Exh 7AAGENDA ITEM #7A
MARCH 10, 2003
CITY OF ATLANTIC BEACH
CITY COMMISSION MEETING
5 T Ar'F REPORT
AGENDA ITEM: Code Revisions for Stormwater Management
SUBMITTED BY: Robert S. Kosoy, P.E.
Director of Public Works
llA 1'1EJ: March 3, 2003
BACKGROUND: The proposed revisions to Chapter 24 of the City Code for
stormwater management were presented to the City Commission
for a first reading on February 24, 2003. During this meeting, the
Commission requested that provisions be added to allow a waiver
of the proposed requirements under unusual circumstances and to
provide enforcement capabilities for the proposed requirements.
In response to these requests, a line was added to the end of item 2,
On-Site Storage, stating that "The requirement for on-site storage
may be waived by the Director of Public Works if storage is
deemed to be unnecessary." In addition, item 6 was added stating
that "Enforcement: Subsequent to approval of a property owner's
final grading, including on-site storage and stormwater treatment,
the improvements shall be maintained by the property owner.
Failure to maintain the improvements will require restoration,
upon notification by the Director of Public Works, within a
stipulated timeframe. If restoration is not completed, a lien may
be placed on the property for the estimated cost of the restoration
or further action may be recommended by the Code Enforcement
Board."
On February 28, 2003, the FDEP notified us that NPDES
requirements for projects of one acre or more would not go into
effect until May 1, 2003 (previously April 1, 2003). This change
was made to item 5.
RECOMMENDATION: Approve proposed Code changes to Chapter 24.
ATTACHMENTS: Proposed Code Changes.
REVIEWED BY CITY
AGENDA ITEM #7A
MARCH 10, 2003
CITY OF ATLANTIC BEACH, FLORIDA
ORDINANCE NO. 90-03-180
AN ORDINANCE OF THE CITY OF ATLANTIC BEACH, FLORIDA,
AMENDING CHAPTER 24, ZONING, SUBDIVISION AND LAND
DEVELOPMENT REGULATIONS, TO ESTABLISH STORMWATER ON-SITE
STORAGE REQUIREMENTS AND TREATMENT, FLOODPLAIN STORAGE,
AND NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
(NDPES) REQUIREMENTS, AND PROVIDING AN EFFECTIVE DATE
BE IT ENACTED BY THE CITY COMMISSION ON BEHALF OF THE PEOPLE OF
THE CITY OF ATLANTIC BEACH, FLORIDA:
Section 24-67. Development review and issuances of development Hermits; revise (d)
Stormwater drainage requirements, to read:
(d) Stormwater drainage, storage and treatment requirements.
1. Topog_ra~hxand Grading: All lots and development sites shall be constructed and
graded in such a manner so that the Stormwater drains to the adjacent street, an existing natural
element used to convey Stormwater (See section 22-303, definitions: Stormwater management
system), or a city drainage structure after meeting on-site storage requirements, as listed in this
Section. The city shall be provided with apre-construction topographical survey prior to the
issuance of a development permit and apost-construction topographical survey prior to the
issuance of a certificate of occupancy. The surveys shall be prepared by a licensed Florida
surveyor, and the requirement for either or both surveys may be waived by the Director of Public
Works if they are determined to be unnecessary.
2. On-Site Storage: The applicant will be required to provide on-site storage, such that
there is no increase in the rate or volume of flow to off-site, from every developed or
redeveloped parcel, and provide documentations and calculations to demonstrate compliance.
Subdivisions and developments previously permitted by the St. Johns River Water Mana eg_ment
District (SJRWNIDI, and have an in-compliance retention/detention system that collects and
controls run-off, are exempt. The requirement for on-site stora a may be waived by the. Director
of Public Works if storage is determined to be unnecessary or unattainable.
Volume calculations for lots that require on-site storage should be based on the difference
in run-off volume generated by the new impervious area ("delta volume"1 and would be
calculated bv:
V=CAR/12, where
V =volume of storage in cubic feet,
A =area of the lot in square feet,
R = 25 year and 24 hour rainfall depth (9.3 inches) over the lot area, and
C =run-off coefficient, which is 0.6 for the 50% maximum imperviousness 0 4 for 25%
imperviousness, and 0.2 for 0% imperviousness.
AGENDA ITEM #7A
MARCH 10, 2003
This delta volume (post V minus pre V in cubic feet) must be stored at least 1 foot above
the wet season water table and below the overflow point to off-site (in many cases this may be
the adjacent road elevation. As an option, and as approved by the Director of Public Works, the
owner of the parcel to be developed or redeveloped ma~plement, at the applicant's cost, off-
site storage and necessarX conveyance to control existing flood stages off-site.
3. Flood Plain Storage: There shall be no net loss of storage for azeas in the 100-~eaz
floodplain, where a floodQlain elevation has been defined by either the Federal Emergency
Management Agencv~FEMA) on Flood Insurance Rate Maps (FIRMs), the 1995 Stormwater
Master Plan, the Core Citesproject, or the 2002 Stormwater Master Plan Update (e.~., Hopkins
Creek . Site rg ading shall create storage on-site to mitigate for filling of volume on-site. This
storage is in addition to the storage required for the increase in impervious azea.
4. Stormwater Treatment: Stormwater treatment shall be provided for a volume
equivalent to either retention or detention with filtration, of the run-off from the first one (1) inch
of rainfall; or as an option, for facilities with a drainage area of less than one hundred (100
acres, the first one-half (1/2) inch ofrun-offpursuant to Chapter 62-25, Florida Administrative
Code (FAC). No dichazge from any stormwater facility shall cause or contribute to a violation
of water quality standazds as provided in Section 62.302 of the Florida Administrative Code.
This treatment volume can be included as part of the on-site storage requirement in item d (2) of
this Section.
5. NPDES RecLuirements: All construction activities shall be in conformance with the
City's National Pollutant Discharge Elimination Systems (NPDES2permit in addition to the
r~uirements of the Water Management District and the Florida Department of Environmental
Protection. NPDES requirements include use of Best Management Practices (BMPs~prior to
"~ dischaz~e into natural or artificial drainage systems. Beginning May 1 2003 all construction
projects of one acre or more will require a NPDES permit.
6. Enforcement: Subsequent to approval of a property owner's final rg ading including
on-site and/or flood plain storage and stormwater treatment the improvements shall be
maintained by the property owner. Failure to maintain the improvements will require restoration
upon notification by the Director of Public Works. within a stipulated timeframe If restoration
is not completed, a lien mawplaced on the property for the estimated cost of the restoration
and administrative fees or further action may be recommended by the Code Enforcement Board
This ordinance shall take effect immediately upon its final passage and adoption.
Passed by the City Commission on first reading this day of ,
2003. Passed by the City Commission on the second and final reading this day of
2003.
ATTEST:
Maureen King
City Clerk
John S. Meserve
Mayor, Presiding Officer
Alan C. Jensen, Esquire
City Attorney