AGENDA ITEM
TO:
HONORABLE CHAIR
AND MEMBERS OF THE PLANNING COMMISSION
FROM:
COLLEEN T. DOAN
COMMUNITY DEVELOPMENT DIRECTOR
SUBJECT:
title
CONSIDERATION OF AN ORDINANCE AMENDING THE CITY’S ZONING CODE CONCERNING PERMEABLE HARDSCAPE AND LANDSCAPE MATERIALS
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Summary:
Form of Notice: The City published the required Notice in the Signal Hill Tribune newspaper per Government Code §65854(b)(2) on July 25, 2025; and posted in accordance with Signal Hill Municipal Code Section 1.08.010 on July 25, 2025.
The City of Signal Hill (“City”) has current regulations in place aimed at alleviating the negative health impacts associated with the potential concentrations of methane gas caused by the legacy of oil operations and other natural means occurring subsurface within and outside the City. Through the subject ordinance, the City desires to implement additional environmentally conscious measures to reduce such impacts by requiring that replacement of existing hardscape and landscape materials in the City’s residential and commercial zones, including all Specific Plans, would require administrative review to ensure that a certain level of permeability is maintained.
Strategic Plan Goal(s):
Goal No. 2 Community Safety: Maintain community safety by supporting public safety services and increasing emergency preparedness.
Goal No. 5 High-Functioning Government: Strengthen internal communication, recruitment, retention, systems, and processes to increase the effectiveness and efficiency of City services.
recommendation
Recommendation:
Adopt a resolution recommending City Council adoption of Zoning Ordinance Amendment 25-01, entitled:
AN RESOLUTION OF THE PLANNING COMMISSION OF THE CITY OF SIGNAL HILL, CALIFORNIA, RECOMMENDING CITY COUNCIL APPROVAL OF ZONING ORDINANCE AMENDMENT 25-01, AMENDING CHAPTERS 20.10 “RESIDENTIAL DISTRICTS” AND 20.20 “COMMERCIAL DISTRICTS” OF TITLE 20 “ZONING” OF THE SIGNAL HILL MUNICIPAL CODE TO REGULATE PERMEABLE HARDSCAPE AND LANDSCAPE MATERIALS; AND FINDING SAID ACTION EXEMPT FROM THE CALIFORNIA ENVIRONMENTAL QUALITY ACT
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Background:
The City of Signal Hill, California (“City”) is a municipal corporation, duly organized under the California Constitution and laws of the State of California. Pursuant to the police powers delegated to it by Article XI, Section 7 of the California Constitution, the City has the authority to enact laws which promote the public health, safety, and general welfare of its citizens, that are not in conflict with general law.
The City’s legacy of oil operations has the potential for the presence of concentrations of methane gas which can rise up from the subsurface, accumulate, and present a fire hazard if pressurized. The City’s Municipal Code (“SHMC”) has existing regulations aimed at reducing the negative environmental impacts associated with methane. Such regulations include but are not limited to:
• Requiring a methane assessment for all proposed property development, the result of which may require methane mitigation (SHMC Section 16.24.080(C)-(D).); and
• Requiring methane mitigation for all properties with development proposed over or in close proximity to abandoned wells (SHMC Section 16.24.090(6)(C).).
As an example, in the Town Center Northwest Specific Plan (SP-24), the City requires that any deviation or change out of hardscape and landscape materials requires administrative review and approval before installation of such materials, to ensure methane mitigation is maintained in such areas (SHMC Section 20.46.100(J).) “Hardscape” is defined by the City’s Municipal Code to mean, “paved or installed materials both permeable and non-permeable such as concrete, grasscrete, pavers, asphalt, or a combination of such materials.” (SHMC Section 20.04.364.) The subject ordinance further defines artificial turf as a nonpermeable material.
Analysis:
Methane Gas
Methane gas is lighter than air, colorless, odorless, non-carcinogenic, and flammable. Methane occurs naturally in coal mines, oil and gas fields, and other geological formations, in natural settings (e.g., wetlands), and man-made settings (e.g., landfills, engineered fill, hydrocarbon waste, food processing facilities, sewer lines, septic systems, dairies and concentrated animal feedlots). Given that methane is lighter than air, it tends to seek the path of least resistance to rise from ground surface where it harmlessly dissipates into the atmosphere. Where a relatively impermeable barrier, such as a concrete slab, artificial turf, decomposed granite, pavers, asphalt driveways and concrete walkways, is present at the ground surface, methane cannot dissipate and may become trapped or pressurized. Since methane is combustible and potentially explosive if present at concentrations in excess of 53,000 parts per million by volume (ppmv) in the presence of oxygen, the City regulates development and redevelopment to ensure concentrations remain at a much lower level, at a maximum of 500 ppmv with the use of various types of venting systems and other mitigation measures.
Ordinance Intent and Purpose
Since replacement of permeable landscape areas, which act as venting systems, with nonpermeable materials such as patios, walkways, or even artificial turf, reduces the permeability of a property, an ordinance providing guidance, information, and plan review by staff for replacement of existing landscape materials is appropriate as a health and safety measure. The intent of the proposed ordinance is to reduce the potential for methane accumulation underneath proposed or existing structures and to minimize the potential for migration of methane offsite by maximizing the permeability of landscaping surrounding the structure. Through the proposed Ordinance (Attachment A), the City desires to regulate changes to existing hardscape and landscape materials in the City’s residential and commercial zones (including Specific Plans) by requiring a certain level of permeability be maintained. The purpose of this Ordinance is to establish a maximum percentage of nonpermeable replacement materials to protect public safety while allowing for design flexibility.
Specifically, for residential districts, the proposed ordinance would limit the maximum amount of nonpermeable materials, whether hardscape material or artificial turf, within the front setback to twenty-five percent of the allowed hardscape area. This area, as currently provided, includes walkways, patios and courtyards but excludes driveways.
For both residential and commercial districts, newly constructed buildings or structures, and structural and physical improvements, the Ordinance both limits the maximum allowed nonpermeable materials, including artificial turf, and may require installation of vent boxes for methane mitigation.
Further, any deviation or change out of hardscape materials or landscape materials on either residential or commercial properties requires administrative review by the Director of Community Development, and approval, prior to installation, to ensure the requirements of the Ordinance are met and maximum methane mitigation is maintained. The Ordinance also sets forth the following regulations concerning the placement of nonpermeable materials on the property or development area in both districts, which include but are not limited to:
• The total percentage of nonpermeable hardscape and permeable landscape and hardscape materials on a property or development area;
• That every structure or building be bordered on at least three sides by permeable materials; and
• Exceptions from the above two bullet points may apply for a property or development area that has City-approved vent boxes installed for methane mitigation.
Conclusion
To aid in the Commission’s review, the proposed changes to the existing language of the City’s Municipal Code are underlined for the inclusion of new language and struck through for the deletion of existing language.
If adopted, the City Council shall direct the City Clerk to instruct the City Codifier to include the adopted ordinance language in all Specific Plans both residential and commercial.
CEQA Categorical Exemption
This Ordinance is exempt from review under the California Environmental Quality Act (“CEQA”) (California Public Resources Code Section 21000 et seq.), because pursuant to State CEQA Regulation 15307 (14 Cal. Code Regs., § 15307), this Ordinance is covered by the CEQA Categorical Exemption for actions taken to assure the maintenance, restoration, enhancement, or protection of a natural resource where the regulatory process involves procedures for protection of the environment. The adoption of this Ordinance will result in the enhancement and protection of land and water resources in the City, and will not result in cumulative adverse environment impacts. It is therefore exempt from the provisions of CEQA.
Approved:
Colleen T. Doan
Attachment A: Resolution XXX-08-19