Article 25 — GH (Geologic Hazard) Overlay Zone — Atascadero Zoning Code

§ 9-3.611. Purpose. ¶

A Geologic Hazard Overlay Zone is applied to areas where geologic and soil conditions could present new developments and their users with potential hazards to life and property. These standards are applied where the following conditions exist:

(a) Seismic Hazard. Areas of seismic (earthquake) hazard are identified through the application of special studies zones established by the State Geologist as required by Sections 2621 et seq., of the Public Resources Code (the Alquist Priolo Special Studies Zones Act).
(b) Landslide Hazard. Areas identified as being subject to moderately high to high landslide risk.

§ 9-3.612. Applicability of geologic hazard standards. ¶

The standards of Sections 9-3.613 and 9-3.614 apply to all land uses for which a zoning approval is required, except:

(a) One single family residence when not constructed in conjunction with two or more residences by a single contractor on abutting lots of record, unless located in an area subject to liquefaction or landslide.
(b) Any agricultural use not involving a building, and any agricultural accessory structure.
(c) Alterations or additions to any structure, the value of which does not exceed 50% of the assessed value of the structure in any 12 month period.
(Ord. 68 § 9-3.612, 1983)

§ 9-3.613. Application content: Geologic and soils report required. ¶

All applications for projects located within a Geologic Hazard Overlay Zone (except those exempted by Section 93.612 ) are to be accompanied by a report prepared by a registered civil engineer and/or engineering geologist, as appropriate, which identifies, describes and illustrates, where applicable, potential hazard of surface fault rupture, seismic shaking, liquefaction or landslide, as provided by this section; provided, however, that no report is required for an application located in an area for which the City Engineer determines that sufficient information exists because of previous geologic or soils reports. Where required, a geologic report is to include:

(a) A review of the local and regional seismic and other geologic conditions that may significantly affect the proposed use;
(b) An assessment of conditions on or near the site that would contribute to the potential for the damage of the proposed use from a seismic or other geologic event or the potential for a new use to create adverse effects upon existing uses because of identified geologic hazards. The conditions assessed are to include, where applicable,

rainfall, soils, slopes, water table, bedrock geology, and any other substrata conditions that may affect seismic response, landslide risk or liquefaction potential;

(c) Conclusions and recommendations regarding the potential for, where applicable:
- (1) Surface rupture or other secondary ground effects of seismic activity at the site,
- (2) Active landsliding or slope failure,
- (3) Adverse groundwater conditions,
- (4) Liquefaction hazards;
(d) Recommended building techniques, site preparation measures, or setbacks necessary to reduce risks to life and property from seismic damage, landslide, groundwater and liquefaction to insignificant levels.
(Ord. 68 § 9-3.613, 1983)

§ 9-3.614. Geologic Hazard Overlay Zone special standards. ¶

All uses within a Geologic Hazard Overlay Zone are to be established and maintained in accordance with the following, as applicable:

(a) Grading. Any grading not otherwise exempted from the permit requirements of Sections 9-4.138 et seq., is to be performed as engineered grading under the provisions of those sections.
(b) Seismic Hazard Areas. No structure intended for human occupancy shall be located within 50 feet of an active fault trace within a special studies zone.
(Ord. 68 § 9-3.614, 1983)