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A floodplain use permit shall be required for extraction of sand, gravel and other earth products within a floodway or floodplain (which includes the floodway fringe areas) or erosion hazard areas. An engineering study outlining effects on stream mechanics prepared by a state- registered professional civil engineer shall be required with an application for a floodplain use permit for major extraction operations, for operations in locations that appear to be hazardous because of their relative proximity to structures or banks of watercourses, and for any other operations considered by the city engineer to be potentially hazardous. The operations plan and any engineering study required shall meet the approval of the city engineer. For other operations, a study may be required, at the discretion of the city engineer, depending upon the nature of the proposed operation.
The engineering study is for the purpose of evaluating the possible flood- and erosion- related hazards and must include considerations of effects of the excavation on water velocities, direction of flows, volume of flows, channel geometry (shape and size), type of channel banks, depth of flow, and other items that may be pertinent to stream mechanics, which includes an analysis indicating a balanced sediment flow system or channel aggradation, and resultant effects on structures (including but not limited to roads, bridges, culverts and utilities), banks of watercourses, adjoining lands, and groundwater recharge for the respective alluvial watercourse.
Floodplain use permits for sand and gravel mining operations shall be issued for a time limit of one (1) year only. All such permits are subject to review by the city engineer prior to issuance. No mining operation shall be commenced without an approved permit.
In granting the permit, the city engineer may impose restrictions/conditions regarding the location and boundaries of the area where excavations/stockpiles are allowed, the quantity of excavations/stockpiles, and time period and methods of operation.
After July 25, 1990, the effective date of this section, any extraction of sand and gravel or related materials in the floodway, floodway fringe or erosion hazard areas shall be allowed only if a reclamation plan is also provided for the extraction operation. The reclamation plan shall show that all adverse effects of extraction are mitigated. The plan shall also contain a timetable and financial assurances for accomplishing reclamation.
The city engineer may require bonds or other financial assurances appropriate for the sand and gravel extraction operation.
(Ord. No. 7407, § 5, 6-25-90)
(a) There shall be no stockpiling within the floodway of materials or tailings that may obstruct, divert or retard the flow of floodwaters, except as may be approved by the city engineer pursuant to an application for a floodplain use permit.
(b) The storage or processing of materials that are in time of flooding buoyant, flammable, explosive, or that could be injurious to human, animal or plant life is prohibited. Storage of other materials or equipment may be allowed if it is not subject to major damage by floods, and is firmly anchored to prevent flotation, or is readily removable from the area within the very short time available after a flood warning.
(Ord. No. 7407, § 5, 6-25-90)
All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system and discharge from systems into floodwaters.
On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.
Waste disposal systems shall not be installed wholly or partially in a floodway.
(Ord. No. 7407, § 5, 6-25-90)
The banks of watercourses constitute an erosion hazard zone which is subject to channel widening and/or meandering. Setback distances are best determined by a detailed engineering study performed by a state-registered professional civil engineer. Guidelines for such studies and for determining setbacks are found in the Standards Manual for Drainage Design and Floodplain Management in Tucson, Arizona (Standards Manual).
Setbacks from unstabilized banks may be determined by use of methodology found in the Standards Manual.
Reduced setbacks may be considered at the discretion of the city engineer only upon submitting to the city a detailed engineering study performed by a state-registered professional civil engineer for review and approval.
(Ord. No. 7407, § 5, 6-25-90)
Unless a more restrictive setback has been determined, the minimum setback to structures, for the corresponding regional watercourses, shall be as indicated in Table I.
Table I
Watercourse | Minimum Setback in Straight Section (Feet) | Minimum setback in Curved Section (Feet) |
Pantano Wash | 360 | 900 |
Rillito Creek | 360 | 900 |
Santa Cruz River | 490 | 1,230 |
Curved sections are any sections of the watercourse that do not meet the criteria of equation 7.7a of the Standards Manual.
When banks are protected to the regulatory design requirements the setback to structures shall be fifty (50) feet.
Setbacks for other regional watercourses may be determined from guidelines in the Standards Manual.
(Ord. No. 7407, § 5, 6-25-90; Ord. No. 11801, § 1, 12-8-20)
When the banks are stabilized to the level of the base flood (plus an appropriate freeboard) the setback to structures shall be a minimum of twenty (20) feet for access and maintenance. When access and maintenance easements are not required by the city engineer, the minimum setback may be reduced to ten (10) feet at the discretion of the city engineer. When banks are not stabilized, the setback to structures shall be as calculated from guidelines in the Standards Manual.
(Ord. No. 7407, § 5, 6-25-90)
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