Letter agreement, dated August 14, 2020, between NWN Gas Storage, LLC and SENSA Holdings LLC, amending the Purchase and Sale Agreement, dated June 20, 2018, as amended

August 14, 2020                BY EMAIL AND OVERNIGHT COURIER

Gentlemen:

To follow up on our previous conversations regarding extending the deadline after which either NW Natural Gas Storage, LLC (Seller) or SENSA Holdings LLC (Buyer) can terminate the Purchase and Sale Agreement between Seller and Buyer, dated as of June 20, 2018, as amended (Purchase Agreement), we are submitting this letter to you and requesting that you acknowledge your agreement with the matters set forth herein by signing it in the space provided below. Please note that all capitalized terms used and not otherwise defined herein shall have the meanings given to such terms in the Purchase Agreement.

Pursuant to Section 11.4 of the Purchase Agreement, Seller and Buyer agree that Section 8.1(b)(i) of the Purchase Agreement is hereby amended to read as follows:

“(i) automatically until September 30, 2020 if the CPUC has not issued the CPUC Order as of the close of business on the first anniversary of the date of this Agreement and/or.”

Seller and the Company may:

(a)make any capital expenditure or commitment to make a capital expenditure in accordance with planned 2020 capital expenditures as set forth in the “2020 Capital Budget” (as defined in the letter agreement, dated June 26, 2020, between the parties), and

(b)in the ordinary course of business, consistent with past practice and the terms of the Purchase Agreement (as amended by this letter), enter into or amend any storage Contract, including without limitation any Firm Storage Contract, Interruptible Contract or Park and Loan Contract, but only if such Contract, as entered into or amended, expires on or before March 31, 2021.

This paragraph constitutes the prior written approval of Buyer to the matters set forth in clauses (a) and (b) in accordance with Section 6.1 of the Purchase Agreement.

Pursuant to Section 11.4 of the Purchase Agreement, Seller and Buyer agree that the definition of “Current Assets” in Section 1. 1 of the Purchase Agreement is hereby amended to read as follows:

““Current Assets” as of a specified date means the sum of (a) the current assets of the Company as reflected on a balance sheet of the Company as of that date as determined under GAAP and, subject to the following exclusions, applied in a manner consistent with

preparation of the Financial Statements, but excluding, however, (i) cash and cash equivalents and (ii) intercompany accounts between the Company, on the one hand, and Seller or its Affiliates, on the other, plus (b) the amount of cash, if any, contributed by Seller or an Affiliate of Seller to the Company to serve as collateral for the “GRS LC” (as defined in the Fifth Amendment to Purchase and Sale Agreement, dated April 29, 2020, between the parties), plus accrued interest on such amount of contributed cash from the date the GRS LC is issued through the Closing Date based on an interest rate of 3% per annum, plus (c) the aggregate of (i) all capital expenditures made by the Company from June 27, 2020 through the Closing Date relating to any and all of the projects set forth in the “2020 Capital Budget” (as defined in the letter agreement, dated June 26, 2020, between the parties) but not to exceed the amounts set forth on Exhibit A to the letter agreement, dated August 14, 2020, between the parties, for each period identified on such Exhibit A and (ii) all expenditures made by the Company to respond to any catastrophe or other emergency situation from June 27, 2020 through the Closing Date and to restore safe operations of the Business (but not resulting from the gross negligence or willful misconduct of Seller, the Company, or their respective Affiliates, or any of their respective Representatives), including to prevent, mitigate or remedy the endangerment or the health or safety of any person(s) or of the environment.”

All references in the Purchase Agreement to “Agreement,” “herein,” “hereof,” or terms of like import referring to the Purchase Agreement or any portion thereof are hereby amended to refer to the Purchase Agreement as amended by this letter. Except as and to the extent expressly modified as set forth in this letter, the Purchase Agreement shall remain in full force and effect in all respects. Each of the provisions in Article XI of the Purchase Agreement is hereby incorporated by reference herein, mutatis mutandis.

We look forward to working together to complete the transaction as soon as possible.

Regards,

/s/ Justin Palfreyman

Justin Palfreyman

Vice President, Strategy & Business Development

NW Natural Gas Storage, LLC

Buyer acknowledges and agrees to the matters set forth in this letter as of the date first set forth above.