Sacramento County Zoning Code § 906-05 Special Construction

A. Anchoring. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the building resulting from hydrodynamic and hydrostatic loads including the effects of buoyancy. All manufactured homes shall also meet the standards of Section 906-07.
B. Construction materials and methods. Unless specifically described in 906-04, all new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage and using methods and practices that minimize flood damage. Electrical, heating, ventilation, plumbing and air conditioning equipment, and other service facilities shall be designed and/or located to prevent water from entering or accumulating within the components during flooding.
C. Compacted Fill. If a site is filled above the base flood elevation, then buildings constructed within special or local flood hazard areas must be constructed on compacted fill in accordance with the Construction Specifications or at least 90% density per ASTM-01557 (known as Modified Proctor) and extending at least five feet beyond the building foundation walls before dropping below the base flood elevation and shall include appropriate protection from erosion and scour. The design of the fill must be approved by a registered professional engineer.
D. Drainage Paths -Zones AO and AH. Within zones AO and AH, drainage paths around buildings on slopes are required to guide floodwater around and away from proposed buildings.
E. Underground and above-ground tanks shall be designed, constructed, installed, and anchored to prevent flotation, collapse, and lateral movement resulting from floodwater loads, including the effects of buoyancy, hydrostatic pressure, and velocity. Tank inlets, fill openings, outlets, and vents shall be installed 1 foot above the base flood elevation or fitted with covers designed to prevent the inflow of floodwater and outflow of the contents of the tank during the base flood. Water tanks for agricultural operations may be exempted from this elevated venting requirement.
F. Foundations. Foundations and walls constructed below the base flood elevation shall be vented to equalize hydrostatic pressures. Vent openings shall be permanent openings in the walls that allow for the free passage of water automatically in both directions without human intervention. Such venting shall be on at least two sides of the structure, or enclosure, and have a bottom at no more than 1 foot above the ground elevation. The total area of such venting shall be at least one square inch per square foot of enclosed footprint. Openings may be equipped with screens, louvers, or automated float control in accordance with FEMA Technical Bulletin TB #108 Foundations and walls below the base flood elevation shall be constructed of flood-resistant materials in accordance with FEMA Technical Bulletin TB #2-08. Alternatively, the project proponent may submit a design that will allow for automatic equalization of hydrostatic flood forces on exterior walls, signed and stamped by a registered civil engineer and approved by the Floodplain Administrator. A window, a door, or a garage door is not considered a vent opening. If there are multiple enclosed areas within the foundation, each area must be vented as herewith described.
G. Non-Conversion. To put current and future tenants and owners on notice that the area below the base flood elevation may not be architecturally finished and converted to living space and that the space may only be used as incidental material storage, building access, and vehicle parking [also see 906-04], a declaration of land use restriction shall be executed and recorded whenever there is a height of more than five feet to assure that foundation area is never converted to living space. The declaration of land use restriction shall be in a form acceptable to the Floodplain Administrator and County Counsel. The Floodplain Administrator shall have the right to inspect for conversion with 72-hour notice.
H. Basements. A Basement may be constructed with a floor elevation that conforms to Section 90602.
I. Electrical panels for uses other than new or substantially improved residential, commercial, or industrial structures (such as agricultural wells and barns) in areas protected by RD1000 levees

(Natomas area), and in the Delta Area may be installed below the base flood elevation. In this case, marine-grade (or otherwise flood-resistant) equipment is recommended.

J. Commercial solar power plants are treated as development (Section 906-06), and any structures or electrical panels for such facilities shall be elevated or flood-proofed at least 1.5' above the base flood elevation and designed and anchored in accordance with this section. A declaration of land use restriction in a format approved by County Counsel must be recorded if any part of the commercial solar development will be lower than 1.5' above the base flood elevation.
K. Any structure with the increased cost of compliance flood insurance coverage that sustains flood damage on two or more occasions exceeding 25 percent of the market value (measured before the recent damage occurred) but less than 50 percent in any one event should, as such insurance allows, elevate or otherwise mitigate the flood risk.