Southwest Gas Storage Company

Original Volume No. 1

Effective Date: 04/01/1999, Docket: CP97-237-001, Status: Effective

First Revised Sheet No. 95 First Revised Sheet No. 95 : Superseded

Superseding: Original Sheet No. 95

RATE SCHEDULE ISS (Continued)

INTERRUPTIBLE STORAGE SERVICE

quantities of natural gas to Buyer at the Point of

Delivery. Seller and Buyer shall, by mutual agreement,

establish the date of commencement of receipt and

redelivery of gas hereunder. Receipts and redeliveries of

gas hereunder shall be at uniform hourly and daily rates of

flow as nearly as practicable.

(b) Measurement shall be both volumetric and thermal, at a

temperature of 60ø Fahrenheit and at a pressure of 14.73

psia, and on the basis of the methods prescribed and

published by the American Gas Association in conjunction

with the ANSI/API 2530 Report as now and any subsequent

amendments thereof accepted and agreed upon between the

parties if orifice meters are used, and in accordance with

generally accepted industry practices, as mutually agreed

upon, if positive or turbine meters are used.

The Btu content (MMBtu) shall be determined by taking the

arithmetic average of the heating value as recorded by

recording calorimeter or other method of determination

generally accepted in the industry. Flowing temperature

shall be determined by a recording thermometer or EGM.

pressure sufficient to enter Sellerþs facilities at such

point. Redeliveries of gas at the Point of Delivery shall

be at such pressure as exists in Sellerþs facilities. Gas

received and redelivered shall be merchantable natural gas;

shall be free of water and hydrocarbons in liquid form;

shall contain not more than 7 pounds of water vapor per

MMcf; 1.0 grain of hydrogen sulphide and 20 grains of total

sulphur per 100 cubic feet, 2% of carbon dioxide (by

volume), and 50 parts per million of oxygen; and shall not

exceed 120ø Fahrenheit in temperature. The gas shall have

a total or gross heating value of not less than nine

hundred fifty (950) Btu and not more than one thousand two

hundred (1200) Btu per cubic foot. Seller shall not be

obligated to accept gas for storage which does not meet

these quality provisions.