SEMSWA Floodplain goals include protecting and educating the public and protecting property, structures and infrastructure from the damage and cost of floods through the implementation and enforcement of floodplain management standards. SEMSWA enforces the City's floodplain regulations.
Regulatory Mechanism/Code References
The City of Centennial’s Land Development Code (LDC) outlines allowed uses of the Floodplain and the process for obtaining a Flood Development Permit. The specific sections called out below govern the uses of the 100-year floodplain, which includes the flood fringe and floodway (see Figure 1, components of the 100-year floodplain. Staff in the SEMSWA Floodplain Group have access to the most recent floodplain information and should be contacted with any questions regarding the floodplain, designated SFHA (Special Flood Hazard Areas are identified by the Federal Emergency Management Agency on the "Flood Insurance Rate Map (FIRM)" and in the “Flood Insurance Study (FIS)” dated December 17, 2010), Flood Fringe, and/or Floodways. The following LDC Sections prohibit and enforce violations associated with the floodplain.
- LDC, Division 7-2, Section 12-7-202 Use of Floodplains, Special Flood Hazard Area (SFHA), Flood Fringe and Floodways lists the permitted uses and restrictions of land that is within the floodplain, special flood hazard area (SFHA), flood fringe or floodway, and performance standards for those uses. All uses of the floodplain and SFHA shall comply with applicable floodplain management regulations contained in Division 7-3, Floodplain Management and Flood Damage Prevention, as may be amended from time to time and the SEMSWA Stormwater Management Manual.
- LDC, Division 7-2, Section 12-7-303, General Provisions, states, “No structure or land may be constructed, located, extended, converted, or altered without full compliance with the terms of Article 7, Open Space, Floodplain Management, and Environmental Quality, and other applicable regulations. Where Article 7, Open Space, Floodplain Management, and Environmental Quality, conflicts or overlaps with another Section, easement, covenant, or deed restriction enforceable by the City, whichever imposes the more stringent restrictions shall prevail.
- LDC, Division 7-3, Floodplain Management and Flood Damage Prevention, sets out the technical standards and restrictions for development within the floodplain and special flood hazard areas within the City and should be referenced in conjunction with Article 12-14-206 for violations associated with a Floodplain Development Permit.
- LDC, Division 15-2, Section 12-15-201, Violations provide the City with charging language for violations of the LDC and states, “Each calendar day of a continuing violation shall be counted as a separate violation of this LDC.”
- LDC, Division 15-3, Section 12-15-302, Immediate Orders, Permit Holds and Judicial Remedies, provides the enforcement tools that can be used to enforce violations of the LDC.
Activies that are NEVER allowed in the Floodplain
Use Factors: In general any use that has potential for the following to occur is prohibited in the floodplain:
- Obstruction (e.g.. Fill) of the flood water flow so that the floodplain is altered in elevation and extent in excess of the allowable criteria (unless approved through a floodplain modification study).
- Reduction in the carrying capacity of the channel (unless approved through a floodplain modification study).
- Storage of materials, equipment, or facilities that could become dislodged or displaced and /or deposited downstream causing culvert or bridge blockage, channel degradation, or damages to other properties.
- Activities that negatively impact water quality.
Prohibited Uses. The City has determined that the following uses are prohibited within the floodplain:
- All new construction of structures including residential, non-residential, recreational.
- Fill in the floodplain for the purpose of obtaining a CLOMR-F/LOMR-F for future site development.
- New construction of critical facilities.
- Additions to existing structures.
- Permanent fencing, including solid or perforated wood, split rail, chain link, stone, brick and/or other materials.
- New construction of landscaping walls or structural walls that extend or flatten land that result in floodplain encroachment.
- Storage process of materials, or any other activity that may have an adverse impact on water quality.
- Storage or processing of materials, which are buoyant, flammable, explosive, or could cause injury to humans, animals, or plants.
- New construction of streets
- Permanent toilet facilities.
- New construction of structures, ponds, or appurtenances related to water and wastewater treatment facilities.
- Parking lots in the floodplain fringe are prohibited unless it is associated with an approved floodplain use such as recreation facilities/parks where the use is for a short period of time.
- Detention or water quality ponds not part of a regional or approved drainage master plan.
Storage of Materials. Storage of hazardous or floatable materials in the floodplain is prohibited. These materials represent a significant potential public health, environmental or safety risk. Floatable materials can also become lodged in culverts, bridges and channels resulting in increased damages resulting from increased flood depths or diversion of flood waters.
- Temporary storage of construction-related vehicles and materials, including fencing, may be permitted, depending upon location and type of material storage.
Activities that are allowed in the floodplain with the proper Permits
The City has determined that the following uses and improvements may be considered within the floodplain if it is determined that the proposed use or improvement is in conformance with the floodplain management regulations and floodplain management goals.
- Agriculture (including crop production, livestock grazing, and fish hatcheries) and nursery, where allowed in the applicable zoning district.
- Noncommercial production of crops (e.g., orchards or garden plots that are an amenity to development) – gardens in boxes must be permitted.
- Nature areas, picnic areas, and trails. Furniture cannot be placed in the floodway. Furniture in the flood fringe area must be permitted and if allowed, anchored.
- Ball Fields. Structures, including bleachers, are not allowed.
- Golf courses, provided that: The applicant provides a management plan that demonstrates that downstream water quality will not be adversely affected by fertilizers and pesticides associated with the use; Pedestrian or golf cart trails and bridges that are designed to pass the 10-year flood event with freeboard as per requirements of the Stormwater Management Manual.
- Play courts / Playground Equipment (in the flood fringe only).
- Recreational camps.
- Trails and Paths open to the general public.
- Facilities for watershed protection and similar uses.
- Detention and water quality facilities associated with approved master drainage plans.
- Maintenance of existing local streets.
- Underground utilities (that cross through the entire floodplain) as long as adequate cover (as defined by criteria for each utility type) exists to protect the utilities.
- Parking for park and public facilities.
- Landscaping in conformance with the uses allowed in Section 12-7-202, Use of Floodplains.
Uses Not Listed.
- Uses not specifically listed above may be permitted if, in the opinion of the Director (or designee), they are similar in character to permitted uses in this district, and are in conformance with the intent of this district. Uses not specifically prohibited in this section should not be construed as allowed by exclusion.
ALL activities in the floodplain, regardless of impact, need to be permitted. Even when it is apparent that there are no adverse impacts to the floodplain, a permit is required. Common floodplain activities that must be permitted:
- Floodplain modifications – including an any filling, grading, channel improvements or channel works of any kind
- Stabilization improvements – drop structures, rip rap, bank protection
- Installation or maintenance of bridges, culverts, other conveyances
- Any improvements to structures within the floodplain
- Landscaping – including grading, clearing, re-vegetation, tree planting, retaining walls, bridges, stairs, etc.
- Trenching operations associated with utility construction or maintenance
- Installation and maintenance of storm sewer outfall structures
- Fencing, when approved
- Trail construction or rehabilitation
- Construction and maintenance of master planned on-line detention or water quality facilities
- Installation and maintenance of park and recreation facilities