(a) The standards for construction or modification of bridges within an adopted plan of flood control are as follows:(1) Any excavation within the levee section or near bridge supports within the floodway must be backfilled in four- (4) inch to six- (6) inch layers with approved material. The levee section must be compacted 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. Compaction within the floodway must be to the density of the adjacent undisturbed material.(2) Compaction tests by a certified soils laboratory may be required to verify compaction.(3) Bridge piers and bents within the floodway must be constructed parallel to the direction of streamflow.(4) Bridge piers and bents placed within a floodway to support a widened portion of an existing bridge must be constructed in line with existing bents and piers.(5) Erosion control may be required on the channel banks or levee slopes upstream and downstream of a proposed bridge.(6) Drainage from a bridge or highway may not be discharged onto a levee section or streambank.(7) Plans showing all construction facilities (such as temporary staging, coffer dams, and falsework) which will remain in a floodway during flood season, must be submitted to the board for approval prior to installation of these facilities.(8) All construction facilities (such as temporary staging, coffer dams, and falsework) must be designed to prevent bank erosion during normal flows and to maintain maximum channel capacity during the flood season.(9) Stockpiled material, temporary buildings, construction equipment, and detours that obstruct streamflows must be removed from floodways prior to the flood season.(10)(A) The bottom members (soffit) of a proposed bridge must be at least three (3) feet above the design flood plane. The required clearance may be reduced to two (2) feet on minor streams at sites where significant amounts of stream debris are unlikely.(B) When an existing bridge being widened does not meet the clearance requirement above the design flood plane, the bottom structural members of the added section may be no lower than the bottom structural members of the existing bridge, except as may be caused by the extension of existing sloped structural members.(C) When the clearance requirement above design flood plane would result in bridge approach ramp fill in the floodway, the clearance requirement may be reduced to the extent that reasonably balances clearance and fill that would obstruct flow, so as to maintain maximum channel capacity.(11)(A) Vehicular access from the roadway to the levee crown may be required at each end of a bridge.(B) Vehicular access from the levee crown to the floodway and/or the landside levee toe beneath the bridge may be required. Ramps may slope upstream as necessary to provide the access required by this subdivision.(12) Approved gates must be installed at right angles across the levee crown at all points of access to the levee from each end of a bridge.(13) Any bridge abandoned or being dismantled must be completely removed, and must be disposed of outside the limits of the levee section and floodway.(14) Pilings, piers, bents, and abutments of bridges being dismantled must be removed to at least one (1) foot below the natural ground line and at least three (3) feet below the bottom of the low water channel.(15) Any bridge that is damaged to the extent that it may impair the channel or floodway capacity must be repaired or removed prior to the next flood season.(16) Replacement railroad bridges must have the soffit members no lower than those of the replaced bridge, but are not required to have a specified amount of clearance above the design flood plane.(17) Bridge replacements and new bridges shall be built at an elevation so that there is no depression in the crown of the levee.(b) The standards for maintenance of bridges within an adopted plan of flood control are as follows: (1) The area in and around a bridge site must be kept clear to maintain the design flow capacity.(2) Trees, brush, sediment, and other debris must be kept cleared from the bridge site and be disposed of outside the limits of the floodway prior to the flood season.(3) Any accumulation of debris during high flows must be immediately removed from a bridge site and disposed of outside the floodway.Cal. Code Regs. Tit. 23, § 128
1. New section 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 filed 9-30-96; operative 10-30-96 (Register 96, No. 40).