This comment letter response contains two parts:   

(1) The original submittal from the commenter.

(2) A data base printout of EPA’s response to each point raised by the commenter.

Notes about the response letters:

• The response letters were generated by a data base used to track the content of all public

comment submittals and ensure that the Agency responds to each. Each comment letter

was assigned a Letter ID that corresponds to the last four digits of the docket number of the

original comment (as posted on www.regulations.gov).

• Each response letter includes: comment text; an EPA‐assigned comment code; and an

individual response. These are described and explained below.  

• The data base contains Comment text from the letters submitted by commenters.  

Many hard copy letters were scanned into electronic format for inclusion in the data

base. As a result, there may be some typographical errors attributable to optical

character recognition issues.  However, all original submittals were reviewed in the

process of drafting responses to ensure that the comment content was understood and

appropriately addressed.

• The content of each comment letter was divided into topic areas and assigned a unique

Comment ID.  Additionally, one or more Comment Codes (i.e., unique topic area ID) was

assigned to each discrete point raised by a commenter. This information was added to

the data base. To inform final rulemaking decisions, all comments and information

received on a given topic were reviewed by technical experts in each rule area (e.g., on

construction requirements).  

• Following decisions on the final rule requirements, Individual responses were drafted

by topic area to ensure completeness and consistency of the responses with the final

rule and other responses to similar comments.  Each discrete point made by a

commenter was given a unique response.

• Upon completion of comment responses, all information was entered into the data base.

Each letter response is a compilation of each comment and its individual response,

compiled in the order of the original comment letter.  As a result of this process, there is

repetition in the response text.  The Agency believes this approach ensures completeness

and attention to each comment letter that was submitted.   

• All comments in a topic area were reviewed, evaluated, and responded to concurrently.  

Responses on each topic area are compiled and are also available in the rulemaking docket.
Document ID: EPA-HQ-OW-2008-0390-0120

Last Name: Spencer

First Name: Homer

Title: P. Eng.

Organization: Canitron Systems Inc.

City: Calgary

State: AB

Phone Number: (403)259-8732

Current Category Code: 256

Comment: For the past four years, our company has been field testing our proprietary systems and methods for 

utilizing a low melting point fusible metal alloy to mold in situ plugs in wells to repair gas leakage problems. Our 

focus has been on repair of vent gas flows that occur because of channels that exist within the cement 

surrounding production casing in wells. Our field tests have been carried out with permission of the Alberta 

Energy Resources Control Board ("ERCB") and under their scrutiny. We presently have a proposal under

consideration by the ERCB and the Canadian Association of Petroleum Producers (CAPP) to add our methods to 

the approved well abandonment protocols presently under review in Alberta.

We believe our methods are directly applicable to the problem of long term leakage of sequestered GHG from 

wells that penetrate a reservoir used for the sequestration. Obviously, it makes neither economic nor 

environmental sense to capture, concentrate, compress, deliver, and inject CO2 into depleted reservoirs or 

saltwater formations if there is not a reliable sealing method used on existing wells in that reservoir to prevent 

the CO2 leaking back into the atmosphere. We believe that our plugging methods can assure long term success 

in preventing this leakage.

We use an alloy of bismuth and tin for our sealing medium. This alloy is non- toxic and will not corrode or cause 

corrosion in the relevant well environment from either chemical or galvanic processes. We believe we can seal a 

well against gas flow even if the well casing has been entirely corroded away. The important properties of the 

alloy that cause it to be effective are:

1) it expands about 1% by volume when solidifying from the liquid phase; 2) it is impermeable to gas flow; 3) it 

seals effectively in dirty oily casing; 4) it has a high specific gravity to facilitate displacement of other fluids 

present during the deployment process; and 5) it has a very low viscosity and surface tension such that it will 

enter small fissures, and absorb into and wet permeable rocks such as sandstone.

Only small amounts of the alloy are required to form a seal with the differential pressure strength required to 

seal GHG sequestration wells. We set the plugs using an electric heater deployed on a wire line. The procedure is

both fast and inexpensive. We have data to back the above contentions, including corrosion tests carried out in 

a CO2/saltwater environment with a pH of 3 that indicate plug life in steel casing in excess of 10,000 years.

Regards,

Homer Spencer

P.Eng.

Canitron Systems Inc.

Calgary, AB, Canada

Ph/Fax: (403)259-8732

Cell: (403)616-5247
Letter ID: 0120 

Commenter: Homer Spencer 

Organization: Canitron Systems Inc. 

Letter ID: 0120 Comment ID: 22071 Letter Lines: 15 to 53 

Comment Code: 1310 1.1.2.4 Comments on other "out of scope" issues, e.g., pore space 

ownership 

Comment Code: 1350 1.1.3.3 Comments on the need for GS technology 

Comment Code: 3460 2.2.2.3 Acceptable corrective action techniques for GS sites (e.g., 

cements) 

Comment: For the past four years, our company has been field testing our 

proprietary systems and methods for utilizing a low melting point fusible metal 

alloy to mold in situ plugs in wells to repair gas leakage problems. Our focus 

has been on repair of vent gas flows that occur because of channels that exist 

within the cement surrounding production casing in wells. Our field tests have 

been carried out with permission of the Alberta Energy Resources Control Board 

("ERCB") and under their scrutiny. We presently have a proposal under 

consideration by the ERCB and the Canadian Association of Petroleum Producers 

(CAPP) to add our methods to the approved well abandonment protocols presently 

under review in Alberta. 

We believe our methods are directly applicable to the problem of long term 

leakage of sequestered GHG from wells that penetrate a reservoir used for the 

sequestration. Obviously, it makes neither economic nor environmental sense to 

capture, concentrate, compress, deliver, and inject CO2 into depleted reservoirs 

or saltwater formations if there is not a reliable sealing method used on 

existing wells in that reservoir to prevent the CO2 leaking back into the 

atmosphere. We believe that our plugging methods can assure long term success in 

preventing this leakage. 

We use an alloy of bismuth and tin for our sealing medium. This alloy is nontoxic and will not corrode or cause corrosion in the relevant well environment 

from either chemical or galvanic processes. We believe we can seal a well 

against gas flow even if the well casing has been entirely corroded away. The 

important properties of the alloy that cause it to be effective are: 

1) it expands about 1% by volume when solidifying from the liquid phase; 2) it 

is impermeable to gas flow; 3) it seals effectively in dirty oily casing; 4) it 

has a high specific gravity to facilitate displacement of other fluids present 

during the deployment process; and 5) it has a very low viscosity and surface 

tension such that it will enter small fissures, and absorb into and wet 

permeable rocks such as sandstone. 

1
2

Only small amounts of the alloy are required to form a seal with the 

differential pressure strength required to seal GHG sequestration wells. We set 

the plugs using an electric heater deployed on a wire line. The procedure is 

both fast and inexpensive. We have data to back the above contentions, including 

corrosion tests carried out in a CO2/saltwater environment with a pH of 3 that 

indicate plug life in steel casing in excess of 10,000 years. 

Individual Response: EPA thanks the commenters for the information on available well 

materials. EPA believes that the regulation affords owners or operators flexibility to use various 

materials and techniques to perform corrective action, provided they meet with the Director's 

approval.