Los Angeles Municipal Code § 91.7105 Existing Buildings

(Readopted by Ord. No. 188,797, Eff. 12/31/25.)

Section

• 91.7101 Purpose.

• 91.7102 Definitions.

• 91.7103 General Methane Mitigation Requirements.

• 91.7104 General Methane Requirements.

• 91.7105 Existing Buildings.

91.7106 Testing, Maintenance and Service of Gas-detection and Mechanical Ventilation Systems.

91.7107 Emergency Procedures.

91.7108 Application of Methane Seepage Regulations to Locations or Areas Outside the Methane Zone and Methane Buffer Zone Boundaries.

91.7109 Additional Remedial Measures.

This division sets forth the minimum requirements of the City of Los Angeles for control of methane intrusion emanating from geologic formations. The requirements do not regulate flammable vapor that may originate in and propagate from other sources, which include, but are not limited to, ruptured hazardous material transmission lines, underground atmospheric tanks, or similar installations.

For the purpose of this division, certain words and phrases are defined as follows:

Alarm System shall mean a group of interacting elements consisting of components and circuits arranged to monitor and annunciate the status of gas concentration levels or supervisory signal-initiating devices and to initiate the appropriate response to those signals.

Buildings with Raised Floor Construction shall mean a building with the bottom of the floor system raised above grade where the clearance for each of the following items shall be at least: 12 inches for the girder, 18 inches for the floor joist and 24 inches for the structural floors.

Cable or Conduit Seal Fitting shall mean an approved fitting provided in a cable or conduit system to prevent the passage of gases, vapors, or flames through electrical cable or conduit.

Design Methane Concentration shall mean the highest concentration of methane gas found during site testing.

Design Methane Pressure shall mean the highest pressure of methane gas found during site testing.

De-watering System shall mean a permanent water removal system, consisting of perforated pipes, gravel, sump pumps and pits, designed to permanently maintain the ground water level one foot below the sub-slab vent system.

Gas Detection System shall mean one or more electrical devices that measure the methane gas concentration and communicate the information to the occupants, building management, central station or alarm company with audible or visual signals.

Gravel Blanket shall mean a layer of gravel, sand, or approved material designed to transmit gas to the vent riser without obstructing the venting system.

Impervious Membrane shall mean a continuous gas barrier made of material approved by the Department and installed beneath a building for the purpose of impeding methane migration to the interior of the building.

Mechanical Extraction System shall mean a system operated by a machine which is designed to remove methane gas from below the impervious membrane through the use of fans, blowers, or other powered devices.

Mechanical Ventilation shall mean a fan, blower or other similar group of interacting elements operated by a machine within the building, which introduce and/or remove air from an enclosed space.

Narrow Building shall mean a building that has a width less than 50 feet, a footprint of less than 50,000 square feet and having a minimum 2-foot wide landscaped area immediately adjacent to the exterior wall for at least 50 percent of the perimeter of the building.

Oil Well shall mean a deep hole or shaft sunk into the earth for the exploration of oil or gas; or which is on lands producing or reasonably presumed to contain oil or gas; or which is drilled for the purpose of injecting fluids or gas for stimulating oil recovery, re-pressurizing or pressure maintenance of oil or gas, or disposing of waste fluids from an oil or gas field.

Perforated Horizontal Pipe shall mean an approved pipe which contains a series of small holes or narrow openings placed equidistant along the length of the approved pipe, which is placed horizontally beneath the foundation of a building, for the purpose of venting accumulated methane gas and preventing the development of elevated gas pressures, or for drainage of ground water to an approved location.

PPMV shall mean Parts per Million by Volume.

Pressure Sensor (Deleted by Ord. No. 180,619, Eff. 5/12/09.)

Single Station Gas Detector shall mean a device consisting of electrical components capable of measuring methane gas concentration and initiating an alarm.

Trench Dam shall mean an approved subsurface barrier installed within a furrow or ditch adjacent to the foundation of a building, for the purpose of preventing the migration of methane gas beneath that foundation.

Unobstructed Opening shall mean a permanent clearing or gap in the walls, floors or roof-ceiling assemblies without windows, doors, skylights or other solid barriers that may restrict the flow of air.

Vent Riser shall mean an approved pipe which is placed vertically with joints and fittings connected to Perforated Horizontal Pipes to convey and discharge the gas to the atmosphere.

All new buildings and paved areas located in a Methane Zone or Methane Buffer Zone shall comply with these requirements and the Methane Mitigation Standards established by the Superintendent of Building. The Methane Mitigation Standards provide information describing the installation procedures, design parameters and test protocols for the methane gas mitigation system, which are not set forth in the provisions of this division.

Boundaries of the Methane Zones and Methane Buffer Zones are shown on the "Methane and Methane Buffer Zones Map" designated as Map number A-20960, dated September 21, 2003, which is attached to Council File No. 01-1305 or the most recent version of the described map. (Amended by Ord. No. 185,587, Eff. 7/16/18.)

Equipment and Systems. All devices, components and equipment installed in any methane detection system shall be approved by the Fire Department as set forth in Fire Prevention Bureau (F. P. B.) Requirement No. 71. (Added by Ord. No. 180,619, Eff. 5/12/09.)

Additions, alterations, repairs, changes of use or changes of occupancy to existing buildings shall comply with the methane mitigation requirements of LAMC Subsections 91.7104.1 and 91.7104.2, when required by Divisions 81 or 82 of Article 1, Chapter IX of the LAMC. (Amended by Ord. No. 184,692, Eff. 12/30/16.)

Approved methane mitigation systems in existing buildings shall be maintained in accordance with LAMC Section 91.7106. (Amended by Ord. No. 185,587, Eff. 7/16/18.)

(Amended by Ord. No. 185,587, Eff. 7/16/18.)

The installation instructions for the gas detection and mechanical ventilation systems, which are required by LAMC Table 71, shall be approved and enforced by the Fire Department. All gas detection and mechanical ventilation systems shall be maintained and serviced in proper working condition and meet all requirements of the State of California and City Electrical and Mechanical Codes.

A. Fire Department. The Fire Department shall enforce the following:

1. The maintenance and service procedures for each gas detection and mechanical ventilation systems, which are required in LAMC Table 71, shall be performed by the building owner in accordance with the manufacturers written instructions.

2. The annual and maintenance testing shall be performed as set forth by the Fire Department in accordance with the Fire Prevention Bureau (F.P.B.) Requirement No. 71 and Fire Chief's Regulation 4, Section 4J.

3. The testing of the gas detection and mechanical ventilation systems shall be performed by a person with a valid Certificate of Fitness for Gas Detection Systems as set forth in LAMC Section 57.117.

B. Notification Placard. A permanent notification placard shall be posted and maintained at the front entrance of a building that is constructed with Impervious Membrane, except in residential buildings. The placard shall indicate the presence of the Impervious Membrane.

With the exception of single-family dwellings, all buildings required by this division to have a gas detection system or sub-slab vent system shall, subject to Fire Department approval, have established emergency procedures that include, but are not limited to, the following: (Amended by Ord. No. 180,619, Eff. 5/12/09.)

A. Assignment of a responsible person as safety director to work with the Fire Department in the establishment, implementation and maintenance of an emergency plan.

B. Conspicuous posting of the Fire Department’s telephone number in areas designated by the Fire Department.

C. Conspicuous posting of emergency plan procedures approved by the Fire Department.

(Amended by Ord. No. 185,587, Eff. 7/16/18.)

Upon a determination by the Department that a hazard may exist from methane intrusion at a geographical location or in an area outside the boundaries established in LAMC Section 91.7103, the Department and the Fire Department may enforce any or all of the requirements of Division 71, Article 1, Chapter IX of the LAMC as required to preclude potential fire or explosion from methane concentration.