Abstracts

out in heterogeneous and anisotropic littoral silts and sands. A field site was instrumented
with five direct-push wells arranged in a diamond pattern using about 10-m spacing. Direct-push
wells were installed with long screens placed in direct contact with natural sediments,
thus allowing flexibility in the design of high-resolution hydraulic tests using packers.
In these wells, horizontal K (Kh) was estimated at a 15-cm spacing using an electromagnetic
flowmeter and multilevel slug tests, while Kh, K anisotropy (Kv/Kh) and specific storage (Ss)
were characterized at 60-cm vertical intervals using vertical interference slug tests within a
well and tomographic slug tests across wells. Furthermore, sediment samples were collected
near the wells to assess Kh and Kv using grain size analyses and laboratory permeameter tests,
respectively. The hydraulic property fields obtained from the different measurement methods
were then quantitatively evaluated by predicting transient head responses from independent
hydraulic tests using a forward numerical model. Results show that independent hydraulic
tests are fairly well reproduced with vertical interference slug tests. So, even though this approach
requires more complex numerical inverse analysis than conventional hydraulic tests
with analytical solutions, it proves to be relatively time efficient considering that Kh, Kv/Kh
and Ss can be estimated together. Tomographic slug tests are also shown to better represent
transient hydraulic responses between wells, but the additional instrumentation costs and
data burden involved compared to vertical interference slug tests should be carefully considered
for practical field studies. Finally, this study shows that the strong Kv/Kh anisotropy
at the scale of test measurements can make K characterization challenging. The study also
highlights the need for hydraulic methods that can reliably estimate Kv/Kh, since groundwater
flow is strongly influenced by K anisotropy.
262 - Advanced techniques for site characterization: Real-Time
High-Resolution Site Characterization of the Subsurface Using
and MIP, LIF and HPT
Patrick O’Neill
Vertex Environmental Inc, Cambridge, Ontario, Canada
In-situ site characterization can be a key component of site delineation and remediation.
In-situ site characterization allows for large amounts of detailed data to be collected quickly
and cost-effectively compared to traditional techniques. These data, combined with traditional
Phase II Environmental Site Assessment (ESA) methods, greatly enhance the understanding
of the presence, concentration and distribution of contaminants in the subsurface,
which can lead to more efficient and focused monitoring and remediation programs.
Three high-resolution characterization technologies have recently been introduced to
Canada. These include, the Membrane Interface Probe (MIP) for dissolved phase contamination,
the Laser-Induced Fluorescence (LIF) probe for free-phase petroleum hydrocarbon
(PHC) contamination, and the Hydraulic Profiling Tool (HPT) for measuring
the subsurface permeability and ultimately estimating the hydraulic conductivity of the
subsurface. All three probes are advanced to depth by direct push methods (Geoprobe).
The MIP is a heated probe that is used to volatilize dissolved and sorbed contaminants.
The contaminants diffuse through a semi-permeable membrane on the probe and are sub-
100 IAH-CNC 2015 WATERLOO CONFERENCE