficulty in deploying
sensors to any depth within

671
00:43:05.000 --> 00:43:10.000
the sediment. You certainly can
encounter types of materials
that

672
00:43:10.000 --> 00:43:16.000
prevent reliable installation
that doesn't end up damaging

673
00:43:16.000 --> 00:43:20.000
your sensors. With regard to
layering, that can be an issue.

674
00:43:20.000 --> 00:43:25.000
I did mention a procedure that
we used to measure thermal

675
00:43:25.000 --> 00:43:31.000
conductivity of sediments. That
parameter is dependent not

676
00:43:31.000 --> 00:43:35.000
only on the drain size of the
sediments but the constituents
whether it's

677
00:43:35.000 --> 00:43:38.934
primarily minimal grains or if
you are in a productive surface
water

678
00:43:38.934 --> 00:43:44.934
system where there might be a
lot of organic matter mixed in.
That

679
00:43:44.934 --> 00:43:49.934
will affect the distribution of
that thermal conductivity and
that

680
00:43:49.934 --> 00:43:54.000
will enhanced -- be enhanced if
you've

681
00:43:54.000 --> 00:43:56.000
got a layer type system.

682
00:43:56.000 --> 00:44:01.000
One of the available free
versions that I made

683
00:44:01.000 --> 00:44:06.000
reference to, we can send out
information following this call,
actually considered

684
00:44:06.000 --> 00:44:10.000
layered systems where you
assigned different
parameterization

685
00:44:10.000 --> 00:44:13.000
to the different sediment
layers.

686
00:44:13.000 --> 00:44:17.000
That can be considered when you
solve the overall sheet

687
00:44:17.000 --> 00:44:22.000
transport equation. There are
models and ways to account

688
00:44:22.000 --> 00:44:28.000
for this ultimately if that
layering system results in

689
00:44:28.000 --> 00:44:32.000
impermeable layers you may get
temperature data that really
seems

690
00:44:32.000 --> 00:44:35.000
out of whack and that's because
you don't actually have water
flow

691
00:44:35.000 --> 00:44:40.000
being conveyed through the
entire sediment package that you
are trying

692
00:44:40.000 --> 00:44:42.000
to monitor.

693
00:44:42.000 --> 00:44:48.000
>> Can you talk about this depth
of the

694
00:44:48.000 --> 00:44:53.000
nested piezometer sensors?
Pardon me, they want to know
what depth

695
00:44:53.000 --> 00:44:57.000
did you nest those piezometers
and

696
00:44:57.000 --> 00:45:00.000
temperatures?

697
00:45:00.000 --> 00:45:04.000
>> The piezometers that we have
been using are hand driven

698
00:45:04.000 --> 00:45:09.000
and typically we reliably get to
a depth of 5 mina

699
00:45:09.000 --> 00:45:15.000
6 feet, one or two meters at
most if you have other
mechanical equipment,

700
00:45:15.000 --> 00:45:19.000
powered mechanical equipment you
can get deeper into the sediment

701
00:45:19.000 --> 00:45:24.000
package. With regard to the
sediment temperature sensors, we

702
00:45:24.000 --> 00:45:29.000
typically have -- we routinely
deploy to a total depth

703
00:45:29.000 --> 00:45:35.000
of three feet because it's a
depth we can routinely achieve
for

704
00:45:35.000 --> 00:45:36.000
most types of sediment
materials.

705
00:45:36.000 --> 00:45:40.934
There are instances where we put
a lot of effort in and we've

706
00:45:40.934 --> 00:45:43.934
gone down to a depth of six
feet.

707
00:45:43.934 --> 00:45:46.934
The issue becomes if you leave

708
00:45:46.934 --> 00:45:52.934
these deployed, sensors deployed
for an extended period of time
while

709
00:45:52.934 --> 00:45:56.000
you may have gotten it down to
six feet can you actually
retrieve

710
00:45:56.000 --> 00:45:59.000
that sensor from the sediment
package?

711
00:45:59.000 --> 00:46:04.000
In many case we rely on rhe
collapse of the sediment
materials

712
00:46:04.000 --> 00:46:09.000
to encapsulate that sensor and
isolate it from other parts

713
00:46:09.000 --> 00:46:12.000
of the sediment.

714
00:46:12.000 --> 00:46:15.000
Which is good in collecting
temperature data but

715
00:46:15.000 --> 00:46:20.000
it's bad over the long run in
terms of having deep sensors
that may

716
00:46:20.000 --> 00:46:23.000
be difficult to retrieve.

717
00:46:23.000 --> 00:46:27.000
>> Excellent, thank you. Are
there geologic

718
00:46:27.000 --> 00:46:32.000
or hydrologic environments where
this model does not apply for
example

719
00:46:32.000 --> 00:46:37.000
layered red rock scenarios?

720
00:46:37.000 --> 00:46:40.934
>> That sounds like more of an
issue that's relevant to 3PE.

721
00:46:40.934 --> 00:46:48.934
I'm going to hand it to Randall
or Steve. What I will say for
the

722
00:46:48.934 --> 00:46:52.934
seepage flux measurements, we
are assuming we are working with

723
00:46:52.934 --> 00:46:55.000
unconsolidated material we are
not deploying temperature
sensors

724
00:46:55.000 --> 00:46:59.000
into fractures within the
surface water body. Steve or
Randall have

725
00:46:59.000 --> 00:47:02.000
at it.

726
00:47:02.000 --> 00:47:05.000
>> We will echo what you said,
the temperature sensors are

727
00:47:05.000 --> 00:47:10.000
in unconsolidated sediments and
once you get into fresh

728
00:47:10.000 --> 00:47:16.000
bed rock all bets are off and it
gets more complicated then

729
00:47:16.000 --> 00:47:19.000
I'm going to deal with.

730
00:47:19.000 --> 00:47:25.000
>> I was going to say it will be
a heterogeneous issue

731
00:47:25.000 --> 00:47:31.000
versus largest -- common adjust
-- they are

732
00:47:31.000 --> 00:47:35.000
not decide for heterogeneous
systems it's like

733
00:47:35.000 --> 00:47:42.934
most tools it's the ability to
monitor and get

734
00:47:42.934 --> 00:47:44.934
representative data.

735
00:47:44.934 --> 00:47:48.934
>> Again, extrapolating further
can these models be used

736
00:47:48.934 --> 00:47:52.934
for reservoir settings where the
water level and the surface
water

737
00:47:52.934 --> 00:47:58.000
body is managed at multiple
levels over the course of

738
00:47:58.000 --> 00:48:01.000
the year?

739
00:48:01.000 --> 00:48:07.000
>> They certainly could be. And
that's one thing that

740
00:48:07.000 --> 00:48:12.000
we have not dealt with reservoir
situation specifically. We have

741
00:48:12.000 --> 00:48:19.000
dealt with systems where the
river water level might change
due to

742
00:48:19.000 --> 00:48:23.000
title -- tidal cycles or changes
dramatically over seasonal
cycles.

743
00:48:23.000 --> 00:48:28.000
Typically, the issues are

744
00:48:28.000 --> 00:48:32.000
if there are sharp transition
periods where the water levels
are changing

745
00:48:32.000 --> 00:48:37.000
and for the temperature-based
measurements for heat flux it's
the transitional

746
00:48:37.000 --> 00:48:38.934
periods that can be problematic.
From a site monitoring

747
00:48:38.934 --> 00:48:44.934
perspective what you would want
to look at is look at these
variations

748
00:48:44.934 --> 00:48:49.934
in time and see what the timing
is and focus your monitoring

749
00:48:49.934 --> 00:48:55.000
effort during those periods that
are

750
00:48:55.000 --> 00:48:57.000
not transitional. There may be a
period where your reservoir
level

751
00:48:57.000 --> 00:49:03.000
is maintained high versus
periods where it's maintained
over extended

752
00:49:03.000 --> 00:49:07.000
period of time at lower levels.

753
00:49:07.000 --> 00:49:10.000
You can target those periods in
terms of data collection are
certainly

754
00:49:10.000 --> 00:49:14.000
the data analysis and you will
probably end up filling out

755
00:49:14.000 --> 00:49:18.000
those transitional periods where
the water levels may change
dramatically

756
00:49:18.000 --> 00:49:22.000
and dramatically as hard to say
depending on what the period of

757
00:49:22.000 --> 00:49:26.000
time is but typically you will

758
00:49:26.000 --> 00:49:30.000
see during those transitional
periods for temperature some
weird things

759
00:49:30.000 --> 00:49:35.000
happening in terms of the
temperature profile it won't be
grading in a

760
00:49:35.000 --> 00:49:38.934
certain direction and you will
have intermediate temperatures
that don't

761
00:49:38.934 --> 00:49:44.934
follow a typical trend either
decreasing or increasing.

762
00:49:44.934 --> 00:49:49.934
>> One person just chimed in,
temperature profiles

763
00:49:49.934 --> 00:49:54.000
all by themselves don't indicate
losing or gaining streams do

764
00:49:54.000 --> 00:49:58.000
they? These temperature profiles
just relative measurements that

765
00:49:58.000 --> 00:50:03.000
you have to put in context to
other sets of information?

766
00:50:03.000 --> 00:50:07.000
>> The temperature data itself
gives you a relative indication.

767
00:50:07.000 --> 00:50:12.000
That's true. As I mentioned, a
typical screening

768
00:50:12.000 --> 00:50:16.000
approach is to go out and do a

769
00:50:16.000 --> 00:50:22.000
synaptic grounder areawide
survey on the shoreline and look

770
00:50:22.000 --> 00:50:27.000
at differences between the
sediment temperature and the
surface

771
00:50:27.000 --> 00:50:31.000
water temperature and look for
anomalous situations. That's a
qualitative

772
00:50:31.000 --> 00:50:37.000
indicator and if we stop with
the relative profile we would
still

773
00:50:37.000 --> 00:50:39.934
have the same indication.
However, the models

774
00:50:39.934 --> 00:50:44.934
are taking the temperature data
and inputting it into a

775
00:50:44.934 --> 00:50:50.934
heat flux equation calculating
what combination of water

776
00:50:50.934 --> 00:50:54.000
movement and heat conduction
would give you

777
00:50:54.000 --> 00:50:59.000
that temperature profile so when
you actually take

778
00:50:59.000 --> 00:51:01.000
the raw temperature data and
input them into the heat flux
modeling

779
00:51:01.000 --> 00:51:06.000
you are taking a step further
and getting a quantitative
information

780
00:51:06.000 --> 00:51:11.000
of direction and magnitude of
the actual flux at that
monitored location.

781
00:51:11.000 --> 00:51:19.000
>> Thank you. Would you say in
your experience do

782
00:51:19.000 --> 00:51:21.000
seepage bags, hydraulic gradient
estimates and temperature flux
give

783
00:51:21.000 --> 00:51:26.000
similar results when you applied
them at the same site?

784
00:51:26.000 --> 00:51:32.000
>> I will answer that and say
they can and we've

785
00:51:32.000 --> 00:51:35.000
seen that. We have also seen
situations where they

786
00:51:35.000 --> 00:51:38.934
haven't. In one example I would
give

787
00:51:38.934 --> 00:51:42.934
you, where the seepage flux
calculation based on temperature
measurements

788
00:51:42.934 --> 00:51:47.934
don't match up with those
measurements of vertical
hydraulic gradient

789
00:51:47.934 --> 00:51:51.934
and/or separate direct seepage
flux measurements using

790
00:51:51.934 --> 00:51:56.000
a meter. Typically, that occurs
because those temperature data
are

791
00:51:56.000 --> 00:52:00.000
not reflecting a condition that
adheres to the assumptions

792
00:52:00.000 --> 00:52:05.000
of the different models that I'm
trying to make use of. That's
why

793
00:52:05.000 --> 00:52:11.000
typically at least routinely, we
don't go and just measure

794
00:52:11.000 --> 00:52:15.000
temperature profiles. We will
collect other sources of
information as

795
00:52:15.000 --> 00:52:21.000
a quality insurance quality
control hip-check. --

796
00:52:21.000 --> 00:52:26.000
Type check. Is weaved approach
this following at a wider

797
00:52:26.000 --> 00:52:31.000
variety of sites we've developed
a higher comfort level

798
00:52:31.000 --> 00:52:36.000
of when we are collecting data
that really does adhere to the
temperature

799
00:52:36.000 --> 00:52:40.934
flux models. We still do collect
other lines of evidence

800
00:52:40.934 --> 00:52:45.934
to confirm that yes indeed this
-- these temperature flux data
are

801
00:52:45.934 --> 00:52:50.934
actually giving us reality.

802
00:52:50.934 --> 00:52:55.000
>> All right, thank you. Once
you've been able

803
00:52:55.000 --> 00:52:59.000
to calculate contaminant flux do
you have any

804
00:52:59.000 --> 00:53:04.000
suggestions on models to
evaluate dilution or dispersion

805
00:53:04.000 --> 00:53:09.000
within the surface water body?

806
00:53:09.000 --> 00:53:13.000
>> For me,

807
00:53:13.000 --> 00:53:18.000
I'm not an expert in surface
water hydrology, I would

808
00:53:18.000 --> 00:53:24.000
typically just mixing type
calculations where I might have

809
00:53:24.000 --> 00:53:28.000
some assessment of what the
volumetric water flow is in

810
00:53:28.000 --> 00:53:33.000
that surface water body and I've
come up with an assessment of
what

811
00:53:33.000 --> 00:53:37.000
I think is a reasonable
groundwater flow entering into
some

812
00:53:37.000 --> 00:53:42.934
part of a river reach or
whatever surface water bodies. I
would look

813
00:53:42.934 --> 00:53:45.934
at that and it's giving me an
indication of what

814
00:53:45.934 --> 00:53:51.934
that water volume deletion
factor would

815
00:53:51.934 --> 00:53:55.000
be -- dilution factor would be
and I could apply that

816
00:53:55.000 --> 00:53:57.000
to what I might expect to see
for chemistry measurements but
that

817
00:53:57.000 --> 00:54:01.000
would be accrued assessment and
beyond that I could not point to

818
00:54:01.000 --> 00:54:05.000
any specific models. I do know
they exist. I don't know if
anyone

819
00:54:05.000 --> 00:54:11.000
else here would want to point
you to any available models. I

820
00:54:11.000 --> 00:54:13.000
know they do exist.

821
00:54:13.000 --> 00:54:18.000
In fact come up there are models
that are out there where input
might

822
00:54:18.000 --> 00:54:25.000
be your estimate of base flow
and or groundwater

823
00:54:25.000 --> 00:54:29.000
discharge contribution to base
flow or throughout the period of
time

824
00:54:29.000 --> 00:54:32.000
for a given water body.

825
00:54:32.000 --> 00:54:38.000
>> Okay. How about this one.
When temperature and gradient
data

826
00:54:38.000 --> 00:54:44.000
are discordant which would you
trust more?

827
00:54:44.000 --> 00:54:50.000
>> I'm from Missouri, the
show-me-state. In terms of

828
00:54:50.000 --> 00:54:54.000
the complexity of the
measurement and things that

829
00:54:54.000 --> 00:54:59.000
can go wrong or violations of
what I know should be reality, I
favor

830
00:54:59.000 --> 00:55:04.000
those gradient data. As I
mentioned, this is dependent on

831
00:55:04.000 --> 00:55:08.000
whether that piezometer has been
constructed and developed in a

832
00:55:08.000 --> 00:55:14.000
way to show good hydraulic
connection to the

833
00:55:14.000 --> 00:55:18.000
underlying aquifer. I've seen
situations where a piezometer

834
00:55:18.000 --> 00:55:23.000
gets installed in sediments are

835
00:55:23.000 --> 00:55:26.000
very clay almost moldable clay.

836
00:55:26.000 --> 00:55:29.000
When you measure the head
difference

837
00:55:29.000 --> 00:55:33.000
in the surface water body in the
piezometer depending what time

838
00:55:33.000 --> 00:55:37.000
you take the measurement, you
may not be measuring

839
00:55:37.000 --> 00:55:40.934
is steady-state in terms of the
hydraulic gradient. You can get

840
00:55:40.934 --> 00:55:45.934
a false sense that there is a
really strong gradient because
the

841
00:55:45.934 --> 00:55:51.934
water level has not recovered
within that piezometer screen.
Concordant

842
00:55:51.934 --> 00:55:56.000
with that type of measurement
I've seen sediment temperature
profiles

843
00:55:56.000 --> 00:55:59.000
that basically tell you the only
thing

844
00:55:59.000 --> 00:56:03.000
that's occurring that's causing
that temperature profile is heat

845
00:56:03.000 --> 00:56:07.000
conduction. There's little to no
actual

846
00:56:07.000 --> 00:56:13.000
calculated flow. Given my
knowledge of what I've seen from

847
00:56:13.000 --> 00:56:15.000
sediment cores and basically
stomping around in

848
00:56:15.000 --> 00:56:18.000
those sediments, I would never
expect there to be any
significant water

849
00:56:18.000 --> 00:56:21.000
flow across a multiple place
sediment.

850
00:56:21.000 --> 00:56:26.000
Just pointing out, you have to
pay attention to

851
00:56:26.000 --> 00:56:32.000
all type lines of evidence and
information you collect relative
to the context

852
00:56:32.000 --> 00:56:37.000
or physical conditions of the
sediment or situation you

853
00:56:37.000 --> 00:56:37.934
are monitoring.

854
00:56:37.934 --> 00:56:42.934
>> Okay. I think you highlighted
this very concept, someone
wanted

855
00:56:42.934 --> 00:56:47.934
to know if the clay bed stream
pardon me at Clay streambed
would throw

856
00:56:47.934 --> 00:56:50.934
the results off if you are in
that environment.

857
00:56:50.934 --> 00:56:57.000
>> I guess just a follow-up, it
may be that it could

858
00:56:57.000 --> 00:57:06.000
in that you are applying a heat
flux model to

859
00:57:06.000 --> 00:57:11.000
really low situations of water
advection and it's

860
00:57:11.000 --> 00:57:16.000
a situation where you're working
at the limits of the accuracy
and

861
00:57:16.000 --> 00:57:18.000
sensitivity of your temperature
sensors. You are at

862
00:57:18.000 --> 00:57:23.000
a point where your close to the
limits of technology but in
essence

863
00:57:23.000 --> 00:57:28.000
what you might see is values and
I've seen they

864
00:57:28.000 --> 00:57:31.000
bounce around zero seepage flux
that you've calculated from
those

865
00:57:31.000 --> 00:57:36.000
temperature profiles. Basically
they're telling you that

866
00:57:36.000 --> 00:57:39.934
yes indeed there really isn't
much invective flux across the
sediment

867
00:57:39.934 --> 00:57:44.934
layer because it's essentially
impermeable to vertical

868
00:57:44.934 --> 00:57:47.934
water flow.

869
00:57:47.934 --> 00:57:52.934
>> Excellent. How deep is
conduction? Is it inches or

870
00:57:52.934 --> 00:57:56.000
several feet?

871
00:57:56.000 --> 00:58:01.000
>> It can be -- it's relative

872
00:58:01.000 --> 00:58:04.000
and it depends on the sediment
material.

873
00:58:04.000 --> 00:58:08.000
Some materials and as an
example, if you are dealing

874
00:58:08.000 --> 00:58:14.000
in a system that is primarily
like a coarse grain sand, well

875
00:58:14.000 --> 00:58:19.000
sorted sand, you will get
thermal conductivity measurement

876
00:58:19.000 --> 00:58:25.000
that's a factor of three higher
than you would get for a

877
00:58:25.000 --> 00:58:27.000
sediment, a shallow sediment in
a highly productive

878
00:58:27.000 --> 00:58:31.000
surface water system where you
see a lot of product plant

879
00:58:31.000 --> 00:58:37.000
growth and die off and you were
to measure high levels

880
00:58:37.000 --> 00:58:41.934
of organic carbon. When you mix
that

881
00:58:41.934 --> 00:58:45.934
organic carbon it's insulation
so your heat production will
propagate

882
00:58:45.934 --> 00:58:51.934
to shorter distances and in
equivalent sediment that's
dominated by a minimal,

883
00:58:51.934 --> 00:58:58.000
well sorted sandy sized sediment
material. In terms of the

884
00:58:58.000 --> 00:59:02.000
absolute depth, from a gut
perspective

885
00:59:02.000 --> 00:59:08.000
of indicate, suggest it might be
several feet. It depends

886
00:59:08.000 --> 00:59:12.000
on the absolute difference in
temperature between that surface
water body

887
00:59:12.000 --> 00:59:15.000
in the groundwater where you are
monitoring, or the higher

888
00:59:15.000 --> 00:59:19.000
the temperature differences you
will have more forcing of the
heat

889
00:59:19.000 --> 00:59:24.000
conduction downward but it will
be modified by the thermal
conductivity

890
00:59:24.000 --> 00:59:29.000
of the sediment material.

891
00:59:29.000 --> 00:59:34.000
>> Okay Pete --. I moving onto a
different

892
00:59:34.000 --> 00:59:38.934
group of questions and these are
more comparisons to other
approaches

893
00:59:38.934 --> 00:59:44.934
or technologies. One is familiar
they

894
00:59:44.934 --> 00:59:49.934
are -- it's analogous to using
heat

895
00:59:49.934 --> 00:59:54.000
flux based models that are
described in this presentation.
They want

896
00:59:54.000 --> 01:00:00.000
to know if the heat model needs

897
01:00:00.000 --> 01:00:04.000
insulation properties.

898
01:00:04.000 --> 01:00:09.000
>> Yes, that's an input
parameter for the models. That's
why

899
01:00:09.000 --> 01:00:14.000
we actually when we go to a site
we will routinely

900
01:00:14.000 --> 01:00:17.000
collect sediments at multiple
locations to understand what the
distribution

901
01:00:17.000 --> 01:00:26.000
of that model input parameter is
forgiven site. -- For a given
site.

902
01:00:26.000 --> 01:00:31.000
The seepage flux workbooks that
Bob has prepared do have default

903
01:00:31.000 --> 01:00:36.000
inputs and we have a recent
technical review of the

904
01:00:36.000 --> 01:00:38.934
literature to provide a more
up-to-date review of what people

905
01:00:38.934 --> 01:00:41.934
have seen under different
settings.

906
01:00:41.934 --> 01:00:46.934
We tried to tie that to the
depositional environment and/or

907
01:00:46.934 --> 01:00:50.934
local geology to give you a
sense of what value you should
be

908
01:00:50.934 --> 01:00:56.000
using for whatever your
particular site is. However, we
would always

909
01:00:56.000 --> 01:01:02.000
recommend if you can attempt to
collect real site-specific

910
01:01:02.000 --> 01:01:06.000
data. But, yes that's an input
parameter for these

911
01:01:06.000 --> 01:01:09.000
models.

912
01:01:09.000 --> 01:01:14.000
>> Another comparison question,
they were interested

913
01:01:14.000 --> 01:01:19.000
if this temperature based
seepage flux estimate could
compare to

914
01:01:19.000 --> 01:01:25.000
something called the ultra seep
meter in terms of

915
01:01:25.000 --> 01:01:27.000
overall accuracy, cost and
limitations. They weren't sure

916
01:01:27.000 --> 01:01:33.000
if you were familiar with that
product and how it compares.

917
01:01:33.000 --> 01:01:36.000
>> I am somewhat familiar with
the product. I believe it's one

918
01:01:36.000 --> 01:01:41.934
that's been developed as part of
the Navy's research program.

919
01:01:41.934 --> 01:01:46.934
In essence, there is going to be
comparability. That particular

920
01:01:46.934 --> 01:01:52.934
platform is really -- one of

921
01:01:52.934 --> 01:01:57.000
its strengths is its ability to
be deployed in deep

922
01:01:57.000 --> 01:02:01.000
surface water depth. It is
something and that's the
situation

923
01:02:01.000 --> 01:02:09.000
that we have not routinely work
in at Superfund Sites in terms

924
01:02:09.000 --> 01:02:12.000
of the accuracy and resolution
of temperature sensors, I don't
know

925
01:02:12.000 --> 01:02:16.000
offhand. I would imagine there
is some level

926
01:02:16.000 --> 01:02:22.000
of overlap. In terms of the
sensors that I've highlighted in
the

927
01:02:22.000 --> 01:02:26.000
presentation, they are ones we
refused that may

928
01:02:26.000 --> 01:02:29.000
not be quite as accurate or
sensitive as those deployed with
the ultra

929
01:02:29.000 --> 01:02:34.000
see but there are those that are
cost competitive and

930
01:02:34.000 --> 01:02:38.934
they are those that we don't
have to have remote data

931
01:02:38.934 --> 01:02:41.934
logging capabilities. They have
built in memory so they retain
the

932
01:02:41.934 --> 01:02:47.934
temperature measurements. We
just retrieve them at some point

933
01:02:47.934 --> 01:02:51.934
in time. In essence, I don't
know that I can truly answer

934
01:02:51.934 --> 01:02:56.000
the question. They are going to
be similar type systems in terms

935
01:02:56.000 --> 01:02:59.000
of what they are attempting to
achieve.

936
01:02:59.000 --> 01:03:04.000
>> Okay. Now, we have some
clarifying

937
01:03:04.000 --> 01:03:09.000
questions. Someone asked about
slide 34 they would like to know
if the

938
01:03:09.000 --> 01:03:15.000
units on site 34 are grams per
day such as mass

939
01:03:15.000 --> 01:03:20.000
flux or gallons per day.

940
01:03:20.000 --> 01:03:26.000
>> The flux

941
01:03:26.000 --> 01:03:32.000
values -- there are two types of
flux values I've posted in the
figures.

942
01:03:32.000 --> 01:03:37.000
One is just looking at water
flux and I've presented two

943
01:03:37.000 --> 01:03:41.934
types of data. One is cubic
meters

944
01:03:41.934 --> 01:03:45.934
per day, which was the total
volume of water through that
cross-section

945
01:03:45.934 --> 01:03:48.934
bounded by the piezometer
clusters and another

946
01:03:48.934 --> 01:03:51.934
value comes directly from 3PE.

947
01:03:51.934 --> 01:03:58.000
That is water flux more like a
specific discharge

948
01:03:58.000 --> 01:04:04.000
which is centimeters per day per
a

949
01:04:04.000 --> 01:04:09.000
unit area. I also presented --
that is

950
01:04:09.000 --> 01:04:13.000
what you are getting from the
seepage flux models. They are
presenting

951
01:04:13.000 --> 01:04:17.000
at water flux in centimeters as
a specific discharge and

952
01:04:17.000 --> 01:04:20.000
centimeters per day per square
meter.

953
01:04:20.000 --> 01:04:25.000
The other -- on that slide that
really is water

954
01:04:25.000 --> 01:04:31.000
flux it's not mass or
contaminant flux. When

955
01:04:31.000 --> 01:04:36.000
I presented data specific to
arsenic, that's a

956
01:04:36.000 --> 01:04:38.000
mass flux where I have actually
taken the concentrations within

957
01:04:38.000 --> 01:04:44.000
the aquifer and/or within the
sediment poor water and
multiplied that

958
01:04:44.000 --> 01:04:53.000
against the discharge.

959
01:04:53.000 --> 01:04:59.000
I did present units that truly
were in milligrams of

960
01:04:59.000 --> 01:05:04.000
arsenic per day per square
meter. The slide that you

961
01:05:04.000 --> 01:05:09.000
have pulled up right here, if
that's the one they are speaking
to

962
01:05:09.000 --> 01:05:14.000
that is in grams per day and
that's from the flow net
analysis that

963
01:05:14.000 --> 01:05:19.000
predated this slide in which we
are actually looking at not just

964
01:05:19.000 --> 01:05:23.000
specific discharge but the
entire volume

965
01:05:23.000 --> 01:05:26.000
of water moving through a
particular cross-section within
the aquifer.

966
01:05:26.000 --> 01:05:32.000
Those units are going to be
slightly different because they
were taking

967
01:05:32.000 --> 01:05:37.934
account for the area within the
aquifer where that contaminant

968
01:05:37.934 --> 01:05:40.934
mass is moving.

969
01:05:40.934 --> 01:05:45.934
>> Okay. The next question is in
reference to slide 42. For

970
01:05:45.934 --> 01:05:51.934
slide 42 they want to know if
both figures are showing
locations

971
01:05:51.934 --> 01:05:56.000
east of the barrier wall. I'm
pulling that up

972
01:05:56.000 --> 01:05:59.000
right now.

973
01:05:59.000 --> 01:06:03.000
>> Yes. Those are two sets of
piezometer clusters that were

974
01:06:03.000 --> 01:06:07.000
east of the barrier wall but
west of the Cove. They

975
01:06:07.000 --> 01:06:15.000
were previously installed in the
intervening space that
ultimately

976
01:06:15.000 --> 01:06:18.000
got cut off from the landfill
following installation of the
barrier

977
01:06:18.000 --> 01:06:19.000
wall.

978
01:06:19.000 --> 01:06:22.000
>> Okay. We have a couple of
questions about this case study
and I will

979
01:06:22.000 --> 01:06:27.000
start with the ones on the
barrier wall. One

980
01:06:27.000 --> 01:06:30.000
participant noted the barrier
wall mitigated groundwater
discharge

981
01:06:30.000 --> 01:06:35.000
to the Cove but arsenic impacted
groundwater still needs to

982
01:06:35.000 --> 01:06:40.934
flow somewhere. They would like
to know where is the diverted
groundwater

983
01:06:40.934 --> 01:06:41.934
now flowing?

984
01:06:41.934 --> 01:06:46.934
>> That is an issue for the site
as a whole. What I did not speak

985
01:06:46.934 --> 01:06:52.934
to just for perspective and
brevity, was that

986
01:06:52.934 --> 01:06:59.000
the plume itself has another
arm, if you will come up that

987
01:06:59.000 --> 01:07:03.000
is discharging in a direction
north or it's moving

988
01:07:03.000 --> 01:07:07.000
north come of the north end of
the landfall has a groundwater
extraction

989
01:07:07.000 --> 01:07:12.000
and treatment system.
Installation of this barrier
wall while it did

990
01:07:12.000 --> 01:07:16.000
cut off the flow directly to the
Cove where it was discharged and

991
01:07:16.000 --> 01:07:22.000
redirect it it along a path that
is now headed

992
01:07:22.000 --> 01:07:26.000
towards the groundwater
extraction system. The plume
itself

993
01:07:26.000 --> 01:07:31.000
within the landfill hasn't been
dealt with by this barrier wall.

994
01:07:31.000 --> 01:07:36.000
That's why I said this was an
intermediate step. The barrier
wall was

995
01:07:36.000 --> 01:07:40.934
only addressing the issue of
impacts to the lake specifically
in

996
01:07:40.934 --> 01:07:45.934
that Cove. Other portions in the
lake, it extends further north,

997
01:07:45.934 --> 01:07:50.934
actually you move further north
and downstream within that flow

998
01:07:50.934 --> 01:07:55.000
through Lake you enter an area
where the lake starts to

999
01:07:55.000 --> 01:07:59.000
read charge -- recharged aquifer
system and

1000
01:07:59.000 --> 01:08:03.000
pushes against the contaminant
plume that's moving North
underneath

1001
01:08:03.000 --> 01:08:05.000
the landfill.

1002
01:08:05.000 --> 01:08:11.000
>> I think you have highlighted
this but to

1003
01:08:11.000 --> 01:08:14.000
clarify, now that the flow of
arsenic contaminated groundwater

1004
01:08:14.000 --> 01:08:18.000
has been deflected from the pond
are there other surface water
bodies

1005
01:08:18.000 --> 01:08:22.000
further down gradient to the
north that

1006
01:08:22.000 --> 01:08:25.000
are impacted?

1007
01:08:25.000 --> 01:08:30.000
>> That potential exists or
those site character

1008
01:08:30.000 --> 01:08:33.000
raises -- characterization has
gone beyond the northern South
laundry

1009
01:08:33.000 --> 01:08:38.934
which is the direction the main
blew is moving

1010
01:08:38.934 --> 01:08:41.934
and while data has shown there's
been migration

1011
01:08:41.934 --> 01:08:46.934
in the deeper groundwater North
of the site boundary there does

1012
01:08:46.934 --> 01:08:50.934
not appear to be ongoing impacts
to a wetland

1013
01:08:50.934 --> 01:08:55.000
system and stream that's farther
north of the site which doesn't

1014
01:08:55.000 --> 01:08:59.000
mean that it couldn't happen.
Right now, it appears

1015
01:08:59.000 --> 01:09:04.000
at least the groundwater
extraction system is addressing
the majority

1016
01:09:04.000 --> 01:09:09.000
of that migration north of the
site. I'm glad that question

1017
01:09:09.000 --> 01:09:11.000
was asked, that something to
consider.

1018
01:09:11.000 --> 01:09:16.000
You have to think about where
groundwater will ultimately be
moving beyond

1019
01:09:16.000 --> 01:09:20.000
the site boundaries. It could be
that it could impact either

1020
01:09:20.000 --> 01:09:25.000
down gradient water supply wells
and/or surface water bodies and

1021
01:09:25.000 --> 01:09:29.000
it depends on the local geology,
topography

1022
01:09:29.000 --> 01:09:34.000
and the groundwater flow system.

1023
01:09:34.000 --> 01:09:38.934
>> Okay. Someone wanted to know
if there was a review of
monitoring

1024
01:09:38.934 --> 01:09:45.934
data Paris feel to the barrier
wall -- Paris feel to

1025
01:09:45.934 --> 01:09:48.934
bypass arsenic.

1026
01:09:48.934 --> 01:09:51.934
>> Yes, there has and that data
was not

1027
01:09:51.934 --> 01:09:57.000
included in this presentation
but I did indicate on one of the

1028
01:09:57.000 --> 01:10:03.000
slides that it was the one the
flow net slide in there --

1029
01:10:03.000 --> 01:10:07.000
the whole Cove is ringed by
nested

1030
01:10:07.000 --> 01:10:13.000
piezometers. We've been
monitoring that around the Cove.
The site

1031
01:10:13.000 --> 01:10:17.000
robbery owner also has
monitoring wells that extend
beyond

1032
01:10:17.000 --> 01:10:22.000
the perimeter of the Cove both
South and northern shoreline of
the lake

1033
01:10:22.000 --> 01:10:26.000
to monitor that specific issue.
There is no indication

1034
01:10:26.000 --> 01:10:30.000
to date to indicate that at
least the plume was discharging

1035
01:10:30.000 --> 01:10:32.000
to the Cove is bypassing.

1036
01:10:32.000 --> 01:10:37.000
There is other data that would
suggest the deflection

1037
01:10:37.000 --> 01:10:40.934
that's occurred because of the
barrier wall has been quite
effective. It

1038
01:10:40.934 --> 01:10:46.934
is moving further north and it's
deflected enough that it's not

1039
01:10:46.934 --> 01:10:49.934
circling around the northern or
southern end of the barrier
wall.

1040
01:10:49.934 --> 01:10:55.000
Part of the design of that
barrier wall was informed by the
spatial

1041
01:10:55.000 --> 01:11:00.000
distribution of not only flux
measurements but groundwater
chemistry. The

1042
01:11:00.000 --> 01:11:04.000
length of the barrier wall over
which was constructed

1043
01:11:04.000 --> 01:11:09.000
was informed by our knowledge of
the distribution of the
contaminant

1044
01:11:09.000 --> 01:11:14.000
plume as well as the
distribution of the contaminant
discharge

1045
01:11:14.000 --> 01:11:15.000
environment.

1046
01:11:15.000 --> 01:11:19.000
>> Well, you literally lead
right into the next question
which is

1047
01:11:19.000 --> 01:11:22.000
on the design of the hydraulic
barrier.

1048
01:11:22.000 --> 01:11:27.000
It seems like a high cost
alternative and they were
curious

1049
01:11:27.000 --> 01:11:31.000
as to what other technologies
were evaluated assuming arsenic

1050
01:11:31.000 --> 01:11:35.000
needed to be removed from
groundwater.

1051
01:11:35.000 --> 01:11:39.934
>> In terms of the goal of
shutting off plume discharge,
the barrier

1052
01:11:39.934 --> 01:11:45.934
wall has relative potentially
high upfront capital costs.
There isn't

1053
01:11:45.934 --> 01:11:47.934
any actual remedial monitoring
costs

1054
01:11:47.934 --> 01:11:54.000
with the barrier wall. Once it's
in place unless it fails and
needs

1055
01:11:54.000 --> 01:11:59.000
to be repaired or replaced,
there aren't additional

1056
01:11:59.000 --> 01:12:02.000
maintenance costs associated
with it other than

1057
01:12:02.000 --> 01:12:07.000
monitoring costs. Those
monitoring costs will be present
regardless

1058
01:12:07.000 --> 01:12:12.000
of the remedial technology. I
should point out that barrier
wall is not

1059
01:12:12.000 --> 01:12:17.000
a permeable barrier. It's not
designed to actually

1060
01:12:17.000 --> 01:12:21.000
chemically remove arsenic as the
groundwater passes through it.
That

1061
01:12:21.000 --> 01:12:26.000
could have been an option
considered for this application
or

1062
01:12:26.000 --> 01:12:33.000
other applications. One could
put in some sort of a wall or

1063
01:12:33.000 --> 01:12:36.000
other configure where you allow
the contaminated groundwater to

1064
01:12:36.000 --> 01:12:40.934
pass through but the material
you include in the semi
permeable wall

1065
01:12:40.934 --> 01:12:46.934
actually has chemical acetate

1066
01:12:46.934 --> 01:12:50.934
-- capacity to remove or observe
-- absorb the

1067
01:12:50.934 --> 01:12:56.000
contaminant. That would be the
option you could consider if
just redirecting

1068
01:12:56.000 --> 01:13:00.000
the contaminated plume flow is
not something that

1069
01:13:00.000 --> 01:13:03.000
works for your site. Likewise,
I've seen situations

1070
01:13:03.000 --> 01:13:09.000
where people have installed
react of sediment caps

1071
01:13:09.000 --> 01:13:12.000
to try to do the same thing
where the installation is not
within the

1072
01:13:12.000 --> 01:13:17.000
aquifer but actually within the
surface water bodies. The issue

1073
01:13:17.000 --> 01:13:22.000
is that you really -- that's
where doing these

1074
01:13:22.000 --> 01:13:25.000
types of contaminant flux not
only water flux but contaminant
flux

1075
01:13:25.000 --> 01:13:30.000
within the surface water bodies
becomes critical, they are

1076
01:13:30.000 --> 01:13:35.000
very important to know in terms
of understanding

1077
01:13:35.000 --> 01:13:37.934
what capacity to design into
that type of reactive barrier if
you

1078
01:13:37.934 --> 01:13:42.934
apply it as a sediment cap
within the surface water bodies.

1079
01:13:42.934 --> 01:13:49.934
>> Thank you. Just a few more
questions

1080
01:13:49.934 --> 01:13:54.000
in queue. If you have a question
or comment now is your last call

1081
01:13:54.000 --> 01:14:00.000
to get those in before we close
out. This

1082
01:14:00.000 --> 01:14:06.000
question is in the comparison
technology category. Is there
any

1083
01:14:06.000 --> 01:14:10.000
work to compare the old baggage
meter to

1084
01:14:10.000 --> 01:14:14.000
the temperature profile seepage
determination?

1085
01:14:14.000 --> 01:14:20.000
>> Yes, multiple groups have
done that. We have done

1086
01:14:20.000 --> 01:14:25.000
that also with our own seepage
measurements. This is something

1087
01:14:25.000 --> 01:14:29.000
that Bob has done prior to
focusing on the sediment

1088
01:14:29.000 --> 01:14:35.000
temperature profile approach he
was doing work using seepage

1089
01:14:35.000 --> 01:14:38.000
flux meters. You would deploy
these similar to what you are
describing

1090
01:14:38.000 --> 01:14:44.000
in multiple locations with the
surface water bodies to get a
direct measurement

1091
01:14:44.000 --> 01:14:47.000
at that deployment area. We have
also done

1092
01:14:47.000 --> 01:14:53.000
comparison measurements of the
temperature profiling method
with other groups

1093
01:14:53.000 --> 01:14:59.000
specifically a group from the
USGS office in Golden, Colorado.

1094
01:14:59.000 --> 01:15:04.000
That individual is referenced in
the acknowledgments.

1095
01:15:04.000 --> 01:15:10.000
I encourage you to look up that
individual. They have a wealth

1096
01:15:10.000 --> 01:15:13.000
of information not only in terms
of the years they have done to
do

1097
01:15:13.000 --> 01:15:15.000
this type of assessment but also
they are connected to a
long-term

1098
01:15:15.000 --> 01:15:21.000
research site in Minnesota where
a lot of this comparison work
has

1099
01:15:21.000 --> 01:15:27.000
been done. I don't know, Bob do
you want to add

1100
01:15:27.000 --> 01:15:32.000
anything? No, but yes we've done
it internally and others have

1101
01:15:32.000 --> 01:15:36.000
done method comparisons and
we've collaborated with folks
external

1102
01:15:36.000 --> 01:15:40.934
to the EPA for this particular
purpose.

1103
01:15:40.934 --> 01:15:47.934
>> We have another clarifying
question on units. This is in
reference to

1104
01:15:47.934 --> 01:15:56.000
slides 45 and 46. They say, I
noticed the seepage flux

1105
01:15:56.000 --> 01:16:02.000
reported on 45 and 46 are in
units of centimeters per

1106
01:16:02.000 --> 01:16:04.000
day meters squared is that
correct?

1107
01:16:04.000 --> 01:16:10.000
Normally a volumetric flow per
unit area is reported with units
of length

1108
01:16:10.000 --> 01:16:15.000
per time such as centimeters per
day.

1109
01:16:15.000 --> 01:16:20.000
>> Yes, there's two ways to
calculate or present flux data.

1110
01:16:20.000 --> 01:16:26.000
In this case I am presenting the
flux data as a specific

1111
01:16:26.000 --> 01:16:32.000
discharge. That's a linear
distance per time over

1112
01:16:32.000 --> 01:16:37.000
some unit area. If I wanted to
calculate an equivalent

1113
01:16:37.000 --> 01:16:41.934
volumetric flux I would have to
take that number and multiply it

1114
01:16:41.934 --> 01:16:45.934
by what is the cross-sectional
area that I'm

1115
01:16:45.934 --> 01:16:51.934
actually monitoring in support
of these calculations. In that

1116
01:16:51.934 --> 01:16:58.000
case, you could then convert
this to what would be

1117
01:16:58.000 --> 01:17:04.000
more of a volumetric flux. This
is just to point out and

1118
01:17:04.000 --> 01:17:09.000
it's somewhat an issue with the
terminology used

1119
01:17:09.000 --> 01:17:15.000
in the hydrologic literature. It
can be confusing at

1120
01:17:15.000 --> 01:17:18.000
times. Steve, is this something
you want to address

1121
01:17:18.000 --> 01:17:21.000
or add to?

1122
01:17:21.000 --> 01:17:27.000
>> I think you have summed it
up.

1123
01:17:27.000 --> 01:17:31.000
It's specific discharge versus
volumetric flux and when you
calculate

1124
01:17:31.000 --> 01:17:37.000
your volumetric flux that's
using a unit

1125
01:17:37.000 --> 01:17:44.934
square area, whatever your units
are.

1126
01:17:44.934 --> 01:17:50.934
>> They are still confused and
want to know exactly what does
CM

1127
01:17:50.934 --> 01:17:54.000
per day stand for?

1128
01:17:54.000 --> 01:18:00.000
>> That centimeter per day per
square meter where the per
square

1129
01:18:00.000 --> 01:18:05.000
meter is a specific discharge
that one applies to unit

1130
01:18:05.000 --> 01:18:09.000
area. If one wanted to apply
that over a certain area

1131
01:18:09.000 --> 01:18:15.000
within aquifer you would have to
take account of the area

1132
01:18:15.000 --> 01:18:18.000
that aquifer to factor in and
that would convert

1133
01:18:18.000 --> 01:18:22.000
this number to something that
would be a volumetric

1134
01:18:22.000 --> 01:18:25.000
flux.

1135
01:18:25.000 --> 01:18:28.000
>> Okay.

1136
01:18:28.000 --> 01:18:30.000
Thank you.

1137
01:18:30.000 --> 01:18:34.000
Another participant wants to
know how can you access the
spreadsheet

1138
01:18:34.000 --> 01:18:37.000
models you've discussed?

1139
01:18:37.000 --> 01:18:42.934
>> The 3PE model for
groundwater, is

1140
01:18:42.934 --> 01:18:47.934
available and the report is
referenced in

1141
01:18:47.934 --> 01:18:54.000
the attached spreadsheet tool
and it's referenced in

1142
01:18:54.000 --> 01:18:59.000
this presentation. It's also
included as an information link
on the website.

1143
01:18:59.000 --> 01:19:05.000
If you go to that link for 3PE,
you will find both a PDF
document

1144
01:19:05.000 --> 01:19:08.000
as well as an Excel work.

1145
01:19:08.000 --> 01:19:14.000
You download the work book and
that's your calculation

1146
01:19:14.000 --> 01:19:19.000
tool. In terms of the seepage
flux model, those are not in

1147
01:19:19.000 --> 01:19:25.000
a form that can be handed over
at this moment. They have gone
through

1148
01:19:25.000 --> 01:19:29.000
internal clearance and we are
also in the process of
publishing them.

1149
01:19:29.000 --> 01:19:35.000
At which point they will be made

1150
01:19:35.000 --> 01:19:37.000
publicly available. Right now,
the ones we have developed are
not ready

1151
01:19:37.000 --> 01:19:41.934
to hand over although several
folks within the regions have
done beta

1152
01:19:41.934 --> 01:19:44.934
testing for them.

1153
01:19:44.934 --> 01:19:47.934
That's why, if you are
interested in other

1154
01:19:47.934 --> 01:19:51.934
tools that currently are
available from other sources
this is information

1155
01:19:51.934 --> 01:19:55.000
we can provide separately by
pointing you to those sources
and in one

1156
01:19:55.000 --> 01:19:59.000
case at least one of those tools
is also a

1157
01:19:59.000 --> 01:20:03.000
spreadsheet-based tool that you
can use Excel to operate. Some

1158
01:20:03.000 --> 01:20:09.000
of the others that are freeware
are those that are add-ins to

1159
01:20:09.000 --> 01:20:15.000
commercial software and what's
the software -- the

1160
01:20:15.000 --> 01:20:18.000
commercial software?

1161
01:20:18.000 --> 01:20:25.000
>> I don't think they are
commercial software. There

1162
01:20:25.000 --> 01:20:31.000
are two molecules in
[ Indiscernible ] and I'm

1163
01:20:31.000 --> 01:20:37.000
not sure they are commercial I
think they are free. You need

1164
01:20:37.000 --> 01:20:42.934
to type meth lab to get the
module from

1165
01:20:42.934 --> 01:20:48.934
the author -- med

1166
01:20:48.934 --> 01:20:50.934
lab to get the module from the
author.

1167
01:20:50.934 --> 01:20:57.000
We don't have those modules, we
have not

1168
01:20:57.000 --> 01:21:03.000
used them. If you contact the
author of those

1169
01:21:03.000 --> 01:21:08.000
models like Swanson in 2011 in

1170
01:21:08.000 --> 01:21:17.000
Gordon 2012. they can probably
give you direction of how to

1171
01:21:17.000 --> 01:21:20.000
obtain those.

1172
01:21:20.000 --> 01:21:29.000
Not one probe is window based --

1173
01:21:29.000 --> 01:21:33.000
program it's another platform. I
think you can

1174
01:21:33.000 --> 01:21:38.934
download it from there website
and as for the

1175
01:21:38.934 --> 01:21:47.934
XL -- XL

1176
01:21:47.934 --> 01:21:54.000
-- it was published in 2017.
It's

1177
01:21:54.000 --> 01:22:01.000
a spreadsheet. But we only deal
with

1178
01:22:01.000 --> 01:22:07.000
steady-state solutions. It's
specific for a steady-state
solution

1179
01:22:07.000 --> 01:22:13.000
but they are capable of handling

1180
01:22:13.000 --> 01:22:16.000
layer profile. I remember from
earlier someone asked about

1181
01:22:16.000 --> 01:22:21.000
layering and yes some of this
work book can handle

1182
01:22:21.000 --> 01:22:24.000
that situation.

1183
01:22:24.000 --> 01:22:28.000
>> We can provide a list of
those references and where they

1184
01:22:28.000 --> 01:22:30.000
are available.

1185
01:22:30.000 --> 01:22:34.000
You are -- URL addresses where
folks can download the

1186
01:22:34.000 --> 01:22:38.934
calculation tools and/or
documentation that may be free.
We can send you

1187
01:22:38.934 --> 01:22:47.934
that in a separate document that
can be posted on

1188
01:22:47.934 --> 01:22:48.934
the website.

1189
01:22:48.934 --> 01:22:51.934
But in terms of the ones we've
developed in-house, we are
working on the

1190
01:22:51.934 --> 01:22:55.000
publication and public release
process.

1191
01:22:55.000 --> 01:23:01.000
Unfortunately, I doubt they will
occur

1192
01:23:01.000 --> 01:23:02.000
prior to a period of six months
before they can be downloaded

1193
01:23:02.000 --> 01:23:04.000
for use.

1194
01:23:04.000 --> 01:23:09.000
>> Okay. I think we will close
out our question period. In our
last

1195
01:23:09.000 --> 01:23:15.000
few moments, I would like to
echo the thanks

1196
01:23:15.000 --> 01:23:17.000
for the over 320 people who
chimed in fourth today's

1197
01:23:17.000 --> 01:23:22.000
broadcast from all over the
world as well as the presenters

1198
01:23:22.000 --> 01:23:26.000
who took time from their day to
join us for today's

1199
01:23:26.000 --> 01:23:29.000
live broadcast. There are some
final reminders I would like to
walk the

1200
01:23:29.000 --> 01:23:33.000
audience through before closing
out today. As we noted at the
start

1201
01:23:33.000 --> 01:23:37.934
of the broadcast, these Internet
seminars are available on the

1202
01:23:37.934 --> 01:23:43.934
network or if you are interested
in learning about the next

1203
01:23:43.934 --> 01:23:48.934
free technical webinar we're
offering we encourage you to
visit our website

1204
01:23:48.934 --> 01:23:52.934
or sign up for our monthly
newsletter that comes out on the
first of

1205
01:23:52.934 --> 01:23:56.000
each month. If you are looking
for some of the references that
were

1206
01:23:56.000 --> 01:24:02.000
highlighted during the
presentation such as the 3PE
reference or the

1207
01:24:02.000 --> 01:24:07.000
other case studies and
supporting documentation you
will find it on

1208
01:24:07.000 --> 01:24:12.000
the seminar homepage if you
follow the links in the middle
right there

1209
01:24:12.000 --> 01:24:17.000
is a link to seminar resources,
you can open

1210
01:24:17.000 --> 01:24:22.000
up the browse site and you can
access the

1211
01:24:22.000 --> 01:24:26.000
discussed references. There will
be additional materials added
after

1212
01:24:26.000 --> 01:24:29.000
the broadcast. If you are one of
those replaying the recorded
version

1213
01:24:29.000 --> 01:24:32.000
the links will still work so you
can still click through and
access

1214
01:24:32.000 --> 01:24:36.000
resources. I ask each of you to
take a moment to

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fill out our feedback form and
let us know what you thought of
the

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session. One of the most common
questions is, do I offer CEU's

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or PDH and while we don't we do
give you a seminar

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01:24:48.000 --> 01:24:53.000
participation certificate after
you fill

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out feedback. If you click the
link to the seminar feedback
form and

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01:24:57.000 --> 01:24:59.000
fill out the form please know I
read each one of your
submissions

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01:24:59.000 --> 01:25:04.000
for our sessions, there's a box
at the bottom and

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as long as you fill that out
completely and correctly
specifically with

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your email address being correct
and check the box you were here

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01:25:10.000 --> 01:25:14.000
for the entire session when you
submit the form you will have
immediate

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access to a certificate.

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Each person can fill out their
own version of the feedback form

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so if you participate as a group
from one location with another

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01:25:25.000 --> 01:25:28.000
registration information each
can fill out the form on your
own for

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01:25:28.000 --> 01:25:31.000
your own certificate regardless
of how you registered. I want to

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01:25:31.000 --> 01:25:36.000
think again everybody who joined
for the

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live broadcast and you will
automatically get an email once
the archived version

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01:25:39.934 --> 01:25:44.934
is available. Thank you, very
much for

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01:25:44.934 --> 01:25:49.934
joining us. This is the formal
conclusion of this broadcast.