Chapter 15.08
DRAINAGE REGULATIONS
Sections:
15.08.020 Application and exceptions.
15.08.030 Copies of Town Drainage Regulations available.
15.08.040 Requirements for storm water detention and drainage facilities.
15.08.050 Storm water detention systems which are not permitted.
15.08.060 Additional requirements for subdivisions.
15.08.070 Additional requirements for preliminary plat submittals.
15.08.080 Additional requirements for final plat submittals.
15.08.090 Erosion hazard and building setbacks from watercourses.
15.08.100 Minimum elevation of lowest finished floor for residential construction.
15.08.010 Purpose.
The purpose of this chapter is to provide requirements and guidelines for drainage design, engineering, and construction for projects and developments within the Town. The requirements for sound drainage design, engineering, and construction of all drainage facilities, including storm water and runoff drainage, is an essential part of every development and construction project within the Town, and is necessary for the health, safety, and protection of all residents and property owners within the Town. (Ord. 08-318 § 2)
15.08.020 Application and exceptions.
The Town Drainage Regulations shall apply to all construction projects and developments except single-family detached dwelling units on individual lots excluding Section 15.08.100, single commercial detached buildings on one-half (1/2) acre or less, or when the Town Engineer shall determine that the regulation is not necessary or does not apply. (Ord. 21-443 § 1; Ord. 08-318 § 2)
15.08.030 Copies of Town Drainage Regulations available.
Copies of the "Town Drainage Regulations" are available at the Pinetop-Lakeside Town Office, 325 W. White Mountain Blvd. Lakeside, AZ 85929, Monday through Friday, 8:00 a.m. to 5:00 p.m. (Ord. 08-318 § 2)
15.08.040 Requirements for storm water detention and drainage facilities.
A. All construction and development to which this chapter applies shall provide a preliminary and a final drainage report prepared and sealed by a professional engineer licensed in the State of Arizona. In addition, when required, owners, developers, and builders shall prepare engineering plans and specifications, and will construct storm water and drainage facilities necessary to ensure that all improvements, buildings, structures, lots, parcels, and properties located within the subject development, and those located adjacent to, upstream and downstream of the construction or development, shall be protected from the adverse impact of storm water runoff caused by or related to the proposed construction or development.
B. All subdivisions whether new, replatted, or redeveloped shall be required to provide on-site storm water detention and drainage facilities for the entire subdivision, including all adjacent streets and roads. Adjacent subdivisions may join together to provide a common storm water detention facility.
C. On-site surface or underground storm water detention facilities shall be designed in accordance with good and acceptable engineering practices as approved by the Town Engineer. See Town’s Drainage Design Guidelines.
D. No part of a private detention basin shall be constructed on public property, in a public right-of-way or public utility easement.
E. All storm water detention facilities’ and drainage facilities’ plans, engineering, and construction shall be approved by the Town Engineer and are subject to approval by the Town in accordance with this Town Code.
F. Maintenance and operation of on-site detention facilities shall be the responsibility of the property owner or homeowners’ association.
G. The owner or the homeowners’ association shall be solely responsible for obtaining a storm water detention facility(ies) inspection and certification by a professional engineer licensed in the State of Arizona every three (3) years or within forty-five (45) days of a written request by the Town Engineer. A copy of the inspection report and certification shall be provided to the Town.
H. Detention basins and related facilities should be designed and maintained to minimize the following typical problems:
1. Weed growth.
2. Grass and vegetation maintenance.
3. Sedimentation control.
4. Bank deterioration.
5. Standing water or soggy surfaces.
6. Mosquitoes.
7. Blockage of outlet structures.
8. Litter accumulation.
9. Maintenance of fences and perimeter plantings.
I. No detention facility shall retain standing water longer than thirty-six (36) hours unless the facility has been designed and constructed as a permanent body of water (e.g., a lake) with appropriate health, safety, and water quality measures for such a body of water.
J. The use of retention or infiltration storm water systems is discouraged unless it can be demonstrated that no other means of drainage conveyance would suffice or, due to the nature of the site and topography, a detention system is not feasible. All systems must drain down within thirty-six (36) hours of a storm event per State Standard 8-99, Stormwater Detention/Retention. The property owner or the HOA must maintain all retention systems annually.
K. The Town periodically may inspect storm water detention and drainage facilities to verify that the detention and drainage facilities are operational and are being maintained. Final plats, covenants, conditions, and restrictions (CC&Rs), and development plans shall include a special note stating that (1) the owner(s)/homeowners’ association shall be solely responsible for the operation, maintenance, inspection, certification, general liability and premises liability of all storm water detention facilities; and (2) the Town of Pinetop-Lakeside shall have the right of ingress and egress to storm water detention and drainage facilities in perpetuity to inspect and verify good operation and maintenance of those facilities. (Ord. 23-462 § 1; Res. 23-1664 (Exh. A); Ord. 08-318 § 2)
15.08.050 Storm water detention systems which are not permitted.
A. The use of pavement parking lot storage as a primary detention facility is not permitted.
B. Building rooftop detention storage is not permitted.
C. Individual on-lot storage systems within single-family residential developments are not permitted. (Ord. 23-462 § 1; Res. 23-1664 (Exh. A); Ord. 08-318 § 2)
15.08.060 Additional requirements for subdivisions.
A. All subdivisions (see Town Code Chapter 16.12) greater than fifty (50) lots or larger than five (5) acres located in a United States Federal Emergency Management Agency ("FEMA") designated Unnumbered Zone A must provide base flood elevation and floodway delineation data.
B. All subdivisions within riverine environments with a contributing watershed of one-fourth (1/4) square mile or more must provide base flood elevation and floodway data in accordance with the criteria set forth on Arizona Department of Water Resources State Standards or other generally accepted criteria or methods approved by the Town Engineer.
C. All final plats within a FEMA one hundred (100) year (one (1%) percent chance) floodplain must show the one hundred (100) year (one (1%) percent chance) base flood elevations, surveyable floodplain limits, finish floor elevations, including basements, a minimum of one (1) foot above the base flood elevations and appropriate erosion hazard setbacks.
D. A Storm Water Pollution Prevention Plan ("SWPPP") shall be required of any subdivision, development, or construction project if required to do so in compliance with Arizona Department of Environmental Quality ("ADEQ") or federal Environmental Protection Agency ("EPA") regulations. In addition, a copy of the Notice of Intent ("NOI") filed with ADEQ shall be provided to the Town, prior to any construction, and a copy of the Notice of Termination ("NOT") filed with ADEQ shall be provided to the Town after construction has been completed.
E. Any development or project which infringes on the "Waters of the United States," as defined by Section 404 of the Federal Clean Water Act, shall require a summary report, describing any encroachments and requirements for permits (nationwide or specific) as outlined by the Army Corps of Engineers, prepared by an qualified consultant or by the Army Corps of Engineers and submitted to the Town. If a specific permit or an Army Corps of Engineers Letter of Determination is required, the owner or developer shall provide copies of the specific permit or Letter of Determination, or other evidence of same satisfactory to the Town prior to the issuance of a building permit.
F. Any development or project which encroaches into a defined Flood Hazard Area, as defined by FEMA, shall prepare and submit the necessary letters of map revision ("CLOMR" or "LOMR") to FEMA if required by the Town Engineer.
G. No subdivision, development or project will be permitted within a defined floodway as defined by FEMA. (Ord. 08-318 § 2)
15.08.070 Additional requirements for preliminary plat submittals.
A preliminary drainage report showing all storm water detention facilities and other drainage facilities shall be submitted at the time of preliminary plat submission for staff review and approval and in addition should include preliminary calculations for the one hundred (100) year (one (1%) percent chance) storm water flow. The preliminary drainage report shall also show the FEMA floodplain when applicable. The preliminary drainage report shall be prepared and sealed by a registered professional engineer licensed to practice in the State of Arizona. (Ord. 08-318 § 2)
15.08.080 Additional requirements for final plat submittals.
A. All final plats must show the one hundred (100) year (one (1%) percent chance) base flood elevations, surveyable floodplain limits, finish floor elevations a minimum of one (1) foot above the base flood elevations, and appropriate erosion hazard setbacks for all drainage areas with one hundred (100) year (one (1%) percent chance) flow equal to or greater than fifty cubic feet per second (50 c.f.s.).
B. A final drainage report shall be submitted at the time of final plat submission.
C. Floodplain studies may also be required as a part of the final drainage report by the Town Engineer for a Conditional Letter of Map Amendment ("CLOMA") or a Conditional Letter of Map Revision on Fill ("CLOMR-F"). (Ord. 08-318 § 2)
15.08.090 Erosion hazard and building setbacks from watercourses.
A. The hazards associated with flooding natural or unlined artificial channels include erosion of the channel banks, which may occur over a long period of time or during a single storm event. This can present a danger to adjacent structures or other development as the channel banks erode or migrate. In addition to other applicable setback requirements in the Town Zoning Regulations (see Town Code Title 17) and the Town Building Code (see Town Code Title 15), erosion hazard and building setbacks approved by the Town Engineer shall be provided for all construction, subdivisions, and development adjacent to natural watercourses or unlined, engineered open water channels in order to protect structures from potential damage.
B. All new buildings or structures constructed adjacent to a natural watercourse or an unprotected engineered channel located within Town of Pinetop-Lakeside shall be set back from the channel top of bank a sufficient distance in order to protect the structure from erosion of the channel banks and to allow for maintenance access and buffer.
C. The setback shall be measured from the top edge of the highest channel bank with the minimum setback being twenty (20) feet to allow for access and maintenance considerations. There will be watercourses with greater flows that will require setbacks greater than twenty (20) feet. The lowest floor elevation of any structure adjacent to a channel shall be set a minimum of one (1) foot above the one hundred (100) year (one (1%) percent chance) water surface in the channel. Exceptions or reductions of the building setback requirements may be granted by the Town Engineer if it can be demonstrated that adequate erosion and flow velocity protection can and will be constructed. All requests and plans for exception or reduction of setback requirements must be accompanied by detailed soil-stability and/or sediment transport studies approved by the Town Engineer. Requests for reduction of the minimum building hazard setbacks must take access and maintenance into consideration.
D. A slope-stability analysis of the channel may be required by the Town Engineer if conditions exist which indicate that the channel bank may be or may become unstable.
E. Natural vegetation is not an acceptable means of bank stabilization for the purpose of reducing building setbacks. Vegetation should be used along watercourses where flow velocities are less than five (5) feet per second during the one hundred (100) year (one (1%) percent chance) discharge, and an acceptable seeding and maintenance program shall be established. (Ord. 08-318 § 2)
15.08.100 Minimum elevation of lowest finished floor for residential construction.
The determination of the minimum elevation of the lowest finished floor shall be made by the Community Development Director on a site-specific basis. This requirement may be waived for existing residential structures where an addition is being added to the home. However, in general, if the height of the top of the stem wall is lower than the crown of the nearest road to any corner of the building, the lowest finished floor must be eighteen (18) inches above the highest point of the finished dirt grade adjacent to the building homesite. Any parcel with the lowest finished floor elevation higher than the nearest road at the crown must be elevated twelve (12) inches above the highest point of finished dirt grade adjacent to building. Sub grade construction will have an International Residential Code (IRC) approved water barrier applied up to twelve (12) inches above grade. All other construction will be elevated as required by the IRC, or as required by this chapter. (Ord. 21-443 § 1)