UNITED STATES DEPARTMENT OF THE INTERIOR
MINERALS MANAGEMENT SERVICE
GULF OF MEXICO OCS REGION
NTL No. 98-16
August 10, 1998
NOTICE TO LESSEES AND OPERATORS OF FEDERAL OIL, GAS, AND SULPHUR LEASES
ON THE OUTER
CONTINENTAL SHELF,
GULF OF MEXICO OCS REGION
Hydrogen Sulfide (H2S) Requirements
This Notice To Lessees and Operators (NTL) supersedes NTL 97-09 and updates cited regulatory authorities and includes a statement regarding the Paperwork Reduction Act of 1995.
This notice clarifies and offers guidance and information regarding the interpretation of certain provisions contained within the revised Minerals Management Service (MMS) H2S Requirements for Operations on the Outer Continental Shelf (OCS), Regulation 30 CFR 250.417. In addition, this notice identifies general areas of concern that the operator must satisfy in submitting an H2S Contingency Plan to the District Supervisor for approval.
Implementation of the Regulation The MMS published the regulation in the Federal Register, Volume 62, No. 17, on Monday, January 27, 1997, with an effective date of March 28, 1997.
In the event you detect H2S, you must furnish an H2S Contingency Plan within 30 days following detection, such plan to be directed specifically toward facilities processing any product containing a concentration of H2S that could result in an atmospheric concentration of 20 ppm if released.
If you need more time to purchase, modify, or install equipment, you need to submit a request to extend the time for implementation of the proposed plan to the District Supervisor within 30 days after the effective date of this NTL, and provide documentation supporting your request for a time extension for compliance with this regulation.
The following guidance relating to the implementation of certain provisions of this regulation will apply in the Gulf of Mexico OCS Region (GOMR):
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 a more effective or a more efficient placement of sensors. The GOMR will accept alternate placement of 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 percent 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 percent (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.
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.
The GOMR will limit approval of any self-contained, pressure-demand-type respirators with hoseline capability with breathing time less than 15 minutes 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 the following in your request for approval:
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.
Approving of Alternative Measures for Protection Against Sulfur Dioxide (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 (authority delegated from the Regional Supervisor 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.
Requirements for Classifying an Area for the Presence of H2S, 30 CFR 250.417(c) The GOMR will continue to require a request for the classification of an area for the presence of H2S to be submitted in the Plan of Exploration and Development Operations Coordination Document and not in the Application for Permit to Drill.
Requirements for Flaring and Venting of Gas Containing H2S
Regulation 30 CFR 250.1105(f) details the requirements for flaring, venting, and reporting of flared gas containing H2S.
In addition, District Supervisors may require:
1. Well Tests, Extended Flaring, or Burning of Acid Gas
a. Dispersion models of the toxic effects on downwind constituents for all well tests whose product contains H2S concentrations exceeding 0.05 percent by volume (500 ppm). These models are to include contours of H2S concentrations and SO2 concentrations as determined by the District Supervisor. In addition, these models must depict the relationship of these concentrations to known structures, shipping lanes, and proximity to shore.
b. The estimated burner efficiency ratings for the flare system. Estimated maximum flow rate. H2S concentration at the maximum rate of the well stream, H2S concentration after burn, and SO2 concentration after burn.
2. Nearby Manned Facilities
You must address, as part of the emitting facility’s H2S Contingency Plan, all manned facilities that a major release of product containing H2S or SO2 may affect and provide for the same measure of personal protection as the emitting facility for the appropriate concentrations. This protection includes H2S and SO2 detectors connected to audible and visual alarms, breathing equipment, training, and evacuation plan. A dispersion model depicting the worst case release shall validate whether a manned facility will be affected.
Requirements for Approval of an H2S Contingency Plan
An H2S Contingency Plan must contain the information required by 30 CFR 250.417(f).
District Supervisors in the GOMR prefer that:
1. The plan be segmented as follows:
a. General information relative and common to all types of operations.
b. Drilling Operations
c. Workover Operations
d. Production Operations
e. Pipelines
f. Simultaneous Operations
2. You must report changes to a plan to the appropriate district office immediately.
3. Any detection of H2S gas at concentrations of 20 ppm or greater or SO2 gas at concentrations at 5 ppm or greater on manned or unmanned platforms necessitates that all known H2S sources (wells) at the facility be shut in. District Supervisor approval is required to resume operations.
Signs, Visual Alert Devices, and Audible Warning Devices, 30 CFR 250.417(I)
A visual device must be visible from the helideck and all boat landings. The audible warning alert must be recognizable at all boat landings and the helideck.
Paperwork Reduction Act Statement
The collections of information referred to in this NTL are contained in 30 CFR Part 250, Subparts D and K. The Office of Management and Budget (OMB) has approved the information collection requirements in these Regulations. The applicable OMB Control Numbers are 1010-0053 for Subpart D and 1010-0041 for Subpart K. This NTL does not impose additional information collection requirements subject to the Paperwork Reduction Act of 1995.
Chris Oynes
Regional Director
Return to Notices to Lessees and Operators