ASSUMPTION AGREEMENT

     This CONTRIBUTION, CONVEYANCE AND ASSUMPTION AGREEMENT (this “ Agreement ”), dated as of June 29, 2011, is entered into by and among El Paso Pipeline Partners, L.P., a Delaware limited partnership (the “ Partnership ”), El Paso Pipeline Partners Operating Company, L.L.C., a Delaware limited liability company and direct wholly-owned subsidiary of the Partnership (the “ Operating Company ”),  El Paso SNG Holding Company, L.L.C., a Delaware limited liability company and direct wholly-owned subsidiary of El Paso Corporation (“ EP SNG ”), EPPP SNG GP Holdings, L.L.C., a Delaware limited liability company and an indirect wholly-owned subsidiary of the Partnership (“ EPPP SNG ”), Southern Natural Gas Company, a Delaware general partnership (“ SNG ”), El Paso Noric Investments III, L.L.C., a Delaware limited liability company and indirect wholly-owned subsidiary of El Paso Corporation (“ EP Noric ”), Colorado Interstate Gas Company, a Delaware general partnership, (“ CIG” ), EPPP CIG GP Holdings, L.L.C., a Delaware limited liability company and an indirect wholly-owned subsidiary of the Partnership (“ EPPP CIG ”), El Paso CNG Company, L.L.C., a Delaware limited liability company and direct wholly-owned subsidiary of El Paso Corporation (“ EP CNG”) and El Paso Corporation, a Delaware corporation (“ El Paso ”).  The parties to this Agreement are collectively referred to herein as the “ Parties .”  El Paso, EP Noric, EP CNG and EP SNG are referred to herein collectively as the “ Contributing Parties .” Capitalized terms used herein shall have the meanings assigned to such terms in Section 1.1.

     WHEREAS, the Contributing Parties desire to transfer to the Partnership a 15% general partner interest in SNG (the “ SNG Subject Interest ”) and a 28% general partner interest in CIG (the “ CIG Subject Interest” and, together with the SNG Subject Interest, the “ Subject Interest ”)   pursuant to the terms of the Contribution Agreement (as defined below) and this Agreement; and

     WHEREAS, EP SNG owns a 15% general partner interest in SNG and EPPP SNG owns an 85% general partner interest in SNG; and

     WHEREAS,  EP Noric owns a 42% general partner interest in CIG and EPPP CIG owns a 58% general partner interest in CIG; and

     WHEREAS, after giving effect to the completion of the contribution of the Subject Interest referred to above pursuant to the terms of this Agreement and the Contribution Agreement (as defined below), EPPP SNG will own an 85% general partner interest in SNG, EP Noric will own a 14% general partner interest in CIG and EPPP CIG will own a 15% general partner interest in SNG and an 86% general partner interest in CIG; and

     WHEREAS, in order to accomplish the objectives and purposes in the preceding recitals, and to effect the intent of the Parties in connection with the consummation of the transactions contemplated hereby, the Partnership, the Operating Company, EP SNG, EPPP SNG, SNG, EP Noric, EPPP CIG, CIG and El Paso entered into that certain Contribution Agreement (the “ Contribution Agreement ”), dated June 29, 2011, pursuant to which the Partnership agreed to acquire the Subject Interest from the Contributing Parties for aggregate consideration of $745 million (as may be adjusted pursuant to the Contribution Agreement) (the “ Consideration ”).

     WHEREAS, concurrently with the consummation of the transactions contemplated hereby (the “ Closing ”), each of the following shall occur:

1.   EP SNG will transfer the SNG Subject Interest to El Paso.

2.   EP Noric will transfer the CIG Subject Interest to EP CNG.

3.   EP CNG will transfer the CIG Subject Interest to El Paso.

4.   El Paso will transfer the Subject Interest to the Operating Company.

5.   The Operating Company will contribute the Subject Interest to EPPP CIG.

6.   The general partnership agreements of CIG and SNG will be amended to the extent necessary to reflect the matters and transactions mentioned in this Agreement.

     NOW, THEREFORE, in consideration of their mutual undertakings and agreements hereunder, the Parties undertake and agree as follows:

     Section 1.1  The following capitalized terms shall have the mean i ngs given below.

(a)   “ Agreement ” has the meaning assigned to such term in the first paragraph of this Agreement.

(b)   “CIG” has the meaning assigned to such term in the first paragraph of this Agreement.

(c)   “ CIG Subject Interest ” has the meaning assigned to such term in the recitals.

(d)   “ Consideration ” has the meaning assigned to such term in the recitals.

(e)   “ Closing ” has the meaning assigned to such term in the recitals.

(f)   “ Closing Date ” has the meaning assigned to such term in the Contribution Agreement.

(g)   “ Closing Time ” shall mean 9:00 a.m. Houston, Texas time on the Closing Date.

(h)    “ Contributing Parties ” has the meaning assigned to such term in the first paragraph of this Agreement.

(i)   “ Contribution Agreement ” has the meaning assigned to such term in the recitals.

(j)    “ El Paso ” has the meaning assigned to such term in the first paragraph of this Agreement.

(k)    “ EP CNG ” has the meaning assigned to such term in the first paragraph of this Agreement.

(l)   “ EP Noric ” has the meaning assigned to such term in the first paragraph of this Agreement.

(m)   “ EP SNG ” has the meaning assigned to such term in the first paragraph of this Agreement.

(n)   “EPPP CIG ” has the meaning assigned to such term in the first paragraph of this Agreement.

(o)    “ EPPP SNG ”