Exhibit 10.4

 AM NDING AGREEMENT This Amending Agreement is made as of the 26111 day of June 201B. BETWEEN: TRANSCANADA PIPELINES L MITED a Canadlon corporation (''T•·sntsCanada'') "and .. PORTLAND NATURAL GAS TRANSMISSION SYSTEM a Maine General Pal'tnership (''SWppe1''1)-WHEREAS TmnsCanadn and Sh.ippet·are jJattiteo a Financial Assmances Agreement dated Novembe·30,2011(the "Agt·ccm utu); nd WHEREAS Tl'f\llsCanada and S.hipper wish to nm md the Agreement by inct·easing the Phnse III quantity by 10,551 GJ/d fl'Om 182,751 GJ/d to 193,302 OJ/d; NOW THEREFORE TrausCanada and Shipper agree as follow : ARTICLiif 1 INCORPORATION, DEFINITIONS AND EFFECTIVE DATE 1.1TWs Amending A-greement md the pt'ovh;ious hereof are supplemental to the Agreement, 1U1d at'e to· form pa\t of and have the same effect ns though h1colpo1·ated in t!te Agrement. 1,2 Unle:Js ot\terwlse defined it1 this Amending Agree.m t}t, all cap1tallzed terms contained in this Amending Agreement which ardefined ht the Agreement shall fol' aU pu poses hereof have thmeaning given to thm Jn the Agreetneut "Unless the context otherwi11e specifks or i'equires. 1.3This Amending Agl.'eement 1s effec vc as of the dae ft ·st vy1·ittet'nbove. ARTICLE2 AMENDMENTSTOTHEAGREEMENT 2.1The Agreement is amended as follows: (a)by deleting the second and thil'd l'ecltut's in te! tirety nnd replacing it with the following:

 WHEREAS, each Contract, upon execution, will be tor gas h'nnsporlalion aud related services where TransCaunda determined it must construct fi1cililles in order to provide such service (the "Expansion Capacity Service,) and would provide for TmnsGnnnda to trattsport for the account of Shipper up to 1a4,862 GJ/d of nnl1trl gas from the Union Dawn Receipt Point and 8,440 GJ/9 of nal1ll'al gas from the Union Pmkway Delt Receipt Polnl Lo, ln both cases, the Enst Hereford, Quebec Delivery Point (into the PNGTS system); and WHEREAS, the Expansi.on Capacity Sm·vice is auticipnted to be on a three phased basis conunenciug (for enoh J>huse, its 41In Scrvlce Df\te")s follows (st1ch tlu·ee phases are sometimes refe1'red to individually as n "Phase,): • CQmtnencing on he 1st ofNovembet• 2018 or as :;oon as p.ossible thereafter, 39,663 GJ/dny from the Union Dawn Receipt Point and 2,651 GJ/day frol)1, the Pal'lcway Receipt Polnt for an nggt·egate of 42,314 GJ/day, for a term of22 yeal'll ("Phase I''); • Qollllllel}oiug 01) the lt ofNovember 2019 or as soon ns possible thcrenftcr, 159,960 GJ/day : o;.fl'Om the Union Dawn Recelpt Point and 7,481 GJ/clny from the Union Parkway Belt Receipt Point fo1' an aggreg&te of 167,441 GJ/day, for a term of21 yeat·s ("Phase II"); and ,. CotnmenoU1g on the 1st of November 2020 01' as soon as possible therea{te1', l84,862 GJ/d y ft•om thUnlon Dawn Receipt Point and 8,440 GJ/dny fi•om the UnionPal'lcway Belt Receipt Point for nnggregate of 193,302 GJ/dny,fort\ term of20 years (transportation.services comm.encing at this time shall be referred to as "Phase Ill" of the Expausioh Capacity Service)and ARTICLE3 MlSCELLANEOUS 3.1This Amending Agreement supercedes all negotiations, discussions and undertakings between the parties in relation to the subject mattehtereof.· 3.2The Agreetll.ertt. shall t'ema!n in full force and eftect as amended by this Amending Agreement and is hereby ratifit!d a,nd confirmed ·us amended. 3.3This A n ndh)g Agreement may be executed by the parties. In separate co !nterpat't$, ctnoh of which when so executed and delivered shall be an odginal, but all such counteiparts shall together o·onstltute one and the s me instnnnellt, A facslrnile or o.ther eh:ctron.ic copy qf thiA,tneudlng Agl'eemcn.t contftining the slgn tme of a party will be deemed to be an ol'lginnUy signed document. [Execulion·pag follows]

 IN WITNESS WHEREOF the parties to this Amending Agreement have caused it to be executed by theh·duly authorized officel's lis of !he day mtd yeat·first written above. l)ORTLAND NATUUAL GAS TRANSMISSION SYSTEM, BY ITS OPERATOR, PNGTS Ol,ERATING CO.,LLC TRANSCANADA PIPELINES LIMITED By:4lhtL . Z'E?By: Nome:Nathanlei Qrown Title: Chief P. namcta(Officer By: Name: Title:Don Bell Director,Colll1l1Cl'clal East Contract _Content Mannger, Customer Service Content Review LegalReview