HomeMy WebLinkAboutLand Development Code§ 54-3-12.4 SEBASTIAN LAND DEVELOPMENT CODE
which meets the requirements of the city's standard specifications for the construction of
public facilities and physical improvements shall be presumed not to impede the functioning
of the drainage system.
Sec. 54-3-12.5. Exemptions.
The following activities shall be exempt from the surface water management permitting
requirements herein established:
(a) Any maintenance, alteration, renewal, repair, use or improvement of an existing
structure which does not change or affect the rate or volume of stormwater runoff, or
the construction of any structure or addition thereto which does not create an
impervious surface exceeding ten percent of the site or 5,000 square feet, whichever is
less.
(b) Any activity or development project which is demonstrated by the applicant to have
vested rights.
(c) All activities undertaken by a governmental agency within their respective easements
and rights -of -ways. These surface water management policies shall not be construed to
prevent the committing of any act otherwise lawful and necessary to prevent material
harm to or destruction of real or personal property as a result of a present emergency,
including but not limited to fire, infestation by pests, or hazards resulting from violent
storms or hurricanes or when the property is in imminent peril and the necessity of
obtaining a permit is impractical and would cause undue hardship in the protection of
the property.
(d) A report of any such emergency action shall be made to. the city engineer by the owner
or person in control of the property upon which emergency action was taken as soon as
practicable, but not more than ten days following such action. Remedial action may be
required by the city engineer, subject to appeal to the city council in the event of
dispute.
Sec. 54-3.12.6. Single-family drainage, stormwater management.
Drainage and flood protection regulations are applied to the construction of single-family
and duplex homes. In newer subdivisions complete drainage systems have been constructed to
address most, if not all, drainage concerns. Nonetheless, lots must be filled and graded in a
manner to meet other requirements including the standards for septic tanks. The following
drainage, stormwater management, and flood protection regulations apply to single-family
and duplex homes.
(a) Flood protection. Prior to constructing a single-family home or duplex on a parcel in a
flood hazard zone, a Type "C" stormwater management permit shall be obtained from
the city engineer. The city engineer shall approve any revisions to the approved permit.
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SURFACE WATER MANAGEMENT § 54-3-12.8
(b) Drainage and stormwater management. Prior to constructing a single-family home or
duplex on a parcel not in a flood hazard zone, a Type "D" (known as a drainage permit)
stormwater management permit shall be obtained from the city engineer. The city
engineer shall approve any revisions to the approved permit.
No certificates of occupancy shall be issued until a functional drainage system has
been constructed and approved by the city engineer. The city engineer may require the
construction of retaining walls, roof gutters, underdrains, or other facilities deemed
necessary to provide adequate drainage.
Sec. 54-3-12.7. Commercial, industrial or institutional sites with less than 5,000
square feet impervious surface drainage, stormwater management.
Drainage and flood protection regulations are applied to the construction of commercial,
industrial or institutional sites. Lots may need to be filled and graded in a manner to meet
various requirements. The following drainage, stormwater management, and flood protection
regulations apply to commercial, industrial or institutional sites that have less than 5,000
square feet of impervious surface.
(a) Flood protection. For each commercial, industrial or institutional facility located in a
flood hazard zone, the site plan approval application shall include an application for a
Type "B" stormwater management permit. The city engineer shall approve any
revisions to the approved permit.
(b) Drainage and stormwater management. For each commercial, industrial or institu-
tional facility not located in a flood hazard zone, the site plan approval application
shall include an application for a Type "A" stormwater management permit. The city
engineer may waive any of the requirements of section 54-3-12.10, if the city engineer
determines that such requirements are unnecessary. The Type "A" stormwater
management permit shall be approved by the city engineer prior to the issuance of a
land clearing or building permit. The city engineer shall approve any revisions to the
approved conceptual plan.
No certificates of occupancy shall be issued until a functional drainage system has
been constructed and approved by the city engineer. The city engineer may require the
construction of retaining walls, roof gutters, underdrains, or other facilities deemed
necessary to provide adequate drainage.
Sec. 54-3.12.8. Commerical, industrial, or institutional sites with 5,000 square feet
or more impervious surface drainage, stormwater management.
Drainage and flood protection regulations are applied to the construction of commercial,
industrial or institutional sites. Lots may need to be filled and graded in a manner to meet
various requirements. The following drainage, stormwater management, and flood protection
regulations apply to commercial, industrial or institutional sites which have 5,000 square feet
or more of impervious surface.
(a) Flood protection. For each commercial, industrial or institutional facility located in a
flood hazard zone, the site plan approval application shall include an application for a
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§ 54-3-12.5 SEBASTIAN LAND DEVELOPMENT CODE
Type "B" stormwater management permit. Site plan approval and a Type "B" permit
shall be issued prior to the issuance of a land clearing or building permit. The city
engineer shall approve any revisions to the approved permit.
(b) Drainage and stormwater management. For each commercial, industrial or institu-
tional facility not located in a flood hazard zone, the site plan approval application
shall include an application for a Type "A" stormwater management permit. Prior to
the issuance of a Type "A" permit, the project's engineer of record shall certify that the
plans submitted to the city are the same as the drainage and stormwater management
plans approved by the St. Johns River Water Management District (S.J.R.WM.D.) or
the department of environmental protection. Site plan approval and a Type "A" permit
shall be issued prior to the issuance of a land clearing or building permit. The city
engineer shall approve any revisions to the approved permit.
No certificates of occupancy shall be issued until a functional drainage system has
been constructed and approved by the city engineer. The city engineer may require the
construction of retaining walls, roof gutters, underdrains, or other facilities deemed
necessary to provide adequate drainage.
Sec. 54-3-12.9. Subdivision developments, drainage and stormwater management.
(a) Flood protection. For each subdivision where a portion of the site is determined to be in
a flood hazard zone, a Type "B" permit shall be obtained prior to the approval of a construction
permit. The Type "B" permit shall be consistent with the approved preliminary plat. The city
engineer shall approve any revisions to the approved permit.
(b) Drainage and stormwater management. Each subdivision not located in a flood hazard
zone shall obtain a Type "A" stormwater management permit. A Type "A" permit shall be
issued prior to the issuance of a construction permit. The city engineer shall approve any
revisions to the approved permit.
Sec. 54-3-12.10. Type "A" permit, stormwater management (drainage), commercial
subdivisions.
(a) Criteria. No Type "A" permit shall be issued unless the following criteria are met:
(1) Design storm. The design of the on-site stormwater management system shall be
based at a minimum on a 25 -year frequency, 24-hour duration storm event. The design
of any off-site stormwater management system improvements shall be based upon a
25 -year frequency, 24-hour duration storm event. The modified Type 2 SCS rainfall
distribution shall be used. Post development runoff shall not exceed pre -development
runoff.
(2) One or more elevation benchmarks NGVD (1929) must be established or referenced.
The stormwater system is to be designed utilizing the benchmarks.
(3) The hydrologic computations for the stormwater management system shall be based
on full hydrograph generation for the development project and contributory area
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SURFACE WATER MANAGEMENT § 54-3-12.10
utilizing such methods as published by the National Resources Conservation Service
(NRCS) (U.S. Department of Agriculture, SCS "Natural Engineering Handbook,"
Section 4, Hydrology: 1985, and "Urban Hydrology for Small Watersheds," Technical
Release No. 55: 1986). For projects of less than 12.00 acres, the rational method of
runoff computation is satisfactory. The rainfall intensity -duration curves provided in
Volume 2 - Procedures Florida Department of Transportation (FDOT) Drainage
Manual are hereby incorporated as part of this code and shall be used in making all
required hydrologic computations.
(4) Required retention. Retention or detention with filtration of the first one inch of
rainfall shall be provided on-site. Detention with filtration or retention shall be
provided on-site for the initial one inch of rainfall plus additional stormwater runoff
generated by the development project over and above that generated by the site prior
to the proposed development unless there is a legal positive outfall available which has
sufficient capacity to accept the additional runoff. All projects located east of the
Florida East Coast Railroad shall retain the first one and one-half inch of rainfall
on-site before discharge into a legal positive outfall or the Indian River.
(5) Retention or detention design criteria.
a. Retention or detention facilities shall be constructed in such a manner as to
maximize utilization of available percolation capabilities on the site for recharge
enhancement, to minimize mosquito breeding and shall be easy to maintain. All
detention facilities shall have a skimmer if required by SJRWMD.
b. Stormwater management systems that are to be dedicated to the city shall not
penetrate the seasonally high groundwater table.
C. Private wet retention/detention systems shall meet the following criteria:
1. The applicant provide a water quality certification from the St. Johns River
Water Management District or DEP that the direct connection to the
groundwater table, as proposed, will not significantly adversely affect the
quality of the groundwater. The issuance of a SRJWMD permit, exception,
or waiver shall be sufficient and conclusive that all water quality standards
are satisfied. If the site is below SJRWMD or DEP thresholds, the city
engineer can waive this certification.
2. The site is not located on a recharge area.
d. As the SJRWMD requirements for treatment are equal to, or more stringent than
the city s, the issuance to the applicant of an appropriate SJRWMD permit,
exemption, or waiver shall be sufficient to show that all water quality treatment
standards contained in this code are satisfied for Types A, B, and C permits. For
issuance of Type A, B, C, or D permit, the applicant must show adherence to other
sections of this code related to flood regulation, water runoff and quality
discharge regulation, and other appropriate regulations contained herein.
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(6) Legal positive outfall required. Discharges from the development project shall be
handled to a point of legal positive outfall. Tailwater stages of the receiving waters
must be taken into account in design.
(7) Dry detention discharge. The bottom of dry retention areas shall be sloped to form a
permanent drain. A detention area shall have an outlet device, and shall not be lower
than the elevation of the off-site receiving channel or water body unless protected by
a suitably designed flap gate.
(8) Open drainage ways. Where permitted, open drainage ways shall retain natural design
characteristics and be so designed and protected that they do not present a hazard to
life or property. The design shall include measures to protect against scour and erosion
and provide for stable side slopes. Whenever possible, such waterways shall provide for
adequate flushing action by prevailing winds and currents to assure the prevention of
stagnant water and debris accumulation.
(9) Disposition of stormwater runoff. The stormwater management system for develop-
ments located predominately on excessively drained soils should maximize stormwater
infiltration. This shall be accomplished through the use of bottomless inlets, perforated
pipe, grading to retard runoff, natural or artificial retention or detention basins, or
other methods depending on the characteristics of the land area. Specific guidelines
are as follows:
a. Areas and lots shall be developed to maximize the amount of natural rainfall that
is percolated into the soil and to minimize direct overland runoff into adjoining
streets and watercourses. Stormwater runoff from roofs and other impervious
surfaces should be diverted into swales, or terraces on the lot.
b. Street drainage shall be sodded swales or curb and gutter in accordance with city
specifications, provided all curb and gutter systems shall discharge or direct
water across a sodded swale area or other filtering medium.
C. Whenever practical, as indicated by soil characteristics, water table elevation,
and topography, the overflow from any swale used shall be diverted to percolation
areas, ponding areas, or natural or artificial seepage basins of sufficient capacity
to retain and provide for the maximum infiltration of stormwater runoff from
each drainage area for the design storm.
d. Whenever practical, except in those development projects where temporary
ponding is allowable, each percolation or retention area shall include positive
drainage facilities which provide for drainage to public outfalls or a lake, or
watercourse, to handle the runoff from storms of longer duration and severity
than the design storm.
e. The area surrounding a retention or detention basin is recommended to be used
as private or public open space and shall be grassed unless the slopes exceed four
to one which would require sod.
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SURFACE WATER MANAGEMENT § 54-3-12.10
f. The Soil Survey of Indian River County published by the U.S. Department of
Agriculture, Soil Conservation Service: 1987, shall be the document to determine
soil classifications. Such soil classification may be modified by on-site testing and
engineering evaluation.
g. Flood routing analysis for all new local road facilities shall show that the water
elevation shall at no time during the design storm duration exceed an elevation
that would:
1. Permit floodwater encroachment outside existing drainage easements or
right-of-way for a three-year/24-hour duration storm.
2. Place more than 20% of the front yard or rear yard area below floodwater
elevation any time during a ten-year/24-hour duration storm.
3. Exceed two inches above the lowest elevation on the centerline profile of the
roadway for a 25-year/24-hour duration storm.
4. Exceed the finished -floor elevation of any structure for a 100-year/three-day
duration storm for projects located in a flood hazard area.
h. All new stormwater discharging into any canal or receiving water body shall be
designed to convey the permitted discharge after tailwater conditions are
considered.
i. All bridges shall be designed to pass the 100-year/three-day duration storm
event.
j. All drainage easements shall a sod e '
(10) Material specifications for culverts and storm sewers. The following pipe materials are
acceptable:
a. Reinforced concrete pipe; aluminum pipe; aluminum pipe arch; or HDPE. Other
pipe material may be used if approved for the intended use by the Florida
Department of Transportation (FDOT). In private systems, bituminous -coated
steel may be acceptable as determined by the city engineer.
b. Workmanship and pipe materials shall conform to FDOT Standard Specifica-
tions, latest edition.
C. FDOT approved pipe material shall be used under city right-of-way pavement
and/or into salt water outfalls. Concrete for reinforced concrete box culverts shall
conform to FDOT's Standard Specifications, latest edition.
(11) Inlets. Design and spacing of inlets shall be in accordance with FDOT's Standard
Specifications or the city's standard specifications.
(12) Drainage structures. All cross drains, driveway culverts, and storm sewers shall have
headwalls, flared -end sections, mitered end sections or terminating structures in
accordance with city standard specifications or FDOT's Standard Specifications, latest
edition. Endwalls, inlets, or other appropriate terminating and intermediate struc-
tures, and backflow devices may be required where necessary. Exfiltration systems
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