§ 120. Levees.
23 CA ADC § 120Barclays Official California Code of Regulations
23 CCR § 120
§ 120. Levees.
(a) Levees constructed, reconstructed, raised, enlarged, or modified within a floodway shall be designed and constructed in accordance with the U.S. Army Corps of Engineers manual, “Design and Construction of Levees” (EM 1110-2-1913 dated March 31, 1978, which is incorporated by reference) and as supplemented with the following standards:
(2) An engineering analysis that evaluates levee embankment and foundation stability shall be submitted to the board with the permit application. The analysis must verify that the levee is adequately designed and will be constructed to remain stable under loading conditions for “Case IV - Steady seepage from full flood stage” as defined in the Department of the Army manual, “Design and Construction of Levees” (EM 1110-2-1913), pp.6-6, 6- 7.
(5) The applicant shall provide the board with a permanent easement granting the Sacramento and San Joaquin Drainage District all flood control rights upon, over, and across the property to be occupied by the proposed flood control works. The easement must include the area within the proposed floodway, the levee section, and the area at least ten (10) feet in width adjacent to the landward levee toe if the area is not presently encumbered by a board easement. The board may require an easement over a larger area and over any property when it is foreseeable that the proposed activities subject to a permit would be injurious to or interfere with the adopted plan of flood control.
(8) Prior to construction or enlargement of the embankment, all surface vegetation shall be removed from the area to receive fill to a depth of six (6) inches. Organic soil and roots one and one-half (1- ½ ) inches in diameter or larger, shall be removed from the area to receive fill to a depth of three (3) feet.
(12) Impervious material, with twenty (20) percent or more of its passing the No. 200 sieve, and having a plasticity index of eight (8) or more, and having a liquid limit of less than (50), must be used for construction of new levees and the reconstruction of existing levees. Special construction details (e.g., 4:1 slopes) may be substituted where these soil properties are not readily attainable. Where the design of a new levee structure utilizes zones of various materials or soil types, the requirements of this subdivision do not apply.
(13) Fill material must be placed in four (4) to six (6) inch layers and compacted with a sheepsfoot roller, or equivalent, to a relative compaction of not less than ninety (90) percent per ASTM D1557-91, dated 1991, which is incorporated by reference and above optimum moisture content, or ninety-seven (97) percent per ASTM D698-91, dated 1991, which is incorporated by reference and at or above optimum moisture content.
(31) The minimum crown width of a levee is normally twelve (12) feet on minor streams and twenty (20) feet on major streams. The levee crown width for a levee on a specific stream is defined by the project document and/or operations manual in current use and must be consistent with minimum width requirements of existing levees on the specific stream.
(33) As used in this section, the term “approved risk-based analysis” means an analysis which uses simulation modeling of river discharge versus probability of occurrence, river stage versus river discharge estimates, and river stage versus flood damage estimates and accounts for uncertainty in these functions to determine the performance of a proposed flood control feature.
(g) If a proposed project which includes levee improvements would result in substantial residential development within an area that without the levee improvements would be subject to the Federal Emergency Management Agency's regulatory 100-year flood plain constraints, the board may require the permittee to mitigate for any increased average annual flood damage by increasing the level of protection provided by the levee improvement project, up to and including the Standard Project Flood.
Credits
Note: Authority cited: Section 8571, Water Code. Reference: Sections 8608, 8609 and 8710, Water Code.
History
1. New section and figure 8.01 filed 9-30-96; operative 10-30-96 (Register 96, No. 40).
2. Amendment of subsections (a)(5) and (a)(22) filed 12-1-2009; operative 12-31-2009 (Register 2009, No. 49).
This database is current through 8/30/24 Register 2024, No. 35.
Cal. Admin. Code tit. 23, § 120, 23 CA ADC § 120
End of Document |