Heat Extraction Barrier Pilot Study Data Needs –Update
Subject: Heat Extraction Pilot Study Updated Data Needs to Adequately Evaluate Potential
Effectiveness of Heat Extraction Barrier, West Lake Landfill
Date: October 9, 2105
One of the alternatives evaluated in the October 2014 Isolation Barrier Alternatives Analysis
report submitted by Bridgeton Landfill LLC is a heat extraction barrier. However, the
Alternatives Analysis report lacked detailed information necessary for USACE to make an
independent technical evaluation of the potential effectiveness of such a system. Since the
October report was submitted, Bridgeton Landfill LLC proposed to expand on the current test
well (GIW-4) and perform a pilot study to obtain information to demonstrate the effectiveness of
this proposed alternative and to obtain data necessary for design of the system. It is USACE’s
understanding that this expansion pilot study was approved by the Missouri Department of
Natural Resources (MDNR) and implemented.
In December 2014, USACE submitted to EPA the information listed below. This list is
information USACE will need regarding the heat extraction study at GIW -4 and the pilot study
expansion system that consisted of retrofitting 6 additional GIW wells with recirculation coolant
tubes, to assess whether adequate information is being collected to design an effective heat
It is USACE’ s understanding that the pilot study data that was submitted to the Missouri
Department of Natural Resources (MDNR) was posted on their website. USACE reviewed the
information posted on the MDNR web site and supplemented the list below with what
information was identified from that web page. The supplemental information is included below
in brackets with text bolded. If there is no bracketed/balded information, we could not locate the
• Schematic of the modified GIW -4 used in the preliminary heat extraction study including
depth and construction of the well and all pipe sizes where fluid is flowing [MDNR website
has a submittal from Republic that shows a schematic of the cooling loop proposed for
the expanded pilot. As-built information was not provided]
• Details of the cooling equipment and/or coolant being used in the pilot study.
• The preliminary data collected from the heat extraction study at GIW -4 including inflow and
outflow water temperatures, flow rate, and the temperature within the casing measured at
• Calculations to determine the 25kW extraction rate.
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• Location of the 6 additional GIW wells to be retrofitted with recirculation coolant tubes
including depth and construction of the wells and all pipe sizes where fluid will flow.
[MDNR website has a Republic submittal requesting expansion of the pilot study and
includes a plan view of proposed GIW wells and locations of proposed new temperature
• An explanation ofhow the modified GIW wells are representative of the proposed driven
heat extraction wells and whether or not a pilot study of driven wells of the material proposed
for the full scale system will be tested prior to design and installation of the system.
• Plans of the proposed closed loop header system used to convey cooling water to the
• Location of current Temperature Monitoring Probes and depths and proposed locations and
depths of temperature measurements when the pilot study is expanded.
• Proposed study procedures including assumptions used.
• Proposed calculations to determine thermal conductivity and heat storage properties of the
landfill waste. In addition, how is obtaining thermal conductivity and heat storage properties
of the South/North Bridgeton landfill waste representative of these properties in the proposed
location of the heat extraction system in the West Lake Landfill waste?
• Results of the assessment ofheat front progress to the north and the rate of energy flux to the
• Calculations used to predict the amount of heat that could be extracted under steady state
conditions and the results of those calculations.
• A plan view of the proposed Temperature Monitoring Points as well as a cross section
showing depth intervals of temperature readings. Attachment C indicates it is envisioned as
one array per 120 feet would be sufficient. Is this 120 ft spacing parallel with the proposed
barrier? [[MDNR website has a Republic submittal requesting expansion of the pilot
study and includes a plan view of proposed GIW wells and locations of proposed new
• It appears the settling front associated with the SSE would render the heat exchange system
non-functional if the system fell within the influence of settlement (similar to the need to set
back Option 3 IB wall). Therefore, it appears the heat exchange system would need to halt
the SSE and settling front some distance south of the barrier to prevent this failure from
occurring. What distance is this and what temperature needs to be attained some distance
from the barrier to prevent this from happening?
On October 8, EPA notified US ACE that Republic Services had provided them with more details
of the cooling system. Once that information is provided, US ACE will review that information
and provide further updates, as required, on what additional information is necessary to evaluate
the cooling loop pilot with the potential of utilizing it as a thermal barrier option for the isolation
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If you have any questions, please contact me at 816-389-3615.