Long Beach Municipal Code Ch. 18.79 Methane Gas Mitigation

Footnotes:

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Editor's note— ORD-22-0033 § 1(Exh. A), adopted Nov. 15, 2022, Ch. 18.79 in its entirety to read as herein set out. Former Ch. 18.79, §§ 18.79.010—18.79.120, pertained to similar subject matter, and derived from ORD-21-0019 § 1, 2021.

This chapter sets forth the minimum requirements of the City of Long Beach for control of methane gas 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.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

The provisions of this chapter shall govern methane gas mitigation systems for all buildings and structures. Additional requirements shall apply as follows:

1. Methane gas mitigation system submittal documents shall be required for any project with a methane gas mitigation system in accordance with Subsection 18.05.030.A Item 8.

2. Methane gas mitigation inspection and plans examination fees shall be required for any project with a methane gas mitigation system in accordance Sections 18.06.010 and 18.06.020.

3. Methane gas mitigation inspections shall be required for any project with a methane gas mitigation system in accordance with Section 18.07.050. A preconstruction meeting shall be scheduled with the Building Official or a duly designated representative prior to installation of the methane gas mitigation system

4. Methane gas mitigation measures shall be required for any subgrade electrical work in compliance with the requirements of Chapter 5 of the California Electrical Code occurring in all areas identified in Section 18.79.040. Exemptions noted in Section 18.79.050 shall not apply to subgrade electrical work, except where methane soil gas testing indicates that methane gas concentrations and pressures on the project site are less than those required for a Site Design Level I classification in accordance with Section 18.79.060.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-25-0015 § 1, 2025; ORD-22-0033 § 1(Exh. A), 2022)

The following terms shall have the following meanings, unless otherwise clearly apparent from the context:

"Combustible soil gas" means flammable gas within soil pores.

"Development Projects" means newly constructed buildings or structures, additions to existing buildings or structures, or alterations of fifty (50) percent or greater to the existing foundations, slabs-on-grade, or raised floors of existing buildings or structures.

"Flammable Gas" means a gaseous substance capable of sustaining combustion or explosion, as defined in the California Fire Code as adopted in Chapter 18.48.

"Gas Membrane Barrier" means a manufactured membrane barrier designed to prevent the transmission of methane with a minimum dry thickness of fifteen (15) mils and a gas transmission rate (GTR) of less than forty (40) milliliters per square meter day (ml/m 2 -D), when tested in accordance with the American Society for Testing and Materials D1434 standard.

"Methane Gas" means the hydrocarbon substance commonly known as "natural gas," chemical formula CH4. For the purpose of this definition, natural gas from the distribution system of a utility company is exempt and excluded from the scope of this Chapter.

"Methane Gas Detection and Alarm System" means one or more electrical devices capable of continuous monitoring for the presence of methane gas in accordance with Section 18.79.070. Alarm systems shall consist of audible and visual alarms capable of alerting occupants that a hazardous atmosphere exists.

"Methane Gas Mitigation System" means a collection of building systems designed to mitigate the accumulation of methane gas to less than hazardous levels within a structure. This includes a designed collection system of piping components located beneath a structure to vent combustible soil gas to the atmosphere; heating, ventilation, and air conditioning (HVAC) systems to introduce outdoor air into a structure to ventilate accumulated methane; and sensors and alarms to detect concentrations of methane gas, activate HVAC and/or active methane mitigation, and alert occupants to the presence of methane gas.

1. Active Methane Gas Mitigation System: The complete designed piping system originating below a building or structure and terminating above the building or structure with a motorized evacuation device to exhaust accumulated gases;

2. Passive Methane Gas Mitigation System: A non-powered piping system originating below a building and terminating outside of the building using natural air flow for venting accumulated gases.

"Qualified Professional" means a California Registered Professional Civil Engineer, Petroleum Engineer, or Geologist with experience in the design and construction of methane gas mitigation systems.

"Site Design Level" means a designated level assigned to a project site based on the concentration and pressure of methane gas detected during shallow and soil gas probe testing or as indicated in Section 18.79.060.

"Soil Gas Investigation" means a scientific investigation performed in accordance with Section 18.79.060 conducted under the direction of a Qualified Professional for the purpose of determining the locations and concentrations of combustible soil gas.

"Subslab Vent Piping" means polyvinyl chloride (PVC), high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), or strip composite perforated piping, or equivalent, with a minimum diameter of three (3) inches.

"Vertical Vent Risers" means cast-iron or galvanized steel piping with a minimum diameter of three (3) inches connecting subslab piping to the atmosphere.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

The methane gas mitigation requirements of this chapter shall be required for all development projects, unless exempted by Section 18.79.050, located in the following areas:

A. All areas overlying petroleum-bearing formations and within the limits of a petroleum reservoir's boundary, as mapped by the State Geological Energy Management Division (CALGEM, or any successor agency). Properties or parcels which partially fall into the areas described herein are fully subject to the methane gas mitigation measures required by this Chapter, for the entire property.

B. All areas three hundred (300) feet or less from any active oil or gas well, or one hundred (100) feet or less from any idle and/or abandoned oil or gas well.

C. All areas one thousand (1,000) feet or less from the refuse footprint of any existing or new landfill or disposal site.

D. Where the building official determines a significant hazard exists from methane gas intrusion at any location within the City, the Building Official is authorized to enforce the requirements of Chapter 18.79 as required to prevent a potential fire or explosion due to methane gas concentrations.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

The following development projects are exempt from the provisions of this chapter:

1. Buildings or structures with permanent natural ventilation, such as but not limited to, open parking structures, carports, patio covers or similar open structures.

2. Buildings or structures with raised foundations providing adequate underfloor ventilations.

3. Alterations to existing buildings or structures where less than fifty (50) percent of the existing foundations and slabs-on-grade are replaced.

4. Newly constructed buildings or structures accessory to an existing one- or two-family dwelling that are less than fifty (50) percent of the area of the existing one- or two-family dwelling.

5. Addition to existing buildings or structures that are less than fifty (50) percent of the floor area of the existing building or structure.

6. Any development project where methane soil gas testing indicates that methane gas concentrations and pressures on the project site are less than those required for a Site Design Level I classification in accordance with Section 18.79.060.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

A. Methane soil gas testing shall be required for all development projects located within any area as indicated in Section 18.79.040. Testing shall be in accordance with the policies and criteria established by the Building Official.

Exceptions. Methane soil gas testing is not required for any of the following:

1. One- and two-family dwellings that comply with the Site Design Level I methane gas mitigation system requirements.

2. Any development project that complies with the Site Design Level III methane gas mitigation system requirements.

3. Any development project that complies with Chapter 18.78 Construction in the Vicinity of Abandoned Oil Wells and Site Design Level III methane gas mitigation system requirements.

B. Methane soil gas investigation shall classify the development project into one of the following Site Design Levels:

Level I: Concentrations of methane soil gas less than fifty-thousand (50,000) ppmv and greater than one thousand (1,000) parts per million by volume (ppmv), and measured pressure less than two (2) inches of water column (WC).

Level II: Concentrations of methane gas up to fifty thousand (50,000) ppmv, and measured pressure greater than two (2) inches of water column (WC), or concentrations of methane gas between fifty thousand (50,000) ppmv and three hundred thousand (300,000) ppmv, at all pressures.

Level III: Concentrations of methane gas greater than three hundred thousand (300,000) ppmv.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

The development project shall provide a methane gas mitigation system with the required mitigation features indicated in Table 1 of this section.

TABLE 1 METHANE GAS MITIGATION SYSTEM DESIGN REQUIREMENTS

a. Methane gas mitigation features, as required in this Table, shall be designed and detailed in accordance with the policies and criteria established by the Building Official.

b. Site Design Level shall be determined by a methane soil gas investigation in accordance with Section 18.79.060.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

An operation and maintenance plan shall be required for development projects with methane mitigation features provided for Site Design Levels II or III. The plan shall be prepared by a Qualified Professional.

Specification for the repair of the methane gas mitigation systems shall be provided to the property owner or authorized agent of the property owner for development projects with mitigation features provided for Site Design Level I.

A. The operation and maintenance plan shall contain the following information:

1. An emergency response procedure including, but not limited to, an outlined procedure for emergency response to methane gas intrusion, contact information for the Fire Department and other individuals critical during emergency response, and requirements for conspicuous posting of emergency contact information and emergency response procedures.

2. The locations of equipment and components of the methane gas mitigation system, including, but not limited to, the control panel, methane gas detection and alarm system components and any other related equipment or components.

3. Specification for the repair of the methane gas mitigation system.

4. Specification of the required frequency of methane gas detection and alarm system testing. The frequency of testing shall not exceed twelve (12) months.

B. The property owner or authorized agent of the property owner shall be provided with detailed operation and maintenance instructions for the methane gas mitigation system.

C. Testing records shall be maintained by the property owner for a period determined by the Building Official. Such records shall be made available to the Building Official upon request.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

After completion of testing of the methane gas mitigation system and prior to final inspection, a final testing report and project certification of the methane gas mitigation system, signed by the Qualified Professional, shall be provided to the Building Official. The project certification shall be provided upon a form prescribed by the Building Official, including a written statement from the Qualified Professional indicating the structure is free from methane gas and can be safely occupied.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

Prior to the final inspection, the property owner shall file with the Building Official on a form approved by the City Attorney an agreement binding such property owner, heirs and assignees, to maintain and operate the methane gas mitigation system in accordance with the requirements specified on the construction documents approved by the City. Such agreement shall be recorded in the County Recorder's Office.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

ASTM D1434-82(2015)E1 - Standard Test Method for Determining Gas Permeability Characteristics of Plastic Film and Sheeting

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)

The City Manager, or designee, is authorized and directed to promptly adopt administrative rules, which may be in the form of information bulletins, supplemental to the provisions of this chapter as necessary or appropriate to implement this chapter. The provisions of this chapter and the rules adopted by the City Manager, or designee, shall be provided to property owners, developers, potential developers, and other interested members of the public to the widest extent practical. No person shall fail to comply with any such information bulletin, rule or regulation.

(ORD-25-0019 § 1(Exh. A), 2025; ORD-22-0033 § 1(Exh. A), 2022)