Section 121 - Erosion Control(a) Quarry stone, cobblestone, or their equivalent may be used for erosion control along rivers and streams if the material meets the criteria below. Typical sections delineating methods of placement and dimensions of revetment using rock and sacked concrete are shown in Figures 8.02 and 8.03. (1) Bedding materials must be placed under the stone protection at locations where the underlying soils require such material for stabilization, considering such factors as tidal fluctuation, wave action, and streamflow velocity.(2) Cobblestone protection must be placed on prepared slopes of three (3) feet horizontal to one (1) foot vertical or flatter.(3) Cobblestone protection, having acceptable cobblestone gradations, may be used where streamflow velocities ten (10) feet from the bank do not exceed eight (8) feet per second.(4) Quarry stone protection must be placed on prepared slopes steeper than three (3) feet horizontal to one (1) foot vertical.(5) Quarry stone protection, meeting required gradations and sizes, may be used at locations where streamflow velocities ten (10) feet from the bank do not exceed twelve (12) feet per second.(6) Required gradations of cobblestone and quarry stone are as follows: Cobblestone | Quarry stone |
Stone Size | Percent Passing | Stone Size | Percent Passing |
| 15 " | 100 | 15 " | 100 |
| 10 " | 55 to 95 | 8 " | 80 to 95 |
| 8 " | 35 to 65 | 6 " | 45 to 80 |
| 6 " | 10 to 35 | 4 " | 15 to 45 |
| 3 " | 1 to 5 | 2 " | 0 to 15 |
(7) Graded cobblestone and quarry stone must be placed in a manner which avoids segregation.(8) Where streamflow velocities ten (10) feet from the bank exceed twelve (12) feet per second, special cobble or quarry stone gradation is required. Flow retarding structures, such as retards, wing dams, and rock groins may be permitted at these high streamflow velocity sites.(9) Alternative bank protection materials may be permitted by the board. Possible alternatives include but are not limited to: sacked concrete; broken concrete free of projecting steel; reinforced concrete; precast concrete cribbing; and stone-filled gabion baskets.(10) Broken concrete used for levee revetment may be no larger than sixteen (16) inches at its maximum dimension.(11) Asphalt or other petroleum-based products may not be used as fill or as erosion control on a levee section or within a floodway.(12) The minimum thickness of revetment is eighteen (18) inches perpendicular to the bank or levee slope below the usual water surface and twelve (12) inches above the usual surface.(13) Revetment must be uniformly placed and properly transitioned into the bank, levee slope or adjacent revetment.(b) When revetment is proposed by an applicant but not required by the board, the standards relating to revetment bedding, gradation, size, shape and thickness are recommended but not required.Cal. Code Regs. Tit. 23, § 121
1. New section and figures 8.02 and 8.03 filed 9-30-96; operative 10-30-96 (Register 96, No. 40). Note: Authority cited: Section 8571, Water Code. Reference: Sections 8608, 8609 and 8710, Water Code.
1. New section and figures 8.02 and 8.03 filed 9-30-96; operative 10-30-96 (Register 96, No. 40).