Exh 8DAGENDA ITEM #8D
NOVEMBER 14, 2005
CITY OF ATLANTIC BEACH
CITY COMMISSION MEETING
STAFF REPORT
AGENDA ITEM: Request for a Waiver from Land Development Regulations
Requirement for On- Site Retention for a lot located at 1718 Selva
Marina Drive
SUBMITTED BY: Rick Carper, P.E., Public Works Director
DATE: October 26, 2005
BACKGROUND: Land Development Regulations (LDR) Section 24-66(b) requires on-
site storage of stormwater runoff "such that there is no increase in the
rate or volume of flow to off-site, from every developed or
' redeveloped Parcel" (emphasis added). The property owner is
requesting a waiver from on-site retention requirements by saying the
LDR should not be applied to a new home within an already existing
" subdivision, stating the regulation "applies only to subdivisions and
not to individual lots". As noted, Section 24-66(b) specifically applies
to both development and redevelopment at the Parce{ (lot) level.
Although the Selva Marina Subdivision is nearly built out, the lot in
question was undeveloped at the time of the permit request. The
intent of LDR Section 24-fifi(b) is to ensure the capacity of existing
stormwater collection systems is not exceeded because of the
increase in stormwater runoff caused by the increased impervious
areas resulting from both development (new construction) and from
redevelopment (tear downs). That the property is being built to less
than 50% impervious simply means it is complying with another
section of the City's LDR (Section 24-104 (f)), unrelated to on-site
retention. ~ ~ ~ ~ ~~
Public Works approved the Building permit request for property at
1718 Selva Marina Drive on May 27, 2005. At that time, Public Works
had conducted several plan reviews with the Builder (Game)
Construction) to obtain a plan for on-site retention that met the spirit
of the City's Land Development Regulations. Because the lot has
natural Type B drainage (splits front and rear), Staff agreed that the
. portion of the lot draining directly to the lagoon would not be
considered in the retention calculations. The front half of the lot
drains to Selva Marina Drive, with an existing City catch b"asin at the
curb. This curb inlet is piped directly to Selva Lagoon along Mr.
Fitzgera(d's northern property line. Combined with flowfrom the inlets
immediately across Selva Marine Drive, this 18" pipe carries runoff
from approximately 700 linear feet of Selva Marina Drive, over 900
• AGENDA ITEM #8D
NOVEMBER 14, 2005
• feet of Live Oak Lane and 500 feet of the north side of Palmwood
• Drive and all the properties adjacent to these roads.
. As a result of an Administrative oversight, Staff is unable to find the
permitted drainage plan and approved on-site retention calculations
for this property. Staff requested a copy from the Builder who stated
he did not have them either. However, the portion of the lot draining
directly to the lagoon was taken into account when the amount of on-
site storage required was calculated.
RECOMMENDATION: Staff recommends disapproval of the waiver request. LDR
Section 24-66(b) gives the Director of Public Works authority to waive
on-site retention "if storage is determined to be unnecessary or
unattainable". In this case, Staff feels it is both necessary and
attainable, and that to grant the waiver would set a dangerous
precedent for the City.
ATTACHMENTS: 1) Waiver Request from Joseph Fitzgerald, 1718 Selva Marina Drive
2) COAB Land Development Regulations, Section 24-66
3) Required retention volume calculation worksheet
4) Site Plan -•1718 Selva Marina Drive
BUDGET: No budget issues.
REVIEWED BY CITY MANAG
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AGENDA ITEM #8D
NOVEMBER 14, 2005
City of Atlantic Beach
City Commission Meeting
Agenda Item: Request for a waiver for my property (1718 Selva Marina Dr.)
regarding Regulation -Atlantic Beach Zoning, Subdivision and Land Development
Regulations, Section 24-66(b).
Present Situation: Upon applying for a building permit for my new home, Mr. Rick
Carper, P.E. Public Works Director used section 24-66(b) of the above regulation to
calculate the volume of run off and storage requirements for my individual lot at 1718
Selva Marina Dr. The results from the calculation required 3,740 cu. ft. of storage. After
discussion with my builder, Mr. Frank Gamel, Mr. Carper reduced the requirement to
2,500 cu. ft. between the house and the road (see attached sheet A). Upon additional
discussion with Mr. Gamel, he agreed to a 6" birm to be constructed in the front of the
property to retain the water. Then the building permit was approved.
Waiver Request: I request that the Regulation of Atlantic Beach, Subdivision and
Land Development, Section 24-66(b) not be applied to my property on 1718 Selva
Marina Dr.
Reasons: I do not believe that an individual lot, within an established
community should be required to comply with a regulation that has as its intent to cover a
Subdivision and Land Development situation. Selva Marina was developed in the 1960's
and constructed the water management system for the subdivision for all the homes at
that time. If the present thinking of the requirement fora 25 year and 24 hour rainfall (9.3
inches) has changed since then, applying this regulation to the two remaining properties
on the street, which do not have homes on them, (2 homes out of 40 - 5%) would have a
small impact on the water management situation. Certainly, there would not be enough
impact to correct the situation if the system is now defined to be unable to handle the
situation in its present condition.
I dnn't believe the regulation is being applied to homes which are being rebuilt or under
going renovations.
Reasoning: The last 40 feet of my property is located in the canal which is used
as the water management system for the subdivision. Therefore, 16 % of the total
property is being used for the system presently. (150 ft. X 250 ft. = 37,500 sq. ft. & 40 ft.
X 150 ft. = 6000 sq. ft.) Also, on the North East corner of the lot, which is in the street,
there is a storm water drain which collects the water in to a buried 3 ft. corrugated steel
pipe draining under the property into the canal in the rear of the home. I feel that I am
already contributing to the water management of the community.
Reasoning (cont.): The front of the property (home to property line is 75 ft X 150 ft.)
is 11,250 sq. ft. If the initial calculation of a storage requirement (3,740 cu. ft.) were to
AGIJNDA IT1;NI #SD
NOVIJNIBER 14, 2005
apply and the depth were'/z ft. then two thirds of the front yard would be a holding pond.
Also, I followed the regulation regarding the tree retention regulations and to follow this
water retention approach the trees in the holding pond area would be affected negatively.
Summary: The existing regulation, (section 24-66 b) applies only to
subdivisions and not to individual lots.
Our building plans and specs do not in any way violate the
impervious surface area limit of 50% which was established in November of 2001.
In addition, the last 40 feet of our lot is in the canal, part of the
existing storm water management system. Therefore we already have a storm water
management system on our lot.
The fact that Mr. Carper reduced the requirement indicates that he
also believes that the resulting calculation is too much for an individual lot.
Mr. Frank Gamel, my construction manager, and an active builder
for the last 25 years at the beaches, has also indicated that he has never seen this kind of
approach to an individual lot.
Section 24-46(d) permits the commission to authorize limited
waivers on a case by case basis, from specific provisions of the land development
regulations when it is demonstrated that compliance with such provision would be
unreasonable, in conflict with the public interest, or a practical impossibility.
Regards,
Joseph Fitzgerald
AGENDA ITEM #SD
NOVEMBER 14, 200
Sec. 24-66. Stormwater, Drainage, Storage and Treatment Requirements.
(Emphasis added)
(al, Topography and 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 within this Section. The City shall be provided with a
pre-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. Said 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 determined to be unnecessary.
(b) On-Site Storage: The Applicant shall 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. Development Projects previously permitted by the St. Johns
River Water Management District (SJRWMD), which have an in-compliance
retention or detention system that collects and controls run-off, are exempt. The
requirement for on-site storage 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")
and would be calculated by:
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.
" ' This delta volume (post V minus pre V in cubic feet) must be stored zt 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
may implement, at the applicant's cost, off-site storage and necessary conveyance to
control existing flood stages off-site.
(c) Flood Plain Storage: There shall be no net loss of storage for areas in the 100-year
floodplain, where a floodplain elevation has been defined by either the Federal
Emergency Management Agency (FEMA) on Flood Insurance Rate Maps (FIRMS),
the 1995 Stormwater Master Plan, the Core City project, or the 2002 Stormwater
Master Plan Update (e.g., Hopkins Creek). Site grading 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 Surface Area.
AGIrNDA ITIJNI #8D
NOVIrMBIJR 14, 200
(d) 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 of run-off pursuant to Chapter
62-25, Florida Administrative Code (FAC). No discharge from any stormwater
facility shall cause or contribute to a violation of water quality standards 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.
(e) NPDES Requirements: All construction activities shall be in conformance with the
City's National Pollutant Discharge Elimination Systems (NPDES) permit, in
addition to the requirements of the Water Management District and the Florida
Department of Environmental Protection. NPDES requirements include use of Best
Management Practices (BMPs) prior to discharge into natural or artificial drainage
systems. Beginning May 1, 2003, all construction projects of one acre or more will
• require a NPDES permit.
(f) Enforcement: Subsequent to approval of a property owner's final grading, 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 time frame. If restoration is not timely completed, the City shall have the
right to complete the restoration, and -the City's actual cost incurred, together with a
charge of 100% of said costs to cover the City's administrative expenses, shall be
charged to the owner.
AGENDA ITEA'I #SD
NOVEMBER 14, 2005
Runoff Volume Calculations (Ref City of Atlantic Beach Zoning, Subdivision and
Land Development Regulations, Section 24-66(b): 1718 Selva Marina Drive
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") and would be calculated by:
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 impervious coverage, 0.4 for 25%
impervious coverage, and D.2 for 0% impervious coverage.
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 maybe 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 may implement, at the applicant's cost, off-site storage and necessary
conveyance to control existing flood stages off-site.
Calculation: 1/2 total lot size due to type Bdrainage - 38484/2 = 17,424 ftz
PredeveloQment:
Runoff Volume = 0.2 (no impervious surface) * 17,424 ft2 *9.3 in./12in./ft
V = 2700 ft'
Post development:
Runoff Volume = 0.6 (50% impervious surface) * 17,424 ftZ *9.3 in./12in./ft
' V = 8102 ft3
Delta Volume = 8102 ft3 - 2700 ft3 - 5402 ft3 (This is the volume of storage that must be provided
for this lot, either on the building site, or with Public Works approval, offsite).
Required Documentation: Include a block or section on the Paving and Drainage Plan showing the
requirement and amount of storage provided. (See example below)
Stormwater Stora a Re uirements
Area Percent Im ervious Runoff Volume
Predevelo went Ft Ft
Post Develo ment F Ft
Stora a Volume Re wired: Ft
Stora a Volume Provided: F
AGENDA ITEM #SD
NOVEMBER 14, 2005
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