Mainline 100 Pipeline Maintenance, Effective October 6 – October 19, 2026

SEV 4/5Maintenance0.345 Bcf/d14 days

Summary

CGT has issued a critical maintenance notice for Mainline 100, effective October 6-19, 2026 (14 days). Backhaul capacity through ClemSEG will be reduced to 1,950,000-2,050,000 Dth/day against a design capacity of 2,344,656 Dth/day, a reduction of approximately 295,000-395,000 Dth/day (~0.295-0.395 Bcf/d). Separately, the Tetco/Adair Co., Ky receipt interconnect (MS 3194) will be reduced to 0-50,000 Dth/day against a design of 207,517 Dth/day, representing a near-complete curtailment of that interconnect. CGT explicitly warns of potential curtailments to Interruptible, Secondary Firm, and Primary Firm services.

Trading note

CGT Mainline 100 maintenance removes up to ~0.345 Bcf/d of backhaul capacity through ClemSEG (currently running at 83.9% utilization, 1.97 Bcf/d scheduled of 2.34 Bcf/d operating capacity per timely cycle 2026-09-28) and effectively zeros the Tetco/Adair Ky receipt (3194, currently 96.4% utilized at 0.200 Bcf/d), with primary firm curtailments explicitly at risk -- expect bullish pressure on Transco Zone 4 and CGT mainline basis vs Henry Hub; Columbia Gulf mainline basis most recently -0.475 vs HH on 2026-09-25, with a 5-day average of -0.347, and this constraint should narrow that discount.

Reroute potential

Moderate: TETCO and Trunkline (TGC) serve overlapping Gulf Coast northbound corridors, but with the Tetco/Adair Ky receipt effectively curtailed, TETCO's own receipt capacity from CGT at that interconnect is simultaneously impacted, limiting the typical reroute option at that junction. Partial reroute via ANR and CGT alternate paths may absorb some volume but is unlikely to fully offset primary firm curtailments.

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View original notice text (as posted by Columbia Gulf Transmission (CGT))

TSP Name Columbia Gulf Transmission, LLC
TSP 007854581
Notice Type Description: Maintenance

Notice Stat Desc: Initiate

Prior Notice: 

Critical: Y

Reqrd Rsp Desc: No Response Required
Post

Notice Effective

Notice End



Response
Post Date: 09/28/26

09/28/26

10/28/26
Subject: Subject: Mainline 100 Pipeline Maintenance, Effective October 6 – October 19, 2026
Author: Author: Jonah Skiles
Notice Text
Columbia Gulf Transmission, LLC (CGT) notifies customers of upcoming pipeline maintenance on Mainline 100 beginning on Tuesday, October 6, 2026, through Monday, October 19, 2026. As a result, the backhaul capacity through ClemSEG will be reduced to a level between 1,950,000 and 2,050,000 Dth effective Timely Cycle for Gas Day Tuesday, October 6, 2026.

Additionally, the receipt capacity at the Texas Eastern Adair interconnect (MS 3194) will be reduced to a level between 0 and 50,000 Dth effective Timely Cycle for Gas Day Tuesday, October 6, 2026. CGT encourages customers to monitor the Daily Capacity Posting for the specific capacity settings each day of the maintenance.

CGT anticipates this restriction may result in curtailments to Interruptible, Secondary Firm, and Primary Firm services. Please see the details provided below for more information.

ClemSEG

·       Estimated Capacity Setting: 1,950,000 – 2,050,000 Dth

·       Design Capacity: 2,344,656 Dth

·       Posted Percentage: 83-87%

3194 – Tetco/Adair Co., Ky Receipt

·       Estimated Receipt Capacity Setting: 0 – 50,000 Dth (Primary Only)

·       Design Capacity: 207,517 Dth

·       Posted Percentage: 0-24%

Due to the potential impact to firm service, CGT encourages customers to monitor the scheduled volumes on the Operationally Available Capacity screen on Informational Postings, as nominations can fluctuate based on market conditions. 

Reservation Charge Credits (RCCs) will be determined per the process set forth in the General Terms and Conditions, Section 40 of CGT’s FERC Gas Tariff (Tariff). By means of this notice, CGT is establishing the 7-day Average Usage Quantity to be the period of August 20-26, 2026, pursuant to the provisions in the Tariff. 

Please contact your Customer Services Representative with any questions.

ID: CGT-26276039 | Rev. 1 | Posted: 2026-09-28 19:13 | Direction: Bullish All Columbia Gulf Transmission (CGT) notices · page generated 2026-09-28 19:15 UTC