NOTICE TO LESSEES AND OPERATORS OF
 FEDERAL OIL AND GAS LEASES
         IN THE PACIFIC OUTER CONTINENTAL SHELF REGION

Hydrogen Sulfide (H₂S) Requirements 

This notice supersedes NTL 98-09.

We have received several questions on the interpretation of certain provisions of our regulation on H₂S requirements for operations in the OCS (30 CFR 250.417).  The main concerns involve sensor calibration, sensor location and respirator with 15-minute air supply.  The following guidance applies in the Pacific OCS Region for implementing certain provisions of this regulation.

Sensor Location for Production Operations -- 30 CFR 250.417(j)(5):

The specifications in 250.417(j)(5)(i), (iii), and (iv) require one sensor per 400 square feet of deck area and a sensor within 10 feet of equipment, where atmospheric concentrations of H₂S could reach 20 ppm.

You may conduct a design analysis including dispersion modeling to determine more effective or more efficient placement of sensors.  We will accept alternate placement of the sensors if the analysis shows that the alternate placement provides levels of safety equal or superior to placement based on the specific requirements in the regulation.

Calibration of H₂S Sensors -- 30 CFR 250.417(j)(6)(ii):

This section specifies that a sensor tolerance of 2 ppm or 10% during a functional test is acceptable.

Alternatively, you may use sensors with a higher test tolerance, provided you adjust the activation point so that the sensor alarm will activate at no higher than 22 ppm H₂S atmospheric concentrations. For example, if the tolerance of the instrument is 25% (5 ppm for a reading of 20 ppm), then you may set the alarm to activate at 17 ppm. With the possible 5 ppm error, the alarm could activate between 12 and 22 ppm. The level of safety for the worst case of 22 ppm would then be the same as the level of safety specified in the rule.

Approving Alternative Measures for Protection Against SO₂ -- 30 CFR 250 417(j)(12):

Section 250.417(j)(11) lists actions that you must take to protect against SO₂ if you burn gas containing H₂S.

Section 250.417(j)(12) allows you to follow alternative measures instead of those in paragraph (j)(11) of this section, if you propose and the District Supervisor (delegated from the Regional Supervisor/Program Office Chief level) approves the alternative measures.

Additionally you must not use gas containing more than 50 ppm H₂S for fuel gas without the prior approval of the District Supervisor.

Respirator Breathing Time -- 30 CFR 250.417(j)(13):

This section requires that you provide all personnel, including contractors and visitors on the facility, with immediate access to self-contained pressure-demand-type respirators with hoseline capability and breathing time of at least 15 minutes.

Our approval of any self-contained-pressure-demand-type respirators with hoseline capability with breathing time less than 15 minutes will be limited to cases where you have shown that the overall protection will be equivalent to that provided by the requirements in this regulation. You must address in your request for approval the following:

1.   The number of excess breathing devices that are on the platform (i.e., number of devices in excess of the number of personnel). 

2.   Quick access to stationary breathing supply. 

3.   Anticipated egress time for all personnel who might end up with less than a 15-minute supply. 

4.   Effective duration of respirator air supply in a panic situation.

Requirement for Flaring and Venting of Gas Containing H₂S:

The requirements for flaring, venting and reporting of flared gas containing H₂S are now covered in 30 CFR 250.1105(f). Please refer to NTL No. 2003-P04, regarding flaring and gas venting, for additional information.

Paperwork Reduction Act of 1995 Statement:  The collection of information referred to in this notice provides clarification, description, or interpretation of requirements in 30 CFR 250, subpart D.  The Office of Management and Budget (OMB) approved the information collection requirement in these regulations and assigned OMB Control Number 1010-0141.  This notice does not impose additional information collection requirements subject to the Paperwork Reduction Act of 1995.

If you have any questions or need clarification regarding the NTL, please contact the Office of District Operations at (805) 389-7777.